JPH0671696A - Tunnel gate type synthetic resin molding machine - Google Patents

Abstract

PURPOSE:To prevent knock-down of a molded product by resin fixed in a runner and a gate in the case of releasing it from molds in a tunnel gate type synthetic resin injection molding machine. CONSTITUTION:A cavity 7 is recessed in one mold 2, a tunnel-like gate 11 for making a runner communicate with the cavity 7 is opened, and a wall 12 protrudes at a position corresponding to the gate 11 of mating surface of the mold 2. When resin B1 fixed in the runner and the gate 11 is once largely deflected to be deformed and then largely jumped to be deformed to be returned to its original shape at the time of releasing from the molds, knock-down of the resin fixed in the gate 11 which is brought into contact with a product A is prevented by the wall 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called tunnel gate (or submarine gate) type synthetic resin injection molding apparatus.

[0002]

2. Description of the Related Art As a synthetic resin injection molding apparatus, a tunnel gate type is used as shown in FIG. In other words, this tunnel gate type molding apparatus has a cavity 22 matched to the shape of a product and a cavity 22 on the mating surfaces of a pair of molds 20 and 21 that can be closely attached and separated from each other.
And a runner 23 for supplying the molten synthetic resin c from the sprue to the mold 20 having the cavity 22 formed therein, and a tunnel-shaped gate 24 for injecting the molten synthetic resin from the runner 23 into the cavity 22. Is formed in an inclined shape so as to open to the mating surface of one mold 20 and the inner side surface of the cavity 22.

According to this structure, after the resin in the cavity 22 is solidified, the first push-up pin 25 provided on one of the molds 20 pushes up the product a and demolds it in the gate 24. Since the resin b1 and the product a are automatically separated, it is not necessary to cut the product from the resin solidified in the gate by the cutting device as in the so-called pinpoint gate type molding device, and the molding work can be performed efficiently. Moreover, since the gate traces remaining on the product a are small and inconspicuous, the product a can be finished beautifully.

[0004]

By the way, in this tunnel gate type molding apparatus, when the product a is stamped out, the resin b2 solidified in the runner 23 is used as the second push-up pin provided in one die 20. The resin b2 and b1 solidified in the runner 23 and the gate 24 are removed from one mold 20 by extruding at 26.

In that case, the resin b hardened in the gate 24
Since 1 is in the state of being engaged with the gate 24, FIG.
As shown in FIG. 5, the resin b2, b1 solidified in the runner 23 and the gate 24 is largely bent and deformed by the push-up by the push-up pin 26, and then the engagement with the gate 24 is released. At the same time that the engagement with the resin is released, the resins b2, b1 return to the original shape and deform as if they largely bounce from the flexurally deformed state.

Therefore, when the resins b1 and b2 are returned and deformed, the tip of the resin b1 solidified in the gate 24 is the product a.
There is a problem that the product a is bounced off frequently by touching, and therefore, there is a problem that the product a disappears or it takes time to collect the bounced product a. An object of the present invention is to provide a tunnel gate type molding apparatus that solves this problem.

[0007]

In order to achieve this object, the present invention provides a mating surface of a pair of molds that can be closely contacted and separated from each other.
A cavity for molding and a runner for the cavity are formed in a recess, and a gate for communicating the runner and the cavity is formed in one of the two molds in which the cavity is formed, and a mating surface of the one mold. And a cavity forming an opening on the inner surface of the cavity, in a part of the mating surface of the one die corresponding to the gate, the mating surface of one die A wall member is provided so as to block between the opening hole of the gate and the cavity, while the mold is closely attached to a portion of the mating surface of the other mold corresponding to the wall member. It is configured to form a recess into which the wall body fits.

[0008]

With this structure, the resin in the cavity is solidified and the two molds are separated from each other, and the product molded in the cavity is ejected to perform die cutting, and the runner and the tunnel gate are provided. When the resin solidified inside is ejected from one mold, even if the resin solidified inside the runner and the gate bounces off from one mold, the resin solidified inside the gate is removed from the mold. It is possible to reliably prevent the die-cut product from being bounced off because the wall prevents contact with the.

Therefore, according to the present invention, in a tunnel gate type molding apparatus, a molded product can be obtained without impairing its advantage, that is, molding can be performed efficiently and the product can be finished beautifully. This has the effect of reliably eliminating problems such as the disappearance of and the trouble of collecting. Further, since the wall body is formed in one mold and the recess is formed in the other mold, the manufacturing cost of the mold does not increase, and the existing equipment is not used. It can be easily applied to a simple processing.

[0010]

Embodiments of the present invention will now be described with reference to the drawings (FIGS. 1 to 7).
It will be described based on. In the figure, reference numeral 1 is an injection molding apparatus provided with a pair of molds 2 and 3, and one of the molds (fixed mold) 2 is a support frame 6 fixed to a fixed frame body 5 screwed to a device body 4. And the other mold 3
The (movable die) is configured to be in close contact with and separated from the one die 2.

Of the mating surfaces of the two molds 2 and 3, a cavity 7 for molding a product is provided on the mating surface of one mold 2.
Four dents are formed in a state of being distributed to the left and right sides, while a sprue 8 communicates with a portion of the mating surface of the other die 3 between the cavities 7 on both the left and right rows of the one die 2. Four first runners 9 are formed so as to linearly extend along the row of the cavities 7 in one of the molds 7 and branch toward two cavities 7. Second runner 10
Are formed so as to communicate with the first runner 9.

In addition, one of the two dies 2 has a second shape in plan view.
Tunnel-shaped gates 11 for communicating the second runners 10 and the cavities 7 are provided at the respective parts located between the tip of the runner 10 and the cavities 2, and the mating surface of one mold 2 and the cavities 7 are provided. Is formed in an inclined shape so as to open to the inner surface of the. Further, a wall body 12 is provided so as to block between the opening hole of the gate 11 and the cavity 7 at a portion of the mating surface of the one die 2 corresponding to each gate 11, and the other die 3 In the state in which both molds 2 and 3 are in close contact with the part of the mating surface of
The recess 13 into which is fitted is formed as a recess.

On one die 2 and the support plate 6, a first push-up pin 14 for pushing out the product A molded in each cavity 7 and a resin B solidified in each second runner 10 are provided.
The second push-up pin 15 for pushing out 1 and the ejector pin 16 for pulling out the first runner 9 pass through. Slide plate 1 slidably inserted in
Lock at 7.

A compression spring 18 is inserted between the slide plate 17 and the support plate 6 for one mold 2.
Further, an engaging groove 16a is cut out at the tip of the ejector pin 16. In the above configuration, both molds 2,
3, the molten synthetic resin C is injected from the sprue 8 in this state to form the product A in each cavity 7, and the molds 2 and 3 are separated after the resin is solidified.

Then, the resin B2 solidified in the first runner 9 is engaged with the engaging groove 16a of the ejector pin 16 in a state of being meshed with each other.
The slide plate 17 is connected to the spring 18 via the ejector pin 16.
When the slide plate 17 moves, the first and second push-up pins 14 and 15 simultaneously project to push out the molded product A from the cavity 7 and the second runner 10 The resin B1 solidified in the inside is ejected from one mold 2, and the product A is separated from the resin B3 solidified in the gate 7.

When the molds 2 and 3 are completely separated, the resin B3 solidified in the first runner 9 is disengaged from the ejector pin 16, and the slide plate 17 is returned to its original position by the spring 18. While returning to the position, the resin B4 solidified in the sprue 8 is separated from the other mold 3. In the middle of this die cutting, the resin B3 is engaged with the gate 11, so that the resins B1 and B2 solidified in the second runner 10 and the gate 11 are once pushed up by the second push-up pin 15, As shown in FIG. 6, after the resin B3 is flexed and deformed, the resin B3 is separated from the gate 11, and at the same time,
It bounces back to its original shape and deforms.

In that case, the resin B hardened in the gate 11
Since the wall 3 prevents the product 3 from touching the product A, the product A is not splashed.

[Brief description of drawings]

1 is a cross-sectional view of a molding apparatus, which is a cross-sectional view taken along line I-I of FIG. 2.

FIG. 2 is a II-II view of FIG.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is a perspective view of a main part.

FIG. 5 is a cross-sectional view showing a molded state.

FIG. 6 is a cross-sectional view showing the middle of die cutting.

FIG. 7 is a diagram showing an operation of the invention.

8A and 8B are diagrams showing a conventional technique, in which FIG. 8A is a diagram showing a molding state, and FIG. 8B is a diagram showing a die cutting state.

[Explanation of symbols]

 1 Molding device 2 One mold 3 The other mold 7 Cavity 8 Sprue 9,10 Runner 11 Tunnel gate 12 Wall 14,15 Push-up pin 16 Ejector pin A Product

Claims (1)

[Claims] 1. A mold cavity and a runner for the cavity are formed in a recess on the mating surfaces of a pair of molds which can be closely attached to and separated from each other, and one of the molds having the cavity is formed with the mold cavity. In a molding device comprising a gate for communicating a runner and a cavity in a tunnel shape so as to open to a mating surface of one mold and an inner side surface of the cavity, a mating surface of the one mold At a portion corresponding to the gate of the above, a wall body is formed so as to block between the opening hole of the gate and the cavity to the mating surface of one mold, while the other of the mating surfaces of the other mold is provided. A tunnel gate type synthetic resin molding device, characterized in that a recess into which the wall body is fitted is formed in a portion corresponding to the wall body in a state where both molds are in close contact with each other.