Abstract:
A heat-resistant container molding apparatus and method which are compact and inexpensive and can reliably increase the crystallinity, reduce the residual stress in a container filled with a hot content such as thermally sterilized fruit juice, and prevent a thermal deformation with improved container stability at a raised temperature. The apparatus has a receiving and removing unit for receiving primary moldings obtained by blow-molding preforms and for removing final products, a heat treatment section for heating the primary moldings by bringing the primary moldings into contact with the inner wall of a heat treatment mold while pressurizing the interior of the primary moldings within the heat treatment mold, a final molding section for blow molding intermittent moldings into final products within a final blow mold, and a rotary plate, neck support fixing plate and neck support member for conveying the moldings through the receiving and removing unit, heat treatment section and final molding section.

Description:
This is a Division of application Ser. No. 08/980,373 filed Nov. 28, 1997, now U.S. Pat. No. 5,975,880, which in turn is a Continuation of application Ser. No. 08/544,544 filed Oct. 18, 1995, abandoned. The entire disclosure of the prior application(s) is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method of molding a heat-resistant container particularly from a synthetic resin such as polyethylene terephthalate (which will be called “PET”). 
     2. Description of the Prior Art 
     In general, a synthetic resin thin-walled packaging container known as biaxial stretching blow molded container is formed by positioning an injection-molded or extruded preform having an appropriate temperature for stretching within a mold and stretching the preform in its longitudinal direction corresponding to the longitudinal axis of the container while at the same time expanding the same preform in its lateral direction under the action of a pressurized gas blown into the mold. 
     Depending on selection of a material used to form the container, however, a problem was raised in that the container deformed when it was filled with a hot content such as a thermally sterilized fruit juice beverage. 
     To overcome such a problem, a proposal such as the applicant&#39;s Japanese Patent Application Laid-Open No. 3-205124 has been made in which the blow molding step to be executed after the temperature of the preform has been regulated is divided into primary and secondary sub-steps. In the primary blow molding sub-step, a primary molding is formed in the desired form of a container. The primary molding is thermally processed to shrink and then subjected to the secondary blow molding sub-step to form the final container. 
     Such a proposed molding process can provide a heat-resistant container which is improved in mechanical strength through the thermal treatment before the secondary blow molding sub-step. 
     More particularly, the thermal treatment before the secondary sub-step removes a strain produced at the primary blow molding sub-step or a residual stress due to stretching, and crystallizes the oriented walls to a higher level. This improves the heat resistance of the final product which may be placed under a severe temperature condition in markets. 
     To attain such a heat-resistant container, it is required that the temperature of the primary molding has been increased sufficiently to improve the crystallinity in the primary molding at its oriented walls. 
     However, the prior art could not smoothly increase the temperature of the molding since the necessary heat was only transmitted to the molding through radiation within an atmosphere. 
     Therefore, a long time is required until the temperature of the molding reaches a level that can provide the necessary crystallinity for the molding to have its sufficient heat resisting property. Thus, time for heating or conveying the molding must be prolonged. This may extend the molding cycle or increase the dimensions of the container molding apparatus including the heating conveyor path. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an inexpensive and compact apparatus and method of molding a heat-resistant container to be filled with a hot content such as a thermally sterilized fruit juice, which can increase the crystallinity of the container and also reduce the residual stress thereof in a reliable and short manner, resulting in improvement of the form stability at high temperature to avoid a thermal deformation. 
     Another object of the present invention is to provide a heat-resistant container molding apparatus and method of molding a heat-resistant container in an efficient blow molding manner without thermal loss. 
     Still another object of the present invention is to provide a heat-resistant container molding apparatus and method of molding a heat-resistant container, in which when a plurality of steps using clamping mechanisms are used, it can be prevented to increase the installation space due to a stroke required to open and close the respective mold. 
     A further object of the present invention is to provide a heat-resistant container molding apparatus and method of molding a heat-resistant container, in which a preform can be sufficiently cooled such that the blow molding step will not be influenced by the heat history of an injection molded preform. 
     To accomplish these objects, the present invention provides a heat-resistant container molding apparatus comprising: 
     a primary molding section for blow-molding preforms into primary moldings by using a primary blow mold having split molds; 
     a heat treatment section for heat treating the primary moldings to obtain intermediate moldings by bringing the primary moldings into contact with inner walls of a heat treatment mold having split molds while pressurizing an interior of each of the primary moldings within the heat treatment mold; and 
     a final molding section for blow-molding the heat treated intermediate moldings into final products within a heated final blow mold having split molds. 
     According to the present invention, the heat transfer is carried out by heating the primary molding in direct contact with the inner wall of the heat treatment mold while pressurizing the interior of the primary molding. Therefore, the temperature of the molding can efficiently be increased for a short time. At the same time, the apparatus can be compacted. In addition, the residual stress produced in the primary molding can reliably be removed for a short time to increase the crystallinity of the primary molding. As a result, the form stability can be improved at a raised temperature reliably to prevent a container from being thermally deformed when the container is filled with a hot content such as a thermally sterilized fruit juice beverage or the like. 
     Since the heat shrinkage and thus uneven wall thickness is prevented by pressurizing the interior of the primary molding within the heat treatment mold, an uneven wall thickness and irregular heat resistance can reliably be prevented at the final blow molding step. Thus, a desired heat can certainly be provided to the molding without variability. This can stabilize the shrinkage in the intermediate molding after being heat-treated. Consequently, the wall-thickness distribution of the final product can also be stabilized. 
     In the final molding section after the heat treating step, a strain in the final product can be removed by heat treating it within the final heated blow mold when the intermediate molding is blow-molded into the final product in the final heated blow mold. Thus, the heat stability can be improved to increase the heat resistance in the final product. 
     In the apparatus of the present invention, it is preferred that it comprises a receiving section for receiving the preforms to be primarily molded and a removing section for removing the final products and wherein the primary molding, heat treatment and final molding sections being located adjacent to one another. 
     Since the primary molding, heat treatment and final molding sections are sequentially positioned, the final blow molding step can be carried out immediately after the heat treating step while maintaining the heat in the heat treated molding. Thus, the blow molding step can efficiently be performed without heat loss. 
     It is also preferable that the apparatus of the present invention further comprises conveyor means for intermittently conveying a given number of preforms to be simultaneously molded to the primary molding section and a given number of moldings to be simultaneously molded to the heat treatment and final molding sections respectively, and wherein each of the primary molding, heat treatment and final molding sections includes a mold clamping mechanism for clamping the split molds, the primary molding, heat treatment and final molding sections are rectilinearly disposed in a transfer direction. 
     Such mold clamping mechanisms require a stroke of opening and closing the split molds and thus an increased installation space. If the mold clamping mechanisms are disposed opposed to one another, the spacing between the adjacent conveyor means will unnecessarily be increased. This will also increase the installation space. 
     When the primary molding, heat treatment and final molding sections respectively having the mold clamping mechanisms are rectilinearly disposed in the direction of conveyance as in the present invention, the strokes of opening and closing the split molds can rectilinearly be taken in the same direction. Since the strokes of opening and closing the split molds in the mold clamping mechanisms are avoided from overlapping in the opposed direction, the installation space can be minimized. By executing the heat treatment using the heat treatment molds, further, the heat treatment can efficiently be carried out for a short time. 
     In such a case, it is preferable that the split molds of the heat treatment mold in the heat treatment section have cavity configuration substantially equal to that of the primary blow mold in the primary molding section and a mechanism for heating the heat treatment mold to a heat treatment temperature. 
     Since the primary moldings are brought into contact with and heated by the heat treatment molds which have been heated to the necessary heat treatment temperature by the heating mechanism, the temperature of the primary moldings can efficiently be raised for a short time. Further, the residual stress produced at the primary molding section can certainly be removed for a short time to provide an improved crystallinity. As a result, the form stability at a raised temperature can be improved certainly to avoid a container from being thermally deformed when it is filled with a high temperature content. 
     It is further preferable that the conveyor means forms a substantially rectangular conveyor path and the primary molding, heat treatment and final molding sections are disposed on a long side of the rectangular conveyor path. 
     In such an arrangement, the spacing between the long opposite sides of the conveyor path can be minimized to reduce the entire installation space. 
     It is further preferable that the receiving section is disposed on a short side of the conveyor path. 
     By disposing the primary molding, heat treatment and final molding sections requiring the mold opening/closing spaces on the one longer side of the conveyor path as described, a given spacing between the longer opposed sides of the conveyor path can be provided. If the receiving and removing sections are disposed on one shorter side of the conveyor path, the distance between the longer opposed sides of the conveyor path can be reduced. 
     It is preferable in this case that the receiving section is used as a removing section for removing final products. 
     The heating and heat treating sections need relatively longer time, while the receiving and removing steps in the receiving and removing sections do not relatively consume time. Therefore, such a single receiving/removing section can contribute to reduce the installation space. 
     It is further preferable that a plurality of heating units for heating preforms are disposed between the receiving section and the primary molding section. 
     Thus, the preform heating time can be sufficiently secured such that the preforms will certainly be heated to the blow molding temperature. 
     It is further preferable that the present invention includes a plurality of heating units for heating preforms received at the receiving section and wherein the plurality of heating units are disposed on at least one side of the conveyor path excluding the long side on which the primary molding, heat treatment and final molding sections are disposed. 
     Thus, the conveyor path of a conveyor having no mold clamping mechanism can effectively be used to secure an appropriate heating distance and thus a sufficient heating time. 
     In such a case, it is preferable that each of the heating units has a rotary mechanism for rotating the preforms. 
     The heating unit can uniformly heat the preform around the circumference thereof while being rotated by the rotary mechanism. This can avoid any uneven wall thickness in the product during the blow molding step. 
     It is further preferred that the conveyor means includes carrier members for conveying moldings to be simultaneously molded upside down and a conveyor chain mounted on the carrier members and engaged with sprockets which are disposed in the conveyor path at corners thereof, each of the carrier members having a rotating sprocket engaged with preform rotating means in each of the heating units. 
     In such an arrangement, the moldings are supported upside down on the respective carrier members and conveyed to the respective molding sections by the conveyor chain engaging the sprockets. At the same time, the carrier members and thus associated moldings are rotated about their own axes by the rotating sprockets engaging the preform rotating means at the respective heating units. Thus, the moldings can be heated uniformly around their circumferential direction to avoid any uneven wall thickness during the blow molding step. 
     In another aspect, it provides a heat-resistant container molding apparatus for molding a heat-resistant container, comprising: 
     a preform molding section for injection-molding preforms; 
     a heat-resistant container molding section for blowmolding the preforms into heat-resistant containers; and 
     a conveyor line for conveying the preforms to the heat-resistant container molding section after removing the preforms from the preform molding section, the conveyor line including cooling means located at least at an upstream side for cooling the preforms. 
     According to this aspect, the preform removed from the preform molding section is conveyed to the heat-resistant container molding section through the conveyor line. In the heat-resistant container molding section, the preform is blow-molded into a heat-resistant container. During transfer through the conveyor line, the preform is forcedly cooled at least at the upstream side by the cooling means. This can avoid a sticking between adjacent preforms during transfer and also sufficiently cool the preforms through a short transfer distance. 
     It is preferable that the conveyor line includes preform rotating and conveying means for conveying the preforms while rotating them. 
     Thus, the preforms can be cooled uniformly around their circumference by rotating them through the preform rotating and conveying means while conveying in the conveyor line. 
     It is preferable that the preform rotating and conveying means includes upstream intermittent conveying means for intermittently conveying preforms to be simultaneously molded and downstream continuous conveying means for continuously conveying the preforms from the upstream intermittent conveying means. 
     Thus, the simultaneously injection-molded preforms from the upstream intermittent conveying means can be conveyed while maintaining a pitch between adjacent preforms during the injection molding step or preventing a sticking therebetween. The downstream continuous conveying means can convey the preforms in close contact with one another. This can avoid any excess transfer while securing sufficient preforms. 
     It is also preferable that the conveyor line provides a transfer distance and time which allow preforms to be cooled to a temperature sufficiently lower than a blow-molding temperature. 
     Thus, the blow molding step will not be influenced by the heat history of the injection-molded preforms. According to the present invention, further, the conveyor line can more compactly be formed by conveying the preforms, unlike the prior art machines wherein the primary moldings are conveyed. 
     The present invention further provides a method of molding a heat-resistant container, comprising: 
     a primary molding step for blow-molding injection molded preforms into primary moldings in a primary blow mold; 
     a heat treating step for heat treating the primary moldings to obtain intermediate heat treated moldings by bringing the primary moldings into contact with an inner wall of a heat treatment mold while pressurizing an interior of each of the primary moldings within the heat treatment mold; and 
     a final molding step for blow-molding the intermediate heat treated moldings into final products in a final blow mold. 
     According to the present invention, any residual stress produced in the primary molding step can certainly be removed to provide an improved crystallinity by heat treating the primary molding obtained by the primary blow molding step within the heat treatment mold at the heat treating step. As a result, the form stability can be improved at a raised temperature reliably to avoid any thermal deformation in a container when it is filled with a hot content. 
     It is preferable that the method of the present invention also comprises the steps of: 
     receiving preforms prior to the primary molding step; and 
     removing final products after the final molding step. 
     It is also preferable that a plurality of preform heating steps are carried out between the receiving step and the primary molding step. 
     Each of the plurality of preform heating steps includes the step of rotating the preforms while heating them. 
     It is further preferred in the present invention that a primary molding has a height slightly larger than that of a final product and a diameter slightly smaller than that of the final product barrel, thereby providing a margin compensating the heat shrinkage when the primary molding is thermally treated. In such a case, it is preferable that the intermediate molding after heat treated is formed into a size slightly smaller than that of the final product and has a sufficient wall-thickness distribution in its height direction. Thus, the intermediate molding will not be pinched in its diametrical direction by the final blow mold when it is closed. By providing the intermediate molding having its size slightly larger than that of the final product, thus, the intermediate molding will not be stretched in the final blow molding step. Therefore, only a few strain can be produced in the final blow molding step. Additionally, the strain thus produced can substantially completely be removed by heating the final blow mold. As a result, the heat stability can be improved in the final product. 
     If the heat treatment step is so designed that the intermediate molding has its size substantially equal to or slightly smaller than that of the final product, depending on the heat treatment temperature and time, the intermediate molding can be controlled at the heat treatment step such that it has a size substantially equal to or slightly smaller than that of the final product. 
     Where a primary molding has its cylindrical barrel having substantially no tongued and grooved face, the barrel may have no axial undercut and be formed with a circumferentially integral pot-shaped part corresponding to the cylindrical barrel of the heat treatment mold. Thus, only the shoulder of the primary molding can be formed through a split mold, resulting in minimization of the other expensive split mold sections. Furthermore, this permits a large-sized mold clamping mechanism to be omitted, thereby reducing the manufacturing cost of the entire system and its installation area. 
     If the heating temperature at the final blow mold is equal to or higher than a desired heat-resisting temperature, the heat stability at that heat-resisting temperature can be improved to avoid any deformation in a container thereat. 
     It is further preferable that the primary molding has a diameter larger than that of the final product and a height about 10% larger than that of the final product. Thus, the intermediate molding can be formed such that it will have a size substantially equal to or slightly smaller than that of the final product through the shrinkage after the heat treatment of the primary molding. This prevents the molding from being pinched by the final blow mold. 
     If the heat treatment time in the heat treating step is set between five seconds and ten seconds, the size of the intermediate molding can be stabilized while shortening the molding cycle. More particularly, if the heat treatment time is less than five seconds, the shrinkage in the intermediate molding will be unstable to scatter the size of the intermediate molding. If the heat treatment time exceeds ten seconds, the molding cycle becomes too long. It is thus preferable that the heat treatment time is in the range of five to ten seconds. 
     If the blow molding time in the final molding step is set between five seconds and fifteen seconds, a practical heat-set effect can be provided to minimize the molding cycle. 
     According to a further aspect, the present invention provides a method of molding a heat-resistant container, comprising: 
     a preform molding step for injection-molding preforms; 
     a conveying step for removing the injection molded preforms from the preform molding step and conveying the preforms to a conveyor line; and 
     a heat-resistant container molding step for receiving and heating the preforms conveyed by the conveyor line and subsequently blow-molding the preforms into heat-resistant containers, the conveying step including a cooling step located at least at an upstream side of the conveyor line for cooling the preforms. 
     In such an arrangement, the conveying step preferably includes the step of rotating the preforms while conveying them. 
     In a further aspect, the present invention provides a heat-resistant container molding apparatus for molding a heat-resistant container, comprising: 
     a receiving section for receiving primary moldings obtained by blow-molding preforms; 
     a heat treatment section for bringing the primary moldings received by the receiving section into contact with an inner wall of a heat treatment mold and for heat treating the primary moldings while pressurizing an interior of each of the primary moldings within the heat treatment mold, whereby intermediate moldings are obtained; 
     a final molding section for blow-molding the intermediate heat-treated moldings into final products in a heated final blow mold; 
     a removing section for removing the final products; and 
     conveyor means for conveying the moldings to the receiving, heat treatment, final molding and removing sections. 
     According to this aspect, the apparatus is defined by the primary molding receiving section, the heat treatment section, the final molding section and the removing section which are separated from one another. This enables the injection-molding and primary blow molding devices to be omitted from the apparatus of the present invention, resulting in a compacted system. If an existing blow-molding machine is used as a primary molding device, a heat-resistant container molding system can simply be formed only by connecting the apparatus of the present invention to that blow molding machine. 
     It is preferred in the present invention that receiving and removing unit replaced with the receiving and removing sections, heat treatment section and final molding section are disposed at three points which are equidistant from a center point and wherein the conveyor means comprises split type neck support members for grasping necks of the moldings, a neck support fixing plate formed by a split plate for holding and allowing the neck support members to be open and closed, and a rotary plate for supporting the neck support fixing plate at positions corresponding to the receiving and removing unit, heat treatment section and final molding section and for rotatably conveying the neck support fixing plate to positions corresponding to the receiving and removing unit, heat treatment section and final molding section. 
     Thus, the molding can be moved to the receiving and removing unit, heat treatment section and final molding section merely by intermittently rotating the rotary plate through 120 degrees. This can simplify the conveying means. If the receiving and removing unit, heat treatment section and final molding section are disposed within the rotating locus of the rotary plate, the respective sections can efficiently be disposed to improve the installation space. 
     It is further preferably that the conveying means has a rectilinear conveyor path and the heat treatment section is located adjacent to the final molding section on the rectilinear conveyor path. 
     Thus, the primary molding is heat treated and finally blow molded along the rectilinear conveyor path. The final blow molding step can be carried out immediately after the heat treatment step while maintaining the heat treat. The blow molding step can efficiently be performed without heat loss. 
     In a further aspect, the present invention provides a method of molding a heat-resistant container, comprising: 
     a receiving step for receiving primary moldings obtained by blow-molding preforms; 
     a heat treating step for bringing the primary moldings received by the receiving step into contact with an inner wall of a heat treatment mold and for heat treating the primary moldings while pressurizing an interior of each of the primary moldings within the heat treatment mold, whereby intermediate moldings are obtained; 
     a final molding step for blow-molding the intermediate heat-treated moldings into final products in a heated final blow mold; and 
     a removing step for removing the final products. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of one embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     FIG. 2 is a longitudinal sectional view of a carrier member shown in FIG.  1 . 
     FIG. 3 is a plan view of another embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     FIG. 4 is a fragmentary plan view, on an enlarged scale, of the conveyor line shown in FIG.  3 . 
     FIG. 5 is a longitudinal sectional view taken along a line V—V in FIG.  4 . 
     FIG. 6 is a plan view, on an enlarged scale, of the receiving/removing section shown in FIG.  4 . 
     FIG. 7 is a side view as viewed in a direction of arrow VII in FIG.  6 . 
     FIG. 8 is a side view as viewed in a direction of arrow VIII in FIG. 6, showing the receiving/removing section under its reception state. 
     FIG. 9 is a side view showing the receiving/removing section of FIG. 8 under its removal state. 
     FIG. 10 is a plan view of one embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     FIG. 11 is a vertical sectional view taken along a line II—II in FIG.  10 . 
     FIGS. 12A,  12 B and  12 C are respectively front, side and top views of the receiving/removing section. 
     FIG. 13 is a longitudinal sectional view showing a primary molding supported at the receiving/removing section. 
     FIG. 14 is a perspective view of the heat treatment molds in the heat treatment section. 
     FIG. 15 is a longitudinal sectional view through one of the heat treatment molds shown in FIG.  14 . 
     FIGS. 16A and 16B are respectively front and plan views showing the heat treatment core molds in the heat treatment section. 
     FIG. 17 is a front view of the blow core mold in the final molding section in up and down states. 
     FIG. 18 is a longitudinal sectional view of the final blow mold in the final molding section. 
     FIG. 19 illustrates one embodiment of a method for molding a heat-resistant container in accordance with the present invention. 
     FIG. 20 illustrates a part of another embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     FIG. 21 illustrates-a part of still another embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Several preferred embodiments of the present invention will now be described in detail with reference to the drawings. 
     FIG. 1 is a view of one embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     The heat-resistant container molding apparatus is so designed as to heat and blow mold preforms which have been injection molded by a separate injection molding machine. 
     The apparatus comprises a receiving/removing section  202 , first to fourth heating sections  204 ,  206 ,  208  and  210 , a primary molding section  212 , a heat treatment section  214  and a final molding section  216 , all of which are arranged along a loop-like conveyor means  200 . 
     The conveyor means  200  intermittently moves to carry a given number of every moldings to be simultaneously molded by this heat-resistant container molding apparatus (four in this embodiment), such as preforms from the receiving/removing section  202 , primary moldings from the primary molding section  212  and final products from the final molding section  216 , from the receiving/removing section  202  through the first to fourth heating sections  204 ,  206 ,  208  and  210 , primary molding section  212  and heat treatment section  214  to the final molding section  216 . The conveyor means  200  forms a substantially rectangular conveyor path along which a pair of conveyor rails  218  are disposed. The conveyor rails  218  are in engagement with the carrier members  220  at eight points spaced away from one another with a given pitch for every set of four moldings to be simultaneously formed. 
     Each of the carrier members  220  comprises a fixing portion  222  and a placement base  224 , as shown in FIG.  2 . The fixing portion  222  engages the conveyor rails  218  through cam followers  226  and also a conveyor chain  230  passing around conveyor sprockets  228  which are disposed in the conveyor path at four corners. When the conveyor chain  230  is driven, the carrier members  220  will be moved. 
     The placement base  224  is rotatably mounted on the fixing portion  222 . The top of the placement base  224  includes a conveyor pin  236  adapted to be inserted into the neck  234  of a preform  232  for supporting the preform  232  upside down. The placement base  224  also includes a preform rotation sprocket  238  through which the placement base  224  and thus the preform  232  supported thereon is rotated. 
     The primary molding section  212 , heat treatment section  214  and final molding section  216  are disposed on one longer side of the rectangular conveyor path formed by the conveyor means  200 . The receiving/removing section  202  is disposed on one shorter side of the rectangular conveyor path adjacent to the final molding section  216 . The first to third heating sections  204 ,  206  and  208  are disposed on the other longer side of the conveyor path while the fourth heating section  210  is disposed on the other shorter side of the conveyor path. 
     The primary molding section  212  blow molds a preform  232  into a primary molding after the preform has been heated through the first to fourth heating sections  204 ,  206 ,  208  and  210 . The primary molding section  212  includes primary blow mold halves  240  defining a split mold. The primary blow mold halves  240  can be clamped and opened by a mold clamping mechanism  242 . 
     The mold clamping mechanism  242  comprises a pair of mold clamping plates  244   a,    244   b,  a movable plate  248 , four tie rods  250  and a pair of driving cylinders  246 . The mold clamping plates  244   a  and  244   b  support the primary blow mold halves  240 , respectively. The movable plate  248  is disposed adjacent to the mold clamping plates  244   a.  The four tie rods  250  extend through the mold clamping plate  244   a  and slidably support it. The mold clamping plate  244   b  is fixedly connected to the movable plate  248  through the four tie rods  250 . The driving cylinders  246  are mounted on the movable plate  248 . Each of the driving cylinders  246  has a piston rod  252  fixedly connected to the mold clamping plate  244   a.  The piston rods  252  move the mold clamping plate  244   a  to the mold clamping or opening position, with the reaction force thereof moving the movable plate  248 . The movement of the plate  248  moves the mold clamping plate  244   b  to the mold clamping or opening position through the tie rods  250 . 
     The heat treatment section  214  heats the primary molding blow-molded by the primary molding section  212  to remove a strain such as residual stress which is produced by the stretching in the primary blow molding step, resulting in improvement of the heat resistance in the molding. The heat treatment section  214  includes heat treatment mold halves  254  defining a split mold. The heat treatment mold halves  254  can be clamped or opened by a mold clamping mechanism  242 . The heat treatment mold halves  254  are substantially of the same configuration as in the primary blow mold halves  240  and will be heated by a heating mechanism (not shown). The heat treatment section  214  heats the primary molding by bringing it into contact with the inner wall of the heat treatment mold halves  254  while pressurizing the interior of the primary molding within the heat treatment mold halves  254 . This shortens the heat treatment time and thus the molding cycle. The mold clamping mechanism  242  is of the same structure as the mold clamping mechanism for the primary blow mold halves  240 . 
     The final molding section  216  blow-molds the primary molding heated by the heat treatment section  214  into a final product and thus includes final blow mold  256  defining a split mold. The final blow mold  256  can be clamped and opened by a mold clamping mechanism  242 . The final molding section  216  heats the final blow mold  256  by a heating mechanism. The primary molding is blow-molded into a final product within the final blow mold  256  heated by the heating mechanism. Thus, a strain produced at the final blow molding step can be removed by heat treatment through the heated final blow mold  256 , resulting in improvement of the heat stability and thus the heat resistance. The mold clamping mechanism  242  is of the same structure as the mold clamping mechanisms used for the primary blow mold halves  240  and heat treatment mold halves  254 . 
     As will be apparent from the drawings, the primary molding section  212 , heat treatment section  214  and final molding section  216  all of which require the motion stroke for clamping and opening the split molds are rectilinearly disposed on one longer side of the rectangular conveyor path defined by the conveyor means  200 . This prevents the spacing between the opposite sides of the conveyor means  200  from being unnecessarily widened, unlike the prior art in which these sections are disposed opposed to one another. Consequently, the distance between the longer sides of the conveyor path formed by the conveyor means  200  can be minimized to save the installation space. 
     The receiving/removing section  202  receives injection-molded preforms  232  and transfers them onto the carrier members  220  in the conveyor means  200 , as shown in FIG.  2 . Further, the receiving/removing section  202  can externally remove the final products formed by the final molding section  216 . For such a purpose, the receiving/removing section  202  includes an appropriate receiving/removing device (now shown). The receiving/removing section  202  is disposed on one shorter side of the rectangular conveyor path defined by the conveyor means  200 , utilizing the length of the shorter sides of the rectangular conveyor path being elongated by the motion stroke in the mold clamping mechanism  242  when the primary molding section  212 , heat treatment section  214  and final molding section  216  are disposed on one longer side of the rectangular conveyor path. Thus, the conveyor path can effectively be used to provide a further saved installation space. 
     When the primary molding section  212 , heat treatment section  214  and final molding section  216  are located adjacent one another, the primary molding can immediately be blow-molded into a final product while maintaining heat provided by heat treating of the primary molding. Thus, the blow molding step can efficiently be carried out without heat loss. 
     The first to fourth heating sections  204 ,  206 ,  208  and  210  heat the preforms  232  from the receiving/removing section  202  to an appropriate blow molding temperature. Each of the heating sections  204 ,  206 ,  208  and  210  comprises a heating device  258  disposed outside the conveyor path and a reflecting plate  260  located inside the conveyor path at a position opposite to the heating device  258 . 
     Although not illustrated, the heating device  258  may include a plurality of heaters which are disposed along the direction of conveyance and arranged vertically. The reflecting plate  260  is disposed at a position corresponding to four intermittently conveyed preforms  232  to be simultaneously molded and parallel to the axis of the preforms  232 . 
     A preform rotation mechanism  266  includes a preform rotation chain  264  extending along a line on which the first to fourth heating sections  204 ,  206 ,  208  and  210  are located and passing around sprockets  262 . The preform rotation chain  264  engages with the preform rotation sprockets  238  of the placement bases  224  of the carrier members  220 . Thus, the placement bases  224  and thus the preforms  232  thereon can be rotated through the preform rotation chain  264 . 
     Thus, the preforms  232  being intermittently conveyed by the conveyor means  200  can be rotated by the preform rotation mechanism  266  at the stop position in each of the first to fourth heating sections  204 ,  206 ,  208 , and  210  such that the preforms  232  can uniformly be heated around their circumferences. 
     The fourth heating section  210  is disposed on the other shorter side of the conveyor path opposite to the receiving/removing section  202 . This enables the conveyor path to be effectively used for reducing the installation space by utilizing the length of the shorter sides of the conveyor path being elongated by disposing the primary molding section  212 , heat treatment section  214  and final molding section  216  on one longer side of the conveyor path, each of the sections having its own mold clamping mechanism  242 . 
     According to this embodiment, the carrier members  220  of the conveyor means  200  receive the preforms  232  from the receiving/removing section  202  and intermittently move them through the first to fourth heating sections  204 ,  206 ,  208  and  210 . The preforms  232  are heated by the heating sections while being rotated by the preform rotation mechanism  266 . After passed through the fourth heating section  210 , the preforms  232  are blow molded into primary moldings at the primary molding section  212 . The primary moldings are then heated at the heat treatment section  214  and finally blow-molded into final products at the final molding section  216 . The final products are transferred from the final molding section  216  to the receiving/removing section  202  from which the final products are externally removed. 
     FIGS. 3-9 show another embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     The heat-resistant container molding apparatus comprises a preform molding section  302  for injection-molding preforms  300 , a heat-resistant container molding section  304  for blow-molding the preform  300  into heat-resistant containers and a conveyor line  306  for receiving and conveying the preforms  300  from the preform molding section  302  to the heat-resistant container molding section  304 . 
     The preform molding section  302  comprises an injection molding portion  308 , a preform removing portion  310  and a rotary carrying means  312  for conveying the preforms  300  from the injection molding portion  308  to the preform removing portion  310  while rotating the preforms  300 . 
     The injection molding portion  308  comprises an injection device  314  and an injection mold (not shown) connected to the injection device  314 . The injection molding portion  308  illustrated is adapted to form four preforms  300  simultaneously. In this embodiment, each of the preform molding section  302  and heat-resistant container molding section  304  is adapted to handle every four preforms that are simultaneously molded. However, the number of preforms to be handled by these sections may optionally be selected depending on the heat treatment time (e.g., eight preforms at the preform molding section  302  and four preforms at the heat-resistant container molding section  304 ). 
     The preform removing portion  310  is located at a position opposite to the injection molding portion  308  and removes the preforms  300  from the rotary carrying means  312  at each time when the preforms  300  are moved from the injection molding portion  308  to the preform removing portion  310  through 180 degrees by the rotary carrying means  312  after the preforms  300  have been injection-molded at the injection molding portion  308 . 
     The rotary carrying means  312  includes four split neck molds (not shown) mounted thereon at a position corresponding to each of the injection molding portion  308  and preform removing portion  310 . Each of the neck molds is adapted to receive an injection core mold (not shown). When a preform  300  is held by the corresponding neck and core molds, it is then moved from the injection molding portion  308  to the preform removing portion  310  at which the preform  300  will be removed by a removing mechanism (not shown). 
     The heat-resistant container molding section  304  is of the same structure as that of the heat-resistant container molding device shown in FIGS. 1 and 2 wherein the receiving/removing section  202 , first to fourth heating sections  204 ,  206 ,  208  and  210 , primary molding section  212 , heat treatment section  214  and final molding section  216  are disposed on the rectangular conveyor path defined by the conveyor means  200 , except that such a receiving/removing device  316  as will be described is disposed in the receiving/removing section  202 . Therefore, the heat-resistant container molding section  304  will not further be described except the receiving/removing device  316 . 
     The conveyor line  306  is used to convey the preforms  300  removed by the preform removing portion  310  of the preform molding section  302  to the receiving/removing section  202  of the heat-resistant container molding section  304 . As the preforms  300  are being conveyed in such a manner, they are cooled before the preforms  300  are moved into the heat-resistant container molding section  304 . 
     If the temperature of the preforms  300  is cooled to a level sufficiently lower than the blow molding temperature at the heat-resistant container molding section  304 , the influence of heat history can be reduced. For such a purpose, the conveyance distance and time are set such that the preforms  300  are cooled preferably to a temperature equal to or lower than about 50° C. and more preferably to about 30° C. In such a case, it is preferred that the conveyance time is about five minutes. However, the conveyance time may optionally be selected depending on the wall-thickness of the preforms. 
     The conveyor line  306  includes a preform rotating and conveying means  318  for conveying the preforms  300  while rotating them. 
     The preform rotating and conveying means  318  comprises an upstream intermittent conveying means  320  for intermittently conveying every given number of rotating preforms  300  to be simultaneously formed (four) and a downstream continuous conveying means  322  for receiving and continuously conveying the rotating preforms  300  from the intermittent conveying means  320 . The intermittent conveying means  320  conveys the preforms  300  while maintaining a pitch set at the preform removing portion  310  of the preform molding section  302  such that the preforms  300  will not stick. one another during the conveyance. The continuous conveying means  322  preferably adjusts the conveyance speed such that the preforms  300  will be conveyed in close contact with one another to be sufficiently gathered. The intermittent conveying means  320  a has a connection to the preform removing portion  310  of the preform molding section  302 , such a connection part being arranged parallel to the array of preforms in the preform removing portion  310 . The continuous conveying means  322  has a connection to the receiving/removing section  202  of the heat-resistant container molding section  304 , the connection part being arranged perpendicular to the receiving/removing section  202 . 
     The intermittent and continuous conveying means  320 ,  322  comprise a guide rail  328 , a conveyor belt  330  and a belt drive motor  332  (see FIGS. 3 to  5 ). 
     The guide rail  328  supports the bottom of a support ring  326  in a neck  324  of each preform  300 . The conveyor belt  330  is disposed parallel to the guide rail  328  and also supports the bottom of the support ring  328  in each preform neck such that the preform will be held between the conveyor belt  330  and the guide rail  328 . The belt drive motor  332  moves the conveyor belt  330  intermittently in the intermittent conveying means  320 , and moves the conveyor belt  330  continuously in the continuous conveying means  322 . 
     The intermittent conveying means  320  further includes a cooling means  334  for cooling the preforms  300 , as shown in FIG.  5 . The cooling means  334  forcibly cools the preforms  300  and reliably prevents sticking of the preforms  300 . This can reduce the conveyance distance in the intermittent conveying means  320 . In addition, the continuous conveying means  322  may include a further cooling means to improve the cooling effect. 
     The cooling means  334  comprises an axial fan  336  located below the conveyor path and a perforated plate  340  disposed between the axial fan  336  and the conveyor path, the plate  340  having a number of small apertures  338 . Thus, a flow of cooling air can be uniformly provided for the preforms  300  being conveyed. 
     In such a manner, the preforms  300  removed from the preform removing portion  310  of the preform molding section  302  are intermittently conveyed by the intermittent conveying means  320  for every number of simultaneously formed preforms. The preforms  300  are then supplied to the receiving/removing section  202  of the heat-resistant container molding section  304  by the continuous conveying means  322  while the preforms are in close contact with one another. Therefore, the preforms  300  just removed from the preform removing portion  310  can be conveyed in close contact with one another and without sticking under such a state that they are sufficiently cooled. Thus the preforms can be gathered sufficiently. 
     The preforms  300  gathered in close contact with one another by the continuous conveying means  322  are then transferred to the conveyor means  200  of the heat-resistant container molding section  304  by the receiving/removing device  316  disposed in the receiving/removing section  202  of the heat-resistant container molding section  304 . 
     The receiving/removing device  316  comprises a pitch changing mechanism  342  and a receiving/removing mechanism  346 . 
     The pitch changing mechanism  342  provides a pitch set for simultaneous molding in the heat-resistant container molding section  304  to the preforms  300  conveyed from the continuous conveying means  322  in close contact with one another. 
     The pitch changing mechanism  342  comprises a pitch changing member  350 , a linear guide rail  352  and a rodless cylinder  354 , as shown in FIGS. 6-8. The pitch changing member  350  is arranged parallel to a pat of the conveyor means  200  at the receiving/removing section  202  and perpendicular to the continuous conveying means  322  in contact with it. The pitch changing member  350  has preform support recesses  348  equal in number to the preforms to be simultaneously molded, these recesses  348  being formed in the side of the pitch changing member  350  contacting the continuous conveying means  322  with a pitch set for simultaneous molding in the heat-resistant container molding section  304 . The linear guide rail  352  guides the pitch changing member  350  parallel to the conveyor means  200  at the receiving/removing section  202  toward a position corresponding to the carrier members  220 . The rodless cylinder  354  moves the pitch changing member  350  along the linear guide rail  352 . 
     As the pitch changing member  350  is moved to the conveyor means  200  along the linear guide rail  352  by the rodless cylinder  354 , the preforms  300  gathered in close contact with one another at the continuous conveying means  322  are sequentially received by the respective preform support recesses  348  of the pitch changing member  350  such that the preforms  300  will be positioned corresponding to the carrier members  220  in the receiving/removing section  202  with the pitch for simultaneous molding. 
     The receiving/removing mechanism  346  receives and transfers the preforms  300  from the pitch changing mechanism  342  to the carrier members  220  of the conveyor means  200  at the receiving/removing section  202 . The receiving/removing mechanism  346  also receives and removes final products  344  (see FIG. 9) from the carrier members  220  when they are conveyed from the final molding section  216  to the receiving/removing section  202  after one cycle has terminated in the heat-resistant container molding section  304 . 
     The receiving/removing mechanism  346  comprises four chucks  356 , an inverting mechanism  358 , a lifting mechanism  360  and a horizontal drive mechanism  362 . The chucks  356  can open and close, and are disposed at a position opposing to the position in which the carrier members  220  of the conveyor means  200  are stopped in the receiving/removing section  202  of the heat-resistant container molding section  304 . The inverting mechanism  358  inverts the chucks  356  between the pitch changing mechanism  342  and the conveyor means  200 . The lifting mechanism  360  lifts the chucks  356  up and down between a height corresponding to the carrier members  220  of the conveyor means  200  and the pitch changing member  350  and another height slightly higher than the above height. The horizontal drive mechanism  362  moves the chucks  356  in the horizontal direction between a position corresponding to the carrier members  220  and another position corresponding to the preform support recesses  348  in the pitch changing member  350 . 
     More particularly, each of the chucks  356  is formed by a pair of chuck members  356   a  and  356   b.  The chuck members  356   a  and  356   b  can be opened and closed by a pair of opening/closing rods  366   a  and  366   b  which are slidably moved in the opposite directions by a chuck drive cylinder  364 . More particularly, the opening/closing rods  366   a  and  366   b  are slidable in the opposite directions through an interlocking mechanism such as a rack-and-pinion mechanism or the like. One of the opening/closing rods  366   a  or  366   b  fixedly supports one of the chuck members  356   a  or  356   b.  The other chuck member  356   b  or  356   a  is fixedly mounted on the other opening/closing rod  366   b  or  366   a.  As one of the opening/closing rods  366   a  or  366   b  is driven by the chuck drive cylinder  364  connected thereto, both the opening/closing rods  366   a  and  366   b  are slidably moved in the opposite directions through the interlocking mechanism so that the chuck members  356   a  and  356   b  fixedly mounted on the respective rods will be moved toward or away from each other to close or open the chuck  356 . 
     The inverting mechanism  358  is connected to each of the opening/closing rods  366   a  and  366   b  at one end. The inverting mechanism  358  comprises an inverting actuator  368  which rotates to move the opening/closing rods  366   a  and  366   b  as a unit so as to invert the chucks  356  between the conveyor means  200  and the pitch changing mechanism  342 . 
     The lifting mechanism  360  comprises a lifting cylinder  370  for supporting the chucks  356  and inverting mechanism  358  for up-and-down movement. As the chucks  356  and inverting mechanism  358  are moved upward or downward, the preforms  300  are received or removed. 
     The horizontal drive mechanism  362  comprises a horizontal guide  372  for guiding the lifting mechanism  360  between a receiving position at which the preforms  300  are received from the pitch changing mechanism  342  and a transfer position at which the preforms  300  are transferred to the carrier members  220 , and a horizontal drive cylinder  374  for moving the lifting mechanism  360  in the horizontal direction between the aforementioned two positions. 
     When the preforms  300  are to be transferred from the pitch changing mechanism  342  to the carrier members  220  of the conveyor means  200 , the chucks  356  are moved to their inverted positions above the pitch changing member  350  by the inverting mechanism  358  when the chucks  356  have been supported at their raised positions by the lifting mechanism  360 . At the positions, the chucks  356  will be opened by the chuck drive cylinder  364 . 
     When the pitch changing member  350  of the pitch changing mechanism  342  holds the preforms  300  and is in a position corresponding to the receiving/removing mechanism  346 , the horizontal drive cylinder  374  is energized to slide the chucks  356  and inverting mechanism  358  supported by the lifting mechanism along the horizontal guide  372  toward the pitch changing mechanism  342 . 
     The lifting mechanism  360  then moves the chucks  356  downward to the pitch changing member  350 . 
     As the chucks  356  are closed by the chuck drive cylinder  364 , the chucks  356  will grasp the necks of the preforms  300  supported by the pitch changing member  350  at the preform support recesses  348 . Under such a state, the lifting mechanism  360  is again actuated to move the chucks  356  to their raised positions at which the inverting mechanism  358  in turn inverts the chucks  356  toward the carrier members  220 . At the same time, the horizontal drive mechanism  362  moves the chucks  356  horizontally toward the carrier members  220 . Thus, the chucks  356  will be located above the carrier members  220  under such a state that the preforms  300  are inverted with the necks  324  thereof oriented downward. 
     The lifting mechanism  360  is then actuated to move the chucks  356  downward. Conveyor pins  236  in the carrier members  220  will be inserted into the respective preforms  300  held by the chucks  356  to support them. Under such a state, the chuck drive cylinder  364  is actuated to open the chucks  356 . The opened chucks  356  are then moved by the horizontal drive mechanism  362  horizontally to the pitch changing mechanism  342 . The preforms  300  are transferred from the pitch changing mechanism  342  to the carrier members  220 . Thus, the carrier members  220  may convey the preforms  300 . 
     When the final products  344  formed by the heat-resistant container molding section  304  have been moved to the receiving/removing section  202 , the receiving/removing mechanism  346  causes the chucks  356  to grasp the inverted final products  344  at their necks and also the inverting mechanism  358  to invert the final products  344 , as shown in FIG.  9 . Under such a state, the chucks  356  are opened to fall the final products  344  into a chute  376  through which they can externally be removed. 
     Thus, the receiving/removing mechanism  346  has two functions, that is, a function of receiving the preforms from the pitch changing mechanism  342  and transferring them to the carrier members  220  and another function of receiving the final products  344  formed by the heat-resistant container molding section  304  from the carrier members  220  and externally removing them. Therefore, the system can be simplified with saving of the installation space, unlike use of separate mechanisms for performing the above two functions. 
     FIGS. 10-19 show a heat-resistant container molding apparatus and method according to a further embodiment of the present invention. 
     The heat-resistant container molding apparatus will first be described. The apparatus comprises a machine base  10 , an upper fixed plate  12  mounted above the machine base  10 , an upper base plate  14  located between the machine base  10  and the upper fixed plate  12  and a rotatable plate  16  rotatably mounted on the underside of the upper base plate  14 . 
     A molding space is formed between the machine base  10  and the rotatable plate  16 . Receiving/removing section  18 , heat treatment section  20  and final molding section  22  are angularly located equidistantly spaced away from one another by 120 degrees through which the rotatable plate  16  is angularly rotated and stopped. 
     The upper fixed plate  12  is fixedly mounted on the top ends of three tie rods  24  upstanding from the machine base  10  so that the top ends of the three tie rods  24  will be connected together. 
     The upper base plate  14  is mounted below the upper fixed plate  12  and movable vertically along the tie rods  24 . The upper base plate  14  can also be moved up and down by an upper base plate drive device  26  which is disposed between the machine base  10  and the upper base plate  14 . 
     The upper base plate drive device  26  comprises an upper base plate lifting cylinder  28  mounted on the machine base  10  and an upper base plate lifting rod  30  extendible from and retractable through the upper base plate lifting cylinder  28 . The top end of the upper base plate lifting rod  30  is rotatably connected to a connecting block  42  which is rotatably mounted on the upper base plate  14  at its center. The bottom end of the upper base plate lifting rod  30  is extendible into the machine base  10 . The machine base  10  includes a stopper  32  which engages the bottom end of the upper base plate lifting rod  30  to limit the downward movement of the upper base plate  14 . 
     The rotatable plate  16  is rotatably supported by a guide rail  34  mounted on the underside of the upper base plate  14  at its outer edge and can be moved up and down through the up-and-down movement of the upper base plate  14 . 
     The rotatable plate  16  is repeatedly rotated and stopped for every 120 degrees by a rotary actuator  36 . The rotary actuator  36  is mounted on a mounting block  38  on the top of the upper base plate  14  and includes an output shaft  40  which is connected to the top of the rotatable plate  16  through a connecting block  42 . 
     The underside of the rotatable plate  16  includes three neck support fixing plates  44  mounted thereon which are disposed equidistantly through 120 degrees, that is, at positions respectively corresponding to the receiving/removing section  18 , heat treatment section  20  and final molding section  22 . 
     Each of the neck support fixing plates  44  is formed by a pair of split plates  46  which support neck support members  48  each comprising mold halves for grasping the neck of a molding. The split plates  46  are biased against each other for closing and may be separated using wedge apertures  50  which are formed therein at the opposite ends. When the neck of a molding is grasped by the neck support member  48 , the molding may be conveyed through the receiving/removing section  18 , heat treatment section  20  and final molding section  22 . The neck support fixing plate  44  includes four of such neck support members  48  such that four moldings can be conveyed at the same time. 
     The receiving/removing section  18 , on one hand, receives primary moldings  52  blow-molded from preforms and on the other hand, removes final products  54  blow molded in the final stage. More particularly, as shown in FIG. 12A, a pair of guide rods  56  stand on the upper base plate  14 . The tops of the guide rods  56  are fixedly connected to a cylinder fixing plate  60  on which an opening cam drive cylinder  58  is mounted. The opening cam drive cylinder  58  moves a movable plate  62  along the guide rods  56  between the upper base plate  14  and the cylinder fixing plate  60 . The underside of the movable plate  62  supports an opening cam fixing plate  64  from which a pair of opening cams  66  suspend at positions respectively corresponding to the wedge apertures  50 . 
     When the upper base plate  14  is in its lower limit position and if the opening cams  66  are downward moved by the opening cam drive cylinder  58 , the bottom tips of the opening cam  66  are inserted into the wedge apertures  50  of the neck support fixing plate  44  to force and expand the split plates  46  for opening the neck support member  48 , as shown in FIG.  12 B. Under such a state, the neck of a primary molding  52  can be inserted into the neck support member  48 . The upward movement of the opening cams  66  closes the neck support member  48  to grasp the neck  68  of the primary molding. The downward movement of the opening cams  66  opens the neck support member  48  to release the neck  68  of the final product  54  for removal. Although not illustrated, the receiving/removing section  18  performs the transfer of the primary moldings  52  or final products  54  relative to the neck support members  48  through any known robot device or the like. 
     The heat treatment section  20  comprises four heat treatment molds  70  mounted on the machine base  10  and four heat treatment core molds  72  provided at the upper base plate  14  for up-and-down movement. A primary molding  52  is brought into contact with the inner wall of a heat treatment mold  70  and heated while pressurizing the interior of the primary molding  52 . Such a primary molding  52  has been molded through a primary blow mold having its internal dimensions slightly larger than those of the desired final product  54  in the other stage. 
     In such a case, the primary molding  52  is enlarged from the neck  68  toward a shoulder  74  to form a barrel portion  76  in the form of a cylinder having substantially no irregularity in the axial direction thereof. Thus, each of the heat treatment molds  70  is formed by a split shoulder heating block  78  corresponding to the shoulder  74  of the primary molding  52  and a barrel heating block  80  corresponding to the cylindrical barrel portion  76  and having a circumferentially continuous pot-shaped configuration. The shoulder heating block  78  can be opened and closed by an opening/closing cylinder  82 . The heat treatment mold  70  also includes a bottom heating block  84  including a push-up bottom heating block  86 . The outer walls of the barrel and bottom heating blocks  80 ,  84  are surrounded by band heaters  88  while the shoulder and push-up bottom heating blocks  78 ,  86  include internal heaters  79 . The internal heaters  79  may be replaced by any internal piping means through which a temperature regulating medium is circulated. Since the inner wall of the heat treatment mold  70  is formed corresponding to the configuration of the primary molding  52  and only the shoulder heating block  78  corresponding to the shoulder  74  of the primary molding is formed to be of a split type, the number of expensive split mold parts can be minimized to reduce the manufacturing cost and installation space of the entire system while taking a small-sized opening/closing cylinder  82 . 
     Each of the heat treatment core molds  72  is mounted on the movable plate  62  through a heat treatment core mold fixing plate  92  and moved up and down by a core drive cylinder  90  placed on the cylinder fixing plate  60 . Thus, the heat treatment core mold  72  can be opened or closed relative to the heat treatment mold  70 . The heat treatment core mold  72  is supplied with air through the proximal end thereof. The air is conducted into the primary molding  52  to pressurize the interior thereof so that the primary molding  52  will be brought into contact with the inner wall of the heat treatment mold  70  and heated. This improves the heat transfer and can prevent the primary molding  52  from being shrunk during the heat treatment to avoid uneven wall thickness. 
     In such a case, the pressure of air conducted into the primary molding  52  is in the range of 2-10 kg/cm 2 . The heat treatment temperature is between 150° C. and 220° C. at the shoulder and between 150° C. and 220° C. at the barrel while the heat treatment time is between five seconds and ten seconds. If the heat treatment time is less than five seconds, an intermediate molding  94  will have its unstable shrinkage after the heat treatment, resulting in variability of the size from one intermediate molding  94  to the other. If the heat treatment time exceeds ten seconds, it is not preferable in viewpoint of the molding cycle. 
     The rate of shrunk volume of the primary molding  51  to the intermediate molding  94  after the heat treatment is set to be between 10% and 30% (5-15% in the axial direction and 0-15% in the circumferential direction). The temperature of the intermediate molding  94  immediately before it is finally blow-molded is set to be about 180° C. Thus, the size of the intermediate molding  94  will be substantially equal to or slightly smaller than that of the final product  54  after the heat treatment. 
     The final molding section  22  includes final blow mold  96  mounted on the machine base  10  and four blow core molds  98  which are provided at the upper base plate  14  and can be moved up and down. The final blow mold  96  is heated and thereafter blow-molds a heat treated intermediate molding  94  into a final product  54 . 
     The final blow mold  96  is of a split type that is defined by four cavity surfaces forming the configuration of the final product  54 . The final blow mold  96  is clamped by a mold clamping device  100 . The mold clamping device  100  has a drive cylinder  102  only on one side. The mold clamping device  100  opens or closes the split mold halves in synchronism with each other through a synchronizing mechanism (not shown). The final blow mold  96  includes a bottom mold  106  driven by a bottom mold drive cylinder  104  and an internal heater  108  for heating the molding to a temperature equal to or higher than the desired heat resisting temperature when the molding is blow-molded into a final product. This can remove any strain produced in the final product. The internal heater  108  may be replaced by any internal piping through which a temperature regulating medium is circulated. 
     A blow core mold  98  is mounted on the movable plate  62  through a blow core mold fixing plate  112 . The blow core mold  98  is driven up and down by a blow core mold drive cylinder  110  on the cylinder fixing plate  60  against the final blow mold  96 . The blow core mold  98  also conducts blow air into the interior of the molding. 
     In the final molding section  22 , the intermediate molding  94  is in a softened state after it has been heat-treated. The intermediate molding  94  is blow-molded into a final product  54  within the heated final blow mold  96 , and the final product  54  is heat treated by the heated final blow mold  96 . 
     The heat treatment condition in the final blow molding step is selected such that the temperature of the final blow mold is between 90-100° C., the blow molding time is between five and ten seconds and the pressure of blow air is between 15-30 kg/cm 2 . By heat-treating the final product within the final blow mold in such a manner, any strain can be removed to improve the heat resisting property. Since the size of the intermediate molding  94  is designed to be substantially equal to or slightly smaller than that of the final product  54 , the molding will not substantially be stretched in the blow molding step. In addition, the molding will not substantially be oriented since the intermediate molding  94  is placed at a temperature sufficiently higher than the appropriate stretching temperature. Therefore, a strain will not substantially be produced under such a condition. Since the size of the intermediate molding  94  is substantially equal to or slightly smaller than that of the final product  54 , any pinch can be avoided on clamping in the final blow molding step. 
     A method of molding a heat-resistant container using the aforementioned heat-resistant container molding apparatus will be described mainly with reference to FIG.  19 . 
     First of all, a primary molding  52  is blow-molded from an injection-molded preform by a primary blow molding device other than the heat-resistant container molding apparatus of the present invention. The primary molding  52  is slightly larger than the final product  54 . The condition of molding the primary molding  52  is selected such that the surface temperature of the preform during the primary molding step is between about 100° C. and about 120° C., the primary blow mold is at room temperature, and the size of the primary molding is 10% larger than that of the final product  54 . The primary molding  52  is transferred to the receiving/removing section  18  through a transfer device such as a robot device (not shown). 
     In the receiving/removing section  18 , the upper base plate  14  is now positioned at its lower limit position by the upper base plate drive device  26 . Each neck support member  48  is placed in its open position by moving the opening cams  66  downward into the wedge aperture  50  of the neck support fixing plate  44  under the actuation of the opening cam drive cylinder  58 . Under such a state, as shown in FIG.  19 (A), the neck  68  of the primary molding  52  is inserted into the neck support member  48  and then the opening cams  66  are moved upward and separated from the wedge aperture  50  under the action of the opening cam drive cylinder  58 . Thus, the transfer of the primary molding  52  to the neck support member  48  will terminate. At this time, the upper base plate  14  is moved to its upper limit position at which the stage is shifted to the conveyance stage under the action of the upper base plate drive device  26 . The upper limit position is set at a height whereat the lower end of the primary molding  52  does not come in contact with the heat treatment mold  70  of the heat treatment section  20 . Under such a state, the rotary actuator  36  is energized to rotate the rotatable plate  16  through 120 degrees. When the rotatable plate  16  is stopped, the primary molding  52  may be conveyed to the heat treatment section  20 , as shown in FIG.  19 (B). During this rotation, the opening cams  66 , heat treatment core mold  72  and blow core mold  98  are at their retracted positions above the rotatable plate  16 . Thus, the rotatable plate  16  can reliably be rotated. 
     In the heat treatment section  20 , as shown in FIG.  19 (B), the primary molding  52  is located above the heat treatment mold  70  in which the shoulder heating block  78  is now placed in its open position under the action of the opening/closing cylinder  82 . The upper base plate drive device  26  is then actuated to move the upper base plate  14  downward to the lower limit position at which the primary molding  52  is inserted into the heat treatment mold  70 . Since the shoulder heating block  78  is in its open-position at this time, the primary molding  52  will certainly be inserted into the heat treatment mold  70 . The heat treatment mold  70  is set to have its inner wall slightly larger than that of the primary molding  52  such that the primary molding  52  can be prevented from being damaged when it is inserted into the heat treatment mold  70 . 
     As shown in FIG.  19 (C), the shoulder heating block  78  is then closed by the opening/closing cylinder  82  and the heat treatment core mold  72  is downward moved by the heat treatment core drive cylinder  90  to engage with the neck support member  48 . Air is then conducted into the interior of the primary molding  52  through the heat treatment core mold  72  to pressurize the interior of the primary molding  52  such that the primary molding  52  will be brought into contact with the inner wall of the heat treatment mold  70  for heat treatment. The heat treatment is carried out under the heat treatment temperature and time condition set such that the intermediate molding  94  is substantially equal to or slightly smaller than the final product  54 . For example, the pressure of conducted air is about 2-10 kg/cm 2 , the shoulder temperature is 150-220° C., the barrel temperature is 150-220° C. and the heat treatment time is 5-10 seconds. Under such a setting, the primary molding  52  is molded into the intermediate molding  94  having its rate of shrunk volume between 10-30% (5-15% in the axial direction and 0-15% in the circumferential direction) after the heat treatment. The heat treatment is carried out such that the temperature of the intermediate molding  94  becomes about 180° C. immediately before the final blow molding step. 
     When the heat treatment terminates, the opening/closing cylinder  82  is actuated to open the shoulder heating block  78  while the core drive cylinder is actuated to move the heat treatment core mold  72  upward for retracting it above the rotary plate. The upper base plate drive device  26  is actuated to move the upper base plate  14  to its upper limit position so that the heat treated primary molding  52  will be drawn from the heat treatment mold  70 . The primary molding  52  is then transferred to the next step. In such a case, the primary molding  52  drawn from the heat treatment mold  70  becomes the intermediate molding  94  which is in its softened state with shrinkage. 
     The rotary actuator  36  is then actuated to rotate the rotatable plate  16  through 120 degrees such that the intermediate molding  94  will be conveyed to the final molding section  22 . 
     In the final molding section  22 , as shown in FIG.  19 (D), the final blow mold  96  is now placed in its open state under the action of the mold clamping device  100 . The blow core mold  98  is retracted above the rotatable plate  16  by the blow core mold drive cylinder  110 . The upper base plate drive device  26  is then actuated to move the upper base plate  14  downward to its lower limit position so that the intermediate molding  94  is positioned within the blow mold  96 . As shown in FIG.  19 (E), the blow mold  96  is clamped by the mold clamping device  100 . The blow core mold drive cylinder  110  is then actuated to move the blow core mold  98  downward to engage with the neck support member  48 . The blow air is conducted into the interior of the intermediate molding  94  through the blow core mold  98  and blow-molded into the final product  54  within the final blow mold  96 . 
     In such a case, the final product  54  is heated by the final blow mold  96  after the latter has been heated by the internal heater  108 . The heat treatment condition in the final blow molding step is selected such that the temperature of the final blow mold  96  is between 90-100° C., the blow molding time is between five and fifteen seconds and the blow air pressure is between 15-30 kg/cm 2 . In the final blow molding step, the final blow mold  96  is heated to a temperature equal to or higher than the desired heat resisting temperature such that any strain produced in the final product  54  when it is blow-molded will be removed. Since the intermediate molding  94  is substantially equal to or slightly smaller than the final product  54 , the intermediate molding  94  will not be substantially stretched in the final blow molding step. In addition, the temperature of the intermediate molding  94  is sufficiently higher than the appropriate stretching temperature. Therefore, the intermediate molding  94  will not also be substantially oriented. As a result, a strain will not substantially be produced. Furthermore, the intermediate molding  94  will not be pinched by the final blow mold  96  since the intermediate molding  94  is substantially equal to or slightly smaller than the final product  54 . After termination of the final blow molding step, the mold clamping device  100  is again actuated to open the final blow mold  96  while the blow core mold drive cylinder  110  is actuated to move the blow core mold  98  upward above the rotatable plate  16 . The upper base plate  14  is thereafter moved upward to its conveyance position, as shown in FIG.  19 (F). 
     Thereafter, the rotatable plate  16  is rotated through 120 degrees, the upper base plate  14  is downward moved and the opening cams  66  are downward moved. Thus, the final product  54   10  may be removed at the receiving/removing section  18 , as shown in FIG.  19 (G). 
     The steps (A) to (G) will be repeated sequentially. 
     FIG. 20 shows a further embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. This embodiment uses a linear type conveyor device  120 . This heat-resistant container molding apparatus functions in a manner similar to those of the embodiments shown in FIGS. 10-19 wherein a primary molding blow-molded from a preform is conveyed through the receiving section  122 , heat treatment section  20 , final molding section  22  and removing section  124  so that the molding will be heat-treated and blow-molded into the final product. 
     FIG. 21 shows a further embodiment of a heat-resistant container molding apparatus constructed in accordance with the present invention. 
     This embodiment also uses a linear type conveyor device  120 . The heat-resistant container molding apparatus performs the heat treatment and final molding by conveying an injection molded preform through a receiving section  126 , primary heating section  128 , secondary heating section  130 , temperature regulating section  132 , intermediate blow molding section  134 , heat treatment section  20 , final molding section  22  and removing section  124 , as in the embodiment of FIGS. 1 and 2. 
     The present invention is not limited to the aforementioned embodiments, and various modifications can be made within the scope of the invention. 
     For example, in the embodiment shown in FIGS. 10-19, the drive devices for the upper base plate and rotatable plate may be replaced by any of various other drive devices. 
     In the embodiment of FIGS. 10-19, the heat treatment and A final blow molds are fixed while the upper base plate is upward moved to retract the moldings above the heat treatment and blow molds. However, the present invention may also be applied to a case where the upper base plate is fixed and the heat treatment and final blow molds are movable. 
     The number of containers to be simultaneously molded may be freely selected rather than four as in the aforementioned embodiments. 
     If a plurality of heat treatment sections are disposed in series or parallel between the primary molding section and the final molding section, the heat treatment time can be prolonged longer than that of a single heat treatment section. Thus, a desired heat treatment may be applied depending on the wall thickness of the final product.