JP3582722B2 - Drive control device and drive control method for injection molding machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drive control device and a drive control method when a screw is synchronously driven by two or more servomotors, particularly, but not limited to, components of an injection molding machine.
[0002]
[Prior art]
As is well known in the art, the electric injection molding machine includes a heating cylinder, a screw that is driven to rotate in the heating cylinder and is driven in the axial direction, an electric motor that drives the screw, and the like. . Therefore, when the screw is rotated by an electric motor to plasticize and measure the resin material, and the screw is driven in the axial direction, the measured molten resin is injected into the cavity of the clamped mold to cool and solidify. When the mold is opened after waiting, a molded product having a desired shape is obtained.
By the way, a servomotor whose position, speed, torque and the like can be easily controlled is applied to the electric motor as described above, but a plurality of servomotors are used for a large injection machine. This is a drive system for the purpose of meeting the output limit of the ball screw, simplifying the drive mechanism, preventing acceleration performance deterioration, etc., but the drive control of an injection molding machine that controls such a plurality of servomotors An apparatus has been proposed, for example, in Japanese Patent Application Laid-Open No. H11-28751.
[0003]
As shown in FIG. 3, the drive control device for an injection molding machine proposed by the above publication includes an operation instructing means 60, a master servo amplifier 62, a slave servo amplifier 64, a master servo motor 66, and a slave servo motor 68. Etc. A belt 74 is wrapped around the output shafts of the master servomotor 66 and the slave servomotor 68 and mechanically connected to each other, so that the simultaneousness of the torque between the servomotors 66 and 68 is ensured. 3 is a screw, 76a is a feed screw mechanically connected to the output shaft of the master servomotor 66, and 76b is mechanically connected to the output shaft of the slave servomotor 68. The reference numeral 78 designates a driving member which is screwed into these feed screws 76a and 76b to drive the screw 70 in the axial direction, and 72 designates a heating cylinder. Therefore, when the plasticizing signal is output by the operation instructing means 60, the screw 70 is rotationally driven by a motor (not shown), the resin material is plasticized, and the resin material is measured at the tip of the heating cylinder 72. Next, an injection signal is output from the operation instruction means 60 to the master servo amplifier 62. Then, the molten resin is injected into the mold 80 as described in page 13, column 7, lines 13 to 36 of JP-A-11-28751. As a result, a molded product can be obtained as conventionally known.
[0004]
As described above, in the drive control device of the conventional injection molding machine, since the master servo amplifier 62 outputs the torque command signal to the slave servo amplifier 64 and the slave servomotor 68 is torque-controlled, disturbance The advantage that stable and stable control is performed is recognized. Further, since the master servo amplifier 62 and the slave servo amplifier 64 operate in synchronization with the synchronization signal, the drive timings can be matched, and even if there are a plurality of servomotors, the effect of stable control can be further achieved. Since the slave servo amplifier 64 controls the torque of the slave servomotor 68, the capacity of the master servomotor 66 and the capacity of the slave servomotor 68 do not need to match, which increases the degree of freedom in device design. The advantage is also recognized.
[0005]
[Problems to be solved by the invention]
However, in the related art, for example, since the slave servomotor 68 is controlled only by the torque control, the operations of the master servomotor 66 and the slave servomotor 68, that is, the simultaneousness of the thrust and the movement amount are not synchronized with the torque generation. It is guaranteed by the process.
Therefore, the belt connecting the output shaft of the master servomotor 66 or the output shaft of the slave servomotor 68 to the feed screws 76a, 76b for driving the screw 70 of the injection molding machine is elongated, and the mechanical frictional force of each part is not uniform. In this case, the rotation amounts of the master servomotor 66 and the slave servomotor 68 are not always guaranteed. Therefore, in the drive control device of the conventional injection molding machine, the output shaft of the master servomotor 66 and the output shaft of the slave servomotor 68 are wound around the belt 74 to be integrated, whereby the master servomotor 66 The synchronization of the rotation amount of the slave servo motor 68, the movement amount of the feed screw, and the like is temporarily ensured.
[0006]
However, it is necessary to pay attention to the tension relationship between the output shaft of the master servomotor 66 or the output shaft of the slave servomotor 68 and the belts wound around the feed screws 76a and 76b, and there is a problem of maintenance. . In addition, since no special measures have been taken against belt aging, there is also a problem in this respect. Further, since the belt 74 must be provided between the output shaft of the master servomotor 66 and the output shaft of the slave servomotor 68, the driving mechanism becomes complicated and the cost is expected to increase.
[0007]
For this reason, the applicant has eliminated the belt 74 and realized the function of the belt 74 by software by applying a control algorithm, thereby simplifying the drive mechanism and operating the plurality of feed screws (thrust and thrust). The invention of a control device and a method of an injection molding machine capable of ensuring the simultaneity of the amount of movement and further monitoring the degree of aging has already been filed. Basically, torque is controlled, and a drive device such as a feed screw mechanism having relatively large static friction has a problem that it is difficult to control at a low speed or at a stop.
[0008]
An object of the present invention is to provide a drive control device and a control method for an injection molding machine that solve the conventional problems as described above, and specifically, the operation of a plurality of servomotors, for example, the operation of an injection molding machine. The simultaneousness of the thrust and the movement amount of the ball screw is secured, and the structure of the mechanical power transmission mechanism between these servo motors and the components of the injection molding machine, for example, the screw is simplified. It is an object of the present invention to provide a drive control device and method for an injection molding machine that are less susceptible to nonlinear friction.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention relates to an injection molding machine that drives at least two motors (10, 12) configured in a master-slave relationship to drive a movable portion of the injection molding machine. In the drive control device, a speed detecting means (11, 36, 13, 46) for detecting a speed of a drive shaft of the at least two motors (10, 12) and a speed detected by the speed detecting means are provided. A speed controller (32, 38) that forms a drive control signal for each of the motors (10, 12) based on the comparison result; and a speed controller corresponding to each of the motors. by feeding back the comparison result of the output to the speed controller for motor in accordance relation of the at least two motors, the motors are in a relationship of the sub The Configure speed changing means (44, 45) for changing the output value of the speed controller, a torque tuner which performs torque tuning of the at least two motors (45), said at least two motors (10, 12) Position detecting means (11, 35, 13, 41) for detecting the position of the drive shaft of the motor, and position synchronization based on a comparison result of the positions of the drive shafts of the at least two motors detected by the position detecting means. A position controller (43) for generating a signal and synchronizing the position of the at least two motors in addition to the drive control signals of the subordinate motors of the at least two motors. I do.
[0010]
Further, in the drive control device for an injection molding machine of the present invention, the at least two motors (10, 12) apply thrust to the movable portion by a feed screw mechanism .
[0011]
In the drive control device for an injection molding machine according to the present invention, the movable portion is a slide plate (26) provided with a screw of the injection molding machine .
[0012]
The present invention also relates to a drive control method for an injection molding machine, wherein at least two motors (10, 12) configured in a master and slave relationship are driven to drive a movable part of the injection molding machine. The speed of the drive shaft of at least two motors (10, 12) is detected, the detected speed is compared with a given speed command, and the drive control of each of the motors (10, 12) is performed based on the comparison result. Forming a signal, comparing the drive control signals corresponding to each of the motors, and feeding back the comparison result for forming the drive control signals for a subordinate one of the at least two motors. in, and change the drive control signal as a speed control value for the motor in a relationship of the sub, the perform at least torque tuning of the two motors, the small Both detects the position of the drive shaft of the two motors (10, 12), follow one of the above forms a position synchronization signal based on the comparison result of the position of at least two of the motor drive shaft at least two motors And the position synchronization of the at least two motors is performed in addition to the drive control signals of the motors having the following relationship.
[0014]
In the above-described configuration, by controlling the drive axes of a plurality of motors to coincide, for example, by position control, the positions of the motors can be matched without a synchronous belt in the related art. In addition, each motor is provided with a speed control loop, the output torque of each motor is compared, and a feedback process is performed to correct the difference, thereby preventing the output torque of each shaft from becoming unbalanced. In addition, the influence of the non-linear friction at the time of stopping and at the time of low speed can be canceled, and the synchronization accuracy can be improved.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. As shown in FIG. 1, in the present embodiment, the movable part of the injection molding machine is a slide plate 26 to which a screw 21 is attached, and two servo motors 10 and 12 for driving the screw 21 in the axial direction. Examples will be described. The control device according to the present embodiment includes a command generation controller 1, a servo controller 2, a master voltage source inverter 3, a slave voltage source inverter 4, and the like. The command generation controller 1 is connected to the servo controller 2 via a signal line a, and signals relating to the driving direction of the screw 21, the injection speed, the injection pressure, the back pressure during plasticization, and the like are input to the servo controller 2. ing. The servo controller 2 and the master voltage source inverter 3 are connected by a signal line b, and an operation value calculated by the servo controller 2 is input to the master voltage source inverter 3, and the frequency, voltage amplitude, and An AC voltage having a variable phase is obtained. The power is supplied to the master servomotor 10 via the first power line E1. Similarly, the servo controller 2 and the slave voltage source inverter 4 are connected by a signal line c, and the operation value calculated by the servo controller 2 is input to the master voltage source inverter 4, and the voltage in the master voltage source inverter 4 is variable. AC voltage can be obtained. Then, the power is supplied to the slave servomotor 12 via the second power line E2.
[0016]
A master pulse generator 11 is provided in association with master servomotor 10. The master pulse generator 11 and the servo controller 2 are connected by a signal line d, and the position or movement of the first ball screw 22 driven by the master servomotor 10 according to the position or rotation speed of the master servomotor 10 by the master pulse generator 11. The speed is input to the servo controller 2. A slave pulse generator 13 is provided in association with the slave servomotor 12. The slave pulse generator 13 and the servo controller 2 are connected by a signal line e. As a result, the position or moving speed of the second ball screw 24 driven by the slave servomotor 12 according to the position or rotational speed of the slave servomotor 12 by the slave pulse generator 13 is input to the servo controller 2. A first current sensor 5 is provided on the first power line E1, and a second current sensor 6 is provided on the second power line E2. The currents measured by these current sensors 5, 6 are respectively provided. The values are input to the servo controller 2 through the respective signal lines f and g.
[0017]
Since the injection molding machine itself is conventionally known, only the heating cylinder 20 and the screw 21 provided in the heating cylinder 20 so as to be driven in the rotation direction and the axial direction are shown in FIG. It is shown. In this embodiment, the screw 21 is driven in the axial direction by two servo motors, a master servo motor 10 and a slave servo motor 12, to synchronize a predetermined injection speed, holding pressure, back pressure during plasticization, and the like. Is given. A drive pulley 14 is mounted on the output shaft of the master servomotor 10, and a driven pulley 15 is mounted on the first ball screw 22. A first timing belt 16 is wound between these pulleys 14 and 15. Have been. Similarly, a drive pulley 17 is attached to the output shaft of the slave servomotor 12, and a driven pulley 18 is attached to the second ball screw 24, and a second timing belt 19 is provided between these pulleys 17 and 18. Is being wrapped around. A first ball nut 23 is screwed into the first ball screw 22, and a second ball nut 25 is screwed into the second ball screw 24. The first and second ball nuts 23 and 25 are fixed to a slide plate 26 that moves in the axial direction but is restricted in the rotation direction. Therefore, when the first and second ball screws 22 and 24 are driven to rotate, the first and second ball nuts 23 and 25 cannot rotate but move in the axial direction. Thereby, the slide plate 26 is driven in the axial direction. The start end of the screw 21 is attached to the slide plate 26 driven in the axial direction in this way via the pressure sensor 27. A pressure signal such as an injection pressure, a holding pressure, and a back pressure measured by the pressure sensor 27 is input to the servo controller 2 through a signal line h. The motor that drives the screw 21 in the rotational direction, that is, the plasticizing direction, is not shown in FIG.
[0018]
Next, the operation of the embodiment shown in FIG. 1 will be described. A speed command value, a position command value, or a pressure command value which is a basic operation of the screw 21 from the command generation controller 1, for example, a retreat speed of the screw 21 when the screw 21 is rotationally driven and plasticized, a retreat position, that is, a weighing position, Various command values such as the back pressure value at the time, the injection speed at the time of injecting the measured molten resin, the injection pressure, and the holding pressure after the injection are output to the servo controller 2 via the signal line a.
On the other hand, the movement speed and the position of the first ball screw 22 are input to the servo controller 2 via the signal line d as the feedback amount according to the rotation speed and the position of the master servomotor 10 measured by the master pulse generator 11. Further, the pressure of the screw 21 measured by the pressure sensor 27 is also input as a feedback amount. Further, a current flowing through the first power line E1 is measured by the first current sensor 5, and is similarly input to the servo controller 2 via the signal line f as a feedback amount. The servo controller 2 calculates based on the deviation obtained from the command value from the command generation controller 1 and the measured feedback amount, and outputs the calculated value to the master voltage type inverter 3 via the signal line b. An AC voltage is obtained in the master voltage source inverter 3 and supplied to the master servomotor 10 via the first power line E1. As a result, the feedback control of the master servomotor 10 is performed so that the command value is output from the command generation controller 1.
[0019]
The slave servomotor 12 is similarly controlled. However, the rotational speed of the second ball screw 24 driven by the slave servomotor 12, that is, the axial position and thrust, is controlled by the first servomotor 10 driven by the master servomotor 10. Is controlled so as to match the axial position of the ball screw 22 and the thrust. As a result, the screw 21 is driven by one common slide plate 26 in synchronization with the axial direction.
[0020]
As described above, in the servo controller 2, the signal calculated so that the axial position and the thrust of the second ball screw 24 match the axial position and the thrust of the first ball screw 22, respectively. Although the servomotor 12 is controlled, a block diagram of a control device in the servo controller when the command signal output from the command generation controller 1 to the servo controller 2 is a speed command signal is shown in FIG. .
[0021]
2, the same elements as those shown in FIG. 1 are denoted by the same reference numerals and will not be described repeatedly. However, the control device according to the present embodiment includes a master servo motor drive control unit and a slave servo motor. And a drive control unit.
The master servomotor drive control unit adds a speed controller 32 to which a speed command is input via a first adder 31 and an output of the speed controller 32 with a feedback current from the current sensor 5 by a second adder 33. A current controller 34 that outputs a control current to the master voltage type inverter 3 and a position signal processor 35 that outputs a position signal from a signal (master speed FB (feedback)) from the master pulse generator 11 described above. And a speed signal processor 36 that obtains a speed signal from the position signal from the position signal processor 35, outputs the speed signal to the first adder 31, adds the speed command described above, and outputs the result to the speed controller 32. It is configured.
[0022]
The slave servo motor control unit includes a speed controller 38 to which a speed command is input via a third adder 37, and a current controller 40 to which an output of the speed controller 38 is input via a fourth adder 39. A position signal processor 41 for outputting a position signal from a signal (slave speed FB (feedback)) from the slave pulse generator 13 described above, and a position signal processor for subtracting the position signals of the position signal processors 35 and 41 to obtain a deviation therebetween. A position controller 43 to which a deviation between the position of the drive shaft of the master servomotor 10 and the position of the drive shaft of the slave servomotor 12 is input via a 5-adder 42, and a speed controller 32 in the master servomotor control unit. The deviation of these outputs is input via an adder 44 which detects the deviation between the output and the output of the speed controller 38 in the slave servomotor control unit. A torque tuner 45 for inputting a torque tuning control output, which is an output, to a third adder 37, and a speed signal processor 46 for obtaining a speed signal from a position signal from the position signal processor 41 and inputting the speed signal to the third adder 37. It is comprised including. The third adder 37 subtracts the torque tuning control output and the speed signal from the speed signal processor 46 from the speed command.
[0023]
In the above configuration, the speed command from the command generation controller 1 is compared with the speed FB from the master servomotor 10, and the speed is controlled by the speed controller 32. The output of the speed controller 32 becomes a current command for the master servomotor 10, is compared with the current FB of the master servomotor 10, and is controlled by the current controller 34.
[0024]
On the other hand, the same speed command as the speed command input to the master servomotor 10 is input to the speed controller 38 of the slave servomotor control unit, and the speed command is compared with the speed FB from the slave servomotor 12. The speed is controlled by the heater 38. The output of the speed controller 38 becomes a current command for the slave servomotor 12, is compared with the current FB of the slave servomotor 12, and is controlled by the current controller 40.
[0025]
The speed FB of the master servomotor 10 is integrated by a position signal processor (integration counter) 35 to obtain a position signal of the master servomotor 10. On the other hand, the speed FB of the slave servomotor 12 is integrated by the position signal processor (integration counter) 41 to become a position signal of the slave servomotor 12. The obtained position signal of the master servomotor 10 and the position signal of the slave servomotor 12 are compared, and the position is controlled by the position controller 43 so that the positions of the master servomotor 10 and the slave servomotor 12 become equal. The position control output from the position controller 43 is added to the current command of the slave servomotor 12 by the adder 39 as a position synchronization control output.
[0026]
Further, the speed control output output from the speed controller 32 of the master servomotor 10 and the speed control output output from the speed controller 38 of the slave servomotor 12 are compared by an adder 44. The speed control outputs of the motor 10 and the slave servomotor 12 are controlled so as to be coincident with each other, and become a torque tuning control output, which is input to the speed controller 38 of the slave servomotor 12.
[0027]
Thus, according to the drive control device and the drive control method of the injection molding machine in the embodiment, the belt described in the related art can be eliminated, and the mechanical structure can be simplified. In addition, since the connecting portion between the main drive shaft and the slave drive shaft is only the portion of the feed screw mechanism, the relationship of the force transmission is clear, and for example, the displacement amount of the output shaft of the master servomotor 10 and the slave servomotor 12 is reduced. By measuring and obtaining the spring constant between the output shafts from the measured displacement and torque, the degree of aging of the mechanical power transmission mechanism can be monitored from the spring constant, and the reliability of the machine can be reduced. Can be improved. Further, it is possible to control the positional relationship between the main drive shaft and the slave drive shaft and the relationship between the driving forces by software, and it is possible to ensure the simultaneous operation of the master drive shaft and the slave drive shaft. . As a result, in particular, the degree of balance of the feed screw mechanism is ensured, and it is possible to prevent a decrease in mechanical efficiency and to prevent a reduction in the life of the feed screw. In addition, by having a control configuration that further tunes the torque balance, it becomes possible to apply a speed control loop to each of the main drive shaft and the slave drive shaft, so that the influence of non-linear friction at the time of stopping and at the time of low speed is canceled, A drive system with high synchronization accuracy can be configured. By the above effects, the mechanical efficiency is improved and the reliability against aging is improved, and it is possible to provide an end-user with an injection molding machine capable of producing a stable molded product for a long period of time. .
[0028]
In the present embodiment, two servo motors, the master servo motor 10 and the slave servo motor 12, have been described. However, it goes without saying that the present invention can be similarly applied to three or more servo motors.
[0029]
【The invention's effect】
As described above, according to the present invention, the operation of a plurality of servomotors, for example, the simultaneousness of the thrust and the movement amount of a ball screw of an injection molding machine is ensured, and the components of these servomotors and the injection molding machine are ensured. For example, it is possible to provide a drive control device and a method of an injection molding machine that are not easily affected by non-linear friction at the time of stopping and at low speed, and the structure of a mechanical power transmission mechanism between the screw and the screw is simplified. It works.
[Brief description of the drawings]
FIG. 1 is a control block diagram schematically showing a drive control device of an injection molding machine according to an embodiment of the present invention.
FIG. 2 is a control block diagram of a drive control device of the injection molding machine according to the embodiment of the present invention.
FIG. 3 is a schematic diagram showing a conventional example.
[Explanation of symbols]
1 Command generation controller, 2 servo controllers, 10 master servomotors, 12 slave servomotors, 11 master pulse generators, 13 slave pulse generators, 31, 33, 37, 39, 42, 44 adders, 35, 41 position signal processors , 36, 46 speed signal processor, 34, 40 current controller, 43 position controller, 45 torque tuner.

Claims (4)

A drive control device for an injection molding machine configured to drive at least two motors (10, 12) configured in a master-slave relationship to drive a movable portion of the injection molding machine,
Speed detecting means (11, 36, 13, 46) for detecting the speed of the drive shaft of the at least two motors (10, 12);
A speed controller (32, 38) for comparing a speed detected by the speed detecting means with a given speed command and forming a drive control signal for each of the motors (10, 12) based on the comparison result; ,
The results of the comparison of the outputs from the speed controllers corresponding to the respective motors are fed back to the speed controllers for the subordinate motors of the at least two motors, so that the subordinate motors A torque tuner (45) which constitutes speed changing means (44, 45) for changing the output value of the speed controller with respect to the torque control of the at least two motors;
Position detection means (11, 35, 13, 41) for detecting a position of a drive shaft of the at least two motors (10, 12);
A position synchronization signal is formed based on a comparison result of the positions of the drive shafts of the at least two motors detected by the position detection means, and a drive control signal of a subordinate motor of the at least two motors is formed. A drive control device for an injection molding machine, further comprising: a position controller (43) for performing position synchronization of the at least two motors. The drive control device for an injection molding machine according to claim 1,
The drive control device for an injection molding machine, wherein the at least two motors (10, 12) apply thrust to the movable portion by a feed screw mechanism. The drive control device for an injection molding machine according to claim 1 or 2,
The drive control device for an injection molding machine, wherein the movable part is a slide plate (26) provided with a screw of the injection molding machine. A drive control method for an injection molding machine configured to drive at least two motors (10, 12) configured in a master-slave relationship to drive a movable portion of the injection molding machine,
The speed of the drive shaft of the at least two motors (10, 12) is detected, the detected speed is compared with a given speed command, and the driving of each of the motors (10, 12) is performed based on the comparison result. Forming a control signal,
Comparing the drive control signals corresponding to the respective motors, and feeding back the comparison result for forming the drive control signals for the subordinate motors of the at least two motors, thereby forming the subordinate motors . Changing the drive control signal as a speed control value for the motors in relationship, performing torque tuning of the at least two motors,
Detecting the positions of the drive shafts of the at least two motors (10, 12);
A position synchronization signal is formed based on a comparison result of the positions of the drive shafts of the at least two motors, and a position control signal of the at least two motors is added to a drive control signal of a subordinate motor of the at least two motors. A drive control method for an injection molding machine, comprising performing position synchronization.

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