JPH0577285A - Injection mold - Google Patents

Abstract

PURPOSE:To provide a mold for injection molding wherein temperatures of molten resin flowing through a resin passage in a valve body can be maintained uniformly at a predetermined value and also thermal efficiency is very excellent. CONSTITUTION:The forward end (gate) of a resin passage 6 provided in a valve body 3 is opened and closed by the reciprocating movement of a valve pin 4 and the passage 6 is heated efficiently by a heater included in the valve body 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called valve gate type injection molding die provided with a valve pin (movable rod) for opening and closing a gate.

[0002]

2. Description of the Related Art Conventionally, as this type of injection molding die,
A cavity is formed between the fixed mold plate and the movable mold plate, a bush having a resin passage communicating with the cavity through a gate is provided in the fixed mold plate, and a heater is provided on the outer periphery of the tip of the bush. It is known that the movable rod is mounted in the resin passage so as to be movable in the axial direction, and the tip of the movable rod opens and closes the gate.

[0003]

By the way, in the injection molding die configured as described above, since the movable rod reciprocates in the resin passage inside the bush, the heater is mounted on the outer circumference of the bush. Must be installed (external heating method). Therefore, there is a problem that the heat of the heater easily escapes to the outside, the molten resin in the bush cannot be efficiently heated, and it is difficult to uniformly heat the entire bush, and the temperature distribution tends to vary. is there.

The present invention has been made in view of the above circumstances, and an object thereof is to maintain the temperature of the molten resin flowing through the resin passage in the valve body at a uniform and predetermined value. And to provide an injection mold having extremely good temperature efficiency.

[0005]

In order to achieve the above object, the present invention provides a cavity between a pair of mold plates,
A valve body is provided in one template, and a valve pin that penetrates the valve body and opens and closes a gate is provided in the valve body so as to be movable in the axial direction thereof.
A resin passage communicating with the valve pin mounting hole at the gate portion while avoiding the valve pin mounting hole of the valve body is provided in the valve body, while a heater is built in the valve body.

[0006]

In the injection molding die of the present invention, the tip end (gate portion) of the resin passage provided in the valve body is opened and closed by the reciprocating movement of the valve pin, and the heater built in the valve body is used. , Efficiently heat the resin passage.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

In these drawings, reference numeral 1 is a fixed mold plate, and a movable mold plate (not shown) is provided so as to be close to and away from the fixed mold plate 1, and between these mold plates. Has a cavity 2 in the shape of a molded product. Although not shown in the fixed template 1,
A fixed mounting plate is attached via the first and second fixed receiving plates and a spacer block, and a manifold is installed between the second fixed receiving plate and the fixed mounting plate. A valve body 3 is mounted inside the second and first fixed receiving plates and the fixed mold plate 1, and a valve pin 4 which is movable in the axial direction is mounted at the center of the valve body 3. The pin mounting hole 5 is formed. And the valve body 3
A straight portion 6a of a resin passage 6 parallel to the pin mounting hole 5 is formed inside the pin mounting hole 5 while avoiding the pin mounting hole 5.
At the tip of the straight portion 6a, there is formed an inclined portion 6b which is inclined and communicates with the straight portion 6a.
Furthermore, one end of the inclined portion 6b is communicated with the pin mounting hole 5, and the other end of the inclined portion 6b is opened to the outer periphery of the valve body 3. The opening of the inclined portion 6b to the outside is closed by a tubular member 7 attached to the valve body 3 by shrinkage fitting.

A temperature sensor 8 is mounted at a position point-symmetrical to the straight portion 6a of the resin passage 6 about the axis of the valve body 3 and the resin passage 6 is provided.
A pair of cartridge heaters 9 is mounted at a position orthogonal to the plane connecting the straight lines 6a and the axis of the temperature sensor 8. Further, the fixed mold plate 1 facing the tip of the valve body 3 has a funnel-shaped gate bush 1
No. 0 is mounted, and molten resin is supplied to the cavity 2 through the inside of the manifold, the resin passage 6 inside the valve body 3, and the inside of the gate bush 10.

In the injection molding die constructed as described above, by moving the valve pin 4 mounted in the pin mounting hole 5 of the valve body 3 along its axis,
The gate pin (inside the tip of the gate bush 10) is opened and closed by the tip of the valve pin 4.

In this case, the molten resin in the resin passage 6 of the valve body 3 is heated by the pair of cartridge heaters 9 built in the valve body 3, and by the temperature sensor 8 also mounted in the valve body 3. The temperature is detected, and the temperature of each cartridge heater 9 is controlled based on the detected temperature. Therefore, the temperature of the molten resin supplied into the cavity 2 via the gate bush 10 can be always kept constant, and variations between products can be prevented when a large number of products are taken at once or when products are repeatedly molded. , Good quality products are obtained.

[0012]

As described above, according to the present invention, a cavity is formed between a pair of mold plates, a valve body is provided in one mold plate, and the valve body is penetrated through the valve body. A valve pin for opening and closing the gate is provided so as to be movable in the axial direction thereof, and a resin passage communicating with the valve pin mounting hole at the gate portion is provided in the valve body while avoiding the valve pin mounting hole of the valve body. Since the heater is built in the valve body, the tip end (gate portion) of the resin passage provided in the valve body is opened and closed by the reciprocating movement of the valve pin, and the heater built in the valve body is used. ,
By efficiently heating the resin passage, the temperature of the molten resin flowing through the resin passage in the valve body can be uniformly maintained at a predetermined value, and a product with good quality can be obtained.

[Brief description of drawings]

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

2 is a cross-sectional view of FIG.

[Explanation of symbols]

 1 Fixed mold plate 2 Cavity 3 Valve body 4 Valve pin 5 Pin mounting hole 6 Resin passage 9 Cartridge heater 10 Gate bush

Claims (1)

[Claims] 1. A cavity is formed between a pair of mold plates,
A valve body is provided in one template, and a valve pin that penetrates the valve body and opens and closes a gate is provided in the valve body so as to be movable in the axial direction thereof.
An injection molding die characterized in that a resin passage communicating with the valve pin mounting hole at the gate portion is provided inside the valve body while avoiding the valve pin mounting hole of the valve body, while a heater is built in the valve body. Type.