New energy automobile motor cover plate forming method
By using continuous die multi-station stamping process and local induction heating and cooling technology, the problems of residual stress concentration and warping deformation of motor cover plates in new energy vehicles have been solved, achieving efficient and precise forming and high material utilization, and improving the flatness and structural consistency of motor cover plates.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-11
- Publication Date
- 2026-04-17
AI Technical Summary
In the manufacturing of motor covers for new energy vehicles, existing technologies suffer from residual stress concentration and warping deformation due to high material utilization and complex structural forming. These problems are difficult to eliminate effectively using traditional methods, affecting flatness and assembly accuracy.
By employing a continuous die multi-station stamping process, combined with local induction heating, cooling and pressure holding technologies, and through thermo-mechanical coupling precision separation, stepped thermal-assisted three-dimensional forming, in-mold stress homogenization and room temperature precision machining, precision forming and stress control of metal strips are achieved.
It significantly improves the flatness and dimensional accuracy of the motor cover, enhances production efficiency and material utilization, avoids additional heat treatment processes, and ensures structural stability and consistency.
Smart Images
Figure CN121869968A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy vehicle parts manufacturing technology, and in particular to a method for forming a motor cover plate for new energy vehicles. Background Technology
[0002] As a key structural component, the drive motor end cap of new energy electric vehicles mainly uses advanced high-strength steel strip, and its manufacturing trend is towards high strength, lightweight, and integrated molding of complex geometric features. Currently, the industry generally uses multi-station progressive die stamping processes for high-efficiency production. To improve material utilization, optimized layout designs are commonly used, such as nesting the protrusions and concave contours of adjacent workpieces. However, the combination of such irregular nested contours with subsequent multi-step progressive blanking, deep drawing, and three-dimensional forming processes introduces complex and uneven plastic strain and work hardening within the material, resulting in residual stress in specific areas of the workpiece (especially at the connection root of the parallel protrusion structure 1, such as...). Figure 1 As shown in the figure, the stress is significantly concentrated. This stress is released after forming, often manifesting as warping deformation at both ends of the workpiece along its length, which seriously affects the flatness of the end cap, assembly accuracy, and overall structural reliability.
[0003] Traditional solutions primarily rely on separate leveling processes after forming or overall heat treatment annealing to eliminate stress. The former can only correct macroscopic deformation but cannot eliminate internal stress, resulting in springback issues; the latter requires additional heating equipment, has a long production cycle, high energy consumption, and may lead to material performance degradation or surface oxidation. Some technologies have attempted to introduce heating during the stamping process, but these are mostly global heating or single-temperature heating, lacking the precise energy input and zoned temperature control capabilities to match complex stamping sequences. This makes it difficult to achieve synchronous dynamic control of stress generation and elimination, easily causing new thermal stress or affecting local material properties.
[0004] Therefore, there is an urgent need in the existing technology: to develop an intelligent, localized thermo-mechanical coupling control method that can be deeply integrated into the continuous die stamping process, so as to suppress and eliminate harmful residual stress in the forming process of complex workpieces from the root while ensuring high material utilization and high production efficiency, and to ensure dimensional accuracy and structural stability. Summary of the Invention
[0005] The purpose of this invention is to provide a method for forming a cover plate for a new energy vehicle motor, so as to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for forming a motor cover plate for new energy vehicles, which uses a continuous die for multi-station stamping, characterized in that the method includes the following steps performed in sequence: S1. Strip pretreatment: Uncoiling, leveling and cleaning of metal strip; S2. Precision separation by thermal coupling: During the stamping process, the planned internal separation area on the strip is first locally induction heated to a predetermined temperature, and then punched to form an internal separation seam and connecting bridge; subsequently, the connecting bridge area is heated and punched to separate the workpiece blank from the strip. S3, Stepped thermal assisted three-dimensional forming: The predetermined three-dimensional structure area of the separated workpiece blank is locally induction heated to a second predetermined temperature, which is higher than the first predetermined temperature. After heating, the three-dimensional structure is immediately drawn or formed. Then, the edge area of the workpiece is cooled and the edge structure is cold formed. S4. In-mold stress homogenization and finishing: Apply pressure to the workpiece after step S3 in the mold and hold the pressure, and use the residual heat of the workpiece to relax the stress in the mold. S5. Room temperature finishing and leveling: Under the assistance of micro-area heating at room temperature or a third predetermined temperature, hole punching, final blanking of the shape and three-dimensional leveling are performed.
[0007] In the new energy vehicle motor cover forming method of the present invention, in step S2, the first predetermined temperature is set to the temperature at which the material is in the dynamic recovery stage; The first predetermined temperature is 450℃-550℃; The local induction heating is achieved by an eddy current induction coil embedded in the punch or die, and the heating time is controlled between 0.5 seconds and 1.5 seconds.
[0008] In the new energy vehicle motor cover forming method of the present invention, in step S3, the second predetermined temperature is set to be close to the material recrystallization temperature or austenitization temperature. The second predetermined temperature is 650℃-720℃; The three-dimensional structure includes multiple parallel protrusions in the middle of the motor end cover, and the heating area precisely covers the root connection area and the protrusion body of the protrusions.
[0009] In the new energy vehicle motor cover forming method of the present invention, in step S3, "cooling the edge area of the workpiece" is carried out by circulating cooling medium through a cooling channel integrated in the mold, or by using fixed-point air mist spraying to quickly cool the annular area that needs to be edge formed to below 100°C, while the three-dimensional structure area, due to its large heat capacity, still maintains a temperature above 200°C, thereby forming a regional temperature difference.
[0010] The method for forming a motor cover plate for new energy vehicles according to the present invention, wherein in step S4, the holding pressure is 1.5 to 2.5 times the yield strength of the material, and the holding time is 2 to 5 seconds; During the pressure holding process, the three-dimensional structural region undergoes creep under the combined action of pressure and residual heat, achieving stress relaxation and geometric stability.
[0011] In the new energy vehicle motor cover forming method of the present invention, in step S5, before punching the hole and finally blanking the shape, the local area of the corresponding punching path is subjected to pulse induction heating at the third predetermined temperature. The third predetermined temperature is lower than the first predetermined temperature, specifically 300℃-400℃, and the heating time is less than 0.3 seconds.
[0012] The method for forming a motor cover plate for new energy vehicles according to the present invention is characterized by further including step S0, online sensing and closed-loop control: After heating in at least step S2, after heating in step S3, and after step S5, an infrared thermal imager is used to perform non-contact measurement of the workpiece temperature field, and a laser profile scanner is used to detect the deformation of key parts of the workpiece. The measurement data is fed back to the central controller, which has a pre-set process parameter model that can dynamically adjust the power, time parameters and cooling intensity of subsequent heating stations to achieve closed-loop control of temperature and strain.
[0013] The new energy vehicle motor cover plate forming method of the present invention, wherein the eddy current induction coil is a modular contour splicing coil, the shape of which matches the contour of the target heating area of the corresponding heating station; For heating areas with complex shapes, multiple independent temperature and time control sub-coil units are combined to achieve differentiated gradient heating of different areas of the same workpiece.
[0014] The new energy vehicle motor cover forming method of the present invention includes generating a unique "thermal-mechanical process history file" for each workpiece during continuous production. The file records the actual temperature-time curves at each heating station, the pressure-displacement curves at each forming station, and online deformation detection data. The file is bound to the workpiece's serial number for quality traceability and process optimization.
[0015] The method for forming a cover plate for a new energy vehicle motor according to the present invention includes a nesting design stage in which the protruding structure and concave contour of adjacent workpieces are nested; the shape and position of the internal separation seam are designed according to the gap between the protrusion and concave of adjacent workpieces in the nested nesting, and the gap width is 1.0 to 1.5 times the material thickness.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention discloses a method for forming a motor cover plate for new energy vehicles, aiming to solve the problems of residual stress concentration and warping deformation of the end cover caused by high material utilization layout and complex structure forming. The method employs a continuous die multi-station stamping process, sequentially performing strip pretreatment, thermo-coupling precision separation, stepped heat-assisted three-dimensional forming, in-mold stress homogenization and finishing, and room-temperature finishing and leveling. Its core lies in applying localized induction heating at different levels to specific areas of the metal strip or workpiece blank before the critical punching and forming stations, combined with cooling and pressure holding processes after forming. This method, through the thermo-coordinated processes of "heating to plasticize and reduce forming stress, zoned temperature control to coordinate deformation, and in-mold creep to homogenize residual stress," eliminates harmful stresses that cause workpiece deformation in situ during the stamping process, significantly improving the flatness, dimensional accuracy, and structural consistency of the motor end cover, while avoiding subsequent separate heat treatment processes, thus improving production efficiency and material utilization. Attached Figure Description
[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the end cap structure after processing by the molding method of the present invention.
[0019] Figure 2 This is a schematic diagram of the punching of the blank and strip in the initial stage of the forming method of the present invention.
[0020] Figure 3 This diagram illustrates the continuous changing states of the workpiece end cap processed by the molding method of the present invention.
[0021] Figure 4 This is a flowchart of the molding method of the present invention. Detailed Implementation
[0022] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.
[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0024] "Multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0025] Furthermore, the terms indicating orientation, such as "up," "down," "left," "right," "upper end," "lower end," and "longitudinal," are all based on the posture and position of the device or equipment described in this solution during normal use.
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, a clear and complete description will be provided below in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.
[0027] This embodiment discloses, as follows: Figures 1 to 4 The method for forming the motor cover of a new energy vehicle shown employs a progressive die for multi-station stamping. This method includes the following steps performed sequentially: S1. Strip pretreatment: Uncoiling, leveling and cleaning the metal strip 10; S2. Precision separation by thermal coupling: During the stamping process, the internal separation area 20 planned on the strip 10 is first locally induction heated to a first predetermined temperature, and then punched to form the internal separation seam 30 and the connecting bridge 40; then the area of the connecting bridge 40 is heated and punched to separate the workpiece blank 500 from the strip 10. S3, Stepped thermal assisted three-dimensional forming: The predetermined three-dimensional structure region 50 of the separated workpiece blank is locally induction heated to a second predetermined temperature, which is higher than the first predetermined temperature. After heating, the three-dimensional structure is immediately drawn or formed; then the edge region of the workpiece is cooled and the edge structure is cold formed. S4. In-mold stress homogenization and finishing: Apply pressure to the workpiece after step S3 in the mold and hold the pressure, and use the residual heat of the workpiece to relax the stress in the mold. S5. Room temperature finishing and leveling: Under the assistance of micro-area heating at room temperature or a third predetermined temperature, hole punching, final blanking of the shape and three-dimensional leveling are performed.
[0028] This invention discloses a method for forming a motor cover plate for new energy vehicles, aiming to solve the problems of residual stress concentration and warping deformation of the end cover caused by high material utilization layout and complex structure forming. The method employs a continuous die multi-station stamping process, sequentially performing strip pretreatment, thermo-coupling precision separation, stepped heat-assisted three-dimensional forming, in-mold stress homogenization and finishing, and room-temperature finishing and leveling. Its core lies in applying localized induction heating at different levels to specific areas of the metal strip or workpiece blank before the critical punching and forming stations, combined with cooling and pressure holding processes after forming. This method, through the thermo-coordinated processes of "heating to plasticize and reduce forming stress, zoned temperature control to coordinate deformation, and in-mold creep to homogenize residual stress," eliminates harmful stresses that cause workpiece deformation in situ during the stamping process, significantly improving the flatness, dimensional accuracy, and structural consistency of the motor end cover, while avoiding subsequent separate heat treatment processes, thus improving production efficiency and material utilization.
[0029] In this embodiment, in step S2, the first predetermined temperature is set to the temperature at which the material is in the dynamic recovery stage; the first predetermined temperature is 450℃-550℃; the local induction heating is achieved by an eddy current induction coil embedded in the punch or die, and the heating time is controlled between 0.5 seconds and 1.5 seconds; the advantage of this process setting is that it ensures that the material is in the best plastic state during the first precise separation, which reduces the punching force, extends the die life, improves the cross-sectional quality, and avoids performance degradation or deformation caused by overheating, thus laying an ideal initial stress state for subsequent processes.
[0030] In this embodiment, in step S3, the second predetermined temperature is set to be close to the material recrystallization temperature or austenitizing temperature; the second predetermined temperature is 650℃-720℃; the three-dimensional structure includes multiple parallel protrusions in the middle of the motor end cover, and the heating area precisely covers the root connection area and the protrusion body of the protrusions; by applying a temperature sufficient to induce highly plastic flow or beneficial phase transformation of the material to the root of the "multiple parallel protrusions" where the stress is most concentrated, the internal stress during the molding process is released to the maximum extent, which is the core step of this method to solve the end cover warping problem.
[0031] In this embodiment, the "cooling of the workpiece edge area" in step S3 is achieved by using a cooling channel integrated in the mold to circulate a cooling medium, or by using a fixed-point aerosol spray to rapidly cool the annular area that needs to be edge-shaped to below 100°C. Meanwhile, the three-dimensional structure area, due to its large heat capacity, maintains a temperature above 200°C, thus creating a regional temperature difference. This achieves a "hot core, cold edge" partitioning state, allowing the edge structure to be cold-formed with high precision to ensure dimensions, while allowing the high-temperature core area to freely compensate for deformation under pressure, greatly reducing the mutual restraint and competitive stress between different structures during forming.
[0032] In this embodiment, in step S4, the holding pressure is 1.5 to 2.5 times the yield strength of the material, and the holding time is 2 to 5 seconds. During the holding process, the three-dimensional structure region undergoes creep under the combined action of pressure and residual heat, achieving stress relaxation and geometric stability. By utilizing pressure and residual heat, under the precise constraint of mold closure, the creep relaxation behavior of the material is actively induced, and the uneven residual stress is "ironed out" in the mold, which is a key guarantee for achieving dimensional stability and shape accuracy.
[0033] In this embodiment, in step S5, before punching the holes and final blanking the shape, pulsed induction heating of the third predetermined temperature is applied to the local area of the corresponding punching path; the third predetermined temperature is lower than the first predetermined temperature, specifically 300℃-400℃, and the heating time is less than 0.3 seconds; limited thermal assistance is provided only in the local area where high punching quality is required, which can significantly reduce the punching force, obtain a smooth cross-section (especially for high-strength steel), and avoid reintroducing unnecessary thermal stress or affecting the dimensions of the formed structure due to large-area heating.
[0034] In this embodiment, the method described in this solution further includes step S0, online sensing and closed-loop control: After heating in at least step S2, after heating in step S3, and after step S5, an infrared thermal imager is used to perform non-contact measurement of the workpiece temperature field, and a laser profile scanner is used to detect the deformation of key parts of the workpiece. The measurement data is fed back to the central controller, which has a pre-set process parameter model that can dynamically adjust the power, time parameters and cooling intensity of subsequent heating stations to achieve closed-loop control of temperature and strain.
[0035] By adding an online sensing and closed-loop control system, the entire process is upgraded from "open-loop" experience-based operation to "closed-loop" intelligent control. This system can compensate for interference caused by factors such as fluctuations in material properties and changes in mold status in real time, ensuring process stability and product consistency. This is the core guarantee for achieving high-quality, large-scale production.
[0036] In this embodiment, the eddy current induction coil is a modular contour-following splicing coil, the shape of which matches the outline of the target heating area of the corresponding heating station; for heating areas with complex shapes, it is composed of multiple independent temperature and time-controlled sub-coil units, which can realize differentiated gradient heating of different areas of the same workpiece; it enables the energy of induction heating to be applied precisely and evenly to areas with complex and irregular shapes (such as the root of a protrusion), realizing fine control of heat input in space, which is the key hardware foundation for achieving the expected thermo-mechanical coupling effect.
[0037] In this embodiment, during continuous production, a unique "thermal-mechanical process history file" is generated for each workpiece. This file records the actual temperature-time curves at each heating station, the pressure-displacement curves at each forming station, and online deformation detection data. This file is bound to the workpiece's serial number for quality traceability and process optimization, realizing fully digital recording and traceability of the production process. This not only provides a data foundation for quality control and problem analysis, but also supports the continuous optimization of process parameters through big data accumulation.
[0038] In this embodiment, during the nesting design stage, the method nests the protruding structures and concave contours of adjacent workpieces; the shape and position of the internal separation seam are designed according to the gap between the protrusions and concave contours of adjacent workpieces in the nested nesting, and the gap width is 1.0 to 1.5 times the material thickness, so as to combine material utilization optimization with process feasibility (such as the relationship between gap width and material thickness).
[0039] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A new energy automobile motor cover forming method, a continuous die is used for multi-station stamping, characterized in that, The method includes the following steps performed sequentially: S1. Strip pretreatment: Uncoiling, leveling and cleaning of metal strip; S2. Precision separation by thermal coupling: During the stamping process, the planned internal separation area on the strip is first locally induction heated to a predetermined temperature, and then punched to form an internal separation seam and connecting bridge; subsequently, the connecting bridge area is heated and punched to separate the workpiece blank from the strip. S3, Stepped thermal assisted three-dimensional forming: The predetermined three-dimensional structure area of the separated workpiece blank is locally induction heated to a second predetermined temperature, which is higher than the first predetermined temperature. After heating, the three-dimensional structure is immediately drawn or formed; then the edge area of the workpiece is cooled and the edge structure is cold formed. S4. In-mold stress homogenization and finishing: Apply pressure to the workpiece after step S3 in the mold and hold the pressure, and use the residual heat of the workpiece to relax the in-mold stress. S5. Room temperature finishing and leveling: Under the assistance of micro-area heating at room temperature or a third predetermined temperature, hole punching, final blanking of the shape and three-dimensional leveling are performed.
2. The method for forming a new energy vehicle motor cover plate according to claim 1, characterized in that, In step S2, the first predetermined temperature is set to the temperature at which the material is in the dynamic recovery stage; The first predetermined temperature is 450℃-550℃; The local induction heating is achieved by an eddy current induction coil embedded in the punch or die, and the heating time is controlled between 0.5 seconds and 1.5 seconds.
3. The method for forming a new energy vehicle motor cover plate according to claim 2, characterized in that, In step S3, the second predetermined temperature is set to be close to the material recrystallization temperature or austenitization temperature; The second predetermined temperature is 650℃-720℃; The three-dimensional structure includes multiple parallel protrusions in the middle of the motor end cover, and the heating area precisely covers the root connection area and the protrusion body of the protrusions.
4. The method for forming a new energy vehicle motor cover plate according to claim 3, characterized in that, In step S3, "cooling the edge area of the workpiece" is achieved by using a cooling channel integrated in the mold to circulate a cooling medium, or by using a fixed-point aerosol spray to rapidly cool the annular area that needs to be edge-shaped to below 100°C. Meanwhile, the three-dimensional structure area, due to its large heat capacity, remains at a temperature above 200°C, thus creating a regional temperature difference.
5. The method for forming a new energy vehicle motor cover plate according to claim 4, characterized in that, In step S4, the holding pressure is 1.5 to 2.5 times the material's yield strength, and the holding time is 2 to 5 seconds. During the pressure holding process, the three-dimensional structural region undergoes creep under the combined action of pressure and residual heat, achieving stress relaxation and geometric stability.
6. The method for forming a new energy vehicle motor cover plate according to claim 1, characterized in that, In step S5, before punching the holes and final blanking the shape, pulse induction heating at the third predetermined temperature is applied to the local area of the corresponding punching path. The third predetermined temperature is lower than the first predetermined temperature, specifically 300℃-400℃, and the heating time is less than 0.3 seconds.
7. The method for forming a new energy vehicle motor cover plate according to any one of claims 1 to 6, characterized in that, It also includes step S0, online sensing and closed-loop control: After heating in at least step S2, after heating in step S3, and after step S5, an infrared thermal imager is used to perform non-contact measurement of the workpiece temperature field, and a laser profile scanner is used to detect the deformation of key parts of the workpiece. The measurement data is fed back to the central controller, which has a pre-set process parameter model that can dynamically adjust the power, time parameters and cooling intensity of subsequent heating stations to achieve closed-loop control of temperature and strain.
8. The method for forming a new energy vehicle motor cover plate according to claim 7, characterized in that, The eddy current induction coil is a modular contour-following splicing coil, the shape of which matches the outline of the target heating area of the corresponding heating station. For heating areas with complex shapes, multiple independent temperature and time control sub-coil units are combined to achieve differentiated gradient heating of different areas of the same workpiece.
9. The method for forming a new energy vehicle motor cover plate according to claim 8, characterized in that, During continuous production, a unique "thermal-mechanical process history file" is generated for each workpiece. This file records the actual temperature-time curves at each heating station, the pressure-displacement curves at each forming station, and online deformation detection data. This file is linked to the workpiece's serial number for quality traceability and process optimization.
10. The method for forming a new energy vehicle motor cover plate according to claim 9, characterized in that, In the layout design stage, the method nests the protruding structures and concave contours of adjacent workpieces. The shape and position of the internal separation seam are designed according to the gap between the protrusions and recesses of adjacent workpieces in the nested layout, and the gap width is 1.0 to 1.5 times the material thickness.