Design method for machining allowance of asymmetric bearing ring

Abstract

The invention relates to a design method for machining allowance of an asymmetric bearing ring, and the machining efficiency of batch production is improved by confirming the allowance of the ring before heat treatment of the asymmetric bearing ring. Comprising the following steps: S1, determining a test allowance based on an allowance standard and a heat treatment expansion and shrinkage amount of a bearing ring of the same size section, and determining a test processing technology according to the test allowance; s2, selecting a certain amount of test bearing rings for test processing, and recording the allowance and ellipse at the maximum wall thickness and minimum wall thickness positions of the inner and outer surfaces before and after heat treatment of the test bearing rings; s3, analyzing and calculating the average expansion and contraction amount and the maximum ellipse at different wall thicknesses of the test piece; and S4, on the premise that it is guaranteed that the machining allowance can be compatible with the position with the minimum expansion and contraction amount, and the machining amount after heat treatment is reduced, the formal allowance of the inner surface and the outer surface of the bearing ring under the heat treatment expansion trend and the heat treatment contraction trend is designed. By means of the method, the overall material utilization rate is effectively increased, the ferrule machining allowance is reduced, the hot working efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of bearing production, and in particular to a method for designing machining allowance of an asymmetric bearing ring. Background Art

[0002] At present, the traditional bearing ring process allowance design method is to add design allowance in the radial direction without considering the symmetry of the ring wall thickness. However, for asymmetric bearing rings, such as tapered roller bearing rings, the wall thickness at both ends is different due to the different inner diameters of the two sides. During the heat treatment process, there are inconsistent expansion and contraction amounts at different wall thickness positions, and the expansion and contraction amounts at large wall thickness positions are significantly greater than the expansion and contraction amounts at small wall thickness positions. If the traditional radial allowance design method is adopted, although it can meet production needs to a certain extent, a large taper will be generated at both ends of the bearing ring after heat treatment, which is not conducive to bearing clamping and processing. In addition, due to the inconsistent expansion and contraction amounts at different wall thicknesses, the process allowance design needs to be compatible with the positions with small expansion and contraction amounts, and the overall allowance design needs to be increased. In order to ensure the quality of the finished product, a large processing allowance will not only affect the processing efficiency, but also increase the production cost. Summary of the invention

[0003] The object of the present invention is to provide a method for designing machining allowance of an asymmetric bearing ring, so as to solve the problem of low machining efficiency and high production cost caused by large machining allowance when machining an asymmetric bearing ring.

[0004] To achieve the above-mentioned purpose, the technical solution of a method for designing a machining allowance for an asymmetric bearing ring of the present invention is: a method for designing a machining allowance for an asymmetric bearing ring, comprising: S1: Confirm the test reserve based on the reserve standard and the shrinkage of the bearing rings of the same size segment during heat treatment, and determine the test processing technology according to the test reserve; S2: Select a certain amount of test bearing rings for test processing, and record the allowance and ellipse at the maximum wall thickness and minimum wall thickness positions on the inner and outer surfaces of the test bearing rings before and after heat treatment; S3: Analyze the average expansion and contraction and the maximum ellipse of the test bearing ring at different wall thicknesses; S4: Under the premise of ensuring that the processing allowance can be compatible with the minimum position of expansion and shrinkage and reducing the processing amount after heat treatment, the formal allowances of the inner and outer surfaces of the bearing rings are designed under the trend of heat treatment expansion and heat treatment reduction.

[0005] Furthermore, in S2, it is ensured that the taper and ellipse of the test bearing ring processed by soft turning before heat treatment are as close to zero as possible.

[0006] Furthermore, the designed formal allowance satisfies that the outer peripheral surface of the bearing ring after heat treatment is a cylindrical surface.

[0007] Furthermore, in S4, under the rising trend: The formal allowance of the outer surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding - the average expansion and contraction at the maximum wall thickness; The formal allowance of the inner surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the maximum wall thickness; The formal allowance of the outer surface at the minimum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding - the average expansion and contraction at the minimum wall thickness; The formal allowance of the inner surface at the minimum wall thickness = the maximum ellipse of the test batch + the fine grinding allowance + the final grinding allowance + the average expansion and contraction at the minimum wall thickness.

[0008] Furthermore, in S4, under the shrinking trend: The formal allowance of the outer surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the maximum wall thickness; The formal allowance of the inner surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding - the average expansion and contraction at the maximum wall thickness; The formal allowance of the outer surface at the minimum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the minimum wall thickness; The formal allowance of the inner surface at the minimum wall thickness = the maximum ellipse of the test batch + the fine grinding allowance + the final grinding allowance - the average expansion and contraction at the minimum wall thickness.

[0009] The present invention provides a pioneering method for designing the machining allowance of asymmetric bearing rings. A small batch of bearing rings are subjected to test machining based on the test allowance confirmed by the allowance standard and the shrinkage of the same size segment bearing rings during heat treatment. The allowance and ellipse at the maximum wall thickness and minimum wall thickness positions on the inner and outer surfaces of the test bearing rings before and after heat treatment are measured. Then, the average shrinkage and maximum ellipse are obtained. Different allowances are designed for different wall thicknesses of the asymmetric bearing rings according to the average shrinkage and maximum ellipse, so that the machining allowance can be compatible with the position with the minimum shrinkage while minimizing the machining amount after heat treatment. The beneficial effect is that the overall material utilization rate is effectively improved through this method, the machining allowance of the rings is reduced, the heat processing efficiency is improved, and the production cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of the design of the reserve for the traditional heat treatment trend increase; Figure 2 It is a schematic diagram of the reserve design under the heat treatment expansion trend when the asymmetric bearing ring processing reserve design method of the present invention is adopted; Figure 3 Schematic diagram of the design of the reserve for reducing the trend of traditional heat treatment; Figure 4It is a schematic diagram of the reserve design under the trend of heat treatment reduction when the asymmetric bearing ring processing reserve design method of the present invention is adopted; Figure 5 When the asymmetric bearing ring processing allowance design method of the present invention is adopted, the dimension record analysis table of the bearing ring outer diameter at different wall thickness positions before and after heat treatment under the increasing trend; Figure 6 When the asymmetric bearing ring machining allowance design method of the present invention is adopted, under the trend of increasing, the dimension record analysis table of different wall thickness positions of the outer raceway of the bearing ring before and after heat treatment; Figure 7 When the asymmetric bearing ring machining allowance design method of the present invention is adopted, the dimension record analysis table of the different wall thickness positions of the bearing ring outer diameter before and after heat treatment under the shrinking trend; Figure 8 When the asymmetric bearing ring processing allowance design method of the present invention is adopted, the dimension record analysis table of different wall thickness positions of the outer raceway of the bearing ring before and after heat treatment is provided under the shrinking trend.

[0011] In the figure: 1. Dimensions of the finished ring; 2. Dimensions of the finished ring before heat treatment; 3. Dimensions after heat treatment. DETAILED DESCRIPTION

[0012] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0013] The present invention provides a method for designing the machining allowance of an asymmetric bearing ring, which is mainly aimed at the problems of low overall material utilization, large machining allowance, low machining efficiency and high production cost during heat treatment of an asymmetric bearing ring. The present invention provides a method for designing the machining allowance of an asymmetric bearing ring, which is based on the expansion and contraction law of different wall thicknesses of the bearing ring during heat treatment, and formulates the bearing allowances at different wall thicknesses before heat treatment, thereby effectively improving the overall material utilization, reducing the machining allowance of the ring, improving the heat processing efficiency and reducing the production cost.

[0014] Based on the above main concepts, different embodiments are provided below for illustration.

[0015] In Example 1, the outer ring of the tapered roller bearing 32234 made of steel Gr15SiMn-GB / T18254 material is selected for bearing ring reserve design. This material tends to expand during heat treatment.

[0016] According to the allowance standard and the shrinkage of the same size section bearing ring heat treatment, the end face test allowance is determined to be 0.5mm, the outer diameter test allowance is 0.4mm, and the raceway allowance is designed to be 0.65mm. Further, according to the established test process, a small batch of test processing is carried out. Preferably, in order to ensure the accuracy and validity of the data, before heat treatment, the soft turning process should make the taper and ellipse of the bearing ring approximately equal to zero.

[0017] like Figure 5 As shown in FIG. 1 , it can be seen that the outer diameter of the bearing ring before heat treatment and the allowance and ellipse of the maximum wall thickness and minimum wall thickness position of the inner and outer surfaces after heat treatment; further, Figure 5 Analyzing the test data in, it can be seen that the maximum ellipse of the outer surface of the bearing ring is 0.35mm, the minimum ellipse is 0.03mm, the average expansion and contraction at the maximum wall thickness is 0.46mm, the average expansion and contraction at the minimum wall thickness is 0.36mm, and the average taper is 0.1mm.

[0018] The fine grinding allowance for similar size segments of this type of bearing rings is designed to be 0.2mm, and the final grinding allowance is designed to be 0.1mm.

[0019] Then according to the above test data: The formal allowance design for the outer diameter at the maximum wall thickness is: the maximum ellipse of the test batch 0.35mm + fine grinding allowance 0.2mm + final grinding allowance 0.1mm - average expansion and contraction at the maximum wall thickness 0.46 = 0.19mm.

[0020] The formal allowance for the outer diameter at the minimum wall thickness is designed as: the maximum ellipse of the test batch 0.35mm + fine grinding allowance 0.2mm + final grinding allowance 0.1mm - average expansion and contraction at the minimum wall thickness 0.36 = 0.29mm.

[0021] Through the above calculation, the formal allowance for the outer diameter of the outer ring of the tapered roller bearing 32234 bearing ring is designed to be 0.19mm at the maximum wall thickness and 0.29mm at the minimum wall thickness.

[0022] like Figure 6 As shown in the figure, it can be seen that the size of the outer raceway of the bearing ring before heat treatment and the allowance and ellipse of the maximum wall thickness and minimum wall thickness position of the inner and outer surfaces after heat treatment; further, Figure 6 Analyzing the test data in, it can be seen that the maximum ellipse of the outer raceway of the bearing ring is 0.32mm, the minimum ellipse is 0.02mm, the average expansion and contraction at the maximum wall thickness is 0.35mm, the average expansion and contraction at the minimum wall thickness is 0.25mm, and the average taper is 0.1mm.

[0023] The formal allowance design for the outer raceway at the maximum wall thickness is: the maximum ellipse of the test batch 0.32mm + fine grinding allowance 0.2mm + final grinding allowance 0.1mm + average expansion and contraction at the maximum wall thickness 0.35 = 0.97mm.

[0024] The formal allowance design for the outer raceway at the minimum wall thickness is: the maximum ellipse of the test batch 0.32mm + fine grinding allowance 0.2mm + final grinding allowance 0.1mm + average expansion and contraction at the minimum wall thickness 0.25 = 0.87mm.

[0025] Through the above calculation, the formal allowance of the outer raceway of the tapered roller bearing 32234 bearing ring can be obtained. The allowance at the maximum wall thickness is designed to be 0.97mm, and the allowance at the minimum wall thickness is designed to be 0.87mm.

[0026] Under the rising trend, in traditional heat treatment, such as Figure 1 As shown in the figure, it can be seen that the finished size of the bearing ring before heat treatment is 2. After heat treatment, there is still a lot of margin compared to the finished size 3 after heat treatment and the finished size 1 of the ring, and a large taper is generated, which is not conducive to bearing clamping and processing. The asymmetric bearing ring processing allowance design method of the present invention calculates the allowance at different wall thicknesses. After heat treatment, as shown in Figure 2 As shown, the machining allowance is reduced, the taper variation is improved, and the outer side of the bearing ring is close to the cylindrical surface, which is convenient for clamping.

[0027] In Example 2, the outer ring of the tapered roller bearing 338R / 1270-A made of steel G20Cr2Ni4A-XYGN3284.1 material is selected for bearing ring reserve design. This material tends to shrink during heat treatment.

[0028] According to the allowance standard and the shrinkage of the same size section bearing ring heat treatment, the end face test allowance is determined to be 4.5mm, the outer diameter test allowance is 5mm, and the raceway allowance is designed to be 3mm. Further, according to the established test process, a small batch of test processing is carried out. Preferably, in order to ensure the accuracy and validity of the data, before heat treatment, the soft turning process should make the taper and ellipse of the bearing ring approximately equal to zero.

[0029] like Figure 7 As shown in FIG. 1 , it can be seen that the outer diameter of the bearing ring before heat treatment and the allowance and ellipse of the maximum wall thickness and minimum wall thickness position of the inner and outer surfaces after heat treatment; further, Figure 7 Analyzing the test data in, it can be seen that the maximum ellipse of the outer surface of the bearing ring is 2.1mm, the minimum ellipse is 0.5mm, the average expansion and contraction at the maximum wall thickness is 1.6mm, the average expansion and contraction at the minimum wall thickness is 1.2mm, and the average taper is 0.4mm.

[0030] The fine grinding allowance for similar size segments of this type of bearing rings is designed to be 0.3mm, and the final grinding allowance is designed to be 0.2mm.

[0031] Then according to the above test data: The formal allowance design for the outer diameter at the maximum wall thickness is: the maximum ellipse of the test batch 2.1mm + fine grinding allowance 0.3mm + final grinding allowance 0.2mm + average expansion and contraction at the maximum wall thickness 1.6mm = 4.2mm.

[0032] The formal allowance for the outer diameter at the minimum wall thickness is designed as: the maximum ellipse of the test batch 2.1mm + fine grinding allowance 0.3mm + final grinding allowance 0.2mm + average expansion and contraction at the minimum wall thickness 1.2mm = 3.8mm.

[0033] Through the above calculation, the formal allowance for the outer diameter of the outer ring of the tapered roller bearing 338R / 1270-A bearing ring is designed to be 4.2mm at the maximum wall thickness and 3.8mm at the minimum wall thickness.

[0034] like Figure 8 As shown in the figure, it can be seen that the size of the outer raceway of the bearing ring before heat treatment and the allowance and ellipse of the maximum wall thickness and minimum wall thickness position of the inner and outer surfaces after heat treatment; further, Figure 8 Analyzing the test data in, it can be seen that the maximum ellipse of the outer raceway of the bearing ring is 1.8mm, the minimum ellipse is 0.4mm, the average expansion and contraction at the maximum wall thickness is 1.3mm, the average expansion and contraction at the minimum wall thickness is 1.05mm, and the average taper is 0.25mm.

[0035] The formal allowance design for the outer raceway at the maximum wall thickness is: the maximum ellipse of the test batch 1.8mm + fine grinding allowance 0.3mm + final grinding allowance 0.2mm - average expansion and contraction at the maximum wall thickness 1.3 = 1mm.

[0036] The formal allowance design for the outer raceway at the minimum wall thickness is: the maximum ellipse of the test batch 1.8mm + fine grinding allowance 0.3mm + final grinding allowance 0.2mm - average expansion and contraction at the minimum wall thickness 1.05 = 1.25mm.

[0037] Through the above calculation, the formal allowance of the outer raceway of the tapered roller bearing 338R / 1270-A bearing ring can be obtained. The allowance at the maximum wall thickness is designed to be 1mm, and the allowance at the minimum wall thickness is designed to be 1.25mm.

[0038] Under the shrinking trend, in traditional heat treatment, such as Figure 3As shown in the figure, it can be seen that the finished size of the bearing ring before heat treatment is 2. After heat treatment, there is still a lot of margin compared to the finished size 3 after heat treatment and the finished size 1 of the ring, and a large taper is generated, which is not conducive to bearing clamping and processing. The asymmetric bearing ring processing allowance design method of the present invention calculates the allowance at different wall thicknesses. After heat treatment, as shown in Figure 4 As shown, the machining allowance is reduced, the taper variation is improved, and the outer side of the bearing ring is close to the cylindrical surface, which is convenient for clamping.

[0039] The method for designing machining allowance for asymmetric bearing rings of the present invention designs different allowances for different wall thicknesses of the asymmetric bearing rings before heat treatment, thereby effectively improving the taper change of the asymmetric bearing rings after heat treatment. This machining method effectively reduces the machining allowance and improves the machining efficiency of asymmetric bearing rings in mass production.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A method for designing machining allowance of an asymmetric bearing ring, characterized in that: include: S1: Confirm the test reserve based on the reserve standard and the shrinkage of the bearing rings of the same size segment during heat treatment, and determine the test processing technology according to the test reserve; S2: Select a certain amount of test bearing rings for test processing, and record the allowance and ellipse at the maximum wall thickness and minimum wall thickness positions on the inner and outer surfaces of the test bearing rings before and after heat treatment; S3: Analyze the average expansion and contraction and the maximum ellipse of the test bearing ring at different wall thicknesses; S4: Under the premise of ensuring that the processing allowance can be compatible with the minimum position of expansion and contraction and reducing the processing amount after heat treatment, the formal allowances of the inner and outer surfaces of the bearing rings are designed under the trend of heat treatment expansion and heat treatment contraction respectively.

2. The method for designing the machining allowance of an asymmetric bearing ring according to claim 1, characterized in that: In S2, it is ensured that the taper and ellipse of the test bearing rings soft turned before heat treatment are as close to zero as possible.

3. The method for designing the machining allowance of an asymmetric bearing ring according to claim 1, characterized in that: The formal allowance designed is to ensure that the outer peripheral surface of the bearing ring is a cylindrical surface after heat treatment.

4. The method for designing the machining allowance of an asymmetric bearing ring according to claim 1, 2 or 3, characterized in that: In S4, under the rising trend: The formal allowance of the outer surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding - the average expansion and contraction at the maximum wall thickness; The formal allowance of the inner surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the maximum wall thickness; The formal allowance of the outer surface at the minimum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding - the average expansion and contraction at the minimum wall thickness; The formal allowance of the inner surface at the minimum wall thickness = the maximum ellipse of the test batch + the fine grinding allowance + the final grinding allowance + the average expansion and contraction at the minimum wall thickness.

5. The method for designing machining allowance of an asymmetric bearing ring according to claim 1, 2 or 3, characterized in that: In S4, under the shrinking trend: The formal allowance of the outer surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the maximum wall thickness; The formal allowance of the inner surface at the maximum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding - the average expansion and contraction at the maximum wall thickness; The formal allowance of the outer surface at the minimum wall thickness = the maximum ellipse of the test batch + the allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the minimum wall thickness; The formal allowance of the inner surface at the minimum wall thickness = the maximum ellipse of the test batch + the fine grinding allowance + the final grinding allowance - the average expansion and contraction at the minimum wall thickness.

Images