JPH0329017Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an automatic weld seam tracking device that allows a welding torch to accurately follow the seam when welding the seam of a steel plate.

Prior Art and Problems In order to manufacture a steel pipe, as shown in FIG. There is a method of welding the butt portion 62 using a welding machine. Figure 6 shows the process in which a steel plate is successively bent into a pipe shape, where a shows the initial flat plate state, b shows the state where the cross section is bent into a bowl shape, and c
is further bent so that the cross section becomes almost circular,
d shows the state after further bending and welding.

When seam welding thin sheets like this, it is preferable to weld the seam directly above (in the center) and aim the welding torch at it, but since the sheets are thin, they have strong resilience, and the rollers can be used to weld them into a tubular shape. Even if it is formed, there will be a gap when it comes out of the roller. Further, in the step of rolling the flat plate into a tubular shape and welding the seams, the positions of the seams are not constant, but gently undulate in the longitudinal direction of the pipe. During forming, the seam position change is suppressed by the boat-shaped guide 56, but when the seams are in close contact, it is impossible to control the seam positions by such means. If the seam is meandering and the welding machine just aims directly above the steel pipe and welds, the center of the weld bead will not match the center of the seam.
It may shift to the left or right, and in severe cases it may shift from the seam, resulting in defective products.

Purpose of the Invention The present invention attempts to avoid the above-mentioned drawbacks by detecting changes in the position of the seam using optical means and automatically causing the welding machine to follow the position of the seam.

Structure of the invention The automatic weld seam tracking device of the invention consists of an optical fiber bundle consisting of a light-emitting optical fiber bundle in the center and light-receiving fiber bundles arranged on the left and right sides of the light-emitting fiber bundle, and an optical fiber bundle arranged at one end of the light-emitting fiber bundle. A light source is provided, and a pair of light receivers are placed at one end of the left and right light receiving fiber bundles, and the other end of the light emitting optical fiber bundle is located at the center of the seam of the welded object immediately before welding, where there is still a gap. To, left,
The other end of each light-receiving optical fiber bundle on the right is to the left of the seam,
A photodetector placed so as to face each of the surfaces of the workpieces on the right, and the projected light from the other end of the optical fiber bundle for projection, the surfaces of the workpieces on the left and right sides of the seam. an amplifier that takes the difference in the output of the pair of light receivers generated by receiving the light reflected by the light receiver;
The present invention is characterized in that it has a motor that is driven by the output of the amplifier and adjusts the position of the welding machine and the optical fiber bundle for illumination so as to aim at the seam during welding work. Let me explain this.

Embodiment of the invention FIG. 1 shows an embodiment of the invention, in which 10 is an object to be welded, and in the case of steel pipe welding, it is a steel plate rolled into the pipe shape described above. 12 is a light source that projects light toward the seam of the workpiece 10, 14 and 16 are light receivers that receive the reflected light, 18 and 20 are amplifiers, 22 is an inverter, and 24 is a difference calculator. amplifier,
26 is a comparator, 28 is a pulse generator, and 30 is a pulse motor. The light from the light source 12 is applied to the workpiece 1
0, and the reflected light is sent to the receiver 14, 1.
As shown in FIG. 2, a bundle 40 of optical (glass) fibers is used for the light receiving portion 6. As shown in FIG. As shown in the figure, this optical fiber bundle 40 includes a light projection 42 and its left side,
The light source 12 is located at one end of the light emitting optical fiber bundle 42, and the light receivers 14, 16 are opposed to one end of the light receiving optical fiber bundle 44, 46. The other end is the object to be welded 10
to face.

As shown in FIGS. 3a and 3b, the light emitting optical fiber bundle 42 is arranged with its center aligned with the center of the seam G of the workpiece 10 to be welded. A is a case where the width of the stitch G is large, and b is a case where it is small. In a, the projected light
Most of the light L ₁ passes through the seam G and enters the tube, and a small amount of light that hits the surfaces on both sides of the seam is reflected and enters the receiving optical fiber bundles 44 and 46, and these lights L ₂ , L ₃ are received by the light receivers 14 and 16.
In b, since the width of the seam G is narrow, only a small amount of light passes through the seam, and most of the light is reflected from the surfaces on both sides of the seam and enters the light-receiving optical fiber bundles 44 and 46, and these lights L ₂ , L ₃ is received by the light receivers 14 and 16. The outputs of the photodetectors 14 and 16 are amplified by amplifiers 18 and 20, one of which is inverted by an amplifier 22, and then the difference is taken by an amplifier 24. In FIG. 3A, the received light output is small, and in FIG.

On the other hand, Fig. 3c shows the case when the seam G shifts to the left, and Fig. 3d shows the case when it shifts to the right. and d, the opposite is true, so the amplifier 24 produces, for example, a positive output in the former case and a negative output in the latter case. Pulse generator 28 produces a pulse PL when amplifier 24 produces an output, and comparator 26 determines whether the output of amplifier 24 is positive or negative and produces a modified direction signal UD. Although not shown, the seam welding machine is set so as to aim at the top (center) of the steel pipe, but is also mounted so that it can be moved to the left and right by a motor. The pulse PL and the corrected direction signal UD output by the pulse generator 28 are supplied to the control device of the motor to cause the welding machine to follow the seam. These pulses PL and correction direction signal UD are also supplied to a pulse motor 30, which moves the photodetectors 12, 14, 16, and 40 left and right to the center of the light emitting optical fiber 42. align with the center of the seam. Therefore, the position control of the welding machine ends when the above-mentioned centers coincide, and in this state, the welding machine correctly aims at the seam.

Note that pulse motors are generally polyphase type, and can be rotated forward or reverse by changing the excitation order and the generation order of each phase pulse, so in this case, the correction direction signal is
UD is integrated with pulse PL. Further, a photodetector may be attached to the welding machine, and in this case, the motor 30 becomes a motor for adjusting the position of the welding machine.

Figure 4 shows a few examples of optical fiber bundles. a
is an example in which the optical fiber bundles 42, 44, and 46 for transmitting and receiving light are all housed in an outer sheath with a rectangular cross section, and b is an example in which the bundles of optical fibers for transmitting and receiving light are housed in an outer sheath with a circular cross section and divided into three equal parts by a line parallel to the diameter. In the example shown in FIG. In both cases, the light emitting optical fiber bundle 42 is located in the center, and the light receiving optical fiber bundles are located to the left and right of it.

As is clear from FIG. 3, the wideness or narrowness of the seam G will affect the received light output, so if the outputs of the amplifiers 18 and 20 are taken out, the wideness or narrowness of the seam can be detected, and if it is too wide, an alarm will be issued and/or The correction can be made within a predetermined width by operating the increase correction mechanism. Also, instead of shifting the welding machine to the left or right according to the left or right deviation of the seam as described above, friction rollers are placed on both sides of the steel pipe and the rollers are driven by the output of detecting the left or right deviation of the seam. It is also possible to return the seam to the center.

Effects of the Invention As explained above, according to the present invention, it is possible to detect the deviation of the seam position to the left or right, correct the welding position, and perform correct welding. Furthermore, since the above-mentioned detection is performed using an optical fiber bundle, it can be easily installed even in a narrow place, and accurate left and right deviation detection can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of a photodetector, Fig. 3 is an explanatory diagram of seam detection operation, and Fig. 4 is an explanatory diagram showing various types of optical fiber bundles. , FIG. 5 is an explanatory diagram of the steel pipe welding process, and FIG. 6 is an explanatory diagram of the forming procedure from a flat plate to a tubular shape. In the drawing, 42 is a fiber bundle for light projection, 44, 46
12 is a light receiving fiber bundle, 12 is a light source, 14 and 16 are light receivers, 10 is an object to be welded, G is a seam thereof, 18,
20, 22, 24 are amplifiers, and 30 is a motor.

Claims (1)

[Scope of Claim for Utility Model Registration] An optical fiber bundle consisting of a light-emitting optical fiber bundle in the center and light-receiving fiber bundles arranged on the left and right sides thereof;
It is equipped with a light source placed at one end of the light emitting fiber bundle, and a pair of light receivers placed at one end of the right and left light receiving fiber bundles, and the other end of the light emitting optical fiber bundle is connected to the workpiece immediately before welding. A photodetector is placed in the center of the seam, where there is still a gap, so that the other ends of the left and right light-receiving optical fiber bundles face the surfaces of the workpieces to be welded on the left and right sides of the seam, respectively. out of the projected light from the other end of the light projecting optical fiber bundle, the light of the pair of light receivers is generated by receiving the light reflected by the surfaces of the workpieces to be welded on the left and right sides of the seam, respectively. A welding stitch characterized by having an amplifier that takes a difference in output, and a motor that is driven by the output of the amplifier and that adjusts the position of the welding machine and the light emitting optical fiber bundle so that they are aimed at the seam during welding work. Eye automatic tracking device.