An Asymmetric Bearing Ring Machining Stock Design Method

Abstract

The present invention relates to a design method for machining stock allowance of an asymmetric bearing ring. Before heat treatment of the asymmetric bearing ring, the stock allowance of the ring is confirmed to improve the machining efficiency of mass production. The method includes the following steps: S1. Based on the stock allowance standard and the thermal expansion and contraction amount of the bearing ring in the same size range, confirm the test stock allowance, and determine the test machining process according to the test stock allowance; S2. Select a certain amount of test bearing rings for test machining, and record the stock allowance and ovality at the positions of the maximum wall thickness and the minimum wall thickness on the inner and outer surfaces of the test bearing rings before and after heat treatment; S3. Analyze and calculate the average thermal expansion and contraction amount and the maximum ovality at different wall thicknesses of the test pieces; S4. On the premise of ensuring that the machining stock allowance can be compatible with the position of the minimum thermal expansion and contraction amount and reducing the machining amount after heat treatment, design the formal stock allowance of the inner and outer surfaces of the bearing ring under the trend of thermal expansion and the trend of thermal contraction. Through this method, the overall material utilization rate is effectively improved, the machining stock allowance of the ring is reduced, the hot working efficiency is improved, and the production cost is reduced.

Description

Technical Field

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

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

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

[0004] To achieve the above purpose, the technical solution of a method for designing machining stock for an asymmetric bearing ring of the present invention is: a method for designing machining stock for an asymmetric bearing ring, including:

[0005] S1: Based on the stock standard and the expansion and contraction amount of the bearing ring of the same size segment during heat treatment, confirm the test stock, and determine the test machining process according to the test stock;

[0006] S2: Select a certain amount of test bearing rings for test machining, and record the stock and ovality at the positions of the maximum and minimum wall thicknesses on the inner and outer surfaces of the test bearing rings before and after heat treatment;

[0007] S3: Analyze the average expansion and contraction amount and the maximum ovality at different wall thicknesses of the test bearing rings;

[0008] S4: On the premise of ensuring that the machining stock can be compatible with the position with the minimum expansion and contraction amount and reducing the machining amount after heat treatment, design the formal stock on the inner and outer surfaces of the bearing ring under the heat treatment expansion trend and the heat treatment contraction trend respectively.

[0009] Furthermore, in S2, ensure that the taper and ovality of the test bearing rings machined by soft turning before heat treatment are as close to zero as possible.

[0010] Furthermore, the designed formal allowance ensures that the outer peripheral surface of the bearing ring after heat treatment is a cylindrical surface.

[0011] Furthermore, in S4, under the expanding trend:

[0012] The formal allowance on the outer surface at the maximum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance - the average expansion and contraction amount at the maximum wall thickness;

[0013] The formal allowance on the inner surface at the maximum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance + the average expansion and contraction amount at the maximum wall thickness;

[0014] The formal allowance on the outer surface at the minimum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance - the average expansion and contraction amount at the minimum wall thickness;

[0015] The formal allowance on the inner surface at the minimum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance + the average expansion and contraction amount at the minimum wall thickness.

[0016] Furthermore, in S4, under the shrinking trend:

[0017] The formal allowance on the outer surface at the maximum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance + the average expansion and contraction amount at the maximum wall thickness;

[0018] The formal allowance on the inner surface at the maximum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance - the average expansion and contraction amount at the maximum wall thickness;

[0019] The formal allowance on the outer surface at the minimum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance + the average expansion and contraction amount at the minimum wall thickness;

[0020] The formal allowance on the inner surface at the minimum wall thickness = the maximum ovality of the test batch + the fine grinding allowance + the finish grinding allowance - the average expansion and contraction amount at the minimum wall thickness.

[0021] The present invention pioneeringly provides a design method for the machining allowance of an asymmetric bearing ring. By using the test allowance confirmed based on the allowance standard and the heat treatment expansion and contraction amount of the bearing rings in the same size segment to conduct test machining on a small batch of bearing rings, measuring the allowances and ovalities at the maximum and minimum wall thickness positions of the inner and outer surfaces of the test bearing rings before and after heat treatment, then obtaining the average expansion and contraction amount and the maximum ovality, and designing different allowances for different wall thicknesses of the asymmetric bearing ring according to the average expansion and contraction amount and the maximum ovality, the machining allowance can be made to be compatible with the position of the minimum expansion and contraction amount while minimizing the machining amount after heat treatment as much as possible. The beneficial effects are that through this method, the overall material utilization rate is effectively improved, the machining allowance of the ring is reduced, the hot working efficiency is improved, and the production cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the allowance design for the traditional heat treatment expanding trend.

[0023] Figure 2 Schematic diagram of allowance design under the trend of heat treatment expansion when adopting the asymmetric bearing ring processing allowance design method of the present invention;

[0024] Figure 3 Schematic diagram of allowance design under the shrinking trend of traditional heat treatment;

[0025] Figure 4 Schematic diagram of allowance design under the shrinking trend of heat treatment when adopting the asymmetric bearing ring processing allowance design method of the present invention;

[0026] Figure 5 Analysis table of size records at different wall thickness positions of the outer diameter of the bearing ring before and after heat treatment under the expansion trend when adopting the asymmetric bearing ring processing allowance design method of the present invention;

[0027] Figure 6 Analysis table of size records at different wall thickness positions of the outer raceway of the bearing ring before and after heat treatment under the expansion trend when adopting the asymmetric bearing ring processing allowance design method of the present invention;

[0028] Figure 7 Analysis table of size records at different wall thickness positions of the outer diameter of the bearing ring before and after heat treatment under the shrinking trend when adopting the asymmetric bearing ring processing allowance design method of the present invention;

[0029] Figure 8 Analysis table of size records at different wall thickness positions of the outer raceway of the bearing ring before and after heat treatment under the shrinking trend when adopting the asymmetric bearing ring processing allowance design method of the present invention.

[0030] In the figure: 1. Finished product size of the ring; 2. Size of the soft-turned finished product before heat treatment; 3. Size after heat treatment. Detailed implementation mode

[0031] The features and performance of the present invention are further described in detail below in conjunction with embodiments.

[0032] An asymmetric bearing ring processing allowance design method of the present invention mainly aims at the problems of low overall material utilization rate, large processing allowance, low processing efficiency and high production cost during the heat treatment of asymmetric bearing rings. An asymmetric bearing ring processing allowance design method of the present invention formulates the bearing allowances at different wall thicknesses before heat treatment according to the heat treatment expansion and contraction laws at different wall thicknesses of the bearing ring, effectively improving the overall material utilization rate, reducing the processing allowance of the ring, improving the hot processing efficiency and reducing the production cost.

[0033] Based on the above main concepts, different embodiments are provided below for illustration.

[0034] In Example 1, a tapered roller bearing 32234 outer ring made of steel Gr15SiMn - GB / T18254 material was selected for the allowance design of the bearing ring. This material has an expanding trend during heat treatment.

[0035] According to the allowance standard and the expansion and contraction amount of the bearing ring during heat treatment in the same size segment, the end face test allowance was determined to be 0.5 mm, the outer diameter test allowance was 0.4 mm, and the raceway allowance design was 0.65 mm. Further, according to the established test process, a small batch of test processing was carried out. Preferably, in order to ensure the accuracy and effectiveness of the data, before heat treatment, the taper and ovality of the bearing ring should be approximately zero after soft turning.

[0036] As Figure 5 shown, it can be seen the dimensions of the bearing ring outer diameter before heat treatment and the allowances and ovality at the positions of the maximum and minimum wall thicknesses of the inner and outer surfaces after heat treatment; further, by analyzing the detection data in Figure 5 , it can be known that the maximum ovality of the outer surface of the bearing ring is 0.35 mm, the minimum ovality is 0.03 mm, the average expansion and contraction amount at the maximum wall thickness is 0.46 mm, the average expansion and contraction amount at the minimum wall thickness is 0.36 mm, and the average taper is 0.1 mm.

[0037] The fine grinding allowance design for the bearing ring in the similar size segment of this type of bearing is 0.2 mm, and the finish grinding allowance design is 0.1 mm.

[0038] Then, based on the above test data:

[0039] The formal allowance design for the outer diameter allowance at the maximum wall thickness is: the maximum ovality of the test batch 0.35 mm + fine grinding allowance 0.2 mm + finish grinding allowance 0.1 mm - average expansion and contraction amount at the maximum wall thickness 0.46 = 0.19 mm.

[0040] The formal allowance design for the outer diameter allowance at the minimum wall thickness is: the maximum ovality of the test batch 0.35 mm + fine grinding allowance 0.2 mm + finish grinding allowance 0.1 mm - average expansion and contraction amount at the minimum wall thickness 0.36 = 0.29 mm.

[0041] Through the above calculations, the formal allowances for the outer diameter of the outer ring of the tapered roller bearing 32234 bearing ring are obtained. The allowance design at the maximum wall thickness is 0.19 mm, and the allowance design at the minimum wall thickness is 0.29 mm.

[0042] As Figure 6 shown, it can be seen the dimensions of the outer raceway of the bearing ring before heat treatment and the allowances and ovality at the positions of the maximum and minimum wall thicknesses of the inner and outer surfaces after heat treatment; further, for Figure 6By analyzing the detection data, it can be known that the maximum ellipse of the outer raceway of the bearing ring is 0.32 mm, the minimum ellipse is 0.02 mm, the average expansion and contraction amount at the maximum wall thickness is 0.35 mm, the average expansion and contraction amount at the minimum wall thickness is 0.25 mm, and the average taper is 0.1 mm.

[0043] The formal allowance design for the outer raceway allowance at the maximum wall thickness is: the maximum ellipse of the test batch 0.32 mm + fine grinding allowance 0.2 mm + finish grinding allowance 0.1 mm + average expansion and contraction amount at the maximum wall thickness 0.35 = 0.97 mm.

[0044] The formal allowance design for the outer raceway allowance at the minimum wall thickness is: the maximum ellipse of the test batch 0.32 mm + fine grinding allowance 0.2 mm + finish grinding allowance 0.1 mm + average expansion and contraction amount at the minimum wall thickness 0.25 = 0.87 mm.

[0045] Through the above calculations, the formal allowances for the outer raceways of the bearing rings of the tapered roller bearing 32234 are obtained. The allowance design for the maximum wall thickness is 0.97 mm, and the allowance design for the minimum wall thickness is 0.87 mm.

[0046] In the case of an expanding trend, in traditional heat treatment, such as Figure 1 shown, it can be known that the soft turning finished product size 2 of the bearing ring before heat treatment. After heat treatment, there are still many allowances when comparing the size 3 after heat treatment and the finished product size 1 of the ring, and a relatively large taper is generated, which is not conducive to the clamping and machining of the bearing. Through the asymmetric bearing ring machining allowance design method of the present invention, the allowances at different wall thicknesses are calculated. After heat treatment, as Figure 2 shown, the machining allowance is reduced, the taper change amount is improved, and the outer side surface of the bearing ring is close to a cylindrical surface, which is convenient for clamping.

[0047] In Example 2, a tapered roller bearing 338R / 1270-A outer ring made of steel G20Cr2Ni4A-XYGN3284.1 material is selected for the bearing ring allowance design. This material shows a shrinking trend during heat treatment.

[0048] According to the allowance standard and the heat treatment expansion and contraction amount of the bearing ring in the same size segment, the end face test allowance is determined to be 4.5 mm, the outer diameter test allowance is 5 mm, and the raceway allowance design is 3 mm. Further, according to the formulated test process, small batch test machining is carried out. Preferably, in order to ensure the accuracy and effectiveness of the data, before heat treatment, the soft turning process should make the taper and ellipse of the bearing ring approximately equal to zero.

[0049] As Figure 7 shown, it can be known the size of the outer diameter of the bearing ring before heat treatment and the allowances and ellipses at the maximum and minimum wall thickness positions of the inner and outer surfaces after heat treatment; further, for Figure 7By analyzing the detection data, it can be known that the maximum ovality of the outer surface of the bearing ring is 2.1 mm, the minimum ovality is 0.5 mm, the average expansion and contraction amount at the maximum wall thickness is 1.6 mm, the average expansion and contraction amount at the minimum wall thickness is 1.2 mm, and the average taper is 0.4 mm.

[0050] For this type of bearing ring, the fine grinding stock allowance in the similar size range is designed to be 0.3 mm, and the finish grinding stock allowance is designed to be 0.2 mm.

[0051] Then, based on the above test data:

[0052] The official stock allowance design for the outer diameter at the maximum wall thickness is: the maximum ovality of the test batch 2.1 mm + fine grinding stock allowance 0.3 mm + finish grinding stock allowance 0.2 mm + average expansion and contraction amount at the maximum wall thickness 1.6 mm = 4.2 mm.

[0053] The official stock allowance design for the outer diameter at the minimum wall thickness is: the maximum ovality of the test batch 2.1 mm + fine grinding stock allowance 0.3 mm + finish grinding stock allowance 0.2 mm + average expansion and contraction amount at the minimum wall thickness 1.2 mm = 3.8 mm.

[0054] Through the above calculations, the official stock allowance for the outer ring outer diameter of the tapered roller bearing 338R / 1270 - A bearing ring is obtained. The stock allowance design at the maximum wall thickness is 4.2 mm, and the stock allowance design at the minimum wall thickness is 3.8 mm.

[0055] As Figure 8 shown, it can be known the dimensions of the outer raceway of the bearing ring before heat treatment and the stock allowance and ovality at the maximum and minimum wall thickness positions of the inner and outer surfaces after heat treatment; further, by analyzing the detection data in Figure 8 it can be known that the maximum ovality of the outer raceway of the bearing ring is 1.8 mm, the minimum ovality is 0.4 mm, the average expansion and contraction amount at the maximum wall thickness is 1.3 mm, the average expansion and contraction amount at the minimum wall thickness is 1.05 mm, and the average taper is 0.25 mm.

[0056] The official stock allowance design for the outer raceway at the maximum wall thickness is: the maximum ovality of the test batch 1.8 mm + fine grinding stock allowance 0.3 mm + finish grinding stock allowance 0.2 mm - average expansion and contraction amount at the maximum wall thickness 1.3 = 1 mm.

[0057] The official stock allowance design for the outer raceway at the minimum wall thickness is: the maximum ovality of the test batch 1.8 mm + fine grinding stock allowance 0.3 mm + finish grinding stock allowance 0.2 mm - average expansion and contraction amount at the minimum wall thickness 1.05 = 1.25 mm.

[0058] Through the above calculations, the official stock allowance for the outer raceway of the tapered roller bearing 338R / 1270 - A bearing ring is obtained. The stock allowance design at the maximum wall thickness is 1 mm, and the stock allowance design at the minimum wall thickness is 1.25 mm.

[0059] In the shrinking trend, in traditional heat treatment, such as Figure 3 shown, it can be seen that the soft turning finished product size 2 of the bearing ring before heat treatment, after heat treatment, there is still a lot of margin compared with the size 3 after heat treatment and the finished product size 1 of the ring, and a large taper is generated, which is not conducive to the clamping and processing of the bearing. Through the design method of machining allowance for the asymmetric bearing ring of the present invention, the allowances at different wall thicknesses are calculated. After heat treatment, as Figure 4 shown, the machining allowance is reduced, the taper change amount is improved, and the outer side surface of the bearing ring is close to a cylindrical surface, which is convenient for clamping.

[0060] Before heat treatment, the design method of machining allowance for the asymmetric bearing ring of the present invention effectively improves the taper change amount of the asymmetric bearing ring after heat treatment by designing different allowances at different wall thicknesses of the asymmetric bearing ring. Through this processing method, the machining allowance is effectively reduced, and the processing efficiency under the mass production of the asymmetric bearing ring is improved.

[0061] The above 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 is subject to the claims. All equivalent structural changes made by using the description and drawings of the present invention should, by the same token, 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; Under the trend of increasing: 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 increase and decrease 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 allowance for fine grinding + the allowance for final grinding + the average expansion and contraction at the minimum wall thickness; 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.

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.

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