JPH0368793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a teaching device for an automatic seam welding robot.

(Prior Art) The present applicant has developed a teaching device for a robot in an automatic seam welding machine in which a workpiece is held by a multi-axis robot and the welded part is fed between a pair of electrode rolls provided in the seam welding machine. A robot model having the same mechanical dimensions and operation as the robot is constructed, each encoder is connected to each axis of the model via a reducer, and the model and a separate teaching roll are used. An apparatus has been proposed which is provided with a sampling period oscillator that defines the sampling period of the output signal from each encoder obtained when a teaching operation is performed, and a storage device that stores the sampled position data.

(Problems to be Solved by the Invention) The above-mentioned teaching device does not have a driving source like a robot, so the workpiece is held in a robot model, fed to a teaching roll, and teaching data is obtained from the output of each encoder. In this case, the robot model can be operated with a light force, but it is desirable to be able to operate it with an even lighter force.

Furthermore, since teaching was performed by rotating the teaching roll at the same speed as when the robot was actually operating, it was difficult to feed the corners of the workpiece to the teaching roll at the same speed, which resulted in accurate teaching. I can't get it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a teaching device for an automatic seam welding robot that can teach with a light force and at a slow speed.

(Means for Solving the Problems) The present invention provides a robot in an automatic seam welding apparatus in which a workpiece is held by a multi-axis robot and the welded part is fed between a pair of electrode rolls provided in a seam welding machine. The teaching device is a robot model that has the same mechanical dimensions and motion as the robot, and is connected to each axis of the model on the output side of a robot drive source connected to each axis of the robot. Each encoder is connected via a model reducer having a smaller reduction ratio than the reducer, and teaching work is performed using the model and the electrode roll or a separate teaching roll corresponding to the electrode roll. a sampling period oscillator that defines the sampling period of the output signal from each encoder obtained when The drive speed of the robot drive source is rewritten according to the ratio with the reduction ratio of the model reducer, and the drive speed of the robot drive source is changed according to the ratio between the speed of the electrode roll or teaching roll during teaching work and the speed of the electrode roll during actual work. The present invention is characterized in that it is provided with an arithmetic device that performs arithmetic operations.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1-3 illustrate an automatic seam welding position with a multi-axis robot taught by a robot teaching device.

In the figure, 1 indicates the body of a seam welding machine, and a pair of upper and lower electrode rolls 2 ₁ are installed at the front of the body 1.
2 ₂ and a drive source 3 for the rolls 2 ₁ and 2 ₂ at the rear thereof.
₁ , 3 and ₂ were established. The upper electrode roll 2 ₁ is pivotally supported by an electrode holder 5 ₁ that is raised and lowered by a pressurizing cylinder 4 and is rotationally driven by a drive source 3 ₁ via a knurl gear 6, and the lower electrode roll 2 ₂ is fixed to the body 1. It is assumed that the electrode holder ₅₂ is pivotally supported and rotationally driven by the drive source ₃₂ , and the welded part of the workpiece W such as a fuel tank for a two-wheeled vehicle is touched by lowering the upper electrode roll _{21 .} In this state, both the rolls 2 ₁ and 2 ₂ are rotated, and the transformer 7 mounted on the rear of the body 1 is connected to the rolls 2 1 and 2 2 .
The welded portion is seam welded by applying electricity through the ounce copper plate 8, and during this seam welding, the workpiece W is guided to weld the welded portion between the two rolls 2 ₁ ,
_2. A multi-axis robot a (hereinafter simply referred to as robot 9) is attached to the machine body 1 in order to feed the robot in synchronization with the rotation between 2 and 2.
Equipped with.

The robot 9 includes a robot body 1 which is rotatably pivoted about a first axis 11a perpendicular to a base 10 fixed to the upper surface of the robot body 1;
a first arm 12 that extends forward and is pivotably mounted on the top of the first arm 12 so as to be swingable about a horizontal second shaft 12a;
A second shaft extending downward is provided at the tip of the first arm 12 so as to be swingable about a horizontal third shaft 13a.
It consists of an arm 13 and a wrist 14 attached to the lower end of the second arm 13 so as to be always held in a constant position by a parallel ruler mechanism (not shown), and is rotatable around a fourth axis 15a perpendicular to the wrist 14. A wrist arm 15 is provided as a shaft, and a cross joint 1 is attached to the arm 15.
6, the workpiece holder 17 is attached to each axis 1.
1a, 12a, 13a, and 15a are rotationally controlled by separate drive sources 18 ₁ , 18 ₂ , 18 ₃ , and 18 ₄ each equipped with a speed reducer, and the workpiece W held by the holder 17 is moved along a predetermined teaching trajectory. I made it possible to lead them to the street.

Next, a robot teaching device used for teaching the robot of the automatic seam welding apparatus will be explained.

4 to 6, reference numeral 101 includes a pair of upper and lower teaching rolls 102 ₁ , 102 ₂ corresponding to the electrode rolls ₂ 1 , 2 ₂ disposed at predetermined positions, and a driving source 103 thereof. A teaching frame body having a configuration similar to that of the seam welding machine is shown, and a robot model 109 having the same mechanical dimensions and operation as the robot 9 is shown, and the relative position with respect to the teaching rolls 102 ₁ and 102 ₂ is the same as that of the electrodes. It is assumed that the robot 9 is mounted on the frame 101 so as to be mechanically in the same relative position as the robot 9 with respect to the rolls 2 ₁ and 2 ₂ .

To explain this in more detail, the lower teaching roll 102 _{2 is pivotally supported on a holder 105 2 fixed} at the middle part of the frame 101 in the height direction, and a pressure cylinder 104 is placed above the holder 105 ₂ in the vertical direction. A holder 105 ₁ is provided, which is pivoted to swing the upper teaching roll _{102 1 ,} and a driving source 103 is attached to the tail end of the holder 105 ₁ . If the upper teaching roll 102 ₁ is rotated at a predetermined circumferential speed by the drive source 103 with the welded part of the workpiece W sandwiched between 102 ₂ and 102 2 , the lower teaching roll 102
₂ is driven to rotate, and the two rolls 102 ₁ , 102
The welded part was drawn in between _{the two} . 1 in drawings
02a indicates a peripheral speed detector of the upper teaching roll ₁₀₂₁ .

The robot model 109 includes a robot model body 111 that is rotatably pivoted about a first axis 111a perpendicular to a base 110 fixed to the upper surface of the frame 101, and a robot model body 111 that is attached to the top of the robot model body 111. A first arm 112 extends forward and is pivotably pivoted about a second horizontal shaft 112a, and a first arm 112 is pivotably pivoted about a third horizontal shaft 113a at the tip of the first arm 112. a second arm 113; and a lower end of the second arm 113, each arm 112,
A pair of links 114a, 114b parallel to 113
A wrist arm 114 is attached to the wrist 114 so as to be always held in a constant position by a link type parallel ruler mechanism, and a wrist arm 115 is rotatable about a fourth axis 115a perpendicular to the wrist 114.
A workpiece holder 17 is attached to the arm 115 via the same cross joint 16 as the robot 9, and a reducer 119 is attached to the base 110 as shown in FIG.
A first encoder 120 ₁ is connected to the first shaft 111a via a first encoder 120 ₁ , and a first encoder 120 1 is connected to the second shaft 112 a via a reducer 119 ₂ on one side of the shaft support of the second shaft 112 a of the robot model main body 111. A _second encoder 120 ₂ is connected to a second
A third shaft connected to the third shaft 113a of the arm 113
The encoder 120 ₃ is attached to the wrist 114 as shown in the fourth figure, and the _fourth
A fourth encoder 120 ₄ coupled to the shaft 115a
I installed it.

Here, the first and second arms 112, 113,
The wrist 114 and wrist arm 115 are configured to have the same mechanical dimensions as those of the actual robot 9 described above, and the robot model main body 111 is
Teaching roll 10 of shaft 111a and second shaft 112a
2 ₁ and 102 ₂ is mechanically the same as the relative position of the first and second shafts 11a and 12a of the robot 9 with respect to the electrode rolls 2 ₁ and 2 ₂ .

In addition, reducers 119 ₁ , 119 ₂ , 119 ₃ , 1
19 ₄ is a drive source 18 ₁ , 18 for each axis of the robot 9
₂ , 18 ₃ , 18 ₄ , and the peripheral speed of the teaching roll 102 ₁ by the drive source 103 is controlled by the upper and lower electrodes by the robot's drive sources 3 ₁ , 3 ₂ . Roll 2 ₁ , 2 ₂
The circumferential speed was set to be lower than the circumferential speed of

In the drawing, 122 indicates the robot model body 111 and the first
A balance sampling is shown stretched between the tip of the arm 112.

FIG. 8 shows the encoders 120 ₁ , 120 ₂ ,
FIG. 2 is a block diagram showing a configuration for obtaining teaching data from the outputs of 120 ₃ and 120 ₄ .

As shown in the figure, encoders 120 ₁ , 12
Each axis 111 obtained from 0 ₂ , 120 ₃ , 120 ₄
The position signals of a, 112a, 113a, and 115a are passed through a direction discriminator 124, sampled at every sampling period of a predetermined time defined by a sampling period oscillator 123, and sent to a current value counter 1.
Count to 25 and convert this count value to buffer 1
26, it is configured to be stored in the memory 127 via the CPU 129.

According to the CPU 129, the position data sampled and stored in the memory 127 includes the reduction ratios of the reduction gears attached to the drive sources 18 ₁ to 18 ₄ of the respective axes of the robot 9 and the reduction gear 119 of the robot model 109.
The ratio with the reduction ratio of ₁ to 119 ₄ , that is, the difference in reduction ratio A, is multiplied, and the deviation amount D ₁ between each sampling of the obtained corrected position data is calculated as the feed rate at the time of teaching the workpiece W to the sampling period T ₁ . (peripheral speed of teaching roll 102 ₁ ) and feeding speed during robot actual operation (peripheral speed of upper and lower electrode rolls 2 ₁ and 2 ₂ )
The arithmetic operation of dividing by the ratio s ₁ multiplied by 1 is now performed.

In FIG. 8, 128 is an initial value setter for setting the origin position data of the robot.

Next, the operation of the above embodiment will be explained.

A workpiece W is held in a robot model 9, and the welded part of the workpiece W is fed between teaching rolls 102 ₁ and 102 ₂ in synchronization with the rotation of the workpiece W at a lower feed rate than when the robot is actually operating. Encoder 120 ₁ for each axis
The position signal output from ₁₂₀₄ is sampled every sampling period _T1 by the sampling period oscillator 123 as described above and is stored in the memory 127.
is stored in This flow is shown in steps ~ in the flowchart shown in Figure 9. When the teaching is completed, the position data stored in the memory 127 is first rewritten by multiplying the position data for each sampling step by the speed reduction ratio difference A (step). Next, in the step, the deviation D ₁ between each sampling step of the position data obtained by multiplying, that is, the displacement amount, is calculated according to the sampling period T ₁
is multiplied by the ratio _s1 to calculate the feed speed of each arm when the robot is actually operating (step). This calculation is performed for all sampling steps (steps), and the converted teaching data is stored in the memory 127.

In seam welding, the feed speed of the welding part of the work W with respect to the circumferential speed of the electrode rolls 2 ₁ and 2 ₂ causes slippage depending on the circumferential speed and welding conditions.
The teaching data stored in the memory 127 is further arithmetic-modified using software and is used as control data for the robot.

In the above embodiment, the teaching rolls 102 ₁ , 10
₂ Robot model 1 is attached to the teaching frame 101 having 2
Although the robot model 109 is mounted on the seam welding machine body 1, in this case,
The speed of the electrode roll during teaching is lower than the speed of the electrode roll during actual robot operation, as is the speed of the teaching roll.

(Effects of the Invention) As described above, according to the present invention, a model reducer having a smaller reduction ratio than the robot reducer on the output side of the robot drive source connected to each axis of the robot is attached to each axis of the robot model. Since each encoder is connected via the It is rewritten according to the ratio of the reduction ratio of the reduction gear for the model and the reduction ratio of the reduction gear for the model, and it is also rewritten according to the ratio of the speed of the electrode roll during teaching work or the speed of the teaching roll and the speed of the electrode roll during actual operation. Since a calculation device is provided to calculate the drive speed of the robot drive source, it is possible to teach at a slow speed.

[Brief explanation of drawings]

FIG. 1 is a side view of an automatic seam welding device having a robot, FIG. 2 is a front view thereof, FIG. 3 is a plan view thereof, FIG. 4 is a side view of an example of the robot teaching device of the present invention, and FIG. The figure is a front view, FIG. 6 is a plan view, and FIG. 7 is an enlarged cross-sectional view taken along the line - in FIG.
FIG. 8 is a block diagram of the robot teaching device, and FIG. 9 is a float chart. DESCRIPTION OF SYMBOLS 1... Seam welding machine body, 2 ₁ , 2 ₂ ... Electrode roll, 9... Multi-axis robot, 101... Teaching frame, 102 ₁ , 102 ₂ ... Teaching roll, 10
9... Robot model, 120 ₁ , 120 ₂ , 120
₃ , 120 ₄ ...Encoder, 125...Current value counter, 127...Memory, 129...CPU.

Claims (1)

[Claims] 1. A teaching device for a robot in an automatic seam welding device in which a workpiece is held by a multi-axis robot and the welded part is fed between a pair of electrode rolls provided in a seam welding machine, and the robot has the same mechanical dimensions as the robot. A robot model with the same operation is configured, and a model reducer having a smaller reduction ratio than the robot reducer on the output side of the robot drive source connected to each axis of the robot is connected to each axis of the model. Sampling of output signals from each encoder obtained when each encoder is connected to each other and a teaching operation is performed using the model and the electrode roll or a separate teaching roll corresponding to the electrode roll. a sampling period oscillator that defines a cycle; a storage device that stores sampled position data; The present invention is characterized by being provided with a calculation device that calculates the driving speed of the robot drive source according to the ratio of the speed of the electrode roll or teaching roll during teaching work and the speed of the electrode roll during actual work. Automatic seam welding robot teaching device.