Method for improving roundness of thick steel plate pressed pipe

Abstract

The present application relates to welded pipe, especially to a method for improving the roundness of thick steel plate pressed round pipe, comprising the following steps: S1, calculating the number of pressing times; S2, setting the reference line of the second roundness correction of the steel plate according to the 90-degree, 180-degree and 270-degree points of the pipe section; S3, setting the bending action line of the steel plate on the left and right sides respectively; S4, pressing the A area and the B area into arcs; S5, using the positions of the D point, the E point and the F point in the upward deformation area of the bottom to complete the upward deformation treatment of the bottom; S6, pressing the C area and the D area into arcs; S7, pressing the pipe closed by the press machine at the 180-degree line, and then lifting; S8, turning over 90 degrees, and pressing the pipe closed by the press machine; S9, measuring the roundness, correcting, and fixing the closed mouth after passing the inspection. The present application greatly improves the one-time forming qualified rate of the roundness of the steel pipe, improves the efficiency of the second roundness correction of the steel pipe, reduces the correction times, thereby improving the process quality of the basic section steel pipe group, and reducing the processing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to welded pipe, in particular to a method for improving the roundness of thick steel plate pressed round pipe. BACKGROUND

[0002] At present, common Q355B-Z performance welded pipe is mostly made by pressing forming, which has low investment cost and considerable profit. However, the pressing forming has the following disadvantages: in the pressing process, the end part collides with the cutter head of the press machine to different degrees, resulting in different deformations, and thus the roundness of the round pipe cannot be guaranteed. In the pressing process, the following problems occur:

[0003] 1. The original basic section 355B-Z performance steel pipe has two or more uneven and uncontrollable stress areas in the last pressing area, resulting in roundness deformation;

[0004] 2. In the last correction stage, the deformation is also different due to the different stress of each bending point;

[0005] 3. Due to the circular feature, the pipe is deformed once after each correction, thereby increasing unnecessary correction cost.

[0006] The welded round pipe is mostly made by splicing several segments. Due to the difficulty in controlling the roundness of the basic section welded steel pipe, the roundness is repeatedly corrected, and the gap between the basic section and the group is increased, which undoubtedly increases the welding difficulty and seriously affects the weld and appearance quality. SUMMARY

[0007] The present application aims to solve the above technical problems, and provides a method for improving the roundness of thick steel plate pressed round pipe, reducing the correction times, improving the roundness, and improving the yield.

[0008] To solve the technical problems, the present application adopts the following technical scheme:

[0009] A method for improving the roundness of thick steel plate pressed round pipe, comprising the following steps:

[0010] S1, calculating the pressing times of one pressing

[0011] Pressing times={(R x pi+X) / 2-Z / 2-Z / 2} / Z x 2+K

[0012] Wherein: K is a fixed number, K=3; R is the diameter of the round pipe; pi is a coefficient of 3.14; X is an error value that meets the design diameter increase, X=25mm; Z is the width of the cutter head of the press machine;

[0013] S2, the 90-degree, 180-degree, 270-degree points of the circular tube section are provided with the 90-degree, 180-degree, 270-degree secondary roundness reference lines of the steel plate, which are used as secondary roundness identification points, the 180-degree line is located at the center of the width of the steel plate, and the 90-degree line, the 180-degree line and the 270-degree line divide the steel plate into A area, B area, C area and D area, the C area and the D area are respectively located on the two sides of the 180-degree line, the A area and the B area are respectively located at the two ends of the steel plate, and a bottom upward deformation area is arranged between the C area and the D area, and the bottom upward deformation area is sequentially provided with D point, E point and F point;

[0014] S3, the 90-degree, 180-degree, 270-degree points of the circular tube section are provided with the 90-degree, 180-degree, 270-degree secondary roundness reference lines of the steel plate, which are used as secondary roundness identification points, the 180-degree line is located at the center of the width of the steel plate, and the 90-degree line, the 180-degree line and the 270-degree line divide the steel plate into A area, B area, C and D area, C area and D area are respectively located on the two sides of the 180-degree line, A area and B area are respectively located at the two ends of the steel plate, and a bottom upward deformation area is arranged between the C area and the D area, and the bottom upward deformation area is sequentially provided with D point, E point and F point;

[0015] S4, the A area and the B area are pressed into arcs;

[0016] S5, the bottom upward deformation area is processed by using the positions of D point, E point and F point;

[0017] S6, the C area and the D area are pressed into arcs;

[0018] S7, the press machine is pressed downward to the 180° line, so that the steel plate is closed, and then the press machine is lifted up;

[0019] S8, the 90-degree is turned over, the press machine is pressed downward to make the pipe closed;

[0020] S9, the roundness is measured, and the parts exceeding the difference greater than the drawing and the specification are corrected, and then the closed mouth is fixed.

[0021] The technical scheme of the present application has the beneficial effects compared with the prior art:

[0022] The present application can greatly improve the one-time forming qualified rate of the roundness of the steel pipe, improve the roundness, improve the secondary roundness efficiency of the steel pipe, reduce the correction times, thereby improve the process quality of the basic section steel pipe group, improve the yield, and reduce the processing cost of the steel pipe.

[0023] Further, the optimization scheme of the present application is:

[0024] The width of the bottom upward deformation area is adapted to the width of the press machine cutter head, D point and F point correspond to the outer edge line of the press machine cutter head respectively, and E point corresponds to the center line of the press machine cutter head. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The present application is a schematic diagram of the round pipe forming.

[0026] In the figure: steel plate 1. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] See Figure 1 In this embodiment, a hospital project in a certain area is used. A 40mm thick steel plate 1 is pressed into a 500mm diameter round pipe. The material of the steel plate 1 is Q355B.

[0029] A method for improving the roundness of pressed round tubes made from thick steel plates is carried out according to the following steps:

[0030] S1. Calculate the number of compressions per press.

[0031] Number of suppressions = {(R×π+X) / 2-Z / 2-Z / 2} / Z×2+K

[0032] ={(500mm×3.14+25mm) / 2-50 / 2mm-50 / 2mm} / 50mm×2+3

[0033] =30+3=33

[0034] Where: K is the fixed number of times, taken as K=3, once on each side of the starting and ending point of the closed steel plate at Z / 2, and once at the bottom upward deformation zone at 180°; R is the diameter of the round tube, R is 500 mm; π is taken as a coefficient of 3.14; X is the error value to meet the increase in design diameter, taken as 25 mm; Z is the width of the press head, the width of the press head is 50 mm, the number of pressing times on the left and right sides of the steel plate 1 is equal, so that the unavoidable error is evenly distributed;

[0035] S2. Set the bending point action lines at 90°, 180°, and 270° of the steel plate 1 according to the 90°, 180°, and 270° points of the circular tube cross section. These lines are used as identification points for secondary roundness correction. The 180° line is located at the center of the width of the steel plate 1. The 90°, 180°, and 270° lines divide the steel plate 1 into areas A, B, C, and D. Areas C and D are located on both sides of the 180° line, and areas A and B are located at both ends of the steel plate 1. A bottom-up deformation zone is set between areas C and D. Points D, E, and F are set in sequence in the bottom-up deformation zone.

[0036] S3. Starting from 1 / 2 of the width of the press cutter head at the end of the steel plate 1, and ending at 1 / 2 of the width of the press cutter head in the transverse center line of the steel plate 1, that is, extending the end of the steel plate 1 inward to 1 / 2 of the width of the press cutter head, the bending action lines of the steel plate 1 are evenly set on the left and right sides respectively.

[0037] S4. Press areas A and B into arcs, with 180° as the center line. Press the left and right sides an equal number of times to distribute the unavoidable error evenly. Use four points as adjustment points.

[0038] S5. The bottom upward deformation zone is processed by using the positions of points D, E and F. The width of the bottom upward deformation zone is adapted to the width of the press head. Points D and F correspond to the outer edge of the press head, and point E corresponds to the center line of the press head. The bottom upward deformation zone makes the two ends of the steel plate 1 and the mold head act with equal forces and cancel each other out, so that no other areas are deformed.

[0039] S6. Press areas C and D into an arc;

[0040] S7. Press down 180° on the press line to close the steel plate 1, then lift it up.

[0041] S8. Rotate 90 degrees and press down to close the pipe fitting;

[0042] S9. Measure the roundness, correct any parts that exceed the requirements of the drawings and specifications, and fix the closed end after it is qualified.

[0043] This embodiment is mainly applicable to Q355B steel plates. If other steel plates are used, the degree of deformation under stress will be different due to different yield strengths, so the bottom anti-deformation height needs to be increased appropriately. The number of pressing times should be an integer value, and the width of the press head after pressing should be avoided from overlapping with the previous one.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent structural changes made based on the description and drawings of the present invention are included within the scope of the present invention.

Claims

1. A method for improving the roundness of pressed round tubes made from thick steel plates, comprising the following steps: S1. Calculate the number of compressions per press. Number of suppressions = {(R×π+X) / 2-Z / 2-Z / 2} / Z×2+K in: K is the fixed number of press cycles, taken as K=3; R is the diameter of the circular tube; π is a coefficient of 3.14; X is the error value to meet the increase in the design diameter, taken as 25mm; Z is the width of the press cutter head, and the number of pressing cycles is taken as an integer value; S2. Set secondary rounding reference lines at 90°, 180°, and 270° points on the cross-section of the circular tube for the steel plate. These lines are used as identification points for secondary rounding. The 180° line is located at the center of the steel plate width. The 90°, 180°, and 270° lines divide the steel plate into areas A, B, C, and D. Areas C and D are located on both sides of the 180° line, and areas A and B are located at both ends of the steel plate. A bottom-up deformation zone is set between areas C and D. The width of the bottom-up deformation zone is adapted to the width of the press cutter head. Points D and F correspond to the outer edge of the press cutter head, and point E corresponds to the center line of the press cutter head. S3. Starting from 1 / 2 of the width of the press cutter head at the end of the steel plate, and ending at 1 / 2 of the width of the press cutter head on the inner side of the transverse center line of the steel plate, the bending action lines of the steel plate are evenly set on the left and right sides respectively. S4. Press areas A and B into an arc; S5. Use the positions of points D, E and F to complete the upward deformation of the bottom area; S6. Press areas C and D into an arc; S7. Press down 180° on the line to close the steel plate, then lift it up. S8. Rotate 90 degrees and press down to close the pipe fitting; S9. Measure the roundness, correct any parts that exceed the requirements of the drawings and specifications, and fix the closed end after it is qualified.

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