Hollow shaft cold heading and friction welding combined forming process and welding equipment

Abstract

This invention provides a composite forming process and welding equipment for cold heading and friction welding of hollow shafts, including the following steps: S1, hot piercing of round steel; S2, sawing of tube material; S3, straightening; S4, spheroidizing annealing of round steel; S5, phosphating; S6, cold heading of the ends; S7, friction welding; S8, isothermal normalizing; S9, rough turning and boring. This invention also provides friction welding equipment for hollow shafts, including a base, a support fixedly mounted on the base, a tube material tray rotatably connected to the support, a movable seat mounted on the base, and a shoulder plate rotatably connected to the top of the movable seat. The circumferential sidewall of the tube material tray has multiple tube material grooves, with the top of the tube material tray serving as the loading position, the rear as the preheating position, and the bottom as the welding position. This process uses a composite cold heading and friction welding process to form hollow shafts, and the formed structure includes through holes and shoulders, greatly improving material utilization, simplifying manufacturing processes, reducing costs, and simultaneously reducing subsequent machining allowances.

Description

Technical Field

[0001] This invention relates to the field of hollow motor shaft technology, and in particular to a composite forming process and welding equipment for cold heading and friction welding of hollow shafts. Background Technology

[0002] In recent years, the development of new energy vehicles has been rapid, and the motor shaft is one of the core components of its drive system, playing a role in transmitting torque and fixing the rotor. Hollow motor shafts have many advantages, such as being lightweight, having good heat dissipation performance, and low noise and vibration, and have gradually replaced solid motor shafts as the mainstream in the market.

[0003] Hollow motor shafts are primarily formed using methods such as deep hole drilling, rotary forging, and cold extrusion. These methods suffer from drawbacks including low material utilization, high equipment costs, and short tooling life. To address these issues, this invention employs a combined cold heading and friction welding process to form hollow shafts. This method significantly improves material utilization, simplifies manufacturing processes, reduces costs, and minimizes subsequent machining allowances. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a composite forming process and welding equipment for hollow shafts using cold heading and friction welding. The hollow shaft is formed using a composite process of cold heading and friction welding, and the formed structure includes through holes and shaft shoulders, which greatly improves material utilization, simplifies manufacturing processes, reduces costs, and also reduces subsequent machining allowances.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: A composite forming process for hollow shafts, comprising the following steps: S1. Hot piercing of round steel: Round steel is formed into tubes with specific inner and outer diameters using a hot piercing process. S2, Pipe sawing: The pipe is cut into sections of specific lengths using a sawing process; S3. Straightening: The blank is straightened to improve dimensional accuracy and straightness. S4. Spheroidizing Annealing of Round Steel: The round steel billet is spheroidized annealed to improve the metal structure and reduce the hardness, which facilitates subsequent cold heading. S5. Phosphate Saponification: The billet is treated with phosphate saponification to reduce the friction between the billet and the mold during cold heading. S6, Cold heading end: Cold heading through hole and shoulder structure for round steel; S7. Friction welding: Friction welding is performed between the tube and the end of the shaft shoulder using friction welding equipment; S8. Isothermal normalizing: The isothermal normalizing process is used to release the internal stress of cold heading and friction welding and improve the microstructure. S9. Rough turning and boring: rough turning of the outer diameter and boring of the inner diameter to remove the oxide scale from friction welding burrs and isothermal normalizing.

[0006] Preferably, the process parameters for S4 are: temperature 760±10℃, holding temperature for 2-3 hours, cooling with the furnace to about 500℃, and then air cooling.

[0007] Preferably, the process parameters for S8 are: first normalizing temperature 930±10℃, holding for 1.5h, second isothermal temperature 600-650℃, holding for 2h, followed by air cooling.

[0008] This invention also provides a friction welding device for hollow shafts, including a base, a support fixedly mounted on the base, a tube tray rotatably connected to the support, a movable seat mounted on the base, and a corresponding shoulder plate rotatably connected to the top of the movable seat. The circumferential sidewall of the tube tray has multiple tube slots for placing tubes; the top of the tube tray is a loading position, the rear is a preheating position, and the bottom is a welding position. A positioning port is provided on the right side of each tube slot, and a clamping assembly is installed within the positioning port. A push plate is installed on the left side of the material tray corresponding to the loading position to push the tube into the positioning port. The circumferential side wall of the shoulder plate is equipped with a first three-jaw chuck corresponding to multiple positioning ports. A preheating tube is installed between the tube tray and the shoulder plate at the preheating position. An electromagnetic chuck is installed on the left side of the tube tray at the preheating position to push the end of the tube into the preheating tube. A movable arm is installed on the left side of the base. An inner support arm is rotatably connected to the top of the movable arm. An inner support mechanism is installed on the inner support arm to support and press the tube from the inside.

[0009] Preferably, the moving seat, push plate, electromagnetic chuck, and moving arm are all propelled by hydraulic cylinders.

[0010] Preferably, both the tube tray and the shoulder tray are driven to rotate by a drive shaft, which is rotatably connected to the movable seat and the support.

[0011] Preferably, the clamping assembly is a second three-jaw chuck, which is installed in the positioning port. The ends of the three jaws of the second three-jaw chuck are rotatably connected to rollers that abut against the tube material. A hydraulic oil pipe is installed at the center of the tube material plate and the shoulder plate. One end of the hydraulic oil pipe in the tube material plate is connected to multiple second three-jaw chucks through multiple branch pipes. One end of the hydraulic oil pipe in the shoulder plate is connected to multiple first three-jaw chucks through multiple branch pipes. A solenoid valve is installed in each branch pipe. The other end of the hydraulic oil pipe extends out to a drive shaft and is connected to a pump oil pipe through a rotary joint.

[0012] Preferably, the inner support mechanism includes hydraulic expansion discs installed at both ends of the inner support arm. Each pair of hydraulic expansion discs has an arc-shaped inner support plate installed at its corresponding expansion end. An end bracket is fixed to the left end of the inner support arm. A rotating shaft is fixed to the side wall of the end bracket. The rotating shaft is rotatably connected to the moving arm. The hydraulic pipeline of the hydraulic expansion disc extends out of the rotating shaft and connects to the pump oil pipe through a rotary joint.

[0013] Preferably, a motor is mounted on the mobile arm, and the output end of the motor is driven by a pulley assembly to the rotating shaft.

[0014] Preferably, the inner bottom of the tube trough is provided with a pair of telescopic grooves, and a support seat is elastically connected to the telescopic grooves by a spring. An electromagnetic block is installed at the inner bottom of the telescopic grooves, and a magnetic block corresponding to the electromagnetic block is installed at the bottom of the support seat. A connector electrically connected to the corresponding electromagnetic block is installed on the left side of the tube tray, and a connector adapted to the connector is installed on the support at the material loading position.

[0015] The beneficial effects of this invention are as follows: 1. This invention uses a combination of cold heading and friction welding to form hollow shafts, which improves material utilization; it forms complex structures such as long through holes and shaft shoulders, reducing manufacturing costs; and it provides high dimensional accuracy of the blank, reducing subsequent machining allowances.

[0016] 2. By installing the tube tray, shoulder tray, loading position, preheating position, and welding position, the tube is placed in the tube trough at the loading position. The shoulder is clamped by the first three-jaw chuck, and the push plate pushes one end of the tube into the positioning port. It is then clamped by the second three-jaw chuck. The tube is then rotated to the preheating position, where the corresponding end of the tube is magnetically attracted by the electromagnetic chuck, pushing the welding end of the tube into the preheating tube. The moving seat drives the welding end of the corresponding shoulder into the preheating tube to preheat the welding end. After preheating, the tube is rotated to the welding position, and the moving arm drives the inner support arm. Inserting the tube into the pipe, the internal support mechanism supports and presses the pipe against the inside. The motor is started, and the shaft is driven to rotate through the pulley assembly. Finally, the pipe is driven to rotate at high speed through the internal support arm. The rollers roll, and the moving arm and moving seat advance to achieve friction welding at the end. After welding is completed, the second and third jaw chucks and the internal support mechanism release the pipe. The moving seat moves, and the welded hollow motor shaft can be pulled out. The first and third jaw chucks are then released for unloading. This enables a continuous and automated welding process, and the preheating setting improves welding efficiency.

[0017] 3. By installing an internal support mechanism, the internal support mechanism supports and clamps the pipe material from the inside. In conjunction with the clamping of the external second and third jaw chucks, the clamping effect on longer pipe materials can be improved, and end swaying during rotation can be avoided. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic diagram of the pipe structure of the present invention; Figure 3 This is a schematic diagram of the shoulder structure of the present invention; Figure 4 This is a schematic diagram of the hollow motor shaft structure of the present invention; Figure 5 This is a schematic diagram of the friction welding equipment of the present invention; Figure 6 This is a left-side view of the tubular material tray proposed in this invention; Figure 7 for Figure 5 Enlarged schematic diagram of the structure at point A in the diagram; Figure 8 for Figure 5 Enlarged schematic diagram of the structure at point B in the diagram; Figure 9 This is a schematic diagram of the support state of the internal support mechanism proposed in this invention.

[0019] In the diagram: 1. Pipe tray, 2. Preheating pipe, 3. Shoulder plate, 4. Moving seat, 5. Drive shaft, 6. Hydraulic oil pipe, 7. Solenoid valve, 8. First three-jaw chuck, 9. Pipe groove, 10. Push plate, 11. Support, 12. Electrical connector, 13. Lifting seat, 14. Electromagnetic chuck, 15. Electrical connector, 16. Hydraulic expansion plate, 17. Inner support arm, 18. Arc-shaped inner support plate, 19. End seat, 20. Rotary shaft, 21. Pulley assembly, 22. Motor, 23. Base, 24. Positioning port, 25. Second three-jaw chuck, 26. Roller, 27. Electromagnetic block, 28. Magnetic block, 29. Telescopic groove, 30. Spring, 31. Moving arm, 32. Pipe, 33. Shoulder. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Reference Figure 1-4 A composite forming process for cold heading and friction welding of hollow shafts includes the following steps: S1. Hot piercing of round steel: Round steel is formed into tubes with specific inner and outer diameters using a hot piercing process. S2, Pipe sawing: The pipe is cut into sections of specific lengths using a sawing process; S3. Straightening: The blank is straightened to improve dimensional accuracy and straightness. S4. Spheroidizing Annealing of Round Steel: The round steel billet adopts the spheroidizing annealing process to improve the metal structure, reduce the hardness, and facilitate subsequent cold heading. The process parameters are: temperature 760±10℃, holding temperature for 2-3 hours, furnace cooling to about 500℃, and then air cooling. S5. Phosphate Saponification: The billet is treated with phosphate saponification to reduce the friction between the billet and the mold during cold heading. S6, Cold heading end: Cold heading through hole and shoulder structure for round steel; S7. Friction welding: Friction welding is performed between the tube and the end of the shaft shoulder using friction welding equipment; S8. Isothermal normalizing: The isothermal normalizing process is adopted to release the internal stress of cold heading and friction welding and improve the microstructure. The process parameters are: first normalizing temperature 930±10℃, holding for 1.5h, second isothermal temperature 600-650℃, holding for 2h, followed by air cooling. S9. Rough turning and boring: rough turning of the outer diameter and boring of the inner diameter to remove the oxide scale from friction welding burrs and isothermal normalizing.

[0022] Reference Figure 5-9 A friction welding device for hollow shafts includes a base 23, a support 11 fixedly mounted on the base 23, a tube tray 1 rotatably connected to the support 11, a movable seat 4 also mounted on the base 23, and a corresponding shoulder plate 3 rotatably connected to the top of the movable seat 4. The circumferential sidewall of the tube tray 1 is provided with multiple tube grooves 9 for placing tubes 32. The top of the tube tray 1 is the feeding position, the rear side is the preheating position, and the bottom is the welding position. The tube tray 1 and the shoulder plate 3 are both driven to rotate by a drive shaft 5, which is rotatably connected to the movable seat 4 and the support 11, enabling a continuous and automated welding process.

[0023] The right side of the pipe trough 9 is provided with a connecting positioning port 24. A clamping assembly is installed in the positioning port 24. The clamping assembly is a second three-jaw chuck 25. The second three-jaw chuck 25 is installed in the positioning port 24. The ends of the three jaws of the second three-jaw chuck 25 are rotatably connected to rollers 26 that abut against the pipe 32. A hydraulic oil pipe 6 is installed at the center of the pipe trough 1 and the shoulder plate 3. One end of the hydraulic oil pipe 6 in the pipe trough 1 is connected to multiple second three-jaw chucks 25 through multiple branch pipes. The hydraulic oil pipe 6 in the shoulder plate 3... One end of the hydraulic oil pipe 6 is connected to multiple first three-jaw chucks 8 through multiple branch pipes. Each branch pipe is equipped with a solenoid valve 7. The other end of the hydraulic oil pipe 6 extends out to the drive shaft 5 and connects to the pump oil pipe through a rotary joint. When the solenoid valve 7 in the corresponding branch pipe is opened, the oil supply or suction process of the corresponding first three-jaw chuck 8 and second three-jaw chuck 25 can be realized. At this time, the hydraulic oil pipe 6 is in the oil supply or suction state. The rotary joint can realize the oil circuit conduction in the rotation state. The oil supply or suction process realizes clamping and release.

[0024] On the left side of the tube tray 1, at the corresponding feeding position, there is a push plate 10 that pushes the tube 32 into the positioning port 24. The hydraulic cylinder drives the push plate 10 to move, and the push plate 10 pushes one end of the tube 32 into the positioning port 24 to realize the feeding process.

[0025] The circumferential sidewall of the shoulder plate 3 is equipped with a first three-jaw chuck 8 that corresponds one-to-one with multiple positioning ports 24, and the shoulder 33 is clamped by the first three-jaw chuck 8.

[0026] A preheating tube 2 is installed at the preheating position between the tube tray 1 and the shoulder tray 3. An electromagnetic chuck 14 is installed on the left side of the tube tray 1 at the preheating position, which can push the end of the tube 32 into the preheating tube 2. The electromagnetic chuck 14 can magnetically hold the tube 32 and push the tube into the preheating tube 2 through a hydraulic cylinder. The preheating tube 2 adopts electromagnetic heating to preheat the welding end and improve welding efficiency.

[0027] A movable arm 31 is mounted on the left side of the base 23. An inner support arm 17 is rotatably connected to the top of the movable arm 31. An inner support mechanism is mounted on the inner support arm 17 to support and press against the pipe 32 from the inside. The inner support mechanism includes hydraulic expansion discs 16 installed at both ends of the inner support arm 17. A pair of hydraulic expansion discs 16 have arc-shaped inner support plates 18 mounted on their respective expansion ends. An end bracket 19 is fixed to the left end of the inner support arm 17. A rotating shaft 20 is fixed to the side wall of the end bracket 19. The rotating shaft 20 is rotatably connected to the movable arm 31. The hydraulic line of 6 extends out of the rotating shaft and connects to the pump oil pipe through a rotary joint. A motor 22 is installed on the moving arm 31. The output end of the motor 22 is driven to the rotating shaft 20 through the pulley assembly 21. The moving arm 31 drives the inner support arm 17 to insert into the pipe 32. The inner support mechanism supports and presses the pipe 32 from the inside. The motor 22 is started, and the rotating shaft 20 is driven to rotate through the pulley assembly 21. Finally, the pipe 32 is driven to rotate at high speed through the inner support arm 17. The roller 26 rolls. The advancement of the moving arm 31 and the moving seat 4 realizes the friction welding of the end.

[0028] The movement of the movable seat 4, push plate 10, electromagnetic chuck 14 and movable arm 31 is all achieved by hydraulic cylinders. After welding is completed, the second three-jaw chuck 25 and the inner support mechanism release the tube 32, the movable seat 4 moves, and the welded hollow motor shaft can be pulled out from the positioning port 24. The first three-jaw chuck 8 is released to unload the material.

[0029] In addition, a pair of telescopic grooves 29 are provided at the bottom of the tube material trough 9. A lifting seat 13 is elastically connected to the telescopic groove 29 by a spring 30. An electromagnetic block 27 is installed at the bottom of the telescopic groove 29. A magnetic block 28 corresponding to the electromagnetic block 27 is installed at the bottom of the lifting seat 13. A connector 15 electrically connected to the corresponding electromagnetic block 27 is installed on the left side of the tube material tray 1. A connector 12 adapted to the connector 15 is installed on the support 11 at the loading position. When the tube material tray 1 is rotated to the loading position, the connector 15 contacts the connector 12, the circuit is connected, the electromagnetic block 27 works, and the magnetic block 28 and the electromagnetic block 27 repel each other with the same pole. Under the magnetic repulsion force, the spring 30 is compressed, and the lifting seat 13 is pushed out of the telescopic groove 29, lifting the tube material 32 so that its center is aligned with the center of the positioning port 24, making it easy to push into the positioning port 24. In other positions, the lifting seat 13 is retracted in the telescopic groove 29.

[0030] At the loading position, the tube 32 is placed in the tube trough 9. The shoulder 33 is clamped by the first three-jaw chuck 8. The push plate 10 pushes one end of the tube 32 into the positioning port 24 and clamps it by the second three-jaw chuck 25. The tube is then rotated to the preheating position. The corresponding end of the tube 32 is magnetically attracted by the electromagnetic chuck 14, and the welding end of the tube 32 is pushed into the preheating tube 2. The moving seat 4 drives the welding end of the corresponding shoulder 33 into the preheating tube 2 to preheat the welding end. After preheating, the tube is rotated to the welding position. The moving arm 31 drives the inner support arm 17 to insert into the tube 32. The inner support mechanism supports and presses the tube 32 from the inside, cooperating with the external second three-jaw chuck 2. The clamping mechanism at point 5 improves the clamping effect on longer pipe sections 32, preventing end wobbling during rotation. Starting the motor 22 drives the rotating shaft 20 via the pulley assembly 21, ultimately causing the pipe section 32 to rotate at high speed via the inner support arm 17. The rollers 26 roll, and the advancing motion of the moving arm 31 and moving seat 4 achieves friction welding at the ends. After welding, the second three-jaw chuck 25 and the inner support mechanism release the pipe section 32, and the moving seat 4 moves, allowing the welded hollow motor shaft to be pulled out. The first three-jaw chuck 8 then releases, enabling continuous automated welding. The preheating setting improves welding efficiency. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite forming process for cold heading and friction welding of hollow shafts, characterized in that, Includes the following steps: S1. Hot piercing of round steel: Round steel is formed into tubes with specific inner and outer diameters using a hot piercing process. S2, Pipe sawing: The pipe is cut into sections of specific lengths using a sawing process; S3. Straightening: The blank is straightened to improve dimensional accuracy and straightness. S4. Spheroidizing Annealing of Round Steel: The round steel billet is spheroidized annealed to improve the metal structure and reduce the hardness, which facilitates subsequent cold heading. S5. Phosphate Saponification: The billet is treated with phosphate saponification to reduce the friction between the billet and the mold during cold heading. S6, Cold heading end: Cold heading through hole and shoulder structure for round steel; S7. Friction welding: Friction welding is performed between the tube and the end of the shaft shoulder using friction welding equipment; S8. Isothermal normalizing: The isothermal normalizing process is used to release the internal stress of cold heading and friction welding and improve the microstructure. S9, Rough turning and boring: Rough turning of the outer diameter and boring of the inner diameter to remove the oxide scale from friction welding burrs and isothermal normalizing; The friction welding equipment includes a base (23), on which a support (11) is fixedly installed. A tube tray (1) is rotatably connected to the support (11). A movable seat (4) is also installed on the base (23). A shoulder plate (3) corresponding to the tube tray (1) is rotatably connected to the top of the movable seat (4). The circumferential sidewall of the tube tray (1) is provided with multiple tube grooves (9) for placing tubes (32). The top of the tube tray (1) is the feeding position, the rear side is the preheating position, and the bottom is the welding position. A positioning port (24) is provided on the right side of the tube groove (9). A clamping component is installed in the positioning port (24). The left side of the tube tray (1) is corresponding to the feeding position. A push plate (10) is installed at the position to push the tube (32) into the positioning port (24). The circumferential side wall of the shoulder plate (3) is equipped with a first three-jaw chuck (8) corresponding to the multiple positioning ports (24). A preheating tube (2) is installed at the preheating position between the tube plate (1) and the shoulder plate (3). An electromagnetic chuck (14) is installed on the left side of the tube plate (1) at the preheating position to push the end of the tube (32) into the preheating tube (2). A moving arm (31) is installed on the left side of the base (23). An inner support arm (17) is rotatably connected to the top of the moving arm (31). An inner support mechanism is installed on the inner support arm (17) to support and press the tube (32) from the inside.

2. The cold heading and friction welding composite forming process for hollow shafts according to claim 1, characterized in that, The process parameters for S4 are: temperature 760±10℃, holding temperature for 2-3 hours, cooling with the furnace to about 500℃, and then air cooling.

3. The cold heading and friction welding composite forming process for hollow shafts according to claim 1, characterized in that, The process parameters for S8 are: first normalizing temperature 930±10℃, holding for 1.5h, second isothermal temperature 600-650℃, holding for 2h, followed by air cooling.

4. The cold heading and friction welding composite forming process for hollow shafts according to claim 1, characterized in that, The moving seat (4), push plate (10), electromagnetic chuck (14) and moving arm (31) are all driven by hydraulic cylinders.

5. The cold heading and friction welding composite forming process for hollow shafts according to claim 1, characterized in that, The tube tray (1) and the shoulder tray (3) are both driven to rotate by the drive shaft (5), which is rotatably connected to the movable seat (4) and the support (11).

6. The cold heading and friction welding composite forming process for hollow shafts according to claim 5, characterized in that, The clamping assembly is a second three-jaw chuck (25). The second three-jaw chuck (25) is installed in the positioning port (24). The three jaw ends of the second three-jaw chuck (25) are rotatably connected to rollers (26) that abut against the tube material (32). A hydraulic oil pipe (6) is installed at the center of the tube material plate (1) and the shoulder plate (3). One end of the hydraulic oil pipe (6) in the tube material plate (1) is connected to multiple second three-jaw chucks (25) through multiple branch pipes. One end of the hydraulic oil pipe (6) in the shoulder plate (3) is connected to multiple first three-jaw chucks (8) through multiple branch pipes. A solenoid valve (7) is installed in each branch pipe. The other end of the hydraulic oil pipe (6) extends out to the drive shaft (5) and is connected to the pump oil pipe through a rotary joint.

7. The cold heading and friction welding composite forming process for hollow shafts according to claim 1, characterized in that, The inner support mechanism includes hydraulic expansion discs (16) installed at both ends of the inner support arm (17). The expansion ends of the pair of hydraulic expansion discs (16) are all equipped with arc-shaped inner support plates (18). An end bracket (19) is fixed to the left end of the inner support arm (17). A rotating shaft (20) is fixed to the side wall of the end bracket (19). The rotating shaft (20) is rotatably connected to the moving arm (31). The hydraulic pipeline of the hydraulic expansion disc (16) extends out of the rotating shaft and connects to the pump oil pipe through a rotary joint.

8. The cold heading and friction welding composite forming process for hollow shafts according to claim 7, characterized in that, A motor (22) is installed on the movable arm (31), and the output end of the motor (22) is driven by the rotating shaft (20) through a pulley assembly (21).

9. The cold heading and friction welding composite forming process for hollow shafts according to claim 1, characterized in that, The inner bottom of the tubular material trough (9) is provided with a pair of telescopic grooves (29). A support seat (13) is elastically connected to the telescopic groove (29) by a spring (30). An electromagnetic block (27) is installed at the inner bottom of the telescopic groove (29). A magnetic block (28) corresponding to the electromagnetic block (27) is installed at the bottom of the support seat (13). A connector (15) electrically connected to the corresponding electromagnetic block (27) is installed on the left side of the tubular material tray (1). A connector (12) adapted to the connector (15) is installed on the support (11) at the material loading position.

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