JPH05305452A - Tip sticking detector for spot welding gun - Google Patents

Abstract

PURPOSE:To speedily detect an electrode tip sticking to material to be welded by detecting a conductive state between a power source for the welding gun and the material to be welded in a state with the electrode tip separated slightly from the material to be welded. CONSTITUTION:The material 10 to be welded is welded by the spot welding gun 2. After welding, the electrode tip of welding gas 2 is opened slightly, at the same time, an electrode 14 for checking is pressed against a supporting base 12 and connected thereto and a current value between an electrode 13 for the gun and the electrode 14 for checking is measured. When the current value exceeds a specified current value, it is judged that the electrode tip is deposited on a weld zone and operation of the welding gun 2 is stopped to inform of the occurrence of failure. It can be detected speedily and surely that the electrode tip is stuck to the weld zone and breakdown of the electrode tip and damage of the material to be welded can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding gun tip sticking detection device for detecting sticking of an electrode tip press-fitted to the tip of a welding arm of a spot welding gun.

[0002]

2. Description of the Related Art Conventionally, spot welding used when welding a vehicle body of an automobile is a vehicle body (workpiece to be welded) made of metal (or alloy) by a pair of electrode tips press-fitted to the tip of a welding arm of a spot welding gun. ) Is sandwiched, and the current is applied to the weld using these electrodes to pressurize the weld and heat and melt the metal (or alloy) of the weld by Joule heat generated in the weld. The welding portion is welded in spots. The electrode tip is usually
Since a material having good electrical conductivity and thermal conductivity, such as a copper alloy, is used and forcedly cooled by using cooling water during welding work, the temperature rise in normal working conditions is not so high. In this spot welding, if welding conditions such as welding current, energization time, and pressure are appropriately controlled, the generation of Joule heat is maximized at the welded portion of the vehicle body having the highest contact resistance, and welding proceeds normally.

[0003]

However, in the above spot welding, for example, the contact between the electrode tip and the vehicle body becomes insufficient due to wear of the electrode tip or the like, and the contact resistance between the electrode tip and the vehicle body increases. There is a problem that the electrode chip and the vehicle body are welded to each other due to the temperature rise due to heat generation of the electrode chip. If the electrode tip and the vehicle body are welded, the electrode tip may be broken or the vehicle body may be damaged when the electrode tip is removed from the vehicle body, and it takes time to repair the electrode tip. Therefore, the defective rate of the vehicle body increases, the operating rate of the manufacturing line decreases, and the manufacturing cost increases.

The present invention has been made in view of the above circumstances, and provides a tip sticking detection device for a spot welding gun for detecting sticking of an electrode tip pressed into the tip of a welding arm of the spot welding gun. To provide.

[0005]

In order to solve the above-mentioned problems, the present invention employs the following chip sticking detection device for spot welding guns. That is, a tip sticking detection device for a spot welding gun, which detects sticking of an electrode tip press-fitted to the tip of a welding arm that holds an object to be welded,
A support table on which the object to be welded is placed and made of a conductive material, and a gun electrode connected to the spot welding gun,
A checking electrode connected to the support base, a current measuring device provided in the middle of a distribution line for applying a voltage between the gun electrode and the checking electrode, and the electrode tip by the current measuring device. And a means for stopping the operation of the spot welding gun at the same time as detecting a conduction state between the gun electrode and the check electrode in a state slightly separated from the object to be welded. I am trying.

[0006]

In the spot welding gun tip sticking detection device of the present invention, when the electrode tip is slightly separated from the object to be welded by the current measuring machine, the conduction state between the gun electrode and the check electrode is maintained. By the detection, it becomes possible to detect the sticking of the electrode tip quickly and surely, and the troubles such as breakage of the electrode tip and breakage of the vehicle body are eliminated.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side view showing a tip sticking detection device (hereinafter, simply referred to as a detection device) 1 for a spot welding gun, and FIG. 2 is a welding arm 3, 4 of a spot welding gun 2.
It is a side view which shows the tip part of.

This detection device 1 is provided with a vehicle body (object to be welded) 10
Supports 11 and 1 on which the table is placed and which is made of a conductive material such as metal
1, a gun electrode 13 connected to the spot welding gun 2 provided on the upper part of the scale 12, a check electrode 14 connected to the support 12, and a gap between the gun electrode 13 and the check electrode 14. Distribution line 15 for applying voltage to the
Current measuring machine 16 provided in the middle of the
Detects the conduction state between the gun electrode 13 and the check electrode 14 while the electrode tips 17 and 18 are slightly separated from the vehicle body 10 by the spot welding gun 2
And a control device (operation stopping means) 19 for stopping the operation of the above.

The support bases 12 and 12 are mounted on a carriage 22 through an insulating plate 21 which can move in a direction perpendicular to the plane of FIG. Further, the ikele 12 is installed so as to be close to and away from the trolley 22, and this operation is controlled by a limit switch 23 provided on the bottom. Further, the control device 19 has a built-in relay 24 as shown in FIG.

Next, the operation of the detection device 1 will be described with reference to FIG. First, the welding arms 3 and 4 are rotated to clamp the vehicle body 10 by the electrode tips 17 and 18, and a current is supplied to the welded portion 10a using these electrode tips 17 and 18 by a welding power source (not shown). While this welding part 10a
Is pressurized (step 1). The metal (or alloy) of the weld 10a due to the Joule heat generated in the weld 10a
Is melted by heating and the welded portion 10a is welded in a spot shape (s
step2).

Next, the welding arms 3 and 4 are slightly opened to separate the electrode tips 17 and 18 from the welding portion 10a of the vehicle body 10, and at the same time, the check electrode 14 is pressed and connected to the support base 12, and the gun electrode 13 is connected. A voltage is applied between the check electrode 14 and the check electrode 14 (step 3). Next, current measuring machine 1
6, the current value I between the gun electrode 13 and the check electrode 14 is measured. Here, if the current value I is less than or equal to the predetermined current value I ₀ , the electrode tips 17 and 18 are not welded to each other.
If the current value I exceeds a predetermined current value I ₀ , it is determined that the electrode tip 1 has not been welded
7 and 18 are welded to the welded part 10a (there is a defect)
Is determined (step 4).

When it is determined that there is no problem in the above, the welding arms 3 and 4 are further opened and the electrode tip 1 is opened.
7 and 18 are completely separated from the welded portion 10a of the vehicle body 10, and at the same time, the check electrode 14 pressed by the support base 12 is moved to the side of the scale 12 and separated from the support base 12,
Is sent to the next step, and at the same time, the new vehicle body 10 is moved to a predetermined position and the welding step is repeated again. Also, "There is a problem"
If it is determined that the spot welding gun 2 is stopped, an emergency light, a buzzer, or the like is notified (step 5).

As described above, according to the detection device 1 of this embodiment, the support bases 11, 11 on which the vehicle body 10 is mounted are mounted.
And a gun electrode 13 connected to the spot welding gun 2.
And a current measuring device 1 provided in the middle of a check electrode 14 connected to the support 12 and a distribution line 15 for applying a voltage between the gun electrode 13 and the check electrode 14.
6 and the current measuring device 16 detects the conduction state between the gun electrode 13 and the check electrode 14 while the electrode tips 17 and 18 are slightly separated from the vehicle body 10, and at the same time, the operation of the spot welding gun 2 is stopped. Since it is provided with a control device (operation stopping means) 19 for
It is possible to detect the sticking of the vehicle body 10 to the welded portion 10a promptly and surely, and it is possible to prevent problems such as damage to the electrode tip or damage to the vehicle body. Therefore, the defective rate of the vehicle body can be reduced, the operating rate of the manufacturing line can be improved, and the manufacturing cost can be reduced.

[0014]

As described above, according to the tip sticking detection device of the spot welding gun of the present invention, spot welding for detecting sticking of the electrode tip press-fitted to the tip of the welding arm that holds the object to be welded. A tip attachment detection device for a gun, comprising: a support table on which the object to be welded is placed and made of a conductive material; a gun electrode connected to the spot welding gun; and a check table connected to the support table. An electrode, a current measuring machine provided in the middle of a distribution line for applying a voltage between the gun electrode and the checking electrode, and the electrode tip was slightly separated from the workpiece by the current measuring machine. In this state, the means for stopping the operation of the spot welding gun at the same time as detecting the conduction state between the gun electrode and the checking electrode is provided. It is possible to detect the sticking to the welding portion of the body quickly and reliably, the electrode tip body or destruction can be prevented problems such as damaged.
Therefore, the defective rate of the vehicle body can be reduced, the operating rate of the manufacturing line can be improved, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view showing a tip sticking detection device for a spot welding gun of the present invention.

FIG. 2 is a side view showing the tip of the welding arm of the spot welding gun.

FIG. 3 is a circuit diagram showing a relay of the control device.

FIG. 4 is a flow chart showing the operation of the tip sticking detection device for a spot welding gun of the present invention.

[Explanation of symbols]

 1 Spot welding gun tip sticking detection device 2 Spot welding gun 3,4 Welding arm 10 Car body (workpiece to be welded) 11 Support stand 12 Imager 13 Gun electrode 14 Check electrode 15 Distribution line 16 Current measuring device 17,18 Electrode tip 19 Control device (operation stop means) 21 Insulating plate 22 Truck 23 Limit switch 24 Relay

Claims (1)

[Claims] 1. A tip sticking detection device for a spot welding gun for detecting sticking of an electrode tip press-fitted to a tip of a welding arm for holding a work piece to be welded. A support base made of a material, a gun electrode connected to the spot welding gun, a check electrode connected to the support base, and a voltage application between the gun electrode and the check electrode. A current measuring device provided in the middle of the distribution line, and at the same time detecting the conduction state between the gun electrode and the checking electrode in a state where the electrode tip is slightly separated from the object to be welded by the current measuring device, A tip sticking detection device for a spot welding gun, comprising: an operation stopping means for stopping the operation of the spot welding gun.