JP4239158B2 - Servo motor control device for electric injection molding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a servo motor control device for controlling the rotation operation of an electric servo motor that drives a control shaft in an injection device, a mold clamping device, an ejector device or the like of an electric injection molding machine.
[0002]
[Prior art]
Conventionally, in a large electric injection molding machine, a feed screw shaft is screwed onto a motion controller that commands the operation of an injection screw of an injection device and a nut fixed to a support member that rotatably supports the injection screw. A plurality of servo motors that drive the injection screw forward and backward via a screw mechanism and a transmission mechanism that has a belt wound around a pulley, and one specific servo motor of the plurality of servo motors. A master servo amplifier that controls the rotation of the specific servo motor according to a command from the controller, and a slave amplifier that is provided corresponding to a non-specific servo motor other than the specific servo motor and controls the rotation of the non-specific servo motor. When the master servo amplifier receives an operation command from the motion controller, A specific servo motor is rotated by torque control and a torque command signal is output to the slave servo amplifier. Based on the torque command signal, the slave servo amplifier rotates the non-specific servo motor by torque control. 2. Description of the Related Art Servo motor control devices that can control a servo motor with high accuracy are known (see, for example, Patent Document 1 and Patent Document 2).
[0003]
[Patent Document 1]
JP 11-28751 A
[Patent Document 2]
JP 2001-212855 A
[0004]
[Problems to be solved by the invention]
However, in the servo motor control device of the electric injection molding machine, when the transmission mechanism is individually provided for a plurality of servo motors, for example, any one of the plurality of servo motors. The belt of the transmission mechanism corresponding to one breaks, and an imbalance occurs between the output of the servo motor corresponding to the transmission mechanism where the belt is broken and the output of another servo motor corresponding to the transmission mechanism where the belt does not break. However, since there is no means for automatically detecting this, there is a possibility that the machine may be operated with the output of each servo motor being in an unbalanced state, and the servo corresponding to the transmission mechanism in which the belt is broken. When the operation of the screw mechanism by the motor is stopped, the support member of the injection screw is inclined, and the injection screw with respect to the screw of the screw mechanism and the support member is placed. Ryu support bearings, damage to the guide device and the like for moving the support member to slide guidance may occur.
[0005]
The present invention has been made in view of the above circumstances, and when an abnormality occurs in the transmission mechanism that transmits the driving force of the servo motor to the movable member, this is surely detected to prevent damage to the machine. An object of the present invention is to provide a servo motor control device for an electric injection molding machine that can be prevented.
[0006]
[Means for Solving the Problems]
  The present invention is characterized by the following points in order to solve the above problems.
  That is, a servo motor control device for an electric injection molding machine according to claim 1 includes a controller that commands operation of a movable member in the electric injection molding machine, and a plurality of servo motors that drive the movable member via a transmission mechanism. A master servo amplifier that is provided corresponding to a specific servo motor of the plurality of servo motors and controls rotation of the specific servo motor in accordance with a command from the controller; and a non-specific servo other than the specific servo motor In a servo motor control device provided corresponding to a motor and provided with a slave servo amplifier that controls rotation of the non-specific servo motor, the master servo amplifier performs torque control on the specific servo motor, and A main control means for outputting a torque command signal to the slave servo amplifier; Motor ofThe load factor that is the ratio of the load current output by the specific servo motor to the rated currentMain state quantity detecting means for detecting the slave servo amplifier, the slave servo amplifier, slave control means for performing torque control on the non-specific servo motor based on the torque command signal, and non-specific servo motorLoad factor, which is the ratio of load current output by the non-specific servo motor to the rated currentAnd a secondary state amount detecting means for detecting the main state amount detecting means.Load factorAnd the sub-state quantity detection meansLoad factorAnd a comparison control means for displaying an abnormality on the display when the deviation or ratio thereof is equal to or greater than an allowable value.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a servo motor control device of an electric injection molding machine according to an embodiment of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an injection device of an electric injection molding machine. An injection screw (movable member) is inserted into a heating cylinder 3 fixed to a front plate 2 so as to be rotatable in the circumferential direction and movable in the axial direction. ) 4. The injection screw 4 is rotatably and axially relative to a pusher plate (movable member) 7 supported and guided by guide rods 6 and 6 that connect the front plate 2 and the rear plate 5 with a load cell 7a interposed therebetween. It is supported so as not to move, and is rotated by an electric servomotor (servomotor) for screw rotation (not shown) fixed to the pusher plate 7.
[0011]
The pusher plate 7 is fixed to a pair of ball nuts (nuts) 8 and 8 rotatably supported by the front plate 2 and the rear plate 5, and a pair of screw nuts 8 and 8 are screwed together. Ball screw shafts (screw shafts) 9 and 9 are timing pulleys 12 and 12 fixed to timing pulleys (pulleys) 10 and 10 fixed to the ball screw shafts 9 and 9 and output shafts of a pair of electric servomotors 11a and 11b. The injection screw 4 is moved forward and backward in the axial direction by being rotated by the electric servomotors 11a and 11b via transmission mechanisms 14 and 14 each having a timing belt 13a and 13b wound thereon. It has become. The electric servo motors 11a and 11b are provided with rotary encoders (position detectors) 11a1 and 11b1 for detecting their rotational positions. The ball nuts 8 and 8 and the ball screw shafts 9 and 9 constitute a screw mechanism 9a that converts the rotation of the electric servo motors 11a and 11b into a linear motion and moves the pusher plate 7 in the axial direction of the injection screw 4. Yes.
In the figure, K is a mold that is clamped by a mold clamping device (not shown), and the resin material introduced into the heating cylinder 3 is plasticized by the rotation of the injection screw 4 so that the tip end side of the heating cylinder 3 is plasticized. The molten resin is measured in the resin reservoir 3a, and the injection screw 4 retracted while applying a back pressure to the molten resin is advanced by the rotation of the electric servo motors 11a and 11b, thereby the resin reservoir 3a. The molten resin is injected into the mold cavity of the mold K.
[0012]
In FIG. 1, G is a servo motor control device that controls the rotation of each of the electric servo motors 11a and 11b of the injection device 1 of the electric injection molding machine. The servo motor control device G is output from a controller 15 that controls the overall operation of the electric injection molding machine, a machine operation panel 16 that inputs various instruction items and set values to the controller 15, and a controller 14. A display 17 for displaying various data and alarms, and a servo amplifier (hereinafter referred to as “a specific servo motor”) 11a for controlling the rotation of one of the electric servo motors 11a and 11b. 18) and a servo amplifier (hereinafter referred to as "slave servo amplifier") for controlling the rotation of another electric servo motor (hereinafter referred to as "non-specific servo motor") 11b among the electric servo motors 11a and 11b. 19).
[0013]
The machine operation panel 16 includes various operation switches 16a for operating the electric injection molding machine, the injection speed of the injection screw 4 of the injection apparatus 1, the injection pressure, the switching position thereof, the back pressure, and the molten resin. Various setting devices 16b for setting the measurement completion position, pressure holding time, etc., allowable time setting device 16c for setting the allowable continuation time of abnormal operation described later, and load factor of load current of each electric servomotor 11a, 11b (described later) And an allowable deviation setting unit 16d for setting an allowable value for the deviation.
The controller 15 includes a sequence program for controlling the overall operation of the electric injection molding machine, set values set by the setting devices 16b, 16c, and 16d of the machine operation panel 16 (the electric injection molding machine The memory 15a for storing the molding conditions and the like by the injection apparatus 1) and the necessary calculation processing and the like are performed based on the set values stored in the memory 15a and the detection values of the load cell 7a and the rotary encoders 11a and 11b. Various control data for operating the injection apparatus 1 and the like are created, and the control data is output to the master servo amplifier 18 and the slave servo amplifier 19 via the signal lines L1 and L2, and required for the display unit 17. The control part 15b which outputs the display item of is provided.
[0014]
The control unit 15b has a timer function (timer) 15c, an allowable value for a deviation of a load factor (described later) set by the allowable deviation setter 16d of the machine operation panel 16, and the master servo amplifier 18 The load factor input from the slave servo amplifier 19 is compared with the deviation of the load factor input from the slave servo amplifier 19, and when the deviation exceeds the allowable value, the time during which the state exceeding the allowable value continues is determined as the timer. Comparing control means 15d is provided for displaying an abnormality warning on the display unit 17 when the time is measured (monitored) by the function 15c and the measured time matches the allowable duration set by the allowable time setter 16c. .
[0015]
The master servo amplifier 18 includes a CPU (central processing unit) 20, a power unit 21 that rotates the specific servo motor 11a based on a torque command signal i1 output from the CPU 20, and an output from the specific servo motor 11a. CT (current detection unit) 22 for detecting (measuring) the load current (operating state quantity) Im, and A / D conversion of the load current Im detected by the CT 22 to output to the CPU 20 And a D / A converter 23b that D / A converts the torque command signal i1 output from the CPU 20 and outputs the converted signal to the slave servo amplifier 19. The CPU 20, the power unit 21 and the D / A converter 23b constitute a main control means 18a for performing torque control on the specific servo motor 11a and outputting a torque command signal to the slave servo amplifier 19.
[0016]
The CPU 20 operates based on an operation command from the controller 15b of the controller 15, and displays a torque command signal i1 for driving the specific servo motor 11a as a ratio of a load current to a rated current of the specific servo motor 11a. And a torque command signal (digital signal) i1 based on the calculated load factor is output to the power unit 21 and to the D / A converter 23b, and the first A / D converter The load current Im input from 23a is compared with the rated current to calculate its load factor and output to the controller 15b of the controller 15.
[0017]
The slave servo amplifier 19 performs A / D conversion on the torque command signal (analog signal) i1a output from the CPU (central processing unit) 24 and the D / A converter 23b of the master servo amplifier 18 to perform digital conversion. A second A / D converter 25 input to the CPU 24 as a signal i1, a power unit 26 that rotates the non-specific servo motor 11b based on a torque command signal i1 output from the CPU 24, and the non-specific servo. A CT (current detection unit) 27 for detecting (measuring) the load current (operation state quantity) Is output from the motor 11b, and a third output for A / D conversion of the load current Is detected by the CT 27 and outputting it to the CPU 24. And an A / D converter 28. The CPU 24, the power unit 26, and the second A / D converter 25 constitute sub control means 19a that performs torque control on the non-specific servo motor 11b.
[0018]
The CPU 24 operates based on the operation command and control data input from the controller 15b of the controller 15, and sends the torque command signal i1 input from the second A / D converter 25 to the power unit 27. And outputs the load factor Is of the non-specific servo motor 11b input from the third A / D converter 28 to the rated current to calculate the load factor, and sends it to the control unit 15b of the controller 15. It is designed to output.
The CPUs 20 and 24 of the master servo amplifier 19 and the slave servo amplifier 19 respectively detect the rotational position signals f1 and f2 detected by the rotary encoders 11a1 and 11b1 of the electric servomotors 11a and 11b, and the rotational position signals. Based on the speed signal obtained by calculating f1 and f2 and the load signal detected by the load cell 7a, the rotation amount (rotation position) and the rotation force (drive torque) of each electric servomotor 11a, 11b, that is, The forward / backward position, injection speed, injection pressure, and back pressure of the injection screw 4 are feedback-controlled.
[0019]
Next, the operation of the servo motor control device G of the injection device 1 in the electric injection molding machine having the above configuration will be described with reference to FIG.
Prior to starting the molding operation by the electric injection molding machine, necessary numerical values are set and input by various setting devices 16b of the machine operation panel 16, and predetermined values are respectively input to the allowable time setting device 16c and the allowable deviation setting device 16d. Set and input the numerical value of. The numerical values inputted and set are stored in the memory 15a via the control unit 15b of the controller 15 and the selected required items are displayed on the display unit 17. Thereafter, the operation switch 16a of the machine operation panel 16 is operated to start the molding operation by the electric injection molding machine.
[0020]
When the injection operation is started after the molding operation is started, the controller 15c of the controller 15 in the servo motor controller G sends the master servo amplifier 18 and the slave servo amplifier 19 with respect to them via signal lines L1 and L2. An activation signal is sent to turn on each servo amplifier 18, 19 (step S1), and an operation command is output to the CPU 20 of the master servo amplifier 18 (step S2). The CPU 20 generates a torque command signal i1 for driving the specific and non-specific servo motors 11a and 11b based on an operation command from the control unit 15b, and determines the load current corresponding to the rated current of the specific and non-specific servo motors 11a and 11b. The torque command signal (digital signal) i1 based on the calculated load factor is output to the power unit 21 (step S3), and the D / A converter 23b and the second A The data is output to the CPU 24 of the slave servo amplifier 19 via the / D converter 25 (step 4).
[0021]
When the torque command signal i1 is input from the CPU 20, the power unit 21 rotationally drives the specific servo motor 11a based on the torque command signal i1 (step S5). On the other hand, the CPU 24 outputs the torque command signal i1 input from the master servo amplifier 18 to the power unit 26 (step S6), and based on the torque command signal i1, the power unit 26 performs the non-specific servo motor. 11b is rotationally driven (step S7). Thereby, the injection operation in the injection device 1 is executed according to the sequence program stored in the memory 15a of the controller 15, and the transmission mechanisms 13a and 13b, the ball nut 8 and the ball are rotated by the rotation of the electric servomotors 11a and 11b. A mold in which the injection screw 4 moves forward through the screw 9 (screw mechanisms 9a, 9a), and the molten resin previously measured in the resin reservoir 3a in the heating cylinder 3 is clamped by a mold clamping device. The molding cavity of K is filled.
[0022]
During the forward movement of the injection screw 4, the load currents Im and Is of the electric servomotors 11a and 11b are detected (measured) by the CTs 22 and 27 (steps S8 and S9), and the A / D converters 23a and 28 are detected. Are sent to the CPUs 20 and 24 through the motors 20 and 24, so that the CPUs 20 and 24 have motor load factors (load factors) Pm that are ratios of the load currents Im and Is to the rated currents of the electric servomotors 11a and 11b. , Ps are calculated and output to the controller 15b of the controller 15 (steps S10 and S11). When the motor load factors Pm and Ps are input to the controller 15b, the comparison control means 15d determines the deviation between the motor load factor Pm of the specific servo motor 11a and the motor load factor Ps of the non-specific servo motor 11b. It is compared whether or not the absolute value (| Pm−Ps |) is equal to or larger than the deviation allowable value P set by the allowable deviation setting device 16d (| Pm−Ps | ≧ P) (step S12). When the absolute value of deviation (| Pm−Ps |) is equal to or greater than the allowable value P (when | Pm−Ps | ≧ P), the timer function 15b measures the time during which the state exceeding the allowable value continues. (Monitoring) (step S13), and when the measurement time coincides with the allowable duration T set by the allowable time setting unit 16c (step S14), an abnormality warning is displayed on the display unit 17, and this It shows the operator performs the required processing (step S15). After performing the process of recovering the abnormal state in step 15, the process returns to step S1 and returns to each electric servo by the controller 15 as in the case where the measurement time does not reach the allowable duration T and no abnormality is recognized in step S14. The control operation of the motors 11a and 11b is repeated, and the injection operation by the injection screw 4 is continued.
[0023]
As described above, the servo motor control device G according to the embodiment includes the specific servo motor 11a among the plurality of servo motors that drive the injection screw 4 of the electric injection molding machine via the transmission mechanisms 14 and 14. The controller 15 is rotationally driven by the master servo amplifier 18 with torque control by the operation command of the controller 15, and the non-specific servo motor 11b other than the specific servo motor 11a is output from the master servo amplifier 18 to the slave servo amplifier 19. Based on the signal i1, it is rotationally driven by torque control. At this time, the load ratios (operating state quantities) of the load currents of the specific and non-specific servomotors 11a and 11b are respectively determined by the master servo amplifier 18 and the slave servo amplifier 19. Detected by the main and sub-state quantity detecting means 18a and 19a, When the difference becomes equal to or greater than the allowable value in the comparison control means 15d of the controller 15 and it is determined that the state has continued for the allowable duration T, an abnormality is displayed on the display 7 by the comparison control means 15d. It is set as the structure.
[0024]
Therefore, according to the servo motor control device G according to the embodiment, for example, the timing belt 13a (13b) of the transmission mechanism 14 (14) corresponding to one of the specific and non-specific servo motors 11a and 11b is broken. Then, the driving force by the one servo motor 11a (11b) is not transmitted to the injection screw 4 via the screw mechanism 9a (9a) corresponding to the one servo motor 11a (11b), and both servo motors If there is a difference in load factor between load currents Im and Is between 11a and 11b, the indicator 17 immediately finds out that an abnormality has occurred in the transmission mechanism 14 (14) and stops the machine. And appropriate measures such as replacing the timing belt 13a (13b) can be taken. As a result, the drive of the injection screw 4 is prevented from continuing for a long time only by the other servo motor 11b (11a), and the pusher plate (support member of the injection screw 4) 7 is moved in an inclined state. There is a risk of damage to the ball screw of the screw mechanisms 9a, 9a, the support bearing of the injection screw 4 with respect to the pusher plate 7, and the guide devices such as the guide rods 6 and 6 that move the pusher plate 7 by sliding guide. It is possible to prevent the machine from being damaged and to extend its service life.
[0025]
The servo motor control device G according to the embodiment includes the injection screw 4 that injects the molten resin in the heating cylinder 3 into the mold K in the injection device 1, the transmission mechanisms 14 and 14, and the screw mechanisms 9a and 9a. The servo motor control device that controls the rotation of the two electric servo motors 11a and 11b that move forward through the servo motor control device has been described. However, the present invention is not limited to this, and the injection device 1 plasticizes the resin material in the heating cylinder 3. The present invention can also be applied to the case where the rotation of the injection screw 4 when measuring the molten resin and the control of the back pressure during the measurement are performed by a plurality of electric servo motors. The present invention can also be applied to drive control of a movable platen (movable member) in the mold clamping device and drive control of an ejector pin of an ejector device that projects a molded product from the mold. Moreover, although the case where the said non-specific servo motor 11b is one was shown, it is not restricted to this, A non-specific servo motor may be two or more, and in that case, each non-specific servo motor has Slave servo amplifiers and transmission mechanisms are individually provided.
[0026]
Further, in the servo motor control device G according to the embodiment, the control unit 15b of the controller 15 outputs motor load factors (load factors) output from the CPUs 20 and 24 of the master servo amplifier 18 and the slave servo amplifier 19. Based on the deviation of Pm and Ps (| Pm−Ps |), the abnormality of the transmission of the driving force from the specific and non-specific servo motors 11a and 11b to the injection screw 4 by the transmission mechanisms 14 and 14 is detected. Not limited to this, when the ratio (Pm / Ps) between the motor load factors Pm and Ps is greater than or equal to a preset allowable value, an abnormality in the transmission of the driving force of the transmission mechanisms 14 and 14 is detected. Alternatively, the rotational position signals f1, f of the specific and non-specific servo motors 11a, 11b detected by the rotary encoders 11a1, 11b1. When the rotational speeds (operation state quantities) of the specific and non-specific servo motors 11a and 11b calculated by the CPUs 20 and 24 are output to the control unit 15b, and the deviation between the rotational speeds exceeds a predetermined value. In addition, it is possible to detect an abnormality in transmission of the driving force of the transmission mechanisms 14, 14.
[0027]
In addition, the servo motor control device G according to the above embodiment is an example when applied to an in-line screw type electric injection molding machine, but the present invention is not limited thereto, and a filling plunger ( And a plasticizing device in which a plasticizing screw (movable member) is rotatably inserted into a plasticizing heating cylinder, and a plasticizing screw of the plasticizing device is provided. Rotating to plasticize the resin material, supplying the molten resin to the resin reservoir at the tip of the filling cylinder, measuring the molten resin in the filling cylinder, and moving the measured molten resin into the mold by the advance of the filling plunger The present invention can be applied to a pre-plastic electric injection molding machine that is filled.
[0028]
【The invention's effect】
  As described above, according to the present invention, the following excellent effects are obtained.
  According to the servo motor control device of the electric injection molding machine according to claim 1, the specific servo motor among the plurality of servo motors that drive the movable member of the electric injection molding machine via the transmission mechanism is operated by the controller. The command is rotated by torque control by the master servo amplifier, and non-specific servo motors other than the specific servo motor are rotated by torque control based on the torque command signal output from the master servo amplifier to the slave servo amplifier. At that time, the specific and non-specific servo motorsLoad factor that is the ratio of load current output by the specified or non-specific servo motor to the rated currentAre detected by the master and slave state quantity detection means in the master servo amplifier and slave servo amplifier, respectively.Load factorWhen the deviation or ratio of the motor is greater than or equal to an allowable value, an abnormality is displayed on the display by the controller. For example, a transmission mechanism corresponding to one of the specific and non-specific servo motors. If the belt breaks and a difference in operating state such as driving force or rotational speed occurs between the two servomotors, the indicator immediately detects an abnormality in the transmission mechanism and takes appropriate countermeasures. This can prevent the machine from being damaged.
[0029]
  In particular, since the operating state quantity of each servo motor is compared by the load ratio, which is the ratio of the load current to the rated current of the specific servo motor and non-specific servo motor, even if the rated capacity of each servo motor is different, each servo motor The deviation of the operation state quantity can be accurately calculated, and the abnormality in the transmission mechanism can be found with certainty.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a servo motor control device of an electric injection molding machine according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the servo motor control device of the electric injection molding machine according to the embodiment of the present invention.
[Explanation of symbols]
1 Injection device
4 Injection screw (movable member)
7 Pusher plate (movable member)
8 Ball nut (nut)
9 Ball screw shaft (screw shaft)
10,12 Timing pulley (pulley)
11a Electric servo motor (specific servo motor)
11a1, 11b1 rotary encoder (rotational position detector)
11b Electric servo motor (non-specific servo motor)
13a, 13b Timing belt (belt)
14 Transmission mechanism
15 Controller
15a memory
15b Control unit
15c Clock function (time measuring means)
15d comparison control means
16 Machine operation panel
17 Display
18 Master servo amplifier
19 Slave servo amplifier
20, 24 CPU
21, 26 Power section
22, 27 CT (current detector)

Claims (1)

A controller that commands the operation of the movable member in the electric injection molding machine, a plurality of servo motors that drive the movable member via a transmission mechanism, and a specific servo motor among the plurality of servo motors. A master servo amplifier that controls the rotation of the specific servo motor in accordance with a command from the controller, and a slave servo that is provided corresponding to a non-specific servo motor other than the specific servo motor and controls the rotation of the non-specific servo motor In a servo motor control device equipped with an amplifier,
The master servo amplifier includes a main control means for performing torque control on the specific servo motor and outputting a torque command signal to the slave servo amplifier, and the specific servo motor for the rated current of the specific servo motor. And a main state quantity detection means for detecting a load factor that is a ratio of a load current output by
The slave servo amplifier includes slave control means for performing torque control on the non-specific servo motor based on the torque command signal, and load current output by the non-specific servo motor with respect to the rated current of the non-specific servo motor. Subordinate amount detecting means for detecting a load factor that is a ratio of
The said controller, comparing the load factor said main state quantity detecting means detects the load factor and the slave state quantity detecting means detects, indicator when their deviation or ratio becomes allowable value or more A servo motor control device for an electric injection molding machine, characterized in that comparison control means for displaying an abnormality is provided.

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