JP3453649B2 - Control method of injection molding machine provided with indirect resin pressure sensor and control device therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of an injection molding machine provided with an indirect resin pressure sensor for controlling the operation of an injection device based on a measurement value detected by an indirect resin pressure sensor provided in a heating cylinder. The present invention relates to a method and a control device.

[0002]

2. Description of the Related Art Conventionally, an indirect type resin pressure sensor for converting a strain amount into a resin pressure is attached to the tip of the heating cylinder by utilizing the fact that a strain amount proportional to the resin pressure in the heating cylinder is generated in the heating cylinder. Mounting and feedback-controlling the operation of the injection device based on the resin pressure detected by the indirect resin pressure sensor can be performed, for example, in the publication “Plastic molding technology (10th article).
Vol. 6) ", pp. 13-17.

[0003]

However, the indirect resin pressure sensor has a large drift due to temperature, and when it is used for a long time, its measured value B gradually decreases as shown in FIG. In this case, the difference (error) from the resin pressure A becomes large, and when the injection nozzle comes into contact with the mold, a measurement signal based on the deformation of the heating cylinder that is not caused by the resin pressure is output. There was a problem that proper feedback control of operation could not be performed. In the operation by the control device of the injection molding machine equipped with the conventional indirect resin pressure sensor,
As shown in FIG. 7, the change in the resin pressure is based on the accumulation of the measured value of the indirect resin pressure sensor and the error when the injection nozzle is brought into contact with the mold. Further, when the indirect resin pressure sensor is damaged and the output is always zero, the feedback signal disappears and the machine output becomes maximum, so that the machine may be damaged or the worker may be in danger.

Therefore, according to the present invention, the measured value detected by the indirect resin pressure sensor is accurately grasped as the resin pressure in the heating cylinder by eliminating the error due to the passage of time, and the operation of the injection device is performed by the resin pressure. It is an object of the present invention to provide a control method and a control device for an injection molding machine provided with an indirect resin pressure sensor capable of appropriately performing feedback control. Another object of the present invention is to control an injection molding machine provided with an indirect resin pressure sensor that can prevent a machine or a mold from being damaged even if an abnormality occurs in the indirect resin pressure sensor, or a danger to an operator. A method and a control device.

[0005]

In order to achieve the above object, the invention according to claim 1 is such that, after the mold is clamped by the mold clamping device, the injection device is advanced to move the injection nozzle of the heating cylinder to the metal mold. In an injection molding machine that abuts against a mold, drives an injection member to inject the molten resin in the heating cylinder into the mold from the injection nozzle, and measures the molten resin in the heating cylinder after completion of this injection. When the injection nozzle comes into contact with the mold, it is determined whether or not the measured value detected by the indirect resin pressure sensor attached to the heating cylinder has reached a set value, and the measured value is set. When the measured value is reached, the measured value is reset to zero value, and the operation of the injection device is controlled based on the measured value detected by the indirect resin pressure sensor after the reset.

In the invention of the above structure, when the mold is clamped by the mold clamping device, the injection device is advanced and the injection nozzle of the heating cylinder is brought into contact with the mold. At this time, it is judged whether or not the measured value detected by the indirect resin pressure sensor attached to the heating cylinder has reached the set value, and when the measured value reaches the set value, the measured value is zero. The value is reset, and the injection operation and the metering operation of the injection device are feedback-controlled based on the measured value detected by the indirect resin pressure sensor after the reset.

According to the method of the above construction, when the injection nozzle of the heating cylinder is brought into contact with the mold, the measured value detected by the indirect resin pressure sensor due to the strain generated in the heating cylinder once becomes zero. Since the reset is performed, the indirect resin pressure sensor detects the net resin pressure in the heating cylinder without error due to the passage of time, and the resin pressure accurately controls the injection operation and the metering operation of the injection device. Controlled.

In the method of the above construction, when the measured value detected by the indirect resin pressure sensor attached to the heating cylinder does not reach the set value when the injection nozzle comes into contact with the mold, The operation of the injection device can be stopped when it is determined that the type resin pressure sensor is abnormal (claim 2). According to this configuration, when an abnormality occurs in the indirect resin pressure sensor, the abnormality can be easily determined, and it is possible to prevent the machine or the mold from being damaged or the worker from being in danger.

In the method of the above construction, the operation of the injection device is to perform an injection operation and reset the measured value detected by the indirect type resin pressure sensor to zero value at the time of injection operation after the injection operation is completed. The metering operation can be controlled based on the measured value detected by the indirect resin pressure sensor after the reset (claim 3). According to this configuration, not only the injection operation but also the metering operation are reset to zero values by the indirect resin pressure sensor in the operation of the previous process, and are appropriately controlled by the net resin pressure. .

Further, the invention according to claim 4 is a mold clamping device for clamping a mold, a nozzle touch drive means for advancing the injection device to bring the injection nozzle of the heating cylinder into contact with the mold, and the heating device. Equipped with an injection means for injecting the molten resin in the cylinder into the mold from the injection nozzle by driving the injection member, and a measuring means for measuring the molten resin in the heating cylinder after the injection by this injection means is completed. In an injection molding machine, an indirect type resin pressure sensor attached to the heating cylinder, a detection means provided in the nozzle touch drive means for detecting that the injection nozzle is in contact with a mold, and the detection means Judgment means for judging whether or not the measured value detected by the indirect resin pressure sensor has reached a set value when contact of the injection nozzle with the mold is detected, and the measured value by the judging means. Reaches the set value A structure provided with reset means for resetting the measured value to zero value, and control means for controlling the operation of the injection device based on the measured value detected by the indirect resin pressure sensor after the reset by the reset means. I am trying.

In the invention of this structure, when the detection means detects the contact of the injection nozzle with the mold, it is determined whether or not the measured value detected by the indirect resin pressure sensor has reached the set value. When the measured value reaches the set value, the reset value resets the measured value to zero, and the control is performed based on the measured value detected by the indirect resin pressure sensor after the reset. The means controls the operation of the injection device. According to the apparatus having the above-described configuration, the measured value of the indirect resin pressure sensor when the injection nozzle is in contact with the mold is reset to a zero value, so that the operation of the injection apparatus thereafter does not have an error due to the passage of time. It is accurately controlled by the measured value of the net indirect resin pressure sensor.
Moreover, the structure of the device is simple and easy to implement.

Further, in the apparatus having the above construction, when the measurement value detected by the indirect resin pressure sensor by the judging means does not reach the set value, it is judged that the indirect resin pressure sensor is abnormal and the injection is performed. An abnormal stop means for stopping the operation of the device may be provided (Claim 5). With this configuration, when the indirect resin pressure sensor is abnormal, the operation of the injection device is stopped by the abnormal stop means, and the safety of the machine and the operator is achieved.

Further, in the apparatus having the above structure, the reset means resets the measurement value detected by the indirect resin pressure sensor at the time of the injection operation to zero value before starting the weighing operation after the injection operation by the injection means. (Claim 6) According to this configuration, since the measured value by the indirect resin pressure sensor in the operation of the previous step is reset to zero value by the reset means, the injection operation is of course performed. The metering operation is also appropriately controlled by the net resin pressure.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a hydraulic injection molding machine, which comprises a mold clamping device 2 and an injection device 3. In the mold clamping device 2, an end plate 6 is connected to a fixed plate 4 by a tie bar 5, and a movable plate 7 between the end plate 6 and the fixed plate 4 and guided by the tie bar 5 is fixed to the end plate 6. The mold clamping cylinder 8 moves back and forth with respect to the fixed platen 4 via the toggle mechanism 9 to move the mold K.
It is designed to open and close and to close the mold. The crosshead 9a of the toggle mechanism 9 is provided with a mold clamping encoder 10, which detects the moving position of the crosshead 9a to know the moving position of the movable plate 7.

The injection device 3 has an injection nozzle 1 at the tip.
1 is provided with a heating cylinder 12, and an injection screw (injection member) 13 (see FIG. 2) inserted into the heating cylinder 12 is rotated by a hydraulic motor (not shown) to melt and knead the resin material. Then, this molten resin is injected into the injection screw 13
While applying back pressure by an injection cylinder (not shown) that retracts the resin, the resin reservoir 12 inside the tip end side of the heating cylinder 12
a (see FIG. 2), the measured molten resin is moved forward by the injection cylinder by the injection cylinder,
The injection nozzle 11 injects into the cavity of the mold K that has been clamped. In the above description, the injection screw 13, the hydraulic motor for rotating the injection screw, the injection cylinder for applying a back pressure, and the like constitute the measuring means, and the injection screw 13, the injection cylinder for advancing the same, and the like constitute the injection means.

A nozzle touch cylinder (driving means for nozzle touch) 14 for moving the injection device 3 forward and backward with respect to the fixed platen 4 to bring the injection nozzle 11 into contact with the mold 9 is mounted on the frame 3a of the injection device 3. Rod 14a is connected.
The nozzle touch cylinder 14 is connected to a hydraulic pressure source E by a pipe 16 via an electromagnetic switching valve 15. A hydraulic pressure sensor (detection means) 18 is connected to the upstream side of the check valve in the conduit 16a of the pipe 16 connected to the rod side of the nozzle touch cylinder 14. On the front end side of the heating cylinder 12, the resin reservoir portion 1 is provided from the outer peripheral portion toward the center side.
A bottomed sensor hole 12b approaching 2a is drilled. An indirect resin pressure sensor 17, which detects the strain of the heating cylinder 12 by the resin pressure acting on the resin reservoir 12a and converts it into a resin pressure, is attached to the sensor hole 12b with a screw 17a.

Next, the structure of the control device 19 for controlling the injection molding machine 1 will be described. In FIG. 1, reference numeral 20 denotes a control calculation means, which receives a signal from the mold clamping encoder 10 via an input interface 21, and
The signal output from the indirect resin pressure sensor 17 via the sensor amplifier 22 and the signal output from the hydraulic sensor 18 are input via the A / D converter 23. Further, the control calculation means 20 sends a reset signal to the sensor amplifier 22 via the output interface 24, and outputs the reset signal to both solenoids 15 of the electromagnetic switching valve 15.
Switching signals are output to a and 15b, respectively. The control calculation means 20 has a memory 25 in which a program for executing the operation of the injection molding machine 1 and data necessary for controlling the operation are recorded, and an input key interface 26.
Keyboard 27, display interface 28 via
The display devices 29 are connected to each other via.

When it is confirmed by the signal output from the hydraulic pressure sensor 18 that the injection nozzle 11 is in contact with the mold, the control calculation means 20 causes the indirect resin pressure sensor 17 to drive the sensor amplifier 22. The output signal is the pressure setting value P1 preset in the memory 25.
It has a function of a judgment means for judging whether or not it has reached the set value P1 by comparing with. In addition, the sensor amplifier 2
2, the control operation means 20 is an output interface 2
The control calculation means 20 is a reset means for receiving a reset signal output via 4 and resetting the measured value input from the indirect resin pressure sensor 17 to a zero value in advance.
It is composed with. The reset means is not limited to the above configuration and may have another configuration.

When it is confirmed that the injection nozzle 11 has come into contact with the mold as described above, the control calculation means 20
Alternatively, the reset signal is output when instructed by the machine operation program in the memory 25 at the start timing of the injection process and the metering process of the injection device. Further, the control calculation means 20 has a function of a judgment means for determining whether or not the measured value of the indirect resin pressure sensor 17 has reached a set value P1 and a function of a reset means for resetting the measured value of the indirect resin pressure sensor 17. In addition to the above, when the determination unit determines that the signal from the indirect resin pressure sensor 17 does not reach the set value P1 of the resin pressure, the function of the abnormal stop unit that stops the operation of the injection device and the injection It has a function as a control means for controlling the operation of each step of the molding machine.

Next, the operation of the control device constructed as described above and the control method will be described with reference to FIG. When the automatic operation of the injection molding machine 1 starts, the mold clamping device operates and the mold clamping cylinder 8 advances the movable platen 7 through the toggle mechanism 9 to close the mold K (step S1). The mold clamping is completed by pressing the movable platen 7 by the mold clamping cylinder 8 (step S2). When the mold clamping is completed, the mold clamping encoder 10 detects this and sends an output signal to the control calculating means 20, so that the indirect resin pressure sensor 17 starts the measurement according to the command of the control calculating means 20 (step S3). , The solenoid 15b is excited to switch the electromagnetic switching valve 15, pressure oil is supplied to the rod 14a side of the nozzle touch cylinder 14, the injection device advances, and the injection nozzle 11 of the heating cylinder 12 contacts the mold K. (Step S4). At this time, the hydraulic pressure sensor 18 detects the rising operating pressure of the nozzle touch cylinder 14, and the detection signal is input to the control calculation means 20 via the A / D converter 23, and the control calculation means 20 causes the injection nozzle 11 to operate. The presence or absence of contact with the mold K is confirmed (step S5).

In step S5, when the contact is not confirmed within a predetermined time due to the abnormality of the machine or the like, the machine is stopped by the command of the control calculation means 20. Mold K of injection nozzle 11
When it is confirmed whether or not the contact is made, the measurement value detected by the indirect resin pressure sensor 17 and input to the control calculation means 20 via the sensor amplifier 22 is stored in the memory 25 by the control calculation means 20. Is compared with the set value P1 of No. 1 to determine whether or not the set value P1 has been reached (step S
6). When the measured value reaches the set value P1, the control calculation means 20 outputs a reset signal to the interface 24.
Since it is sent to the sensor amplifier 22 via, the sensor amplifier 22 resets the measured value to a zero value by this reset signal (step S7).

Subsequently, when the control calculation means 20 starts the operation of the injection process based on the operation program in the memory 25, the injection cylinder of the injection device 3 operates, the injection screw 13 moves forward, and the heating cylinder 12 is moved in advance. Resin reservoir 12a
The molten resin which has been weighed in the above is injected into the cavity of the mold K through the injection nozzle 11 (step S8). At this time, the measurement value detected by the indirect resin pressure sensor 17 is sent to the control calculation means 20 via the sensor amplifier 22 as the net resin pressure whose measurement is started after the sensor amplifier 22 is reset. . After that, the control calculation means 20 controls the normal operation of the injection device 3 based on the net resin pressure. Therefore, the feedback control of the filling and holding pressure in the injection process of the injection device 3 and the back pressure in the metering process is accurately performed by the above-mentioned net resin pressure having no error due to the passage of time from the start of operation of the machine.

In step S6, the measured value is the set value P.
If you did not reach the 1, the control arithmetic unit 20 determines that an abnormality in the indirect resin pressure sensor 17 has occurred (step S9), and functions as the abnormality stop means, to demagnetize the solenoid 15b electromagnetic The switching valve 15 is switched to the neutral position and the automatic operation of the machine is stopped (step S10). After the detection is started by the indirect resin pressure sensor 17, after the injection nozzle 11 comes into contact with the mold K,
The elapsed time T from the injection operation to the completion of the metering operation, the measured value P of the resin pressure by the indirect resin pressure sensor 17, and the control calculation means 20 to the sensor amplifier 22.
The relationship with the reset signal R transmitted to is as shown in FIG.

In the above embodiment, the injection nozzle 1
It is confirmed whether or not 1 is in contact with the mold K, and the measured value input from the indirect resin pressure sensor 17 through the sensor amplifier 22 reaches the set value P1 in the memory 25 by the control calculation means 20. When it is determined that the control calculation means 20 sends a reset signal to the sensor amplifier 22, the sensor amplifier 22 resets the measured value to a zero value by the reset signal, and thereafter, the injection device 3 Is controlled based on the measured value from the indirect resin pressure sensor 17 after the reset, but in the process of the operation of the injection device 3, when the injection operation is completed, the control calculation means 20 controls the operation. Reset signal to sensor amplifier 22
The measured value of the resin pressure detected during the injection operation is once reset to a zero value, and the metering operation is controlled based on the measured value detected by the indirect resin pressure sensor 17 after the reset. You may

The elapsed time T at this time and the measured value P of the resin pressure
And the relationship with the reset signal R is as shown in FIG. With this configuration, not only the injection operation but also the metering operation can be accurately controlled by the net resin pressure having no error due to the passage of time. Further, in the above-described embodiment, the present invention is applied to the hydraulic injection molding machine in which each operating unit is driven by the hydraulic drive means, but the present invention is not limited to this, and the rotation of each operating unit is controlled by an electric motor. It can also be applied to an electric injection molding machine of a system in which the reciprocating motion of each operation unit is performed by an electric motor through a motion conversion mechanism including a screw shaft and a nut.

[0026]

As described above, according to the invention described in claim 1, when the injection nozzle of the heating cylinder abuts on the mold, the indirect type resin pressure sensor attached to the heating cylinder is used. Determine whether the detected measured value has reached the set value, if the measured value reaches the set value, reset the measured value to zero value, by the indirect resin pressure sensor after this reset Since the operation of the injection device is controlled based on the detected measurement value, the measured value detected by the indirect resin pressure sensor due to the strain generated in the heating cylinder when the injection nozzle contacts the mold is Since the value is once reset to zero, the indirect resin pressure sensor detects the net resin pressure in the heating cylinder without error due to the passage of time. Accurately measure the weighing operation It is possible to click control.

According to the second aspect of the invention, when the injection nozzle comes into contact with the mold, the measured value detected by the indirect resin pressure sensor attached to the heating cylinder reaches the set value. If not, the indirect resin pressure sensor is judged to be abnormal and the operation of the injection device is stopped. Therefore, if there is an abnormality in the indirect resin pressure sensor, it can be easily judged, and the machine or die It is possible to prevent damage to the work and danger to the operator.

According to the third aspect of the present invention, after the injection operation is completed, the measured value detected by the indirect resin pressure sensor during the injection operation is reset to a zero value, and the indirect resin pressure after the reset is reset. Since the metering operation is controlled based on the measured value detected by the sensor, both the injection operation and the metering operation, respectively, reset the measured value by the indirect resin pressure sensor in the operation of the previous process to zero value, It can be properly controlled by the net resin pressure.

According to the fourth aspect of the present invention, the indirect type resin pressure sensor attached to the heating cylinder and the injection nozzle of the heating cylinder provided in the driving means of the injection device are brought into contact with the mold. Detecting means for detecting and a judgment for determining whether or not the measured value detected by the indirect resin pressure sensor has reached a set value when the contact of the injection nozzle with the mold is detected by the detecting means. Means and resetting means for resetting the measured value to a zero value when the measured value reaches the set value by the judging means, and a measured value detected by the indirect resin pressure sensor after resetting by the reset means. Based on the configuration, the control means for controlling the operation of the injection device is provided, so that the measured value of the indirect resin pressure sensor at the time of contact of the injection nozzle with the mold is reset to zero, and thereafter. Injection equipment Work can be accurately feedback controlled by measurements of indirect resin pressure sensor net without error over time of. Moreover, since the structure of the device is simple, it is easy to implement.

According to the fifth aspect of the present invention, when the determination means determines that the measured value detected by the indirect resin pressure sensor does not reach the set value, the indirect resin pressure sensor is abnormal. If there is an abnormal stop means to stop the operation of the injection device when it is judged that there is something wrong, the operation of the injection device is stopped when the indirect resin pressure sensor is abnormal, preventing the damage of the machine and the safety of the operator. Can be planned.

According to the sixth aspect of the present invention, the reset means sets the measured value detected by the indirect resin pressure sensor during the injection operation to zero after the injection operation by the injection means and before the metering operation is started. Since the value is reset, the measured value by the indirect resin pressure sensor can be reset to zero value by the reset means each time the operation of each process is started, and both the injection operation and the metering operation can be performed by the net resin pressure. Therefore, the feedback control can be appropriately performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a control device of an injection molding machine provided with an indirect resin pressure sensor of the present invention.

FIG. 2 is a vertical sectional view of a heating cylinder in an injection molding machine provided with an indirect resin pressure sensor to which the present invention is applied.

FIG. 3 is a flow chart for explaining the operation of the control device of the injection molding machine provided with the indirect resin pressure sensor of the present invention.

FIG. 4 is a diagram showing changes in resin pressure during operation by a controller of an injection molding machine provided with an indirect resin pressure sensor of the present invention.

FIG. 5 is a diagram showing a change in resin pressure during another operation by the control device of the injection molding machine provided with the indirect resin pressure sensor of the present invention.

FIG. 6 is a diagram showing change characteristics of measured values of an indirect resin pressure sensor.

FIG. 7 is a diagram showing a change in resin pressure during operation by a controller of an injection molding machine provided with a conventional indirect resin pressure sensor.

[Explanation of symbols]

2 Mold clamping device 3 Injection device 10 Mold clamping encoder 11 Injection nozzle 12 Heating cylinder 12a Resin reservoir 13 Injection screw 14 Nozzle touch cylinder 15 Electromagnetic switching valve 17 Indirect resin pressure sensor 18 Oil pressure sensor 19 Controller 20 Control calculation means 22 Sensor Amplifier 25 memory

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Shimada 1300 Okayama, Niigata City, Niigata Prefecture Niigata Iron Works Niigata Seiki Plant (72) Inventor Masakazu Ono 2-11-14, Kugahara, Ota-ku, Tokyo Sankyo Kasei Co., Ltd. (56) Reference JP 5-111935 (JP, A) JP 2000-246773 (JP, A) JP 3-221428 (JP, A) JP 1-259919 ( JP, A) Patent 2649111 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/77 B29C 45/46 B29C 45/84

Claims (6)

(57) [Claims] 1. After the mold is clamped by the mold clamping device, the injection device is moved forward to bring the injection nozzle of the heating cylinder into contact with the mold, and the molten resin in the heating cylinder drives the injection member. An injection molding machine that injects the molten resin into the mold from the injection nozzle and measures the molten resin in the heating cylinder after completion of the injection, and mounts the heating resin on the heating cylinder when the injection nozzle contacts the mold. Determined whether the measured value detected by the indirect resin pressure sensor reached the set value, if the measured value reaches the set value, reset the measured value to zero value,
A method for controlling an injection molding machine provided with an indirect resin pressure sensor, characterized in that the operation of the injection device is controlled based on a measurement value detected by the indirect resin pressure sensor after the reset. 2. The indirect resin pressure sensor, when the measured value detected by the indirect resin pressure sensor attached to the heating cylinder does not reach a set value when the injection nozzle comes into contact with the mold. The method of controlling an injection molding machine provided with an indirect type resin pressure sensor according to claim 1, wherein the operation of the injection device is stopped when it is judged that is abnormal. 3. The operation of the injection device is such that an injection operation and a measurement value detected by the indirect resin pressure sensor at the time of injection operation after completion of the injection operation are reset to a zero value, and the indirect operation after the reset is performed. The control method for an injection molding machine provided with an indirect resin pressure sensor according to claim 1, wherein the measuring operation is controlled based on a measurement value detected by the resin pressure sensor. 4. A mold clamping device for clamping a mold, a nozzle touch drive means for advancing an injection device to bring an injection nozzle of a heating cylinder into contact with the mold, and a molten resin in the heating cylinder. In an injection molding machine equipped with an injection means for driving a member to inject it into the mold from the injection nozzle, and a measurement means for measuring the molten resin in the heating cylinder after the injection by the injection means is completed, An indirect type resin pressure sensor attached to the cylinder, a detection means provided in the nozzle touch drive means for detecting that the injection nozzle is in contact with the mold, and a detection means for detecting the injection nozzle to the mold. When a contact is detected, a judgment means for judging whether or not the measurement value detected by the indirect resin pressure sensor has reached a set value, and the judgment means means that the measurement value has reached the set value. If judged, the measured value (B) reset means for resetting the value, and control means for controlling the operation of the injection device based on the measurement value detected by the indirect resin pressure sensor after the reset by the reset means are provided. A control device for an injection molding machine equipped with an indirect resin pressure sensor. 5. When the determination means determines that the measured value detected by the indirect resin pressure sensor does not reach a set value, it is determined that the indirect resin pressure sensor is abnormal, and the injection device The control device for an injection molding machine provided with the indirect resin pressure sensor according to claim 4, further comprising an abnormal stop means for stopping the operation. 6. The reset means resets a measurement value detected by the indirect resin pressure sensor during the injection operation to a zero value before the weighing operation after the injection operation by the injection means is completed. A control device for an injection molding machine provided with the indirect resin pressure sensor according to claim 4.