JP3759671B2 - Injection compression molding method and compression timing detection device - Google Patents

Description

[0001]
BACKGROUND 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 detection device having a novel mechanism for detecting the timing of compression start during an injection / holding process.
[0002]
[Prior art]
Uniform compressive force is applied to the entire surface of the molten resin by injecting the molten resin into the mold cavity where a low mold clamping force is acting or slightly opened, and then compressing by mold clamping. In addition, in the injection compression molding method to make the pressure distribution in the mold cavity uniform, reduce molding distortion, improve transferability, shorten molding cycle, improve appearance quality and reduce mold clamping force, The timing of starting compression is an important factor that affects the compression effect.
[0003]
Conventionally, in order to measure the timing of starting compression, that is, the timing of increasing the initial clamping force, a method of detecting based on the time measured from the start of injection or the position of the movable platen has been employed.
[0004]
[Problems to be solved by the invention]
However, the former method of measuring the timing with the time measured from the start of injection is the amount of resin filling into the mold at the start of the initial mold clamping force increase due to variations in the back flow rate of the resin from the screw backflow prevention valve. In some cases, burrs may occur immediately before the start of increasing the initial clamping force. Therefore, the timer set value is determined by trial and error.
[0005]
In addition, the latter method of measuring the timing at the position of the movable platen has a small compression margin when the initial mold clamping force is applied to the mold parting surface (usually 1/100 mm range). It is necessary to capture the movement in the first half of / 1000 to 1/100 mm. On the other hand, the amount of forward and backward movement of the movable platen during mold pressurization and decompression usually has a difference between the left and right and top and bottom of the movable platen, and may be 5/1000 mm in a medium-sized machine of an injection molding machine. . That is, since the movement difference when moving the movable platen is often larger than the moving amount of the movable platen for measuring the timing of increasing the initial mold clamping force, a method for detecting this timing is not practical.
[0006]
In other words, conventionally, the timing of changing the initial clamping force in the injection compression molding method has been detected from the time measured from the start of injection or the position of the movable platen, but the former is the compression timing due to variations in the reverse flow rate of the resin in the cylinder. At that time, the amount of resin filling in the mold varied, and the latter was difficult to detect directly because the amount of movement of the movable platen was very small.
[0007]
Therefore, the present invention provides an injection compression molding method and a compression start timing detection device that make it easy to set the timing for increasing the initial mold clamping force and perform compression molding with a constant resin filling amount in the mold. The issue is to provide.
[0008]
[Means for Solving the Problems]
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. That is, the injection compression molding method of the present invention is an injection compression molding method for detecting the timing of the start of compression based on the position of the resin in the mold cavity during filling in the injection / holding process, In the mold cavity, the step of projecting the detection pin so as to move in the resin flow direction, and the resin that has reached the position where the detection pin protrudes and is moved in the resin flow direction, The detection pin is pushed in, and the operation pin attached to the detection pin via the piston activates the operation switch when the detection pin is pushed in, and the timing when the operation switch is activated is compressed. And detecting as a start timing.
The position of the resin is detected by the detection device of the present invention having a detection pin that can project into the mold cavity. The detection device of the present invention includes a cylinder attached to the mold, a piston provided in the cylinder and pressed against the mold cavity side by a spring, and attached to the mold cavity side of the piston in the mold cavity. Consists of a detection pin that protrudes so as to move in the flow direction of the resin that has reached the position where the detection pin protrudes, an operation pin that is attached to the anti-mold cavity side of the piston, and an operation switch that is operated by the operation pin The compression timing detection is characterized in that when the detection pin is pressed by the resin and moves in the flow direction of the resin, the operation pin activates the operation switch, and the operation of the operation switch is detected as a compression start timing. Device.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings together with examples.
[0010]
FIG. 1 is a schematic diagram of a compression timing detection apparatus used for carrying out an injection compression molding method according to the present invention. In the figure, a detection device 4 for detecting the position of the resin A being filled in a mold cavity 1c formed by the fixed mold 1b and the movable mold 1a is attached to the outer wall of the fixed mold 1b. The detection device 4 is attached to a cylinder 5 attached to the fixed die 1b, a piston 7 provided in the cylinder 5 and pressed against the die cavity by a spring 6, and attached to the die cavity side of the piston 7. A detection pin 8 protruding into the mold cavity, an operation pin 9 attached to the anti-mold cavity side of the piston 7, and an operation switch 10 such as a limit switch or a proximity switch operated by the operation pin 9. It consists of and.
[0011]
Next, the operation of the detection device will be described.
[0012]
When the resin A filling the mold cavity 1c reaches a predetermined position of 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 is operated by the operation switch 10. Actuate. When the mold cavity 1c is filled with the resin A, the tip of the detection pin 8 is pressed so as to be positioned on the same plane as the inner surface of the mold cavity 1c.
[0013]
FIG. 2 is a process diagram 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 with the initial mold clamping force.
(C) Injection starts with the advance of the screw 2, and the resin in the screw cylinder 3 starts to be injected into the mold 1, and the mold is slightly opened by the injection pressure during the injection. However, it may not open depending on the initial clamping force setting.
(D) The position of the resin A in the mold cavity 1c during filling, which is set in advance, is detected by the detection pin 8 of the detection device 4 and is set as the initial mold clamping force increase start timing.
(E) Increase the initial clamping force and start compression.
[0014]
【The invention's effect】
The present invention allows the detection pin to protrude into the cavity of the mold and directly detect the degree of filling of the resin, thereby eliminating variation in the filling amount at the start of compression and providing a more uniform compression effect. Can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a compression start timing detection device according to the present invention.
FIG. 2 is a process diagram showing an injection compression molding method according to the present invention.
[Explanation of symbols]
1 Mold 1a Moving mold 1b Fixed mold 1c Mold cavity 2 Screw 3 Screw cylinder 4 Detector 5 Cylinder 6 Spring 7 Piston 8 Detection pin 9 Actuation pin 10 Actuation switch A Resin

Claims (2)

An injection compression molding method for detecting the timing of the start of compression based on the position of the resin (A) in the mold cavity (1c) during filling that is set in advance in the injection / holding step ,
Projecting the detection pin (8) into the mold cavity (1c) so as to move in the flow direction of the resin (A);
A step in which the detection pin (8) is pushed in by being pressed by the resin (A) reaching the position where the detection pin (8) protrudes and moving in the flow direction of the resin (A);
An operation pin (9) attached to the detection pin (8) via a piston (7), the operation switch (10) being operated when the detection pin (8) is pushed; ,
An injection compression molding method including a step of detecting a timing at which the operation switch (10) is operated as a compression start timing. A detection device (4) for detecting the compression timing in injection compression molding includes a cylinder (5) attached to the mold (1), and a mold cavity side by a spring (6) provided in the cylinder (5). A piston (7) pressed against the piston (7), and a detection pin ( a ) that is attached to the mold cavity side of the piston (7) and protrudes into the mold cavity (1c) so as to move in the flow direction of the resin (A). 8), and said piston (7) actuating pin attached to Hankin cavity side (9) is constructed from a hydraulic actuated switch (10) by the actuating pin (9), the detection When the detection pin (8) moves in the flow direction of the resin (A) by being pressed by the resin (A) reaching the position where the pin (8) protrudes, the operation pin (9) is moved to the operation switch ( 10) Activate It was compression timing detection device and detecting the actuation of the actuating switch (10) as the timing for starting the compression.

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