JP2999611B2 - 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 molding die used for molding plastics.

[0002]

2. Description of the Related Art Conventionally, in a molding die having a pinpoint gate of this kind, as shown in FIG. 3 (a), a stationary mold plate 2 and a runner A fixed-side mold portion having a stripper plate 3 and a fixed-side mounting plate 4 is opposed to each other, and a sprue hole 1 is provided in the mold.
The cavity 8 was formed via the reference numeral 5, the runner 6, and the pinpoint gate 7. The sprue hole 15
Was formed in a tapered shape having a smaller cross section from the fixed mold plate 2 toward the press nozzle (not shown). Due to such a mold configuration, the molten resin during molding is formed in the sprue hole 1.
5 and was filled into the cavity 8 through the runner 6 and the pinpoint gate 7. Next, when the mold is partially opened, the fixed side mold plate 2 and the runner stripper plate 3 are separated from each other as shown in FIG. At the time of opening the mold, as shown in FIG. 3 (c), by separating the movable mold plate 1 from the fixed mold plate 2, the product 9 is taken out and the sprue / runner 10 is taken out from the mold. Was.

[0003]

However, according to the prior art, the mold structure is a three-plate structure including the movable mold plate 1, the fixed mold plate 2 and the runner stripper plate 3, so that the number of parts is reduced. Since many assembly adjustments are difficult, there has been a problem that the mold cost is high, especially when small lot production is considered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a molding die in which the cost of the die is reduced by simplifying the structure of the die. It is in.

[0005]

In order to achieve the above object, the present invention relates to a molding die having a pinpoint gate, wherein a sprue bush is provided on a fixed side mounting plate so as to float via an elastic body; A sprue hole formed in a tapered shape having a larger cross section from the pinpoint gate toward the resin injection port. When the mold is closed, the sprue bush is brought into close contact with the nozzle in the mold closing direction by a nozzle touch pressure. A gate cut is performed by projecting the sprue bush in the mold opening direction by the body.

[0006]

According to the present invention, according to the present invention, when opening the mold, the sprue bush arranged on the fixed-side mounting plate is moved out of the mold by the elastic force of the elastic body by separating the press side nozzle from the resin injection port. The projecting force makes it possible to cut the pinpoint gate and easily remove the sprue portion from a so-called reverse tapered sprue hole. That is, since the sprue hole is formed in a reverse tapered shape having a large cross section from the pinpoint gate toward the nozzle side, the conventional runner stripper plate is unnecessary, the number of parts is reduced, and the mold structure is simplified. Becomes possible.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the same or corresponding members are denoted by the same reference symbols throughout the drawings. FIG. 1 shows a main configuration of a molding die according to the present invention. In this figure, the mold includes a movable mold part having a movable mold plate 1,
A fixed mold portion having a fixed mold plate 2 and a fixed mounting plate 4 is arranged to face each other. A sprue groove 15 a is formed inside the fixed mold plate 2 via a cavity 8 and a pinpoint gate 7. Further, a sprue bush 5 is disposed on the fixed side mounting plate 4 via a spring 11, and the sprue bush 5 is mounted by a mounting pin 12 so as to be freely floatable in a mold opening and closing direction by a small gap h.

The fixed-side mounting plate 4 and the sprue bush 5 are provided with sprue grooves 15b and 15c connected to the sprue groove 15a provided on the fixed-side mold plate 2, and these sprue grooves 15a, 15b and 15c A sprue hole 15 is formed. This sprue hole 15
It is formed in a tapered shape whose cross section increases from the pinpoint gate 7 toward the press-side nozzle 13.

As described above, the sprue bush 5 is brought into close contact with the fixed-side mounting plate 4 by pressing the press-side nozzle 13 against the resin injection port of the sprue hole 15 and pressing it. If it separates from the entrance, it is protruded in the mold opening direction by the gap h by the urging force of the spring 11.

FIGS. 2 (a) to 2 (c) are views showing an operation state during molding. That is, as shown in FIG. 2 (a), when closing the mold, the sprue bush 5 is pressed against the fixed side mounting plate 4 in the mold closing direction by the touch pressure of the nozzle 13, whereby the sprue grooves 15a, 15b, 15c are integrated. The molten resin injected from the nozzle 13 is filled into the cavity 8 through the sprue hole 15 and the pinpoint gate 7.

Next, when the resin is solidified, the movable mold plate 1 and the fixed mold plate 2 are separated as shown in FIG. 2B, the nozzle 13 retreats, and the sprue bush 5 is At the same time, the gate is cut off and the sprue portion 10a is released by the force. Further, as shown in FIG. 2 (c), the product 9 is manually taken out of the mold, and the sprue portion 10a whose gate has been cut is taken out of the mold.

[0012]

As described above, according to the present invention, in a molding die having a pinpoint gate, a sprue bushing which is disposed on a fixed mounting plate via an elastic body so as to be free to float, and a resin injection port is provided from the pinpoint gate to the resin injection port. And a sprue hole formed in a tapered shape having a large cross section toward the mold. When the mold is closed, the sprue bush is brought into close contact with the mold in the mold closing direction by a nozzle touch pressure. By performing the gate cut by projecting the mold, the mold structure can be simplified, and the mold cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of a molding die according to the present invention.

FIGS. 2A to 2C are diagrams showing an operation state during molding.

FIGS. 3 (a) to 3 (c) are views showing an operation state at the time of molding by a conventional molding die.

[Description of Signs] 1 Movable mold plate 2 Fixed mold plate 4 Fixed mounting plate 5 Sprue bush 7 Pinpoint gate 8 Cavity 11 Spring 12 Mounting pin 13 Nozzle 15a, 15b, 15c Sprue groove 15 Sprue hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-118421 (JP, A) JP-A-3-214117 (JP, A) JP-A-55-17569 (JP, A) 178926 (JP, U) Japanese Utility Model Hei 4-71224 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/26-45/44

Claims (1)

(57) [Claims] 1. A molding die having a pin point gate, wherein a sprue bush is disposed on a fixed side mounting plate via an elastic body so as to be free to float, and a tapered shape in which a cross section increases from the pin point gate toward a resin injection port. When the mold is closed, the sprue bush is brought into close contact with the mold in the mold closing direction by the nozzle touch pressure, and when the mold is opened, the elastic body projects the sprue bush in the mold opening direction to perform gate cutting. A molding die characterized in that: