JP2003117956A - Mold assembly and injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify work for the maintenance/control of an injection molding machine and to sufficiently suppress the generation of stringing. SOLUTION: This mold assembly has a mold body, a sprue bush 24, a stringing preventing member arranged in contact with the sprue bush 24 and a holding member arranged in contact with the stringing preventing member to prevent the falling of the stringing preventing member. The heat of an injection nozzle and the heat of the resin in the injection nozzle are transmitted to the stringing preventing member accompanied by the pressing of the injection nozzle to a fixed mold 12 and further transmitted to the holding member and the sprue bush 24 from the stringing preventing member. The movement of heat from the injection nozzle to the holding member and the sprue bush is accelerated and, since only the temperature of the front end of the injection nozzle becomes low, the viscosity of the resin in the cut part formed in the injection nozzle can increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device and an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure to fill a cavity space of a mold device.
After being cooled and solidified in the cavity space, it is taken out as a molded product.

The injection molding machine comprises a mold device, a mold clamping device and an injection device. The mold device comprises a fixed mold and a movable mold. The mold clamping device comprises a fixed platen, a movable platen and a mold. It is equipped with a tightening motor. Then, by driving the mold clamping motor to move the movable platen forward and backward relative to the fixed platen, mold closing, mold clamping and mold opening of the mold device can be performed. A cavity space is formed between the fixed mold and the movable mold as the mold device is clamped.

On the other hand, the injection device includes a heating cylinder for heating and melting the resin supplied from the hopper, an injection nozzle for injecting the melted resin, and the like. A screw is provided in the heating cylinder. It is arranged to be rotatable and movable back and forth. Then, the screw
The resin is weighed by rotating it by the measuring motor and retracting it with it, and by advancing it by the injection motor, the resin is injected from the injection nozzle and filled in the cavity space.

Next, the injection nozzle will be described.

FIG. 2 is a sectional view showing a main part of a conventional injection molding machine.

In the figure, reference numeral 11 is a cylindrical injection nozzle, and the injection nozzle 11 comprises a cylindrical main body 50 and a nozzle heater 13 arranged on the outer peripheral surface of the main body 50.
A resin channel 50a is formed in the main body 50. By energizing the nozzle heater 13, the resin in the resin flow channel 50a can be heated.

The injection nozzle 11 is attached to the front end of a heating cylinder (not shown) so that the resin flow path formed in the heating cylinder and the resin flow path 50a communicate with each other. At the front end of the injection nozzle 11 (the left end in the figure), the taper portion 19 and the reverse taper portion 20 are formed by the resin flow path 50a, and the diameter of the boundary portion between the taper portion 19 and the reverse taper portion 20 is the smallest. A cutting portion S1 for cutting the resin is formed on the. In addition, the injection nozzle 11
A nozzle hole 51 having a predetermined inner diameter is formed on the front end surface (left end surface in the figure) of the.

Then, in the injection process, the injection device is moved forward, and the injection nozzle 11 is fixed to the fixed mold 1 of the mold device.
When the screw in the heating cylinder is moved forward by driving an injection motor (not shown), the resin (not shown) stored in front of the screw is injected from the injection nozzle 11, and the fixed mold 1 is pressed.
A cavity space (not shown) is filled through a sprue 16 formed in the sprue bush 5 and a runner (not shown).

After that, when the mold device is cooled, the resin filled in the cavity space is cooled and solidified into a molded product, and the mold device is opened to remove the molded product. Be done. Further, as the mold apparatus is cooled, the resin in the runner and the sprue 16 is solidified together with the molded product to form a runner / sprue portion. The runner sprue portion is taken out together with the molded product when the mold opening is performed.

At this time, the resin in the resin flow path 50a is cut at the cutting portion S1 and separated into the taper portion 19 side and the reverse taper portion 20 side.

By the way, in the metering process, the injection device is retracted and the injection nozzle 11 is separated from the fixed mold 15. However, when it is necessary to use a resin whose viscosity becomes low in a molten state, the inner diameter of the nozzle hole 51 is changed. When it is necessary to increase the size, threading occurs at the front end of the injection nozzle 11, and a thread-like portion is formed integrally with the runner / sprue portion. Then, if the thread-like portion adheres to the surface of the molded product or the fixed mold 15 on the cavity space side, defective molding will occur.

Therefore, there is provided an injection molding machine capable of suppressing the occurrence of stringing.

In this case, a cap made of a material having high thermal conductivity is attached to the front end of the injection nozzle 11. Therefore, the transfer of heat from the injection nozzle 11 to the sprue bush is promoted, and only the temperature of the front end of the injection nozzle 11 is lowered, so that the viscosity of the resin in the cutting portion S1 can be increased and stringing occurs. Can be suppressed.

[0015]

However, in the conventional injection molding machine described above, when the injection nozzle 11 is pressed against the fixed mold 15 through the cap, a large stress is applied to the cap, so that the shape of the cap is changed. In some cases, it is not possible to ensure sufficient strength, and the cap is frequently damaged. The cap is the injection nozzle 1
Since it is sandwiched by 1 and the fixed mold 15, the state of attachment to the injection nozzle 11 becomes unstable, and when the injection nozzle 11 is retracted (moved to the right in the figure), the cap drops from the injection nozzle 11. Sometimes. Therefore, the work for maintenance and management of the injection molding machine is troublesome.

Further, depending on the molding temperature, the transfer of heat from the injection nozzle 11 to the sprue bush cannot be sufficiently promoted, and the occurrence of stringing cannot be sufficiently suppressed.

According to the present invention, the problems of the conventional injection molding machine can be solved, the work for maintenance and management can be simplified, and the occurrence of stringing can be sufficiently suppressed. An object is to provide a mold device and an injection molding machine.

[0018]

Therefore, in the mold apparatus of the present invention, the mold main body, the sprue bush set in the sprue bush accommodating portion of the mold main body, and the sprue bush are brought into contact with each other. It has a stringing prevention member arranged and a holding member arranged in contact with the stringing prevention member to prevent the stringing prevention member from falling.

In another mold apparatus of the present invention, the stringing prevention member is made of a material having high thermal conductivity.

In still another mold apparatus according to the present invention, the stringing prevention member has a shape corresponding to the front end of the injection nozzle.

In still another mold device of the present invention, the stringing prevention member further includes a flange portion. Then, the flange portion is sandwiched by the holding member and the sprue bush.

In still another mold apparatus of the present invention, a channel for supplying a temperature control medium is further formed in the sprue bush.

In the injection molding machine of the present invention, a platen, a mold body attached to the platen via a mounting plate, a sprue bush set in a sprue bush accommodating portion of the mold body, and the sprue bushing. And a holding member that is disposed in contact with the stringing prevention member and the platen and that prevents the stringing prevention member from falling.

A flow path for supplying a temperature control medium is formed in the platen.

In another injection molding machine of the present invention, the stringing prevention member is made of a material having high thermal conductivity.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing an essential part of an injection molding machine according to an embodiment of the present invention, FIG. 3 is a sectional view of a stringing prevention plate according to an embodiment of the present invention, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a front view of the stringing prevention plate in FIG. 5, and FIG. 5 is a cross-sectional view showing an injection molding machine during an injection step in the embodiment of the present invention.

The injection molding machine comprises a mold device, a mold clamping device and an injection device 61. The mold device comprises a fixed platen 10 as a platen and bolts b11, 1 via a mounting plate 17.
2 includes a fixed mold 12 attached by 2 and a movable mold (not shown). The mold clamping device includes the fixed platen 10, a movable platen (not shown), and a mold clamping motor (not shown).

The fixed mold 12 is provided with a bolt b2.
1, a base plate 18 attached to the attachment plate 17, a disc plate 25 attached to the base plate 18 by a bolt b22, and the disc plate 2
An annular guide ring 27 formed to project forward (leftward in FIGS. 1 and 5) along the outer peripheral edge of 5 and attached to the base plate 18 by a bolt b23, and fixed radially inward from the attachment plate 17. Platen 10
Locating ring 2 that is disposed so as to face the base plate 18 and is attached to the base plate 18 by a bolt b24 to position the base plate 18 with respect to the fixed platen 10.
3 and a sprue bush 24 disposed adjacent to the locate ring 23 in the base plate 18. The base plate 18, the disc plate 25 and the guide ring 27 constitute a mold body. The locate ring 23 is attached to the mounting plate 17
Is placed in contact with.

The sprue bush 24 is provided with a small-diameter tubular portion 29 and a flange portion 31 formed at the rear end (the right end in FIGS. 1 and 5) of the tubular portion 29, and is provided in the base plate 18 and the disc plate. 25 can be extended. Therefore, the first through hole 3 is formed in the base plate 18 so as to correspond to the tubular portion 29 and the flange portion 31.
A second through hole 33 is formed in the disk plate 25 so as to correspond to the tubular portion 29 and communicate with the first through hole 32. The first through hole 32 has a small diameter portion 36 that accommodates the tubular portion 29 and a large diameter portion 37 that accommodates the flange portion 31. The first and second through holes 32 and 33 form a sprue bush accommodating portion for setting the sprue bush 24.

The resin (not shown) injected from the injection nozzle 62 of the injection device 61 is applied from the rear end surface (right end surface in FIGS. 1 and 5) to the front end surface (left end surface in FIGS. 1 and 5) of the sprue bush 24. A sprue 26 is formed for passage. Further, a flow channel 45 for cooling the sprue bush 24 is formed in the flange portion 31, the flow channel 45 and a temperature controller (not shown) are connected, and a temperature from the temperature controller to the flow channel 45 is provided. Not-shown temperature control water as a control medium is supplied, and the temperature control water maintains the sprue bush 24 at a predetermined temperature. A flow channel 55 is formed in the stationary platen 10, the flow channel 55 and the temperature controller are connected, and temperature control water is supplied to the flow channel 55.

The front end surface of the sprue bush 24 (the left end surface in FIGS. 1 and 5) is the disk plate 2
5 is formed by slightly retracting (moving to the right in FIGS. 1 and 5) from the front end face of the die 5, and the die 28 is formed by the inner peripheral edge of the second through hole 33 and the front end face of the disc plate 25.
Is formed. In this case, the amount by which the front end of the sprue bush 24 is retracted from the front end surface of the disc plate 25, that is, the depth of the die 28 can be changed as necessary.

Therefore, the bottom surface S11 of the large diameter portion 37 is
And the front end surface of the flange portion 31 between the annular spacer 3
8 is provided, and by changing the annular spacer 38 to have a different thickness, the position of the front end face of the sprue bush 24 can be changed and the depth of the die 28 can be changed.

Further, the movable mold is arranged so as to be movable back and forth in a state of being attached to the movable platen, and the mold clamping device is operated to move the movable platen forward and backward, thereby closing the mold, closing the mold, and closing the mold. Mold opening can be performed. Similar to the fixed mold 12, the movable mold includes a mounting plate, a base plate, a disc plate, a guide ring, and the like, and further includes a cut punch having a shape corresponding to the die 28.

A recess is formed on the surface of the disk plate of the movable mold facing the disk plate 25, and a cavity space is formed by the recess as the mold is clamped.

In the mold apparatus, the mold is closed, the movable mold is moved forward, and the movable mold is fixed.
Then, the mold is clamped and the movable mold is pressed against the fixed mold 12, and a cavity space is formed between the disk plate and the disk plate 25 of the movable mold. Next, in the injection step, the injection device 61 is moved forward (moved to the left in FIGS. 1 and 5), the front end of the injection nozzle 62 is pressed against the fixed mold 12, and the resin melted from the injection nozzle 62. Is ejected. The resin passes through the sprue 26 and is filled in the cavity space.

Subsequently, the resin in the cavity space is cooled and solidified to form a prototype of the disk substrate, that is,
A master substrate is formed, but before the resin is completely solidified, the cut punch is advanced to enter into the die 28, so that the master substrate is perforated, and the disc substrate is processed. It is formed. Then, the movable mold is retracted to open the mold, and the disk substrate is taken out as a molded product.

By the way, a concave portion 3 for accommodating the front end of the injection nozzle 62 is formed in the rear end surface of the flange portion 31.
0 is formed. Then, in the recess 30, between the locate ring 23 and the sprue bush 24, in contact with the locate ring 23 and the sprue bush 24, a plate-shaped yarn pulling prevention plate 34 as a yarn pulling prevention member is disposed. The stringing prevention plate 34 is made of a material having a higher thermal conductivity than the locate ring 23, the sprue bush 24, and the injection nozzle 62.
0, and a protruding portion 41 formed by projecting forward, and extending from the rear end of the protruding portion 41 outward in the circumferential direction and having a predetermined thickness. The protrusion 41 has a rising portion 43 rising from the flange portion 42, and the rising portion 4 having an annular flange portion 42.
3 is formed at the front end (the left end in FIG. 3) and is composed of a hemispherical curved portion 44. In the present embodiment, the sprue bush 24 is made of stainless steel, has a thermal conductivity of 22.68 [kcal / ° C · m · h], and the stringing prevention plate 34 is made of copper or aluminum. In the case of copper, the conductivity is 324.8 [kcal / ° C · m ·
h], and in the case of aluminum, 210.6 [kca
1 / ° C · m · h]. Then, a resin flow port 47 through which the resin flows is formed in the curved portion 44. The stringing prevention plate 34 has a shape corresponding to the front end of the injection nozzle 62, and the curvature of the inside of the curved portion 44 and the curvature of the front end of the injection nozzle 62 are made equal.

In this case, the locate ring 23 presses the flange portion 42 against the sprue bush 24 as it is attached to the base plate 18 by the bolt b24, and functions as a holding member for preventing the sprue bush 24 from dropping.

Therefore, when the thread-pulling prevention plate 34 is set on the sprue bush 24 with the projection 41 accommodated in the recess 30, and then the locate ring 23 is attached to the base plate 18 by the bolt b24, the flange portion 42 is located. The stringing prevention plate 34 is securely held in the fixed mold 12 in a state of being sandwiched by the 23 and the sprue bush 24.

Then, in the injection step, the injection nozzle 6
The heat of the injection nozzle 62 and the resin in the injection nozzle 62 is transferred to the stringing prevention plate 34 as the 2 is pressed against the fixed mold 12, and is transferred to the entire stringing prevention plate 34 very quickly. From the string pull prevention plate 34, it is further transmitted to the locate ring 23 and the sprue bush 24. Therefore, regardless of the molding temperature, the transfer of heat from the injection nozzle 62 to the locate ring 23 and the sprue bush 24 is promoted, and the injection nozzle 6
Since only the temperature of the front end of 2 becomes low, the viscosity of the resin in the cut portion S1 (see FIG. 2) formed in the injection nozzle 62 can be increased. As a result, it is possible to sufficiently suppress the occurrence of stringing.

The thread-pulling prevention plate 34 has a shape corresponding to the front end of the injection nozzle 62, and the curvature of the inside of the curved portion 44 and the curvature of the front end of the injection nozzle 62 are made equal to each other. The peripheral surface and the outer peripheral surface of the front end of the injection nozzle 62 are in surface contact with each other, so that the heat transfer area between the injection nozzle 62 and the stringing prevention plate 34 can be increased. Further, since the protruding portion 41 is formed along the concave portion 30, the heat transfer area between the stringing prevention plate 34 and the sprue bush 24 can be increased, and the flange portion 42 further includes the locate ring 23 and the sprue. Bush 24
The heat transfer area between the stringing prevention plate 34 and the locate ring 23 and the sprue bush 24 can be increased because they are sandwiched between.

Therefore, the transfer of heat from the injection nozzle 62 to the sprue bush 24 and the locate ring 23 is further promoted, so that the occurrence of stringing can be further suppressed. In order to adjust the amount of heat transfer, the material of the stringing prevention plate 34 may be changed to change the thermal conductivity.

Moreover, since the sprue bush 24 and the stationary platen 10 are cooled by the temperature-controlled water flowing through the flow paths 45 and 55, the heat transferred to the sprue bush 24, the locate ring 23 and the mounting plate 17 are fixed. The heat transferred to the platen 10 can be sufficiently discharged to the outside of the system by temperature control water. Therefore, it is possible to further suppress the occurrence of stringing.

Even when a large stress is applied to the thread-pulling prevention plate 34 when the injection nozzle 62 is pressed against the fixed mold 12, the thread-pulling prevention plate 34 has a plate-like shape, so that it is sufficient. It is possible to secure sufficient strength, and it is possible to prevent the stringing prevention plate 34 from being damaged. Further, even if the stringing prevention plate 34 is sandwiched by the injection nozzle 62 and the fixed mold 12, the flange portion 42 has the sprue bush 24 and the locate ring 23.
Since it is sandwiched by, the attachment state of the stringing prevention plate 34 can be stabilized. Then, when the injection nozzle 62 is retracted, the stringing prevention plate 34 does not drop from the fixed mold 12. Therefore, the work for maintenance and management of the injection molding machine can be simplified.

Further, since a heat transfer route is formed for transferring the heat transferred from the injection nozzle 62 to the string pulling prevention plate 34 to the mounting plate 17 and the fixed platen 10 via the locate ring 23, the temperature of the sprue bush 24 is increased. It is possible to sufficiently suppress the occurrence of stringing regardless of the molding temperature.

Next, a method of attaching the stringing prevention plate 34 will be described. FIG. 6 is a first diagram showing a method of attaching the stringing prevention plate in the embodiment of the present invention, and FIG.
FIG. 7 is a second diagram showing a method of attaching the string pulling prevention plate in the embodiment of the present invention.

In this case, the bolts b11 (FIG. 1) and b12 are loosened and removed beforehand, and the fixed platen 1
The mounting plate 17 is removed from 0, and the fixed mold 12 is removed. Then, as shown in FIG. 6, the bolt b24
Is loosened and removed, the locate ring 23 is removed from the base plate 18, and the land pressure adjusting spacer 46 previously arranged between the locate ring 23 and the sprue bush 24 is taken out. The land pressure adjusting spacer 46 is for changing the depth of the die 28 together with the annular spacer 38, and when the annular spacer 38 having a predetermined thickness is set in the large diameter portion 37. , Is used to fill a gap formed between the locate ring 23 and the sprue bush 24, and has a predetermined thickness corresponding to the thickness of the annular spacer 38.

Subsequently, the protrusion 41 is housed in the recess 30, the threading prevention plate 34 is set, and the bolt b
Locating ring 23 by base plate 18
Attach to. The string pulling prevention plate 34 is selected to have a predetermined thickness corresponding to the thickness of the annular spacer 38. Finally, the fixed mold 12 is attached to the fixed platen 10 via the attachment plate 17 by the bolts b11 and b12.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention, and they are not excluded from the scope of the present invention.

[0051]

As described in detail above, according to the present invention, in the mold apparatus, the mold body, the sprue bush set in the sprue bush accommodating portion of the mold body, and the sprue bush. And a holding member that is disposed in contact with the thread-pulling prevention member and that prevents the thread-pulling prevention member from falling.

In this case, since the stringing prevention member is disposed in contact with the sprue bush, the heat of the injection nozzle and the resin in the injection nozzle is increased as the injection nozzle is pressed against the fixed mold in the injection process. Is transmitted to the stringing prevention member, is transmitted to the entire stringing prevention member very quickly, and is further transmitted from the stringing prevention member to the holding member and the sprue bush. Therefore, regardless of the molding temperature, the transfer of heat from the injection nozzle to the holding member and the sprue bush is promoted, and only the temperature at the front end of the injection nozzle is lowered, so that the resin in the cutting portion formed in the injection nozzle is reduced. The viscosity can be increased.

Further, since the holding member is arranged in contact with the stringing prevention member to prevent the stringing prevention member from dropping, the stringing prevention member drops from the mold device when the injection nozzle is retracted. Never. Therefore, the work for maintenance and management of the injection molding machine can be simplified. As a result, it is possible to sufficiently suppress the occurrence of stringing.

In another mold apparatus of the present invention, the stringing prevention member further has a shape corresponding to the front end of the injection nozzle.

In this case, since the stringing prevention member has a shape corresponding to the front end of the injection nozzle, the heat transfer area between the injection nozzle and the stringing prevention member can be increased.
Therefore, the movement of the sprue bush and the holding member from the injection nozzle is further promoted, so that the occurrence of stringing can be further suppressed.

In still another mold apparatus of the present invention, the stringing prevention member further includes a flange portion.

The flange portion is sandwiched by the holding member and the sprue bush.

In this case, since the flange portion of the stringing prevention member is sandwiched between the holding member and the sprue bush, the heat transfer area between the stringing prevention member and the holding member and the sprue bush can be increased. Therefore, the transfer of heat from the injection nozzle to the sprue bush and the holding member is further promoted, so that the occurrence of stringing can be further suppressed.

Further, since the heat transfer route for transferring the heat transferred from the injection nozzle to the stringing prevention member to the platen and the mounting plate via the holding member is formed, it does not depend on the temperature of the sprue bush, and It is possible to sufficiently suppress the occurrence of stringing regardless of the molding temperature.

In still another mold apparatus of the present invention, a channel for supplying a temperature control medium is further formed in the sprue bush.

In this case, since the flow path for supplying the temperature control medium is formed in the sprue bush, the heat transferred to the sprue bush can be discharged to the outside of the system by the temperature control medium. Therefore, it is possible to further suppress the occurrence of stringing.

In the injection molding machine of the present invention, a platen, a mold body attached to the platen via a mounting plate, a sprue bush set in a sprue bush accommodating portion of the mold body, and the sprue bushing. And a holding member that is disposed in contact with the stringing prevention member and the platen and that prevents the stringing prevention member from falling.

A flow path for supplying the temperature control medium is formed in the platen.

In this case, since the flow path for supplying the temperature control medium is formed in the platen, the heat transferred to the platen can be discharged to the outside of the system by the temperature control medium. Therefore, it is possible to further suppress the occurrence of stringing.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of a conventional injection molding machine.

FIG. 3 is a cross-sectional view of the string pulling prevention plate according to the embodiment of the present invention.

FIG. 4 is a front view of the stringing prevention plate according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an injection molding machine during an injection step in the embodiment of the present invention.

FIG. 6 is a first diagram showing a method of attaching the string pulling prevention plate according to the embodiment of the present invention.

FIG. 7 is a second diagram showing a method of attaching the string pulling prevention plate in the embodiment of the present invention.

[Explanation of symbols]

10 Fixed platen 12 Fixed mold 17 Mounting plate 18 base plate 23 Locate ring 24 sprue bush 25 disc plate 27 Guide ring 32, 33 First and second through holes 34 String pull prevention plate 42 Flange 45, 55 channels 62 injection nozzle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiichi Sato             1 731 Naganumahara-cho, Inage-ku, Chiba-shi, Chiba               Sumitomo Heavy Industries, Ltd. Chiba Works F-term (reference) 4F202 AJ12 AM32 AR06 CA11 CK01                       CL41 CN15 CN22

Claims (7)

[Claims] 1. A (a) mold body, (b) a sprue bush set in a sprue bush accommodating portion of the mold body, and (c) a stringing prevention member disposed in contact with the sprue bush. And (d) a holding member which is disposed in contact with the stringing prevention member and which prevents the stringing prevention member from falling. 2. The mold apparatus according to claim 1, wherein the stringing prevention member is made of a material having high thermal conductivity. 3. The mold apparatus according to claim 1, wherein the stringing prevention member has a shape corresponding to the front end of the injection nozzle. 4. The mold apparatus according to claim 1, wherein (a) the stringing prevention member includes a flange portion, and (b) the flange portion is sandwiched by the holding member and a sprue bush. 5. The mold apparatus according to claim 1, wherein a channel for supplying a temperature control medium is formed in the sprue bush. 6. (a) a platen, (b) a mold body attached to the platen via a mounting plate, (c) a sprue bush set in a sprue bush accommodating portion of the mold body, d) a stringing prevention member arranged in contact with the sprue bush, and (e) a holding member arranged in contact with the stringing prevention member and the platen to prevent the stringing prevention member from falling. Along with
(F) An injection molding machine characterized in that a flow path for supplying a temperature control medium is formed in the platen. 7. The injection molding machine according to claim 6, wherein the stringing prevention member is made of a material having high thermal conductivity.