JPH10202697A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform molding without coagulating a resin in a gate part even in a hot runner system. SOLUTION: In an injection mold 1 wherein a cavity 4 corresponding to the shape of a molded product to be molded is formed between a movable mold 2 and a fixed mold 3 and a hot runner 32 having the gate part 5 coming into contact with the cavity 4 and the resin passage 6 communicating with the gate part 5 is provided to the fixed mold 3, a laminar heat absorbing and radiating element 8 having a heat absorbing surface 81 and a heat radiating surface 82 is arranged between the outer periphery of the gate part 5 and a fixed mold main body 31 so that the heat absorbing surface 81 forms a part of the cavity 4 and the heat radiating surface 82 is turned toward the outer periphery of the gate part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a mold for injection molding.

[0002]

2. Description of the Related Art Conventionally, a hot runner system has been known as a runnerless type mold for injection molding. In this method, the runner is heated with a cartridge heater or the like to keep the heat of the runner, and the heat is not conducted to the mold.
This is to prevent the nozzle from clogging.

According to this method, when molding a resin having inferior heat resistance such as a vinyl chloride resin, especially when there is no means for forcibly cutting the gate such as an open gate, the gate diameter is reduced. As the size increases, the resin solidifies in the gate portion or the occurrence of the so-called "honey-drop phenomenon" increases depending on the molding conditions. In this case, in order to reduce these defects, it is necessary to sufficiently insulate the runner plate and the mold body.

As one means for achieving this, although not of the hot runner type, there is an injection blow mold in which a Peltier element is arranged such that the heating surface faces the nozzle of the injection molding machine and the cooling surface faces the mold cavity. It has been proposed (JP-A-57-24220). This method can be diverted to a hot runner method, but in this case, as shown in FIG. 7, since the distance from the heat dissipation surface of the Peltier element a to the cavity b is long, the joining of the cavity a and the gate c is performed. The problem that not only the part but also the runner d is cooled and solidified and solidified at the gate part c still remains.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and the injection molding die which can be efficiently molded without solidifying the resin at the gate even in the hot runner system. Is to provide.

[0006]

According to a first aspect of the present invention, there is provided an injection mold having a cavity corresponding to a shape of a molded product to be molded between a movable mold and a fixed mold. Is fixed to the outer periphery of the gate portion of the injection molding mold provided with a hot runner having a gate portion in contact with the cavity and a resin flow path communicating with the gate portion in the fixed mold. A layered heat-absorbing and radiating element having a heat-absorbing surface and a heat-dissipating surface is disposed between the side mold body and the heat-absorbing surface on the cavity side, and the heat-dissipating surface faces the outer peripheral side of the gate portion. .

[0007] The layered heat absorbing and dissipating element having a heat absorbing surface and a heat dissipating surface has an electronic heat pump based on the Peltier effect in which heat is absorbed when a current flows through a junction of a plurality of dissimilar metals. Refers to a layered device. For example, as disclosed in JP-A-57-24220, a positive electrode
With the configuration of n-type semiconductor-intermediate electrode-p-type semiconductor─negative electrode, a heat pump having both the positive and negative electrodes as a heat source and the intermediate electrode as a heat absorbing source can be obtained. A heat source and a heat absorbing source of this heat pump are each formed as a layered body, and a member provided with a bonding material can be used as a layered heat absorbing and radiating element having a heat absorbing surface and a heat radiating surface.

According to a second aspect of the present invention, a heat insulating member is provided between the heat radiation surface of the layered heat absorbing and radiating element of the injection mold of the present invention and the gate. It is characterized by the following.

The heat insulating member is not particularly limited, but is preferably a resin having a thermal conductivity of 10 W / m · K or less and a thermal deformation temperature of 200 ° C. or more. For example, polyimide, polyphenylene sulfide, polyether, And polyether ether ketone.

According to the third aspect of the present invention, a cavity corresponding to the shape of a molded product to be molded is formed between the movable mold and the fixed mold.
The fixed mold has a gate portion in contact with the cavity and a hot runner having a resin flow path communicating with the gate portion. In between, the layered heat absorbing and radiating element having a heat absorbing surface and a heat radiating surface is arranged so that the heat absorbing surface faces the cavity via the good heat transfer member and the heat radiating surface faces the gate portion side. I do.

The good heat transfer member is not particularly limited, and examples thereof include copper alloys such as beryllium copper.

(Operation) In the injection mold of the present invention 1, a cavity corresponding to the shape of a molded product to be molded is formed between the movable mold and the fixed mold, and the fixed mold is formed. The mold is provided with a hot runner having a gate portion in contact with the cavity and a resin flow path communicating with the gate portion of the injection molding die, between the outer periphery of the gate portion and the fixed-side die body, Since the layered heat absorbing and radiating element having the heat absorbing surface and the heat radiating surface is arranged so that the heat absorbing surface forms a part of the cavity and the heat radiating surface is directed to the outer peripheral side of the gate part, Since only the cavity can be cooled without cooling or heating the resin passage and the gate portion of the runner, the resin can be efficiently molded without solidifying the resin at the gate portion.

The injection mold of the second aspect of the present invention has a heat insulating member provided between the heat radiation surface of the layered heat radiation element and the gate of the injection mold of the first aspect of the present invention. Even if the heat radiation surface cannot be directly in contact with the outer periphery of the gate, only the cavity can be cooled without cooling or heating the resin flow path and the gate of the hot runner, so that the resin solidifies at the gate. The molding can be performed efficiently without performing.

According to the injection molding die of the third aspect, a cavity corresponding to the shape of a molded product to be molded is formed between the movable die and the fixed die, and the fixed die is formed in the fixed die. A heat absorbing surface is provided between the outer periphery of the gate portion and the fixed mold body of the injection mold provided with a hot runner having a gate portion abutting on the cavity and a resin flow path communicating with the gate portion. The layered heat absorbing and radiating element having the heat radiating surface is arranged so that the heat absorbing surface faces the cavity through the good heat transfer member therebetween, and the heat radiating surface faces the gate portion side. Even in a structure where a part of the cavity cannot be formed directly, only the cavity can be cooled without cooling or heating the resin flow path and the gate of the hot runner, so that the resin solidifies at the gate. Don't do it , It can be molded efficiently.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the injection mold of the present invention 1 and the present invention 2, and FIG.
Is a sectional view taken along the line A-A.

The injection mold 1 comprises a movable mold plate 2 and a fixed mold plate 3 and corresponds to the shape of a molded product to be molded between the movable mold plate 2 and the fixed mold plate 3. A cavity 4 is formed. The fixed mold 3 is provided with a hot runner 32 having a gate portion 5 in contact with the cavity 4 and a resin flow path 6 communicating with the gate portion 5, and a heater 7 on the outer periphery of the hot runner 32. A heat absorbing surface 8 is provided between the outer periphery of the gate portion 5 and the fixed mold body 31.
The layered heat absorbing and dissipating element 8 having the heat absorbing surface 1 and the heat dissipating surface 82 is disposed so that the heat absorbing surface 81 forms a part of the cavity 4 and the heat dissipating surface 82 faces the outer peripheral side of the gate portion 5.

A gap layer 33 is provided between the fixed mold body 31 and the hot runner 32, and a heat insulating layer made of a polyamide resin is provided between the heat radiating surface 82 of the layered heat absorbing and radiating element 8 and the hot runner 32. Material 9 is provided. The nozzle 10 of the injection molding machine is in contact with the hot runner 32, and the resin can be injected into the cavity 4 through the resin flow path 6 and the gate 5 of the hot runner 32.

In order to obtain a molded product using the injection mold 1, first, a resin (for example, vinyl chloride resin) is injected from the injection molding machine 10 into the resin flow path 6 of the hot runner 32 and the gate 5.
And is injected into the cavity 4. Next, a predetermined voltage (for example, 15 volts) is applied between the terminals (not shown) of the layered heat absorbing and dissipating element 8.
A molded product can be obtained by maintaining the pressure at a predetermined pressure while applying V) and solidifying by cooling. A voltage may be continuously applied to the layered heat absorbing and dissipating element 8 according to the molding conditions,
The load may be applied only during the dwell.

Further, the heat insulating material 9 is not necessarily provided when there is a low possibility that the gate portion 5 is solidified according to the type of the resin.

FIG. 3 is a cross-sectional view showing another example of the injection mold of the present invention 1 and the present invention 2. Fixed mold body 1
31 is the same as FIG. 1 except that a blower 20 is provided.

When an injection-molded product is obtained by using the present mold, the fan (not shown) of the blower 20 is rotated to positively discharge the heat of the air gap layer 133 to the outside of the system. The heat from the heat radiation surface 182 is also released outside the system. In addition,
The hot runner 132 is heated by the heater 17 and is kept warm by the heat insulating material 19 to prevent a temperature drop.

FIG. 4 is a sectional view showing still another example of the injection mold of the present invention 1 and the present invention 2. It is the same as FIG. 1 except that two layered heat absorbing and dissipating elements 28 and 28 ′ are stacked. Thereby, the heat absorbing ability can be improved as compared with the case where a single heat absorbing and radiating element is used.

FIG. 5 is a sectional view showing an example of the injection mold of the present invention 3, and FIG. 6 is a sectional view taken along line AA of FIG.

The injection molding die 41 comprises a movable mold plate 42 and a fixed mold plate 43, and corresponds to the shape of a molded product to be molded between the movable mold plate 42 and the fixed mold plate 43. A cavity 44 is formed. The fixed mold 43 is provided with a gate portion 45 in contact with the cavity 44 and a hot runner 432 having a resin flow path 46 communicating with the gate portion 45.
7 are provided. A heat absorbing surface 481 and a heat radiating surface 482 are provided between the outer periphery of the gate 45 and the fixed mold body 431.
Are arranged so that the heat absorption surface 481 faces the cavity 44 via the good heat transfer member 40 made of beryllium copper, and the heat radiation surface 482 faces the gate portion 45 side. .

The method of obtaining a molded product by using the injection mold 41 of the present invention 3 is the same as that of the first and third embodiments, but by adopting such a structure, the gate portion far from the heater 47 is formed. 45 is heated by a heat radiation surface 482 to prevent a temperature drop.

[0026]

According to the injection molding die of the present invention 1 having the above-described structure, the resin can be efficiently molded without solidifying the resin at the gate portion. Since the injection mold according to the second aspect of the invention has the above-described structure, even if the heat radiation surface cannot be directly in contact with the outer periphery of the gate, the resin does not solidify at the gate portion, and the injection molding is efficiently performed. Can be molded. Since the injection mold of the third aspect has the above-described structure, the cavity can be cooled even if the heat-absorbing surface cannot directly form a part of the cavity, and the gate portion can be cooled. Thus, the resin can be efficiently molded without solidifying.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an injection mold according to the present invention 1 or 2.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view showing another example of the injection mold of the present invention 1 or 2.

FIG. 4 is a cross-sectional view showing still another example of the injection mold of the present invention 1 or 2.

FIG. 5 is a cross-sectional view showing one example of an injection mold according to the third embodiment of the present invention.

6 is a sectional view taken along line AA of FIG.

FIG. 7 is a cross-sectional view showing an example of a conventional injection mold.

[Explanation of symbols]

 1, 11, 41 Injection mold 2, 42 Movable mold 3, 43 Fixed mold 31, 131, 431 Fixed mold body 32, 132, 432 Hot runner 4, 44 Cavity 5, 45 Gate 6 , 46 Resin flow path 8, 18, 28, 28 ', 48 Layered heat absorbing and dissipating element 81, 181, 481 Heat absorbing surface 82, 182, 482 Heat absorbing surface 9, 19 Insulation material 40 Good heat transfer member

Claims (3)

[Claims] 1. A cavity corresponding to the shape of a molded product to be molded is formed between a movable mold and a fixed mold, and a gate portion in contact with the cavity and the gate in the fixed mold. A layered heat-absorbing and radiating element having a heat-absorbing surface and a heat-dissipating surface is provided between the outer periphery of the gate portion and the fixed-side mold body of the injection mold provided with a hot runner having a resin flow path communicating with the portion. An injection mold, wherein the heat-absorbing surface is arranged so as to form a part of the cavity, and the heat-radiating surface is directed to the outer peripheral side of the gate portion. 2. An injection mold according to claim 1, wherein a heat insulating member is provided between the heat radiating surface of the layered heat absorbing and radiating element of the mold and the gate portion. 3. A cavity corresponding to the shape of a molded product to be molded is formed between the movable mold and the fixed mold, and the fixed mold has a gate portion in contact with the cavity and a gate thereof. A layered heat-absorbing and radiating element having a heat-absorbing surface and a heat-dissipating surface is provided between the outer periphery of the gate portion and the fixed-side mold body of the injection mold provided with a hot runner having a resin flow path communicating with the portion. An injection mold, wherein a heat absorbing surface is arranged to face a cavity via a good heat transfer member and a heat radiating surface is arranged to face a gate portion.