JPS63197619A - Drilling method of injection molding and drilling device therefor - Google Patents

Abstract

PURPOSE:To prevent generation of weld line, burn marks or internal stress in a molding by a method in which the tip of a punch projects and penetrates thermoplastic resin, and after solidification by cooling, the punch is retracted, whereby the molding is drilled. CONSTITUTION:The air gap 5 of the shape of a hemisphere-shell is formed corresponding to a product by the recessed portion 3 and the projected portion 4 of top and bottom forces 1, 2. The thermoplastic resin melted by heating is injected into the mold from a nozzle, and the air gap 5 is filled with the thermoplastic resin by way of the sprue 7 and a gate 6 provided in the connecting part of the top force 1 to the bottom force 2. Then the tip 9a of a punch 9 is projected in the air gap 5 by operating a punch driving mechanism, and its tip is contacted with the tip of a pin 11, and then the punch 9 penetrates the thermoplastic resin in the molten state in the thick wall direction thereof. The thermoplastic resin is cooled and solidified, while keeping the penetrated state by the punch 9. After the thermoplastic resin in the air gap 5 has been solidified, the tip 9a of the punch 9 is retracted in the top force 1 by operating the punch driving mechanism. Then the mold is opened and the molding is taken out.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and a device for making holes in injection molded products made of thermoplastic resin, and particularly to a method and device for simultaneously forming holes during injection molding. Related to equipment.

[Prior Art] Conventionally, when making a hole in an injection molded product of this type of thermoplastic resin, the injection molded product is cooled and solidified and taken out from the mold, and then punched out to the desired size using a punch. It had a hole in it.

[Problems to be Solved by the Invention] However, in such conventional hole-drilling methods, since the elasticity of the thermoplastic resin is extremely high, the diameter and shape of the outside and inside of the hole differ greatly.

There was a problem in that non-uniform pores were formed.

Focusing on this problem, it is conceivable to provide a core corresponding to the hole in advance in the cavity corresponding to the molded product of the mold. However, if the core is integrally installed in the cavity, the flow of molten resin is divided into two parts by the core during the injection process, which can cause weld lines in the molded product and sometimes cause burns and internal stress. This poses a problem in that it causes a decrease in the strength and deterioration of the appearance of the molded product.

The present invention was made in view of such problems, and after filling a mold with a thermoplastic resin in a molten state,
The purpose is to solve the above problems by piercing the molten resin with a punch before it solidifies.

[Means for Solving the Problems] In order to achieve the above object, the present application fills a void corresponding to the molded product provided at the joint portion of the upper mold and the lower mold with a thermoplastic resin heated and melted, and The tip of the punch is protruded into a predetermined position in the gap, the tip penetrates the thermoplastic resin in a molten state, and after cooling and solidifying, the punch is retreated to make a hole in the molded product. Provides a method for making a hole in an injection molded product as a specified invention, as well as an upper mold and a lower mold that can be opened and closed by providing a gap corresponding to the molded product at the joint, and at least one of the upper mold and the lower mold that can be moved back and forth. a punch that is supported and has a tip that protrudes into the gap at a predetermined position in the gap and spans between the upper and lower molds to form a hole to be drilled in the molded product; and a punch that is moved forward and backward to open the tip. A combined invention provides an apparatus for punching holes in injection molded products, characterized by comprising a punch drive mechanism that protrudes into the gap and retreats from the gap.

[Function] According to the invention of the present application, after filling the void of the molded product provided in the mold with the molten thermoplastic resin, the punch is projected into the molten thermoplastic resin, and the resin is After solidifying, the punch is retracted to punch holes in the molded product during injection molding.

[Embodiment #1] Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram showing a main part of an embodiment of the present invention.

First, to explain the configuration, in the figure, 1 is the upper mold of the mold, 2 is the lower mold of the mold, a hemispherical recess 3 is provided at the joint of the upper mold 1, and the lower mold 2 is provided with a hemispherical recess 3. A hemispherical convex portion 4 smaller than the concave portion 3 is provided at a position corresponding to the concave portion 3 at the joint portion, and these concave portions 3 and convex portions 4 form a half-shell-shaped cavity 5 corresponding to the molded product. is formed. Therefore, both the upper and lower molds 1.2 are configured to be openable and closable. 6 is a gate formed on the upper mold 1, and 7 is also a sprue.

Furthermore, the upper die l is provided with a through hole 8 whose one end is open in the central portion, which is a predetermined position of the cavity 5.
A punch 9 whose tip 9a projects into the cavity 5 is slidably inserted. Although not shown, a punch drive mechanism for advancing and retracting the punch 9 is provided at the other end of the punch 9, and the punch drive mechanism is activated after the heated and melted thermoplastic resin is filled into the mold. tip 9a of punch 9
protrudes into the cavity 5.

As the punch drive mechanism, various types of actuators such as a cylinder device driven by fluid pressure or an electromagnetic solenoid operated by electromagnetic force can be used.

Further, the lower mold 2 is provided with a communicating hole lO which is concentric with the through hole 8 and has one end open to the void 5.
A pin 11 with its tip facing the gap 5 is slidably inserted into the hole O. A flange 12 is provided in the middle of the pin 11 in the axial direction, and a spring 13 whose one end is seated on this flange 12 constantly urges the pin 11 toward the gap 5. In such a state, the pin 11 The tip surface of the convex portion 4 &4
It is on the same plane and also comes into contact with the protruding tip surface of the punch 9. 14 is a cover that prevents the spring 13 from falling off.

Next, the operation of this embodiment will be explained.

When manufacturing a molded product, a thermoplastic resin heated and melted by a heating device (not shown) is injected into the mold from a nozzle, and sprue 7 and gate 6 provided at the joint between upper mold 1 and lower mold 2 are used.
The thermoplastic resin is filled into the void 5 through the steps.

After that, the punch drive mechanism is activated to remove the tip 9 of the punch 9.
A is projected into the gap 5, and its tip is brought into contact with the tip of the pin 11, so that the punch 9 penetrates the molten thermoplastic resin in the thickness direction. While maintaining the penetrating state of the punch 9, the thermoplastic resin is cooled and solidified.

After the thermoplastic resin in the gap 5 has solidified, the punch drive mechanism is operated to move the tip 9a of the punch 9 into the upper mold 1, open the mold, and take out the molded product.

Thereby, holes can be simultaneously formed in the molded product during the molding process during injection molding.

2 and 3 show other embodiments of the invention.

In this embodiment, the punch 19 placed inside the runner 18 allows
The opening and closing of the runner 18 and the drilling of holes in the molded product can be performed at the same time.

The punch 19 is slidably disposed in a runner 18 provided in the upper mold 20 and opens upward in the figure, and is moved forward relative to the lower mold 23 by the operation of a punch drive mechanism (not shown). fall back.

When the punch 19 moves forward, its tip 19a penetrates the gate 21 and protrudes into the cavity 22, and its tip surface contacts a hemispherical convex portion 23a provided on the lower mold 23. Further, a spherical portion 19b is provided inside the tip portion 19a of the punch 19, and the punch 19 seats on a spherical seat 24 provided inside the runner 18 when moving forward.

When manufacturing a molded product using a mold using a punch 19 having the function of a needle valve, first, as shown in FIG. 3, the punch 19 is retracted to open the gate 21 and the runner The molten thermoplastic resin is injected into the cavity 22 from the cavity 18 to fill the cavity 22 with the molten resin.

Immediately after filling, as shown in FIG. 2, the punch 19 is advanced to close the gate 21, and the tip 19a is protruded into the gap 22 to insert the tip 19a into the still molten thermoplastic resin. Penetrate. Thereby, holes can be simultaneously formed on the molded product during injection molding.

This embodiment takes advantage of the fact that the solidification of the molten resin at the gate portion is delayed the most during the injection process.

[Effects of the Invention] As explained above, according to the present application, a heated and melted thermoplastic resin is filled into a void corresponding to a molded product, and a punch is ejected while the thermoplastic resin is in a molten state. By providing holes in the molded product, the flow of the molten thermoplastic resin is not interrupted during the injection process, which prevents weld lines, burns, and internal stress from occurring in the injection molded product. The effect is that it is possible to provide a method and apparatus that can produce a molded product that does not occur, has high strength, and has a beautiful appearance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view of essential parts showing one embodiment of the present invention, FIGS. 2 and 3 are views showing other embodiments of the present invention, and FIG. 2 is an explanatory view showing the protruding state of the punch. FIG. 3 is an explanatory diagram showing the retracted state of the punch. 1.20: Upper die 2, 23: Lower die 3: Concave portion 4: Convex portion 5.22: Gap 8: Through hole 9.19: Punch 9a, 19a: Tip portion 11: Bottle patent applicant Vision Co., Ltd. agent Patent Attorney Elementary School 1) Osamu Parent Figure 2 Figure 3

Claims (2)

[Claims] (1) Fill a gap formed in a mold corresponding to the molded product with heated and molten thermoplastic resin, protrude the tip of a punch into a predetermined position of the gap, and insert the tip into the molten thermoplastic resin. 1. A method for making a hole in an injection molded product, the method comprising: piercing the hole through the injection molded product, and retracting the punch after cooling and solidifying to make a hole in the molded product. (2) An upper mold and a lower mold that can be opened and closed, each having a gap corresponding to the molded product at the joint, and a mold that is supported by at least one of the upper mold and the lower mold so as to be able to move forward and backward, and that the gap is located at a predetermined position in the gap. a punch having a tip that protrudes inward and spans between the upper and lower molds to form a hole to be drilled in the molded product, and the punch is moved back and forth to make the tip protrude into the gap and retreat from the gap; A drilling device for injection molded products, characterized by comprising a punch drive mechanism.