JPH07178778A - Mold - Google Patents

Abstract

PURPOSE:To provide a mold capable of eliminating the operational inferiority of the reciprocal motion of a valve pin and reducing the removing work of the discharged resin leaked to heat insulating space. CONSTITUTION:A bush 13 is provided between a manifold 12 and a valve nozzle 11 and a valve pin 14 is passed through the manifold 12 and the bush 13 to be extended into the valve nozzle 11. A heat source is provided to the valve pin 14 and the valve pin 14 is freely heated by the heat source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gate molding die having a mechanism for preventing malfunction of the valve pin caused by leakage and solidification of the molding material around the valve pin.

[0002]

2. Description of the Related Art In a multi-cavity valve gate type molding die, in order to prevent high temperature molten molding material leaking from the periphery of a reciprocating valve pin from entering the heat insulating space, A seal member is required between them. As such a sealing member, for example, Japanese Patent Laid-Open No.
As described in JP-A-3-107528, a seal and a supporting bush surround a valve pin between a manifold and a mold receiving plate, and each bushing penetrates a central hole.
As a result, a multi-cavity valve gate molding apparatus has been proposed which can almost completely prevent the pressurized molten molding material from leaking around the reciprocating valve pin.

[0003]

However, in the prior art as described above, since there is a delicate gap (about 10 to 20 μm) in the matching portion between the bushing hole and the valve pin, a molding material containing glass fiber is used. In particular, when a molding material having a high glass fiber content is used, the molding material is more likely to enter the gap, which eventually causes wear of the valve pin and the bushing, or the molding material enters the heat insulating space, where There is a problem that the reciprocating movement of the valve pin is hindered by the solidification of the resin.

Therefore, making the gap between the bush hole and the valve pin more severe increases the manufacturing cost and is technically difficult. In addition, in order to remove the solidified discharged resin that has entered the heat insulating space, the bush must be removed, which makes maintenance work difficult.

An object of the present invention is to solve the problems of the prior art in the mold for molding the valve gate type, to solve the malfunction of the reciprocating motion of the valve pin and to reduce the work of removing the discharged resin leaking into the heat insulating space. It was made.

[0006]

DISCLOSURE OF THE INVENTION In a molding die of the present inventions 1 to 3, a bush is mounted between a manifold and a valve nozzle, and a valve pin extends through the manifold and the bush into the valve nozzle. The structure as a gate mold is provided as a common component.

In addition to the above-mentioned structural requirements, the molding die of the first aspect of the present invention has a structure in which a heat source is provided on the valve pin, and the valve pin can be freely heated by the heat source. As a means for allowing the valve pin to be heated by a heat source, for example, a band heater may be attached to the outer circumference of the valve pin to heat it, or a cut ridge heater may be embedded in the valve pin to heat it. Then
Further, a heating heat medium heated by an external heat source may circulate in the valve pin.

The molding die according to the second aspect of the present invention has, in addition to the above-mentioned structural requirements, a structure in which the valve pin is made of a material having good heat conduction. When the valve pin is made of a material having a high thermal conductivity, for example, the valve pin may be made of a heat pipe, and the valve pin is a material having a high thermal conductivity, such as aluminum, copper or an alloy thereof. It may consist of

Further, in addition to the above-mentioned structural requirements, the molding die of the present invention 3 has a cylindrical portion of a bush inserted into a through hole provided in a manifold so as to be spaced from each other. A resin discharge bush is detachably inserted in a gap between the through hole of the manifold and the cylindrical portion of the bush, and the resin discharge bush has a small-diameter cylindrical portion that slides on the outer surface of the cylindrical portion of the bush. A large-diameter tubular portion is provided along the inner surface of the through hole of the manifold, and a resin reservoir portion is provided by connecting the proximal end sides of the tubular portions of the bush of the small-diameter tubular portion and the large-diameter tubular portion to each other. It has a different configuration.

The resin discharging bush is provided with a flange portion projecting outward on the outer peripheral surface of the end portion on the side opposite to the side where the resin reservoir portion of the large-diameter tubular portion is provided. Is preferably fixed to the end face of the peripheral wall of the through hole of the manifold.

[0011]

In the molding die of the present invention 1, since the valve pin is provided with a heat source so that it can be heated, the portion of the valve pin shaft portion in contact with the bush can be heated by the heat source. It is possible to prevent the solidification of the molten resin that enters or leaks between the bush and the bush, and does not cause poor forward / backward movement of the valve pin.

In the molding die of the second aspect of the present invention, since the valve pin is made of a material having good heat conduction, the portion of the shaft portion of the valve pin that comes into contact with the bush can be heated by the heat of the molten resin. It is possible to prevent the solidification of the molten resin that enters between the bushes and leaks from between the bushes, and to prevent the valve pin from moving backward and forward.

In the molding die according to the third aspect of the present invention, the tubular portions of the bush are inserted into the through holes provided in the manifold so that the tubular portions are spaced apart from each other. A resin discharging bush is detachably inserted in the gap between the bush and the resin discharging bush, and the resin discharging bush has a small-diameter cylindrical portion that slides on the outer surface of the cylindrical portion of the bush and a large diameter along the inner surface of the through hole of the manifold. Since the tubular portion of the small diameter and the tubular portion of the large diameter are connected to each other at the base end sides of the tubular portions of the bush, and the resin reservoir portion is provided, the shaft portion of the valve pin is provided. The molten resin that leaks from between the bush and the bush is discharged into the resin reservoir of the resin discharging bush, and during maintenance, the resin discharging bush can be pulled out and washed to easily remove the discharged resin. it can.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partially cutaway sectional view for explaining the entire structure commonly provided as a molding die for valve gate molds of the present invention 1 to 3.

The molding die 1 comprises a valve nozzle 11, a manifold 12, a bush 13 and a valve pin 14. The valve nozzle 11 has a base end mounted on the manifold 12 via a bush 13, and the other parts inserted into a cavity mold. A gate 111 for injecting a molten resin is opened at the tip of the valve nozzle 11, and the tip is exposed on the mold surface of the cavity mold.

A shaft portion 141 of the valve pin 14 extends through the manifold 12 and the bush 13 and extends into the valve nozzle 11. In the valve nozzle 11, a gap is formed between the shaft portion 141 of the valve pin 14 and the gap, which is communicated with the injection molding machine.
It is supposed to be 2.

A base end portion of the valve pin 14 is fixed to a mold receiving plate 16 via a hydraulic cylinder 15. Then, by operating the hydraulic cylinder 15, the shaft portion 141 of the valve pin 14 advances and retreats, and the valve portion 142 provided at the tip thereof can open and close the gate 111 of the valve nozzle 11 from the inside. There is.

When the shaft portion 141 of the valve pin 14 is retracted, the valve portion 142 can open the gate 111 of the valve nozzle 11 to inject the molten resin from the gate 111, and the shaft portion 141 of the valve pin 14 can be opened. When moved forward, the valve portion 142 can close the gate 111 of the valve nozzle 11.

The bush 13 is provided with a collar portion 132 at one end of a shaft portion 131. Collar portion 13 of bush 13
1 is sandwiched between the base end surface of the valve nozzle 11 and the side surface of the manifold 12 on the valve nozzle 11 side, and the shaft portion 13
1 is inserted in a through hole 121 provided in the manifold 12. A through hole 133 is provided in the bush 13 so as to penetrate the shaft portion 131 and the flange portion 132 along the axial direction, and the shaft portion 141 of the valve pin 14 is inserted into the through hole 133 so as to advance and retract. . The outer diameter of the shaft portion 131 is slightly smaller than the inner diameter of the through hole 121 of the manifold 12.

FIG. 2 is a front view for explaining a main part of an example of the molding die of the present invention 1. Shaft 14 of valve pin 14
A band heater 2 is wound around the outer periphery of the base end portion 1 of FIG. 1, and the shaft portion 141 of the valve pin 14 can be heated by the band heater 2.

FIG. 3 is a front view for explaining a main part of another example of the molding die of the present invention 1. Shaft 1 of valve pin 14
The base end portion of 41 is thickened, and a hollow portion 143 is provided in that portion. The cartridge heater 3 is inserted in the hollow portion 143.
Thus, the shaft portion 141 of the valve pin 14 can be heated.

Band heater 2 as shown in FIG. 2 and FIG.
In order to heat the shaft portion 141 of the valve pin 14 with a heat source such as the cartridge heater 3 as shown in FIG. 1, for example, a method of performing temperature control by voltage control outside the die is preferably adopted. As a result, the shaft portion 141 of the valve pin 14
Since a portion of the valve pin 14 that comes into contact with the bush 13 can be heated by a heat source, it is possible to prevent solidification of the molten resin that enters between the shaft portion 141 of the valve pin 14 and the bush 13 or leaks from between the bush portion 13 and to prevent the valve pin 14 from moving backward or forward. It does not cause.

FIG. 4 is a sectional view showing an example of the molding die of the second invention. In this molding die, the valve pin 14 'is composed of a heat pipe having good heat conduction. The shaft portion 141 ′ of the valve pin 14 ′ is made of an aluminum pipe, and glass fibers or net-like thin copper wire bundles are inserted into the shaft portion 141 ′, and a heat medium is packed therein, although not particularly shown.

The shaft portion 141 'of the valve pin 14' is
The heat conduction can be performed between the portion of the bush 13 'that contacts the resin flow path 112' and the portion of the bush 13 'that contacts the shaft portion 131'. That is, the valve pin 14 '
In the portion of the shaft portion 141 'that contacts the resin flow path 112', the heat medium packed in the shaft portion 141 'is vaporized and moves to the portion in contact with the bush 13 due to the pressure difference, Conducts heat. Further, the heat medium cooled in the portion in contact with the bush 13 is returned to the portion in contact with the resin flow path. By repeating this, the shaft portion 1 of the valve pin 14 'is
It is possible to quickly conduct heat from the portion of 41 'that contacts the resin flow passage 112' to the portion of the bush 13 'that contacts the shaft portion 131'.

As a result, the shaft portion 14 of the valve pin 14 'is
Since the portion of the bush 1'which is in contact with the shaft portion 131 'is heated, solidification of the molten resin that enters between the shaft portion 141' of the valve pin 14 'and the bush 13' or leaks from between is prevented. It is possible to prevent the valve pin 14 'from moving backward and forward.

FIG. 5 is a partial cross-sectional view for explaining an example of the molding die of the third invention. Through hole 1 in manifold 12
Shafts 131 of the bush 13 are inserted into the shaft 21 so as to be spaced apart from each other. The resin discharging bush 4 is detachably inserted into a gap between the through hole 121 of the manifold 12 and the shaft portion 131 of the bush 13.

The resin discharging bush 4 includes a bush 13
The small-diameter tubular portion 41 along the outer surface of the shaft portion 131 and the large-diameter tubular portion 42 along the inner surface of the through hole 121 of the manifold 12 are provided, and the bush of the small-diameter tubular portion 41 and the large-diameter tubular portion 42 is provided. The resin reservoir 43 is provided by connecting the base end sides (lower ends in FIG. 5) of the shaft portions 131 of 13 to each other. A flange portion 44 projecting outward is provided on the outer peripheral surface of the end portion (upper end portion in FIG. 5) of the large-diameter tubular portion 42 opposite to the side where the resin reservoir portion 43 is provided. . The flange portion 44 is provided with a bolt hole.

The resin discharging bush 4 has a flange portion 44.
Can be fixed to the end surface (upper end surface in FIG. 5) of the peripheral wall of the through hole 121 of the manifold 12 by inserting the bolt hole with the tightening bolt 5. As a result, the molten resin leaking from between the shaft portion 141 of the valve pin 14 and the bush 13 is discharged into the resin reservoir 43 of the resin discharging bush 4. Then, at the time of maintenance, a hydraulic cylinder and valve pin 1 (not shown)
After removing 4, the tightening bolt 5 is removed, the resin discharging bush 4 is removed, and the resin is washed, as shown in FIG. 6, whereby the discharged resin can be easily removed.

[0029]

EFFECTS OF THE INVENTION Since the molding die of the present invention 1 is constructed as described above, it is possible to prevent the solidification of the molten resin that enters or leaks between the shaft portion of the valve pin and the bush. It is possible to prevent the valve pin from moving backward and forward.

Since the molding die of the second aspect of the present invention is configured as described above, it is possible to prevent the solidification of the molten resin that enters between the shaft portion of the valve pin and the bush and leaks out from the bush. , It does not cause poor movement of the valve pin.

Since the molding die of the third aspect of the present invention is configured as described above, the molten resin leaking between the shaft portion of the valve pin and the bush is discharged into the resin reservoir portion of the resin discharging bush, At the time of maintenance, the resin discharging bush can be pulled out and washed to easily remove the discharged resin.

[0032]

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view for explaining an entire structure commonly provided as a molding die for a valve gate mold of a molding die of the present invention 1 to 3.

FIG. 2 is a front view showing a main part of an example of a molding die of the first invention.

FIG. 3 is a front view showing a main part of another example of the molding die of the first invention.

FIG. 4 is a cross-sectional view showing an example of a molding die of the second invention.

FIG. 5 is a partial cross-sectional view showing the main parts of an example of a molding die according to the present invention 3.

6 is a partial cross-sectional view showing a state where a resin discharging bush of the molding die shown in FIG. 5 is removed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold for molding 2 Band heater 3 Cartridge heater 4 Bush for resin discharge 11 Valve nozzle 12 Manifold 13 Bush 14,14 'Valve pin 141,141' Shaft part 142 Valve part

Claims (3)

[Claims] 1. A valve gate type molding die in which a bush is mounted between a manifold and a valve nozzle, and a valve pin extends through the manifold and the bush into the valve nozzle. The valve pin is provided with a heat source. The
A mold for molding, characterized in that the valve pin can be heated by the heat source. 2. A valve gate type molding die, wherein a bush is mounted between the manifold and the valve nozzle, and the valve pin extends through the manifold and the bush into the valve nozzle. Mold for molding characterized by being made of good material. 3. A valve gate type molding die in which a bush is mounted between a manifold and a valve nozzle, and a valve pin extends through a tubular portion provided in the manifold and the bush and extends into the valve nozzle. Then, the tubular parts of the bush are inserted into the through holes provided in the manifold with a space between them, and the resin discharge bush is attached and detached in the gap between the through hole of the manifold and the tubular part of the bush. The resin discharging bush is provided with a small-diameter cylindrical portion that slides on the outer surface of the cylindrical portion of the bush and a large-diameter cylindrical portion that extends along the inner surface of the through hole of the manifold. And a large-diameter tubular portion, the tubular portion of the bush of the tubular portion is connected to each other at the base end portions thereof to provide a resin reservoir portion.