JPH11129304A - Injection compression molding method and compression timing detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the setting of the increase timing of initial mold clamping force by detecting the position of the resin within a mold cavity during filling in an injection/maintenance process to set the increase start timing of initial mold clamping force. SOLUTION: A detector 4 for detecting the position of the resin A during filling within a mold cavity 1c formed by a fixed mold 1b and a movable mold 1a is attached to the outer wall of the fixed mold 1b. The detector 4 is constituted of the cylinder 5 attached to the fixed mold 1b, the piston 7 pressed by a spring 6 within the cylinder 5, a detection pin 8, an operation pin 9 and the operation switch 10 operated by the operation pin 9. When the resin A during filling within the mold cavity 1c arrives at a predetermined position of the mold cavity 1c, the detection pin 8 projected by the spring 6 is pressed and the operation pin 9 operates the operation switch 10.

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 method, and more particularly, to an injection compression molding method and a compression timing having a novel mechanism for detecting the timing of the start of compression during an injection / holding process. The present invention relates to a detection device.

[0002]

2. Description of the Related Art A molten resin is injected into a mold cavity in which a low mold clamping force is acting or is slightly opened, and thereafter, compression is performed by mold clamping. Injection that applies uniform compression force to the mold to make the pressure distribution in the mold cavity uniform and to reduce molding distortion, improve transferability, shorten molding cycle, improve appearance quality, and reduce mold clamping force. In the compression molding method, the timing of starting compression is an important factor that affects the compression effect.

Conventionally, in order to measure the timing of the start of compression, that is, the timing of the increase of the initial mold clamping force, a method of detecting the time from the start of injection and the position of the movable plate has been adopted.

[0004]

However, the former method of measuring the timing based on the time measured from the start of injection is based on the fact that the initial mold clamping force starts increasing due to variations in the reverse flow rate of the resin from the check valve of the screw. In some cases, the amount of resin charged into the mold may vary, and burrs may occur immediately before the start of the initial mold clamping force increase. Therefore, the timer setting value is determined by trial and error.

In the latter method of measuring the timing at the position of the movable platen, the compression allowance when the initial mold clamping force is applied to the mold parting surface is small (usually 1/100 mm allowance). It is necessary to capture the movement of the board in the early 1 / 1000-1 / 100 mm range. On the other hand, the amount of advance and retreat of the movable platen at the time of pressurizing and depressurizing the mold usually causes a difference between the left and right and up and down of the movable platen.
May extend to 5/1000 mm. In other words, since the difference in the movement of the movable plate is often larger than the amount of movement of the movable plate for measuring the timing of the increase in the initial mold clamping force, the method of detecting this timing is not practical.

That is, conventionally, the timing of the change of the initial mold clamping force in the injection compression molding method has been detected based on the time measured from the start of injection and the position of the movable platen. As a result, the amount of resin filling in the mold at the time of compression varies, and in the latter case, direct detection is difficult because the amount of movement of the movable plate is very small.

In view of the above, the present invention provides an injection compression molding method and a compression start timing in which the timing for increasing the initial mold clamping force can be easily set and the compression molding can be performed with the resin filling amount in the mold being constant. It is an object to provide a detection device.

[0008]

In the injection compression molding method according to the present invention, the timing of increasing the initial clamping force is detected by the position of the resin in the mold cavity during filling. The detection of the position of the resin is performed by a detection device having a detection pin that can project into the mold cavity.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described together with embodiments with reference to the drawings.

FIG. 1 is a schematic view of a compression timing detecting device used for carrying out the injection compression molding method according to the present invention. In the figure, a fixed mold 1b is provided on the outer wall of the fixed mold 1b.
A detecting device 4 for detecting the position of the resin A being filled in the mold cavity 1c formed by the mold 1a and the movable mold 1a is attached. The detection device 4 includes a cylinder 5 attached to the fixed mold 1b, a piston 7 provided in the cylinder 5 and pressed by a spring 6 toward the mold cavity, and a piston 7 attached to the mold cavity side of the piston 7. Detection pin 8 protruding into the mold cavity
And an operating pin 9 attached to the piston 7 on the side opposite to the mold cavity, and an operating switch 10 such as a limit switch or a proximity switch operated by the operating pin 9.

Next, the operation of the detection device will be described.

Resin A filling mold cavity 1c
When the detection pin 8 reaches a predetermined position in the mold cavity 1c, the detection pin 8 protruding into the mold cavity 1c by the spring 6 is pressed, and the operation pin 9 operates the operation switch 10. When the resin A is filled in the mold cavity 1c, the tip of the detection pin 8 is pressed and the mold cavity 1c is pressed.
It is configured to be located on the same plane as the inner surface of c.

FIG. 2 is a process chart showing an injection compression molding method according to the present invention. (A) The movable mold 1a touches the fixed mold 1b by closing the mold. (B) The mold 1 is clamped by the initial clamping force. (C) Injection starts when the screw 2 advances, and the resin in the screw cylinder 3 starts to be injected into the mold 1, and during injection, the mold is slightly opened by the injection pressure. However, it may not open depending on the setting of the initial mold clamping force. (D) The preset position of the resin A in the mold cavity 1c during filling is detected by the detection pin 8 of the detection device 4, and this is set as the timing to start increasing the initial mold clamping force. (E) The compression is started by increasing the initial mold clamping force.

[0014]

According to the present invention, it is possible to directly detect the degree of filling of the resin by projecting the detecting pin into the cavity of the mold, so that the variation in the filling amount at the start of compression can be eliminated. A more uniform compression effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a compression start timing detecting device according to the present invention.

FIG. 2 is a process chart showing an injection compression molding method according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 mold 1a movable mold 1b fixed mold 1c mold cavity 2 screw 3 screw cylinder 4 detecting device 5 cylinder 6 spring 7 piston 8 detecting pin 9 operating pin 10 operating switch A resin

Claims (2)

[Claims] The present invention is characterized in that a position of a resin (A) in a mold cavity (1c) during filling which is set in advance in an injection / holding process is detected, and a timing to start increasing an initial mold clamping force is set. Injection compression molding method. 2. A cylinder (5) attached to a mold (1) and a spring (6) provided in the cylinder (5), comprising a detection device (4) for detecting a compression timing in the injection compression molding. A piston (7) pressed toward the mold cavity by the above, a detection pin (8) attached to the mold cavity side of the piston (7) and capable of projecting into the mold cavity (1c); Actuating pin (9) mounted on the side of the piston (7) opposite the mold cavity
And an operation switch (10) operated by the operation pin (9).