Rolling and forging combined production method for gearbox intermediate gear shaft blank and forging die

Abstract

The present invention discloses a rolling and forging combined production method and a forging die for a gearbox intermediate gear shaft blank, which is characterized in that: it is manufactured by the following steps: selecting a bar with a diameter of 80 mm; medium frequency heating; rolling it into a gearbox intermediate gear shaft rolling blank by a wedge cross rolling mill; and forging it into a gearbox intermediate gear shaft blank by a press. The present invention uses a small diameter bar to produce a gearbox intermediate gear shaft blank with a large diameter disc, so that the large disc of the gearbox intermediate gear shaft blank can undergo stress deformation, prevent internal looseness, ensure product quality, reduce the cost of production raw materials, and improve economic benefits.

Description

Technical Field

[0001] The present invention relates to an improvement in a method for producing a gearbox intermediate gear shaft blank, and more specifically to a rolling and forging combined production method and a forging die for the gearbox intermediate gear shaft blank, which uses a small-diameter bar to produce a gearbox intermediate gear shaft blank with a large-diameter disc, so that the large-diameter outer circle of the gearbox intermediate gear shaft blank can undergo stress deformation, thereby preventing internal looseness and ensuring product quality. Background Art

[0002] The gearbox intermediate gear shaft is a transmission part of an automobile transmission. It is made from the gearbox intermediate gear shaft blank after fine processing. At present, the gearbox intermediate gear shaft blank is generally made by wedge cross rolling production method. The shape of the gearbox intermediate gear shaft blank is as follows: Figure 1 As shown, the total length of the gearbox intermediate gear shaft blank is 368mm, which is composed of a tapered shaft 1, a large disc 2, a connecting shaft 3, a small disc 4 and a stepped shaft 5. This model of the stepped shaft 5 is composed of three shafts with different diameters; the outer end diameter of the tapered shaft 1 is 30mm, the inner end diameter is 43.7mm, and the length is 157.5mm; the diameter of the large disc 2 is 115mm, and the length is 24.7mm; the diameter of the connecting shaft 3 is 33mm, and the length is 72.1mm; the diameter of the small disc is 87.6mm, and the length is 23mm; the stepped shaft 5 has three shafts with different diameters, the outer end shaft diameter is 33.2mm, the length is 57.1mm, the middle shaft diameter is 40.2mm, the length is 30.4mm, and the inner end shaft diameter is 50mm, and the length is 3.2mm. The wedge-cross rolling production method of the gearbox intermediate gear shaft blank adopts a bar with a diameter of 120 mm and is rolled into shape at one time through a wedge-cross rolling die. The disadvantage of the wedge-cross rolling production method of the gearbox intermediate gear shaft blank using a bar with a diameter of 120 mm is that: during the rolling process, the tapered shaft 1, the connecting shaft 3, the small disc 4 and the step shaft 5 are all deformed, and the internal part is dense, which meets the product quality requirements; since the bar diameter is the same as the outer diameter of the large disc 2, the large disc 2 is not deformed during the rolling process, and its internal structure is loose, which does not meet the product quality requirements. Summary of the invention

[0003] The purpose of the present invention is to provide a rolling and forging production method of a gearbox intermediate gear shaft blank which adopts a small diameter bar to produce a large diameter disc, so that the large disc of the gearbox intermediate gear shaft blank can undergo stress deformation, prevent internal looseness, and ensure product quality.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is: a rolling and forging combined production method of the gearbox intermediate gear shaft blank, characterized in that it is manufactured by the following steps:

[0005] 1. Select the bar: Cut the bar with a diameter of 80 mm;

[0006] (ii) Medium frequency heating: Use a medium frequency heating furnace to heat the cut bar material to a temperature of 1000-1100℃;

[0007] (III) The heated bar stock is rolled into a gearbox intermediate gear shaft rolling blank by a wedge cross rolling mill. At this time, the temperature of the gearbox intermediate gear shaft rolling blank is 950-1000℃: wedge cross rolling dies are symmetrically installed on the upper and lower rollers of the wedge cross rolling mill; the wedge cross rolling die is provided with two mutually symmetrical tapered shaft rolling cavities, two mutually symmetrical rolling disc rolling cavities, two mutually symmetrical connecting shaft rolling cavities, two mutually symmetrical small disc rolling cavities, two mutually symmetrical step shaft rolling cavities and a cutter, and the cutter is fixedly arranged at the end of the wedge cross rolling die and located at the center of the two step shaft rolling cavities; the bar stock is rolled into two gearbox intermediate gear shaft rolling blanks at one time; the gearbox intermediate gear shaft rolling blank has a total length of 413.3mm, and it is composed of a tapered shaft, a rolling disc, a connecting shaft, a small disc and a step shaft, and the outer end diameter of the tapered shaft is 29mm, and the inner end diameter is 42 .7mm, length 157.5mm; the diameter of the rolled disc is 70mm, and the length is 70mm; the diameter of the connecting shaft is 33mm, and the length is 72.1mm; the diameter of the small disc is 87.6mm, and the length is 23mm; the step shaft has three shafts of different diameters, the outer end shaft diameter is 33.2mm, the length is 57.1mm, the middle shaft diameter is 40.2mm, the length is 30.4mm, the inner end shaft diameter is 50mm, and the length is 3.2mm; the tapered shaft rolling cavity is adapted to the tapered shaft of the gearbox intermediate gear shaft rolling blank, the rolling disc rolling cavity is adapted to the rolling disc of the gearbox intermediate gear shaft rolling blank, the connecting shaft rolling cavity is adapted to the connecting shaft of the gearbox intermediate gear shaft rolling blank, the small disc rolling cavity is adapted to the small disc of the gearbox intermediate gear shaft rolling blank, and the step shaft rolling cavity is adapted to the step shaft of the gearbox intermediate gear shaft rolling blank;

[0008] (IV) Forging the rolled blank of the gearbox intermediate gear shaft into the gearbox intermediate gear shaft blank by a press: the press is equipped with a forging die, which is composed of an upper die and a lower die, and the lower die is composed of a symmetrically arranged left die and a right die; the upper die is provided with a tapered shaft forming cavity, a large disc upper forming cavity and a groove, the central axes of the tapered shaft forming cavity, the large disc upper forming cavity and the groove coincide, and the groove is located at the bottom of the upper die; the upper end of the left die is provided with a left boss, the inner side wall of the left boss is provided with a left forming cavity of the lower part of the large disc, the inner side wall of the left die is provided with a left cavity of the connecting shaft, a left cavity of the small disc and a left cavity of the step shaft, and the outer side wall of the left die is provided with a left die fixing hole connected and fixed to the press; the upper end of the right die is provided with a right boss, the inner side wall of the right boss is provided with a right forming cavity of the lower part of the large disc, and the inner side wall of the right die is provided with a right The outer wall of the right mold is provided with a right mold fixing hole connected and fixed to the press; the tapered shaft forming cavity is adapted to the tapered shaft; the left boss and the right boss are adapted to the groove after closing, so that the left boss and the right boss can be inserted into the groove cavity after closing; the upper forming cavity of the large disk is adapted to the upper part of the large disk, and the left forming cavity of the lower part of the large disk and the right forming cavity of the lower part of the large disk are adapted to the The lower part of the large disc is adapted, and when the upper die and the lower die are in the process of closing the mold, the upper forming cavity of the large disc and the left forming cavity and the right forming cavity of the lower part of the large disc press the rolled disc in the cavity into a large disc; the left cavity of the connecting shaft and the right cavity of the connecting shaft are closed and adapted to the connecting shaft; the left cavity of the small disc and the right cavity of the small disc are closed and adapted to the small disc; the left cavity of the step shaft and the right cavity of the step shaft are closed and adapted to the step shaft;

[0009] The upper die is raised by a press machine, and after the left die and the right die are separated, the rolled blank of the gearbox intermediate gear shaft obtained in step (iii) is placed between the left die and the right die. After the left die and the right die are closed, the rolled disc is located in the left molding cavity of the lower part of the large disc and the right molding cavity of the lower part of the large disc, the connecting shaft is located in the left molding cavity of the connecting shaft and the right molding cavity of the connecting shaft, the small disc is located in the left molding cavity of the small disc and the right molding cavity of the small disc, the step shaft is located in the left molding cavity of the step shaft and the right molding cavity of the step shaft, and then the upper die is pressed down, the tapered shaft is inserted into the tapered shaft molding cavity, and the upper molding cavity of the large disc and the left molding cavity of the lower part of the large disc and the right molding cavity of the lower part of the large disc press the rolled disc in the cavity into a large disc; thereby, the gearbox intermediate gear shaft blank is obtained.

[0010] The forging die used for the rolling and forging production of the intermediate gear shaft blank of the above-mentioned gearbox comprises an upper die and a lower die, and is characterized in that: the lower die is composed of a symmetrically arranged left die and a right die; the upper die is provided with a tapered shaft forming cavity, an upper forming cavity of a large disc and a groove, the central axes of the tapered shaft forming cavity, the upper forming cavity of the large disc and the groove coincide, and the groove is located at the bottom of the upper die; the upper end of the left die is provided with a left boss, the inner side wall of the left boss is provided with a left forming cavity of the lower part of the large disc, the inner side wall of the left die is provided with a left cavity of a connecting shaft, a left cavity of a small disc and a left cavity of a step shaft, and the outer side wall of the left die is provided with a left die fixing hole connected and fixed to a press; the upper end of the right die is provided with a right boss, the inner side wall of the right boss is provided with a right forming cavity of the lower part of the large disc, the inner side wall of the right die is provided with a right cavity of a connecting shaft, a right cavity of a small disc and a right cavity of a step shaft, and the outer side wall of the right die is provided with a right die fixing hole connected and fixed to a press; The tapered shaft forming cavity is matched with the tapered shaft of the gearbox intermediate gear shaft blank; the left boss and the right boss are matched with the groove after closing, so that the left boss and the right boss can be inserted into the groove cavity after closing; the upper forming cavity of the large disc is matched with the upper part of the large disc of the gearbox intermediate gear shaft blank, and the left forming cavity of the lower part of the large disc and the right forming cavity of the lower part of the large disc are matched with the lower part of the large disc of the gearbox intermediate gear shaft blank after closing. In the process, the upper forming cavity of the large disc and the left and right forming cavities of the lower part of the large disc press the rolled disc in the cavity into a large disc; the left and right cavities of the connecting shaft are matched with the connecting shaft of the gearbox intermediate gear shaft blank after being closed; the left and right cavities of the small disc are matched with the small disc of the gearbox intermediate gear shaft blank after being closed; the left and right cavities of the step shaft are matched with the step shaft of the gearbox intermediate gear shaft blank after being closed.

[0011] The beneficial effect of the present invention is that compared with the current wedge cross-rolling production method of using large-diameter bars to roll gearbox intermediate gear shaft blanks, the present invention uses small-diameter bars to produce gearbox intermediate gear shaft blanks with a large-diameter disk, so that the large disk of the gearbox intermediate gear shaft blank can undergo stress deformation, preventing internal looseness, ensuring product quality, reducing the cost of production raw materials, and improving economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the gearbox intermediate gear shaft blank of the present invention;

[0013] Figure 2 It is a schematic diagram of the unfolded structure of the wedge cross-rolling die of the present invention;

[0014] Figure 3 For the present invention Figure 2The structural section in the A-A direction and the corresponding enlarged schematic diagram of the rolling blank of the gearbox intermediate gear shaft;

[0015] Figure 4 It is an enlarged schematic diagram of the structure of the rolling blank of the gearbox intermediate gear shaft of the present invention;

[0016] Figure 5 It is a schematic diagram of an enlarged cross-section of the structure of the forging die of the gearbox intermediate gear shaft blank of the present invention.

[0017] In the figure: 1, tapered shaft; 2, large disc; 3, connecting shaft; 4, small disc; 5, stepped shaft; 6, wedge cross-rolling die; 61, tapered shaft rolling cavity; 62, connecting shaft rolling cavity; 63, rolling disc rolling cavity; 64, small disc rolling cavity; 65, stepped shaft rolling cavity; 66, cutter; 7, gearbox intermediate gear shaft rolling blank; 8, rolling disc; 9, upper die; 91, tapered shaft forming cavity; 92, large disc upper forming cavity; 93, Groove; 10, left mold; 101, left mold fixing hole; 102, left cavity of small disc; 103, left cavity of connecting shaft; 104, left molding cavity of lower part of large disc; 105, left boss; 106, left cavity of stepped shaft; 11, right mold; 111, right mold fixing hole; 112, right cavity of small disc; 113, right cavity of connecting shaft; 114, right molding cavity of lower part of large disc; 115, right boss; 116, right cavity of stepped shaft. DETAILED DESCRIPTION

[0018] Reference Figure 2 , Figure 3 , Figure 4 , Figure 5 Make the mold required for the present invention, for producing Figure 1 The gearbox intermediate gear shaft blank is shown.

[0019] like Figure 1 As shown, the total length of the gearbox intermediate gear shaft blank is 368mm, which is composed of a tapered shaft 1, a large disc 2, a connecting shaft 3, a small disc 4 and a stepped shaft 5. This model of the stepped shaft 5 is composed of three shafts with different diameters; the outer end diameter of the tapered shaft 1 is 30mm, the inner end diameter is 43.7mm, and the length is 157.5mm; the diameter of the large disc 2 is 120mm, and the length is 24.7mm; the diameter of the connecting shaft 3 is 33mm, and the length is 72.1mm; the diameter of the small disc is 87.6mm, and the length is 23mm; the stepped shaft 5 has three shafts with different diameters, the outer end shaft diameter is 33.2mm, the length is 57.1mm, the middle shaft diameter is 40.2mm, the length is 30.4mm, and the inner end shaft diameter is 50mm, and the length is 3.2mm.

[0020] The rolling and forging combined production method of the gearbox intermediate gear shaft blank is characterized in that it is manufactured by the following steps:

[0021] 1. Select the bar: Cut the bar with a diameter of 80 mm;

[0022] (ii) Medium frequency heating: Use a medium frequency heating furnace to heat the cut bar material to a temperature of 1000-1100℃;

[0023] (III) The heated bar material is rolled into a gearbox intermediate gear shaft rolling blank 7 by a wedge cross rolling mill. At this time, the gearbox intermediate gear shaft rolling blank 7 has a temperature of 950-1000°C. A wedge cross rolling die 6 is symmetrically installed on the upper and lower rollers of the wedge cross rolling mill. The wedge cross rolling die 6 is provided with two mutually symmetrical tapered shaft rolling cavities 61, two mutually symmetrical rolling disc rolling cavities 63, two mutually symmetrical connecting shaft rolling cavities 62, and two mutually symmetrical small disc rolling cavities 64. , two symmetrical step shaft rolling cavities 65 and a cutter 66, the cutter 66 is fixedly arranged at the end of the wedge cross rolling die 6 and is located at the center of the two step shaft rolling cavities 65; the bar material is rolled into two gearbox intermediate gear shaft rolling blanks 7 at one time; the gearbox intermediate gear shaft rolling blank 7 has a total length of 413.3mm, and it consists of a tapered shaft 1, a rolling disc 8, a connecting shaft 3, a small disc 4 and a step shaft 5, the outer end diameter of the tapered shaft 1 is 29mm, and the inner end diameter is 29mm. 42.7mm, length 157.5mm; the rolling disc 8 has a diameter of 70mm and a length of 70mm; the connecting shaft 3 has a diameter of 33mm and a length of 72.1mm; the small disc 4 has a diameter of 87.6mm and a length of 23mm; the stepped shaft 5 has three shafts of different diameters, the outer end has a diameter of 33.2mm and a length of 57.1mm, the middle end has a diameter of 40.2mm and a length of 30.4mm, the inner end has a diameter of 50mm and a length of 3.2 mm; the tapered shaft rolling die cavity 61 is adapted to the tapered shaft 1 of the gearbox intermediate gear shaft rolling blank 7, the rolling disc rolling die cavity 63 is adapted to the rolling disc 8 of the gearbox intermediate gear shaft rolling blank 7, the connecting shaft rolling die cavity 62 is adapted to the connecting shaft 3 of the gearbox intermediate gear shaft rolling blank 7, the small disc rolling die cavity 64 is adapted to the small disc 4 of the gearbox intermediate gear shaft rolling blank 7, and the step shaft rolling die cavity 65 is adapted to the step shaft 5 of the gearbox intermediate gear shaft rolling blank 7;

[0024] (IV) The rolled blank 7 of the gearbox intermediate gear shaft is forged into a gearbox intermediate gear shaft blank by a press: the press is equipped with a forging die, the forging die is composed of an upper die 9 and a lower die, the lower die is composed of a symmetrically arranged left die 10 and a right die 11; the upper die 9 is provided with a tapered shaft forming cavity 91, a large disc upper forming cavity 92 and a groove 93, the central axes of the tapered shaft forming cavity 91, the large disc upper forming cavity 92 and the groove 93 coincide, and the groove 93 is located at the bottom of the upper die 9; the upper end of the left die 10 is provided with a tapered shaft forming cavity 91, a large disc upper forming cavity 92 and a groove 93; the central axes of the tapered shaft forming cavity 91, the large disc upper forming cavity 92 and the groove 93 coincide, and the groove 93 is located at the bottom of the upper die 9; the upper end of the left die 10 is provided with a tapered shaft forming cavity 91, a large disc upper forming cavity 92 and the groove 93 are ... A left side boss 105 is provided, and a left side molding cavity 104 of the lower part of the large disc is provided on the inner side wall of the left side boss 105; a left side molding cavity 103 of the connecting shaft, a left side molding cavity 102 of the small disc and a left side molding cavity 106 of the step shaft are provided on the inner side wall of the left die 10; a left die fixing hole 101 connected and fixed to the press is provided on the outer side wall of the left die 10; a right side boss 115 is provided at the upper end of the right die 11, and a right side molding cavity 114 of the lower part of the large disc is provided on the inner side wall of the right side boss 115; a right side molding cavity 113 of the connecting shaft, a left side molding cavity 102 of the small disc and a left side molding cavity 106 of the step shaft are provided on the inner side wall of the right die 11 The right side cavity 112 of the small disc and the right side cavity 116 of the stepped shaft, the outer side wall of the right die 11 is provided with a right die fixing hole 111 connected and fixed to the press; the tapered shaft forming cavity 91 is adapted to the tapered shaft 1; the left side boss 105 and the right side boss 115 are adapted to the groove 93 after closing, so that the left side boss 105 and the right side boss 115 can be inserted into the groove 93 cavity after closing; the upper forming cavity 92 of the large disc is adapted to the upper part of the large disc 2, and the left side forming cavity 104 of the lower part of the large disc and the right side forming cavity 114 of the lower part of the large disc are closed. After that, it is matched with the lower part of the large disc 2. When the upper die 9 and the lower die are in the process of closing the mold, the upper forming cavity 92 of the large disc and the left forming cavity 104 and the right forming cavity 114 of the lower part of the large disc press the rolled disc 8 in the cavity into the large disc 2; the left forming cavity 103 of the connecting shaft and the right forming cavity 113 of the connecting shaft are matched with the connecting shaft 3 after closing; the left forming cavity 102 of the small disc and the right forming cavity 112 of the small disc are matched with the small disc 4 after closing; the left forming cavity 106 of the step shaft and the right forming cavity 116 of the step shaft are matched with the step shaft 5 after closing;

[0025] The upper die 9 is raised by a press machine, and after the left die 10 and the right die 11 are separated, the gearbox intermediate gear shaft rolled blank 7 obtained in step (iii) is placed between the left die 10 and the right die 11. After the left die 10 and the right die 11 are closed, the rolled disc 8 is located in the left molding cavity 104 and the right molding cavity 114 of the lower part of the large disc, the connecting shaft 3 is located in the left molding cavity 103 and the right molding cavity 113 of the connecting shaft, and the small disc 4 is located in the left molding cavity 103 and the right molding cavity 113 of the connecting shaft. The small disc is located in the left cavity 102 and the right cavity 112 of the small disc, the step shaft 5 is located in the left cavity 106 and the right cavity 116 of the step shaft, and then the upper mold 9 is pressed down, the tapered shaft 1 is inserted into the tapered shaft forming cavity 9, the upper forming cavity 92 of the large disc and the left forming cavity 104 and the right forming cavity 114 of the lower part of the large disc press the rolled disc 8 in the cavity into a large disc 2; thereby, the gearbox intermediate gear shaft blank is obtained.

[0026] The forging die used for rolling and forging production of the intermediate gear shaft blank of the above-mentioned gearbox comprises an upper die 9 and a lower die, and is characterized in that: the lower die is composed of a symmetrically arranged left die 10 and a right die 11; the upper die 9 is provided with a tapered shaft forming cavity 91, a large disc upper forming cavity 92 and a groove 93, the central axes of the tapered shaft forming cavity 91, the large disc upper forming cavity 92 and the groove 93 coincide, and the groove 93 is located at the bottom of the upper die 9; the upper end of the left die 10 is provided with a left boss 105, and the inner side wall of the left boss 105 The left mold 10 is provided with a left molding cavity 104 at the lower part of the large disc, the inner wall of the left mold 10 is provided with a left molding cavity 103 of the connecting shaft, a left molding cavity 102 of the small disc and a left molding cavity 106 of the step shaft, and the outer wall of the left mold 10 is provided with a left mold fixing hole 101 connected and fixed to the press; the upper end of the right mold 11 is provided with a right boss 115, the inner wall of the right boss 115 is provided with a right molding cavity 114 at the lower part of the large disc, the inner wall of the right mold 11 is provided with a right molding cavity 113 of the connecting shaft, a right molding cavity 112 of the small disc and a step shaft The right mold cavity 116, the outer side wall of the right mold 11 is provided with a right mold fixing hole 111 connected and fixed to the press; the tapered shaft forming cavity 91 is adapted to the tapered shaft 1; the left boss 105 and the right boss 115 are adapted to the groove 93 after closing, so that the left boss 105 and the right boss 115 can be inserted into the groove 93 cavity after closing; the upper forming cavity 92 of the large disc is adapted to the upper part of the large disc 2, and the left forming cavity 104 of the lower part of the large disc and the right forming cavity 114 of the lower part of the large disc are adapted to the large disc 2 after closing. The lower part is adapted, when the upper mold 9 and the lower mold are in the process of closing the mold, the upper molding cavity 92 of the large disk and the left molding cavity 104 and the right molding cavity 114 of the lower part of the large disk press the rolled disk 8 in the cavity into a large disk 2; the left molding cavity 103 of the connecting shaft and the right molding cavity 113 of the connecting shaft are adapted to the connecting shaft 3 after being closed; the left molding cavity 102 of the small disk and the right molding cavity 112 of the small disk are adapted to the small disk 4 after being closed; the left molding cavity 106 of the step shaft and the right molding cavity 116 of the step shaft are adapted to the step shaft 5 after being closed.

Claims

1. A rolling and forging production method for a gearbox intermediate gear shaft blank, characterized in that: It is made by the following steps:

1. Select the bar: Cut the bar with a diameter of 80 mm; (ii) Medium frequency heating: Use a medium frequency heating furnace to heat the cut bar material to a temperature of 1000-1100℃; (III) The heated bar material is rolled into a gearbox intermediate gear shaft rolling blank (7) by a wedge cross rolling mill, wherein the gearbox intermediate gear shaft rolling blank (7) has a temperature of 950-1000°C: a wedge cross rolling die (6) is symmetrically installed on the upper and lower rolls of the wedge cross rolling mill; the wedge cross rolling die (6) is provided with two mutually symmetrical tapered shaft rolling cavities (61), two mutually symmetrical rolling disc rolling cavities (63), two mutually symmetrical connecting shaft rolling cavities (62), two mutually symmetrical small disc rolling cavities (64), and two mutually symmetrical rolling cavities (65). The invention relates to a step shaft rolling die cavity (65) and a cutter (66) which are symmetrical to each other. The cutter (66) is fixedly arranged at the end of the wedge cross rolling die (6) and is located at the center of the two step shaft rolling die cavities (65). The bar material is rolled into two gearbox intermediate gear shaft rolling blanks (7) at one time. The gearbox intermediate gear shaft rolling blank (7) has a total length of 413.3 mm and is composed of a tapered shaft (1), a rolling disc (8), a connecting shaft (3), a small disc (4) and a step shaft (5). The outer end diameter of the tapered shaft (1) is 29 mm and the inner end is 29 mm. The diameter of the rolling disc (8) is 42.7 mm and the length is 157.5 mm; the diameter of the rolling disc (8) is 70 mm and the length is 70 mm; the diameter of the connecting shaft (3) is 33 mm and the length is 72.1 mm; the diameter of the small disc (4) is 87.6 mm and the length is 23 mm; the stepped shaft (5) has three shafts of different diameters, the outer end shaft diameter is 33.2 mm and the length is 57.1 mm, the middle shaft diameter is 40.2 mm and the length is 30.4 mm, the inner end shaft diameter is 50 mm and the length is 3.2 mm; the tapered shaft rolling The die making cavity (61) is matched with the tapered shaft (1) of the gearbox intermediate gear shaft rolling blank (7), the rolling disc rolling die cavity (63) is matched with the rolling disc (8) of the gearbox intermediate gear shaft rolling blank (7), the connecting shaft rolling die cavity (62) is matched with the connecting shaft (3) of the gearbox intermediate gear shaft rolling blank (7), the small disc rolling die cavity (64) is matched with the small disc (4) of the gearbox intermediate gear shaft rolling blank (7), and the step shaft rolling die cavity (65) is matched with the step shaft (5) of the gearbox intermediate gear shaft rolling blank (7); (IV) The rolled blank (7) of the gearbox intermediate gear shaft is forged into a gearbox intermediate gear shaft blank by a press machine: the press machine is provided with a forging die, the forging die is composed of an upper die (9) and a lower die, the lower die is composed of a left die (10) and a right die (11) which are symmetrically arranged; the upper die (9) is provided with a tapered shaft forming cavity (91), a large disc upper forming cavity (92) and a groove (93), the central axes of the tapered shaft forming cavity (91), the large disc upper forming cavity (92) and the groove (93) are coincident, and the groove (93) is located at the bottom of the upper die (9); the upper end of the left die (10) is provided with The left side boss (105) has a left side molding cavity (104) at the bottom of the large disc on its inner side wall, a left side molding cavity (103) of a connecting shaft, a left side molding cavity (102) of a small disc and a left side molding cavity (106) of a stepped shaft on its inner side wall, and a left mold fixing hole (101) connected and fixed to a press machine is provided on the outer side wall of the left mold (10); the upper end of the right mold (11) has a right side boss (115), the inner side wall of the right side boss (115) has a right side molding cavity (114) at the bottom of the large disc on its inner side wall, and a right side molding cavity (113) of a connecting shaft, a left side molding cavity (102) of a small disc and a left side molding cavity (106) of a stepped shaft on its inner side wall. The right mold cavity (112) and the right mold cavity (116) of the stepped shaft are provided on the outer wall of the right mold (11); the tapered shaft molding cavity (91) is adapted to the tapered shaft (1); the left boss (105) and the right boss (115) are adapted to the groove (93) after closing, so that the left boss (105) and the right boss (115) can be inserted into the groove (93) cavity after closing; the upper molding cavity (92) of the large disc is adapted to the upper part of the large disc (2); the left molding cavity (104) and the right molding cavity (114) of the lower part of the large disc are adapted to the tapered shaft (1) after closing. The upper mold (9) and the lower mold (104) are adapted to fit the lower part of the large disk (2). When the upper mold (9) and the lower mold are in the process of closing the mold, the upper molding cavity (92) of the large disk and the left molding cavity (104) and the right molding cavity (114) of the lower part of the large disk press the rolled disk (8) in the cavity into the large disk (2); the left molding cavity (103) and the right molding cavity (113) of the connecting shaft are closed to fit the connecting shaft (3); the left molding cavity (102) and the right molding cavity (112) of the small disk are closed to fit the small disk (4); the left molding cavity (106) and the right molding cavity (116) of the step shaft are closed to fit the step shaft (5); The upper die (9) is raised by a press machine, and the left die (10) and the right die (11) are separated. The gearbox intermediate gear shaft rolled blank (7) obtained in step (iii) is placed between the left die (10) and the right die (11). After the left die (10) and the right die (11) are closed, the rolled disc (8) is located in the left molding cavity (104) and the right molding cavity (114) of the lower part of the large disc, the connecting shaft (3) is located in the left molding cavity (103) and the right molding cavity (113) of the connecting shaft, and the small disc ( 4) is located in the left cavity (102) of the small disc and the right cavity (112) of the small disc, the step shaft (5) is located in the left cavity (106) of the step shaft and the right cavity (116) of the step shaft, and then the upper die (9) is pressed down, the tapered shaft (1) is inserted into the tapered shaft forming cavity (9), and the upper forming cavity (92) of the large disc and the left forming cavity (104) and the right forming cavity (114) of the lower part of the large disc press the rolled disc (8) in the cavity into a large disc (2); thereby obtaining a gearbox intermediate gear shaft blank.

2. A forging die for rolling and forging production of a gearbox intermediate gear shaft blank, comprising an upper die (9) and a lower die, characterized in that: The lower mold is composed of a symmetrically arranged left mold (10) and a right mold (11); the upper mold (9) is provided with a tapered shaft molding cavity (91), a large disc upper molding cavity (92) and a groove (93); the central axes of the tapered shaft molding cavity (91), the large disc upper molding cavity (92) and the groove (93) coincide with each other, and the groove (93) is located at the bottom of the upper mold (9); the upper end of the left mold (10) is provided with a left boss (105), and the inner side wall of the left boss (105) is provided with a large disc lower left molding cavity (104). The inner wall of the left mold (10) is provided with a left cavity (103) of the connecting shaft, a left cavity (102) of the small disc and a left cavity (106) of the stepped shaft, and the outer wall of the left mold (10) is provided with a left mold fixing hole (101) connected and fixed to the press machine; the upper end of the right mold (11) is provided with a right boss (115), the inner wall of the right boss (115) is provided with a right molding cavity (114) of the lower part of the large disc, and the inner wall of the right mold (11) is provided with a right cavity (113) of the connecting shaft, a right cavity (112) of the small disc and a left cavity (106) of the stepped shaft. The right side cavity (116) of the stepped shaft is provided with a right die fixing hole (111) connected and fixed to the press on the outer side wall of the right die (11); the tapered shaft forming cavity (91) is adapted to the tapered shaft (1) of the gearbox intermediate gear shaft blank; the left side boss (105) and the right side boss (115) are adapted to the groove (93) after closing; the upper part forming cavity (92) of the large disc is adapted to the upper part of the large disc (2) of the gearbox intermediate gear shaft blank, and the left side forming cavity (104) and the right side forming cavity (111) of the lower part of the large disc are adapted to the upper part of the large disc (2) of the gearbox intermediate gear shaft blank. 4) after closing, they are matched with the lower part of the large disc (2) of the gearbox intermediate gear shaft blank; after closing, the left cavity (103) of the connecting shaft and the right cavity (113) of the connecting shaft are matched with the connecting shaft (3) of the gearbox intermediate gear shaft blank; after closing, the left cavity (102) of the small disc and the right cavity (112) of the small disc are matched with the small disc (4) of the gearbox intermediate gear shaft blank; after closing, the left cavity (106) of the step shaft and the right cavity (116) of the step shaft are matched with the step shaft (5) of the gearbox intermediate gear shaft blank.

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