An integrated hollow motor shaft closed spinning forming process and device, spinning wheel

Abstract

A kind of integrated hollow motor shaft closed end spinning forming process and device, spinning wheel, the closed end spinning process of integrated hollow motor shaft, it includes the following steps: first, pipe blank blanking;Second, open end spinning;Third, closed end spinning;Fourth, machining finishing.Processing is realized by spinning the closed end of motor shaft, maximum degree close to finished product profile, reduce the subsequent machining allowance, improve the production efficiency of product, realize lightweight while improving the utilization rate of material, reduce the production cost of product.Relative to traditional welding process, closed end spinning forming is efficient, stable, flexible, realizes the integrated structure of motor shaft.By plastic forming of spinning, the motor shaft has uninterrupted material flow line organization, material is more dense, reduces the failure risk of subsequent process processing.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicles and new energy vehicle drive motor components, specifically to a closed-end spinning forming process for a hollow motor shaft with one end closed. Background Technology

[0002] The rapid development of new energy vehicles has placed higher demands on their components. This patented technology effectively utilizes the molding of a closed-end structure at one end of the hollow motor shaft, a core component of the drive motor in new energy vehicles. The motor shaft not only needs to be lightweight to achieve high vehicle range, but also needs to accommodate the flow space for cooling oil at ultra-high speeds (some motor shafts operate at speeds exceeding 20,000 rpm). A thin-walled, hollow structure for the motor shaft is an essential trend for future development. Some hollow motor shafts, such as... Figure 1 One end is open, and the other end is closed. The open end allows cooling oil to enter the cavity of the motor shaft; the main function of the closed end is to seal the cooling oil inside the hollow shaft so that it does not leak out, because the cooling oil and the reducer lubricating oil connected to the closed end are of different types and cannot be mixed. Traditional molding methods include... Figure 2 As shown, both the upper and lower parts are made of bar stock. The closed end is forged into a blank with a shallow blind hole, and then turned to form a deep blind hole and thin wall. The open end is turned and then welded to the closed end to complete the required structure. Due to the limitations of the forging process, the depth of the forged blind hole is limited, requiring extensive machining to achieve the final hole depth. This process has low material utilization and low processing efficiency, resulting in material waste and increased costs for mass production. Furthermore, deformation and defects at the welded parts affect subsequent heat treatment or machining of the workpiece, increasing the risk of failure in the later market. Summary of the Invention

[0003] The purpose of this invention is to provide an integrated hollow motor shaft closed-end spinning forming process and device, and a spinning wheel. The integrated forming process is efficient, stable, and highly flexible, which can effectively solve the above-mentioned problems existing in the existing machining processes.

[0004] The technical solution of this invention is: an integrated spinning process for a hollow motor shaft with a closed end.

[0005] First step, blank blanking: Calculate the diameter and thickness of the blank based on the final product specifications and subsequent machining allowance;

[0006] Second step, closing and spinning: The tube blank obtained in the first step is fixed on the spinning equipment by a chuck, and the open end is closed and spun to obtain tube blank one;

[0007] Third-stage closed-end spinning: After flipping the tube blank obtained in the second stage, it is fixed on the spinning equipment by a chuck. At the same time, the upper die pressure rod presses down on the closed end face, and the closed end is spun by a spinning wheel to obtain the tube blank second.

[0008] Fourth stage, finishing: The tube blank obtained in the third stage is finished by machining.

[0009] In the three-stage closed-end spinning process, the spinning wheel only feeds and extrudes along the radial direction of the tube blank, and no longer moves and extrudes along the axial direction. This reduces the elongation of the tube blank during the spinning process, allowing more material to flow into the inner diameter, which is beneficial for closing the tube blank.

[0010] In the three-stage closed-end spinning process, two identical symmetrical spinning wheels are arranged and fed synchronously to ensure uniform and consistent force on the part during processing. This prevents the blank from skewing during the spinning wheel feed, which would affect the closing effect and cause large deviations in the coaxiality of the profile and clamping positioning surface. The two identical spinning wheels in the three-stage process are spinning wheel three and spinning wheel four.

[0011] The working surface of the spinning wheel used in the three-stage closed-end spinning process is a step consisting of a closed section, a transition section, and a closing section. When extruding the tube blank, it can promote the material to flow towards the closed direction, which is beneficial for closing.

[0012] The height difference between the closed section and the closed section of the spinning wheel used in the three-stage closed spinning process is 5-8 mm, referring to the step height difference of the final product; the transition section is an arc section with an arc radius R of 20-25 mm.

[0013] The pressure bar used in the three-stage closed-end spinning process restricts the material of the tube blank from flowing more easily in the elongation direction; it prevents the inner diameter from shrinking to a certain extent, causing the thickness of the tube blank to continuously decrease and the length to continuously increase, but the inner diameter to no longer decrease, thus making it impossible to achieve a closed seal; the pressure bar maintains a certain clamping force F on the tube blank during the spinning process, which can effectively restrict elongation and promote the material to flow towards the closed end.

[0014] The diameter of the pressing surface of the pressure rod is 1-2 mm larger than the outer diameter of the tube blank before processing. The entire bottom surface of the tube blank is pressed down to prevent the material from flowing out from the side. The pressure value is light pressure of 3-5 MPa. Excessive pressure will cause the tube blank to deform. At the same time, the pressure rod has the function of moving up and down when maintaining pressure to prevent excessive pressing force from causing overload.

[0015] The spinning process of the closed end of the integrated hollow motor shaft is described. The spinning equipment is equipped with upper and lower main shafts and a side cylinder assembly. First, the tube blank is placed into the lower shaft chuck. The lower shaft chuck is fixed to the lower main shaft of the spinning equipment through the lower shaft assembly. When the spinning equipment is started, the lower shaft chuck clamps the tube blank and drives the tube blank to rotate.

[0016] The pressure bar is installed on the upper shaft fixing seat, which is fixed to the equipment by the upper shaft assembly. The equipment drives the bar to move up and down, pressing the tube blank one, and rotating in the opposite direction. The diameter of the pressure surface of the pressure bar is 1-2mm larger than the outer diameter of the tube blank one before processing. The entire bottom surface of the tube blank one is pressed down to prevent the material from flowing out from the side. The pressure value is a light pressure of 3-5MPa.

[0017] Roller 3 is mounted on the left-side roller bracket and fixed to the side cylinder of the equipment via the side cylinder assembly. Driven by the left-side roller bracket, roller 3 moves left and right to approach tube blank 1, radially feeding and extruding tube blank 1. After contacting tube blank 1, roller 3 rotates in the opposite direction to extrude the tube blank inward and eventually close it. Roller 4 is symmetrically mounted on the right side of roller 3. Roller 4 and roller 3 are exactly the same in size and assembly. Roller 4 is driven by the roller bracket and moves synchronously with roller 3. Roller 3 and roller 4 are symmetrically distributed, balancing the lateral extrusion force on tube blank 1 during the spinning process and preventing tube blank 1 from tilting during the spinning process. During the feeding and extrusion process of rollers 3 and 4, the material flow will cause tube blank 1 to elongate upward. The clamping force of the pressure rod restricts the elongation of tube blank 1 and promotes the material flow to the closed end. In addition, the pressure rod has a function of moving up and down when in the pressure holding state to prevent excessive clamping force from causing overload.

[0018] An integrated spinning forming device for closing the closed end of a hollow motor shaft includes a spinning wheel for closing the spin and a pressure rod for pressing the closed end face of the blank to be processed. The spinning equipment is equipped with a lower shaft chuck for fixing the blank to be processed, a spinning wheel bracket for fixing the spinning wheel, and an upper shaft fixing seat for fixing the pressure rod. The diameter of the pressing surface of the pressure rod is 1-2 mm larger than the outer diameter of the blank to be processed before processing. The working profile of the spinning wheel for closing the spin has a step consisting of a closed section, a transition section, and a closing section. The height difference between the closed section and the closing section is 5-8 mm. The transition section is an arc section with an arc radius R of 20-25 mm.

[0019] A spinning wheel for spinning an integrated hollow motor shaft with a closed end includes a spinning wheel body. The working cross-section of the spinning wheel body is composed of multiple line segments, including an upper plane, a closed section, a transition section, a closing section, and a lower plane. The closed section, transition section, and closing section constitute the working part and form a step. The upper part of the step connects to the upper plane, and the lower part of the step connects to the lower plane. The height difference between the closed section and the closing section is 5-8 mm. The transition section is an arc segment with an arc radius R of 20-25 mm.

[0020] Because the final product requires high quenching hardness, this invention uses 20CrMoTi tube blanks as raw materials, with a tensile strength ≥1080. First, the open end of the tube blank is spun to close it, then the closed end is spun to close it. The main process of spun closing is as follows: the tube blank is fixed and rotated, while a spinning wheel continuously feeds and compresses the tube blank to close it. Under the constraint of the spinning wheel profile and the pressure bar, a closed end is finally formed. This spinning process is a plastic forming process that prevents the metal flow lines of the material from being cut off, resulting in a more uniform material structure and improved mechanical properties. Finally, the product is finished through machining.

[0021] In the three-stage closed-end spinning process, material flow is more intense than in the two-stage process, and the inner diameter is zero. Using conventional shrinking spinning methods, once the inner diameter is reduced to a certain extent, further inward extrusion results in a situation where the tube thickness continuously decreases and the length continuously increases, but the inner diameter no longer decreases synchronously, making closed-end sealing impossible. In practice, forcibly shrinking the tube inward eventually leads to tube breakage, with the smallest inner diameter still exceeding 1mm, failing to achieve closed-end sealing. Furthermore, the material itself has high strength and relatively poor elongation, resulting in high spinning resistance. Difficult, unstable, and uncontrollable material flow are the main challenges of closed-end spinning. To address these problems, the main solutions employed in this invention include:

[0022] (1) In the three-stage closing spinning process, the spinning wheel only feeds and extrudes along the radial direction of the tube blank, and no longer moves and extrudes along the axial direction; unlike the two-stage closing spinning process, the spinning wheel feeds and extrudes along both the radial and axial directions of the tube blank simultaneously. This can reduce the elongation of the tube blank during the spinning process, allowing more material to flow into the inner diameter, which is beneficial for closing. During operation, two spinning wheels are set in a symmetrical layout and feed synchronously to ensure that the force on the parts is uniform and consistent during the processing, avoiding the parts from being skewed when the spinning wheels are feeding, which would affect the closing effect and cause a deviation in the coaxiality of the forming surface and the clamping positioning surface.

[0023] (2) The working surface of the three-stage closed-end spinning roller is set with shapes such as end section, closed section and transition section. When the tube blank is extruded radially, the amount of material flowing into the inner diameter is increased, which is beneficial to closing.

[0024] (3) During the three-stage closed-end spinning, the spinning wheel squeezes the tube blank while the upper shaft clamping rod clamps the tube blank, restricting the tube blank from elongating along the axial direction, so that the material flows into the closed direction.

[0025] This invention achieves a closed end of the motor shaft through a spinning process, closely approximating the finished product contour, reducing subsequent machining allowances, improving production efficiency, and simultaneously achieving lightweighting of the motor shaft while increasing material utilization and reducing production costs. The spinning plastic forming process gives the motor shaft a continuous material flow structure, and under compressive stress, the material becomes denser, increasing the surface hardness of the part and reducing the risk of failure in subsequent processing steps. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0027] Figure 1 This is a schematic outline of the product to which the present invention is applied;

[0028] Figure 2 This is a schematic diagram of the process steps in traditional welding products.

[0029] Figure 3 This is a schematic diagram of the process of applying the product technology of this invention;

[0030] Figure 4 This is a schematic diagram of the three-stage closed-loop spinning process;

[0031] Figure 5 This is a schematic diagram of the spinning wheel in the three-stage closed-loop spinning process;

[0032] Figure 6 This is a schematic diagram of the pressure bar 3 in the three-stage closed spinning process;

[0033] Figure 7 This is a schematic diagram of the two-stage closing spinning process;

[0034] Figure 8 This is a schematic diagram of the rotary wheel in the second-stage closing and spinning process. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Technologies, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be considered part of the specification.

[0036] like Figure 1 As shown, the product is a hollow motor shaft with closed ends. The left end is open, and the right end is closed. The closed end A mainly serves a sealing function to prevent pressurized cooling oil that enters the cavity from the open end from leaking out from the closed end.

[0037] like Figure 2As shown, traditional manufacturing processes for such products typically involve using two separate bars, one for the open end and one for the closed end, to hollow out their internal cavities through forging and machining, before finally welding them together. Weld B reduces the product's strength, and manufacturing defects in the weld can also lead to reduced sealing performance. The most significant problem is that machining the internal cavities at both the open and closed ends requires extensive turning, resulting in low material utilization and processing efficiency. For mass production, this leads to material waste and increased costs.

[0038] like Figure 3 As shown, the process provided by this invention mainly consists of four steps: first, billet blanking; second, open-end spinning; third, closed-end spinning; and fourth, finishing. Specifically:

[0039] First step, billet cutting: Calculate based on product specifications and process, taking into account a certain margin factor.

[0040] Second step, opening spin forming: Fix the product obtained in the first step on the equipment, and use a spinning wheel to perform closing spin forming and shoulder shaving on the opening end.

[0041] Third step, closed-end spinning: The product obtained in the second step is flipped over, the open end is fixed on the equipment, and the closed end is spun using a spinning wheel.

[0042] Fourth stage, finishing: The product obtained from the third stage is finished by turning, milling, gear hobbing, grinding and other processes.

[0043] The process provided by this invention uses hollow tube blanks for closed-end spinning and forming, and employs a non-chip removal machining process. The inner cavity is no longer machined separately, the outer cavity closely approximates the finished product outline, and the final finishing allowance is very small, resulting in a significant improvement in material utilization and processing efficiency; the integrated structure also increases the reliability of product performance.

[0044] like Figure 4 The diagram illustrates the three-stage closed-end spinning process. The spinning equipment is equipped with upper and lower shafts and a side cylinder assembly. First, the tube blank 1 obtained from the second-stage open-end spinning is placed into the lower shaft chuck 2, which is fixed to the lower main shaft of the equipment via the lower shaft assembly. During operation, the equipment starts, the lower shaft chuck 2 clamps the tube blank 1, and drives the tube blank 1 to rotate.

[0045] The pressure rod 3 is mounted on the upper shaft fixing seat 4, which is fixed to the equipment via the upper shaft assembly. Driven by the equipment, it moves up and down, pressing the tube blank 1, and then rotates in the opposite direction. The diameter of the pressure surface of the pressure rod 3 is 1-2 mm larger than the outer diameter of the tube blank 1 before processing. The entire bottom surface of the tube blank is pressed down, preventing material from flowing out from the side. The pressure value is a light pressure of 3-5 MPa; excessive pressure may cause deformation of the tube blank.

[0046] The third rotary wheel 5 is mounted on the left rotary wheel bracket 6 and fixed to the side cylinder of the equipment via the side cylinder assembly. Driven by the rotary wheel bracket 6, the third rotary wheel 5 moves left and right to approach the tube blank 1, radially feeding and extruding the tube blank 1. After contacting the tube blank 1, the third rotary wheel 5 rotates in the opposite direction, extruding the tube blank inwards until it is closed. The fourth rotary wheel 7 is symmetrically mounted on the right side of the third rotary wheel 5. The fourth rotary wheel 7 is identical in size and assembly to the third rotary wheel 5, driven by the rotary wheel bracket 8 and moving synchronously with the third rotary wheel 5. The symmetrical distribution of the third rotary wheel 5 and the fourth rotary wheel 7 balances the lateral extrusion force on the tube blank 1 during the spinning process, preventing the tube blank 1 from tilting and affecting accuracy. During the feeding and extrusion process of the third rotary wheel 5 and the fourth rotary wheel 7, the material flow causes the tube blank 1 to elongate upwards. The clamping force of the pressure rod 3 restricts the elongation of the tube blank 1 and promotes the material flow towards the closed end. In addition, the pressure rod 3 also has the function of moving up and down when in the pressure holding state to prevent excessive clamping force from causing overload.

[0047] like Figure 5 As shown, the three-stage closed-end spinning roller (model 3.5) consists of multiple line segments, including an upper plane 301, a closed section 302, a transition section 303, a closing section 304, and a lower plane 305. The closed section 302, transition section 303, and closing section 304 form the working part. The closed section 302 and closing section 304 have a certain height difference, forming a step with the transition section 303. This promotes material flow towards the closed end during the extrusion of the tube blank. The height difference between the closed section 302 and closing section 304 can be referenced to the step height difference of the final product, but a range of 5-8 mm is most effective in achieving product closure.

[0048] like Figure 6 As shown, the main function of the pressure rod 3 used in the three-stage closed-end spinning process is: during the normal unrestricted closing spinning process, the material of tube blank 1 is most likely to flow in the elongation direction; when the inner diameter is reduced to a certain extent, and then squeezed inward, the thickness of the tube blank will continuously decrease and the length will continuously increase, but the inner diameter will no longer decrease, and the closed seal cannot be achieved; the pressure rod 3 always maintains a certain clamping force on tube blank 1 during the spinning process, which can effectively limit the elongation and promote the material to flow towards the closed end.

[0049] like Figure 7 Schematic diagram of the second-stage finishing spinning process: The spinning equipment is equipped with a lower die fixture and a side cylinder fixing seat assembly, such as... Figure 8As shown. The tube blank 9 obtained in the first sequence is placed in the lower shaft chuck 10, which is fixed to the lower shaft of the equipment by components such as the lower die clamp. During operation, the lower shaft chuck 10 is activated to clamp the tube blank and drive it to rotate. The rotating wheel 11 is fixed to the equipment by the side cylinder assembly. Driven by the equipment, the rotating wheel 11 moves left and right to approach the upper end of the tube blank, moves from top to bottom, and radially penetrates 3mm. After contacting the tube blank, the rotating wheel 11 rotates in the opposite direction to squeeze the tube blank to close the end and elongate it upwards. After reaching the set position, the above actions are repeated to squeeze the tube blank to close the end to the set size. A rotating wheel 12 is symmetrically installed on the right side of the rotating wheel 11. The rotating wheel 12 is exactly the same in size and assembly method as the rotating wheel 11, and moves synchronously. The rotating wheel 12 has a later axial stroke and a radial penetration of 3mm more than the rotating wheel 11. The setting of the rotating wheel 12 is equivalent to completing the processing volume of 2 times in one feed, improving the operation efficiency. Simultaneously, the two spinning wheels (i.e., spinning wheel one 11 and spinning wheel two 12) work symmetrically, balancing the lateral extrusion force of spinning wheel one 11 on the tube blank 9, thus obtaining tube blank one. Among them, the left spinning wheel shaft 13 is fixed to the side cylinder of the spinning equipment through the spinning wheel bracket 14.

[0050] Closed spinning requires controlling the material flow in the axial elongation direction and increasing the material flow in the radial direction. The main differences are: (1) the closed spinning wheel 35 only feeds radially, while the closed spinning wheel 11 feeds radially and axially at the same time; (2) the closed spinning is equipped with a pressure rod 3.

[0051] like Figure 8 The spinning wheel 11 used in the second-stage necking spinning process consists of multiple line segments, including an upper plane 1101, an upper inclined plane 1102, an arc segment 1103, a lower inclined plane 1104, and a lower plane 1105. Among them, the arc segment 1103 and the lower inclined plane 1104 constitute the working part. The radius of the arc segment 1103 is 15-20mm, which is selected according to the necking ratio. The lower inclined plane 1104 and the bottom surface are at a 40-45 degree angle.

[0052] The above description is merely an exemplary 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 forming process for an integrated hollow motor shaft with a closed end, characterized in that: First step, blank blanking: Calculate the diameter and thickness of the blank based on the final product specifications and subsequent machining allowance; Second step, closing and spinning: The tube blank obtained in the first step is fixed on the spinning equipment by a chuck, and the open end is closed and spun to obtain tube blank one; Third-stage closed-end spinning: After the tube blank obtained in the second stage is flipped over, it is fixed on the spinning equipment by a chuck. The spinning equipment includes a spinning wheel for closed-end spinning and a pressure rod for pressing the closed end face of the tube blank to be processed. The spinning wheel includes a third spinning wheel (5) and a fourth spinning wheel (7). The spinning equipment is provided with a lower shaft chuck for fixing the tube blank to be processed, a spinning wheel bracket for fixing the spinning wheel, and an upper shaft fixing seat for fixing the pressure rod. The working surface section of the spinning wheel used for closed-end spinning is provided with a step consisting of a closed section (302), a transition section (303), and a closing section (304). The height difference between the closed section (302) and the closing section (304) is 5-8 mm. The transition section (303) is an arc section with an arc radius R of 20-25 mm. The spinning equipment is equipped with upper and lower main shafts and side cylinder assembly; firstly, the tube blank is placed into the lower shaft chuck (2), and the lower shaft chuck (2) is fixed on the lower main shaft of the spinning equipment through the lower shaft assembly. When the spinning equipment is started, the lower shaft chuck (2) clamps the tube blank and drives the tube blank to rotate. The pressure rod (3) is installed on the upper shaft fixing seat (4), which is fixed to the equipment by the upper shaft assembly. The equipment drives the rod to move up and down, pressing the tube blank one, and rotating in the opposite direction. The diameter of the pressing surface of the pressure rod (3) is 1-2 mm larger than the outer diameter of the tube blank one before processing. The entire bottom surface of the tube blank one is pressed to prevent the material from flowing out from the side. The pressure value is 3-5 MPa. The third swivel wheel (5) is mounted on the left swivel wheel bracket (6) and fixed by the side cylinder assembly and the equipment side cylinder. Driven by the left swivel wheel bracket (6), the third swivel wheel (5) moves left and right to approach the first tube blank and feeds radially to extrude the first tube blank. After the third swivel wheel (5) contacts the first tube blank, it rotates in the opposite direction to extrude the tube blank inward and finally closes the end. The fourth swivel wheel (7) is symmetrically mounted on the right side of the third swivel wheel (5). The fourth swivel wheel (7) and the third swivel wheel (5) are exactly the same in size and assembly method. The fourth swivel wheel (7) is driven by the swivel wheel bracket (8) and moves synchronously with the third swivel wheel (5). The three (5) and four (7) spinning wheels are symmetrically distributed, balancing the lateral extrusion force of the tube blank during the spinning process and preventing the tube blank from tilting during the spinning process; during the feeding and extrusion process of the three (5) and four (7) spinning wheels, the material flow will cause the tube blank to elongate upwards, and the clamping force of the pressure rod (3) will limit the elongation of the tube blank and promote the material flow to the closed end; in addition, the pressure rod (3) has the function of moving up and down when holding pressure, preventing the pressure force from being too large and causing overload; during the three-sequence closed spinning, the spinning wheels only feed and extrude along the radial direction of the tube blank and no longer move and extrude along the axial direction; Fourth stage, finishing: The tube blank obtained in the third stage is finished by machining.

Images