JPH0753383B2 - Molding method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for forming a molded product by injecting a material into a cavity from a tunnel gate, for example.

[0002]

2. Description of the Related Art The applicant of the present invention discloses in Japanese Patent Laid-Open No. 60-151013.
No. 1 proposes an injection molding method. This injection molding method uses an extension part that connects the resin from the runner through the tunnel gate to the cavity in order to eliminate the need for gate mark processing and burr removal work, and when the resin is injected into the cavity. , Without filling the inside of the cavity to the extent that the amount of the resin to be injected is approximately the same as the volume of the extension so that an unfilled portion is generated in the cavity, and then the press-fitting pin is extended into the extension. The tunnel gate is cut, the resin in the extension is press-fitted into the cavity, and the press-fitting is stopped when the resin reaches the entrance of the cavity.

[0003]

The above-mentioned molding method can achieve its object sufficiently and is effectively used for that purpose, but there are the following points to be improved. That is, the resin in the extension portion is pushed into the cavity while advancing and cutting the press-fitting pin, but the portion of the resin contacting the inner peripheral surface of the extension portion has a higher solidification rate than the central portion, and therefore, For example, for a resin with a high solidification rate such as a liquid crystal resin, the part in contact with the inner peripheral surface of the extension part may be pushed in in a semi-solidified state. However, there is an inconvenience that the quality of the molded product deteriorates. For this reason, it is necessary to select the resin to be injected depending on the type of molded product.

It is an object of the present invention to make the indentation mark clean.

[0005]

The molding method of the present invention is a manufacturing method in which a material is injected into the cavity from the runner through an extension portion which is continuous with the cavity through the gate portion and the cavity, and at the time of injecting the material, A press-fitting body that extends into the extension so that an unfilled portion having substantially the same volume as the volume of the extension is generated in the cavity without completely filling the cavity with the material. After that, the press-fitting body extends into the extension portion to block the gate portion, and the material in the extension portion is pushed into the cavity, and the pushing is stopped when the material reaches the inlet of the cavity. In order to obtain a good finishing mark, the material in the extension portion is subjected to a predetermined vibrating circumference through the press-fitting body before it is cut at the gade portion and even after it is cut. It is capable of imparting vibration number.

When vibration is applied to the material in the extension through the press-fitting body, there are the following. The first is
This is a case in which the press-fitting body is extended while being vibrated to give vibration to the material. In this case, before extending the press-fitting body,
Pre-vibration may or may not be applied to the material in the extension. Then, when the press-fitting body reaches the entrance of the cavity, the pushing may be stopped, the vibration may be stopped after the stop, or the vibration may be continued for a predetermined time. Second, after the preliminary vibration,
This is a case where the press-fitting body extends in the extension portion without vibrating to perform a pushing operation, stops pushing when reaching the entrance of the cavity, and after stopping, vibrates the press-fitting body again for a predetermined time.

[0007]

[Operation] The vibration of the press-fitting body is transmitted to the injection material in the extension, the vibration energy is converted into heat energy, and the material in the extension which is solidifying softens and moves into the cavity due to the extension of the press-fitting body. And then spread.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An injection mold apparatus used for carrying out the molding method of the present invention will be described with reference to FIGS. The fixed-side template 1 is attached by a fixed-side attachment plate 2, and a sprue bush 3 is inserted in the center of the fixed-side template and the attachment plate and fixed by a locate ring 4. The movable side mold plate 5 is movably provided by a movable side mounting plate 8 via a receiving plate 6 and a spacer block 7.

A cavity 51 is provided in the movable mold plate 5. The movable side mold plate 5 is provided with a relief pin 18 movably in the axial direction, and the tip end surface of the relief pin is a cavity 51.
Has reached the bottom of. The pressure adjusting spring 19 housed in the hole of the receiving plate 6 is in contact with the rear end of the relief pin 18, and the relief pin is always urged by the pressure adjusting spring to exert a spring force toward the cavity 51. ing.

A projecting strip 7a is provided at the center of the inner wall of the hollow portion of the spacer block 7, and an ejector plate 9 and a sliding plate 10 face each other and are inserted in parallel in the hollow portion. There is.

The movable side mounting plate 8 is formed with two through holes 8a and 8b, and rams 11 and 12 of a cylinder (not shown) pass through the through holes, and one of the rams is passed through. Reference numeral 12 is connected to the sliding plate 10, and the other ram 11 is passed through the through hole 10a of the sliding plate, and its tip is connected to the ejector plate 9.

On the front surface of the ejector plate 9, a sprue lock pin 13 and an ejector pin 14 are provided so as to project. The ejector pin is a cavity 5 of the movable side mold plate 5.
It is possible to project into 1.

On the front surface of the sliding plate 10, a press-fitting pin 15 constituting a press-fitting body is provided so as to project, and the press-fitting pin penetrates the through hole 9a of the ejector plate 9 to form the cavity 5
1 can be extended so as to be flush with the resin inlet 52. A vibration device (not shown) is attached to the sliding plate 10.
Since the vibration is applied to the press-fitting pin, the press-fitting pin can also vibrate.

In FIG. 2, an extension portion 53 of the cavity is provided in communication with a resin inlet 52 formed on the bottom surface of the cavity 51, and the runner 5 is provided in this extension portion.
The tunnel gate portion 55 communicating with the No. 4 is communicated.

A bush 16 is attached to the fixed mold plate 1, and a guide pin 17 protruding from the movable mold plate 5 is inserted in the bush.

Next, a method of molding a molded product will be described. Figure 1
In this state, when the resin A is injected and injected from the sprue bush 3, the resin passes through the runner 54 and the tunnel gate portion 55, enters the cavity extension portion 53, and further flows into the cavity 51 from the inlet 52, as shown in FIG. .

At this time, the cavity A is not fully filled with the resin A. That is, the end filling portion B of the resin is generated. The amount of resin injected at this time is set so that the volume of the end filling portion B and the volume of the extension portion 53 are substantially the same. At the same time, the press-fitting pin 15 is vibrated in advance through the sliding plate 10.

In consideration of the time-dependent shrinkage of the molded product after molding, it is more desirable to make the volume of the extension portion 53 slightly larger than that of the end filling portion B.

When the ram 12 of the cylinder is then extended while the resin is still heated and has fluidity, the press-fitting pin 15 extends into the extension 53 to block the tunnel gate 55. . The resin A in the extension portion 53 cut by the interruption of the tunnel gate 55 is pushed into the cavity 51 by the tip surface of the press-fit pin 15, and as shown in FIG.
Match the second surface. At this time, the press-fitting pin 15 is vibrated with a vibration frequency of several Hz to 10 Hz through the sliding plate 10. Therefore, the press-fitting pin 15 cuts and presses the resin while vibrating, and finally pushes the resin into the cavity 51. Therefore, the vibration of the resin hinders solidification of the resin particularly in contact with the inner peripheral surface of the extension portion. Therefore, the resin moves to the inside of the cavity and diffuses while being softened.

After the resin in the cavity 51 is solidified,
The movable side mold plate 5 is operated to open between the fixed side mold plate 1 and
The ejector pin 14 and the sprue lock pin 13 are extended by the action of the ram 11, and the molded product is projected from the cavity.

In the above example, the press-fitting pin 15 is preliminarily vibrated (preliminary vibration) through the sliding plate 10, but the present invention is not limited to this. In the process, the vibration may be stopped, and the vibration (post-vibration) may be restarted when the tip surface of the press-fit pin reaches the inlet 52 of the cavity. Also, press-fit pin 15
May be performed only in the process of extending the press-fitting pin, only in the pre-vibration and the process in the extending process, and only in the process in the extending process and post vibration. .

As another example, FIGS. 4 and 5 show a tab gate instead of the tunnel gate (submarine gate). In FIG. 4, runner 20 to tab 2
After 1, the gate portion 22 is cut by the press-fitting pin 23 to which vibration is applied from the vibration device. After cutting, the molded product P1 is ejected by the ejector pins 24 and 24a. Reference numeral 25 is an ejector pin, 26 is a sprue, 27 is a cold slug well portion, and 28 is a cavity.

6 and 7, as still another example,
The disc gate is shown. In FIG. 6, the annular gate portion 29 is cut by a pipe-shaped press-fitting body 30. The press-fitting body 30 is given vibration of a predetermined frequency as in the above example. Other configurations are substantially the same as the above example. Three
Numerals 1 and 31a are ejector pins, and each ejector pin projects a disk-shaped molded product P2 having a hole at the center. 32 is a sprue, 33 is a cold slug well part, 34 is a cavity, and 35 is an ejector pin.

[0024]

According to the present invention, even after the material is cut at the gate portion, the material can be vibrated by the press-fitting body, so that the material is prevented from solidifying and remains in the cavity while being softened. The marks of the press-fitted body are pushed in and the traces of the press-fitted body are cleaned, the quality of the molded product can be maintained, and the above effect can be reliably obtained even with a material having a high solidification rate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an injection molding die device used for implementing the present invention.

FIG. 2 is an enlarged cross-sectional view showing a filled state of resin.

FIG. 3 is an enlarged cross-sectional view showing a state where resin is pushed in by a press-fit pin.

FIG. 4 is an enlarged cross-sectional view showing an example used for a tab gate and showing a relationship between a cavity and press-fitting pins.

5 is a perspective view of a molded product formed by the example of FIG.

FIG. 6 is an enlarged cross-sectional view showing an example used for a disc gate and showing a relationship between a cavity and a press-fitting body.

FIG. 7 is a vertical cross-sectional view of a molded product formed by the example of FIG.

[Explanation of symbols]

 10 sliding plate 15 press-fitting pin 20 runner 22 gate part 23 press-fitting pin 28 cavity 29 gate part 30 press-fitting body 34 cavity 51 cavity 52 inlet 53 extension 54 runner 55 tunnel gate part A material (resin) B unfilled part

Claims (5)

[Claims] 1. A material with a production method through the extension portion continuous to the cavity through a gate portion from the runner is injected into the cavity, when the injection of the material, pressure inclusion bodies are extending the extension portion with blocking the gate portion Te, pushing the material in the extension portion which is cut at the gate portion into the cavity, the distal end surface of the press-fitting body be one that stops pushing when it reaches the inlet of the cavity the material in the rolled <br/> length portion is, and before being cut by the gate portion
Molding method characterized in that vibration is imparted through the vibration of the press-fitting member after / or cutting. 2. The molding method according to claim 1, wherein the press-fitting body is extended while being vibrated to extend into the extension portion to impart vibration to the material. 3. The extension of the press-fitting body according to claim 2,
A molding method characterized in that vibration is applied to the material in the extension portion in advance. 4. The molding method according to claim 3, wherein the pressing is stopped when the tip of the press-fitting body reaches the entrance of the cavity, and the press-fitting body is vibrated for a predetermined time after the stop. 5. Before the press-fitting body is extended, the material in the extension part is previously vibrated, and then the extension part is extended without vibrating the press-fitting body and is pushed at the time of reaching the cavity inlet. A molding method, which comprises stopping and vibrating the press-fitted body for a predetermined time after stopping.