Source: http://www.allindianpatents.com/patents/197151-an-injection-stretch-blow-molding-method-for-blow-molding-containers-from-preforms
Timestamp: 2019-05-19 10:33:05
Document Index: 275033258

Matched Legal Cases: ['art 214', 'art 218', 'art 214', 'art 218', 'art 214', 'art 218', 'art 214', 'art 214', 'art 214', 'art 218', 'art 218', 'art 214', 'art 218', 'art\n218', 'art 214', 'art 218', 'art 218', 'art 214', 'art 218', 'art 218', 'art 214', 'art 218', 'art 214', 'art 218', 'art 218', 'art 214', 'art 218', 'art 218', 'art 218', 'art 332']

Indian Patents. 197151:AN INJECTION STRETCH BLOW MOLDING METHOD FOR BLOW MOLDING CONTAINERS FROM PREFORMS
AN INJECTION STRETCH BLOW MOLDING METHOD FOR BLOW MOLDING CONTAINERS FROM PREFORMS
An injection stretch blow molding method for blow molding containers from preforms retaining heat from when the preforms were injection molded, comprising the steps of: releasing the preforms, molded using at least an injection core mold and an injection cavity mold, from the injection cavity mold; with the preforms held by the injection core mold, carrying the injection core mold to an ejecting section along a first carrying path at a first pitch (PI) while the preforms are cooled by the injection core mold; in the ejecting section, ejecting the preforms by releasing from the injection core mold;
The present invention relates to an injection stretch blow molding method for blow molding containers from preforms
The present invention is a divisional out of Indian Patent No 191081 (formerly IP 341/DEL/95)
This invention relates to an injection stretch blow molding apparatus and method wherein containers are stretch blow molded from preforms retaining heat from when they were injection molded This invention also relates to an injection stretch blow molding apparatus and method wherein N (N>2) preforms are simultaneously injection molded and n (N>N) preforms among these are simultaneously blow molded into n containers More particularly, the invention relates to an injection stretch blow molding apparatus and method with which while ample cooling time is provided the preforms can be molded with a shortened injection molding cycle time and furthermore the operation rate of the blow cavities can be increased Also, this invention relates to constructions and methods for heating and adjusting the temperature of the preforms before they are blow molded Also, this invention relates to an injection stretch blow molding apparatus and method with which it is possible when necessary to discharge the preforms to outside the apparatus instead of carrying them to the blow molding section
Methods for blow molding a container from a preform (parison) include that known as the cold parison or 2-stage method and that which is known as the hot parison or 1-stage method In both these methods, for injection molding the preforms required for the blow molding, at least an injection cavity mold which shapes the outer wall of the preform and an injection core mold which shapes the inner wall of the preform
are necessary Also, after the injection cavity mold and the injection core mold are clamped together and the preform is injection molded, with the molds still clamped together it is necessary to cool the preform down to a temperature at which the preform can be released from the molds
Particularly in the case of the cold panson (2-stage) method, because this preform mold-release temperature has to be made quite low, the injection molding cycle time has been long and productivity has been poor This is because when the preform is ejected by the injection cavity mold and the injection core mold being released from the preform and the preform being dropped or the like, it is necessary for the preform to be cooled to a mold-release temperature low enough for the preform not to be deformed when it makes contact with other members
In the case of the cold panson method, because the preform molding step and the step in which a container is blow molded from this preform are completely release, the blow molding cycle time is not affected by the injection molding cycle time However, because the cold panson method involves reheating preforms which have been cooled to room temperature the cold panson method is inferior to the hot panson method in its energy efficiency
In a hot panson (1-stage) method injection stretch blow molding machine which draw blow molds bottles from preforms still containing heat from when they were injection molded the cycle time of the overall apparatus is determined by the injection molding cycle time, which of all the cycles is the one requiring the most time Consequently there has been the
problem that when the time required for injection molding is long, the throughput of the whole apparatus is low
In the case of the hot panson method, although the preform is mold-released at a higher temperature than in the cold panson method, there is a limit on this mold-release temperature and consequently it is not possible to greatly speed up the injection molding cycle One reason for this is that when the preform mold-release temperature is high, when the injection core mold is released from the preform, a mold-release called lifting, wherein the preform sticks to the core mold, occurs Also, after the injection core mold is released from the preform, because there is no longer any member restricting deformation of the preform, deformation caused by temperature nonumformity and thermal contraction and the like make it impossible for preforms conforming to the design to be ejected Furthermore, when the cooling effected by the injection core mold is inadequate, crystallization caused by inadequate cooling occurs, particularly at the inner wall of the preform, and a preform of which the trunk portion is opaque is ejected
Also, when preforms are ejected before they are completely cooled by the injection core mold and the injection cavity mold (with the preforms still at a temperature at which blow molding is possible) and blow molding is carried out thereafter, there have been the following problems
(A) Unless the internal pressure (injection sustain pressure) is raised, shrink marks form at the injection cavity mold side of the preform and a preform with a uniform temperature distribution cannot be obtained Consequently,
when this preform is blow molded, a molded product with a uniform wall thickness distribution cannot be obtained
high Consequently, when the preform is blow molded, a molded
cavity surface Because of this, there are some parts of the
becomes uneven As a result, when this preform is blow
Thus, in a conventional hot parison system, unless the preform is amply cooled by the injection cavity mold and the injection core mold it has not been possible to obtain good blowing characteristics or good bottle characteristics Because of this, the injection molding of the preforms has required time, and the throughput of the apparatus has been low
injection stretch blow molding machines using the hot panson method, including the following
When in order to increase the throughput the number N of preforms injection molded simultaneously is increased, the same number N of cavities conforming to the external shape of the bottles being manufactured have to be formed in the blow cavity mold Of the molds used in a blow molding machine the blow cavity mold is the most expensive, and the cost of this blow cavity mold increases roughly in proportion to the number of cavities in it Even if a mold is expensive, if its operation rate is high then it can be used cost-effectively, however, because as described above the cycle time of the overall apparatus depends on the injection molding cycle time and cannot be shortened, the operation rate of each cavity in the blow cavity mold has unavoidably been low Also, when the number of bottles blow molded simultaneously increases, not only the number of cavities in the blow mold but also the number of drawing rods and blow core molds and mechanisms for supporting and driving these increases, and this has resulted in increases in the size and cost of the apparatus
Another problem has been that conventionally it has not been possible to eject the preforms unless the injection core mold is completely pulled out of the preforms, and consequently with a rotary injection molding apparatus it has not been possible to carry the preforms from the injection molding section to the next stage When on the other hand the injection core mold is completely pulled out of the preforms, there has been the problem that this pullout stroke is long and the overall height of the apparatus is high
Another problem has been that when hot panson blow molding is earned out by a rotary earner type blow molding machine the injection molded preforms are always earned by the rotary earner to the blow molding section Here, for example when a problem has arisen in the blow molding section, there has been no alternative but to shut down the preform injection molding as well as the blow molding section However, once the injection molding section is shut down, a long starting-up time is required when it is restarted This is because the injection apparatus contains numerous resin-heating mechanisms in the hot runner mold and elsewhere
As a result, as well as it not being possible to raise the throughput of the overall apparatus, as described above, a lot of time is required for starting up the apparatus when a problem has arisen, and the productivity falls even further
Accordingly, it is an object of the invention to provide an injection stretch blow molding apparatus and method with which while ample preform cooling time is provided the injection molding cycle time can be shortened and the cycle time of the overall apparatus can thereby be shortened
Another object of the invention is to provide a highly efficient injection stretch blow molding apparatus and method with which while reducing costs by reducing the number of cavities in the blow mold the operation rate of the blow mold can be increased
Another object of the invention is to provide an injection stretch blow molding apparatus and method which while exploiting the heat energy efficiency of hot panson molding also has the preform temperature distribution
stability of the cold parison method
Another object of the invention is to pr injection stretch blow molding apparatus and method wnn which temperature nonumformity and deformation can be prevented even when the preform mold-release temperature at which the preforms are released from the injection cavity mold is made high and furthermore the preforms can be amply cooled before they are released from the injection core mold and can be stably blow molded thereafter at a suitable blow molding temperature
A further object of the invention is to provide an injection stretch blow molding apparatus and method with which the temperature difference between the inner and outer walls of the preforms is moderated before the preforms are blow molded
A further object of the invention is to provide an injection stretch blow molding apparatus with which general-purpose medium-sized containers of capacity 1 to 3 liters can be blow molded with high efficiency
A further object of the invention is to provide a blow molding apparatus with which it is possible to efficiently heat the regions below the necks of the preforms to a suitable blow molding temperature
A further object of the invention is to provide an injection stretch blow molding apparatus and method which can be started up without any wasteful blow molding being earned out at the time of start-up and with which it is not necessary to stop the operation of the whole apparatus when there is a problem in the blow molding section
An injection stretch blow molding apparatus according to the invention as set forth in claim 1 comprises
a blow molding station for stretch blow molding the preforms into containers, and
a circulatory carrier for intermittently circulatonly carrying along a carrying path a plurality of injection core molds disposed apart,
an injection molding section for injection molding the preforms having an injection cavity mold together with which the injection core molds, stopped in the carrying path, are severally clamped, and
an ejecting section for ejecting preforms from the injection core molds by releasing the injection core molds, stopped in the carrying path, and the preforms
An injection stretch blow molding method according to the invention as set forth in claim 7 for blow molding a container from a preform retaining heat from when it was injection molded comprises the steps of
releasing the preform, molded using at least an injection core mold and an injection cavity mold, from the injection cavity mold,
with the preform held by the injection core mold, carrying the injection core mold to an ejecting section along a carrying path while the preform is cooled by the injection core mold,
in the ejecting section, ejecting the preform by releasing the injection core mold therefrom, and
thereafter, blow molding a container from the preform retaining heat from when it was injection molded
According to the invention as set forth in claims 1 and 7, the preforms injection molded in the injection molding section are cooled by the injection cavity mold and the injection core mold and then the injection cavity mold only is released from the preforms After that, the preforms are earned to the preform ejecting section by the injection core mold The preforms are ejected after being cooled by the injection core mold during this carrying and in the preform ejecting section As a result, by the preforms being cooled by the injection core mold even after the injection cavity mold is mold-released in the injection molding section, ample preform cooling time is provided Therefore, the preform mold-release temperature at which the preforms are released from the injection cavity mold can be made high, the injection molding cycle time can thereby be shortened and the cycle time of the overall apparatus can be shortened Also, even when the preforms are released from the injection cavity mold at a high temperature, deformation of the preforms is prevented by
the injection core mold Furthermore, not only does the cooling efficiency increase because the preforms contract into contact with the injection core mold as they are cooled, and consequently crystallization and loss of transparency of the trunk portions of the preforms caused by inadequate cooling is prevented, but also by thus stabilizing the cooling process it is possible to stabilize the amount of heat retained by the preforms and thereby stabilize the wall thickness distributions of successively blow molded containers
An injection stretch blow molding apparatus according to the invention as set forth in claim 2 comprises
a first circulatory carrier for intermittently circulatonly carrying along a first carrying path a plurality of injection core molds disposed apart,
an injection molding section for simultaneously injection molding N (N>2) of the preforms having an injection cavity mold together with which the injection core molds, stopped in the first carrying path, are severally clamped, and
and the blow molding station comprises
a second circulatory earner for intermittently
circuiatoniy carrying along a second carrying path the preforms transferred from the preform molding station by the transfer station, and
a blow molding section for simultaneously blow molding n (1 An injection stretch blow molding method according to the invention as set forth in claim 8 for blow molding containers retaining heat from when they were injection molded comprises the steps of
releasing N (N>2) of the preforms, molded using at least an injection core mold and an injection cavity mold, from the injection cavity mold,
with the injection core mold still in the preforms, carrying the injection core mold to an ejecting section along a first circulatory carrying path while the preforms are cooled by the injection core mold,
in the ejecting section, ejecting the preforms by releasing the injection core mold therefrom,
transferring the ejected preforms to earner members carried along a second circulatory carrying path,
carrying the earner members supporting the preforms along the second carrying path to a blow molding section, and
in the blow molding section, simultaneously blow molding n (l According to the invention as set forth in claims 2 and 8, the invention provides the following operations and effects
in addition to those of the invention as set forth in claims 1 and 7 Because the number n of preforms simultaneously blow molded is made smaller than the number N of preforms simultaneously injection molded, fewer cavities are required in the blow mold and mold costs, molds being consumable items, can be greatly reduced Also, because fewer blow core molds, drawing rods, and mechanisms for supporting and driving these are required, the apparatus can be made more compact and cheaper Furthermore, because N simultaneously molded preforms are blow molded n (n Here, a heating section for heating the preforms being carried to the blow molding section can be provided When this is done, the preforms can be brought to a temperature suitable for blow molding by cooling performed by the injection molds and reheating of the cooled preforms, and the temperature stability from cycle to cycle therefore increases Also, even though N simultaneously injection molded preforms are blow molded n preforms at a time over (N/n) blow molding cycles, control reducing the temperature variation among blow molding cycles can easily be earned out
Also, when the preforms being heated are rotated about their vertical center axes, heating unevenness is reduced and temperature nonuniformty in the circumferential direction of the preforms can thereby be reduced
Furthermore, a second circulatory earner comprises a plurality of carrier members which remain spaced at equal
intervals along the second carrying path, and each of the earner members has a supporting portion for supporting a preform in an inverted or an upright state It is preferable that the array pitch at which the plurality of carrier members are spaced along the second earner path be made equal to the array pitch P of the plurality of cavities in the blow cavity mold This is because it makes pitch conversion in the carrying process unnecessary When this is done, the array pitch of the preforms in the heating section of the invention is greater than the small pitch at which the preforms are arrayed in the heating section in a conventional 2-stage system However, because in this invention it is only necessary to give the preforms a small amount of heat energy in addition to the heat which they retain from when they were injection molded, the heating time can be short and the length of the heating section does not have to be made long as it does in the cold panson case
Also, in the method of this invention, as described in claim 9, a step of allowing the preforms to cool between the separation of the preforms from the injection core mold and the start of the blow molding step, over a period of time long enough for the temperature difference between the inner and outer walls of the preforms to be moderated, can be provided Here, when the method of this invention is applied, because the period of time for which the preforms are cooled by the injection core mold in contact with their inner walls is made longer than conventionally, a relatively steep temperature gradient forms between the inner and outer walls of the preforms, and the temperature in the outer wall vicinity
becomes greater than that in the inner wall vicinity By providing this cooling step, this temperature gradient can be moderated and the inner and outer walls of the preforms can be brought to a temperature suitable for blow molding
Also, in the method of this invention, it is preferable that in the blow molding step n (n>2) containers simultaneously be blow molded from n preforms using n blow cavities arrayed at a blow molding pitch P, that the preforms being earned along the second carrying path be earned with the array pitch of the carrier members kept equal to this pitch P, and that in the preform transferring step a process wherein n preforms are simultaneously transferred to n carrier members is repeated a plurality of times
When this is done, as well as no carrying pitch conversion in the second carrying path being necessary, even if the number of preforms simultaneously injection molded N is increased, because only n preforms are transferred at a time, fewer than when N preforms are simultaneously transferred, the preforms can be easily correctly positioned on the earner members, and also no complex mechanisms are required to do this
An injection stretch blow molding method according to the invention as set forth in claim 13 wherein injection molded preforms are transferred from a preform molding station to a blow molding station by way of a transfer station and the preforms are blow molded into containers in the blow molding station is characterized in that
the transfer station turns the upright preforms upside-down and transfers them to the blow molding station in an inverted state, and
the blow molding station blow molds containers from the inverted preforms
According to the invention as set forth in claim 13, the preforms are molded in an upright state with their neck portions facing upward As a result, the injection mold clamping is vertical clamping and is therefore space-saving Also, because resin is normally injected from the preform bottom portion side, a stable arrangement wherein the injecting apparatus and the injection cavity mold are disposed on a machine bed and the injection core mold is disposed thereabove can be employed Also, because when the preforms are earned to the blow molding station they are in an inverted state, the openings at their neck portions can be used to have the preforms support themselves easily Furthermore, because the drawing rods and blow core molds consequently have to be positioned underneath the preforms, they can be disposed using a space in the machine bed and the overall height of the blow molding section can be made low
An injection stretch blow molding method according to the invention as set forth in claim 14 comprises the steps of
simultaneously injection molding N polyethylene terephthalate preforms using at least an injection core mold and a neck cavity mold,
releasing the preforms from the neck cavity mold,
cooling them by means of the injection core mold,
in the ejecting section, after the preforms have been cooled to a predetermined cooling temperature, ejecting the preforms by releasing them from the injection core mold,
heating the ejected preforms to a predetermined temperature, and
wherein the ratio of the numbers of preforms simultaneously molded N, n is N n = 3 1
According to experiments earned out by the present inventors, in the case of a general-purpose medium-sized container of capacity 1 to 3 liters having a relatively small mouth (the diameter of the opening in the neck portion 2 being about 28 to 38mm) for which the market demand is large, the ratio of the simultaneous molding numbers N, n should ideally be set to N n = 3 1 That is, it has been found that in the case of this invention wherein the preforms continue to be cooled by the injection core mold even after the preforms are removed from the injection cavity mold and then blow molded thereafter, the time required for the injection molding of a preform for a general-purpose medium-sized container is shortened to approximately 3/4 of that in the case of a conventional injection stretch blow molding apparatus, and an injection molding cycle time of approximately 10 to 15 seconds is sufficient A blow molding cycle time, on the other hand, of 3 6 to 4 0 seconds is sufficient Therefore, if this injection molding cycle time is T1 and the blow molding cycle time is T2, the ratio T1 T2 is roughly 3 1, and to mold
general-purpose medium-sized containers efficiently the simultaneous molding numbers N, n should ideally be set according to this ratio
An injection stretch blow molding apparatus and method according to the invention as set forth in claim 16 comprises the steps of
simultaneously injection molding N (N>2) preforms, and
simultaneously blow molding n (1 wherein N/n is an integer
When N/n is an integer, for example the N preforms simultaneously injection molded in a first cycle are all used over an integral number (N/n) of blow molding cycles n at a time, and none of these preforms are mixed with and simultaneously blow molded with any of the N preforms simultaneously molded in the subsequent second cycle If preforms from different injection molding cycles are mixed and blow molded together, the carrying sequence is different from the case wherein preforms molded in the same injection molding cycle are simultaneously blow molded together, and the control and structure of the apparatus become complicated, however, this invention eliminates this problem
A blow molding apparatus according to the invention as set forth in claim 17 wherein preforms carried in an inverted state with neck portions thereof facing downward or in an upright state with the neck portions facing upward are heated in a heating section before being earned to a blow molding section is characterized in that
the heating section comprises
a plurality of first heaters disposed at one side of the preform carrying path, spaced apart in the vertical direction and extending in the preform carrying direction,
a reflecting plate disposed facing the first heaters across the preform carrying path, and
wherein the second heaters are positioned at such a height in the vertical direction that they face regions subject to blow molding in the vicinities of the neck portions of the preforms
According to the invention as set forth in claim 17, although the region below the neck portion when the preform is upright is the nearest to the cavity surface of the blow cavity mold, it is a region which is to be draw orientated relatively much By heating this region with the second heaters on either side of the preform, it can be heated to a higher temperature than the trunk portion region heated by the first heaters disposed on one side only, and a high drawing orientation degree can be secured Also, because the first heaters are disposed on one side only, the arrangement is saving Furthermore, because the efficiency with which the region below the neck is heated increases, there is the benefit that the heating time can be shortened and the overall length of the heating section can be made short
A blow molding apparatus according to the invention as set forth in claim 18 comprises
circulatorily carry preforms,
a heating section having heaters extending in the preform carrying direction,
an endless carrying member running along the carrying direction at least through a heating zone of the heating section, and
wherein the earner members each have a rotary drive member for meshing with the endless carrying member and rotating and a preform supporting portion which rotates integrally with the rotary drive member, and
the forward direction of the endless carrying member where it meshes with the rotary drive member is opposite to the preform carrying direction
According to the invention as set forth in claim 18, while the preforms are stopped the preforms are rotated in one direction by the meshing of the endless drive member moving forward in a fixed direction and the rotary drive member rotated in a fixed position, and temperature nonumformity of the preforms can thereby be prevented Also, when the preforms are moving, because the endless drive member moves forward in the opposite direction to that in which the preforms are being carried, the preforms are rotated faster in the same direction and temperature nonumformity is similarly prevented If the endless drive member were to move forward along with the preforms in the same direction as the rotary drive member, because the preforms would only be rotated by the speed differential between the endless drive member and
the rotary drive member, the preforms would rotate slowly or not at all Also, there would be cases wherein the direction of the rotation of the preforms was different from that as of when the preforms were stopped All these situations would cause temperature nonumformity in the preforms, however, according to the invention as set forth in claim 18, this temperature nonuniform!ty is eliminated
A blow molding apparatus according to the invention as set forth in claim 20 wherein preforms are intermittently carried to a blow molding section via a heating section is characterized in that
in the carrying path between the heating section and the blow molding section there is provided a standby section where at least enough preforms for one blow molding cycle are stopped and made to standby before being carried into the blow molding section
According to the invention as set forth in claim 20, by a standby section being provided before the blow molding section, the temperature distributions in the synthetic resin preforms, which have poor thermal conductivity, can be moderated Normally, because heating in the heating section is earned out from around the preforms, the inner wall temperature of the preforms becomes lower than the outer wall temperature By having at least the number of preforms simultaneously blow molded standby after being heated in order to moderate the resulting temperature gradients therein, the
blow molding characteristics are stabilized
Also, by actively carrying out temperature adjustment on the preforms during this temperature moderation time in the standby section, the preforms can be given a temperature distribution for blow molding which could not be obtained just by simply heating the preforms while rotating them
An injection stretch blow molding apparatus according to the invention as set forth in claim 25 comprising a preform molding section for molding preforms and a blow molding section for blow molding containers from the preforms retaining heat from when they were molded is characterized in that
at a location in the path along which the preforms are earned from the preform molding section to the blow molding section there is provided a discharge guide section for guiding preforms which are not to be carried to the blow molding section off the carrying path
An injection stretch blow molding method according to the invention as set forth in claim 27 wherein preforms are injection molded in a preform molding section and these preforms are carried to a blow molding section and containers are blow molded from the preforms retaining heat from when they were molded comprises the steps of
switching to either a container molding operating mode or a preform molding operating mode, and
when the preform molding operating mode is switched to, part way along the preform carrying path leading to the blow molding section, discharging the preforms being molded in the preform molding section to off the carrying path
Accordmg to the invention it is possible to discharge imperfect preforms molded during molding start-up instead of carrying them to the blow molding section, wasteful blow molding can be avoided Also, when a problem arises in the blow molding section or when adjustments have to be made thereto, repair or adjustment of the blow molding section is possible without stoppmg the operation of the preform molding station Once the preform molding station is shut down, it takes a long time to restore the various heatmg mechanism to a state wherein molding is possible, however, with this invention this kind of wasteful starting up time is eliminated
According to the parent application, there is provided an injection stretch blow moldmg apparatus comprising
a preform molding station for injection moldmg preforms,
a transfer station for transferring the preforms from the preform molding station to the blow moldmg station,
an injection moldmg section for simultaneously injection moldmg N(N>2) of the preforms at a first pitch,
wherein the blow molding station comprises
a circulatory carrier for intermittently circulatory carrying the preforms along a carrymg path, the preforms being transferred from the preform moldmg station through the transfer station,
a heating section for heating the preforms transferring along said carrymg path, and
a blow molding section for simultaneously blow molding n (l and wherein said transfer station comprises
a receiving mechanism for receiving the preforms from said preform molding station, characterized in that
said transfer station comprises
a pitch changing mechanism for changing an array pitch of the preforms from said first pitch to a second pitch which is larger than said first pitch, and
an inverting mechanism for inverting the preforms, and said circulatory carrier is provided for intermittently circulatory carrying said preforms along said carrying path at said second pitch
According to the present invention there is provided an injection stretch blow moldmg method for blow molding containers from preforms retaining heat from when the preforms were injection molded, comprising the steps of
releasing^^L^W^T of the preforms, molded using at least an injection core mold and an injection cavity mold, from the injection cavity mold, with the preforms held by the injection core mold, carrying the injection core mold to an ejectmg section along a first carrying path at a first pitch (PI) while the preforms are cooled by the injection core mold,
in the ejectmg section, ejecting the preforms by releasing from the injection core mold,
transferring the preforms, which are ejected to carrier members to be carried along a second carrying path
carrying the carrier members supporting the preforms along the second carrying path to a blow molding section, and
in the blow molding section, simultaneously blow molding n(l^AjN) uf said containers from n of the preforms in a blow mold clamped relative to n of the preforms
in the step of blow molding, n (>2}-ef the containers are simultaneously blow molded from n of the preforms using (Table blow cavities arrayed at a blow I molding pitch (P3) which is larger than the first pitch (PI),
in the step of carrying the preforms along the second carrying path, the preforms are carried with an array pitch (P2) of the carrier members equal to said blow molding pitch, and
the step of transferring the preforms is carried out by a process of pitch changing and simultaneously transferring n of the preforms to rnjf the earner ^ members being repeated a plurality of times
According to the invention as set forth in claims 25 and
27, because it is possible to discharge imperfect preforms
molded during molding start-up instead of carrying them to the
blow molding section, wasteful blow molding can be avoided
Also, when a problem arises in the blow molding section or
when adjustments have to be made thereto, repair or adjustment
of the blow molding section is possible without stopping the
operation of the preform molding station Once the preform
molding station is shut down, it takes a long time to restore
the various heating mechanisms to a state wherein molding is
possible, however, with this invention this kind of wasteful
starting up time is eliminated
Fig 1 is a plan view of a preferred embodiment of the invention,
Fig 2 is a front view of the preferred embodiment apparatus shown in Fig 1,
Fig 3 is a left side view of the preferred embodiment apparatus shown in Fig 1,
Fig 4 is an enlarged view of the main parts of the apparatus shown in Fig 1,
Fig 5 is an underside view of a rotary disc,
Fig 6 is a perspective view showing the mold-released state of an injection core mold when a neck presser plate has been lowered,
Fig 7 is a partially sectional view showing the injection core mold and a neck cavity mold mounted on the rotary disc,
Fig 8 is a view illustrating a preform ejecting drive
mecham sm,
Fig 9 is an enlarged sectional view of portion A in Fig 8,
Fig 10 is a partially sectional view illustrating the mold-released state of the injection core mold,
Fig 11 is a partially sectional view illustrating a preform 1 ejecting operation,
Fig 12 is a view illustrating the operation of a transfer station receiving a preform,
Fig 13 is a view illustrating the operation of a transfer station handing a preform over to a blow molding station,
Fig 14 is a plan view of the transfer station,
Fig 15 is a side view of the transfer station,
Fig 16 is a plan view of a earner member of a second circulatory carrier provided in the blow molding station,
Fig 17 is a side view of the carrier member shown in Fig 16,
Fig 18 is a partially cut-away front view of the earner member shown in Fig 16,
Fig 19 is a side view in the preform carrying direction of a heating section,
Fig 20 is a plan view showing in outline a rotating carrier mechanism of the heating section,
Fig 21 is a plan view showing another preferred embodiment apparatus of the invention wherein the numbers of preforms molded simultaneously are different from those of the apparatus of Fig 1,
Fig 22 is a view illustrating the operation of a
transfer station transferring preforms while converting their pitch,
Fig 23 is a sectional view of a temperature adjusting core disposed in a standby section,
Fig 24 is a sectional view of a temperature adjusting pot disposed in the standby section,
Fig 25 is a sectional view of local temperature adjusting members disposed in the standby section, and
Fig 26 is a view of a flat container blow molded after the temperature adjusting shown in Fig 25 Detailed Description of the Preferred Embodiments
A preferred embodiment wherein the method and apparatus of the invention are applied will be described below with reference to the accompanying drawings
Fig 1, Fig 2 and Fig 3 respectively are a plan view, a front view and a left side view of the apparatus of this preferred embodiment, and Fig 4 is an enlarged view showing the main parts of the apparatus of the preferred embodiment As shown in the drawings, the apparatus comprises a preform molding station 10, a transfer station 200 and a blow molding station 300 disposed on a machine bed 8
As shown in Fig 2, the preform molding station 10 has a rotary disc 30 which has an injection core mold 50 in each of two locations an angle of rotation 180" apart and is a first circulatory carrier which circulatonly carries the injection core molds 50 intermittently along a rotary carrying path An injection molding section 14 facing an injecting apparatus 12 and a preform ejecting section 16 facing this injection
molding section 14 are respectively provided at the stopping positions of the injection core molds 50 The injection molding section 14 has an injection cavity mold 42 to which an injection core mold 50 can be clamped, and with this injection cavity mold 42 the injection molding section 14 simultaneously injection molds N (N>2), for example N = 4, preforms 1 at a time In the preform ejecting section 16, the injection core mold 50 is released from the preforms 1 In this preferred embodiment, a neck portion of each preform 1 is molded by means of a neck cavity mold 60 which will be further discussed later, and the preforms 1 are held by this neck cavity mold 60 and the injection core mold 50 and earned by the rotary disc 30 to the preform ejecting section 16 In the preform ejecting section 16 the preforms 1 are ejected by being released from the neck cavity mold 60 after a partial release of the injection core mold 50
As shown in Fig 1, the blow molding station 300 has a second circulatory carrier 302 comprising four sprockets 320a to 320d and a earner chain 322 running around these sprockets A plurality of for example ten carrier members 330 are fixed to this earner chain 322 uniformly spaced apart, and a preform 1 or a bottle 6 is supported by each earner member 330 In the carrying path of the earner members 330 are provided a preform receiving section 304 which receives the preforms 1 from the transfer station 200, a heating section 306 which heats the preforms 1, a standby section 308 which causes the heated preforms 1 to temporarily standby, a blow molding section 310 which blow molds the preforms 1 into bottles 6, and a bottle ejecting section 312
which ejects the bottles 6 to outside the apparatus
The blow molding section 310 has a blow mold 378 which is clamped around the preforms 1 and blow molds one bottle 6 from each of n (1 The transfer station 200 transfers the preforms 1 ejected from the preform ejecting section 16 of the preform molding station 10 to the preform receiving section 304 of the blow molding station 300 In the preform ejecting section 16 of the preform molding station 10 N preforms 1, I e the number of preforms 1 simultaneously molded in the injection molding section 14, are ejected at a time, but in the transfer station 200 n preforms 1, I e the number of preforms 1 simultaneously molded in the blow molding section 310 of the blow molding station 300, are transferred at a time In the apparatus of this preferred embodiment, four preforms 1 simultaneously ejected by the preform ejecting section 16 are transferred one at a time to the preform receiving section 304 Also, whereas in the preform molding station 10 the preforms 1 are injection molded in an upright state, in the transfer station 200 the preforms 1 are turned upside-down and transferred to the blow molding station 300 in an inverted state
Preform Moldinq Station 10
First the preform molding station 10 will be described, with reference to Fig 1 to Fig 11
Imection Moldinq Section 14 and First Circulatory
As shown in Fig 2 and Fig 4, the injection molding section 14 of the preform molding station 10 is provided with a lower clamping plate 20 mounted on the machine bed 8 A for
example circular upper clamping plate 22 is disposed above this lower mold clamping plate 20 and extends from the injection molding section 14 into the preform ejecting section 16 This upper mold clamping plate 22 is movable vertically along four tie bars 24 provided in four locations around the injection molding section 14 As shown in Fig 1, Fig 2 and Fig 4, a fixed plate 26 is mounted on the upper ends of the tie bars 24 and a clamping cylinder 28 is mounted on this fixed plate 26 The clamping cylinder 28 drives a clamping rod 28a (see Fig 4), and the upper clamping plate 22 is driven up and down by this clamping rod 28a
As shown in Fig 2 to Fig 4, the rotary disc 30 constituting the first circulatory carrier is rotatably mounted at the underside of the upper clamping plate 22 As shown in Fig 7, this rotary disc 30 is fixed to a rotational shaft 34 rotationally driven by a rotary actuator 32 fixed to the upper clamping plate 22 As shown in Fig 5, which is an underside view of the rotary disc 30, the two injection core molds 50 and the two neck cavity molds 60 are mounted on the rotary disc 30 in positions corresponding to the injection molding section 14 and the preform ejecting section 16 The details of the injection core molds 50 and the neck cavity molds 60 will be discussed in detail later
As shown in Fig 2 and Fig 4, the injection molding section 14 is provided with a hot runner mold 40 with which a nozzle of the injecting apparatus 12 nozzle-touches, and the injection cavity mold 42 is mounted on this hot runner mold 40 This injection cavity mold 42 has a cavity for each of the N preforms 1 simultaneously molded in the injection
molding section 14, for example four cavities This injection cavity mold 42 is capable of cooling the injection molded preforms, and a coolant, for example water at room temperature, is circulated therethrough
As shown in Fig 4 to Fig 8, the two injection core molds 50 mounted on the rotary disc 30 each have the same number of core pins 52 as the number N of preforms simultaneously molded, for example four core pins 52 As shown in Fig 7, the base portions 52a of these core pins 52 are supported by a core presser plate 54 fixed to the underside of the rotary disc 30 and a core fixing plate 56 fixed to the underside of this core presser plate 54 When the clamping cylinder 28 is driven and the clamping rod 28a drives down the upper clamping plate 22, the core pins 52 of the injection core mold 50 are driven down integrally with the rotary disc 30, the core presser plate 54 and the core fixing plate 56 mounted on this upper clamping plate 22 and are thereby clamped onto the injection cavity mold 42
As shown in Fig 7 and Fig 11, the two neck cavity molds 60 mounted on the rotary disc 30 are made up of pairs of split molds 62a and 62b, each neck cavity mold 60 comprising the same number of pairs of split molds 62a and 62b as the number N of preforms simultaneously molded, for example four The pairs of split molds 62a and 62b of each neck cavity mold 60 are fixed by split plates 64a and 64b, and these split plates 64a and 64b constitute a neck fixing plate 64 As shown in Fig 11, a neck presser plate 65 which pushes this neck fixing plate 64 downward is disposed on the upper surface side of the split plates 64a and 64b Also, there are provided guide
plates 66 which support the undersides of the ends of the neck fixing plate 64 The split plates 64a and 64b are kept normally closed by springs 64c shown in Fig 5 As shown in Fig 5, a wedge hole 64d is provided at each end of the split plates 64a and 64b After the neck fixing plate 64 has been earned into the preform ejecting section 16, the split plates 64a and 64b are opened by being driven apart along the guide plates 66 by split plate opening cams 108, which will be further discussed later, driven into the wedge holes 64d
As shown in Fig 9, which is an enlarged sectional view of portion A of Fig 8, and in Fig 6, at each end of each guide plate 66 a vertical lifting and lowering pin 70 has its lower end fixed in the guide plate 66, and a flange 70a is formed at the upper end of this lifting and lowering pin 70 A guide cylinder 72 extends downward from the underside of the rotary disc 30, and the lifting and lowering pin 70 is disposed inside this guide cylinder 72 A return spring 74 is disposed between the inner wall of the bottom portion of the guide cylinder 72 and the flange 70a of the lifting and lowering pin 70 The upward urging force of these return springs 74 urges the guide plate 66 upward at all times, and as a result the neck presser plate 65 is normally in contact with the underside of the core fixing plate 56
By this state of contact between the core fixing plate 56 and the neck presser plate 65 being maintained, the injection core mold 50 and the neck cavity mold 60 are kept clamped together When in the preform ejecting section 16 an external force (which will be further discussed later) is applied to the lifting and lowering pins 70, the lifting and lowering
pins 70 descend against the urging force of the return springs 74 and the neck presser plate 65 is driven down so that it moves away from the underside of the core fixing plate 56 and pushes the neck fixing plate 64 downward As a result, the core pins 52 of the injection core mold 50 are released from the preforms 1 whose neck portions 2 are held by the neck cavity mold 60
Preform Electing Section 16
Next, the construction of the preform ejecting section 16, and in particular the preform ejection drive mechanism will be described In this preferred embodiment, the preform ejection drive mechanism is made up of a neck mold-release driver 80 and a split mold opening driver 100 As shown in Fig 8, the neck mold-release driver 80 has a first cylinder 82, and this first cylinder 82 is mounted on a first cylinder mounting plate 84b supported on the upper clamping plate 22 by way of first support rods 84a The first cylinder 82 drives a first raising and lowering plate 86 up and down by way of a first piston rod 82a Presser drive rods 88 are provided at each end of this first raising and lowering plate 86 Holes 22a are provided in the upper clamping plate 22 passing through from the upper surface to the lower surface thereof, and the presser drive rods 88 are disposed in these holes 22a The initial position of the first raising and lowering plate 86 is a position such that the ends of the presser drive rods 88 do not project below the underside of the upper clamping plate 22 so they do not obstruct the rotation of the rotary disc 30
As shown in Fig 8, the rotary disc 30, the core presser
plate 54 and the core fixing plate 56 respectively have holes 30a, 54a and 56a in positions facing the holes 22a in the upper clamping plate 22 Driven rods 68 disposed in the holes 30a, 54a and 56a are mounted on the upper surface of the neck presser plate 65
As a result, when the first cylinder 82 is driven, the neck presser plate 65 and the neck fixing plate 64 are driven down against the urging force of the return springs 74 by the first cylinder 82 by way of the first piston rod 82a, the presser drive rods 88 and the driven rods 68 As shown in Fig 10, this causes the core pins 52 of the injection core mold 50 to release from the preforms 1 whose neck portions 2 are held by the neck cavity mold 60 In this preferred embodiment, the core pins 52 of the injection core mold 50 do not have to be pulled completely clear of the open ends of the preforms 1, it only being necessary that at least gaps through which air can enter form between the core pins 52 and the inner walls of the preforms 1 In this preferred embodiment, the downward stroke of the neck fixing plate 64, that is the releasing stroke of the core pins 52 (the length L shown in Fig 10), is set at for example 50mm
Next, the split mold opening driver 100 will be described As shown in Fig 1 and Fig 8, this split mold opening driver 100 has for example two second cylinders 102 These second cylinders 102, as shown in Fig 11, are mounted on a second cylinder mounting plate 104b supported on the first raising and lowering plate 86 by way of second support rods 104a As a result, when the first raising and lowering plate 86 is driven up or down by the first cylinder 82, the
second cylinders 102 are also moved up or down at the same time These second cylinders 102 drive second raising and lowering plates 106 up and down by way of second piston rods 102a The split plate opening cams 108 are mounted on these second raising and lowering plates 106 The lower end portions of these split plate opening cams 108 are of a wedge shape fitting the wedge holes 64d formed in the split plates 64a and 64b constituting the neck fixing plate 64 By driving the second cylinders 102 the split plate opening cams 108 are driven down and the wedge portions at their ends are thereby inserted into the wedge holes 64d in the neck fixing plate 64, and this opens the split plates 64a and 64b Consequently the pairs of split molds 62a and 62b mounted on this pair of split plates 64a and 64b are opened, and the preforms 1 are ejected from the neck cavity mold 60 In this preferred embodiment the drive timing of the second cylinders 102 is set to after the first cylinder 82 is driven
Next, the operation of the preform molding station 10 of the apparatus of the preferred embodiment will be described Imection Moldinq in Imection Molding Section 14 The clamping cylinder 28 is driven and the upper clamping plate 22 is thereby driven down, whereby the injection core mold 50 and the neck cavity mold 60 are clamped to the injection cavity mold 42 After the clamped state shown in Fig 4 is reached, by a screw inside the injecting apparatus 12 being advanced and rotated, the preforms 1 injection molding material, for example polyethylene terephthalate (PET), is injected by way of the hot runner mold 40 into the cavity bounded by the molds 42, 50 and 60, and the preforms 1
are thereby injection molded
Coolinq Step in Imection Moldinq Section 14
The injection cavity mold 42, the injection core mold 50 and the neck cavity mold 60 each have a coolant, for example water at room temperature, circulating through them, and the resin injected into the cavity bounded by the molds can be immediately cooled
Imection Cavity Mold 42 Mold-Release Step in Imection
Moldinq Section 14
By the clamping cylinder 28 being so driven that it lifts the upper clamping plate 22, the injection core mold 50 and the neck cavity mold 60 can be lifted up away from the injection cavity mold 42 as shown by the mold-open state of Fig 10 At this time, because the neck portions 2 of the preforms 1 form an undercut with respect to the mold-release direction, the injection molded preforms 1 are held on the injection core mold 50 and neck cavity mold 60 side and are released from the injection cavity mold 42
The timing at which this mold-release starts in the injection molding section 14 can be made considerably earlier than a conventional mold-release starting timing In other words, the cooling time of the preforms 1 in the injection molding section 14 can be shortened This is because even after the preforms 1 have been released from the injection cavity mold 42 the core pins 52 of the injection core mold 50 remain inside the preforms 1 and deformation of the preforms 1 accompanying their thermal contraction can be prevented Therefore, the mold-release temperature of the preforms 1 in the injection molding section 14 only has to be low enough for
a skin layer thick enough for the shape of the preforms 1 to be maintained after they are released from the injection cavity mold 42 to form at the outer surfaces of the preforms 1, and can be higher than conventional mold-release temperatures Even if the mold-release temperature is high like this, because the cooling causes the preforms 1 to contract around the core pins 52 of the injection core mold 50, mold-release from the injection cavity mold 42 can be carried out relatively smoothly, and preform 1 mold-release problems do not occur Also, because in the injection molding section 14 withdrawal of the core pins 52 is not earned out, even if the preforms 1 are mold-released at a high mold-release temperature, the mold-release problem of the lower ends of the preforms 1 being lifted together with the core pins 52 does not occur
The clamped state of the injection core mold 50 and the neck cavity mold 60 with respect to the preforms 1 released from the injection cavity mold 42 is maintained by the core fixing plate 56 and the neck presser plate 65 being kept in contact with each other by the return springs 74 This clamped state of the injection core mold 50 and the neck cavity mold 60 is maintained through the subsequent preforms 1 carrying step and until in the preform ejecting section 16 the injection core mold 50 is released from the preforms 1 Cooling of the preforms 1 is possible throughout the time during which this clamped state of the injection core mold 50 and the neck cavity mold 60 is maintained
Preforms 1 Carryinq Step
The preforms 1 are earned from the injection molding
section 14 to the preform ejecting section 16 by the rotary actuator 32 being driven and the rotary disc 30 constituting the first circulatory earner being rotated thereby through 180° During this preforms 1 carrying step, it is possible for cooling of the preforms 1 by the coolant circulating through the injection core mold 50 and the neck cavity mold 60 to continue without interruption
Generally, when the preforms 1 are mold-released at a high temperature, crystallization occurs due to inadequate cooling and the wall surfaces o-f the preforms 1 become nontransparent, and particularly when PET is being used to make transparent containers this is a fatal defect According to experiments carried out by the present inventors, this crystallization and loss of transparency of the preforms 1 accompanying inadequate cooling is particularly marked at the inner wall sides of the preforms 1 This is because at the inner wall side of a preform 1 there is less surface area in contact with the mold and consequently the inner wall is more liable to be inadequately cooled than the outer wall Also, when as in the past the injection cavity mold 42 and the injection core mold 50 are released from the preforms 1 in the injection molding section, the inner wall side is more liable to be inadequately cooled than the outer wall because the heat-radiating surface area at the inner wall side of the preform 1 is smaller than at the outer wall side and furthermore heat is confined in the interior of the preform 1
it is possible for the preforms 1 to continue to be cooled by the injection core mold 50 and the neck cavity mold 60 In particular, because the inner walls of the preforms 1 can be uninterruptedly cooled by the core pins 52 of the injection core mold 50, crystallization and loss of transparency caused by inadequate cooling can be certainly prevented Also, the neck portions 2, which because they are thick have large heat capacities and are more liable to crystallize than other portions, can be cooled by the neck cavity mold 60 and prevented from crystallizing
Preform Coolinq Step in Preform Eiectinq Section 16
Even after the preforms 1 have been carried into the preform ejecting section 16, by the clamped state of the injection core mold 50 and the neck cavity mold 60 with respect to the preforms 1 being maintained, the preforms 1 can be cooled as they were during the above-mentioned carrying step At this time, even if in the injection molding section 14 the clamping cylinder 28 has been driven and the upper clamping plate 22 lowered for the injection molding of the next preforms, because the above-mentioned clamped state in the preform ejecting section 16 is maintained, cooling of the preforms 1 can be continued
Separation of Neck Cavity Mold 60 from imecfion Core
preforms 1 are excessively cooled by the core pins 52, removal of the core pins 52 becomes difficult Therefore, in this preform ejecting section 16, first the injection core mold 50 is released from the preforms 1 In this preferred embodiment, this is achieved by the neck cavity mold 60 holding the preforms 1 being released from the injection core mold 50
This separation of the neck cavity mold 60 is earned out by the neck presser plate 65 kept in contact with the core fixing plate 56 by the urging force of the return springs 74 being lowered by the neck mold-release driver 80 When the first cylinder 82 of the neck mold-release dnve-r 80 is driven, the pushing force thereof transmitted through the first piston rod 82a, the first raising and lowering plate 86, the presser drive rods 88 and the driven rods 68 causes the neck fixing plate 64 to be pressed against the neck presser plate 65 and be driven downward as shown in Fig 6 and Fig 10 At this time, because the preforms 1 have their neck portions 2 held by the neck cavity mold 60, the preforms 1 are also driven downward together with the neck fixing plate 64 and the neck cavity mold 60 Consequently, the separation of the neck cavity mold 60 from the injection core mold 50 results in the injection core mold 50 being released from the preforms 1
enough for at least gaps through which air can enter to be formed between the inner walls of the preforms 1 and the core pins 52 Consequently, the mold-releasing stroke of the injection core mold 50 depends on the angle of the removal taper provided on the core pins 52 and the inner walls of the preforms 1, and the greater this removal taper angle is, the shorter the mold-release stroke need be Because the mold-releasing stroke of the injection core mold 50 can be shortened in this way the installation height of the first cylinder 82 can be made low and the overall height of the injection molding apparatus can be made low, and this is advantageous in the transportation and installation of the apparatus
Preforms 1 Election Step in Preform Eiectinq Section 16 Because the preforms 1 have their neck portions 2 held by the neck cavity mold 60 comprising the pairs of split molds 62a and 62b, the preforms 1 can be ejected by this neck cavity mold 60 being released To bring this about, the second cylinders 102 of the split mold opening driver 100 are driven This driving force of the second cylinders 102 is transmitted to the split plate opening cams 108 by way of the second piston rods 102a and the second raising and lowering plates 106 By the split plate opening cams 108 being driven downward, as shown in Fig 11 their ends are inserted into the wedge holes 64d formed in the split plates 64a and 64b, these split plates 64a and 64b are driven open, and the pairs of split molds 62a and 62b are thereby opened At this time, even if a neck portion 2 of a preform 1 has stuck to one of the split molds 62a, 62b and tries to move therewith, because
the respective core pin 52 of the injection core mold 50 is still inside the preform 1, lateral movement of the preform 1 is restricted and the preform 1 can be dropped downward without fail
In the state before the split plate opening cams 108 are driven downward, in order to avoid the split plate opening cams 108 interfering with the rotation of the rotary disc 30 it is necessary that their ends stop within the thickness of the upper clamping plate 22 On the other hand, because the neck fixing plate 64 which is driven open by these split plate opening cams 108 is in the farthest position from the rotary disc 30, the downward stroke of the split plate opening cams 108 is long In this preferred embodiment, because the second cylinders 102 which drive these split plate opening cams 108 are mounted on the first raising and lowering plate 86 driven by the first cylinder 82 and because before the split plate opening cams 108 are driven the first raising and lowering plate 86 is driven, the actual downward stroke through which the split plate opening cams 108 are driven by the second cylinders 102 is short As a result, the installation height of the second cylinders 102 can be made low, the overall height of the injection molding apparatus an be made low, and an apparatus advantageous from the points of view of transportation and installation can be provided
After this preform 1 ejecting step is finished, the first and second cylinders 82 and 102 return to their original states As a result, the neck presser plate 65 is brought back into contact with the core fixing plate 56 by the return springs 74, and the injection core mold 50 and the neck cavity
mold 60 are returned to their clamped state in preparation for the next injection molding
The cooling and mold-releasing steps described above carried out in the preform ejecting section 16 only have to be finished within the time taken for the injection molding of the next, new preforms in the injection molding section 14 to finish, in other words within the injection molding cycle time The preform 1 cooling time depends particularly on the thickness of the trunk portions of the preforms 1, and the thicker the preforms 1 are the longer the cooling time that must be provided In this preferred embodiment this cooling time can be adjusted by way of the setting of the timing of the mold-release of the injection core mold 50 in the preform ejecting section 16 as well as by adjusting the cooling time in the injection molding section 14 As a result, even while the mold-release temperature in the injection molding section 14 is made high and the injection molding cycle time thereby shortened, because adjustment of the cooling time is easy a highly flexible preform injection molding station can be provided
After the preform 1 injection molding in the injection molding section 14 is finished, the injection core molds 50 and the neck cavity molds 60 in the two sections 14 and 16 are changed around by the rotary disc 30 being rotated through 180° by the rotary actuator 32 In this preferred embodiment, the rotary actuator 32 consists of reversible rotary carrying means of which the rotary carrying direction reverses each time As a result, even if the injection core molds 50 and the neck cavity molds 60 rotationally carried have cooling
ipes for circulating coolant therethrough connected thereto, these cooling pipes will not be twisted through more than one revolution Consequently, it is possible to connect these cooling pipes to the molds without using rotary connectors and their construction does not become complicated
Because for the reasons discussed above the preforms 1 are given a uniform temperature or a suitable temperature distribution, it is possible to mold bottles of a desired thickness Also, because whitening crystallization of the bottles is prevented, highly transparent bottles can be molded This invention is not limited to being applied to the hot panson blow molding described above, and of course can also be applied to so-called cold panson blow molding wherein the preforms are returned to room temperature before being heated again and blow molded In this case also, there is the effect that the injection molding cycle time can be shortened
Next, the constitution and operation of the transfer station 200 will be described with reference to Fig 2, Fig 12 to Fig 14 and Fig 21 and Fig 22 Fig 12 to Fig 15 show a mechanism corresponding not to the preferred embodiment apparatus shown in Fig 1 but rather corresponding to a preferred embodiment apparatus shown in Fig 21 Fig 21 shows a case wherein the above-mentioned numbers N and n of preforms molded simultaneously are respectively N = 6 and n = 2, and accordingly the mechanisms of the transfer station 200 shown in Fig 12 to Fig 15 transfer n = 2 preforms 1 simultaneously The case wherein n = 1 preform 1 is transferred at a time is exactly the same as the case where n
= 2 except in that there is no transfer pitch conversion, which will be further discussed later
This transfer station 200 has a receiving and lowering mechanism 210 which receives and lowers preforms 1 ejected from the preform ejecting section 16 of the preform molding station 10, and an inverting and handing over mechanism 230 which then turns the preforms 1 upside-down and hands them over to the preform receiving section 304 of the blow molding station 300
Receivinq and Lowennq Mechanism 210
Fig 12 and Fig 13 respectively show the receiving and lowering mechamsm 210 in a raised position and a lowered position This receiving and lowering mechanism 210 has a bottom portion holding part 214 which holds the bottom portion 3 of a preform 1 and a neck lower portion holding part 218 which supports a support ring 2a formed at the lower end of the neck portion 2 of the preform 1 The bottom portion holding part 214 is mounted on a rod 212a of a first raising and lowering drive device 212 comprising an air cylinder or the like and is movable up and down between the raised position in which it is shown in Fig 12 and the lowered position in which it is shown in Fig 13 This vertical stroke b is shown in Fig 4
The neck lower portion holding part 218 is movable up and down together with the bottom portion holding part 214 and is movable horizontally through a horizontal stroke a. shown in Fig 4 To make this possible, a first slider 220 is disposed on a rail 222 slidably therealong This first slider 220 is driven horizontally by a rod 216a of a first advancing and
withdrawing drive device 216 comprising an air cylinder or the like The neck lower portion holding part 218 has a small diameter shaft portion 218a at its lower part and a large diameter shaft portion 218b at its upper part, and the small diameter shaft portion 218a passes through a stopper member 220a mounted on the first slider 220 A flange 218c is fixed to the lower end of the small diameter shaft portion 218a which projects below this stopper member 220a Also, a spring 218d is disposed around a portion of the small diameter shaft portion 218a projecting upward of the bottom portion holding part 214 Because this spring 218d is disposed between the bottom portion holding part 214 and the large diameter shaft portion 218b, the large diameter shaft portion 218b is pushed upward by the spring 2l8d as the bottom portion holding part 214 ascends, and the neck lower portion holding part 218 can thereby be raised When the first advancing and withdrawing drive device 216 is driven, because this horizontal driving force is transmitted by way of the first slider 220 to the shaft portions 218a and 218b, the neck lower portion holding part 218 is caused to slide horizontally This sliding stroke a. is shown in Fig 4
The operation of this receiving and lowering mechanism 210 will now be explained with reference to Fig 4, Fig 12 and Fig 13 Before the neck cavity mold 60 is driven open in the preform ejecting section 16 of the preform molding station 10, the bottom portion holding part 214 and the neck lower portion holding part 218 are disposed in the positions in which they are shown in Fig 12 In this state shown in Fig 12, the raised position of the neck lower portion holding part
218 is determined by the flange 218c thereof abutting with the stopper member 220a The bottom portion holding part 214 is stopped in a position which it reaches by compressing the spring 2l8d after the neck lower portion holding part 218 has reached its upper limit position At this time, the neck lower portion holding part 218 is in a position wherein it is withdrawn to the right in Fig 4 and Fig 12 of a position directly below the support ring 2a of the preform 1 When the neck cavity mold 60 is driven open, the preform 1 drops downward and its bottom portion 3 is caught by the bottom portion holding part 214 At this time, as shown in Fig 12, the preform 1 does not completely release from the core pin 52 and the preform 1 maintains an upright state with a portion of the core pin 52 remaining inserted therein
After that the first advancing and withdrawing drive device 216 is driven, and the neck lower portion holding part 218 is moved to the left through the stroke a (see Fig 4) As a result, the neck lower portion holding part 218 is positioned directly below the support ring 2a of the preform 1
After that, the first raising and lowering drive device 212 is so driven that it pulls in the rod 212a, and the bottom portion holding part 214 starts to be lowered In the initial stage of this lowering, until the spring 218d returns to its original length, the neck lower portion holding part 218 stays in its upper position As a result, during the initial stage of this lowering, the bottom portion holding part 214 moves away from the bottom portion 3 of the preform 1 and the support ring 2a of the preform 1 comes to rest on the neck
lower portion holding part 218 The first raising and lowering drive device 212 continues to be driven after this, and the preform 1 descends with its support ring 2a being held by the neck lower portion holding part 218 only It is preferable that members of low thermal conductivity, for example synthetic resin or the like, be used for the portions of the bottom portion holding part 214 and the neck lower portion holding part 218 which make contact with the preform 1 The preform 1 supported by the neck lower portion holding part 218 continues to be lowered until it reaches the position in which it is shown in Fig 13
Invertinq and Handinq Over Mechanism 230
Next, the constitution of the inverting and handing over mechanism 230 will be described with reference to Fig 4 and Fig 13 to Fig 15 This inverting and handing over mechanism 230 has two neck holding mechanisms 232 corresponding to the number n = 2 of preforms simultaneously blow molded in the blow molding section 310 shown in Fig 21 (see Fig 14) The neck holding mechanisms 232 each have an open/closeable pair of neck holding members 234 which hold the neck portion 2 of the preform 1 As shown in Fig 15, these two neck holding mechanisms 232 are mounted on a support table 236, and this support table 236 is linked to a rod 238a of a second raising and lowering drive device 238 comprising and air cylinder or the like As a result, the two neck holding mechanisms 232 are movable vertically through a vertical stroke e shown in Fig 4 In order to make this vertical movement smooth, for example two guide rods 240 are provided and guided by guide portions 242
The second raising and lowering drive device 238 and the guide portions 242 described above are mounted on a second slider 244 as shown in Fig 15 This second slider 244 is provided with a horizontal drive device 246 which moves the second slider 244 in the direction in which the number of preforms N, for example 4, simultaneously molded in the injection molding section 14 are arrayed This horizontal drive device 246 moves the second slider 244 horizontally by means of for example a ball screw 246a The horizontal drive device 246 is mounted on a third slider 248, and this third slider 248 is provided with a second advancing and withdrawing drive device 250 which advances and withdraws the raising and lowering drive device 238 through the advancing and withdrawing stroke c shown in Fig 4 That is, as shown in Fig 14, a rod 250a of the second advancing and withdrawing drive device 250 is linked to the third slider 248
Also, there is provided an inverting drive device 252 which rotates the two neck holding mechanisms 232 through 180° about a horizontal axis The 180° rotational stroke d of this inverting drive device 252 is shown in Fig 4 As a result of this inversion the preform 1 moves from an upright state wherein the neck portion 2 faces upward to an inverted state wherein the neck portion 2 faces downward
Next, the operation of this inverting and handing over mechanism 230 will be explained When the preforms 1 reach their lowered positions as shown in Fig 13, the neck holding mechanisms 232 which are in a standby position shown with chain lines in Fig 13 are rotated through 180° by the inverting drive device 252 Opening and closing drive
mechanisms incorporated into the neck holding mechanisms 232 close the pairs of neck holding members 234, and the neck portions 2 of the preforms 1 are held by these neck holding members 234 Then the preforms 1 are inverted Before that, however, to prevent the preforms 1 from interfering with other members, the neck lower portion holding part 218 is withdrawn to the right through the moving stroke a (see Fig 4), and by the third slider 248 being moved to the left through the moving stroke c (see Fig 4) the two neck holding mechanisms 232 are moved to the left After that, by the preforms 1 being rotated through 180" by the inverting drive device 252, the preforms 1 reach the position shown with chain lines in Fig 13 Then, by the two neck holding mechanisms 232 being lowered by the second raising and lowering drive device 238 through the stroke e (see Fig 4), the preforms 1 can be placed on carrier members 330 positioned in the preform receiving section 304 of the blow molding station 300 After that, the neck holding mechanisms 232 are opened and moved through the vertical stroke e and the transverse stoke c shown in Fig 4 whereby the neck holding mechanisms 232 are moved away from the preforms 1 and returned to their standby position shown with chain lines in Fig 13
When the above transfer operation is carried out in the preferred embodiment apparatus shown in Fig 21 wherein the number of simultaneously blow molded preforms 1 is n = 2, n = 2 preforms 1 are transferred simultaneously The transferred two preforms 1 are handed over to earner members 330 in two receiving positions 260 At this time, the pitch P2 at which the neck holding mechanisms 232 receive the two preforms 1
from the receiving and lowering mechanism 210 is different from the pitch P3 at which the neck holding mechanisms 232 deliver the two preforms 1 to the earner members 330 This is because during the transfer of the preforms 1 pitch conversion is performed by a pitch change drive device 254, this point will be further discussed later In the case of the preferred embodiment apparatus of Fig 1 wherein the number of preforms 1 simultaneously blow molded is n = 1, the preform 1 is delivered to a earner member 330 positioned between the two receiving positions shown in Fig 14 Therefore, each time an injection molding operation in which N = 4 simultaneously injection molded preforms 1 are injection molded is finished, transfer of one preform 1 at a time is repeated four times
Blow Moldinq Station 300
Next, the blow molding station 300 will be described with reference to 41, Fig 4 and Fig 16 to Fig 20
Second Circulatory Carrier 302 and Preform Receivinq
This blow molding station 300 circulates the carrier member 330 earned by the second circulatory carrier 302 in order through the preform receiving section 304, the heating section 306, the standby section 308, the blow molding section 310 and the bottle ejecting section 312 As shown in Fig 1, the second circulatory earner 302 has four sprockets 320a to 320d, and for example only the sprocket 320a is driven and the other sprockets 320b to 320d are not driven An endless earner chain 322 runs around these four sprockets 320a to
320d Some other endless drive member, such as a belt, for example a V-belt or a toothed belt, can be used instead of the chain, and other rotary drive members such as pulleys can be used instead of the sprockets
In the preferred embodiment apparatus shown in Fig 1, ten earner members 330 are fixed to the carrier chain 322 This fixing structure is as follows
As shown in Fig 18, each earner member 330 has a cylindrical mount portion 332 This mount portion 332 has is provided at one side thereof with projecting portions 334a and 334b which respectively project above and below the earner chain 322, sandwiching the carrier chain 322 Adjacent chain links in the carrier chain 322 are connected by hollow pins, and the upper and lower projecting portions 334a and 334b are linked to the earner chain 322 by fixing pins 336 being passed through the central portions of the hollow pins and having their ends secured so that they cannot drop out
A cylinder 342 is rotatably supported by way of a bearing 340 inside the cylindrical portion of the mount part 332 The upper portion of this cylinder 342 functions as a carrying surface 344 on which the end surface of the neck portion 2 of an inverted preform 1 is placed Also, a carrying pin 346 is supported inside this cylinder 342 This carrying pin 346 has a portion thereof projecting upward of the carrying surface 344 which enters the neck portion 2 of the preform 1 and can support the preform 1 in its inverted state Thus, the carrying surface 344 and the carrying pin 346 constitute a preform 1 supporting portion
As shown in Fig 16, three cam followers 338 consisting
of rollers or the like are supported on this carrier member 330 Two of the cam followers 338 roll along the inner side locus described when the earner member 330 is driven by the earner chain 322 The other cam follower 338 rolls along the outer side locus These three cam followers 338 are guided by a earner base 324 or by rails 326, depending on where the earner member 330 is in the blow molding station 300 As shown in Fig 18, the two rails 326 are disposed on either side of the carrying path and each are formed with a C-shaped cross-section and have a cam surface 326a These rails 326 have portions which so project that they cover the upper portions of the cam followers 338, and the cam followers 338 cannot leave the rails 326 These rails 326 are disposed in the blow molding section 310
On the other hand, in all parts of the carrying path outside the blow molding section 310, for example as shown in Fig 19 showing the heating section 306, the earner base 324 is provided below the carrying path Upper surfaces of this carrier base 324 constitute cam surfaces 324a Portions of the rails 326 disposed in the heating section 306 are so disposed that they cover the upper portions of the cam followers 338 and prevent the cam followers 338 from escaping from their travel paths Because if the carrier base 324 were provided in the blow molding section 310 it would not be possible for a drawing rod and a blow core mold to be inserted from below into the preform 1, such a construction is not used
An autorotation sprocket 348 is mounted on the cylinder 342 of the earner member 330 When the preform 1 is in the
heating section 306, this autorotation sprocket 348 rotates the preform 1 about its vertical axis, this point will be further discussed in the description of the heating section 306
The driving sprocket 320a repeats an intermittent carrying movement wherein it moves by an amount corresponding to one pitch of the carrier members 330 fixed to the earner chain 322 at a predetermined pitch and then stops for a predetermined period of time By the preform 1 being received in an inverted state by the preform receiving section 304 of the blow molding station 300 the preform 1 is placed on the carrying surface 344 of the carrier member 330 and the carrying pin 346 is inserted into the neck portion 2 of the preform 1 When after that the driving sprocket 320a is driven and rotates, the earner chain 322 meshing with the sprockets 320a to 320d moves and the earner members 330 are thereby moved by one pitch By this carrying operation being repeated, the preforms 1 received in the preform receiving section 304 are carried through the heating section 306 and the standby section 308 to the blow molding section 310, and here they are drawn and blow molded into bottles 6 After that the bottles 6 on the carrier members 330 are carried to the bottle ejecting section 312, and here the bottles 6 are ejected to outside the apparatus
Heatinq Section 306
Next, the heating section 306 will be described with reference to Fig 19 and Fig 20
The heating section 306 heats the preform 1 by means of radiant heat in a space enclosed by a heating box cover 350
As described above, in the apparatus of this preferred embodiment, the preform 1 can be amply cooled by the injection core mold 50 while it is being carried to the preform ejecting section 16 and in the preform ejecting section 16 until the injection core mold 50 is released from the preform 1 As a result, while the method is still a hot panson method, the preform 1 can be amply cooled and can be cooled to a temperature lower than is suitable for blow molding For this reason, in the apparatus of this preferred embodiment, the preform 1 is heated in the heating section 306 provided in the blow molding station 300 until it reaches a temperature suitable for blow molding
Inside the heating box cover 350 of the heating section 306 there are provided first to fourth barlike heaters 352a to 352d constituting a first heater set disposed spaced apart in the axial direction of the preform 1 The barlike heaters 352a to 352d are for example infrared heaters, and extend in the preform 1 carrying direction inside the heating box cover 350 The first and second barlike heaters 352a and 352b are partly surrounded by a focussing reflecting plate 354a, and heat especially the bottom portion 3 of the preform 1 with radiant heat The third and fourth barlike heaters 352c and 352d are partly surrounded by a focussing reflecting plate 354b and heat especially the vicinity of the trunk portion 4 of the preform 1 with radiant heat As shown in Fig 19, a reflecting plate 356 is disposed on the other side of the carrying path facing the barlike heaters 352a to 352d
Also, as shown in Fig 19, fifth and sixth barlike heaters 352e and 352f constituting a second heater set are
disposed one on either side of the preform 1 carrying path These barlike heaters 352e and 352f are positioned at such a vertical height that they face the vicinity of the neck portion 2 of the preform 1 which is draw orientated in the blow molding section 310 The region of the preform 1 heated by these fifth and sixth barlike heaters 352e and 352f is the region which is immediately below the neck portion 2 when the preform 1 is upright, and will hereinafter be called the region below the neck 4a
This region below the neck 4a is the region corresponding to the shoulder portion of the blow molded bottle 6 Consequently, when the preform 1 is positioned inside the blow mold 378, this region below the neck 4a is in the position closest to the surface of the blow cavity Because of this, because the transverse axis orientation rate is low, the region below the neck 4a tends to become thick, but by amply heating the region below the neck 4a it is possible for it to be molded to the desired thinness To this end, in this preferred embodiment, as well as the fifth and sixth barlike heaters 352e and 352f being disposed in positions where they face the region below the neck 4a of the preform 1, the heat-radiating surfaces of these heaters are disposed closer to the region below the neck 4a than the other heaters are to the preform 1
As shown in Fig 20, two sprockets 360a and 360b are disposed inside the heating box cover 350 of this heating section 306, and an autorotation drive chain 358 runs around these two sprockets 360a and 360b This autorotation drive chain 358 also meshes with the autorotation sprocket 348 on
the carrier member 330 that has been carried into the heating section 306 As a result of this arrangement, when the autorotation drive chain 358 is driven, the autorotation sprocket 348 rotates, this rotation is transmitted by way of the cylinder 342 to the preform 1, and the preform 1 is rotated
As a result, when the preform 1 is carried into the heating section 306, the bottom portion 3 and the trunk portion 4 of the preform 1 receive radiant heat both from the barlike heaters 352a to 352d disposed on one side of the carrying path and from the reflecting plate 356 disposed on the other side of the carrying path, and because the preform 1 is rotated it receives heat substantially uniformly in the circumferential direction and therefore is heated uniformly in the circumferential direction Also, the region below the neck 4a of the preform 1 is amply heated by the fifth and sixth barlike heaters 352e and 352f disposed close to the preform 1 on either side of the carrying path, and furthermore the rotation of the preform 1 ensures that this region below the neck 4a also is heated substantially uniformly in the circumferential direction
Here, as shown in Fig 20, when the preform 1 carrying direction is direction A, the direction of travel of the autorotation drive chain 358 where it meshes with the autorotation sprocket 348 of the carrier member 330 is made direction B, the opposite direction to direction A The reason for this is as follows
If the earner chain 322 and the autorotation drive chain 358 were both to move at the same speed and in the same
direction, direction A, there would be no relative movement between the autorotation sprocket 348 on the carrier member 330 side and the autorotation drive chain 358, and the preform 1 would not rotate at all Even if the running speeds of the earner chain 322 and the autorotation drive chain 358 were to be changed, depending on the sizes of the speeds the rotation of the preform 1 would either be extremely slow or would be reverse rotation These situations will not occur if the autorotation drive chain 358 is driven at a higher speed than the earner chain 322, but normally it is not desirable to rotate it at high speed in this way for reasons relating to moment When rotated at high speed, if the preform 1 is slightly bent, this bend will be made greater by the strong moment it undergoes and this will cause uneven heating of the preform 1 and adversely affect the thickness distribution of the bottle 6
Therefore, in the preferred embodiment shown in Fig 20, by having the carrier chain 322 and the autorotation drive chain 358 run in opposite directions, when the preform 1 is carried in direction A the direction of its autorotation will always be the arrow c direction, and the problems described above are eliminated The preform 1 rotates faster while it is being moved than when it is at a preform 1 stopping position
Also, in this preferred embodiment, the total number of revolutions through which the preform 1 is rotated while it is inside the heating zone inside the heating box cover 350 is made a substantially integral number In this preferred embodiment, 'while the preform 1 is in the heating zone'
refers to the time that the preform 1 spends moving through the distances L1, L2 and L3 (L1+L2+L3 = the heating zone length L), as shown in Fig 20, and the time the preform 1 spends stopped at the two positions shown in Fig 20 L1 is the distance over which the preform 1 is earned between entering the heating zone and the first stopping position, L2 is the distance between the two stopping positions, and L3 is the distance over which the preform 1 is earned between the second stopping position and leaving the heating zone In this preferred embodiment, by making the number of turns through which the preform 1 autorotates in this carrying time and stopped time a substantially integral number of turns, the radiant heat from both sides of the preform 1 carrying path can be received substantially uniformly in the circumferential direction of the preform 1 and temperature variation in the circumferential direction of the preform 1 can thereby be prevented
Also, according to this preferred embodiment, the operation of heating the preform 1 in this heating section 306 can be carried out after any temperature difference between the inner wall and the outer wall of the preform 1 has been sufficiently reduced That is, in this preferred embodiment, the preform 1 is amply cooled from the inner wall side thereof by the injection core mold 50 in the preform molding station 10 As a result, the inner wall temperature of the preform 1 ejected in the preform ejecting section 16 is low, and the outer wall temperature is high However, this preform 1 does not immediately enter the heating section after a short carrying period as in the case of a so-called hot panson or
1-stage apparatus but rather enters the heating section 306 after being transferred by the transfer station 200 and earned stepwise by the carrier member 330 As a result, after the preform 1 is released from the injection molds, a considerably longer cooling time elapses than in a so-called 1-stage apparatus before the preform 1 enters the heating section 306 Because of this, the difference between the temperatures of the inner and outer walls of the preform 1 can be amply moderated This lack of temperature difference between the inner and outer walls l-s the same as in so-called cold panson or 2-stage apparatuses, but because unlike the case in these apparatuses the bottle 6 in this preferred embodiment can be blow molded from a preform 1 still containing heat from when it was injection molded, the preferred embodiment is superior in that less heat energy has to be given to the preforms and therefore energy can be saved Furthermore, with this preferred embodiment, by heating control of preforms 1 cooled to a temperature lower than a blow molding temperature (but considerably higher than room temperature), the stability of the preform temperature from molding cycle to molding cycle is improved and it is possible to reduce the variation in temperature occurring when a plurality of simultaneously injection molded preforms 1 are blow molded non-simultaneously Also, in the apparatus of this preferred embodiment, the carrying pitch at which the preforms 1 are earned by the second circulatory carrier 302 is maintained at a fixed pitch In contrast to this, in conventional cold panson or 2-stage molding machines, the carrying pitch is made smaller when the preforms are heated in
the heating section and the carrying pitch is made larger when they enter the blow molding section The reason why the carrying pitch is made smaller in the heating section is that because it is necessary to heat the preforms all the way from room temperature to the blow molding temperature the total number of preforms inside the heating section is made as large as possible in order to keep the apparatus as small as possible The reason why the carrying pitch is made larger in the blow molding section, on the other hand, is that when a plurality of preforms are to be blow molded simultaneously the distance between the preforms has to be made at least greater than the maximum width of the molded product Also, preforms about to be carried into the blow molding section and preforms having just been carried out of the blow molding section have to standby outside the blow mold clamping apparatus of the blow molding section Because of this, in conventional 1-stage molding machines the carrying pitch has to be changed midway around the carrying path and the apparatus consequently is complex
In contrast with this, in this preferred embodiment apparatus, because bottles 6 are blow molded from preforms 1 which still contain heat from when they were injection molded in the injection molding section 14, the amount of heat energy which has to be given to the preforms 1 in the heating section 306 is very small compared to a 2-stage case As a result, the preforms 1 can be fully reheated to the blow molding temperature without the total number of preforms 1 in the heating section 306 being increased, and it is not necessary for the carrying pitch to be changed midway around the
As shown in Fig 1, in the carrying path between the heating section 306 and the blow molding section 310, one stop of the preform 1 performed by the normal carrying sequence carrying out intermittent drive is allocated to the standby section 308 The provision of this standby section 308 makes it possible to moderate the temperature distribution in the preform 1, which, being made of a synthetic resin, has poor thermal conductivity Like the heating in the heating section 306 in this preferred embodiment apparatus, the heating of the preform 1 is normally carried out from the outside using radiant heat Because of this, the temperature of the inner wall of the preform 1 becomes lower than the temperature of the outer wall In the apparatus of this preferred embodiment, after the preform 1 is carried out of the heating section 306, by stopping the preform 1 at least once in the standby section 308 before it is carried into the blow molding section 310 it is possible to reduce this temperature difference between the inner and outer walls and the blow molding characteristics of the bottle 6 can thereby be stabilized
During this temperature distribution moderation in the standby section 308 it is also possible to perform temperature adjustment of the preform 1 actively By actively performing temperature adjustment of the preform 1 in the standby section 308 it is possible to obtain a temperature distribution which cannot be obtained just by heating the preform 1 while rotating it in the heating section 306
As a temperature adjusting member disposed in the standby section 308, for example a temperature adjusting core 400 which is inserted from below the preform 1 into the preform 1 and performs temperature adjustment from the inner wall side over a temperature adjustment region S can be used, as shown in Fig 23 This temperature adjusting core 400 has a first temperature adjusting core 402 which performs temperature adjustment of the region below the neck 4a of the preform 1 from the inner wall side thereof This temperature adjusting core 400 also has a second temperature adjusting core 404 which performs temperature adjustment on the trunk portion excluding the region below the neck 4a As described above, because it is necessary to adjust the temperature of the region below the neck 4a to a higher temperature than other regions, in Fig 23 the first temperature adjusting core 402 has a larger diameter than the second temperature adjusting core 404 Alternatively, a layer consisting of a material which radiates heat of such a wavelength that it is easily absorbed by the resin material from which the preforms 1 are molded (for example PET) may be coated onto the first temperature adjusting core 402
As shown in Fig 24, the temperature adjusting member can also be made a temperature adjusting pot 410 having a cylindrical portion which can be positioned around the preform 1 In this case, the temperature adjusting pot 410 has blocks 414a to 4!4d divided into zones in the axial direction of the preform 1 by thermal insulation 412, and each of the blocks 414a to 4Hd has an independent temperature adjusting fluid passage 416 whereby independent temperature control of each
zone is carried out Because the temperature adjusting pot 410 can be so positioned that is covers the preform 1, a temperature distribution stepped in the axial direction of the preform 1 can be certainly obtained By this means, it is possible to for example adjust the region below the neck 4a to a high temperature and adjust the bottom portion 3 to a low temperature As shown in Fig 14, it is also possible to apply an internal pressure to the preform 1 by introducing air into the preform 1 in the direction of the arrow 420 and thereby bring the outer wall of the preform 1 and the blocks 414a to 414d into contact and facilitate the temperature adjustment
Also, as this kind of temperature adjusting member, it is possible to use a member which in one or a plurality of locations in the circumferential direction of the preform 1 extend in the axial direction of the preform 1 and impart the preform 1 with a temperature distribution in the circumferential direction thereof For example, as shown in Fig 25, it is possible for example at both sides of the preform 1 to dispose a pair of cooling members 430 along the axial direction of the preform 1 and bring them into contact with the side wall of the trunk portion of the preform 1 using air cylinders 432 or the like When this is done, the preform 1 is given a temperature distribution in the circumferential direction, and for example as shown in Fig 26 it is possible to fully secure the wall thickness required of the high transverse axis drawing rate region of a flat bottle 6 This kind of measure can be applied not only to flat containers but also to for example square containers When a temperature
distribution in the circumferential direction of the preform 1 is to be imparted, besides bringing a cooling member into contact with the preform 1 it is also possible to position a heating member in the vicinity of the preform 1
Blow Moldinq Section 310
The blow molding section 310 has two blow mounting plates 370 mounted on the machine bed 8, one on either side of the preform 1 carrying path As shown in Fig 4, for example four tie bars 372 are mounted crossing between these two blow mounting plates 370 Two blow mold clamping plates 374 which move horizontally along the four tie bars 372 are mounted between the blow mounting plates 370 These two blow mold clamping plates 374 are opened and closed symmetrically about a vertical line by a blow mold clamping mechanism 376, comprising for example hydraulic pistons, mounted on the blow mounting plates 370
A pair of split molds 378a and 378b constituting the blow mold 378 are mounted on these two blow mold clamping plates 374 In the case of the preferred embodiment apparatus shown in Fig 1, because the number n of bottles simultaneously blow molded is n = 1, a cavity for one bottle is formed in the pair of split molds 378a and 378b In the case of the preferred embodiment apparatus shown in Fig 21, because the number n of bottles simultaneously blow molded is n = 2, cavities for two bottles are formed in the pair of split molds 378a and 378b
A cylinder mounting plate 380 is mounted at a position midway along the upper two tie bars 372, and a bottom mold driving cylinder 382 is mounted on this cylinder mounting plate 380 This bottom mold driving cylinder 382 raises and
lowers a bottom mold 384 In this preferred embodiment, because the bottle 6 is blow molded from a preform 1 which is inverted, the bottom mold 384 is made movable up and down above the preform 1
Thus in this preferred embodiment, while raising productivity by injection molding N = 4 preforms 1 simultaneously in the injection molding section 14 of the preform molding station 10, by only molding n = 1 bottle 6 at a time in the blow molding section 310 it is possible to raise the operation rate of the blow cavity mold 378 Also, by reducing the number of cavities in the blow cavity mold 378, which is a relatively expensive type of mold, mold costs, molds being consumable items, can be reduced Furthermore, in this preferred embodiment apparatus, because in the preform molding station 10 the preforms 1 are amply cooled before they are released from the injection molds, and because enough cooling time is provided thereafter for the temperature difference between the inner and outer walls of the preforms 1 to be moderated before the preforms 1 are heated to the blowing temperature, the uniformity of the temperature distribution of the retained heat in the preforms 1 can be increased and the stability of the blow molding can be greatly improved
Bottle Eiectinq Section 312
As shown in Fig 1 and Fig 4, the bottle ejecting section 312 is disposed in the carrying path of the earner members 330 earned by the second circulatory earner 302 between the blow molding section 310 and the preform receiving section 304 This bottle ejecting section 312 has a neck
holding mechanism 390 having for example a similar construction to that of the neck holding mechanisms 232 employed in the inverting and handing over mechanism 230 This neck holding mechanism 390 holds the neck portion of the inverted bottle 6 by means of a pair of holding members As shown in Fig 3 and Fig 4, there are also provided a raising and lowering drive device 392 which raises and lowers this neck holding mechanism 390 and an inverting drive device 394 which inverts the neck holding mechanism through an angle of 180° By the neck holding mechanism 390 being raised by the raising and lowering drive device 392, the neck portion of the bottle 6 is pulled upward off the carrying pin 346 of the carrier member 330 After that, by this holding mechanism 390 being rotated through 180° by the inverting device 394, the bottle 6 is brought into an upright state to one side of the machine bed 8, and by the pair of holding members of the neck holding mechanism then being opened, the bottle 6 is discharged to outside the apparatus
When Simultaneous Moldinq Numbers Are N = 6, n = 2 Fig 21 is a plan view of a preferred embodiment apparatus wherein the simultaneous molding numbers are N = 6, n = 2 The preferred embodiment shown in Fig 21 differs from the preferred embodiment apparatus shown in Fig 1 in the following points
First, because the blow molding section 310 is to simultaneously blow mold two bottles 6 at a time from among the N = 2 simultaneously injection molded preforms, the blow cavity mold 378 has two blow cavities spaced an array pitch P3 apart The array pitch at which the earner members 330
carned by the second circulatory earner 302 are spaced apart is the same pitch as the array pitch P3 of the blow cavities in the blow molding section 310 Also, the total number of earner members fitted to the earner chain 322 constituting the second circulatory earner 302 is twenty, twice as many as in the case of the preferred embodiment shown in Fig 1 Enough preforms 1 for two blow molding cycles, 2 x n = 4 preforms 1, are stopped inside the heating section 306 In the standby section 308, enough preforms 1 for one blow molding cycle, n = 2 preforms 1, are made to standby The earner chain 322 and the earner members 330 used in the preferred embodiment apparatus of Fig 21 are the same as those used in the preferred embodiment apparatus shown in Fig 1, and it is only the positions and pitch at which the carrier members 330 are fitted to the earner chain 322 that are different
In the preferred embodiment apparatus shown in Fig 21, in the transfer station 200, the number n = 2 of preforms 1 simultaneously blow molded in the blow molding section 310 are simultaneously transferred For this, a transfer pitch converting operation, which will now be explained with reference to Fig 22, is necessary In Fig 22, six preforms 1 simultaneously injection molded in the injection molding section 14 of the preform molding station 10 are shown as preform 1a to preform 1f In Fig 22, the first row on the right shows the array pitch of the preforms 1 injection molded in the preform molding station 10 The array pitch of the preforms 1 at this time is the same as the array pitch P1 of the core pins 52 of the injection molding section 14 The
second row from the right in Fig 22 shows the state of the preforms 1 before they are received by the inverting and handing over mechanism 230 of the transfer station 200 The array pitch of the preforms 1 here is also the pitch P1 The third row from the right in Fig 22 shows the state of two preforms 1 received by the preform receiving section 304 of the blow molding station 300 The transfer of these two preforms 1 is carried out using the two pairs of neck holding members 234 shown in Fig 4 The array pitch of the preforms 1 received by the preform receiving section 304 is the same as their array pitch P3 in the blow molding section 310
Here, in the transfer station 200, when the two preforms 1 are transferred by the two pairs of neck holding members 234, first, for example the first and fourth preforms 1a and id are held That is, the two preforms 1a and 1d are held and the two preforms 1b and 1c are ignored this time As a result, the array pitch P2 of the neck holding members 234 at this time is P2 = 3 x P1 This pitch conversion from the pitch P2 to the pitch P3 is carried out by the array pitch of the two neck holding mechanisms 232 being converted by the pitch change drive device 254 shown in Fig 14 Similarly thereafter, by the second and fifth preforms 1b and 1e being transferred and then the third and sixth preforms 1c and 1f being simultaneously transferred after that, the operation of transferring of the six simultaneously molded preforms 1 is completed
When the simultaneous molding numbers N, n are made N = 4, n = 2, the transfer operation in the transfer station 200 is earned out with pitch conversion from the pitch P2 = 2 x
preforms 1 are cooled by the injection core mold 50 even after
being released from the injection cavity mold 42 and then blow
molded thereafter, the time required for molding a preform for
this kind of general-purpose medium-sized container is
shortened to about 3/4 of that of a conventional injecting
stretch blow molding machine, and an injection molding cycle
time of approximately 10 to 15 seconds is sufficient
Therefore, if this injection molding cycle time (approx
10 to 15 seconds) is T1 and the blow molding cycle time (3 6
to 4 0 seconds) is T2, the ratio T1 T2 is about 3 1, and it is
established that in order to efficiently mold general-purpose
medium-sized containers the simultaneous molding numbers N and
n should ideally be set in accordance with this ratio When
a large container is to be molded from a thicker preform an
injection molding cycle time of 16 seconds or more is suitable
and the ratio N n can be set to around 4 1 When a small
container is to be molded from a thin preform the injection
molding cycle time is shortened and consequently the ratio N n
can be set to for example 4 2
Thus, if N/n is set to 3, the injection molding cycle and the
blow molding cycle will be suitable for molding medium-sized
containers, for which the market demand is the greatest, and
a blow molding machine with little waste in the molding cycles
Intermediate Preform Discharqe Mechanism
In this preferred embodiment, as shown in Fig 2 and Fig
machine bed 8 where the transfer station 200 is disposed
formed inside the machine bed 8, and this chute 8b leads to a preform discharge opening 8c formed in the side of the machine bed 8
With this type of hot panson blow molding machine there are various situations wherein it is desirable that the transfer to the blow molding station 300 of the preforms 1 being molded in the preform molding station 10 be stopped For example, when the whole blow molding machine is started up, until the preform 1 injection molding characteristics stabilize it is preferable that the imperfect preforms 1 being produced at this stage not be supplied to the blow molding station 300 Also, when for some reason trouble has arisen in the blow molding station 300 it is preferable that only the operation of the blow molding station 300 be stopped and that the operation of the preform molding station 10 not be stopped so that preforms 1 continue to be molded This is because there are various heating parts in the preform molding station 10 and consequently once the preform molding station 10 is shut down a considerable amount of time is required to start it up again
In this preferred embodiment, when such a situation arises, the preforms 1 continuing to be injection molded in the preform molding station 10 are discharged to the side of the machine bed 8 through the above-mentioned preform dropout opening 8a, the chute 8b and the discharge opening 8c instead of being transferred to the blow molding station 300 by the transfer station 200 This preform 1 discharging operation can for example be carried out by the pair of neck holding members 234 of the inverting and handing over mechanism 230
taking hold of the preforms 1 as usual but then, without inverting them through 180°, moving the preforms 1 for example horizontally to a predetermined position above the preform dropout opening 8a in the machine bed 8 and then simply releasing the preforms 1
This preferred embodiment, as sequence control modes, has a bottle molding operating mode wherein the preforms 1 are transferred to the blow molding station 300 and blow molding of the bottles 6 is performed, and a preform molding operating mode wherein the preforms 1 are not transferred to the blow molding station 300 It is possible to change over from the normal bottle molding operating mold for example automatically when an abnormality is detected by a sensor or the like or by an operator flicking a manual switch When the apparatus is switched over to the preform molding operating mode the operation of the transfer station 200 changes o^er to the operation of carrying the preforms 1 to the preform dropout opening 8a as described above, and no further preforms 1 are transferred to the blow molding station 300
This invention is not limited to the preferred embodiment described above, and various modifications can be made within the scope of the invention
In the preferred embodiment described above, the rotary disc 30 carried both the injection core mold 50 and the neck cavity mold 60, but for example in cases such as when the shape of the neck portion 2 does not form an undercut with respect to the mold-release direction it is not always necessary to use the neck cavity mold 60 When the neck cavity mold 60 is not used, after the preforms 1 are released
from the injection cavity mold 42 in the injection molding section 14, the preforms 1 can be earned to the preform ejecting section 16 by the injection core mold 50 alone Because the preforms 1 contract around the core pins 52 of the injection core mold 50 as they cool they can be smoothly released from the injection cavity mold 42, and the preform 1 can be earned by the injection core mold 50 even without there being any undercut at the neck portion 2
In the preform ejecting section 16, to remove the injection core mold 50 from the preforms 1, for example the core pins 52 of the injection core mold 50 can be provided with a function enabling them to introduce air for -ejection into the preforms 1 When this is done, in the preform ejecting section 16, by blowing air from the core pins 52 into the preforms 1 after they are cooled by the injection core mold 50, the preforms 1 can be caused to drop downward by this air pressure
According to the invention as set forth in claims 1 to 12, as well as the injection molding cycle time being shortened and the cycle time of the whole apparatus also being shortened, by stabilizing the cooling process the amount of heat retained by the preforms is stabilized and the wall thickness distributions of the successively blow molded containers can be made stable Also, if the simultaneous blow molding number n is made less than the simultaneous injection molding number N, fewer blow mold cavities are required, and the cost of molds, which are consumable parts, can be reduced Furthermore, because the N preforms simultaneously injection molded within the shortened molding cycle time are blow molded
over a : urality of blow molding cycles, the operation rate of the n :i/ities of the blow cavity mold increases
-ziording to the invention as set forth in claim 13, because :he preforms are molded in an upright state, vertical mold-: imping can be employed and space is therefore saved, and bs-iise the injection apparatus can be disposed directly on the -achine bed the installation is stable Also, because the p'~arms are carried to the blow molding section in an invert:: state, the preforms can be easily supported using the openi"; in their neck portions, and drawing rods and blow core -I'ds and the like can be disposed in a space in the machine zed below the preform carrying path
herding to the invention as set forth in claims 14 and 15, b": -:::rding to the invention as set forth in claim 16, because all the preforms simultaneously molded in one injec" :~ molding cycle can be used in a plurality of blow moldi"' :ycles and are not mixed with preforms molded in the next -,ection molding cycle, molding stability can be secure:
-:::rding to the invention as set forth in claim 17, while "- region below the neck, which needs to be given the most r-.:' energy, can be efficiently heated, other regions can be hea~-: in an energy-saving manner
-.::-ding to the invention as set forth in claims 13 and 19, i- :e the heating section, both when the preforms are
stopped and when they are moving the preforms can be certainly rotated and the occurrence of temperature unevenness can be prevented
According to the invention as set forth in claim 20, the temperature gradient between the inner and outer walls of the preform before blow molding can be moderated, and a container can be blow molded from a preform whose inner and outer walls are both set to a suitable blowing temperature
According to the invention as set forth in claims 21 to 24, temperature adjustment of the preforms can be actively carried out while the temperature gradients therein are being moderated, and the blow molding characteristics can thereby be further improved
According to the invention as set forth in claims 25 to 27, because the preforms can be discharged to outside the apparatus instead of being transferred to the blow molding section, wasteful blow molding of containers from imperfect preforms of unstable quality during starting up of the apparatus can be prevented, and because when there is trouble or adjustments have to be made in the blow molding section, the preform molding section does not have to be shut down, the problem of time being wasted in starting up the apparatus again when the operation of the blow molding section is stopped is eliminated
1. An injection stretch blow molding method for blow molding containers from preforms retaining heat from when the preforms were injection molded, comprising the steps of:
releasing the preforms, molded using at least an injection core mold and an injection cavity mold, from the injection cavity mold; with the preforms held by the injection core mold, carrying the injection core mold to an ejecting section along a first carrying path at a first pitch (PI) while the preforms are cooled by the injection core mold;
transferring the preforms, which are ejected to carrier members to be carried along a second carrying path;
in the blow molding section, simultaneously blow molding said containers from the preforms in a blow mold clamped relative to the preforms.
in the step of blow molding, the containers are simultaneously blow molded from the preforms using blow cavities arrayed at a blow molding pitch (P3) which is larger than the first pitch (PI);
the step of transferring the preforms is carried out by a process of pitch changing and simultaneously transferring the preforms to the carrier members being repeated a plurality of times.
2.	An injection stretch blow molding method as claimed in claim 1, wherein between releasing of the preforms from the injection core mold and starting of blow molding allowing the preforms to cool down for a period of time sufficient for a temperature difference between inner and outer walls of the preforms to be moderated.
3.	An injection stretch blow molding method as claimed in claim 2, wherein the step of ejecting the preforms is carried out after the preforms are cooled by the injection core mold to a temperature lower than a temperature which is suitable for blow molding; and said method comprising a step of heating the preforms in the second carrying path along which said preforms are carried to the blow molding section.
4.	An injection stretch blow molding method as claimed in claim 1, wherein said preforms are made of polyethlene terephtalate; and wherein the number of the preforms in the step of releasing the preforms is three times of the number of performs in the step of blow molding.
5.	An injection stretch blow molding method as claimed in claim 4, wherein in the step of injection molding, each of said preforms which is injection molded has the maximum wall thickness of 3.0 mm to 4.0 mm at a barrel portion.
6.	An injection stretch blow molding method substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
207-del-2003-abstract.pdf
207-del-2003-claims.pdf
207-del-2003-complete specification (as files).pdf
207-del-2003-complete specification (granted).pdf
207-del-2003-correspondence-others.pdf
207-del-2003-correspondence-po.pdf
207-del-2003-description (complete).pdf
207-del-2003-drawings.pdf
207-del-2003-form-1.pdf
207-del-2003-form-13.pdf
207-del-2003-form-2.pdf
207-del-2003-form-3.pdf
207-del-2003-form-4.pdf
207-del-2003-gpa.pdf
207/DEL/2003
NISSEI ASB MACHINE CO.,LTD