WO1994006603A1

WO1994006603A1 - Spatter preventing method and apparatus for visual arc sensors

Info

Publication number: WO1994006603A1
Application number: PCT/JP1993/001336
Authority: WO
Inventors: Ryo Nihei; Hiroshi Wakio
Original assignee: Fanuc Ltd
Priority date: 1992-09-17
Filing date: 1993-09-17
Publication date: 1994-03-31
Also published as: JPH0691586A

Abstract

A visual arc sensor (30) attached with a welding torch to a free end portion of a welding robot is provided with a spatter preventing apparatus having a curtain forming unit, which is adapted to form a curtain (37) of a gas current in parallel with a protective window glass (38) of the arc sensor (30), so as to prevent the welding spatter or welding fume scattering and falling from the above from reaching the outer surface of the window glass even when the detection of a welding position (52) is carried out with an arc welding torch (28) used in an upwardly directed posture.

Description

Description Method and apparatus for preventing spatter of visual arc sensor

The present invention relates to an industrial robot, and more particularly, to a visual arc sensor protection device provided in a tip region of an arc welding robot for detecting an arc welding position and measuring a distance, and particularly relates to a visual arc sensor inside a container. Protects the detection light emitting means and light receiving means composed of CCD elements stored in the protective window plate. The welding fume, spatter, etc. during arc welding to the protective window plate do not adhere or accumulate even when the protective window plate is facing upward. The present invention relates to a method for protecting a visual arc sensor from spatters and the like, which is capable of protecting and preventing dirt, and for implementing the same method in a visual arc sensor. Conventional technology

Recently, arc welding robots tend to be used frequently in the manufacture of automobiles, assembly lines, and assembly of building structural frames, etc. In this type of arc welding port, the arc welding position of the workpiece is measured using an arc sensor. In accordance with the detected data, the movable part of the robot controls the movement of the arc welding torch attached to the robot tip area so as to achieve arc welding along a desired welding line on the workpiece. It is configured.

In such an arc welding robot, an arc sensor that detects a welding position or a part has recently been irradiated with laser light emitted from a semiconductor laser onto a workpiece, and the reflected light is a light receiving means comprising the above-described CCD element. There is a tendency to use a visual arc sensor that receives light at a time and obtains shape data of the welded part. Such a visual arc sensor includes a semiconductor laser as described above inside a sensor container, a galvanometer for giving a scanning effect to laser emission light,

It has a structure in which light receiving means composed of CCD elements, optical elements such as lenses, etc. are stored, and these are covered with a protective window made of transparent resin material, etc., which protects them from spatter generated during arc welding and welding fumes. ing. An open air chamber is provided in the front area of the protective window, and a means is also provided for injecting pressurized air into the air chamber to purge spatter fume scattered from the arc welded portion to the outside through the opening. Have been.

However, even in the above-described visual arc sensor, the arc welding robot, for example, performs arc welding on a ceiling area inside a vehicle body or a corner portion above a steel structure in an automobile assembly line. The arc sensor detects the welding position with respect to the arc welding part while maintaining the protection window in the upward position. As a result, it is difficult to completely prevent the spatter that scatters and falls from the arc-welded part from adhering and accumulating on the surface of the protective window. Also occurs. Thus, the sputter welding fume deposited on the surface of the protective window degrades the visual arc sensor's ability to detect the welding position mediated by the laser beam, and in turn reduces the welding accuracy due to the arc welding robot. O Disclosure of the invention

Accordingly, an object of the present invention is to solve such a problem and to improve a method of protecting against a spatter by improving the protection window of the visual arc sensor so that the welding position can be detected while always keeping the protection window clean. It is to provide

Another object of the present invention is to implement the above-described protection method against spatter. Another object of the present invention is to provide a spatter prevention device incorporated in a visual arc sensor.

According to the present invention, even when the visual arc sensor performs the detection of the welding position in an upward state in accordance with the upward use of the arc welding torch, the spatters scattered and dropped from above cannot reach the window plate surface of the protective window. In this way, a gas (gas) flow curtain is formed, and at the same time, the welding fume is prevented from adhering.

That is, according to one aspect of the present invention, the sensor container and the detection light emitted from the inside of the sensor container through the protective window of the sensor container are irradiated to the arc welding portion and reflected. A method for protecting a visual arc sensor having a sensor unit for detecting an arc welding portion by receiving light through the above protective window from contamination by welding fumes and welding spatters.

A light-transmitting protective window plate is attached to the protective window,

Forming a gas curtain comprising a gas flow layer on the front surface of the protective window plate;

The present invention provides a method for protecting a visual arc sensor from dirt in which the welding fume and the welding spatter scattered toward the protective window plate are carried away from the front of the protective window plate to the surroundings by the gas flow of the gas curtain. Is done.

According to another aspect of the present invention, a sensor container and a detection light emitted from the inside of the sensor container through a protective window of the sensor container are applied to the arc welding portion, and the reflected light is reflected by the above-described light source. A spark-prevention device incorporated in a visual arc sensor equipped with a sensor unit that receives light through a protective window and detects the arc welded area,

Means for forming a gas power layer comprising a gas flow layer provided in a front area of a window plate mounted on the protective window of the sensor container. And a sprung prevention device for a visual arc sensor, wherein the gas curtain scatters from the arc welding site and a sputter is cut off in front of the protection window.

The gas curtain composed of a gas flow layer is preferably composed of an air curtain using a pressure air flow, and a pressure air line of about 5 atm, which is often used in arc welding robots, is provided. As a pressure air supply source, a power air flow can be formed by the pressure air flow introduced from the pressure air line. Preferably, a pressure air flow path is formed along the vessel wall of the visual arc sensor, and air having a constant thickness is formed along the surface of the protective window provided at the front of the vessel. If a stream bed is formed and an air curtain is stretched by this air stream layer, a compact spatter prevention device can be formed. BRIEF DESCRIPTION OF THE FIGURES

The above and other objects, features, and advantages of the present invention will be described in more detail with reference to embodiments shown in the accompanying drawings.

FIG. 1A is a cross-sectional view of a visual arc sensor provided with a spall prevention device according to the present invention,

Fig. 1B is a front view of the visual arc sensor as seen from the entrance and exit of the detection light,

FIG. 2 is a front view showing a state in which a corner of a structure is arc-welded in an upward posture by an articulated arm type arc welding robot having an arc sensor.

BEST MODE FOR CARRYING OUT THE INVENTION

First, referring to FIG. 2, a multi-jointed arm type robot 10 having a spark sensor at the forefront end having a spatter protection device for implementing the spatter protection method according to the present invention. Are steel frames such as buildings or bridges, Arc welding is performed while flying an arc upward at a corner 52 of a structure 50 such as a steel girder.

That is, the robot 10 has a rotating body 16 at the top of a stationary body 14 erected on the base 12, and a joint 16 a having a horizontal axis in the tip region of the rotating body 16. A first robot arm 18 is pivotally attached to the joint 16a so as to be able to turn up and down. A joint 18a having the same horizontal axis is provided at the tip of the first robot arm 18, and the second robot arm 20 is pivotally connected to the joint 18a. A wrist drive motor 22 is provided on the rear side of the second robot arm 20, and a distal end of the second robot arm 20 includes a swivel around a horizontal axis parallel to the axes of the joints 16 a and 18 a. A robot wrist 24 having a number of degrees of freedom of movement is attached, and a torch 28 for arc welding and an arc sensor 30 are attached to the robot wrist 24 via a holding bracket 26. Arc welding is performed with the tip of the welding torch 28 and the front of the arc sensor 30 facing upward at the corner 52 of the object 50.

As described above, when an arc welding is to be performed on the welded portion in the inner deep region such as the corner 52 of the structure 50 in an upward posture, the welding spatter naturally falls from the welded portion and the arc sensor 3 Above 0, those spatters are scattered. Therefore, such welding spatter is caused by the arc sensor 3

When the sensor enters through the exit of the position detection light at 0 and the entrance of the detection light,

If it accumulates on the protective window of No. 0, the detection performance of the detected laser beam in the protective window decreases and the transmission performance at the time of incidence decreases, and the detection performance of the welding position deteriorates. Therefore, even when the arc welding posture is upward, a spatter prevention device that protects the protective window of the arc sensor 30 from welding spatter or welding fume is required. Referring to FIG. 1A and FIG. IB, the arc sensor 30 is composed of a container 32 having a housing structure, a laser oscillator 34 composed of a semiconductor laser as a sensor unit housed in the container 32, and the same laser. An oscillation mirror 36 consisting of a galvanometer that reflects and directs the laser light emitted from the oscillator 34 in a desired direction, and a light receiver consisting of a CCD camera that receives the reflected laser light from the object to be measured. Element 40 and lens 42 are provided.

In addition, a protective window plate 38 made of a material such as a synthetic resin material provided for protecting the sensor unit is formed on the front surface of the container 32, and an air chamber 44 is formed in front of the protective window plate 38. A lid 46 is provided, and a long hole-shaped emission port 48 a for directing the measurement laser beam emitted from the laser oscillator 34 toward the welding portion on the front surface of the lid 46, and a laser reflection. An entrance 48 b into which light enters is provided.

On the other hand, a nozzle means 45 is piped inside the container 32 and is a pressurized gas. Usually, compressed air sent from a compressed air source consisting of a compressor device installed at a robot use site or the like is supplied to the container 32. Air is supplied to the area in front of the protective window plate 38 from behind. The nozzle means 45 is provided along the inner wall surface of the container 32, and has a nozzle opening 45 a for jetting a layered or film-like air flow on the surface of the protective window plate 38 inside the air chamber 44. Therefore, the air flow ejected from the nozzle opening 45a forms an air curtain 37 in front of the protective window plate 38, and an exhaust port formed at the other end of the air chamber 44. A part of the airflow which is mainly exhausted from the air outlet 45b and forms the air curtain 37 is also exhausted from the laser light output port 48a and the laser light input port 48b.

For this reason, the welding spatter that scattered and fell from the arc welded portion via the laser beam output port 48a and the input port 48b entered the surface of the protective window plate 38. Even if those spatters are air curtains Due to 37, it is discharged from the exhaust port 45 along with the airflow forming the air curtain 37 without adhering or accumulating on the surface of the protective window plate 38.

Therefore, the surface of the protective window plate 38 is subjected to the wiping action by the air curtain 37, and at the same time, the adhesion and deposition of welding spatter or the adhesion of welding fumes are prevented. It can be maintained. As a result, the luminous intensity level of the detection laser light transmitted through the protective window plate 38 is maintained at a predetermined level, and the arc sensor function can be sufficiently exhibited.

The nozzle means 45 preferably blows out the air flow over the entire width of the inner side width “L” of the container 32 shown in FIG. 1B, but at least the laser light emission port 48 a, forming an air curtain 37 slightly wider than the full width of the entrance 4 8 b,

It is necessary to ensure that welding spatter and welding fumes can be excluded from the air chamber 44.

Further, in the illustrated example, the air curtain 37 is further formed along the front surface of the protective window plate 38, but the air curtain 37 is formed on the inner surface of the lid 46 having the laser light emission port 48a and the like. Another layer of air curtain along the side may be installed.

Further, in the above-described embodiment, the spatter prevention device is provided in the arc sensor provided at the tip of the arc welding robot. However, the invention is not limited to the robot, but may be provided in a dedicated automatic welding machine or the like. It is obvious that it can be applied to arc sensors.

As is apparent from the above description, the present invention provides a welding spatter or a spatter that falls and falls from above even when the visual arc sensor performs the welding position detection in an upward state with the upward use of the arc welding torch. Gas flow to prevent welding fumes from reaching the surface of the protective glazing. Since the curtains are stretched and the fumes are also prevented from adhering, the protective window is protected from contamination due to welding spatter and welding fume adhesion and accumulation, and always maintains a clean protective window surface. Therefore, the performance of the arc sensor can be maintained at a high level.

Of course, not only in the upward position, but also in the downward position and the horizontal position, it is needless to say that the protection function of the protection window is prevented by the welding spatter or the welding unit.

Further, since the air curtain is formed inside the air chamber, the air flow forming the air curtain does not disturb the flow of the shielding gas used for arc welding.

It goes without saying that the present invention can be variously modified within the technical scope of the invention described in the appended claims.

Claims

The scope of the claims

1. The detection light emitted from the sensor container and the inside of the sensor container through the protective window of the sensor container is irradiated to the arc welding part, and the reflected light is received through the protective window to detect the arc welding part. In a method of protecting a visual arc sensor with a sensor unit for performing welding from fumes and welding spatters,

Forming a gas curtain comprising a gas flow layer (layer 1) on the front surface of the protective window plate;

The welding humid and the welding spatter scattered toward the protective window plate are carried away from the front of the protective window plate to the periphery by the gas flow of the gas force.

A method for protecting a visual arc sensor from contamination.

2. Irradiation of the detection light emitted from the sensor container and the inside of the sensor container through the protection window of the sensor container to the arc welding portion, and detection of the arc welding portion by receiving the reflected light through the protection window. A spatter prevention device incorporated in a visual arc sensor with a sensor unit that performs

Means for forming a gas curtain comprising a gas flow layer (layer 1) provided in a front area of a window plate mounted on the protective window of the sensor container, and the gas curtain scatters from the arc welding portion. A spatter prevention device for a visual arc sensor, wherein a welding hum and spatter are blocked in front of the protective window.

3. The means for forming the gas curtain includes: a nozzle means for discharging a steady flow of gas in parallel with a window plate mounted on the protective window of the sensor container; and supplying gas at a certain pressure to the nozzle means. Gas supply The sparger prevention device for a visual type ark sensor according to claim 2 provided.

4. The spatter preventing device for a visual arc sensor according to claim 3, wherein the sensor container includes an outlet for discharging a gas flow emitted by the means for forming the gas curtain.

5. The spatter prevention device for a visual arc sensor according to claim 2, wherein the gas emitted by the means for forming a gas force is air at a certain pressure.