JPH0457434B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is an automatic seam welding machine that automatically feeds a welding part of a workpiece by an automatic machine that holds the workpiece between a pair of electrode rolls provided in a seam welding machine. The present invention relates to a method of driving an electrode roll in a seam welding device.

(Prior art) Conventionally, seam welding has been carried out using a seam welding machine equipped with
The welding part of the workpiece is sandwiched between a pair of electrode rolls, and in this state, the welding part is sequentially fed between the electrode rolls while rotating the electrode rolls.

Here, as an electrode roll, one size is different in diameter.
A pair of rolls is generally used, and conventionally, both rolls are driven by a common drive motor via a differential gear mechanism so that both rolls can rotate at the same circumferential speed.

(Problem to be Solved by the Invention) By the way, in an automatic seam welding device, the automatic machine feeds the workpiece in synchronization with the rotation of the electrode roll, and the feeding speed of the welding part of the workpiece relative to the electrode roll is controlled by the electrode roll. However, since the welded part of the workpiece is welded between the electrode rolls and slips to some extent against the electrode roll, the actual feed speed of the welded part is lower than the peripheral speed of the electrode roll. However, if this continues, the automatic machine synchronized with the rotation of the electrode roll will move in advance of the actual welding by the electrode roll, causing the welding trajectory to deviate from the normal trajectory.

In view of the above points, the present invention provides an electrode roll driving method that synchronizes the workpiece feeding operation by an automatic machine and the actual feeding of the workpiece by the electrode roll, thereby achieving accurate seam welding. Its purpose is to.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for automatically feeding a welded portion of a workpiece by an automatic machine that holds the workpiece between a pair of electrode rolls provided in a seam welding machine. In the automatic seam welding apparatus, each of the pair of electrode rolls is driven to rotate by a separate drive motor, and the workpiece is fed by the automatic machine in synchronization with the rotation of one of the electrode rolls, and the workpiece is fed by the automatic machine in synchronization with the rotation of one of the electrode rolls. The invention is characterized in that the electrode rolls are rotated such that their circumferential speed is faster than the circumferential speed of the one electrode roll.

(Function) Even if the welding part of the work slips against the electrode roll, the feed speed of the welding part can be adjusted to rotate the other electrode roll at a peripheral speed faster than the peripheral speed of one electrode roll that synchronizes the automatic machine. This speed can be made equal to the peripheral speed of the one electrode roll, and the actual feed of the welding part and the feed operation of the workpiece by the automatic machine are synchronized, and seam welding is performed along the regular welding trajectory. It will be done.

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

In the drawing, 1 is a pair of upper and lower electrode rolls 2 ₁ on the front.
2 ₂ , where the upper electrode roll 2 ₁ is attached to an electrode holder 4 ₁ that is raised and lowered by a pressure cylinder 3 , and the lower electrode holder 2 ₂ is attached to an electrode holder 4 ₂ that is fixed to the welding machine 1 . A robot 5, which is an automatic machine, is mounted on the welding machine 1, and includes a rotatable robot body 15a and a pair of swinging arms 5b, 5c. A workpiece W such as a fuel tank for a two-wheeled vehicle is held via a workpiece holder 5e, and the welding part around the workpiece W is placed on the lower electrode roll ₂₂ at a predetermined welding start point. The upper electrode roll 2 ₁ is lowered, and the welded portion is sandwiched between the electrode rolls _{2 1 and} 2 _{2 .}
The robot 5 is rotated, and in synchronization with this, the robot 5 is operated according to the taught data, and the welding part is continuously fed between the electrode rolls 2 ₁ and 2 ₂ to perform automatic seam welding.

Here, the two electrode rolls 2 ₁ , 2 ₂ are driven by separate drive motors 6 ₁ , 2 , respectively, according to the characteristics of the present invention.
In the illustrated example, a pair of upper and lower drive motors 6 ₁ and 6 ₂ are provided at the rear of the seam welding machine 1, and an upper electrode roll 2 ₁ is mounted on the circumferential surface by a cylinder _7a . The first drive motor 6 ₁ on the upper side and the lower electrode roll 2 ₂ are connected to the second drive motor 6 ₂ on the lower side at their rotating shafts via the knurled gear 7 which is pressed into contact with the upper electrode roll 2 ₁ . A first circumferential speed detector 8 ₁ having a touch roller 8 a in contact with the circumferential surface is provided, and the rotational speed of the first drive motor 6 ₁ is feedback-controlled by a signal from the detector 8 ₁ to control the upper electrode roll 2 ₁ . A touch roller 8 is rotated so that its circumferential speed is maintained at a predetermined speed, and is in contact with the circumferential surface of the lower electrode roll ₂₂ .
A second circumferential speed detector 8 ₂ having a diameter of 8.a is provided movably by a cylinder 9 between an upper operating position and a lower non-operating position, and after welding is completed, the second circumferential velocity detector 8 ₂
was moved to the operating position as shown in FIG. 1 and a test operation was performed, and the rotational speed of the second drive motor ₆₂ was adjusted so that the circumferential speed of the lower electrode roll ₂₂ became a predetermined speed. , when welding the next workpiece W, the second drive motor 6 ₂ is operated at this adjusted speed.
Thus, the lower electrode roll ₂₂ can be rotated at a predetermined circumferential speed regardless of changes in the outer diameter due to wear. During the welding work, the workpiece W is moved to the inoperative position as shown in the third figure so that it does not interfere with the second circumferential velocity detector ₈₂ .

Here, the circumferential speed of the upper electrode roll 2 ₁ driven via the knurled gear 7 is maintained at a constant speed corresponding to the rotational speed of the knurled gear 7 regardless of changes in the outer diameter, so the first circumferential speed detector 8 ₁ is not necessarily required, but there is a possibility that a change in circumferential speed may occur due to slip between both 2 ₁ and 7, so the circumferential speed of the upper electrode roll 2 ₁ should be accurately managed using the detector 8 ₁ . It is desirable to obtain.

Also, the touch rollers 8a of each circumferential speed detector 8 ₁ , 8 ₂
It is also possible to use it as a shaper for each electrode roll 2 ₁ and 2 ₂ .

Next, the robot 5 is moved at a speed constant to the circumferential speed of the upper electrode roll 2 ₁ so that the welded part of the workpiece W is connected to both electrode rolls 2 ₁ ,
The test results will be described when the upper electrode roll 2 ₁ is operated in synchronization with the rotation of the upper electrode roll 2 ₁ so that the upper electrode roll 2 1 is fed between 2 1 and 2 2 .

In the test, the width of the electrode rolls 2 ₁ and 2 ₂ was 4 mm, the pressing force was 300 kg, the welding current passed between the electrode rolls 2 ₁ and 2 ₂ was 8500 A, and the circumferential speed of the upper electrode roll 2 ₁ was 2 m/min. The welding part of the workpiece and the upper electrode roll 2 were changed while changing the circumferential speed of the lower electrode roll 2 ₂ as appropriate.
This was done by measuring the slip ratio with respect to _{No. 1} .

As a result, when the circumferential speed of the upper electrode roll 2 ₁ is V ₁ and the circumferential speed of the lower electrode roll 2 ₂ is V ₂ , the peripheral speed difference ratio expressed as V ₂ −V ₁ /V ₁ and the upper electrode roll 2 The circumference of ₁ is L ₁ , and the feed length of the welded part per revolution is L ₂
, the relationship with the slip rate expressed as L ₁ −L ₂ /L ₁ is as shown in Figure 4.

As is clear from the figure, when V ₁ is 2 m/min, when V ₂ is made faster than V ₁ so that the circumferential speed difference ratio is about 25%, and when V ₁ is 3 m/min teeth,
When the circumferential speed difference ratio is about 15%, the slip ratio is zero, that is, the welded part is fed without slipping against the upper electrode roll _{2 1 ,}
The feeding of the welding part by 2 ₂ and the operation of the robot 5 that is synchronized with the rotation of the upper electrode roll 2 ₁ match,
It can be seen that accurate seam welding is performed.

This means that even if the welded part slips with respect to the upper electrode roll 21 due to melting between both electrode rolls _{21 and 22} of the welded part, the welded part can be removed by the relatively high speed rotation of the lower electrode roll ₂₂ . This is because the decrease in feed speed is compensated for.

(Effects of the Invention) As is clear from the above description, according to the present invention, even if a slit occurs in the welded part of the workpiece to one electrode roll for synchronizing the automatic machine, the other electrode roll whose circumferential speed is increased This compensates for the decrease in the feed speed of the welding part, and synchronizes the workpiece feed operation by the automatic machine with the actual feed of the workpiece by the electrode roll, resulting in accurate seam welding along the required welding trajectory. has.

[Brief explanation of the drawing]

Fig. 1 is a side view of an example of a seam welding machine equipped with the device of the present invention, Fig. 2 is a front view thereof, Fig. 3 is a side view of the seam welding machine during welding work, and Fig. 4 is a circumferential speed difference. There is a diagram showing the relationship between the rate and the slip rate. DESCRIPTION OF SYMBOLS 1... Seam welding machine, 2 ₁ , 2 ₂ ... Electrode roll, 6 ₁ , 6 ₂ ... Drive motor.

Claims (1)

[Claims] 1. In an automatic seam welding device in which a welding part of a workpiece is automatically fed by an automatic machine that holds the workpiece between a pair of electrode rolls provided in the seam welding machine, each of the pair of electrode rolls is driven separately. The workpiece is rotated by a motor, and the work is fed by the automatic machine in synchronization with the rotation of one electrode roll, so that the circumferential speed of the other electrode roll is faster than the circumferential speed of the one electrode roll. A method for driving an electrode roll in an automatic seam welding device, which is characterized by rotating an electrode roll in such a manner as to rotate the electrode roll in an automatic seam welding device.