Rigid wheel, machining method thereof and harmonic speed reducer

Abstract

The invention discloses a rigid wheel, a machining method thereof and a harmonic speed reducer, and relates to the technical field of harmonic speed reducers, the rigid wheel comprises a body and a nitriding layer, and the nitriding layer is formed on the surface of the body through nitriding treatment on the body. The surface hardness of the nitriding layer ranges from 450 HV to 650 HV, so that the surface hardness of the rigid wheel can be improved, the wear resistance of the rigid wheel is improved, and the service life of the rigid wheel is prolonged. Compared with the scheme that the body is manufactured through materials with the hardness meeting the corresponding requirements, the scheme has the advantages that the body can be manufactured through the materials with the low hardness, and then the surface hardness of the body is improved through nitriding treatment so as to meet the corresponding performance requirements. And low-hardness materials are convenient to process, the processing time is short, the precision is high, the working efficiency is high, and the production cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of harmonic reducers, and in particular to a rigid wheel and a processing method thereof, and a harmonic reducer. Background Art

[0002] In the related art, the harmonic reducer includes a rigid wheel, a flexible wheel and a wave generator. The flexible wheel is sleeved on the outer ring of the wave generator, and the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel. The flexible wheel is deformed by the rotation of the wave generator, so that the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel at different positions, thereby driving the flexible wheel to rotate and output power. The wear between the inner teeth of the traditional rigid wheel and the outer teeth of the flexible wheel is large, and it is necessary to improve the wear resistance by increasing the hardness. However, if a harder metal is used, there will be problems such as difficult processing, long processing time, and the inability to guarantee precision, resulting in high production costs. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a rigid wheel, wherein the body of the rigid wheel is made of a material with low hardness, and the material with low hardness has the advantages of convenient processing, short processing time, high precision, etc., and a subsequent nitriding treatment forms a nitriding layer on the surface of the rigid wheel to improve the surface hardness of the rigid wheel and increase the wear resistance of the rigid wheel.

[0004] The invention also provides a processing method of the rigid wheel.

[0005] According to the first aspect of the present invention, the rigid wheel includes: a main body, including an annular portion and an inner tooth portion, wherein the inner tooth portion is arranged on the inner wall of the annular portion; a nitriding layer, formed on the surface of the inner tooth portion and the annular portion, wherein the surface hardness of the nitriding layer is 450HV to 650HV.

[0006] The rigid wheel according to the embodiment of the present invention has at least the following beneficial effects:

[0007] By nitriding the annular portion and the inner tooth portion of the body, a nitriding layer is formed on the surface of the annular portion and the inner tooth portion. The surface hardness of the nitriding layer is 450HV to 650HV, so the surface hardness of the wheel can be improved, the wear resistance of the wheel can be increased, and the service life of the wheel can be increased. Compared with the scheme of using materials with hardness meeting the corresponding requirements to make the body, this scheme can use materials with lower hardness to make the body, and then perform nitriding treatment to increase the surface hardness of the annular portion and the inner tooth portion to meet the corresponding performance requirements. Materials with low hardness are easy to process, with short processing time, high precision, high work efficiency, and can reduce production costs.

[0008] According to some embodiments of the present invention, the thickness of the nitriding layer is t, and the hardness at a distance of 0.3t from the surface of the nitriding layer is 440 HV to 500 HV.

[0009] According to some embodiments of the present invention, the hardness at a distance of 0.5t from the surface of the nitriding layer is 430 HV to 440 HV.

[0010] According to some embodiments of the present invention, a white bright layer is further provided on the surface of the nitriding layer, and the hardness of the white bright layer is greater than the hardness of the nitriding layer.

[0011] According to some embodiments of the present invention, the thickness of the white bright layer is less than or equal to 0.03 mm.

[0012] According to some embodiments of the present invention, the thickness of the nitriding layer is greater than or equal to 0.1 mm.

[0013] According to some embodiments of the present invention, the body is made of ductile iron material, and the chemical composition of the body is, in mass percentage, C: 3.0%-4.0%, Si: 2.0%-3.0%, Mn: ≤1.0%, P: ≤0.1%, S: ≤0.06%, Cr: ≤0.1%, Cu: 0.5%-0.8%, and the remainder is Fe.

[0014] The harmonic reducer according to the second embodiment of the present invention comprises the rigid wheel described in the above embodiment; a flexible wheel comprising a cylinder having an outer tooth portion meshing with the inner tooth portion; and a wave generator installed in the inner hole of the cylinder.

[0015] The harmonic reducer according to the embodiment of the present invention has at least the following beneficial effects:

[0016] The rigid wheel of the first aspect of the embodiment is used, and a nitriding treatment is performed on the main body of the rigid wheel, so that a nitriding layer is formed on the surface of the main body. The surface hardness of the nitriding layer is 450HV to 650HV, so the surface hardness of the rigid wheel can be improved, the wear resistance of the rigid wheel can be increased, and the service life of the rigid wheel can be improved. Compared with the scheme of using materials with hardness meeting the corresponding requirements to make the main body, this scheme can use materials with lower hardness to make the main body, and then perform nitriding treatment to increase the surface hardness of the main body to meet the corresponding performance requirements. Materials with low hardness are easy to process, have short processing time, high precision, high work efficiency, and can reduce production costs.

[0017] According to some embodiments of the present invention, the wave generator includes a cam and a flexible bearing, wherein the flexible bearing is sleeved on an outer peripheral wall of the cam and has an interference fit with the cam.

[0018] According to some embodiments of the present invention, the harmonic reducer further includes a cross roller bearing, and an inner ring and an outer ring of the cross roller bearing are respectively connected to the rigid wheel and the flexible wheel.

[0019] According to the third aspect of the present invention, the processing method of the rigid wheel is used to process the rigid wheel of the first aspect, comprising the following steps: using a ductile iron substrate to process a rigid wheel semi-finished product; performing low-temperature nitriding treatment on the rigid wheel semi-finished product; wherein the surface hardness of the rigid wheel semi-finished product after low-temperature nitriding is 450HV to 650HV.

[0020] The method for processing a rigid wheel according to an embodiment of the present invention has at least the following beneficial effects:

[0021] By nitriding the body of the steel wheel, a nitriding layer is formed on the surface of the body. The surface hardness of the nitriding layer is 450HV to 650HV, so the surface hardness of the steel wheel can be improved, the wear resistance of the steel wheel can be increased, and the service life of the steel wheel can be increased. Compared with the scheme of using materials with hardness meeting the corresponding requirements to make the body, this scheme can use materials with lower hardness to make the body, and then nitriding treatment is performed to increase the surface hardness of the body to meet the corresponding performance requirements. Materials with low hardness are easy to process, with short processing time, high precision, high work efficiency, and can reduce production costs.

[0022] According to some embodiments of the present invention, the process of using a ductile iron substrate to form a semi-finished rigid wheel comprises the following steps: using a ductile iron substrate to form a semi-finished rigid wheel through casting, rough turning, and fine turning.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 A schematic diagram of the structure of a harmonic reducer according to an embodiment of the present invention;

[0026] Figure 2 An exploded schematic diagram of a harmonic reducer according to an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of a partial structure of a rigid wheel according to an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the hardness of the nitrided layer of a rigid wheel at different positions according to an embodiment of the present invention;

[0029] Figure 5A flow chart of a method for processing a rigid wheel according to an embodiment of the present invention;

[0030] Figure 6 The present invention is a flowchart of a method for processing a rigid wheel according to an embodiment of the present invention.

[0031] Figure Number:

[0032] Harmonic reducer 100; rigid wheel 110; body 111; nitriding layer 112; white bright layer 113; inner tooth portion 114; first inner hole 115; annular portion 116; flexible wheel 120; outer tooth portion 121; cylinder portion 122; second inner hole 123; partition 124; flange 125; wave generator 130; flexible bearing 131; cam 132; cross roller bearing 140. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0034] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In the description of the present invention, "a plurality" means more than two. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0037] The harmonic reducer has the advantages of high load-bearing capacity, large transmission ratio, small size, light weight, high transmission efficiency, and smooth transmission. It can be used in the rotating joints of industrial robots to reduce speed. The harmonic reducer includes a rigid wheel, a flexible wheel, and a wave generator. The flexible wheel is sleeved on the outer ring of the wave generator, and the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel. The flexible wheel is deformed by the rotation of the wave generator, so that the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel at different positions, thereby driving the flexible wheel to rotate and output power. The wear between the inner teeth of the traditional rigid wheel and the outer teeth of the flexible wheel is large, which reduces the service life of the rigid wheel.

[0038] Based on this, the present invention proposes a steel wheel, which forms a nitriding layer on the surface of the steel wheel through nitriding treatment to improve the surface hardness of the steel wheel, increase the wear resistance of the steel wheel, and further improve the service life of the steel wheel.

[0039] The following is a description with reference to the accompanying drawings:

[0040] Reference Figure 1 , Figure 2 and Figure 3 As shown, in an embodiment of the present invention, the rigid wheel 110 includes a body 111 and a nitriding layer 112, the body 111 includes an annular portion 116 and an inner tooth portion 114, and the inner tooth portion 114 is arranged on the inner wall of the annular portion 116. The nitriding layer 112 is formed on the surface of the annular portion 116 and the surface of the inner tooth portion 114. For example, the method of forming the nitriding layer 112 can be to place the body 111 in a nitriding furnace after cleaning to perform nitriding, so that the nitriding layer 112 is formed on the surface of the body 111. The surface hardness of the nitriding layer 112 is 450HV to 650HV, for example, it can be 400HV, 450HV, 500HV, 550HV. Therefore, the surface hardness of the rigid wheel 110 can be improved, the wear resistance of the rigid wheel 110 can be increased, the wear amount when cooperating with the flexible wheel 120 can be reduced, and the service life of the rigid wheel 110 can be improved.

[0041] Reference Figure 3 As shown, in the embodiment of the present invention, the thickness of the nitriding layer 112 is t, and the hardness at 0.3t from the surface of the nitriding layer 112 is 440HV to 500HV, for example, it can be 450HV, 460HV, 470HV, 490HV. It can be understood that the hardness of the nitriding layer 112 at different positions can be different, for example, the hardness at 0.3t from the surface of the nitriding layer 112 is less than the surface hardness of the nitriding layer 112. The hardness of the surface of the nitriding layer 112 is the largest, which can improve the hardness and wear resistance of the surface of the rigid wheel 110, thereby improving the overall service life of the rigid wheel 110. The hardness inside the nitriding layer 112 is reduced, which can reduce stress concentration and make the stress distribution uniform, thereby improving the fatigue resistance of the rigid wheel 110.

[0042] Continue to refer to Figure 3As shown, in the embodiment of the present invention, the hardness at a distance of 0.5t from the surface of the nitriding layer 112 is 430HV to 440HV. Figure 4 As shown in Figure 4 The abscissa in represents the depth of the nitrided layer 112, and the ordinate represents the hardness of the nitrided layer 112. The hardness of the nitrided layer 112 gradually decreases from the surface to the inside, which can make the stress distribution more uniform, reduce the risk of cracks on the surface of the rigid wheel 110, and thus improve the fatigue life of the rigid wheel 110.

[0043] In an embodiment of the present invention, the thickness of the nitriding layer 112 is greater than or equal to 0.1 mm. For example, the thickness of the nitriding layer 112 may be 0.2 mm, 0.3 mm, 0.5 mm, 1 mm, etc. It is understandable that, assuming that the thickness of the nitriding layer 112 is less than 0.1 mm, the thinner nitriding layer 112 may not provide sufficient hardness and wear resistance, resulting in the surface of the rigid wheel 110 being susceptible to wear and fatigue, thereby shortening the service life of the rigid wheel 110. At the same time, the thinner nitriding layer 112 may not be able to effectively protect the surface of the rigid wheel 110, making it susceptible to oxidation, corrosion, and chemical erosion. Therefore, a reasonable design of the thickness of the nitriding layer 112 can improve the surface hardness of the rigid wheel 110, so that it has good wear resistance and strength, and prolongs the service life of the rigid wheel 110.

[0044] Reference Figure 3 As shown, in the embodiment of the present invention, a white bright layer 113 is further provided on the surface of the nitriding layer 112, and the hardness of the white bright layer 113 is greater than the hardness of the nitriding layer 112. Therefore, by providing a white bright layer 113 with greater hardness on the surface of the nitriding layer 112, the wear resistance, corrosion resistance and fatigue resistance of the rigid wheel 110 can be further improved, and the wear can be reduced, and the service life of the rigid wheel 110 can be increased.

[0045] In an embodiment of the present invention, the thickness of the white bright layer 113 is less than or equal to 0.03 mm. For example, the thickness of the white bright layer 113 may be 0.02 mm or 0.01 mm. It is understandable that if the thickness of the white bright layer 113 is too thick, for example, greater than 0.03 mm, it is easy to change the geometric size and surface shape of the inner tooth portion 114 of the rigid wheel 110, resulting in inaccurate tooth shape, affecting the transmission efficiency and the stability of the transmission. If the white bright layer 113 is too thick, it is easy to cause internal stress accumulation, resulting in cracks on the surface of the rigid wheel 110, reducing the strength and durability of the rigid wheel 110. At the same time, it will increase the difficulty of processing and increase the production cost. Therefore, a reasonable design of the thickness of the white bright layer 113 can ensure that the rigid wheel 110 has good performance and a long life.

[0046] In an embodiment of the present invention, the main body 111 is made of ductile iron material. Ductile iron is a high-strength cast iron material containing spheroidal graphite. Due to the presence of spheroidal graphite, stress can be dispersed, providing good toughness and fracture resistance. This enables ductile iron to withstand dynamic or impact loads in engineering applications and has good deformation resistance. Ductile iron also has good processing properties and can be subjected to a variety of processing techniques such as casting, machining and heat treatment, which can meet the production needs of parts of different shapes and sizes. Compared with some high-strength alloy materials, ductile iron has a lower production cost and provides an economical and convenient option. Therefore, the use of ductile iron to make the main body 111 can improve production efficiency, reduce costs, and meet the performance requirements of the rigid wheel 110.

[0047] In an embodiment of the present invention, the chemical composition of the body 111 is calculated by mass percentage as follows: carbon C: 3.0%-4.0%, silicon Si: 2.0%-3.0%, manganese Mn: ≤1.0%, phosphorus P: ≤0.1%, sulfur S: ≤0.06%, chromium Cr: ≤0.1%, copper Cu: 0.5%-0.8%, and the balance is iron Fe. It should be noted that carbon is a basic element of ductile iron. A high carbon content is conducive to graphitization, and it will also cause graphitization expansion during solidification of cast iron, thereby improving the self-compensation capacity of molten iron. However, too high a carbon content will cause graphite to float. Therefore, it is necessary to control the carbon content to 3.0%-4.0%. Silicon can effectively reduce the tendency of white cast iron in ductile iron, and it has the effect of refining the eutectic group and improving the roundness of graphite balls. However, too high silicon content will increase the toughness-brittleness transition temperature of cast iron and reduce impact toughness, so the silicon content should not be too high; while too low silicon content is not conducive to improving the roundness of graphite balls. Since the sulfur content in ductile iron is not high, too much manganese is not needed to neutralize sulfur. Manganese is mainly used to increase the stability of pearlite, but too much manganese content will increase the toughness-brittleness transition temperature of ductile iron. The manganese content generally does not exceed 0.4-0.6%, but in order to improve the wear resistance of ductile iron, the manganese content can be appropriately increased to less than or equal to 1.0%. Phosphorus and sulfur are impurities in ductile iron, the less the better. Reducing the content of phosphorus and sulfur helps to reduce the brittleness of ductile iron, improve its impact toughness, and enhance the durability and reliability of rigid wheel 110. Chromium and copper exist in ductile iron at low levels. Chromium can improve the corrosion resistance of ductile iron, while copper helps to improve the strength and wear resistance of ductile iron.

[0048] Reference Figure 5 As shown, a method for processing a rigid wheel 110 according to an embodiment of the present invention comprises the following steps:

[0049] Step S501: Use ductile iron substrate to process into a semi-finished rigid wheel. It is understandable that ductile iron is a high-strength cast iron material containing spheroidal graphite. Due to the presence of spheroidal graphite, it can absorb and disperse stress, and provide good toughness and fracture resistance. This enables ductile iron to withstand dynamic or impact loads in engineering applications and has good deformation resistance. Ductile iron has good processing properties and can be subjected to a variety of processing techniques such as casting, machining and heat treatment, which can meet the production needs of parts of different shapes and sizes. Compared with some high-strength alloy materials, ductile iron has a lower production cost, providing an economical and feasible option. Therefore, the use of ductile iron to make the main body 111 can improve production efficiency, reduce costs, and meet the performance requirements of the rigid wheel 110.

[0050] Step S502: low-temperature nitriding treatment is performed on the semi-finished steel wheel. The nitriding temperature of the conventional nitriding treatment is usually higher than 500°C. Too high a temperature can easily lead to an increase in the deformation of the semi-finished steel wheel, affecting the product quality. Therefore, the nitriding temperature of the low-temperature nitriding can be controlled between 350°C and 450°C, such as 350°C, 380°C, 400°C, and 450°C. Among them, gas nitriding can be used for nitriding. The low-temperature nitriding method can reduce the deformation risk of the semi-finished steel wheel, protect the surface quality, and improve the toughness of the material. For example, during low-temperature nitriding, due to the low temperature, the thermal expansion coefficient of the material is small, thereby reducing the risk of material deformation and stress accumulation that may be caused during the nitriding process. Problems such as surface oxidation, burning and discoloration caused by excessive temperature can be effectively avoided, and the surface quality of the semi-finished steel wheel can be protected. At the same time, the low-temperature nitriding layer has a good bond with the substrate, so the overall toughness and anti-stripping ability of the semi-finished steel wheel can be improved.

[0051] The surface hardness of the semi-finished rigid wheel after low temperature nitriding is 450HV to 650HV. For example, it can be 400HV, 450HV, 500HV, 550HV. Therefore, the surface hardness of the rigid wheel 110 can be improved, the wear resistance of the rigid wheel 110 can be increased, the wear amount when it cooperates with the flexible wheel 120 can be reduced, and the service life of the rigid wheel 110 can be increased.

[0052] Reference Figure 6 As shown, in the embodiment of the present invention, step S501 includes:

[0053] Step S601: The ductile iron substrate is used to form a semi-finished gear wheel through casting, rough turning and fine turning. It is understood that the ductile iron substrate has good machining properties and can be cast, rough turned and fine turned. This allows the semi-finished gear wheel to be flexibly designed and accurately processed according to actual needs to meet the requirements of different sizes, shapes and gear parameters.

[0054] A harmonic reducer 100 according to an embodiment of the present invention comprises a flexible wheel 120, a wave generator 130 and a rigid wheel 110 according to the above embodiment. A first inner hole 115 is provided in the middle of the rigid wheel 110, and an inner tooth portion 114 is provided around the inner wall of the first inner hole 115. The flexible wheel 120 comprises a cylinder 122, a second inner hole 123 is formed in the cylinder 122, and an outer tooth portion 121 is provided in the cylinder 122, and the outer tooth portion 121 is meshed with the inner tooth portion 114. The wave generator 130 is installed in the second inner hole 123 and has an interference fit with the flexible wheel 120. The wave generator 130 is connected to an input shaft, and the input shaft drives the wave generator 130 to rotate, so that the flexible wheel 120 is deformed. The number of teeth of the outer tooth portion 121 is usually two less than the number of teeth of the inner tooth portion 114. When the outer tooth portion 121 meshes with the inner tooth portion 114 at different positions, the flexible wheel 120 can be driven to rotate, thereby completing power output.

[0055] The harmonic reducer 100 of the embodiment of the present invention adopts the rigid wheel 110 of the embodiment of the first aspect, and nitriding is performed on the body 111 of the rigid wheel 110, and the body 111 is cleaned and placed in a nitriding furnace for nitriding, so that a nitriding layer 112 is formed on the surface of the body 111. The surface hardness of the nitriding layer 112 is 450HV to 650HV, so that the surface hardness of the rigid wheel 110 can be improved, the wear resistance of the rigid wheel 110 can be increased, and the service life of the rigid wheel 110 can be improved.

[0056] Reference Figure 2 As shown, in the embodiment of the present invention, the wave generator 130 includes a cam 132 and a flexible bearing 131, the cam 132 is elliptical, and is arranged on the inner ring of the flexible bearing 131 by interference fit. The flexible bearing 131 is flexible and can be elastically deformed, so when the cam 132 is arranged on the flexible bearing 131, the flexible bearing 131 is elliptical. During the rotation of the cam 132, the long axis region can make the outer tooth portion 121 of the flexible wheel 120 and the inner tooth portion 114 of the rigid wheel 110 mesh, and the short axis region can make the outer tooth portion 121 of the flexible wheel 120 and the inner tooth portion 114 of the rigid wheel 110 separate, and the flexible bearing 131 can reduce the rotational friction between the cam 132 and the flexible wheel 120, thereby increasing the service life of the wave generator 130.

[0057] Reference Figure 1 and Figure 2As shown, in the embodiment of the present invention, the harmonic reducer 100 further includes a cross roller bearing 140, the inner ring of the cross roller bearing 140 is connected to the rigid wheel 110, and the outer ring is connected to the flexible wheel 120, and the cross roller bearing 140 plays the role of transmitting force and bearing load. For example, the flexible wheel 120 also includes a partition 124 and a flange 125, the partition 124 is connected to the end of the barrel 122 away from the outer tooth portion 121, the partition 124 is bent in the direction away from the second inner hole 123 and arranged around the second inner hole 123, and the flange 125 is arranged around the side of the partition 124 away from the barrel 122. The flange 125 is fixedly connected to the outer ring of the cross roller bearing 140, and when the flexible wheel 120 rotates, it can drive the outer ring of the cross roller bearing 140 to rotate to complete the power output. Therefore, the cross roller bearing 140 also has a positioning function, which can effectively reduce the occurrence of offset and dislocation of the flexible wheel 120.

[0058] Since the harmonic reducer 100 adopts all the technical solutions of the rigid wheel 110 of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described in detail here.

[0059] An industrial robot according to an embodiment of the present invention comprises the harmonic reducer 100 of the above-mentioned embodiment. Since industrial robots usually need to perform complex movements and precise position control. The harmonic reducer 100 can provide high-precision speed conversion and torque output, so that the robot can achieve accurate positioning and motion control. Industrial robots usually need to be installed and operated in a limited space. The harmonic reducer 100 adopts a miniaturized and compact design, which can effectively save installation space, make the overall size of the industrial robot smaller, and facilitate operation and movement in a small space. The harmonic reducer 100 has high wear resistance and fatigue resistance, can operate stably for a long time under high load and frequent working conditions, and provides reliable performance and long-lasting service life.

[0060] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. Rigid wheel, used in harmonic reducer, characterized by: include: A body, comprising an annular portion and an inner tooth portion, wherein the inner tooth portion is arranged on an inner wall of the annular portion; A nitriding layer is formed on the surfaces of the inner tooth portion and the annular portion, and the surface hardness of the nitriding layer is 450 HV to 650 HV.

2. The rigid wheel according to claim 1, characterized in that: The thickness of the nitriding layer is t, and the hardness at a distance of 0.3t from the surface of the nitriding layer is 440 HV to 500 HV.

3. The rigid wheel according to claim 2, characterized in that: The hardness at a distance of 0.5t from the surface of the nitriding layer is 430HV to 440HV.

4. The rigid wheel according to claim 1, characterized in that: A white bright layer is also provided on the surface of the nitriding layer, and the hardness of the white bright layer is greater than the hardness of the nitriding layer.

5. The rigid wheel according to claim 4, characterized in that: The thickness of the white bright layer is less than or equal to 0.03 mm.

6. The rigid wheel according to claim 1, characterized in that: The thickness of the nitriding layer is greater than or equal to 0.1 mm.

7. The rigid wheel according to claim 1, characterized in that: The body is made of ductile iron material, and the chemical composition of the body is as follows in terms of mass percentage: C：3.0％-4.0％， Si: 2.0%-3.0%, Mn:≤1.0%, P：≤0.1％， S：≤0.06％， Cr：≤0.1％， Cu: 0.5%-0.8%, The balance is Fe.

8. Harmonic reducer, characterized in that: include: The rigid wheel according to any one of claims 1 to 7; A flexible wheel, comprising a cylindrical portion, wherein the cylindrical portion is provided with an external tooth portion meshing with the internal tooth portion; The wave generator is installed in the inner hole of the cylinder.

9. The harmonic reducer according to claim 8, characterized in that: The wave generator comprises a cam and a flexible bearing. The flexible bearing is sleeved on the outer peripheral wall of the cam and is interference fit with the cam.

10. The harmonic reducer according to claim 8, characterized in that: The harmonic reducer also includes a cross roller bearing, and the inner ring and the outer ring of the cross roller bearing are respectively connected to the rigid wheel and the flexible wheel.

11. A method for processing a rigid wheel, characterized in that: The following steps are involved: The semi-finished steel wheel is made of ductile iron base material; Performing low temperature nitriding treatment on the semi-finished steel wheel; Wherein, the surface hardness of the semi-finished steel wheel after low-temperature nitriding is 450HV to 650HV.

12. The method for processing a rigid wheel according to claim 11, characterized in that: The method of using ductile iron substrate to process the semi-finished steel wheel comprises the following steps: The ductile iron base material is made into a semi-finished steel wheel through casting, rough turning and fine turning.

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