JPH1128577A - Electrode ring height measurement instrument of seam welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct measurement for correcting a height of a lower electrode ring advantageously in workability and equipment investment. SOLUTION: A movable rack gear 24 is mounted, as relatively movable in the up/down direction, on an elevation body 21, which supports a lower electrode ring 4 and moves up/down, and a pinion gear 26 is attached to a fixed position of the elevation body 21, the pinion gear 26 is engaged to a fixing gear 25 fixed to an outside and the movable rack gear 24, a change in an electrode ring diameter at an outer peripheral lower part of the lower electrode ring 4 is measured by a displacement sensor 22 fixed to the movable rack gear 24, based on this measured value, when the elevation body 21 is elevated, the displacement sensor 22 is elevated by two times of the displacement quantity, a relative distance to the lower electrode ring 4 is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode wheel height measuring apparatus in a seam welding machine for continuously seam welding a peripheral portion of a work such as a fuel tank of an automobile using a pair of electrode wheels.

[0002]

2. Description of the Related Art A fuel tank of an automobile is manufactured by overlapping peripheral portions of a pair of metal shells and performing seam welding. Since this kind of fuel tank is required to have high rust resistance, the surfaces of the pair of metal shells are plated with a rust-preventive material such as tin-lead alloy, and the periphery of the pair of metal shells is, for example, shown in FIG. Seam welding is performed using a robot 1 and a seam welding machine 2 as shown in FIG.

The robot 1 has a fixed robot body 1
1. An industrial robot including a robot arm 12 having a multi-joint structure extending three-dimensionally from a robot body 11, a handling jig 13 attached to a tip of the robot arm 12, and the like. A work 3 having a pair of metal shells for a fuel tank stacked on a handling jig 13 is detachably supported.

The seam welding machine 2 comprises a pair of upper and lower electrode wheels 4, 5 on the front surface of a fixed welding machine body 14,
5 has shaping rollers 6 and 7 and shaping tools 8 and 9. Each of the electrode wheels 4 and 5 is installed on the welding machine main body 14 in a vertically vertical position and rotatable and rotatable. The shaping rollers 6 and 7 attached to the electrode wheels 4 and 5 rotate at a constant speed to shape the outer peripheral surfaces of the corresponding electrode wheels 4 and 5 into a predetermined arc shape to secure the welding quality of the work 3. . The shaping tools 8, 9 attached to each of the electrode wheels 4, 5 are used as needed to remove a plating layer, which will be described later, attached to the outer peripheral surface of the corresponding electrode wheel 4, 5.

[0005] The seam welding machine 2 clamps the peripheral portion 3 ′ of the work 3 from above and below at the uppermost point (hereinafter referred to as a vertex) of the outer periphery of the lower electrode wheel 4 and the lowermost point of the outer periphery of the upper electrode wheel 5. Then, seam welding is performed in the following manner. As shown in FIG. 4, the height H of the apex P of the lower electrode wheel 4 is kept constant, and the peripheral portion 3 ′ of the work 3 supported by the robot 1 is positioned between the upper and lower electrode wheels 4, 5. Then, the upper electrode wheel 5 is lowered, and the work peripheral portion 3 ′ is pressed against the vertex P of the lower electrode wheel 4. In this state, the work 3 is automatically rotated by the robot 1 so that the peripheral portion 3 ′ passes between the electrode wheels 4 and 5, and the electrode wheels 4 and 5 are rotated following the rotation. Simultaneously, when a welding current is applied between the electrode wheels 4 and 5, a nugget in which the joining surfaces of the pair of metal shells of the work peripheral portion 3 'are welded by resistance heat due to the welding current is generated, and the work peripheral portion 3' is continuously formed. The seal is welded.

When the seal welding of the work 3 is completed, FIG.
Only the upper electrode wheel 5 rises and separates from the work 3 as shown in FIG.
, And another next work is carried into the seam welding machine 2, and the above-described welding operation is repeatedly performed.

[0007] As described above, a plating layer of a tin-lead alloy or the like is formed on the entire surface of the work 3 to be seam-welded to prevent rust. Therefore, when the workpiece periphery 3 ′ is seam-welded with the electrode wheels 4 and 5 of the seam welding machine 2, the plating layer of the workpiece 3 adheres to the outer circumference of the electrode wheels 4 and 5 due to heat generated during welding. The plating layer adhering to the outer circumferences of the electrode rings 4 and 5 accumulates as the number of welding increases, and if this is left unattended and seam welding is continued, welding defects such as cracks and the like due to the electric resistance of the adhered plating layer will occur. It is easy to occur.

Therefore, in order to prevent deterioration of the welding quality of the peripheral portion 3 'of the work, shaping tools 8, 9 are applied to the outer circumferences of the rotating electrode wheels 4, 5 from a fixed direction, and the leading ends of the shaping tools 8, 9 are applied. The outer peripheral surfaces of the electrode wheels 4 and 5 are ground to remove a plating layer attached to the outer peripheral surfaces. Such removal of the plating layer is often performed constantly while performing seam welding.

The removal of the plating layer is performed by an operator as follows. When seam welding of the work 3 is performed by the robot 1 and the seam welding machine 2, an operator visually observes the outer peripheral surfaces of the pair of electrode wheels 4 and 5. The outer peripheral surfaces of the electrode rings 4 and 5 change color when the plating layer adheres,
An operator observes this discoloration. When the worker determines that the outer peripheral surfaces of the electrode wheels 4 and 5 have been discolored by a plating layer exceeding the allowable amount in several times of seam welding, the worker removes the plating layer using shaping tools 8 and 9 and then performs the next step. The lower electrode wheel 4 is manually raised by a desired amount in preparation for the seam welding.

That is, when the outer peripheral surface of each of the electrode wheels 4 and 5 is ground by the shaping tools 8 and 9 to remove the plating layer, the outer peripheral surface of each of the electrode wheels 4 and 5 is polished to reduce the diameter of each electrode wheel. Thus, the height of the apex P of the lower electrode wheel 4 becomes lower than the reference height H at the time of seam welding. For example, as shown in the lower electrode wheel 4 before grinding in FIG. 6 (A) and the lower electrode wheel 4 after grinding in FIG. 6 (B), when the outer peripheral surface is ground by the thickness α to remove the plating layer. The height H ′ of the vertex P of the lower electrode wheel 4 after grinding is higher than the welding reference height H of the vertex P of the lower electrode wheel 4 before grinding.
Becomes lower by α. When the seam welding is continued with the lower electrode wheel 4 having the height H ′ of the apex P lowered as it is, as shown in FIG. When the upper electrode wheel 5 is pressed, the workpiece peripheral edge 3 ′ is excessively lowered by α from the predetermined height and tilts, and good seam welding may not be performed. The upper limit of the α value that causes such seam welding failure is several meters.
If m is less than m, for example, if α exceeds the allowable value of 1.5 mm, seam welding failure is likely to occur. Note that FIG.
Shows the state of seam welding by the lower electrode wheel 4 when the value is less than or equal to the allowable value. At this time, a good seam welding is performed with the work peripheral portion 3 'hardly inclined.

Therefore, the worker removes the plating layer from each of the electrode wheels 4 and 5 and then measures the outer diameter of the outer peripheral surface of the lower electrode wheel 4 with a gauge, and determines that the measured value α exceeds the allowable value. Then, for example, the jack 15 shown in FIG. 5 is manually operated to raise the lower electrode wheel 4 by an amount corresponding to α, and the height of the vertex P of the lower electrode wheel 4 is corrected to a normal allowable range.
Seam welding of the next work is performed.

[0012]

By the way, the measurement of the changing electrode wheel diameter of the lower electrode wheel of the seam welding machine as described above and the correction of the height of the lower electrode wheel based on the measured value are manually performed by an operator. , The work efficiency is poor, and the seam welding is not possible during the measurement of the electrode wheel diameter, and this time zone is a loss time, which deteriorates the operation rate of the seam welding equipment. Furthermore, in the case of the lower electrode wheel height management system by the operator, the difference in the manually corrected height of the lower electrode wheel due to the individual difference of the worker appears, and this variation directly changes the seam welding quality of the work. May occur.

As a solution to the above problem, each of a first displacement sensor for measuring an amount of change in the electrode wheel diameter of the lower electrode wheel and a second displacement sensor for measuring the amount of change in the height of the lower electrode wheel is provided. It is conceivable to measure the height of the lower electrode wheel at the present time based on the sum of the measured amounts of the first and second displacement sensors and to automatically correct the height. In this case, a commercially available high precision sensor can be used for each displacement sensor, and the height of the lower electrode wheel can be corrected with high precision. However, two measurement operation systems with two displacement sensors are required,
In addition, a commercially available high-precision displacement sensor is expensive and uses two of them, which causes a problem that the capital investment cost of the entire measuring device is high.

An object of the present invention is to measure the height of the lower electrode wheel of a seam welding machine as described above in a practical manner.
Another object of the present invention is to provide an electrode wheel height measuring device that can be advantageously used in terms of capital investment.

[0015]

According to the present invention, a peripheral portion of a work is sandwiched from above and below by a pair of upper and lower rotatable and vertically movable electrode wheels of a seam welding machine, and the height of the apex of the outer periphery of the lower electrode wheel is increased. A height measuring device for the lower electrode wheel in a seam welding machine that seams the periphery of the workpiece as a reference, and is installed on the elevating body that supports the lower electrode wheel and moves up and down, and is relatively movable vertically in the elevating body A movable rack gear, a displacement sensor fixed to the movable rack gear and measuring a change in the diameter of the electrode wheel at the lower part of the outer periphery of the lower electrode wheel, and a fixed rack gear fixed in a fixed position facing the movable rack gear in parallel. A pinion gear rotatably connected to a fixed position of the elevating body and meshing with both the fixed rack gear and the movable rack gear, and moves up and down based on the measured value of the electrode wheel diameter of the lower electrode wheel by a displacement sensor. The pinion gear is rotated by the fixed rack gear by the displacement when the lower electrode wheel is moved up and down, and this rotation causes the movable rack gear and the displacement sensor to move up and down relative to the up and down body with a displacement amount twice as large as the up and down displacement amount of the up and down body. The above object is achieved by moving.

Further, in the present invention, the elevating body includes:
It is desirable to provide an elevating source for vertically moving the elevating body by an amount of change in the electrode wheel diameter of the lower electrode wheel obtained from the measured value of the displacement sensor in order to automate the measurement and correction of the electrode wheel height.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a height measuring device for a lower electrode wheel 4 of a seam welding machine 2 shown in FIG. 3 will be described below with reference to FIGS.

The electrode wheel height measuring device shown in FIG. 1 is built in the seam welding machine 2, and is installed on the elevating body 21 which supports the lower electrode wheel 4 to move up and down and the elevating body 21. One contact-type displacement sensor 22, an elevating body 21, a rack and pinion mechanism 23 installed near the elevating body 21, and a jack, such as a jack 2, for directly moving the elevating body 21 up and down
7 is provided. The rack and pinion mechanism 23 includes a pair of movable rack gears 24, a fixed rack gear 25, and a pinion gear 26 installed between the two rack gears.

The upper electrode wheel 4 is rotatably supported above the elevating body 21, and a vertically long movable rack gear 24 is installed on the lower side surface of the elevating body 21 while being held by the guide unit 28. A displacement sensor 22 is fixed to the upper end of the movable rack gear 24, and the displacement sensor 22 constantly contacts the lowermost point of the outer periphery of the lower electrode wheel 4 and measures a change in the electrode wheel diameter of the lower electrode wheel 4 one by one. The fixed rack gear 25 is fixed to a place different from the elevating body 21 and the movable rack gear 24
And at regular intervals. A pinion gear 26 is inserted between the fixed rack gear 25 and the movable rack gear 24 so as to mesh with the rack gears 24, 25. Pinion gear 26
Is rotatably installed at a fixed position on the side surface of the elevating body 21.

When the seam welding machine 2 is operated in the manner shown in FIG. 4 to perform seam welding of the work, and the plating layer on the outer periphery of the lower electrode wheel 4 is removed to reduce the electrode wheel diameter, the amount of change in the electrode wheel diameter is reduced. The displacement sensor 22 measures. For example, the vertex P of the outer circumference of the lower electrode wheel 4 in FIG. 1 is located at the position of the reference height H for seam welding, and the electrode wheel diameter of the lower electrode wheel 4 is as shown in FIG.
Assuming that the radius is reduced by α in the radius from the chain line to the solid line in (A), the displacement sensor 22 measures the numerical value of α. At this point, the vertex P of the outer periphery of the lower electrode wheel 4 is at a height lower than the reference height H by α.

Here, when the lifting body 21 is raised by α using the jack 27 based on the measurement value of the displacement sensor 22, the apex P of the outer circumference of the lower electrode wheel 4 becomes the reference height as shown in FIG. H, and at the same time, the displacement sensor 22 rises with a displacement amount twice as large as α, and the relative distance to the outer periphery of the lower electrode wheel 4 becomes the same as the distance before the electrode rise in FIG. That is, when the elevating body 21 is raised by an arbitrary amount α, the pinion gear 2
6 also rises while being rotated by the fixed rack gear 25 along the fixed rack gear 25 by the same amount. Pinion gear 2
6, the movable rack gear 24 meshed with the pinion gear 26 is pushed up by the pinion gear 26 and relatively rises by α with respect to the elevating body 21. As a result, the movable rack gear 24 and the displacement sensor 22 supported by the movable rack gear 24 become 2α.
Just rise.

The measured value α of the displacement sensor 22 is a predetermined allowable value of the quality of seam welding, for example, 1.5 m
If m is exceeded, the upper electrode wheel 4 is raised by an amount corresponding to α by the jack 27 in the above manner, and good seam welding is continuously performed. If the measured value α of the displacement sensor 22 does not exceed the allowable value, the seam welding may be continued without raising the lower electrode wheel 4.

Since the relative distance between the outer periphery of the lower electrode wheel 4 and the displacement sensor 22 is maintained substantially constant, the height measurement of the lower electrode wheel 4 is always executed with high accuracy, and the displacement sensor 22 used is always used. However, there is also an economic advantage that only one is required. Further, since the displacement sensor 22 is installed at the lower part of the outer circumference of the lower electrode wheel 4 to measure the change in the diameter of the electrode wheel, the upper outer circumference of the lower electrode wheel 4 is used for seam welding when measuring the height of the electrode wheel. Therefore, the electrode wheel height correction by the seam welding and the electrode wheel height measurement can be performed simultaneously.

A jack 2 for vertically moving the elevating body 21
7 can be a manual one, but it is possible to use an automatic jack or other automatic lifting source to
If the automatic control is performed based on the measurement value of 2, the automatic measurement and correction of the electrode wheel height and the full automation of the seam welding equipment can be easily performed.

[0025]

According to the present invention, the height measurement and the height correction of the lower electrode wheel of the seam welding machine can be performed by using one displacement sensor. An apparatus can be provided, and the automation of electrode wheel height measurement and height correction becomes easy, and this automation can increase the accuracy and efficiency of the seam welding machine. Furthermore, since the height of the electrode wheel is measured by the displacement sensor at the lower part of the outer periphery of the lower electrode wheel, the seam welding operation by the upper electrode wheel can be performed simultaneously with this measurement operation. Seam welding machines can be made even more precise and efficient.

[Brief description of the drawings]

FIG. 1 is a front view of an electrode wheel height measuring device and a lower electrode wheel according to an embodiment of the present invention.

FIGS. 2A and 2B are front views of a main part of the apparatus in FIG. 1, wherein FIG. 2A is a front view before lower electrode wheels are raised, and FIG. .

FIG. 3 is a front view showing an outline of existing seam welding equipment using a robot and a seam welder.

FIG. 4 is a front view of a pair of electrode wheels during a seam welding operation of the seam welding machine in the facility of FIG. 3;

5 is a front view of a pair of electrode wheels after seam welding of the seam welding machine in the facility in FIG. 3;

6 is a front view of the lower electrode wheel in FIG. 5 before and after grinding.

FIG. 7 is a side view of the pair of electrode wheels of FIG. 4 during normal welding and at the time of poor welding.

[Explanation of symbols]

 2 Seam welding machine 3 Work 4 Lower electrode wheel 5 Upper electrode wheel 21 Lifting body 22 Displacement sensor 24 Movable rack gear 25 Fixed rack gear 26 Pinion gear 27 Lifting source (jack)

Claims (2)

[Claims] 1. A peripheral portion of a work is sandwiched from above and below by a pair of upper and lower rotatable and vertically movable electrode wheels of a seam welding machine, and the peripheral portion of the work is seam-welded based on a height of an apex of an outer periphery of a lower electrode wheel. A height measuring device for a lower electrode wheel in a seam welding machine, comprising: an elevating body that moves up and down while supporting the lower electrode wheel; and a movable rack gear that is installed on the elevating body so as to be relatively movable up and down,
A displacement sensor fixed to the movable rack gear and measuring the change in the diameter of the electrode wheel at the lower part of the outer periphery of the lower electrode wheel; a fixed rack gear fixed in a fixed position facing the movable rack gear in parallel with the movable rack gear; A pinion gear rotatably connected to mesh with both the fixed rack gear and the movable rack gear, and when the elevating body and the lower electrode wheel are moved up and down based on the measured value of the electrode wheel diameter of the lower electrode wheel by the displacement sensor. A seam characterized in that the pinion gear is rotated by a fixed rack gear by the displacement, and the rotation causes the movable rack gear and the displacement sensor to move up and down relative to the elevating body by a displacement amount twice as large as the up and down displacement amount of the elevating body. Electrode wheel height measuring device for welding machines. 2. The seam according to claim 1, wherein the lifting body is provided with a lifting source for moving the lifting body up and down by an amount of change in the electrode wheel diameter of the lower electrode wheel determined by a measurement value of a displacement sensor. Electrode wheel height measuring device for welding machines.