JPH07117087A - Injection and compression molding apparatus - Google Patents

Abstract

PURPOSE:To make possible precise and stable molding reduced in molding deficiency such as flash, a short shot or a sink by setting the injection part of an injection and compression molding apparatus equipped with at least an injection part to a preplastication type. CONSTITUTION:A control part operates a mold opening and closing hydraulic cylinder 31 to allow a retreated moving die plate 20 to rapidly approach a fixed die plate 10. When the moving die plate 20 reaches a predetermined position, the mold opening and closing hydraulic cylinder 31 is stopped to stop the moving die plate 20. Next, the hydraulic clamping machine 41 of an engaging device 40 is operated to engage the moving die plate 20 so as not to move the same on a tie bar 51. Subsequently, the mold clamping cylinder 55 of a mold clamping device 50 is operated to allow the moving die plate 20 to again approach the fixed die plate 10. When the moving die plate 20 reaches a predetermined position, the mold clamping cylinder 55 is again stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding apparatus suitable for reducing molding defects such as burrs, short shots and sink marks.

[0002]

2. Description of the Related Art Conventionally, when an injection compression molding apparatus is divided into an injection section and a compression molding section, the former injection section has a so-called injection molding machine for plasticizing (including so-called kneading) and injection. Despite being roughly divided into an in-line screw type in which only the screw is used and a pre-plastic type in which plasticization is performed with the screw and injection is performed with a plunger, the former in-line screw type is usually diverted as it is. is there.

[0003]

As described above, the conventional injection compression molding apparatus has the following inconvenience because it uses an in-line screw type injection molding machine as it is as an injection section.

When the molten resin is sent to the front of the screw during plasticization of the resin, the reaction force of the molten resin pushes the screw back. Therefore, the plasticization of the resin supplied from the hopper becomes different depending on the screw stroke, and as a result, the density of the obtained molten resin becomes nonuniform depending on the location, and there is a problem that variations in the molded product occur.

Further, a check ring is attached to the tip of the screw, which moves forward during plasticization to send the molten resin forward through the gap between the tip of the screw and the other end during injection. By moving backward and sealing the gap, the resin is prevented from leaking backward, but in reality, there is a time delay from the start of injection until the check ring is seated and sealed. It is the actual situation that is occurring. Further, the seating position of the check ring is unstable, and therefore, the injection start position fluctuates. Due to the above, even if injection is performed under the same setting conditions, the amount of injected resin varies, and defects such as burrs and short shots occur. Further, in such a case, when the mold is clamped and compressed, the molten resin flows back from the gate portion, sink marks and insufficient weight occur near the gate portion, and there is a problem that the stability of the molded product is impaired.

The present invention has been made in view of the above-mentioned disadvantages of the prior art.
An object of the present invention is to provide an injection compression molding apparatus capable of performing precision stable molding with few molding defects such as burrs, short shots and sink marks.

[0007]

In order to achieve the above-mentioned object, an injection compression molding apparatus according to the present invention is an injection compression molding apparatus comprising at least an injection section and a compression molding section, wherein the injection section is a preplasticizer. It was set as a formula.

Further, the injection compression molding apparatus is provided with at least an injection section and a compression molding section. In the injection compression molding apparatus, the injection section communicates with a communication hole a communicating with the screw tip chamber and a plunger tip chamber. The communication hole a and the communication hole b communicate with each other at least at the intersection of the communication hole b and the communication hole c that communicates with the cavity of the compression-molding portion by changing the position of the communication hole a and the communication hole b. It is a pre-plastic type with a three-way valve.

The injection compression molding apparatus includes at least an injection section, a compression molding section, and a control section. In the injection compression molding apparatus, the injection section has a communication hole a communicating with a screw tip chamber and a plunger. Communication hole b leading to the tip chamber
Is a pre-plastic type having a three-way valve at the intersection of the communication hole and the communication hole c communicating with the cavity of the compression molding section, and the control section is at least the communication hole a at the time of plasticizing the resin.
, The communication hole c is closed at the time of measuring the amount of the injected resin, the communication hole a and the communication hole b are communicated with each other, and the communication hole a is closed when the resin is injected, and the communication hole b and the communication hole c are communicated with each other.
After the injection of the resin is completed, the three-way valve is driven so that at least the communication hole c is closed when the resin is compressed in the compression molding section.

In the above structure, the control unit drives the three-way valve so as to plasticize and measure the resin between the injection of the resin and the compression of the resin in the compression molding unit. Alternatively, the control unit may be configured to drive the three-way valve so as to plasticize the resin between the time of injection of the resin and the time of resin compression in the compression molding unit. .

The injection compression molding apparatus includes at least an injection section, a compression molding section, and a control section. In the injection compression molding apparatus, the injection section has a communication hole a communicating with the screw tip chamber and a plunger. Communication hole b leading to the tip chamber
Is a pre-plastic type having a three-way valve at the intersection of the communication hole and the communication hole c communicating with the cavity of the compression molding section, and the control section is at least the communication hole a at the time of plasticizing the resin.
, And the communication hole c is closed at the time of measuring the amount of injected resin, and the communication hole a and the communication hole b are communicated with each other. When the resin injection and the resin compression in the compression molding portion are simultaneously performed, the communication hole a is closed and communicated. The three-way valve is driven so that the hole b and the communication hole c communicate with each other.

In the above structure, the control unit may drive the three-way valve so that the plasticization of the resin is performed between the injection of the resin and the compression of the resin in the compression molding unit. Good.

[0013]

According to the above construction, since the injection part is of the pre-plastic type, plasticization is carried out by the screw and injection is carried out by the plunger.

This pre-plastic type injection part has a three-way valve at the intersection of a communication hole a communicating with the screw tip chamber, a communication hole b communicating with the plunger tip chamber, and a communication hole c communicating with the cavity of the compression molding part. Of course, in this three-way valve, at least the communication hole a and the communication hole b, and the position (including rotation, the same applies hereinafter) of the three-way valve are changed so that the communication hole b and the communication hole c communicate with each other. Good to be configured. As a result, when the resin is compressed in the compression molding section after the injection of the resin is completed, at least the communication hole a is closed when the resin is plasticized and the communication hole c is measured when the amount of the injected resin is measured, in accordance with a command from the control section. Is closed and the communication hole a and the communication hole b are communicated with each other. When the resin is injected, the communication hole a is closed and the communication hole b and the communication hole c are communicated with each other. At least the communication hole c is sometimes closed.

In this case, the control unit may drive the three-way valve so that the plasticization of the resin is performed between the injection of the resin and the compression of the resin in the compression molding unit. The three-way valve may be driven so that the plasticization and measurement of the resin are performed between the time of injection of the resin and the time of resin compression in the compression molding section. It is possible to raise it.

On the contrary, the control section closes the communication hole a, connects the communication hole b and the communication hole c to each other, and controls the compression molding section synchronously, so that the resin is injected and the compression molding section is controlled. It is possible to perform resin compression at the same time.

Also in the above configuration, the control section may drive the three-way valve so that the plasticization of the resin is carried out between the injection of the resin and the compression of the resin in the compression molding section. By doing so, it becomes possible to increase the molding speed as described above.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The most preferred embodiment according to the present invention will be described with reference to FIGS. The embodiment is applied to a horizontal injection compression molding apparatus as shown in FIG. This horizontal injection compression molding apparatus is composed of a compression molding unit 1, an injection unit 2, and a control unit (not shown).

The compression molding section 1 includes a fixed die plate section 10 for holding a fixed die 11 positioned vertically, a moving die plate section 20 for holding a moving die 21 that can be moved horizontally, and a moving die plate. 20 fixed die plate 1
The moving device 30 for quickly moving forward and backward with respect to 0, the locking device 40 for locking the moving die plate 20 to the diver 51 at the position where the moving die plate 20 approaches the fixed die plate 10, and the moving die plate 20. After the movable die plate 20 approaches the fixed die plate 10 and reaches a predetermined position, the moving die plate 20 is moved to the solid die plate 10 to compress and spread the plastic resin, and the die clamping device 50 is configured. .

On the other hand, the injection section 2 is composed of a plasticizing portion 70 such as a screw 71 for uniformly plasticizing the raw material resin, and a plunger 81 for injecting a molten resin 92 into the cavities 100 of the molds 11 and 21. It is a pre-plastic type injection machine composed of an injection part 80, a communication hole a communicating with the tip chamber of the screw 71, a communication hole b communicating with the tip chamber of the plunger 81, and a communication hole c communicating with the cavity 100 of the compression molding part. A three-way valve 83 is provided at the intersection with the. As shown in FIG. 2, the three-way valve 83 has at least the communication hole a and the communication hole b (FIG. 2 (b2)), and the rotation of the three-way valve 83 causes the communication hole b and the communication hole c.
And ((b4) in the figure) communicate with each other.

Incidentally, the three-way valve 83 need only satisfy the above-mentioned minimum communication condition and closing condition, and it is not necessary that the three-way valve 83 itself has three holes.
For example, as shown in FIG. 3, the three-way valve 83 itself may be provided with one hole. As described above, the three-way valve 82 has various other forms. It should be noted that in FIG. 3, the same functions as those in FIG.

The control unit controls the mold clamping speed of the mold clamping unit 50 of the compression molding unit 1, the mold clamping pressure, the start time of compressing and spreading the plastic resin, the injection start time of the injection unit 2, and the like. , And controls the operation of the three-way valve 83 in synchronization therewith.

For the sake of clarity, the operation based on the command from the control unit will be described below as a whole. The control unit
The mold opening / closing hydraulic cylinder 31 is operated to quickly move the retracted moving die plate 20 toward the fixed die plate 10. When the movable die plate 20 reaches a predetermined position, the die opening / closing hydraulic cylinder 31 is stopped and the movable die plate 20 is once stopped. Next, the locking device 40
The hydraulic tightening machine 41 is operated to lock the moving die plate 20 on the tie bar 51 so as not to move. Next, the mold clamping cylinder 55 of the mold clamping device 50 is operated to move the moving die plate 20 again toward the fixed die plate 10. When the movable die plate 20 reaches a predetermined position, the mold clamping cylinder 55 is stopped again. Next, description will be made with reference to Table 1.

[0024]

[Table 1]

The control unit drives the three-way valve 83 to connect the communication hole a.
Are closed (steps in Table 1, (b in FIG. 2
1)). Then, in this state, the screw 71 is rotated at a constant speed to plasticize the resin supplied from the hopper (not shown) and accumulate the resin in front of the plasticizing cylinder 72 set to a constant temperature. Next, the three-way valve 83 is driven to open the communication holes a and b to allow them to communicate with each other and close the communication hole c (step of Table 1, (b2) in FIG. 2). Then, in this state, the molten resin 92 is sent out from the plasticizing cylinder 72 into the injection cylinder 82, and a predetermined amount is weighed. The three-way valve 83 is driven to close the communication hole a and open the communication holes b and c (step in Table 1, (b4) in FIG. 2). Then, in this state, the plunger 81 is extended and the molten resin 92 is injected into the cavity 100 of the molds 11 and 21. Next, the three-way valve 83 is driven and at least the communication hole c
Is closed (step in Table 1, (b3) in FIG. 2). Then, in this state, the compression molding described below is performed.

The above steps can be performed during the above steps. The above steps may be performed during the steps or subsequent to the steps. Further, if the pressure is balanced between the injection side and the compression side and the compression timing is adjusted, the compression step may be performed at the same time as the step. Valve 83
Drive) is omitted. However, if the injection time is longer than the compression period, the in-table process is additionally performed.

Returning to the original description, the control unit then closes the movable mold 21 with respect to the fixed mold 11 at a predetermined speed and pressure, and injects the molten resin 92 injected into the cavity 10.
These moving molds 21 are brought into contact with the fixed mold 11 while being compressed and spread in every corner of 0 to increase the density of the molten resin 92. Next, the mold clamping cylinder 55 is stopped and the molten resin 92
It remains in that state until it cools. After the molded product has cooled, the mold clamping cylinder 55 is activated to move the movable die plate 2
0 is retracted, the hydraulic fastening device 41 is operated to release the lock, and then the mold opening / closing hydraulic cylinder 31 is operated to return the moving mold 21 to the initial position.

The effects of the embodiment will be described. The resin supplied from the hopper is fitted into the plasticizing cylinder 72 and plasticized by the screw 71 rotating at a fixed position and sent out forward, so that the temperature of the plasticizing cylinder 72 and the rotation speed of the screw 71 are set to be constant. If so, the plasticization that the resin receives is always constant, and the density of the obtained molten resin 92 is uniform regardless of the location. The clearance between the outer diameter of the plunger 81 and the inner diameter of the injection cylinder 82 is designed and manufactured in consideration of the viscosity of the resin 92, and this design and manufacture is easy. Since resin leakage as in the case can be prevented and the injection is performed up to the stroke end, it is possible to always inject the molten resin 92 of the same volume under the same conditions. Further, when performing compression while injecting, the communication holes b and c are communicated by the three-way valve 83, and the compression timing is adjusted while balancing the pressures on the injection side and the compression side. When the compression is performed after the injection is completed, by closing the communication hole c by the three-way valve 83, as in the prior art, molding such as sink mark and insufficient weight near the gate portion caused by the backward flow of the molten resin from the gate portion is formed. The problem of impairing product stability is prevented. As described above, according to the embodiment, since the density of the molten resin is uniform, the injection volume is always constant, and there is no backflow of the resin from the gate portion during injection compression, burrs, short shots, sink marks, etc. It is possible to perform precise and stable molding without the occurrence of molding defects and without variations in molding quality.

[0029]

According to the present invention, in the injection compression molding apparatus,
By making the injection part a pre-plastic type, by providing a three-way valve, and by establishing control of this three-way valve, molding defects such as burrs, short shots and sink marks do not occur, and the molded product It enables precise and stable molding without quality variation.

[Brief description of drawings]

FIG. 1 is an overall side view including a partial cross section of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a three-way valve which is one component in the embodiment of the present invention, in which (a) is an overall view, and (b1)-
(B4) is a dynamic diagram.

FIG. 3 is a view showing another example of a three-way valve which is one component in the embodiment of the present invention, (a) is an overall view, and (b1) to
(B4) is a dynamic diagram.

[Explanation of symbols]

1 Compression molding part 100
Cavity 2 injection part a, b, c
Communication hole 71 Screw 81 Plunger 83 Three-way valve

Claims (6)

[Claims] 1. An injection compression molding apparatus comprising at least an injection section and a compression molding section, wherein the injection section is of a pre-plastic type. 2. An injection compression molding apparatus comprising at least an injection section and a compression molding section, wherein the injection section has a communication hole a communicating with the screw tip chamber, a communication hole b communicating with the plunger tip chamber, and a compression hole. At least at the communication hole a and the communication hole b at the intersection with the communication hole c communicating with the cavity of the molding portion.
The injection compression molding apparatus is characterized in that it is a pre-plastic type having a three-way valve in which the communication hole b and the communication hole c communicate with each other by changing their positions. 3. An injection compression molding apparatus comprising at least an injection section, a compression molding section, and a control section, wherein the injection section has a communication hole a communicating with the screw tip chamber and a communication hole communicating with the plunger tip chamber. b is a pre-plastic type having a three-way valve at the intersection of the communication hole c communicating with the cavity of the compression molding section, and the control section at least closes the communication hole a when plasticizing the resin, When the quantity is measured, the communication hole c is closed and the communication hole a and the communication hole b are communicated with each other. When the resin is injected, the communication hole a is closed and the communication hole b and the communication hole c are communicated with each other. An injection compression molding apparatus characterized in that the three-way valve is driven so as to close at least the communication hole c when the resin is compressed in the compression molding section. 4. The control unit is configured to drive a three-way valve so as to plasticize and measure the resin between injection of the resin and compression of the resin in the compression molding unit. Item 3. The injection compression molding device according to Item 3. 5. An injection compression molding apparatus comprising at least an injection section, a compression molding section, and a control section, wherein the injection section has a communication hole a communicating with the screw tip chamber and a communication hole communicating with the plunger tip chamber. b is a pre-plastic type having a three-way valve at the intersection of the communication hole c communicating with the cavity of the compression molding section, and the control section at least closes the communication hole a when plasticizing the resin, When the quantity is measured, the communication hole c is closed and the communication hole a and the communication hole b are communicated with each other. When the resin injection and the resin compression in the compression molding portion are simultaneously performed, the communication hole a is closed and the communication hole b and the communication hole are connected. c
An injection compression molding apparatus, characterized in that the three-way valve is driven so as to communicate with the. 6. The control unit is configured to drive a three-way valve so as to plasticize the resin between the time of injection of the resin and the time of resin compression in the compression molding unit. The injection compression molding apparatus according to claim 5.