JPH08174616A - Method and apparatus for controlling injection compression molding - Google Patents

Abstract

PURPOSE: To obtain stably a good product independently of fluctuation in molding condition by a simple comparative control by a method wherein the amt. of injection filling is corrected by comparing the position of a mold when the mold clamping pressure is removed for taking out the product after compression process has been completed with the position of the mold before injection filling. CONSTITUTION: A reference point setting part 19 for setting the position of a movable mold 2 before injection filling as a reference point by means of a position sensor 7 and a mold position detecting part 18 are connected with each other. Further a comparative control part 20 for comparing the set value of the reference point setting part 19 with the detected signal of the mold position detecting part 18 of the position of the movable mold 2 when the mold clamping pressure is removed after compression process has been completed by means of the position sensor 7 and outputting a correcting signal for the amt. of injection filling, is also connected. In addition, the comparative control part 20 is connected to a means 22 for setting the amt. of injection filling and the means 22 for setting the amt. of injection filling is connected with an injection control part 21 being connected to a hydraulic pressure control value 16 for controlling driving of an injection cylinder 12 and a motor 13 for normal and reverse rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and apparatus for injection compression molding for highly accurately controlling the injection filling amount during injection compression molding in which a molten resin is injected into a mold and then compressed on the mold clamping side. .

[0002]

2. Description of the Related Art When performing injection compression molding, the control accuracy of the injection filling amount filled in the mold has a great influence on the subsequent compression process on the mold clamping side, and as a result, the quality of the molded product is determined. This is an important item.

Conventionally, such control of the injection filling amount has been performed as follows. That is, (1) control of the injection filling amount (injection side control) by setting the injection stroke of the injection plunger or the injection cylinder. (2) The position of the mold is detected, and the mold opening amount during injection filling (the mold opening amount is held at the mold opening position that allows for the amount of movement or compression of the mold that moves backward due to the resin pressure of the filled resin). The injection filling amount is controlled (mold clamping side control). (3) The injection filling amount is controlled by detecting the resin pressure in the mold and defining the resin pressure during injection filling (mold side control).

[0004]

However, there are the following problems when the injection filling amount is controlled by the injection side, the mold clamping side and the mold side respectively. (1) In injection-side control, high-precision injection compression molding is performed due to differences in back pressure settings during measurement, variations in check ring operation during injection, variations in stop position of the injection cylinder, etc. at the completion of injection. There is still a large variation in the injection filling amount.

(2) In the mold clamping side control, it is extremely difficult to set the optimum mold opening amount, and it is impossible to cope with the case when the molding conditions such as the resin temperature during molding change. In addition, in order to solve the above problem, there is also a method of detecting the mold position during injection filling and taking measures such as injection stroke correction when deviation from the set value occurs, but during injection filling the injection resin flow Since the kinetic energy of is added to the mold clamping side, the mold opening amount varies and the filling amount cannot be accurately detected depending on the injection conditions.Furthermore, the quality of the molded product is determined by the state after the completion of the compression process, New problems such as lack of accuracy in detection during injection filling have been pointed out.

(3) In the mold side control, it is difficult to predict the resin flow because the resin flow state during injection filling differs depending on the cavity shape of the mold and the mold moves during the injection filling. Therefore, a large detection error occurs depending on the mounting position of the resin pressure sensor or the like. Also,
It is necessary to attach the detection sensor to each die, and there are many problems such as the time and labor required to attach the detection sensor to the die and the limitation to a position that does not affect the appearance of the product.

The present invention has been made in view of the above problems, and a highly accurate injection filling amount by simple comparison control only by detecting the mold position when the mold clamping force before injection filling and before product ejection is removed. The purpose of this control is to stably supply good products without being affected by changes in molding conditions during molding.

[0008]

In order to achieve the above object, in the first invention, when injection compression molding of resin is performed,
The mold position before injection filling is detected, the detected value is used as a reference value, and the mold position when the mold clamping pressure is removed to take out the product after the compression process is completed is set with respect to the reference point. In the second aspect of the present invention, the injection filling amount is corrected when it deviates from an arbitrary set value, and in the second invention, the molten resin is filled in a mold that is closed in advance, and then compression is performed on the mold clamping side. In the method, the reference point according to claim 1 is the mold closing position before injection filling.

According to a third aspect of the present invention, there is provided a molding method in which a molten resin is filled in a mold held in a mold opening position in which a compression amount of the resin is expected in advance, and then compression is performed on the mold clamping side. The reference point described in 1 is set to the mold closing position in the mold touch state which is performed in advance when setting the compression amount. Further, in the fourth invention, the injection filling amount is corrected by
If the mold position when the mold clamping pressure is removed is smaller than the set value, the injection filling amount is increased, and in the fifth aspect, the injection filling amount is corrected by the metal mold when the mold clamping pressure is removed. If the mold position is larger than the set value, the injection filling amount is decreased. In the sixth invention, the injection filling amount correction operation is performed during the test molding operation by setting the molding conditions.
In the invention, the correction operation is performed constantly or at regular time intervals during the molding operation.

Further, in the eighth aspect of the present invention, an injection filling amount setting unit is provided, an injection control unit for performing injection filling based on the setting unit is provided, and a mold position detection unit for detecting the position of the mold and injection are performed. A reference point setting unit that sets the mold position before filling as a reference point, and a detection signal from the mold position detection unit when the mold clamping pressure is removed to take out the product after the compression process is completed, and the reference point The configuration is provided with a comparison control unit that compares the set values of the setting unit and generates a correction signal for correcting the injection filling amount to the injection control unit.

[0011]

[Function] The mold position before injection filling is used as a reference point, and the mold filling position when the mold clamping pressure is removed to remove the product after the completion of the compression process is compared with the reference point to correct the injection filling amount. By doing so, there is no influence of disturbance factors that adversely affect the control accuracy, such as variations in the operation of the check ring during injection and variations in molding conditions such as resin temperature during molding.
In addition, it is the most ideal control method because it is based on the control of the injection filling amount in the mold state at the completion of compression, which determines the quality of the molded product, and the software and hardware aspects of control are simple and highly accurate. It is possible to easily control the injection filling amount.

That is, in the injection compression molding in which a compression action is added on the mold clamping side, the mold clamping force must be continuously applied until the compression is completed, and the molded resin body that has been cooled and solidified at the completion of the compression is the mold clamping. Ideally, some compression is exerted by the force. Therefore, when the mold clamping force after the completion of the compression is removed, the optimum injection filling amount is such that the mold is slightly backed by the compression restoring force of the molding resin body. By setting the backing amount within the quality standard range of the molded product,
Obtain high quality molded products. Further, in a mold designed in consideration of the amount of shrinkage upon cooling and solidification of the resin, it is necessary to set the back amount in consideration of the design value.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a control method and apparatus for injection compression molding according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a conceptual diagram of control according to an embodiment of the present invention,
2 is a control flow chart at the time of injection compression molding according to the embodiment of the present invention, and FIG. 3 is a control flow chart at the time of other injection compression molding similar to the present invention.

The fixed mold 3 is attached to a fixed platen 5 fixed to one end of a machine base (not shown), while the other end of the machine base is provided with a movable mold 2 facing the fixed platen 5. It is attached to the movable platen 4.

A mold clamping cylinder 6 is provided on the back surface of the movable platen 4.
The movable platen 4 is fixed to the piston 6a that moves back and forth inside and the tip of the piston rod 6b of this piston 6a, and the movable platen 4 is movable back and forth by introducing pressure oil before and after the piston 6a. There is. Reference numeral 25 indicates a cavity.

Reference numeral 10 denotes an injection device, which is composed of a screw 11, an injection cylinder 12, a forward / reverse rotation motor 13, a hopper 14a and a barrel 14.

A screw 11 is rotatably provided in a barrel 14, a resin raw material in a hopper 14a is heated and compressed in a supply zone and a compression zone, melt-measured in a measuring zone, and injected into a nozzle 15 through an injection zone. It is configured to be.

A heater for externally heating the resin raw material is provided on the outer peripheral surface of the barrel 14, and the resin raw material is sent forward by the rotation of the screw 11 while being melted.

Reference numeral 12 is an injection cylinder, and 13 is a forward / reverse rotation motor, which is directly connected to the screw 11 and rotates the screw 11 forward and backward.

Reference numeral 8 is a hydraulic control valve, and 9a and 9b are hydraulic supply sources. Reference numeral 17 denotes a control unit, which includes a position sensor 7, a mold position detection unit 18, a reference point setting unit 19, a comparison control unit 20,
It is composed of an injection controller 21 and an injection filling amount setting means 22.

The position sensor 7 is connected to the mold position detector 18. A reference point setting unit 19 that sets the position of the movable mold 2 before injection filling as a reference point by the position sensor 7.
And the mold position detecting unit 18 are connected, and the mold position of the movable mold 2 when the mold clamping pressure after the completion of the compression process is removed by the set value of the reference point setting unit 19 and the position sensor 7. A comparison control unit 20 is connected which compares the detection signals of the detection unit 18 and outputs a correction signal of the injection filling amount. Also,
The comparison control unit 20 is connected to the injection filling amount setting unit 22, and the injection filling amount setting unit 22 is connected to the injection control unit 21 connected to the hydraulic control valve 16 that controls the drive of the injection cylinder 12 and the forward / reverse rotation motor 13. It is connected. In the present embodiment, the position sensor 7 is attached to the molds 2 and 3 to detect the mold position, but the present invention is not limited to this, and the movable platen 4 or the mold clamping cylinder 6 can be mounted. .

A control method using the injection compression molding apparatus described above will be described.

First, a low-pressure injection compression method will be described in which the molds 2 and 3 that have been closed in advance are filled with the molten resin, and then compression is performed on the mold clamping side.

First, in the first embodiment shown in FIG. 2, pressure oil is introduced into the mold clamping cylinder 6 to move the movable mold 2 forward to the fixed mold 3 side.

After the movable mold 2 and the fixed mold 3 are touched, the hydraulic pressure control valve 8 is controlled by the mold clamping pressure setting means to send the pressure oil to the mold clamping cylinder 6 to fix the movable mold 2. Press the mold 3 side to increase the mold clamping pressure.

Here, the detection signal from the position sensor 7 is received by the mold position detecting section 18, and the reference point setting section 1 is used as a reference point.
Set to 9. In this case, the reference point may be set either at the time when the movable mold 2 touches the fixed mold 3 (reference point A) or at any time after the mold clamping pressure increase (reference point B). Either A or B is determined in advance according to molding conditions, product shape, and the like.

After the mold clamping pressure rise reaches the set value, the injection filling amount set by the injection filling amount setting means 22 is set to the injection control unit 21.
To control the hydraulic control valve 16 to drive the forward / reverse rotation motor 13 and the piston of the injection cylinder 12,
Injection filling is performed into the cavity 25 formed by the movable mold 2 and the fixed mold 3.

Along with the injection filling, the movable mold 2 moves in a direction away from the fixed mold 3 due to the balance between the injection filled resin pressure and the mold clamping force applied by the mold clamping cylinder 6 (mold opening). behavior).

At any time during the completion of injection or injection filling, the movable mold 2 is pressed again toward the fixed mold 3 by the mold clamping pressure of the mold clamping cylinder 6, and the compression process is performed on the mold clamping side. In this case, the mold clamping force generated by the mold clamping cylinder 6 may be the mold clamping force set before injection filling or may be changed as necessary.

After completion of the compression process on the mold clamping side, the hydraulic control valve 8
Is controlled to remove the mold clamping pressure of the mold clamping cylinder 6 and take out the product. Here, the movable mold 2 when the mold clamping pressure is removed
Change amount is detected by the position sensor 7, and the mold position detection unit 18
Is input as a comparison value (die position C) for determining whether or not the injection filling amount was appropriate, and comparison calculation is performed by the comparison control unit 20 with the preset value (D) and based on the comparison calculation result. Then, a command to correct the injection filling amount is issued.

That is, in the injection compression molding in which the resin in the cavity 25 is compressed on the mold clamping side, the compression force from the mold clamping side is continued until the molten resin filled in the cavity 25 is cooled and solidified. When the mold clamping pressure is removed after the resin has been cooled and solidified, the movable mold 2 is allowed to move relative to the fixed mold 3 by the amount of the solid elastic compression of the resin, and the allowable range of product quality. Ideally, they are spaced apart within.

Therefore, the mold position (C) after the mold clamping pressure is reduced.
If the mold position (C) is larger than the set value (D) from the set value (D) set based on the reference point (A or B) set earlier and the product quality standard (CA> D) Or C
-B> D), it is determined that the injection filling amount is excessive, and C-
According to the difference between A or CB and D, the comparison control unit 20 outputs a command signal to decrease the injection filling amount to the injection filling amount setting means 22 to correct the injection filling amount. Conversely, C is D
If it is smaller than (C-A <D or CB <D), it is determined that the injection filling amount is too small, and C-A or C
The comparison control unit 20 outputs a command signal for increasing the injection filling amount to the injection filling amount setting means 22 according to the difference between B and D to correct the injection filling amount. If C is within the range of D (CA = D or CB = D), it is determined that the injection filling amount is appropriate.

The set value (D) depends on the quality standard of the product. For example, for a product having a thickness of 2 mm, the quality standard is ±
If the wall thickness tolerance value is 1%, the set value D is the upper limit value = 2.0.
2 mm and lower limit value = 1.98 mm. Further, if the quality standard is the degree of variation in weight, it is converted into an allowable value of the product volume (cavity volume) obtained from the degree of variation in weight, and is further substituted with the variation amount of the movable mold 2 to set value (D).
Will be decided. On the contrary, there is also a method of designing a mold according to the quality standard of the product and setting the set value (D) based on this, and a setting method according to the required product is possible.

The correction means can respond in real time during molding, in which case it directly affects the next molding operation. It is also possible to set an appropriate initial condition of the injection filling amount by the correction means during the test molding operation and to carry out the production molding operation that is continuously performed according to the set value obtained. Further, during the molding operation, it is also possible to perform the comparison calculation process for performing the correction operation at regular time intervals to appropriately manage the injection filling amount.

Next, in Example 2, a low-pressure injection compression method is shown in which a molten resin is filled in a mold held in a mold open position in which the amount of compression is expected, and then compression is performed on the mold clamping side. 3 will be used for the explanation.

When setting the compression amount (that is, the mold opening amount), in order to set the origin of the movable mold 2, the movable mold 2 is advanced to the fixed mold 3 side to move the movable mold 2 and the fixed mold 3 together. Touch to set the origin. Here, the detection signal from the position sensor 7 is received by the mold position detection unit 18, the origin is set, and a reference point is set in the reference point setting unit 19 (reference point A).

The mold opening amount setting means separates the movable mold 2 from the fixed mold 3 until the set mold opening amount is reached. After the set mold opening amount is reached, the position of the movable mold 2 is held by means such as controlling the hydraulic control valve 8 to lock the mold clamping cylinder 6.

After that, the molten resin is injected and filled into the cavity 25 formed by the movable mold 2 and the fixed mold 3. At any point during injection completion or injection filling, the hydraulic control valve 8 is controlled to operate the piston 6a of the mold clamping cylinder 6, and the movable mold 2 is pressed against the fixed mold 3 to perform the compression process on the mold clamping side. I do.

After completion of the compression process on the mold clamping side, the hydraulic control valve 8
Is controlled to remove the mold clamping pressure of the mold clamping cylinder 6 and take out the product. Here, as in the first embodiment, the position sensor 7 detects the amount of fluctuation of the movable mold 2 when the mold clamping pressure is removed, and inputs it to the mold position detection unit 18 as the mold position (C), A comparison calculation is performed by the comparison control unit 20 with a preset setting value (D), and an injection filling amount correction command is issued based on the comparison calculation result.

That is, the mold position (C) is the set value (D).
If it is larger than (C-A> D), it is determined that the injection filling amount is excessive, and the comparison control unit 20 outputs a command signal to decrease the injection filling amount according to the difference between C-A and D. It is output to the amount setting means 22 to correct the injection filling amount. On the contrary, if C is smaller than D (C-A <D),
It is determined that the injection filling amount is too small, and the comparison control unit 20 outputs a command signal for increasing the injection filling amount to the injection filling amount setting means 22 according to the difference between C-A and D to correct the injection filling amount. . If C is within the range of D (CA-D),
It is judged that the injection filling amount is appropriate. The method of setting the set value (D) and the timing of the correction means are the same as in the first embodiment.

[0042]

As is apparent from the above description, according to the present invention, (1) the mold position before injection is used as a reference point, and the mold clamping pressure is removed for taking out the product after the completion of the compression process. By performing the correction operation of the injection filling amount by comparing the mold position at the time with the set value with respect to the reference point, the quality of the injection compression molded product can be controlled in the mold state at the time of compression completion that determines the quality of the molded product. For,
Further, since it is not affected by the disturbance factors during molding, extremely high quality products can be stably supplied.
Also, the control system does not require simultaneous interlocking control between the detection signal and the injection or the mold clamping side, so that simple control is possible, and as a result, operability is extremely easy. (2) Since the control reference point is the mold closing position before injection filling, and the comparison point is the amount of mold fluctuation when the mold clamping pressure is removed after completion of compression, a single control system can perform a wide variety of injection compression. Since it can be applied to any of the molding methods, the productivity is greatly improved. (3) Since it is controlled by the amount of mold variation when the mold clamping pressure is removed after the completion of compression, the injection filling amount can be accurately corrected and used as a product quality determination function. Two controls can be performed simultaneously with one control system. (4) Since the injection filling amount can be properly set during the test operation, a good product can be obtained from the early stage of the production operation, and the productivity is significantly improved. Moreover, even during production operation, it is possible to switch correction control constantly or at regular intervals,
Control that corresponds to production adjustment is possible, and good products can be stably supplied.

[Brief description of drawings]

FIG. 1 is a control conceptual diagram according to an embodiment of the present invention.

FIG. 2 is a control flow chart at the time of injection compression molding according to the embodiment of the present invention.

FIG. 3 is a control flow chart at the time of other injection compression molding similar to the present invention.

[Explanation of symbols]

 2 movable mold 3 fixed mold 4 movable plate 5 fixed plate 6 mold clamping cylinder 7 position sensor 8 hydraulic control valve 9a, 9b hydraulic power supply source 10 injection device 12 injection cylinder 13 forward / reverse motor 14 barrel 16 hydraulic control valve 17 control Part 18 Mold position detecting part 19 Reference point setting part 20 Comparison control part 21 Injection control part 22 Injection filling amount setting means 25 Cavity

Claims (8)

[Claims] 1. When performing injection compression molding of a resin, a mold position before injection filling is detected, and the detected value is used as a reference value, and a mold clamping pressure for taking out a product is completed after the compression process is completed. An injection compression molding control method, wherein the injection filling amount is corrected when the die position when removed is out of an arbitrary set value set with respect to the reference point. 2. In a molding method in which a molten resin is filled in a mold which is closed in advance, and then compression is performed on the mold clamping side, the reference point according to claim 1 is set to a mold closing position before injection filling. A method for controlling injection compression molding, comprising: 3. The method according to claim 1, wherein a molding method in which a molten resin is filled in a mold held in a mold opening position in which a compression amount of the resin is expected, and then compression is performed on the mold clamping side, A method for controlling injection compression molding, wherein a point is set at a mold closing position in a mold touch state which is set in advance in setting the compression amount. 4. The injection filling amount correction according to claim 1, wherein the injection filling amount is increased if the mold position when the mold clamping pressure is removed is smaller than a set value. Injection compression molding control method. 5. The injection filling amount correction according to claim 1, wherein the injection filling amount is decreased if the mold position when the mold clamping pressure is removed is larger than a set value. Injection compression molding control method. 6. A method for controlling injection compression molding, wherein the injection filling amount correcting operation according to claim 1 is performed during a test molding operation by setting molding conditions. 7. A method of controlling injection compression molding, wherein the correction operation according to claim 1 is performed constantly or at regular time intervals during a molding operation. 8. An injection filling amount setting means, an injection control section for performing injection filling based on the setting means, a mold position detecting section for detecting a position of a mold, and a mold position before injection filling. With a reference point setting unit for setting as a reference point, the detection signal from the mold position detecting unit when the mold clamping pressure is removed for taking out the product after the completion of the compression process, and the set value of the reference point setting unit. 8. The injection compression molding control device according to claim 1, further comprising a comparison control unit for generating a correction signal for correcting the injection filling amount to the injection control unit by comparison.