JP3166465B2 - Valve gate type mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gate type mold used for injection molding of a resin.

[0002]

2. Description of the Related Art As is well known, a hot runner mold used for injection molding of a thermoplastic resin always maintains a molten state of a resin from a sprue and a runner to a gate in order to increase molding efficiency. It is configured. Also,
The mold is provided with a gate opening / closing mechanism for opening the gate when filling the cavity with the resin and closing the gate after filling to solidify the resin in the cavity. In this case, the gate opening and closing method
A valve gate system in which a gate is mechanically opened and closed by a valve is known.

An example of a conventional valve gate type mold will be described with reference to FIGS. In the figure, a fixed mold member 1 and a movable mold member 2 are vertically movable with each other and can be joined and separated from each other, and are joined at the time of mold clamping so that a cavity 3 is formed therebetween. Has become. The fixed mold member 1 includes a cavity member 4 forming a cavity 3, and the cavity member 4 includes receiving plates 5, 6,
The fixed-side mounting plate 8 is mounted on the fixed-side mounting plate 8 via the spacer block 7, and is mounted on the fixed-side platen of the injection molding machine. The movable mold member 2 is mounted on a movable mounting plate (both not shown) via a receiving plate and a spacer block, and the movable mounting plate is mounted on a movable platen of an injection molding machine.

[0004] A manifold 10 having a heater 9 is disposed between the receiving plate 6, the spacer block 7, and the fixed-side mounting plate 8.
Is buried and fixed. A runner 12 is formed in the manifold 10, and the runner 12 communicates with a spool 13 of a spool bush 11. A nozzle (not shown) of the main body of the injection molding machine is connected to the spool bush 11. A gate bush 14 is embedded and fixed in the cavity member 4, and a gate 15 that opens into the cavity 3 is formed in the gate bush 14. A cooling passage 17 communicating with a cooling passage 16 formed in the cavity member 4 is formed on the upper outer peripheral surface of the gate bush 14, and O-rings 18 and 19 are provided above and below the passages 16 and 17, respectively. . A valve casing 21 provided with a heater 20 on the outer peripheral portion is provided in the receiving plates 5 and 6 and the gate bush 14.
The upper end of the valve casing 21 has a manifold 1
A resin passage 22 communicating with the 0 runner 12 is formed. A guide bush 23 is provided at an upper end of the valve casing 21 and a valve pin holder 2 is provided at a lower end thereof.
4 are fitted and fixed on the same axis, and a gate 1 is provided in the guide bush 23 and the valve pin holder 24.
A valve pin 25 for opening and closing 5 is slidably held.

[0005] In this case, the guide bush 23 is an integrally formed iron product comprising a flange portion 26 and a cylindrical portion 27, and a space in the valve casing 21 with the valve pin 25 held in the cylindrical portion 27. It is fitted and fixed in the space 28 so as to close the upper part of the space 28. The upper end of the valve pin 25 is driven to move in the vertical direction by a cylinder 30 fixed to the fixed-side mounting plate 8 through a through hole 29 formed in the manifold 10.

In order to perform molding using the above-mentioned mold, the fixed mold member 1 and the movable mold member 2 are clamped. And
With the gate 15 open, the resin is injected from the nozzle of the injection molding machine. The injected resin is the spool bush 11
Runner 1 in manifold 10 from spool 13 in
2, and a resin passage 2 communicating with the runner 12.
2, the space 28 in the valve casing 21 is filled into the cavity 3, and is further injected into the cavity 3 through the gate 15. Next, the gate 15 is closed by lowering the valve pin 25 and fitting the tip to the gate 15. Then, after the resin in the cavity 3 has solidified,
Opening the fixed mold member 1 and the movable mold member 2,
Take out the resin molding. A series of molding operations are repeated to produce a molded body.
The resin in the runner 12 is heated by the heater 9 and the resin filled in the space 28 in the valve casing 21 is heated by the heater 20 provided on the outer peripheral portion, and is always in a molten state.

[0007]

In the above-described bubble gate mold, since the resin in the valve casing 21 is always kept in a molten state by the heater 20, gasification from the molten resin is performed. Large amount of resin
The gaseous resin accumulates in the through hole 29 of the manifold 10 through a slight gap between the guide bush 23 and the valve pin 25 in the valve casing 21. Further, the gaseous resin 31 remaining in the through hole 29 is carbonized during the repetition of the molding, and adheres to the peripheral surface of the valve pin 25. Therefore, in this mold, when the valve pin 25 is moved up and down to open and close the gate 15 when the mold is operated for a long period of time, the valve pin 25 is caught by the guide bush 23, and the movement of the valve pin 25 is reduced. become worse. Further, the gaseous resin adheres to the lead wires of the heaters 9 and 20 and the lead wire of a temperature sensor (not shown) that detects the temperature of the resin in the manifold 10 and the valve casing 21, resulting in poor insulation. Alternatively, there is a problem that a disconnection or the like is caused.

The present invention is intended to solve the above problems, and efficiently absorbs gasified resin generated from a molten resin to prevent leakage of the resin, thereby preventing malfunction of a valve pin. An object of the present invention is to provide a valve gate type mold that prevents insulation failure or disconnection of a lead wire of a heater or a temperature sensor.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the valve gate type mold, and has a plurality of fixed side mold members which are formed inside the cavity at the time of mold clamping and which can move relative to each other. A mold member, a valve casing portion provided facing a gate opening in the cavity formed by the mold member, and a gate disposed by moving in the axial direction disposed in the valve casing portion. A valve pin that opens and closes, the guide bush that is fitted at a position separated from the gate side end in the valve casing, and holds the valve pin movably in the direction inside the valve pin, and through the gate and the inside of the valve casing. A manifold for supplying the molten resin into the cavity, and heating for heating the molten resin in the valve casing portion With the door, the guide bush,
It is formed of a breathable steel material that absorbs gas generated from the molten resin.

[0010]

In the valve gate type mold of the present invention, the resin in the runner of the manifold is always kept in a molten state by heating the heater, and the resin in the valve casing is also always melted by the heating of the heater on the outer periphery of the valve casing. It is kept in condition. Here, gasified resin is generated from the molten resin, and the gasified resin is absorbed in the guide bush.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a valve gate type mold according to the present invention will be described below with reference to FIG. In this embodiment, the structure is the same as that of the conventional valve gate type mold shown in FIGS. 2 and 3, but the point is that a gas permeable metal is used for the guide bush 23 </ b> A holding the guide pin 25. Different from type. 2 and 3 for the mold of FIG.
The same reference numerals are given to the same components as those shown in FIG.

[Table 1]

The gas-permeable metal forming the guide bush 23A has a fine communication hole as a whole and can absorb gas. The guide bush 23A made of a breathable metal in this case is manufactured by molding metal fibers or metal powder and a binder into a shape having a flange portion 26A and a cylindrical portion 27A, and firing this. As a specific example of the breathable metal, there is Pocerax II manufactured by Shinto Kogyo Co., Ltd. This Porcelax II
Means PM40, PM35, PM30, PM2
0, and its main characteristics are as shown in Table 1.

The guide bush 23A made of a breathable metal manufactured as described above is used for the mold shown in FIG. In the mold, the resin filled in the space 28 in the valve casing 21 is always kept in a molten state by the heater 20, so that a part of the resin is gasified.
The gasified resin tends to flow out through the gap between the valve casing 21 and each member at the periphery thereof due to the pressure. However, the valve casing 2
Since the guide bush 23A, which is arranged in the inside 1 and supports the guide pin 25, is formed of a gas-permeable metal, it absorbs the gasified resin. That is, the gasified resin penetrates into the fine holes of the guide bush 23A, and adheres to the peripheral surface of the fine holes as it proceeds to the inner part of the fine holes.

Therefore, according to the above-mentioned mold, since the gas component generated from the resin in the valve casing 21 does not enter the through hole 29 above the guide bush 23A, the guide pin 25 carbonizes the gas component. The guide pin 25 can always smoothly move up and down in the guide bush 23A without any adhered matter, and the malfunction of the guide pin 25 can be prevented. In addition, the gaseous resin does not adhere to the lead wires of the heaters 9 and 20 and the lead wires of a temperature sensor that detects the temperature of the resin in the manifold 10 and the valve casing 21. Alternatively, disconnection or the like can be prevented.

In the above configuration, if the guide bush 23A is removably mounted on the valve casing 21, the guide bush 23A will be replaced with a new one when the operation time of the mold reaches a certain value. Can be exchanged.

[0016]

According to the valve gate type mold of the present invention, the gasified resin generated in the valve casing is adsorbed by the guide bush before adhering to the guide pin. It is possible to prevent the operation failure of the guide pin and to prevent the heater and the temperature sensor from adhering to the lead wires, thereby preventing insulation failure or disconnection.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view of a conventional valve gate type mold.

FIG. 3 is an enlarged sectional view of a main part of the mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed mold member 3 Cavity 10 Manifold 15 Gate 20 Heater 21 Valve casing 23A Guide bush 25 Guide pin

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/26-45/44 B29C 33/00-33/76

Claims (1)

(57) [Claims] 1. A plurality of mold members including a fixed mold member movable relative to each other and having a cavity formed therein at the time of mold clamping, and a gate opening into the cavity at the fixed mold member. A valve casing portion provided with
A valve pin that is arranged in the valve casing and opens and closes the gate by moving in the axial direction is fitted into the valve casing at a position separated from the gate-side end, and the valve pin is inserted in the valve casing in the direction. A guide bush that is movably held, a manifold that supplies the molten resin into the cavity through the valve casing and the gate, and a heating unit that heats the molten resin in the valve casing; A valve gate type mold, wherein the shroud is formed of a gas-permeable metal having fine communication holes for absorbing gas generated from the molten resin.