JPS5919125A - Die for injection molding - Google Patents

Abstract

PURPOSE:To obtain the titled die wherein the gate section can be cut off from a resin article in the die thereby improving the operation efficiency of the injection molding, by providing a core die and a cavity die with cutting blocks for cutting the gate to work in cooperation with the cavity body. CONSTITUTION:After the injection and the hardening of the resin, a slide cam 19 is lowered by a hydraulic cylinder 18 and the cutting block 17 is retracted to the left. Then by the resilient force of a coil spring 16, the cutting block 15 is moved toward the cutting block 17 thereby cutting off the gate (G) with the resin article (W) pinched between the cutting blocks 15, 17. In this case, the runner R1 pinched between the cutting blocks 15, 17 and the runner R2 pinched between the core die body 2 and the cavity die body 1 are severed by the cooperation of the cutting blocks 15, 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-mold injection mold in which a gate is cut out from a resin product within the mold.

To injection mold resin products of various shapes, thermoplastic resin in a heated and molten state is injected and filled into the product molding part formed in an injection mold consisting of a cavity die body and a core die body. ing. In such an injection mold, a runner and a gate are provided between a spool that discharges heated and molten resin and a product molding section.

The runner is provided so that the molten resin flows smoothly with as little resistance as possible, and the runner serves as a runner that connects the spool and the gate.

A gate is located at the end of this runner, and serves as an entrance for resin to the product molding section.

The cross-sectional shape of the gate is usually circular, semicircular, rectangular, trapezoidal, etc. When the gate is provided on the side of the product molding part, it is called a side gate or edge gate.

In addition, a gate that is dug into the mold in a tunnel shape from the launch located on the parting surface of the mold, that is, the dividing surface between the cavity die body and the core die body, is called a tunnel gate or submarine gate. There is. Due to the nature of the structure of these gates, particularly tunnel gates, it is possible to cut out the gates at the same time during so-called mold opening to separate the cavity die body and the core die body from each other. However, when resin molding is performed using these gates, it is necessary to provide a plurality of gates because the cross-sectional area of one gate cannot be increased in order to mold one resin product. When molten resin is injected and filled into a product molding part in a mold through a plurality of gates, there is a possibility that weld marks or flow 7 - ri may occur in the resin product.

Weld marks, also called weld lines, are a phenomenon in which a thin line is generated where the tips of two fluid resins injected from different gates collide and fuse. This is a phenomenon that causes concentric luster or roughness around the area. When these phenomena occur, the appearance of the resin product becomes poor, and the preferred shape for the resin product is a film gate or a fan gate.

A film gate is also called a flash gate or a slit gate, and is a gate that has a thin gate thickness of about 0.2 to 1 mm and a long width along the longitudinal direction of the resin product. This is a perspective view showing a state in which a U-shaped resin product W is molded using film goo (R).
and gate G are integrated with the resin product. When injection molding is performed using Fan Gate O, resin can be injected and filled from one gate, so weld marks and 70-marks do not occur and products with a good surface finish are produced. However, there was a problem in that it was difficult to cut out the gate when opening the mold.

This was also the case when a thin fan-shaped gate was formed from the fan gate switching runner.

Therefore, in the past, the runner R and game) (
) is removed from the mold in a state where it is integrated with the resin product,
It is necessary to cut out the gate from the resin product using a press or manually, which poses a problem of poor work efficiency.

Particularly when molded using a resin material with high strength, it is extremely inefficient to cut it out manually.

In view of the problems of the prior art as described above, the present invention has been developed to solve the problem of the gate in the mold when using a gate with a thin wall thickness and a long width in the longitudinal direction of the product, such as a film gate or a fan gate. The purpose of this invention is to improve the working efficiency of injection molding by making it possible to cut out parts from resin products. To achieve this object, the present invention has a structure in which a product forming part is formed between a cavity die body and a core die body which is movable towards and away from the cavity die body, and the product is injected from a spool provided on the cavity die body. In the injection mold, the product molding part is filled with a molten resin, in which a thin and long gate is formed between the cavity die body and the core die body, and A cutting block that forms a runner connecting the spool and cuts the gate in cooperation with the cavity die body is attached to the core die body and the cavity die body in the approaching and separating direction.

Next, an embodiment of the present invention shown in FIGS. 2(a) to 6 will be described. FIGS. 2(a) and 2(b) are diagrams showing a preliminary mold for injection molding a resin product W having a U-shaped cross section as shown in FIG. 1, and the injection mold has a cavity on the fixed side. It has a die body 1 and a movable core die body 2, and when these are molded together as shown in FIGS. 2(a) and 2(b), a product molding part (cavity) 3 is formed.

The cavity die main body 1 is fixed to a mounting plate 5 via a spacer 4, and an injection molding machine main body (not shown) is mounted on the mounting plate 5.

Then, the core die body 2 is attached to the mounting plate 7 via the spacer 6.
A driving device (not shown) is attached to this mounting plate 7, and the core die body 2 can move toward and away from the cavity die body 1.

A runner block 1o is attached between a spool 8 provided on the mounting plate 5 and a nozzle bush 9 provided on the cavity die body 1, and a molten resin is discharged from the injection molding machine body (not shown) onto the spool 8. is discharged from a spool 11 provided at the tip of the nozzle bush 9 via the runner block 1o and the nozzle bush 9. A heater 12 is attached to the runner block 1o and the nozzle bush 9 to prevent the resin flowing therefrom from solidifying.

A first cutting block 1 is attached to the tip of a guide pin 14 that is slidably fitted into a hole 13 formed in the cavity die body 1.
5 is fixed, and this first cutting block 15 is movable toward the core die body 2. Also hole 13
A resilient force directed toward the core die body 2 is applied to the first cutting block 15 by a coil spring 16 housed therein.

A second cutting block 15 faces this first cutting block 15 and forms a runner R and a thin and long gate G therebetween.
A cutting block 17 is attached to the core die body 2 so as to be movable toward the cavity die body 1. A hydraulic cylinder 18 is attached to the spacer 6 as a driving means for driving the second cutting block 17 in the direction toward the cavity die body 1. A sliding cam 19 moving in the direction engages the second cutting block 17. The engagement between the second cutting block 17 and the slide cam 19 is achieved by forming a dovetail groove (not shown) in the second cutting block 17 and forming a protrusion (not shown) in the slide cam that fits into the dovetail groove.

An extrusion plate 21 is provided in a space 2o surrounded by the core die body 2, spacer 6, and mounting plate 7, and a return pin 22 and an extrusion pin 2 attached to this extrusion plate 21 are provided.
3 are slidably fitted into holes formed in the core die body 2, so that the extrusion plate 21 is attached to the core die body so as to be movable in the mold opening direction. After the molding of the resin product W is completed, when the core die body 2 is separated from the cavity die body 1 by a drive device (not shown),
Mounting plate 17 for pushing extrusion plate 21 with extrusion rod 24
A through hole 25 is formed in.

Therefore, when the core die main body 2 moves away, the extrusion rod 24 pushes the extrusion plate 21, so that the extrusion plate 21
is adapted to move toward the capity die main body l side. Note that the extrusion rod 24 has a drive device not shown.

When opening the mold after molding the resin product W, the gate part G
In order to allow the runner R to remain on the core die body 2, a reverse tapered portion 26 is formed in the core die body 2, and the hole 27 formed in the second cutting block 17 is further axially A reverse tapered portion 29 is also formed at the tip of the ejector pin 28 that is slidably fitted. Core die body 2
In order to take out the runner R1 remaining in the extrusion plate 21, an ejector turbine 31 is fitted into a hole 30 formed in the core die body 2 in communication with the reverse taper part 26 so as to be slidable in the axial direction.
Fixed. Further, in order to take out the runner R2 remaining in the second cutting block 17, the ejector turbine 28 fitted into the hole 27 so as to be slidable in the axial direction is fitted into the hole formed in the extrusion plate 21 so as to be slidable in the axial direction. are combined.

An engagement pin 32 is attached to the second cutting block 17,
As shown in FIG. 3, a U-shaped two-pronged portion 33 is provided at the tip, and a flange portion 28a formed on the ejector turbine 28 engages with the two-pronged portion 33. As shown in FIGS. 2(a) and 2(b), this bifurcated portion 33 is located in a notch 34 formed in the extrusion plate 21, and when the extrusion plate 21 moves toward the core die body 2. A stopper 36 that passes through a groove 35 provided in the fork 33 and still contacts the flange 28a of the ejector turbine 28 is fixed to the extrusion plate 21.

Next, the operation will be explained with reference to FIGS. 4 to 6. This is a diagram showing a state where the mold is clamped as shown in FIG. 4, and after applying a pressing force to the cavity die body 1 to the core die body 2, the molten resin is released from the spool 11.
The products formed by the first and second cutting blocks 15 and 1.7 pass through the runner R and the gate G and are filled into the product forming section 3.

After the injection is completed and the resin has hardened, the hydraulic cylinder 18 is actuated to lower the slide cam 19 and the second
Retract the cutting block 17 to the left.

Then, as shown in FIG. 4, the first cutting block 1 is moved toward the second cutting block 17 by the elastic force of the coil spring 16.
Step 5 advances, and the gate 01 is cut out from the resin product W while being held between the second cutting blocks 15 and 17. At this time, the runner I in the part sandwiched between the first and second cutting blocks 15. Divided by the cooperation of 17 people.

After that, as shown in Fig. 5, the mold is opened and the core die body 2 is removed.
When separated from the cavity die body L, the resin product W
is attached to the core die body 2. Next, when the extrusion rod 24 is advanced and the extrusion plate 21 is moved toward the core die 2, the extrusion bottle 23 is moved so that the ejector turbines 28, 31 of the core die body 22 protrude from the surface of the core die body 2, as shown in FIG. Runner l<1, R
Remove 2. After that, the push rod 24 is quickly retreated to close the mold, and the hydraulic cylinder 18 is driven to return the slide cam 19 to the position shown in FIG. 2(a) in preparation for the next operation.

FIG. 7 is a diagram showing another embodiment of the present invention, in which a hydraulic cylinder 18 is used as a drive means for moving the second cutting block 17 in the previous embodiment, whereas a slide cam is used as a drive means for moving the second cutting block 17. A drive cam 37 that comes into contact with the cavity die body 1 is attached to the cavity die body 1, and the movement of the core die body 2 relative to the cavity die body 1 is converted into movement of the slide cam. The symbol is attached. In this case, the slide cam 19 is driven by the elastic force of the coil spring 39 installed between the stopper 38 fixed to the core die body 2 and the slide cam 19, so the hydraulic cylinder 18 in the previous embodiment is unnecessary. be.

As described above, according to the present invention, a product forming section is formed between a cavity die main body and a core die main body that is movable towards and away from the cavity die main body, and a product forming section is formed between a cavity die main body and a core die main body that can move toward and away from the cavity die main body, and the product is injected from a spool provided on the cavity die main body. In the injection mold, the product molding part is filled with a molten resin, in which a first cutting block is attached to the cavity die body so as to be movable toward the core die body; A second cutting block, which forms a thin and long gate between itself and the first cutting block, is movably moved toward the cavity die body. Since the driving means for moving the second cutting block is attached to the core die body, it is possible to cut out the gate from the product when taking out the resin product from the mold after resin molding, unlike the conventional method. It is no longer necessary to remove the gate manually or by pressing, etc., and by using a film gate or fan gate, it has become possible to improve the finish of the resin product and greatly improve the efficiency of injection molding.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a resin product molded by injection, FIG. 2(a) is a sectional view showing an injection mold according to an embodiment of the present invention, and FIG. 2(1)) is a sectional view taken along the line ■-■ in FIG. 2(a), and FIG. 3 is a perspective view showing the tip of the retaining bottle.
4 is an enlarged sectional view of the main part of FIG. 2, FIGS. 5 and 6 are enlarged sectional views of the main part showing the molding process of the present invention, and FIG. 7 is an enlarged sectional view of the main part showing another embodiment of the invention. It is a diagram. G...gate, 1<...u/su, W...resin product, l...cavity die body, 2...core die body, 3...product molding section, 15...th 1 cutting block,
]6... Spring, 17... Second cutting block, 18...
...Hydraulic cylinder. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] A product molding section is formed between a cavity die main body and a core die main body that can move toward and away from the cavity die main body, and a molten resin injected from a spool provided in the cavity die main body is injected into the product molding section. In the injection mold for filling, a first cutting block is attached to the cavity die body so as to be movable toward the core die body, and an elastic force directed toward the core die body is applied to the first cutting block. and a second cutting block forming a thin and long gate with the first cutting block is attached to the core die body so as to be movable toward the cavity die body, and the second cutting block is moved. A mold for injection molding, characterized in that a driving means for driving the core die is attached to the core die body.