Method of forging a half shaft and a cogging device for a half shaft

Abstract

This invention discloses a forging method and an upsetting device for a half-shaft, belonging to the field of half-shaft processing technology. It includes medium-frequency heating, upsetting, and rolling processes. The upsetting process includes: S101: placing the heated bar stock vertically on the upsetting device, with the heated end of the bar stock located at the upsetting die; S102: closing the lower die and clamping the lower part of the heated end; S103: moving the upper die downwards to fit over the heated end and locking it onto the locking boss; S104: adding graphite release oil to the upper die; S105: moving the punch downwards into the upper die and pressing down on the top of the bar stock; S106: moving the punch upwards, and then moving the upper die upwards above the bar stock, with the lower end of the punch located in the upper die; S107: spraying graphite release oil solution upwards from the lower part of the upper die into the die cavity, while simultaneously opening the lower die to remove the upset bar stock; S108: spraying cooling water from the lower die to cool and rinse.

Description

Technical Field

[0001] This invention belongs to the field of axle machining technology, and specifically relates to a forging method for axles and an upsetting device for axles. Background Technology

[0002] The axle of an automobile is the direct drive component for wheel rotation and a crucial part for transmitting torque. The current machining process for axles is as follows: 1. Blanking the incoming raw materials; 2. Forging; 3. Straightening; 4. Sawing the overall length; 5. Rough turning; 6. Quenching and tempering; 7. Straightening; 8. Splitting the overall length; 9. Drilling the center hole; 10. Semi-finish turning; 11. Finish turning; 12. Gear milling; 13. Surface medium-frequency heat treatment; 14. Tempering; 15. Fine straightening; 16. Fine shot blasting; 17. Fine turning of the disc; 18. Drilling; 19. Threading; 20. Grinding the journal; 21. Magnetic particle inspection; 22. Final inspection. The forging process typically consists of three steps: medium-frequency heating, upsetting, and rolling. Upsetting is performed immediately after medium-frequency heating, followed immediately by rolling. Upsetting equipment is used in the upsetting process, which usually includes a hydraulic press, upsetting dies, and other auxiliary structures.

[0003] For example, the device disclosed in application number CN201910236600.0 is a hydraulic press for semi-shaft polymer molding, including a frame, a worktable on the frame, a lower mold on the worktable, the lower mold including two bodies that cooperate with each other, one of which is connected to a mold closing cylinder, and a trough for placing blanks vertically below the frame; a hydraulic column is provided above the frame, a fixed plate is provided below the hydraulic column, a pressure rod is provided on the fixed plate, a pressure block and an upper mold are provided at the end of the pressure rod, the pressure block is located inside the upper mold and matches the upper mold and can move up and down relative to the upper mold, the pressure block can lift the upper mold, and also includes an automatic inkjet device, the automatic inkjet device including an inkjet cylinder and a printhead, the inkjet cylinder is fixedly provided on one side of the frame, the printhead nozzle is fixedly provided at the end of the piston rod of the inkjet cylinder, after the material is pressed, the inkjet cylinder extends, and the printhead is located directly below the upper mold and sprays ink into the mold. A forging device is also used, the forging device including a medium frequency heating furnace, an upsetting structure and a swing mill structure arranged in sequence.

[0004] Although graphite release oil is sprayed into the upper mold in the aforementioned device, demolding difficulties still exist. Specifically, during the separation and upward movement of the upper and lower molds, the formed bar remains within the upper mold (tubular structure) and separates from the lower mold. Ideally, the bar should remain clamped to the lower mold during the upward movement of the upper mold, and the upper mold should separate from the formed bar. The demolding success rate of the aforementioned structure is only 70-80%. If the bar fails to separate from the upper mold, it needs to be manually pulled out. This process has the following disadvantages: 1. Waste of manpower; 2. Waste of time, which may cause the bar temperature to drop below the temperature of the milling process; 3. The processed bar is extremely hot, reaching 900°C, posing a significant safety hazard; 4. The pulling process may cause the bar to fall to the ground or onto equipment, resulting in damage. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a forging method and an upsetting device for a half-shaft, improving the demolding success rate to over 95%. The technical solution is as follows:

[0006] On one hand, embodiments of the present invention provide a forging method for a half-shaft, including medium-frequency heating, upsetting, and rolling processes, wherein the upsetting process includes:

[0007] S101: The heated bar 1 is placed vertically on the upsetting device, with the heated end of the bar 1 facing upward and located at the upsetting mold of the upsetting device.

[0008] S102: The mold closing cylinder 18 of the upsetting device extends to close the lower mold 20 of the upsetting device and hold the lower part of the heating end. Then the mold closing locking structure 16 of the upsetting device locks the lower mold 20.

[0009] S103: The upper die 19 of the upsetting device moves downward to be fitted outside the heating end and is locked onto the locking boss 21 on the top of the lower die 20.

[0010] S104: Add graphite release oil from the top of the mold cavity of the upper mold 19;

[0011] S105: The punch 10 of the upsetting device moves downward into the upper die 19 and presses down on the top of the bar stock 1 to upset it.

[0012] S106: After the upsetting is completed, the punch 10 moves upward and then the upper die 19 moves upward to above the bar stock 1. At this time, the lower end of the punch 10 is located in the upper through hole 27 of the upper die 19.

[0013] S107: Graphite release oil solution is sprayed from the lower part of the upper mold 19 into the mold cavity of the upper mold 19. The graphite release oil solution is made by mixing graphite release oil and water at a mass ratio of 1:45-70. At the same time, the mold closing locking structure 16 returns to its original position, and the mold closing cylinder 18 retracts to open the lower mold 20, so as to take out the upsetting bar 1.

[0014] S108: The cooling water nozzle 17 of the roughing device sprays water onto the lower mold 20 to cool the lower mold 20 and rinse the graphite release oil from the surface.

[0015] The medium-frequency heating process involves heating to 1050-1150℃ for 160-200 seconds.

[0016] Specifically, in step S104, the amount of graphite release oil used is 40-50 mL.

[0017] Specifically, in step S107, the process of spraying the graphite release oil solution is as follows: the spray volume is 10-20 mL and the spraying time is 3-5 s.

[0018] The upper mold 19 is equipped with a cooling jacket. After the roughing process is completed, the temperature of the heating section is greater than or equal to 850°C. After the rolling process is completed, the rolled bar 1 is naturally cooled.

[0019] The heating section after upsetting consists of, from bottom to top, a straight upsetting section 2, a lower conical upsetting section 3, and an upper conical upsetting section 4. The straight upsetting section 2 and the lower conical upsetting section 3 are formed by the lower mold 20, and the upper conical upsetting section 4 is formed by the upper mold 19. The diameter of the straight upsetting section 2 is larger than the diameter of the bar stock 1. The diameter of the lower conical upsetting section 3 gradually increases from bottom to top, and its lower end diameter is the same as the diameter of the straight upsetting section 2. The diameter of the upper conical upsetting section 4 gradually decreases from bottom to top, and its lower end diameter is the same as the upper end diameter of the lower conical upsetting section 3. Its upper end diameter is larger than the diameter of the bar stock 1, and its length is greater than the length of the lower conical upsetting section 3.

[0020] Specifically, in this embodiment of the invention, the length of the straight upsetting section 2 is 4-8cm, and its diameter is 1.1-1.3 times the diameter of the bar stock 1; the length of the lower conical upsetting section 3 is 2-4cm, and the diameter of its upper end is 1.3-1.5 times the diameter of the bar stock 1; the length of the upper conical upsetting section 4 is 8-15cm, and the diameter of its upper end is 1.1-1.3 times the diameter of the bar stock 1.

[0021] On the other hand, embodiments of the present invention also provide a half-shaft upsetting device, which includes a hydraulic punch, an upsetting die, a spray structure 15, a die-closing locking structure 16, a cooling water nozzle 17, and a die-closing cylinder 18. The upsetting die includes an upper die 19 and a lower die 20. The lower die 20 is disposed on the worktable 5 of the hydraulic punch. The upper die 19 is located directly above the lower die 20 and can be driven up and down by the hydraulic punch. The punch 10 of the hydraulic punch is coaxially arranged with the bar stock 1 and is located directly above the upper die 19. The lower die 20 is composed of two half-dies arranged opposite each other and cooperating with each other. The rear half-die is fixed on the worktable 5, and the front half-die is rotatably disposed on the worktable 5 or the rear half-die. A mold-closing cylinder 18 is hinged between it and the worktable 5; the worktable 5 is provided with a mold-closing locking structure 16 for locking the two half molds together; the spray structure 15 can spray the mold cavity of the upper mold 19 from below; the top of the lower mold 20 is provided with a locking boss 21, which is a circular boss coaxial with the bar stock 1, the top of the mold cavity of the lower mold 20 is coaxially provided on the locking boss 21, and the bottom of the mold cavity of the upper mold 19 is coaxially provided with a locking cavity 25 that cooperates with the locking boss 21; during upsetting, the locking cavity 25 is fitted onto the locking boss 21; the cooling water nozzle 17 includes two nozzles, which are respectively located above the two half molds after unfolding.

[0022] In this embodiment of the invention, the lower mold 20 has a cavity that, from bottom to top, is divided into a lower through hole 22, a straight upsetting forming cavity 23, and a lower conical upsetting forming cavity 24. The upper mold 19 has a cylindrical structure, and its cavity, from bottom to top, is divided into a locking cavity 25, an upper upsetting forming cavity 26, and an upper through hole 27. The lower through hole 22, the straight upsetting forming cavity 23, the lower conical upsetting forming cavity 24, the locking cavity 25, the upper upsetting forming cavity 26, and the upper through hole 27 are all coaxially arranged with the bar stock 1. The lower through hole 22, the straight upsetting forming cavity 23, and the upper through hole 27 are all cylindrical. The lower conical upsetting forming mold cavity 24 is a conical hole that gradually increases in size from bottom to top, and the upper upsetting forming mold cavity 26 is a conical hole that gradually increases in size from top to bottom. The inner diameter of the lower through hole 22 matches the diameter of the bar stock 1, the inner diameter of the locking cavity 25 matches the diameter of the locking boss 21, and the inner diameter of the upper through hole 27 matches the diameter of the punch 10. The straight upsetting forming mold cavity 23, the lower conical upsetting forming mold cavity 24, and the upper upsetting forming mold cavity 26 form the mold cavity of the upsetting mold and are respectively used to form the straight upsetting section 2, the lower conical upsetting section 3, and the upper conical upsetting section 4.

[0023] In this embodiment of the invention, the hydraulic punch press includes a worktable 5, a head 6 above the worktable 5, a vertically arranged hydraulic cylinder 7 on the head 6, a lower lifting plate 8 capable of vertical movement, an upper lifting plate 9 capable of vertical movement, a punch 10 vertically arranged in the lower center of the upper lifting plate 9, four vertically arranged guide pillars 11 between the head 6 and the worktable 5, two vertically arranged lifting cylinders 12 on the head 6, and a guide positioning groove 13 arranged along the front-back direction below the worktable 5. The worktable 5, lower lifting plate 8, upper lifting plate 9, and head 6 are arranged sequentially from bottom to top. The upper lifting plate 9 and lower lifting plate 8 are both rectangular plates arranged along the left-right direction and cooperating with each other. The four guide pillars 11 are arranged in a rectangular pattern. The four corners of the upper lifting plate 9 and lower lifting plate 8 are slidably mounted on the four guide pillars 11. The lower die 20 is located in the middle of the lower lifting plate 8. The hydraulic cylinder 7... The lower end of the telescopic rod is fixedly connected to the upper side of the upper lifting plate 9; two lifting cylinders 12 are located on the left and right sides of the machine head 6 and driven synchronously, with their telescopic rods passing downward through the upper lifting plate 9 and their lower ends fixedly connected to the upper side of the lower lifting plate 8; the worktable 5 has a notch 14 on the front of the semi-die located on the rear side for vertically inserting the bar stock 1 along the front-rear direction; the guide positioning groove 13 is a rectangular groove with an open front side, which allows the lower end of the bar stock 1 to be vertically inserted, and its rear end is located directly below the semi-die on the rear side; the punch 10 has a limiting protrusion 28 coaxially provided in the middle, and the limiting protrusion 28 cannot pass through the upper lifting plate 9; when the lifting cylinder 12 extends, the locking cavity 25 is fitted onto the locking boss 21; when the hydraulic cylinder 7 extends, the punch 10 presses against the top of the bar stock 1 to form a rough shape; during the rough shape, the limiting protrusion 28 abuts against the upper side of the upper lifting plate 9.

[0024] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: This patent improves the demolding success rate through various means, including the following means:

[0025] (1) Add graphite release oil directly.

[0026] (2) Design a special demolding cavity. Under the premise that it is easy to roll and form later, the bar after the upsetting is easy to separate from the upper mold (such as designing a longer upper upsetting forming cavity) and not easy to separate from the lower mold (such as designing a straight upsetting forming cavity and a shorter lower conical upsetting forming cavity).

[0027] (3) After the roughing is completed, the graphite release oil solution is sprayed. The functions are as follows: First, it cools down the upper mold; second, the graphite release oil solution vaporizes under high temperature conditions, so that the graphite release oil adheres more evenly and has a better adhesion effect on the upper mold cavity; third, it cleans the upper mold cavity to avoid the residue of impurities such as iron sheets, so as to facilitate demolding; fourth, the vaporized water vapor is in the upper mold cavity (the top is closed by the punch) and flows downward, which has a better cooling effect, a better cleaning effect (the water vapor flows downward to form pressure), and a better adhesion effect of the graphite release oil (vaporization forms pressure), so that the graphite release oil added directly and the residue are evenly dispersed on the surface of the mold cavity.

[0028] (4) Improve molding accuracy, including mold closing and locking structure, combination of locking boss and locking cavity, four guide pillars and limiting rings shared by the upper and lower lifting plates. Attached Figure Description

[0029] Figure 1 This is a flowchart of the forging method of the half-shaft in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the heating end after the backing is thickened;

[0031] Figure 3 This is a schematic diagram of the structure of the axle upsetting device in an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the lower mold structure;

[0033] Figure 5 This is a schematic diagram of the upper mold structure;

[0034] Figure 6 This is a schematic diagram of the combination of the lower mold and the upper mold.

[0035] In the diagram: 1. Bar stock, 2. Straight block forming section, 3. Lower conical block forming section, 4. Upper conical block forming section, 5. Workbench, 6. Machine head, 7. Hydraulic cylinder, 8. Lower lifting plate, 9. Upper lifting plate, 10. Punch, 11. Guide column, 12. Lifting cylinder, 13. Guide positioning groove, 14. Notch, 15. Spray structure, 16. Mold closing and locking structure, 17. Cooling water nozzle, 18. Mold closing cylinder, 19. Upper mold, 20. Lower mold, 21. Locking boss, 22. Lower through hole, 23. Straight block forming mold cavity, 24. Lower conical block forming mold cavity, 25. Locking cavity, 26. Upper block forming mold cavity, 27. Upper through hole, 28. Limiting ring. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] Example 1

[0038] Example 1 provides a forging method for a half-shaft, including medium-frequency heating, upsetting, and rolling processes. See also... Figure 1 The roughing process includes:

[0039] S101: The heated bar stock 1 is placed vertically on the upsetting device, with the heated end (upper end) of the bar stock 1 facing upwards and located at the upsetting mold of the upsetting device. Specifically, the lower end of the bar stock 1 is located in the guide positioning groove 13, and the middle part is located in the notch 14. At this time, the lower mold 20 opens, the mold cavity of the rear half mold is exposed, the mold closing cylinder 18 retracts, and the locking cylinder of the mold closing locking structure 16 retracts; the upper mold 19 is located above the bar stock 1.

[0040] S102: The mold closing cylinder 18 of the upsetting device extends to close the lower mold 20 of the upsetting device and hold the lower part of the heating end tightly. Then the mold closing locking structure 16 locks the two half molds.

[0041] S103: The upper mold 19 of the upsetting device moves downward (the lifting cylinder 12 extends) to be fitted outside the heating end and its (locking cavity 25) is fitted onto the locking boss 21 on the top of the lower mold 20. The locking cavity 25 holds the lower mold 20 tightly to improve molding accuracy and also prevents graphite release oil from leaking out.

[0042] S104: Graphite release oil is added from the top of the mold cavity of the upper mold 19. Specifically, the graphite release oil can be manually fed into the upper mold 19 through a long-handled water ladle, and the graphite release oil fills the gap between the bar stock and the upsetting mold cavity.

[0043] S105: The punch 10 of the upsetting device moves downward (the hydraulic cylinder 7 extends) into the upper die 19 and presses down (to the lower end of the punch 10 to the top of the upper upsetting forming cavity 26) the top of the bar stock 1 to upset it.

[0044] S106: After the upsetting is completed, the punch 10 moves upward (the hydraulic cylinder 7 retracts), and then the upper die 19 moves upward (the lifting cylinder 12 retracts) to the top of the bar stock 1. At this time, the lower end of the punch 10 is located in the upper through hole 27 of the upper die 19 to block the mold cavity of the upper die.

[0045] S107: Graphite release oil solution is sprayed upwards from the lower part of the upper mold 19 into the mold cavity of the upper mold 19. The graphite release oil solution is prepared by mixing graphite release oil and water at a mass ratio of 1:45-70. At the same time, the mold closing locking structure 16 returns to its original position (specifically, the locking cylinder retracts), and then the mold closing cylinder 18 retracts to open the lower mold 20, allowing the manually removed upsetting bar 1. The spraying process of the graphite release oil solution is as follows: the spray cylinder extends, the nozzle moves inwards from the side of the lower mold 20 to the adjacent lower part of the lower mold 20, and the nozzle opens to spray upwards.

[0046] S108: The cooling water nozzle 17 of the roughing device sprays water onto the lower mold 20 to cool the lower mold 20 and rinse the graphite release oil from the surface.

[0047] The medium-frequency heating process involves heating to 1050-1150℃ for 160-200 seconds, preferably 180 seconds.

[0048] Specifically, in step S104, the amount of graphite release oil used is 40-50 mL.

[0049] Specifically, in step S107, the process of spraying the graphite release oil solution is as follows: the spray volume is 10-20 mL, and the spraying time is 3-5 seconds. During this time, the molded rod can be removed from the lower mold 20.

[0050] Preferably, the graphite release oil solution is prepared by mixing graphite release oil and water at a mass ratio of 1:60. In this patent, the graphite release oil and water need to be mixed in a specific ratio and the amount is also required; if there is too much water, the amount of graphite release oil will be insufficient, and water residue may remain on the mold; if there is too little water, the cooling and rinsing will not be achieved, and the generated steam will be insufficient, which is also not convenient for spraying.

[0051] The upper die 19 is equipped with a cooling jacket containing coolant. After the roughing process is completed, the temperature of the heating section is greater than or equal to 850℃. After the rolling process is completed, the rolled bar 1 cools naturally.

[0052] The heating section after upsetting consists of, from bottom to top, a straight upsetting section 2, a lower conical upsetting section 3, and an upper conical upsetting section 4, resembling a spindle shape. The straight upsetting section 2 and the lower conical upsetting section 3 are formed by the lower die 20, while the upper conical upsetting section 4 is formed by the upper die 19. The diameter of the straight upsetting section 2 is larger than the diameter of the bar stock 1. The diameter of the lower conical upsetting section 3 gradually increases from bottom to top, forming a cone shape, and its lower end diameter is the same as the diameter of the straight upsetting section 2. The diameter of the upper conical upsetting section 4 gradually decreases from bottom to top, forming a cone shape, and its lower end diameter is the same as the upper end diameter of the lower conical upsetting section 3. Its upper end diameter is larger than the diameter of the bar stock 1, and its length is greater than the length of the lower conical upsetting section 3. Correspondingly, the shape of the upsetting die cavity matches the shape of the heating section after upsetting.

[0053] Specifically, in this embodiment of the invention, the length of the straight upsetting section 2 is 4-8 cm, and its diameter is 1.1-1.3 times the diameter of the bar stock 1. The length of the lower conical upsetting section 3 is 2-4 cm, and the diameter of its upper end is 1.3-1.5 times the diameter of the bar stock 1. The length of the upper conical upsetting section 4 is 8-15 cm, and the diameter of its upper end is 1.1-1.3 times the diameter of the bar stock 1.

[0054] The effectiveness of this method will be verified below:

[0055] The material of bar 1 is 40Cr steel, and the diameter of the bar is 30mm.

[0056] Comparative Example 1 uses the equipment with application number CN201910236600.0 (the equipment before the company's improvement) and the corresponding process. The amount of graphite release oil used is 15mL, and the number of test pieces is 200.

[0057] Comparative Example 2 uses the burring device of Example 2 of this application. In S104, no graphite release oil is added. The other steps are the same as those in Test Example 1. The number of test pieces is 200.

[0058] Comparative Example 3 uses the thickening device of Example 2 of this application, with water sprayed directly in S107, and the other steps are the same as those in Test Example 1. The number of test specimens is 200.

[0059] Comparative Example 4 uses the roughing device of Example 2 of this application, S107 direct graphite release oil (not convenient for spraying, so a nozzle with a larger spray hole is used), and other steps are the same as those in Test Example 1. The number of test pieces is 200.

[0060] Comparative Example 5 uses the burring device of Example 2 of this application. In S107, the graphite release oil solution is prepared by mixing graphite release oil and water at a mass ratio of 1:10. Other steps are the same as in Test Example 1. The number of test pieces is 200.

[0061] Comparative Example 6 uses the roughing device of Example 2 of this application. In S107, the graphite release oil solution is prepared by mixing graphite release oil and water at a mass ratio of 1:100. Other steps are the same as in Test Example 1. The number of test pieces is 200.

[0062] Test Example 1 uses the roughing device of Example 2 of this application. In step S104, the amount of graphite release oil is 45 mL; in S107, the graphite release oil solution is prepared by mixing graphite release oil and water at a mass ratio of 1:60, and the amount used is 15 mL; the number of test pieces is 200.

[0063] Test Example 2 uses the roughing device of Example 2 of this application. In S107, the graphite release oil solution is prepared by mixing graphite release oil and water at a mass ratio of 1:50. Other steps are the same as in Test Example 1. The number of test pieces is 200.

[0064] The results are shown in Table 1:

[0065] Table 1

[0066]

[0067] Table 1 shows that the demolding success rate of existing technologies is less than 80%. Comparative Example 1 shows that if the amount of graphite release oil is insufficient, the demolding success rate is very low. Comparative Examples 3 and 4 show that using only water spray or graphite release oil, while more effective than existing technologies, still only achieves a demolding success rate of around 85%. Comparative Examples 5 and 6 show that if the concentration of the graphite release oil is incorrect, there is essentially no improvement compared to Comparative Examples 3 or 4. Experimental Examples 1 and 2 show that the demolding success rate using this method is very high.

[0068] Example 2

[0069] See Figure 2-6 Example 2 provides an upsetting device for a half-shaft, which includes a hydraulic press, an upsetting die, a spray structure 15, a die-closing and locking structure 16, a cooling water nozzle 17, and a die-closing cylinder 18. The upsetting die includes an upper die 19 and a lower die 20, both vertically oriented. The lower die 20 is positioned on the worktable 5 of the hydraulic press, and the upper die 19 is located directly above it and can be driven up and down by the hydraulic press. The upper die 19 and the punch 10 are preferably guided by the same guide post 11 to ensure machining accuracy. The punch 10 of the hydraulic press is coaxially aligned with the bar stock 1 and located directly above the upper die 19; the punch 10 is a vertically oriented cylindrical structure. The lower die 20 consists of two half-dies arranged opposite each other and cooperating with each other. Each half-die has half a mold cavity, and the two half-dies are closed to form a single unit. The rear half-mold is fixed on the worktable 5, and the front half-mold is rotatably mounted on the worktable 5 or the rear half-mold, with a mold-closing cylinder 18 hinged between it and the worktable 5. The mold-closing cylinder 18 is arranged in the left-right direction; its extension allows the two half-molds to close, and its retraction allows the front half-mold to rotate so that the cavity of the rear half-mold is exposed. Specifically, the left or right side of the front half-mold is rotatably mounted on the worktable 5 via a vertically arranged pivot. The worktable 5 is provided with a mold-closing locking structure 16 for closing and locking the two half-molds; specifically, the mold-closing locking structure 16 and the mold-closing cylinder 18 are located on the left and right sides of the lower mold 20, respectively. The left side of the half-mold has a semi-circular protrusion along the left-right direction, and the two semi-circular protrusions are arranged opposite each other. After mold closing, the two semi-circular protrusions are spliced ​​together to form a cylinder. The mold clamping and locking structure 16 includes a mold clamping cylinder arranged in the left-right direction and mounted on the worktable 5, and a circular cover at the inner end of the telescopic rod of the mold clamping cylinder that mates with a ring cylinder. When the mold is clamped, the mold clamping cylinder extends, and the circular cover covers the cylinder and fits tightly with it. The spraying structure 15 can spray the mold cavity of the upper mold 19 in the downward direction of the upper mold 19. Specifically, the spraying structure 15 includes a bracket on the worktable 5, a horizontally arranged spraying cylinder on the bracket, and a vertically arranged nozzle at the inner end of the telescopic rod of the spraying cylinder. The nozzle is located adjacent to and below the lower mold 19 (when the lifting cylinder 12 retracts).

[0070] The aforementioned structure is basically the same as that of existing upsetting devices, except that: in this embodiment, the lower mold 20 has a locking boss 21 on its top, which is a circular boss coaxial with the bar stock 1. The top of the mold cavity of the lower mold 20 is coaxially mounted on the locking boss 21, and the bottom of the mold cavity of the upper mold 19 has a locking cavity 25 that mates with the locking boss 21. During upsetting, the locking cavity 25 is fitted onto the locking boss 21, and the top of the locking boss 21 rests against the top of the locking cavity 25. Preferably, the outer diameter of the upper part of the locking boss 21 gradually increases from top to bottom to form a cone shape (with a small inclination angle), and the locking cavity 25 is a conical hole. The cooling water nozzle 17 includes two nozzles (specifically, bamboo-joint water pipes), which are located above the two half-molds after unfolding.

[0071] Among them, see Figure 3-6 In this embodiment of the invention, the lower mold 20 has a cavity that, from bottom to top, is divided into a lower through hole 22, a straight upsetting mold cavity 23, and a lower conical upsetting mold cavity 24. The upper mold 19 has a cylindrical structure, and its cavity, from bottom to top, is divided into a locking cavity 25, an upper upsetting mold cavity 26, and an upper through hole 27. The lower through hole 22, the straight upsetting mold cavity 23, the lower conical upsetting mold cavity 24, the locking cavity 25, the upper upsetting mold cavity 26, and the upper through hole 27 are all coaxially arranged with the bar stock 1. The lower through hole 22, the straight upsetting mold cavity 23, and the upper through hole 27 are all circular holes. The lower conical upsetting mold cavity 24 is a tapered hole that gradually increases in size from bottom to top, and the upper upsetting mold cavity 26 is a tapered hole that gradually increases in size from top to bottom. The inner diameter of the lower through hole 22 matches the diameter of the bar stock 1 to achieve a clearance fit. The inner diameter of the locking cavity 25 matches the diameter of the locking boss 21 to achieve a tight fit. The inner diameter of the upper through hole 27 matches the diameter of the punch 10 to achieve a clearance fit. The straight upsetting forming mold cavity 23, the lower conical upsetting forming mold cavity 24, and the upper upsetting forming mold cavity 26 form the mold cavity of the upsetting mold and are respectively used to form the straight upsetting section 2, the lower conical upsetting section 3, and the upper conical upsetting section 4.

[0072] Among them, see Figure 2The hydraulic punch press in this embodiment of the invention includes a worktable 5, a head 6 above the worktable 5, a hydraulic cylinder 7 vertically arranged in the middle of the head 6, a lower lifting plate 8 capable of vertical movement, an upper lifting plate 9 capable of vertical movement, a punch 10 vertically arranged in the middle of the lower side of the upper lifting plate 9, four guide columns 11 vertically arranged between the head 6 and the worktable 5, two lifting cylinders 12 vertically arranged on the head 6, and a guide positioning groove 13 arranged along the front-back direction below the worktable 5. The worktable 5, lower lifting plate 8, upper lifting plate 9, and head 6 are arranged sequentially from bottom to top, and the worktable 5, lower lifting plate 8, and upper lifting plate 9 are all horizontally arranged. The upper lifting plate 9 and lower lifting plate 8 are both rectangular plates arranged along the left-right direction and cooperating with each other. The four guide columns 11 are arranged in a rectangular pattern, and each guide column 11 is a smooth round rod. The four corners of the upper lifting plate 9 and lower lifting plate 8 are respectively slidably (through vertically arranged sliding sleeves) on the four guide columns 11. The lower die 20 is located in the middle of the lower lifting plate 8, and the lower end of the telescopic rod of the hydraulic cylinder 7 is fixedly connected to the upper side of the upper lifting plate 9. Two lifting cylinders 12 are located on the left and right sides of the machine head 6 and are driven synchronously. Their telescopic rods pass downward through the upper lifting plate 9, and their lower ends are fixedly connected to the upper side of the lower lifting plate 8. On the worktable 5, the front of the half-die located on the rear side is provided with a notch 14 (specifically a flared opening that is larger at the front and smaller at the back) for vertically inserting the bar stock 1. The guide positioning groove 13 is a rectangular groove with an open front side, which allows the lower end of the bar stock 1 to be vertically inserted, and its rear end is located directly below the rear half-die. The punch 10 is coaxially provided with a limiting protrusion 28 in the middle, and the limiting protrusion 28 cannot pass through the upper lifting plate 9. When the lifting cylinder 12 extends, the locking cavity 25 is fitted onto the locking boss 21; when the hydraulic cylinder 7 extends, the punch 10 presses against the top of the bar stock 1 to form a rough shape; during the rough shape formation, the limiting protrusion ring 28 rests against the upper side of the upper lifting plate 9.

[0073] 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 method of forging a half shaft comprising the steps of intermediate frequency heating, upsetting and roll turning, characterised in that, The roughing process comprises: S101: vertically placing the heated rod (1) on the roughing device, with the heated end of the rod (1) upward and at the roughing die of the roughing device; S102: extending the closing oil cylinder (18) of the roughing device to allow the lower die (20) of the roughing device to close and tightly hold the lower part of the heated end, and then locking the lower die (20) by the closing locking structure (16) of the roughing device; S103: moving the upper die (19) of the roughing device downward to be sleeved on the heated end and tightly sleeved on the locking boss (21) at the top of the lower die (20); S104: adding graphite demolding oil to the top of the cavity of the upper die (19); S105: moving the punch (10) of the roughing device downward into the upper die (19) to press the top of the rod (1) downward to roughen and form; S106: after the roughing and forming is completed, moving the punch (10) upward, and then moving the upper die (19) upward above the rod (1), at this time, the lower end of the punch (10) is located in the upper through hole (27) of the upper die (19); S107: spraying graphite demolding oil solution into the cavity of the upper die (19) from the lower part of the upper die (19), the graphite demolding oil solution is prepared by mixing graphite demolding oil and water at a mass ratio of 1:45-70; at the same time, the closing locking structure (16) is reset, the closing oil cylinder (18) is retracted to open the lower die (20), and the roughened and formed rod (1) is taken out; S108: spraying water by the cooling water nozzle (17) of the roughing device to the lower die (20) to cool the lower die (20) and wash the surface graphite demolding oil; In step S104, the amount of graphite demolding oil is 40-50 mL; In step S107, the process of spraying graphite demolding oil solution is: the spraying amount is 10-20 mL, and the spraying time is 3-5 s.

2. The method of forging a half shaft as defined in claim 1, wherein, The process of medium frequency heating is: heating to 1050-1150℃, and the heating time is 160-200 s.

3. The method of forging a semi-axle of claim 1, wherein, The upper die (19) is provided with a cooling jacket, the temperature of the heating section after the roughing process is completed is greater than or equal to 850℃, and after the rolling process is completed, the rod (1) after rolling is naturally cooled.

4. The method of forging a semi-axle of claim 1, wherein, The heating section after roughing is sequentially straight roughing section (2), lower conical roughing section (3) and upper conical roughing section (4) from bottom to top, the straight roughing section (2) and the lower conical roughing section (3) are formed by the lower die (20), the upper conical roughing section (4) is formed by the upper die (19), the diameter of the straight roughing section (2) is larger than that of the rod (1), the diameter of the lower conical roughing section (3) gradually increases from bottom to top, and the diameter of the lower end is the same as that of the straight roughing section (2); the diameter of the upper conical roughing section (4) gradually decreases from bottom to top, the diameter of the lower end is the same as that of the upper end of the lower conical roughing section (3), the diameter of the upper end is larger than that of the rod (1), and the length is larger than that of the lower conical roughing section (3).

5. The method of forging a semi-axle of claim 4, wherein, The length of the straight stub (2) is 4-8 cm, and its diameter is 1.1-1.3 times of the diameter of the bar (1); the length of the lower conical stub (3) is 2-4 cm, and the diameter of its upper end is 1.3-1.5 times of the diameter of the bar (1); the length of the upper conical stub (4) is 8-15 cm, and the diameter of its upper end is 1.1-1.3 times of the diameter of the bar (1).

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