JPH11267854A - Method and device for driving control of welding gun arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of vibration to a gun arm in the collision in one sequential action that the gun arm is displaced in a direction for approaching a work and is stopped after the collision to the work so as to press the work. SOLUTION: When first and second gun arms 12, 14 are approaching to works W1, W2, a current value I to be supplied to a motor 20 which drives the first and second gun arms 12, 14 is obtained based on the deviation between the setting rotational velocity V0 and the actual rotational velocity V of the motor 20. When the first and second gun arms 12, 14 are collided to the works W1, W2, the current value I is obtained based on the formula I=(1-V/V0)×Ic from the setting rotational velocity V0 and the actual rotational velocity V of the motor 20 and the setting limit value Ic to set an upper limit value of the current value I to be supplied to the motor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control apparatus and a drive control method for a welding gun arm for controlling the drive of a gun arm constituting a welding apparatus.

[0002]

2. Description of the Related Art In general, a resistance welding machine for applying a voltage (current) to a work to weld the work has a pair of gun arms for sandwiching a portion where the work is to be welded and applying pressure. Have been. The gun arm is provided with a driving device, which is displaced toward or away from each other under the urging action of the driving device. Conventionally, a hydraulic cylinder has been used as this drive device.

[0003]

By the way, an electric motor can be used as the driving device instead of a fluid pressure type cylinder.

The present invention relates to a drive control device and a drive control method for a welding gun arm constituted by using this electric motor, and relates to a drive control method and a drive control method in which a gun arm is displaced in a direction approaching a work and stops after colliding with the work. An object of the present invention is to provide a drive control device and a drive control method for a welding gun arm that can appropriately control an operation of pressing a work.

[0005]

In a drive control apparatus for a welding gun arm according to the present invention, a motor for driving a welding gun arm is provided by a first arithmetic unit, the difference between a set speed of the motor and an actual rotation speed. Is controlled by the current value obtained from the above or by the second calculating means from the set speed, the rotation speed and the predetermined set current value based on a predetermined calculation formula.

In this case, the motors can be driven in different operation modes. For example, when the gun arm is moved at a high speed, the motor is supplied with the current value from the first calculating means, so that the motor can be driven. Is rotated with high responsiveness to a set speed, the moving time of the gun arm can be reduced, and when the gun arm collides with a workpiece, the current value from the second calculating means is supplied to the motor. By supplying the current, the current value can be set so that the impact generated at the time of the collision is reduced.

The current value from the first calculating means and the current value from the second calculating means may be switched by a switching means (the invention according to claim 2). Further, the switching operation of the switching means may be performed at a predetermined timing based on the set speed and the rotation speed based on a signal output from the timing detecting means (the invention according to claim 3). In this case, the operation mode of the motor can be easily switched according to the operation schedule of the motor.

[0008] Further, a calculation for obtaining a current value in the second arithmetic means is performed by determining that the current value changes in an inclined manner with respect to a change in the rotation speed of the motor, and that the rotation speed is changed to a set speed of the motor. When the rotation speed is 0, the current value is set to 0 when the rotation speed is 0, and the current value is set to the set current value. Invention).

In this case, the torque generated in the motor as the motor decelerates increases from 0 in an inclined manner.
For example, when the gun arm collides with the workpiece, a large torque is instantaneously generated in the motor, and a large impact is prevented from being applied to the gun arm or the workpiece.

The calculation of the current value in the second calculating means may be performed based on the following equation: I = (1−V / V0) × Ic (the invention according to claim 5). In this case, the current value can be obtained by a simple calculation formula, and simplification of the configuration of the second calculation means and shortening of the calculation time are realized.

[0011] Next, in the invention according to claim 6, a series of operations for stopping the gun arm after approaching and colliding with the work and pressurizing the work include an approaching step in which the gun arm approaches the work, The operation mode of the motor is changed at a collision stop stage in which the gun arm collides with the workpiece and stops.

In this case, in the approaching step, for example, an operation mode in which the gun arm can be moved at a high speed is selected, and in the collision stopping step, for example, an impact generated when the gun arm collides with the work is reduced. In addition, by selecting an operation mode capable of shortening the time required for shifting from the collision to the pressurization, the welding time can be shortened, and the collision does not reduce the welding quality. Is done.

In the approaching step, a current value to be supplied to the motor is obtained based on a deviation between a set rotation speed of the motor and an actual rotation speed. It may be determined from the actual rotation speed and a predetermined set current value based on a predetermined calculation formula (the invention according to claim 7).

In this case, in the approaching step, high responsiveness to the set speed of the rotation speed of the motor can be obtained, and in the collision stopping step, the application of the work by the gun arm due to the collision of the gun arm with the work can be obtained. By arbitrarily setting the torque generated by the motor at the time of pressurization based on the above-described formula, the welding time can be shortened and the welding quality can be improved.

Further, the calculation of the current value performed in the collision stop step is performed by determining that the current value supplied to the motor changes in an inclined manner with respect to a change in the rotation speed of the motor, and that the rotation speed is set to a predetermined rotation speed. At the same time, the current value may be set to 0, and when the motor stops and the rotation speed becomes 0, the current value may be set to the set current value based on a calculation formula. (Claim 8
Described invention). In this case, by setting the torque generated in the motor as the motor decelerates from, for example, 0 to increase in an inclined manner, a large torque is instantaneously applied to the motor when the gun arm collides with the workpiece. Is generated, and a large impact is applied to the gun arm or the work.

The calculation of the current value performed in the collision stop stage may be performed based on the following equation: I = (1−V / V0) × Ic (the invention according to claim 9). . In this case, the current value can be obtained by a simple calculation, and the means for calculating the current value can be simplified and the calculation time can be shortened.

Next, in the invention according to claim 10,
In a series of operations in which the gun arm stops and collides after approaching the work and pressurizes the work, the current value to be supplied to the motor is determined by the set rotation speed of the motor, the actual rotation speed, and the predetermined set current value. Is obtained based on a predetermined calculation formula. In this case, by configuring the calculation formula so as to reduce the impact generated when the gun arm collides with the workpiece, it is possible to avoid a decrease in welding quality due to the collision.

Further, the calculation of the current value is performed when the current value supplied to the motor changes in an inclined manner with respect to a change in the actual rotation speed of the motor, and when the rotation speed is the same as the set rotation speed. When the current value becomes 0, and the motor stops and the rotation speed becomes 0, the calculation may be performed based on a calculation formula configured so that the current value becomes the set current value. 11). In this case, by setting the torque generated in the motor as the motor decelerates from, for example, 0 to increase in an inclined manner, a large torque is instantaneously applied to the motor when the gun arm collides with the workpiece. Occurs,
A large impact is prevented from being applied to the gun arm or the work.

Further, the calculation of the current value may be performed based on the following equation: I = (1−V / V0) × Ic (the invention according to claim 12). In this case, the current value can be obtained by a simple calculation, and the means for calculating the current value can be simplified and the calculation time can be shortened.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a drive control device and a drive control method for a welding gun arm according to the present invention (hereinafter simply referred to as a control device according to the embodiment).
This will be described with reference to FIG. 3C.

Before describing the control device according to the present embodiment, the configuration of the welding device will be briefly described.

As shown in FIG. 1, a welding device 10 to which the control device according to the present embodiment is applied includes works W1, W2
The first is a pair of gun arms for welding to
It has a gun arm 12 and a second gun arm 14, and welding tips 16 a and 16 b are provided at the distal ends of the first gun arm 12 and the second gun arm 14 facing each other.

The first gun arm 12 is connected to a rotating shaft of a motor (AC servo motor) 20 fixed to a hollow cylindrical base 18 via a bearing member (not shown) provided on the first gun arm 12. It is screwed to the ball screw 22 and displaces inside the base 18 so as to be able to advance and retreat along the axial direction of the base 18 under the driving action of the motor 20. The second gun arm 14 is fixed to the base 18. The first gun arm 12 and the second gun arm 14 are connected to a power supply (not shown) for applying a welding voltage (current) between the welding tips 16a and 16b.

The motor 20 has cables 24a to 24c
The cable is connected to a servo amplifier 60 described later via a cable 24 (when it is not necessary to separately describe the cable 24), and is driven at a predetermined speed and output (torque) by an alternating current supplied from the servo amplifier 60. You. The rotation direction of the motor 20 is the same as that of the first gun arm 12.
Is positive when moving forward, and negative when moving backward.

Next, a control device according to the present embodiment will be described.

As shown in FIG. 1, a control device 100 according to the present embodiment includes a welding device 10 and the control device 100.
A main controller 42 for controlling the entire operation, and speed data Dv0 supplied from the main controller 42
A current value and frequency of an alternating current to be supplied to the motor 20 based on the limit data Di, the actual speed data Dv obtained by the detector 44 provided in the motor 20, and the synchronization signal Sd. Signal Si
The speed control unit 50 outputs c and Sid, and the current value command signals Sic and Sid from the speed control unit 50 are supplied to current sensors 52a and 52a provided on the cables 24a and 24b.
2b, based on the detected current value signals Sii, Sij supplied from the current control unit 54 and output as current value command signals Sie, Sif; and based on the current value command signals Sie, Sif from the current control unit 54. PW that modulates the pulse width and outputs it as an alternating current signal having a pulse train
An M circuit 56, a servo amplifier 60 that supplies a three-phase AC current (current value I) based on the AC current signal from the PWM circuit 56 to the motor 20, and a predetermined signal based on the speed data Dv0 and the actual speed data Dv. Detect timing,
A timing detecting section (timing detecting means) 82 for outputting a timing signal St at this timing is provided.

In particular, the speed control unit 50 obtains a current value of an alternating current to be supplied to the motor 20 based on the speed data Dv0, the limit data Di and the actual speed data Dv, and outputs it as a current value command signal Sia or Sih. Current value calculating means 102, and a current value command signal Sia by limiting the upper limit of the current value command signal Sia or Sih from the current value calculating means 102 based on the limit data Di.
b, and a current value command signal Sic in the form of a pulse at a timing based on the synchronization signal Sd.
And a distribution unit 66 for outputting as Sid.

As shown in FIG. 2, the current value calculation means 102 calculates the speed data Dv0 and the actual speed data Dv
Speed deviation calculating means (first calculating means) 68 which calculates a speed deviation based on the above and outputs it as speed deviation data Dσ.
And speed deviation data Dσ from the speed deviation calculation means 68.
Current value calculating means (first calculating means) 70 which calculates a current value based on the above and outputs it as a current value command signal Sia.
A coefficient calculating means (second calculating means) 104 for calculating a coefficient based on a predetermined formula from the speed data Dv0 and the actual speed data Dv and outputting the coefficient as a coefficient data Dk; Based on data Dk and limit data Di from main controller 42,
A coefficient current value calculating means (second calculating means) 106 for obtaining a current value of an alternating current to be supplied to the motor 20 and outputting it as a current value command signal Sih;
And switches the current value command signal Sia from the deviation current value calculation means 70 and the current value command signal Sih from the coefficient current value calculation means 106 to the limit means 64 based on the timing signal St. And a selector (switching means) 108.

The detector 44 shown in FIG.
And a magnetic pole sensor that detects the position of the magnetic pole of the motor 20 and outputs it as a synchronization signal Sd. Specifically, it is configured by an optical encoder, a magnetic encoder, and the like including the speed sensor and the magnetic pole sensor. The rotation frequency signal from the detector 44 is converted to a voltage signal by an F / V conversion circuit 72, and then converted to digital data by an A / D conversion circuit 74, and converted to actual speed data Dv (rotation speed). V). Also, the servo amplifier 6 is controlled by the synchronization signal Sd.
From 0, the frequency of the three-phase alternating current supplied to the motor 20 is determined.

The servo amplifier 60 has terminals 58a to 58c.
After temporarily converting a three-phase AC current supplied from a power supply (not shown) connected through a terminal 58 (hereinafter referred to as a terminal 58) to a DC current, the three-phase AC current is converted to a three-phase AC current based on an AC current signal from the PWM circuit 56. It is configured to reconvert and supply to the motor 20.

The speed data Dv0 is used as a speed look-up table for setting a schedule (speed schedule) of the rotation speed V of the motor 20.
2 are stored in storage means (not shown). The speed data Dv0 is read from the speed look-up table at predetermined time intervals, and is output from the main controller 42 as a set rotation speed for setting the rotation speed of the motor 20 at each time. The speed look-up table is stored in the storage means of the main controller 42 as a plurality of data groups, and a desired one is selected from the data group.

The limit data Di is stored in the motor 20
Is stored in the storage means of the main controller 42 as a limit look-up table for setting a limit value schedule (limit schedule) for limiting the upper limit of the current value I of the alternating current to be supplied to the main controller 42. The limit data Di is read out from the limit look-up table at predetermined time intervals and output from the main controller 42 as a set limit value (set current value) for setting the limit value of the current value I at each time. Is done. The limit look-up table is stored in the storage means of the main controller 42 as a plurality of data groups, as in the case of the speed data Dv0, and a desired one is selected therefrom.

The operation schedule of the motor 20 is determined by the speed schedule and the limit schedule.

Next, the control device 100 according to the present embodiment
Will be described.

The set rotation speed is supplied as speed data Dv0 from the main controller 42 to the speed deviation calculating means 68 and the coefficient calculating means 104 constituting the current value calculating means 102, and the current value calculating means 102 calculates the coefficient current value. The set limit value is supplied to the means 106 and the limit means 64 as limit data Di (FIG. 1).
And FIG. 2). The rotational speed V of the motor 20 is supplied from the detector 44 to the speed deviation calculating means 68 and the coefficient calculating means 104 via the F / V conversion circuit 72 and the A / D conversion circuit 74 as actual speed data Dv.

The timing detector 82 detects a predetermined timing based on the speed data Dv0 (set rotation speed) and the actual speed data Dv, and outputs a timing signal St to the main controller 42 and the selector 108 at this timing. I do.

The speed deviation calculating means 68 calculates a speed deviation based on the speed data Dv0 and the actual speed data Dv, and outputs it as speed deviation data Dσ. In this case, the value of the speed deviation data Dσ becomes a negative value when the value of the actual speed data Dv (the rotation speed V of the motor 20) exceeds the set rotation speed, and the rotation speed V becomes equal to the set rotation speed. If the value is less than, it is assumed to be a positive value.

Then, the deviation current value calculation means 70 calculates a current value based on the speed deviation data Dσ from the speed deviation calculation means 68 and outputs it as a current value command signal Sia. In this case, the sign of the current value command signal Sia depends on the sign of the speed deviation data Dσ.

On the other hand, the coefficient calculation means 104 calculates a coefficient based on a predetermined calculation formula from the speed data Dv0 and the actual speed data Dv, and outputs it as coefficient data Dk. Then, the coefficient current value calculation means 106 calculates the coefficient data Dk from the coefficient calculation means 104 and the main controller 42.
The current value of the alternating current to be supplied to the motor 20 is determined based on the limit data Di from
Output as ih.

The selector 108 receives the current value command signal Sia from the deviation current value calculation means 70 and the current value command signal Sih from the coefficient current value calculation means 106 based on the timing signal St from the timing detection section 82. And outputs to the limit means 64.

The limit means 64 is connected to the selector 108
The upper limit of the current value command signal Sia or Sih is limited based on the limit data Di and output as the current value command signal Sib. In this case, the upper limit of the current value command signal Sia or Sih is limited as an absolute value, and does not depend on the sign.

The distribution means 66 outputs the current value command signal Sib from the limit means 64 as pulsed current value command signals Sic and Sid at a timing based on the synchronization signal Sd supplied from the detector 44.

The current control unit 54 receives the current value command signals Sic and Sid from the distribution unit 66 and
a, 52b detected current value signals Sii, Si
j, and outputs as current value command signals Sie and Sif.

The PWM circuit 56 modulates the pulse width based on the current value command signals Sie and Sif from the current control unit 54 and outputs it as an alternating current signal having a pulse train. In this case, the frequency of the alternating current signal is determined by the current value command signals Sic and Sid output from the distribution means 66.
(Pulse period).

The servo amplifier 60 temporarily converts a three-phase AC current supplied from a power supply (not shown) connected via a terminal 58 into a DC current, and then converts the three-phase AC current based on the AC current signal from the PWM circuit 56 into a three-phase AC current. The current is converted back to the current and supplied to the motor 20. When the value of the current value command signal Sia is positive, the AC current
, And the opposite phase when negative.

The motor 20 rotates by generating a torque depending on the current value I of the alternating current supplied from the servo amplifier 60. In this case, the cycle of the alternating current is modulated in synchronization with the rotation of the motor 20. And
The motor 20 is accelerated or decelerated by increasing or decreasing the current value I and rotating the phase forward or backward.

Then, by the rotation of the motor 20,
The first gun arm 12 advances and retreats with respect to the base 18. The position where the welding tip 16a provided at the tip of the first gun arm 12 contacts the workpiece W1 is referred to as the welding position of the first gun arm 12.

As described above, in the control device 100 according to the present embodiment, the rotation speed V of the motor 20 for driving the first gun arm 12 can be controlled based on a predetermined speed schedule. Gun arm 12
Can be set arbitrarily.

The limit data Di (set limit value) to be supplied from the main controller 42 to the limit means 64 is transmitted from the timing detector 82 to the speed data Dv.
Since it can be changed in accordance with the timing signal St output at a predetermined timing based on 0 (set rotation speed) and the actual speed data Dv, the timing for changing the set limit value corresponds to the speed schedule. Can be set.

In accordance with the timing signal St supplied from the timing detecting section 82 to the selector 108, the signal output from the selector 108 (ie, the current value calculating means 102) is converted into the speed deviation calculating means 68 and the deviation current value calculating means 68. The current value command signal Sia obtained by the means 70 can be changed to the current value command signal Sih obtained by the coefficient calculation means 104 and the coefficient current value calculation means 106. Therefore, it is possible to drive the motor 20 in different operation modes during one welding operation. Thereby, the operation mode of the first gun arm 12 is changed by changing the operation mode of the motor 20 between, for example, when the first gun arm 12 is displaced to the vicinity of the welding position and immediately before the first gun arm 12 collides with the workpiece W1. The displacement can be performed in a short time, and the impact when the first gun arm 12 collides with the workpiece W1 can be buffered.

It should be noted that the current value calculating means 102 can be constituted by a plurality of coefficient calculating means 104 and coefficient current value calculating means 106. In this case, the motor 20 can be driven in a plurality of operation modes during one welding operation.

Also, by supplying the timing signal St from the timing detecting section 82 to the coefficient calculating means 104 and the coefficient current value calculating means 106, the calculation set in the coefficient calculating means 104 and the coefficient current value calculating means 106 is performed. It is also possible to configure to change the expression.
Also in this case, the motor 20 can be driven in a plurality of operation modes during one welding operation.

Next, the control device 100 according to the present embodiment
An example will be described.

In this embodiment, the coefficient calculating means 10
The calculation of the coefficient in 4 is performed based on the following equation.

K = 1-V / V0 (1) where k is a coefficient, V is the rotation speed of the motor 20 supplied as the actual speed data Dv, and V0 is the speed data Dv
The set rotation speed (high speed Va or low speed Vb) of the motor 20 supplied as 0 is indicated.

On the other hand, the calculation of the current value in the coefficient current value calculation means 106 is performed based on the following equation.

I = k × Ic (2) where I is a current value output as the current value command signal Sih (same value as the AC current supplied to the motor 20), and k is the coefficient. , Ic respectively represent a set limit value {set current value (high limit value Ia or low limit value Ib)} supplied as limit data Di.

As shown in FIGS. 3A to 3C, the speed schedule (shown by a dotted line in FIG. 3A) is such that the set rotation speed becomes the high speed Va during the period of the time points a to c, and the low speed Vb after the time point c. It is set to be. on the other hand,
The limit schedule (shown by a dotted line in FIG. 3B) is set so that the set limit value becomes the high limit value Ia during the period from the time point a to d, and becomes the low limit value Ib after the time point d. The set rotation speed and the set limit value are assumed to be 0 in an initial state (before time point a). FIG. 3C shows the characteristics of the pressing force applied to the first gun arm 12.

After the set rotation speed is changed from the high speed Va to the low speed Vb, the timing detection unit 82
When it is detected that the rotation speed V of the motor 20 has reached the low speed Vb, when the motor 20 detects a decrease in the rotation speed V of the motor 20 while driving at the low speed Vb, and when the motor 20 Motor 2
When the stop of 0 is detected, the timing signal St is set to be output.

It is assumed that the current value command signal Sia supplied from the deviation current value calculation means 70 is selectively output from the selector 108 during the period from the time points a to d.

First, at a time point a, the set rotation speed (high speed Va) is supplied as speed data Dv0 from the main controller 42 to the speed deviation calculation means 68 constituting the current value calculation means 102, and the limit means The set limit value (high limit value Ia) is supplied to the H.64 as limit data Di (see FIGS. 1 and 2). Accordingly, the motor 20 starts.

That is, at this time point a, the motor 2
Since the rotation speed V of 0 is 0, the speed deviation calculating means 68
From the rotation speed V and the set rotation speed (high speed V
Speed deviation data Dσ having a positive value based on the deviation from a) is output. With the supply of the speed deviation data Dσ,
The deviation current value calculation means 70 starts outputting a positive current value command signal Sia based on the speed deviation data Dσ in order to start the motor 20.

Until the rotation speed V of the motor 20 reaches the high speed Va, the value of the speed deviation data Dσ output from the speed deviation calculation means 68 is
And a high value based on the deviation between the high speed Va and
The value of the current value command signal Sia output from the deviation current value calculation means 70 also becomes a positive value based on the deviation, and the motor 20 keeps accelerating (period a and b, acceleration region). In this case, when the current value command signal Sia exceeds the high limit value Ia, the limit means 64 outputs a current value command signal Sib in which the upper limit of the current value command signal Sia is limited by the high limit value Ia.

When the rotation speed V of the motor 20 reaches the high speed Va, the speed deviation calculated by the speed deviation calculating means 68 becomes substantially zero, so that the current value command signal Sia output from the deviation current value calculating means 70 Decreases to a value (almost 0) necessary to maintain the speed of the motor 20 at the high speed Va (time point b). And the motor 20
Driving at a constant speed at high speed Va until time point c (time points b to c
Period, high-speed driving area).

At time point c, the main controller 42
The set rotation speed supplied to the speed deviation calculating means 68 as speed data Dv0 from the high speed Va to the low speed Vb
Is changed to At this time, since the rotation speed V of the motor 20 exceeds the low speed Vb, the speed deviation calculating means 68 outputs a negative value of the speed deviation data based on the difference between the rotation speed V and the low speed Vb. Dσ is output. Then, the deviation current value calculation means 70 outputs the motor 2
A current value command signal Sia having a negative value based on the speed deviation data Dσ is output to decelerate 0. Along with this, the motor 20 starts to decelerate.

Until the rotation speed V of the motor 20 reaches the low speed Vb, the speed deviation data Dσ output from the speed deviation calculation means 68 is a negative value based on the difference between the rotation speed V and the low speed Vb. Therefore, the current value command signal Sia output from the deviation current value calculation means 70 also becomes a negative value based on the deviation, and the motor 20 continues to decelerate (the period from the time point c to d, the deceleration region).

When the rotation speed V of the motor 20 reaches the low speed Vb, the speed deviation calculated by the speed deviation calculating means 68 becomes almost 0, so that the value of the current value command signal Sia becomes
The speed of the motor 20 increases (decreases when viewed as an absolute value) to a value (almost 0) necessary to maintain the speed of the low speed Vb (time point d). At this time, the timing detecting section 82 determines that the rotation speed V of the motor 20 is equal to the low speed V
b, the main controller 4
2 and outputs a timing signal St to the selector 108.

The main controller 42 changes the set limit value to be supplied as the limit data Di to the limit means 64 from the high limit value Ia to the low limit value Ib based on the timing signal St (see FIGS. 3A and 3B). See time point d).

On the other hand, based on the timing signal St from the timing detecting section 82, the selector 108 replaces the current value command signal Sia supplied from the deviation current value calculating means 70 with the coefficient current value calculating means 106. It outputs the supplied current value command signal Sih. by this,
The operation mode of the motor 20 is changed.

At this time, the coefficient calculation means 104 calculates the coefficient k from the speed data Dv0 and the actual speed data Dv based on the equation (1), and outputs the coefficient k as the coefficient data Dk. Actually, the set rotation speed V0 supplied to the coefficient calculation means 104 as the speed data Dv0
Is the low speed Vb, and since the rotation speed V of the motor 20 supplied to the coefficient calculating means 104 as the actual speed data Dv has reached the low speed Vb, V / V
0 = 1, and the coefficient k obtained at this time point d is almost 0.
Becomes

The coefficient current value calculating means 106 calculates the coefficient data Dk from the coefficient calculating means 104 and the limit data Di (low limit value Ib) from the main controller 42.
, A current value I is obtained by performing a calculation based on the above equation (2), and is output as a current value command signal Sih. Actually, since the coefficient k supplied as the coefficient data Dk is almost 0, the current value I obtained here is also almost 0.

As a result, no torque is generated in the motor 20 and the motor 20 is driven at a constant speed at the low speed Vb (the period from the time point de to the time point e, the landing area). However, when the rotation speed V of the motor 20 fluctuates, a current value I for canceling the fluctuation is obtained based on the equations (1) and (2) and supplied to the motor 20.

The tip of the first gun arm 12 is the workpiece W1
When the collision occurs, the path of the first gun arm 12 is interrupted and its forward speed decreases, and accordingly, the rotation speed V of the motor 20 also decreases (time point e). In this case, it is assumed that the welding tip 16b at the tip of the second gun arm 14 is in contact with the other workpiece W2. And then,
Since the rotation speed V of the motor 20 in the equation (1) is lower than the set rotation speed V0 (low speed Vb), V / V0
<1, and the coefficient k obtained by the coefficient calculation unit 104 based on the above equation (1) is a positive value.

The current value I obtained by the coefficient current value calculating means 106 based on the equation (2) is
Since the coefficient k supplied as coefficient data Dk to 06 is a positive value, the coefficient k is also a positive value. Therefore, the motor 20
Is supplied with an AC current having a positive current value, and a torque is generated in the motor 20.

As the rotational speed V of the motor 20 decreases, the value of V / V0 in the equation (1) decreases, and the value of the coefficient k obtained by the coefficient calculating means 104 increases.
In response to this, the current value I obtained by the coefficient current value calculating means 106 based on the expression (2) gradually increases, and the torque generated in the motor 20 also gradually increases based on the current value I (time point). e-i, collision area).

When the motor 20 stops, the rotation speed V of the motor 20 in the equation (1) becomes substantially zero, and therefore V / V
0 = 0, and the coefficient k obtained by the coefficient calculating means 104 based on the equation (1) becomes substantially 1. Therefore, the current value I obtained by the coefficient current value calculation means 106 based on the equation (2) is substantially equal to the low limit value Ib. Accordingly, a torque based on the low limit value Ib is generated in the motor 20 (time i).

The motor 20 includes the motor 2
As long as 0 is stopped, a substantially constant torque is generated based on the low limit value Ib. Therefore, the first gun arm 12 and the second gun arm 14 press the workpieces W1 and W2 with a substantially constant pressing force generated between the first gun arm 12 and the second gun arm 14 due to this torque (after time i). Pressurized area).

At the time point i, the timing detector 82
Supplies the timing signal St to the selector 108, and outputs the signal output from the selector 108 to the current value command signal Si.
The operation mode of the motor 20 may be changed again by changing from h to the current value command signal Sia.

As described above, in the present embodiment, at the time point d
The processing performed by the current value calculating means 102 based on the timing signal St output from the timing detection section 82 to the selector 108 is based on the speed deviation based on the rotation speed V of the motor 20 and the set rotation speed. Command signal S
The process for obtaining ia is changed to a process for obtaining the current value command signal Sih based on the above equations (1) and (2) from the rotation speed V, the set rotation speed and the set limit value.

The expressions (1) and (2) are
Since the current value command signal Sih is set to increase in inverse proportion to the decrease in the rotation speed V as the rotation speed V of the motor 20 decreases, the first gun arm 12
When the motor 20 decelerates by colliding with the workpiece W1, a large torque is instantaneously generated in the motor 20 to prevent the first gun arm 12 from being elastically deformed to cause vibration. be able to.

Accordingly, by calculating the current value of the current to be supplied to the motor 20 based on such a simple calculation formula, the collision area (the period between time points e and i in FIGS. 3A to 3C) is reduced. Thus, a loss in welding time is avoided. Further, the configurations of the coefficient calculating means 104 and the coefficient current value calculating means 106 can be simplified.

Comparative Example Next, in order to clarify the features of the present invention, a comparative example with respect to the present embodiment (example) will be described.

First, a first comparative example will be described with reference to FIGS.
This will be described with reference to C.

As shown in FIG. 4, the control device 40 according to the first comparative example is different from the control device 100 according to the present embodiment shown in FIG. I have. Further, no limit data Di is supplied to the current value calculation means 62.

Further, as shown in FIG. 5, the current value calculating means 62 is different from the current value calculating means 102 shown in FIG.
The configuration does not include the coefficient calculation means 104, the coefficient current value calculation means 106, and the selector 108. That is, only the current value command signal Sia from the deviation current value calculation means 70 is supplied to the limit means 64.

Next, an operation mode in the case where the welding device 10 is driven by the control device 40 according to the first comparative example with the same speed schedule and limit schedule (see FIGS. 3A and 3B) as in the above embodiment. explain.

In the period from the time point a to the time point d, almost the same processing as in the case of the above embodiment (see FIGS. 3A to 3C) is performed.

At time d, the rotational speed V of the motor 20
When the motor speed reaches the low speed Vb, the speed deviation calculated by the current value calculation means 62 becomes substantially zero. Therefore, the value of the current value command signal Sia is necessary to maintain the speed of the motor 20 at the low speed Vb. Value (almost 0) (lower when viewed as an absolute value). After that, the limit data D is sent from the main controller 42 to the limit means 64.
The set limit value supplied as i is the high limit value Ia
To the low limit value Ib. And motor 2
0 is the tip of the first gun arm 12 (welding tip 16
The drive is driven at a constant speed at the low speed Vb until the point a) collides with the workpiece W1 (a period from time de to time e, a landing area).

The tip of the first gun arm 12 is the workpiece W1
When the collision occurs, the path of the first gun arm 12 is interrupted and its forward speed decreases, and accordingly, the rotation speed V of the motor 20 also decreases. Since the rotation speed V falls below the low speed Vb due to the decrease in the rotation speed V of the motor 20, the speed deviation calculating means 68 outputs a positive value based on the difference between the rotation speed V and the low speed Vb. The value speed deviation data Dσ is output. Then, the deviation current value calculation means 70 outputs a positive current value command signal Sia based on the speed deviation data Dσ to accelerate the motor 20.
Is output. Accordingly, a forward torque is generated in the motor 20 (time e).

After the tip of the first gun arm 12 collides with the work W1 at time point e, the rotation speed V
Rapidly decreases, and accordingly, the value of the speed deviation data Dσ output from the speed deviation calculating means 68 sharply increases. The current value command signal Si output from the deviation current value calculation means 70 based on the speed deviation data Dσ
The value of “a” also rises rapidly and instantaneously reaches the upper limit value (low limit value I).
b) is reached. As a result, from the limit means 64,
The current value command signal Sib having substantially the same value as the low limit value Ib is continuously output (period between the time points ef and the collision area).

When the motor 20 stops, a constant torque is generated in the motor 20 based on the current value command signal Sib, and this torque causes the first gun arm 12 and the second gun arm 14 to move the workpieces W1 and W2. Is pressurized with a constant pressing force (a pressurized region after time point f).

Incidentally, in the first comparative example,
After the first gun arm 12 collides with the work W1, the value of the current value command signal Sia sharply increases,
Includes a current value command signal Si substantially equal to the low limit value Ib.
The torque based on b is instantaneously generated. As a result, the pressing force is also instantaneously applied to the first gun arm 12 and the second gun arm 14, and the pressing force causes the first gun arm 12 and the second gun arm 14 to undergo elastic deformation. (Refer to the period from time point ef to time point f in FIGS. 6A to 6C). Therefore,
Compared to the case of the above-described embodiment, it takes much time until the first gun arm 12 and the second gun arm 14 are stopped and a state in which welding can be performed, so that welding time is lost ( 7A and 7B).

Next, a second comparative example will be described with reference to FIGS. 7A to 10C.

As shown in FIG. 8, the control device 80 according to the second comparative example differs from the control device 100 according to the present embodiment shown in FIG. Is not supplied.

Then, the current value calculating means 8 shown in FIG.
Reference numeral 4 denotes an increase / decrease that outputs a current value command signal Sig by limiting the rate of increase / decrease of the current value command signal Sia from the deviation current value calculation means 70 to the current value calculation means 62 shown in FIG. It has a rate limiting means 86.
The rate-of-change limiting means 86 starts or stops the process of limiting the rate of change of the current value command signal Sia based on the timing signal St from the timing detecting section 82.

Next, an operation mode in the case where the welding device 10 is driven by the control device 80 according to the second comparative example with the same speed schedule and limit schedule (see FIGS. 3A and 3B) as in the above embodiment. explain.

In the period between time points a and d (including time point d),
Almost the same processing as in the case of the above-described embodiment (see FIGS. 3A to 3C) is performed (except for the processing in the selector 108 and the like).

After the tip of the first gun arm 12 collides with the workpiece W1 at time point e, the rotation speed V
Rapidly decreases, and accordingly, the value of the speed deviation data Dσ output from the speed deviation calculating means 68 rapidly increases. Then, the current value command signal Sia output from the deviation current value calculation means 70 based on the speed deviation data Dσ also sharply rises (a period of time points e to g, the first collision area).

When the timing detecting section 82 detects that the rotation speed V of the motor 20 has decreased when the set rotation speed of the motor 20 is the low speed Vb, the timing detection section 82 supplies the change rate limiting means 86 of the current value calculation means 84 to the change rate limiting means 86. On the other hand, the timing signal S
t is output (time point g). The increase / decrease rate limiting means 86 limits the increase / decrease rate of the current value command signal Sia supplied from the deviation current value calculation means 70 to a predetermined slope based on the timing signal St from the timing detection section 82, and The process of outputting the command signal Sig is started. When the current value command signal Sig reaches the low limit value Ib, the limit means 64 outputs the low limit value Ib.
The current value command signal Sib having substantially the same value as the above is continuously output (period between time points g and h, the second collision area).

When the motor 20 stops, a substantially constant torque is generated in the motor 20 based on the current value command signal Sib (same value as the low limit value Ib), and this torque causes the first gun arm 12 and the first The two-gun arm 14 presses the works W1 and W2 with a constant pressing force (a pressurizing region after time point h). When the timing detecting section 82 detects that the motor 20 has stopped, the timing detecting section 82 outputs a timing signal St to the increase / decrease rate limiting section 86 of the current value calculating section 84. The increase / decrease rate limiting means 86 is provided with the timing detecting section 82
Based on the timing signal St, the processing for limiting the rate of increase / decrease of the current value command signal Sia supplied from the deviation current value calculation means 70 is stopped.

As described above, in the second comparative example, when a decrease in the rotation speed V of the motor 20 is detected when the set rotation speed is the low speed Vb, the timing signal St output from the timing detection section 82 is detected. , The process of limiting the rate of increase / decrease of the current value command signal Sia in the rate-of-change limiting means 86 is started, so that the impact when the tip of the first gun arm 12 collides with the workpiece W1 can be buffered. .

However, since the current value command signal Sia sharply rises after the collision between the first gun arm 12 and the work W1 and before the start of the limitation of the increase / decrease rate, the first comparative example is different from the first comparative example. Similarly, vibration was generated in the first gun arm 12 and the second gun arm 14. Therefore, in the second comparative example, the effect of reducing the welding time loss was not sufficiently obtained as compared with the case of the above-described example (see FIGS. 7A and 7C).

As described above, in the control device 100 according to the present embodiment, an excellent vibration suppression effect is obtained as compared with the first and second comparative examples, and therefore, the welding time is reduced. Is done.

[0104]

According to the drive control device and the drive control method for a welding gun arm according to the present invention, the operation of displacing the gun arm in the direction approaching the work, stopping after the collision with the work, and pressing the work is performed. , The occurrence of vibration when the gun arm collides with the work is suppressed, and the welding time is shortened.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device according to the present embodiment.

FIG. 2 is a block diagram showing a configuration of a current value calculating unit according to the present embodiment.

3A and 3B are graphs showing the operation of the motor in the present embodiment, FIG. 3A shows the actual rotation speed and the set rotation speed of the motor, and FIG. 3B shows the current value and the limit of the AC current to be supplied to the motor. FIG. 3C is a diagram showing the pressure applied to the gun arm.

FIG. 4 is a block diagram of a control device according to a first comparative example.

FIG. 5 is a block diagram illustrating a configuration of a current value calculating unit according to a first comparative example.

6 is a graph showing the operation of the motor in the first comparative example, FIG. 6A shows the actual rotation speed and the set rotation speed of the motor, and FIG. 6B shows the current value of the AC current to be supplied to the motor. FIG. 6C is a diagram showing a pressing force generated in the gun arm.

7A shows a pressing force generated on the gun arm in the present embodiment, FIG. 7B shows a pressing force generated on the gun arm in the first comparative example, and FIG. 7C shows a pressing force on the gun arm in the second comparative example. It is a figure which shows the pressurizing force which arises.

FIG. 8 is a block diagram of a control device according to a second comparative example.

FIG. 9 is a block diagram illustrating a configuration of a current value calculation unit according to a second comparative example.

10 is a graph showing the operation of the motor in the second comparative example, FIG. 10A shows the actual rotation speed and the set rotation speed of the motor, and FIG. 10B shows the current value of the AC current to be supplied to the motor. FIG. 10C
FIG. 4 is a diagram showing a pressing force generated in a gun arm.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Welding device 12 ... 1st gun arm 14 ... 2nd gun arm 20 ... Motor 42 ... Main controller 50 ... Speed control part 54 ... Current control part 60 ... Servo amplifier 64 ... Limit means 68 ... Speed deviation calculation means (1st calculation means) ) 70: deviation current value calculation means (first calculation means) 82: timing detection section (timing detection means) 100: control device 102: current value calculation means 104: coefficient calculation means (second calculation means) 106: coefficient current value Calculation means (second calculation means) 108 ... selector (switching means)

Claims (12)

[Claims] An apparatus for controlling the operation of a motor that drives a gun arm for performing welding on a workpiece, comprising: a main controller that manages an operation schedule of the motor; and a motor that is controlled based on the operation schedule. And a servo amplifier for supplying a current based on the current value from the current value calculation unit to the motor, wherein the current value calculation unit sets the motor. First calculating means for calculating the current value from a deviation between the speed and the actual rotation speed; and calculating the current value by performing a calculation based on a predetermined formula from the set speed, the rotation speed and a predetermined set current value. A drive control apparatus for a welding gun arm, comprising: two arithmetic means. 2. A drive control device for a welding gun arm according to claim 1, wherein said switching means outputs a current value obtained by said first calculation means and a current value obtained by said second calculation means. A drive control device for a welding gun arm, characterized by comprising: 3. A drive control device for a welding gun arm according to claim 2, further comprising timing detection means for outputting a signal at a predetermined timing based on said set speed and said rotation speed, and wherein said switching means performs said timing. A drive control device for a welding gun arm, wherein the switching operation is performed based on a signal from a detection means. 4. The drive control device for a welding gun arm according to claim 1, wherein a calculation formula for obtaining a current value in said second calculating means is such that the current value of said motor is The current value becomes 0 when the rotation speed is the same as the set speed, and the current value becomes 0, and the rotation speed becomes 0.
Wherein the current value is equal to the set current value. 5. The drive control apparatus for a welding gun arm according to claim 4, wherein the calculation expression is such that the current value is I, the set speed is V0, and
When the rotation speed is V and the set current value is Ic, I = (1−V / V0) × Ic. 6. A method for controlling an operation of a motor for driving a gun arm for performing welding on a workpiece, the method comprising: stopping the gun arm after approaching and colliding with the workpiece to pressurize the workpiece. The operation of the motor is changed in an approaching step in which the gun arm approaches the work and in a collision stopping step in which the gun arm collides with the work and stops. Drive control method for gun arm. 7. The drive control method for a welding gun arm according to claim 6, wherein the current value supplied to the motor is:
It is determined based on the deviation between the set rotation speed of the motor and the actual rotation speed.In the collision stop stage, a predetermined calculation formula is obtained from the set rotation speed of the motor, the actual rotation speed, and a predetermined set current value. A drive control method for a welding gun arm, wherein the method is obtained based on the following. 8. The drive control method for a welding gun arm according to claim 7, wherein in the calculation formula, a current value supplied to the motor changes in an inclined manner with respect to a change in an actual rotation speed of the motor. When the rotation speed is the same as the set rotation speed, the current value becomes 0, and when the motor stops and the actual rotation speed becomes 0, the current value becomes the set current value. A drive control method for a welding gun arm, characterized in that: 9. The drive control method for a welding gun arm according to claim 8, wherein the calculation expression is such that the current value supplied to the motor is I, the set current value is Ic, and the set rotation speed of the motor is V.
0. A drive control method for a welding gun arm, wherein I = (1−V / V0) × Ic, where V is an actual rotation speed of the motor. 10. A method for controlling an operation of a motor for driving a gun arm for performing welding on a work, comprising: Wherein the current value supplied to the motor is obtained from a set rotational speed of the motor, an actual rotational speed, and a predetermined set current value based on a predetermined calculation formula. Drive control method. 11. The drive control method for a welding gun arm according to claim 10, wherein the calculation expression is such that a current value supplied to the motor changes in an inclined manner with respect to a change in an actual rotation speed of the motor. When the rotation speed is the same as the set rotation speed, the current value becomes 0, and when the motor stops and the actual rotation speed becomes 0, the current value becomes the set current value. A drive control method for a welding gun arm, characterized in that: 12. The method for controlling the drive of a welding gun arm according to claim 11, wherein the calculation formula is such that a current value supplied to the motor is I, the set current value is Ic, and a set rotation speed of the motor is V.
0. A drive control method for a welding gun arm, wherein I = (1−V / V0) × Ic, where V is an actual rotation speed of the motor.