JPS5930512B2 - Welding torch turning mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating mechanism for a welding torch in an automatic welding line for continuously welding materials to be welded having a corrugated portion in a welding joint.

Membrane type LNG tanks have a heat insulating layer on the inside of the tank body made of concrete or thick steel plates, and a thin plate membrane made of a material with excellent low-temperature properties is provided on the entire surface of the inner surface.

When storing LNG, the membrane is exposed to extremely low temperatures of -162°C, and when empty it reaches room temperature, subjecting it to extremely large temperature changes. Therefore, the membrane is provided with corrugated expansion and contraction wrinkles in a lattice shape at appropriate intervals to prevent excessive thermal stress. This is done in such a way that it does not occur. TIG welding (TIG) is used to weld thin plate members such as membranes.
Tungsten inert gas welding) or plasma welding methods are applied, but these welding methods require stabilizing the welding arc to maintain a constant bead shape and ensuring the appearance, quality, and weld strength of the welded part. It is desirable that the torch always maintain a certain angle with respect to the direction of the welding line (in the case of welding a corrugated part, the direction of the cut line at the welding point). When welding flat plates, it is sufficient to move the torch while fixing it at a certain angle, but when welding a workpiece that has a corrugated part, such as a membrane, continuously through the flat part and the corrugated part, In order to maintain the above-mentioned angle, when welding the corrugated portion, it is necessary to move and rotate the welding torch in accordance with the shape of the material to be welded. In the case of membranes that are currently being manufactured,
The direction of the perpendicular to the material to be welded in the corrugated portion extends within a range of approximately ±700 with respect to the perpendicular direction to the flat portion. The operating characteristics of the torch rotation mechanism are such that the center of rotation is the arc generation point, and this point moves in accordance with the waveform of the material to be welded, while maintaining a constant angle with respect to the tangential direction of the waveform. It is desirable to have the following characteristics. However, rotating the torch around the tangential arc generation point while maintaining a constant angle to the welding line means aligning the pivot axis with the surface of the material to be welded. Direct rotation is not possible. Therefore, the most common method of rotating the torch that has been implemented in the past is to provide an arcuate rail on the torch gripping part, and use a rack pinion method etc. to rotate the gripping part while always pointing the torch toward the center of the arc. A device that moves along an arc is known.

However, with this method, unless the turning angle is small, in order to turn the torch over a wide range of approximately +70 degrees from the reference position as described above, a very large arcuate rail is required, and the wave shape of the material to be welded is required. In some cases, when welding a flat part close to a corrugated part, the arcuate rail may come into contact with the corrugated part of the material to be welded, making welding impossible. To solve this problem, some systems have divided the rail into several parts, stacked on top of each other, and let the rails out as needed.However, the mechanism and its control become extremely complex, increasing the size of the equipment, increasing costs, and reducing human reliability. There are drawbacks that lead to Another method is to shift the center of rotation of the torch from the arc generation point so that the swivel device does not come into contact with the material being touched, but this is because rotating the torch moves the arc generation point back and forth. , the moving speed and direction of the trolley are adjusted to compensate for this difference, and the landing is performed.

In this case, it is necessary to change the speed and direction of movement of the heavy truck and the entire device mounted on it to follow the rotation of the torch, and a control device is required to maintain the positional accuracy of the arc generation point. It has the disadvantage of being complicated. The present invention provides a torch rotation mechanism for an automatic welding machine that eliminates the above-mentioned drawbacks of the conventional torch rotation mechanism and has a simple structure for continuously welding a thin plate such as a membrane having a corrugated portion in a welding joint. The purpose is to Hereinafter, the present invention will be explained in detail based on drawings showing embodiments.

As shown in Fig. 1, lap joints are usually used for joints of materials to be welded 1 having corrugated portions in weld joints 2, and when welding such lap joints, as shown in Fig. 2. If welding is performed by tilting the torch 3 by a slight angle θ1 from a perpendicular line on the welded material 1 in a plane perpendicular to the tangent line (in the paper of Fig. 2), a uniform bead can be obtained. It has become common knowledge that this happens. The above angle θ1 is a force ζ which is usually about 200, and there is no practical problem even if this angle changes by ±10. As mentioned above, it is desirable to always keep the angle between the force direction of the tangential line and the torch constant.

An embodiment of the present invention will be described with reference to FIGS. 3 and 4. The welding machine main body 12 is supported on a traveling truck 11, and the truck 11 is used to move horizontally placed materials to be welded. It is movable along a linear guide rail 13 that is installed horizontally at a constant distance from the flat surface of 1. Welding machine body 12
A sliding portion 8b of the bracket 8 is attached to the bracket 8 so as to be slidable in the vertical direction. The slidable range is set to be greater than or equal to the maximum amount of protrusion of the corrugated portion of the material to be welded 1 from the flat surface.
A rotating means attachment part 8a is fixed to the lower end of the sliding part 8b. A torch rotation drive motor 6 is attached to the rotation means attachment part 8a.
And a bearing 7 for the torch pivot shaft 5 is fixed. A speed reducer 10 and a drive transmission belt 9 are interposed between the 5 drive motor 6 and the pivot shaft 5.

A welding torch support 4 is fixed to the flat front end of the pivot shaft 5. The contact torch 3 is sandwiched between the main body 4b of the support 4 and the holding member 4a. Two sensors 14a and 14b are attached to the lower end of the support body 4b at appropriate intervals in the front-rear direction for detecting the relative position of the tip of the torch with respect to the surface of the workpiece and the angle of the torch. As explained in FIG. 2, the welding torch 3 is installed in a plane perpendicular to the direction of the welding line and inclined at an angle θ1 with respect to the vertical line (the sliding direction of the bracket 8), and is tilted in the direction of the welding line. On the other hand, as shown in the side view on the left side of Figure 4,
In this embodiment, it is perpendicular to the surface of the material to be welded. That is, the forward inclination angle in this case is 00. The center line of the pivot shaft 5 lies in a plane perpendicular to the moving direction of the truck 11 (i.e.
3), its extension line passes through the welding arc generation point 15 located at a point extending from the tip of the torch 3 by the welding arc length, and the rotating member such as the bearing 7 Angle θ2 greater than the angle that does not interfere with the surface of the welded material 1
It is provided so as to be inclined with respect to the surface of the material to be contacted.
This angle θ2 does not necessarily have to match the inclination angle θ1 of the torch, but if they match, the torch 3
and the pivot axis 5 are perpendicular to each other, which is convenient for processing and installation work. Since this device is constructed as described above, when welding the flat part of the material 1 to be welded, the torch 3 is supported by the support member 4 so that its tip is at the welding point B, as shown on the left side of FIG. The carriage 11 is held vertically at a constant interval.
Welding is performed while moving along the guide rail 13. As the welding progresses and the welding point reaches the corrugated portion C of the welded material 1 and the weld line begins to rise, the sensors 14a and 14b detect that the tip of the torch 3 has come too close to the welded material 1. It is detected that the forward inclination angle with respect to the tangent line has increased, and a control device (not shown) causes the sliding part 8b of the bracket 8 to slide on the upper blade, and rotates the swing 1 drive motor 6 to rotate the torch 3. The torch is rotated and moved along the guide rail 13 while correcting the distance and forward inclination angle between the tip of the torch and the workpiece to reference values.

When the waveform portion C is brought into contact in this way, as shown on the right side of FIG. It tilts to the right and becomes vertical when it reaches the flat surface, making it possible to perform continuous welding while always maintaining a predetermined gap and forward inclination angle at the tip of the torch. There is a known control means that uses two sensors arranged in the direction of travel to detect the relative distance and relative angle between the member to which they are attached and the opposing member, and maintains these reference values by feedback. Although the description will be omitted, it is possible to use a combination of a mechanical sensor and a microswitch, an electrical sensor, a change in arc voltage, etc. as the sensor.

In this device, the extension line of the center line of the torch rotation shaft 5 is provided so as to pass through the welding arc generation point, so when the torch 3 is rotated when welding a corrugated part, the torch 3 will not touch the welding arc. It rotates around the arc generation point 15, and there is no secondary back-and-forth movement due to the rotation due to the arc generation. Therefore, changing the moving speed and moving direction of the trolley to correct this becomes unnecessary, and the control device becomes simpler. In addition, since the pivot shaft 5 is inclined at an angle greater than the angle that prevents components of the pivot mechanism, such as the bearing 7, from interfering with the surface of the workpiece 1, the pivot mechanism does not come into contact with the workpiece. There is no possibility that welding will become impossible.

This inclination angle θ2 is 100 to 20, as shown in FIG.
About 0 is sufficient. Since the pivot shaft 5 is tilted, when the torch 3 is tilted back and forth by rotating the shaft, the tilt angle of the torch 3 in the plane perpendicular to the welding line (θ1 in Figures 2 and 3) is strictly In other words, it changes slightly. but,
As mentioned above, this angle may vary within a considerable range without causing any practical problems. In the above description of the embodiment, a description has been given of a torch rotation mechanism for automatically welding a workpiece having a flat part and a corrugated part arranged horizontally, but as is clear from the above description, the present invention It can also be applied to welding materials to be welded where only the waveform is continuous, and to welding horizontal or vertical weld lines when the materials to be welded are arranged vertically.

As described above, by using the present invention, it is possible to rotate the welding torch around the welding arc generation point with a relatively simple mechanism and control, thereby simplifying the carriage movement and the torch rotation mechanism. This makes it possible to make the welding device more compact and to simplify the control circuit, which has a significant effect on simplifying the entire welding device and reducing costs.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a joint of materials to be welded having a corrugated portion on the rear welding joint, Fig. 2 is an enlarged cross-sectional view of part A in Fig. 1 and a diagram showing a state in which it is in contact, and Fig. 3 is a perspective view showing a joint of materials to be welded having a corrugated portion on the rear welding joint. FIG. 4 is a front view showing an embodiment of the torch turning mechanism, and FIG. 4 is a side view showing the state when the plane part and the corrugated part are in contact with each other. 1... Material to be welded, 2... Raku-joint, 3
・・・． . . . Contact torch, 5 . . . Torch rotation axis, 6 . . . Swivel drive motor, 8 . . . Sliding bracket, 11 . 12...
... Welding machine main body, 13 ... Guide rail, 14a
, 14b...-sensor, 15... arc generation point.

Claims (1)

[Claims] 1 The welding joint has a corrugated part in the direction perpendicular to the welding material.It is carried on a traveling trolley that moves on a linear guide rail provided parallel to the average plane of the welding material, and the direction of the welding line and the welding torch are In the welding torch rotation mechanism of an automatic welding machine that performs welding while always maintaining a constant relative angle, there is a holding member that is movable in the vertical direction with respect to the welding machine body, and a rotating means at the lower end of the holding member that can be rotated. The center line of the attached rotating shaft lies within a plane perpendicular to the direction of carriage movement, its extension line approximately passes through the welding arc generation point, and at least the rotating means component does not interfere with the surface of the material to be welded. a welding torch support member that is fixed to the pivot axis and holds the welding torch so that the tip of the welding torch points toward the welding line; and a means for detecting a relative angle between the welding line and the torch, and a means for detecting a relative angle between the welding line and the torch, and displacing the holding member in the vertical direction based on a detection signal from the gap detecting means. It is characterized by having a control means for controlling the above-mentioned turning shaft to be controlled in response to a detection signal so as to maintain the gap between the workpiece to be welded and the tip of the welding torch and the relative angle between the welding line and the welding torch within a predetermined range. Swivel mechanism of welding torch.