Dual-frequency induction heat treatment method and apparatus with movable semi-contour coil

Abstract

This invention provides a dual-frequency induction heat treatment method and apparatus with a movable semi-contour coil, belonging to the field of bevel gear induction heating technology. The specific steps of the heat treatment method are as follows: adjusting the positions of the first-end coil and the second-end coil to perform induction heating and temperature monitoring on the bevel gear teeth; sequentially performing induction heating on the tooth tip at the first end and the tooth root at the second end of the tooth, performing induction heating on the tooth root at the first end and the tooth tip at the second end of the tooth, and performing induction heating on the tooth root and tooth tip in the middle of the tooth; performing tempering treatment on the bevel gear teeth; and performing stress detection on the bevel gear teeth. The heat treatment apparatus includes a base, a rotating table, a laser ultrasonic stress detector, a cooling nozzle, an induction tempering assembly, an induction heating assembly, a thermometer, a moving platform, and a vision camera. This invention combines the heating characteristics of high-frequency power supplies and uses a method of mutual heating of two coils to achieve uniform heating of the bevel gear tooth tip and tooth root.

Description

Technical Field

[0001] This invention relates to the field of bevel gear induction heating technology, and in particular to a dual-frequency induction heat treatment method and apparatus with a movable semi-contour coil. Background Technology

[0002] Bevel gears are crucial components in transmission systems. Complex operating conditions and high load-bearing requirements place higher demands on their quality and reliability. To improve bevel gear quality and service life, a key research focus has emerged: developing surface heat treatment technologies that achieve a deep, uniformly distributed hardened layer along the tooth profile while maintaining core toughness and reducing stress concentration.

[0003] Compared to traditional carburizing strengthening processes, induction heat treatment has advantages such as low cost, minimal deformation, and ease of automated production. However, due to the complex surface geometry of bevel gears, which includes concave and convex surfaces, if only one type of coil is used for single-frequency induction heating of the bevel gear, high-frequency induction heating will result in hardening of the tooth tip due to the skin effect and sharp corner effect, while insufficient hardening of the tooth root; medium-frequency induction heating will result in complete hardening of the tooth root, while insufficient hardening of the tooth tip.

[0004] In recent years, "synchronous dual-frequency induction heating equipment" can simultaneously input high-frequency and medium-frequency currents onto a single induction coil. However, bevel gears have a unique geometric structure, making this single-coil dual-frequency heating method ineffective. Currently, asynchronous dual-frequency induction heating is relatively low-cost and achieves the same effect as synchronous dual-frequency induction heating. However, due to the unique geometric structure of bevel gear teeth, it is often necessary to customize a tooth-shaped 3D induction coil based on the specific parameters of the bevel gear. Furthermore, as the module increases, the gradient of the single coil's cross-sectional area becomes too large, and it is limited by the internal cooling water channel structure. Neither synchronous nor asynchronous dual-frequency induction heating can solve the problem of a large temperature difference between the second and first ends in the tooth profile direction.

[0005] Therefore, there is an urgent need for a method and apparatus for dual-frequency induction heat treatment of bevel gears with a movable semi-contour coil. This method utilizes asynchronous dual-frequency induction heating, switching frequencies and adjusting the coil positions at the first and second ends of the gear teeth to achieve uniform temperature treatment along the tooth profile and tooth width directions. In this paper, the first end of the gear teeth refers to the small gear end of the bevel gear, and the second end refers to the large gear end. Summary of the Invention

[0006] To address the problems of existing technologies, this invention provides a dual-frequency induction heat treatment method and apparatus with a movable semi-contour coil. It acquires positional information of the first and second end coils using a vision camera and temperature information of the teeth on the bevel gear using a thermometer, thereby adjusting the positional relationship between the first and second end coils and the bevel gear teeth to achieve uniform surface temperature of the bevel gear. Furthermore, it utilizes the stress distribution on the bevel gear teeth detected by a laser ultrasonic stress detector to perform tempering treatment and overall stress re-inspection of the bevel gear. This solves the problems of uneven heating at the large first end of the bevel gear and the excessively long heating time required by multiple iterations in the asynchronous dual-frequency heating method, resulting in higher production efficiency and potential market value.

[0007] This invention provides a dual-frequency induction heat treatment method with a movable semi-contour coil, the specific implementation steps of which are as follows:

[0008] S1. Adjust the positions of the first and second coils respectively;

[0009] S2. Induction heating and temperature monitoring of the bevel gear teeth:

[0010] S21. Set the initial parameters for induction heating temperature, heating time, and power supply, and mark the first end, middle part, and second end of the gear teeth at different positions on adjacent tooth tips and roots.

[0011] S22. Induction heating is applied to the tooth tip at the first end of the gear teeth and the tooth root at the second end of the gear teeth:

[0012] S221. The first end coil is moved into the working position of the first end of the gear tooth and the second end coil is moved into the working position of the second end of the gear tooth by the lifting moving platform and the horizontal moving platform respectively, and the first end power supply is connected to the high frequency power supply and the second end power supply is connected to the medium frequency power supply.

[0013] S222. After heating the tooth tip at the first end of the gear tooth for a period of time, the tooth tip temperature TA1 at the first end of the gear tooth is obtained by a temperature measuring instrument. If TA1 is less than TA-T1, heating continues [(TA-T1-TA1) / T1]*t0; if TA1 is greater than TA+T1, the first end coil is moved out of the working position by the lifting and lateral moving platform and cooled {[(TA1-TA-T1) / T1]*t1; if TA1 is greater than or equal to TA-T1 and less than or equal to TA+T1, the tooth tip at the first end of the gear tooth meets the heating requirement, and the first end coil is moved out of the working position by the lifting and lateral moving platform; where TA is the target heating temperature of the first end of the gear tooth in the bevel gear, T1 is the allowable temperature difference of the tooth tip of the bevel gear, and t0 and t1 are both unit heating time;

[0014] S223. After heating the tooth root at the second end of the gear tooth for a period of time, the tooth root temperature TC2 at the second end of the gear tooth is obtained by a thermometer. If TC2 is less than TC-T2, heating continues [(TC-T2-TC2) / T2]*t0; if TC2 is greater than TC+T2, the second end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TC2-TC-T2) / T2]*t1; if TC2 is greater than or equal to TC-T2 and less than or equal to TC+T2, the tooth root at the second end of the gear tooth meets the heating requirements, and the second end coil is moved out of the working position by the lifting and lateral moving platform; where TC is the target heating temperature of the second end of the gear tooth in the bevel gear, and T2 is the allowable temperature difference of the tooth root of the bevel gear.

[0015] S23. Induction heating is applied to the root of the first end of the gear teeth and the tip of the second end of the gear teeth:

[0016] S24. Induction heating is applied to the tooth root and tooth tip at the middle of the gear teeth:

[0017] S25. The rotating table drives the bevel gear to rotate, and the cooling nozzle is used to cool the gear teeth after induction heating in steps S22 to S24. Steps S21 to S24 are repeated to induction heat the next gear tooth until all gear teeth of the bevel gear are induction heated.

[0018] S3. Temper the teeth of the bevel gear obtained in step S2:

[0019] S31. The stress distribution value of the bevel gear teeth is measured using a laser ultrasonic stress detector. If the maximum stress value Fmax of the teeth is greater than the ultimate stress value Fx of the teeth or the stress difference ΔF of the teeth is greater than the ultimate stress difference ΔFx of the teeth, then the temperature difference between the heating target temperatures of the first end, the middle part, and the second end of the teeth in step S21 is reduced respectively, and step S2 is repeated to perform induction heating on the teeth again. If the maximum stress value Fmax of the teeth is less than or equal to the ultimate stress value Fx of the teeth and the stress difference ΔF of the teeth is less than or equal to the ultimate stress difference ΔFx of the teeth, then step S32 is performed, where ΔF = Fmax - Fmin, and Fmin is the minimum stress value of the teeth.

[0020] S32. A medium-frequency power supply is supplied to the tempering power supply in the induction tempering assembly, and the teeth of the bevel gear are tempered and heated by the tempering coil. The expression for the energizing time of the tempering coil is:

[0021]

[0022] Where [F] is the allowable stress, [ΔF] is the allowable stress difference, and m1, m2, m3, m4 and m5 are the gradient energizing times, respectively;

[0023] S33. The rotating table drives the bevel gear to rotate. Repeat steps S31 to S32 until the tempering of all the teeth of the bevel gear is completed.

[0024] S4. Perform stress testing on the teeth of the bevel gear obtained in step S3.

[0025] Preferably, the specific implementation steps of step S1 include:

[0026] S11. Calculate the height of the bevel gear based on its shape parameters.

[0027] S12. Based on the power frequencies of the high-frequency power supply and the medium-frequency power supply, as well as the material of the bevel gear, the induction heating depths of the first end coil and the second end coil are obtained respectively.

[0028] S13. Based on the induction heating depth obtained in step S12, and using the position information obtained by the vision camera, the distance d between the first end coil and the second end coil and the bevel gear teeth is set by the lifting moving platform and the horizontal moving platform, respectively.

[0029] Preferably, in step S21, the initial parameters of the power supply include the frequency f1 of the intermediate frequency power supply of the induction heating component, the frequency f2 of the high frequency power supply of the induction heating component, the power P1 of the intermediate frequency power supply of the induction heating component, the power P2 of the high frequency power supply of the induction heating component, and the power PH of the intermediate frequency power supply of the induction tempering component; in step S33, the power PH of the intermediate frequency power supply of the induction tempering component is less than the power P1 of the intermediate frequency power supply of the induction heating component.

[0030] Preferably, the specific implementation steps of step S23 include:

[0031] S231. The first coil is moved into the working position at the first end of the gear tooth and the second coil is moved into the working position at the second end of the gear tooth by the lifting moving platform and the horizontal moving platform respectively, and the first power supply is connected to the intermediate frequency power supply and the second power supply is connected to the high frequency power supply.

[0032] S232. After heating the tooth root at the first end of the gear tooth for a period of time, the tooth root temperature TA2 at the first end of the gear tooth is obtained by a thermometer. If TA2 is less than TA-T2, heating continues [(TA-T2-TA2) / T2]*t0; if TA2 is greater than TA+T2, the first end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TA2-TA-T2) / T2]*t1; if TA2 is greater than or equal to TA-T2 and less than or equal to TA+T2, the tooth tip at the first end of the gear tooth meets the heating requirements, and the first end coil is moved out of the working position by the lifting and lateral moving platform.

[0033] S233. After heating the tooth tip at the second end of the gear tooth for a period of time, the root temperature TC1 at the second end of the gear tooth is obtained by a thermometer. If TC1 is less than TC-T1, heating continues [(TC-T1-TC1) / T1]*t0; if TC1 is greater than TC+T1, the second end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TC1-TC-T1) / T1]*t1; if TC1 is greater than or equal to TC-T1 and less than or equal to TC+T1, the tooth tip at the second end of the gear tooth meets the heating requirements, and the second end coil is moved out of the working position by the lifting and lateral moving platform.

[0034] Preferably, the specific implementation steps of step S24 include:

[0035] S241. Move the first end coil into the tooth root working position in the middle of the gear tooth by means of the lifting and lateral moving platform and the horizontal moving platform, and connect the first end power supply and the intermediate frequency power supply.

[0036] S242. After heating the tooth root at the middle of the gear teeth for a certain period of time, the tooth root temperature TB2 at the middle of the gear teeth is obtained by a thermometer. If TB2 is less than TB-T2, the power of the intermediate frequency power supply is adjusted to P1+K*P0, and heating continues [(TB-T2-TB2) / T2]*t0; if TB2 is greater than TB+T2, the power of the intermediate frequency power supply is adjusted to P1-K*P0, and the first end coil is moved out of the working position by the lifting and lateral moving platform to cool [(TB2-TB-T2) / T2]*t1; if TB2 is greater than or equal to TB-T2 and less than or equal to TB+T2, the tooth root at the middle of the gear teeth meets the heating requirements, and the first end coil is moved out of the working position by the lifting and lateral moving platform. Here, TB is the target heating temperature of the middle of the gear teeth in the bevel gear, and K is the power coefficient.

[0037] S243. Move the second-end coil into the tooth tip working position in the middle of the gear tooth by using the lifting and lateral moving platform and the horizontal moving platform, and connect the second-end power supply and the high-frequency power supply.

[0038] S244. After heating the tooth tip at the middle of the gear teeth for a certain period of time, the tooth tip temperature TB1 at the middle of the gear teeth is obtained by a thermometer. If TB1 is less than TB-T1, the power of the high-frequency power supply is adjusted to P2+K*P0, and heating continues [(TB-T1-TB1) / T1]*t0; if TB1 is greater than TB+T1, the power of the high-frequency power supply is adjusted to P2-K*P0, and the second end coil is moved out of the working position by the lifting and lateral moving platform to cool [(TB1-TB-T1) / T1]*t1; if TB1 is greater than or equal to TB-T1 and less than or equal to TB+T1, the tooth tip at the middle of the gear teeth meets the heating requirements, and the second end coil is moved out of the working position by the lifting and lateral moving platform.

[0039] Preferably, in step S25, the rotating platform rotates by an angle α = 2π / z each time, where z is the number of teeth of the bevel gear.

[0040] Preferably, the specific implementation steps of step S4 are as follows: the bevel gear obtained in step S3 is rotated one revolution using a rotating table, and the stress distribution of the bevel gear is detected by a laser ultrasonic stress detector. If the maximum stress value Fmax of the bevel gear is less than the ultimate stress value Fx of the bevel gear, and the stress difference ΔF of the bevel gear is less than or equal to the ultimate stress difference ΔFx of the bevel gear, then the induction heat treatment of the bevel gear ends. If the maximum stress value Fmax of the bevel gear is greater than or equal to the ultimate stress value Fx of the bevel gear, or the stress difference ΔF of the bevel gear is greater than the ultimate stress difference ΔFx of the bevel gear, then the power of the tempering power supply is adjusted to PH+P0, and step S32 is repeated until the stress distribution value of the bevel gear teeth meets the requirements, and the induction heat treatment ends. Wherein, P0 is the unit power supply power.

[0041] In another aspect, the present invention provides a dual-frequency induction heat treatment device with a movable semi-contour coil, comprising a base, a rotating platform, a laser ultrasonic stress detector, a cooling nozzle, an induction tempering assembly, an induction heating assembly, a thermometer, a lateral moving platform, a lifting moving platform, a vision camera, and a support. The rotating platform is located in the middle of the base. The laser ultrasonic stress detector, the cooling nozzle, and the induction tempering assembly are respectively connected to a first mounting end, a second mounting end, and a third mounting end of the base in the circumferential direction. The first end coil and the second end coil of the induction heating assembly are located at a fourth mounting end of the base. The thermometer is symmetrically distributed on both sides of the induction heating assembly. The mounting end of the induction heating assembly is connected to the first end of the lateral moving platform. The lateral moving platform is symmetrically distributed at both ends of the lifting moving platform. The top of the lifting moving platform is connected to the first end of the support, and the second end of the support is connected to the vision camera.

[0042] Preferably, the induction tempering assembly includes a tempering bracket, a tempering power supply, and a tempering coil. The bottom of the tempering bracket is connected to the third mounting end of the base, the top of the tempering bracket is connected to the fixed end of the tempering power supply, and the output end of the tempering power supply is connected to the tempering coil. The induction heating assembly includes a first-end power supply, a second-end power supply, a first-end coil, and a second-end coil. The output end of the first-end power supply is connected to the first-end coil, the output end of the second-end power supply is connected to the second-end coil, the second-end coil is located below the first-end coil, and the fixed ends of the first-end power supply and the second-end power supply are respectively connected to the first ends of the transverse moving platform symmetrically distributed at both ends of the lifting moving platform.

[0043] Preferably, the outer shape of the second end coil and the first end coil respectively conforms to the outer contour of a bevel gear.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] 1. This invention proposes a segmented, synchronous dual-frequency heating method for heating bevel gears, taking into account the structural characteristics of large-module bevel gears. By combining the heating characteristics of high-frequency and medium-frequency power supplies, the high-frequency and medium-frequency power supplies are switched at the first and second power supply terminals, respectively, to achieve uniform heating of the large-module bevel gears at the tooth tip and tooth root, thus providing a fundamental guarantee for the uniform distribution of tooth hardness.

[0046] 2. This invention utilizes the principle that different frequencies of current heat different depths, employing two dynamic coils working together to heat the gear. By switching between different power sources and relying on real-time temperature data from a temperature sensor, the invention ensures uniform temperature of the bevel gear and achieves controllable induction heating. Simultaneously, the bevel gear is heated at both high and medium frequencies along its tooth profile (from the tooth tip to the tooth root). This controls the dynamic coordination of coils at different positions on the bevel gear, enabling synchronous heating of the bevel gear by both high-frequency and medium-frequency power sources, resulting in high production efficiency.

[0047] 3. This invention performs induction tempering treatment and overall stress re-inspection on bevel gears, detects the stress distribution of bevel gears after cooling, sets allowable stress and allowable stress difference, improves the strength and stability of bevel gears, and ensures the performance and service life of bevel gears. Attached Figure Description

[0048] Figure 1 This is a flowchart of the dual-frequency induction heat treatment method with a movable semi-contour coil according to the present invention.

[0049] Figure 2 This is a flowchart of the induction heating temperature control method in the dual-frequency induction heat treatment method with a movable semi-contour coil of the present invention.

[0050] Figure 3 This is an overall structural diagram of the dual-frequency induction heat treatment device with a movable semi-contour coil according to the present invention.

[0051] Figure 4 This is a first partial structural diagram of the dual-frequency induction heat treatment device with a movable semi-contour coil of the present invention.

[0052] Figure 5 This is a second partial structural diagram of the dual-frequency induction heat treatment device with a movable semi-contour coil of the present invention.

[0053] Figure 6 This is a working position diagram of the first end coil and the second end coil in the dual-frequency induction heat treatment device with movable semi-contour coil of the present invention.

[0054] Figure 7 This is a diagram showing the removal of the first and second end coils in the dual-frequency induction heat treatment method with a movable semi-contour coil of the present invention.

[0055] Figure 8 This is a simulation result diagram of the heating bevel gear in the dual-frequency induction heat treatment method with movable semi-contour coil of the present invention.

[0056] Key reference numerals:

[0057] 1. Base, 2. Rotating platform, 3. Bevel gear, 4. Laser ultrasonic stress detector, 5. Cooling nozzle, 6. Induction tempering assembly, 601. Tempering bracket, 602. Tempering power supply, 603. Tempering coil, 7. Induction heating assembly, 701. First end power supply, 702. Second end power supply, 703. Second end coil, 704. Temperature measuring instrument, 8. Lateral moving platform, 9. Lifting moving platform, 10. Vision camera, 11. Bracket, 12. Gear tooth first end A, gear tooth middle B, gear tooth second end C. Detailed Implementation

[0058] To fully describe the technical content, structural features, objectives, and effects of this invention, a detailed description will be provided below in conjunction with the accompanying drawings.

[0059] A dual-frequency induction heat treatment method with a movable semi-contour coil is implemented as follows: Figure 1 As shown.

[0060] S1. Adjust the positions of the first coil 702 and the second coil 704 respectively.

[0061] S2. Induction heating and temperature monitoring are performed on the teeth of bevel gear 3.

[0062] S3. Temper the teeth of the bevel gear 3 obtained in step S2.

[0063] S4. Perform stress testing on the teeth of the bevel gear 3 obtained in step S3.

[0064] Furthermore, the specific implementation steps for adjusting the positions of the first coil 702 and the second coil 704 in step S1 include:

[0065] S11. Calculate the height of the bevel gear 3 based on its shape parameters.

[0066] S12. Based on the power frequencies of the high-frequency power supply and the medium-frequency power supply, and the material of the bevel gear 3, the induction heating depths of the first end coil 702 and the second end coil 704 are obtained respectively.

[0067] S13. Based on the induction heating depth obtained in step S12, the position information of the first end coil 702 and the second end coil 704 is obtained by using the vision camera 11. The distance d between the first end coil 702 and the second end coil 704 and the teeth of the bevel gear 3 is set by the lifting moving platform 10 and the horizontal moving platform 9 respectively.

[0068] Furthermore, such as Figure 2 As shown, the specific process of induction heating and temperature monitoring of the teeth of the bevel gear 3 in step S2 includes:

[0069] S21. Set the initial parameters for induction heating temperature, heating time, and power supply, and mark the first end A, the middle part B, and the second end C of the gear teeth at different positions on adjacent tooth tips and roots of the bevel gear 3.

[0070] Specifically, the initial parameters of the power supply include the frequency f1 of the intermediate frequency power supply of the induction heating component 7, the frequency f2 of the high frequency power supply of the induction heating component 7, the power P1 of the intermediate frequency power supply of the induction heating component 7, the power P2 of the high frequency power supply of the induction heating component 7, and the power PH of the intermediate frequency power supply of the induction tempering component 6.

[0071] S22. Induction heating is applied to the tooth tip at the first end A and the tooth root at the second end C of the gear tooth.

[0072] S221, such as Figure 6 As shown, the first end coil 702 is moved into the working position of the first end A of the gear tooth and the second end coil 704 is moved into the working position of the second end C of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9 respectively. The first end power supply 701 is connected to the high frequency power supply and the second end power supply 703 is connected to the medium frequency power supply.

[0073] S222. After heating the tooth tip at the first end A of the gear tooth for a period of time, the tooth tip temperature TA1 at the first end A of the gear tooth is obtained by the temperature measuring instrument 8. If TA1 is less than (TA-T1, where TA is the target heating temperature of the first end A of the gear tooth in the bevel gear 3, and T1 is the allowable temperature difference of the tooth tip of the bevel gear 3), then heating continues {[(TA-T1-TA1) / T1]*t0, where t0 is the unit heating time}; if TA1 is greater than (TA+T1), then the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9, and cooled {[(TA1-TA-T1) / T1]*t1, where t1 is the unit cooling time}; if TA1 is greater than or equal to (TA-T1) and less than or equal to (TA+T1), then the tooth tip at the first end A of the gear tooth meets the heating requirement, and the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9. Figure 7 As shown.

[0074] S223. After heating the tooth root at the second end C of the gear tooth for a period of time, the tooth root temperature TC2 at the second end C of the gear tooth is obtained by the temperature measuring instrument 8. If TC2 is less than (TC-T2, where TC is the heating target temperature of the second end C of the gear tooth in the bevel gear, and T2 is the allowable temperature difference of the tooth root of the bevel gear), then heating continues {[(TC-T2-TC2) / T2]*t0, where t0 is the unit heating time}; if TC2 is greater than (TC+T2), then the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9, and cooled {[(TC2-TC-T2) / T2]*t1, where t1 is the unit cooling time}; if TC2 is greater than or equal to (TC-T2) and less than or equal to (TC+T2), then the tooth root at the second end C of the gear tooth meets the heating requirements, and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0075] S23. Induction heating is applied to the root of the tooth at the first end A and the tip of the tooth at the second end C.

[0076] S231. The first end coil 702 is moved into the working position of the first end A of the gear tooth and the second end coil 704 is moved into the working position of the second end C of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9 respectively. The first end power supply 701 is connected to the intermediate frequency power supply and the second end power supply 703 is connected to the high frequency power supply.

[0077] S232. After heating the tooth root at the first end A of the gear tooth for a period of time, the temperature of the tooth root at the first end A of the gear tooth is obtained by the temperature measuring instrument 8 as TA2. If TA2 is less than (TA-T2, where TA is the heating target temperature of the first end A of the gear tooth in the bevel gear 3, and T2 is the allowable temperature difference of the tooth root of the bevel gear 3), then heating continues {[(TA-T2-TA2) / T2]*t0, where t0 is the unit heating time}; if TA2 is greater than (TA+T2), then the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the transverse moving platform 9, and cooled {[(TA2-TA-T2) / T2]*t1, where t1 is the unit cooling time}; if TA2 is greater than or equal to (TA-T2) and less than or equal to (TA+T2), then the tooth tip at the first end A of the gear tooth meets the heating requirements, and the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the transverse moving platform 9.

[0078] S233. After heating the tooth tip at the second end C of the gear tooth for a period of time, the root temperature TC1 at the second end C of the gear tooth is obtained by the temperature measuring instrument 8. If TC1 is less than (TC-T1, where TC is the target heating temperature of the second end C of the gear tooth in the bevel gear 3, and T1 is the allowable temperature difference of the tooth tip of the bevel gear 3), then heating continues {[(TC-T1-TC1) / T1]*t0, where t0 is the unit heating time}. If TC1 is greater than (TC+T1), then the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9, and cooled {[(TC1-TC-T1) / T1]*t1, where t1 is the unit cooling time}. If TC1 is greater than or equal to (TC-T1) and less than or equal to (TC+T1), then the tooth tip at the second end C of the gear tooth meets the heating requirements, and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0079] S24. Induction heating is applied to the tooth root and tooth tip at point B in the middle of the gear teeth.

[0080] S241. The first end coil 702 is moved into the tooth root working position at the middle B of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9, and the first end power supply 701 and the intermediate frequency power supply are connected.

[0081] S242. After heating the tooth root at point B in the middle of the gear tooth for a certain period of time, the temperature of the tooth root at point B in the middle of the gear tooth is obtained by the thermometer 8 as TB2. If TB2 is less than (TB-T2, where TB is the target heating temperature of point B in the middle of the gear tooth in bevel gear 3, and T2 is the allowable temperature difference of the tooth root of bevel gear 3), then the power of the intermediate frequency power supply is adjusted to (P1+K*P0, where K is the power coefficient), and heating continues to {[(TB-T2-TB2) / T2]*t0, where t0 is the unit heating time}; if TB2 is greater than (TB+T2), then the power of the intermediate frequency power supply is adjusted to (P1+K*P0, where K is the power coefficient), and heating continues to {[(TB-T2-TB2) / T2]*t0, where t0 is the unit heating time}. When the frequency is adjusted to (P1-K*P0, where K is the power coefficient), the first coil 702 is moved out of the working position by the lifting platform 10 and the horizontal moving platform 9 to cool {[(TB2-TB-T2) / T2]*t1, where t1 is the unit cooling time}; if TB2 is greater than or equal to (TB-T2) and less than or equal to (TB+T2), the tooth root at the middle B of the gear tooth meets the heating requirement, and the first coil 702 is moved out of the working position by the lifting platform 10 and the horizontal moving platform 9.

[0082] S243. The second-end coil 704 is moved into the tooth tip working position at the middle B of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9, and the second-end power supply 703 is connected to the high-frequency power supply.

[0083] S244. After heating the tooth tip at point B in the middle of the gear teeth for a certain period of time, the temperature of the tooth tip at point B in the middle of the gear teeth is obtained by the thermometer 8 as TB1. If TB1 is less than (TB-T1, where TB is the target heating temperature of point B in the middle of the gear teeth in bevel gear 3, and T1 is the allowable temperature difference of the tooth tip of bevel gear 3), then the power of the high-frequency power supply is adjusted to (P2+K*P0, where K is the power coefficient), and heating continues to {[(TB-T1-TB1) / T1]*t0, where t0 is the unit heating time}; if TB1 is greater than (TB+T1), then the power of the high-frequency power supply is adjusted to (P2+K*P0, where K is the power coefficient), and heating continues to {[(TB-T1-TB1) / T1]*t0, where t0 is the unit heating time}. When the high-frequency power supply is adjusted to (P2-K*P0, where K is the power coefficient), the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9, and cooled {[(TB1-TB-T1) / T1]*t1, where t1 is the unit cooling time}; if TB1 is greater than or equal to (TB-T1) and less than or equal to (TB+T1), the tooth tip at the middle B of the gear tooth meets the heating requirement, and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0084] S25. The rotating table 2 drives the bevel gear 3 to rotate, and the cooling nozzle 5 is used to cool the gear teeth after induction heating. Steps S21 to S24 are repeated to induction heat the next gear tooth until all the gear teeth of the bevel gear 3 are induction heated.

[0085] Specifically, the rotating platform 2 rotates by an angle α = 2π / z each time, where z is the number of teeth of the bevel gear 3.

[0086] Furthermore, the specific implementation process of tempering the teeth of the bevel gear 3 in step S3 is as follows:

[0087] S31. The stress distribution value of the teeth of the bevel gear 3 is measured using the laser ultrasonic stress detector 4. If the maximum stress value Fmax of the teeth is greater than the ultimate stress value Fx of the teeth, or the stress difference of the teeth (ΔF = Fmax - Fmin, where Fmin is the minimum stress value of the teeth) is greater than the ultimate stress difference ΔFx of the teeth, then the temperature difference between the heating target temperatures of the first end A, the middle part B, and the second end C of the teeth in step S21 is reduced respectively, and step S2 is repeated to perform induction heating on the teeth again; if the maximum stress value Fmax of the teeth is less than or equal to the ultimate stress value Fx of the teeth and the stress difference ΔF of the teeth is less than or equal to the ultimate stress difference ΔFx of the teeth, then step S32 is performed.

[0088] S32. A medium-frequency power supply is supplied to the tempering power supply 602 in the induction tempering assembly 6, thereby using the tempering coil 603 to temper and heat the teeth of the bevel gear 3. The expression for the energizing time of the tempering coil 603 is as follows:

[0089]

[0090] Wherein, [F] is the allowable stress, [ΔF] is the allowable stress difference, and m1, m2, m3, m4 and m5 are the gradient energizing times. In a preferred embodiment of the present invention, m1 is set to 6 seconds, and m1 to m5 are incremented by 3 seconds at intervals. The values ​​can be adjusted according to the material and shape of the actual bevel gear 3.

[0091] Specifically, the power PH of the medium-frequency power supply in the induction tempering assembly 6 is less than the power P1 of the medium-frequency power supply in the induction heating assembly 7.

[0092] S33. The rotating table 2 drives the bevel gear 3 to rotate, and steps S31 to S32 are repeated until the tempering of all the teeth of the bevel gear 3 is completed.

[0093] Furthermore, the specific steps for stress detection of the bevel gear 3 obtained in step S3 in step S4 are as follows: the bevel gear 3 obtained in step S3 is rotated one revolution using the rotating table 2, and the stress distribution of the bevel gear 3 is detected by the laser ultrasonic stress detector 4. If the maximum stress value Fmax of the bevel gear 3 is less than the ultimate stress value Fx of the bevel gear 3, and the stress difference ΔF of the bevel gear 3 is less than or equal to the ultimate stress difference ΔFx of the bevel gear 3, then the induction heat treatment of the bevel gear 3 ends. If the maximum stress value Fmax of the bevel gear 3 is greater than or equal to the ultimate stress value Fx of the bevel gear 3, or the stress difference ΔF of the bevel gear 3 is greater than the ultimate stress difference ΔFx of the bevel gear 3, then the power of the tempering power supply 602 is adjusted to (PH+P0, where P0 is the unit power supply), and step S32 is repeated until the stress distribution value of the bevel gear 3 teeth meets the requirements, and the induction heat treatment ends.

[0094] A dual-frequency induction heat treatment device with a movable semi-contour coil, such as Figure 3 As shown, the system includes a base 1, a rotating platform 2, a laser ultrasonic stress detector 4, a cooling nozzle 5, an induction tempering assembly 6, an induction heating assembly 7, a thermometer 8, a horizontal moving platform 9, a lifting moving platform 10, a vision camera 11, and a bracket 12. The rotating platform 2 is located in the middle of the base 1, and its mounting end is connected to a bevel gear 3. The laser ultrasonic stress detector 4, the cooling nozzle 5, and the induction tempering assembly 6 are respectively connected to the first, second, and third mounting ends of the base 1 in the circumferential direction. The first end coil 702 and the second end coil 704 of the induction heating assembly 7 are located at the fourth mounting end of the base 1. The thermometers 8 are symmetrically distributed on the induction heating assembly 7. On both sides, the mounting end of the induction heating component 7 is connected to the first end of the transverse moving platform 9. The transverse moving platform 9 is symmetrically distributed at both ends of the lifting moving platform 10. The lifting moving platform 10 and the transverse moving platform 9 drive the high-frequency power supply and the medium-frequency power supply to move, thereby realizing the movement of the first end coil 702 and the second end coil 704 along the tooth profile of the bevel gear 3. The top of the lifting moving platform 10 is connected to the first end of the bracket 12. The second end of the bracket 12 is connected to the vision camera 11. The vision camera 11 acquires position images of the first end coil 702 and the second end coil 704 to adjust the distance between the first end coil 702 and the second end coil 704 and the teeth of the bevel gear 3.

[0095] Induction tempering assembly 6, such as Figure 5 As shown, it includes a tempering bracket 601, a tempering power supply 602, and a tempering coil 603. The bottom of the tempering bracket 601 is connected to the third mounting end of the base 1, the top of the tempering bracket 601 is connected to the fixed end of the tempering power supply 602, and the output end of the tempering power supply 602 is connected to the tempering coil 603.

[0096] Induction heating component 7, such as Figure 4As shown, it includes a first-end power supply 701, a second-end power supply 703, a first-end coil 702, and a second-end coil 704. The output end of the first-end power supply 701 is connected to the first-end coil 702, and the output end of the second-end power supply 703 is connected to the second-end coil 704. The second-end coil 704 is located below the first-end coil 702. The fixed ends of the first-end power supply 701 and the second-end power supply 703 are respectively connected to the first end of the transverse moving platform 9, which is symmetrically distributed at both ends of the lifting moving platform 10.

[0097] The external structures of the second end coil 704 and the first end coil 702 respectively conform to the external contour of the bevel gear 3. Furthermore, in a preferred embodiment of the present invention, considering factors such as power load, the intermediate frequency power supply and the high frequency power supply can only load a single coil. Therefore, the second end power supply 703 and the first end power supply 701 are interleaved with the intermediate frequency power supply and the high frequency power supply. Simultaneously, the working positions of the first end coil 702 and the second end coil 704 are not fixed. The first end coil 702 and the second end coil 704 reciprocate along the tooth profile direction, thereby heating different areas of the bevel gear 3 to increase the heating range of the first end coil 702 and the second end coil 704.

[0098] The following describes in further detail a dual-frequency induction heat treatment method and apparatus with a movable semi-contour coil according to the present invention, with reference to embodiments:

[0099] S1. Adjust the positions of the first coil 702 and the second coil 704 respectively:

[0100] S11. Calculate the height of the bevel gear 3 based on its shape parameters.

[0101] S12. Based on the power frequencies of the high-frequency power supply and the medium-frequency power supply, and the material of the bevel gear 3, the induction heating depths of the first end coil 702 and the second end coil 704 are obtained respectively.

[0102] S13. Based on the induction heating depth obtained in step S12, the position information of the first end coil 702 and the second end coil 704 is obtained by using the vision camera 11. The distance d between the first end coil 702 and the second end coil 704 and the teeth of the bevel gear 3 is set by the lifting moving platform 10 and the horizontal moving platform 9 respectively.

[0103] S2. Induction heating and temperature monitoring of the teeth of bevel gear 3:

[0104] S21. Set the induction heating temperature, heating time, frequency f1 of the medium frequency power supply in the induction heating component 7, frequency f2 of the high frequency power supply in the induction heating component 7, power P1 of the medium frequency power supply in the induction heating component 7, power P2 of the high frequency power supply in the induction heating component 7, and power PH of the medium frequency power supply in the induction tempering component 6. Mark the first end A, the middle part B, and the second end C of the gear teeth at different positions of adjacent tooth tips and tooth roots on the bevel gear 3, respectively.

[0105] S22. Induction heating is applied to the tooth tip at the first end A and the tooth root at the second end C of the gear tooth.

[0106] S221, such as Figure 6 As shown, the first end coil 702 is moved into the working position of the first end A of the gear tooth and the second end coil 704 is moved into the working position of the second end C of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9 respectively. The first end power supply 701 is connected to the high frequency power supply and the second end power supply 703 is connected to the medium frequency power supply.

[0107] S222. After heating the tooth tip at the first end A of the gear tooth for a period of time, the tooth tip temperature TA1 at the first end A of the gear tooth is obtained by the temperature measuring instrument 8. If TA1 is less than (TA-T1), heating continues {[(TA-T1-TA1) / T1]*t0}; if TA1 is greater than (TA+T1), the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9, and cooled {[(TA1-TA-T1) / T1]*t1}; if TA1 is greater than or equal to (TA-T1) and less than or equal to (TA+T1), the tooth tip at the first end A of the gear tooth meets the heating requirement, and the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9. Figure 7 As shown.

[0108] S223. After heating the tooth root at the second end C of the gear tooth for a period of time, the tooth root temperature TC2 at the second end C of the gear tooth is obtained by the temperature measuring instrument 8. If TC2 is less than (TC-T2), then heating continues {[(TC-T2-TC2) / T2]*t0}; if TC2 is greater than (TC+T2), then the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9 and cooled {[(TC2-TC-T2) / T2]*t1}; if TC2 is greater than or equal to (TC-T2) and less than or equal to (TC+T2), then the tooth root at the second end C of the gear tooth meets the heating requirements, and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0109] S23. Induction heating is applied to the root of the tooth at the first end A and the tip of the tooth at the second end C.

[0110] S231. The first end coil 702 is moved into the working position of the first end A of the gear tooth and the second end coil 704 is moved into the working position of the second end C of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9 respectively. The first end power supply 701 is connected to the intermediate frequency power supply and the second end power supply 703 is connected to the high frequency power supply.

[0111] S232. After heating the tooth root at the first end A of the gear tooth for a period of time, the temperature of the tooth root at the first end A of the gear tooth is obtained by the temperature measuring instrument 8 as TA2. If TA2 is less than (TA-T2), then heating continues {[(TA-T2-TA2) / T2]*t0}; if TA2 is greater than (TA+T2), then the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9, and cooled {[(TA2-TA-T2) / T2]*t1}; if TA2 is greater than or equal to (TA-T2) and less than or equal to (TA+T2), then the tooth tip at the first end A of the gear tooth meets the heating requirements, and the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0112] S233. After heating the tooth tip at the second end C of the gear tooth for a period of time, the root temperature TC1 at the second end C of the gear tooth is obtained by the temperature measuring instrument 8. If TC1 is less than (TC-T1), heating continues {[(TC-T1-TC1) / T1]*t0}; if TC1 is greater than (TC+T1), the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9 and cooled {[(TC1-TC-T1) / T1]*t1}; if TC1 is greater than or equal to (TC-T1) and less than or equal to (TC+T1), the tooth tip at the second end C of the gear tooth meets the heating requirements, and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0113] S24. Induction heating is applied to the tooth root and tooth tip at point B in the middle of the gear teeth.

[0114] S241. The first end coil 702 is moved into the tooth root working position at the middle B of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9, and the first end power supply 701 and the intermediate frequency power supply are connected.

[0115] S242. After heating the tooth root at the middle B of the gear tooth for a certain period of time, the temperature of the tooth root at the middle B of the gear tooth is obtained by the temperature measuring instrument 8 as TB2. If TB2 is less than (TB-T2), the power of the intermediate frequency power supply is adjusted to (P1+K*P0), and heating continues {[(TB-T2-TB2) / T2]*t0}. If TB2 is greater than (TB+T2), the power of the intermediate frequency power supply is adjusted to (P1-K*P0), and the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9 to cool {[(TB2-TB-T2) / T2]*t1}. If TB2 is greater than or equal to (TB-T2) and less than or equal to (TB+T2), the tooth root at the middle B of the gear tooth meets the heating requirements, and the first end coil 702 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0116] S243. The second-end coil 704 is moved into the tooth tip working position at the middle B of the gear tooth by the lifting moving platform 10 and the horizontal moving platform 9, and the second-end power supply 703 is connected to the high-frequency power supply.

[0117] S244. After heating the tooth tip at the middle B of the gear tooth for a certain period of time, the temperature of the tooth tip at the middle B of the gear tooth is obtained by the temperature measuring instrument 8 as TB1. If TB1 is less than (TB-T1), the power of the high-frequency power supply is adjusted to (P2+K*P0), and heating continues {[(TB-T1-TB1) / T1]*t0}. If TB1 is greater than (TB+T1), the power of the high-frequency power supply is adjusted to (P2-K*P0), and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9 to cool {[(TB1-TB-T1) / T1]*t1}. If TB1 is greater than or equal to (TB-T1) and less than or equal to (TB+T1), the tooth tip at the middle B of the gear tooth meets the heating requirements, and the second end coil 704 is moved out of the working position by the lifting moving platform 10 and the horizontal moving platform 9.

[0118] S25. The rotating table 2 drives the bevel gear 3 to rotate by an angle α. The cooling nozzle 5 is used to cool the gear teeth after induction heating. Steps S21 to S24 are repeated to induction heat the next gear tooth until all the gear teeth of the bevel gear 3 are induction heated.

[0119] S3. Temper the teeth of the bevel gear 3 obtained in step S2:

[0120] S31. The stress distribution value of the teeth of the bevel gear 3 is measured using the laser ultrasonic stress detector 4. If the maximum stress value Fmax of the teeth is greater than the ultimate stress value Fx of the teeth or the stress difference (ΔF=Fmax-Fmin) of the teeth is greater than the ultimate stress difference ΔFx of the teeth, then the temperature difference between the heating target temperatures of the first end A, the middle part B and the second end C of the teeth in step S21 is reduced respectively, and step S2 is repeated to perform induction heating on the teeth again; if the maximum stress value Fmax of the teeth is less than or equal to the ultimate stress value Fx of the teeth and the stress difference ΔF of the teeth is less than or equal to the ultimate stress difference ΔFx of the teeth, then step S32 is performed.

[0121] S32. A medium-frequency power supply is supplied to the tempering power supply 602 in the induction tempering assembly 6, thereby using the tempering coil 603 to temper and heat the teeth of the bevel gear 3.

[0122] S33. The rotating table 2 drives the bevel gear 3 to rotate, and steps S31 to S32 are repeated until the tempering of all the teeth of the bevel gear 3 is completed.

[0123] S4. Perform stress testing on the teeth of the bevel gear 3 obtained in step S3:

[0124] The bevel gear 3 obtained in step S3 is rotated one revolution using the rotating table 2, and the stress distribution of the bevel gear 3 is detected by the laser ultrasonic stress detector 4. If the maximum stress value Fmax of the bevel gear 3 is less than the ultimate stress value Fx of the bevel gear 3, and the stress difference ΔF of the bevel gear 3 is less than or equal to the ultimate stress difference ΔFx of the bevel gear 3, then the induction heat treatment of the bevel gear 3 is completed. If the maximum stress value Fmax of the bevel gear 3 is greater than or equal to the ultimate stress value Fx of the bevel gear 3, or the stress difference ΔF of the bevel gear 3 is greater than the ultimate stress difference ΔFx of the bevel gear 3, then the power of the tempering power supply 602 is adjusted to (PH+P0), and step S32 is repeated until the stress distribution value of the teeth of the bevel gear 3 meets the requirements, and the induction heat treatment is completed.

[0125] Simulation results of heat treatment of bevel gears using the method of this invention are shown in the figure. Figure 8 As shown in the simulation results, the segmented synchronous heating method of the dual-frequency heating system for bevel gears solves the problem of large temperature differences between the second and first ends of the bevel gear's tooth profile. By using two dynamic coils working together to heat the gears and connecting power supplies of different frequencies, the system ensures uniform temperature distribution and achieves controllable induction heating. The bevel gear exhibits good uniformity in temperature distribution, providing a fundamental guarantee for the uniform distribution of tooth hardness, thereby improving the strength and stability of the bevel gears and ultimately ensuring their performance and service life.

[0126] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A dual-frequency induction heat treatment method with a movable semi-contour coil, characterized in that, The specific implementation steps are as follows: S1. Adjust the positions of the first and second coils respectively; S2. Induction heating and temperature monitoring of the bevel gear teeth: S21. Set the initial parameters for induction heating temperature, heating time, and power supply, and mark the first end, middle part, and second end of the gear teeth at different positions on adjacent tooth tips and roots. S22. Induction heating is applied to the tooth tip at the first end of the gear teeth and the tooth root at the second end of the gear teeth: S221. The first end coil is moved into the working position of the first end of the gear tooth and the second end coil is moved into the working position of the second end of the gear tooth by the lifting moving platform and the horizontal moving platform respectively, and the first end power supply is connected to the high frequency power supply and the second end power supply is connected to the medium frequency power supply. S222. After heating the tooth tip at the first end of the gear tooth for a period of time, the tooth tip temperature TA1 at the first end of the gear tooth is obtained by a temperature measuring instrument. If TA1 is less than TA-T1, heating continues [(TA-T1-TA1) / T1]*t0; if TA1 is greater than TA+T1, the first end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TA1-TA-T1) / T1]*t1; if TA1 is greater than or equal to TA-T1 and less than or equal to TA+T1, the tooth tip at the first end of the gear tooth meets the heating requirements, and the first end coil is moved out of the working position by the lifting and lateral moving platform; where TA is the target heating temperature of the first end of the gear tooth in the bevel gear, T1 is the allowable temperature difference of the tooth tip of the bevel gear, and t0 and t1 are both unit heating time; S223. After heating the tooth root at the second end of the gear tooth for a period of time, the tooth root temperature TC2 at the second end of the gear tooth is obtained by a thermometer. If TC2 is less than TC-T2, heating continues [(TC-T2-TC2) / T2]*t0; if TC2 is greater than TC+T2, the second end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TC2-TC-T2) / T2]*t1; if TC2 is greater than or equal to TC-T2 and less than or equal to TC+T2, the tooth root at the second end of the gear tooth meets the heating requirements, and the second end coil is moved out of the working position by the lifting and lateral moving platform; where TC is the target heating temperature of the second end of the gear tooth in the bevel gear, and T2 is the allowable temperature difference of the tooth root of the bevel gear. S23. Induction heating is performed on the tooth root at the first end of the gear tooth and the tooth tip at the second end of the gear tooth: The first end coil is moved into the working position at the first end of the gear tooth and the second end coil is moved into the working position at the second end of the gear tooth by the lifting moving platform and the horizontal moving platform respectively, and the first end power supply is connected to the intermediate frequency power supply and the second end power supply is connected to the high frequency power supply. S24. Induction heating of the tooth root and tooth tip in the middle of the gear teeth: The first end coil is moved into the tooth root working position in the middle of the gear teeth by the lifting and moving platform and the lateral moving platform, and the first end power supply and the intermediate frequency power supply are connected to heat the tooth root in the middle of the gear teeth for a certain period of time. The second end coil is moved into the tooth tip working position in the middle of the gear teeth by the lifting and moving platform and the lateral moving platform, and the second end power supply and the high frequency power supply are connected to heat the tooth tip in the middle of the gear teeth for a certain period of time. S25. The rotating table drives the bevel gear to rotate, and the cooling nozzle is used to cool the gear teeth after induction heating in steps S22 to S24. Steps S21 to S24 are repeated to induction heat the next gear tooth until all gear teeth of the bevel gear are induction heated. S3. Temper the teeth of the bevel gear obtained in step S2: S31. The stress distribution value of the bevel gear teeth is measured using a laser ultrasonic stress detector. If the maximum stress value Fmax of the teeth is greater than the ultimate stress value Fx of the teeth or the stress difference ΔF of the teeth is greater than the ultimate stress difference ΔFx of the teeth, then the temperature difference between the heating target temperatures of the first end, the middle part, and the second end of the teeth in step S21 is reduced respectively, and step S2 is repeated to perform induction heating on the teeth again. If the maximum stress value Fmax of the teeth is less than or equal to the ultimate stress value Fx of the teeth and the stress difference ΔF of the teeth is less than or equal to the ultimate stress difference ΔFx of the teeth, then step S32 is performed, where ΔF = Fmax - Fmin, and Fmin is the minimum stress value of the teeth. S32. A medium-frequency power supply is supplied to the tempering power supply in the induction tempering assembly, and the teeth of the bevel gear are tempered and heated by the tempering coil. The expression for the energizing time of the tempering coil is: ； Where [F] is the allowable stress, [ΔF] is the allowable stress difference, and m1, m2, m3, m4 and m5 are the gradient energizing times, respectively; S33. The rotating table drives the bevel gear to rotate. Repeat steps S31 to S32 until the tempering of all the teeth of the bevel gear is completed. S4. Perform stress testing on the teeth of the bevel gear obtained in step S3.

2. The dual-frequency induction heat treatment method with a movable semi-contour coil according to claim 1, characterized in that, The specific implementation steps of step S1 include: S11. Calculate the height of the bevel gear based on its shape parameters. S12. Based on the power frequencies of the high-frequency power supply and the medium-frequency power supply, as well as the material of the bevel gear, the induction heating depths of the first end coil and the second end coil are obtained respectively. S13. Based on the induction heating depth obtained in step S12, using the position information obtained by the vision camera, the distance d between the first end coil and the second end coil and the bevel gear teeth is set by the lifting moving platform and the horizontal moving platform, respectively.

3. The dual-frequency induction heat treatment method with a movable semi-contour coil according to claim 1, characterized in that, In step S21, the initial parameters of the power supply include the frequency f1 of the intermediate frequency power supply of the induction heating component, the frequency f2 of the high frequency power supply of the induction heating component, the power P1 of the intermediate frequency power supply of the induction heating component, the power P2 of the high frequency power supply of the induction heating component, and the power PH of the intermediate frequency power supply of the induction tempering component; in step S33, the power PH of the intermediate frequency power supply of the induction tempering component is less than the power P1 of the intermediate frequency power supply of the induction heating component.

4. The dual-frequency induction heat treatment method with a movable semi-contour coil according to claim 1, characterized in that, The specific implementation steps of step S23 include: S231. After heating the tooth root at the first end of the gear tooth for a period of time, the tooth root temperature TA2 at the first end of the gear tooth is obtained by a thermometer. If TA2 is less than TA-T2, heating continues [(TA-T2-TA2) / T2]*t0; if TA2 is greater than TA+T2, the first end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TA2-TA-T2) / T2]*t1; if TA2 is greater than or equal to TA-T2 and less than or equal to TA+T2, the tooth tip at the first end of the gear tooth meets the heating requirements, and the first end coil is moved out of the working position by the lifting and lateral moving platform. S232. After heating the tooth tip at the second end of the gear tooth for a period of time, the root temperature TC1 at the second end of the gear tooth is obtained by a temperature measuring instrument. If TC1 is less than TC-T1, heating continues [(TC-T1-TC1) / T1]*t0; if TC1 is greater than TC+T1, the second end coil is moved out of the working position by the lifting and lateral moving platform and cooled [(TC1-TC-T1) / T1]*t1; if TC1 is greater than or equal to TC-T1 and less than or equal to TC+T1, the tooth tip at the second end of the gear tooth meets the heating requirements, and the second end coil is moved out of the working position by the lifting and lateral moving platform.

5. The dual-frequency induction heat treatment method with a movable semi-contour coil according to claim 1, characterized in that, The specific implementation steps of step S24 include: S241. The root temperature TB2 at the middle of the gear tooth is obtained by a thermometer. If TB2 is less than TB-T2, the power of the intermediate frequency power supply is adjusted to P1+K*P0, and heating continues [(TB-T2-TB2) / T2]*t0. If TB2 is greater than TB+T2, the power of the intermediate frequency power supply is adjusted to P1-K*P0, and the first coil is moved out of the working position by the lifting and lateral moving platform to cool [(TB2-TB-T2) / T2]*t1. If TB2 is greater than or equal to TB-T2 and less than or equal to TB+T2, the root temperature at the middle of the gear tooth meets the heating requirement, and the first coil is moved out of the working position by the lifting and lateral moving platform. Wherein, TB is the target heating temperature at the middle of the gear tooth, and K is the power coefficient. S242. The temperature TB1 at the tooth tip in the middle of the gear tooth is obtained by a temperature measuring instrument. If TB1 is less than TB-T1, the power of the high-frequency power supply is adjusted to P2+K*P0, and heating continues [(TB-T1-TB1) / T1]*t0. If TB1 is greater than TB+T1, the power of the high-frequency power supply is adjusted to P2-K*P0, and the second end coil is moved out of the working position by the lifting and lateral moving platform to cool [(TB1-TB-T1) / T1]*t1. If TB1 is greater than or equal to TB-T1 and less than or equal to TB+T1, the tooth tip in the middle of the gear tooth meets the heating requirement, and the second end coil is moved out of the working position by the lifting and lateral moving platform.

6. The dual-frequency induction heat treatment method with a movable semi-contour coil according to claim 1, characterized in that, In step S25, the rotating platform rotates by an angle α = 2π / z each time, where z is the number of teeth of the bevel gear.

7. The dual-frequency induction heat treatment method with a movable semi-contour coil according to claim 1, characterized in that, The specific implementation steps of step S4 are as follows: the bevel gear obtained in step S3 is rotated one revolution using a rotating table, and the stress distribution of the bevel gear is detected by a laser ultrasonic stress detector. If the maximum stress value Fmax of the bevel gear is less than the ultimate stress value Fx of the bevel gear, and the stress difference ΔF of the bevel gear is less than or equal to the ultimate stress difference ΔFx of the bevel gear, then the induction heat treatment of the bevel gear ends. If the maximum stress value Fmax of the bevel gear is greater than or equal to the ultimate stress value Fx of the bevel gear, or the stress difference ΔF of the bevel gear is greater than the ultimate stress difference ΔFx of the bevel gear, then the power of the tempering power supply is adjusted to PH+P0, and step S32 is repeated until the stress distribution value of the bevel gear teeth meets the requirements, and the induction heat treatment ends. Wherein, P0 is the unit power supply power.

8. A dual-frequency induction heat treatment apparatus with a movable semi-contour coil, the dual-frequency induction heat treatment apparatus being used in the dual-frequency induction heat treatment method with a movable semi-contour coil as described in any one of claims 1-7, characterized in that, The dual-frequency induction heat treatment device includes a base, a rotating table, a laser ultrasonic stress detector, a cooling nozzle, an induction tempering assembly, an induction heating assembly, a thermometer, a lateral moving platform, a lifting moving platform, a vision camera, and a support. The rotating table is located in the middle of the base. The laser ultrasonic stress detector, the cooling nozzle, and the induction tempering assembly are respectively connected to the first, second, and third mounting ends of the base in the circumferential direction. The first and second coils of the induction heating assembly are located at the fourth mounting end of the base. The thermometer is symmetrically distributed on both sides of the induction heating assembly. The mounting end of the induction heating assembly is connected to the first end of the lateral moving platform. The lateral moving platform is symmetrically distributed at both ends of the lifting moving platform. The top of the lifting moving platform is connected to the first end of the support, and the second end of the support is connected to the vision camera.

9. A dual-frequency induction heat treatment apparatus with a movable semi-contour coil according to claim 8, characterized in that, The induction tempering assembly includes a tempering bracket, a tempering power supply, and a tempering coil. The bottom of the tempering bracket is connected to the third mounting end of the base, the top of the tempering bracket is connected to the fixed end of the tempering power supply, and the output end of the tempering power supply is connected to the tempering coil. The induction heating assembly includes a first-end power supply, a second-end power supply, a first-end coil, and a second-end coil. The output end of the first-end power supply is connected to the first-end coil, the output end of the second-end power supply is connected to the second-end coil, the second-end coil is located below the first-end coil, and the fixed ends of the first-end power supply and the second-end power supply are respectively connected to the first ends of the transverse moving platform symmetrically distributed at both ends of the lifting moving platform.

10. A dual-frequency induction heat treatment apparatus with a movable semi-contour coil according to claim 8, characterized in that, The outer shapes of the second end coil and the first end coil respectively conform to the outer contour of a bevel gear.

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