JP3516836B2 - Electrode wheel height measuring device for seam welding machine - Google Patents

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 device in a seam welding machine for continuously seam welding a peripheral edge 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 for an automobile is manufactured by stacking peripheral portions of a pair of metal shells and seam welding them. Since this type of fuel tank is required to have high anticorrosion properties, the surfaces of the pair of metal shells are plated with an anticorrosive material such as tin-lead alloy, and the peripheral portions of the pair of metal shells are for example 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 multi-joint structure robot arm 12 extending three-dimensionally from a robot body 11, a handling jig 13 attached to the tip of the robot arm 12, and the like. A work 3 having a pair of fuel tank metal shells stacked on a handling jig 13 is detachably supported.

The seam welder 2 has a pair of upper and lower electrode wheels 4, 5 on the front surface of a fixed welder body 14, and each electrode wheel 4,
5 has shaping rollers 6 and 7 and shaping tools 8 and 9. The electrode wheels 4 and 5 are installed in the main body 14 of the welding machine so as to be vertically movable and rotatable in a vertically vertical posture. 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 and 9 attached to the electrode wheels 4 and 5 are used as needed to remove a plating layer described later attached to the outer peripheral surfaces of the corresponding electrode wheels 4 and 5.

The seam welder 2 holds the peripheral portion 3'of the work 3 from above and below at the uppermost point (hereinafter referred to as the apex) of the outer circumference of the lower electrode wheel 4 and the lowest point of the outer circumference of the upper electrode wheel 5. , Seam welding as follows. As shown in FIG. 4, the height H of the apex P of the lower electrode wheel 4 is kept constant, and the peripheral edge portion 3 ′ of the work 3 supported by the robot 1 is positioned between the upper and lower electrode wheels 4 and 5. , The upper electrode wheel 5 is lowered and the work peripheral portion 3 ′ is pressed against the apex P of the lower electrode wheel 4. In this state, the work 3 is automatically swung by the robot 1 so that the peripheral edge portion 3'passes between the electrode wheels 4 and 5, and the electrode wheels 4 and 5 are driven to rotate by this turning. When a welding current is passed between the electrode wheels 4 and 5 at the same time, a nugget is produced in which the joint surface of the pair of metal shells of the work peripheral portion 3'is welded by resistance heat due to the welding current, and the work peripheral portion 3'is continuous. Seal welded.

When the seal welding of the work 3 is completed, as shown in FIG.
As shown in FIG. 3, only the upper electrode wheel 5 rises and moves away from the work 3, and then the robot 1 moves the work 3 to the seam welding machine 2
Then, another workpiece is carried into the seam welder 2 and the above welding operation is repeated.

As described above, a plated layer of 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 work peripheral portion 3 ′ is seam-welded by the electrode wheels 4 and 5 of the seam welding machine 2, the plating layer of the work 3 adheres to the outer periphery of the electrode wheels 4 and 5 due to the heat generated during welding. The plating layer adhered to the outer circumferences of the electrode wheels 4 and 5 accumulates every time the number of welding increases, and if the plating layer is left standing and the seam welding is continued, the electric resistance of the adhered plating layer causes a welding defect such as a crack. It tends to occur.

Therefore, in order to prevent the deterioration of the welding quality of the work peripheral portion 3 ', shaping tools 8 and 9 are applied from the fixed direction to the outer circumferences of the rotating electrode wheels 4 and 5, and the tips of the shaping tools 8 and 9 are applied. The outer peripheral surfaces of the electrode wheels 4 and 5 are ground to remove the plating layer attached to the outer peripheral surfaces. In many cases, such removal of the plating layer is constantly performed while 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 wheels 4 and 5 change color when a plating layer is attached,
The worker observes this discoloration. When the worker determines that the outer peripheral surfaces of the electrode wheels 4 and 5 have been discolored by the plating layer more than the allowable amount by the seam welding of several times, the worker removes the plating layer with the shaping tools 8 and 9, and then, In preparation for seam welding, the lower electrode wheel 4 is manually raised by a desired amount.

That is, when the outer peripheral surfaces of the electrode wheels 4 and 5 are ground by the shaping tools 8 and 9 to remove the plating layer, the outer peripheral surfaces of the electrode wheels 4 and 5 are polished to reduce the diameter of each electrode wheel. Therefore, the height of the apex P of the lower electrode wheel 4 becomes lower than the reference height H during seam welding. For example, as shown in the lower electrode wheel 4 before grinding in FIG. 6A and the lower electrode wheel 4 after grinding in FIG. 6B, when the outer peripheral surface is ground by the thickness α to remove the plating layer. , The height H'of the apex P of the lower electrode wheel 4 after grinding is higher than the welding reference height H of the apex P of the lower electrode wheel 4 before grinding.
Is lower by α. When 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. 7B, the lower electrode wheel 4 having the lowered height H ′ has a work peripheral portion 3 ′. When is pressed by the upper electrode wheel 5, the work peripheral portion 3 ′ may be excessively lowered by α from a predetermined height and tilted, and good seam welding may not be performed. The upper limit of α value that causes such seam welding failure is several meters.
If m is less than m, for example, α exceeds a permissible value of 1.5 mm, seam welding failure is likely to occur. In addition, in FIG.
Shows a state of seam welding by the lower electrode wheel 4 when is less than or equal to the allowable value. At this time, good seam welding is performed with almost no inclination of the work peripheral portion 3 ′.

Therefore, the worker removes the plating layer of each electrode wheel 4 and 5, and then measures the outer diameter of the outer peripheral surface of the lower electrode wheel 4 with a gauge to determine 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 apex P of the lower electrode wheel 4 is corrected to a normal allowable range.
The next work is seam welded.

[0012]

By the way, a worker manually measures the changing electrode wheel diameter of the lower electrode wheel of the seam welding machine as described above and corrects the height of the lower electrode wheel based on the measured value. The work relying on is not efficient, and seam welding becomes impossible during the measurement of the diameter of the electrode wheel, and this time zone becomes a loss time, which deteriorates the operating rate of the seam welding equipment. Further, in the case of the height control system of the lower electrode wheel by the worker, the manually corrected height of the lower electrode wheel will show variations due to individual differences of the workers, and this variation will be the same as that of the seam welding quality of the work. The following problems may occur.

As a solution to the above problem, a first displacement sensor that measures the amount of change in the diameter of the electrode ring of the lower electrode wheel and a second displacement sensor that measures the amount of change in the height of the lower electrode wheel are used. It is conceivable that the height of the lower electrode wheel at the present time is measured based on the sum of the measured amounts of the first and second displacement sensors, and the height is automatically corrected. 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, it requires two measurement operation systems with two displacement sensors,
Further, since a highly accurate displacement sensor on the market is expensive and two of them are used, there is a problem that the capital investment cost of the entire measuring device is high.

An object of the present invention is to operatively perform measurement for correction of the height of the lower electrode wheel of the seam welding machine as described above.
In addition, the object is to provide an electrode wheel height measuring device which can be advantageously made in terms of equipment investment.

[0015]

According to the present invention, the peripheral edge of a work is held from above and below by a pair of vertically 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 adjusted. As a reference, a height measuring device for the lower electrode wheel in a seam welding machine that seam-welds the peripheral edge of the work.It is an elevator that supports the lower electrode wheel and moves up and down. A movable rack gear, a displacement sensor that is fixed to the movable rack gear and measures a change in the diameter of the electrode wheel at the lower outer periphery of the lower electrode wheel, and a fixed rack gear that faces the movable rack gear in parallel and is fixed in a fixed position. Equipped with a pinion gear that is rotatably connected to a fixed position of the lifting body and meshes with both fixed rack gear and movable rack gear, and moves up and down based on the measured value of the electrode wheel diameter of the lower electrode wheel by the 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 lifting body by a displacement that is twice the vertical displacement of the lifting body. By moving it, the above object is achieved.

Further, in the present invention, the lifting body is
In order to automate the height measurement and correction of the electrode wheel, it is desirable to attach a lifting source that moves the lifting body up and down by the amount of change in the diameter of the electrode wheel of the lower electrode wheel, which is obtained from the measurement value of the displacement sensor.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION 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. 1 and 2.

The electrode wheel height measuring device shown in FIG. 1 is built in the seam welding machine 2, and is installed in the lifting body 21 for supporting the lower electrode wheel 4 and moving it up and down, and in the lifting body 21. One contact-type displacement sensor 22, a lifting / lowering body 21 and a rack / pinion mechanism 23 installed in the vicinity thereof, and a lifting source for directly moving the lifting / lowering body 21 up and down, for example, a jack 2
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 rack gears.

The upper electrode wheel 4 is rotatably supported on the upper and lower parts of the elevating body 21, and a movable rack gear 24 which is long in the vertical direction is held and installed on a guide unit 28 on the lower side surface of the elevating body 21. The displacement sensor 22 is fixed to the upper end of the movable rack gear 24, and the displacement sensor 22 constantly contacts the lowest point on the outer circumference of the lower electrode wheel 4 to measure the change in the electrode wheel diameter of the lower electrode wheel 4 step by step. The fixed rack gear 25 is fixed to a place different from the lifting body 21, and the movable rack gear 24 is fixed.
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 both rack gears 24, 25. Pinion gear 26
Is rotatably installed at a fixed position on the side surface of the lifting 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 variation of the electrode wheel diameter is reduced. The displacement sensor 22 measures. For example, the apex 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 this lower electrode wheel 4 is shown in FIG.
Assuming that the radial dimension from the chain line in (A) to the solid line is reduced by α, the displacement sensor 22 measures the numerical value of α. At this point, the apex P of the outer periphery of the lower electrode wheel 4 is at a height that is lower than the reference height H by α.

When the lifting body 21 is raised by the jack 27 by α based on the measured value of the displacement sensor 22, the apex P of the outer periphery of the lower electrode wheel 4 is at the reference height as shown in FIG. 2B. At the same time, the displacement sensor 22 ascends with a displacement amount of twice α, and the relative distance to the outer periphery of the lower electrode wheel 4 becomes the same as the distance before the electrode ascends in FIG. That is, when the lifting 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
When 6 rotates upward, the movable rack gear 24 meshing 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, and as a result, the movable rack gear 24 and the displacement sensor 22 supported by the movable rack gear 24 are 2α.
Only rises.

The above measured value α of the displacement sensor 22 is a preset allowable value of seam welding quality, for example, 1.5 m.
When m is exceeded, the upper electrode wheel 4 is raised by the jack 27 by an amount corresponding to α 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, seam welding may be continued without raising the lower electrode wheel 4.

Further, since the relative distance between the outer circumference of the lower electrode wheel 4 and the displacement sensor 22 is kept substantially constant, the height measurement of the lower electrode wheel 4 is always performed with high accuracy and the displacement sensor 22 used. There is also an economic advantage that only one is required. Further, since the displacement sensor 22 is installed under 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 seam welding and the electrode wheel height correction by measuring the electrode wheel height can be carried out simultaneously.

The jack 2 for moving the lifting body 21 up and down.
7 can be a manual type, but an automatic jack or other automatic lifting source can be used for the displacement sensor 2
If the automatic control is performed based on the measurement value of 2, it becomes easy to automatically measure and correct the height of the electrode wheel and to fully automate the seam welding equipment.

[0025]

According to the present invention, the height of the lower electrode wheel of the seam welder can be measured and the height can be corrected by using one displacement sensor. A device can be provided, and automation of electrode wheel height measurement and height correction becomes easy, and this automation can improve 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 circumference of the lower electrode wheel, the seam welding operation by the upper electrode wheel can be performed simultaneously with this measurement operation. The accuracy and efficiency of the seam welder can be further improved.

[Brief description of drawings]

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

FIG. 2 is a front view of a main part of the apparatus shown in FIG. 1, where (A) is a front view before the lower electrode wheel is raised and (B) is a front view after the lower electrode wheel is raised. .

FIG. 3 is a front view showing an outline of an existing seam welding facility 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 equipment of FIG. 3;

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

FIG. 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 during defective welding.

[Explanation of symbols]

2 seam welders 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)

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23K 11/24 336 B23K 11/24 350 B23K 11/06 520

Claims (2)

(57) [Claims] 1. A peripheral edge of a work is clamped from above and below by a pair of vertically movable and vertically movable electrode wheels of a seam welding machine, and the peripheral edge of the workpiece is seam welded based on the height of the apex of the outer periphery of the lower electrode wheel. A height measuring device for a lower electrode wheel in a seam welding machine, comprising: a lifting body that supports the lower electrode wheel and moves up and down; and a movable rack gear that is installed on the lifting body so as to be vertically movable relative to each other.
A displacement sensor that is fixed to the movable rack gear and measures the change in the diameter of the electrode ring at the lower outer circumference of the lower electrode wheel, a fixed rack gear that is fixed parallel to the movable rack gear and fixed in place, and a fixed position in the lifting body. It is equipped with a pinion gear that is rotatably connected and meshes with both a fixed rack gear and a movable rack gear.When the lifting 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 displacement, and this rotation causes the movable rack gear and the displacement sensor to move up and down relatively with respect to the lifting body by a displacement amount that is twice the vertical displacement amount of the lifting body. Electrode wheel height measuring device for welding machine. 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 diameter of the electrode ring of the lower electrode wheel, which is obtained from the measurement value of the displacement sensor. Electrode wheel height measuring device for welding machine.