JP2003053812A - Injection molding machine having mold closing unit for protectively controlling mold and method for controlling mold closing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a mold from becoming impossible to be closed due to stopping of a movable mold immediately before a mold contact position by a frictional force or the like in the case of inserting a guide pin of a fixed mold into the movable mold in the case of protectively controlling the mold in an injection molding machine having a mold closing unit for protectively controlling the mold and to set an accurate mold protection finishing position capable of accurately detecting the state of a runner or the like being caught between the molds when the runner is caught therebetween. SOLUTION: The injection molding machine comprises the mold closing unit for protectively controlling the mold by lowering a mold closing force by a drive means at the time of arriving at a mold protectively starting position. In the molding machine, the setting of the mold protection finishing position can be optionally inputted from a set input unit or omitted. When the mold protection finishing position is set, the mold protection finishing position can be arbitrarily changed set between the mold protection starting position and the mold contact position by a signal from the input unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a mold closing device for performing mold protection control for preventing damage to a mold when foreign matter remains in the mold when the movable mold is closed. The present invention relates to a method for controlling an injection molding machine and a mold closing device.

[0002]

2. Description of the Related Art As an injection molding machine provided with a mold closing device for performing mold protection control for the purpose of preventing damage to the mold when foreign matter remains in the mold when the mold is closed, The thing described in Japanese Patent Publication No. 2-30848 is known. What is described in this publication is to perform mold closing control using a servo motor, and the mold protection start position is detected by a mold position detector, and the movable mold is moved to the mold protection start position. Between the mold contact position and the mold contact position, a torque limit command in the mold closing direction is output from the control device that controls the servo motor, and the movable mold is closed with a low torque, and the movable mold is moved within a fixed time. When is not reached the die contact position, it is judged to be abnormal and an alarm is issued.

By the way, a difference in thermal expansion occurs between the fixed mold and the movable mold due to a difference in temperature rise, and when the mold is closed, a frictional force when the guide pin of the fixed mold is inserted into the movable mold. May become large. However, the above-mentioned conventional technique performs mold protection control for closing the movable mold with low torque over the entire section between the mold protection start position and the mold contact position. When the frictional force between the molds is strong, the movable mold may stop just before reaching the mold contact position with the fixed mold, even if no foreign matter is caught between the molds. It occurred rarely and hindered continuous production.

Further, there is provided a mold closing device which uses a hydraulic mechanism and performs mold protection control for the purpose of preventing damage to the mold when foreign matter remains inside the mold when the movable mold is closed. As such an injection molding machine, the one described in JP-A-8-252847 is known. Since the technology described above has a problem in responsiveness in the hydraulic mechanism, the pressure increase is started immediately before the die contact position toward the mold clamping, and intentionally just before the die contact position. Although it is not intended to solve the problem that the movable mold stops due to friction between the molds, the mold protection control section is ended on the mold opening side from the mold contact position, and in the subsequent sections. With respect to the problem that the movable mold stops immediately before the mold contact position by increasing the pressure, the effect of solving the problem can be expected. However, with this technology, the end of the mold protection control section is set by the limit switch, so it takes time and skill to adjust the mold protection control section, and because of the hydraulic mechanism, the mold protection control section and There is a problem that it is difficult to accurately adjust the mold closing force in the sections before and after that.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and performs mold protection control by reducing the mold closing force of the drive means when the movable mold is closed by the mold closing device. At this time, it is possible to prevent the movable mold from being stopped immediately before the mold contact position due to the frictional force when the guide pin of the fixed mold is inserted into the movable mold, and prevent the mold from being closed.
When a runner or the like is sandwiched between molds, it is intended to reliably detect it and enable the protection of the mold. Another object of the present invention is to solve the problem that adjustment is time-consuming and requires skill during the setting.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and a molding machine according to claim 1 is provided with a mold closing device for reducing the mold closing force and performing mold protection control. In the injection molding machine, the presence or absence of the mold protection end position can be set between the mold protection start position and the mold contact position by inputting from the setting input section, and the setting position is set to Yes. The mold protection end position can be set to any position between the mold protection start position and the mold contact position.

According to a second aspect of the present invention, there is provided a method of controlling a mold closing device, wherein the upper limit of a torque value of a servo motor is limited when a movable mold reaches a mold protection starting position. When the movable mold reaches the mold protection end position set between the mold protection start position and the mold contact position, the upper limit value of the torque value of the servo motor in the mold closing direction may be increased. It is a feature.

According to a third aspect of the present invention, there is provided a method of controlling a mold closing device according to the second aspect, wherein a deceleration start position of the movable mold is provided on a mold opening side from a mold protection start position, and the movable mold is located at the deceleration start position. When it reaches, the servo motor outputs torque in the mold opening direction to decelerate the movable mold, and when the movable mold reaches the mold protection start position, the upper limit of the torque value in the mold closing direction of the servo motor. It is characterized by limiting the value.

According to a fourth aspect of the present invention, there is provided a method of controlling a mold closing device according to the second or third aspect, wherein the mold protection end position can be set within a range of 0 to 2.0 mm from the mold contact position to the mold opening side. It is characterized by being provided in.

According to a fifth aspect of the present invention, there is provided a method of controlling a mold closing device according to any one of the second to fourth aspects, wherein the upper limit value of the torque value between the mold protection end position and the mold contact position is gradually increased. It is characterized by.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic explanatory view of an injection molding machine provided with a mold closing device of the present invention. Figure 2
FIG. 8 is an explanatory view showing the control of the servo motor in the control method of the mold closing device of the present invention. FIG. 3 is a flowchart showing the control method of the mold closing device of the present invention. FIG. 4 is a graph showing the current value of the servo motor and the moving speed of the movable mold regarding the control method of the mold closing device of the present invention.

Reference numeral 1 denotes an injection molding machine according to an embodiment of the present invention, in which a plurality of tie bars 5 are fixed between a fixed platen 3 to which a fixed mold 2 is attached and a support plate 4, and the tie bar 5 is fixed to the tie bar 5. A movable plate 8 to which a movable mold 6 and servo motors 7, 7 are attached is slidably provided.

Servo motors 7 and 7 as mold closing devices are fixed to both sides of a movable platen 8. The servo motors 7 and 7 are provided with ball screws 9 and 9, respectively, and the other ends of the ball screws 9 and 9 are supported. The ball nuts 10, 10 provided on both sides of the board 4 are respectively screwed. Then, by driving the servo motors 7, 7, the movable mold 6 is
The mold can be closed from the mold opening position P0 to the mold contact position P4 with the fixed mold 2.

Further, the mold closing device includes an encoder 11 as position detecting means for detecting the number of rotations of the servo motors 7, 7.
And a control means 12 for controlling the servomotors 7, 7. The encoder 11 is attached to each of the servo motors 7, 7 and outputs the rotation of the servo motors 7, 7 as a rotation angle pulse.
8 to the servo amplifier 20.

The control means 12 connected to the servomotors 7, 7 is composed of a setting input section 13, a display section 14, a storage section 15, a clock section 16, a CPU 17, an output section 18, an input processing section 19 and the like. The two are connected by a bus 21 or the like. The setting input unit 13 is a part for inputting set values of molding conditions such as the mold protection start position P2 and the mold protection end position P3, and is input from the touch panel in this embodiment. However, the setting input unit 13 may be a keyboard of a personal computer, a ten-key board, voice input means, wireless remote input means, or the like. The display unit 14 is a unit for displaying the set value input as described above and the actual molding value, and is a CRT or a liquid crystal panel. In this embodiment, the touch panel is arranged on the surface of the display unit 14. The display unit 14 also includes a printer and the like. The storage unit 15 has a ROM in which an application program is stored and an R for temporarily storing calculation data and the like.
It consists of AM. Alternatively, a memory card or the like storing molding conditions and the like may be inserted and the data may be read.

The clock unit 16 has a timer function and is used for clocking various application program controls. In particular, in this embodiment, in the mold protection control, the movable mold 6 is moved to the mold protection end position P3 by the predetermined time from the position detection of the mold protection start position P2.
Alternatively, time measurement is performed when it is determined that there is an abnormality when the die contact position P4 cannot be reached, or the die protection end position P3.
The timekeeping unit 16 is used when the upper limit of the torque value from is increased over time. The CPU 17 sends a mold closing position command, a mold closing speed command, and a torque command to the servomotors 7, 7 via the output unit 18 based on the application program read from the storage unit 15, and is provided in the servomotor 7. The calculation is performed based on the signal sent from the encoder 11 via the input processing unit 19 and the time measured by the time counting unit 16, and the sequential commands are output.

2 connected to the output section 18 of the control means 12
Reference numeral 0 denotes a servo amplifier, which is composed of three control systems, a position control loop, a speed control loop, and a current control loop, as shown in FIG. Regarding the position control of the movable mold 6 when the mold is closed, a command is issued from the CPU 17, the servo motor 7 is driven via the servo amplifier 20, and the rotation angle pulse output from the encoder 11 which is the position detecting means is used for the position control. Input to the deviation counter 22 via a loop,
The position of the movable mold 6 is controlled by comparing the current values with the current controller 26 through the position controller 23. Then, position control of a mold protection start position P2, a mold protection end position P3, and the like, which will be described later, is performed.

For speed control when the movable mold 6 is closed, a signal for instructing a current value is output from the CPU 17,
The servo motor 7 is driven via the servo amplifier 20,
The rotation angle pulse output from the encoder 11 is input and compared to the speed control unit 24 via the speed loop, and the current value is controlled via the current control unit 26 and the power conversion unit 27 to control the speed of the movable mold 6. Take control. At this time, the speed of the movable mold 6 is not only a command from the CPU 17, but also a load caused by disturbance such as inertia problem of the movable plate 8 or frictional force when the guide pin of the fixed mold 2 is inserted into the movable mold 6. Since it is also affected by, the control is performed while correcting the speed change due to them.

The CPU also controls the torque when the movable mold 6 is closed.
A signal for instructing the current value is output from the servo motor 7
Current value measured by the current measuring unit 28,
Through the current loop, the current control unit 26 compares and controls the current value. Further, in the deceleration section T2 when the mold is closed, the direction of the torque of the servo motor 7 is switched by the speed control unit 24, and the torque is applied in the mold opening direction to perform braking. In the mold protection control section T3, the CPU1
7 sends a torque limit command to the current limiter 25,
The upper limit of the current value sent to the servo motor 7 is limited,
The upper limit of the torque value in the mold closing direction is limited. And, even though the position command pulse is sent from the CPU 17, when there is a foreign substance between the molds and the forward movement of the movable mold 6 is stopped, an excessive torque force of the servo motor 7 acts on the molds,
It prevents the mold from being damaged.

Next, a method of controlling the mold closing device of the present invention will be described. First, the input of the setting value regarding the mold protection control will be described. The setting input is performed from the touch panel of the setting input unit 13 as described above. The setting input is the daylight T, which is the maximum distance from the mold closed position to the mold open position.
In addition to setting 0, the speed of the high-speed mold closing section T1 is set in multiple stages, and the mold protection start position P2, the mold protection end position P3, the mold protection pressure, etc. are input. These set input values can be set depending on the mold used for molding and other molding conditions, but the mold protection end position P3 is 0 mm to 2.0 mm from the mold contact position P4 to the mold opening side. Set to range. Further, it is particularly preferable that the mold protection end position P3 is set in the range of 0.05 mm to 1.0 mm from the mold contact position P4 to the mold opening side. In the above, when the mold protection end position P3 is set to 0 mm from the mold contact position P4 to the mold opening side,
Mold protection control section T3 without providing the mold protection end section T4
Is continued from the mold protection start position P2 to the mold contact position P4.

Further, the mold protection start position P2 is preferably in a range of 10 mm to 20 mm on the mold opening side from the mold contact position P4. The mold protection start position P2 and the mold protection end position P3 are displayed on the display unit 1.
4 and a touch panel for easy monitoring and correction. Further, these set input values are stored in the RAM of the storage unit 15.

The control method of the mold closing device will be described with reference to the flowchart of FIG. 3 and the line graph showing the current value and the torque value of the servo motor 7 in FIG. 4. The servo motor used for this control is from start to end of control. This is continuously performed for the same servo motor 7, 7. In step 1, the CPU 17 outputs a signal instructing the position to the servo amplifier 20 and a signal instructing the current value, the servo motor 7 is energized, and the movable mold 6 and the movable platen 8 at the mold opening position P0 are closed. Start moving in the direction. The speed increasing command to the servo motor 7 is continued until the speed reaches a predetermined speed, and when the speed reaches the predetermined speed, the current value sent from the servo amplifier 20 to the servo motor 7 is reduced, and the movable mold 6 and the like move at a substantially constant speed. Done. For these speed controls, the position control unit 23 and the speed control unit 24 of the servo amplifier 20 constantly monitor the deviation between the position set value and the set speed and the actual measured position and the actual speed, and set the current value so as to approach the set speed. It is done while carrying out the fine adjustment of. Although the high-speed mold closing section T1 is from the mold opening position P0 to the next deceleration start position P1, the speed of the movable mold 6 may be controlled in multiple stages during this period.

In step 2, it is determined whether the movable mold 6 has reached the deceleration start position P1. In this embodiment, the deceleration start position P1 is CP based on the speed of the movable mold 6 and the deceleration rate preset by the tuning data.
In U17, the position is determined by back-calculating from the mold protection start position P2. In step 3, in the deceleration section T2, the torque output in the mold opening direction to the servo motor 7 is counteracted by the inertia of the movable mold 6 in the mold closing direction so that the deceleration rate is preset by the tuning data. By doing so, the movable mold 6 and the like are braked, and the mold protection start position P described below is obtained.
By the time reaching 2, the movable mold 6 is decelerated to the set speed in the mold protection control section T3. The deceleration start position P1 may be set and input, and the deceleration of the movable mold 6 or the like may be started by detecting the deceleration start position P1 by the encoder 11.

In step 4, the mold protection start position P2 is set by the rotation angle pulse output from the encoder 11.
Is detected, in step 5, the servo amplifier 2
An upper limit value is set for the current value sent from 0 to the servo motor 7, and the torque value of the servo motor 7 is limited in the mold closing direction to reduce the current value to the servo motor 7. By the above control, the movable mold 6 moves forward at a low speed in the mold protection control section T3, and the torque value of the servo motor 7 is limited. Therefore, when a foreign object is caught, the torque increases abnormally. Do not damage the die. Further, at the same time when the mold protection start position P2 is detected, the timer which is the time measuring unit 16 starts the time measurement.

In step 7, when the mold protection end position P3 is detected by the rotation angle pulse from the encoder 11 before the timer measures a predetermined time, foreign matter is detected in the mold protection control section T3. The CPU 17 determines that there is no pinching or the like, and proceeds to the next step 8. Further, in step 6, even though the timer clocked a predetermined time, the rotation angle pulse from the encoder 11 did not match the command pulse, leaving a pool pulse,
When the time is up, the CPU 17 determines that there is a foreign substance trapped in the mold protection control section T3, stops the control of the servo motor 7, and displays an alarm. It should be noted that when foreign matter is caught, the servo motor 7 may be controlled to move in the mold opening direction without being stopped.

In step 8, when it is detected that the movable mold 6 has reached the mold protection end position P3 by the rotation angle pulse output from the encoder 11, the CPU
17 outputs a command to the servo amplifier 20 to increase the upper limit value of the torque value of the servo motor 7 in the mold closing direction,
The mold protection control section T3 ends. This is because, as described above, stopping of the movable mold 6 due to friction with the guide pin occurs frequently immediately before the mold contact position P4. Although the upper limit value of the torque value in the mold closing direction is set also in the mold protection end section T4, it is increased to the upper limit value of the torque value larger than that in the mold protection control section T3. In this embodiment, the upper limit value of the torque value is gradually controlled to increase linearly or curvedly from the mold protection end position P3 over time.

This is because when the movable mold 6 increases the frictional force between the movable mold 6 and the fixed mold 2 and the servo motor 7 decelerates or stops, the upper limit of the torque value is controlled to increase stepwise. The torque value in the closing direction suddenly rises to overcome the frictional force, the movable mold 6 is rapidly moved, and the fixed mold 2 is moved.
This is because there is a risk of colliding with and damaging the mold.
Therefore, as described above, the upper limit value of the torque value is gradually increased in a linear or curved manner as time elapses, whereby the torque is gradually increased with respect to the frictional force between the movable mold 6 and the fixed mold 2. And apply a mold closing force,
The movable mold 6 can be moved smoothly. Note that the gradual increase control of the upper limit value of the torque value may be made to increase in a quadratic function curve or in small steps in multiple steps over time.

In step 9, whether or not the movable mold 6 has reached the mold contact position P4 is detected by the rotation angle pulse output from the encoder 11. Then, in step 10, the accumulated pulse becomes 0 in the deviation counter 22, the movable mold 6 reaches the mold contact position P4, and when it is confirmed that the molds are in close contact with each other, the CPU 17 servos the servo amplifier 20. A command for releasing the torque limitation of the motor 7 is output, and then the mold clamping is performed.

Further, in this embodiment, the mold closing device of the electric injection molding machine in which the servomotors 7, 7 are fixed to both sides of the movable platen 8 has been described, but the servomotor 7 is used as the movable platen 8 or the support platen 4. The mold closing device may use a toggle mechanism. Further, in this embodiment, it is judged as abnormal when the die protection end position P3 cannot be detected when the timer measures a predetermined time, but the mold contact position P4 is determined when the timer measures a predetermined time. It may be determined to be abnormal when it cannot be detected.

Furthermore, even with a mold closing device using a hydraulic mechanism, it is possible to arbitrarily set the mold protection start position and the mold protection end position. Even in the case of a hydraulic mechanism, by setting the input from the touch panel etc., the mold protection end position is provided between the mold protection start position and the mold contact position by a simple input, and the hydraulic pressure is gradually increased from the mold protection end position. Can be made. As the control in that case, an encoder for detecting the position of the movable platen 8 is provided, and when the encoder detects the die protection end position, a servo valve for controlling the hydraulic pressure of the booster ram is controlled by the control means for controlling the hydraulic mechanism. It is provided so that the hydraulic pressure can be gradually increased by controlling. Further, in these controls, the mold protection start position, the mold protection end position, etc. may be automatically corrected in accordance with the thermal expansion of the movable mold 6 and the fixed mold 2.

[0031]

INDUSTRIAL APPLICABILITY The present invention is an injection molding machine provided with a mold closing device for performing mold protection control, and a mold is inserted between a mold protection start position and a mold contact position by inputting from a setting input section. The presence or absence of the mold protection end position can be set, and when setting the mold protection end position to Yes, the setting position can be changed arbitrarily, so the guide pin of the fixed mold is inserted into the movable mold. The frictional force at this time is large and the movable mold stops immediately before the mold abutting position to prevent the mold from being closed. When it is pinched, it can be reliably detected and the mold can be protected. Further, it does not require time for adjustment when setting the mold protection control section, and even an unskilled person can easily perform the adjustment.

Further, in the method of controlling the mold closing device using the servo motor, when the movable mold reaches the mold protection end position provided between the mold protection start position and the mold contact position, the mold is closed. By increasing the upper limit of the torque value in the protection control section, while preventing the problem that the movable mold stops just before the mold contact position, when the runner etc. is sandwiched between the molds It is now possible to detect it reliably and protect the mold.

In the method of controlling the mold closing device using the servo motor, the deceleration position of the movable mold is provided on the mold opening side from the mold protection start position, and the torque output in the mold opening direction by the servo motor. After decelerating the movable mold, when the movable mold reaches the mold protection start position, the upper limit of the torque value in the mold closing direction of the servo motor is limited, so no complicated mechanism is required. , It became possible to start the mold protection after the movable mold was rapidly decelerated to the mold protection start position. And while preventing the problem that the movable mold stops just before the mold contact position, it is possible to reliably detect when a runner etc. is sandwiched between the molds and protect the mold. Became.

In the method of controlling the mold closing device using the servomotor, the mold protection end position is set so that it can be set in the range of 0 to 2.0 mm from the mold contact position to the mold opening side. Therefore, it is possible to freely set the presence or absence of the mold protection end position, and while preventing the problem that the movable mold that occurs depending on the mold stops just before the mold contact position, the runner etc. When it is sandwiched between molds, it can be reliably detected and the mold can be protected.

Further, when the upper limit value of the torque value from the die protection end position to the die abutment position is controlled to be gradually increased, when the movable die is decelerated or stopped by the frictional force with the fixed die. After that, since the torque value of the servo motor in the mold closing direction is gradually increased and the mold closing force gradually overcomes the frictional force to smoothly move the movable mold,
There is no risk of the movable mold colliding with the fixed mold and damaging the mold.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an injection molding machine provided with a mold closing device of the present invention.

FIG. 2 is an explanatory diagram showing control of a servomotor of the mold closing device of the present invention.

FIG. 3 is a flowchart showing a control method of the mold closing device of the present invention.

FIG. 4 is a graph showing a current value of a servo motor and a moving speed of a movable mold regarding a control method of a mold closing device of the present invention.

[Explanation of symbols]

1 ……… Injection molding machine 2 ……… Fixed mold 3 ……… Fixed plate 4 ………… Supporting board 5 ………… Tie bar 6 ... Movable mold 7 ……… Servo motor 8 ……… Movable plate 9 ……… Ball screw 10 ... Ball nut 11 ... Encoder 12 ... Control means 13 ... Setting input section 14 ... Display 15 ... Memory 16 …… Timekeeping section 17 ... CPU 18 ... Output section 19 …… Input processing unit 20 ... Servo amplifier 21 …… Bus 22 ... Deviation counter 23 ... Position control unit 24 …… Speed control unit 25 …… Current limiter 26 …… Current control unit 27 …… Power converter 28 …… Current measurement section P0 ... Mold open position P1 ...... Deceleration start position P2 …… Mold protection start position P3 …… Mold protection end position P4 ...... Mold contact position T0 …… Daylight T1 ...... High speed type closed section T2: Deceleration section T3 …… Mold protection control section T4 …… Mold protection end section

Claims (5)

[Claims] 1. A drive means for moving a movable mold from a mold open position toward a mold contact position, and position detection means for detecting a position of the movable mold, wherein the movable mold is a mold protection start position. In the injection molding machine provided with a mold closing device that reduces the mold closing force by the driving means to perform mold protection control, the presence or absence of the mold protection end position can be freely set by a signal from the setting input section. At the same time, when the mold protection end position is set to be provided, the mold protection end position is provided so that it can be arbitrarily set between the mold protection start position and the mold contact position by a signal from the setting input section. An injection molding machine characterized by that. 2. A mold closing device comprising a servo motor for moving a movable mold from a mold open position toward a mold contact position, control means for controlling the servo motor, and position detecting means for detecting the position of the movable mold. When the movable mold reaches the set mold protection start position, the upper limit of the torque value of the servo motor in the mold closing direction is limited to perform mold protection control. A mold characterized by increasing the upper limit of the torque value in the mold closing direction of the servo motor when the movable mold reaches the mold protection end position set between the protection start position and the mold contact position. Control method for closing device. 3. A deceleration start position of the movable mold is provided on the mold opening side from the mold protection start position, and when the movable mold reaches the deceleration start position, the torque output in the mold opening direction of the servo motor is performed. 3. The upper limit of the torque value of the servo motor in the mold closing direction is limited when the movable mold reaches the mold protection start position after decelerating the movable mold.
A method for controlling the mold closing device according to. 4. The mold protection end position is provided so that it can be set in a range of 0 to 2.0 mm from the mold contact position to the mold opening side, according to claim 2 or claim 3. Control method of mold closing device. 5. The control of the mold closing device according to claim 2, wherein the upper limit value of the torque value from the mold protection end position to the mold contact position is gradually increased. Method.