JP3818958B2 - Servo press motor overload protection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor overload protection method for preventing an overload abnormality of a slide drive servomotor during automatic press operation in a servo press in which a slide is driven by a servomotor via a predetermined power transmission mechanism.
[0002]
[Prior art]
The servo press that reciprocates the slide via a predetermined power transmission mechanism such as a ball screw, toggle link mechanism, crank mechanism or eccentric mechanism with a servo motor is used to control workpiece processing conditions by servo-controlling the position and speed of the servo motor. It has an excellent advantage that the slide can be controlled so that the slide motion conforms to the above. And, taking advantage of this advantage, high-precision molding can be performed, and productivity can be improved by increasing the number of strokes. (For example, see Patent Document 1 and Patent Document 2.)
[0003]
In the servo press as described above, when a workpiece is continuously processed in the automatic operation mode, the servo motor temperature gradually rises due to a load current that continuously changes in the servo motor. That is, the servo motor generates heat by energy corresponding to the work amount due to the effective output torque of the servo motor. Normally, the maximum allowable output current of a servo motor is limited by its ambient temperature and the motor's own temperature. Therefore, if the motor's own temperature exceeds a predetermined maximum allowable temperature, the servo motor's An alarm signal is output as an overload error by the servo amplifier thermal monitoring function. At this time, if the press controller inputs this overload abnormality signal, the press controller turns off the command to the servo amplifier and cuts off the main circuit power supply input to the servo amplifier to cut off the current output to the servo motor. I have to.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-277797
[Patent Document 2]
Japanese Patent Application No. 2002-175831
[0005]
[Problems to be solved by the invention]
However, in the above conventional servo press, once a motor overload abnormality occurs during the continuous operation of the press, the servo amplifier shuts off the motor current output and the main circuit power is turned off as described above. In order to release this overload abnormal stop of the amplifier, it is necessary to turn off the control power supply of the servo amplifier and then wait until the motor temperature falls below the specified value, and then turn on the control power supply and main circuit power supply again. It becomes. For this reason, once an overload abnormality alarm occurs, it takes time to restart the press operation, and productivity in automatic operation is reduced.
[0006]
In addition, if the servo motor suddenly stops due to an overload error during automatic operation, if the workpiece is being machined, not only will it produce a defective product, but it will also restart by raising the slide from the slide stopped state and waiting. The troublesome operation of returning to the point, discharging the defective product from the mold, and then restarting it is necessary, and there is also a problem that it takes time.
[0007]
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a motor overload protection method for a servo press that can prevent the occurrence of an overload abnormality of the servo motor even during automatic press operation.
[0008]
[Means, actions and effects for solving the problems]
  In order to achieve the above object, the first invention provides a servo motor (21).As the drive source,In a motor overload protection method of a servo press that drives a slide (3) via a power transmission mechanism,
  Detects the load current when the servo motor (21) is activated,
  InspectionMotor load current (In)Past valuesincludingFruitTo measurements, Taking into account the weighting factor to reduce the contribution according to the elapsed time from the measurement timeCalculate calorific value (Qn)
  When the obtained heat amount integrated value (Qn) exceeds the first heat amount integrated threshold value (Qs1), the slide (3) is moved to a region other than the molding region.PresetPause to position,
  After the slide (3) is temporarily stopped, if the heat integrated value (Qn) falls below a second heat integrated threshold (Qs2) set lower than the first heat integrated threshold (Qs1), the slide (3 ) Is suspended and restartedIt's a way.
[0009]
  According to the first aspect of the invention, the motor heat amount integrated value approximately proportional to the motor temperature is monitored, and the slide is moved when the motor heat amount integrated value reaches the predetermined first heat amount integrated threshold value.At a preset position other than the molding areaSince the motor temperature is lowered before the motor is temporarily stopped and an overload abnormality occurs, the occurrence of an overload abnormality during automatic operation can be prevented in advance. For this reason, the operation interruption for a long time accompanying the occurrence of an overload abnormality and the operation for restarting are eliminated, and the productivity and workability can be improved. Furthermore, there is no need to make defective products.Further, after the slide is temporarily stopped, when the motor heat amount integrated value falls below the second heat amount integrated threshold, the temporary stop is canceled and the operation is restarted, that is, the operation is resumed in the continuous operation mode, For example, in the external safety one-stroke mode, the system waits for a press activation request from the transfer feeder device, so that automatic operation can be continued. Thereby, automatic operation can be performed while monitoring the motor temperature and avoiding motor overload abnormality. Further, when the vehicle is temporarily stopped at the standby point, it is possible to easily resume the synchronous operation with the transfer feeder or the like.
  The molding area refers to a slide motion area in which a slide presses a workpiece to perform molding or a die cushion is pressed down.
[0010]
  The second invention is a servo motor (21).As the drive source,In a motor overload protection method of a servo press that drives a slide (3) via a power transmission mechanism,
  Detects the load current when the servo motor (21) is activated,
  InspectionMotor load current (In)Past valuesincludingFruitCalculate the calorific value (Qn) based on the measured value,
  When the calculated heat value (Qn) exceeds the first heat value threshold (Qs1), slide (3)thereOnce stopped,
  After this, if the detected current motor load current (In) is greater than or equal to a predetermined value, slide (3)PresetIt is a method of raising the distance and pausing.
[0011]
  According to the second aspect of the invention, the motor heat amount integrated value approximately proportional to the motor temperature is monitored, and thisMotor heat value integrated valueSlides when reaches the predetermined first heat accumulation thresholdthereWhen the current motor load current value is greater than or equal to a predetermined value, that is, when the servo motor is stopped with a pressurizing torque greater than or equal to the predetermined value, the motor load is reduced. SlidePresetSince the distance is increased and temporarily stopped, the motor load current can be reduced to a predetermined value or less before an overload abnormality occurs. Thereby, since motor temperature falls, generation | occurrence | production of the overload abnormality in automatic operation can be prevented beforehand. For this reason, the operation interruption for a long time accompanying the occurrence of an overload abnormality and the operation for restarting are eliminated, and the productivity and workability can be improved. Furthermore, there is no need to make defective products.
[0012]
  The third invention is the2In the invention, after pausing the slide,heatThe amount integrated value isSet lower than the first heat accumulation thresholdWhen the value falls below the second heat amount integration threshold, the slide is temporarily stopped and is restarted.
[0013]
According to the third aspect of the present invention, when the motor heat amount integrated value falls below the second heat amount integrated threshold, the temporary stop is canceled and the operation is restarted, that is, the operation is resumed in the continuous operation mode, In the safe one-stroke mode, the system waits for a press activation request from the transfer feeder device, so that automatic operation can be continued. Thereby, automatic operation can be performed while monitoring the motor temperature and avoiding motor overload abnormality. Further, when the vehicle is temporarily stopped at the standby point, it is possible to easily resume the synchronous operation with the transfer feeder or the like.
[0014]
  The fourth invention is the2In the invention, after a predetermined time has elapsed after the slide is paused, the slide is released from the pause state to be in a restart state.
[0015]
According to the fourth invention, after a temporary stop, when a predetermined time (a preset time required for the motor temperature to decrease by a predetermined amount) elapses, the operation is restarted (the same as described above), so automatic operation is continued it can. Thereby, automatic operation can be performed while monitoring the motor temperature and avoiding motor overload abnormality. Further, when the vehicle is temporarily stopped at the standby point, it is possible to easily resume the synchronous operation with the transfer feeder or the like.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0017]
First, the configuration of a servo press to which the present invention is applied will be described with reference to FIGS. 1 and 2 are a partial side sectional view and a partial rear sectional view of the servo press, respectively.
The press machine 1 is a servo press (hereinafter referred to as “servo press 1”), and the slide 3 is driven by a servo motor 21. A slide 3 is supported in a substantially central portion of the main body frame 2 of the servo press 1 so as to be movable up and down, and a bolster 5 mounted on a bed 4 is disposed at a lower portion facing the slide 3. A body portion of the screw shaft 7 for adjusting the die height is rotatably inserted into a hole formed in the upper portion of the slide 3 while being prevented from coming off. The screw portion 7 a of the screw shaft 7 is exposed upward from the slide 3 and is screwed into a female screw portion below the plunger 11 provided above the screw shaft 7.
[0018]
A worm wheel 8 a of a worm gear 8 is mounted on the outer periphery of the main body of the screw shaft 7, and the worm 8 b of the worm gear 8 screwed into the worm wheel 8 a is connected to the output shaft of the induction motor 9 attached to the back surface of the slide 3. It is connected via a gear 9a. The induction motor 9 is configured to be flat and compact by shortening the axial length.
[0019]
The upper portion of the plunger 11 is rotatably connected to one end portion of the first link 12a by a pin 11a, and one end portion is rotatably connected to the other end portion of the first link 12a and the main body frame 2. Two connecting holes provided on one side of the triaxial link 13 are rotatably connected by pins 14a and 14b to the other end of the second link 12b. The connection hole on the other side of the triaxial link 13 is rotatably connected to an eccentric shaft 28 of the slide drive unit 20 described later in detail. The first link 12a, the second link 12b, and the triaxial link 13 constitute a toggle link mechanism.
[0020]
A servo motor 21 for slide driving is attached to the side surface of the main body frame 2 with the axis centered in the left-right direction of the press. The first pulley 22a attached to the output shaft of the servo motor 21 and the servo motor 21 A belt 23 (usually composed of a timing belt) is wound between a second pulley 22b attached to an intermediate shaft 24 that is provided so as to be pivotable upward in the press horizontal direction. Yes. A drive shaft 27 is rotatably supported on the main body frame 2 above the intermediate shaft 24, and a gear 26 attached to one end side of the drive shaft 27 meshes with a gear 25 attached to the intermediate shaft 24. Yes. An eccentric shaft 28 is formed at a substantially central portion in the axial direction of the drive shaft 27, and the other side of the triaxial link 13 is rotatably connected to an eccentric position of the outer peripheral portion of the eccentric shaft 28. .
[0021]
In addition, an oil chamber 6 is formed in the slide 3 so as to be sealed between the lower end surface portion of the screw shaft 7, and the oil chamber 6 passes through an oil passage 6 a formed in the slide 3. Connected to the switching valve 16. The switching valve 16 switches supply and discharge of the operating oil into the oil chamber 6. The operating oil supplied into the oil chamber 6 through the switching valve 16 is closed in the oil chamber 6 during press processing, and the pressing force during pressurization is transmitted to the slide 3 via the oil in the oil chamber 6. I have to. When an overload is applied to the slide 3 and the oil pressure in the oil chamber 6 exceeds a predetermined value, the oil is returned from a relief valve (not shown) to the tank, the slide 3 is cushioned by a predetermined amount, and the slide 3 and the mold are not damaged. It has become.
[0022]
A pair of brackets 31, 31 protruding from two upper and lower portions toward the side surface of the main body frame 2 are attached to the back surface of the slide 3, and a position detection rod is interposed between the pair of upper and lower brackets 31, 31. 32 is attached. A body portion of a position sensor 33 such as a linear scale is fitted in the position detection rod 32 provided with a position detection scale portion so as to be movable up and down. The position sensor 33 is fixed to an auxiliary frame 34 provided on the side surface of the main body frame 2. The auxiliary frame 34 is formed vertically long in the vertical direction, the lower part is attached to the side surface portion of the main body frame 2 by bolts 35, and the upper part is slid in the vertical direction by bolts 36 inserted in vertical elongated holes (not shown). The side part is supported and freely contacted and supported by a pair of front and rear support members 37, 37.
[0023]
The auxiliary frame 34 has a structure in which only one of the upper and lower sides (the lower side in this example) is fixed to the main body frame 2 and the other side is supported to be movable up and down. It has become unaffected. Thereby, the position sensor 33 can accurately detect the slide position and the die height without being affected by expansion and contraction due to a temperature change of the main body frame 2.
[0024]
Next, the hardware configuration of the control device will be described based on the control configuration block diagram shown in FIG.
This control apparatus includes a controller 10, a memory 10a, a monitor display 19, a current sensor 29, a position sensor 33, a servo amplifier 45, and a servo motor 21 for slide driving.
[0025]
The current sensor 29 detects the load current of the servo motor 21 and outputs the detected current value to the controller 10.
The position sensor 33 outputs the detected slide position to the controller 10.
[0026]
The memory 10 a stores preset slide motion data and table data representing the relationship between the slide position and the rotation angle of the servo motor 21. This relationship is determined by the eccentric length of the eccentric shaft 28, each link length of the toggle link mechanism, the relationship between the rotational center position of the eccentric shaft 28 and the toggle link, and the like.
[0027]
The monitor display 19 is based on a display command from the controller 10, and various monitor information such as a current slide position (height), a motor load current value at this time, and a calculated value of the motor load state, an alarm message, etc. Is displayed. This display can be constituted by a numerical display such as LED, a character display such as liquid crystal, a graphic display, or the like.
[0028]
And the controller 10 is comprised from high-speed arithmetic devices, such as a computer apparatus and PLC (it is a programmable logic controller, what is called a programmable sequencer). The controller 10 refers to the slide position / motor rotation angle correspondence table stored in the memory 10a and creates a slide motion for control based on preset motion data. When in the continuous operation mode, A calculation process is performed so that the slide moves in accordance with the created motion, and a speed command of the servo motor 21 is obtained based on a deviation value between the target position and the position input from the position sensor 33 to the servo amplifier 45. Output. In the inching mode or the safe one-stroke mode, only when the operation button switch (not shown) is being operated (however, in the safe one-stroke mode, when the bottom dead center is passed, it continuously rises to the top dead center regardless of the operation button operation. The speed command of the servo motor 21 is obtained based on the deviation value between the target position and the position input from the position sensor 33 so that the slide moves at a predetermined speed, and is output to the servo amplifier 45.
[0029]
Further, while the servo motor 21 is driven as described above, the controller 10 inputs the load current value of the servo motor 21 being driven from the current sensor 29, and will be described later based on this load current value. The motor load state is monitored by predetermined arithmetic processing, and the servo motor 21 is raised by a predetermined distance before the overload state is reached to reduce the load, thereby preventing the occurrence of motor overload abnormality. Further, various information such as the current slide position, servo motor current value, overload state, etc. are monitored, and a display command is output to the monitor display 19.
[0030]
The servo amplifier 45 is fed back with a motor rotation angle from a servo motor rotation angle sensor (not shown). The servo amplifier 45 calculates a deviation value between the speed command from the controller 10 and a speed feedback signal obtained from the motor rotation angle, and controls the servo motor 21 to reduce the deviation value based on the obtained deviation value. To do. Thereby, the position and speed of the slide are controlled with high accuracy.
[0031]
Next, based on the control flowchart shown in FIG. 4, the processing procedure of the first embodiment of the motor overload protection method according to the present invention will be described with reference to FIG. FIG. 5 is a time chart of a slide position, a motor generated torque, and a heat amount integrated value by the motor overload protection method according to the first embodiment.
In FIG. 4, first, in step S1, the first heat quantity integration threshold value Qs1 and the second heat quantity integration threshold value Qs2 are set to predetermined values. As shown in FIG. 5, the first heat accumulation threshold value Qs1 is a threshold value for checking the timing for performing the temporary stop control for the motor overload protection. A predetermined amount (corresponding to the margin) is set to a value smaller than the maximum allowable heat amount integrated value corresponding to the overload abnormality. The second heat accumulation threshold value Qs2 is a threshold value for checking the timing of releasing the temporary stop and restarting, and corresponds to the temperature when the motor temperature is lowered by a predetermined temperature from the temperature at the time of the temporary stop. . It should be noted that the relationship of the first heat accumulation threshold value Qs1 ≧ the second heat accumulation threshold value Qs2 may be set. It is desirable that the integration threshold value Qs1> the second heat quantity integration threshold value Qs2. Then, the measured current value tables I1 to In used for the following arithmetic processing are initialized (cleared). Here, n is the number of data of such a magnitude that the heat quantity integrated value Qn obtained by the following calculation can equivalently represent the motor temperature.
[0032]
Next, in step S2, the current value In during operation of the servo motor 21 is detected, and this is stored in In of the measured current value tables I1 to In. Further, in step S3, the equation “Qn = ΣIn · Kn” is used. The calorie integrated value Qn is calculated. Here, Kn (n = 1 to n) is a weighting coefficient whose contribution is reduced in accordance with the elapsed time from the measurement time point, and 0 ≦ Kn−1 ≦ Kn. Thereafter, in step S4, the data of the measured current value tables I1 to In are shifted as “In-1 ← In”. As a result, the oldest measured data I1 is deleted. Then, in step S5, it is checked whether the obtained heat amount integrated value Qn is greater than or equal to the first heat amount integrated threshold Qs1, and if it is not greater than or equal to the first heat amount integrated threshold Qs1, the process returns to step S2 and the above processing is repeated.
[0033]
When the first heat amount integration threshold Qs1 or more is reached in step S5, the process proceeds to step S6, and the slide is temporarily stopped at a predetermined position other than the molding region (for example, a preset standby point or top dead center). At the same time, an alarm message such as “Paused” is displayed on the monitor display 19. Note that “temporarily stopped” may be notified by voice. Thereafter, the current value In of the servo motor 21 is detected in step S7, and this is stored in In of the actually measured current value tables I1 to In. Next, in step S8, the mathematical expression "Qn = ΣIn" similar to the previous expression is stored. Calculate the calorific value Qn by “Kn”, and further shift the data in the measured current value tables I1 to In as “In-1 ← In” in Step S9, and then proceed to Step S10 to change to this new It is checked whether the calorific value integrated value Qn obtained in (1) has fallen below the second calorific value integrated threshold Qs2. If it has not fallen below the second heat accumulation threshold value Qs2, the process returns to step S7 and the above processing is repeated. Then, the process returns to step S2 to repeat the process.
[0034]
The slide restart state in step S11 is, for example, a state in which continuous operation is resumed in the case of automatic operation and continuous operation mode, and the external safety operation is performed in synchronization with a transfer feeder such as a transfer press. In the stroke mode, if there is a press activation request signal from the transfer feeder device, the activation request waiting state can be activated.
[0035]
Next, the operation according to the above method will be described with reference to FIG.
In FIG. 5, it is assumed that the operation button is operated in the continuous operation mode at time t0 and the press is continuously activated. Since the controller 10 controls the position and speed of the servo motor 21 so that the slide moves along a preset slide motion, the load current is applied to the servo motor 21 in a pattern corresponding to the slide motion. Flowing. As the load current corresponding to the one-cycle operation of the slide (cycle time Tc) continuously flows every cycle, the temperature of the servo motor 21 gradually increases. The controller 10 measures the motor current value In during this time, and based on the actual data of the motor current value In so far, based on the actual data “Qn = ΣIn · Kn”, the heat amount integrated value Qn (which is approximately proportional to the motor temperature rise). (Step S2, 3). Then, during continuous operation, it is checked whether or not the heat amount integrated value Qn obtained this time has become equal to or greater than a predetermined first heat amount integrated threshold Qs1 (step S5). The above processing is continued until reaching. Note that, in the calculation of the calorific value Qn, the past current actual measurement value reduces the contribution to the temperature rise according to the elapsed time by the weighting coefficient Kn (step S4).
[0036]
When the heat amount integrated value Qn obtained this time becomes equal to or greater than the first heat amount integrated threshold Qs1 at time t2, the cycle during the current operation is completed, and then the slide is temporarily placed at a predetermined position other than the forming region at time t3. Stop (step S6). As a result, the load current of the servo motor 21 is reduced to a small current required for position holding, and the decrease of the heat integrated value Qn, that is, the temperature of the servo motor 21 and the high power semiconductor element of the power circuit in the servo amplifier is rapidly increased. To lower. Thereafter, the motor current value In is continuously monitored, and the heat amount integrated value Qn is obtained based on the motor current value In detected every predetermined calculation processing cycle time and the past value data of the motor current (step S7, 8, 9), the temporary stop is continued until the obtained latest heat integrated value Qn falls below the second heat integrated threshold Qs2 (step S10). Then, when the heat amount integrated value Qn falls below the second heat amount integrated threshold Qs2 (time t4 in FIG. 5), the slide is brought into a restart state (step S11).
[0037]
In the above-described embodiment, the eccentric shaft 28 is rotated by the servo motor 21 and the slide press is driven by this rotational power via the toggle link mechanism. The configuration is not limited, and for example, a direct-acting servo press in which the ball screw is directly moved by a servo motor and the slide is directly moved by this direct power, or an eccentric rotation drive such as a crank mechanism or an eccentric mechanism is driven by the servo motor. The present invention can also be applied to a servo press that drives a slide up and down through a section and a connecting rod, or a servo press that drives a toggle link mechanism with a ball screw.
[0038]
In the embodiment, the magnitude of the heat amount integrated value obtained by calculation based on the actual data of the motor load current value is monitored, but the motor temperature may be monitored instead of the heat amount integrated value.
The condition for releasing the temporary stop and restarting is not limited to the method for determining whether the motor temperature (heat integrated value) is equal to or lower than the predetermined second heat integrated threshold Qs2 as described above. You may make it restart after the time which can reduce temperature (heat amount integrated value) only by the predetermined amount passes.
[0039]
Next, a second embodiment will be described with reference to FIGS. The control configuration in the second embodiment is the same as that shown in FIG.
First, the processing procedure of the second embodiment will be described with reference to FIG. FIG. 6 is a control flowchart according to the second embodiment. In FIG. 6, steps having the same processing contents as those in FIG. 4 are denoted by the same step numbers and description thereof is omitted.
[0040]
From step S1 to step S5, processing is performed in the same procedure as in the first embodiment. In step S5, it is checked whether the calculated heat amount integrated value Qn is equal to or greater than the first heat amount integrated threshold Qs1, and when it is equal to or greater than the first heat amount integrated threshold Qs1, in step S21, Also stop. Next, in step S22, the current value Is while the servo motor 21 is stopped is detected, and in step S23, it is checked whether the current value Is is equal to or greater than a predetermined allowable value Ir. Shifting to S6, the current temporary stop position of the slide 3 is continued. When the current value Is is greater than or equal to the predetermined allowable value Ir in step S23, the servomotor 21 is driven by a predetermined amount in a direction in which the motor load is reduced in step S24, that is, the slide 3 is moved a predetermined distance from the stop position at this time. Raise. Thereafter, the slide 3 is temporarily stopped in the step S6, and the processes from the step S7 to the step S11 are performed thereafter.
[0041]
Next, the operation according to the second embodiment will be described with reference to FIG.
As in the first embodiment, when the press is operated in the continuous operation mode from time t0, a load current flows in the servo motor 21 in a pattern corresponding to the slide motion, and accordingly, the temperature of the servo motor 21 is increased. Increasing gradually. During this time, the controller 10 measures the motor current value In, and calculates the integrated amount of heat Qn according to the formula “Qn = ΣIn · Kn” based on the past data of the motor current value In (steps S2 and S3). Then, during continuous operation, it is checked whether or not the heat amount integrated value Qn obtained this time has become equal to or greater than a predetermined first heat amount integrated threshold Qs1 (step S5). The above processing is continued until reaching.
[0042]
Thereafter, at time t2, when the heat amount integrated value Qn obtained this time becomes equal to or greater than the first heat amount integrated threshold Qs1, the servo motor 21 is temporarily stopped on the spot even during the pressurizing process with the slide 3 ( Step S21). Next, it is checked whether the stopped motor current value Is is equal to or greater than a predetermined allowable value Ir (steps S22 and S23). When the motor current value Is is equal to or greater than the allowable value Ir, the servo motor 21 is under a pressurizing torque. At t5, the slide 3 is raised by a predetermined distance (step S24), and after the pressure torque is not applied, the slide 3 is temporarily stopped (step S6). As a result, the load current of the servo motor 21 is reduced to a current as small as necessary for holding the slide position, thereby reducing the integrated heat quantity Qn, that is, the high power semiconductor element of the servo motor 21 and the power circuit in the servo amplifier. Reduce the temperature rapidly. Note that the subsequent restart procedure from the paused state is the same as that in steps S7 to S11, and a description thereof will be omitted.
[0043]
According to the second embodiment, the same effect as that of the first embodiment can be obtained, and further, the slide is stopped immediately when the heat amount integrated value exceeds the first heat amount integrated threshold Qs1, and thereafter, at a position where the motor load current is small. In order to temporarily stop the slide, the first heat accumulation threshold Qs1 only needs to have a small margin with respect to the allowable heat amount that would lead to an overload abnormality. Can be used to the limit.
[0044]
According to the present invention, the following effects can be obtained.
A first heat integration threshold value Qs1 corresponding to a temperature lower by a predetermined amount than the maximum allowable motor temperature at which motor overload abnormality occurs is set in advance, and the motor is operating (when a load current flows to hold the slide stop position) And a motor load current value measured every predetermined measurement cycle time is weighted according to the elapsed time and integrated to obtain a calorific value integrated value Qn equivalently representing the motor temperature rise, When the sequentially obtained heat amount integrated value Qn exceeds the set first heat amount integrated threshold Qs1, the slide is temporarily stopped to lower the motor temperature. For this reason, during automatic operation such as continuous press operation mode and external safe one-stroke mode operation, the motor temperature is lowered by temporarily stopping the slide before the motor overload error occurs. Thus, the restart operation after the occurrence of the motor overload abnormality as shown in the prior art becomes unnecessary, and the operability and workability can be improved.
[0045]
Further, unlike the conventional case, it is no longer possible to produce defective products by stopping the slide due to the occurrence of an overload abnormality during workpiece processing. Furthermore, when the slide pause position is at the slide standby point or top dead center, the linked operation with the transfer feeder is easy, and automatic operation is possible.
Furthermore, since the alarm message such as “Paused” is displayed on the monitor display 19 during the pause due to the temperature rise, the operator can easily grasp the cause of the stop and give a sense of security.
[Brief description of the drawings]
FIG. 1 is a partial side sectional view of a servo press to which the present invention is applied.
FIG. 2 is a partial rear sectional view of a servo press to which the present invention is applied.
FIG. 3 is a control configuration block diagram according to the present invention.
FIG. 4 is a control flowchart according to the first embodiment.
FIG. 5 is a time chart according to the motor overload protection method according to the first embodiment.
FIG. 6 is a control flowchart according to the second embodiment.
FIG. 7 is a time chart according to a motor overload protection method according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Servo press, 3 ... Slide, 4 ... Bed, 5 ... Bolster, 6 ... Oil chamber, 7 ... Screw shaft, 9 ... Induction motor, 10 ... Controller, 10a ... Memory, 11 ... Plunger, 12a ... First link , 12b ... second link, 13 ... triaxial link, 16 ... switch valve, 19 ... monitor display, 20 ... slide drive, 21 ... servo motor, 22a ... first pulley, 22b ... second pulley, 23 ... belt , 27 ... drive shaft, 28 ... eccentric shaft, 29 ... current sensor, 33 ... position sensor, 34 ... auxiliary frame, 45 ... servo amplifier.

Claims (4)

In a motor overload protection method for a servo press that uses a servo motor (21) as a drive source and drives a slide (3) via a power transmission mechanism,
Detects the load current when the servo motor (21) is activated,
The test out motor load current (In), the real Hakachi including past values, the amount of heat accumulated value by adding a weighting factor to reduce its contribution in accordance with the elapsed time from the measurement time points (Qn) Seeking
When the calculated heat integration value (Qn) exceeds the first heat integration threshold (Qs1), the slide (3) is temporarily stopped at a preset position other than the molding region ,
After the slide (3) is temporarily stopped, if the heat integrated value (Qn) falls below a second heat integrated threshold (Qs2) set lower than the first heat integrated threshold (Qs1), the slide (3 The motor overload protection method of the servo press, wherein the temporary stop is released and the system is restarted . In a motor overload protection method for a servo press that uses a servo motor (21) as a drive source and drives a slide (3) via a power transmission mechanism,
Detects the load current when the servo motor (21) is activated,
Test out motor load current (In), calculated heat quantity integrated value (Qn) based on the actual measurement values including past values,
When the calculated heat value integrated value (Qn) exceeds the first heat value integrated threshold value (Qs1), the slide (3) is temporarily stopped on the spot ,
Thereafter, when the detected current motor load current (In) is equal to or greater than a predetermined value, the slide (3) is raised by a preset distance to be temporarily stopped. The motor overload protection method for a servo press according to claim 2 ,
Wherein after a pause the slide (3), the heat amount accumulated value (Qn) is, when falls below is set lower than the first heat accumulation threshold (Qs1) second heat accumulation threshold (Qs2), the slide ( 3) A motor overload protection method for a servo press, wherein the temporary stop in 3) is released and the system is restarted. The motor overload protection method for a servo press according to claim 2 ,
A method for protecting a motor overload of a servo press, wherein a predetermined time elapses after the slide (3) is paused, and the slide (3) is released from being paused to be restarted.

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