Crossed roller bearing inner and outer ring raceway convexity machining method

Abstract

The invention relates to the technical field of precision machining processes, and particularly provides a method for machining convexity of raceways of inner and outer rings of a crossed roller bearing. Comprising the following steps: S1, calculating distribution of a raceway convexity value along a raceway direction to obtain a modification curve; s2, the feeding and retracting amount of the grinding wheel each time and the swing angle between the grinding wheel and the workpiece to be machined are calculated; and S3, the grinding wheel conducts approximate grinding on the roller path convexity from the two ends to the middle of the roller path in sequence according to the cutter feeding and retracting amount and the swing angle result, and finally the needed continuous and smooth convexity profile is formed in an enveloping mode. According to the scheme, the swing grinding process is innovatively designed on the basis of the feeding and retracting amount calculation formula and the machining swing angle calculation formula, the target modification curve can be machined on the V-shaped raceway of the bearing ring through a conventional grinding wheel, and the repeatability and consistency of the process can be improved; the process is convenient to optimize and adjust; the dependence on high-skill operators is reduced; the processing cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology, and in particular provides a method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing. Background Technology

[0002] Structurally, crossed roller bearings have a "V"-shaped raceway. They can simultaneously withstand combined loads such as axial, radial, and overturning moments, and possess advantages such as high rigidity, high precision, and compact structure. Therefore, they are used in applications with low speeds but complex load types, large load values, and extremely high requirements for accuracy in all directions. High accuracy in all directions, in turn, requires the bearing to have very high radial stiffness, axial stiffness, or moment stiffness. To improve bearing stiffness, crossed roller bearings often use very small clearance or even negative clearance. The small clearance, coupled with the large number of rollers inside the crossed roller bearing, leads to an increase in starting and running frictional torque. This increased torque, in turn, causes the bearing temperature to rise, inevitably leading to a decrease in the precision of the bearing and the main machine. This is an objectively existing structural contradiction. Conventional crossed roller bearings with raceways without convexity and in straight contact with the rollers suffer from the aforementioned deficiencies in terms of operating accuracy and service life.

[0003] Meanwhile, the geometry of the raceway working surface of crossed roller bearings differs from other types of bearings; the raceway is V-shaped. Combined with the inner and outer ring assembly clearance and the presence of U-grooves in the machined raceway, the raceway length is less than the roller length. Simply modifying the roller shape is insufficient to fully compensate for the fit deviations caused by the raceway geometry and assembly clearance. Under heavy loads, the lack of convexity in the V-shaped raceway of crossed roller bearings leads to an edge effect with a peculiar pressure distribution at the raceway ends and pressure concentration in the middle of the raceway. Since bearing failure occurs at the contact area with the highest stress, the bearing's load-carrying capacity is severely reduced, and the risk of early localized fatigue failure in the contact area is high. Furthermore, the rollers have poor anti-skewness capability; even a slight external eccentric load can cause the bearing to rotate poorly or even seize.

[0004] Existing technologies (such as patent CN106195015A) clearly propose the design concept and corresponding processing methods for setting convexity on the raceway of crossed roller bearings, such as... Figure 1 However, the specific processing techniques used to realize this design concept have inherent limitations and technological defects: 1. Contour grinding and its drawbacks: This method requires first manufacturing a diamond roller that precisely matches the target convexity profile, in order to dress the grinding wheel. This is essentially a "shape replication" process.

[0005] The accuracy of a workpiece contour is entirely dependent on the manufacturing precision and wear uniformity of the diamond rollers. Even minute errors in the rollers or uneven wear during use will directly affect all workpieces, resulting in large variations in the accuracy of batch-produced products and making it difficult to guarantee consistency.

[0006] 2. CNC precision hard turning method and its defects: This method uses a CNC system to control the cutting tool to perform turning along a predetermined convexity curve trajectory.

[0007] Because the curved trajectory is relatively complex, it can easily cause interference between the tool and the raceway slope or flange. To avoid interference, programming is often conservative, which can lead to the incomplete machining of critical areas at the end of the raceway.

[0008] Executing complex spatial trajectories with high precision and continuity places stringent requirements on the dynamic accuracy and servo response of machine tools, which inevitably leads to high equipment costs. Summary of the Invention

[0009] The technical problem to be solved by the present invention is that in the prior art, when machining the convexity of the raceway, the grinding wheel used for machining often needs to be customized, which is costly; or hard turning is used, which requires high precision of the machine tool and is easily affected, and the surface quality of the raceway is worse than that of grinding.

[0010] Therefore, this invention provides a method for machining the convexity of the inner and outer raceways of crossed roller bearings. The method aims to use a oscillating grinding process and conventional grinding wheels, and through innovative calculation formulas for the feed and retraction amounts and machining oscillation angles, to calculate the oscillation angle and corresponding feed and retraction amounts of the grinding wheel for each machining operation, thereby machining the target arc or logarithmic convexity profile on the "V"-shaped raceway of the bearing rings.

[0011] The technical solution adopted by this invention to solve its technical problem is: A method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing includes the following steps: S1, calculate the convexity value of the selected point for the raceway convexity machining, and the multi-point convexity profile is an intersecting circular arc shaping curve; The distribution of the raceway convexity value along the raceway direction is determined by formula (1): (1) in, For the reshaping curve of intersecting circular arcs, the first The convexity value of each selected processing point , This represents the total number of processing selection points; The radius of the intersecting arcs (corresponding to the convexity of the machining selection point); This is the length of the straight section of the raceway; For the first The coordinates of each selected processing point along the raceway direction are measured starting from the center of the raceway.

[0012] S2, calculates the feed and retraction amount and oscillation angle for each step in grinding wheel machining; The feed / retraction amount includes the initial retraction amount of the grinding wheel. and grinding wheel After the second swing, the tool advance / retreat amount (including the first) The feed rate after the first swing and the first The retraction amount after each swing is a value that is... The results are obtained by formulas (2) and (3) respectively: (2) (3) The swing angle Calculated using formula (4): (4) in, Where is the roller radius; This is the length of the raceway.

[0013] It should be noted that the swing angle is the relative swing angle between the grinding wheel and the workpiece (bearing ring).

[0014] S3, the grinding wheel on the machining lathe performs a series of discrete but precisely planned grinding operations on the raceway convexity based on the calculation results of the feed and retraction amount and oscillation angle calculated in step S2. The grinding wheel systematically approaches the raceway from both ends to the middle, and finally envelops and forms the continuous and smooth convexity profile required by the design.

[0015] The core principle of this method is to select a conventionally shaped grinding wheel as the machining tool, and to control the relative oscillation angle (deflection angle) between the grinding wheel and the workpiece. The precise control and step adjustment of the process follow a progressive step-by-step approximation strategy of "processing both ends of the raceway first, then approaching the middle, and first using a larger deflection angle, then gradually reducing the deflection angle" to finally form a continuous and smooth target arc or logarithmic curve profile (shaping curve) on the workpiece raceway.

[0016] Furthermore, step S3 specifically includes: S31 Workpiece clamping: The workpiece to be processed is fixed at the end of the spindle in the machining lathe. The spindle is used to drive the workpiece to rotate around its axis. At this time, the grinding wheel is located on the radial side of the workpiece and is installed in the drive device of the machining lathe.

[0017] It should be noted that controlling the grinding wheel to swing relative to the workpiece (i.e., the grinding wheel swings while the workpiece is fixed, which is processing mode one) or controlling the workpiece to swing relative to the grinding wheel during processing (i.e., the grinding wheel is fixed while the workpiece swings, which is processing mode two) are both processing modes.

[0018] The two processing modes are based on the same technological principle and achieve the same technical effect, but their structural characteristics are different, and therefore they have different applicable scenarios.

[0019] S32 raceway end machining: Workpiece starts rotating, first feed. Afterwards, the relative oscillation angle between the grinding wheel and the workpiece is a positive angle ( At this swing angle, the working surface of the grinding wheel contacts both inclined surfaces of the V-shaped raceway of the inner or outer ring of the bearing, mainly grinding the outer side of one raceway and the inner side of the raceway on the other side.

[0020] It should be noted that the initial swing angle is relatively large. During the initial contact phase at this large swing angle, the grinding wheel effectively cuts the areas at both ends of the raceway, but does not contact the middle section of the raceway.

[0021] Subsequently, the grinding wheel is deflected relative to the workpiece by a large negative angle ( This creates symmetrical grinding zones on both sides of the raceway.

[0022] This stage (adopted) The design mechanism of this process is as follows: by using an initial large oscillation angle, the edge of the grinding wheel is precisely aligned and the material to be removed from both ends of the raceway is removed, initially forming the endpoint reference of the profile and the retraction space. This process prioritizes establishing the boundary position of the convexity curve. At the same time, the grinding wheel exhibits low cutting force and low grinding heat during this process, effectively controlling the workpiece surface temperature and providing conditions for ensuring the integrity of the machined surface.

[0023] S33 progressively approaches the target profile: After completing the grinding process at both ends of the raceway, it enters the gradual shaping stage of the profile, that is, the grinding stage in the middle of the raceway.

[0024] Because the oscillation angle between the grinding wheel and the workpiece decreases sequentially ( , Furthermore, the two ends of the raceway have been pre-machined in step (S32), and the effective contact area between the grinding wheel and the workpiece is sequentially shifted from both ends to the middle along the raceway slope.

[0025] The core mechanism of this stage (using decreasing oscillation angles) lies in stepwise envelope forming: by systematically and sequentially reducing the deflection angle, the contact position between the working surface of the grinding wheel and the raceway starts from the pre-machined end areas and progresses towards the center of the raceway. Each grinding trajectory after adjusting the angle partially overlaps with the previous trajectory. Through this series of grinding movements with decreasing deflection angles, envelope processing is achieved, thereby ultimately and accurately approximating the required circular arc or logarithmic curve profile.

[0026] Furthermore, the grinding wheel is a high-grit fine grinding wheel. The key mechanism for selecting a high-grit fine grinding wheel lies in its relatively mild and controllable grinding capability.

[0027] The beneficial effects of this invention are: 1. By introducing a formula for calculating the raceway profile, supporting data is provided for modifying the raceway shape, effectively suppressing roller skew and improving rotational flexibility. Stress distribution is optimized to prevent edge stress concentration and improve contact fatigue life.

[0028] 2. Introducing calculation formulas for tool advance / retraction and oscillation angles can improve the repeatability and consistency of the process; it is highly adaptable, facilitating process optimization and adjustment; and it reduces reliance on highly skilled operators.

[0029] 3. This solution can utilize existing grinding equipment commonly used in machine tools, requiring no special customization or modification, thus reducing processing costs. In contour grinding: grinding wheels wear easily, leading to a low yield rate. Defective products cannot be further processed, and the grinding wheel needs replacement due to wear, resulting in a long processing time. This solution eliminates concerns about inaccuracies caused by wear, and if replacement is necessary, only a standard grinding wheel needs to be replaced. In CNC hard turning: due to a relatively conservative approach to interference path design, some workpiece edges may be defective. Furthermore, CNC hard turning is highly dependent on complex CNC trajectory programming and high-precision lathes; insufficient precision at any point during lathe machining will cause path deviation, rendering all machined parts unusable. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Figure 1 A cross-sectional view of a cross-shaped cylindrical roller bearing with a convex profile; Figure 2 This is a schematic diagram illustrating the machining of the inner ring raceway convexity of the crossed cylindrical roller bearing of the present invention. Figure 3 This is a schematic diagram illustrating the machining of the raceway convexity of the outer ring of the crossed cylindrical roller bearing of the present invention. Figure 4 This is an enlarged schematic diagram of position I in processing mode one of the present invention; Figure 5 This is an enlarged schematic diagram of position I in processing mode two of the present invention; Figure 6 This is a schematic diagram of the parameters for machining the raceway crown of the present invention; Figure 7 This is a schematic diagram of the raceway convexity machining process of the present invention; Figure 8 This is a partially enlarged schematic diagram of the raceway convexity machining process of the present invention.

[0032] In the picture: 1. Shaft; 2. Magnetic poles; 3. Bearing inner ring; 4. Grinding wheel. Detailed Implementation

[0033] The invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention and therefore showing only the components relevant to the invention. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use.

[0034] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] Reference Figures 1-8 A method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing includes the following steps: Data preparation stage S1, calculate the convexity value of the selected point for the raceway convexity machining, and the multi-point convexity profile is an intersecting circular arc shaping curve; The distribution of raceway convexity along the raceway direction is determined by formula (1): (1) in, For the reshaping curve of intersecting circular arcs, the first The convexity value of each selected processing point , This represents the total number of processing points selected. The radius of the intersecting arcs; This is the length of the straight section of the raceway; For the first The coordinates of each selected processing point along the raceway direction are measured starting from the center of the raceway.

[0039] S2, calculate the feed and retraction amount and oscillation angle of each pass / retract during machining of grinding wheel 4; The feed and retraction amounts include the initial retraction amount of grinding wheel 4. and grinding wheel 4th After the second swing, the tool advance / retreat amount (including the first) The feed rate after the first swing and the first The retraction amount after each swing is a value that is... The results are obtained by formulas (2) and (3) respectively: (2) (3) Swing angle Calculated using formula (4): (4) in, Where is the roller radius; This is the length of the raceway.

[0040] It should be noted that the oscillation angle is the relative oscillation angle between the grinding wheel 4 and the workpiece (bearing ring). Furthermore, the oscillation occurs within the same plane.

[0041] The formulas (2) and (3) introduced in this scheme have the following characteristics: (1) Improved process repeatability and consistency: All machining parameters (oscillation angle, feed and retraction amount, machining step sequence) are calculated using formulas. The same set of machining parameters can be reused in the same batch or even different batches of bearings of the same model, ensuring that the convex profile of each product is completely consistent, which is suitable for mass production. This greatly improves the stability of the production process and product consistency, meeting the high quality and reliability requirements of precision bearings.

[0042] (2) High adaptability, facilitating process optimization and adjustment: The processing parameters in the formula can be flexibly adjusted according to different bearing models, sizes, and crown design requirements. Users can quickly generate processing programs suitable for new products by modifying the parameters in the formula, without having to redevelop the process. This enhances the versatility and scalability of the processing method, making it suitable for multi-variety, small-batch, or customized production scenarios.

[0043] (3) Reduced reliance on highly skilled operators: The entire machining process can be automatically executed by the CNC system. Operators only need to input the correct parameters and start the program, without needing to have high-level grinding experience or manual adjustment capabilities. This reduces labor costs, minimizes quality fluctuations caused by human error, and is more suitable for modern, intelligent manufacturing environments.

[0044] Specifically, the length of the raceway ,in The width of the raceway U-groove is half its width. Calculate the length of the straight section based on the length of the raceway. ,generally ; Select the raceway center as position 0, and the farthest segment as... Since the raceway is symmetrical on both sides, only half is selected for calculation (divided into left and right), that is, the non-straight section of the left half of the raceway is divided into equal parts. Share, received indivual Coordinates, farthest segment for ;Sure The convexity of the raceway at that position is used to determine the radius of the intersecting arc at that position. ; Take the rest respectively Substitute the coordinates into formula (1) to obtain the convexity value at each coordinate.

[0045] In Example 1, the CSF-20 crossed roller bearing is used as an example ( , Perform raceway crown calculation:

[0046]

[0047] The length of the non-straight segment is divided into three equal parts (i.e., three processing selection points). ),get , , ,in (in (For the machining point near the raceway end), the convexity value of this machining point is set according to the needs of raceway shaping. Substituting into formula (1) yields ; Known ,Will , Substituting back into formula (1), we get , .

[0048] In Example 2, the V-shaped raceway of the inner ring 3 of the crossed roller bearing (material GCr15, hardness HRC59-63) with an outer diameter of 51.4 mm is machined to have a convexity.

[0049] in, , , .

[0050] Processing preparation stage In this embodiment, to ensure the stable implementation and repeatability of the progressive oscillating grinding process, the following key processing parameters are defined and optimized. These parameters together form the basis for achieving high-precision convex profiles and ultra-precise surface quality: Grinding tools and motion parameters: Grinding wheel specification 4: A resin-bonded cubic boron nitride (CBN) grinding wheel is selected. Resin was chosen as the bond because its good elasticity helps achieve a gentler contact and better polishing results in oscillating grinding. The grit size of grinding wheel 4 is set to #1000 (corresponding to a high-grit fine grinding wheel), which ensures sufficient cutting power while producing excellent surface finish. The width of grinding wheel 4 is set to 10mm, a width suitable for oscillating strategies, creating appropriate contact areas at different angles.

[0051] Grinding wheel speed: The grinding wheel spindle features a high-speed design, operating at 26,000 rpm. Combined with the grinding wheel diameter, this speed provides a constant high surface velocity of approximately 35 m / s. High surface velocity is crucial for achieving efficient micro-cutting, reducing the load on individual abrasive grains, and thus minimizing grinding force and heat.

[0052] Cooling method: High-pressure water-based grinding fluid is used for cooling and rinsing throughout the machining process. High-pressure cooling can effectively penetrate the grinding zone, remove heat and wash away grinding debris in time, which is a necessary measure to control the temperature rise of the workpiece, prevent thermal damage and ensure machining accuracy.

[0053] Processing stage S3. The grinding wheel on the machining lathe performs a series of discrete but precisely planned grinding operations on the raceway convexity based on the initial retraction amount calculated in step S2, the subsequent advance and retraction amounts, and the calculation results of the oscillation angle. The grinding wheel systematically approaches the raceway from both ends to the middle, and finally envelops and forms the continuous and smooth convexity profile required by the design.

[0054] Processing mode selection: To adapt to different equipment conditions and workpiece characteristics, the processing technology in this solution is implemented through the following two equivalent processing modes. It should be noted that the following description uses the machining of the inner ring raceway 3 as an example; the processing principle, steps, and mechanism are completely the same for the outer ring raceway.

[0055] Processing mode 1: The workpiece is fixed and the grinding wheel 4 oscillates.

[0056] The structural feature of this mode is that the workpiece (bearing ring) only rotates around its axis, while the grinding wheel 4 and its drive device have the function of oscillating at positive and negative angles around a specific axis. The specific processing steps are as follows, and each step is designed with a specific mechanism: S31 Workpiece clamping: The inner ring 3 of the bearing to be processed is attracted and fixed on the magnetic pole 2 at the end of the rotating shaft 1.

[0057] S32 and both ends of the raceway are machined: Start the machining lathe, and the shaft 1 drives the inner ring 3 of the bearing to rotate. This causes the grinding wheel 4 and its drive device to deflect by a large positive angle ( At this angle, the working surface of grinding wheel 4 contacts both inclined surfaces of the 3V-shaped raceway of the bearing inner ring, mainly grinding the outer side of the left raceway and the inner side of the right raceway, as shown in the machining state. Figure 4 As shown in (b). Subsequently, the grinding wheel 4 and its drive mechanism are deflected by a large negative angle ( Processing status as follows Figure 4 As shown in (c), this creates symmetrical grinding zones on both sides of the raceway.

[0058] S33 progressively approaches the target profile: After machining both ends of the raceway, the grinding stage begins in the middle of the raceway. The grinding wheel 4 and its drive mechanism are sequentially set to deflect a series of progressively decreasing oscillation angles. The effective contact area between the grinding wheel 4 and the workpiece is sequentially shifted towards the center along the raceway surface. This achieves step-by-step envelope forming of the contour.

[0059] Processing mode 2: Grinding wheel 4 is fixed, and the workpiece swings.

[0060] The structural features of this mode are: the grinding wheel 4 only performs rotational and feed movements, maintaining a fixed spatial posture; while the oscillation function is performed by the workpiece (bearing inner ring 3) and its connection to the rotating shaft 1. Its specific machining steps and underlying mechanism correspond completely to Mode 1, only the object of motion distribution differs: S31 Workpiece clamping: The inner ring 3 of the bearing is also adsorbed and fixed on the rotating shaft 1 and driven to rotate.

[0061] S32 raceway end machining: First, set the bearing inner ring 3 deflection. Angle, so that the grinding wheel 4, with its spatial orientation fixed, contacts the two inclined surfaces of the V-shaped raceway. The contact state between the grinding wheel 4 and the raceway is as follows: Figure 5 As shown in (b), the grinding zone is formed. Subsequently, workpiece deflection is set. Angle, state as Figure 5 As shown in (c), a symmetrical grinding zone is formed. In this stage, a precise machining grinding zone is also established at both ends of the raceway by prioritizing large-angle oscillation.

[0062] S33 progressively approximates the target contour: Subsequently, the workpiece is deflected sequentially by a series of decreasing angles. Based on the same step-by-step envelope forming mechanism, as the workpiece swing angle gradually decreases, the effective grinding contact area of ​​the grinding wheel 4 on the raceway systematically shifts from both ends toward the center of the raceway. Through the superposition and envelope of grinding trajectories at this series of decreasing angles, the target convex profile is finally machined by the fixed grinding wheel 4.

[0063] This embodiment takes processing mode one as an example; the geometric relationships of each parameter are shown below. Figure 6 The key positions of the grinding wheel (① to ⑧) during the machining process and their correspondence with the steps are shown in [reference needed]. Figure 7 .

[0064] Specifically, step S32 includes: S321 Raceway Finishing: When grinding wheel 4 is in position ① (e.g.) Figure 4 (a) Figure 5 (a) state), at which point grinding wheel 4 performs finishing grinding on the raceway ( Figure 7 a) At this stage, no wobbling occurs. This process aims to obtain a straight reference raceway with precise dimensions and a smooth surface, eliminating errors from previous machining processes and providing an ideal geometric reference for subsequent convexity profile forming. The raceway has no convexity at this point.

[0065] It should be noted that after the bearing is machined and formed, it needs to be rough ground and fine ground (finished) before the raceway convexity is machined.

[0066] S322 First-stage convexity machining: First, calculate the initial radial retraction amount of grinding wheel 4 according to formula (2). To position ②. Then, according to formula (4), the positive oscillation angle of grinding wheel 4. To position ③, the grinding wheel 4 then uses the radial feed rate according to formula (3). Move to position ④ and begin grinding. In this position, grinding wheel 4 mainly acts on the outer side of the left raceway and the inner side of the right raceway, efficiently removing material to form the first level of convexity. Calculate the convexity value on one side according to formula (1). After completing the forward grinding, grinding wheel 4 retracts 2.118mm to return to position ③, then swings back to position ②. Next, grinding wheel 4 swings in the reverse direction. Then, the feed rate is increased by 2.118mm again to perform symmetrical machining on the other side of the raceway (the inner left side and the outer right side), thereby establishing a complete primary convexity boundary profile (i.e., machining at both ends of the raceway).

[0067] Step S33 specifically includes: S331 Reset: Grinding wheel 4 retracts 2.118mm and swings back to zero degrees, stabilizing at position ②, preparing for the next machining step.

[0068] S332 second-level convexity machining: such as Figure 7 As shown in (b), the angle to which the grinding wheel 4 oscillates is calculated according to formula (4). Upon reaching position ⑤, the feed rate is then calculated using formula (3). Move to position ⑥ for grinding. Reduce the oscillation angle to move the grinding area toward the center of the raceway. This step is mainly used to smoothly connect the convex boundary profile formed in step S322 with the middle of the raceway, achieving a continuous transition of the profile. From formula (1), the unilateral convexity value generated in this stage can be seen. Afterwards, the blade was withdrawn and straightened, with... The same feed rate is used to complete the grinding process on the symmetrical side.

[0069] S333 Reset: Grinding wheel 4 retracts 2.119mm and returns to position ②, preparing for the next machining step.

[0070] S334 third-level convexity machining: such as Figure 7 As shown in (c), according to formula (4), the swing angle of grinding wheel 4 Upon reaching position ⑦, the micro-feed amount is then calculated according to formula (3). Move to position ⑧ for grinding. This step uses the minimum oscillation angle and fine feed, with grinding concentrated in the middle area of ​​the raceway. According to formula (1), the unilateral convexity value at this stage can be determined. This ensures the overall outline ultimately aligns with the design goals. Following the same logic, complete... Reverse symmetrical grinding.

[0071] S335 machining completed: Grinding wheel 4 retracted 2.12mm and swung back to zero degrees (position ②), the raceway convexity machining program was completed.

[0072] Design mechanism: such as Figure 8 As shown, the adopted swing angle sequence (±3.12°→±1.679°→±0.62°) exhibits a clear decreasing trend. This sequence is directly calculated by formula (1), ensuring that each discrete grinding position accurately corresponds to the target convexity position point profile. The change of the swing angle from large to small systematically drives the effective grinding area of ​​the grinding wheel 4 to smoothly migrate from both ends of the raceway to the center, which is a direct manifestation of the "outside to inside" discrete envelope forming principle.

[0073] Key points of process control: The above swing angle sequence ( , , ), feed / retraction amount ( , , , The machining process is automated by integrating the existing CNC system program of the lathe with motion logic input. Machining is performed fully automatically under conditions of workpiece speed of 20,000 rpm and adequate high-pressure cooling. The CNC system sequentially and precisely drives the grinding wheel 4 to complete the above 7 steps. Each swing angle includes forward and reverse symmetrical grinding cycles to ensure the axisymmetric accuracy of the convex profile. The entire process requires no manual intervention, thus ensuring the stability and repeatability of the process and meeting the quality consistency requirements of mass production of precision bearings.

[0074] This concludes the detailed description of a method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to this disclosure. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0075] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing, characterized in that, Includes the following steps: S1, Calculate the crown value at the selected point for raceway crown machining. The convex profile of multiple points is a modified curve of intersecting circular arcs; The distribution of the raceway convexity value along the raceway direction is determined by formula (1): (1) in, For the reshaping curve of intersecting circular arcs, the first The convexity value of each selected processing point , This represents the total number of processing selection points; The radius of the intersecting arcs; This is the length of the straight section of the raceway; For the first The coordinates of each processing selection point along the raceway direction are measured starting from the center of the raceway; S2, calculate the feed and retraction amount of the grinding wheel (4) and the swing angle between the grinding wheel (4) and the workpiece to be processed during each machining process; The advance and retraction amount includes the initial retraction amount of the grinding wheel (4). and grinding wheel (4) The feed and retraction amount after each swing The results are obtained by formulas (2) and (3) respectively: (2) (3) The swing angle Calculated using formula (4): (4) in, Where is the roller radius; This refers to the length of the raceway; S3, Grinding wheel on machining lathe (4) Grinding the raceway convexity from both ends of the raceway to the middle according to the calculation results of step S2, and finally enveloping and forming the required continuous and smooth convexity profile.

2. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 1, characterized in that, In step S3 During the next processing, the grinding wheel (4) first reaches the swing angle. Then, complete another forward and backward cut.

3. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 2, characterized in that, Step S3 specifically includes: S31 Workpiece clamping: Fix the workpiece at the end of the spindle (1) in the machining lathe. The spindle (1) is used to drive the workpiece to rotate around its axis. At this time, the grinding wheel (4) is located on the radial side of the workpiece. S32 raceway end machining: Workpiece starts rotating, first feed. Then, the grinding wheel (4) and the workpiece are aligned... The grinding wheel oscillates, and the working surface of the grinding wheel contacts both inclined surfaces of the V-shaped raceway, grinding the outer side of the raceway on one side and the inner side of the raceway on the other side. Subsequently, the grinding wheel (4) is deflected relative to the workpiece. This creates symmetrical grinding zones on both sides of the raceway. S33 Gradual Approach to the Target Contour: After completing the grinding process at both ends of the raceway, the contour gradually takes shape; the swing angle between the grinding wheel (4) and the workpiece decreases sequentially, and the effective contact area between the grinding wheel (4) and the workpiece shifts sequentially from both ends to the middle along the raceway slope to achieve the enveloping process of the raceway convexity, approximating the required shaping curve.

4. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 3, characterized in that, In step S3, the swing angle control has two processing modes, namely: Processing mode 1: Control the grinding wheel (4) to swing relative to the workpiece; Processing mode 2: Control the workpiece to swing relative to the grinding wheel (4).

5. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 3, characterized in that, Before the convexity is processed, the raceway needs to be precision ground or smoothed.

6. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 1, characterized in that, The length of the raceway for: in, The width of the raceway U-groove is half.

7. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 1, characterized in that, The length of the straight section for: 。 8. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 3, characterized in that, The grinding wheel (4) retracts to the initial retraction position after each grinding operation and then returns to the center position.

9. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 1, characterized in that, In step S3, the convexity of both sides of the raceway is symmetrically processed.

10. The method for machining the raceway convexity of the inner and outer rings of a crossed roller bearing according to claim 9, characterized in that, The grinding wheel (4) is a high-mesh fine grinding wheel.

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