JPH02249617A - Injection molding device for disk molded product - Google Patents

Abstract

PURPOSE:To manufacture an injection molding device for molding a central opening section without opening a mold by a method wherein a central component is arranged so as to be moved forward by a shape memory alloy coil spring which may be deformed and stretched by application of electricity, the central component is projected in the cavity after resin injection in the cavity, and an opening is arranged at the central part of the disk. CONSTITUTION:A mold is closed and a material resin is injected from a nozzle 33 into a mold cavity through a sprue bush 16. Then, resin is injected, and electricity is applied to a shape memory alloy coil spring 43 to heat stretch the coil spring 43, move a central component actuation block 41 forward in the arrow direction (a) by the thickness S of a disk and make a central component 40 projected into a cavity. At that time, an end 40a of the central component 40 reaches a cavity surface of a fixed side cavity 14 while molten resin is excluded, and retains said state as it is to form an opening in the center of a molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an injection molding apparatus for a disc molded product having an opening at the center of the disc surface, such as a video disc or a compact disc.

(Prior art) Conventionally, when molding a thin disc molded product with an open center such as a compact disc, for example,
There is a device disclosed in Publication No. 45809. This molding device has a sprue bush concentrically inserted into the cavity of the stationary side mold so as to be movable independently of the stationary side mold, and a punch that can move forward and backward concentrically with the center of the cavity of the movable side mold, The protrusion of the punch causes the sprue bush to retreat without opening the mold, thereby forming a central opening. According to this device, the opening can be formed with the mold closed, so it has excellent effects such as shortening the molding time and forming the opening accurately. Since it is necessary to incorporate a mechanism for advancing and retracting the punch into the molding device, the device becomes complicated and its operation becomes complicated.

(Problems to be Solved by the Invention) Therefore, in view of the above-mentioned circumstances, the object of the present invention is to propose a new injection molding device that can form a central opening without opening the mold using a simpler mechanism and operation. It is something. Furthermore, the present invention proposes an apparatus that simplifies the mechanism for forming the center opening and also simplifies the ejector mechanism of the product.

(Means for Solving the Problems) That is, the injection molding apparatus for disc molded products according to the first invention includes a center member having a tip portion shaped like the center opening of the disc in the movable side cavity of the mold having the disc cavity. The center member is arranged so as to be able to move forward by a shape memory alloy coil spring that changes shape and expands when energized, and after resin is injected into the cavity, the center member is projected into the cavity and an opening is provided in the center of the disk. It is characterized by

Furthermore, the injection molding apparatus according to the second invention has a tip end shaped like a center opening of a disk in the movable side cavity of Venus having a disk cavity, and is capable of moving forward by a shape memory alloy coil spring that changes shape and expands when energized. After placing the center member and injecting resin into the cavity, the center member is projected into the cavity, an opening is provided in the center of the disk, and the molded product ejector is formed by a shape memory alloy coil spring that changes shape and expands when energized. The molded product is characterized in that it is arranged so as to be able to move forward so that the ejector after molding protrudes into the cavity to take out the molded product.

(Example) The present invention will be described in detail below with reference to the attached drawings.
Fig. 1 is a longitudinal cross-sectional view showing the main parts of the injection molding apparatus according to the present invention during molding, Fig. 2 is a longitudinal cross-sectional view showing the center member protruding into the mold cavity, and Fig. 3 is after molding. FIG. 4 is a vertical cross-sectional view showing the molded product ejector in an activated state.

FIG. 1 shows the main parts of an injection molding apparatus according to the present invention. In this embodiment, the first invention and the second invention are illustrated at the same time for convenience of explanation, and will be explained at the same time in the following explanation.

In the figure, reference numeral 10 is a fixed plate, to which a fixed side mounting plate 11 and a fixed side first member 12 are attached. A fixed cavity member 14 is attached inside the first fixed member 12 via a fixed insert member 13 . A spiral cooling groove 14a is provided in the cavity member 14, and a sprue bushing 16 and a fixing member 15 are fitted into the center of the cooling groove 14a. Reference numeral 17 is a locate ring. Note that the reference numeral 32 represents a heating cylinder of the injection device, and 33 represents its nozzle.

Further, reference numeral 20 is a movable plate, and a movable side mounting plate 2 is attached to this.
1 is fixed, followed by the movable first member 22 and the movable second member 22.
Member 23. A third movable member 24°, a fourth movable member 25, and a fifth movable member 26 are attached in this order. Reference numeral 30 is a ram of the mold clamping cylinder. Movable side fifth member 26
Inside there is a spiral cooling groove 28 along with a movable side insertion member 27.
A movable cavity member 28 having a diameter is attached.

On the cavity surface of the movable cavity member 28, a stamper 35 is attached to a standby outer circumference presser 36 and a standby inner hole presser 3.
Fixed by 7. Reference numeral 37a denotes a threaded portion of the stub bar inner hole presser 37, which is threadedly engaged with a gear 39 that meshes with the ohmic portion 38a of the stub bar inner hole presser operating shaft 38, and is attached and detached by rotation of the operating shaft 38. Reference numeral 29 is a bush.

In this invention, a center member 40 having a distal end portion 40a in the shape of a center opening of a disk is disposed on the movable side member concentrically with the center of the cavity. The center member 40 is the movable fourth
The member 25 and t53 pass through the member 24 and are coupled to the center member operating block 41. A spring mounting portion 42 is formed on the center member operating block 41, and a shape memory alloy coil spring 43 is installed in the spring mounting portion.

The shape memory alloy coil spring 43 changes shape and expands when energized, and moves the center member operating block 41 forward by a thickness S (approximately 1 to 2 mm) taken out of the center opening. 43a is a conducting wire of the coil spring 43, and 43b is a control section. In addition,
The shape memory alloy coil spring used in this example is a Ni-Ti alloy with excellent corrosion resistance and shape recovery ability, and has a spring thickness of 2 mm in diameter, a coil diameter of 20 mm, and a spring output of approximately 5 kgf. In order to uniformly move the center member actuating block 41 forward, two or three (preferably, one is provided) as necessary.

Reference numeral 45 denotes a return spring that automatically returns the center member actuating block 41°, which has been advanced by the shape memory alloy coil 43, to its original position after the coil 43 is actuated. Reference numeral 44 represents a mounting portion for the return spring 45.

Next, the ejector mechanism of the second invention will be explained. The ejector 50 is arranged between the bushing 29 and the center member 40.

Reference numeral 51 denotes a central bottle for projecting the resin from the center opening of the disc, which passes through approximately the center of the center member 40 and is connected to the ejector operating first block 52. Reference numeral 55 designates a second ejector operation block coupled to the ejector 50, which is connected to the ejector operation first block 5.
It is connected to the hole 53 of No. 2 through an engaging portion 56 with play.

A shape memory alloy coil spring 62 similar to that described above is installed in the spring mounting portion 61 of the ejector operation first block 52. This shape memory alloy coil spring 62 is heated by electricity, transforms its shape, and expands to advance the ejector actuating first block 52 and eject the center bottle 51 first.
Stage) 0 Then, after moving a certain distance, the first operation block 5
The contact portion 54 of the second ejector operation block 55 abuts against the contact portion 57 of the second ejector operation block 55.
is advanced, and the ejector 40 is advanced (second stage).

The reference numeral 62a is a conductive wire of the shape memory alloy spring 62, and the reference numeral 62b is a control section. On the opposite side of the spring mounting part 61 is a return spring 64 for automatically returning the advanced ejector actuating first block 52 to its original position. e is placed.

Note that the shape memory alloy coil spring 62 used in the ejector mechanism is also the same as the coil spring 4 used for operating the center member.
Two or three of the same type as No. 3 are provided as necessary.

(Operation) Next, the operation of this injection molding apparatus will be explained with reference to the drawings in FIGS. 1 to 4.

First, as shown in Figure 1, the mold is closed and the nozzle 3
3, material resin is injected into the mold cavity via the spring pusher Ll 6.

Next, after the resin is injected, as shown in FIG. 2, the shape memory alloy coil spring 43 is energized, the coil spring 43 is heated and expanded, and the center member operating block 41 is advanced in the direction of arrow a by the thickness S of the disk. , the center member 40 is made to protrude into the cavity. At this time, the tip 40a of the center member 40 is inserted into the fixed cavity 1 while removing the molten resin.
By reaching the cavity surface of No. 4 and maintaining that state, an opening is formed in the center of the molded product.

After injection molding, as shown in FIG. 3, the movable mold is moved back, the mold is opened, and the molded product is taken out. At the time of ejection, the shape memory alloy coil spring 62 is energized to heat and expand the spring 62, thereby moving the ejector actuating first block 52 forward in the direction of arrow b1. Ejector operation 1st
As the block 52 moves forward, the center bottle 51 protrudes from the center member 40 as a first stage, and the sprue resin N at the center opening protrudes and falls.

The first ejector actuating block 52 moves further forward, and its contact portion 54 abuts against the abutting portion 57 of the second ejector actuating block 55, forming the second stage.

As shown in FIG. 4, the second ejector actuation block 55 is advanced. That is, the first block 52 is indicated by the arrow b.
As it moves forward in two directions, the second block 55 moves in the direction of arrow C.
move forward in the direction As the second block 55 moves forward, the ejector 50 protrudes into the cavity and ejects the molded product M. Then, as shown by the chain line, the molded product ejecting arm 71 is lowered to adsorb the molded product M and pull up the molded product.

After removing the molded product, shape memory alloy coil springs 43 and 6
When the energization of the coil spring 2 is stopped, the coil spring contracts as it cools, and each member is automatically returned to a predetermined position by the return spring 44, 64, thereby completing the 1 cycle.

(Effects) As illustrated and explained above, in the injection molding apparatus according to the present invention, the center member having the tip end shaped like a disk center opening advances into the cavity and the disk center opening is performed without opening the mold. The parts can be formed accurately. Moreover, since the center member is advanced using the force generated by shape transformation due to heating of the shape memory alloy coil spring, the mold device can be made smaller and simpler than the conventional punch protruding structure using a cylinder device, etc. It has become possible to easily perform one operation.

Furthermore, in a device equipped with an ejector mechanism, the mechanism can also be made smaller and simpler, contributing to the simplification of the entire molding device.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view showing the main parts of the injection molding apparatus according to the present invention during molding, Fig. 2 is a longitudinal cross-sectional view showing the center member protruding into the mold cavity, and Fig. 3 is after molding. FIG. 4 is a vertical cross-sectional view showing the molded product ejector in an activated state. 10... Fixed platen, 14... Fixed side cavity, 20
...Movable plate, 28...Movable side cavity, 40...
- Center member, 41... Center member actuation block 43... Shape memory alloy coil spring, 50... Ejector, 52... Ejector actuation first block. 55... Ejector operation second block, 62... Shape memory alloy coil spring.

Claims (1)

[Scope of Claims] 1. A center member having a tip end shaped like the center opening of a disk is disposed in a movable side cavity of a mold having a disk cavity so as to be movable by a shape memory alloy coil spring that changes shape and expands when energized. An injection molding apparatus for a disc molded product, characterized in that after resin is injected into the cavity, the center member is protruded into the cavity to provide an opening in the center of the disc. 2. A shape memory alloy coil spring, which has a tip shaped like a central opening of a disk, is disposed in the movable side cavity of a mold having a disk cavity, and is movable by a shape-memory alloy coil spring that changes shape and expands when energized is applied, and the resin is poured into the cavity. After injection, the center member is protruded into the cavity, an opening is provided in the center of the disk, and the molded product ejector is moved forward by a shape memory alloy coil spring that transforms and expands when energized. An injection molding device for a disk molded product, characterized in that the molded product is ejected by protruding into a cavity.