Lightweight cross bearing for harmonic reducer and machining method of lightweight cross bearing

Abstract

According to the light-weight cross bearing for the harmonic reducer and the machining method of the light-weight cross bearing, the weight of the cross bearing is effectively reduced by adopting two materials, and the performance of the cross bearing can be further optimized according to selection of the materials. The bearing structurally comprises a bearing inner ring and a bearing outer ring, a roller is arranged between the inner side face of the bearing outer ring and the outer side face of the bearing inner ring, and the bearing is characterized in that the bearing outer ring and / or the bearing inner ring are / is of a light-weight structure, and when the bearing outer ring is of the light-weight structure, the bearing outer ring comprises a hard material layer located outside and a light material layer located inside; when the bearing inner ring is of a light weight structure, the bearing inner ring comprises a hard material layer located on the outer portion and a light material layer located on the inner portion.

Description

Technical Field

[0001] This invention relates to the field of cross bearing technology, specifically to a lightweight cross bearing for harmonic reducers and its processing method. Background Technology

[0002] With the rapid development of technologies such as artificial intelligence, the demand for harmonic reducers is increasing due to the growing use of industrial robots and humanoid robots. There is an urgent need for lighter and higher-performance harmonic reducers. Cross bearings are a crucial component of harmonic reducers, typically connected to the flexspline for power output. Their weight directly impacts the overall performance of the reducer. Currently, most cross bearings on the market are made of steel (Gr15), making lightweight design a critical challenge. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a lightweight cross bearing for harmonic reducers, along with its processing method. This method effectively reduces the weight of the cross bearing by employing two materials, and further optimizes the performance of the cross bearing based on the material selection.

[0004] The technical solution is as follows: A lightweight cross-bearing for a harmonic reducer includes an inner bearing ring and an outer bearing ring, with rollers provided between the inner surface of the outer bearing ring and the outer surface of the inner bearing ring. The bearing ring and / or the inner bearing ring employ a lightweight structure. When the outer bearing ring employs a lightweight structure, it includes an outer hard material layer and an inner lightweight material layer. When the inner bearing ring employs a lightweight structure, it includes an outer hard material layer and an inner lightweight material layer.

[0005] Furthermore, when the bearing outer ring adopts a lightweight structure, the hard material layer is located at the upper and lower ends and the inner side of the bearing outer ring, and the lightweight material layer is located on the outer side and the middle of the bearing outer ring; when the bearing inner ring adopts a lightweight structure, the hard material layer is located at the upper and lower ends and the outer side of the bearing inner ring, and the lightweight material layer is located on the inner side and the middle of the bearing inner ring.

[0006] Furthermore, the connection surface between the lightweight material layer and the rigid material layer has an irregular shape.

[0007] Furthermore, when the outer ring of the bearing adopts a lightweight structure, the mating surface of the hard material layer and the lightweight material layer of the outer ring of the bearing has a plurality of inclined protrusions extending toward the lightweight material layer; when the inner ring of the bearing adopts a lightweight structure, the mating surface of the hard material layer and the lightweight material layer of the inner ring of the bearing has a plurality of inclined protrusions extending toward the lightweight material layer.

[0008] Furthermore, the rigid material layer is made of steel, and the lightweight material layer is made of aluminum alloy.

[0009] A method for processing a lightweight cross-bearing for a harmonic reducer, characterized in that it includes the following steps: Step 1, blank processing; according to the position of the lightweight structure, a cavity for the composite lightweight material layer is processed inward from the outer side of the outer ring blank of the ring bearing and / or outward from the inner side of the inner ring blank of the ring bearing.

[0010] Step 2: Perform heat treatment and surface treatment on the processed blank;

[0011] Step 3: Inspect the surface of the blank for defects;

[0012] Step 4, Casting; Lightweight materials are injected into the blank through casting to combine hard and lightweight materials and form a lightweight material layer.

[0013] Step 5: Perform heat treatment on the cast parts;

[0014] Step 6: Check whether the performance of the parts meets the requirements;

[0015] Step 7: Turning; Machining the part according to the design requirements of the bearing inner and outer rings;

[0016] Step 8: Perform heat treatment on the machined parts to eliminate cutting stress;

[0017] Step 9: Grinding and assembly.

[0018] Furthermore, in step 1, the inner wall of the cavity used for the composite lightweight material layer is machined into an irregular shape, and multiple inclined protrusions extending toward the lightweight material layer are also machined.

[0019] Furthermore, the heat treatment step in step 2 is as follows: the room temperature is raised to 300-350℃ at a heating rate of ≤150℃ / h, then raised to 550-580℃ at a heating rate of ≤70℃ / h and held for 2-3 hours, and then cooled to room temperature. Special gas is used to protect against oxidation during the heat treatment process.

[0020] The heat treatment step in step 5 is as follows: the temperature is raised to 140-210℃ at a heating rate of ≤45℃ / h to preheat the part and hold it at that temperature, and then the temperature is raised to 500℃±25℃ at a heating rate of 30-50℃ / h and held for 3-4 hours. Special gas protection is used during the heat treatment process to prevent oxidation.

[0021] Furthermore, the lightweight material layer is made of 7075 aluminum, while the hard material layer is made of GCr15 bearing steel.

[0022] Beneficial effects: By combining hard material layers and lightweight material layers to form a lightweight structure, the weight of the cross bearing can be effectively reduced. At the same time, the lightweight material layer can be made of aluminum with good thermal conductivity, which can improve the thermal conductivity of the cross bearing and thus increase its service life. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of a cross bearing;

[0024] Figure 2 for Figure 1 A schematic diagram of the protrusion at point A in the middle;

[0025] Figure 3 This is a schematic diagram of the structure of the bearing outer ring blank after step 1.

[0026] Figure 4 This is a schematic diagram of the structure of the bearing inner ring blank after step 1.

[0027] Figure 5 This is a schematic diagram of the bearing outer ring after processing in step 7;

[0028] Figure 6 This is a schematic diagram of the bearing inner ring after processing in step 7. Detailed Implementation

[0029] like Figure 1 The illustration shows a lightweight cross-bearing for a harmonic reducer, comprising an inner bearing ring 1 and an outer bearing ring 2. Rollers are provided between the inner surface of the outer bearing ring 2 and the outer surface of the inner bearing ring 1. The outer bearing ring 2 and / or the inner bearing ring 1 adopt a lightweight structure. This embodiment takes the example of both the inner and outer bearing rings adopting a lightweight structure. The outer bearing ring 2 includes an outer layer of hard material 100 (e.g., steel). Figure 1 The mid-section line is the part filled with diagonal lines) and the lightweight material layer 200 located inside (e.g., aluminum alloy). Figure 1 (The mid-section line is the part filled with intersecting lines). The bearing inner ring 1 includes a hard material layer 100 on the outside and a light material layer 200 on the inside.

[0030] Specifically, the hard material layer 100 is located at the upper and lower ends and the inner side of the outer ring 2 of the bearing, and the light material layer 200 is located on the outer side and the middle of the outer ring 2 of the bearing; the hard material layer 100 is located at the upper and lower ends and the outer side of the inner ring 1 of the bearing, and the light material layer 200 is located on the inner side and the middle of the inner ring 1 of the bearing. In this way, the hard material layer 100 is set in the parts with greater stress, and the light material layer is used in the parts with less stress, so as to effectively reduce the weight of the cross bearing while ensuring that it has sufficient load-bearing capacity.

[0031] In addition, to increase the contact area and the clamping force between the two materials, ensuring that the two materials do not vibrate and break during operation of the cross bearing, the connection surface between the lightweight material layer 200 and the hard material layer 100 is irregularly shaped. The mating surface between the hard material layer 100 and the lightweight material layer 200 of the bearing outer ring 2 has multiple inclined grooves extending towards the lightweight material layer 200. Figure 2 As shown, the inner ring 1 of the bearing has a plurality of inclined protrusions 300 extending toward the lightweight material layer 200 on the mating surface of the hard material layer 100 and the lightweight material layer 200.

[0032] The above-mentioned lightweight cross bearing for harmonic reducers includes the following steps: Step 1, blank machining; according to the position of the lightweight structure, cavities for the composite lightweight material layer 200 are machined from the outer side of the outer ring 2 blank inward and / or from the inner side of the inner ring 1 blank outward. Irregular shapes are machined into the inner walls of the cavities for the composite lightweight material layer 200, and multiple inclined protrusions 300 extending towards the lightweight material layer 200 are also machined. Their main function is to increase the contact area between the aluminum alloy (aviation aluminum 7075) and the steel (GCr15) and to increase the clamping force between them, ensuring that the two materials do not vibrate and break during subsequent operation of the cross bearing; the machined outer ring 2 blank and inner ring 1 blank are respectively as shown in the figure below. Figure 3 , Figure 4 As shown, its inner circle has no steps and needs to meet the dimensions in the drawing. The top and bottom surfaces must be parallel, mainly to facilitate the placement of aluminum alloy material into the tooling later.

[0033] Step 2: Heat treat the processed blank to reduce the internal stress generated by turning. Since the blank is an irregular shape, excessively high heating and cooling rates will cause deformation of the blank's shape. Preferably, the heat treatment steps in this scheme are as follows: heat the room temperature to 300-350℃ at a heating rate of ≤150℃ / h, then heat it to 550-580℃ at a heating rate of ≤70℃ / h and hold it for 2-3 hours, and then cool it to room temperature. During the heat treatment process, a special gas is used to protect against oxidation, such as neutral nitrogen atmosphere with a purity of ≥99.9% (by volume) and an oxygen content of ≤50ppm. After the heat treatment, the bearing steel workpiece needs to be thoroughly cleaned of cutting fluid, iron filings, and oil stains. Ultrasonic cleaning can be used (cleaning temperature 40-60℃, time approximately 15-20 minutes) to avoid carbonization of oil stains during heat treatment, which can lead to surface defects.

[0034] Step 3: Check for defects on the surface of the blank; a portion of the blank can be sampled for inspection: fluorescent penetrant testing is used to mainly detect whether the blank has cracks or pores.

[0035] Step 4, Casting; Lightweight materials are injected into the blank through casting to combine hard and lightweight materials and form a lightweight material layer 200; Specifically, after the blank enters the casting workshop, it is cast using low-pressure casting. Before placing the blank into the casting machine, the blank body needs to be preheated to about 500℃ to ensure that the blank is heated evenly before being placed into the casting machine.

[0036] Step 5: Heat-treat the cast parts to eliminate the internal stress generated during casting. The heat treatment steps are as follows: preheat the parts to 140-210℃ at a heating rate of ≤45℃ / h and hold for about 2 hours. Then, heat the parts to 500℃±25℃ at a heating rate of 30-50℃ / h and hold for 3-4 hours. During the heat treatment, use a special gas to prevent oxidation. For example, a neutral atmosphere of nitrogen can be used with a purity of ≥99.9% (by volume) and an oxygen content of ≤50ppm.

[0037] Step 6: After casting is completed, quality inspection and performance verification are required. Once the verification is passed, the process proceeds to the next step.

[0038] Step 7: Turning; Machining the parts according to the design requirements of the bearing inner and outer rings. The finished bearing outer ring 2 and bearing inner ring 1 are as follows: Figure 5 , Figure 6 As shown.

[0039] Step 8: Perform a 200℃ heat treatment on the machined parts to eliminate cutting stress. The heat treatment process requires a neutral nitrogen atmosphere with a purity of ≥99.9% and an oxygen content of ≤50ppm.

[0040] Step 9: The subsequent processes include double-end face grinding, outer cylindrical grinding, inner cylindrical grinding, groove grinding, and groove ultra-precision grinding to grind the inner and outer rings to the required positions before assembly.

[0041] The cross-bearing manufactured using the above method is 33.8% lighter than the original cross-bearing of the same specifications. Due to its aluminum core, it has better thermal conductivity, resulting in superior heat transfer efficiency compared to traditional iron cross-bearings. In a comparative heating experiment, when both types of bearings were heated to 200°C and then naturally cooled to 20°C, the cooling time of the iron-aluminum composite material was halved compared to the all-iron material. Due to its excellent heat dissipation performance, its lifespan has now surpassed that of cross-bearing bearings made entirely of bearing steel, with an overall lifespan extension of approximately 20%.

[0042] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A lightweight cross-bearing for a harmonic reducer, comprising an inner bearing ring and an outer bearing ring, wherein rollers are provided between the inner surface of the outer bearing ring and the outer surface of the inner bearing ring, characterized in that: The bearing outer ring and / or the bearing inner ring adopt a lightweight structure. When the bearing outer ring adopts a lightweight structure, the bearing outer ring includes an outer hard material layer and an inner lightweight material layer. When the bearing inner ring adopts a lightweight structure, the bearing inner ring includes an outer hard material layer and an inner lightweight material layer.

2. The lightweight cross-bearing for a harmonic reducer according to claim 1, characterized in that: When the bearing outer ring adopts a lightweight structure, the hard material layer is located at the upper and lower ends and the inner side of the bearing outer ring, and the lightweight material layer is located on the outer side and the middle of the bearing outer ring; when the bearing inner ring adopts a lightweight structure, the hard material layer is located at the upper and lower ends and the outer side of the bearing inner ring, and the lightweight material layer is located on the inner side and the middle of the bearing inner ring.

3. The lightweight cross-bearing for a harmonic reducer according to claim 1, characterized in that: The connection surface between the lightweight material layer and the rigid material layer has an irregular shape.

4. A lightweight cross-bearing for a harmonic reducer according to claim 3, characterized in that: When the outer ring of the bearing adopts a lightweight structure, the mating surface of the hard material layer and the lightweight material layer of the outer ring of the bearing has a plurality of inclined protrusions extending toward the lightweight material layer; when the inner ring of the bearing adopts a lightweight structure, the mating surface of the hard material layer and the lightweight material layer of the inner ring of the bearing has a plurality of inclined protrusions extending toward the lightweight material layer.

5. A lightweight cross-bearing for a harmonic reducer according to claim 1, characterized in that: The hard material layer is made of steel, and the lightweight material layer is made of aluminum alloy.

6. A method for manufacturing a lightweight cross-bearing for a harmonic reducer according to any one of claims 1-5, characterized in that, It includes the following steps: Step 1, blank processing; depending on the location of the lightweight structure, process cavities for the composite lightweight material layer on the outer side of the outer ring blank of the ring bearing and / or the inner side of the inner ring blank of the ring bearing outward. Step 2: Perform heat treatment and surface treatment on the processed blank; Step 3: Inspect the surface of the blank for defects; Step 4, Casting; Lightweight materials are injected into the blank through casting to combine hard and lightweight materials and form a lightweight material layer. Step 5: Perform heat treatment on the cast parts; Step 6: Check whether the performance of the parts meets the requirements; Step 7: Turning machining; The parts are machined according to the design requirements of the bearing's inner and outer rings; Step 8: Perform heat treatment on the machined parts to eliminate cutting stress; Step 9: Grinding and assembly.

7. A method for machining a lightweight cross-bearing for a harmonic reducer according to claim 6, characterized in that: In step 1, the inner wall of the cavity used for the composite lightweight material layer is machined into an irregular shape, and multiple inclined protrusions extending toward the lightweight material layer are also machined.

8. A method for machining a lightweight cross-bearing for a harmonic reducer according to claim 6, characterized in that: The heat treatment steps in step 2 are as follows: the room temperature is raised to 300-350℃ at a heating rate of ≤150℃ / h, then raised to 550-580℃ at a heating rate of ≤70℃ / h and held for 2-3 hours, and then cooled to room temperature. Special gas protection is used during the heat treatment process to prevent oxidation. The heat treatment step in step 5 is as follows: the temperature is raised to 140-210℃ at a heating rate of ≤45℃ / h to preheat the part and hold it at that temperature, and then the temperature is raised to 500℃±25℃ at a heating rate of 30-50℃ / h and held for 3-4 hours. Special gas protection is used during the heat treatment process to prevent oxidation.

9. A method for machining a lightweight cross-bearing for a harmonic reducer according to claim 8, characterized in that: The lightweight material layer is made of 7075 aluminum, and the hard material layer is made of GCr15 bearing steel.

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