JPS58224729A - Mold for injection molding - Google Patents

Abstract

PURPOSE:To enable to part the resin of a product and a gate by a small power without causing an extraordinary pressure change, by making the gate setting part of a mold movable and moving the movable part in the direction which blocks the gate port of a product before the resin injected in the mold solidifies. CONSTITUTION:A mold is composed of the cavity core 4 setting a cavity (a), the gate core 5 setting a gate (b) and the runner core 6 setting a runner (c). The gate core 5 is made movable to the other parts 4, 6 of the mold in an arrow 7 direction and its reverse direction. After a plasticized resin is poured in the cavity (a) via the runner (c) and the gate (b), the gate core 5 is moved in the arrow 7 direction before the resin solidifies. By this, the gate (b) is separated from the cavity (product) (a) and the runner (c) and the gate port of the cavity (a) is blocked by the slide part of the gate core 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection mold having an automatic gate cutting device within the mold.

Conventional injection molds generally use side gates, and the gates are cut after molding, but as molded products become larger and resin containing glass fibers is injection molded, the gates need to be made larger. 2, and an increase in the number of man-hours for gate finishing becomes a problem. On the other hand, when using a bottle point gate or submarine gelt that does not require gel finishing, the size of the gate is limited because if the gate is set too thick, it will have negative effects such as chipping of the molded product.

In order to solve these problems, several proposals have been made for automatic gate cutting devices that cut the gate before the resin cloth hardens in the mold (Japanese Patent Publication No. 53-4
544, mouth open 5! l-5358, opening 53-2584F
). However, the gate automatic cutting devices that have been proposed in the past have a structure in which the resin in the gate part is pushed away to the product part or the launch part by a slide pin and cut, which requires a large amount of power.

The part of the injected resin that comes into contact with the mold surface immediately begins to solidify, so it is not completely pushed away and remains as a lump, making it difficult to leave the gate unfinished.

Furthermore, if an attempt is made to avoid abnormal pressure changes within the mold when pushing away the resin in the gate portion, the apparatus has the disadvantage that it becomes complicated and expensive.

Therefore, the purpose of the present invention is to completely separate and solidify the resin in the product part and the gate part in the mold, without causing abnormal pressure changes due to relatively small power consumption, and to realize an unfinished gate. An object of the present invention is to provide a 7-hi injection mold equipped with a gate automatic cutting device housing.

In the present invention, which achieves the above object, the gate W of the mold is
1 is configured as a movable part that can be moved relative to other parts, and before the injected resin solidifies, this movable part is moved by external power to separate the product part and the gate part, and the gate part is separated from the product part. It was made to solidify on the spot without moving the fat from one part to another. In this case, the gate may be attached to either the bottom or side of the finished product.

The details will be explained below with reference to the drawings.

FIG. 1 shows an example of an injection molded product obtained using a conventional mold with a side gate. With a normal gate structure (molded product 1 and gate as shown in this figure) 2. -1 Inner 3 is completely stamped out to the mold side, and after removing reed 1, cutting and finishing of gate 2 is required.

An embodiment of the present invention is shown in FIGS. 2 and 3. In other words, the mold has a cavity center γ that sets the product part (cavity) a.
4. Gate part '6 Gate core 5, Launch part C
In this case, the gate is placed at a position corresponding to the bottom surface of the molded product. The gate core 5 is configured as a movable part that can move in the direction of the arrow 7 in FIG. 3 and in the opposite direction with respect to the other parts 4 and 6 of the mold.

One end thereof is connected to a drive source (hydraulic cylinder, air cylinder, etc.) not shown.

During resin injection, the gate core 5 is placed in a position relative to the capacity core 4 and runner core 6 as shown in FIG. 2, and the plasticized resin flows into the product section a through the launch section C and the gate section. . Before the resin is filled and solidified,
As shown in FIG. 3, the gate iron 5 is moved in the direction of the arrow 7 by external power. As a result, the gate part is separated from the product part a and the runner part C, and the gate opening of the product part a is covered by the sliding surface of the gate core 5, so the resin filled in each part is solidified on the spot and molded. Item 1. Gate 2.
They are discharged to the runner 3 in a separated state from the mold.

The state is shown in FIG. Since each part of the molded product 1, gate 2, and runner 3 can be discharged by the same method as in the conventional method, illustration of the mechanism is omitted.

By employing the gate automatic cutting device of the present invention as described above, the following effects can be obtained.

(Since the re-gate part itself is moved, the molded product and gate can be completely separated within the mold without leaving a gap, eliminating the need for cutting and finishing the gate after molding.

(2) Since the gate can be cut without displacing the resin, less power is required, and mechanically it is simpler and cheaper to manufacture than other methods.

(3) From a molding perspective, the gate can be made larger and multiple gates can be easily removed, reducing molding defects even in large molded products and low-flow resin molded products such as glass fiber-containing resin.
Furthermore, since the injection time can be shortened and the pressure holding time can be eliminated, the molding cycle can be sped up.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of an injection molded product obtained by a conventional mold with a side gate, Fig. 2 is a cross-sectional perspective view showing the state of the mold according to the present invention during injection, and Fig. 6 is a diagram showing an example of an injection molded product obtained by a conventional mold with a side gate. FIG. 4 is a cross-sectional perspective view showing state U from immediately after solidification to completion of solidification, and is a view showing an example of an injection molded product obtained by the present invention. 1: Molded product, 2: Gate, 32 runners, 4: Cavity core, 5: Gate core (movable part), 6: ″3 Nako γ,
7: Movement direction of gate core, a: Product part (cavity)
, b two-gate section, C: launch section.

Claims (1)

[Claims] In an injection mold that has a gate at a position corresponding to the bottom or side surface of the molded product, the part of the mold that sets the gate part is configured as a movable part that is movable relative to other parts, and this movable part is It is connected to a drive source and separates the gate part and product part of the mold before the resin injected into the mold solidifies.
An injection mold, characterized in that the movable part is moved in a direction that blocks a gate opening of a product section.