JP2002178155A - Plasma cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma cutting device capable of cutting a material to be worked while processing a picture of a TV camera (television camera) which is provided integrally with a torch moved or turned by a robot and estimating/controlling a distance between a torch nozzle and the material to be worked at a real time. SOLUTION: The device is provided with the torch which is moved or turned by the robot having a controller, the television camera which is provided integrally with the torch and a picture processor for the picture imaged by the television camera. A waveform signal relating to a plasma arc is extracted and information estimating the distance between a torch nozzle and the material to be worked is outputted by the picture processor, the information is inputted into the controller and the distance between the nozzle and the material to be worked is controlled by the robot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma cutting apparatus, which performs image processing of a photographed image of a plasma arc.
The present invention relates to a means for estimating and controlling the distance between a torch nozzle and a workpiece.

[0002]

2. Description of the Related Art In a plasma cutting apparatus, gas ejected at a high speed from a torch nozzle to which a voltage is applied between a workpiece and a workpiece is a plasma arc in which ions and protons are separated, and emits strong light at extremely high temperatures. Accompany. The proton is
It collides with a minute part of the workpiece and concentrates on it, forming a melting point and dispersing and piercing. The melting point is cut by a relative movement in a cutting direction by a robot or the like. As described above, there is a correlation between the cutting speed, the voltage, and the distance between the nozzle and the workpiece (hereinafter simply referred to as the distance to the workpiece). For high-quality cutting, it is necessary to adjust any one based on the correlation to maintain stable plasma arc.

However, when the shape of the workpiece is a three-dimensional shape such as a curved surface, means for controlling a robot or the like by a program stored in advance so that the torch height relative to the workpiece becomes a set value such as a constant value. It is not practical because of its complicated and high processing cost. Therefore, it is desirable to perform a cutting process while providing a distance measuring unit such as a non-contact distance sensor and detecting and controlling the distance to the workpiece in real time.

[0004]

The detection of the distance to the workpiece needs to be based on the length of the plasma arc along the locus of the plasma arc. That is, even if the torch height is the same, the measurement angle on the workpiece is different from the melting point when the plasma arc is emitted to the workpiece or when the workpiece is three-dimensional. In this case, measurement accuracy becomes a problem, and it becomes difficult to maintain stable plasma arc. Therefore, it is necessary to provide a distance sensor or the like near the torch and measure along the plasma arc as much as possible. However, since the plasma arc and the melting point are very high temperature and high brightness, it is difficult to install a distance sensor near the plasma arc and to make the measurement near the melting point. do not do.

The present invention has been made in view of such a background, and performs image processing of an image of a television camera (television camera) provided integrally with a torch which is moved or rotated by a robot, so that the workpiece can be processed. It is an object of the present invention to provide a plasma cutting device capable of performing a cutting process while estimating and controlling the distance of the object in real time.

[0006]

Means for Solving the Problems As a result of earnest research, the present inventor has solved this problem by the following means. The present invention includes a robot and a control device for the robot, a torch moved or rotated by the robot, a television camera provided integrally with the torch, and an image processing device for an image captured by the television camera. It is a cutting device.

Here, a feature of the present invention is that the image processing apparatus extracts a waveform signal relating to a plasma arc and outputs information estimating a distance between a nozzle of the torch and a workpiece, and the information includes the information. It is an object to provide means for inputting to a control device and controlling the distance between the nozzle and the workpiece by the robot.

[0008] It is desirable that the television camera is provided via a turning mechanism, and the TV camera is turned in an appropriate shooting direction based on the traveling direction of cutting processing to shoot an image.

The control device can control the distance between the nozzle of the torch and the workpiece to be constant.

It is preferable that an optical reflecting mirror is provided, and the television camera shoots an image via the optical reflecting mirror.

[0011]

Embodiments of the present invention will be described with reference to the drawings of the embodiments. FIG. 1 is a configuration diagram of a main part of a plasma cutting apparatus according to Embodiment 1 of the present invention. In the figure, 1 is a robot, 2 is a torch, 3 is a TV camera, 4 is a workpiece,
5 is a nozzle, 6 is an image processing device, 7 is a control device, 8 is a plasma arc, and 9 is a turning mechanism.

The plasma cutting apparatus shown in the embodiment of FIG.
A robot 1 and a controller 7 for the robot 1; a torch 2 moved or rotated by the robot 1; and a television camera 3 provided integrally with the torch 2. It is a cutting device provided with.

Here, the feature of the present invention is that the image processing device 6
Is to extract a waveform signal such as binarization of the plasma arc 8 and output information that estimates the distance between the nozzle 5 and the workpiece 4. Further, the information is input to the control device 7 to control the robot 1 and control the distance between the nozzle 5 and the workpiece 4. The television camera 3 takes an image of the plasma arc 8 from a substantially side surface thereof, and at an angle such that a linear image of the plasma arc 8 is parallel or vertical to a horizontal scanning line as much as possible so that image processing is easy. Shoot.

The plasma arc 8 has a high temperature of about 6000 ° C. and emits light of high brightness. However, workpiece 4
Is about 1500 ° C. for iron, for example. Therefore, the plasma arc 8 portion of the photographed image becomes a video signal of a much higher level than the image other than the portion unless there is an influence of other illuminations or the like. In the image processing device 6, the video signal is used as a signal of the plasma arc 8.
The binarized waveform signal is extracted separately from the melting point and other portions. Further, the image processing device 6 includes an arithmetic unit, and converts the length of the plasma arc 8 by referring to the shooting distance and angle, the focal length of the shooting lens, and other conditions based on the length of the waveform signal, That is, the nozzle height is estimated by calculation, and the information is output.
The information is input to the control device 7 and the height of the nozzle is controlled by the robot 1 to obtain a stable plasma arc 8 so that high-quality cutting can be performed.

In recent years, very small television cameras have been developed. The small television camera 3 is provided integrally with the torch 2 and is moved or rotated by the robot 1 so as to avoid shooting from the rear of the cutting process, and to minimize the plasma arc from the traveling direction or the lateral direction of the traveling. 8 is photographed. This is because, when photographed from the rear in the traveling direction, a portion of the plasma arc 8 pierced through the workpiece and ejected to the back side can be seen from the gap between the cut workpieces 4, and when the photograph is taken including this, the measurement is performed. This is because of an error. In this case, it is desirable that the television camera 3 is provided via a turning mechanism 9 and that an image be taken from an appropriate direction concentrically turned around the plasma arc 8. The swivel mechanism 9 can be photographed from the traveling direction side by performing adjustment or control manually or by control means, and the photographing angle and the distance to the plasma arc 8 are constant and accurate measurement can be performed.

Since the plasma arc 8 has a very high brightness, the television camera 3 can use the photographing lens having an extremely small aperture, may be dimmed by a filter or the like, or may be an infrared camera or the like. In order to take an image of the plasma arc 8 from the side, it is necessary to use the television camera 3 as small as possible and provide it so as not to come in contact with the workpiece 4. Therefore, if the imaging lens of the small diameter is used as much as possible, an optical reflecting mirror having a small area corresponding to the imaging lens is provided in front of the imaging lens, and the imaging is performed by reflecting the optical axis.
The size restriction of the television camera 3 is relaxed, and the television camera 3 can be installed away from the workpiece 4 and the plasma arc 8.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has two means relating to the arrangement of a television camera 3 for photographing a plasma arc 8. (Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIG. The movement or rotation of the torch 2 and the television camera 3 provided integrally with the torch 2 are controlled by the robot 1 having an articulated arm and the control device 7 thereof.
The plasma arc 8 ejected from the nozzle 5 of the torch 2 is
A melting point is formed by intensive collision with a minute portion of the workpiece 4, and the melting point is perforated by melting and scattering. Furthermore, cutting is performed by relatively moving the position of the plasma arc 8 with respect to the workpiece 4 in the cutting direction.

The television camera 3 photographs the plasma arc 8 from substantially its side, and photographs at a photographing angle such that a linear image of the plasma arc 8 is as parallel or perpendicular as possible to a scanning line. The TV camera 3 has a plasma arc 8
Can be avoided from the rearward direction of the cutting process by the turning mechanism 9 that turns concentrically around the center, and a turning control unit can be provided to control turning based on the moving direction of the cutting process. .

The video signal from the television camera 3 is input to an image processing device 6. The waveform signal of the portion of the plasma arc 8 which has been binarized or the like is referred to by the arithmetic means with reference to the photographing distance and angle, the focal length of the photographing lens, and other photographing conditions, and is converted to obtain the actual plasma arc 8 length. Estimate
Output that information. The control device 7 inputs the information,
The robot 1 controls the height of the nozzle based on the correlation, so that even in the case of a workpiece having a three-dimensional shape such as a curved surface, high-quality and low-cost cutting can be performed by the stable plasma arc 8.

Embodiment 2 Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a main part configuration diagram of a plasma cutting apparatus according to Embodiment 2 of the present invention. In the figure, 1 to 9 have been described above. 10 is an optical reflecting mirror. Embodiment 2 of the present invention
Is different from Embodiment 1 of the present invention in that
0 is provided to reflect the optical axis of the television camera 3 to photograph the plasma arc 8. Since the plasma arc 8 has high brightness, a small-diameter lens and an optical reflecting mirror 10 having a small area corresponding to the lens can be used. Thereby, the size limitation of the television camera 3 can be relaxed, and the television camera 3 can be installed away from the workpiece 4 and the high-temperature plasma arc 8.

[0021]

According to the present invention, the following effects can be exerted. The image processing apparatus extracts a waveform signal related to a plasma arc and outputs information that estimates a distance between a nozzle of the torch and a workpiece. The information is input to the control device, and the nozzle is connected to the nozzle by the robot. Since the distance to the workpiece is controlled, the height of the torch can be accurately controlled, and cutting of a workpiece having a three-dimensional shape such as a curved surface with high quality and low processing cost can be easily performed.

The television camera is provided via a swivel mechanism, and shoots in an appropriate shooting direction based on the traveling direction of cutting processing to shoot an image, thereby shooting the plasma arc that has penetrated the workpiece and ejected to the back side. Without this, the distance to the workpiece can be accurately controlled.

If the control unit controls the distance to the workpiece to be constant, the robot can control the distance to the workpiece stably by a robot.

[0024] By taking a picture through the optical reflecting mirror, the television camera can reduce the size limitation of the television camera, and can be installed at a distance from the workpiece and the plasma arc. Contact can be avoided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a plasma cutting apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of a plasma cutting apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

1: Robot 2: Torch 3: TV camera 4: Workpiece material 5: Nozzle 6: Image processing device 7: Control device 8: Plasma arc 9: Rotating mechanism 10: Optical reflecting mirror

Claims (4)

[Claims] An image processing apparatus for an image captured by the television camera, comprising a robot and a control device for the robot, a torch moved or rotated by the robot, and a television camera provided integrally with the torch. A cutting device, wherein the image processing device extracts a waveform signal related to a plasma arc and outputs information that estimates a distance between a nozzle of the torch and a workpiece, and the information is input to the control device. And a distance between the nozzle and the workpiece is controlled by the robot. 2. The plasma cutting apparatus according to claim 1, wherein the television camera is provided via a turning mechanism, and turns and shoots in an appropriate shooting direction based on a traveling direction of the cutting process. 3. The plasma cutting apparatus according to claim 1, wherein the control device controls the distance from the workpiece to be constant. 4. The optical camera according to claim 1, further comprising an optical reflecting mirror, wherein said television camera captures an image via said optical reflecting mirror.
4. The plasma cutting device according to any one of claims 1 to 3.