JPH01306018A - Method for straightening out-of-roundness and bend and tube expanding machine for its use - Google Patents

Abstract

PURPOSE:To improve straightening accuracy and to reduce a cost of equipment by equipping a frame backward a pipe expanding head, disposing plural blocks capable of stretching on its opening and stretching the blocks existing in a specified range to perform the straightening. CONSTITUTION:The frame 9 is provided in the rear of the pipe expanding head 1, outside the pipe 2 to be worked and on its central opening, plural flexible radial blocks 5a-5h are disposed in the radial direction. In this case, each block is formed of the material causing no flaw if it is brought into contact with the pipe 2. For the camber of the pipe 2 to be worked, the blocks 5a-5c existing in the range of 90-180 deg. are stretched, the remains are shrinked to control the height, then, the pipe 2 is horizontally fed successively to straight. Because plural blocks are used, a positive straightening of the bend is performed through small contact surface pressure. Therefore, the straightening accuracy is improved and the cost of equipment is reduced by simplifying the mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for simultaneously correcting the 11 roundness and bending of a UOjlJ pipe when expanding the pipe, and a pipe expanding machine used therefor.

(Prior Art) Straight seam welded steel pipes such as 00M pipes tend to bend in the longitudinal direction of the steel pipe due to residual stress during forming into a steel pipe due to uneven thickness of the steel plate used as a raw material, thermal distortion during straight seam welding, and the like.

Conventionally, as a method to correct this bend in a steel pipe, a uniform straightening pressure in the radial direction is applied from inside the pipe to a predetermined length of the steel pipe during the tube expansion process, which is the final process of UOa pipe forming. Expand that section, and when that is finished, send the steel pipe and expand the next predetermined length section.The process is repeated to expand the entire pipe, and at the same time, the roundness is corrected by expansion, and at the same time, the steel pipe is bent. He also took corrective measures.

To explain this method in detail with reference to FIG. 3, by expanding the tube with the tube expansion head 1 crossed at an appropriate angle to the axis of the tube 2 to be processed, the roundness can be corrected. For example, in the case of a warp (a shape in which the bend is convex downward in the figure), the tube to be processed 2 is tilted (l) with respect to the tube expansion head l as shown in the figure. In this state, expand the tube expansion head I as shown by the dotted line.

Then it's the tube expansion head! The two corners of ffi<Ia
.

! b is strong (hits the inner surface of the steel pipe and tries to rotate the pipe to be processed 2 counterclockwise in the figure, but by receiving this reaction force with the gripping part 3a of the steel pipe feeding device 3, the pipe to be processed does not bend. A bending moment in the opposite direction is applied, and as a result, the tube is expanded, that is, the bending is corrected while the roundness is corrected. In the figure, It is a boom.

If the tube to be processed is downwardly curved, it can be corrected in the reverse manner to the above, and if it is curved to the left or right, it can be corrected in the same manner.

(Problem to be solved by the invention) However, in recent years, the required quality of UO steel pipes has become gradually stricter.
The conventional methods described above are no longer able to produce steel pipes that satisfy the required roundness and bending tolerances.

In order to satisfy this required quality, for example,
Publication No. 99522 discloses a counterproposal as shown in FIG. That is, in this method, pressure rolls 48 to 4d are arranged in the longitudinal direction of the pipe to be processed after the tube expansion head I is inserted outside the pipe to be processed 2, and the pressure rolls are pushed in at the same time as the pipe is expanded by expansion of the pipe expansion head I. This method attempts to forcibly apply a bending moment to the pipe to be processed, thereby correcting the roundness by expanding the pipe and simultaneously correcting the bend.

With this method, the effect of straightening bends is superior to that of the method explained in Fig. 3.However, during straightening, the contact surface pressure between the tube to be processed and the presser roll increases, so the wall thickness of the tube to be processed increases. If the pressure roll is thin, there is a problem in that the contact area of the presser roll of the pipe to be processed is locally depressed and deformed, deteriorating the roundness. Since the device requires a function to push the device into the device, the device becomes large and expensive, which leaves the problem that it cannot be said to be fully satisfactory.

The present invention has been made to solve these problems.

(Means for Solving the Problems) The present invention provides a straightening method and a pipe expanding machine that ensure higher roundness and higher surface accuracy than ever before in the above-mentioned mechanical expansion method. , its feature is that it uses a tube expander with a frame in which a plurality of blocks that can be expanded and contracted in a radial manner surrounding the tube to be processed are arranged outside the tube to be processed at the rear of the tube expansion head. Among them, select a plurality of blocks within a 90° to 180° angle range located on the same side as the bending direction of the pipe to be processed before expansion, apply them to the outer surface of the pipe to be processed, and connect the head with these blocks. The purpose is to expand the tube and straighten the bend at the same time through the interaction of the two.

(for production) The operation of the present invention will be explained with reference to FIG.

In Figure 1, (a) is a longitudinal cross-sectional view in the long plane direction, (
b) is a Δ-Δ arrow-view diagram of (a).

Here is the tube expansion head! Blocks 5a to 51+ are mounted at 45 inside the frame 9 provided on the outside of the pipe to be processed 2.
An example will be shown in which 8 blocks are installed in a pit, and 3 blocks out of the 8 blocks are protruded according to the bending direction of the pipe 2 to be processed, and each block is adjusted to an appropriate height to straighten the pipe to be processed.

In the following, we will discuss the case where the pipe to be processed is upwardly curved. In this case, the knocks 53 to 5c are pushed out, and the other 5 blocks are retracted.

The height of the three blocks 58 to 5c is adjusted according to the amount of -L warpage of the pipe to be processed, and each block is held at an appropriate position. On the other hand, the tubes to be processed are fed into the tube in a horizontal state so as to enclose the tube expansion head one after another, but the axis of the tube to be processed is lower than the axis of the tube expansion head, and in this state, the normal Perform tube expansion.

During tube expansion, the tube to be processed tends to remain bent in the two warp directions, but since it is held down from the outside by the three blocks 5a to 5C, the tube expansion head is used as a fulcrum to hold these blocks together. 53 to 5C and the gripping part 3a of the steel pipe feeder 3, a bending moment in the opposite direction to the bending is applied, and the pipe to be processed is bent as shown by the dotted line 2° when the head has finished expanding. and the upward curvature is corrected.

At this time, the blocks are those in the 90° to 180° angle range (5a to 5a) located on the same side as the bending direction of the steel pipe.
5c) presses the outer surface of the steel pipe at the same time, and the direct surface pressure is dispersed, so unlike the method shown in Fig. It is possible to avoid X conversion by 2y.

Hereinafter, the case where the pipe to be processed is upwardly curved has been explained as an example, but if it is downwardly curved, a block of 50 to 5 g is brought into contact with the tube, and the others are retracted. In addition, in the case of left or right curvature,
Blocks 5C to 5e, 5g, 5h, and 5a may be brought into contact with the outer surface of the pipe to be processed, respectively, on the same mallet.

(Example) Embodiments of the present invention will be described with reference to FIGS. 1 and 2.

explain.

As mentioned above, 9 is a frame installed outside the tube to be processed 2 at the rear of the tube expansion head 1, and the center thereof has a circular opening 12 through which the tube to be processed 2 can pass. Eight blocks 5a to 5h radially extending from the inner circumferential surface of the opening 12 toward the center thereof are provided at a pitch of 45° so that the height can be adjusted.

To further explain the structure of this block with reference to FIG. 2, each block is guided and supported by a fixed wedge 15 welded and fixed to the inner peripheral surface of the frame, and by an 'r-shaped guide 17 with respect to the wedge I5. (Multi-moving wedge 14, this moving wedge I4
It consists of a block body 13 attached with bolts to the block body 13, and a screw I6 that connects both wedges I4 and 15 and adjusts the height.

This block body 13 is made of MC nylon or other material that will not cause scratches when it comes into contact with and presses the outer surface of the pipe to be processed. In addition, although the wedge method was used to adjust the height in this example, it is possible to prepare light liners of various thicknesses and insert the liners between the block body 13 and the movable wedge 14 to adjust the height. You may also do so. Furthermore, it is possible to move the wedge, mark, and adjust the height of the block by using a cylinder actuation method or an electric method instead of using a screw method, so that the structure can be remotely controlled.

In this example, the number of correction blocks installed is eight, but the number is not limited to eight. 90° to 180° located on the same side as the bending direction of the pipe to be processed with respect to the outer surface of the pipe to be processed
As long as the blocks can be arranged so that two or more blocks can be brought into contact with each other at the same time within a range of 8 degrees, fewer or more blocks can be arranged depending on the eight prongs.

Further, if the blocks are structured to be rotatable in the circumferential direction within the frame, it is possible to minimize the number of blocks to be installed.

Next, an example of implementation in which the present invention is applied will be shown in comparison with a case in which the above-mentioned conventional technology (FIGS. 3 and 4) is applied.

The table below shows the case of straightening according to the present invention and the case of straightening using only a conventional mechanical expander (third example).
Fig. 4 shows the results of roundness and bending δ)11 in the case of correction according to the counter plan (Fig. 4).

The tube expansion conditions are as follows.

(1) Outer diameter of the pipe to be processed: 40cm (1016mm) (i
i) tt Wall thickness: 25.4mm (…) “
Length: I20001N+6 (!V) // Material: Carbon j14j14 tube (yield point 60Kg/a11'') (v)
Tube expansion rate: 1.3% 1) ma++ Dmin (Note 1) Roundness Δ-X100 (%) N D) J: Nominal diameter DayuX: Actual maximum diameter after pipe expansion 1) sin: Minimum of N 1B diameter (see Figure 5) (Note 2) Bend n (Reference to 61st threshold) (Note 3) The use of blocks in the method of the present invention requires three blocks within a 90° range depending on the bending direction of the pipe to be processed. I chose and went.

In the method shown in FIG. 3, the straightening effect is insufficient, resulting in poor roundness and bending.

In the method shown in Fig. 4, the bending is actively corrected, so there are fewer bends, but due to the high contact surface pressure of the presser foot [J-ru] to the pipe to be processed, local depressions and deformations occur. J!
The endothelium is further deteriorated.

In the present invention, both the roundness and bending of the machine L are significantly improved.

(Effects of the Invention) According to the present invention, the following unique and remarkable effects can be obtained.

(1) Since a plurality of blocks within the range of 90° to 180° are brought into contact with the outer surface of the pipe to be processed, the contact surface pressure can be reduced, and the roundness can be maintained (i.e., local depressions, (no deformation), active bending correction is possible, and as a result, steel pipes with high roundness and bending accuracy can be obtained.

(2) From the perspective of the device, the structure is simple, so it has the advantage of being less likely to break down and being inexpensive.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the operation of the present invention, (a) is a longitudinal cross-sectional view, (b) is a front view taken along the line A-Δ of (a), and Fig. 2 is an example of a correction block. (a) is a vertical sectional view, (b) is a front view taken along the line B-B, FIGS. 3 and 4 are explanatory diagrams of conventional correction methods, and FIG. 5 is a diagram showing roundness. FIG. 6 is an explanatory diagram of bending. In the figure, 1... Pipe expansion head, 2... Tube to be processed, 3... Steel pipe feeding device, 5a to 5h... Block, 9... Frame.

Claims (2)

[Claims] (1) After applying uniform straightening pressure in the radial direction from inside the pipe to a predetermined length of the pipe to be processed and completing the expansion of that part, send the pipe to be processed to the next predetermined length. In a mechanical expander that repeatedly expands a section and expands the tube by a predetermined length, a block that can be expanded and contracted in the radial direction is placed radially on the outside of the tube to be processed behind the tube expansion head. When expanding a tube with poor roundness and bends in the length direction using a tube expander having a plurality of frames, among the plurality of blocks,
90° to 18 located on the same side as the bending direction of the pipe to be processed
A plurality of blocks in the 0° angle range are stretched in the opposite direction to the bending of the pipe to be processed and fixed against the outer surface of the pipe to be processed,
The other blocks are kept in a contracted state, and the roundness and bending of the tube are corrected by the interaction between the head during tube expansion and the block applied to the outer surface of the tube to be processed. Curved correction method. (2) After applying uniform straightening pressure in the radial direction from inside the pipe to a predetermined length of the pipe to be processed and completing the expansion of that part, send the pipe to be processed to the next predetermined length. In a mechanical expander that repeatedly expands a section and expands the tube by a predetermined length, a plurality of blocks are placed radially outside the tube to be processed behind the tube expansion head and can be expanded and contracted in the radial direction. A pipe expanding machine for correcting the roundness and bending of pipes, characterized by the installation of individually arranged frames.