Spinning method and spinning tool for inner tooth-shaped transmission part

Abstract

The application relates to a spinning method of an inner tooth transmission part, which comprises the following steps: in a finite element software, a model of a plate-shaped blank and a spinning tool which are same as actual machining transmission parts are established, the plate-shaped blank is simulated and machined by deep drawing spinning of the spinning tool, and a simulated formed cylindrical blank is obtained; then the cylindrical blank is simulated and machined by single-pass spinning of the model of the spinning tool, and the simulated reduction amount required by the tooth height of the inner tooth of the transmission part is determined; the deep drawing spinning and the single-pass spinning are adopted, the transmission part is actually machined by using the reduction amount, and the transmission part with the inner tooth is obtained. The inner tooth transmission part is produced by the spinning method, compared with traditional extrusion, broaching and composite forming methods, the fiber flow direction of the original blank is reserved, the surface quality of the part is high, and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of metal plastic forming technology, and more specifically to a method for processing internal gear transmission parts. Background Technology

[0002] my country's auto parts industry has grown rapidly alongside the expansion of the vehicle market and global procurement, providing a solid foundation for the continued steady development of the automotive manufacturing industry. With the rapid development of the automotive industry and the rapid growth of market demand, there is an urgent need for lightweight and low-energy-consumption auto parts. Gear-shaped parts account for more than 30% of the auto parts market, such as various gears, splines, lead screws, and gear rings. These parts have a large application volume and wide coverage. For transmission parts with internal gears, traditional processing technologies mainly include subtractive manufacturing and plastic forming.

[0003] (1) Subtractive processing, including gear hobbing, gear shaving, gear shaping, and gear grinding, removes excess material by friction or cutting the blank with a cutting tool to form a part of the required size. The disadvantages of this method include: a large amount of metal chips are generated during the processing, resulting in low material utilization; the original flow lines of the material are destroyed during the forming process; the processing cost of the cutting tool is high; the processing efficiency is low; and the dimensional accuracy is poor.

[0004] (2) Extrusion belongs to the field of plastic forming. It involves extruding the blank with a punch with external teeth, causing the excess blank to flow out of the mold cavity, thereby forming a transmission part with internal teeth. The disadvantages of this method are: during the extrusion process, the friction between the blank and the mold is large, the mold is more easily damaged, resulting in a reduction in the dimensional accuracy of the part; extrusion forming results in a large residual stress in the part. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a spinning method for obtaining precision-sized internal gear transmission parts by spinning a plate blank.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a spinning method for internal gear transmission parts, comprising the following steps:

[0007] Step 1: In the finite element software, establish a model of the same plate blank and spinning tooling as the actual processed transmission parts. Use the spinning tooling to perform deep drawing and spinning simulation processing on the plate blank to obtain the simulated cylindrical blank.

[0008] Step 2: Use the spinning fixture model to perform a single-pass spinning simulation on the cylindrical blank to determine the simulated reduction required for the internal tooth height of the transmission parts.

[0009] The spinning fixture model includes a core mold, a deep drawing spinning wheel for deep drawing spinning simulation, and a spinning wheel model for single-pass spinning simulation. The core mold surface is provided with a tooth mold that matches the tooth profile of the transmission parts.

[0010] At this time, the simulated reduction amount is the amount of reduction in a single-pass spinning process, in which the spinning wheel presses the blank of the transmission part tightly into the tooth mold on the core mold, so that the inner surface of the transmission part forms the reduction amount of the target tooth height of the transmission part.

[0011] Step 3: Using deep drawing spinning and single-pass spinning, and using the reduction amount to actually machine the transmission parts, a transmission part with internal tooth profile is obtained.

[0012] Furthermore, in step two, a model using multiple spinning wheels was established and simulated, and the multiple spinning wheels included at least one circular arc spinning wheel and at least two double conical spinning wheels, with the multiple spinning wheels evenly distributed around the mandrel.

[0013] At this point, the spinning wheel is used to simulate the staggered spinning process of the cylindrical blank, thereby determining the total simulated reduction required for the internal tooth height of the transmission part;

[0014] Furthermore, the simulated total reduction is distributed to multiple spinning wheels in different proportions to simulate offset spinning with different radial offsets. The simulated reduction of each spinning wheel is selected when the difference in spinning pressure between multiple spinning wheels is less than 3-5%. The simulated reduction of each spinning wheel is the amount of reduction in which each spinning wheel presses the blank of the transmission part tightly into the tooth mold on the mandrel during offset spinning, so that the inner surface of the blank of the transmission part forms the target tooth height of the transmission part. The sum of the reductions of each spinning wheel is the total reduction, and the total reduction is equal to the simulated total reduction.

[0015] At the same time, the axial spacing between the multiple spinning wheels is determined to prevent interference between them.

[0016] In step three, multiple spinning wheels are used to perform staggered spinning, and the actual machining of the transmission parts is done using the pressing amount of each spinning wheel, resulting in transmission parts with internal teeth.

[0017] Furthermore, in step two, during the simulated single-pass deep drawing and spinning process, the gap between the deep drawing and spinning wheel and the mandrel is 6-20mm, the rotation speed of the mandrel is 300-2000rpm, the axial feed speed of the deep drawing and spinning wheel is 0.5-1.5mm / r, and the simulated single-pass deep drawing and spinning process is the same as the actual single-pass deep drawing and spinning process.

[0018] Furthermore, the plate-shaped billet is a round plate-shaped billet with a diameter of 150-400mm and a thickness of 6-15mm.

[0019] Furthermore, in step two, the single-pass spinning simulation is the same as the actual single-pass spinning, and the target tooth height of the transmission part is h=2-4mm, and the pressing amount of the spinning wheel is 2.8-6mm.

[0020] Furthermore, the staggered spinning simulation process is the same as the actual staggered spinning process. The target tooth height of the transmission part is h=2-4mm. The model of the spinning wheel includes a circular arc wheel and two double conical surface wheels. The total reduction of the three spinning wheels is 2.8-6mm.

[0021] The reduction amounts t1, t2, and t3 of the three spinning rollers are 45-55%, 25-35%, and 15-25% of the total reduction amount, respectively.

[0022] At this time, the radial distance between the first spinning wheel and the second spinning wheel is equal to t2, and the radial distance between the second spinning wheel and the third spinning wheel is equal to t3;

[0023] Meanwhile, to prevent interference between the spinning wheels, the axial distance S between the first and second spinning wheels is determined. 12 The axial distance S between the second and third spinning rollers is 15-20mm. 23 It is 10-15mm.

[0024] Furthermore, the plate-shaped billet mentioned in step three is made of carbon or alloy structural steel and is annealed before deep drawing and spinning to reduce hardness, improve plasticity and eliminate internal stress in the billet.

[0025] Further, the specific annealing steps are as follows: the plate billet is placed in the annealing furnace, the furnace temperature is heated to 650-850℃, and after holding for 10-15 hours, it is cooled to 400-500℃ with the furnace. Then the plate billet is taken out and air-cooled to room temperature to complete the annealing treatment of the plate billet.

[0026] The present invention also provides a spinning fixture for the spinning method of the internal gear transmission parts as described above, including a tail top, a core mold mounted on a base, the tail top and the core mold cooperating to press the plate-shaped blank, the tail top, the core mold and the base being coaxially arranged, and all being driven to rotate by the spindle of the spinning machine;

[0027] It also includes a drawing and spinning wheel mounted on a spinning wheel frame, and three spinning wheels. The spinning wheel frame is used to drive the three spinning wheels to move axially and radially.

[0028] Among them, the drawing spinning wheel is used in the drawing spinning process; the spinning wheel is used in the single-pass spinning or staggered spinning process. The spinning wheel includes a circular arc wheel and two double conical wheels. The drawing spinning wheel and the circular arc wheel have the same structure.

[0029] Furthermore, the diameter D of the deep drawing spinning wheel, the circular arc spinning wheel, and the double-cone spinning wheel is:

[0030] D = (1.2 - 2)d, where d is the diameter of the mandrel;

[0031] If the diameter D is too small, it will increase the tangential flow of metal and reduce the accuracy of the workpiece; if it is too large, it will increase the spinning force.

[0032] In the deep drawing and spinning process, in order to increase the contact area between the deep drawing and spinning wheel and the billet and improve the quality of the cylindrical billet, the radius R of the deep drawing and spinning wheel is 30-40mm.

[0033] During single-pass spinning or staggered spinning, when the cone angle radius r of the double-conical spinning wheel is large, the contact area between the double-conical spinning wheel and the blank increases, the blank of the transmission parts is fully compressed, and the surface quality of the formed part is high. However, it will increase the spinning force, which is prone to wrinkling and instability of the blank, which is not conducive to the forming of the spun part. When the value of r is small, the spinning force decreases and the forming process is more stable, but the surface quality of the blank is poor. The small contact area will also lead to stress concentration, resulting in cracks or tears.

[0034] Therefore, the value of the cone radius r is taken as:

[0035] r = (1-3)t, where t is the thickness of the plate blank;

[0036] Meanwhile, if the working angle α of the double-cone spinning wheel is too large, it will increase the height of the material in front of the spinning wheel, which will reduce the fluidity of the material and even cause instability or wrinkling. If it is too small, the contact area between the spinning wheel and the blank will increase, thereby increasing the spinning force and having an adverse effect on spinning. Therefore, the value of the working angle α is 15-30°.

[0037] The beneficial effects of this invention are: This invention produces internal gear transmission parts by spinning, which, compared with traditional extrusion, broaching, and composite forming methods, preserves the original fiber flow direction of the blank, resulting in high surface quality of the parts. Moreover, it is a forming method with little or no cutting, effectively improving the utilization rate of materials.

[0038] This invention can spin round blanks through the mold provided by this invention in two passes in a spinning machine to form transmission parts with internal teeth, which greatly improves production efficiency.

[0039] This invention uses a three-wheel staggered spinning method to fill the tooth profile step by step, which can improve the forming accuracy of transmission parts with internal teeth, and the internal tooth accuracy can reach level 6. Attached image description:

[0040] Figure 1 This is a schematic diagram of the spinning tooling model used in the deep drawing and spinning simulation process of this invention;

[0041] Figure 2 This is a schematic diagram of the spinning tooling model for the staggered spinning simulation processing of the present invention;

[0042] Figure 3 This is a schematic diagram of the radial offset machining of the second rotating wheel of the present invention;

[0043] Figure 4 This is a schematic diagram of the axial offset machining of the second rotating wheel of the present invention;

[0044] Figure 5 This is a schematic diagram of the arc-shaped rotating wheel structure in the second rotating wheel of the present invention;

[0045] Figure 6 This is a schematic diagram of the double-conical wheel structure in the second wheel of the present invention;

[0046] Figure 7 This is a schematic diagram of the structure in which the blank of the transmission part is tightly pressed into the toothed mold on the core mold during the staggered spinning process of the present invention;

[0047] Figure 8 This is a schematic diagram of the process flow for a specific example of the present invention;

[0048] Figure 9 This is a schematic diagram of an internal tooth forming part according to a specific embodiment of the present invention.

[0049] The numbers in the diagram are: 1. Core mold; 11. Tooth mold; 2. Tail top; 3. Plate blank; 41. Deep drawing spinning wheel; 42. Spinning wheel; 421. Circular arc spinning wheel; 422. Double conical spinning wheel; 7. Spinning wheel frame; 8. Base; 9. Cylindrical blank. Detailed Implementation

[0050] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0051] To achieve the above objectives, the present invention provides the following specific embodiments:

[0052] Example 1: As Figure 1 As shown, a spinning method for an internal gear transmission component includes the following steps:

[0053] Step 1: In the finite element software, create models of the same plate blank 3 and spinning fixture as the actual machined transmission parts. Use the spinning fixture to simulate deep drawing and spinning of the plate blank 3 to obtain the simulated cylindrical blank 9, as shown below. Figure 1 As shown;

[0054] Among them, plate-shaped billet 3 is a round plate-shaped billet with a diameter of 150-400mm and a thickness of 6-15mm.

[0055] Step 2: Use the spinning fixture model to perform a single-pass spinning simulation on the cylindrical blank 9 to determine the simulated reduction required for the internal tooth height of the transmission parts.

[0056] The model of the spinning tooling includes a core mold 1, a deep drawing spinning wheel 41 for deep drawing spinning simulation processing, and a spinning wheel 42 for single-pass spinning simulation processing. The surface of the core mold 1 is provided with a tooth mold 11 that matches the tooth profile of the transmission parts.

[0057] At this time, the simulated reduction amount is the amount of reduction in a single pass of spinning, where the spinning wheel 42 presses the blank of the transmission part tightly into the tooth mold 11 on the core mold 1, so that the inner surface of the transmission part forms the reduction amount of the target tooth height of the transmission part.

[0058] In the single-pass deep drawing and spinning simulation, the gap between the deep drawing and spinning wheel 41 and the mandrel 1 is 6-20mm, the rotation speed of the mandrel 1 is 300-2000rpm, the axial feed speed of the deep drawing and spinning wheel 41 is 0.5-1.5mm / r, and the single-pass deep drawing and spinning simulation is the same as the actual single-pass deep drawing and spinning.

[0059] The single-pass spinning simulation is the same as the actual single-pass spinning. The target tooth height of the transmission parts is h=2-4mm, and the pressing amount of the spinning wheel 42 is 2.8-6mm.

[0060] Step 3: Using deep drawing spinning and single-pass spinning, and using the reduction amount to actually machine the transmission parts, a transmission part with internal tooth profile is obtained.

[0061] Example 2: As Figure 2 , Figure 7 As shown, similar to Example 1, the difference is that in step two, a model with multiple spinning wheels 42 was established and simulated. These multiple spinning wheels 42 include at least one circular arc wheel 421 and at least two double-cone surface wheels 422. The multiple spinning wheels 42 are evenly distributed around the core mold 1, as shown... Figure 2 As shown;

[0062] At this time, the spinning wheel 42 is used to perform a staggered spinning simulation of the cylindrical blank, thereby determining the total simulated reduction required for the internal tooth height of the transmission part;

[0063] Furthermore, the simulated total reduction is distributed to multiple spinning rollers 42 at different proportions to perform offset spinning simulation processing with different radial offset amounts. The simulated reduction of each spinning roller 42 is selected when the spinning pressure difference among the multiple spinning rollers 42 is less than 3-5%. The simulated reduction of each spinning roller 42 is the amount of reduction in offset spinning processing, such as... Figure 7 As shown, each spinning wheel 42 presses the blank of the transmission part tightly into the tooth mold 11 on the core mold 1, so that the inner surface of the blank of the transmission part forms the reduction amount of the target tooth height of the transmission part. The sum of the reduction amounts of each spinning wheel 42 is the total reduction amount, and the total reduction amount is equal to the simulated total reduction amount.

[0064] At the same time, under the premise of preventing interference between multiple spinning wheels 42, the axial spacing of multiple spinning wheels 42 is determined;

[0065] In step three, multiple spinning wheels 42 are used to perform staggered spinning, and the pressing amount of each spinning wheel 42 is used to actually process the transmission parts to obtain transmission parts with internal teeth.

[0066] Example 3: As Figure 3 , Figure 4 As shown, the process is the same as in Example 2, except that the simulated staggered spinning process is the same as the actual staggered spinning process. The target tooth height of the transmission part is h = 2-4 mm. The model of the spinning wheel 42 includes a circular arc wheel 421 and two double conical wheels 422. The total reduction of the three spinning wheels 42 is 2.8-6 mm. Figure 3 As shown;

[0067] The reduction amounts t1, t2, and t3 of the three spinning rollers 42 are 45-55%, 25-35%, and 15-25% of the total reduction amount, respectively.

[0068] At this time, the radial distance between the first spinning wheel 42 and the second spinning wheel 42 is equal to t2, and the radial distance between the second spinning wheel 42 and the third spinning wheel 42 is equal to t3;

[0069] Meanwhile, to prevent interference between the spinning wheels 42, the axial distance S between the first spinning wheel 42 and the second spinning wheel 42 is determined. 12 The axial distance S between the second and third spinning rollers 42 is 15-20mm. 23 It is 10-15mm, such as Figure 4 As shown.

[0070] Example 4: Same as Example 1, except that the material of the plate blank 3 is carbon or alloy structural steel, and it is annealed before deep drawing and spinning to reduce hardness, improve plasticity and eliminate internal stress in the blank.

[0071] The specific annealing steps are as follows: Place the plate billet 3 into the annealing furnace, heat the annealing furnace to 650-850℃, hold it for 10-15 hours, cool it with the furnace to 400-500℃, and then take out the plate billet and air cool it to room temperature to complete the annealing treatment of the plate billet.

[0072] Example 5: Figure 1 , Figure 5 , Figure 6 As shown, the present invention also provides a spinning fixture for the spinning method of the above-mentioned internal gear transmission parts, such as... Figure 1 As shown, it includes a tail top 2 and a core mold 1 mounted on a base 8. The tail top 2 and the core mold 1 work together to press the plate-shaped blank 3. The tail top 2, the core mold 1 and the base 8 are coaxially arranged and are all driven to rotate by the spindle of the spinning machine.

[0073] It also includes a drawing and spinning wheel 41 and three spinning wheels 42 mounted on the spinning wheel frame 7. The spinning wheel frame 7 is used to drive the three spinning wheels to move axially and radially.

[0074] Among them, the deep drawing spinning wheel 41 is used in deep drawing spinning; the spinning wheel 42 is used in single-pass spinning or staggered spinning. The spinning wheel 42 includes an arc wheel 421 and two double-cone wheels 422. The deep drawing spinning wheel 41 and the arc wheel 421 have the same structure.

[0075] The diameter D of the deep drawing spinning wheel 41, the circular arc spinning wheel 421, and the double conical spinning wheel 422 is:

[0076] D = (1.2 - 2)d, where d is the diameter of core mold 1;

[0077] If the diameter D is too small, it will increase the tangential flow of metal and reduce the accuracy of the workpiece; if it is too large, it will increase the spinning force.

[0078] During deep drawing and spinning, in order to increase the contact area between the deep drawing and spinning roller 41 and the billet, and thus improve the quality of the cylindrical billet 9, such as... Figure 5 As shown, the radius R of the arc of the deep drawing spinning wheel 41 is 30-40 mm;

[0079] In single-pass spinning or staggered-pitch spinning, such as Figure 6As shown, when the cone radius r of the double-conical spinning wheel 422 is large, the contact area between the double-conical spinning wheel 422 and the blank increases, the blank of the transmission parts is fully compressed, and the surface quality of the formed part is high. However, it will increase the spinning pressure, which is prone to wrinkling and instability of the blank, which is not conducive to the forming of the spun part. When the value of r is small, the spinning pressure decreases and the forming process is more stable. However, the surface quality of the blank is poor, and the small contact area will also lead to stress concentration, resulting in cracks or tears.

[0080] Therefore, the value of the cone radius r is taken as:

[0081] r = (1-3)t, where t is the thickness of the plate blank;

[0082] Meanwhile, if the working angle α of the double conical spinning wheel 422 is too large, it will increase the height of the material in front of the spinning wheel, which will reduce the fluidity of the material and even cause instability or wrinkling. If it is too small, the contact area between the spinning wheel and the blank will increase, thereby increasing the spinning force and having an adverse effect on spinning. Therefore, the value of the working angle α is 15-30°.

[0083] like Figure 2 , Figure 3 , Figure 4 , Figure 8 , Figure 9 As shown, to further illustrate the technical solution and technical effects of the present invention, the present invention provides the following specific examples:

[0084] Specific example 1: such as Figure 8 As shown,

[0085] The process described in this example is as follows: Figure 8 In the processing flow chart, step (e) of internal tooth spinning involves plate blank 3, which is a plate blank with a mounting shaft hole in the middle. Its size is determined in step (a) blanking. After steps (b), (c), and (d), the blank shown in (d) is obtained. The internal tooth spinning of this invention is performed on the blank of shape (d). At this time, the part of the blank that participates in deep drawing spinning and staggered spinning is the outer side of the circumference. The structure of the central shaft hole of the blank does not affect the process described in this example. The specific processing steps are as follows:

[0086] Step 1: Based on the dimensions and volume of the internal gear transmission part to be formed, determine the plate blank 3. The plate blank 3 is a round plate blank with a diameter of 250mm, a thickness of 8mm, and a material of SAPH440.

[0087] Step 2: Place the plate billet 3 into the annealing furnace, heat the annealing furnace to 750℃, then hold it for 10 hours, cool it down to 450℃ with the furnace, and finally take out the plate billet 3 and air cool it to room temperature to complete the annealing treatment of the initial billet.

[0088] Step 3: Single-pass deep drawing and spinning. The plate blank 3 is drawn and spun in a single pass using a deep drawing and spinning wheel 41. The gap between the deep drawing and spinning wheel 41 and the mandrel 1 is 7mm. The spindle speed is 600rpm. The axial feed speed of the wheel is 1mm / r, so that the plate blank 3 is formed into a cylindrical blank 9 through deep drawing and spinning.

[0089] Among them, the diameter of the deep drawing spinning wheel 41 is D=300mm, the radius of the arc is R=40mm, the arc spinning wheel (421) is the same as the deep drawing spinning wheel 41, the diameter of the double conical spinning wheel 422 is D=300mm, the working angle is α=30°, the cone radius is r=10mm, and the tooth mold 11 on the core mold 1 matches the internal tooth shape of the target part;

[0090] Step 4: In the finite element software ABAQUS, perform a single-pass spinning simulation to determine the amount of reduction required to form the target tooth height. The internal tooth height of the target internal tooth transmission part is 2.25mm. Based on the simulation results, the total reduction of the spinning wheel 42 needs to reach 3mm.

[0091] Step 5: As Figure 2 , Figure 3 , Figure 4 As shown in Table 1, staggered spinning simulation was performed in the finite element software ABAQUS. The specific scheme was determined based on the simulation results, with the radial spacing distributed according to the isorotatory force distribution.

[0092] The radial distance between the first and second spinning rollers 42 is equal to t2, and the radial distance between the second and third spinning rollers 42 is equal to t3. t1 = 1.5 mm, t2 = 0.9 mm, and t3 = 0.6 mm. At this time, the radial distance Δ between the first and second spinning rollers 42 is... 12 = t2=0.9mm, the radial distance Δ between the second and third spinning rollers 42 23 = t3=0.6mm.

[0093] To prevent interference between the spinning wheels, the axial distance S between the first and second spinning wheels 42 is determined. 12 =15mm, the axial distance S between the second and third spinning rollers 42 23 =10mm.

[0094] Table 1

[0095]

[0096] Among them, the spinning pressure difference of multiple spinning rollers 42 is less than 3-5%;

[0097] Step Six: Perform actual staggered spinning on a spinning machine. The positions of the three spinning wheels 42 are determined according to the radial and axial spacing mentioned above. They are evenly distributed around the mandrel and staggered spinning is performed. The spindle speed is 600 rpm and the axial feed speed of the spinning wheels is 1 mm / r, thereby obtaining a toothed transmission part with dimensional accuracy that meets the requirements.

[0098] 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 spinning method for an internal gear transmission component, characterized in that, Includes the following steps: Step 1: In the finite element software, establish a model of the same plate blank (3) and spinning tooling as the actual transmission parts. Use the spinning tooling to perform deep drawing and spinning simulation processing on the plate blank (3) to obtain the simulated cylindrical blank (9). Step 2: Use the spinning fixture model to perform single-pass spinning simulation machining on the cylindrical blank (9) to determine the simulated reduction amount required for the internal tooth height of the transmission parts; The spinning fixture model includes a core mold (1), a deep drawing spinning wheel (41) for deep drawing spinning simulation processing, and a spinning wheel (42) for single-pass spinning simulation processing. The core mold (1) has a tooth mold (11) on its surface that matches the tooth profile of the transmission parts. At this time, the simulated pressing amount is the pressing amount in a single pass spinning process, in which the spinning wheel (42) presses the blank of the transmission part tightly into the tooth mold (11) on the core mold (1), so that the inner surface of the transmission part forms the pressing amount of the target tooth height of the transmission part. Step 3: Using deep drawing spinning and single-pass spinning, and using the reduction amount to actually machine the transmission parts, a transmission part with internal tooth profile is obtained; In step two, a model was established and simulated using multiple spinning wheels (42), and the multiple spinning wheels (42) included at least one circular arc wheel (421) and at least two double conical wheels (422), and the multiple spinning wheels (42) were evenly distributed around the core mold (1). At this time, a spinning wheel (42) is used to simulate the staggered spinning of the cylindrical blank, thereby determining the total simulated reduction required for the internal tooth height of the transmission part; Furthermore, the simulated total reduction is distributed to multiple spinning wheels (42) in different proportions to perform offset spinning simulation processing with different radial offset amounts. The simulated reduction of each spinning wheel (42) is selected when the spinning pressure difference of multiple spinning wheels (42) is less than 5%. The simulated reduction of each spinning wheel (42) is the amount by which each spinning wheel (42) presses the blank of the transmission part tightly into the tooth mold (11) on the core mold (1) in the offset spinning process, so that the inner surface of the blank of the transmission part forms the reduction amount of the target tooth height of the transmission part. The sum of the reduction amounts of each spinning wheel (42) is the total reduction amount, and the total reduction amount is equal to the simulated total reduction amount. Meanwhile, under the premise of preventing interference between multiple spinning wheels (42), the axial spacing of multiple spinning wheels (42) is determined; In step three, multiple spinning wheels (42) are used to perform staggered spinning, and the pressing amount of each spinning wheel (42) is used to actually process the transmission parts to obtain transmission parts with internal teeth. The staggered spinning simulation is the same as the actual staggered spinning. The target tooth height of the transmission part is h=2-4mm. The model of the spinning wheel (42) includes a circular arc wheel (421) and two double conical wheels (422). The total pressing amount of the three spinning wheels (42) is 2.8-6mm. The reduction amounts t1, t2, and t3 of the three spinning rollers (42) are 45-55%, 25-35%, and 15-25% of the total reduction amount, respectively; At this time, the radial distance between the first spinning wheel (42) and the second spinning wheel (42) is equal to t2, and the radial distance between the second spinning wheel (42) and the third spinning wheel (42) is equal to t3; Meanwhile, to prevent interference between the spinning wheels (42), the axial distance S between the first spinning wheel (42) and the second spinning wheel (42) is determined. 12 The axial distance S between the second and third spinning rollers (42) is 15-20 mm. 23 It is 10-15mm.

2. The spinning method for internal gear transmission parts as described in claim 1, characterized in that, In step two, during the single-pass spinning simulation, the gap between the drawing spinning wheel (41) and the mandrel (1) is 6-20mm, the rotation speed of the mandrel (1) is 300-2000rpm, the axial feed speed of the drawing spinning wheel (41) is 0.5-1.5mm / r, and the single-pass spinning simulation is the same as the actual single-pass spinning.

3. The spinning method for internal gear transmission parts as described in claim 1, characterized in that, The plate-shaped billet (3) is a round plate-shaped billet with a diameter of 150-400mm and a thickness of 6-15mm.

4. The spinning method for internal gear transmission parts as described in claim 1, characterized in that, In step two, the single-pass spinning simulation is the same as the actual single-pass spinning. The target tooth height of the transmission part is h=2-4mm, and the total pressing amount of the three spinning wheels (42) is 2.8-6mm.

5. The spinning method for internal gear transmission parts as described in any one of claims 1-4, characterized in that, The plate blank (3) mentioned in step three is made of carbon or alloy structural steel and is annealed before deep drawing and spinning to reduce hardness, improve plasticity and eliminate internal stress in the blank.

6. The spinning method for internal gear transmission parts as described in claim 5, characterized in that, The specific annealing steps are as follows: Place the plate billet (3) into the annealing furnace, heat the annealing furnace to 650-850℃, keep it for 10-15 hours, cool it with the furnace to 400-500℃, and then take out the plate billet and air cool it to room temperature to complete the annealing treatment of the plate billet.

7. A spinning fixture for a spinning method of internal gear transmission parts as described in any one of claims 1-4, characterized in that, Includes a tail top (2), a core mold (1) mounted on a base (8), the tail top (2) and the core mold (1) working together to press the plate-shaped blank (3), the tail top (2), the core mold (1) and the base (8) are coaxially arranged and all driven to rotate by the spindle of the spinning machine; It also includes a deep drawing spinning wheel (41) and three spinning wheels (42) mounted on the spinning wheel frame (7); Among them, the deep drawing spinning wheel (41) is used in deep drawing spinning; the spinning wheel (42) is used in single-pass spinning or staggered spinning. The spinning wheel (42) includes an arc spinning wheel (421) and two double-cone spinning wheels (422). The deep drawing spinning wheel (41) and the arc spinning wheel (421) have the same structure. The diameter D of the deep drawing spinning wheel (41), the circular arc spinning wheel (421), and the double conical spinning wheel (422) is: D = (1.2-2)d, where d is the diameter of the core mold (1); If the diameter D is too small, it will increase the tangential flow of metal and reduce the accuracy of the workpiece; if it is too large, it will increase the spinning force. In the deep drawing and spinning process, in order to increase the contact area between the deep drawing and spinning wheel (41) and the billet and improve the quality of the cylindrical billet (9), the radius R of the deep drawing and spinning wheel (41) is 30-40mm. When the cone radius r of the double-conical spinning wheel (422) is large during single-pass spinning or staggered spinning, the contact area between the double-conical spinning wheel (422) and the blank increases, the blank of the transmission parts is fully compressed, and the surface quality of the formed part is high. However, it will increase the spinning pressure, which is prone to wrinkling and instability of the blank, which is not conducive to the forming of the spun part. When the value of r is small, the spinning pressure decreases and the forming process is more stable. However, the surface quality of the blank is poor, and the small contact area will also lead to stress concentration, resulting in cracks or tears. Therefore, the value of the cone radius r is taken as: r = (1-3)t, where t is the thickness of the plate blank (3); Meanwhile, if the working angle α of the double conical spinning wheel (422) is too large, the height of the material in front of the spinning wheel will increase, which will make the material flow poor, or even cause instability or wrinkling. If it is too small, the contact area between the spinning wheel and the blank will increase, which will increase the spinning pressure and have an adverse effect on spinning. Therefore, the value of the working angle α is 15-30°.

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