JPH0970675A - Control device for spot welding robot and its control method - Google Patents

Abstract

(57) [Abstract] [Purpose] The gun equalizes during pressurization to absorb the impact of robots and workpieces and the amount of electrode wear, but welding is eliminated, but the equalization mechanism is eliminated and welding tip management can be automated. . [Structure] A means for idle driving with a reference electrode tip at the time of teaching, a means for bringing a movable side electrode into contact with a reference fixed object, and a means for storing the robot position and gun motor position at the time of the idle contact. , A means for calculating the wear amount / correction amount of the movable side electrode tip based on the difference in position between when the electrode tip used for program reproduction is idled and abutted against a fixed object and when the teaching piece is moved. It comprises means for correcting and operating the position of the side electrode tip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding robot controller and its control method.

[0002]

2. Description of the Related Art Conventionally, in spot welding with a robot, the spot gun for welding equalizes during pressurization to absorb the impact of the robot and the work and the amount of electrode wear. This is called "Conventional Example 1"]. In addition, as a method for detecting wear, a means for detecting the wear by installing a dedicated sensor on the gun or the outside, such as Japanese Patent Publication No. 6-79787 and Japanese Utility Model Publication No. 6-27273, will be referred to as “conventional example 2 and conventional example 3” hereinafter. ]Met. Furthermore, regarding tip replacement, it is necessary to perform molding with the number of times of welding and replace with the number of times of molding.
It depends on the detection amount obtained from the sensors of Conventional Example 2 and Conventional Example 3 [hereinafter, referred to as "Conventional Example 4"].
As a means for processing the transformer thermo-abnormality, as in the system example shown in FIG. 7, if the thermostat signal line of the welding transformer of the gun is arranged in the welding timer and the thermostat abnormality of the transformer is detected by the welding timer during operation. This was integrated with other factors as a welding abnormality, output to the robot controller, and processed as a welding abnormality alarm by the robot. That is, as a wiring example of the conventional example, in FIG.
Mounted, and from the spot gun 30 the robot controller 1
5, the gun control cable 22 is wired as the gun control signal line 23 via the relay section 25, while the gun control cable 22 is wired as the trans-thermo signal line 24 via the relay section 25.
Wired to 0. The welding signal line 28 is connected to the welding timer 20 from the robot controller 15, and the welding signal line 28 is connected to the transformer 32 of the spot gun 30 by the power cable 29. Reference numeral 11 denotes a power supply cable for supplying power to a drive motor that controls the attitude of the spot robot 10,
Is a programming pendant for robots (programming
pendant) [hereinafter, this is referred to as "conventional example 5"]. Furthermore, in the conventional electric spot gun welding of a robot, it is necessary to bring the fixed-side electrode into contact with the work to teach its position.In this teaching, the fixed-side electrode is moved in minute increments to hit the work. The robot was designed to be in contact with each other or to have an equalizing mechanism in the gun so that welding can be performed without teaching the robot to contact the workpiece [hereinafter, this is referred to as "conventional example 6"]. Here, to add a little more about the equalizing mechanism, it is a means for supporting the welding gun so that it can be displaced in the pressurizing direction, and is a means for absorbing the displacement of the object to be welded. When the moving side electrode comes into contact with the work piece, the fixed side electrode is unlocked and the fixed side electrode is made swingable by the spring means. This is a mechanism in which the electrode comes into contact with the object to be welded based on the swing of the tip. By the way, if the prior art according to the above-mentioned document is applied, the conventional example 2 is an automatic welding machine that performs welding by sequentially moving the welding gun to a plurality of welding points of the work by a robot, Using the gun arm opening when the welding gun is idled with the electrode tip attached as the reference opening, set the lower opening of the gun arm when the length of the electrode tip has decreased to the usable limit, Before welding the welding point position, the welding gun is idled, the opening of the gun arm at this time is detected by the opening sensor provided on the welding gun, and this detected opening is compared with the lower limit opening. In addition to determining whether or not the electrode tip needs to be replaced, the upper limit opening is set by adding a tolerance to the reference opening, and when the detected opening exceeds the upper limit opening, a chip defect is detected. Activates the indicator shown An electrode tip management method of the welding gun in an automatic welding machine, characterized in that there was Unishi. In addition, the conventional example 3 is a welding robot apparatus in which a welding unit is floatingly supported on an arm of a robot body via an equalizer, and an electrode position correction device that displaces the position of the welding unit with respect to the arm in the electrode facing direction, and a welding unit. Wear amount detecting device for detecting the wear amount of the fixed electrode, and the wear amount detecting device operates to correct the position of the fixed electrode with respect to the arm to the initial position based on the electrode wear amount detected by the wear amount detecting device. And a control device for controlling the welding robot.

[0003]

However, the equalizing mechanism of the conventional examples 1 to 4 limits the freedom of the gun design, and the sensor is difficult to implement in the welding environment. It was. Therefore, the present invention provides a spot welding robot control device and method capable of detecting the wear amount of a tip without using an equalizing mechanism, a sensor, etc., and detecting the wear amount correction and the tip replacement time. This is the first purpose. Furthermore, in the method of Conventional Example 5, guns having different strokes have appeared, and nowadays, the spot gun is controlled by a robot controller. Nowadays, only the line that transmits the thermostat output signal of the welding transformer is welded from the gun. Since it will be wired to the machine, the efficiency in design and implementation is poor. Further, the robot control device has a problem that it is difficult to make detailed measures because abnormalities that should be taken as individual factors of transthermo abnormalities can be taken only as integrated welding abnormalities. Therefore, it is a second object of the present invention to provide a controller for a spot welding robot having a monitoring / processing means for the thermostat signal of the spot gun so that the signal is directly wired. Furthermore, in the teaching method in the spot welding robot shown in Conventional Example 6,
There is a problem that it is difficult to teach the fixed side electrode to abut on the work, and it takes time, and the equalizing mechanism has been a factor in increasing the cost. Therefore, a third object of the present invention is to provide a control device for a spot welding robot that can teach the contact position of the fixed electrode by a simple method and a method thereof.

[0004]

In order to solve the above problems, the present invention provides an electric spot gun in a robot controller for resistance welding a workpiece with an electric spot gun without using an equalizing mechanism or a sensor. It is a robot controller for spot welding that detects the wear amount of the tip from the arrival position when driving, and corrects the wear amount and detects when the tip is replaced. It also monitors and processes the thermostat signal of the welding transformer of the spot gun. And a robot controller for spot welding, which is capable of teaching the contact position of the fixed-side electrode with a simple means in a robot for resistance welding a workpiece. That is, in an apparatus for controlling a robot that resistance-welds an object to be welded with an electric spot gun, means for idle driving with a reference electrode tip during teaching, means for contacting a movable side electrode with a reference fixed object, and Means for storing the robot position and gun motor position at the time of blank hitting and abutting, and the electrode on the movable side by the blanking of the electrode tip used at the time of program reproduction and contact with a fixed object and the position difference at the time of teaching Chip,
A spot welding robot having means for calculating the wear amount of each fixed electrode tip and a correction amount obtained from the wear amount, and means for correcting the positions of the movable electrode tip and the fixed electrode tip with the correction amount. It is a control device, and the robot is moved to teach an approach position C in which the movable electrode tip is hit at the time of teaching, the position A of the movable electrode tip at this time is stored, and the movable electrode tip can be brought into contact with the reference fixed object. , The movable electrode tip is brought into contact with the reference fixed object from the position C, and the difference α from the position D of the movable electrode tip at this time is α
The amount of movement of the gun motor position is stored, the same blanking and reference fixed object contact are taught to the program at the time of chip dress or chip replacement, and the empty space taught at the time of playing the program of chip dress or chip replacement. The striking is reproduced, and the difference δ between the position of the gun motor at the position B of the movable side electrode tip and the position A at the time of teaching is calculated, and this difference δ becomes the first total (movable side + fixed side) wear amount. The taught contact with the reference fixed object is reproduced, and the difference β between the approach position C ′ and the position D is detected, and δ: First total (movable side + fixed side) wear amount, that is, first movable Side correction amount α: Reference stroke length β: First wear stroke length γ = β−α: First movable side wear amount ε = δ− (β−α): First fixed side wear amount First
As the fixed-side correction amount of, the movable-side electrode tip is corrected by the first movable-side correction amount indicated by δ, and the fixed-side electrode tip is corrected by the first fixed-side wear amount indicated by ε. The method of controlling the spot welding robot further includes storing the gun motor position of the movable side electrode tip at the same pressurizing state as the welding at the time of teaching, or the gun motor position and the plate at the blanking position during teaching. The thickness and the number of welds are stored, and spot welding is performed with the electrode used during program reproduction, and the wear amounts of the movable electrode tip and fixed electrode tip are added from the position of the movable electrode tip at this time. A means for calculating a second wear amount and a second correction amount for the movable side electrode tip and the fixed side electrode tip from the first wear amount and the first correction amount is provided. During the calculation cycle of
First to correct the wear of the electrode tip based on the second correction amount
The controller of the robot for spot welding according to item,
Furthermore, the difference δ ′ between the position of the movable side electrode tip registered in advance in the pressurized state at the gun motor position and the position of the gun motor at the pressure position during welding this time is calculated, and δ ′: 2 total (movable side + fixed side) wear amount, that is, second
Movable side correction amount ε ′ = ε + {(δ′−δ) / 2}: from the second fixed side wear amount, that is, the second fixed side correction amount, to the second movable side correction amount δ ′ and the second fixed side correction amount δ ′. This is the control method of the spot welding robot according to the second item, in which the fixed side correction amount is calculated and ε'is corrected when the program of the welding operation is regenerated, and the movable side electrode tip and the fixed side electrode tip use limit wear. The spot welding robot according to the first aspect, which has means for storing the amount, outputs an alarm signal and automatically replaces the tip when the first wear amount exceeds the value of the wear limit wear amount. It is a control device, and when the second total wear amount exceeds a value obtained by adding the movable side electrode tip and the fixed side electrode tip with the preset wear limit wear amount, an alarm signal is output after welding is completed. Or the first of the movable side electrode tip and the fixed side electrode tip The controller for the spot welding robot according to the first item, which calculates the amount of wear, determines which of the tips is to be used, outputs an alarm signal, and automatically exchanges the tips, and also uses a spot gun for welding. In a device for controlling a robot for resistance welding of objects, a control of a spot welding robot having means for inputting a thermostat signal of a welding transformer of a spot gun, means for stopping a welding operation by the signal, and means for outputting an alarm A device for controlling a robot that resistance-welds an object to be welded with a gun motor-driven spot gun, and a means for setting the plate thickness of the workpiece and the number of welds, and a fixed electrode on the robot axis for welding at the teaching position. To move the movable side electrode to the work, and the fixed side tip from the gun motor position at the time of contact. A controller for a spot welding robot provided with means for calculating a movement amount for contacting and means for calculating and teaching a position at which the fixed side electrode is brought into contact from this movement amount, and also a movable side during idle driving. The gun motor position p of the reference position of the electrode tip is registered, the thickness s of the workpiece conditions to be taught and the number of welds t are set, the robot is operated, and the vertical positioning of the gun is taught at the approach position for welding. Then, the movable side electrode tip is slowly brought into contact with the contact torque of the gun motor in the contact monitoring state, and the contact position is set to q, and the third correction amount η for teaching is η = (p−q )-(S × t), and teaches the robot in this abutting state as it is.

[0005]

According to the above means, the present invention can eliminate the equalizing mechanism and the sensor in an environment where there is almost no displacement of the workpiece, and can simplify the design and implementation, shorten the schedule, and reduce the cost. By the above means, the present invention provides
Everything related to the spot gun including the gun pressurization signal, stroke switching signal, opening confirmation signal and transformer thermostat signal can be wired only to the robot controller, improving design and implementation efficiency and reducing costs. Can be expected. Also, by wiring the thermostat signal of the spot gun transformer directly to the robot controller,
Instead of being integrated as a welding abnormality, it can be separately recognized as a thermostat abnormality of the transformer, and detailed measures can be taken, improving safety and work efficiency. By the above means,
The contact position of the fixed electrode can be easily taught, the teaching time for contact teaching can be shortened for guns without an equalize mechanism, and wear compensation can be used for guns with an equalize mechanism, allowing freedom in gun design by omitting the equalize mechanism. It is possible to anticipate expansion of the degree and cost reduction.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same reference numerals represent the same or corresponding members. 1 is a conceptual perspective view showing an example of a system to which the present invention is applied, and FIG. 2 is a side view showing an electric spot gun in a first embodiment of the present invention. 1 and 2, the spot robot 10 is equipped with an electric spot gun 30, and a welding control signal line 28 from the robot controller 15 to the welding timer 20 and a power cable (welding) from the welding transformer 32 of the electric spot gun 30. 29) is connected. In addition, electric spot gun 3
The control of the electric motor 31 of 0 is performed by the robot controller 15, and the movable side electrode tip 36 at the tip of the movable side electrode part 34 is connected to a workpiece (not shown) via a drive part 33 including a ball screw for driving the electric motor 31. ) Pressurize and open. Furthermore, the fixed side electrode tip 37 at the tip of the fixed side electrode portion 35 obtains a large current at the time of welding together with the movable side electrode tip 36 from the welding transformer 32. And
FIG. 3 is a partial side view showing the configuration of the first embodiment of the present invention,
FIG. 4 is a partial side view showing the configuration of the second embodiment of the present invention. The detection of the chip replacement timing and the correction of the wear amount in this system are as follows.

[Correction Performed at the Time of Chip Dressing (Chip Polishing) of the Electric Spot Gun or Chip Replacement] First, as a first embodiment of the present invention, the first correction performed at the time of chip dressing or chip replacement will be described below. To do. FIG. 3 is an explanatory diagram of correction performed at the time of chip dressing or chip replacement. First, when teaching as shown in FIG. 3 (a ₁ ), the reference electrode tip is blanked. The position A (position of the gun motor 31) of the movable electrode tip 36 at this time is stored.
That is, the reference position A of the movable side electrode chip 36 is registered by blanking with the reference chip (upper side). Also, FIG. 3 (b ₁ ).
As described above, the robot is moved to teach the approach position C at which the movable electrode tip 36 can be brought into contact with the reference fixed object 21, and the movable electrode tip 36 is brought into contact with the reference fixed object 21 from this approach position C. The difference α (the amount of movement of the position of the gun motor 31) from the position D of the movable electrode tip 36 at this time is stored. At this time, the same blank driving and reference fixed object contact are taught to the program at the time of chip dressing or chip replacement.

Next, as shown in FIG. 3 (a ₂ ), the blank driving that was taught at the time of program reproduction for chip dressing or chip exchange is reproduced, and the position B of the movable side electrode chip 36 (position of the gun motor 31) is reproduced. And the difference δ between the teaching position A and the position A at the time of teaching is calculated. This difference δ is the first total (movable side + fixed side) wear amount. Then, the contact with the reference fixed object 21, which was also taught, is reproduced, and the approach position C ′ (the position displaced from C by the wear of the movable tip, the position of the gun motor 31 is C).
And the position D of the movable side electrode tip 36 (D + moveable tip wear amount at the position of the gun motor 31) are detected. As a result, δ: first total (movable side + fixed side) wear amount, that is, first movable side correction amount α: reference stroke length β: first wear stroke length γ = β−α: first Movable side wear amount ε = δ− (β−α): First fixed side wear amount, that is, first
Is the fixed side correction amount.

Here, δ is the first movable-side correction amount because the fixed-side electrode tip 37 is corrected in the movable-side direction by the first fixed-side correction amount, and the movable-side electrode tip 36 remains as it is. Since it moves that much [see the mechanism of FIG. 2], it is necessary to correct the same amount in the opposite direction. As described above, the present invention basically comprises the following ideas. That is, the relationship of fixed-side wear amount = fixed-side wear amount fixed-side wear amount + movable-side wear amount = movable-side correction amount is established. To explain this in detail, the amount of wear of the movable side electrode tip 36 is performed by servo position correction of the electric spot gun 30 [at that time, offsetting the position correction of the spot robot 10 described later], and the fixed side electrode tip 37. The amount of wear corrects the position of the spot robot 10.

[Correction Performed During Teaching During Program Reproduction of Welding Operation for Electric Spot Gun] Next, as a second embodiment of the present invention, a second correction performed during teaching during program reproduction of the welding operation. Will be described. For the position set to perform the second correction (usually, the position of the approach for welding), the first movable correction amount δ and the first fixed-side correction amount ε are each corrected after further correction. Operate the electrodes. Although the above-described correction at the time of tip dressing or tip replacement can be sufficiently used by itself, if the correction is performed at the time of teaching during the program reproduction of the welding operation, further welding accuracy can be obtained. That is, in this case, the setting is such that the correction amount is calculated during welding during the teaching operation. The difference δ ′ between the position of the movable side electrode tip 36 (the position of the gun motor 31) that was previously placed under pressure and the pressurizing position (position of the gun motor 31) during welding this time is calculated, and the following formula is used: The second movable side correction amount and the second fixed side correction amount are calculated. δ ′: Second total (movable side + fixed side) wear amount, that is, second
Movable side correction amount ε ′ = ε + {(δ′−δ) / 2}: Second fixed side wear amount, that is, second fixed side correction amount. When the correction is used, the movable side electrode tip 36 and the fixed side electrode tip 37 are evenly worn based on the third total wear amount (δ′−δ) from the previous tip dress and the correction at the time of tip replacement to the present. It is assumed and corrected.

When the first correction at the time of tip dressing or tip replacement is not used, the first fixed side wear amount / the first fixed side correction amount ε = 0, the first total (movable side + Fixed side) Abrasion amount / First movable side correction amount δ = 0 If calculated, it is possible to use only the second correction during welding as a simple correction means. The method of performing the second correction operation is the same as the correction at the time of the first chip dressing or chip replacement. Further, if the second total wear amount δ ′ calculated at the time of spot welding exceeds the value obtained by adding the use limit wear amounts of the movable side electrode tip 36 and the fixed side electrode tip 37 stored in advance,
In the same procedure as the correction at the time of tip dress or tip replacement,
First of movable side electrode tip 36 and fixed side electrode tip 37
The wear amount is calculated to determine which electrode tip is the limit of use, and at that point the robot retracts to the electrode tip replacement position, outputs a replacement request signal, and executes a program that automatically performs automatic tip replacement. It is also possible to do so. As described above, if the function of detecting and correcting the amount of wear of the chip is timely and periodically, the management of the chip can be automated. Further, if the correction at the time of tip dressing or tip replacement and the correction at the time of welding are used together, more appropriate correction becomes possible.

[Control Wiring Means in Control Device of Robot for Air Spot Gun Welding] FIG. 5 is a conceptual diagram showing the wiring and the circuit configuration of the third embodiment of the present invention.
Although the air spot gun 30 is used in this embodiment, it goes without saying that the electric spot gun 30 can be applied. In the present embodiment presented here, as shown in FIG. 5, the gun control cable 22 from the air [or electric] spot gun 30 does not pass through the relay section 25, but directly.
It is connected to the robot controller 15 and wired so that all signals including the trans-thermo signal are transmitted.
That is, the transformer thermo signal line 24 of the air spot gun 30, which is only one wire from the air spot gun 30 to the welding machine 20 in FIG.
Then, along with the signals related to other gun control signal cables,
Robot controller 15 directly from gun control cable 22
Nothing is wired to the welding machine 20 from the air spot gun 30, which is efficient. In addition, since it was summarized as a welding abnormality so far, the robot side stopped and investigated the welding machine for the cause, but it is easy to operate the robot because the reason is a transtherm abnormality After returning to, it becomes possible to perform processing such as setting an alarm, and there is no need to check the welding machine.

[Means for Teaching Workpiece Abutting Position of Fixed Side Electrode Tip in Controller for Electric Spot Gun Welding Robot] As a fourth embodiment of the present invention, an equalizing mechanism is not provided and teaching is not performed for each welding. The means for performing fixed-side electrode correction on a plurality of works in a timely manner will be described. Less than,
This embodiment will be described with reference to the drawings. This embodiment is shown in FIG.
2 is a means for applying the electric gun of FIG. FIG. 6 is an explanatory view of a teaching means of a work contact position of the fixed side electrode tip, and FIG. 6A is an explanatory view and a diagram for registering a reference position (position of the gun motor 31) of the movable side electrode tip during idle driving. 6 (b) is an explanatory diagram when contact teaching is performed after setting teaching symmetrical work conditions (thickness s, welding number t). The circuit configuration and operation of each part in FIG. 1 and FIG. 2 have been described above, and the description thereof will be omitted.

Therefore, the teaching means of the work contact position of the fixed electrode tip 37 in the controller for the electric spot gun welding robot according to the present embodiment is as follows. First, as shown in FIG. 6A, the movable-side electrode chip 3 during blank driving is used.
The reference position 6 (position of the gun motor 31) p of 6 is registered.
Next, the teaching symmetrical work conditions (thickness s, number of welds t) are set. The robot is then operated to properly teach the vertical positioning of the gun at the position of the approach for welding. Next, as shown in FIG. 6B, the movable electrode chip 3
6 is slowly contacted in the contact monitoring state (contact torque detection state of the gun motor 31). Where the contact position is q
Then, when the third correction amount η for teaching is obtained in the robot controller 15 as shown in FIG. 6, η = (p−q) − (s × t). Then, when contact teaching is designated and taught in this contact state, the fixed electrode portion 35 is corrected by the third correction amount η (the fixed electrode tip 37 is in contact with the work W). Be taught in. The position can be confirmed by manually moving to that position after teaching. In this way, the present embodiment does not include a gun equalizing mechanism and does not need to teach the workpiece to contact each time welding is performed.
It is also advantageous in terms of cost and efficiency.

[0015]

As described above, according to the present invention,
In an environment where there is almost no work position displacement, the equalization mechanism and wear detection sensor can be eliminated, and electrode management can be automated from electrode position correction based on wear, which shortens the design / implementation schedule and reduces costs. It is possible to achieve a particular effect that the reduction can be achieved. further,
From the improvement of the circuit configuration on the wiring of the present invention, efficiency in design and implementation is improved, cost reduction can be expected, and it is possible to deal with trans-thermo abnormalities in detail, thus improving safety and workability. There is. Furthermore, according to the means of the present invention which does not require the equalizing mechanism and does not teach the contact with the work, the contact position of the fixed side electrode can be easily taught.
By shortening the teaching time for abutting teaching and omitting the equalizing mechanism, it is possible to expect more freedom in gun design and cost reduction.

[Brief description of drawings]

FIG. 1 is a conceptual perspective view showing an example of a system to which the present invention is applied.

FIG. 2 is a side view showing an electric spot gun according to first, second and fourth embodiments of the present invention with a part thereof cut away.

FIG. 3 is a partial side view showing the configuration of the first embodiment of the present invention, in which (a) shows a reference electrode position by hitting with a reference electrode tip at the time of teaching, and playing back to obtain a first wear amount. (B) is a state diagram in which the robot is moved to teach the approach position where the movable side electrode tip can be brought into contact with the reference fixed object, and the movable side electrode tip is brought into contact with the reference fixed object from this position.

FIG. 4 is a partial side view showing a configuration of a second embodiment of the present invention, (a) is a state diagram in which teaching is performed with a reference electrode tip at the time of teaching, and (b) is a state of a real work piece during playback during playback. State diagram of contact

FIG. 5 is a conceptual perspective view showing a circuit configuration of a third embodiment of the present invention.

FIG. 6 is a partial side view showing a configuration of a fourth embodiment of the present invention, (a) is a state diagram in which a reference position of a reference fixed side electrode tip is registered at the time of teaching, and (b) is a teaching target work condition (thickness).・ State diagram when teaching the contact by setting the number of welds)

FIG. 7 is a conceptual perspective view showing a system example in a conventional example.

[Explanation of symbols]

 10 Spot Robot 11 Power Supply Cable (for Robot Drive Power Supply) 15 Robot Controller 16 Programming Pendant (for Robot) 20 Welding Timer 21 Reference Fixed Object 22 Gun Control Signal Cable 23 Gun Control Signal Line 24 Trans Thermo Signal Line 25 Relay Section 28 Welding control signal 29 Power cable 30 Electric spot gun (or air spot gun) 31 Gun motor 32 Welding transformer 33 Drive part 34 Movable side electrode part 35 Fixed side electrode part 36 Movable side electrode tip 37 Fixed side electrode tip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Kamei, No. 2 Kurosaki Shiroishi, Yawatanishi-ku, Kitakyushu, Fukuoka Prefecture Yasukawa Electric Co., Ltd. (72) Inventor Kiyotaka Watanabe, No. 2 Kurosaki Shiroishi, Hachimansai-ku, Kitakyushu, Fukuoka Yasukawa Electric Co., Ltd.

Claims (9)

[Claims] 1. A device for controlling a robot for resistance-welding an object to be welded with an electric spot gun, means for idle driving with a reference electrode tip at the time of teaching, and means for bringing a movable side electrode into contact with a reference fixed object. And a means for storing the robot position and the gun motor position at the time of blank hitting and abutting, and the electrode tip used at the time of the program playback to make a blank hit and contact the fixed object with the difference in position from that at the time of teaching. It has means for calculating wear amounts of the movable side electrode tip and fixed side electrode tip and a correction amount obtained therefrom, and means for correcting the positions of the movable side electrode tip and the fixed side electrode tip by the correction amount. A controller for a spot welding robot, which is characterized in that 2. A robot is moved to teach an approach position C at which the movable side electrode tip can be contacted with a reference fixed object by performing a blank shot at the time of teaching, storing the position A of the movable side electrode tip at this time. , The movable side electrode tip is brought into contact with the reference fixed object from the position C, the movement amount of the position of the gun motor of the difference α from the position D of the movable side electrode tip at this time is stored, and the same blank ejection is performed. And the reference fixed object abutment are taught in a program for tip dressing or tip exchange, and the blank driving taught in the program for tip dressing or tip exchange is reproduced, and the position B of the movable side electrode tip is reproduced. Position of the gun motor and position A during teaching
And the difference δ becomes the first total (movable side + fixed side) wear amount, and the contact with the reference fixed object, which was also taught, is reproduced to obtain the approach position C ′. Position D
Δ: First total (movable side + fixed side) wear amount, that is, first movable side correction amount α: Reference stroke length β: First wear stroke length γ = β- α: first movable side wear amount ε = δ− (β−α): first fixed side wear amount, that is, first
As the fixed side correction amount of, the movable side electrode tip is corrected by the first movable side correction amount indicated by δ, and the fixed side electrode tip is corrected by the first fixed side wear amount indicated by ε. A method for controlling a robot for spot welding, which is characterized by a correction. 3. When teaching, the gun motor position at the position of the movable side electrode tip is stored in the reference work under the same pressurization state as during welding, or the gun motor position at the blanking position, the plate pressure, and the number of welds. And a means for storing spots with the electrode used during program reproduction and adding the respective wear amounts of the movable side electrode tip and the fixed side electrode tip from the position of the movable side electrode tip at this time. A second amount of wear of the movable side electrode tip and the fixed side electrode tip from the first amount of wear and the first amount of wear and the first amount of wear; The controller of the spot welding robot according to claim 1, wherein wear of the electrode tip is corrected based on the second correction amount during a calculation cycle of the correction amount of 1. 4. A difference .delta. 'Between the position of the movable electrode tip registered in advance in a pressurized state at the position of the gun motor and the position of the gun motor at the pressed position during welding this time.
Then, δ ′: the second total (movable side + fixed side) wear amount, that is, the second
Movable side correction amount ε ′ = ε + {(δ′−δ) / 2}: from the second fixed side wear amount, that is, the second fixed side correction amount, to the second movable side correction amount δ ′ and the second fixed side correction amount δ ′. The control method for a spot welding robot according to claim 2, wherein the fixed side correction amount is calculated by ε ', and the correction is performed when the welding operation program is reproduced. 5. A means for storing the wear limit wear amount of the movable side electrode tip and the fixed side electrode tip is provided, and an alarm signal is issued when the first wear amount exceeds the value of the use limit wear amount. The controller for the spot welding robot according to claim 1, wherein the controller performs output or automatic tip replacement. 6. When the second total wear amount exceeds a value obtained by adding the movable side electrode tip and the fixed side electrode tip of the use limit wear amount set in advance, after welding is completed,
An alarm signal is output, or the first wear amount of the movable-side electrode tip and the fixed-side electrode tip is calculated, and which of the tips is used is judged to output an alarm signal or an automatic tip. The control device for the spot welding robot according to claim 1, wherein the robot is replaced. 7. A device for controlling a robot for resistance welding of an object to be welded with a spot gun, means for inputting a thermostat signal of a welding transformer of a spot gun, means for stopping welding operation by the signal, and outputting an alarm. A controller for a spot welding robot, which comprises: 8. A device for controlling a robot for resistance welding an object to be welded with a gun motor driven spot gun, means for setting a plate thickness of a work piece and the number of welds, and a welding position of the fixed side electrode with a robot shaft at the time of teaching. Means to move to
A means for bringing the movable side electrode into contact with the work, a means for calculating a movement amount for bringing the fixed side tip into contact with the gun motor position at the time of the contact, and a means for contacting the fixed side electrode with the movement amount. A controller for a spot welding robot, comprising a means for calculating and teaching a contact position. 9. The position p of the gun motor at the reference position of the movable side electrode tip at the time of blank driving is registered, the thickness s and the number of welds t of the work object to be taught are set, and the robot is operated to perform welding. When the vertical positioning of the gun is taught to the approach position of (1), the movable side electrode tip is slowly contacted in the contact torque detection state of the gun motor in the contact monitoring state, and the contact position is q, A control method for a spot welding robot, characterized in that a third correction amount η for teaching is obtained as η = (p−q) − (s × t) and teaching is performed in this contact state.