Heating cylinder device for a molding machine

This heating cylinder device for a molding machine includes a cylinder member along the axial direction of which and within which are defined several heating zones for material to be molded, each of the heating zones being provided with a heater, wherein the heating capacities and the thermal conductivities to the exterior of the heating zones are suitably arranged so as to correspond to the temperatures and operational performances required from the heating zones. Each of the heaters may optionally surround the portion of the cylinder member defining its heating zone. The external diameter of the portion of the cylinder member defining each of the heating zones may be varied according to the heat capacity and temperature required therefrom; or, the portions of the cylinder member between its portions defining the heating zones may be substantially narrowed down as compared to its portions defining the heating zones; or, each of the heaters may be buried in the portion of the cylinder member defining its heating zone; or, a plurality of layers of insulating material may be provided as surrounding a plurality of the heating zones and the heaters surrounding them. In the last case, these layers may be of different thicknesses.

BACKGROUND OF THE INVENTION 
The present invention relates to a heating cylinder device for melting 
resin material in a molding machine such as an injection molding machine 
or an extruder or the like which performs mold forming using such resin as 
a material, and in particular to such a heating cylinder device which can 
more effectively accomplish steady and uniform heating up of such resin 
material. 
In the prior art with regard to this sort of heating cylinder device for a 
molding machine, demands are nowadays constantly being made for shortening 
of the injection cycle, in order to improve productivity. Further, it is 
also very desirable to reduce the power consumption of the heating means 
for the resin, which typically accounts for about a third of the total 
power consumption of the injection molding machine. Reduction of the power 
required for setting up the machine and bringing its various parts to 
appropriate operating temperatures is effective for meeting this end. And 
yet further it is a constant requirement to improve the precision of the 
molded products made by the molding machine, which entails as accurate 
control of heating of the resin material as possible. Accordingly, proper 
heat management of the heating cylinder device for the resin is crucial 
for meeting these needs. 
Now, in the prior art, such a heating cylinder device typically has had a 
plurality of heating zones arranged, and has basically been shaped as a 
uniform hollow cylinder, with a plurality of annular band shaped heaters 
arranged longitudinally around its outer surface along the lengthwise 
direction, each such heater being wrapped around one of the heating zones. 
These heaters are energized in such appropriate amounts as to keep the 
successive heating zones at appropriate temperatures to ensure proper 
heating up of the resin material to be molded, as such resin material is 
progressively moved down along the central hole of the hollow heating 
cylinder device by the action of a plunger or the like. Thus, the heat 
management for these heating zones is performed. 
However, the problems with such a prior art type of heating cylinder device 
are as follows. 
First, because the thickness of the heating cylinder has been uniform for 
each of the heating zones, thermal interferences tend to develop between 
neighboring ones of the heating zones, in addition to the interferences 
arising from external sources such as changes in the ambient temperature, 
fluctuations in the system due to the motion of the resin material which 
is being heated up, changes in the temperature of the resin material, 
dissipation of heat in injecting the resin material, and so on. 
Accordingly accurate temperature control of the resin becomes very 
difficult. Further, because the thickness of the heating cylinder has been 
uniform for each of the heating zones, each of these heating zones has 
approximately the same heat capacity, and in view of the different 
temperatures up to which these zones are required to be heated this causes 
difficulties in heating control. 
Secondly, because each heating zone as defined along the axis of the 
heating cylinder device is contiguous to the next, and the heating 
cylinder device is constructed basically as a uniform hollow cylinder, the 
abovementioned thermal interferences which tend to develop between 
neighboring ones of the heating zones are very strong, and present a 
substantial obstacle to the proper heat control of the various heating 
zones. 
Thirdly, because the thickness of the walls of the heating cylinder device, 
in other words the distance between its outer circumferential surface on 
which, in the above outlined prior art, the band shaped heaters are 
mounted, and its inner hole in which the resin is flowing, is very 
substantial, a time delay occurs in the transfer of heat from the heaters 
to the resin, and accordingly precise temperature control of the resin 
becomes very difficult, and fluctuations in the system, such as 
alterations in the ambient temperature, changes in the flow speed of the 
resin and in the temperature at which said resin is supplied to the 
heating cylinder device, and changes in the dissipation of heat that 
occurs when injecting the resin, cause great problems with regard to 
temperature control, because of the lack of responsiveness of the system. 
Fourthly and lastly, because the thermal capacity of each of the heating 
zones is approximately the same, and because the resistance to heat flow 
from each of the heating zones to the outside is approximately the same, 
this further causes thermal interferences between the neighboring heating 
zones to occur. 
SUMMARY OF THE INVENTION 
Accordingly, it is the primary object of the present invention to provide a 
heating cylinder device for a molding machine which avoids the above 
outlined disadvantages. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which can keep the injection cycle 
of the machine short. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which can improve productivity of 
the machine. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which reduces the power consumption 
as much as practicable. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which reduces operational cost. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which reduces the cost of the 
finished products. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which can improve the temperature 
control of the resin. 
It is a further object of the present invention to provide such a heating 
cylinder device for a molding machine which can improve the responsiveness 
of the temperature control. 
It is a yet further object of the present invention to provide such a 
heating cylinder device for a molding machine which promotes the 
production of more precise finished molded products. 
It is a yet further object of the present invention to provide such a 
heating cylinder device for a molding machine which provides proper heat 
management. 
It is a yet further object of the present invention to provide such a 
heating cylinder device for a molding machine which keeps the thermal 
interference between neighboring ones of heating zones thereof as low as 
possible. 
It is a yet further object of the present invention to provide such a 
heating cylinder device for a molding machine which keeps the thermal 
interference from outside sources as low as possible. 
It is a yet further object of the present invention to provide such a 
heating cylinder device for a molding machine which minimizes fluctuations 
in the system due to the motion of the resin material which is being 
heated up, changes in the temperature of the resin material, dissipation 
of heat in injecting the resin material, and so on. 
According to the most general aspect of the present invention, these and 
other objects are accomplished by a heating cylinder device for a molding 
machine, comprising a cylinder member along the axial direction of which 
and within which are defined a plurality of heating zones for material to 
be molded, each of said heating zones being provided with a heater, 
wherein the heating capacities and the thermal conductivities to the 
exterior of said heating zones are suitably arranged so as to correspond 
to the temperatures and operational performances required from said 
heating zones. 
According to such a structure, as will be particularly explained with 
regard to particular embodiments of the present invention, there is 
provided a heating cylinder device for a molding machine which can keep 
the injection cycle of the machine short, thus improving the productivity 
of the machine and reducing the cost of operation and the cost of the 
finished products. Further, the power consumption is reduced as much as 
practicable, and the temperature control of the resin is improved, and the 
responsiveness of the temperature control is also improved. Thus, this 
heating cylinder device for a molding machine minimizes fluctuations in 
the system due to the motion of the resin material which is being heated 
up, changes in the temperature of the resin material, dissipation of heat 
in injecting the resin material, and so on. Thereby, this heating cylinder 
device for a molding machine promotes the production of more precise 
finished molded products, by providing proper heat management by keeping 
the thermal interference between neighboring ones of heating zones thereof 
as low as possible, as well as by keeping the thermal interference from 
outside sources as low as possible. 
As a useful specialization of the above defined concept, these and other 
objects are yet more particularly and concretely accomplished by a heating 
cylinder device as described above, wherein each of said heaters surrounds 
the portion of said cylinder member defining its said heating zone. 
Further, according to one particular constructional aspect of the present 
invention, these and other objects may be more particularly and concretely 
accomplished by a heating cylinder device of either of the types described 
above, wherein the external diameter of the portion of said cylinder 
member defining each of said heating zones is varied according to the heat 
capacity and temperature required therefrom; or, according to another 
particular constructional aspect of the present invention, these and other 
objects may be more particularly and concretely accomplished by a heating 
cylinder device of either of the types described above, wherein the 
portions of said cylinder member between its said portions defining said 
heating zones are substantially narrowed down as compared to its said 
portions defining said heating zones; or, according to another particular 
constructional aspect of the present invention, these and other objects 
may be more particularly and concretely accomplished by a heating cylinder 
device of either of the types described above, wherein each of said 
heaters is buried in the portion of said cylinder member defining its said 
heating zone; or, according to yet another particular constructional 
aspect of the present invention, these and other objects may be more 
particularly and concretely accomplished by a heating cylinder device of 
either of the types described above, further comprising one or a plurality 
of layers of insulating material surrounding one or a plurality of said 
heating zones and said heaters surrounding them. 
According to these various particular structural concepts, the present 
invention may be concretely realized in an appropriate form for the 
particular application.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention will now be described with reference to the preferred 
embodiments thereof, and with reference to the appended drawings. FIG. 1 
is a side view of an injection molding machine, denoted generally by the 
reference numeral 10, which is for molding resin, and which incorporates a 
heating cylinder device 12 according to the present invention which may be 
one according to the first preferred embodiment of the present invention. 
In more detail, the injection molding machine 10 comprises a hopper 11 for 
charging the resin, the aforementioned heating cylinder device 12, a screw 
drive device 13 for rotatively driving a screw piston 20 incorporated in 
said heating cylinder device 12 which will be described later for 
injecting the molten resin, and a movable plate drive device 17 for 
removing the molded products by opening and closing a metallic die 16 
which is mounted between a fixed plate 14 and a laterally movable plate 
15. 
In FIG. 2, there is shown a sectional view of this heating cylinder device 
12 according to the first preferred embodiment of the present invention, 
taken in a sectional plane containing the axis of said heating cylinder 
device. The device 12 is generally formed in a cylindrical shape with a 
central axial hole 19 formed through a cylinder wall portion 18, and a 
screw piston 20 mentioned above is fitted in said central axial hole 19, 
so as when rotated in a certain direction by the aforementioned screw 
drive device 13 to move to the left in the figure into said hole 19 so as 
to apply compression force to resin in said hole 19, and so as when 
rotated in the opposite direction to said certain direction to be moved to 
the right in the figure and to be withdrawn out of said hole 19. When said 
screw piston 20 is thus withdrawn from the hole 19 to a position beyond a 
given position, resin charged in the hopper 11 can travel downwards into 
the hole 19 to recharge the heating cylinder device 12. A nozzle 21 is 
provided at the opposite end (the left end) of the heating cylinder device 
12 from the hopper 11 (which is at the right end). Thus, as the screw 
piston 20 is alternately rotated in said certain direction and in the 
opposite direction to said certain direction, it is alternately forced 
into the hole 19 and withdrawn therefrom, thus alternately compressing 
resin in said hole 19 and forcing it out through the nozzle 21, and 
recharging said hole 19 with fresh resin from the hopper 11. 
In the heating cylinder device 12, there are altogether defined five 
heating zones, designated as Z1 through Z5, and axially spaced along the 
axis of said heating cylinder device 12 from the right to the left as seen 
in FIG. 2, i.e. from the end thereof at which the hopper 12 is provided to 
the end thereof at which the nozzle 21 is provided. Around each of these 
heating zones Z1 through Z5 there is fitted a corresponding heater H1 
through H5, which is formed as a band extending right around the cylinder 
of the heating cylinder device 12, and in the inner wall portion of the 
heating cylinder device 12, in each of said heating zones Z1 through Z5, 
there is fitted a corresponding thermocouple T1 through T5. 
In detail, the first heating zone Z1 is the portion of the heating cylinder 
device 12 into which the resin is supplied from the hopper 11, and is 
heated by the heater H1 and is also water cooled so that the resin may be 
supplied from the hopper 11 without any risk of its surface being melted. 
And the thermocouple T1 detects the temperature in this first heating zone 
Z1. The second heating zone Z2 is a portion of the heating cylinder device 
12 in which the resin is, next, heated up substantially only by the heater 
H2, and the thermocouple T2 detects the temperature in this second heating 
zone Z2. The third heating zone Z3 is a portion of the heating cylinder 
device 12 in which the resin is, next, heated up both by the heater H3 and 
by the frictional heat generated by the rotation of and by the compression 
effect generated by the screw piston 20; and the thermocouple T3 detects 
the temperature in this third heating zone Z3. The fourth heating zone Z4 
is a reservoir in which the resin material to be injected is received for 
a certain time interval before being injected, and is required to be kept 
at a certain high temperature; in this portion of the heating cylinder 
device 12, the resin is heated up by the heater H4, and the thermocouple 
T4 detects the temperature in this fourth heating zone Z4. And the fifth 
heating zone Z5, which is just before the nozzle 21, is a portion of the 
heating cylinder device 12 in which the resin is particularly subject to 
disturbance of its temperature by external influences such as the heat 
capacity of the metallic die 16 and the atmosphere; and, in order to 
eliminate such external influence, the resin in this fifth heating zone Z5 
is kept hot by the heater H5, and the thermocouple T5 detects the 
temperature in this fifth heating zone Z5. 
Now, particularly according to the particularly specialized inventive 
concept of this first preferred embodiment of the present invention, the 
wall portion 18 of the heating cylinder device 12 is structured, not as in 
the prior art described above as a uniform cylinder of the same inner and 
outer diameters along its longitudinal length, but with the same inner 
diameter along its longitudinal length and with an outer diameter which 
increases in steps from the first heating zone Z1 to the second heating 
zone Z2, from the second heating zone Z2 to the third heating zone Z3, and 
from the second heating zone Z3 to the fourth heating zone Z4. And the 
outer diameter of the wall portion 18 of the heating cylinder device 12 at 
the fifth heating zone Z5 is much smaller than at all the other heating 
zones Z1 through Z4. Thus, the portions of the wall portion 18 which 
define the heating zones Z1 through Z5 are each of thickness appropriate 
to define a cylinder portion with heat capacity corresponding to the 
heating temperature required for said heating zone. In other words, the 
portions of the wall portion 18 of the heating cylinder device 12 which 
define the first heating zone Z1 and the fifth heating zone Z5 are thin, 
because the temperature control provided by the heaters H1 and H5 for 
these two heating zones Z1 and Z5 is required to be transferred very 
accurately and quickly to the resin, and accordingly the heat capacities 
of these portions of the wall portion 18 are kept low; while on the other 
hand the portions of said wall portion 18 of the heating cylinder device 
12 which define the second, third, and fourth heating zones Z2 through Z4 
are thicker, because heating temperatures required for these heating zones 
Z2 through Z4 are higher and accordingly it is beneficial to make the heat 
capacities of these portions of the wall portion 18 greater. In 
particular, the thickness of the portion of the wall portion 18 which 
defines the fourth heating zone Z4, which is required to be kept at a 
certain relatively high temperature, is made the thickest, so as to 
maximize the heat capacity of this portion of the wall portion 18. 
In FIG. 3, there is schematically shown in block diagram form a possible 
exemplary construction for the control system for the heating control of 
the five heating zones Z1 through Z5; although this control system does 
not form part of the present invention in the strict sense, nevertheless 
it is shown for the purposes of explanation, because its function is 
relevant. In this figure, the reference numeral 22 denotes a CPU (central 
processing unit) which via a bus communicates with an operation panel 23, 
a power output control unit 24, and a temperature input unit 25. The power 
output control unit receives signals from the CPU 22, and based upon their 
values controls the supply of power (in an ON and OFF fashion or a fashion 
of bang bang control) to the five band shaped heaters H1 through H5 for 
the five heating zones Z1 through Z5 respectively. The temperature input 
unit 25 receives supply of signals from the five thermocouples T1 through 
T5 for the five heating zones Z1 through Z5 respectively, and based upon 
the values of said signals (which are representative of the temperatures 
in said heating zones Z1 through Z5) outputs signals to the CPU 22. The 
operation panel 23 allows the setting up of target values for the 
temperatures for the five heating zones Z1 through Z5 individually, and 
based upon the values of said set up target values outputs appropriate 
signals to the CPU 22. CPU 22 operates according to various programs 
stored in its internal memory to control the aforementioned circuits and 
others not shown, thereby recording and reading out necessary data and 
performing calculations of various parameters associated with the 
temperature control of the five heating zones Z1 through Z5. 
In FIG. 4, a schematic control diagram for the temperature control for the 
heating zones Z1 through Z5 as performed by the CPU 22 is shown. In the 
case of the shown exemplary construction and operation, which are not 
intended to be limitative of the present invention, the processes of 
control of the temperatures of the first through the third heating zones 
Z1 through Z3 are performed by adaptive control, while on the other hand 
the processes of control of the temperatures of the fourth and the fifth 
heating zones Z4 and Z5 are performed by I-PD control. 
The reference numeral 26 denotes an adaptive control unit for performing 
this adaptive control of the temperatures of the first through the third 
heating zones Z1 through Z3. This adaptive control unit 26 sets up a 
plurality of parameters for the first through the third heating zones Z1 
through Z3, and, when the target values ts1 through ts3 for the 
temperatures of said first through the third heating zones Z1 through Z3 
are inputted as set up on the operation panel 23, selects the parameters 
which correspond to these target values ts1 through ts3 so as to perform 
temperature control of the heating temperatures of the band heaters H1 
through H3 with certain manipulated variables Un. The calorific values Gn 
of the heating zones Z1 through Z3 are detected by the corresponding 
thermocouples T1 through T3 respectively, or in other words the 
temperatures of the corresponding parts of the inner wall portion of the 
wall portion 18 of the heating cylinder device 12 are detected, and the 
controlled variables tn are inputted into the adaptive control unit 26. 
But these controlled variables are contaminated by external influences and 
interferences. Therefore, the adaptive control unit 26 evaluates the 
parameters according to the manipulated variables Un and the controlled 
variables tn, or in other words evaluates whether the temperature control 
is being performed with the optimum parameters among other parameters 
(because it should be remembered that a plurality of such parameters are 
prepared in advance); and the evaluated variables An thus prepared are fed 
back to the adaptive control unit 26 for temperature controlling the 
heating zones Z1 through Z3 with the optimum parameters. 
Thus, by adapting the outer diameter of the wall portion 18 of the heating 
cylinder device 12 to the particular requirements of each of the three 
heating zones Z1 through Z3, according to their heat capacities, in other 
words by reducing the outer diameter of said wall portion 18 in 
consideration of the desirability of responsiveness of the temperature 
control, in addition to temperature controlling the respective heating 
zones Z1 through Z3, the influences of thermal interferences between the 
heating zones Z1 through Z3 may be largely eliminated, and fluctuations of 
the temperature of the resin which is to be forwarded to the fourth 
heating zone Z4 may be kept minimal. 
The reference numeral 27 denotes an IP-D control unit for performing the 
IP-D control of the temperatures of the fourth and fifth heating zones Z4 
and Z5. This IP-D control unit 27 is set up with a single parameter for 
the temperature control of each of the fourth and fifth heating zones Z4 
and Z5, and, when the target values ts4 and ts5 for the temperatures of 
said fourth and fifth heating zones Z4 and Z5 are inputted as set up on 
the operation panel 23, performs temperature control of the heating 
temperatures of the band heaters H2 and H5 for these heating zones Z4 and 
Z5 with the controlled variables Un for each of the parameters. Because 
the calorific values of the heating zones Z4 and Z5 are detected by the 
respective thermocouples T4 and T5, and the detected variables tn are 
subject to some admixture of external influences and interferences, these 
detected variables tn are fed back to the IP-D control unit 27 for 
temperature control. 
Thus, by adapting the outer diameter of the wall portion 18 of the heating 
cylinder device 12 to the particular requirement of the fourth heating 
zone Z4, according to its heat capacity, in other words by increasing the 
outer diameter of said wall portion 18 in consideration of the 
desirability of increasing its thermal capacity, in addition to 
temperature controlling the heating zones Z4 and Z5, the temperature of 
the resin material to be injected through the nozzle 21 is made uniform 
and is stabilized at a fixed temperature value, and high precision molding 
is made possible. As for the thermal interference G between the first 
through the third heating zones Z1 through Z3 and the fourth and the fifth 
heating zones Z4 and Z5, it is eliminated by calculating the deviations Bn 
and by feeding them back to the controller. 
Thus, according to the present invention, the thermal interference between 
the neighboring ones of the heating zones Z1 through Z5 is kept minimal, 
because the outer diameters of the relevant parts of the wall portion 18 
of the heating cylinder device 12 are adapted to the particular 
requirements of these heating zones Z1 through Z5, so as to provide 
heating capacities corresponding to the heating temperatures of the zones 
Z1 through Z5. 
Thus, according to this first preferred embodiment of the present 
invention, there is provided a heating cylinder device for a molding 
machine which can keep the injection cycle of the machine short, thus 
improving the productivity of the machine and reduces the cost of 
operation and thus the cost of the finished products. Further, the power 
consumption is reduced as much as practicable, and the temperature control 
of the resin is improved, and the responsiveness of the temperature 
control is also improved. Thus, this heating cylinder device for a molding 
machine minimizes fluctuations in the system due to the motion of the 
resin material which is being heated up, changes in the temperature of the 
resin material, dissipation of heat in injecting the resin material, and 
so on. Thereby, this heating cylinder device for a molding machine 
promotes the production of more precise finished molded products, by 
providing proper heat management by keeping the thermal interference 
between neighboring ones of heating zones thereof as low as possible, as 
well as by keeping the thermal interference from outside sources as low as 
possible. 
In FIG. 5, there is shown a sectional view of a heating cylinder device 12 
according to the second preferred embodiment of the present invention, 
taken in a fashion similar to FIG. 2 in a sectional plane containing the 
axis of said heating cylinder device; in FIG. 5, reference symbols like to 
those of FIGS. 1 and 2 relating to the first preferred embodiment denote 
like parts and zones. This heating cylinder device 12 is for being fitted 
into an injection molding machine like the machine 10 shown in FIG. 1 
relating to the first preferred embodiment, comprising a hopper for 
charging the resin, the heating cylinder device 12, a screw drive device 
for rotatively driving a screw piston 20 incorporated in said heating 
cylinder device 12 for injecting the molten resin, and a movable plate 
drive device for removing the molded products by opening and closing a 
metallic die which is mounted between a fixed plate and a laterally 
movable plate; this machine is not particularly shown in the figures, 
because its construction may be substantially identical to that of the 
FIG. 1 machine. 
The heating cylinder device 12, in this second preferred embodiment, again 
is generally formed in a cylindrical shape with a central axial hole 19 
formed through a cylinder wall portion 18, and with a screw piston 20 
mentioned above fitted in said central axial hole 19, so as when rotated 
in a certain direction by the aforementioned screw drive device 13 to move 
to the left in the figure into said hole 19 so as to apply compression 
force to resin in said hole 19, and so as when rotated in the opposite 
direction to said certain direction to be moved to the right in the figure 
and to be withdrawn out of said hole 19. When said screw piston 20 is thus 
withdrawn from the hole 19 to a position beyond a certain position, resin 
charged in the hopper 11 can travel downwards into the hole 19 to recharge 
the heating cylinder device 12. A nozzle 21 is provided at the opposite 
end (the left end) of the heating cylinder device 12 from the hopper 11 
(which is at the right end). Thus, as the screw piston 20 is alternately 
rotated in said certain direction and in the opposite direction to said 
certain direction, it is alternately forced into the hole 19 and withdrawn 
therefrom, thus alternately compressing resin in said hole 19 and forcing 
it out through the nozzle 21, and recharging said hole 19 with fresh resin 
from the hopper 11. 
In the heating cylinder device 12, as before in the FIG. 2 device, there 
are altogether defined five heating zones, designated as Z1 through Z5, 
and axially spaced along the axis of said heating cylinder device 12 from 
the right to the left as seen in FIG. 5, i.e. from the end thereof at 
which the hopper 11 is provided to the end thereof at which the nozzle 21 
is provided. Around each of these heating zones Z1 through Z5 there is 
fitted a corresponding heater H1 through H5, which is formed as a band 
extending right around the cylinder of the heating cylinder device 12, and 
in the inner wall portion of the heating cylinder device 12, in each of 
said heating zones Z1 through Z5, there is again fitted a corresponding 
thermocouple T1 through T5. 
In detail, again, the first heating zone Z1 is the portion of the heating 
cylinder device 12 into which the resin is supplied from the hopper 11, 
and is heated by the heater H1 and is also water cooled so that the resin 
may be supplied from the hopper 11 without any risk of its surface being 
melted. And the thermocouple T1 detects the temperature in this first 
heating zone Z1. The second heating zone Z2 is a portion of the heating 
cylinder device 12 in which the resin is, next, heated up substantially 
only by the heater H2, and the thermocouple T2 detects the temperature in 
this second heating zone Z2. The third heating zone Z3 is a portion of the 
heating cylinder device 12 in which the resin is, next, heated up both by 
the heater H3 and by the frictional heat generated by the rotation of and 
by the compression effect generated by the screw piston 20; and the 
thermocouple T3 detects the temperature in this third heating zone Z3. The 
fourth heating zone Z4 is a reservoir in which the resin material to be 
injected is received for a certain time interval before being injected, 
and is required to be kept at a certain high temperature; in this portion 
of the heating cylinder device 12, the resin is heated up by the heater 
H4, and the thermocouple T4 detects the temperature in this fourth heating 
zone Z4. And the fifth heating zone Z5, which is just before the nozzle 
21, is a portion of the heating cylinder device 12 in which the resin is 
particularly subject to disturbance of its temperature by external 
influences such as the heat capacity of the metallic die 16 and the 
atmosphere; and, in order to eliminate such external influencese, the 
resin in this fifth heating zone Z5 is kept hot by the heater H5, and the 
thermocouple T5 detects the temperature in this fifth heating zone Z5. 
Now, particularly according to the particularly specialized inventive 
concept of this second preferred embodiment of the present invention, the 
wall portion 18 of the heating cylinder device 12 is structured, not as in 
the prior art described above as a uniform cylinder of the same inner and 
outer diameters along its longitudinal length, but with annular 
circumferentially extending grooves 38 spaced apart along its longitudinal 
length. However, in contrast to the first preferred embodiment described 
above, the outer diameters of the parts of the wall portion 18 of the 
heating cylinder device 12 which define the first heating zone Z1, the 
second heating zone Z2, the third heating zone Z3, and the fourth heating 
zone Z4 are all substantially the same; while as before the outer diameter 
of the wall portion 18 of the heating cylinder device 12 at the fifth 
heating zone Z5 is much smaller than at all the other heating zones Z1 
through Z4. Thus, the portions of the wall portion 18 which define the 
heating zones Z1 through Z4 are each of approximately the same thickness, 
in this second preferred embodiment. However, by the provision of the 
annular grooves 38, the heat capacities of the portions of the wall 
portion 18 of the heating cylinder device 12 in between those portions 
thereof which define the first heating zone Z1, the second heating zone 
Z2, the third heating zone Z3, and the fourth heating zone Z4 are made to 
be very much lower than the heat capacities of said portions which define 
said heating zones Z1 through Z4, and further the heat transmission 
capacities of said in between portions are made to be very low; so that, 
substantially, the portions of the wall portion 18 of the heating cylinder 
device 12 in between those portions thereof which define the first heating 
zone Z1, the second heating zone Z2, the third heating zone Z3, and the 
fourth heating zone Z4 are thermally completely isolated from one another. 
This thermal isolation is further promoted by the further constructional 
detail that annular ring members 29 made of a thermally insulating 
material are fitted into the grooves 38, so as further to hamper thermal 
transfer by conduction across said grooves 38 between adjoining ones of 
the heating zones Z1 through Z4, and so as further to substantially 
prevent heat transfer by radiation and by convection between said heating 
zones Z1 through Z4. It should be noted, however, that these insulating 
annular ring members 29 are not strictly necessary for implementing the 
concept of this second preferred embodiment of the present invention, in 
its most basic form, and may be omitted in some cases. 
This heating cylinder device 12 according to the second preferred 
embodiment of the present invention may be controlled by a control system 
similar to that described above with reference to FIGS. 3 and 4 with 
respect to the first preferred embodiment; details are omitted herein in 
the interests of brevity of description. 
Although in the above FIG. 5 relating to this shown second preferred 
embodiment the widths of the grooves 38 are shown as being substantially 
the same, it would be possible to vary the widths of these grooves 38, as 
a further refinement of the inventive concept of said second preferred 
embodiment. 
Thus, by providing the grooves 38 as thermally separating the heating zones 
Z1 through Z4 from one another, and optionally by further providing the 
insulating annular rings 29 as located therein, in addition to temperature 
controlling the respective heating zones Z1 through Z3, the influences of 
thermal interferences between the heating zones Z1 through Z4 may be 
largely eliminated, and fluctuations of the temperature of the resin which 
is to be forwarded to the fifth heating zone Z5 may be kept minimal. 
Thus, also according to this second preferred embodiment of the present 
invention, there is provided a heating cylinder device for a molding 
machine which can keep the injection cycle of the machine short, thus 
improving the productivity of the machine and reduces the cost of 
operation and thus the cost of the finished products. Further, the power 
consumption is reduced as much as practicable, and the temperature control 
of the resin is improved, and the responsiveness of the temperature 
control is also improved. Thus, this heating cylinder device for a molding 
machine minimizes fluctuations in the system due to the motion of the 
resin material which is being heated up, changes in the temperature of the 
resin material, dissipation of heat in injecting the resin material, and 
so on. Thereby, this heating cylinder device for a molding machine 
promotes the production of more precise finished molded products, by 
providing proper heat management by keeping the thermal interference 
between neighboring ones of heating zones thereof as low as possible, as 
well as by keeping the thermal interference from outside sources as low as 
possible. 
In FIG. 6, there is shown a sectional view of a heating cylinder device 12 
according to the third preferred embodiment of the present invention, 
taken in a fashion similar to FIGS. 2 and 5 in a sectional plane 
containing the axis of said heating cylinder device; in FIG. 6, reference 
symbols like to those of FIGS. 1 and 2 relating to the first preferred 
embodiment and FIG. 5 relating to the second preferred embodiment denote 
like parts and zones. This heating cylinder device 12 again is for being 
fitted into an injection molding machine like the machine 10 shown in FIG. 
1 relating to the first preferred embodiment, comprising a hopper for 
charging the resin, the heating cylinder device 12, a screw drive device 
for rotatively driving a screw piston 20 incorporated in said heating 
cylinder device 12 for injecting the molten resin, and a movable plate 
drive device for removing the molded products by opening and closing a 
metallic die which is mounted between a fixed plate and a laterally 
movable plate; again, this machine is not particularly shown in the 
figures, because its construction may be substantially identical to that 
of the FIG. 1 machine. 
The heating cylinder device 12, in this third preferred embodiment, again 
is generally formed in a cylindrical shape with a central axial hole 19 
formed through a cylinder wall portion 18, and with a screw piston 20 
mentioned above fitted in said central axial hole 19, so as when rotated 
in a certain direction by the aforementioned screw drive device 13 to move 
to the left in the figure into said hole 19 so as to apply compression 
force to resin in said hole 19, and so as when rotated in the opposite 
direction to said certain direction to be moved to the right in the figure 
and to be withdrawn out of said hole 19. When said screw piston 20 is thus 
withdrawn from the hole 19 to a position beyond a certain position, resin 
charged in the hopper 11 can travel downwards into the hole 19 to recharge 
the heating cylinder device 12. A nozzle 21 is provided at the opposite 
end (the left end) of the heating cylinder device 12 from the hopper 11 
(which is at the right end). Thus, as the screw piston 20 is alternately 
rotated in said certain direction and in the opposite direction to said 
certain direction, it is alternately forced into the hole 19 and withdrawn 
therefrom, thus alternately compressing resin in said hole 19 and forcing 
it out through the nozzle 21, and recharging said hole 19 with fresh resin 
from the hopper 11. 
In the heating cylinder device 12, as before in the FIG. 2 and FIG. 5 
devices, there are altogether defined five heating zones, designated as Z1 
through Z5, and axially spaced along the axis of said heating cylinder 
device 12 from the right to the left as seen in FIG. 6, i.e. from the end 
thereof at which the hopper 12 is provided to the end thereof at which the 
nozzle 21 is provided. Around each of these heating zones Z1 through Z5 
there is fitted a corresponding heater H1 through H5, and in the inner 
wall portion of the heating cylinder device 12, in each of said heating 
zones Z1 through Z5, there is again fitted a corresponding thermocouple T1 
through T5. 
In detail, again, the first heating zone Z1 is the portion of the heating 
cylinder device 12 into which the resin is supplied from the hopper 11, 
and is heated by the heater H1 and is also water cooled so that the resin 
may be supplied from the hopper 11 without any risk of its surface being 
melted. And the thermocouple T1 detects the temperature in this first 
heating zone Z1. The second heating zone Z2 is a portion of the heating 
cylinder device 12 in which the resin is, next, heated up substantially 
only by the heater H2, and the thermocouple T2 detects the temperature in 
this second heating zone Z2. The third heating zone Z3 is a portion of the 
heating cylinder device 12 in which the resin is, next, heated up both by 
the heater H3 and by the frictional heat generated by the rotation of and 
by the compression effect generated by the screw piston 20; and the 
thermocouple T3 detects the temperature in this third heating zone Z3. The 
fourth heating zone Z4 is a reservoir in which the resin material to be 
injected is received for a certain time interval before being injected, 
and is required to be kept at a certain high temperature; in this portion 
of the heating cylinder device 12, the resin is heated up by the heater 
H4, and the thermocouple T4 detects the temperature in this fourth heating 
zone Z4. And the fifth heating zone Z5, which is just before the nozzle 
21, is a portion of the heating cylinder device 12 in which the resin is 
particularly subject to disturbance of its temperature by external 
influences such as the heat capacity of the metallic die 16 and the 
atmosphere; and, in order to eliminate such external influencese, the 
resin in this fifth heating zone Z5 is kept hot by the heater H5, and the 
thermocouple T5 detects the temperature in this fifth heating zone Z5. 
Now, as in the second preferred embodiment described above, the wall 
portion 18 of the heating cylinder device 12 is structured (however not 
with any annular circumferentially extending grooves spaced apart along 
its longitudinal length) with the outer diameters of the parts of the wall 
portion 18 of the heating cylinder device 12 which define the first 
heating zone Z1, the second heating zone Z2, the third zone Z3, and the 
fourth heating zone Z4 all being substantially the same; while as before 
the outer diameter of the wall portion 18 of the heating cylinder device 
12 at the fifth heating zone Z5 is much smaller than at all the other 
heating zones Z1 through Z4. Thus, the portions of the wall portion 18 
which define the heating zones Z1 through Z4 are each of approximately the 
same thickness, in this third preferred embodiment. However, particularly 
according to the particularly specialized inventive concept of this third 
preferred embodiment of the present invention, while the fifth heater H5 
is as before formed as a band extending right around the cylinder of the 
heating cylinder device 12, the other four heaters H1 through H4, although 
still band shaped, are now buried deep within the wall portion 18 of said 
heating cylinder device 12. In other words, these heaters H1 through H4 
are arranged to be as close in the radial direction to the interior hole 
19 of the heating cylinder device 12 as possible, i.e. as close to the 
molten resin passing through said interior hole 19 as possible. A band 28 
of insulating material is wrapped around the part of the wall portion 18 
of the heating cylinder device 12 which defines the fourth heating zone 
Z4, for providing greater heat capacity and better insulating performance. 
This heating cylinder device 12 according to the third preferred embodiment 
of the present invention may be controlled by a control system similar to 
that described above with reference to FIGS. 3 and 4 with respect to the 
first preferred embodiment; details are omitted herein in the interests of 
brevity of description. 
Thus, by providing the heaters H1 through H4 as buried within the wall 
portion 18 of said heating cylinder device 12, and as close in the radial 
direction to the interior hole 19 of the heating cylinder device 12 as 
possible, i.e. as close to the molten resin passing through said interior 
hole 19 as possible, thermal transmission from said heaters H1 to H4 to 
the molten resin material is made as easy as practicable, and the 
responsiveness of the control system is improved, whereby fluctuations of 
the temperature of the resin which is to be forwarded to the fifth heating 
zone Z5 may be kept minimal. 
Thus, also according to this third preferred embodiment of the present 
invention, there is provided a heating cylinder device for a molding 
machine which can keep the injection cycle of the machine short, thus 
improving the productivity of the machine and reduces the cost of 
operation and thus the cost of the finished products. Further, the power 
consumption is reduced as much as practicable, and the temperature control 
of the resin is improved, and the responsiveness of the temperature 
control is also improved. Thus, this heating cylinder device for a molding 
machine minimizes fluctuations in the system due to the motion of the 
resin material which is being heated up, changes in the temperature of the 
resin material, dissipation of heat in injecting the resin material, and 
so on. Thereby, this heating cylinder device for a molding machine 
promotes the production of more precise finished molded products, by 
providing proper heat management by keeping the thermal interference 
between neighboring ones of heating zones thereof as low as possible, as 
well as by keeping the thermal interference from outside sources as low as 
possible. 
In FIG. 7, there is shown a sectional view of a heating cylinder device 12 
according to the fourth preferred embodiment of the present invention, 
taken in a fashion similar to FIGS. 2, 5, and 6 in a sectional plane 
containing the axis of said heating cylinder device; in FIG. 7, reference 
symbols like to those of FIGS. 1 and 2 relating to the first preferred 
embodiment and FIGS. 5 and 6 relating to the second and third preferred 
embodiments denote like parts and zones. This heating cylinder device 12 
again is for being fitted into an injection molding machine like the 
machine 10 shown in FIG. 1 relating to the first preferred embodiment, 
comprising a hopper for charging the resin, the heating cylinder device 
12, a screw drive device for rotatively driving a screw piston 20 
incorporated in said heating cylinder device 12 for injecting the molten 
resin, and a movable plate drive device for removing the molded products 
by opening and closing a metallic die which is mounted between a fixed 
plate and a laterally movable plate; again, this machine is not 
particularly shown in the figures, because its construction may be 
substantially identical to that of the FIG. 1 machine. 
The heating cylinder device 12, in this fourth preferred embodiment, again 
is generally formed in a cylindrical shape with a central axial hole 19 
formed through a cylinder wall portion 18, and with a screw piston 20 
mentioned above fitted in said central axial hole 19, so as when rotated 
in a certain direction by the aforementioned screw drive device 13 to move 
to the left in the figure into said hole 19 so as to apply compression 
force to resin in said hole 19, and so as when rotated in the opposite 
direction to said certain direction to be moved to the right in the figure 
and to be withdrawn out of said hole 19. When said screw piston 20 is thus 
withdrawn from the hole 19 to a position beyond a certain position, resin 
charged in the hopper 11 can travel downwards into the hole 19 to recharge 
the heating cylinder device 12. A nozzle 21 is provided at the opposite 
end (the left end) of the heating cylinder device 12 from the hopper 11 
(which is at the right end). Thus, as the screw piston 20 is alternately 
rotated in said certain direction and in the opposite direction to said 
certain direction, it is alternately forced into the hole 19 and withdrawn 
therefrom, thus alternately compressing resin in said hole 19 and forcing 
it out through the nozzle 21, and recharging said hole 19 with fresh resin 
from the hopper 11. 
In the heating cylinder device 12, as before in the devices of FIGS. 2, 5, 
and 6, there are altogether defined five heating zones, designated as Z1 
through Z5, and axially spaced along the axis of said heating cylinder 
device 12 from the right to the left as seen in FIG. 7, i.e. from the end 
thereof at which the hopper 12 is provided to the end thereof at which the 
nozzle 21 is provided. Around each of these heating zones Z1 through Z5 
there is fitted a corresponding heater H1 through H5, and in the inner 
wall portion of the heating cylinder device 12, in each of said heating 
zones Z1 through Z5, there is again fitted a corresponding thermocouple T1 
through T5. 
In detail, yet again, the first heating zone Z1 is the portion of the 
heating cylinder device 12 into which the resin is supplied from the 
hopper 11, and is heated by the heater H1 and is also water cooled so that 
the resin may be supplied from the hopper 11 without any risk of its 
surface being melted. And the thermocouple T1 detects the temperature in 
this first heating zone Z1. The second heating zone Z2 is a portion of the 
heating cylinder device 12 in which the resin is, next, heated up 
substantially only by the heater H2, and the thermocouple T2 detects the 
temperature in this second heating zone Z2. The third heating zone Z3 is a 
portion of the heating cylinder device 12 in which the resin is, next, 
heated up both by the heater H3 and by the frictional heat generated by 
the rotation of and by the compression effect generated by the screw 
piston 20; and the thermocouple T3 detects the temperature in this third 
heating zone Z3. The fourth heating zone Z4 is a reservoir in which the 
resin material to be injected is received for a certain time interval 
before being injected, and is required to be kept at a certain high 
temperature; in this portion of the heating cylinder device 12, the resin 
is heated up by the heater H4, and the thermocouple T4 detects the 
temperature in this fourth heating zone Z4. And the fifth heating zone Z5, 
which is just before the nozzle 21, is a portion of the heating cylinder 
device 12 in which the resin is particularly subject to disturbance of its 
temperature by external influences such as the heat capacity of the 
metallic die 16 and the atmosphere; and, in order to eliminate such 
external influencese, the resin in this fifth heating zone Z5 is kept hot 
by the heater H5, and the thermocouple T5 detects the temperature in this 
fifth heating zone Z5. 
Now, as in the second and third preferred embodiments described above, the 
wall portion 18 of the heating cylinder device 12 is structured (however 
not with any annular circumferentially extending grooves spaced apart 
along its longitudinal length) with the outer diameters of the parts of 
the wall portion 18 of the heating cylinder device 12 which define the 
first heating zone Z1, the second heating zone Z2, the third heating zone 
Z3, and the fourth heating zone Z4 all being substantially the same; while 
as before the outer diameter of the wall portion 18 of the heating 
cylinder device 12 at the fifth heating zone Z5 is much smaller than at 
all the other heating zones Z1 through Z4. Thus, the portions of the wall 
portion 18 which define the heating zones Z1 through Z4 are each of 
approximately the same thickness, in this fourth preferred embodiment. 
However, particularly according to the particularly specialized inventive 
concept of fourth preferred embodiment of the present invention, all of 
the first through the fifth heaters H1 through H5 are as in the first 
preferred embodiment of FIG. 2 formed as bands extending right around the 
cylinder of the heating cylinder device 12, so that the four heaters H1 
through H4 are not buried deep within the wall portion 18 of said heating 
cylinder device 12, as was the case in the third preferred embodiment 
shown above; and around the first heater H1 there is provided no 
particular layer of insulating material, while around the second, third, 
and fourth heaters H2, H3, and H4 there is provided a first layer 28' of 
insulating material, around the third and fourth heaters H3 and H4 there 
is further provided a second layer 39 of insulating material on top of 
said first layer 28', and around the fourth heater H4, only, there is yet 
further provided a third layer 30 of insulating material on top of said 
first layer 28' and said second layer 39. And in the shown particular 
construction, although this is not intended to be limiting, all these 
layers 28', 29, and 30 of insulating material are of substantially the 
same thickness. A suitable material for use as this insulating material is 
glass wool. In other words, the first heater H1 for the first heating zone 
Z1 is not wrapped with any insulating material layer, the second heater H2 
for the second heating zone Z2 is wrapped with one layer of insulating 
material, the third heater H3 for the third heating zone Z3 is wrapped 
with two layers of insulating material, and the heater H4 for the fourth 
heating zone Z4 is wrapped with three layers of insulating material, so 
that the thickness of the insulating material provided for each zone 
corresponds to the heat capacity required for that zone. I.e., the heat 
capacities of the various heating zones Z1 through Z4 are adapted to the 
respective temperatures at which they are required to operate. That is, 
the insulation is omitted in the case of the first and the fifth heating 
zones Z1 and Z5, in which it is required to transfer the controlled 
temperature of the respective heaters Hl and H5 to the resin material, so 
as to reduce their heat capacities, while on the other hand in the case of 
the fourth heating zone Z4, which is required to be maintained at a 
certain temperature, a thick layer of insulating material is provided, in 
order to make its heat capacity high; and the cases of the second and 
third heating zones Z2 and Z3 are intermediate between these two extremes. 
This heating cylinder device 12 according to the fourth preferred 
embodiment of the present invention may be controlled by a control system 
similar to that described above with reference to FIGS. 3 and 4 with 
respect to the first preferred embodiment; details are again omitted 
herein in the interests of brevity of description. 
Thus, by providing the layers of insulating material for the three heaters 
H2 through H4, and by determining the thicknesses of said layers in 
consideration of the heat capacities required for proper temperature 
control of the respective heating zones Z1 through Z5, or in other words 
by considering the responsiveness of the temperature control, in addition 
to temperature controlling the respective heating zones Z1 through Z5, the 
influences of thermal interferences between the heating zones Z1 through 
Z5 may be eliminated, and the responsiveness of the control system is 
improved, whereby fluctuations of the temperature of the resin which is to 
be forwarded to the fifth heating zone Z5 and to the nozzle 21 may be kept 
minimal. 
Thus, also according to this fourth preferred embodiment of the present 
invention, there is provided a heating cylinder device for a molding 
machine which can keep the injection cycle of the machine short, thus 
improving the productivity of the machine and reduces the cost of 
operation and thus the cost of the finished products. Further, the power 
consumption is reduced as much as practicable, and the temperature control 
of the resin is improved, and the responsiveness of the temperature 
control is also improved. Thus, this heating cylinder device for a molding 
machine minimizes fluctuations in the system due to the motion of the 
resin material which is being heated up, changes in the temperature of the 
resin material, dissipation of heat in injecting the resin material, and 
so on. Thereby, this heating cylinder device for a molding machine 
promotes the production of more precise finished molded products, by 
providing proper heat management by keeping the thermal interference 
between neighboring ones of heating zones thereof as low as possible, as 
well as by keeping the thermal interference from outside sources as low as 
possible. 
Although the present invention has been shown and described with reference 
to the preferred embodiments thereof, and in terms of the illustrative 
drawings, it should not be considered as limited thereby. Various possible 
modifications, omissions, and alterations could be conceived of by one 
skilled in the art to the form and the content of any particular 
embodiment, without departing from the scope of the present invention. For 
example, although the various embodiments of the present invention which 
have been shown are all directed to its application to an injection 
molding machine, the present invention is not to be considered as limited 
to such an application. Therefore, it is desired that the scope of the 
present invention, and of the protection sought to be granted by Letters 
Patent, should be defined not by any of the perhaps purely fortuitous 
details of the shown preferred embodiments, or of the drawings, but solely 
by the scope of the appended claims, which follow.