JPH07100177B2 - UOE steel pipe roundness straightening method and straightening device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a roundness straightening method and straightening device for a UOE steel pipe.

[Prior art and problems to be solved by the present invention]

One of the methods for forming large-diameter straight seam welded pipes is the UOE method in which a plate is bent into a U shape by a U press, then made into a tubular shape by an O press, seam welded, and then expanded by an expander to adjust the dimensions. Yes, a UOE steel pipe with high dimensional accuracy is obtained by using a mechanical expander.

However, in recent years, dimensional specifications have become stricter, and a steel pipe having excellent roundness has been demanded. Therefore, in the past, roundness was manually corrected using a simple hydraulic device offline, but the efficiency is extremely low because it is manual (15 minutes / 1 correction), and an operator for correction is required. There was a problem that the cost increased.

On the other hand, as a roundness correcting device, in Japanese Patent Laid-Open No. 54-2974,
There is disclosed a device in which a rod for moving up and down by a single hydraulic cylinder is provided with a pipe expanding wedge and a pipe contracting wedge, and the diameter of the pipe is alternately expanded and reduced to correct the roundness. This is the correction of only the pipe end of the joint pipe and the like, and the correction of the central part of the steel pipe cannot be performed, and it is not possible to cope with the roundness specification of the central part of the steel pipe which will become more and more severe in the future.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a roundness straightening method and straightening device for a UOE steel pipe that can automatically correct the roundness over the entire length of the steel pipe online.

[Means for Solving the Problems]

The roundness straightening method according to the present invention includes an inlet side stand 7 for restraining a steel pipe P by rolls arranged at intervals in the steel pipe circumferential direction on the steel pipe carry-in side of a pipe expanding head H of a pipe expander E, and The straightening roll 1 capable of rolling down the outer circumference of the steel pipe P toward the center of the steel pipe on the side opposite to the pipe expanding head H of the entry side stand 7 is provided with a straightening stand 1 provided at intervals in the steel pipe circumferential direction. Installed in the line, and while the steel pipe is restrained by the inlet side stand 7, the pipe is expanded by the pipe expanding head H, and the expanded portion is placed on the straightening stand 1 and the load applied to each straightening roll 2 Is detected, the load change of each straightening roll 2 is obtained based on each detected value, the advancing / retreating direction and the straightening reduction amount of each straightening roll 2 are determined according to this load change, and these advancing / retracting direction and the straightening reduction amount are determined. By advancing and retracting the respective straightening roll 2 based on correcting the roundness of the expanded portion, in which to carry out online over steel entire length correction of roundness with the progress of tube expansion.

The roundness correcting device according to the present invention includes an inlet side stand 7 for restraining the steel pipe P by rolls arranged at intervals in the steel pipe circumferential direction on the steel pipe carry-in side of the pipe expanding head H of the pipe expander E, and The straightening roll 2 arranged on the opposite side of the inlet side stand 7 to the pipe expanding head H and capable of rolling down the outer circumference of the steel pipe P toward the center of the steel pipe is composed of the straightening stand 1 arranged at intervals in the circumferential direction of the steel pipe. The straightening stand 1 includes an actuator 3 for moving each straightening roll 2 forward and backward with respect to the center of the steel pipe, a load detector 4 for detecting a load applied to each straightening roll 2, and each straightening roll 2
The displacement detector 5 for detecting the advancing / retreating position and the load change of each straightening roll 2 are obtained from the respective load detection values, and the advancing / retracting direction and the straightening reduction amount of each straightening roll 2 are determined according to this load change.
The controller 6 is provided for controlling the actuator 3 based on each correction reduction amount and each displacement detection value.

The actuator 3 uses a drive device such as a hydraulic cylinder or a motor cylinder that can move linearly. Load detector 4
Is a load cell or the like, and the displacement detector 5 is a potentiometer, a magnescale or the like.

[Action]

A case in which a pair of straightening rolls 2 are arranged vertically and horizontally will be described.

(I) Straightening roll load detection / roll selection Poor roundness of UOE steel pipes is classified into a horizontally long horizontal ellipse and a vertically long vertical ellipse. Table 1 shows the relationship between the horizontal ellipse and the vertical ellipse and the load change of the straightening roll 2. As an example, in the case of a horizontal ellipse, the load of the upper roll 2A becomes, the load of the lower roll 2B becomes (or), and the load of the left and right rolls 2C and 2D becomes.

These load changes are detected by each load detector 4, and the controller 6 calculates the driving direction and the straightening amount of each straightening roll and outputs the result to the actuator 3. For example, in the case of a horizontal ellipse, the upper roll 2A is raised, the lower roll 2B is lowered, and the left and right rolls 2C and 2D are moved inward to make a correction.

(Ii) Determination of Straightening (Reduction) Amount FIG. 3 shows the relationship between roundness and roll load change, and FIG. 4 shows the relationship between roundness and straightening amount. Determine the roundness correction amount [mm].

For example, the straightening roll load increases as the roundness worsens (% of roundness increases), but when the load change is 0.6 tons, the roundness becomes 1.23%, which is outside the API specification of 1%. . When the roundness reaches 1.23%, the straightening amount to keep it within 1% is obtained from Fig. 4. If a straightening (down) of 2.5 mm is applied, a steel pipe with excellent roundness can be obtained. It will be.
Further, each of the straightening rolls 2A to 2D is set in a state in which the steel pipe P is rolled down, and the roll having a reduced roll load is retracted by that amount.

The displacement detector 5 positions the straightening rolls 2A to 2D so as to form a roundness when the roll load is detected, and detects the moving stroke and performs feedback control during straightening.

Such roundness correction is continuously and automatically performed in synchronization with the tube expansion cycle. In addition, since the steel pipe is constrained by the roller-type entry side stand in front of the pipe expanding head, the center of the steel pipe and the center of the pipe expanding head are aligned. In addition, the entrance side stand serves as a fulcrum when the correction force is applied, and the portion expanded by the correction stand on the rear side of the expansion head is corrected and pressed down, and the correction is performed reliably with a large restraining force. You can

Although an example in which a pair of straightening rolls is arranged vertically and horizontally is shown above, the number of rolls may be appropriately increased or decreased depending on the accuracy of the circularity in the circumferential direction and the installation space.

〔Example〕

As shown in FIGS. 1 and 2, a pipe expanding machine E movably supports a pipe expanding head H inserted into a steel pipe P, a mandrel M that supports the head H in a cantilever manner, and a steel pipe P. It is composed of rollers R and the like, and is configured such that after the steel pipe P is expanded by a pipe expanding head H by several%, it is moved in the axial direction by a predetermined amount and expanded from the end portion to the central portion.

The straightening stand 1 and the entrance side stand 7 are arranged in such a pipe expanding line. The entrance side stand 7 is installed near the steel pipe carry-in side of the tube expansion head H, and the straightening stand 1 is installed on the opposite side of the entrance side stand 7 with a distance.

The straightening stand 1 has a pair of upper and lower rolls 2A and 2B for straightening the steel pipe P from above and below, and a pair of left and right rolls 2C and 2D for straightening the steel pipe P from the left and right, respectively, by hydraulic cylinders 3A to 3D. It is possible to move back and forth with respect to the center O.

Each of the upper and lower rolls 2A, 2B is configured by arranging a pair of left and right substantially frustoconical rolls having a pressure lower surface corresponding to the outer circumference of the steel pipe, and is attached to the slide frame 9 via a pair of left and right bearings 8. . The slide frame 9 is vertically movably supported by left and right guide posts 11 fixed to the upper frame 10A and the lower frame 10B, and attached to the upper frame 10A and the lower frame 10B by central hydraulic cylinders 3A and 3B.

The left and right rolls 2C and 2D are substantially drum-shaped horizontal rolls, which are supported horizontally by attaching the bearing member 12 to a guide member (not shown), and are supported by the hydraulic cylinders 3C and 3D on the left and right frames 10C and 10D. Mounted.

The load cell 4 is provided on the bearing 8 and the bearing member 12 of each roll 2A to 2D.
8 rolls are arranged so that the load can be detected in pairs by each roll, and the detection signal of the load cell 4 is input to the controller 6.

Each of the frames 10A to 10D is provided with a potentiometer 5 so that the displacement of the slide frame 7 or the bearing member 12 can be detected, whereby the movement amount of the rolls 2A to 2D is detected. The detection signal is input to the controller 6.

The controller 6 is programmed with the relationship between the roll load change rate and the correction amount, etc., and performs arithmetic processing on the basis of the detection signals from the load cell 4 and the potentiometer 5 to obtain a hydraulic cylinder.
Control 3A-3D.

The entrance side stand 7 has basically the same structure as the straightening stand 1, in which a pair of upper, lower, left and right rolls are arranged in the stand.
The steel pipe P is restrained by these four rolls. However, since it is not necessary to control the movement like a straightening roll, a screw jack system is used, and it is used by fixing it for each steel pipe size.

When the circularity was corrected with the stand arrangement having the above-described structure, the results shown in FIG. 5 and Table 2 were obtained.

It can be seen that the roundness is improved not only at the end of the pipe but also at the center of the pipe compared to before improvement. The straightening method before the improvement is manual straightening with a simple hydraulic device.

〔The invention's effect〕

As described above, according to the present invention, the roller type entrance side stand and the straightening stand are arranged in the pipe expanding line, and the load applied to each straightening roll is detected in the straightening stand while the steel pipe is restrained by the entrance side stand. The roundness is straightened by advancing and retracting each straightening roll according to the change, so that the roundness can be accurately detected by the straightening stand and straightening can be performed with a large restraining force, and the straightness can be maintained over the entire length of the steel pipe. The roundness can be corrected accurately, continuously and automatically. Further, since it is performed online, highly efficient correction can be performed, and an operator for offline work is not required, so that cost can be reduced.

[Brief description of drawings]

1 and 2 are a front view and a side view showing a roundness correcting device according to the present invention, FIG. 3 is a graph showing the relationship between roundness and roll load change, and FIG. 4 is a roundness. FIG. 5 is a graph showing the relationship between the degree and the correction amount, and FIG. 5 is a graph showing the roundness correction effect according to the present invention. P: Steel pipe, E: Expander, H: Expanding head, 1 ...
Straightening stand, 2 ... Straightening roll, 3 ... Hydraulic cylinder, 4 ... Load cell, 5 ... Potentiometer, 6 ...
… Controller, 7 …… entrance stand, 8 …… bearing, 9 …… slide frame, 10 …… frame, 11 …… guide post, 12 …… bearing member.

Claims (2)

[Claims] 1. An inlet side stand for restraining a steel pipe by rolls arranged at intervals in the steel pipe carry-in side of a pipe expander head of a pipe expander and a side opposite to the pipe expander head of the inlet side stand. A straightening stand in which straightening rolls capable of rolling down the outer periphery of the steel pipe toward the center of the steel pipe are arranged at intervals in the circumferential direction of the steel pipe was installed in the line of the pipe expanding machine, and the steel pipe was restrained by the inlet side stand. In the state, while performing pipe expansion by the pipe expansion head, the expanded portion is arranged on the correction stand to detect the load applied to each correction roll, and the load change of each correction roll is determined based on each detected value, Depending on this change in load, the direction of each straightening roll and the amount of straightening reduction are determined, and the straightening roll is moved forward and backward based on the direction of straightening and the straightening reduction amount to determine the trueness of the expanded portion. Correcting the degree, roundness correction method of UOE steel pipe characterized by performing the correction of roundness with the progress of the tube expansion online over steel pipe length. 2. An inlet side stand for restraining a steel pipe by rolls arranged at intervals in the steel pipe circumferential direction on a steel pipe carry-in side of a pipe expanding head of a pipe expander, and an inlet side stand on the side opposite to the pipe expanding head. The straightening rolls that are arranged and are capable of rolling down the outer circumference of the steel pipe toward the center of the steel pipe are composed of straightening stands arranged at intervals in the circumferential direction of the steel pipe. Actuator that moves forward and backward, a load detector that detects the load applied to each straightening roll, a displacement detector that detects the forward / backward position of each straightening roll, and a load change of each straightening roll from each load detection value. It is equipped with a controller that determines the forward / backward direction of each straightening roll and the straightening reduction amount according to the change, and controls the actuator based on each straightening reduction amount and each displacement detection value. A unique roundness correction device for UOE steel pipes.