JPS649887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for correcting an actual pipe diameter to a predetermined pipe diameter when manufacturing an electric arc welded pipe using a spiral method.

Spiral tubes are generally made by unwinding a coiled strip and using pinch rolls to roll it out as shown in Figures 1 and 2.
As shown in the figure, it is pressed between an inner surface forming roll 1 and outer surface forming rolls 2 and 3, and is bent into a spiral shape to form a tube, and the welding start part 4 is welded by an automatic welding machine 5 to form a continuous spiral tube. 6
It is manufactured as. The outer pressing roll 7 starts from the welding start part 4 along the outer periphery of the strip plate 8 formed into a spiral shape and presses the strip plate so as not to overlap the weld bead 9 so as to reduce the change in the outer circumferential length of the spiral tube 6. 8 is arranged so as to restrain approximately 3/4 of the tube circumference in the direction of curvature. This outer surface pressing roll 7 is attached to a frame (not shown) surrounding the spiral tube 6 so as to be movable in the radial direction. Note that the inner stand 1 is used instead of the outer press roll 7.
A method has also become common in which an inner pressing roll (not shown) is attached to the spiral tube 6 so as to be movable in the radial direction, and the spiral tube 6 is restrained from the inside thereof.

However, the outer circumferential length of the spiral tube 6 manufactured by this method is determined by the fact that the yield point of the strip plate 8, which is used even under the restraint of the outer press roll 7 or the inner press roll, is determined by changes in plate thickness or plate width. Since the circumferential length varies slightly, it is necessary to constantly monitor the circumferential length to ensure that it does not fall outside the allowable range, and to take appropriate corrective measures if the outer circumferential length falls outside the allowable range. Therefore, by forming a step in the radial direction at the welding start part 4, which is the connection part between the spiral pipe 6 side and the strip plate 8, and welding this step, the pipe diameter, that is, the outer circumference length, can be increased or decreased. This method has traditionally been used. For example, by shifting the radial positions of the inner surface forming roll 1 and outer surface forming rolls 2 and 3, or by moving only the inner surface forming roll 1 and outer surface forming rolls 2 and 3 near the welding start part 4 in the radial direction, the spiral tube 6 There is a method in which a step is formed at the welding start part 4 by changing the position of the strip plate 8 relative to the strip plate 8, and a method in which the strip plate 8 is curved to a predetermined curvature by the inner surface forming roll 1 and the outer surface forming rolls 2 and 3 and rolled up in a spiral shape. By moving the outer press roll 7 or the inner press roll that is in contact with the coming strip plate 8 in the radial direction and change the curvature of the strip plate 8 at the welding start part 4, a step is formed there. be.

However, in the former method, since the inner surface forming roll 1 and outer surface forming rolls 2 and 3 for bending the strip 8 are moved in the radial direction, a very large amount of power is required to drive them, which leads to an increase in the size of the device and a narrow space. It becomes difficult to plan automation in places.
Moreover, an inner surface stand 1 supporting the inner surface forming roll 1
0 is inserted into the inside of the spiral tube 6, so it cannot be made larger due to restrictions due to the inner diameter of the spiral tube 6, and furthermore, because it has an unstable cantilevered support form, it is susceptible to deformation due to molding loads. It is large and it is not possible to accurately correct the positional relationship. Therefore,
It is impossible to form precise steps, and a similar result can be obtained by moving the outer forming rolls 2, 3 in the radial direction. Furthermore, in this method of forming a step by moving the strip plate 8 in the radial direction, since the front part of the welding start part 4 has already been welded and is formed as a spiral tube 6 by the weld bead 9, the strip plate 8 also moves on the side of the spiral tube 6. It also moved in the radial direction, and the effect of forming the step was not very good. Furthermore, due to the above-mentioned reasons, it is necessary to stop the mill to adjust the radial position of the inner surface forming roll 1 and the outer surface forming rolls 2 and 3. There were many drawbacks and inconveniences, such as the inability to correct the diameter. On the other hand, in the latter method, since the strip plate 8 is restrained by the inner surface forming roll 1 and the outer surface forming rolls 2 and 3, in order to change the curvature at the welding start part 4, the outer surface presser roll 7 or the inner surface forming roll is A large driving force is required to move in the radial direction, and it is difficult to change the curvature itself, making it extremely difficult to effectively form a step.

The present invention eliminates the drawbacks of such conventional methods,
It is an object of the present invention to provide a method for correcting the pipe diameter of a spiral pipe, which can accurately and effectively correct the pipe diameter (outer circumference value) by forming an accurate step at the welding start part.

The structure of the method for adjusting the diameter of a spiral pipe according to the present invention that achieves this object is such that a continuous spiral pipe is manufactured by winding a strip in a spiral shape and welding the mutually adjacent edges of the strip. , A quarter of the length of each of the weld bead on the spiral pipe side starting from the welding start point and the edge on the strip plate side that forms a spiral when the strip plate is wound once. From the part corresponding to
It is characterized in that the diameter of the spiral tube is corrected by pressing in the radial direction of the spiral tube in a range of up to 2 meters on the spiral tube side in parallel with the longitudinal direction of the spiral tube. .

Hereinafter, one embodiment of the method for adjusting the diameter of a spiral pipe according to the present invention will be described in detail with reference to FIGS. 3 and 4. 12
The tube 14 is inserted between the tubes and bent into a spiral shape to form the spiral tube 14. A welding rod (not shown) is fed from the welding head 16 to the welding start part 17 through the inner stand 15 by a feeding motor (not shown) attached to one end (the right end in FIG. 3) of the inner stand 15. A group of inner rolls 12 is attached to the lower end of the inner stand 15, and can be raised and lowered by two screws 18. At the other end of this inner surface stand 15 located inside the spiral tube 14, there is an inner surface pressurizing device 19 that can press the spiral tube 14 downward.
An external pressure device 20 is installed on the foundation, sandwiching the spiral tube 14 and facing the inner surface pressure device 19, and capable of pressing the spiral tube 14 upward. These internal pressure devices 19
and the outer surface pressurizing device 20 have the same configuration,
A pressure roll 22 which contacts the spiral tube 14 is rotatably attached to the roll bracket 21. This press roll 22 is provided with a turning function that can change the rotation direction according to the forming angle (spiral pitch angle) of the strip plate 11, and the thrust generated by the deviation between the rotation direction of the spiral tube 14 and the rotation direction of the press roll 22 is It is desirable to prevent this. In this case, the pressure roll 22 of the inner surface pressure device 19 is shaped like a barrel, and the pressure roll 22 of the outer surface pressure device 20 is shaped like a barrel.
It is better to make 2 into a barrel shape. Also, the generation of thrust can be prevented by using a sphere instead of the pressing roll 22 or by pressing a plate-shaped shoe against the spiral tube 14. The roll bracket 21 supports the spiral pipe 1 by the action of a wedge 24 that slides horizontally by the operation of the lifting hydraulic cylinder 23.
Although the pressure roll 22 is attached to one end of a support rod 25 that can be moved up and down in the radial direction of the pressure roll 22, a hydraulic cylinder, a screw jack, or the like may be used directly as a means for raising and lowering the pressure roll 22. The pressing positions of the inner surface pressurizing device 19 and the outer surface pressurizing device 20 having such configurations with respect to the spiral tube 14 are within the diagonally shaded range in FIG. 5 (the range indicated by arrow A in FIG. 6) representing the principle of the present invention. ) Anywhere is fine as long as it is within ). That is, the weld bead 26 on the spiral pipe 14 side starting from the welding start part 17
And among the edges 27 on the side of the band plate 11, the edge 27 has a spiral shape when the band plate 11 is wound once.
From the parts corresponding to each quarter of the length of
The range is up to 2 meters on the spiral tube 14 side parallel to the longitudinal direction of the spiral tube 14. Note that if the contact position of the pressure roll 22 with respect to the spiral pipe 14 is too close to the welding start part 17,
The quality of the welded part deteriorates during the solidification process of the welded metal after welding, but this is because the contact area is locally elastically deformed by the pressing force of the press roll 22, and the circumferential curvature of the spiral tube 14 also changes. This is to do so. Further, in the range A in FIG. 6, a particularly large effect of the present invention can be expected in the range of plus or minus 30 degrees centered on the welding start portion 17. Furthermore, it does not matter if the opposing positions of the upper and lower press rolls 22 are shifted, and it is sufficient to have one each of the inner surface pressurizing device 19 and the outer surface pressurizing device 20, but the spiral tube 14
A plurality of units may be installed in the longitudinal direction and circumferential direction. On the other hand, as another application example of forming a step in the welding start part 17 according to the present invention, at least a pair of inner surface pressurizing devices 19 or outer surface pressurizing devices 20 are installed facing each other in the radial direction of the spiral tube 14, It is also conceivable to press the 14 tube walls in the radial direction.

When manufacturing the spiral pipe 14 according to the present invention, the strip plate 11 is first bent into a spiral shape by the inner roll 12 and the outer roll 13, and then welded by the welding head 16 at the welding start part 17. Spiral tube 14 formed in this way
Measure the outer circumference using a tape measure or outer circumference measurement device. As a result, if the outer circumference length, that is, the product of the outer diameter dimension and the circumference ratio, is larger than the target value, the pressure roll 22 of the inner surface pressure device 19 is pushed down;
This is done gradually in increments of about 0.1 mm to 0.3 mm while observing changes in the outer circumference length. In the present invention, the outer circumferential length can be reduced by 1 mm x pi, that is, about 3 mm, by pressing down by 1 mm, and the responsiveness of correction is extremely good.

For example, when reducing the pipe diameter, as shown in FIGS.
A step, ie, an offset, is formed at the joint portion of 1 (see FIG. 7a). In this state, when welding the joint between the strip plate 11 on the side sandwiched by the pressure rolls 22 and the strip plate 11 on the side sandwiched by the inner roll 12 and the outer roll 13, as shown in FIG. 7b, The outer diameter of the spiral tube 14 becomes smaller and smaller. Conversely, when the outer pressure roll 22 is pushed up, a step opposite to the above-mentioned case, that is, an offset occurs, and the outer diameter of the spiral tube 14 becomes larger and larger.

Normally, most of the cases where the initially set outer diameter of the spiral tube 14 fluctuates are due to changes in the camber or material of the strip plate 11, but in addition to this, there are also cases where the outer diameter of the spiral tube 14 changes due to the difference between the conveyance roll level and the forming level. It may also be due to the difference in level. Conventionally, if the outer circumference is about to deviate from the tolerance under such circumstances, the line is stopped, the interval between the inner roll and the outer roll 13 is changed, and the above-mentioned offset is generated to correct the outer circumference. There was no other way. However, by using the press roll 22 of the present invention, the outer circumference of the strip 11 can be forcibly changed and easily returned to the preset outer circumference, so that it is not necessary to adjust the inner roll 12 or the outer roll 13 at all. There's no need.

In addition, in FIG. 3, the change in the outer circumference length can also be estimated by measuring the step that occurs at the welding start portion 17. When the outer circumferential length of the spiral tube 14 matches the target value, the pressure roll 22 is fixed, but there is no need to use the outer surface pressurizing device 20 during this operation, and the pressure roll 22 is fixed on the spiral tube 14.
All you have to do is move it back to a position where it does not come in contact with the However, after the outer circumferential length and the target value match, it is effective to keep the press roll 22 in light contact with the spiral tube 14 to prevent subsequent changes in the outer circumferential length.
If the outer circumferential length is smaller than the target value, the outer surface pressurizing device 20 is used to carry out correction work as described above.

On the other hand, as another modification method of the present invention, each member is assembled so that the diameter of the spiral tube 14 becomes larger than the target value using only the inner surface pressure device 19, and only the inner surface pressure device 19 is used. The diameter of the spiral tube 14 is always smaller than the target value by using only the outer surface pressurizing device 20, or by assembling each member so that the diameter of the spiral tube 14 is always smaller than the target value. It is also possible to approach the target value by only using These operations can also be performed automatically using signals from the outer circumference measuring device.

As described above, according to the method for correcting the diameter of a spiral pipe of the present invention, by displacing the spirally bent strip plate and the pipe wall of the spiral pipe in the radial direction, it is possible to eliminate the influence of the inner and outer rolls. It is possible to form a step at the welding start point, and this step can be achieved with a load of about 10 to 15 tons, making it easy to downsize the device and incorporate remote equipment required to automate correction work. It's relatively easy to do.

[Brief explanation of drawings]

Fig. 1 is a working principle diagram showing the main parts of a conventional spiral pipe manufacturing device, Fig. 2 is a left side view thereof, and Fig. 3 is an embodiment of a spiral pipe diameter correction device using the present invention. Fig. 4 is a left side view, Fig. 5 is a principle drawing showing the pressurizing range of the present invention, Fig. 6 is a right side view, and Fig. 7 a and b are the pipe diameter correction process. It is a conceptual diagram of the work. In the drawing, 11 is a strip plate, 12 is an inner roll, 13
14 is an outer surface roll, 14 is a spiral tube, 15 is an inner surface stand, 16 is a welding head, 17 is a welding start part, 19 is an inner surface pressure device, 20 is an outer surface pressure device,
22 is a pressure roll, 26 is a welding bead, and 27 is an edge of the strip.

Claims (1)

[Claims] 1. When manufacturing a continuous spiral tube by winding a strip in a spiral shape and welding the mutually adjacent edges of the strip, the spiral tube side starting from the welding start point is Parallel to the longitudinal direction of the spiral tube from a portion of the weld bead and the edge on the strip plate side, each corresponding to a quarter of the length of the edge that forms a spiral when the strip plate is wound once. A method for correcting the diameter of a spiral tube, characterized in that the diameter of the spiral tube is corrected by pressing the spiral tube side in a range of up to 2 meters in the radial direction of the spiral tube. 2. The spiral tube according to claim 1, characterized in that the diameter of the spiral tube is formed in advance to be larger, and the tube diameter is adjusted while pressing the tube wall outward in the radial direction. How to correct the pipe diameter. 3. The spiral tube according to claim 1, characterized in that the diameter of the spiral tube is formed in advance to be smaller, and the tube diameter is adjusted while pressing the tube wall inward in the radial direction. How to correct the pipe diameter.