A pipe expander and method for expanding a hot rolled seamless steel pipe

Abstract

The present application relates to the technical field of seamless steel pipe processing, in particular to a diameter expanding device suitable for hot-rolled seamless steel pipe and a diameter expanding method thereof, comprising a machine tool and a steel pipe clamp, wherein a diameter expanding assembly is arranged on the left side of the machine tool, the diameter expanding assembly comprises a plurality of flat support plates regularly distributed in a ring shape and a plurality of inclined support plates hingedly connected to the right ends of the flat support plates one by one, and a diameter changing structure is arranged at the horizontal axis of the flat support plates. The diameter changing structure comprises a first motor, a shaft and a sliding tube, the left end of the shaft is a threaded part, and the sliding tube is threadedly connected to the threaded part. The present application sets the diameter changing structure to adapt to the requirements of different diameter expanding sizes, and the diameter expanding head does not need to be repeatedly replaced, thereby improving the adaptability.

Description

Technical Field

[0001] This invention belongs to the field of seamless steel pipe processing technology, specifically a diameter expansion device and method suitable for hot-rolled seamless steel pipes. Background Technology

[0002] Hot-rolled seamless steel pipes are hollow steel pipes made by heating a billet, piercing it, and then rolling it through a continuous rolling mill. After rolling, the pipes are cooled to room temperature by water or air, and then straightened, cut off, and inspected to form the final product. However, due to equipment limitations or to meet customized requirements, hot-rolled seamless steel pipes often need to be expanded in diameter after production to meet specific application needs.

[0003] For example, the invention patent with publication number CN119456836A discloses a diameter expansion device and its process for hot-rolled seamless steel pipes in the field of seamless steel pipe processing technology. The device includes a frame and a positioning assembly. The diameter expansion assembly is mounted at one end of the frame, and the positioning assembly is located at the rear of the diameter expansion assembly. The positioning assembly includes a synchronizing rod, a lifting plate, a limiting plate, a limiting strip, an elongated hole, a lifting frame, a guide hole, a driving rod, and a clamping plate. In this invention, when the driving seat pulls the diameter expansion head to expand the steel pipe's diameter via the pull rod, the driving seat also drives the limiting plate to slide via the synchronizing rod and the lifting plate. At this time, because the guide hole on the lifting frame restricts the movement direction of the driving rod, it can only move vertically. Therefore, the height of the driving rod can be controlled through the elongated hole, so that the clamping plate can be used to clamp and position the steel pipe. Since the protrusion in the middle of the elongated hole is located at the diameter expansion head, the clamping plate near the diameter expansion head will automatically loosen, preventing the steel pipe from being subjected to external pressure during diameter expansion and affecting the expansion effect.

[0004] Based on the above cases and actual situations, we have identified the following problems: Cold expansion is typically used for hot-rolled seamless steel pipes with thin walls, small diameters, and high precision. In cold expansion, an expansion head is usually inserted directly into the hot-rolled seamless steel pipe. However, the diameter of the expansion head is usually fixed, requiring replacement of the expansion head when different diameters are needed, which is cumbersome and has low adaptability. Furthermore, lubricating oil is usually applied inside the hot-rolled seamless steel pipe during cold expansion. However, during the expansion process, the expansion head is in close contact with the inner wall of the hot-rolled seamless steel pipe, and the pre-applied lubricating oil may be squeezed out during the movement of the expansion head, failing to penetrate the area between the expansion head and the inner wall of the hot-rolled seamless steel pipe, thus affecting the expansion effect. Summary of the Invention

[0005] The purpose of this invention is to provide a diameter expansion device and method suitable for hot-rolled seamless steel pipes. By setting a diameter-changing structure, the position of the flat support plate and the inclined support plate is changed to achieve diameter change to meet the diameter expansion needs. At the same time, by setting a lubrication structure, lubricating oil is directly squeezed into the space between the flat support plate and the inner wall of the hot-rolled seamless steel pipe to improve the lubrication effect, thereby solving the above-mentioned problems of the prior art.

[0006] To achieve the above objectives, the present invention provides a diameter expansion device suitable for hot-rolled seamless steel pipes, including a machine tool and a steel pipe clamp installed on the right side of the machine tool for clamping and fixing the hot-rolled seamless steel pipe. The left side of the machine tool is provided with a diameter expansion component for expanding the diameter of the hot-rolled seamless steel pipe. The diameter expansion component includes a plurality of flat support plates arranged in a regular ring and a plurality of inclined support plates that are hinged to the right ends of the plurality of flat support plates. A diameter-changing structure for changing the diameter expansion size is provided at the horizontal axis of the plurality of flat support plates.

[0007] The variable diameter structure includes a first motor, a shaft coaxially fixedly connected to the first motor, and a sliding tube sleeved on the left end of the shaft. The left end of the shaft is divided into a threaded part, and the sliding tube is threadedly connected to the threaded part. The inner plate of the flat support plate is provided with two sets of left and right support rods. The outer end of the support rod is slidably connected to a slide rod, and the outer end of the slide rod is fixedly connected to the corresponding inner plate of the flat support plate. The middle section of the shaft is sleeved with a connecting sleeve, and the two are slidably connected. Several support rods are fixedly connected to the corresponding ends of the outer surface of the same connecting sleeve. The right end face of the sliding tube is embedded in the left end face of the connecting sleeve, and the two are rotatably connected. The right end of the shaft is provided with a connecting block, and the shaft is embedded in the left end face of the connecting block, and the two are rotatably connected. The right end of the inclined support plate is hinged to the side wall of the connecting block.

[0008] In this design, considering equipment limitations or customized requirements, hot-rolled seamless steel pipes often require diameter expansion after production to meet usage needs. This is typically achieved through either cold or hot expansion. Cold expansion is generally used for hot-rolled seamless steel pipes with thinner walls, smaller diameters, and higher precision. In cold expansion, an expansion head is usually inserted directly into the hot-rolled seamless steel pipe. However, the diameter of the expansion head is usually fixed, requiring replacement when different diameters are needed, which is cumbersome and has low adaptability. Therefore, this technical solution incorporates a variable diameter structure to accommodate different expansion sizes, eliminating the need for repeated head replacements and improving adaptability.

[0009] In the technical solution of the present invention, the machine tool is provided with a control panel on the left side, and a hydraulic cylinder is fixed at the right end of the control panel. The telescopic shaft of the hydraulic cylinder is fixedly connected to a fixed barrel, and the first motor is fixed in the middle of the left inner wall of the fixed barrel.

[0010] In this setup, the electrical structure is controlled via a control panel, and the entire diameter expansion assembly is moved and expanded using hydraulic cylinders.

[0011] In the technical solution of the present invention, a plurality of the flat support plates are cylindrical in shape with an axial horizontal orientation, and a plurality of the inclined support plates are conical in shape with an axial horizontal orientation. The axes of the cylindrical formed by the flat support plates and the conical formed by the inclined support plates are located on the same horizontal line. The left end of the inclined support plate is an arc-shaped surface, and the center of the arc-shaped surface coincides with the rotation center of the corresponding hinge point of the flat support plate and the inclined support plate.

[0012] In this setup, the axes of the horizontal barrel formed by the flat bracing plate and the horizontal cone formed by the inclined bracing plate are located on the same horizontal line to ensure the quality of the diameter expansion and avoid eccentricity that could damage the hot-rolled seamless steel pipe. By setting the center of the arc surface to coincide with the rotation center of the corresponding hinge point of the flat bracing plate and the inclined bracing plate, it is ensured that when the inclined bracing plate rotates, the horizontal line of the middle part of the flat bracing plate is always tangent to the left edge of the inclined bracing plate, thus ensuring a smooth transition between the inclined bracing plate and the flat bracing plate.

[0013] In the technical solution of the present invention, a connecting plate is slidably connected to the shaft, an insert plate is fixed to the left end of the inner plate surface of the flat support plate, a plurality of slots are provided along the plate wall of the connecting plate, a plurality of insert plates correspond one-to-one with a plurality of slots, the insert plate is inserted into the corresponding slot and the two are slidably connected, a limit rod is symmetrically fixed at the left end of the tube wall of the sliding tube, a limit groove corresponding to the limit rod is provided on the tube wall of the fixed barrel, the outer end of the limit rod passes through the corresponding limit groove and the two are slidably connected.

[0014] In this setup, the flat support plate is further restricted by the connecting plate, insert plate, and slot to prevent the flat support plate from sliding and thus preventing the diameter from being expanded. The sliding tube is restricted by the limit rod to prevent the sliding tube from being unable to slide when the shaft rotates.

[0015] In the technical solution of the present invention, the fixed barrel is provided with a rotating structure. The rotating structure includes a second motor fixed to the upper part of the left inner wall of the fixed barrel, an active tooth coaxially arranged with the second motor, and a driven tooth meshing with the active tooth. A rotating seat is coaxially fixed to the left side of the connecting plate. The driven tooth is coaxially fixedly connected to the left end of the rotating seat. The right end of the rotating seat passes through the right end of the fixed barrel wall and is coaxially fixedly connected to the connecting plate.

[0016] In this configuration, by setting up a rotating structure, during the diameter expansion, the second motor is started to drive the active and driven teeth to rotate, which in turn drives the rotating seat to rotate. Under the action of the connecting plate, the flat support plate and the inclined support plate are driven to rotate, thus expanding the diameter evenly.

[0017] In the technical solution of the present invention, a protective shell is provided inside the fixed barrel, the active tooth and the driven tooth are disposed inside the protective shell, the left and right side walls of the active tooth and the driven tooth are respectively attached to the left and right inner walls of the protective shell, and horizontal beams are symmetrically fixed on the upper and lower parts of the fixed barrel, the beams pass through the corresponding ends of the protective shell and the two are slidably connected.

[0018] In this configuration, by setting a protective shell, when the flat support plate expands outward, the flat support plate will also slide to the right, causing the rotating seat and the protective shell to slide to the right synchronously, thereby causing the driving gear to slide to the right synchronously.

[0019] In the technical solution of the present invention, a plug rod is coaxially fixedly connected to the left side of the active tooth. The plug rod is inserted into the output shaft of the second motor. The inner wall of the output shaft is provided with a plurality of protrusions. The plug rod wall is provided with a plurality of protrusion grooves corresponding to the protrusions. The protrusions are embedded in the protrusion grooves and the two are slidably connected.

[0020] In this configuration, by setting up bumps and bump slots, not only can the second motor drive the active gear to rotate, but the active gear can also slide.

[0021] In the technical solution of the present invention, the fixed barrel is provided with a lubrication structure. The lubrication structure includes a storage cavity disposed in the rotating seat, a plurality of first oil supply pipes communicating with the storage cavity, and a second oil supply pipe corresponding to each of the plurality of first oil supply pipes. The plurality of first oil supply pipes are disposed in a corresponding manner with the plurality of flat support plates. The first oil supply pipes and the corresponding second oil supply pipes are connected by a pipe expansion joint. The first oil supply pipes horizontally pass through the corresponding support rods and are fixedly connected. The second oil supply pipes are vertically disposed, and the outer end of the second oil supply pipes passes through the corresponding flat support plate. The outer end of the second oil supply pipes is flush with the outer surface of the flat support plate.

[0022] In this setup, the pipe expansion joint is installed to prevent the pipe from expanding radially during oil delivery, thus preventing the lubricating oil from being squeezed out. The outer end of the second oil delivery pipe is flush with the outer surface of the flat support plate to prevent the port of the second oil delivery pipe from blocking the rotation of the flat support plate. The outer end of the second oil delivery pipe is located at the right end of the flat support plate to ensure timely oil delivery for lubrication when the flat support plate moves to the right.

[0023] In the technical solution of the present invention, a piston plate is provided in the storage cavity, and a threaded tube is coaxially fixed to the left end of the piston plate. The threaded tube passes through the left side wall of the rotating seat and the two are slidably connected. A sleeve is fixed in the middle of the fixed barrel. The sleeve is fitted over the threaded tube and the two are threadedly connected. The piston plate has an outwardly protruding flange on its edge, and the inner wall of the storage cavity has a flange groove.

[0024] In this configuration, by setting up a piston plate, a threaded tube, and a sleeve, when the rotating seat rotates, the threaded tube rotates synchronously and, under the action of the sleeve, pushes the piston plate to slide to the right relative to the storage cavity, thereby slowly squeezing the lubricating oil between the flat support plate and the inner wall of the hot-rolled seamless steel pipe for lubrication.

[0025] On the other hand, the present invention also provides a method for expanding the diameter of hot-rolled seamless steel pipes, comprising the following steps:

[0026] S1. Place the hot-rolled seamless steel pipe on the steel pipe clamp and fix it in place, and adjust the height of the hot-rolled seamless steel pipe to match the height of the expansion assembly.

[0027] S2. After the hot-rolled seamless steel pipe is fixed, the first motor is started to drive the shaft to rotate. Under the action of the threaded part, the sliding tube slides to the right, which in turn pushes the connecting sleeve, support rod and flat support plate to slide to the right, so that the diagonal support plate rotates clockwise to the right. The clockwise rotation of the diagonal support plate will drive the left flat support plate to expand outward, thereby realizing the change of the expansion size to adapt to the expansion needs.

[0028] S3. After the diameter change is completed, apply lubricating oil to the left end of the hot-rolled seamless steel pipe. Then start the hydraulic cylinder to drive the entire expansion assembly to slowly move to the right to expand the diameter until the second oil pipe enters the hot-rolled seamless steel pipe. At this time, stop the expansion and introduce lubricating oil into the storage cavity.

[0029] S4. After the lubricating oil is filled, close the oil inlet, restart the hydraulic cylinder, and at the same time start the second motor to drive the drive gear and driven gear to rotate, thereby driving the rotating seat to rotate. Under the action of the connecting plate, the flat support plate and the inclined support plate will rotate to expand the diameter.

[0030] S5. When the rotating seat rotates, the threaded pipe rotates synchronously and pushes the piston plate to slide to the right relative to the storage cavity under the action of the sleeve, thereby slowly squeezing the lubricating oil between the flat support plate and the inner wall of the hot-rolled seamless steel pipe for lubrication.

[0031] S6. After the diameter expansion is completed, turn off the second motor, start the first motor to drive the shaft to reverse and cause the flat support plate to retract inward. Then, start the hydraulic cylinder to drive the entire diameter expansion assembly to move to the left and exit the hot-rolled seamless steel pipe to complete the diameter expansion.

[0032] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0033] 1. In this invention, by setting a variable diameter structure, a flat support plate and a diagonal support plate, the first motor is started during the diameter expansion to drive the shaft to rotate. Under the action of the threaded part, the sliding tube slides to the right, which in turn pushes the connecting sleeve, the support rod and the flat support plate to slide to the right, so that the diagonal support plate rotates clockwise to the right. The clockwise rotation of the diagonal support plate will drive the flat support plate to expand outward, thereby realizing the change of the diameter expansion size to adapt to the diameter expansion needs, without the need to repeatedly replace the diameter expansion head, thus improving adaptability.

[0034] 2. In this invention, by setting a lubrication structure, when the second motor is started to drive the flat support plate and the inclined support plate to rotate and uniformly expand the diameter, the rotating seat rotates synchronously and drives the threaded pipe to rotate synchronously. Under the action of the sleeve, the piston plate is pushed to slide to the right relative to the storage cavity, thereby slowly squeezing the lubricating oil from the second oil delivery pipe to the space between the flat support plate and the inner wall of the hot-rolled seamless steel pipe for lubrication, thereby improving the lubrication effect. Attached Figure Description

[0035] Figure 1 This is a simplified schematic diagram of the overall structure of the present invention;

[0036] Figure 2 This is a schematic diagram of the overall diameter expansion assembly of the present invention;

[0037] Figure 3 This is a schematic diagram of the internal structure of the diameter expansion component in this invention;

[0038] Figure 4 This is a schematic diagram of the flat bracing plate and the diagonal bracing plate in this invention;

[0039] Figure 5 This is a schematic diagram of the variable diameter structure and the rotating structure in this invention;

[0040] Figure 6 This is a schematic diagram of the variable diameter structure in this invention;

[0041] Figure 7 This is a cross-sectional view of the support rod in this invention;

[0042] Figure 8 This is an exploded view of the lubrication structure in this invention;

[0043] Figure 9 This is a cross-sectional view of the lubrication structure in this invention;

[0044] Figure 10 This is an exploded view of the second motor and the drive gear in this invention;

[0045] Explanation of reference numerals in the attached figures:

[0046] 100. Machine tool; 101. Control panel;

[0047] 200. Expanding diameter assembly; 201. Hydraulic cylinder; 202. Flat support plate; 2021. Insert plate; 203. Diagonal support plate; 204. Support rod; 2041. Slide rod; 2042. Connecting sleeve; 205. Connecting plate; 2051. Slot; 206. Fixed barrel; 207. Connecting block; 210. Variable diameter structure; 211. First motor; 212. Shaft; 213. Threaded part; 214. Sliding tube; 215. Limiting rod; 220. Rotating structure; 221. Second motor; 222. Driving gear; 223. Driven gear; 224. Insert rod; 225. Protrusion; 226. Rotating seat; 230. Lubrication structure; 231. Storage cavity; 232. Threaded tube; 233. Piston plate; 234. Tube sleeve; 235. First oil supply pipe; 236. Second oil supply pipe; 237. Pipe expansion joint;

[0048] 300. Steel pipe clamps. Detailed Implementation

[0049] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0050] Unless otherwise expressly stated, throughout this specification, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0051] Reference Figures 1-10 As shown, this embodiment provides a technical solution:

[0052] An expansion device for hot-rolled seamless steel pipes includes a machine tool 100 and a steel pipe clamp 300 mounted on the right side of the machine tool 100 for clamping and fixing the hot-rolled seamless steel pipe. An expansion assembly 200 for expanding the diameter of the hot-rolled seamless steel pipe is provided on the left side of the machine tool 100. The expansion assembly 200 includes a plurality of flat support plates 202 arranged in a ring and a plurality of inclined support plates 203 that are hinged to the right ends of the plurality of flat support plates 202. A variable diameter structure 210 for changing the expansion size is provided at the horizontal axis of the plurality of flat support plates 202. It should be noted that the upper and lower clamping blocks of the steel pipe clamp 300 can move up and down respectively to ensure that the axis of the hot-rolled seamless steel pipe and the axis of the expansion assembly 200 are at the same height during expansion. This is prior art and will not be described in detail here.

[0053] Due to equipment limitations or to meet customized requirements, hot-rolled seamless steel pipes often require diameter expansion after production to meet specific needs. This is typically achieved through either cold or hot expansion. Cold expansion is generally used for hot-rolled seamless steel pipes with thinner walls, smaller diameters, and higher precision. In cold expansion, an expansion head is usually inserted directly into the hot-rolled seamless steel pipe. However, the diameter of the expansion head is usually fixed, requiring replacement when different diameters are needed, which is cumbersome and has low adaptability. Therefore, this technical solution incorporates a variable diameter structure 210 to accommodate different expansion sizes, eliminating the need for repeated head replacements and improving adaptability.

[0054] The variable diameter structure 210 includes a first motor 211, a shaft 212 coaxially and fixedly connected to the first motor 211, and a sliding tube 214 sleeved on the left end of the shaft 212. It should be noted that the first motor 211 is a servo motor with a brake system. When the first motor 211 is closed, the shaft 212 cannot rotate. This is prior art and will not be described in detail here. The left end of the shaft 212 is divided into a threaded part 213. The sliding tube 214 is threadedly connected to the threaded part 213. The inner plate of the flat support plate 202 is provided with two sets of left and right support rods 204. The outer end of the support rod 204 is slidably connected to the slide rod 2041. The outer end of the slide rod 2041 is fixedly connected to the corresponding inner plate of the flat support plate 202. The middle section of the shaft 212 is fitted with a connecting sleeve 2042 and the two are slidably connected. Several support rods 204 are fixedly connected to the corresponding ends of the outer surface of the same connecting sleeve 2042. The right end face of the sliding tube 214 is embedded in the left end face of the connecting sleeve 2042 and the two are rotatably connected. The right end of the shaft 212 is provided with a connecting block 207. The shaft 212 is embedded in the left end face of the connecting block 207 and the two are rotatably connected. The right end of the inclined support plate 203 is hinged to the side wall of the connecting block 207. When it is necessary to change the size of the expansion, the first motor 211 is started to drive the shaft 212 to rotate. Under the action of the threaded part 213, the sliding tube 214 slides to the right, which in turn pushes the connecting sleeve 2042, the support rod 204 and the flat support plate 202 to slide to the right, so that the inclined support plate 203 rotates clockwise to the right. The clockwise rotation of the inclined support plate 203 will drive the flat support plate 202 to expand outward, thereby realizing the change of the expansion size to adapt to the expansion needs.

[0055] When the inclined brace 203 contacts the hot-rolled seamless steel pipe, the pipe opening of the hot-rolled seamless steel pipe applies a horizontal force to the left to the inclined brace 203, causing the inclined brace 203 to tend to rotate counterclockwise around the hinge of the connecting block 207. Due to the restriction of the sliding tube 214, the connecting sleeve 2042 cannot slide to the left. At this time, the flat brace 202 cannot descend, and the inclined brace 203 cannot rotate counterclockwise, thus achieving diameter expansion. When the flat brace 202 contacts the inner wall of the hot-rolled seamless steel pipe, the flat brace 202 still cannot descend, and diameter expansion can still be achieved. It should be noted that the flat brace 202, the inclined brace 203, the support rod 204, the sliding rod 2041, the connecting sleeve 2042, the shaft 212, the sliding tube 214, and the connecting block 207 are all made of high-strength wear-resistant materials such as alloy structural steel.

[0056] Please see Figures 1-3 As shown, a control panel 101 is provided on the left side of the machine tool 100, which controls the electrical structure. A hydraulic cylinder 201 is fixed to the right end of the control panel 101. The telescopic shaft of the hydraulic cylinder 201 is fixedly connected to a fixed barrel 206. A first motor 211 is fixed to the middle of the left inner wall of the fixed barrel 206. The hydraulic cylinder 201 drives the entire expansion assembly 200 to move and expand its diameter.

[0057] In addition, several flat support plates 202 are cylindrical in shape with an axial horizontal orientation, and several inclined support plates 203 are conical in shape with an axial horizontal orientation. The axes of the cylindrical formed by the flat support plates 202 and the conical formed by the inclined support plates 203 are located on the same horizontal line. The left end of the inclined support plate 203 is an arc-shaped surface, and the center of the arc-shaped surface coincides with the rotation center of the corresponding hinge point of the flat support plate 202 and the inclined support plate 203. This ensures that when the inclined support plate 203 rotates, the horizontal line of the middle part of the flat support plate 202 is always tangent to the left edge of the inclined support plate 203, thereby ensuring a smooth transition between the inclined support plate 203 and the flat support plate 202.

[0058] Please see Figures 3-7 As shown, a connecting plate 205 is slidably connected to the shaft 212, and an insert plate 2021 is fixed to the left end of the inner plate surface of the flat support plate 202. Several slots 2051 are provided along the plate wall of the connecting plate 205. Several insert plates 2021 correspond one-to-one with several slots 2051. The insert plate 2021 is inserted into the corresponding slot 2051 and the two are slidably connected. By setting the connecting plate 205, the insert plate 2021 and the slots 2051, the flat support plate 202 is further restricted, so as to prevent the cylindrical shape formed by the flat support plate 202 from sliding during the hot rolling of seamless steel pipe, which would prevent the diameter from being expanded.

[0059] In addition, the sliding tube 214 has symmetrically fixed limit rods 215 on the left end of the tube wall. The fixed barrel 206 has a limit groove on the barrel wall corresponding to the limit rod 215. The outer end of the limit rod 215 passes through the corresponding limit groove and the two are slidably connected. By setting the limit rod 215, the rotation of the sliding tube 214 is restricted, so as to avoid the inability to push the sliding tube 214 to slide when the shaft 212 rotates.

[0060] Please see Figures 8-9 As shown, the fixed barrel 206 is provided with a rotating structure 220. The rotating structure 220 includes a second motor 221 fixed to the upper part of the left inner wall of the fixed barrel 206, an active gear 222 coaxially arranged with the second motor 221, and a driven gear 223 meshing with the active gear 222. It should be noted that the second motor 221 is a servo motor with a brake system. When the second motor 221 is closed, the active gear 222 and the active gear 223 cannot rotate.

[0061] Specifically, a rotating seat 226 is coaxially fixed on the left side of the connecting plate 205. The driven tooth 223 is coaxially fixedly connected to the left end of the rotating seat 226. The right end of the rotating seat 226 passes through the right end of the fixed barrel 206 and is coaxially fixedly connected to the connecting plate 205. When expanding the diameter, the second motor 221 is started to drive the driving tooth 222 and the driven tooth 223 to rotate, which in turn drives the rotating seat 226 to rotate. Under the action of the connecting plate 205, the flat support plate 202 and the inclined support plate 203 are driven to rotate, thus expanding the diameter evenly.

[0062] In addition, a protective shell is provided inside the fixed barrel 206. The driving gear 222 and the driven gear 223 are disposed inside the protective shell. The left and right side walls of the driving gear 222 and the driven gear 223 are respectively attached to the left and right inner side walls of the protective shell. Horizontal beams are symmetrically fixed at the top and bottom of the fixed barrel 206. The beams pass through the corresponding ends of the protective shell and are slidably connected. The protective shell is fixedly connected to the rotating seat 226. By setting the protective shell, when the flat support plate 202 expands outward, the flat support plate 202 will also slide to the right, causing the rotating seat 226 and the protective shell to slide to the right synchronously, thereby causing the driving gear 222 to slide to the right synchronously.

[0063] Other examples Figure 10 As shown, a rod 224 is coaxially fixedly connected to the left side of the active gear 222. The rod 224 is inserted into the output shaft of the second motor 221. The inner wall of the output shaft is provided with several protrusions 225. The rod wall of the rod 224 is provided with several protrusion grooves that correspond one-to-one with the protrusions 225. The protrusions 225 are embedded in the protrusion grooves and the two are slidably connected. By setting the protrusions 225 and the protrusion grooves, not only can the second motor 221 drive the active gear 222 to rotate, but the active gear 222 can also slide.

[0064] During cold expansion of hot-rolled seamless steel pipes, lubricating oil is typically applied inside the pipe for lubrication. However, during the expansion process, the expanding head is in close contact with the inner wall of the pipe, and the pre-applied lubricating oil may be squeezed out during the movement of the expanding head, failing to penetrate the area between the expanding head and the inner wall of the pipe, thus affecting the expansion effect. Therefore, this technical solution, by setting up a lubrication structure 230, not only allows for lubrication during expansion but also directly squeezes the lubricating oil into the area between the flat support plate and the inner wall of the pipe, improving the lubrication effect.

[0065] Please see Figures 8-9 As shown, the fixed barrel 206 is provided with a lubrication structure 230. The lubrication structure 230 includes a storage cavity 231 disposed in the rotating seat 226, a plurality of first oil supply pipes 235 communicating with the storage cavity 231, and a plurality of second oil supply pipes 236 corresponding to the plurality of first oil supply pipes 235. It should be noted that the rotating seat 226 is provided with an oil inlet, and the fixed barrel 206 is provided with an opening for connecting the oil supply pipe, as shown in the figure. This is prior art and will not be described in detail here.

[0066] Specifically, a number of first oil delivery pipes 235 are provided in a one-to-one correspondence with a number of flat support plates 202. The first oil delivery pipes 235 and the corresponding second oil delivery pipes 236 are connected by a pipe expansion joint 237. The pipe expansion joint 237 is made of metal material and cannot expand radially, but can only expand axially. This avoids the pipe expansion joint 237 from expanding radially during oil delivery and thus failing to squeeze out the lubricating oil.

[0067] In addition, the first oil supply pipe 235 horizontally passes through the corresponding support rod 204 and the two are fixedly connected. The second oil supply pipe 236 is vertically set, and the outer end of the second oil supply pipe 236 passes through the corresponding flat support plate 202. The outer end of the second oil supply pipe 236 is flush with the outer surface of the flat support plate 202 to avoid the port of the second oil supply pipe 236 blocking the rotation of the flat support plate 202. The outer end of the second oil supply pipe 236 is set at the right end of the flat support plate 202 to ensure that oil is supplied in time for lubrication when the flat support plate 202 moves to the right.

[0068] In addition, a piston plate 233 is provided inside the storage cavity 231. A threaded tube 232 is coaxially fixed to the left end of the piston plate 233. The threaded tube 232 passes through the left side wall of the rotating seat 226 and the two are slidably connected. A sleeve 234 is fixed in the middle of the fixed barrel 206. The sleeve 234 and the inner wall of the fixed barrel 206 are welded together by a rod. This is prior art and will not be described in detail here. The sleeve 234 is fitted over the threaded tube 232 and the two are threaded together. The piston plate 233 has an outwardly protruding flange on its edge, and the inner wall of the storage cavity 231 has a flange groove. When the rotating seat 226 rotates, the threaded tube 232 rotates synchronously and, under the action of the sleeve 234, pushes the piston plate 233 to slide to the right relative to the storage cavity 231, thereby slowly squeezing the lubricating oil between the flat support plate 202 and the inner wall of the hot-rolled seamless steel pipe for lubrication.

[0069] It should be noted that the sealing connection between the threaded pipe 232 and the rotating seat 226 is like a mechanical seal sliding joint to avoid oil leakage. This is existing technology and will not be elaborated here. In addition, the rotating seat 226 has an opening in the middle for the connecting sleeve 2042 to slide.

[0070] The method for expanding the diameter of hot-rolled seamless steel pipes in this invention includes the following steps:

[0071] S1. Place the hot-rolled seamless steel pipe on the steel pipe clamp 300 and clamp it in place. Adjust the height of the hot-rolled seamless steel pipe to match the height of the expansion assembly 200.

[0072] S2. After the hot-rolled seamless steel pipe is fixed, the first motor 211 is started to drive the shaft 212 to rotate. Under the action of the threaded part 213, the sliding tube 214 slides to the right, which in turn pushes the connecting sleeve 2042, the support rod 204 and the flat support plate 202 to slide to the right, so that the inclined support plate 203 rotates clockwise to the right. The clockwise rotation of the inclined support plate 203 will drive the left flat support plate 202 to expand outward, thereby realizing the change of the expansion size to adapt to the expansion needs.

[0073] S3. After the diameter change is completed, apply lubricating oil to the left end of the hot-rolled seamless steel pipe. Then start the hydraulic cylinder 201 to drive the entire expansion assembly 200 to slowly move to the right to expand the diameter until the second oil pipe 236 enters the hot-rolled seamless steel pipe. At this time, stop the expansion and introduce lubricating oil into the storage chamber 231.

[0074] S4. After the lubricating oil is filled, the oil inlet is closed, the hydraulic cylinder 201 is restarted, and the second motor 221 is started to drive the active gear 222 and the driven gear 223 to rotate, which in turn drives the rotating seat 226 to rotate. Under the action of the connecting plate 205, the flat support plate 202 and the inclined support plate 203 are driven to rotate and the diameter is expanded.

[0075] S5. When the rotating seat 226 rotates, the threaded pipe 232 rotates synchronously and pushes the piston plate 233 to slide to the right relative to the storage cavity 231 under the action of the sleeve 234, thereby slowly squeezing the lubricating oil between the flat support plate 202 and the inner wall of the hot-rolled seamless steel pipe for lubrication.

[0076] S6. After the diameter expansion is completed, turn off the second motor 221, start the first motor 211 to drive the shaft 212 to reverse and cause the flat support plate 202 to retract inward. Then, start the hydraulic cylinder 201 to drive the entire diameter expansion assembly 200 to move to the left and exit the hot-rolled seamless steel pipe to complete the diameter expansion.

[0077] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the specification and its equivalents.

Claims

1. A diameter expansion device for hot-rolled seamless steel pipes, comprising a machine tool and a steel pipe clamp mounted on the right side of the machine tool for clamping and fixing the hot-rolled seamless steel pipe, characterized in that: The machine tool is provided with a diameter expansion assembly for expanding the diameter of hot-rolled seamless steel pipes on the left side. The diameter expansion assembly includes several flat support plates that are regularly distributed in a ring and several oblique support plates that are hinged to the right ends of the several flat support plates. A variable diameter structure for changing the diameter expansion size is provided at the horizontal axis of the several flat support plates. The variable diameter structure includes a first motor, a shaft coaxially fixedly connected to the first motor, and a sliding tube sleeved on the left end of the shaft. The left end of the shaft is divided into a threaded part, and the sliding tube is threadedly connected to the threaded part. The inner plate of the flat support plate is provided with two sets of left and right support rods. The outer end of the support rod is slidably connected to a sliding rod, and the outer end of the sliding rod is fixedly connected to the corresponding inner plate of the flat support plate. The middle section of the shaft is sleeved with a connecting sleeve, and the two are slidably connected. Several support rods are fixedly connected to the corresponding ends of the outer surface of the same connecting sleeve. The right end face of the sliding tube is embedded in the left end face of the connecting sleeve, and the two are rotatably connected. The right end of the shaft is provided with a connecting block, and the shaft is embedded in the left end face of the connecting block, and the two are rotatably connected. The right end of the inclined support plate is hinged to the side wall of the connecting block. The machine tool is provided with a control panel on the left side, and a hydraulic cylinder is fixed to the right end of the control panel. The telescopic shaft of the hydraulic cylinder is fixedly connected to a fixed barrel, and the first motor is fixed in the middle of the left inner wall of the fixed barrel. The flat support plates are cylindrical in shape with an axial horizontal orientation, and the inclined support plates are conical in shape with an axial horizontal orientation. The axes of the cylindrical formed by the flat support plates and the conical formed by the inclined support plates are located on the same horizontal line. The left end of the inclined support plate is an arc-shaped surface, and the center of the arc-shaped surface coincides with the rotation center of the corresponding hinge point of the flat support plate and the inclined support plate. A connecting plate is slidably connected to the shaft. An insert plate is fixed to the left end of the inner plate of the flat support plate. Several slots are provided along the wall of the connecting plate. Several insert plates correspond one-to-one with several slots. The insert plates are inserted into the corresponding slots and the two are slidably connected. Limiting rods are symmetrically fixed to the left end of the wall of the sliding tube. The wall of the fixed barrel is provided with a limiting groove corresponding to the limiting rod. The outer end of the limiting rod passes through the corresponding limiting groove and the two are slidably connected.

2. The expanding device for hot-rolled seamless steel pipes as described in claim 1, characterized in that: The fixed barrel is equipped with a rotating structure, which includes a second motor fixed to the upper part of the left inner wall of the fixed barrel, an active tooth coaxially arranged with the second motor, and a driven tooth meshing with the active tooth. A rotating seat is coaxially fixed to the left side of the connecting plate. The driven tooth is coaxially fixedly connected to the left end of the rotating seat. The right end of the rotating seat passes through the right end of the fixed barrel wall and is coaxially fixedly connected to the connecting plate.

3. The expanding device for hot-rolled seamless steel pipes as described in claim 2, characterized in that: The fixed barrel is provided with a protective shell. The active tooth and the driven tooth are disposed inside the protective shell. The left and right side walls of the active tooth and the driven tooth are respectively attached to the left and right inner walls of the protective shell. The fixed barrel is symmetrically fixed with horizontal beams at the top and bottom. The beams pass through the corresponding ends of the protective shell and are slidably connected.

4. The expanding device for hot-rolled seamless steel pipes as described in claim 3, characterized in that: A plug rod is coaxially fixedly connected to the left side of the active tooth. The plug rod is inserted into the output shaft of the second motor. The inner wall of the output shaft is provided with several protrusions. The plug rod wall is provided with several protrusion grooves that correspond one-to-one with the protrusions. The protrusions are embedded in the protrusion grooves and the two are slidably connected.

5. The expanding device for hot-rolled seamless steel pipes as described in claim 4, characterized in that: The fixed barrel is equipped with a lubrication structure, which includes a storage cavity disposed in the rotating seat, a plurality of first oil supply pipes communicating with the storage cavity, and a plurality of second oil supply pipes corresponding to the plurality of first oil supply pipes. The plurality of first oil supply pipes are arranged in a corresponding manner with the plurality of flat support plates. The first oil supply pipes and the corresponding second oil supply pipes are connected by pipe expansion joints. The first oil supply pipes pass horizontally through the corresponding support rods and are fixedly connected. The second oil supply pipes are arranged vertically, and the outer end of the second oil supply pipes passes through the corresponding flat support plate. The outer end of the second oil supply pipes is flush with the outer surface of the flat support plate.

6. The expanding device for hot-rolled seamless steel pipes as described in claim 5, characterized in that: The storage cavity is provided with a piston plate, and a threaded tube is coaxially fixed to the left end of the piston plate. The threaded tube passes through the left side wall of the rotating seat and the two are slidably connected. A tube sleeve is fixed in the middle of the fixed barrel. The tube sleeve is fitted over the threaded tube and the two are threadedly connected. The piston plate has an outwardly protruding flange on its edge, and the inner wall of the storage cavity has a flange groove.

7. A method for expanding the diameter of hot-rolled seamless steel pipes, employing the expanding device for hot-rolled seamless steel pipes as described in claim 6, characterized in that, Includes the following steps: S1. Place the hot-rolled seamless steel pipe on the steel pipe clamp and fix it in place, and adjust the height of the hot-rolled seamless steel pipe to match the height of the expansion assembly. S2. After the hot-rolled seamless steel pipe is fixed, the first motor is started to drive the shaft to rotate. Under the action of the threaded part, the sliding tube slides to the right, which in turn pushes the connecting sleeve, support rod and flat support plate to slide to the right, so that the diagonal support plate rotates clockwise to the right. The clockwise rotation of the diagonal support plate will drive the left flat support plate to expand outward, thereby realizing the change of the expansion size to adapt to the expansion needs. S3. After the diameter change is completed, apply lubricating oil to the left end of the hot-rolled seamless steel pipe. Then start the hydraulic cylinder to drive the entire expansion assembly to slowly move to the right to expand the diameter until the second oil pipe enters the hot-rolled seamless steel pipe. At this time, stop the expansion and introduce lubricating oil into the storage cavity. S4. After the lubricating oil is filled, close the oil inlet, restart the hydraulic cylinder, and at the same time start the second motor to drive the drive gear and driven gear to rotate, thereby driving the rotating seat to rotate. Under the action of the connecting plate, the flat support plate and the inclined support plate will rotate to expand the diameter. S5. When the rotating seat rotates, the threaded pipe rotates synchronously and pushes the piston plate to slide to the right relative to the storage cavity under the action of the sleeve, thereby slowly squeezing the lubricating oil between the flat support plate and the inner wall of the hot-rolled seamless steel pipe for lubrication. S6. After the diameter expansion is completed, turn off the second motor, start the first motor to drive the shaft to reverse and cause the flat support plate to retract inward. Then, start the hydraulic cylinder to drive the entire diameter expansion assembly to move to the left and exit the hot-rolled seamless steel pipe to complete the diameter expansion.

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