JPH0575569B2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention [Field of Industrial Application] This invention relates to a mold structure for a molding machine for molding plastic molded products, and in particular to a gate structure for injecting hot water into the mold. It is related to.

[Prior art] Conventionally, a gate structure called a tunnel gate has been put into practical use in molds for molding plastic molded products, and in this gate structure, when the molded product and gate are extruded from the mold with an extrusion pin, the same molded product and the gate are automatically separated, making it possible to omit the work of separating the gate after taking out the molded product from the mold.

That is, the gate structure includes, for example, a movable mold 31 and a cavity 32 as shown in FIG. movably supported. Then, in the clamped state, a gate 35 is formed between the stationary mold 34 and the movable mold 31, which connects to the cavity 32 via the movable mold 31, and hot water is injected from the gate 35 to perform molding. It can be done. Molded product 36 after pouring hot water
To remove the mold, the fixed mold 34 and the movable mold 31 are opened, and as the molds are opened, the slide core 33 retreats, and as shown in FIG. 7, the molded product 36 and the gate 35 are removed. Push out pin 3
7, 38, the same molded product 36 and gate 3
5 is automatically separated and extruded by the movable mold 31.

[Problems to be Solved by the Invention] In the gate structure as described above, the gate 35 cannot be provided on the front surface of the molded product 36 because the molded product 36 is pushed out using the extrusion pins 37 and 38. Therefore, the gate position is necessarily molded product 36.
It is formed so as to be continuous with the side edge of. However, when the wall thickness of the side edge of the molded product 36 becomes thinner, a problem arises in that it becomes impossible to provide a gate on that side edge, making it impossible to form a tunnel gate. SUMMARY OF THE INVENTION An object of the present invention is to provide a gate structure that forms a tunnel gate even when the side edges of a molded product are thin, and allows the molded product and the gate to be removed from the mold in a separated state.

Structure of the Invention [Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a cavity for molding a molded product by combining a fixed mold, a movable mold, and a mold as the movable mold recedes. A gate is formed between the fixed type and the movable type and a slide core that retreats in the radial direction, and a hole is formed through the slide core, and the gate is connected from between the fixed type and the movable type to the front side of the cavity through the hole in the slide core and slides. The structure is such that the gate and molded product can be separated as the core retreats.

[Operation] With the above means, the gate is connected to the front surface of the molded product, and the molded product and the gate are separated by the retreat of the slide core when the mold is opened.

[Embodiment] Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. A cam 2 projecting diagonally outward is provided on both sides of the front surface of the stationary side matrix 1. A fixed piece 3 is fixed to the board. The movable mother die 4 is an air cylinder (not shown)
It is supported so as to be movable back and forth with respect to the stationary side matrix 1 by the driving force of. A movable front mold 5 as a movable mold is supported on the front surface of the movable mother mold 4 so as to be able to move toward and away from the movable mother mold 4.

A cam member 7 in which a diagonal groove 6 is formed is fixed to the center of the movable mother mold 4, and this cam member 7 projects into the movable front mold 5. An inner slide core 8 is supported in the center of the movable front mold 5 so as to be movable in the radial direction of the mold, and the inner slide core 8 is engaged with the groove 6 of the cam member 7. When the cam member 7 retreats together with the movable matrix 4, the inner slide core 8 moves away from the inserting piece 3, that is, in the direction of arrow A in FIG.

Movable front mold 5 on the outside of the inner slide core 8
An outer slide core 9 is supported movably in the radial direction of the mold. The outer slide core 9 is formed with an engagement hole 11 through which the cam 2 can pass, and the movable front mold 5 retreats together with the movable mother mold 1 from the mold clamped state in which the cam 2 penetrates the engagement hole 11. Then, the outer slide core 9 moves in the direction away from the input piece 3 based on the engagement with the cam 2, that is, in the first direction.
It is designed to move in the direction of arrow B in the figure. A cavity 13 for molding the molded product 12 is formed between the input piece 3 and the inner and outer slide cores 8 and 9 in the mold-clamped state.

A gate 14 for injecting hot water into the cavity 13 passes between the stationary side mother mold 1 and the movable front mold 5, reaches between the movable front mold 5 and the input piece 3, and further penetrates the inner slide core 8. and is connected to the front of the cavity 13. A portion of the gate 14 that passes through the inner slide core 8 is formed into a conical hole 15 that tapers toward the cavity 13, and a bent portion 16 that bends toward the molded product 12 is formed just before the conical hole 15. .

A pressing shaft 17 for pressing the movable front mold 5 is movably supported within the stationary mother mold 1, and the tip end of the shaft 17 is moved within the range of the pressing stroke L1 by the biasing force of a coil spring 18. It protrudes from the front and presses the movable front mold 5 rearward.

A press plate 19 is supported in the movable matrix 4 so as to be movable back and forth, and the press plate 19 has a first extrusion pin 20 for extruding the molded product 12 and a second extrusion pin 20 for extruding the gate. The base end of the pin 21 is supported. The tips of the extrusion pins 20 and 21 are in contact with the molded product 12 and the gate 14, respectively.

A connecting rod 22 is fixed to the outer edge of the movable mother mold 4, and the tip of the connecting rod 22 extends inward at right angles to form an engaging portion 23, which engages the outer edge of the movable front mold 5. It protrudes into an engagement recess 24 provided in the. When the movable mother mold 4 retreats, the engaging portion 23 moves within the engaging recess 24 after moving by the movable stroke L2.
The movable mother mold 4 and the movable front mold 5 are made to move back together by contacting the engaging surface 24a of the movable mold 4 and the movable front mold 5.

Next, a molding operation using the mold as described above will be explained.

Now, as shown in FIG. 1, when hot water is injected into the cavity 13 from the gate 14 with the mold clamped, the molded product 12 is molded in the cavity 13 and at the same time the molded product 12 is Gates 14 are formed in series. In order to take out the molded product 12 and the gate 14, the movable mother mold 4 is moved to the fixed mother mold 1.
When moving backward, the movable front mold 5 is first pressed by the pressing shaft 17 due to the biasing force of the coil spring 18 and moves backward by the movement stroke L1. Then, a gap corresponding to the movement stroke L1 is created between the stationary side mother die 1 and the movable front die 5, and a similar gap is created between the input piece 3 and the conical hole 15 of the gate 14, as shown in FIG. arise.

When the movable mother mold 4 further retreats from this state, the movable front mold 5 does not move back until the engaging portion 23 of the connecting rod 22 comes into contact with the engagement surface 24a of the movable front mold 5, and the movable mother mold 4 moves back. Only type 4 regresses. Then, the cam member 7 retreats together with the movable matrix 4, and the inner slide core 8 moves in the direction of arrow A in FIG. At this time, the tip of the gate 14 is separated from the molded product 12 and is bent in the direction of arrow C in FIG. 2 and removed from the conical hole 15, resulting in the state shown in FIG. 3.

When the movable mother mold 4 further retreats after the engaging portion 23 of the connecting rod 22 contacts the engaging surface 24a, the movable front mold 5 retreats together with the movable mother mold 4. Then, the cam 2 of the stationary side matrix 1 and the outer slide core 9
The outer slide core 9 moves in the direction of arrow B in FIG. 1 due to its action with the engagement hole 11, and eventually the outer slide core 9 completely separates from the molded product 12 as shown in FIG. Then, in this state, the press plate 19 is driven, and the molded product 12 is extruded from the cavity 13 by the first extrusion pin 20, as shown in FIG.
At the same time, the gate 14 is pushed out by the second pushing pin 21. Thereafter, the mold is clamped again, and the above operation is repeated to form a large number of molded products 12.

As described above, in this gate structure, the tunnel gate is formed by the conical hole 15 that passes through the inner slide core 8, so that the gate 14 is connected to the molded product 1.
2 is the front surface in the extrusion direction, not the edge of the molded product 12, so the gate 14 can be easily opened into the cavity 13 regardless of the thickness of the edge of the molded product 12, and the gate 14 can be easily opened into the cavity 13, and the position connected to the molded product 12 can be easily extruded. does not cause any trouble, and when extruding the molded product 12 and gate 14, the molded product 12 and gate 1
4 can be configured to automatically disconnect the tunnel gate.

Effects of the Invention As detailed above, the present invention has the advantage that a tunnel gate can be constructed regardless of the wall thickness of the side end of a molded product, and the gate can be removed from the mold after being separated from the molded product. It has a great effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a gate structure embodying this invention, FIGS. 2 to 5 are sectional views showing the operating process of the mold, and FIG. 6 is a sectional view showing a conventional gate structure related to this invention. 7 are sectional views showing the operation. In the figure, 3 is the input piece 3 (fixed type), 5 is the movable front type (movable type), 8 is the inner slide core, 12 is the molded product,
13 is a cavity, and 14 is a gate.

Claims (1)

[Claims] 1 Cavity 13 for molding the molded product 12
The fixed mold 3, the movable mold 5, and the slide core 8 that retreats in the radial direction of the mold as the movable mold 5 retreats.
A hole 15 passing through the slide core 8 is formed between the gate 14 and the fixed mold 3.
and the movable mold 5 through the hole 15 of the slide core 8 to the front surface of the cavity 13, so that the gate 14 and the molded product 12 can be separated as the slide core 8 retreats. type gate structure.