JP4459823B2 - Molding machine - Google Patents

Description

  The present invention relates to a molding machine such as an electric injection molding machine or a die casting machine, and in particular, a linearly movable member such as an injection shaft or a movable die plate is driven by two servo motors (electric servo motors). The present invention relates to a molding machine that is linearly driven by adding driving forces.

  Servo motors are used to drive the forward / reverse drive source of the injection shaft (screws for inline screw injection molding machines and injection plungers for pre-plastic injection molding and die-casting machines) and for the movable die plate equipped with a movable die. When trying to increase the size of the machine (molding machine), if the servo motor is simply increased in size in response to the increase in size of the machine (by using a servo motor with a large motor capacity), the servo The outer diameter of the motor, the ball screw mechanism, and the bearing is increased, the moment of inertia is increased, the transient response is deteriorated, and the large-capacity servo motor is expensive, which causes a significant cost increase.

  For this reason, as a forward / backward drive source for the injection shaft and the movable die plate, a pair of servo motors having a relatively small capacity and a low cost are used, and the driving force of the two servo motors is combined to obtain a large power, There have been various proposals of molding machines that can suppress cost increase and suppress an increase in moment of inertia to obtain a good transient response (rise / fall characteristics).

  By the way, when two servo motors are made to cooperate, if the two servo motors are not synchronized, when the two servo motors are controlled by speed control, the synchronization between the motors shifts and the efficiency decreases. Depending on the case, the torque balance between the motors may be lost when the motor is stopped due to a loss of synchronization, and a phenomenon in which the motors are pulled due to torque imbalance (a state in which the motor cannot be controlled) occurs. In order to prevent this, a synchronization device (synchronization unit) that controls the synchronization between the two servomotors may be used. However, the synchronization device is relatively expensive and increases costs.

  Therefore, in order not to use a synchronizer, to reduce efficiency and to prevent torque imbalance, one of the two servo motors is a master motor and the other is a slave motor. Only the system is given a speed control command from the host device to control the speed of the master motor, and the slave motor control system is given the torque command generated by the master motor control system to The applicant of the present application previously proposed a master / slave motor type twin motor drive molding machine that balances the torque of the motor and the slave motor (Patent Document 1).

  In the technique disclosed in Patent Document 1 described above, a master / slave motor type twin motor drive is used, and a slave motor control system is given a torque command generated by the master motor control system, and the slave motor Since the side is controlled by so-called torque assist, the torque of the two motors can be balanced theoretically (assuming no error in the mechanism) with a simple control system.

  However, in the technique disclosed in Patent Document 1, since the actual measured position value (and the actual measured speed value obtained from the position information) is not monitored on the slave motor side, the master motor side and the slave actually A slight deviation occurs between the position / speed of the master motor and the position / speed of the slave motor due to backlash that is unavoidable due to the tolerance of the rotation transmission system on the motor side. In this way, if a position / speed deviation occurs between the master and the slave, the linear motion plate receives the linear motion force of the ball screw mechanism for the master motor and the linear motion force of the ball screw mechanism for the slave motor together. In addition, a slight inclination occurs, and therefore, the linearly moving members such as the injection shaft and the movable die plate cannot accurately move linearly, and the operation reliability is lowered.

Therefore, as shown in FIG. 3, the rotating part on the master motor side and the rotating part on the slave motor side are connected by a synchronizing belt to mechanically synchronize the position and speed of the two motors. Had to be forced. In FIG. 3, 51 is an injection shaft, 52 is a linear motion plate that moves forward and backward integrally with the injection shaft 51, 53 is a master motor (master servo motor), and 54 is fixed to the output shaft of the master motor 53. The driving pulley 55 is a driven pulley that transmits the rotation of the driving pulley 54 via the timing belt 56, and the ball screw mechanism 57 that converts the rotation of the driven pulley 55 into a linear motion and transmits it to the linear motion plate 52. Is a slave motor (slave servo motor), 59 is a driving pulley fixed to the output shaft of the slave motor 58, 60 is a driven pulley that transmits the rotation of the driving pulley 59 via a timing belt 61, and 62 is a driven pulley. A ball screw mechanism for converting the rotation of 60 into a linear motion and transmitting it to the linear motion plate 52, 63 rotates integrally with the driven pulley 55. Pulling pulley 64, synchronizing pulley rotating integrally with driven pulley 60, and 65 connecting synchronizing pulleys 63, 64 for synchronization to synchronize rotation (position / speed) between master / slave. It is a belt (timing belt).
Japanese Patent No. 3500265

  However, as shown in FIG. 3, if a synchronization belt is used to mechanically synchronize the positions and speeds of the two motors, the synchronization pulleys 63 and 64 and the synchronization belt 65 are required. As a result, the number of parts increases and the cost increases, and there is a problem that the size of the machine is increased by the arrangement space of the synchronization pulleys 63 and 64 and the synchronization belt 65.

  Note that in a configuration in which a single linear moving member is driven by a twin motor, control of two servo motors is performed without using the master / slave motor system as described above that gives a command from the host device only to the master motor control system. A technique in which a command is given to the system from a host device is also known in Japanese Patent No. 3556897. However, in the twin motor control of a molding machine such as an injection molding machine, the master / slave motor system is the current mainstream and reliable, and is disclosed in Japanese Patent No. 3556897. The basic concept of control differs greatly between the technology and the master / slave motor system technology.

  The present invention has been made in view of the above points. The object of the present invention is to control the position and speed of two motors in a configuration in which a single linear moving member is driven by a twin motor and a master / slave motor system. An object of the present invention is to make it possible to reduce the deviation between the position / speed of the master motor and the position / speed of the slave motor as much as possible without using a synchronization belt for mechanical synchronization.

In order to achieve the above object, the present invention
The rotation of the two servo motors is converted into a linear motion by an individual ball screw mechanism, and this linear motion is transmitted to a single linear moving member, and one of the two servo motors is a master motor and the other is a slave motor. As described above, only the master motor control system is given a speed control command from the host device, and the master motor is speed feedback controlled. The slave motor control system is generated by the master motor control system. In a molding machine that gives a torque command for master speed control,
A slave speed correction command generation unit that generates a torque command for speed correction for the slave motor based on the actual speed measurement value of the master motor and the actual speed measurement value of the slave motor;
Generates a slave speed control torque command for the slave motor based on a speed correction torque command output from the slave speed correction command generator and a master speed control torque command generated by the master motor control system. A torque command generator for slave speed control,
A torque correction command generator for generating a torque correction command for the master motor and the slave motor based on the actual position measurement value of the master motor and the actual position measurement value of the slave motor;
Correction means for correcting the master speed control torque command by the torque correction command output from the torque correction command generation unit;
Correction means for correcting the slave speed control torque command by the torque correction command output from the torque correction command generation unit,
The structure which has is taken.

  According to the present invention, based on the actual measured value of the master motor and the actual measured value of the slave motor, a torque command for speed correction for the slave motor is generated, and the torque command for speed correction and the control system of the master motor are used. Generates a slave speed control torque command for the slave motor based on the generated master speed control torque command. Also, based on the master motor position actual measurement value and slave motor position actual measurement value, the master motor and slave motor A torque correction command is generated for the motor, and the master speed control torque command and the slave speed control torque command are appropriately corrected by this torque correction command. Can be reduced as much as possible and the torque between the master motor and the slave motor can be reduced. Deviation of the click can also be reduced as much as possible. Therefore, in a configuration in which a single linear moving member is driven by a twin motor and a master / slave motor system, the master / slave member can be driven without using a synchronization belt for mechanically synchronizing the position and speed of the two motors. Deviations in speed and torque between slaves can be reduced as much as possible, and high operational reliability can be guaranteed. Furthermore, even when a synchronization belt is used, it cannot be denied that there is a slight shift in speed and torque between the master and slave due to the extension of the synchronization belt. However, when such a synchronization belt is used. It has been confirmed by experiments that the amount of deviation can be improved by a little less than 20% with respect to the amount of deviation between the master and the slave, although the present invention excludes the synchronization belt.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a simplified explanatory view of an injection mechanism of an in-line screw injection molding machine according to an embodiment of the present invention (hereinafter referred to as the present embodiment).

  In FIG. 1, 1 is a screw that is an injection shaft, 2 is a linear motion plate that moves forward and backward integrally with the screw 1, 3 is a master motor (master servo motor), and 4 is fixed to an output shaft of the master motor 3. A driving pulley 5 is a driven pulley that transmits the rotation of the driving pulley 4 via the timing belt 6, and a ball screw mechanism 7 that converts the rotation of the driven pulley 5 into a linear motion and transmits the linear motion to the linear plate 2, 8 Is a slave motor (slave servo motor), 9 is a driving pulley fixed to the output shaft of the slave motor 8, 10 is a driven pulley that transmits the rotation of the driving pulley 9 via a timing belt 11, and 12 is a driven pulley. This is a ball screw mechanism that converts 10 rotations into linear motion and transmits it to the linear motion plate 2.

  In the configuration shown in FIG. 1, the rotation of the master motor 3 is transmitted to the rotating portion of the ball screw mechanism 7 via the drive pulley 4 → the timing belt 6 → the driven pulley 5, and thereby converted into a linear motion by the ball screw mechanism 7. The linear moving force is transmitted to the linear motion plate 2 integrated with the linear motion part of the ball screw mechanism 7, and the rotation of the slave motor 8 is driven by the ball screw mechanism via the driving pulley 9 → the timing belt 11 → the driven pulley 10. 12 is transmitted to the linear motion plate 2 integrated with the linear motion part of the ball screw mechanism 12, and is thus transmitted to the linear motion plate 2. The screw 1 moves linearly by being driven by a twin motor together with the moving plate 2.

  FIG. 2 is a block diagram showing a configuration of an injection control system in the injection molding machine of the present embodiment. In FIG. 2, 21 is a computing unit (the computing unit in this specification refers to a processing unit that performs addition or subtraction processing), 22 is a master speed command generation unit, 23 is a computing unit, and 24 is for master speed control. Torque command generation unit, 25 is a computing unit (master torque command correction unit), 26 is a master torque control unit that finally drives and controls the master motor 3, 27 is an encoder attached to the master motor 3, and 28 is a master speed calculation. , 29 is an encoder attached to the slave motor 8, 30 is a slave speed calculator, 31 is a calculator, 32 is a slave speed correction command generator, 33 is a calculator (slave speed control torque command generator), 34 Is a calculator, 35 is a torque correction command generator, 36 is a calculator (slave torque command corrector), and 37 is a slave that finally drives and controls the slave motor 8. A torque control unit.

  In the configuration shown in FIG. 2, the computing unit 21 includes a position command (speed control command) S <b> 1 from a host device (not shown) of the machine (injection molding machine) and a position actual measurement value S <b> 2 of the master motor 3 from the encoder 27. And the master speed command S3 is generated by the speed command generator 22 based on the calculation result of the calculator 21, and this is input to one input terminal of the calculator 23. Based on the actual measured position S2 of the master motor 3 from the encoder 27, the actual measured speed S4 of the master motor 3 calculated by the master speed calculating unit 28 is input to the other input terminal of the arithmetic unit 23. Based on the calculation result, the master speed control torque command generator 24 converts the speed command into a torque command to generate a master speed control torque command S5, and this is generated by the calculator (master torque command correction unit) 25. Input to one input terminal.

  The calculator 31 includes the slave motor 8 calculated by the slave speed calculator 30 based on the actual measured value S4 of the master motor 3 from the master speed calculator 28 and the actual measured value S6 of the slave motor 8 from the encoder 29. , And the slave speed correction command generation unit 32 generates a speed correction command S8 for the slave motor 8 based on the calculation result of the calculator 31. This is the slave speed correction command generation unit 32. Is input. In the slave speed correction command generation unit 32, the speed correction command is converted into a torque command to generate a slave speed correction torque command S9, which is one input terminal of the calculator (slave speed control torque command generation unit) 33. Is input. The master speed control torque command S5 from the master speed control torque command generator 24 is input to the other input terminal of the calculator (slave speed control torque command generator) 33, and the calculator (slave speed control). (Torque command generation unit) 33 generates a slave speed control torque command S10 for the slave motor 8 based on the master speed control torque command S5 and the slave speed correction torque command S9, and this is calculated by a calculator (slave torque). (Command correction unit) 36 is input to one input terminal.

  The calculator 34 receives the actual measured value S2 of the master motor 3 from the encoder 27 and the actual measured value S6 of the slave motor 8 from the encoder 29. Based on the calculation result of the calculator 34, the torque correction command The generation unit 35 generates a torque correction command S11 for the master motor 3 and the slave motor 8, and this torque correction command S11 is connected to the other input terminal of the calculator (master torque command correction unit) 25 and the calculator (slave torque). The command is input to the other input terminal of the command correction unit 36.

  The computing unit (master torque command correction unit) 25 corrects the master speed control torque command S5 from the master speed control torque command generation unit 24 using the torque correction command S11 from the torque correction command generation unit 35, and The corrected torque command S12 is input to the master torque control unit 26, and the master torque control unit 26 drives and controls the master motor 3 according to the input torque command S12.

  The computing unit (slave torque command correction unit) 36 uses the slave speed control torque command S10 from the computing unit (slave speed control torque command generation unit) 33 and the torque correction command S11 from the torque correction command generation unit 35. The corrected torque command S13 is input to the slave torque control unit 37, and the slave torque control unit 37 drives and controls the slave motor 8 in accordance with the input torque command S13.

  Note that the master / slave type twin motor drive speed / torque deviation requires an initial reset. The initial reset is performed at that time because the positions of the two motors 3 and 8 are mechanically aligned when the origin of the injection shaft (screw 1) is set. That is, the initial reset of the master / slave system speed / torque deviation is performed by the following procedure when the origin of the injection shaft (screw 1) is set.

  The origin of the screw 1 is determined by placing the linear motion plate 2 against a stopper (not shown) of the forward limit or backward limit of the screw 1 and stopping the pressing, and the positions (rotational positions) of the two motors 3 and 8 are mechanically determined. When they are all in place, the encoder 27 and the encoder 29 are reset (counter reset), respectively (note that the encoder 27 and the encoder 29 use absolute value encoders, and even if the power is turned off, the internal battery is The counter value is retained). Then, when the origin of the screw 1 is determined, the initial reset of the speed / torque deviation between the master and the slave is simultaneously performed. The initial resetting of the torque deviation amount is performed by resetting the calculator 34, resetting the torque correction command generation unit 35, and resetting the torque correction command S11 (0 (zero) output). Further, the initial resetting of the speed deviation amount resets the computing unit 31, resets the speed correction command S8 for the slave motor 8 and the slave speed correction command generation unit 32, and resets the slave speed correction torque command S9 ( 0 (zero) output).

  As described above, in this embodiment, based on the actual speed measurement value S4 of the master motor 3 and the actual speed measurement value S7 of the slave motor 8, a speed command torque command (slave speed correction torque command S9) for the slave motor 8 is provided. And a slave speed control torque command S10 for the slave motor 8 based on the slave speed correction torque command S9 and the master speed control torque command S5 generated by the control system of the master motor 3. Based on the actual measured position value S2 of the master motor 3 and the actual measured position value S6 of the slave motor 8, a torque correction command S11 for the master motor 3 and the slave motor 8 is generated, and this torque correction command S11 is used for master speed control. Correct the torque command S5 and the slave speed control torque command S10 appropriately. , Can be reduced as much as possible the displacement velocity (position) between the master motor 3 and the slave motor 8, and may as much as possible reduce the deviation of the torque between the master motor 3 and the slave motor 8. Therefore, in a configuration in which a single linear moving member (here, screw 1) is driven by a twin motor and a master / slave motor system, a synchronization belt for mechanically synchronizing the positions and speeds of the two motors is provided. Even if it is not used, the speed and torque deviation between the master and slave can be reduced as much as possible, and high operation reliability can be guaranteed. Furthermore, even when a synchronization belt is used, it cannot be denied that there is a slight shift in speed and torque between the master and slave due to the extension of the synchronization belt. However, when such a synchronization belt is used. In the present embodiment, it was confirmed by experiments that the amount of deviation can be improved by a little less than 20%, even though the synchronization belt is omitted in this embodiment.

It is the explanatory drawing which simplified the injection mechanism of the injection molding machine which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the injection control system in the injection molding machine which concerns on one Embodiment of this invention. It is the explanatory drawing which simplified the injection mechanism of the conventional injection molding machine.

Explanation of symbols

1 Screw (injection shaft)
2 Linear plate 3 Master motor (master servo motor)
4 Drive pulley 5 Driven pulley 6 Timing belt 7 Ball screw mechanism 8 Slave motor (slave servo motor)
DESCRIPTION OF SYMBOLS 9 Drive pulley 10 Driven pulley 11 Timing belt 12 Ball screw mechanism 21 Calculator 22 Master speed command generation part 23 Calculator 24 Master speed control torque command generation part 25 Calculator (master torque command correction part)
26 Master Torque Controller 27 Encoder 28 Master Speed Calculator 29 Encoder 30 Slave Speed Calculator 31 Calculator 32 Slave Speed Correction Command Generator 33 Calculator (Slave Speed Control Torque Command Generator)
34 Calculator 35 Torque Correction Command Generation Unit 36 Calculator (Slave Torque Command Correction Unit)
37 Slave torque controller

Claims (1)

The rotation of the two servo motors is converted into a linear motion by an individual ball screw mechanism, and this linear motion is transmitted to a single linear moving member, and one of the two servo motors is a master motor and the other is a slave motor. As described above, only the master motor control system is given a speed control command from the host device, and the master motor is speed feedback controlled. The slave motor control system is generated by the master motor control system. In a molding machine that gives a torque command for master speed control,
A slave speed correction command generation unit that generates a torque command for speed correction for the slave motor based on the actual speed measurement value of the master motor and the actual speed measurement value of the slave motor;
Generates a slave speed control torque command for the slave motor based on a speed correction torque command output from the slave speed correction command generator and a master speed control torque command generated by the master motor control system. A torque command generator for slave speed control,
A torque correction command generator for generating a torque correction command for the master motor and the slave motor based on the actual position measurement value of the master motor and the actual position measurement value of the slave motor;
Correction means for correcting the master speed control torque command by the torque correction command output from the torque correction command generation unit;
Correction means for correcting the slave speed control torque command by the torque correction command output from the torque correction command generation unit,
A molding machine comprising:

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