Pipe end straightening device and method

Abstract

The present application relates to a straight seam submerged arc welded pipe manufacturing technology field, especially to a pipe end shape correcting device and method, aiming at solving the problem of large workload and low correction efficiency of artificial correction mode. The pipe end shape correcting device provided by the present application comprises a correction mechanism, an adjusting mechanism and a walking mechanism; the correction mechanism comprises a bidirectional telescopic rod and a top block, the midpoint of the bidirectional telescopic rod is hinged to the adjusting mechanism, the adjusting mechanism is connected with the walking mechanism, and the walking mechanism can move along the length direction of the steel pipe; two top blocks are respectively connected with the two ends of the bidirectional telescopic rod, and the bidirectional telescopic rod drives the two top blocks to move synchronously and move away from each other. The bidirectional telescopic rod of the present application keeps its own axis perpendicular to the axis of the steel pipe through the hinged mode, pushes the top block by using the bidirectional telescopic rod to spread the inner diameter of the pipe end, increases the size of the short axis direction of the pipe end ellipse, improves the roundness of the pipe end, simultaneously drives the top block to align with the pipe end plane by the walking mechanism, improves the operation efficiency and reduces the working strength.

Description

Technical Field

[0001] This invention relates to the field of straight seam submerged arc welded pipe manufacturing technology, and in particular to a pipe end straightening device and method. Background Technology

[0002] The production of straight seam submerged arc welded steel pipes requires strict control over the pipe's dimensions, especially at both ends. During production, variations in process parameters, different batches of raw steel plates, and different molds can all cause variations in the roundness of the pipe ends. Currently, correcting the pipe ends is an effective way to ensure roundness. However, the existing method of manually correcting the pipe ends using jacks is both labor-intensive for employees and inefficient, failing to meet the overall production line's pace. Summary of the Invention

[0003] The purpose of this invention is to provide a pipe end alignment device and method to solve the problems of high workload and low alignment efficiency of manual alignment.

[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0005] A pipe end straightening device includes a straightening mechanism, an adjusting mechanism, and a traveling mechanism; the straightening mechanism includes a bidirectional telescopic rod and top blocks, the midpoint of the bidirectional telescopic rod is hinged to the adjusting mechanism, the adjusting mechanism is connected to the traveling mechanism, and the traveling mechanism is capable of moving along the length of the steel pipe; the two top blocks are respectively connected to the two ends of the bidirectional telescopic rod, and the bidirectional telescopic rod drives the two top blocks to move synchronously and move away from each other.

[0006] Furthermore, the adjustment mechanism includes a transverse connecting rod and a slider, one end of the transverse connecting rod being hinged to the midpoint of the bidirectional telescopic rod, and the other end being connected to the slider;

[0007] The slider can move vertically.

[0008] Furthermore, the adjustment mechanism also includes a lead screw, which is vertically arranged and rotatably mounted on the traveling mechanism. The slider is threadedly connected to the lead screw, and the lead screw rotates around its own axis to drive the slider to move.

[0009] Furthermore, the tube end straightening device also includes a guide rod, which is vertically arranged and inserted into the slider.

[0010] Furthermore, the walking mechanism includes a frame and wheels, the wheels being mounted on the frame, and the guide rod and the lead screw being mounted on the frame;

[0011] The wheels rotate to move the vehicle frame.

[0012] Furthermore, the walking mechanism also includes a walking track, along which the walking wheels roll.

[0013] Furthermore, the bidirectional telescopic rod is configured as a double-acting hydraulic cylinder, comprising two extension rods and a cylinder body, wherein the two extension rods are respectively inserted into the two cylinder barrels of the cylinder body;

[0014] The two extension rods are respectively connected to the two top blocks, which are used to drive the two top blocks to move synchronously in opposite directions to press against the inner wall of the steel pipe.

[0015] Furthermore, the pipe end straightening device also includes a hydraulic system, which supplies fluid to the cylinder to push the two extension rods to extend synchronously, thereby causing the two top blocks to press against the inner wall of the steel pipe.

[0016] Furthermore, the hydraulic system includes a piston pump, a first check valve, a directional valve, a stacked hydraulic control check valve, a first one-way speed control valve, a self-adjusting synchronizing valve, a second one-way speed control valve, and an oil tank.

[0017] The extension rod divides the cylinder into a first chamber and a second chamber. When the extension rod extends, oil flows from the oil tank through the plunger pump, the first one-way valve, the reversing valve, the stacked hydraulic control one-way valve, the first one-way speed control valve, and the self-adjusting synchronizing valve into the first chamber, thereby pushing the extension rod to extend and compressing the second chamber. The oil in the second chamber flows through the second one-way speed control valve, the stacked hydraulic control one-way valve, and the reversing valve in sequence before returning to the oil tank.

[0018] When the extension rod retracts, the oil flows from the oil tank through the plunger pump, the first one-way valve, the reversing valve, the stacked hydraulic check valve, and the second one-way speed control valve in sequence before entering the second chamber, thereby pushing the extension rod to retract and compressing the first chamber; the oil in the first chamber flows through the self-adjusting synchronization valve, the first one-way speed control valve, the stacked hydraulic check valve, and the reversing valve in sequence before returning to the oil tank;

[0019] The first one-way speed control valve is used to control the flow rate of oil flowing out of the first chamber, and the second one-way speed control valve is used to control the flow rate of oil flowing out of the second chamber.

[0020] In another aspect, the present invention provides a pipe end straightening method, employing the aforementioned pipe end straightening device, comprising the following steps:

[0021] The bidirectional telescopic rod remains vertical under the action of gravity, and the steel pipe is rotated to make the minor axis of the ellipse at the end of the steel pipe vertical;

[0022] During calibration, the walking mechanism moves along the length of the steel pipe to align the top block with the end of the steel pipe. Then, the bidirectional telescopic rod extends to drive the two top blocks to move synchronously. The two top blocks move away from each other and abut against the inner wall of the steel pipe to increase the diameter of the end of the steel pipe along the minor axis of the ellipse.

[0023] In summary, the technical effects achieved by this invention are as follows:

[0024] The pipe end straightening device provided by the present invention includes a straightening mechanism, an adjusting mechanism, and a traveling mechanism; the straightening mechanism includes a bidirectional telescopic rod and top blocks, the midpoint of the bidirectional telescopic rod is hinged to the adjusting mechanism, the adjusting mechanism is connected to the traveling mechanism, and the traveling mechanism can move along the length of the steel pipe; the two top blocks are respectively connected to the two ends of the bidirectional telescopic rod, and the bidirectional telescopic rod drives the two top blocks to move synchronously and move away from each other.

[0025] The pipe end straightening device provided by this invention uses a bidirectional telescopic rod hinge to maintain the axis of the telescopic rod perpendicular to the axis of the steel pipe when the top block supports the inner wall of the steel pipe. The telescopic rod pushes the top block to expand the inner diameter of the pipe end, increasing the minor axis dimension of the pipe end and improving its roundness. Simultaneously, the traveling mechanism drives the straightening mechanism to align the top block with the plane of the pipe end, improving operational efficiency and reducing workload. When used in conjunction with relevant detection and positioning devices, such as sensors and cameras, the pipe end straightening device provided by this invention can achieve fully automatic correction of pipe end roundness, improving correction efficiency and reducing workload. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the pipe end straightening device provided in an embodiment of the present invention;

[0028] Figure 2 This is another structural schematic diagram of the pipe end straightening device provided in an embodiment of the present invention;

[0029] Figure 3 This is another structural schematic diagram of the pipe end straightening device provided in an embodiment of the present invention;

[0030] Figure 4 This is a front view of the pipe end straightening device provided in an embodiment of the present invention;

[0031] Figure 5This is a left view of the pipe end straightening device provided in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of a hydraulic system.

[0033] Icons: 100, Correction mechanism; 110, Bidirectional telescopic rod; 120, Top block; 111, Extension rod; 112, Cylinder body; 101, First chamber; 102, Second chamber;

[0034] 200. Adjusting mechanism; 210. Lateral connecting rod; 220. Slider; 230. Lead screw; 240. Guide rod; 250. Lifting motor;

[0035] 300. Traveling mechanism; 310. Frame; 320. Traveling wheels; 330. Traveling rails; 340. Gear motor; 350. Universal joint;

[0036] 410. Piston pump; 420. First check valve; 430. Directional control valve; 440. Stacked hydraulic check valve; 450. First one-way speed control valve; 460. Self-adjusting synchronizing valve; 470. Second one-way speed control valve; 480. Oil tank; 490. Solenoid relief valve;

[0037] 510. Liquid level and oil temperature gauge; 520. Air filter; 530. Direct return oil filter; 540. Air cooler; 550. Pressure gauge switch; 560. Shock-resistant pressure gauge; 570. High-pressure hose; 580. Hydraulic pump drive motor;

[0038] 10. Steel pipes. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0041] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0042] The current method of manually correcting the shape of steel pipe ends using jacks results in a large workload for employees during the correction process; moreover, the manual correction method is inefficient and cannot meet the overall production rhythm of the production line.

[0043] In view of this, the present invention provides a pipe end straightening device, including a straightening mechanism 100, an adjusting mechanism 200, and a traveling mechanism 300; the straightening mechanism 100 includes a bidirectional telescopic rod 110 and a top block 120, the midpoint of the bidirectional telescopic rod 110 is hinged to the adjusting mechanism 200, the adjusting mechanism 200 is connected to the traveling mechanism 300, and the traveling mechanism 300 can move along the length direction of the steel pipe 10; the two top blocks 120 are respectively connected to the two ends of the bidirectional telescopic rod 110, and the bidirectional telescopic rod 110 drives the two top blocks 120 to move synchronously and move away from each other.

[0044] The pipe end straightening device provided by this invention uses a bidirectional telescopic rod 110 hinged to maintain the axis of the bidirectional telescopic rod 110 perpendicular to the axis of the steel pipe 10 when the top block 120 supports the inner wall of the steel pipe. The bidirectional telescopic rod 110 pushes the top block 120 to expand the inner diameter of the pipe end, increasing the minor axis dimension of the pipe end and improving its roundness. Simultaneously, the traveling mechanism 300 drives the correction mechanism 100 to align the top block 120 with the pipe end plane, improving operational efficiency and reducing workload. The pipe end straightening device provided by this invention, in conjunction with related detection and positioning devices such as sensors and cameras, can achieve fully automatic correction of pipe end roundness, improving correction efficiency and reducing workload.

[0045] The following combination Figures 1-6 The structure and shape of the pipe end straightening device provided in this embodiment are described in detail below:

[0046] The pipe end straightening device provided in this embodiment includes a straightening mechanism 100, an adjusting mechanism 200, a traveling mechanism 300, and a hydraulic system. Specifically, the straightening mechanism 100 includes a bidirectional telescopic rod 110 and two top blocks 120, with the two top blocks 120 respectively connected to both ends of the bidirectional telescopic rod 110; the adjusting mechanism 200 includes a transverse connecting rod 210, a slider 220, a lead screw 230, a guide rod 240, and a lifting motor 250; the traveling mechanism 300 includes a frame 310, traveling wheels 320, a traveling track 330, a reduction motor 340, and a universal joint 350.

[0047] The bidirectional telescopic rod 110 can be either a double-acting hydraulic cylinder or an electric telescopic rod. Hydraulic drive has the advantage of smaller size compared to electric drive, which facilitates insertion into the end of the steel pipe 10 and reduces its weight. In this embodiment, the double-acting hydraulic cylinder includes two extension rods 111 and a cylinder body 112. The two extension rods 111 are respectively inserted into the two cylinder barrels of the cylinder body 112. One end of the top block 120 is arc-shaped, used to fit against the inner wall of the steel pipe to ensure stable force application, and the other end is connected to the extension rods 111. That is, the two extension rods 111 are respectively connected to the two top blocks 120, used to drive the two top blocks 120 to move synchronously and move away from each other to press against the inner wall of the steel pipe.

[0048] In this embodiment, one end of the transverse connecting rod 210 is hinged to the midpoint of the bidirectional telescopic rod 110, thereby keeping the double-acting hydraulic cylinder vertical under its own weight. The other end is connected to the slider 220, which can move vertically. The lead screw 230 is vertically mounted and rotatably installed on the frame 310, and the slider 220 is threadedly connected to the lead screw 230. The guide rod 240 is vertically mounted on the frame 310 and inserted into the slider 220. The lifting motor 250 is mounted on the frame 310 and connected to the lead screw, used to drive the lead screw 230 to rotate around its own axis to move the slider 220, thereby driving the transverse connecting rod 210 and the correction mechanism 100 to move vertically through the slider 220.

[0049] In this embodiment, the lifting motor 250 is a worm gear motor.

[0050] In this embodiment, the walking mechanism 300 includes four walking wheels 320, which are mounted on the frame 310. Two of the walking wheels 320 are driving wheels, and two are driven wheels. A reduction motor 340 is mounted on the frame 310 and drives one driving wheel to roll via chain drive. The two driving wheels are connected by a universal joint 350 to rotate the other driving wheel.

[0051] In this embodiment, the traveling wheel 320 rolls along the traveling track 330 to improve stability. Specifically, both the traveling wheel 320 and the traveling track 330 are made of steel. The traveling track 330 has an I-shaped cross-section. The outer circular surface of the traveling wheel 320 is provided with a groove to match the traveling track 330, so that the traveling wheel 320 rolls stably along the traveling track 330 and avoids skewing and height changes.

[0052] In this embodiment, a hydraulic system is also provided to drive the two extension rods 111 of the double-acting hydraulic cylinder to extend synchronously, including a piston pump 410, a first check valve 420, a directional valve 430, a stacked hydraulic control check valve 440, a first one-way speed regulating valve 450, a self-adjusting synchronizing valve 460, a second one-way speed regulating valve 470, an oil tank 480, a solenoid relief valve 490, a level and temperature gauge 510, an air filter 520, a direct return oil filter 530, an air cooler 540, a pressure gauge switch 550, a shock-resistant pressure gauge 560, a high-pressure hose 570, and a hydraulic pump drive motor 580, as shown below. Figure 6 As shown.

[0053] Specifically, the extension rod 111 divides the cylinder into a first chamber 101 and a second chamber 102. The first chamber 101 is a rodless chamber, and the second chamber 102 is a rod chamber. The reversing valve 430 is an electro-hydraulic reversing valve. When the extension rod 111 extends, end a of the reversing valve 430 is energized. Oil flows from the oil tank 480 through the plunger pump 410, the first check valve 420, the reversing valve 430, the stacked hydraulic check valve 440, the first one-way speed control valve 450, the self-adjusting synchronizing valve 460, and the high-pressure hose 570 before entering the first chamber 101. This pushes the extension rod 111 to extend and compresses the second chamber 102. At this time, the telescopic rod drives the top block 120 to press against the inner wall of the steel pipe and push the inner wall to expand outward for correction. Simultaneously, the oil in the second chamber 102 flows through the high-pressure hose 570, the second one-way speed control valve 470, the stacked hydraulic check valve 440, the reversing valve 430, the air cooler 540, and the direct return oil filter 530 before returning to the oil tank 480.

[0054] After the top block 120 is in place, both ends of the directional valve 430 are de-energized, and the double-acting hydraulic cylinder enters the pressure-holding state under the action of the superimposed hydraulic control check valve 440.

[0055] When the extension rod 111 retracts, the b end of the reversing valve 430 is energized, and the oil flows from the oil tank 480 through the plunger pump 410, the first check valve 420, the reversing valve 430, the stacked hydraulic check valve 440, the second one-way speed control valve 470, and the high-pressure hose 570 into the second chamber 102, thereby pushing the extension rod 111 to retract and compress the first chamber 101; the oil in the first chamber 101 flows through the high-pressure hose 570, the self-adjusting synchronizing valve 460, the first one-way speed control valve 450, the stacked hydraulic check valve 440, the reversing valve 430, the air cooler 540, and the direct return oil filter 530 before returning to the oil tank 480.

[0056] In this embodiment, the first one-way speed control valve 450 is used to control the flow rate of oil flowing out of the first chamber 101, and the second one-way speed control valve 470 is used to control the flow rate of oil flowing out of the second chamber 102. The self-adjusting synchronization valve 460 ensures that the two extension rods 111 of the double-acting hydraulic cylinder extend and retract synchronously, thereby ensuring that the inner wall of the steel pipe in the short axis direction is simultaneously stressed during the jacking process. The system pressure is regulated by the electromagnetic relief valve 490. When the system pressure exceeds the set value, the oil returns from the plunger pump 410 to the oil tank 480 through the electromagnetic relief valve 490, the air cooler 540, and the direct return oil filter 530.

[0057] In this embodiment, a liquid level and temperature gauge 510 is installed in the oil tank 480 to monitor the height and temperature of the oil in the oil tank 480; an air filter 520 prevents impurities from entering the oil tank 480; a pressure switch is connected in series with a shock-resistant pressure gauge 560 to control the connection and disconnection between the shock-resistant pressure gauge 560 and the pipeline, and the shock-resistant pressure gauge 560 is used to display the system pressure; and a hydraulic pump drive motor 580 is used to drive the plunger pump 410 to work.

[0058] The pipe end straightening device provided in this embodiment achieves five degrees of freedom adjustment through the extension and retraction of two extension rods 111, the hinge of the bidirectional telescopic rod 110 and the transverse connecting rod 210, the vertical movement of the crossbeam connecting rod driven by the slider 220, and the movement of the traveling mechanism 300 along the length of the steel pipe. This facilitates accurate and rapid adjustment of the positioning of the top block 120 and the steel pipe, achieves rapid correction, reduces workload, and improves work efficiency.

[0059] It should be noted that when the top block 120 supports the inner wall of the steel pipe, the hinged connection between the bidirectional telescopic rod 110 and the transverse connecting rod 210, combined with the synchronous extension of the two telescopic rods, can achieve automatic adjustment, ensuring that the axis of the extension rod 111 is perpendicular to the axis of the steel pipe, avoiding the situation where the two axes are not completely perpendicular, thereby avoiding the top deviation phenomenon and improving the quality of correction.

[0060] In this embodiment, the first check valve 420 is a plate check valve, and the plunger pump 410 is a variable displacement plunger pump.

[0061] Based on the pipe end straightening device provided in this embodiment, a pipe end straightening method is proposed, which includes the following steps using the aforementioned pipe end straightening device:

[0062] The bidirectional telescopic rod 110 remains vertical under the action of gravity, and the steel pipe is rotated to make the minor axis of the ellipse at the end of the steel pipe vertical. Specifically, after the steel pipe is rotated on the rotating roller until the minor axis of the ellipse at the end of the pipe is in the vertical direction, the state of the steel pipe on the rotating roller remains unchanged.

[0063] During calibration, the slider 220 moves so that the hinge point of the bidirectional telescopic rod 110 and the transverse connecting rod 210 coincides with the axis of the steel pipe. The traveling mechanism 300 moves along the length of the steel pipe so that the top block 120 is flush with the end of the steel pipe. Then, the hydraulic system drives the bidirectional telescopic rod 110 to extend, causing the two top blocks 120 to move synchronously. The two top blocks 120 move away from each other and abut against the inner wall of the steel pipe to increase the diameter of the end of the steel pipe along the minor axis of the ellipse. After the support is in place, pressure is maintained to prevent retraction. Finally, the extension rod 111 retracts, and the traveling mechanism 300 moves to move the calibration mechanism 100 away from the steel pipe.

[0064] The pipe end straightening device provided in this embodiment automates the correction of non-roundness of steel pipe ends, ensuring the correction effect of steel pipe ends while improving its correction efficiency and quality and reducing the labor intensity of operators.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pipe end straightening device, characterized in that, It includes a correction mechanism (100), an adjustment mechanism (200), and a walking mechanism (300); the correction mechanism (100) includes a bidirectional telescopic rod (110) and a top block (120), the midpoint of the bidirectional telescopic rod (110) is hinged to the adjustment mechanism (200), the adjustment mechanism (200) is connected to the walking mechanism (300), and the walking mechanism (300) can move along the length of the steel pipe; the two top blocks (120) are respectively connected to the two ends of the bidirectional telescopic rod (110), and the bidirectional telescopic rod (110) drives the two top blocks (120) to move synchronously and move away from each other.

2. The pipe end straightening device according to claim 1, characterized in that, The adjustment mechanism (200) includes a transverse connecting rod (210) and a slider (220). One end of the transverse connecting rod (210) is hinged to the midpoint of the bidirectional telescopic rod (110), and the other end is connected to the slider (220). The slider (220) can move in the vertical direction.

3. The pipe end straightening device according to claim 2, characterized in that, The adjustment mechanism (200) further includes a lead screw (230), which is vertically arranged and rotatably mounted on the walking mechanism (300). The slider (220) is threadedly connected to the lead screw (230), and the lead screw (230) rotates around its own axis to drive the slider (220) to move.

4. The pipe end straightening device according to claim 3, characterized in that, It also includes a guide rod (240), which is vertically arranged and inserted into the slider (220).

5. The pipe end straightening device according to claim 4, characterized in that, The walking mechanism (300) includes a frame (310) and a walking wheel (320), the walking wheel (320) being mounted on the frame (310), the guide rod (240) and the lead screw (230) being mounted on the frame (310); The wheels (320) rotate to move the frame (310).

6. The pipe end straightening device according to claim 5, characterized in that, The walking mechanism (300) also includes a walking track (330), along which the walking wheel (320) rolls.

7. The pipe end straightening device according to claim 1, characterized in that, The bidirectional telescopic rod (110) is configured as a double-acting hydraulic cylinder, including two extension rods (111) and a cylinder body (112), with the two extension rods (111) respectively inserted into the two cylinder barrels of the cylinder body (112); The two extension rods (111) are respectively connected to the two top blocks (120) to drive the two top blocks (120) to move synchronously in opposite directions to press against the inner wall of the steel pipe.

8. The pipe end straightening device according to claim 7, characterized in that, It also includes a hydraulic system for supplying fluid to the cylinder (112) to push the two extension rods (111) to extend synchronously, thereby driving the two top blocks (120) to press against the inner wall of the steel pipe.

9. The pipe end straightening device according to claim 8, characterized in that, The hydraulic system includes a piston pump (410), a first check valve (420), a directional valve (430), a stacked hydraulic control check valve (440), a first one-way speed control valve (450), a self-adjusting synchronizing valve (460), a second one-way speed control valve (470), and an oil tank (480). The extension rod (111) divides the cylinder into a first chamber (101) and a second chamber (102). When the extension rod (111) extends, the oil flows from the oil tank (480) through the plunger pump (410), the first one-way valve (420), the reversing valve (430), the stacked hydraulic control one-way valve (440), the first one-way speed control valve (450), and the self-adjusting synchronizing valve (460) before entering the first chamber (101), thereby pushing the extension rod (111) to extend and compressing the second chamber (102). The oil in the second chamber (102) flows through the second one-way speed control valve (470), the stacked hydraulic control one-way valve (440), and the reversing valve (430) before returning to the oil tank (480). When the extension rod (111) retracts, the oil flows from the oil tank (480) through the plunger pump (410), the first one-way valve (420), the reversing valve (430), the stacked hydraulic control one-way valve (440), and the second one-way speed control valve (470) before entering the second chamber (102), thereby pushing the extension rod (111) to retract and compressing the first chamber (101); the oil in the first chamber (101) flows through the self-adjusting synchronous valve (460), the first one-way speed control valve (450), the stacked hydraulic control one-way valve (440), and the reversing valve (430) before returning to the oil tank (480); The first one-way speed control valve (450) is used to control the flow rate of oil flowing out of the first chamber (101), and the second one-way speed control valve (470) is used to control the flow rate of oil flowing out of the second chamber (102).

10. A pipe end straightening method, employing the pipe end straightening device as described in any one of claims 1-9, characterized in that, Includes the following steps: The bidirectional telescopic rod (110) remains vertical under the action of gravity, and the steel pipe is rotated to make the minor axis of the ellipse at the end of the steel pipe vertical; During calibration, the walking mechanism (300) moves along the length of the steel pipe to make the top block (120) flush with the end of the steel pipe. Then, the bidirectional telescopic rod (110) extends to drive the two top blocks (120) to move synchronously. The two top blocks (120) move away from each other and abut against the inner wall of the steel pipe to increase the diameter of the end of the steel pipe along the minor axis of the ellipse.

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