Helical gear shaft precision die forging method

Abstract

The invention discloses a precision die forging method for a helical gear shaft, and belongs to the field of forging. The problems that demolding is difficult and corner parts are difficult to form due to a space spiral structure of an existing helical gear shaft are solved. The method comprises the following steps: 1, designing a helical gear shaft forging; 2, designing a mold; and 3, forming. The method is used for precise die forging of the helical gear shaft.

Description

Technical Field

[0001] This invention belongs to the field of forging. Background Technology

[0002] Helical gear shafts, due to their advantages such as multi-tooth meshing, high load-bearing capacity, and smooth transmission, are widely used in aerospace, shipbuilding, and automotive parts industries. This has placed higher demands on the gear's material properties, tensile strength, and bending fatigue resistance. Compared to simple free forging and machining, precision forging of gears offers higher material utilization and better service performance. However, compared to spur gears, the forging difficulty of helical gear shafts is significantly higher. This is mainly because the tooth profile of helical gear shafts is a spatial helical structure, requiring mold design to consider the helical path during metal filling. The spatial helical structure of the tooth profile restricts traditional axial demolding methods, making demolding difficult. Furthermore, the metal flow path relies on the spatial helical shape of the mold gear, making it difficult to form the corners and edges. Therefore, developing a reasonable helical gear shaft forging mold structure and demolding method has become an urgent problem to be solved. Summary of the Invention

[0003] The present invention aims to solve the problems of difficult demolding and difficult forming of corner parts caused by the spatial helical structure of existing helical gear shafts, and thus provides a precision forging method for helical gear shafts.

[0004] A precision forging method for helical gear shafts, comprising the following steps:

[0005] I. Design of Helical Gear Shaft Forgings:

[0006] Design helical gear shaft forgings based on helical gear shaft components;

[0007] The helical gear shaft part consists of a shaft portion, a web, and gear teeth. The web is arranged circumferentially along the shaft portion, and the gear teeth are arranged circumferentially along the web. Let the diameter of the helical gear shaft part be R0, the maximum height be H0, and the tooth width be h0.

[0008] The helical gear shaft forging consists of a forged shaft portion, a forged web, and forged gear teeth. The forged web is arranged circumferentially along the shaft portion, and the forged gear teeth are arranged circumferentially along the web. The diameter of the helical gear shaft forging is R, the maximum height is H, and the width of the forged gear teeth is h.

[0009] The R:R0 = (1.067~1.08):1; the H:H0 = (1.05~1.2):1; the h:h0 = (1.17~1.19):1; the machining allowance at the tooth tip of the forged gear is 3.5mm~5.5mm, and the machining allowance on the tooth surface is 1.5mm~2mm;

[0010] II. Mold Design:

[0011] Design a precision forging die for helical gear shaft based on the helical gear shaft forging;

[0012] The precision forging die for helical gear shaft comprises an upper die, a pressure plate, a pressure ring, a lower die, an ejector structure, and a segmented die. The upper die is a punch, and the lower die is a die. The ejector structure is located in the middle of the lower die. The segmented die and the pressure ring are arranged inside the lower die cavity. The segmented die is pre-divided into 11 segmented die units along the helical gear direction. A pressure ring is arranged above the segmented die. A pressure plate is arranged above the pressure ring. The upper die, lower die, segmented die, and ejector structure together form the cavity of the helical gear shaft forging.

[0013] Let the outer diameter of the segmented mold be B5 and the height be B4; wherein B5:R = (1.52~1.6):1; wherein B4:h = 1:1;

[0014] III. Shaping:

[0015] ① Lubricate and heat the blank and the precision forging die for the helical gear shaft;

[0016] ② Place the heated blank into the cavity formed by the lower mold, the segmented mold, and the ejector structure;

[0017] ③ The upper die moves at a speed of 50mm / s to 60mm / s. Press the upper die down to the under-pressure height to complete the precision forging method of the helical gear shaft.

[0018] The beneficial effects of this invention are:

[0019] I. This invention enables precision die forging of helical gear shafts, solving the problem of filling difficulties caused by the spatial spiral structure during helical gear shaft forging. Compared with gears manufactured by free forging and machining, it has a higher material utilization rate.

[0020] 2. The mold for the helical gear shaft teeth is divided along the tooth profile direction and designed as 11 segmented molds. By controlling the number of teeth and tooth profile of each segment mold, radial demolding is performed. During the demolding process, a radial pull-out demolding method is adopted to solve the demolding difficulty caused by helix angle interference.

[0021] Third, compared to the overall gear diameter, the helical gear shaft has a smaller tooth height and shallower tooth area, resulting in insufficient deformation of the tooth profile and difficulty in distributing metal flow lines along the tooth contour. This invention provides a precision forging die for helical gear shafts and adjusts the design parameters of the tooth profile during forging to regulate the deformation of the tooth profile during the forging process, thereby achieving a conformal distribution of metal flow lines in the tooth profile of the forging. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the structure of the helical gear shaft part in step one of the present invention;

[0023] Figure 2 This is a cross-sectional view of the helical gear shaft part in step one of the present invention;

[0024] Figure 3 This is a cross-sectional view of the helical gear shaft forging from step one of the present invention.

[0025] Figure 4 This is a three-dimensional view of the precision forging die for the helical gear shaft in step two of this invention.

[0026] Figure 5 This is a three-dimensional view of the cavity formed by the lower mold, the segmented mold, and the ejector structure in step two of this invention.

[0027] Figure 6 This is a cross-sectional view of the precision forging die for the helical gear shaft in step two of this invention.

[0028] Figure 7 This is a side view of the upper mold in step two of the present invention;

[0029] Figure 8 This is a perspective view of the upper mold in step two of the present invention;

[0030] Figure 9 This is a perspective view of the lower mold in step two of the present invention;

[0031] Figure 10 This is a perspective view of the tooth surface of a single segmented mold unit in step two of the present invention;

[0032] Figure 11 This is a rear perspective view of a single segmented mold unit in step two of the present invention;

[0033] Figure 12 This is a perspective view of the pressure ring in step two of the present invention;

[0034] Figure 13 This is a perspective view of the pressure plate in step two of the present invention;

[0035] Figure 14 This is a perspective view of the ejection structure in step two of the present invention;

[0036] Figure 15 This is a perspective view of the guide post in step two of the present invention;

[0037] Figure 16 This is a perspective view showing the positional relationship between the guide post and the lower mold in step two of this invention.

[0038] Figure 17The following is a simulated cross-sectional view of the precision forging of the helical gear shaft in Example 1: a represents 0% pressure, b represents 20% pressure, c represents 40% pressure, d represents 60% pressure, e represents 80% pressure, and f represents under-pressure of 2mm to 3mm.

[0039] Figure 18 This is a load curve diagram of the precision forging simulation process of the helical gear shaft in Example 1;

[0040] Figure 19 This is a schematic diagram of the tooth profile of the forged gear teeth in step one of Example 1;

[0041] Figure 20 The metal flow line diagram of the tooth profile of the helical gear shaft forging prepared in Example 1;

[0042] Figure 21 This is a schematic diagram of the tooth profile of the forged wheel teeth in step one of Example 2;

[0043] Figure 22 The diagram shows the metal flow lines of the tooth profile of the helical gear shaft forging prepared in Example 2.

[0044] Figure 23 A schematic diagram of the tooth profile of the forged gear in step one of the first experiment;

[0045] Figure 24 The metal streamline diagram of the tooth profile of the helical gear shaft forging prepared in Experiment 1 is shown for comparison. Detailed Implementation

[0046] Specific implementation method one, combined with Figures 1 to 16 Detailed explanation: This embodiment of a precision forging method for helical gear shaft is carried out according to the following steps:

[0047] I. Design of Helical Gear Shaft Forgings:

[0048] Design helical gear shaft forgings based on helical gear shaft components;

[0049] The helical gear shaft part consists of a shaft portion 7-1, a web portion 7-2, and gear teeth 7-3. The web portion 7-2 is arranged circumferentially along the shaft portion 7-1, and the gear teeth 7-3 are arranged circumferentially along the web portion 7-2. The diameter of the helical gear shaft part is R0, the maximum height is H0, and the width of the gear teeth 7-3 is h0.

[0050] The helical gear shaft forging consists of a forged shaft portion 8-1, a forged web 8-2, and forged gear teeth 8-3. The forged web 8-2 is arranged circumferentially along the forged shaft portion 8-1, and the forged gear teeth 8-3 are arranged circumferentially along the forged web 8-2. The diameter of the helical gear shaft forging is R, the maximum height is H, and the width of the forged gear teeth 8-3 is h.

[0051] The R:R0 = (1.067~1.08):1; the H:H0 = (1.05~1.2):1; the h:h0 = (1.17~1.19):1; the machining allowance at the tooth tip of the forged gear tooth 8-3 is 3.5mm~5.5mm, and the machining allowance on the tooth surface is 1.5mm~2mm;

[0052] II. Mold Design:

[0053] Design a precision forging die for helical gear shaft based on the helical gear shaft forging;

[0054] The precision forging die for helical gear shaft consists of an upper die 1, a pressure plate 2, a pressure ring 3, a lower die 4, an ejector structure 5, and a segmented die 6. The upper die 1 is a punch, and the lower die 4 is a die. The ejector structure 5 is located in the middle of the lower die 4. The segmented die 6 and the pressure ring 3 are arranged inside the cavity of the lower die 4. The segmented die 6 is pre-divided into 11 segmented die units along the helical gear direction. The pressure ring 3 is arranged above the segmented die 6. The pressure plate 2 is arranged above the pressure ring 3. The upper die 1, the lower die 4, the segmented die 6, and the ejector structure 5 together form the cavity of the helical gear shaft forging.

[0055] Let the outer diameter of the segmented mold 6 be B5 and its height be B4; wherein B5:R = (1.52~1.6):1; wherein B4:h = 1:1;

[0056] III. Shaping:

[0057] ① Lubricate and heat the blank and the precision forging die for the helical gear shaft;

[0058] ② The heated blank is placed in the cavity formed by the lower mold 4, the segmented mold 6 and the ejector structure 5;

[0059] ③ The moving speed of the upper die 1 is 50mm / s~60mm / s. Press the upper die 1 down to the under-pressure height to complete the precision forging method of the helical gear shaft.

[0060] In the specific implementation step one, the web plate 7-2 of the part is relatively thin. In the design of the forging, in order to make the metal flow path smoother, only the upper part of the web plate is set with a concave shape that conforms to the part, and the lower part of the web plate is solid.

[0061] In the second step of the specific implementation method, the shape of the mold cavity is designed according to the shape of the forging. The upper mold is set as a whole with the shape of the forging and a sloping step is made, such as... Figure 7 As shown at point ①, the pressure plate is avoided and a flash groove is formed, which at the same time enhances the strength of the mold;

[0062] In step two of the specific implementation method, since the helical gear shaft is difficult to demold, the gear part of the lower mold adopts a segmented mold, the segmented mold is pressed by a pressure ring, and the overall lower mold cavity structure is fixed by a pressure plate; at the same time, the lower mold also includes an ejector structure, located in the middle of the lower mold, which together with other parts forms a cavity, and a stepped cylinder is set below the ejector rod to bear the force of the central part during forging;

[0063] In step two of the specific implementation method, the tooth-shaped mold is set as a segmented mold structure, divided into 11 segments along the oblique tooth direction. The number of teeth in each segment is controlled to achieve smooth radial demolding. Each segment has reasonable rounded corners at the upper and lower edges and at the junctions of the segments to ensure the fullness of the forging. The tooth-shaped mold of each segment is designed according to the shape of the tooth part of the forging, and an oblique chamfer is made on the top to avoid the flash wrapping around the mold and preventing smooth demolding. A lifting hole is installed on the top and side of the segmented module to facilitate installation and radial demolding.

[0064] In step three of the specific implementation method, the pressing process is guided by two guide pillars located diagonally on the lower die; the overall dimensions of the die are determined by combining the die cavity depth and the pressing load. After forging is completed, the pressure plate is opened, the pressure ring is removed, and the segmented die and forging are ejected. At this time, the segmented die will automatically detach from the forging.

[0065] The beneficial effects of this specific implementation method are:

[0066] I. This specific embodiment can perform precision die forging of helical gear shafts, solving the problem of filling difficulties caused by the spatial spiral structure during helical gear shaft forging. Compared with gears manufactured by free forging and machining, it has a higher material utilization rate.

[0067] 2. The mold for the helical gear shaft teeth is divided along the tooth profile direction and designed as 11 segmented molds. By controlling the number of teeth and tooth profile of each segment mold, radial demolding is performed. During the demolding process, a radial pull-out demolding method is adopted to solve the demolding difficulty caused by helix angle interference.

[0068] Third, compared to the overall gear diameter, the helical gear shaft has a smaller tooth height and shallower tooth area, resulting in insufficient deformation of the tooth profile and difficulty in distributing metal flow lines along the tooth contour. This specific embodiment provides a precision forging die for helical gear shaft, and adjusts the design parameters of the tooth profile of the helical gear shaft forging to adjust the deformation of the tooth profile during forging, so as to achieve the purpose of conforming the metal flow lines of the tooth profile of the forging.

[0069] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the shaft portion 7-1 mentioned in step one is a hollow stepped bushing; the tooth profile helix angle of the gear teeth 7-3 mentioned in step one is 10°~15°, the tooth height is 8mm~15mm, and the tooth width is 8mm~10mm; the upper surface of the forged web 8-2 mentioned in step one is conformally set to the upper surface of the web 7-2 of the part, and the lower surface of the forged web 8-2 is flush with the end of the forged gear teeth 8-3; the angle between the outer sidewall surface of the shaft portion 7-1 mentioned in step one and the upper surface of the web 7-2 of the part is 100°; the angle between the outer sidewall surface of the forged shaft portion 8-1 mentioned in step one and the upper surface of the forged web 8-2 of the part is 100°. Everything else is the same as in Specific Implementation Method One.

[0070] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the upper die 1 described in step two has a punch at its lower part, and the upper part of the punch has a stepped structure; the upper diameter of the stepped structure is C1, the height is C2, and the lower diameter is C3; C1:h = (5.1~7):1; C2:h = (1~1.15):1; C3:h = (3.4~6):1; the lower part of the ejector structure 5 described in step two is a stepped cylinder. Everything else is the same as in Specific Implementation Method One or Two.

[0071] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the upper and lower edges of the 11 segmented mold units mentioned in step two, as well as the contact surfaces between the segmented mold units, are all chamfered, with a chamfer radius of 1mm to 2mm. Everything else is the same as in Specific Implementation Methods One to Three.

[0072] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the angle between the outer sidewall surface of the segmented mold 6 described in step two and the horizontal plane is 7°; the angle between the upper toothed surface of the 11 segmented mold units described in step two and the horizontal plane is 45°. Everything else is the same as in Specific Implementation Methods One to Four.

[0073] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the upper surface and outer sidewall surface of the 11 segmented mold units described in step two are provided with lifting holes. Otherwise, it is the same as Specific Implementation Methods One to Five.

[0074] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: guide post holes are provided at the diagonal positions of the upper mold 1, pressure plate 2, and lower mold 4 mentioned in step two, and guide posts are installed in the guide post holes. Everything else is the same as Specific Implementation Methods One to Six.

[0075] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the billet material mentioned in step three① is 10CrNi2Mo3Cu2V; the billet is a cylindrical billet with chamfers on both the upper and lower surfaces, and the chamfer radius is 25mm; the diameter of the billet is R1, R1:R = (0.66~0.7):1; the height of the billet is H1, H1:H = (1.2~1.32):1. Everything else is the same as in Specific Implementation Methods One to Seven.

[0076] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step three①, the billet and the precision forging die for the helical gear shaft are lubricated and heated to 200℃~300℃. Everything else is the same as in Specific Implementation Methods One to Eight.

[0077] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the undervoltage height mentioned in step three ③ is 2mm~3mm. Everything else is the same as Specific Implementation Methods One to Nine.

[0078] The beneficial effects of the present invention are verified using the following embodiments:

[0079] Example 1, combined with Figure 19 Detailed explanation:

[0080] A precision forging method for helical gear shafts, comprising the following steps:

[0081] I. Design of Helical Gear Shaft Forgings:

[0082] Design helical gear shaft forgings based on helical gear shaft components;

[0083] The helical gear shaft component consists of a shaft portion 7-1, a web portion 7-2, and gear teeth 7-3. The web portion 7-2 is arranged circumferentially along the shaft portion 7-1, and the gear teeth 7-3 are arranged circumferentially along the web portion 7-2. Let the diameter of the helical gear shaft component be R0, the maximum height be H0, and the height of the gear teeth 7-3 be h0; R0 = 280mm, H0 = 180mm, h0 = 60mm.

[0084] The helical gear shaft forging consists of a forged shaft portion 8-1, a forged web 8-2, and forged gear teeth 8-3. The forged web 8-2 is arranged circumferentially along the forged shaft portion 8-1, and the forged gear teeth 8-3 are arranged circumferentially along the forged web 8-2. Let the diameter of the helical gear shaft forging be R, the maximum height be H, and the width of the forged gear teeth 8-3 be h; R=300mm, H=190mm, h=70mm.

[0085] The forged gear tooth 8-3 has a tooth height of 10.5 mm, a tooth tip machining allowance of 5.5 mm, a tooth width of 9.6 mm, and a tooth surface machining allowance of 1.8 mm.

[0086] II. Mold Design:

[0087] Design a precision forging die for helical gear shaft based on the helical gear shaft forging;

[0088] The precision forging die for helical gear shaft consists of an upper die 1, a pressure plate 2, a pressure ring 3, a lower die 4, an ejector structure 5, and a segmented die 6. The upper die 1 is a punch, and the lower die 4 is a die. The ejector structure 5 is located in the middle of the lower die 4. The segmented die 6 and the pressure ring 3 are arranged inside the cavity of the lower die 4. The segmented die 6 is pre-divided into 11 segmented die units along the helical gear direction. The pressure ring 3 is arranged above the segmented die 6. The pressure plate 2 is arranged above the pressure ring 3. The upper die 1, the lower die 4, the segmented die 6, and the ejector structure 5 together form the cavity of the helical gear shaft forging.

[0089] Let the outer diameter of the segmented mold 6 be B5 and the height be B4; B5 = 460mm, B4 = 70mm;

[0090] III. Shaping:

[0091] ① Lubricate and heat the blank and the precision forging die for the helical gear shaft;

[0092] ② The heated blank is placed in the cavity formed by the lower mold 4, the segmented mold 6 and the ejector structure 5;

[0093] ③ The moving speed of the upper die 1 is 55mm / s. Press the upper die 1 down to the under-pressure height to complete the precision forging method of the helical gear shaft.

[0094] The shaft portion 7-1 mentioned in step one is a hollow stepped bushing; the tooth profile helix angle of the gear tooth 7-3 mentioned in step one is 11°, the tooth height is 8.5mm, and the tooth width is 10mm; the upper surface of the forging web 8-2 mentioned in step one is conformally set to the upper surface of the web 7-2 of the part, and the lower surface of the forging web 8-2 is flush with the end of the forging gear tooth 8-3; the angle between the outer sidewall surface of the shaft portion 7-1 mentioned in step one and the upper surface of the web 7-2 of the part is 100°; the angle between the outer sidewall surface of the forging shaft portion 8-1 mentioned in step one and the upper surface of the forging web 8-2 of the part is 100°.

[0095] In step two, the upper die 1 is provided with a punch at the bottom, and the upper part of the punch is a stepped structure; the upper diameter of the stepped structure is C1, the height is C2, and the lower diameter is C3; C1=360mm, C2=80mm, C3=240mm; the lower part of the ejection structure 5 in step two is a stepped cylinder.

[0096] In step two, the upper and lower edges of the 11 segmented mold units and the contact surfaces between the segmented mold units are all chamfered, with a chamfer radius of 1mm to 2mm.

[0097] The angle between the outer sidewall surface of the segmented mold 6 described in step two and the horizontal plane is 7°; the angle between the upper surface of the toothed part of the 11 segmented mold units described in step two and the horizontal plane is 45°.

[0098] The 11 segmented mold units mentioned in step two are provided with lifting holes on their upper surface and outer sidewall surface.

[0099] In step two, guide pin holes are provided at the diagonal positions of the upper mold 1, pressure plate 2, and lower mold 4, and guide pins are installed in the guide pin holes.

[0100] The billet material mentioned in step 3① is 10CrNi2Mo3Cu2V; the billet is a cylindrical billet with chamfers on both the upper and lower surfaces, and the chamfer radius is 25mm; the diameter of the billet is R1, R1=200mm; the height of the billet is H1, H1=250mm.

[0101] In step 3①, the blank and the precision forging die for the helical gear shaft are lubricated and heated to 300℃.

[0102] The undervoltage height mentioned in step 3③ is 2mm~3mm.

[0103] Figure 17 The figure shows a cross-sectional view of the precision forging simulation of the helical gear shaft in Example 1. a represents 0% pressure, b represents 20% pressure, c represents 40% pressure, d represents 60% pressure, e represents 80% pressure, and f represents under-pressure of 2mm-3mm. As shown in the figure, during the forging process, in the first 60% of the pressure (a-d), the upper die contacts the blank and undergoes a process similar to upsetting, filling the gear shaft position of the lower die. As deformation continues, at 80% pressure (e), the gear and the gear shaft portion of the upper die begin to fill. Due to its largest diameter, it exhibits better lateral filling and flow compared to the previous two stages, resulting in a more uniform overall forming process and facilitating the formation of the gear portion. The gear forming is completed when the under-pressure reaches 2mm-3mm. Finally, excess material flows out from the outside of the gear (f), and the flash overflows at the red box in figure (f), indicating that the corners of the gear surface are completely filled.

[0104] Figure 18 The figure shows the load curve of the precision forging process of the helical gear shaft in Example 1. As can be seen from the figure, the forging is completely filled when the load is 4960T.

[0105] Figure 20The figure shows the metal streamline diagram of the tooth profile of the helical gear shaft forging prepared in Example 1. As can be seen from the figure, due to the largest tooth tip allowance, the metal deformation space is the largest during forging, the deformation amount is the largest, and the metal streamline conformity of the gear part is the best, which can basically achieve the conformal distribution of metal streamline.

[0106] Example 2, combined with Figure 21 Specific details: This embodiment differs from Embodiment 1 in that the tooth height of the forged gear tooth 8-3 is 8.5mm, the tooth tip allowance is 3.5mm, the tooth width is 9.6mm, and the tooth surface allowance is 1.8mm. Everything else is the same as in Embodiment 1.

[0107] Figure 22 The figure shows the metal streamline diagram of the tooth profile of the helical gear shaft forging prepared in Example 2. As can be seen from the figure, due to the increase in tooth tip allowance, the deformation of the tooth profile during forging is increased, and the conformity of the metal streamline of the gear is improved compared with the tooth profile in Comparative Experiment 1.

[0108] Compared with Experiment 1, combined Figure 23 Specific details: The difference between this comparative experiment and Example 1 is that the tooth height of the forged gear 8-3 is 5mm, the tooth tip allowance is 1.5mm, the tooth width is 8.1mm, and the tooth surface allowance is 1.5mm. Everything else is the same as in Example 1.

[0109] Figure 24 To compare the metal streamline diagram of the tooth profile of the helical gear shaft forging prepared in Experiment 1; as can be seen from the figure, due to the small allowance at the tooth tip and the small amount of deformation reserved, the metal streamline conformity of the gear part is poor.

Claims

1. A precision forging method for helical gear shafts, characterized in that... It is done in the following steps: I. Design of Helical Gear Shaft Forgings: Design helical gear shaft forgings based on helical gear shaft components; The helical gear shaft part consists of a shaft part (7-1), a web part (7-2), and gear teeth (7-3). The web part (7-2) is arranged circumferentially along the shaft part (7-1), and the gear teeth (7-3) are arranged circumferentially along the web part (7-2). Let the diameter of the helical gear shaft part be R0, the maximum height be H0, and the width of the gear teeth (7-3) be h0. The helical gear shaft forging consists of a forged shaft portion (8-1), a forged web (8-2), and forged gear teeth (8-3). The forged web (8-2) is arranged circumferentially along the forged shaft portion (8-1), and the forged gear teeth (8-3) are arranged circumferentially along the forged web (8-2). Let the diameter of the helical gear shaft forging be R, the maximum height be H, and the width of the forged gear teeth (8-3) be h. The R:R0 = (1.067~1.08):1; the H:H0 = (1.05~1.2):1; the h:h0 = (1.17~1.19):1; the machining allowance at the tooth tip of the forged gear tooth (8-3) is 3.5mm~5.5mm, and the machining allowance on the tooth surface is 1.5mm~2mm; II. Mold Design: Design a precision forging die for helical gear shaft based on the helical gear shaft forging; The precision forging die for the helical gear shaft consists of an upper die (1), a pressure plate (2), a pressure ring (3), a lower die (4), an ejector structure (5), and a segmented die (6); the upper die (1) is a punch, and the lower die (4) is a die; the ejector structure (5) is located in the middle of the lower die (4); the segmented die (6) and the pressure ring (3) are arranged inside the cavity of the lower die (4); the segmented die (6) is pre-divided into 11 segmented die units along the helical gear direction; the pressure ring (3) is arranged above the segmented die (6); the pressure plate (2) is arranged above the pressure ring (3); the upper die (1), the lower die (4), the segmented die (6), and the ejector structure (5) together form the cavity of the helical gear shaft forging. Let the outer diameter of the segmented mold (6) be B5 and the height be B4; B5:R = (1.52~1.6):1; B4:h = 1:1; III. Shaping: ① Lubricate and heat the blank and the precision forging die for the helical gear shaft; ② The heated blank is placed in the cavity formed by the lower mold (4), the segmented mold (6) and the ejector structure (5); ③ The moving speed of the upper die (1) is 50mm / s~60mm / s. Press the upper die (1) down to the under-pressure height to complete the precision forging method of helical gear shaft.

2. The precision forging method for a helical gear shaft according to claim 1, characterized in that... The shaft portion (7-1) of the part mentioned in step one is a hollow stepped bushing; the tooth profile helix angle of the gear teeth (7-3) of the part mentioned in step one is 10°~15°, the tooth height is 8mm~15mm, and the tooth width is 8mm~10mm; the upper surface of the web plate (8-2) of the forging mentioned in step one is set to conform to the upper surface of the web plate (7-2) of the part, and the lower surface of the web plate (8-2) of the forging is flush with the end of the gear teeth (8-3); the angle between the outer sidewall surface of the shaft portion (7-1) of the part mentioned in step one and the upper surface of the web plate (7-2) of the part is 100°; the angle between the outer sidewall surface of the shaft portion (8-1) of the forging mentioned in step one and the upper surface of the web plate (8-2) of the forging is 100°.

3. The precision forging method for a helical gear shaft according to claim 1, characterized in that... In step two, the upper die (1) is provided with a punch at the bottom, and the upper part of the punch is a stepped structure; the upper diameter of the stepped structure is C1, the height is C2, and the lower diameter is C3; C1:h=(5.1~7):1; C2:h=(1~1.15):1; C3:h=(3.4~6):1; the lower part of the ejection structure (5) in step two is a stepped cylinder.

4. The precision forging method for a helical gear shaft according to claim 1, characterized in that... In step two, the upper and lower edges of the 11 segmented mold units and the contact surfaces between the segmented mold units are all chamfered, with a chamfer radius of 1mm to 2mm.

5. The precision forging method for a helical gear shaft according to claim 1, characterized in that... The angle between the outer sidewall surface of the segmented mold (6) in step two and the horizontal plane is 7°; the angle between the upper tooth surface of the 11 segmented mold units in step two and the horizontal plane is 45°.

6. The precision forging method for a helical gear shaft according to claim 1, characterized in that... The 11 segmented mold units mentioned in step two are provided with lifting holes on their upper surface and outer sidewall surface.

7. The precision forging method for a helical gear shaft according to claim 1, characterized in that... In step two, guide pin holes are provided at the diagonal of the upper mold (1), pressure plate (2) and lower mold (4), and guide pins are provided in the guide pin holes.

8. The precision forging method for a helical gear shaft according to claim 1, characterized in that... The billet material mentioned in step 3① is 10CrNi2Mo3Cu2V; the billet is a cylindrical billet with chamfers on both the upper and lower surfaces, and the chamfer radius is 25mm; let the diameter of the billet be R1, R1:R=(0.66~0.7):1; let the height of the billet be H1, H1:H=(1.2~1.32):

1.

9. A precision forging method for a helical gear shaft according to claim 1, characterized in that... In step 3①, the blank and the precision forging die for the helical gear shaft are lubricated and heated to 200℃~300℃.

10. A precision forging method for a helical gear shaft according to claim 1, characterized in that... The undervoltage height mentioned in step 3③ is 2mm~3mm.

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