JPS5847275B2 - Backing metal synchronous control method for single-sided automatic welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for synchronously controlling the movement of a welding torch and a backing metal during single-sided automatic welding.

Single-sided automatic welding, in which the welding machine and backing metal are moved together along the seam of the steel plate, is often used for welding large steel plates such as hull blocks due to its high efficiency. However, in order to weld a steel plate with a curved surface using this method, it is necessary to synchronize the moving speeds of the welding machine and the backing metal, which move the front and back surfaces of the steel plate along the curved surface of the steel plate, so that they always face each other directly. be.

For this purpose, it is known that the moving speed of both is adjusted in advance according to the difference in the moving curvature radius of both, but in this case, it is necessary to adjust the moving speed of the two in advance according to the difference in the moving curvature radius of the two. Calculating and setting the moving speed for welding is extremely troublesome, and the calculations are mainly based on design values, resulting in deviations from the actual dimensions of the actual welding area and mechanical errors in the moving device. As the movement progresses, the misalignment increases, and in the end, the two sides deviate from their directly facing positions, causing the backing metal to no longer function properly.

As one method to solve this drawback, for example,
Publication No. 3612 discloses a method of detecting arc noise at the front end and rear end of a backing metal using an ultrasonic sensor and controlling the arc point so that it is always maintained within the range of the backing metal. In this method, the position of the arc point is detected using sound waves, so external noise, mechanical vibrations, etc. are mixed in as noise, and furthermore, the distance between the sound wave reception positions of the sensor at two points is limited by the size of the backing metal, so it cannot be made wide. Therefore, it is difficult to extract the difference in sound pressure level with high sensitivity, and it is impossible to expect high accuracy in synchronizing the backing metal with the movement of the arc point. There is little possibility that it can be used for control.

This invention was made in view of the above-mentioned problems, and it is possible to move the backing metal with high accuracy while directly facing the welding point directly below the welding point by the torch, and a detector is installed inside the backing metal. The object of the present invention is to provide a method for synchronous control of a backing metal, which can be incorporated and miniaturized, and can also obtain signal information proportional to welding heat input from the detector output.

In other words, in the backing metal synchronous control method for single-sided automatic welding of the present invention, a translucent backing material, such as a backing tape, is brought into contact with the back surface of the welded part of the base material to be welded, and the control method follows the movement of the welding machine. In single-sided automatic welding, in which welding is performed while applying a moving backing metal to the back surface of the welding part directly under the torch through the backing tape, a pair of photoelectric sensors embedded in the side of the backing metal that comes into contact with the backing tape is used. By the light receiving element,
With respect to the direction of welding progress, the light emitted from the back side of the welding part through the backing tape is received at two locations, one in front and the other at the rear, at a predetermined distance from each other in that direction from directly under the torch, and the light emitted from the front button and Obtain an electrical signal corresponding to the deviation of each amount of light received at the rear, compare the electrical deviation signal with a preset appropriate synchronous running signal, and calculate the difference between the front and rear light receiving positions of the backing metal. The speed of the drive motor for the backing metal is controlled based on the above comparison result so that the point directly below the torch is maintained at a predetermined position.

In other words, the point directly below the torch is held at the midpoint of the above light receiving position, the backing metal is driven and controlled so that the deviation of the amount of light received at both light receiving positions is always zero, and the backing metal is controlled to be at a position ahead or behind the above midpoint. If the point directly below the torch is held and moved, the backing metal is driven and controlled so that the deviation is held at either a positive or negative value.

Through such feedback control, the distance in the welding direction between each light receiving element and the point directly below the torch is always kept constant, so that the backing metal is always directly facing directly below the torch of the welding machine. Furthermore, since the change in the amount of light received by one of the preferably front light receiving elements is proportional to the change in the amount of light emitted by the arc and the red-hot part of the welding by the torch,
A detection signal of the amount of heat input is obtained from this change in the amount of received light, which can be used to input control of welding conditions for forming a proper back bead.

This invention will be described in detail with reference to the drawings of the embodiments. In FIGS. 1 and 2, 1 is the base material to be welded, 2 is the welding machine, 3 is the welding torch, 4 is the welding wire at the tip of the torch, and 5 is the welding wire. A backing material such as a backing copper plate, and 6 a translucent backing material such as a glass fiber tape that is in contact with the back surface of the welding portion in the welding length direction.

The backing metal 5 is supported by a self-propelled device 7 that moves following the welding machine 2, and is pressed against the back surface of the welding part directly under the welding torch through the backing material 6 with a predetermined pressing force. It is movable.

On the surface of this backing metal 5 that is in contact with the backing material 6, there are two photodiodes, etc., located directly below the tip of the welding wire 4 of the torch 3, one in front and the other in the welding direction. A pair of front and rear photoelectric light receiving elements 8a, 8b are embedded at a predetermined interval in the direction of welding progress, and the surface of the backing material 6 in contact with each light receiving element 8a, 8b is visually recognized. It is now possible to do so.

In this case, a hole is drilled in the upper surface of the backing metal 5, and a light receiving element 8a such as a photodiode is inserted into the hole.

8b may be inserted, and then the upper surface of this hole may be sealed with glass or the like to make the upper surface of the backing metal 5 a smooth, flush surface. It is possible to prevent the backing material 6 from hanging or wrinkled during movement, and even if the glass or the like that fills this hole has poor thermal conductivity, it will not adversely affect the backing bead since it is located in front of the torch. There isn't.

Each of the photoelectric receiving elements 8a and 8b captures the arc light and the red glow from the back surface of the molten red-hot part 9 that is melted by the arc between the welding wire 4 at the tip of the torch and the base metal 1 at the middle thereof. FIG. 2 shows an example of the incandescent light-emitting portion 9 of the back bead portion on the back surface side.

As shown in the figure, the upper part of each of the light receiving elements 8a, 8b is surrounded by the backing metal 5 itself which is in contact with the backing material 6. Therefore, the buried position of the light receiving elements 8a, ab is surrounded by the backing metal 5 itself which is in contact with the backing material 6. By selecting an appropriate distance from the periphery to the inside, it is completely unaffected by external light, and detection noise due to external light is extremely reduced.

In FIG. 2, a configuration block of a control system for carrying out the method of the present invention is attached, 10a.

10b is an amplifier that amplifies the light receiving output of each light receiving element 8a, 8b.

Each light receiving element 8a passes through these amplifiers 10a and 10b.
, 8b are input to a differential amplifier 11, and their deviation outputs are determined.

This deviation output is further input to the comparator 12, and the setter 1
After being compared with the appropriate synchronous running signal given in advance by 3, the difference signal of the comparison result is sent to the backing money movement speed control device 1.
4, and the speed of the self-propelled device 7 is controlled by the control signal output 15 of the control device 14.

That is, the light emitted from the arc at the point directly below the torch is transmitted through the backing tape 6, such as a transparent glass fiber tape, and is incident on each of the light receiving elements 8a and 8b.
, 8b approaches one of the light receiving elements, the output of the light receiving element on that side increases.

From this, the change in the difference in the outputs of the two light receiving elements is proportional to the amount of movement of the arc point with respect to the backing metal, and the positive or negative of the difference in output means the direction of movement with the reference signal value as the boundary.

Therefore, if a proper synchronous running signal is given by the setter 13 as this reference signal value and this is compared with the output of the differential amplifier 11, for example, when the comparator output is positive, the backing metal 5 is set against the torch. The amount of advance is proportional to the absolute value of the comparator output. Conversely, when the comparator output is negative, the backing metal 5 is lagging behind the torch, and the amount of lag is proportional to the absolute value of the comparator output. It is proportional to the absolute value of the comparator output at that time.

In this case, the appropriate synchronous running signal will give the synchronous position of the backing metal 5 with respect to the point directly below the torch, so that when the control device 14k receives the output of the comparator as an input, it becomes zero. The moving speed of the self-propelled device 7 is increased or decreased.

As a result, the backing metal 5 is moved by the self-propelled device 7 while always maintaining a predetermined corresponding position with respect to the point directly below the torch.

Incident light from the so-called red-hot part of the back pedestal constantly enters the light-receiving element 8b located behind the point directly under the torch in the direction of welding progress, but this is uniquely incorporated into the setting conditions in the setting device 13. It may be possible to compensate for this.

When running in synchronization as described above, the change in the amount of light received by both light receiving elements 8a and 8b corresponds to the change in the amount of heat input by the arc. The output 16 of the front light-receiving element 8a is taken out to the outside, and by controlling welding conditions such as welding current, voltage, and welding speed, this output 16 can be used to optimize the back bead by controlling heat input. That's how it is.

Furthermore, as shown in FIG. 2, two front light-receiving elements 8a and two rear light-receiving elements 8b are provided to calculate the sum of the outputs of the two front light-receiving elements and the sum of the outputs of the two rear light-receiving elements. By comparing, even if the backing metal is biased in the bead width direction or rotated, imbalance in the outputs of the front and rear light receiving elements can be prevented.

Since this invention is constructed as described above, it is possible to accurately detect the relative displacement between the backing metal and the point directly below the torch during welding without being subjected to any disturbance, thereby ensuring that the welding part is directly facing the molten part. The backing metal can be moved in synchronization with the backing metal, and the light emitted directly under the torch is captured by a light receiving element embedded in the backing metal, making it possible to simultaneously miniaturize the detection system and eliminate the effects of external light. It is clear that it can produce high industrial effects, such as being able to simultaneously obtain the following.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing a welding mode according to an embodiment of the present invention, and FIG. 2 is a temperature-controlled view of the configuration block diagram of the control system in FIG. 2: Welding machine, 3: Torch, 4: Welding wire, 5: Backing metal, 6: Backing material, 7: Self-propelled device, 8a. 8b: Photoelectric light receiving element, 11: Differential amplifier, 12: Comparator, 13: Setting device, 14: Backing metal movement speed control device.

Claims (1)

[Claims] 1. Place a translucent monitoring material in contact with the back surface of the welding part of the base material to be welded, and place a backing metal that moves following the movement of the welding machine onto the back surface of the welding part directly under the torch through the backing material. In single-sided automatic welding, in which welding is performed while the backing metal is applied, a pair of photoelectric light receiving elements are embedded in the surface of the backing metal that contacts the backing material, each at a constant interval in the welding progress direction, and the photoelectric light receiving elements detect the welding progress. In terms of direction, the light coming out from the back side of the welding part through the backing material is received at two locations, one in front and the other at the rear, which are spaced apart from each other by a predetermined distance from directly below the torch. Obtain an electrical signal corresponding to the deviation of each amount of light received, compare the deviation electrical signal with a preset appropriate synchronous running signal, and place it at a predetermined position between the front button and rear light receiving position of the backing metal Single-sided automatic welding characterized by synchronizing the movement of the welding torch and backing metal by controlling the speed of the drive motor of the backing metal based on the above comparison results so that the point directly below the torch is maintained. Backing fund synchronization control method.