SNCM439 material harmonic reducer flexible gear long-life composite heat treatment method

Abstract

The invention discloses a long-service-life composite heat treatment method for a harmonic reducer flexible gear made of an SNCM439 material, belongs to the technical field of long-service-life manufacturing of harmonic reducers, and solves the problem that the service life of the harmonic reducer flexible gear is short. According to the method, a flexible gear made of an SNCM439 material is subjected to a composite heat treatment method of secondary normalizing, quenching, deep cooling and tempering, and the specific process method is as follows: the primary normalizing temperature is 870-890 DEG C, the heat preservation time is 50-70 minutes, and air cooling is performed; the secondary normalizing temperature is 850-870 DEG C, the heat preservation time is 50-70 min, and air cooling is carried out; the quenching temperature is 830-850 DEG C, the heat preservation time is 50-70 min, and oil cooling is conducted; the subzero treatment temperature is-70 DEG C to-90 DEG C, and the heat preservation time is 110-120 min; the tempering temperature is 490-510 DEG C, and the heat preservation time is 120-140 minutes.

Description

Technical Field

[0001] The invention relates to a long-life composite heat treatment method for a flexible pulley of a harmonic reducer made of SNCM439 material, and belongs to the technical field of long-life manufacturing of harmonic reducers. Background Art

[0002] Harmonic drive is a new transmission technology theory developed in the mid-1950s with the advancement of space science and technology, based on the theory of elastic deformation of thin shells. A harmonic reducer primarily uses a wave generator to force a flexspline to produce a controllable elastic deformation wave. This breaks away from the rigid component model of mechanical transmission and instead uses a flexible component to achieve mechanical transmission. It consists of three basic components: a rigid gear (rigid wheel) with an internal ring gear, a flexible gear (flexspline) with an external ring gear, and a wave generator. Its operating principle typically employs a wave generator as the active element, a rigid wheel fixed to the center, and a flexspline output element. When the wave generator is installed within the inner diameter of the flexspline, it elastically deforms the flexspline into an elliptical shape, causing the flexspline gear at its major axis to fit into the tooth grooves of the rigid wheel, resulting in full meshing. At their minor axis, the two gears are completely disengaged and free of contact. Continuous rotation of the wave generator forces the flexspline to continuously deform and produce staggered tooth motion, thereby achieving motion transmission between the wave generator and the flexspline. The flexible spline is the core key component of the harmonic reducer and directly determines the overall life of the harmonic reducer. The long-life manufacturing of the flexible spline of the existing harmonic reducer is a common problem in China, which restricts the development of the domestic harmonic reducer industry. The main heat treatment method of the existing harmonic reducer is achieved through tempering treatment.

[0003] In the existing technical methods, the process parameters adopted are generally 860℃ quenching + tempering at about 500℃. The matrix structure state of the material after tempering remains similar to that before heat treatment. The texture and dislocation of the matrix itself will not undergo essential changes. Deformation control is difficult. The grain size will be improved to a certain extent, but the improvement effect is limited. After heat treatment, it is generally around level 8-10, and the hardness is generally maintained at around HRC32-35, which is difficult to meet the needs of long-life flexible pulleys of harmonic reducers. Summary of the Invention

[0004] In order to improve the above technical problems, the present invention provides a composite heat treatment method for extending the life of a flexible pulley of a harmonic reducer made of SNCM439 material, which improves the problem of short life of the flexible pulley of the harmonic reducer.

[0005] The present invention provides a long-life composite heat treatment method for a flexspline made of SNCM439 material for a harmonic reducer. The method is to subject the flexspline made of SNCM439 material to a composite heat treatment method of secondary normalizing + quenching + deep cooling + tempering. The specific steps are as follows: S1: The flexible wheel is subjected to the first normalizing treatment at a temperature of 870-890°C and kept at this temperature for 50-70 minutes. After the holding time is completed, it is cooled to room temperature by air cooling; S2: After the flexible wheel is cooled, it is subjected to a second normalizing treatment at a temperature of 850-870°C and kept at that temperature for 50-70 minutes. After the holding time is completed, it is cooled to room temperature by air cooling. S3: After the flexible pulley is cooled, it is quenched at a quenching temperature of 830-850°C and kept warm for 50-70 minutes. After the holding period, it is cooled by oil cooling. S4: After cooling, the flexible wheel is subjected to a cryogenic treatment at a temperature of -70 to -90°C and kept at this temperature for 110 to 130 minutes; S5: Finally, the flexible wheel is tempered after the insulation is completed. The tempering temperature is 490-510° C. and the temperature is kept for 120-140 minutes. Furthermore, the first normalizing temperature in S1 is 875-885°C, the second normalizing temperature in S2 is 855-865°C, the quenching temperature in S3 is 835-845°C, the temperature of the deep freezing treatment in S4 is -75--85°C, and the temperature of the tempering treatment in S5 is 495-505°C.

[0006] Furthermore, the first normalizing temperature in S1 is 877-883°C, the second normalizing temperature in S2 is 857-863°C, the quenching temperature in S3 is 837-843°C, the temperature of the deep freezing treatment in S4 is -77--83°C, and the temperature of the tempering treatment in S5 is 497-503°C.

[0007] Furthermore, the flexible wheel includes a main body, a first through hole provided at the top of the main body, and a second through hole provided at the bottom of the main body, wherein the first through hole is connected to the second through hole, wherein the width of the main body is 53 mm and the height is 35 mm; the diameter of the first through hole is 12 mm; the diameter of the second through hole is 46 mm and the depth is 24 mm.

[0008] The above technical solution is adopted, and the advantages of the present invention are: through the secondary normalizing process, the texture, dislocation and other organizational defects in the matrix structure can be effectively eliminated, the crystals can be reshaped, the organizational uniformity can be achieved, the grains can be refined, and a better matrix structure can be provided for subsequent quenching. Secondly, by adopting deep cooling treatment after quenching, the degree of transformation of the matrix structure to martensite after quenching is solved, and a larger proportion of the structure is transformed to martensite, providing a better basis for the subsequent transformation of martensite to sorbite, reducing the proportion of austenite, and making the matrix performance better. The composite heat treatment method of secondary normalizing + quenching + deep cooling + tempering using this method can make the sorbite structure of the flexspline matrix uniformly refined, with comparable longitudinal and transverse dimensions, no obvious defects, grain size above level 10, matrix hardness above HRC35, and the flexspline fatigue life above 8000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is the composite heat treatment process curve; Figure 2 This is the appearance diagram of the SNCM439 material harmonic reducer flexspline in the present invention; In the figure: 1 main body, 2 first through hole, 3 second through hole. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0011] The terms "first," "second," and so on (if any) in the specification and claims of this invention are used to distinguish similar items, not to describe a specific order or precedence. Even if "second" is used to distinguish a technical feature, it does not necessarily imply the presence of "first." It should be understood that, in this invention, "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. It should be understood that, in this invention, "plurality" refers to two or more items. "And / or" simply describes an association between related items, indicating that three possible relationships exist. For example, "X and / or Y" can mean: X exists alone; X and Y exist simultaneously; or Y exists alone. The character " / " generally indicates that the related items are in an "or" relationship. "Including X, Y, and Z" means including all three of X, Y, and Z. "Including X, Y, or Z" means including any one of X, Y, and Z. "Including X, Y, and / or Z" means including any one, any two, or any three of X, Y, and Z. Example

[0012] like Figures 1 to 2 As shown, the present invention provides a long-life composite heat treatment method for a flexspline made of SNCM439 material harmonic reducer. The method is to subject the flexspline made of SNCM439 material to a composite heat treatment method of secondary normalizing + quenching + deep cooling + tempering. The specific steps are as follows: S1: The flexible wheel is subjected to the first normalizing treatment at a temperature of 870-890°C and kept at this temperature for 50-70 minutes. After the holding time is completed, it is cooled to room temperature by air cooling; S2: After the flexible wheel is cooled, it is subjected to a second normalizing treatment at a temperature of 850-870°C and kept at that temperature for 50-70 minutes. After the holding time is completed, it is cooled to room temperature by air cooling. S3: After the flexible pulley is cooled, it is quenched at a quenching temperature of 830-850°C and kept warm for 50-70 minutes. After the holding period, it is cooled by oil cooling. S4: After cooling, the flexible wheel is subjected to a cryogenic treatment at a temperature of -70 to -90°C and kept at this temperature for 110 to 130 minutes; S5: Finally, the flexible wheel is tempered after the insulation is completed. The tempering temperature is 490-510° C. and the temperature is kept for 120-140 minutes.

[0013] The present invention can effectively eliminate the texture, dislocation and other organizational defects in the matrix structure through the secondary normalizing process, reshape the crystal, achieve organizational uniformity, and refine the grains, providing a better matrix structure for subsequent quenching. Secondly, by adopting deep cooling treatment after quenching, the degree of transformation of the matrix structure to martensite after quenching is solved, and a larger proportion of the structure is transformed into martensite, providing a better basis for the subsequent transformation of martensite to sorbite, reducing the proportion of austenite, and making the matrix performance better. The composite heat treatment method of secondary normalizing + quenching + deep cooling + tempering using this method can make the sorbite structure of the flexspline matrix uniformly refined, with comparable vertical and horizontal dimensions, no obvious defects, a grain size of more than level 10, a matrix hardness of more than HRC35, and a flexspline fatigue life of more than 8,000 hours.

[0014] Specifically, the flexible pulley includes a main body 1, a first through hole 2 provided at the top of the main body, and a second through hole 3 provided at the bottom of the main body. The first through hole 2 is connected to the second through hole 3. In this embodiment, the width of the main body 1 is 53 mm and the height is 35 mm; the diameter of the first through hole 2 is 12 mm; the diameter of the second through hole 3 is 46 mm and the depth is 24 mm. Example

[0015] Different from Example 1, the first normalizing temperature in S1 is 875-885°C, the second normalizing temperature in S2 is 855-865°C, the quenching temperature in S3 is 835-845°C, the temperature of the deep freezing treatment in S4 is -75--85°C, and the temperature of the tempering treatment in S5 is 495-505°C. Example

[0016] The difference from Example 1 is that the first normalizing temperature in S1 is 877-883°C, the second normalizing temperature in S2 is 857-863°C, the quenching temperature in S3 is 837-843°C, the temperature of the deep cooling treatment in S4 is -77--83°C, and the temperature of the tempering treatment in S5 is 497-503°C.

[0017] In addition to the above-mentioned preferred embodiments, the present invention has other implementation modes. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection requested by the present invention.

Claims

1. A composite heat treatment method for long-life of a SNCM439 material harmonic reducer flexible pulley, characterized by: This method is to use a composite heat treatment method of secondary normalizing + quenching + deep cooling + tempering on the flexible pulley made of SNCM439 material. The specific steps are as follows: S1: The flexible wheel is subjected to the first normalizing treatment at a temperature of 870-890°C and kept at this temperature for 50-70 minutes. After the holding time is completed, it is cooled to room temperature by air cooling; S2: After the flexible wheel is cooled, it is subjected to a second normalizing treatment at a temperature of 850-870°C and kept at that temperature for 50-70 minutes. After the holding time is completed, it is cooled to room temperature by air cooling. S3: After the flexible pulley is cooled, it is quenched at a quenching temperature of 830-850°C and kept warm for 50-70 minutes. After the holding period, it is cooled by oil cooling. S4: After cooling, the flexible wheel is subjected to a cryogenic treatment at a temperature of -70 to -90°C and kept at this temperature for 110 to 130 minutes; S5: Finally, the flexible wheel is tempered after the insulation is completed. The tempering temperature is 490-510° C. and the temperature is kept for 120-140 minutes.

2. The composite heat treatment method for long-life of a SNCM439 material harmonic reducer flexspline according to claim 1, characterized in that: The first normalizing temperature in S1 is 875-885°C, the second normalizing temperature in S2 is 855-865°C, the quenching temperature in S3 is 835-845°C, the temperature of the deep freezing treatment in S4 is -75--85°C, and the temperature of the tempering treatment in S5 is 495-505°C.

3. The composite heat treatment method for long-life of a SNCM439 material harmonic reducer flexspline according to claim 1, characterized in that: The first normalizing temperature in S1 is 877-883°C, the second normalizing temperature in S2 is 857-863°C, the quenching temperature in S3 is 837-843°C, the temperature of the deep freezing treatment in S4 is -77--83°C, and the temperature of the tempering treatment in S5 is 497-503°C.

4. The composite heat treatment method for long-life harmonic reducer flexspline made of SNCM439 material according to claim 1, characterized in that: The flexible wheel comprises a main body (1), a first through hole (2) provided at the top of the main body, and a second through hole (3) provided at the bottom of the main body, wherein the first through hole (2) is connected to the second through hole (3), wherein the width of the main body (1) is 53 mm and the height is 35 mm; the diameter of the first through hole (2) is 12 mm; the diameter of the second through hole (3) is 46 mm and the depth is 24 mm.

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