JPH0740048A - Method and device for preventing malfunction of work position detection - Google Patents

Abstract

PURPOSE:To provide the method and device for preventing a malfunction of work position detection capable of improving the welding quality and working efficiency by preventing the malfunction of work position detection caused by foreign matter stuck on the work surface interposing between works and a welding wire. CONSTITUTION:An arc welding robot is provided with a compressed gas supplying duct 8 and a changeover device 9 which changes over a shielding gas supplying duct 7 and the compressed gas supplying duct 8 is provided. At the time of sensing, the compressed gas supplying duct 8 is communicated with a shielding gas duct of a welding torch 1 and compressed gas is jetted from the tip of the welding torch 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory / reproducing arc welding robot having a sensing means for detecting a work position, and a method and apparatus for preventing malfunction of the work position detection during sensing. Regarding

[0002]

2. Description of the Related Art FIG. 3 shows an example of sensing using the above-mentioned arc welding robot, which includes a work 3a and a work 3a.
It shows sensing when fillet welding b and b at point P. This sensing is a process for the arc welding robot to grasp the welding position (point P) before welding. First, as shown in FIG. 3A, a predetermined angle with respect to the horizontal plane. The welding wire 2 is projected at a predetermined length (for example, about 25 mm) from the tip of the welding torch 1 which is inclined (about 45 degrees) and positioned at the reference position, and the welding wire 2 and the works 3a and 3b A sensing voltage (for example, about 500 V) is applied between the welding torch 1 and work 3
The position where the tip of the welding wire 2 comes into contact with the work 3a and a current (for example, a low current of about 30 mA) flows through is detected as the position of the upper surface of one work 3a. (B). Next, after the welding torch 1 is moved upward and returned to the above position, the welding torch 1 is moved to the other work 3
It is moved horizontally toward b (c), and the position where the tip of the welding wire 2 contacts the other work 3b and a current flows is detected as the position of the side surface of the one work 3b (d). . Based on the positions of the works 3a and 3b detected by such sensing, the position of the point P, which is the corner of the abutting portion of the perpendicular works 3a and 3b, is obtained and the position is stored. It should be noted that the robot controls the welding line of the welding torch 1 (the trajectory along which the welding torch 1 moves and welds) during the welding operation in accordance with the stored value, whereby the work 3a, 3
Fillet welding of b is performed.

[0003]

However, as shown in FIG. 3 (b), the conductive foreign matter 4 such as iron powder or mill scale generated when the work 3a, 3b is manufactured by cutting work is generated. −
If the foreign matter 4 adheres to the surface of the work 3a, the tip of the welding wire 2 may come into contact with the work, causing an error S in the position detection of the upper surface of the work 3a. Further, as shown in FIGS. 3 (c) and 3 (d), the foreign matter 4 may be magnetized and adsorbed to the tip of the welding wire 2, and when the work 3b is sensed in this state, the welding wire 2 is detected. The foreign matter 4 comes into contact with the workpiece 3 before it comes into contact with the side surface of the work 3b, which causes an error T in the position detection of the side surface of the work 3b.

As described above, if the foreign matter 4 causes a malfunction in the position detection of the works 3a and 3b, which are the objects to be welded,
There is a problem that an accurate position of the point P cannot be obtained, the welding line in the welding operation becomes inaccurate, and the welding quality deteriorates. In addition, when the error S or T exceeds a certain value, a so-called chocolate stop occurs in which the sensing is automatically stopped. Therefore, in order to restart the sensing such as the work of removing the foreign matter 4 adhering to the welding wire 2. However, there is a problem in that the work efficiency is lowered because the adjustment and the operation are required.

In view of the above-mentioned problems, the present invention can prevent the erroneous operation of the work position detection caused by the foreign matter adhering to the work surface, and improve the welding quality and the work efficiency. It is an object of the present invention to provide a method for preventing malfunction of the position detection and a device therefor.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention senses between a welding wire and a work in a state where a welding wire of a predetermined length is projected from the tip of the welding torch. A work position detection method using a memory / reproduction type arc welding robot provided with a sensing means for detecting a work position by applying a voltage and causing an electric current to flow when the welding wire and the work come into contact with each other. The sensing is performed while blowing a compressed gas on the surface of the work.

Further, in the apparatus of the present invention, a gas supply source and an existing shield gas supply source and foreign matter removal are provided in the middle of a pipe line for guiding the shield gas ejected from the welding torch to the welding torch. A switching device for switching between the compressed gas supply source and the compressed gas supply source is provided.

[0008]

According to the method of the present invention, the compressed gas is blown onto the surface of the work, so that the foreign matter on the surface of the work is blown away and removed by the compressed gas.

Further, according to the apparatus of the present invention, since the compressed gas such as air is ejected from the tip of the welding torch by utilizing the shield gas pipe line, foreign matter on the work surface is generated by the compressed gas. In addition to being blown off and removed, the nozzle at the tip of the welding torch is cooled, and welding spatter adhering to the inner surface of the nozzle is blown off and removed, and a dedicated device for ejecting compressed gas is not required.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows a memory / memory equipped with an example of a work position detection malfunction prevention device for carrying out the method of the present invention.
FIG. 2 is a perspective view showing a regenerative arc welding system, FIG. 2B is a configuration diagram showing a main part of the embodiment, and FIG. 2 is a partially sectional side view showing a welding torch 1 in an enlarged manner. As shown in FIG. 1, the arc welding robot includes a welding robot 5 having an articulated arm 5a, a controller 6 for controlling the welding welding robot 5, and a welding torch 1. A main part is composed of a switching device 9 for connecting and disconnecting the conduit 7 for supplying the cold gas and the conduit 8 for supplying the compressed gas for removing foreign matters.

The welding robot 5 is equipped with a welding torch 1 at the tip of the arm 5a, and is pulled out from the wire container 12 by a command from the controller 6 equipped with a robot controller, a welding power source and the like. Welding wire 2
The welding work is carried out on the work 3 which is extended from the tip of the jaw 1 and attached to a positioner (not shown).

The pipe line 7 for supplying the shield gas supplies a shield gas such as carbon dioxide gas, argon or helium ejected from the welding torch 1 at the time of welding to a supply source 1 such as a gas cylinder.
It is sent from 0. The compressed gas supply conduit 8 is a pipe for ejecting compressed gas (air) from the compressor 11 from the welding torch 1 during sensing. The switching device 9 includes switching valves 9a and 9b.
It has a structure in which a and 9b are switched by a command from the controller 6 so that the pipe lines 7 and 8 connected to these switching valves are selectively communicated with the welding torch 1 side.

As shown in FIG. 2, the welding torch 1 is provided with hoses 1a and 1b for supplying and discharging water for cooling it, a hose 1c for supplying shield gas, and a welding wire 2 supply. The conduit 1d for welding is assembled from the rear end of the torch cover 1e, and the welding wire 2 fed from the conduit 1d passes through the hollow inner guide 1f and the tip 1g (the tip 1g is the torch tip). Is held by the nozzle 1h through the holder 1i). Further, the shield gas supply hose 1c
Is connected to the inner guide 1f at the portion H, and the shield gas fed from the hose 1c at the time of welding is ejected from the tip of the tip 1g through the inner guide 1f.

Next, the sensing method of the present invention will be described. As shown in FIG. 1 (B), the controller
When the welding torch 1 starts sensing the work 3 under the control of the controller 6, a command is simultaneously issued from the controller 6 to the switching device 9 and the switching valve 9a switches from the illustrated position a to the position b. The compressed gas supply conduit 8 communicates with the shield gas supply hose 1c of the welding torch 1. Also, see
Since the conduit 7 for supplying the cold gas is shut off by the switching valve 9b, only the compressed gas supplied from the compressor 11 is ejected from the tip of the welding torch 1 during sensing. The pressure of the compressed gas is preferably 2 to 10 kg /
cm ^2, more preferably plant air - set to 3-5 kg / cm ² which can be used.

Upon completion of sensing, the controller 6
In response to a command from, the switching valve 9a returns to the illustrated position a,
The switching valve 9b switches from the illustrated c position to the d position. As a result, the conduit 8 is shut off by the switching valve 9a, and the conduit 7 communicates with the shield gas supply hose 1c, so that it remains inside the hose 1c and the welding torch 1. The compressed gas that had been used is blown out by the shield gas, and the shield gas is in a state of being jetted from the tip of the welding torch 1,
Welding work can be started. In this example, the switching valves 9a and 9b are switched under the control of the controller 6, but may be switched manually.

As described above, the compressed gas is ejected from the tip of the welding torch 1 toward the work 3 at the same time when the sensing is started, and the iron powder and the iron powder adhered to the surface of the work 3 by the compressed gas are discharged. Since the foreign matter 4 such as a mill scale is blown away and removed, it is possible to prevent a malfunction of the work position detection caused by the foreign matter 4 existing between the work 3 and the welding wire 2. As a result, an accurate welding line is required, welding quality can be improved, and sensing stop due to a malfunction can be prevented, so that work efficiency can be improved. Further, since the shield gas pipe of the welding torch 1 is used to eject the compressed gas from the tip of the welding torch 1, the welding torch 1 is provided with the compressed gas pipe exclusively. In addition, it is not necessary to provide a separate compressed gas jetting device, and it can be manufactured at low cost. Further, by ejecting the compressed gas from the tip of the welding torch 1, the nozzle 1h is cooled so that welding spatter is less likely to adhere, and the welding spatter adhered to the inner surface of the nozzle 1h is blown away and removed. Therefore, the malfunction of the work position detection can be prevented more reliably.

Although it is possible to use a gas other than air as the compressed gas, the use of factory air can be carried out at a low cost and without using a dedicated compressor 11. The present invention is also applicable to welding of other forms other than fillet welding.

[0018]

According to the first aspect of the present invention, since the sensing is performed while blowing the compressed gas onto the surface of the work, the compressed gas blows away and removes the foreign matter on the surface of the work. It is possible to prevent the erroneous operation of the work position detection caused by the interposition between the welding wire and the welding wire. As a result, an accurate welding line can be obtained, welding quality can be improved, and chocolate stoppage can be prevented, so that work efficiency can be improved.

According to the second aspect of the present invention, the compressed gas supply pipeline can be communicated with the shield gas pipeline of the welding torch at the time of sensing, so that the compressed gas can be ejected from the tip of the welding torch. , The foreign matter on the work surface is blown away and removed by the compressed gas, the nozzle at the tip of the welding torch is cooled, welding spatter hardly adheres, and the welding spatter adhered to the inner surface of the nozzle. Is blown away and removed, so that the malfunction of the work position detection can be more reliably prevented. In addition, it does not require a special device such as a compressed gas jetting device and can be implemented at low cost.

[Brief description of drawings]

FIG. 1A is a memory / reproduction type disk equipped with an example of an apparatus for carrying out a work position detection malfunction prevention method according to the present invention.
3B is a perspective view showing a welding system, and FIG. 1B is a configuration diagram showing a main part of the embodiment.

FIG. 2 is a partial cross-sectional side view showing an enlarged example of the welding torch used in this embodiment.

FIG. 3 is a process diagram showing an example of sensing using a conventional arc welding robot.

[Explanation of symbols]

 1 Welding Torch 2 Welding Wire 3 Work 5 Welding Robot 6 Controller 7 Shield Gas Supply Pipeline 8 Compressed Gas Supply Pipeline 9 Switching Device 9a, 9b Switching Valve 10 Shield Gas Supply Source 11 Compressor −

Claims (2)

[Claims] 1. A welding wire having a predetermined length is projected from the tip of the welding torch, and a sensing voltage is applied between the welding wire and the work so that the welding wire and the work come into contact with each other. A work position detection method using a memory / reproduction type arc welding robot equipped with a sensing means for detecting a work position by flowing an electric current, while spraying a compressed gas on the work surface. A method for preventing malfunction of work position detection, which is characterized by performing sensing. 2. An apparatus for carrying out the malfunction prevention method according to claim 1, wherein a gas supply source is already provided in the middle of a pipeline for guiding the shield gas ejected from the welding torch to the welding torch. 2. A work position detection malfunction preventing device, comprising a switching device for switching between the shield gas supply source and the foreign matter removing compressed gas supply source.