JP2016030403A - Method and device of controlling electric motor, and molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device of controlling an electric motor which can deal with environmental changes and prevent a mechanical stop due to the operation of a protection function.SOLUTION: The present invention provides a method of controlling an electric motor 26 used in a molding device 10, wherein, an output F of the electric motor 26 is detected, an estimated calorific value T of the electric motor 26 is obtained on the basis of the output F, and when the estimated calorific value T becomes a first predetermined value T1 or more or exceeds the first predetermined value T1, the output of the electric motor 26 is limited to a second predetermined value F2 or less or less than the second predetermined value F2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric motor control method, an electric motor control device, and a molding device.

  The electric injection molding machine includes, for example, an extrusion unit that plasticizes and extrudes a resin material (material), an injection unit that injects the material, a mold, and a mold clamping device that clamps the injection unit, and performs injection, measurement, and mold opening / closing. Each operation such as extrusion is operated by a plurality of drive motors (electric motors).

  As a protection function of the molding machine, the drive motor may be stopped when a predetermined set value determined for protecting the apparatus is reached based on the motor load obtained by estimating the heat generation amount from the load current of each drive motor. .

  When the protection function is activated and the drive motor stops, productivity decreases. In order to avoid this, research has been conducted on technologies such as setting a warning preset value that is smaller than the stop setting value, increasing the cycle of the molding cycle when the preset value is reached, and issuing an alarm. ing.

JP 2001-239567 A JP 2001-239551 A

  However, in the extension of the molding cycle, it is difficult to suppress the machine stop due to the action of the protective function when the load increases due to environmental changes. For example, when the motor is heated due to an environmental change such as an increase in the outside air temperature or foreign matter, the load increases due to a protective function that may cause the machine to stop. When the load increases, the calorific value increases suddenly, so that the protection function acts immediately and the machine stops.

  Therefore, an electric motor control method and an electric motor control apparatus that can cope with environmental changes and suppress machine stoppage due to the action of a protective function are desired.

  In order to solve the above-mentioned problems and achieve the object, the motor control method, motor control apparatus and molding apparatus of the present invention are configured as follows.

  A method for controlling an electric motor used in a molding apparatus, wherein the output of the electric motor is detected, an estimated heat generation amount of the electric motor is obtained based on the output, and the estimated heat generation amount is equal to or more than a first predetermined value or When the predetermined value of 1 is exceeded, the output of the electric motor is limited to a second predetermined value or less or less than a second predetermined value.

  A method for controlling an electric motor used in a molding apparatus, wherein the output of the electric motor is detected, and when the output becomes a first predetermined value or more or exceeds a first predetermined value, the output of the electric motor is changed to a first value. It is limited to a value equal to or less than a predetermined value of 2 or less than a second predetermined value.

  A control device for an electric motor used in a molding apparatus, wherein the detection unit detects an output of the electric motor, a calculation unit obtains an estimated heat generation amount of the motor based on the output, and the estimated heat generation amount is a first predetermined value. A determination unit that determines whether or not the value exceeds a first predetermined value, and when the estimated heat generation amount is equal to or higher than a first predetermined value or exceeds a first predetermined value, A limiting unit that limits the output of the electric motor to a second predetermined value or less or less than a second predetermined value.

  A control device for an electric motor used in a molding apparatus, a detection unit for detecting an output of the electric motor, and whether the output is equal to or higher than a first predetermined value or whether the output exceeds a first predetermined value. A determination unit for determining, and when the output exceeds a first predetermined value or exceeds a first predetermined value, the output of the motor is limited to a second predetermined value or less or less than a second predetermined value. And a control unit.

  ADVANTAGE OF THE INVENTION According to this invention, it can respond to an environmental change and it becomes possible to suppress the machine stop by the effect | action of a protective function.

Explanatory drawing which shows the electric injection molding machine which concerns on 1st Embodiment. The flowchart which shows the control method of the electric injection molding machine which concerns on the same embodiment. The graph which shows the time change of the motor load of the electric injection molding machine. The graph which shows the time change of the load current of the same electric injection molding machine, and a motor load tolerance characteristic. The graph which shows the square current and the cumulative calorific value of the electric injection molding machine. The flowchart which shows the cycle time extension process of the same electric injection molding machine. The graph which shows the relationship between the external temperature of the same electric injection molding machine and the accumulated calorific value. The flowchart which shows the control of the upper limit of the maximum electric current when the load factor of the next shot of the electric injection molding machine is expected to exceed the current limit load factor.

[First Embodiment]
Hereinafter, an electric motor control method, an electric motor control device, and a molding machine (forming device) according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. In each figure, the configuration is appropriately enlarged, reduced, or omitted for explanation.

  FIG. 1 is an explanatory view of an injection molding machine 10 (molding machine, molding apparatus). The injection molding machine 10 is, for example, a so-called in-line type injection molding machine, and includes an injection device 20 that melts and kneads a material, measures and injects, a mold clamping device 35 that clamps a mold 30, and an operation of each device. And a control device 40 for controlling.

  The injection device 20 rotates, for example, a cylindrical plasticizing barrel 21, a hopper 22 as a material supply unit, a screw 24 disposed in the plasticizing barrel 21, a heater 25 for heating the material, and the screw 24. Rotation drive motor 26 (drive motor, electric motor) as a plasticizing motor to be driven, and injection drive motor 27 (drive motor, electric motor) that causes screw 24 to move forward at a predetermined timing to perform an injection operation. Furthermore, an advancing / retreating drive motor 28 (driving motor, electric motor) for advancing and retracting the injection device 20 so as to approach and separate from the mold is also provided.

  A material is accommodated in a plasticizing barrel 21 configured in a cylindrical shape, and a screw 24 is accommodated. A hopper 22 for supplying a material is attached to a side surface of the plasticizing barrel 21. A discharge portion 21 b that discharges material is provided at the tip of the plasticizing barrel 21. A heater 25 for heating the plasticizing barrel 21 is provided on the outer periphery of the plasticizing barrel 21. By rotating and driving the screw 24 built in the plasticizing barrel 21, the internal material is melted and sent out toward the tip.

  The rotation drive motor 26 and the injection drive motor 27 are connected to the control device 40. The rotational drive motor 26 and the injection drive motor 27 are driven according to the control of the control unit 40 to control the rotational operation and the forward operation of the screw 24. The control device 40 can control the rotational speed, rotational speed, rotational time, etc. of the screw 24, the stroke of the shaft operation, the operation timing, and the like.

  The injection device 20 also functions as a weighing device. That is, by driving the rotation drive motor 26, the screw 24 rotates, and the material supplied from the hopper 26 into the plasticizing barrel 21 is sent to the tip side of the plasticizing barrel 21 by the rotation of the screw 24. At the same time, it is stored on the tip side. The screw 24 is retracted by the pressure of the material stored on the tip end side of the screw 24, whereby a measuring operation for measuring the material is performed. Therefore, in this embodiment, the rotational drive motor 26 also functions as a metering motor.

  The mold 30 is provided on the discharge side of the plasticizing barrel 21 and includes a fixed mold 31 attached to the fixed platen 36 and a movable mold 32 attached to the moving platen 37. A cavity 33 is formed between the fixed mold 31 and the movable mold 32.

  The mold clamping device 35 includes, for example, a fixed platen 36, a movable platen 37, a toggle mechanism 38 having one end coupled to the movable platen 37, and a mold clamping drive motor 39 (drive) that drives the toggle mechanism 38 to perform mold clamping. A motor, an electric motor), a link housing (pressure receiving plate) 66, a mold thickness adjusting drive motor (drive motor, electric motor) 65 for moving the link housing 66 to adjust the mold thickness, an extrusion device 60, It has. The mold clamping drive motor 39 moves the moving platen 37 through the toggle mechanism 38 under the control of the control device 40 to open and close the mold 30 at a predetermined timing.

  The extruding device 60 is connected to the moving platen 35 and drives an extruding drive motor (driving motor, electric motor) 61 to cause the extruding pin 62 to protrude from the movable mold 32 and to extrude the molded product.

  The control device 40 is connected to the heater 25 and the plurality of drive motors 26, 27, 28, 39, 61, 65, and rotates the screw 24, performs the injection operation by the forward drive of the screw 24, Each of the operations such as the mold opening operation, the mold thickness adjusting operation of the mold clamping device 35, the advance / retreat drive of the injection device 20, and the forward / reverse operation of the push pin 62 are controlled.

  The control device 40 includes, for example, a detection unit 41 that detects an output value (load current) F output to each of the drive motors 26, 27, 28, 39, 61, and 65 and measures a time during which the current flows. Based on the detection result at 41, the calculation unit 42 for obtaining the estimated heat generation amount T of each drive motor 26, 27, 28, 39, 61, 65, and whether or not the estimated heat generation amount T is equal to or greater than the preset value T1. Determination unit 43 for determining, and control for driving by limiting output F of drive motor to less than limit output value F2 when estimated heat generation amount T is greater than first set value T1 or greater than or equal to first set value T1 Part 44.

  Further, the injection molding machine 10 is provided with a display unit 51 that displays a load factor calculated by the control device 40 and a warning display. Furthermore, a speaker 52 that emits a warning sound is also provided.

  Hereinafter, the operation of the electric injection molding machine according to the present embodiment will be described.

  The control device 40 drives the heater 25 to heat the plasticizing barrel 21. The temperature of the plasticizing barrel 21 is detected by a temperature sensor or the like and sent to the control unit 40. When the temperature of the plasticizing barrel 21 reaches the set value, the control device 40 operates the hopper 22 to supply the pellet-shaped material R, and controls the rotation drive motor 26 to rotate the screw 24. .

  With the above operation, in the injection device 20, the material R is drawn into the plasticizing barrel 21 by the rotation operation of the screw 24 and the heating of the heater 25, and is melted and kneaded. Further, when the screw 24 rotates, the material R is sent to the tip end side of the screw 24.

  The fed molten material is stored at the tip of the screw 24 (near the nozzle), and the screw 24 is pushed back by the pressure of the stored molten material.

  That is, the screw 24 is moved backward by the pressure of the molten material stored at the tip of the screw 24. At this time, a measuring torque applied to the screw 24 is detected, and a measuring operation for measuring the molten material is performed. That is, when the screw 24 is pushed back by a predetermined amount (to the measurement completion position), the rotation drive motor 26 stops rotating, and the screw 24 stops rotating to complete the measurement.

  In parallel with the weighing operation, the control device 40 drives the mold clamping drive motor 39 to move the moving platen 37 via the toggle mechanism 38, thereby closing the mold 30 (clamping). Further, the control device 40 drives the advance / retreat drive motor 28 to bring the injection device 20 close to the mold 30 and to connect the discharge part 21 b to the cavity 33 of the mold 30.

  Then, the injection drive motor 27 is driven to advance the screw 24, thereby performing an injection operation of injecting the molten material into the mold 30 from the discharge portion 21b. When the injection operation is completed, the control device 40 drives the mold clamping drive motor 39 to open the mold 30 at a predetermined timing when the molding is completed, and retracts the injection device 20 from the mold 30 by the advance / retreat drive motor 28.

  Further, when the operation of opening the mold 30 is completed, the control device 40 drives the drive motor 61 for extrusion, causes the push pin 62 to protrude from the movable die 32, and pushes out the molded product. When the molded product is taken out by a carry-out device (not shown), the control device 40 drives the pushing drive motor 61 to return the pushing pin 62 to a predetermined return position.

  Thus, the injection molding operation in one cycle is completed. The continuous injection molding operation includes driving the advance / retreat drive motor 28 at the start of continuous injection molding to bring the injection device 20 close to the mold 30 and communicating the discharge part 21b with the cavity 33 of the mold 30; At the end of molding, the advance / retreat drive motor 28 is driven to retract the injection device 20 from the mold 30 only once during continuous injection molding, and other operations, that is, mold clamping to the mold 30 is performed. Operation, material injection operation (injection filling operation and pressure holding operation), cooling operation (molding and solidifying operation), mold opening operation for mold, extrusion / extraction operation of molded product, material weighing operation are continuous as cycle operation By repeating the steps, the molded products are sequentially manufactured.

  Further, when the mold 30 is replaced, the control device 40 drives the mold thickness adjusting drive motor 65 after the new mold 30 is attached to the mold clamping device 35, so that the new mold 30 In addition, the mold thickness is adjusted by moving the link housing 66 so that a predetermined clamping force can be obtained when the mold 30 is closed.

  In this injection molding operation, the control device 40 constantly monitors the heat generation amount T of each motor 26, 27, 28, 39, 61, 65, and provides a predetermined preset value T1 within a range where the protection stop function of the motor does not operate. When the heat generation amount T of the drive motor reaches a pre-load state where the pre-set value T1 is equal to or greater than the pre-set value T1, the output current to the drive motor is controlled to be less than the rated output to control the load increase.

  As shown in the flow of FIG. 2, the control device 40 constantly monitors the amount of heat generated during the injection molding operation or during the mold thickness adjustment (ST1). As an example of the calorific value calculation method, for example, the detection unit 41 constantly detects the load current F that is the output of each motor 26, 27, 28, 39, 61, and 65. Estimated calorific value T is calculated. As the detection of the load current F, for example, an average load amount detected for each molding cycle, a peak load rate for detecting an instantaneous overload, or an average load amount per unit time is used.

The estimated heat generation amount T is proportional to the motor current. This motor current is obtained by the equation I = (Iq ² + Id ² ) ^1/2 where I is the motor current, Iq is the effective current, and Id is the reactive current.

The estimated heat generation amount T is obtained by accumulating the square (I ² ) of the motor current I as shown in FIG. Note that the estimated heat generation amount T does not increase when the motor current I is equal to or less than the reference current Ibase.

  Then, in the determination unit 43, it is determined whether or not the estimated heat generation amount T is equal to or greater than a predetermined protective function overload set value T0 (ST2). If it is determined that the estimated heat generation amount T is equal to or greater than the overload set value T0, the control unit 44 activates the protection function to stop the drive motor, and overload is stopped (ST3).

  When the estimated heat generation amount T is less than the overload set value T0, the determination unit 43 determines whether or not it is greater than or equal to the preliminary set value T1 (first predetermined value) (ST4). The preliminary set value is set in advance corresponding to a predetermined heat generation amount that is lower than the overload set value T0 and requires output limitation. When it is determined that the estimated heat generation amount T is greater than or equal to the preset value T1, the output that restricts the output of the drive motor by the control unit 44 to be less than or less than a preset limit output value F2 (second predetermined value). The adjustment is performed (ST5), the limiting operation is continued, and the process returns to ST1. The limited output value F2 is, for example, a value less than or less than the rated output, and in this embodiment, the limited output value F2 is the rated output.

  On the other hand, when the estimated heat generation amount T is less than the preliminary set value T1, the determination unit 43 determines whether or not it is greater than or equal to the alarm set value T2 (second value) (ST6). The alarm set value T2 is lower than the overload set value T0 and the preliminary set value T1, and is set in advance corresponding to a predetermined heat generation amount that requires a warning report.

  When it is determined that the estimated heat generation amount T is equal to or greater than the alarm set value T2, an alarm unit such as the speaker 52 or the display unit 51 is activated to issue an alarm (ST7), and the operation is performed with the set output value Fb. Continue to ST1. For example, as a warning, a warning screen is displayed on the display unit 51, or a warning sound is emitted from the speaker 52 to notify the worker.

  On the other hand, if it is less than the alarm set value T2, the operation is continued at the set output value Fb without issuing an alarm (ST8), and the process returns to ST1.

  In addition, also when it adjusts to the limit output value F2 below a rated current by ST5, it returns to ST1 after adjustment. Therefore, if the estimated heat generation amount T decreases and becomes less than the preset value T1, the process proceeds to ST6 to ST8, the output adjustment (limit) is released, and the engine is operated with the set output value Fb.

  According to the present embodiment, the following effects can be obtained. That is, before reaching the overload set value T0 that is the target of the stop of the protection function, when the pre-set value T1 with a smaller load is reached, the current value is limited and the operation is continued to stop the protection. Can be avoided.

  Therefore, in addition to the steady overload motor stop of each drive motor, the motor stop at the momentary overload due to the overload due to the heating of the drive motor and the sudden motor load increase due to the gate clogging at the injection is suppressed in advance. It becomes possible. As a result, the productivity of the molded product can be improved.

  Further, when current limiting is performed, there may be a problem in molding such as a short shot. In the above embodiment, a warning is set by setting an alarm set value T2 smaller than the preset value T1 for limiting the current. Thus, it is possible to prompt the operator to change the setting in advance.

  FIG. 3 is a graph showing an example of the transition of the load current of the injection drive motor 27. In this example, as indicated by R1 in FIG. 3, since the alarm set value T2 has been exceeded, an alarm display is performed. In this graph, even after the alarm set value T2 is exceeded, the amount of generated heat further increases and exceeds the preset value T1, so that the current is limited and the amount of generated heat is reduced. On the other hand, R2 in FIG. 3 shows a graph when current limitation is not performed. In this case, since the heat generation amount exceeds the overload set value T0, the motor stops.

  FIG. 4 is a graph showing the motor overload withstand characteristics, showing the load current with respect to time. The left side of the graph is the instantaneous overload capability. That is, this graph shows that the motor protection function is achieved when the overload limit value is reached even for a short time.

  The load current A is obtained by the equation A = (K / t) + Abase, where K is the motor overload capability, Abase is the base current, and t is the time. Further, the motor overload tolerance K is obtained by accumulating a current exceeding the reference current Abase. The overload limit value in FIG. 4 indicates the area where the motor protection function works at the maximum current Amax. Even if the motor current is the maximum current Amax, the motor protection function does not work unless it exceeds the time tm for reaching the motor overload tolerance K. On the other hand, even when the load current An is smaller than the maximum current Amax, the motor protection function is activated after the time tn when the motor overload tolerance K is reached.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of this invention. In addition, the specific configuration of each part, the specific control procedure in each process, and the like are not limited to those illustrated in the above embodiment, and can be changed as appropriate. Furthermore, the present invention can be realized even if some of the constituent features of the above-described embodiment are omitted.

For example, in the said 1st Embodiment, although illustrated about the case where it applies to an injection molding machine, it is not restricted to this, Die casting machine, transfer molding machine, glass molding machine, extrusion molding machine, compression molding machine (press molding) Etc.) and can be applied to various molding apparatuses.

  Moreover, in the said embodiment, although the control method of the injection drive motor was illustrated among several drive motors provided, it is not restricted to this, Any one of the several drive motor provided in a shaping | molding apparatus Alternatively, the same current limit control may be performed for each of the plurality of drive motors.

  As a modification of the control method, instead of or in addition to the comparison with the set value T1, the load current F detected by the control device 40 is recorded by overwriting to record the change in the load current F. Alternatively, the average load current may be recorded as a reference graph, and output control may be performed by comparing with the detected value for each cycle. In addition, the set value or the control expression may be changed by predicting an increase in load from a change in load amount during continuous operation.

  For example, as shown in FIG. 6, the load factor is recorded for each shot, the moving average is taken, and the next load factor is calculated. In this method, the next load factor is obtained by the following load factor = current load factor + (current load factor−previous load factor) × change coefficient. If the next load factor exceeds the corrected load factor, the cycle time is extended.

  Moreover, in the said embodiment, although the determination part and the control part were performed based on the estimated calorific value, this invention is not limited to this. For example, the determination unit and the control unit may be performed based on a load current that is an output of each motor. As an operation method thereof, the determination unit and the control unit of the above-described embodiment can be performed by replacing the portion of the estimated heat generation amount with a load current that is an output of each motor.

  In the above embodiment, the control standard is that each set value is greater than or equal to each set value, and control is switched between each set value and less than each set value. It is good also as a reference | standard of control.

  In addition, the fixed information of the calendar and the machine installation area season and daily temperature change is recorded, and the above control is performed considering the difference between these condition values, the recording date and time of the reference graph, and the current molding temperature. You may change the setting value and control formula used for.

  For example, as shown in FIG. 5, the accumulated heat generation amount is normally rounded down as shown in FIG. 5, but this is corrected according to the outside air temperature. As shown in FIG. 7, when the outside air temperature is low, the minus side is partially accumulated as a whole, and when the outside temperature is high, the plus side is partially truncated as a whole. That is, when the outside air temperature is low, the overload capacity of the motor increases, and when the outside temperature is high, the overload capacity of the motor decreases.

  For example, in addition to the average load factor, the peak load factor may be detected and recorded so as to provide reference data for cycle time adjustment. For example, by detecting an increase in the average load factor for each cycle, it is possible to reduce the increasing load by limiting the current before the motor protection function is activated.

  As shown in FIG. 8, when the load factor of the next shot is expected to exceed the current limit load factor, the load can be reduced by lowering the upper limit of the maximum current.

  T ... Estimated calorific value, T1 ... Preliminary set value (first predetermined value), F ... Load current (output value), T0 ... Overload set value, F2 ... Limit output value (second predetermined value), T2 ... Alarm setting value, Fb ... reference output value, 10 ... injection molding machine (molding device), 20 ... injection device, 21 ... plasticizing barrel, 24 ... screw, 25 ... heater, 26 ... rotation drive motor (electric motor), 27 ... Injection drive motor (electric motor), 28 ... advance / retreat drive motor (electric motor), 30 ... mold, 35 ... mold clamping device, 39 ... mold clamping drive motor (electric motor), 40 ... control device, 41 ... detector, 42 ... calculation , 43 ... determination part, 44 ... control part, 51 ... display part (alarm part), 52 ... speaker (alarm part), 61 ... drive motor for extrusion (electric motor), 65 ... drive motor for mold thickness adjustment (electric motor) .

Claims (7)

A method for controlling an electric motor used in a molding apparatus,
Detecting the output of the motor;
Obtain an estimated calorific value of the electric motor based on the output,
Limiting the output of the motor to a second predetermined value or less or less than a second predetermined value when the estimated heat generation amount is equal to or higher than a first predetermined value or exceeds a first predetermined value;
A method for controlling an electric motor.   The motor control method according to claim 1, wherein the second predetermined value is equal to or less than a rated output of the motor.   The motor control method according to claim 2, wherein the first predetermined value is set lower than a value at which a protection function of the motor operates. A method for controlling an electric motor used in a molding apparatus,
Detecting the output of the motor;
An electric motor characterized by limiting the output of the electric motor to a second predetermined value or less or less than a second predetermined value when the output is equal to or higher than a first predetermined value or exceeds a first predetermined value. Control method. A control device for an electric motor used in a molding device,
A detector for detecting the output of the electric motor;
A calculation unit for obtaining an estimated calorific value of the electric motor based on the output;
A determination unit that determines whether the estimated heat generation amount is equal to or greater than a first predetermined value or exceeds a first predetermined value;
A limiting unit that limits the output of the motor to a second predetermined value or less or less than a second predetermined value when the estimated heat generation amount is equal to or higher than a first predetermined value or exceeds a first predetermined value; An electric motor control device comprising: A control device for an electric motor used in a molding device,
A detector for detecting the output of the electric motor;
A determination unit that determines whether or not the output is equal to or greater than a first predetermined value or exceeds a first predetermined value;
A control unit that limits the output of the motor to a second predetermined value or less or less than a second predetermined value when the output is equal to or higher than a first predetermined value or exceeds a first predetermined value. An electric motor control device.   A molding apparatus comprising the motor control device according to claim 5.

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