JPH0338954B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention includes a seam welding machine equipped with a pair of electrode rolls, which is equipped with a multi-axis robot. The present invention relates to a teaching device for a robot in an automatic seam welding apparatus, which guides the welding part to feed the welded part between the electrode rolls.

(Prior art) The above automatic seam welding device was previously proposed by the applicant in Japanese Patent Application No. 58-226988. In this case, each axis of the robot is determined by calculation from the shape of the welded part of the workpiece. The system operates according to the numerical data provided.

(Problem to be solved by the invention) In the case of a workpiece where the shape of the welded part changes three-dimensionally, such as a fuel tank for a two-wheeled vehicle, the above method requires a large computer to obtain numerical data for each axis. In addition, there is a problem that inputting the shape becomes troublesome.

By the way, as a conventional teaching device for a painting robot, according to Japanese Patent Publication No. 54-43258, a teaching device for a painting robot that has the same mechanical dimensions and movements as the robot and that has the same mechanical dimensions and movements as the robot is installed on the mounting table of the painting robot placed on the side of the workpiece conveyance path. It is known that instead of a drive source, a robot model with connected encoders is installed side by side, and the model is moved by an operator to perform teaching work.Using this technology, the body of a seam welding machine has been developed. The above-mentioned robot and a robot model are mounted so that they can be shifted freely relative to each other, and with the robot model shifted to the robot mounting position, teaching work is performed by holding a workpiece on the robot model, and the position of each axis of the model is determined from the encoder. It is also conceivable to store data in a storage device and operate the robot using a reproduction signal from the storage device.

However, because this type of seam welding machine must be equipped with a robot, a robot model, and its shift mechanism, the seam welding machine becomes large and
Furthermore, due to the difficulty of accurately shifting and positioning the robot and the robot model to the same position, the relative position of the robot model to the electrode roll during teaching and the relative position of the robot to the electrode roll during actual operation may be slightly different. There is a problem in that errors occur and the workpiece cannot be guided as instructed during actual operation.

Also, during teaching, it is desirable to rotate the electrode roll at a lower speed than during actual operation to make the teaching work easier.In this case, even if the teaching work is performed with power being supplied to the electrode roll, the obtained teaching data will Experiments have confirmed that when the robot is controlled during actual operation, the seam welding line of the welded part of the workpiece deviates from the normal taught line.

This is because the difference in the heating time of the workpiece between the electrode rolls causes a difference in the degree of melting of the workpiece during teaching and during actual operation, and the slip rate of the workpiece relative to the electrode roll changes, causing the actual melting of the workpiece by the electrode roll. This is thought to be due to the synchronization between the feed speed and the robot's operating speed being out of sync. By correcting the teaching data according to the welding conditions such as the circumferential speed of the electrode roll and welding current and operating the robot, the deviation of the seam weld line can be reduced. In other words, even if the teaching work is performed without energizing the electrode roll, it has been found that seam welding can be performed accurately by appropriately correcting the teaching data later.

In the present invention, if there is no problem even if the teaching work is performed without energizing the electrode roll as described above, even if a separate teaching device is provided, there is no need to install a transformer in this device, and the cost is also reduced. Focusing on the fact that the robot model is not a burden, we aim to solve the above-mentioned problems when mounting a robot model on a seam welding machine in parallel with the robot, and to provide a device that allows teaching work to be performed easily. That purpose.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the same mechanical dimensions and operation as a multi-axis robot mounted on the body of a seam welding machine equipped with a pair of electrode rolls. A robot model is prepared in which each encoder is connected to each axis in place of a drive source, and a teaching frame is provided separately from the robot body, which includes a pair of teaching rolls corresponding to the electrode rolls and a driving source thereof. The robot model was mounted on the frame so that the relative position with respect to the teaching roll was mechanically the same as the relative position of the robot with respect to the electrode roll.

(Function) The robot model holds the workpiece, and while the teaching roll is rotated at a predetermined circumferential speed by a drive source, the operator guides the workpiece and synchronizes the welding part between the teaching rolls with the rotation. The position data of each axis of the model detected by each encoder is inputted at predetermined time intervals to a suitable storage device and stored therein.

During this teaching work, each axis of the robot model is
Unlike when teaching is performed directly using a robot mounted on an actual machine, the robot moves smoothly as the workpiece moves without being subjected to any load from a driving source, and therefore the workpiece can be guided with a light force, making the teaching task easier.

In addition, the relative position of the robot model mounted on the teaching frame and the teaching roll, and the relative position and mutual positional accuracy of the robot and electrode roll mounted on the body of the seam welding machine are also important. This is improved because there is no difficulty in positioning when a robot model is mounted in a shiftable manner.

Furthermore, the teaching frame body is only equipped with the teaching roll, its driving source, and the robot model;
It is much smaller than a seam welding machine equipped with a transformer, and teaching work can be done by placing the frame in an appropriate dead space such as the spacing of the seam welding machine, making effective use of factory space. can be achieved.

(Example) Embodiments of the present invention will be described based on the drawings.

Referring to FIGS. 1 to 3, reference numeral 1 indicates the body of a seam welding machine, and a pair of upper and lower electrode rolls 2 ₁ , 2 ₂ is provided at the front of the body 1 , and each roll 2 ₁ is provided at the rear of the body 1 . ，
2 ₂ drive sources 3 ₁ and 3 ₂ are provided, where the upper electrode roll 2 ₁ is pivotally supported by an electrode holder 5 ₁ that is raised and lowered by a pressure cylinder 4, and is driven by the drive source 3 ₁ through a knurl gear 6. The lower electrode roll 2 ₂ is pivotally supported by an electrode holder 5 ₂ fixed to the body 1 and rotationally driven by a drive source 3 ₂ , and the lower electrode roll 2 2 is rotatably driven by a drive source 3 2 . When the upper electrode roll 2 ₁ descends, _the welded _portion of
₂ is rotationally driven, and electricity is supplied to it from a transformer 7 mounted at the rear of the fuselage 1 through an ounce copper plate 8 to perform seam welding of the welded portion,
A robot 9 is mounted on the machine body 1 in order to guide the workpiece W during this seam welding and feed the welded portion between the rolls 2 ₁ and 2 ₂ in synchronization with the rotation thereof.
In the drawing, 2a indicates a circumferential speed detector of the upper electrode roll ₂₁ .

The robot 9 includes a robot body 11 which is rotatably pivoted about a vertical first axis 11a on a base 10 fixed to the top surface of the robot body 1, and a horizontal second axis at the top of the robot body 11. A first arm 12 that extends forward and is pivotably installed around a shaft 12a.
and a horizontal third shaft 13 at the tip of the first arm 12.
A second arm 13 extends downward and is pivotably pivoted around a, and a wrist 14 is attached to the lower end of the second arm 13 so as to be always maintained in a constant position by a parallel regulating mechanism (not shown). A wrist arm 15 rotatable about a fourth axis 15a perpendicular to the wrist 14 is installed on the wrist 14, and a workpiece holder 17 is attached to the arm 15 via a cross joint 16.
The respective shafts 11a, 12a, 13a, 15a are driven by separate drive sources 18 ₁ , 18 ₂ , 18 ₃ , each equipped with a reduction gear.
18 ₄ so that the workpiece W held by the holder 17 can be guided along a predetermined trajectory.

In the illustrated example, the robot body 11 has a second
In addition to the drive source 18 ₂ for the shaft 12a, the third shaft 13a
A drive source 18 ₃ for use in the third shaft 13a is mounted, and the third shaft 13a is rotated by the drive source 18 ₃ via a chain (not shown).

The above description is not particularly different from the automatic seam welding apparatus previously proposed by the applicant of the present invention, and a detailed description thereof will be omitted, and the teaching apparatus which is a feature of the present invention will be described below.

Referring to FIGS. 4 to 6, reference numeral 101 denotes a teaching frame body comprising a pair of upper and lower teaching rolls 102 ₁ , 102 ₂ corresponding to the electrode rolls 2 ₁ , 2 ₂ and a driving source 103 thereof. A robot model 109 having the same mechanical dimensions and operation as the robot 9 is shown.
The relative position with respect to the teaching rolls 102 ₁ , 102 ₂ is the position of the robot 9 with respect to the electrode rolls 2 ₁ , 2 ₂ .
The lower part of the holder 105 ₂ fixed to the middle part of the frame 101 in the height direction will be described in more detail. A teaching roll 102 ₂ is pivotally supported, and a pressure cylinder 10 is placed above the holder 105 ₂ .
4, a holder 105 ₁ is provided which swings vertically about a pivot 105a, and the holder 10
The upper teaching roll 102 ₁ is pivotally supported on the upper teaching roll 102 ₁ and the driving source 103 is attached to the tail end _{of the upper teaching roll 102 1 .}
The upper teaching roll 10 is held between the welded parts of
2 ₁ is rotationally driven by the drive source 103 at a predetermined circumferential speed, the lower electrode roll 102 ₂ is driven to rotate via the workpiece W, and both rolls 102
_1,102 The welded part was drawn in between ₂ ,
In the drawing, 102a indicates a peripheral speed detector of the upper teaching roll ₁₀₂₁ .

The robot model 109 has a robot body 11 that is rotatably pivoted about a first axis 111a perpendicular to a base 110 fixed to the upper surface of the frame 101.
1 and a second horizontal part on the top of the robot body 111.
A first arm 112 that extends forward and is pivotably installed around a shaft 112a, and the first arm 11
A second arm 113 is provided at the tip of the second arm 113 to be swingable about a horizontal third shaft 113a, and each arm 112, 113 is provided at the lower end of the second arm 113.
It consists of a wrist 114 attached so that it is always maintained in a constant posture by a link type parallel ruler mechanism consisting of a pair of links 114a and 114b parallel to the
A wrist arm 115 that is rotatable about a fourth axis 115a perpendicular to the wrist 114 is mounted on the wrist 114, and a cross joint 16, which is the same as the robot 9, is attached to the arm 115.
The workpiece holder 17 is attached through the
Here, the first and second arms 112, 113, the wrist 11
4. The wrist arm 115 is configured to have the same mechanical dimensions as those of the actual robot 9 described above, and the robot main body 111 is constructed with the teaching rolls 102 ₁ and 102 of the first shaft 111a and the second shaft 112a. ₂
The relative position to the first and second axes 11 of the robot 9
a, 12a relative to the electrode rolls 2 ₁ , _{2 2} mechanically, and as shown in FIG. the first encoder 120 ₁ connected to the robot body 111 and the second shaft 11 of the robot body 111
A second encoder 120 is connected to the second shaft 112a via a reducer ₁₁₉₂ on one side of the shaft support of the shaft 2a.
₂ and the reducer 119 on the other side ₃ and the first arm 11
2 through a link 121 parallel to the second arm 1
13, that is, a third encoder ₁₂₀₃ connected to the third shaft 113a, and a fourth encoder connected to the fourth shaft 115a via a reducer ₁₁₉₄ , as shown in FIG. 4, on the wrist 114. I installed 120 ₄ .

In the drawing, 121a is a rotating arm connected to the reducer ₁₁₉₃ , 121b is a connecting piece that connects the arm 121a and the link 121, and 122 is a connecting piece stretched between the robot body 111 and the tip of the first arm 112. The balancer spring is shown below.

Using the teaching device configured as described above, an operator holds the workpiece W in the robot model 109 and guides the workpiece W while rotating the teaching rolls 102 ₁ and 102 ₂ at a predetermined circumferential speed. is sent between the rolls 102 ₁ , 102 ₂ in synchronization with the rotation thereof, and the first to fourth echoders 120 ₁ , 1
Each axis 111a from 20 ₂ , 120 ₃ , 120 ₄ ,
As shown in FIG.
direction discriminator 1 at predetermined time intervals defined by
24, the current value is input to the memory 127 via the counter 125 and the buffer 126, and after this teaching work is completed, the current value is input to the memory 127 according to the welding conditions such as the peripheral speed of the electrode rolls 2 ₁ and 2 _{2 and} the welding current during actual operation. The stored teaching data is calculated and corrected using software to create control data for the actual robot 9. In the drawing, 128 is an initial value setter, and 129 is a CPU.

(Effects of the Invention) As described above, according to the present invention, teaching work can be performed with light force using a robot model, work efficiency is improved, and the teaching work is provided in a frame separate from the body of the seam welding machine. Since the roll and the robot model are mounted in a predetermined positional relationship, the seam welding machine can be made smaller and the robot It has become easier to ensure the positional accuracy of the model,
Accurate teaching data that matches the positional relationship between the robot and the electrode roll can be obtained, and the frame can also be made smaller, allowing appropriate dead space in the factory to be used as a teaching work area, reducing factory space. It has the effect of promoting effective use.

[Brief explanation of drawings]

FIG. 1 is a side view of an automatic seam welding device, FIGS. 2 and 3 are a front view and a plan view thereof, respectively, FIG. 4 is a side view of an example of the teaching device of the present invention, and FIGS. 5 and 6.
The figures are a front view and a plan view, respectively, FIG. 7 is an enlarged sectional view taken along the line -- in FIG. 4, and FIG. 8 is a block diagram of a storage device for storing signals from the encoder. DESCRIPTION OF SYMBOLS 1... Seam welding machine body, 2 ₁ , 2 ₂ ... Electrode roll, 9... Robot, 101... Teaching frame, 102 ₁ , 102 ₂ ... Teaching roll, 103
... Drive source, 109 ... Robot model, 120 ₁ ,
120 ₂ , 120 ₃ , 120 ₄ ... encoder.

Claims (1)

[Claims] 1. Teaching of a robot in an automatic seam welding device in which a multi-axis robot is mounted on the body of a seam welding machine equipped with a pair of electrode rolls, and the robot guides a workpiece and feeds the welded part between the electrode rolls. A robot model having the same mechanical dimensions and operation as the robot and having each encoder connected to each axis instead of a drive source is prepared, and a robot model corresponding to the electrode roll is prepared separately from the machine body. A teaching frame including a pair of teaching rolls and a driving source thereof is provided, and the robot model is moved so that the relative position with respect to the teaching roll is mechanically the same as the relative position of the robot with respect to the electrode roll. A teaching device for a robot in an automatic seam welding device, characterized in that it is mounted on the frame.