Large-diameter thin-wall steel pipe end rounding and coaxial positioning chamfering machine and chamfering method

Abstract

The large-diameter thin-wall steel pipe end rounding and coaxial positioning chamfering machine and chamfering method relate to the technical field of steel pipe processing equipment, and the chamfering machine comprises a base, a cutter seat, a cutter disc, a cutter, a positioning rod, an adjusting slide and a steel pipe fixing mechanism, the positioning rod is coaxially arranged with the cutter disc, and the steel pipe fixing mechanism is connected to the end of the positioning rod and can be extended into the pipe orifice of the steel pipe end to expand outward. When chamfering, the steel pipe fixing mechanism simultaneously implements the end rounding and coaxial positioning of the steel pipe end, then the adjusting slide drives the whole steel pipe to move in the direction of the cutter disc, and the rotating cutter completes the chamfering processing. The present application also adjusts the position of the supporting roller in advance through the laser calibration device to ensure the consistency of the long steel pipe axis. The present application integrates the end rounding and coaxial positioning of the steel pipe end, does not need to cut off the end material in advance, effectively avoids material waste, significantly improves the chamfering precision, guarantees the subsequent steel pipe butt welding quality, and is suitable for efficient and precise machining of large-diameter thin-wall steel pipes.

Description

Technical Field

[0001] This invention relates to the field of steel pipe processing equipment technology, and in particular to a chamfering machine and chamfering method for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes. Background Technology

[0002] In major engineering projects such as oil and gas transportation, the application of large-diameter thin-walled steel pipes is becoming increasingly widespread. Before leaving the factory or during field application, the ends of these pipes typically require chamfering to form a specific geometry. Precise end chamfering is particularly crucial in scenarios where adjacent pipes are joined using direct butt welding. Specifically, by chamfering the ends of the two pipes to be joined, a Y-shaped annular gap is formed at the joint. This gap serves as the molten pool space for subsequent welding, ensuring a full weld bead and a smooth transition with the base material, thus guaranteeing weld quality.

[0003] However, due to their inherent poor rigidity, large-diameter thin-walled steel pipes are prone to elliptical deformation or uneven wall thickness at their ends during manufacturing, transportation, and storage. This inherent characteristic poses a significant challenge to subsequent chamfering. Directly chamfering the deformed pipe ends easily leads to uneven cutting allowances, and may even result in completely beveled surfaces penetrating both the inner and outer walls in certain areas, rather than the theoretically regular chamfer formed by bevels and vertical surfaces. This irregular chamfer shape will cause molten metal to sag during subsequent welding, forming raised weld scars on the inner wall of the steel pipe. For pipelines transporting high-pressure gases, this inner wall protrusion disrupts the smoothness of the pipe wall, causing localized turbulence in the airflow. This not only increases energy consumption but may also induce severe erosion and wear during long-term operation, posing a significant safety hazard to the pipeline.

[0004] To address the aforementioned problems, a common approach in this field is to pre-cut off the defective portion at the end of the steel pipe before chamfering. While this method eliminates end deformation, it results in significant material waste and substantially increases production costs. Furthermore, the chamfering process typically requires a separate clamping and fixing mechanism to secure the steel pipe, as disclosed in Chinese Patent CN203992543U, which uses a clamping mechanism to fix the steel pipe and then performs rotary cutting using a machine tool. In this traditional design, the clamping and fixing mechanism and the cutting tool system are independent and separate structures. Due to accumulated tolerances during assembly and the difficulty in achieving dynamic calibration, it is difficult to ensure high-precision alignment between the axis of the clamped steel pipe and the axis of rotation of the cutting tool in actual operation. This axial deviation is another core factor contributing to insufficient chamfering accuracy. Even with significant time spent on manual alignment adjustments, it is difficult to guarantee consistent processing efficiency, ultimately affecting the chamfering quality and failing to meet the stringent welding requirements of large-diameter thin-walled steel pipes. Summary of the Invention

[0005] The purpose of this invention is to provide a chamfering machine and method for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes. This method rounds the ends of large-diameter thin-walled steel pipes before chamfering to eliminate their own deformation defects, thus eliminating the need to pre-cut the ends. At the same time as rounding, it achieves precise coaxial positioning of the steel pipe and the cutter head, thereby improving the chamfering accuracy and fundamentally avoiding welding defects caused by end deformation and axial deviation.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a chamfering machine for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes, comprising a base and a tool holder disposed on the base, a cutter disc disposed at one end of the tool holder, a chamfering tool disposed on the cutter disc, and a chamfering power mechanism for driving the cutter disc to rotate inside the tool holder, characterized in that it further comprises:

[0007] A positioning rod is disposed through the tool holder, the axis of the positioning rod coincides with the rotation axis of the tool disc, and the tool disc can rotate relative to the positioning rod;

[0008] An adjustable slide block is slidably connected to the base, and one end of the positioning rod is fixed to the adjustable slide block;

[0009] A steel pipe fixing mechanism is connected to the other end of the positioning rod that passes through the center of the cutter head. The steel pipe fixing mechanism can extend into the end opening of the steel pipe and expand outward to achieve full circle and coaxial positioning of the end of the steel pipe.

[0010] It also includes a V-shaped roller located below the middle section of the steel pipe, the position of which is adjustable in both the horizontal and vertical directions. Before placing the steel pipe on the roller, a baffle carrying a center mark is set above the roller, and a laser emitter is temporarily fixed at the end of the steel pipe fixing mechanism so that the laser emitted by the laser emitter is coaxial with the positioning rod. The position of the roller is adjusted until the laser hits the center mark to pre-calibrate the axis of the steel pipe and the axis of rotation of the cutter head. The center mark corresponds to the theoretical position of the axis of the steel pipe when the steel pipe to be processed is placed on the roller.

[0011] Preferably, the steel pipe fixing mechanism includes:

[0012] An annular sleeve is fixed to the other end of the positioning rod that protrudes from the center of the cutter head, and its outer diameter is smaller than the inner diameter of the steel pipe to be processed.

[0013] Multiple top blocks are spaced apart circumferentially along the annular sleeve. The top blocks penetrate the sidewall of the annular sleeve and are capable of extending and retracting in the radial direction of the annular sleeve.

[0014] The movable rod is coaxially and movably disposed inside the positioning rod in the hollow structure;

[0015] A tapered rod is coaxially disposed inside the annular sleeve. One end of the tapered rod is fixedly connected to one end of the movable rod, and the tapered surface of the tapered rod mates with the inner end of each of the top blocks.

[0016] A hydraulic cylinder is connected to the other end of the movable rod. The hydraulic cylinder is fixed on the adjusting slide block and is used to drive the movable rod to move axially, thereby driving the tapered rod to push each of the top blocks to expand outward synchronously.

[0017] More preferably, it also includes a drive mechanism disposed on the base for driving the adjusting slide to move axially along the positioning rod.

[0018] More preferably, a support guide ring is coaxially fixed to the end of the annular sleeve away from the positioning rod, and a guide rod is coaxially fixed to the end of the tapered rod away from the movable rod. The guide rod passes through the support guide ring and slides in cooperation with the inner wall of the support guide ring.

[0019] More preferably, the number of top blocks is six, and the six top blocks are evenly spaced along the circumference of the annular sleeve.

[0020] More preferably, the steel pipe fixing mechanism further includes a fixing ring with a notch, the fixing ring being made of a material with elastic deformation capability, and each top block having a through hole at the part located outside the annular sleeve, the fixing ring passing through each through hole in sequence to connect and limit the top blocks in series.

[0021] More preferably, the end face of the cutter head is provided with a plurality of T-shaped grooves spaced apart circumferentially, the T-shaped grooves extend in the radial direction of the cutter head and one end extends to the outer peripheral surface of the cutter head to form an opening, the cutter is fixed on the T-shaped block, and the T-shaped block is slidably fitted into the T-shaped groove and fixed by bolts.

[0022] More preferably, there are two T-shaped blocks, which are symmetrically distributed on the two T-shaped slots, and each T-shaped block is fixed with a cutting tool.

[0023] In addition, the present invention also provides a method for chamfering large-diameter thin-walled steel pipes using the aforementioned chamfering machine that rounds and coaxially positions the ends, comprising the following steps:

[0024] S1. Before placing the steel pipe on the idler roller, a baffle is set above the idler roller, and a laser emitter is temporarily fixed at the end of the steel pipe fixing mechanism so that the laser emitted by the laser emitter is coaxial with the positioning rod. The position of the idler roller is adjusted until the laser hits the center mark on the baffle. Then the laser emitter is removed. The center mark corresponds to the theoretical position of the steel pipe axis when the steel pipe to be processed is placed on the idler roller.

[0025] S2. Fit one end of the steel pipe onto the steel pipe fixing mechanism, so that the steel pipe fixing mechanism extends into the end of the pipe.

[0026] S3. Start the oil cylinder to drive the movable rod and the conical rod to move, so that each top block expands outward synchronously, presses against the inner wall of the end of the steel pipe from the inside, rounds the end of the steel pipe and makes the axis of the steel pipe coincide with the rotation axis of the cutter head.

[0027] S4. Start the drive mechanism to drive the adjusting slide to move away from the cutter head, and drive the steel pipe to move towards the cutter head through the steel pipe fixing mechanism, so that the end of the steel pipe moves to the processing position of the cutter.

[0028] S5. Start the chamfering power mechanism to drive the cutter head to rotate, so that the cutter can chamfer the end of the steel pipe.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The core of this invention lies in directly connecting the steel pipe fixing mechanism to a positioning rod coaxially arranged with the cutter head, thus achieving structural coaxial integration between the fixing mechanism and the tool system. This design fundamentally eliminates the axial deviation problem caused by the independent operation of the clamping mechanism and the tool system in traditional solutions. It eliminates the need for tedious manual alignment adjustments before each machining operation, ensuring that the axis of the steel pipe being processed automatically coincides with the rotation axis of the cutter head, thereby significantly improving the accuracy and consistency of chamfering.

[0031] Before chamfering, the steel pipe fixing mechanism extends into the end of the steel pipe and expands uniformly outward. This allows for the active rounding of the ends of large-diameter thin-walled steel pipes that have undergone elliptical deformation or uneven wall thickness, restoring them to a regular circular cross-section. Because this rounding operation applies force directly to the inner wall surface, it not only achieves significant correction but also completely replaces the traditional method of pre-cutting the ends, thus avoiding substantial material waste and significantly reducing production costs. Simultaneously, this rounding process is completed concurrently with the coaxial positioning process, establishing a high-precision machining axis while eliminating end defects, requiring no additional steps or separate equipment.

[0032] Furthermore, the chamfering method incorporates a laser calibration step for the idler roller in the middle section of the steel pipe. By coordinating a laser emitter temporarily installed at the end of the fixing mechanism with the center mark of the baffle above the idler roller, the idler roller can be pre-adjusted to the accurate position before placing the steel pipe, ensuring that the axis of the entire steel pipe along its length is collinear with the rotation axis of the cutter head. This calibration measure effectively avoids deviation of the distal axis of the pipe body due to the weight of the long steel pipe or the offset of the idler roller, further guaranteeing the positioning reliability of long, large-diameter, thin-walled steel pipes throughout the rounding and subsequent chamfering processes.

[0033] This invention completes the rounding repair and high-precision coaxial positioning of the steel pipe end before chamfering, enabling subsequent cutting to be carried out under conditions of regular geometry and precise axis alignment, thereby obtaining a regular and uniform chamfer edge. This edge can form an ideal Y-shaped gap when two steel pipes are subsequently welded together, ensuring a full weld scar and a smooth transition with the inner wall. This fundamentally eliminates the problem of raised weld scars on the inner wall caused by chamfering deviation, significantly improving the quality of pipe welds and long-term service safety. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure including the steel pipe in the embodiment;

[0035] Figure 2 for Figure 1 A schematic diagram of the planar sectional structure;

[0036] Figure 3 This is a schematic diagram of the positioning rod and the steel pipe fixing mechanism in the embodiment;

[0037] Figure 4 for Figure 3 A schematic diagram of the planar sectional structure;

[0038] Figure 5 An exploded view of the supporting guide ring, fixing ring, top block, annular sleeve, and tapered rod;

[0039] Figure 6 This is a schematic diagram of the machining state when the cutting tool contacts the end of the steel pipe to perform chamfering in the embodiment;

[0040] Figure 7 This is a schematic diagram illustrating the operation state of adjusting the position of the idler roller using a baffle and a laser emitter in the embodiment.

[0041] Figure 8 This is a schematic diagram of the mechanism of the cutter head and cutter holder in the embodiment.

[0042] In the picture:

[0043] 1—Base; 2—Tool holder; 3—Tool disc; 4—Tool; 5—Positioning rod; 6—Adjusting slide; 7—Steel pipe; 8—Annular sleeve; 9—Top block; 10—Modular rod; 11—Conical rod; 12—Hydraulic cylinder; 13—Fixing ring; 14—Through hole; 15—Support guide ring; 16—Guide rod; 17—Idler roller; 18—T-block; 19—T-slot; 20—Laser emitter; 21—Baffle. Detailed Implementation

[0044] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0045] It should be noted in advance that, in this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances. Furthermore, in this invention, unless otherwise explicitly specified and limited, "on" or "under" a second feature can include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0046] like Figure 1 and Figure 2 As shown, the present invention provides a chamfering machine for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes, including a base 1 and a tool holder 2 disposed on the base 1. The base 1 is the basic load-bearing component of the overall equipment of the present invention.

[0047] The tool holder 2 is fixedly installed at the left end of the base 1 (with... Figure 1 (The indicated direction is for reference only). The tool holder 2 has a box-like structure. The interior of the tool holder 2 is a hollow structure used to accommodate and install the chamfering power mechanism. A cutter disc 3 is provided on the left end face of the tool holder 2. The cutter disc 3 has a disc-shaped structure and is made of alloy structural steel. A central through hole is opened at its center for the positioning rod 5 to pass through. The cutter disc 3 is rotatably supported on the left end of the tool holder 2 by a bearing assembly. The right end of the cutter disc 3 is connected to the power output end of the chamfering power mechanism, so that it rotates around its own axis under the drive of the chamfering power mechanism. The chamfering power mechanism can be a combination of an electric motor and a gear reducer, or it can be an electric spindle. Its specific structure is not an improvement of this invention and will not be described in detail here. Those skilled in the art can select a suitable power drive form according to actual needs. The left end face of the cutter head 3 (i.e., the end face facing the steel pipe 7 to be processed) is provided with chamfering tools 4. Preferably, there are two tools 4, and the two tools 4 are symmetrically distributed 180° around the circumference of the cutter head 3 to achieve simultaneous cutting from both sides, ensuring uniform force on the end of the steel pipe 7 and reducing cutting deformation. The tools 4 are made of cemented carbide, and the shape of their cutting edges matches the required chamfering angle. Different angle tools can be selected according to the chamfering requirements of different specifications of steel pipes.

[0048] like Figure 1 and Figure 2 As shown, the core improvement of this invention lies in the fact that a positioning rod 5 is also provided through the tool holder 2. The positioning rod 5 is a slender rod-shaped component, and its axis is aligned with the rotation axis of the cutter head 3. A bearing assembly is provided between the positioning rod 5 and the cutter head 3, allowing the cutter head 3 to rotate freely relative to the positioning rod 5, while the positioning rod 5 itself does not rotate with the cutter head 3. The right end of the positioning rod 5 protrudes from the right side of the tool holder 2 and is fixedly mounted on an adjusting slide 6. The adjusting slide 6 is slidably connected to the base 1. Specifically, a linear guide rail is fixedly mounted on the upper surface of the base 1 at a position located on the right side of the tool holder 2, and a slider that cooperates with the linear guide rail is fixedly mounted on the bottom of the adjusting slide 6, allowing the adjusting slide 6 to move along the axial direction of the positioning rod 5 (i.e., Figure 1The adjusting slide 6 (in the left-right direction) slides freely on the base 1. The sliding of the adjusting slide 6 is driven by a drive mechanism mounted on the base 1. The drive mechanism can be a combination of a servo motor and a ball screw and nut pair. The servo motor is fixed to the base 1, one end of the ball screw is connected to the output shaft of the servo motor via a coupling, and the nut of the ball screw is fixedly connected to the adjusting slide 6. When the servo motor rotates, it drives the ball screw to rotate, thereby driving the adjusting slide 6 to reciprocate along the linear guide rail. The ball screw and nut pair has the advantages of high transmission accuracy and smooth movement, and can precisely control the moving position and speed of the adjusting slide 6. In other embodiments, the drive mechanism can also use any linear power element, as long as it can achieve the reciprocating movement of the adjusting slide 6 along the axial direction; this invention does not impose specific limitations on this.

[0049] In this embodiment, the left end of the positioning rod 5 extends from the left side of the cutter holder 2 and through the central through hole of the cutter head 3 to the outer side of the left end face of the cutter head 3. A steel pipe fixing mechanism is connected to the left end of the positioning rod 5 extending from the center of the cutter head 3. This steel pipe fixing mechanism is used to extend into the right end opening of the steel pipe 7 and expand outwards to achieve complete circular and coaxial positioning of the end of the steel pipe 7. The specific structure of the steel pipe fixing mechanism is detailed below.

[0050] like Figure 3 , Figure 4 and combined Figure 5As shown, the steel pipe fixing mechanism includes an annular sleeve 8, which is a circular ring-shaped component. Its right end face is coaxially and fixedly connected to the left end face of the positioning rod 5. The outer diameter of the annular sleeve 8 is smaller than the inner diameter of the steel pipe 7 to be processed, so that the annular sleeve 8 can smoothly extend into the end opening of the steel pipe 7. Multiple through holes are provided on the side wall of the annular sleeve 8, spaced apart circumferentially. These through holes extend radially along the annular sleeve 8 and are used to install top blocks 9. In this embodiment, the annular sleeve 8 has six through holes evenly distributed circumferentially, and correspondingly, six top blocks 9 are provided. The six top blocks 9 are evenly spaced circumferentially along the annular sleeve 8, that is, adjacent top blocks 9 are spaced at a 60° angle in the circumferential direction. The number of top blocks 9 is set to six, which ensures a sufficiently uniform distribution of support force on the inner wall of the steel pipe 7, while avoiding structural complexity and motion interference due to an excessive number. The top block 9 has a rectangular parallelepiped structure, and its cross-sectional shape matches the cross-sectional shape of the through hole on the annular sleeve 8. The top block 9 is installed through the side wall of the annular sleeve 8 and can extend and retract radially along the annular sleeve 8. The inner end of the top block 9 (i.e., the end closest to the axis of the annular sleeve 8) is located in the internal cavity of the annular sleeve 8, while the outer end of the top block 9 (i.e., the end furthest from the axis of the annular sleeve 8) extends to the outside of the annular sleeve 8. The outer end face of the top block 9 is rectangular with chamfers at both ends. When the top block 9 expands outward and presses against the inner wall of the steel pipe 7, the outer end face of the top block 9 can form surface contact with the inner wall of the steel pipe 7, thereby reducing contact stress and avoiding indentations or localized damage on the inner wall of the steel pipe 7. It also provides more stable support and a rounded effect.

[0051] The positioning rod 5 is a hollow structure with a central hole extending axially inside. A movable rod 10 is coaxially mounted within this central hole. The movable rod 10 is a slender, round rod-shaped component with an outer diameter smaller than the inner diameter of the positioning rod 5, allowing it to slide freely axially within the central hole of the positioning rod 5. The right end of the movable rod 10 protrudes from the right end of the positioning rod 5 and extends to the outside right side of the adjusting slide 6. The right end of the movable rod 10 is fixedly connected to the piston rod end of the hydraulic cylinder 12. The hydraulic cylinder 12 is fixedly mounted on the right end face of the adjusting slide 6, with its axis coinciding with the axis of the movable rod 10. The piston rod of the hydraulic cylinder 12 is fixedly connected to the right end of the movable rod 10 via a threaded connection. The hydraulic cylinder 12 has the advantages of large output force, smooth movement, and easy control, providing sufficient thrust to drive the top block 9 to expand outward and firmly press against the inner wall of the steel pipe 7.

[0052] like Figure 4As shown, the left end of the movable rod 10 extends into the internal cavity of the annular sleeve 8. A tapered rod 11 is coaxially arranged inside the annular sleeve 8. The tapered rod 11 is generally truncated cone-shaped, with its right end being the larger diameter end and its left end the smaller diameter end; that is, the tapered surface of the tapered rod 11 gradually widens from the left end to the right end. The right end face of the tapered rod 11 is coaxially and fixedly connected to the left end face of the movable rod 10. The connection method can be threaded or welded; in this embodiment, a threaded connection is preferred for ease of disassembly and replacement. When the hydraulic cylinder 12 drives the movable rod 10 to move axially, the movable rod 10 drives the tapered rod 11 to move synchronously. The outer circumferential surface of the tapered rod 11 is a conical surface, which engages with the inner end of each top block 9. Specifically, the inner end face of each top block 9 is set as a wedge-shaped surface, and the inclination angle of the wedge-shaped surface matches the conical surface angle of the conical rod 11, so that the wedge-shaped surface of the top block 9 can fit against the conical surface of the conical rod 11 and slide along the conical surface. When the hydraulic cylinder 12 drives the movable rod 10 to move to the left, the movable rod 10 pushes the conical rod 11 to move to the left, and the conical surface of the conical rod 11 gradually pushes against the wedge-shaped surface of each top block 9. Since the conical surface of the conical rod 11 gradually expands from left to right, during the process of the conical rod 11 moving to the left, each top block 9 expands outward in the radial direction under the pushing action of the conical surface until the outer arc-shaped surface of the top block 9 presses against the inner wall surface of the steel pipe 7. Conversely, when the hydraulic cylinder 12 drives the movable rod 10 to move to the right, the conical rod 11 moves to the right and resets, and each top block 9 loses the pushing action of the conical rod 11 and retracts inward in the radial direction under the action of its own weight and the elastic restoring force of the fixed ring 13.

[0053] To ensure that the tapered rod 11 remains coaxial with the annular sleeve 8 during movement and to prevent skewing, a support guide ring 15 is coaxially fixed at the left end of the annular sleeve 8. Figure 4 and Figure 5 As shown, the support guide ring 15 is a circular ring component, and its outer wall is fixedly connected to the inner wall of the left end of the ring sleeve 8 by a threaded connection. A short guide rod 16 is coaxially fixedly connected to the center of the left end face of the tapered rod 11. The guide rod 16 is a cylindrical rod, and its axis coincides with the axis of the tapered rod 11. The outer diameter of the guide rod 16 is adapted to the inner diameter of the support guide ring 15. The guide rod 16 passes through the central hole of the support guide ring 15, and the outer circumferential surface of the guide rod 16 slides in contact with the inner wall of the support guide ring 15. Through the radial limiting and guiding effect of the support guide ring 15 on the guide rod 16, it can be ensured that the tapered rod 11 always remains coaxial with the ring sleeve 8 during axial movement, avoiding the problem of asynchronous expansion of the top blocks 9 due to the skewness of the tapered rod 11, and further ensuring the accuracy of the rounding and positioning.

[0054] like Figure 4 and Figure 5As shown, the steel pipe fixing mechanism also includes a notched fixing ring 13. The fixing ring 13 is a ring-shaped component made of a material with elastic deformation capability; in this embodiment, it is preferably made of spring steel. The fixing ring 13 is not a complete closed ring, but has a notch at a certain position on its circumference, so that the fixing ring 13 can elastically deform when subjected to radial outward force, and its ring diameter can be expanded. Each top block 9 has a through hole 14 on the part located outside the annular sleeve 8, and the axis of the through hole 14 is consistent with the circumferential direction of the annular sleeve 8. The six through holes 14 on the six top blocks 9 are aligned sequentially in the circumferential direction, and the fixing ring 13 passes through the through holes 14 on each top block 9 in sequence, thereby connecting the six top blocks 9 together. The function of the fixing ring 13 is to limit and prevent the six top blocks 9 from detaching, preventing the top blocks 9 from coming out of the through holes of the annular sleeve 8 when not subjected to pushing force. Meanwhile, because the fixed ring 13 has elastic deformation capability and a notch, when the tapered rod 11 pushes each top block 9 to expand outward, the fixed ring 13 can elastically deform along with the expansion of the top block 9, its notch becomes larger, and the diameter of the ring increases, without restricting the normal expansion movement of the top block 9. When the tapered rod 11 moves to the right and resets, the fixed ring 13 returns to its original diameter under the action of its own elastic restoring force, while simultaneously driving each top block 9 to contract inward and reset, playing an auxiliary reset role.

[0055] The present invention also includes a support roller 17 disposed below the middle section of the steel pipe 7. Since the length of the large-diameter thin-walled steel pipe 7 is typically large (for example, in this embodiment, it refers to a steel pipe with a diameter of 630mm), if only the steel pipe fixing mechanism is used for support and positioning at one end of the steel pipe 7, the middle section and the part of the pipe body far from the processing end will sag due to its own weight, causing the entire steel pipe 7 to bend and deform, thereby affecting the positioning accuracy of the processing end. Therefore, the present invention provides a support roller 17 at an appropriate position on the right side of the base 1, such as... Figure 1 and Figure 2As shown, the idler roller 17 is located below the middle section of the steel pipe 7, providing auxiliary support at this location. The idler roller 17 is a V-shaped roller, meaning its upper surface has a V-shaped groove. The two inclined surfaces of this groove make two-point contact with the outer wall of the steel pipe 7, thus providing automatic centering and stable support. The position of the idler roller 17 is adjustable both horizontally and vertically. Specifically, a cross-slide adjustment mechanism is located at the bottom of the idler roller 17. This mechanism includes a horizontal adjusting screw and a vertical adjusting screw. By rotating the corresponding adjusting handle or driving the corresponding adjusting motor, the idler roller 17 can be precisely adjusted in the horizontal direction. Additionally, a lifting adjustment mechanism, such as a screw jack or hydraulic jack, is also provided at the bottom of the idler roller 17 to adjust its vertical height. The aforementioned adjustment mechanism can be used to adjust the idler roller 17 to the optimal support position to accommodate steel pipes of different specifications and degrees of curvature. Since these methods of adjusting the position of the idler roller 17 are also common in the steel pipe processing field, they will not be limited or described in detail.

[0056] Furthermore, such as Figure 7As shown, the chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes of the present invention also includes an auxiliary calibration device for calibrating the position of the idler roller 17. Specifically, before chamfering, a baffle 21 is set above the idler roller 17. The baffle 21 can be detachably mounted on the idler roller 17 by an independent bracket. For example, the bracket can be a U-shaped gantry frame bracket, with its two bottom ends detachably connected to the two ends of the idler roller 17's axis by bolts, or it can be directly detachably mounted on the support frame supporting the idler roller 17. The baffle 21 is installed at the top center of this gantry frame bracket, and a center mark is marked on the center position of the baffle 21. Since the diameter of the steel pipe to be processed is known, the center mark on the baffle 21 can be adjusted to correspond to the theoretical position of the steel pipe 7's axis when the steel pipe 7 is placed on the idler roller 17 by measuring the distance on site. In addition, a laser emitter 20 can be temporarily fixed at the end of the steel pipe fixing mechanism (i.e., the left end face of the guide rod 16, since the left end face of the guide rod 16 extends from the left end of the support guide ring 15 and becomes the leftmost part of the entire steel pipe fixing mechanism). The laser emitter 20 is temporarily installed on the left end of the guide rod 16 through a transition connecting sleeve, and the laser beam emitted by the laser emitter 20 coincides with the axis of the positioning rod 5. Since the axis of the positioning rod 5 coincides with the axis of rotation of the cutter head 3, the laser beam actually indicates the extension direction of the axis of rotation of the cutter head 3. When the laser beam is directed at the baffle 21, the operator can determine whether the position of the idler roller 17 is correct by observing whether the laser spot falls on the center mark point of the baffle 21. If the laser spot deviates from the center mark point, the horizontal position and vertical height of the idler roller 17 are adjusted until the laser spot accurately hits the center mark point, indicating that the position of the idler roller 17 is adjusted in place. After removing the baffle 21 and laser emitter 20, the steel pipe 7 can be placed on the idler roller 17. At this point, the axis of the steel pipe 7 is collinear with the rotation axis of the cutter head 3 in the middle section, ensuring that the entire steel pipe 7 is aligned along its length. This calibration step is particularly important for long, large-diameter, thin-walled steel pipes, effectively preventing problems caused by axis deviation of the steel pipe 7.

[0057] like Figure 8As shown, the left end face of the cutter head 3 (i.e., the end face facing the steel pipe 7) is provided with multiple T-shaped grooves 19 spaced apart circumferentially. The T-shaped grooves 19 extend radially along the cutter head 3, and one end extends to the outer circumferential surface of the cutter head 3, forming an opening on the outer circumferential surface of the cutter head 3. The cross-sectional shape of the T-shaped grooves 19 is T-shaped, that is, the width of the groove bottom is greater than the width of the groove opening. This structure can form a sliding fit and limit with the T-shaped block 18. There are six T-shaped grooves 19, which are evenly distributed circumferentially along the cutter head 3, that is, adjacent T-shaped grooves 19 are spaced at a 60° angle in the circumferential direction. The cutting tool 4 is fixedly mounted on the T-block 18. The shape of the T-block 18 is adapted to the T-slot 19. The T-block 18 can be pushed into the T-slot 19 from the opening on the outer circumferential surface of the cutter head 3, and slide along the extension direction of the T-slot 19 to the desired position. Then, the T-block 18 is locked and fixed in the T-slot 19 by bolts. In this embodiment, there are two T-blocks 18, which are symmetrically mounted in the two T-slots 19, that is, the two T-blocks 18 are symmetrically distributed 180° around the cutter head 3. Each T-block 18 is fixedly mounted with a cutting tool 4. The two cutting tools 4 are symmetrically arranged, and when the cutter head 3 rotates, they can simultaneously chamfer the end of the steel pipe 7, so that the end of the steel pipe 7 is subjected to symmetrical and uniform force. By adjusting the radial position of the T-block 18 in the T-slot 19, the cutting radius of the cutting tool 4 can be adjusted, so that the present invention can adapt to the chamfering needs of steel pipes with different diameter specifications, enhancing the versatility and flexibility of the equipment. In actual production, when processing chamfered steel pipes of different specifications and materials, the pressure of the push rod hydraulic system can be precisely adjusted through database comparison to achieve rounding of the steel pipe without producing hexagonal deformation exceeding the standard. The other four T-slots 19 without T-blocks 18 can be used as spare slots to facilitate increasing the number of tools or adjusting the distribution angle of tools according to processing needs.

[0058] The following describes in detail the operation method of the chamfering machine for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes according to the present invention. The method includes the following steps:

[0059] S1, Calibration Procedure. (For example...) Figure 7As shown, before placing the steel pipe 7 onto the idler roller 17, the position of the idler roller 17 is first calibrated. A baffle 21 is installed above the idler roller 17, and the baffle 21 is fixed to the idler roller 17 by a bracket. A center mark is pre-marked on the center position of the baffle 21. Then, a laser emitter 20 is temporarily fixedly installed at the end of the steel pipe fixing mechanism (i.e., at the left end face of the guide rod 16). The laser emitter 20 is installed at the left end of the guide rod 16 through a transition connecting sleeve, ensuring that the laser beam emitted by the laser emitter 20 coincides with the axis of the positioning rod 5. The laser emitter 20 is turned on, and the laser beam is shot towards the baffle 21 along the axial direction of the positioning rod 5. The operator observes the position of the laser spot on the baffle 21. If the laser spot does not fall on the center mark of the baffle 21, the horizontal position and vertical height of the idler roller 17 are adjusted until the laser spot accurately hits the center mark on the baffle 21. At this time, it indicates that the position adjustment of the idler roller 17 is complete. After adjustment, remove the laser emitter 20 and the baffle 21 to proceed with the subsequent steel pipe placement operation. This calibration step ensures that the centerline of the middle section of the steel pipe 7 is approximately collinear with the rotation axis of the cutter head 3 after it is placed on the roller 17, providing a prerequisite for subsequent precise positioning.

[0060] S2. Steel Pipe Placement and Fixing Mechanism Insertion Step. The large-diameter thin-walled steel pipe 7 to be processed is transported to the chamfering machine station of this invention via a conveying device such as a crane or a steel pipe transverse conveying trolley. The steel pipe 7 is placed horizontally on the idler roller 17, and the V-shaped groove of the idler roller 17 provides support and initial centering for the middle section of the steel pipe 7. Then, the steel pipe 7 is moved axially so that the right end of the steel pipe 7 is gradually fitted onto the steel pipe fixing mechanism, so that the steel pipe fixing mechanism extends into the inside of the right end of the steel pipe 7. During this process, it is necessary to ensure that the end of the steel pipe 7 passes through the annular sleeve 8 and the top block 9, so that the annular sleeve 8 and the six top blocks 9 are completely located inside the end of the steel pipe 7. At this time, there is still a gap between the inside of the right end of the steel pipe 7 and the steel pipe fixing mechanism, and the steel pipe 7 is not yet fixed.

[0061] S3. Rounding and Coaxial Positioning Steps. Start the hydraulic cylinder 12, causing it to drive the movable rod 10 to move axially to the left. As the movable rod 10 moves to the left, it drives the tapered rod 11, which is fixedly connected to it, to move synchronously to the left. During the leftward movement of the tapered rod 11, its tapered surface gradually pushes against the wedge-shaped inner end faces of the six top blocks 9. Because the tapered surface of the tapered rod 11 gradually expands from left to right, the six top blocks 9 expand synchronously outward along the radial direction of the annular sleeve 8 under the pushing action of the tapered rod 11. During the synchronous outward expansion of the six top blocks 9, the arc-shaped surfaces at the outer ends of each top block 9 simultaneously contact and push against the inner wall surface of the right end of the steel pipe 7. Since the six top blocks 9 are evenly distributed circumferentially, the pushing force they exert on the inner wall of the steel pipe 7 is uniformly symmetrical in the circumferential direction. This uniformly distributed radial pushing force can gradually correct the elliptical deformation or local concavity of the end of the steel pipe 7 into a regular circular cross-section, achieving rounding of the end of the steel pipe 7. Simultaneously, as the six top blocks 9 expand synchronously and evenly press against the inner wall of the steel pipe 7, the axis of the steel pipe 7 automatically coincides with the axis of the annular sleeve 8 under the constraint of the top blocks 9. The annular sleeve 8 is fixed on the positioning rod 5, and the axis of the positioning rod 5 coincides with the rotation axis of the cutter head 3. Therefore, the axis of the steel pipe 7 and the rotation axis of the cutter head 3 are precisely coincident at this moment, completing coaxial positioning. The hydraulic cylinder 12 maintains pressure, keeping the six top blocks 9 pressed against the inner wall of the steel pipe 7. At this time, the friction between the top blocks 9 and the inner wall of the steel pipe 7 is very large, which is sufficient to withstand the moving resistance of the steel pipe 7 during the subsequent dragging process without relative slippage. Therefore, the steel pipe 7 is also firmly internally supported and fixed while being rounded and positioned.

[0062] S4. Feeding Step. The drive mechanism mounted on the base 1 is activated, driving the adjusting slide 6 to move to the right along the axial direction of the positioning rod 5. Since the positioning rod 5, annular sleeve 8, tapered rod 11, top block 9, and hydraulic cylinder 12 are all directly or indirectly fixedly connected to the adjusting slide 6, when the adjusting slide 6 moves to the right, it drives all the aforementioned components and the steel pipe 7, which is firmly fixed to the top block 9, to move to the right together. During the movement of the steel pipe 7 to the right, its right end gradually approaches the cutter head 3 and the cutting tool 4. By precisely controlling the feed amount of the drive mechanism, the position of the end of the steel pipe 7 relative to the cutting tool 4 can be precisely controlled, allowing the right end of the steel pipe 7 to move to the pre-processing position of the cutting tool 4. At this time, the relative position between the end of the steel pipe 7 and the cutting tool 4 meets the initial cutting requirements for chamfering.

[0063] S5, chamfering process. (For example...) Figure 6As shown, the chamfering power mechanism is activated, driving the cutter head 3 to rotate at high speed around its rotation axis. The rotation of the cutter head 3 causes the two cutters 4 fixed on it to rotate synchronously. Since the steel pipe 7 has achieved precise coaxial positioning with the rotation axis of the cutter head 3 in step S3, the cutting allowance of the rotating cutter 4 on the end of the steel pipe 7 is uniform in the circumferential direction, preventing uneven cutting due to axial deviation. Simultaneously with the rotation of the cutter head 3, the drive mechanism continues to drive the adjusting slide 6 to move slowly to the right according to the preset feed rate and feed amount, gradually feeding the end of the steel pipe 7 towards the rotating cutter 4. During rotation, the cutter 4 continuously cuts the material at the end of the steel pipe 7, forming a predetermined chamfer shape at the outer edge of the end of the steel pipe 7. Because the cutting process is carried out under the condition that the end of the steel pipe 7 has been rounded and the axis has been precisely aligned, the resulting chamfer edge is regular and uniform, preventing through-bevel defects caused by elliptical deformation of the steel pipe end.

[0064] After the chamfering is completed, the chamfering power mechanism is stopped, and the cutter head 3 stops rotating. The hydraulic cylinder 12 reverses its action, driving the movable rod 10 to move to the right, which in turn moves the tapered rod 11 to the right to reset. Under the elastic restoring force of the fixed ring 13 and its own gravity, the six top blocks 9 retract radially inward to reset, releasing the clamping effect on the inner wall of the steel pipe 7. At this time, the steel pipe 7 is no longer fixed to the steel pipe fixing mechanism, and the steel pipe 7 with one end processed can be lifted from the support roller 17. The steel pipe 7 is rotated 180° and then placed back on the support roller 17, so that the other end of the steel pipe 7 that is not processed (i.e., the left end) faces the steel pipe fixing mechanism. Then, the above steps S2 to S5 are repeated to perform the same rounding, positioning, and chamfering processing on this end.

[0065] In summary, the chamfering machine and method for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes provided by this invention have the following significant advantages over existing technologies: Structurally, this invention directly mounts the steel pipe fixing mechanism on the positioning rod 5, which is coaxially fixed with the cutter head 3. This achieves structural coaxial integration between the fixing mechanism and the tool system, fundamentally eliminating the axial deviation problem caused by the independent clamping mechanism and tool system in traditional solutions. It eliminates the need for tedious manual alignment adjustments before each processing step, significantly shortening auxiliary time and improving production efficiency. Functionally, the steel pipe fixing mechanism of this invention simultaneously performs rounding and coaxial positioning on the ends of the steel pipe 7, achieving a dual purpose in one action. It eliminates inherent defects such as elliptical deformation and uneven wall thickness at the ends of large-diameter thin-walled steel pipes, while ensuring precise alignment of the processing axis. Furthermore, the entire rounding and positioning process is achieved by the synchronous movement of six top blocks 9 driven by the hydraulic cylinder 12, resulting in simple operation, rapid response, and high repeatability. Moreover, the present invention, through the pre-calibration step of the laser emitter 20 cooperating with the baffle 21, can ensure that the middle section axis of the long steel pipe 7 supported by the roller 17 is also collinear with the rotation axis of the cutter head 3, effectively overcoming the problem of the far end axis deviation caused by the steel pipe 7 sagging due to its own weight, and ensuring the axial consistency of the entire steel pipe 7 in the length direction.

[0066] Applying this technical solution to actual production can directly replace the traditional processing mode of first cutting the end and then chamfering, significantly reducing the material loss rate in the processing of large-diameter thin-walled steel pipe ends. Several centimeters of end material can be saved at each end of each steel pipe, resulting in considerable cost savings for steel pipe manufacturers producing in batches. Simultaneously, due to the significantly improved chamfering accuracy, the processed steel pipe ends have regular and uniform edges, ensuring an ideal Y-shaped gap when two steel pipes are welded together. The weld scar is full and smoothly transitions to the inner wall of the steel pipe, completely eliminating the problem of raised weld scars on the inner wall caused by chamfering deviation. This is of great significance for the long-term safe operation of gaseous fluid transportation pipelines such as natural gas. Furthermore, the cutter head 3 of this invention is equipped with a radial adjustment structure for the cutter, where a T-slot 19 and a T-block 18 cooperate, allowing the same equipment to quickly adapt to the processing needs of steel pipes of different diameters. The equipment has strong versatility and good market application prospects.

[0067] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified. The above embodiments are preferred implementations of this invention. In addition, this invention can be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this invention.

Claims

1. A chamfering machine for rounding and coaxially positioning the ends of large-diameter thin-walled steel pipes, comprising a base (1) and a tool holder (2) disposed on the base (1), wherein a cutter disc (3) is disposed at one end of the tool holder (2), and a chamfering tool (4) is disposed on the cutter disc (3), and a chamfering power mechanism for driving the cutter disc (3) to rotate is disposed inside the tool holder (2), characterized in that, Also includes: A positioning rod (5) is inserted through the tool holder (2). The axis of the positioning rod (5) coincides with the rotation axis of the tool disc (3), and the tool disc (3) can rotate relative to the positioning rod (5). Adjustable slide (6) is slidably connected to the base (1), and one end of the positioning rod (5) is fixed to the adjustable slide (6); The steel pipe fixing mechanism is connected to the other end of the positioning rod (5) that passes through the center of the cutter head (3). The steel pipe fixing mechanism can extend into the end port of the steel pipe (7) and expand outward to achieve full circle and coaxial positioning of the end of the steel pipe (7). It also includes a roller (17) set below the middle section of the steel pipe (7). The roller (17) is a V-shaped roller and its position can be adjusted in both the horizontal and vertical directions. Before placing the steel pipe (7) on the roller (17), a baffle (21) carrying the center mark point is set above the roller (17), and a laser emitter (20) is temporarily fixed at the end of the steel pipe fixing mechanism so that the laser emitted by the laser emitter (20) is coaxial with the positioning rod (5). The position of the roller (17) is adjusted until the laser hits the center mark point to pre-calibrate the axis of the steel pipe (7) and the rotation axis of the cutter head (3). The center mark point corresponds to the theoretical position of the axis of the steel pipe (7) when the steel pipe (7) to be processed is placed on the roller (17).

2. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 1, characterized in that, The steel pipe fixing mechanism includes: An annular sleeve (8) is fixed to the other end of the positioning rod (5) that passes through the center of the cutter head (3), and its outer diameter is smaller than the inner diameter of the steel pipe (7) to be processed; Multiple top blocks (9) are arranged circumferentially around the annular sleeve (8). The top blocks (9) penetrate the side wall of the annular sleeve (8) and can extend and retract in the radial direction of the annular sleeve (8). The movable rod (10) is coaxially and movably disposed inside the positioning rod (5) in the hollow structure; A tapered rod (11) is coaxially disposed inside the annular sleeve (8). One end of the tapered rod (11) is fixedly connected to one end of the movable rod (10). The tapered surface of the tapered rod (11) is matched with the inner end of each of the top blocks (9). The oil cylinder (12) is connected to the other end of the movable rod (10). The oil cylinder (12) is fixed on the adjusting slide (6) and is used to drive the movable rod (10) to move axially, thereby driving the tapered rod (11) to push each of the top blocks (9) to expand outward synchronously.

3. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 2, characterized in that: It also includes a drive mechanism disposed on the base (1) for driving the adjusting slide (6) to move axially along the positioning rod (5).

4. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 2, characterized in that: The end of the annular sleeve (8) away from the positioning rod (5) is coaxially fixed with a support guide ring (15), and the end of the tapered rod (11) away from the movable rod (10) is coaxially fixed with a guide rod (16). The guide rod (16) passes through the support guide ring (15) and slides with the inner wall of the support guide ring (15).

5. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 2, characterized in that: The number of the top blocks (9) is six, and the six top blocks (9) are evenly spaced along the circumference of the annular sleeve (8).

6. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 2, characterized in that: The steel pipe fixing mechanism also includes a fixing ring (13) with a notch. The fixing ring (13) is made of a material with elastic deformation capability. Each top block (9) has a through hole (14) at the part located outside the annular sleeve (8). The fixing ring (13) passes through each through hole (14) in sequence to limit the connection of each top block (9).

7. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 2, characterized in that: The end face of the cutter head (3) is provided with six T-shaped grooves (19) spaced apart circumferentially. The T-shaped grooves (19) extend along the radial direction of the cutter head (3) and one end extends to the outer peripheral surface of the cutter head (3) to form an opening. The cutter (4) is fixed on the T-shaped block (18). The T-shaped block (18) is slidably fitted into the T-shaped groove (19) and fixed by bolts.

8. The chamfering machine for rounding and coaxial positioning the ends of large-diameter thin-walled steel pipes according to claim 7, characterized in that: There are two T-shaped blocks (18), which are symmetrically distributed on two T-shaped grooves (19), and each T-shaped block (18) is fixed with a cutting tool (4).

9. A method for chamfering large-diameter thin-walled steel pipe ends using a chamfering machine with end-rounding and coaxial positioning as described in claim 4, characterized in that... Includes the following steps: S1. Before placing the steel pipe (7) on the idler roller (17), a baffle (21) is set above the idler roller (17), and a laser emitter (20) is temporarily fixed at the end of the steel pipe fixing mechanism so that the laser emitted by the laser emitter (20) is coaxial with the positioning rod (5). The position of the idler roller (17) is adjusted until the laser hits the center mark on the baffle (21). Then the laser emitter (20) is removed. The center mark corresponds to the theoretical position of the axis of the steel pipe (7) when the steel pipe (7) is placed on the idler roller (17). S2. Fit one end of the steel pipe (7) onto the steel pipe fixing mechanism, so that the steel pipe fixing mechanism extends into the end of the pipe. S3. Start the oil cylinder (12) to drive the movable rod (10) and the conical rod (11) to move, so that each top block (9) expands outward synchronously and presses against the inner wall of the end of the steel pipe (7) from the inside, rounding the end of the steel pipe (7) and making the axis of the steel pipe (7) coincide with the rotation axis of the cutter head (3); S4. Start the drive mechanism to drive the adjusting slide (6) to move away from the cutter head (3), and drive the steel pipe (7) to move towards the cutter head (3) through the steel pipe fixing mechanism, so that the end of the steel pipe (7) moves to the processing position of the cutter (4); S5. Start the chamfering power mechanism to drive the cutter head (3) to rotate, so that the cutter (4) can chamfer the end of the steel pipe (7).

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