A processing method of a thin-wall bearing outer ring

Abstract

This invention discloses a method for machining a thin-walled bearing outer ring, comprising the following steps: forging; annealing; lathe machining; quenching; and tempering. This method, through quenching and tempering processes, ensures a uniform and stable microstructure of the thin-walled bearing outer ring, contributing to improved mechanical strength and toughness. In particular, the long-term water quenching following a single oil quenching simultaneously achieves aging treatment, further enhancing the mechanical properties and dimensional stability of the thin-walled bearing outer ring. The process design of this invention is scientifically sound, creatively simplifying the machining process and reducing the machining cycle.

Description

Technical Field

[0001] This invention relates to the field of bearing processing technology, and in particular to a method for processing the outer ring of a thin-walled bearing. Background Technology

[0002] A bearing typically consists of an inner ring, an outer ring, balls, and a ball cage that separates the balls between the inner and outer rings. With technological advancements and the need for energy conservation and emission reduction, thin-walled bearings are finding increasing applications. The outer ring plays a crucial role in the overall structure of a thin-walled bearing, serving as a key component in maintaining its structure and performance, and therefore requires excellent strength and resistance to deformation.

[0003] Current methods for machining thin-walled bearing outer rings almost always require quenching and tempering between each machining step. This not only makes the entire machining process extremely cumbersome but also results in excessively long processing cycles, low production efficiency, and high energy consumption. Furthermore, thin-walled bearing outer rings produced by existing methods suffer from surface oxidation due to repeated quenching and tempering, and their resistance to deformation still needs further improvement. Summary of the Invention

[0004] This invention provides a method for machining thin-walled bearing outer rings, thereby solving the aforementioned problems in the machining of thin-walled bearing outer rings in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for machining a thin-walled bearing outer ring, comprising the following steps:

[0006] (1) Forging treatment: Hot forging treatment is performed on the bar stock for the outer ring of the thin-walled bearing;

[0007] (2) Annealing treatment: The forged bar stock in step (1) is placed in an annealing furnace for annealing treatment;

[0008] (3) Lathe machining: The bar stock after annealing in step (2) is shot blasted, cut and end face ground in sequence to obtain the thin-walled bearing outer ring semi-finished product;

[0009] (4) Quenching treatment: The thin-walled bearing outer ring semi-finished product obtained in step (3) is placed in a heating furnace with inert gas continuously passed through for heating. After heating, it is taken out directly and quickly put into oil for one oil quenching treatment. After the first oil quenching, the thin-walled bearing outer ring semi-finished product is immersed in constant temperature water and kept at a constant temperature for 3 to 10 hours for water quenching and aging treatment. Then, after the water temperature is cooled to below 100℃, it is taken out and air-dried.

[0010] (5) Tempering treatment: The thin-walled bearing outer ring semi-finished product taken out and dried in step (4) is placed in a tempering furnace with inert gas continuously passed through it for tempering treatment to obtain the thin-walled bearing outer ring.

[0011] In a preferred embodiment of the present invention, in step (1), the temperature of the hot forging treatment is 850-950°C.

[0012] In a preferred embodiment of the present invention, in step (2), the annealing process conditions are as follows: first, the temperature is kept constant in an annealing furnace at 750-820°C for 0.5-2 hours, then the temperature is reduced to 600°C at a rate of 30-40°C / min, and then the furnace is removed and cooled to room temperature.

[0013] In a preferred embodiment of the present invention, step (3) further includes machining an inner raceway on one side of the cut bar stock.

[0014] In a preferred embodiment of the present invention, in step (4), the heating process conditions are: heating temperature of 820-850°C, and constant temperature for 80-90 minutes.

[0015] In a preferred embodiment of the present invention, in step (4), the process conditions for the first oil quenching are: oil temperature 260-330°C, time 50-70 min.

[0016] In a preferred embodiment of the present invention, in step (4), the temperature of the clean water is 150-200°C.

[0017] In a preferred embodiment of the present invention, in step (5), the tempering process conditions are: 160-180°C for 1-3 hours.

[0018] In a preferred embodiment of the present invention, the inert gas is nitrogen.

[0019] In a preferred embodiment of the present invention, the rod is a GCr16 high-carbon chromium rod.

[0020] The beneficial effects of this invention are as follows: The processing method for thin-walled bearing outer rings of this invention, through quenching and tempering processes, makes the microstructure of the thin-walled bearing outer ring uniform and stable, which helps to improve its mechanical strength and toughness. In particular, the long-term water quenching after one oil quenching simultaneously achieves aging treatment, which helps to improve the mechanical properties of the thin-walled bearing outer ring and improve its dimensional stability. The process design of this invention is scientific and reasonable, creatively simplifies the processing flow, and shortens the processing cycle. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the process flow for processing a thin-walled bearing outer ring according to the present invention. Detailed Implementation

[0022] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0023] Please see Figure 1 The embodiments of the present invention include:

[0024] This invention discloses a method for processing thin-walled bearing outer rings. After forging and annealing the bar stock for the thin-walled bearing outer ring, the processing is completed in one step, including surface shot blasting, cutting, machining of the inner raceway and end face treatment, followed by quenching and tempering. This method can effectively simplify the processing flow and shorten the processing cycle.

[0025] Example 1

[0026] (1) Forging treatment: GCr16 high carbon chromium bar is selected as the bar material for making the outer ring of thin-walled bearing. The bar material is placed in a high temperature environment of 900℃ for 3 hours to eliminate defects such as casting porosity generated during the smelting process, optimize the microstructure, and lay the foundation for subsequent processing.

[0027] (2) Annealing treatment: The forged bar in step (1) above is placed in an annealing furnace at 800°C for 1 hour, and then cooled to 600°C at a rate of 35°C / min. After that, it is taken out of the furnace and cooled to room temperature.

[0028] (3) Lathe machining: The surface of the bar stock after annealing in step (2) above is shot blasted using a shot blasting machine to remove the oxide layer on the surface; then, according to the size requirements of the outer ring of the thin-walled bearing and the additional machining allowance, the bar stock is cut into the target length on the machine tool. The inner raceway is machined on one end face of the cut bar stock to cooperate with the outer raceway on the inner ring of the thin-walled bearing, providing a space for the ball cage and the balls; finally, the two end faces of the above-mentioned material are polished. The specific requirements are: first, perform a grinding process, then perform two fine grinding processes, and clean the surface after polishing.

[0029] (4) Quenching treatment: The thin-walled bearing outer ring semi-finished product obtained in step (3) is placed in a constant temperature heating furnace at 840℃ and heated for 75 minutes. Nitrogen gas is continuously introduced into the constant temperature heating furnace to maintain an oxygen-free inert gas environment in the furnace, so as to prevent the thin-walled bearing outer ring semi-finished product from being oxidized under high temperature heating conditions.

[0030] The heated thin-walled bearing outer ring semi-finished product is quickly removed from the heating furnace and quickly placed into cooling oil at 280℃ for one oil quench. After 60 minutes, the thin-walled bearing outer ring semi-finished product is then immersed in constant temperature water at 180℃ and kept at a constant temperature for 6 hours. Finally, after the water temperature is cooled to below 100℃, the thin-walled bearing outer ring semi-finished product is removed and air-dried.

[0031] (5) Tempering treatment: The thin-walled bearing outer ring semi-finished product taken out and dried in step (4) is placed in a tempering furnace in a nitrogen atmosphere at a temperature of 175°C for tempering treatment for 1.5 hours. Then, it is cooled to below 100°C in the furnace and taken out to obtain the thin-walled bearing outer ring. Nitrogen gas is continuously circulated in the tempering furnace to maintain an oxygen-free inert gas environment inside the furnace, preventing the thin-walled bearing outer ring semi-finished product from being oxidized under high temperature heating conditions.

[0032] In the above-mentioned quenching and tempering processes, the thin-walled bearing outer ring semi-finished product is isolated from oxygen during heating, primary oil quenching, water quenching, and tempering heating, achieving oxygen isolation to the greatest extent possible. This effectively avoids or reduces the possibility of oxidation of the thin-walled bearing outer ring semi-finished product under high-temperature conditions, thereby ensuring the appearance quality of the finished thin-walled bearing outer ring.

[0033] By immersing the product in a constant-temperature water bath for an extended period, it serves two purposes: firstly, it acts as a secondary water quenching process on top of the initial oil quenching; secondly, it serves as an aging treatment, allowing the microstructure of the thin-walled bearing outer ring semi-finished product to undergo a complete transformation, resulting in a more uniform microstructure and more stable performance. Additionally, the water bath conditions also serve a cleaning function.

[0034] The combination of quenching and tempering effectively improves the strength and toughness of the outer ring of the finished thin-walled bearing, and also meets the requirements of thin-walled bearings for wear resistance, fatigue strength and corrosion resistance.

[0035] Comparative Example 1

[0036] Compared to Example 1, after one oil quenching, the oil was directly cooled to below 100°C and then washed with water to remove it, without constant temperature water treatment.

[0037] Comparative Example 2

[0038] Compared with Example 1, in step (4), the heated thin-walled bearing outer ring semi-finished product is quickly taken out of the heating furnace and quickly placed in cooling oil at a temperature of 280°C for one oil quenching. After 60 minutes, the thin-walled bearing outer ring semi-finished product is then immersed in constant temperature water at 180°C for 60 minutes. Finally, the water temperature is cooled to below 100°C, and the thin-walled bearing outer ring semi-finished product is taken out and air-dried.

[0039] Comparative Example 3

[0040] Compared to Example 1, neither the quenching nor the tempering process was carried out in an inert gas environment.

[0041] The thin-walled bearing outer rings prepared in Example 1 and Comparative Examples 1-3 were subjected to performance tests, and the test results are shown in Table 1 below.

[0042] Ellipticity / mm Increase by a large amount / % Warp / mm Appearance Example 1 0.15 0.93 0.54 Unoxidized Comparative Example 1 0.20 1.3 0.97 Unoxidized Comparative Example 2 0.18 0.99 0.63 Unoxidized Comparative Example 3 0.15 0.93 0.55 Oxide layer

[0043] As can be seen from the above data, oxygen isolation treatment during quenching and tempering can effectively solve the oxidation problem of thin-walled bearing outer rings under high temperature conditions. The quenching and tempering process of the present invention makes the microstructure of the thin-walled bearing outer ring uniform and stable, which helps to improve its mechanical strength and toughness. In particular, long-term water quenching after one oil quenching, with simultaneous aging treatment, helps to improve the mechanical properties of the thin-walled bearing outer ring and improve its dimensional stability.

[0044] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method of machining a thin-walled bearing outer ring, characterized in that, The method comprises the following steps: (1) forging treatment: hot forging treatment is performed on the bar material for the thin-wall bearing outer ring; (2) annealing treatment: the bar material after the forging treatment in step (1) is placed in an annealing furnace for annealing treatment; (3) lathe processing: the bar material after the annealing treatment in step (2) is sequentially subjected to shot blasting treatment, cutting and end face polishing treatment, so as to obtain a thin-wall bearing outer ring semi-finished product; (4) quenching treatment: the thin-wall bearing outer ring semi-finished product obtained in step (3) is placed in a heating furnace with continuous inert gas for heating, and after heating, the thin-wall bearing outer ring semi-finished product is directly taken out and rapidly immersed in oil for primary oil quenching treatment; after the primary oil quenching treatment, the thin-wall bearing outer ring semi-finished product is immersed in constant-temperature clean water for constant-temperature keeping for 3-10 h, and then water quenching and aging treatment are performed; then, the water temperature is cooled to below 100 DEG C, and the thin-wall bearing outer ring semi-finished product is taken out and air-dried; (5) tempering treatment: the thin-wall bearing outer ring semi-finished product after air-drying in step (4) is placed in a tempering furnace with continuous inert gas for tempering treatment, so as to obtain the thin-wall bearing outer ring.

2. The method of claim 1, wherein In step (1), the temperature of the hot forging treatment is 850-950 DEG C.

3. The method of claim 1, wherein In step (2), the process conditions of the annealing treatment are as follows: first, constant-temperature keeping at 750-820 DEG C for 0.5-2 h, then cooling at a rate of 30-40 DEG C / min to 600 DEG C, and then furnace cooling to room temperature.

4. The method of claim 1, wherein In step (3), the lathe processing further comprises machining an inner raceway on one side of the cut bar material.

5. The method of claim 1, wherein In step (4), the process conditions of the heating are as follows: heating temperature is 820-850 DEG C, and constant-temperature keeping is performed for 80-90 min.

6. The method of claim 1, wherein In step (4), the process conditions of the primary oil quenching are as follows: oil temperature is 260-330 DEG C, and the time is 50-70 min.

7. The method of claim 1, wherein In step (4), the temperature of the clean water is 150-200 DEG C.

8. The method of claim 1, wherein In step (5), the process conditions of the tempering treatment are as follows: 160-180 DEG C, and the time is 1-3 h.

9. The method of claim 1, wherein The bar material is GCr16 high-carbon chromium bar material.

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