JPH0767723B2 - Mold protection control device for injection molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric injection molding machine, and more particularly to an injection molding machine suitable for surely detecting the presence or absence of residual foreign matter in a mold and preventing damage to the mold. A mold protection control device.

[0002]

2. Description of the Related Art Conventionally, low pressure mold protection control is performed because if the mold is closed and a mold clamping pressure is applied when foreign matter remains in the mold of an injection molding machine, the mold is damaged. In this case, the low-pressure mold protection control method for the electric injection molding machine is to control the torque limiter (torque transmission limiter) of the mold opening / closing servo motor that drives the mold opening / closing mechanism, thereby controlling the mold opening / closing servo motor. In addition to controlling the torque value by controlling the current value at the same time, at the same time, the fact that foreign matter remains in the mold is determined based on whether the time measured by the alarm timer for protecting the low-pressure mold has reached a preset predetermined time. It is judged whether or not to issue the alarm. Here, the relationship between the low-pressure mold protection range and the mold closing side torque set value of the mold opening / closing servomotor in the conventional example is as shown in FIG. That is,
During the low-pressure mold protection range (when the low-metal mold start limit switch E16 is operating to when the high-voltage return limit switch E15 is operating) while the low-voltage mold is closed, the torque on the mold closing side in the mold opening / closing servomotor ( (Mold closing force) is controlled to a set value, and when the high pressure return limit switch E15 is turned on while the time T is being measured by the alarm timer for protecting the low pressure mold, the foreign matter is contained in the low pressure mold. On the other hand, if the alarm timer counts time before the high pressure return limit switch E15 is turned on, it is determined that the low pressure die protection detection has been activated. .

[0003]

However, in the above-mentioned conventional electric injection molding machine, a low-pressure mold protection control method for determining the presence or absence of low-pressure mold protection detection by an alarm timer includes a servo motor for mold opening and closing. Torque ripple occurs, the torque current value of the mold opening / closing servo motor changes due to temperature changes, and the motor current value (for torque current control) and the ball screw of the mold opening / closing servo motor vary depending on the ball screw characteristics of the mold mechanism. Hysteresis is generated in the thrust (low gold force), and there is a defect that the low gold force cannot be precisely controlled due to various reasons.

The present invention has been made to solve the above-mentioned problems, and the foreign matter in the mold is detected based on the accumulated pulse amount of the servo motor for opening and closing the mold without detecting the alarm for protecting the low-pressure mold by the alarm timer as in the prior art. By accurately detecting the presence or absence of residue and issuing an alarm based on the detection result, it is possible to perform precise control with low metal power, and also to prevent damage to the mold. It is an object of the present invention to provide a mold protection control device of.

[0005]

In an injection molding machine comprising a mold opening / closing servomotor for opening / closing a mold, and a position / speed detector for detecting the position / speed of the mold opening / closing servomotor. Input means for inputting a drive command value for the mold opening / closing servomotor, alarm means for warning that foreign matter remains in the mold, and a criterion for determining whether or not foreign matter remains in the mold. Alarm setting means for setting the upper limit alarm pool pulse amount, and the die opening / closing operation based on the drive command value of the die opening / closing servomotor input from the input means and the feedback value output from the position / speed detector. The deviation calculation means for calculating the amount of droop pulses of the servo motor, the present value of the amount of droop pulses of the mold opening / closing servo motor calculated by the deviation calculation means, and the alarm setting means are set. Limit alarm pool pulse amount, and when the current value of pool pulse amount of the mold opening / closing servomotor reaches the upper limit alarm pool pulse amount or more, foreign matter remains in the mold from the alarm means. A comparison control means for generating a warning to that effect and repeating the comparison when the warning is not reached is provided.

[0006]

According to the present invention, the accumulated pulse amount of the mold opening / closing motor is obtained based on the drive command value of the mold opening / closing servomotor and the feedback value output from the position / speed detector.
Repeatedly comparing the current value with the upper limit accumulated pulse amount,
Since an alarm is issued when the upper limit accumulated pulse value is reached, it is no longer necessary to detect the alarm generation time with an alarm timer for low pressure mold protection as in the past, and as a result, the torque ripple of the mold opening / closing servo motor and the temperature It is possible to prevent variations in low gold sensitivity due to changes in torque current value, occurrence of hysteresis in ball screw thrust and servo motor current value.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram of the injection molding machine of the present embodiment. A mold control system of the injection molding machine includes a mold opening / closing servo motor 1 for driving a mold opening / closing mechanism, and an AC servo amplifier 2.
And a controller 3. The mold opening / closing servomotor 1 includes a motor body 4 and the motor body 4
A position / velocity detector (PLG) 5 attached to an end portion is provided, and the AC servo amplifier 2 includes a position command unit 6, a deviation counter 7, a servo amplifier unit 8 and an interface unit 9.
And the controller 3 includes the sequence unit 1
0, an arithmetic unit 11, a comparator 12, and an output unit 13 are provided. Further, the injection molding machine includes an input / output unit (limit switch, lamp, push button, etc.) 14, an alarm setting device 1
5, an alarm device 16 and a drooping pulse number display device 17 are provided.

The input / output section 14 arranged in the injection molding machine.
When an operation signal is output from the sequencer 10 to the calculation unit 11 via the sequence unit 10, the calculation unit 11 causes the mold opening / closing servomotor 1 to operate.
Is output to the position command unit 6 of the AC servo amplifier unit 2. The position command unit 6 outputs the amount of movement with respect to the mold opening / closing servomotor 1 to the deviation counter 7 based on the position command value output from the calculation unit 11. The deviation counter 7 is the position command unit 6
The deviation between the movement amount output from the position and the position feedback value output from the position / speed detector 5 is calculated, and the droop pulse (droop pulse amount = command pulse amount−driving pulse amount) is set to the speed command point 18 and droop pulse. Number display 17 and comparator 12
And output to and respectively. At the speed command point 18, a speed command is generated based on the droop pulse output from the deviation counter 7 and the speed feedback value output from the position / speed detector 5 via the interface unit 9, and the speed command is servo-controlled. After being output to the amplifier unit 8, the speed command amplified by the servo amplifier unit 8 is output to the motor body 4 of the die opening / closing servomotor 1. As a result, the motor body 4 of the mold opening / closing servomotor 1 is driven based on the speed command.

On the other hand, the comparator 12 of the controller 3 outputs the upper limit alarm pool pulse value, which is a guideline for alarm generation, from the alarm setter 15 and outputs the pool pulse of the mold opening / closing servomotor 1 from the deviation counter 7. When output, the upper limit alarm droop pulse value is compared with the droop pulse, and a signal based on the comparison result is output to the output unit 13. When the droop pulse of the mold opening / closing servomotor 1 reaches the upper limit alarm droop pulse value, the alarm unit 1 is output from the output unit 13.
As a result of outputting the alarm signal to 6, the alarm device 16 outputs an alarm indicating that the low-pressure mold protection is abnormal. Further, the droop pulse number display 17 is adapted to display the droop pulse number based on the droop pulse of the die opening / closing servomotor 1 output from the deviation counter 7. In the injection molding machine of this embodiment, the relationship between the command pulse for driving the servo motor 1 for opening and closing the mold and the feedback pulse generated from the position / speed detector 5 by the rotation of the servo motor 1 is related. Based on the equation: accumulated pulse amount = command pulse amount-driving pulse amount, the accumulated pulse amount of the mold opening / closing servomotor 1 is used to detect the presence / absence of foreign matter remaining in the mold.

Next, the control for detecting the presence / absence of foreign matter remaining in the mold by the mold protection control device of the injection molding machine of the present embodiment having the above-mentioned structure will be described with reference to FIGS.

When no foreign matter remains in the mold. When the mold closing signal corresponding to the mold closing speed is output from the input / output unit 14 of the controller 3 to the calculating unit 11 via the sequence unit 10, the calculating unit 10 outputs the position command value corresponding to the mold closing speed to the AC servo. As a result of the output to the position command unit 6 of the amplifier 2, the position command unit 6 outputs the movement amount corresponding to the mold closing speed to the deviation counter 7. The deviation counter 7 outputs the droop pulse of the mold opening / closing servomotor 1 to the speed command point 18 based on the amount of movement from the position command unit 6 and the position feedback value from the position speed detector 5, and at the speed command point 18, A mold closing speed command is output to the motor body 4 of the mold opening / closing servomotor 1 via the servo amplifier unit 8 based on the droop pulse and the speed feedback value. As a result, the mold opening / closing servomotor 1 performs the mold closing operation based on the mold closing speed command. On the other hand, from the position / speed detector 5 attached to the end of the motor body 4 of the mold opening / closing servomotor 1, the position feedback value is sent to the deviation counter 7, and the speed feedback value is sent to the speed command point 18 via the interface unit 9. As a result of being returned, the amount of accumulated pulses of the mold opening / closing servomotor 1 is controlled at a predetermined value or less, although it depends on the control response speed during the motor position control. At this time, the accumulated pulse number display 17
In the field, the number of droop pulses corresponding to the droop pulse amount of the mold opening / closing servomotor 1 controlled at the predetermined value or less is displayed.

When foreign matter remains in the mold. If foreign matter remains in the mold, the mold closing operation becomes impossible, and the position feedback value deviates from the position / speed detector 5 attached to the end of the motor body 4 of the mold opening / closing servomotor 1. Since the speed feedback value to the counter 7 does not return to the speed command point 18, the accumulated pulse amount of the mold opening / closing servomotor 1 becomes a large value exceeding a predetermined value. At this time, the droop pulse number display 17 displays the droop pulse number corresponding to the droop pulse amount of the mold opening / closing servomotor 1 exceeding the predetermined value. In this case, the alarm setter 15
Therefore, when the upper limit alarm pool pulse amount for alarm generation corresponding to the upper limit value of the pool pulse amount is preset, the comparator 12 of the controller 3 causes the deviation from the upper limit alarm pool pulse output from the alarm setter 15. When the droop pulse of the mold opening / closing servomotor 1 output from the counter 7 is compared and it is determined that the droop pulse of the mold opening / closing servomotor 1 has reached the upper limit alarm droop pulse, an alarm device is output via the output unit 13. An alarm is output from 16 indicating that foreign matter remains in the mold. Thereby, the alarm for protecting the low-pressure mold can be accurately generated. Here, the relationship between the low-pressure mold protection range and the mold closing-side torque set value in this embodiment is as shown in FIG. Further, the droop pulse upper limit alarm amount setting unit in the present embodiment is, for example, an arrow A in FIG. 3, and the current value of the droop pulse amount of the mold opening / closing servomotor 1 which is currently being controlled is shown in FIG.
When the relational expression that the accumulated pulse upper limit alarm amount setting unit ≦ current value of accumulated pulse amount is satisfied, the low pressure die protection alarm is generated. Each numerical value in FIG. 3 is an example, and is not limited to the numerical value.

Next, the flow of the low pressure die protection control in the injection molding machine of this embodiment will be described with reference to FIG. After starting the low-pressure mold protection control, the controller 3 determines whether or not the low-gold mold is in operation (step S1). When it is determined, the comparator 12 of the controller 3 reads the number of accumulated pulses of the mold opening / closing servomotor 1 output from the deviation counter 7 of the AC servo amplifier 2 (step S2). After that, the comparator 12 determines whether or not the accumulated pulse number of the mold opening / closing servomotor 1 exceeds the set pulse number (corresponding to the upper limit alarm accumulated pulse amount) (step S3), and the set pulse number is exceeded. If it is determined that it is not, the process returns to step S1. If it is determined that the set number of pulses is exceeded, the alarm device 16 outputs an alarm indicating that the low-pressure mold protection is abnormal (step S4). The low-pressure mold protection control ends.

[0014]

As described above, according to the present invention,
The effects of the following items are achieved. The presence / absence of foreign matter in the mold is detected based on the accumulated pulse amount of the servo motor for mold opening / closing, so that the presence / absence of foreign matter in the mold can be reliably detected and the damage to the mold is prevented. Protection can be achieved. Due to the above, it is not necessary to detect the alarm generation time point by the alarm timer for protecting the low pressure mold as in the conventional case,
The defect that torque ripple occurs in the mold opening / closing servo motor as in the past, the defect that the torque current value changes with temperature,
Due to the characteristics of the ball screw, it is possible to prevent variations in low gold sensitivity caused by defects such as hysteresis occurring in the thrust of the ball screw and the current value of the servo motor. Since the current value of the accumulated pulse and the upper limit pulse alarm accumulated pulse amount are repeatedly compared during the operation of the die, the operation should be stopped immediately by detecting foreign matter, etc., even during the movement stroke of the die. You can

[Brief description of drawings]

FIG. 1 is a control block diagram of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a low pressure mold protection range and a mold closing side torque set value of the injection molding machine of the present embodiment.

FIG. 3 is a diagram showing an example of a droop pulse upper limit alarm amount setting unit of the present embodiment and a current value of a droop pulse amount currently under control.

FIG. 4 is a flowchart of low-pressure mold protection control of this embodiment.

FIG. 5 is a diagram showing a relationship between a low-pressure mold protection range of a conventional injection molding machine and a mold closing side torque set value.

[Explanation of symbols]

 1 Type Servo Motor for Opening / Closing 2 AC Servo Amplifier 3 Controller 5 Position / Speed Detector 7 Deviation Counter (Deviation Calculator) 11 Calculator 12 Comparator (Comparison Control Means) 14 Input / Output (Input Means) 15 Alarm Setting Device (Alarm) Setting device) 16 Alarm device (alarm device) 17 Drooping pulse number display

Claims (1)

[Claims] 1. An injection molding machine comprising: a mold opening / closing servomotor for opening / closing a mold; and a position / speed detector for detecting the position / speed of the mold opening / closing servomotor. Means for inputting the drive command value of the servo motor for use, an alarm means for alarming that foreign matter remains in the mold, and an upper limit alarm pool serving as a criterion for determining whether or not foreign matter remains in the mold. Based on the alarm setting means for setting the pulse amount, the drive command value of the mold opening / closing servo motor input from the input means and the feedback value output from the position / speed detector, the pool of the mold opening / closing servo motor a deviation calculating means for calculating the pulse amount, the upper limit alarm reservoir set by the current value and the alarm setting means accumulated pulses of the type opening and closing servo motor calculated by said deviation calculation means It compares the pulse volume, alarm when the current value of accumulated pulses of the servo motor for the mold closing has reached above the upper limit alarm droop pulse amount indicating remaining foreign material into the mold from the alarm unit When it does not reach
And a comparison control unit that repeats the comparison, and a die protection control device for an injection molding machine.