JP3257347B2 - Good compression discrimination method and apparatus for injection compression molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for judging a good product of injection compression molding for controlling the injection filling amount at the time of injection compression molding in which a molten resin is injected and filled in a mold and then compression is performed on a mold clamping side. is there.

[0002]

2. Description of the Related Art Conventionally, non-defective products of a molded product obtained by injection compression molding have been determined as follows. (1) Since the control accuracy of the injection filling amount to be filled into the mold has a great influence on the subsequent compression process on the mold clamping side, a non-defective product is determined based on a deviation from an injection stroke set value in the injection filling process.

(2) The position of the mold is detected, and a non-defective product is determined based on a deviation from a set value of a mold opening amount during an injection filling process or a deviation from a set value of a compression completion position during a compression process.

(3) A resin pressure, a resin temperature, and the like in a mold are detected, and deviations from respective set values during a compression process (for example, a difference between a PVT curve corresponding to a cooling, solidification, and shrinkage behavior of a resin and an actually measured value). Non-defective is determined based on the difference). Was made by

[0005]

However, the conventional non-defective method has the following problems. That is, (1) The injection filling amount may fluctuate due to a difference in back pressure setting at the time of measurement, a variation in operation of the check ring at the time of injection, a variation in resin temperature during plasticization, and the like. Furthermore, since the quality of the molded product is determined by the state after the completion of the compression step, it can be said that it is impractical to determine a non-defective product based on a deviation from an injection stroke set value in the injection filling step.

(2) In the case where non-defective items are determined based on the deviation from the set value of the mold opening during the injection filling step, for the same reason as in the above (1), it is more difficult to set the optimum mold opening, and also, Since it is impossible to cope with the case where the molding conditions such as the resin temperature fluctuate, it can be said that this is a method for determining a non-defective product that lacks accuracy.

[0007] In the case of performing non-defective product discrimination based on the deviation from the set value of the compression completion position, the discrimination can be performed at a timing closer to the final shape of the molded product. The mold is undergoing compression deformation, and the resin is also undergoing compression deformation. In this state, there is a dimensional difference from the product taken out of the mold. The discrimination still lacks accuracy.

For example, even when the filling amount is excessively large and clearly deviates from the allowable quality value, depending on the setting of the compression force value, the compression may be possible up to the compression completion position set value. Unless the consistency between the pressure and the compression force value is accurately grasped, there is a high possibility that a wrong determination will be made.
In any case, it can be said that it is difficult to apply a high-precision injection compression molding to a non-defective product determination method because the state of the resin in the mold is indirectly detected.

(3) Compared with the above (1) and (2), the state of the resin in the mold is directly detected, so it can be said that this is the most accurate discrimination method. The resin must be in direct contact with the resin in the mold (even if the detection is made via the protruding pin, the protruding pin and the resin are in contact). Therefore, the position is limited to a position that does not affect the appearance of the product. Is generated.

Furthermore, in the conventional detection method, the detection signal for discriminating non-defective products is a pinpoint signal, and it is not possible to grasp the entire inside of the cavity. Even if a large number of detection sensors are mounted, they are merely a collection of pinpoint data, and only complicate software and hardware for processing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple comparison and discrimination based only on mold position detection when the mold clamping force before injection filling and before product removal is removed. ,
An object of the present invention is to provide a non-defective product and method for injection compression molding that can perform high-precision non-defective product determination without being affected by fluctuations in molding conditions during molding, and as a result, can supply a non-defective product stably.

[0012]

In order to achieve the above object, according to a first aspect of the present invention, when performing injection compression molding of a resin, a compression step is performed using a mold position before injection filling as a reference point. When the mold position when the mold clamping pressure is removed for product removal after completion is outside the allowable value set from the quality allowable range value of the molded product with respect to the reference point, it is determined that the product is defective, In the invention of the second aspect, the reference point is set in a state where both molds touch by the mold clamping operation. In the third invention, a mold position detecting section for detecting a mold position and a reference point setting section for setting a mold position before injection filling as a reference point are provided for taking out a product after the completion of the compression step. A non-defective product discriminating unit that compares a detection signal from the mold position detecting unit when the mold clamping pressure is removed with a set value of the reference point setting unit and generates a defective product signal when the value deviates from a set quality allowable value. It is configured to have a unit.

[0013]

By using the mold position before injection filling as a reference point and comparing the mold position when the mold clamping pressure is removed for taking out the product after the completion of the compression process with the reference point to determine a good product,
It is completely unaffected by disturbance factors that adversely affect control accuracy, such as variations in the operation of the check ring during injection and fluctuations in molding conditions such as resin temperature during molding. In addition, since non-defective products are determined based on the state of the mold at the time of completion of compression, which determines the quality of molded products, this is the most ideal method of determination, and both the software and hardware aspects of control are simple and high accuracy is achieved. Non-defective products of easy injection compression molding can be easily determined.
That is, in the injection compression molding in which the compression action is added on the mold clamping side, the mold clamping force must be continuously applied until the compression is completed. Ideally, the compression action is working. Therefore, when the mold clamping force after the completion of the compression is removed, the optimum molding condition is that the mold slightly backs with the compression restoring force of the molding resin body. By setting the amount of this backing within the quality standard range of the molded product, a high-quality molded product is obtained. In a mold designed in consideration of the amount of shrinkage due to cooling and solidification of the resin, it is necessary to set the back amount in consideration of the design value.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of a method and apparatus for determining a non-defective product in injection compression molding according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a control conceptual diagram according to an embodiment of the present invention.
FIG. 2 is a flowchart of good product discrimination by injection compression molding according to the embodiment of the present invention, and FIG. 3 is a flowchart of good product discrimination during injection press molding according to the embodiment of the present invention.

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

A mold clamping cylinder 6 is provided on the back of the movable platen 4.
The movable platen 4 is fixed to the tip of a piston 6a that moves back and forth inside and a piston rod 6b of the piston 6a, and pressure oil is introduced before and after the piston 6a so that the movable platen 4 can be moved back and forth. I have. Reference numeral 25 indicates a cavity.
Reference numeral 1 denotes a mold clamping device.

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

The screw 11 is rotatably provided in the barrel 14, and the resin material in the hopper 14a is heated and compressed in the supply zone and the compression zone, melted and measured in the measurement zone, and injected into the nozzle 15 through the injection zone. It is configured to be.

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

Reference numeral 12 denotes an injection cylinder, and reference numeral 13 denotes a forward / reverse rotation motor which is directly connected to the screw 11 so as to rotate the screw 11 forward / reverse.

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, and a good product discrimination unit 20.

The position sensor 7 is connected to a mold position detector 18. Further, a reference point setting section 19 for setting the position of the movable mold 2 before injection filling by the position sensor 7 as a reference point.
And the mold position detecting unit 18 are connected, and the detection signal from the mold position detecting unit 18 and the set value of the reference point setting unit 19 when the mold clamping pressure is removed for taking out the product after the completion of the compression process. And a non-defective product discriminating unit 20 that generates a defective signal when the value deviates from the set quality tolerance is connected.

A method for determining a non-defective product using the injection compression molding apparatus described above will be described. First, injection compression molding in which a compression action is added on the mold clamping side is classified into the following two methods depending on the position of a mold before injection filling. (1) A method in which a molten resin is injected and filled into a mold which has been closed in advance, and then compression is performed on the mold clamping side (FIG. 2). (2) A method of injecting and filling a molten resin into a mold held at a mold opening position in consideration of the amount of compression in advance, and then performing compression on the mold clamping side (FIG. 3).

First, a method for determining a non-defective product by so-called injection compression molding will be described with reference to FIG. A low-pressure injection compression method in which the molten resin is filled in the molds 2 and 3 that have been closed in advance and then compressed on the mold clamping side will be described.

First, in Embodiment 1 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 have touched each other, the hydraulic pressure control valve 8 is controlled by the mold clamping pressure setting means to send pressure oil to the mold clamping cylinder 6 to fix the movable mold 2. The mold is pressed against the mold 3 to increase the pressure of the mold.

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.
9 is set. 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 step-up (reference point B). Either A or B is determined in advance based on molding conditions, product shape, and the like.

After the completion of the pressurization of the mold, the cavity 25 is injected and filled. Due to the balance between the injection-filled resin pressure and the mold-clamping force applied by the mold-clamping cylinder 6 during the injection-filling, the movable mold 2 retreats in the direction away from the fixed mold 3 (mold-opening behavior). ).

At any time during injection completion 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 to perform a compression process on the mold clamping side. In this case, the mold clamping force generated by the mold clamping cylinder 6 may maintain 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 to take out the product. Here, the amount of change (mold position C) of the movable mold 2 when the mold clamping pressure is removed is detected by the position sensor 7, and
The non-defective product discrimination unit 20 compares the reference point (A or B) with a permissible value (D) in consideration of a permissible value of the product quality.

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. After the cooling and solidification of the resin is completed, when the mold clamping pressure is removed, the movable mold 2 is allowed to move relative to the fixed mold 3 by an amount corresponding to the solid elastic compression amount of the resin. Ideally, they are separated within. In addition, by performing non-defective product discrimination at the time of mold clamping and depressurization closest to the state of the product, highly accurate discrimination can be performed during the operation of the molding cycle.

Therefore, the mold position (C) after the mold clamping pressure
Is out of the allowable value (D) (CA> D or CB> D or CA <D or CB <
In the case of D), since the product quality is out of the allowable range, the non-defective product discriminating unit 20 transmits a defective product signal. If C is within the range of D (CA = D or CB = D), it is determined to be good.

Next, a method for determining a non-defective product by injection press molding will be described with reference to a second embodiment shown in FIG. When setting the compression amount (that is, the mold opening amount), the movable mold 2 is advanced to the fixed mold 3 side to set the origin of the movable mold 2, and the movable mold 2 and the fixed mold 3 are touched. Set the origin.
Here, the detection signal from the position sensor 7 is received by the mold position detection unit 18 to set the origin, and is set as a reference point to the reference point setting unit 19 (reference point A).

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

After the setting of the mold opening is completed, the cavity 25 is injected and filled. At any time 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 a compression process on the mold clamping side. Perform

After the completion of the compression process on the mold clamping side, the hydraulic control valve 8
To remove the mold clamping pressure of the mold clamping cylinder 6 to take out the product. Here, in the same manner as in the first embodiment, the amount of change (mold position C) of the movable mold 2 when the mold clamping pressure is removed is detected by the position sensor 7 and compared with the allowable value (D). Discriminator 2
If it is 0, a good product is judged.

When the mold position (C) at the time of pressurizing and lowering the mold is out of the allowable value (D) (CA> D or C-
If A <D), the quality is out of the allowable range of the product, and the good product discriminating unit 20 transmits a defective product signal. If C is within the range of D (C−A = D), a good product signal is transmitted. .

In the present embodiment, the detection position of the mold is detected by attaching the detection sensor 7 to the mold at a position closer to the resin in the cavity 25 in order to improve the detection accuracy. It is also possible to detect by the position, the stroke position of the mold clamping cylinder 6, and the like. However,
In this case, the detection accuracy is slightly reduced, but the effect of the present invention can be found sufficiently.

[0040]

As is apparent from the above description, according to the present invention, (1) the mold position before injection is set as a reference point, and the mold clamping pressure is removed for taking out the product after the completion of the compression step. The quality of the molded product is determined by comparing the mold position at the time with the allowable value for the reference point to determine the quality of the molded product. Since it is not affected by disturbance factors during molding, it is possible to perform highly accurate non-defective product discrimination, and as a result, it is possible to supply a high-quality molded product. In addition, the determination system does not require simultaneous control of the detection signal and the injection or the mold clamping side, so that simple control is possible, and as a result, the operability is extremely easy. (2) By using the reference point of the discrimination as the mold closing position before injection filling and the comparison point as the mold fluctuation amount when the mold clamping pressure after the completion of compression is removed, a wide variety of injection compression can be performed by one discrimination system. Since it can be applied to any of the molding methods, productivity is greatly improved.

[Brief description of the drawings]

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

FIG. 2 is a flow chart of non-defective product determination by injection compression molding according to the embodiment of the present invention.

FIG. 3 is a flowchart of non-defective product discrimination at the time of injection press molding according to the embodiment of 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 supply source 10 Injection device 12 Injection cylinder 13 Forward / reverse rotation motor 14 Barrel 16 Hydraulic control valve 17 Control Unit 18 Mold position detection unit 19 Reference point setting unit 20 Non-defective product determination unit 25 Cavity

Claims (3)

(57) [Claims] When performing injection compression molding of a resin, the mold position when the mold clamping pressure is removed for taking out a product after the completion of the compression process with the mold position before injection filling as a reference point is the reference point. A non-defective product for injection compression molding, wherein a defective product is determined when the value deviates from an allowable value set from a quality allowable range value of the molded product. 2. A non-defective product determination method for injection compression molding, wherein the reference point according to claim 1 is brought into a state in which both dies are touched by a mold clamping operation. 3. A mold position detecting section for detecting a mold position, and a reference point setting section for setting a mold position before injection filling as a reference point, and a mold clamping pressure for taking out a product after the completion of the compression process. A non-defective product discriminating unit that compares a detection signal from the mold position detecting unit when the value is removed with a set value of the reference point setting unit and issues a defective product signal when the value deviates from a set allowable value of quality. Non-defective product for injection compression molding.