KR100602785B1 - System for weld center point detection - Google Patents

Abstract

The present invention relates to a method for recognizing a welding center point, and an object thereof is to prevent a welding tip from hitting a welding object during welding, thereby preventing damage to the welding tip, improving welding quality, and increasing production speed. In providing.

The present invention for achieving the above object comprises the steps of setting a threshold value for determining the groove edge of the sampling offset d value, p value and the result of the second derivative, by operating the 'OSCIL' switch formed on the upper side of the remote controller Operating the motion controller, moving the torch and laser displacement sensor from left to right using the motion controller, and 2 * d to obtain (k + d) and (kd) values based on the initially measured signal. Measuring the value of the laser displacement sensor by the number of steps, and using the following equation (1) to detect the position value of the portion where the second derivative value is greater than the threshold value and to store the position 'A' value using the motion controller Detecting the position where the second derivative value is greater than or equal to the threshold value through continuous torch transfer, and storing the current position as the position 'B' value through the next motion controller, and recognizing the 'B' value. Motion Supporting the torch, moving the torch at a distance of (BA) / 2 in the opposite direction from the stationary position, displaying a position completion signal on the LCD window of the remote controller, and The technical gist of the method for recognizing a welding center point, comprising the steps of: starting the welding by transferring the height direction to the welding position.

Welding torch, center point, groove, second derivative, laser displacement sensor, remote controller.

Description

System for weld center point detection             

1 is a conceptual diagram of a general welding apparatus,

2 is a groove shape diagram of a welding object;

3 is an electrical model diagram of a torch and a welder,

4 is a development diagram according to an oscillation position;

5 is an edge detection procedure diagram of the present invention;

6 is an edge detection algorithm of the present invention;

7 is a conceptual diagram illustrating a sampling offset of the present invention;

8 is a shape diagram of a remote controller.

<Description of the symbols for the main parts of the drawings>

(10): welding carriage (20): welding torch

21: nozzle 22: torch tip

(23): welding wire (24): laser displacement sensor

30: pipe 40: weld groove

The present invention relates to a method for recognizing a welding center point, and more particularly, to prevent welding tip from hitting a welding object during welding, to prevent damage to the welding tip, to improve welding quality, and to increase production speed. It is about a method.

In general, in the case of pipe welding onshore and offshore, there is a problem in that the pipe is connected by direct welding at the site where the characteristics are intended to be installed. In the case of large pipes, welding can be performed while the pipe is rotated under a fixed welding torch, but it is difficult to fix the welding torch in the field conditions, and there is a problem in installing equipment for rotating a heavy pipe. In order to solve this problem, an orbital welding carriage has been developed to weld a fixed pipe while the welding carriage rotates, but since the size and weight are mostly 500 kg or more, it is not only very difficult for workers to move in the actual field but also desired. To weld at the welding position, there is a disadvantage that a heavy weight welding carriage must be moved. In order to solve this problem, an orbital welding carriage which can be easily moved and welded by an operator has been developed or developed in various forms abroad. It is applied to welding, shielded metal arc welding and gas tungsten arc welding. Prior to the development of digital automatic welding carriages, analog carriage controllers were the mainstay, and tended to be affected by poor welding environment and ambient temperature. In the case of digital controllers, the speed of development is increasing very rapidly in recent years, and most of the recently developed dissolution carriage controllers have exhibited products using digital characteristics.

Welding carriage controller adopting digital function can control motor control, welding machine control, oscillation control, welding condition stored in database in various ways as well as advantages that are not greatly affected by the harsh environment and ambient temperature. The ability to use the machine efficiently and by using pre-programmed functions. Products and patents developed overseas have various controls such as automatic welding condition control, oscillation control, welder control, and real-time control has been successfully implemented.

Conventionally, a welding wire is supplied through a welding tip, and in the case of a welding tip, the welding tip moves together as a single body by the left and right movement of the welding torch, and the welding tip and the welding wire are connected together to a welding power supply that supplies a high current. When the oscillation operation is performed at an abnormal position such as 4b, an electrical short circuit occurs due to contact between the welding object and the welding tip, and melting occurs due to overheating of the tip due to the short circuit phenomenon, thereby deteriorating welding quality. Due to the time delay caused by tip replacement, there are many problems such as lowering the welding production speed.

The present invention is made to solve the conventional problems as described above,

Its purpose is to provide a welding center point recognition method that prevents the welding tip from hitting the welding object during welding, thereby preventing damage to the welding tip, improving welding quality, and increasing production speed.

According to the present invention, a threshold value for determining a groove edge among sampling offset d values, p values, and second derivatives is set, and the motion controller is operated by operating an 'OSCIL' switch formed at an upper side of the remote controller. Moving the torch and the laser displacement sensor from the left to the right using a motion controller, and by 2 * d number of laser displacement sensors to obtain (k + d) and (kd) values based on the initially measured signal. Measuring the value of, using the following equation (1) to detect the position value of the part where the second derivative value is above the threshold value and storing it as the position 'A' value by using the motion controller, and the continuous torch Detecting the position where the second derivative value is greater than or equal to the threshold value through the transfer, and storing the current position as the position 'B' value through the next motion controller, and stopping the motion after recognizing the 'B' value Wow, stop Conveying the torch at a distance of (BA) / 2 in the opposite direction from the position, displaying the position completion signal on the LCD window of the remote controller, and conveying the height direction of the torch to the welding position through the remote controller; By providing a welding center point recognition method characterized in that the step consisting of starting the welding can achieve the object pursued by the invention.

When described in detail with reference to the accompanying drawings, the configuration and the operation of the embodiment of the present invention to achieve the object as described above and to perform the task for eliminating the conventional drawbacks.

1 shows a conceptual diagram of a general welding apparatus, in which a welding groove 40 is formed on a pipe 30, a welding carriage 10 is installed along the groove 40, and the welding torch 20 is provided. It is provided on one side of, and consists of a laser displacement sensor 24 composed of a semiconductor laser, a lens and a one-dimensional array of charge coupled devices (CCD).

2 is a view illustrating a groove shape of a welding object, and generally, an end of the welding object is cut into a 'V' or 'U' shape.

3 shows an electrical model diagram of a torch and a welding machine, the welding torch 20 includes a nozzle 21, a torch tip 22 formed at one lower end of the nozzle, and a welding supplied through the tip 22. It consists of the wire 23.

4 illustrates a development diagram according to an oscillation position, where 4a represents oscillation at a normal position and 4b represents oscillation at an abnormal position.

FIG. 8 is a diagram of a remote controller, comprising: an LCD formed on one side of the remote controller to indicate completion of welding center point recognition; a start switch and a stop switch for setting a welding start; And an oscil switch to set the start of motion and weld center point recognition.

Referring to the configuration as described above the operation of the present invention.

The laser light scanned by the semiconductor laser in the laser displacement sensor 24 is reflected through the measurement object to form a one-dimensional CCD through the lens, and the one-dimensional CCD is composed of tens to hundreds of pixels. By using the principle of predicting the position of the measurement object by the position of the pixel formed by the laser, the center of the welding torch 20 attached to the torch oscillation mechanism and the center point of the laser scanned by the laser displacement sensor are fixed first. When the torch oscillation mechanism is moved from the left to the right, the sensor signal output from the laser displacement sensor varies depending on the distance information. The signal output from the laser displacement sensor passes through the second derivative and detects the groove edge by using a specific point of negative value generated near the edge of the groove, and recognizes the welding center line by the detected groove edge two points.

The formula for obtaining the second derivative value is

value = (m (k + d) -2 * m (k) + m (k-d)) / p equation (1)

Where

value: the second derivative

d`: sampling offset

m (k + d): Laser displacement sensor signal value measured at (k + d) th

m (k): Laser displacement sensor signal value measured at (k) th                     

m (k-d): Laser displacement sensor signal value measured at (k-d) th

p: Constant for adjusting sensitivity of second derivative

to be.

5 and 6, d is a variable for optimally finding the maximum and minimum points of the second derivative. In case I, the value of d is 1, the second derivative is very small and does not differ much from the values calculated in the previous signal measurement section, which can act as a factor to reduce the reliability of the algorithm for groove edge detection. If the d value has a somewhat large value as in case II, the second derivative value is very large and differentiates by comparing with the second derivative value determined in the next signal measurement interval or the previous signal measurement interval as in case III. Since the sampling offset is used in the second derivative to determine the groove edge, the second derivative can be optimally varied by varying the values.

The variable p, which determines the overall size of the second derivative, can be adjusted to suit the characteristics of the CPU processor used. The better the CPU performance, the smaller the value of p can increase the sensitivity.

The algorithm for edge detection is

Setting a threshold for determining a groove edge among the results of the sampling offset d value, p value, and second derivative;

Operating a motion controller by operating an 'OSCIL' switch formed at an upper side of the remote controller;

Transferring the torch 20 and the laser displacement sensor 24 from left to right using a motion controller,

Measuring the value of the laser displacement sensor 24 by the number of 2 * d to obtain (k + d) and (k-d) values based on the initially measured signal,

Motion using the equation (1) (value = (m (k + d) -2 * m (k) + m (kd)) / p) detects the position value of the part where the second derivative is above the threshold Storing the position 'A' using a controller;

Detecting the position where the second derivative value exceeds the threshold value through continuous torch movement, and storing the current position as the position 'B' value through the next motion controller,

Stopping the motion after recognizing the 'B' value;

Conveying the torch at a distance of (B-A) / 2 in the opposite direction from the stationary position,

Displaying the position completion signal on the LCD window of the remote controller;

It is composed of a step of starting the welding by transferring the height direction of the torch to the welding position through the remote controller.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

The present invention as described above can prevent the welding tip from hitting the welding object during welding to prevent damage of the welding tip due to a short circuit, and the welding of the welding tip does not occur as described above to improve the welding quality It is a very useful invention, such as to increase the production speed by reducing the replacement work of the tip caused by the damaged welding tip.

Claims (1)

Setting a threshold for determining a groove edge among the results of the sampling offset d value, p value, and second derivative; Operating a motion controller by operating an 'OSCIL' switch formed at an upper side of the remote controller; Transferring the torch 20 and the laser displacement sensor 24 from left to right using the motion controller; Measuring the value of the laser displacement sensor 24 by the number of 2 * d to obtain (k + d) and (k-d) values based on the initially measured signal, Motion using the equation (1) (value = (m (k + d) -2 * m (k) + m (kd)) / p) detects the position value of the part where the second derivative is above the threshold Storing the position 'A' using a controller; Detecting the position where the second derivative value exceeds the threshold value through continuous torch movement, and storing the current position as the position 'B' value through the next motion controller, Stopping the motion after recognizing the 'B' value; Conveying the torch at a distance of (B-A) / 2 in the opposite direction from the stationary position, Displaying the position completion signal on the LCD window of the remote controller; Welding center point recognition method comprising the step of starting the welding by moving the height direction of the torch to the welding position through a remote controller.

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