Machining method for inner ring of short cylindrical roller bearing with flange-free outer ring

Abstract

The invention discloses a processing method of an inner ring of a short cylindrical roller bearing with a flange-free outer ring, relates to a processing method of a bearing inner ring, and aims to solve the problem that the stability, the consistency and the bearing surface quality of the conventional processing method of the short cylindrical roller bearing with the flange-free outer ring cannot meet the requirements of a user on the bearing quality. The method comprises the following steps: carrying out rough turning and fine turning on a bearing inner ring in sequence, and then turning a raceway, an inner chamfer and an outer chamfer, turning an oil groove and drilling two rows of oil holes; heat treatment is conducted, then coarse grinding is conducted firstly, then fine grinding is conducted, tempering is supplemented at high temperature, then oil grooves and oil holes are cleaned, an inner raceway is subjected to final grinding, acid pickling is conducted, hydrogen removal is conducted, and the outer diameter of the inner ring and the inner diameter are subjected to final grinding; and respectively carrying out abrasive flow machining on the outer surface and the inner surface of the bearing inner ring, then carrying out flaw detection, finely grinding an inner raceway, and submitting inspection. By the adoption of the machining method, the precision scatter difference of the obtained bearing inner ring is controlled within 0.5 micrometer, the consistency and stability of the machining method are good, and the machining method is applied to the field of bearings.

Description

Technical Field

[0001] This invention relates to a method for machining the inner ring of a short cylindrical roller bearing with no outer ring flange. Background Technology

[0002] The unflange-less short cylindrical roller bearing consists of four parts: an inner ring, an outer ring, rollers, and a cage. The outer ring has no flanges and can move freely relative to the inner ring and rollers. This structure allows the bearing to withstand various load types, including radial loads, axial loads, and tilt angles, providing high load-carrying capacity and wear resistance. It is widely used in high-load, high-speed, and high-precision machinery in industries such as machine tools, power equipment, mining, and shipbuilding, and is a high-quality, high-reliability bearing.

[0003] However, with the rapid development of the bearing industry, users have put forward higher requirements for the precision and surface quality of bearings. Traditional processing methods can no longer meet the users' needs for bearing quality. Therefore, it is necessary to study processing methods to improve the processing quality of products and meet the actual needs of users. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the stability, consistency, and bearing surface quality of existing machining methods for short cylindrical roller bearings without outer ring flanges can no longer meet users' requirements for bearing quality. This invention provides a machining method for the inner ring of short cylindrical roller bearings without outer ring flanges.

[0005] The present invention discloses a method for machining the inner ring of a short cylindrical roller bearing with no outer flange, the method comprising:

[0006] First, rough turn and fine turn the inner ring of the bearing in sequence, then turn the raceway, turn the inner and outer chamfers, turn the oil groove and drill two rows of oil holes;

[0007] 2. Perform heat treatment at 545℃~555℃ for 120min~180min;

[0008] 3. First rough grinding, then fine grinding. Both rough grinding and fine grinding include grinding the two planes, grinding the outer diameter of the inner ring, grinding the inner diameter, grinding the side guard, and grinding the inner raceway. When grinding the side guard, a negative back angle of the side guard is formed, with an angle of 10′~30′.

[0009] 4. Perform high-temperature tempering at 345℃~350℃ for 2.5h~3.5h, then clean the oil grooves and oil holes, the inner raceway of the final grinding, pickle, remove hydrogen, and clean the outer diameter and inner diameter of the inner ring of the final grinding.

[0010] 5. Perform abrasive flow machining on the outer and inner surfaces of the bearing inner ring, then perform flaw detection, fine grinding of the inner raceway, and submit for inspection to complete the process.

[0011] The beneficial effects of this invention are:

[0012] I. The cylindrical roller bearing of this invention features a negative back angle design on the inner ring flange, with an angle of 10′~30′, which improves end-face lubrication and enhances roller running stability. The function of the negative back angle: The negative back angle of the bearing flange is a special structural design that forms an inwardly inclined surface at the flange position. The negative back angle can change the flow direction and distribution of lubricating oil. When lubricating oil flows through the bearing flange, the negative back angle can guide the lubricating oil to better flow to the contact area between the rolling elements and the raceway, thereby improving the lubrication effect. Increased bearing load capacity: The design of adding a negative back angle to the bearing optimizes the stress distribution of the bearing. It makes the contact stress distribution between the rolling elements and the raceway more uniform when the bearing is under load, reducing local stress concentration. Reduced vibration and noise: The design of adding a negative back angle to the bearing improves the dynamic performance of the bearing. It reduces the collision and friction between the rolling elements and the flange during operation, thereby reducing vibration and noise generation and improving the smoothness of bearing operation. Facilitates assembly and installation: The beveled design with a negative back angle provides guidance during bearing assembly and installation, making it easier to install the bearing correctly, reducing assembly errors, ensuring the bearing's accuracy and performance after installation, and preventing premature damage due to improper installation. This improves the bearing's reliability, safety, and service life.

[0013] Second, this invention saves on the original process by adding an "abrasive flow machining" step. Specifically, it eliminates five machining steps: "grinding the bearing flange," "polishing the bearing flange," "precision grinding of the inner ring outer diameter," "rough grinding of the inner raceway," and "finishing." This achieves a surface roughness of 0.1μm for the bearing inner ring flange and 0.2μm for the inner ring outer diameter, resulting in a smooth, burr-free inner ring surface. This improves processing efficiency and reduces processing costs. Furthermore, replacing the "finishing" step in the original process reduces surface waviness, achieving the precision finish required for machining, with a roughness below Ra0.1. It also removes residual stress from previous machining processes, preventing workpiece deformation during processing and ensuring product accuracy and uniformity.

[0014] III. Abrasive flow machining is a machining method that uses a high-speed flowing abrasive stream to impact and grind the surface of a workpiece, achieving deburring, polishing, and fine machining. Its principle involves using a semi-solid carrier with certain viscoelasticity and cutting properties to mix with abrasive particles to form abrasive grains. During machining, these abrasive grains are forced through the inner hole or workpiece surface at a uniform speed via extrusion, resulting in reciprocating grinding and achieving better polishing and deburring effects. Furthermore, the friction during abrasive flow machining can improve the microstructure of the workpiece surface to a certain extent, further enhancing its smoothness and gloss. In the aerospace field, abrasive flow machining technology demonstrates unique advantages for the efficient polishing of complex shapes and tiny gaps, improving the overall performance and reliability of the workpiece.

[0015] Arranging abrasive flow machining after all other machining processes aims to remove burrs, sharp points, round corners, and improve the surface roughness of the workpiece. It is particularly effective in removing fine structures such as oil holes and oil grooves. In this paper, the oil hole in the bearing inner ring is a long, narrow hole with a diameter of only φ1.0mm, making burr removal difficult. Traditional machining methods are incomplete in removing burrs, requiring repeated deburring, extending the machining cycle, and making it difficult to guarantee product quality. Abrasive flow machining provides better burr removal, a higher pass rate, and also improves the roughness of the inner wall of the oil hole, resulting in an overall improvement in product quality.

[0016] Fourth, the two high-temperature tempering processes during grinding can effectively remove the stress generated by grinding, reduce the deformation of the bearing inner ring, and improve the machining accuracy of the bearing inner ring.

[0017] Fifth, by using the processing method of the present invention, the accuracy variation of the bearing inner ring is controlled within 0.5μm. The processing method has good consistency and stability, which improves the overall processing level of the bearing inner ring and lays the foundation for the fine processing of this type of structure in the future, providing an important technical means. Attached Figure Description

[0018] Figure 1 Schematic diagrams of roughing and finishing processes;

[0019] Figure 2 A schematic diagram of the car track;

[0020] Figure 3 This is a diagram illustrating a negative back angle.

[0021] Figure 4 This is a schematic diagram of the bearing inner ring structure. Detailed Implementation

[0022] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0023] Specific Implementation Method 1: This implementation method describes the machining method for the inner ring of a short cylindrical roller bearing with no outer ring flange. The method is as follows:

[0024] First, rough turn and fine turn the inner ring of the bearing in sequence, then turn the raceway, turn the inner and outer chamfers, turn the oil groove and drill two rows of oil holes;

[0025] 2. Perform heat treatment at 545℃~555℃ for 120min~180min;

[0026] 3. First rough grinding, then fine grinding. Both rough grinding and fine grinding include grinding the two planes, grinding the outer diameter of the inner ring, grinding the inner diameter, grinding the side guard, and grinding the inner raceway. When grinding the side guard, a negative back angle of the side guard is formed, with an angle of 10′~30′.

[0027] 4. Perform high-temperature tempering at 345℃~350℃ for 2.5h~3.5h, then clean the oil grooves and oil holes, the inner raceway of the final grinding, pickle, remove hydrogen, and clean the outer diameter and inner diameter of the inner ring of the final grinding.

[0028] 5. Perform abrasive flow machining on the outer and inner surfaces of the bearing inner ring, then perform flaw detection, fine grinding of the inner raceway, and submit for inspection to complete the process.

[0029] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the oil hole in step one is drilled from the inner radial direction to the outer radial direction. Everything else is the same as in Specific Implementation Method One.

[0030] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: the single grinding depth in rough grinding is ≤0.1mm, the feed rate is ≤3μm / s, and the dressing wheel is prepared using a pre-dressing method. Everything else is the same as in Specific Implementation Method 1 or 2.

[0031] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the fine grinding cycle dressing of the grinding wheel adopts the intermediate dressing method, with a single grinding amount ≤0.03mm and a feed rate ≤1um / s. Everything else is the same as in Specific Implementation Methods One to Three.

[0032] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the final grinding single-pass grinding amount is ≤0.03mm, the feed rate is ≤1μm / s, and the dressing wheel is performed using the intermediate dressing method. Everything else is the same as in Specific Implementation Methods One to Four.

[0033] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the abrasive in the abrasive flow process is synthetic diamond with a size of 5~200μm. Everything else is the same as in Specific Implementation Methods One to Five.

[0034] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that the abrasive flow machining of the outer surface of the bearing inner ring is divided into a first grinding and a second grinding. In the first grinding, the spindle rotates forward at a speed of 135 r / min-185 r / min; the feed hopper rotates in reverse at a speed of 85 r / min-135 r / min, and the grinding time is 25 min-35 min. After the first grinding, the second grinding is performed. In the second grinding, the spindle rotates in reverse at a speed of 135 r / min-185 r / min, the feed hopper rotates forward at a speed of 85 r / min-135 r / min, and the grinding time is 25 min-35 min. Everything else is the same as in Specific Implementation Methods One through Six.

[0035] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the abrasive flow machining of the inner surface of the bearing inner ring is divided into a first grinding and a second grinding. In the first grinding, the spindle rotates forward at a speed of 135 r / min-185 r / min; the feed hopper rotates in reverse at a speed of 85 r / min-135 r / min, and the grinding time is 15 min-25 min. After the first grinding, the second grinding is performed. In the second grinding, the spindle rotates in reverse at a speed of 135 r / min-185 r / min, the feed hopper rotates forward at a speed of 85 r / min-135 r / min, and the grinding time is 15 min-25 min. Everything else is the same as in Specific Implementation Methods One to Seven.

[0036] The beneficial effects of the present invention are verified using the following embodiments:

[0037] Example 1: A method for machining the inner ring of a short cylindrical roller bearing with no outer ring flange, wherein the method is as follows:

[0038] 1. The bearing inner ring is rough-turned and fine-turned sequentially, followed by turning the raceway, turning the inner and outer chamfers, and drilling two rows of oil holes. The oil holes are drilled from the inner radial direction to the outer diameter direction. The bearing inner ring is then fixed on a machining center. First, a center drill is used to determine the machining position of each oil hole. Then, the oil holes are drilled using a "drilling" method, with each "drilling" depth being 0.05mm~0.1mm, and a rotation speed n=2000~2500r / min, thus ensuring the machining position of the oil holes.

[0039] 2. Perform heat treatment at 550℃ for 150 minutes;

[0040] 3. First rough grinding, then fine grinding. Both rough grinding and fine grinding include grinding the two planes, grinding the outer diameter of the inner ring, grinding the inner diameter, grinding the side guard, and grinding the inner raceway. When grinding the side guard, a negative back angle of the side guard is formed, with an angle of 10′~30′.

[0041] 4. Perform high-temperature tempering at 347℃ for 3 hours, then clean the oil grooves and oil holes, the inner raceway of the final grinding, pickle, remove hydrogen, and clean the outer diameter of the inner ring and the inner diameter of the final grinding.

[0042] 5. Perform abrasive flow machining on both the outer and inner surfaces of the bearing inner ring, followed by flaw detection, fine grinding of the inner raceway, and final inspection. The abrasive used in the abrasive flow process is synthetic diamond with a size of 200 μm. The abrasive flow machining of the outer surface of the bearing inner ring consists of a first grinding and a second grinding. In the first grinding, the spindle rotates forward at 160 r / min, while the feed hopper rotates in reverse at 110 r / min, and the grinding time is 30 minutes. After the first grinding, the second grinding is performed, with the spindle rotating in reverse at 160 r / min and the feed hopper rotating forward at 110 r / min, and the grinding time is 30 minutes. The abrasive flow machining of the inner surface of the bearing inner ring consists of a first grinding and a second grinding. In the first grinding, the spindle rotates forward at 160 r / min, while the feed hopper rotates in reverse at 110 r / min, and the grinding time is 20 minutes. After the first grinding, the second grinding is performed, with the spindle rotating in reverse at 160 r / min and the feed hopper rotating forward at 110 r / min, and the grinding time is 20 minutes.

[0043] The machining accuracy of key parameters of the inner ring of the machined short cylindrical roller bearing with an outer ring without flanges was tested, and the results are shown in Table 1:

[0044]

[0045] The data above shows that the precision variation of the bearing inner ring is controlled within 0.5μm. This machining method has good consistency and stability, improves the overall machining level of the bearing inner ring, and lays the foundation for future precision machining of this type of structure, providing an important technical means.

Claims

1. A method for machining the inner ring of a short cylindrical roller bearing with no outer ring flange, characterized in that, The method is as follows: First, rough turn and fine turn the inner ring of the bearing in sequence, then turn the raceway, turn the inner and outer chamfers, turn the oil groove and drill two rows of oil holes; 2. Perform heat treatment at 545℃~555℃ for 120min~180min; 3. First rough grinding, then fine grinding. Both rough grinding and fine grinding include grinding the two planes, grinding the outer diameter of the inner ring, grinding the inner diameter, grinding the side guard, and grinding the inner raceway. When grinding the side guard, a negative back angle of the side guard is formed, with an angle of 10′~30′.

4. Perform high-temperature tempering at 345℃~350℃ for 2.5h~3.5h, then clean the oil grooves and oil holes, the inner raceway of the final grinding, pickle, remove hydrogen, and clean the outer diameter and inner diameter of the inner ring of the final grinding.

5. Perform abrasive flow machining on the outer and inner surfaces of the bearing inner ring, then perform flaw detection, fine grinding of the inner raceway, and submit for inspection to complete the process.

2. The machining method for the inner ring of a short cylindrical roller bearing without outer flanges according to claim 1, characterized in that, In step one, the oil hole is drilled from the inner diameter to the outer diameter.

3. The method for machining the inner ring of a short cylindrical roller bearing without a flange on the outer ring according to claim 1, characterized in that, For rough grinding, the single grinding amount is ≤0.1mm and the feed rate is ≤3μm / s. The dressing wheel is dressed using the pre-dressing method.

4. The method for machining the inner ring of a short cylindrical roller bearing without a flange on the outer ring according to claim 1, characterized in that, For fine grinding, the single grinding amount is ≤0.03mm and the feed rate is ≤1μm / s. The dressing wheel is dressed using the intermediate dressing method.

5. The method for machining the inner ring of a short cylindrical roller bearing without a flange on the outer ring according to claim 1, characterized in that, The final grinding depth per pass is ≤0.03mm and the feed rate is ≤1μm / s. The dressing wheel is dressed using the intermediate dressing method.

6. The method for machining the inner ring of a short cylindrical roller bearing without a flange on the outer ring according to claim 1, characterized in that, The abrasive used in the abrasive flow process is synthetic diamond with a size of 5~200μm.

7. The method for machining the inner ring of a short cylindrical roller bearing without a flange on the outer ring according to claim 1, characterized in that, The abrasive flow machining of the outer surface of the bearing inner ring is divided into a first grinding and a second grinding. In the first grinding, the spindle rotates forward at a speed of 135 r / min-185 r / min, and the material box rotates in reverse at a speed of 85 r / min-135 r / min. The grinding time is 25 min-35 min. After the first grinding, the second grinding is carried out. In the second grinding, the spindle rotates in reverse at a speed of 135 r / min-185 r / min, and the material box rotates forward at a speed of 85 r / min-135 r / min. The grinding time is 25 min-35 min.

8. The method for machining the inner ring of a short cylindrical roller bearing without a flange on the outer ring according to claim 1, characterized in that, The abrasive flow machining of the inner surface of the bearing inner ring is divided into a first grinding and a second grinding. In the first grinding, the spindle rotates forward at a speed of 135 r / min-185 r / min, and the material box rotates in reverse at a speed of 85 r / min-135 r / min. The grinding time is 15 min-25 min. After the first grinding, the second grinding is carried out. In the second grinding, the spindle rotates in reverse at a speed of 135 r / min-185 r / min, and the material box rotates forward at a speed of 85 r / min-135 r / min. The grinding time is 15 min-25 min.

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