A laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing

Abstract

The invention discloses a laser phase change hardening processing method for the surface of a four-point contact ball bearing raceway. A laser is hinged at the end of a six-degree-of-freedom industrial robot arm at the center of the raceway curvature, and a Gaussian heat source is used as the laser light source of the laser. A turntable performs a uniform circular rotation along the central axis of the bearing, and the laser swings from a starting point to an end point along the radius of curvature of the raceway on a vertical plane. The turntable rotates one circle to generate a spiral first circle of laser phase change hardening area, and the turntable rotates one circle again to generate a spiral second circle of laser phase change hardening area, and so on to complete the laser phase change hardening processing. A spiral phase change hardening gap is formed in the middle of the two circles of laser phase change hardening areas, and the power and spot size of the laser are changed, and a second laser spot is output to scan the surface middle area of ​​the phase change hardening gap, and a spiral groove texture is processed on the gap surfaces of different circles, and finally a hardened layer with relatively uniform depth is formed, which has the advantages of processing continuity and high efficiency.

Description

Technical Field

[0001] The present invention relates to the field of laser phase change hardening processing, and specifically to a method for laser phase change hardening processing of a large four-point contact ball bearing raceway surface. The laser spot is much smaller than the large four-point contact ball bearing raceway surface to be processed, and multiple laser scanning is required to achieve large-area phase change hardening of the raceway. Background Art

[0002] The contact angle between the ball and the raceway of the four-point contact ball bearing is generally 45° in the original assembly. It can bear axial load, radial load and overturning moment at the same time during operation. The contact angle between the ball and the raceway increases with load. It is widely used in metallurgical machinery, wind turbines, medical machinery and other fields. With the development of manufacturing process technology, engineering applications have put forward higher requirements for the raceway surface of four-point contact ball bearings. Laser phase change hardening is to use a high-energy laser beam to irradiate the metal surface, and the photons excite the atoms and electrons on the metal surface to change its vibration or motion state. The atoms absorb heat energy and diffuse to the adjacent atoms. The metal matrix is ​​rapidly heated and self-cooled in a very short time to achieve phase change hardening on the surface of the workpiece. Through laser phase change hardening processing, a hardened structure dominated by fine martensite will be formed on the surface of the material at room temperature, which greatly improves the hardness and wear resistance of the material surface. Laser phase change hardening adjusts the hardening depth by adjusting the laser power, bandwidth, scanning speed, etc. to achieve a good laser surface phase change hardening effect. Laser phase change hardening has a fast heating speed and a small heat-affected zone, which reduces the thermal deformation of the material. At the same time, laser phase change hardening will produce compressive stress on the surface of the material, thereby improving the wear resistance and fatigue resistance of the material surface. Compared with traditional surface phase change hardening processes, such as flame surface phase change hardening, induction surface phase change hardening and other technologies, laser phase change hardening has a wide range of applications, high processing precision and high degree of automation.

[0003] When laser phase transformation hardening is performed on the raceway surface of a large four-point contact ball bearing, since the laser spot is much smaller than the raceway surface to be processed, a multi-channel surface spot overlap process is required. When performing multi-channel laser scanning, the two adjacent lasers will inevitably overlap to a certain extent, that is, the two laser phase transformation hardenings will produce overlapping areas. The martensitic structure located in the overlapping area of ​​the two laser phase transformation hardenings is reheated to produce tempering, and eventually transforms into tempered martensite with lower hardness, that is, a soft zone. The existence of the soft zone will make the surface phase transformation hardening layer unevenly distributed and reduce the processing efficiency to a certain extent. The overlap rate refers to the ratio of the area of ​​the laser spot overlap area to the area of ​​a single laser scan. When the overlap rate is 0%, the middle position of the two laser spot areas will not undergo phase transformation strengthening due to insufficient temperature, and the hardness improvement is not obvious. When the overlap rate is too large, although the hardness uniformity of the quenching layer can be improved, the area of ​​the tempering area will increase, while reducing the processing efficiency. Therefore, choosing a suitable overlap rate can well reduce the area of ​​the tempering area, while maintaining the uniformity of the hardening layer hardness and improving work efficiency. However, the selection of overlap ratio is often complicated and needs to be determined through multiple experiments.

[0004] The device proposed in the document entitled "A device and method for reducing soft bands in laser quenching" with Chinese patent publication number CN108048626B precisely sprays light-absorbing coating on the preset overlap area of ​​the laser located on the surface of the workpiece, improves the light-absorbing properties of the preset overlap area, and reduces the soft band width of the overlap area, thereby obtaining a more uniform laser-strengthened surface. However, the device is not suitable for the processing of the surface of large annular bearing raceways. The processing method proposed in the document entitled "A laser phase change hardening processing method for the surface of a large annular bearing raceway" with Chinese patent application number 202211143041.7 realizes the processing of the flat raceway of a large annular bearing through two lasers, and at the junction of the laser spot, i.e., the soft band, a pit-groove texture method is used to solve the problem of uneven hardness distribution on the raceway surface. However, this method cannot solve the processing of arc-shaped raceways and is not suitable for the structural form of four-point contact ball bearings. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of laser phase change hardening processing of the raceway surface of large four-point contact ball bearings and the easy generation of soft bands during the laser phase change hardening process, resulting in uneven hardness distribution on the raceway surface and low processing efficiency. A laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing is proposed to ensure the continuity of phase change hardening of the raceway surface of a large four-point contact ball bearing, hardness uniformity and hardened layer depth.

[0006] To achieve the above object, the present invention provides a method for laser phase change hardening of the raceway surface of a four-point contact ball bearing, which adopts a technical solution: the inner ring or outer ring of the bearing to be processed is coaxially fixed on the upper surface of a horizontal turntable, and a six-degree-of-freedom industrial robot is arranged at the center of the bearing, and further includes the following steps:

[0007] Step 1): A laser is hinged at the end of the robot arm of the six-degree-of-freedom industrial robot at the center of the raceway curvature, and the laser light source of the laser adopts a Gaussian heat source;

[0008] Step 2): The turntable rotates in a uniform circular motion along the central axis of the bearing, and the laser swings from the starting point to the end point along the radius of curvature of the raceway in the vertical plane. The laser spot output by the laser scans the raceway surface. The turntable rotates one circle to generate a spiral first circle of laser phase change hardening area. The turntable rotates one circle again to generate a spiral second circle of laser phase change hardening area, and so on to complete the laser phase change hardening process; the two circles of laser phase change hardening areas do not contact each other, and there is a spiral phase change hardening gap in the middle;

[0009] Step 3): changing the power and spot size of the laser, outputting a second laser spot to scan the middle area of ​​the surface of the phase change hardening gap, and processing a spiral groove texture on the surface of the phase change hardening gap in different circles.

[0010] Furthermore, when the groove texture is processed in step 3), the scanning method of the laser is the same as the scanning method in step 2).

[0011] Furthermore, on the vertical plane, an angle θ is formed between the two ends of the laser spot 1 and the connecting line of the center of the raceway curvature, an angle θ1 is formed between the two ends of the phase change hardening gap and the connecting line of the center of the raceway curvature, and when the turntable rotates one circle, the laser swing angle is θ+θ1.

[0012] Furthermore, in step 3), the power of the laser light spot 2 output by the laser is greater than the power of the laser light spot 1 output by the laser.

[0013] Furthermore, the arc length of the second laser spot irradiated on the raceway surface is equal to the arc length of the phase change hardening gap, and the arc length of the second laser spot is greater than the arc length of the groove texture.

[0014] Furthermore, the arc length of the laser phase change hardening area generated by the second laser spot is greater than the arc length of the second laser spot.

[0015] Furthermore, after the groove texture processing is completed, the electronic circular runout meter is connected to the robot arm, and the six-degree-of-freedom industrial robot drives the electronic circular runout meter to swing along the circumferential direction of the raceway in the vertical plane, and measures the surface roughness of the raceway from the starting point to the end point. At the same time, the raceway surface is divided into M equal parts in the circumferential direction of the raceway. The turntable stops after rotating 360o / M, and rotates 360o / M again after measuring the roughness of each circumferential direction to complete the roughness measurement of the entire raceway processing surface.

[0016] Furthermore, after the roughness measurement and detection of the upper raceway of the bearing outer ring is completed, only the laser swing position is changed to the curvature center of the lower raceway of the bearing outer ring to process the lower raceway of the bearing outer ring.

[0017] Furthermore, the contact angle of contact point B between the rolling element and the raceway when the bearing raceway is under maximum load is greater than the contact angle of initial contact point A when the bearing raceway and the rolling element are assembled, the contact angle of the starting point of the laser oscillation is greater than the contact angle of point B, and the contact angle of the ending point is less than the contact angle of point A.

[0018] Compared with the prior art, the present invention has the following outstanding beneficial effects:

[0019] 1) The present invention uses only one laser to process the circular arc raceway, and the laser light source is a Gaussian heat source, with high heat in the middle and low heat on both sides. At the same time, the Gaussian heat source is also affected by the irradiation distance. When the Gaussian heat source irradiates the plane vertically, the middle is close to the Gaussian heat source, the heat received is more, and the depth of the hardened layer is deep. The two sides are far away from the Gaussian heat source, the heat received is less, and the depth of the hardened layer is shallow, and eventually an elliptical hardened layer with uneven depth will be formed. When the Gaussian heat source irradiates the circular raceway of the four-point contact ball bearing, the distance between the two sides of the circular raceway and the light spot is close, and more heat is obtained. Combined with the characteristics of the Gaussian heat source itself, the heat in the middle is high and the heat on both sides is low, so the heat source received by the circular raceway is evenly distributed, and eventually a hardened layer with relatively uniform depth is formed.

[0020] 2) The spiral swing laser scanning strategy is used to perform phase change hardening processing on the surface of the raceway of large four-point contact ball bearings. It is composed of two-directional motion, which reduces the processing path and improves the processing continuity, ensuring the uniformity of hardness and hardness depth of the entire raceway surface. At the same time, after the upper raceway of the outer ring of the four-point contact ball bearing is processed, only the six-degree-of-freedom manipulator needs to be located at the center of curvature of other raceways to process the lower raceway of the outer ring of the bearing. The laser rotation direction of the two processing processes is consistent, and the laser and turntable speed are consistent. It has the advantages of processing continuity, high efficiency, and high degree of automation, which is easy to realize automated processing and improve processing efficiency.

[0021] 3) There is a gap between the two adjacent circles of phase change hardening on the raceway surface, and the spot length of the groove texture processing is equal to the gap between the two adjacent circles of phase change hardening. The groove texture generates much more heat than the laser phase change hardening. The heat generated by the groove texture is also laser phase change hardened, connecting the two adjacent circles of laser phase change hardening areas to complete the laser phase change hardening of the entire raceway surface. At the same time, the groove helps the flow of lubricant, allowing the lubricant to carry away metal chips and impurities and ensure the flow of lubricant, and has a certain pressure bearing capacity to ensure the integrity of the oil film when large annular bearings are subjected to large loads.

[0022] 4) The spiral oscillating laser scanning for surface laser phase change hardening of the present invention is also applicable to other non-planar bearing raceway surfaces, shaft parts and rod parts that require continuous laser phase change hardening. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0024] Figure 1 It is an axial cross-sectional view of the local structure of a four-point contact ball bearing;

[0025] Figure 2 It is an overall structural assembly diagram of the outer ring and rolling elements of a four-point contact ball bearing;

[0026] Figure 3 For Figure 2 The state diagram of the four-point contact ball bearing raceway surface after laser phase transformation hardening processing;

[0027] Figure 4 For Figure 3 An enlarged schematic diagram of the laser machining of the raceway on the outer ring of a bearing;

[0028] Figure 5 This is an enlarged schematic diagram of the laser phase transformation hardening and groove texture of the laser phase transformation hardening area processed on the raceway surface of the bearing outer ring.

[0029] Figure 6 for Figure 4 A magnified schematic diagram of the spiral light spot, phase transformation hardening area, and groove texture distribution when processing from point C to point B on the upper raceway surface of the bearing outer ring from the F viewing angle;

[0030] Description of reference numerals:

[0031] 1. Bearing outer ring; 2. Rolling element; 3. Bearing inner ring; 4. Bearing outer ring bolt hole; 5. Bearing outer ring upper raceway; 6. Bearing outer ring lower raceway; 7. Bearing inner ring upper raceway; 8. Bearing inner ring lower raceway; 9. Bearing inner ring bolt hole; 10. Six-degree-of-freedom industrial robot; 11. Turntable; 12. Laser spot one; 13. Laser spot two; 14. High-strength bolt; 15. Laser; 16. Groove texture; 17. Gap phase change hardening area; 18. Laser one first circle phase change hardening area; 19. Laser one second circle phase change hardening area. DETAILED DESCRIPTION

[0032] like Figure 1 and Figure 2 The four-point contact ball bearing shown in the figure includes a bearing outer ring 1 and a bearing inner ring 3. Between the bearing outer ring 1 and the bearing inner ring 3 is a rolling element 2. The upper part of the rolling element 2 is in contact with the bearing outer ring upper raceway 5 and the bearing inner ring upper raceway 7 in the form of point contact, and the lower part of the rolling element 2 is in contact with the bearing outer ring lower raceway 6 and the bearing inner ring lower raceway 8 in the form of point contact, forming a four-point contact. When not loaded, the initial contact angle at the four-point contact is generally 45°. The bearing inner ring 3 is provided with an axially penetrating bearing inner ring bolt hole 9, and the bearing outer ring 1 is provided with an axially penetrating bearing outer ring bolt hole 4. With the central axis direction of the four-point contact ball bearing as the Z axis direction, the two radial directions of the bearing are the X and Y directions, and the origin O is located on the central axis, an OXYZ coordinate system is established.

[0033] like Figure 3 As shown, the present invention is described by taking the processing of the raceway 5 on the outer ring of the bearing as an example. A six-degree-of-freedom industrial robot 10 is arranged at the center of the four-point contact ball bearing, the head end of the robot arm of the six-degree-of-freedom industrial robot 10 is located at the center of the outer ring 1 of the bearing, the end of the robot arm extends toward the bearing raceway, and a laser 15 is hinged at the end, and the hinge between the end of the robot arm and the laser 15 is located at the center of curvature of the raceway to be processed. Since the present invention takes the processing of the raceway 5 on the outer ring of the bearing as an example, the hinge is located at the center of curvature O1 of the raceway 5 on the outer ring of the bearing.

[0034] The bearing outer ring 1 to be processed is placed on the upper surface of the turntable 11, and the central axes of the two are colinear. If the bearing inner ring 3 is to be processed, the bearing inner ring 3 is coaxially placed and fixed on the upper surface of the turntable 11. The turntable 11 is parallel to the XY plane, and the bearing outer ring 1 and the turntable 11 are fixed together with high-strength bolts 14 at the bolt holes 4 of the bearing outer ring. When the turntable 11 rotates, the bearing outer ring 1 is driven to rotate synchronously.

[0035] Since the large four-point contact ball bearing is large in size, the turntable 11 is first positioned horizontally, and then the bearing outer ring 1 is hoisted on the turntable 11, so that the bearing outer ring 1 and the rotation axis of the turntable 11 coincide, and the lower surface of the bearing outer ring 1 fits the upper surface of the turntable 11. Rotate the turntable 11, measure the circular runout of the upper surface of the bearing outer ring 1, the circular runout should be less than 0.05mm, fine-tune the bearing outer ring 1 to ensure that the bearing outer ring 1 is horizontal, and then use high-strength bolts 14 to fix the bearing outer ring 1 to the turntable 11, and measure the circular runout of the upper surface of the bearing outer ring 1 again, the circular runout should be less than 0.05mm, and ensure the horizontality of the bearing outer ring 1.

[0036] like Figure 3 As shown in FIG4 , when the six-degree-of-freedom industrial robot 10 drives the laser 1 to move, it is ensured that the joint between the laser 15 and the robot arm is always located at the curvature center O1 of the raceway 5 on the outer ring of the bearing. With the curvature center O1 as the origin, the O1X1Z1 plane coordinate system is established as follows: Figure 4 As shown, the Z1 axis is parallel to the Z axis, the X1 axis is parallel to the X axis, and the X1Z1 vertical plane is the plane where the laser 15 irradiates the laser scan. The contact angle is the acute angle between the laser scanning direction and the X1 axis. The initial contact point of the raceway to be processed, that is, the raceway 5 on the outer ring of the bearing and the rolling element 2 when assembled is point A, and the contact angle of point A is the acute angle between the O1A line and the X1 axis. When the raceway is subjected to the maximum load, the contact point of the rolling element 2 and the raceway is point B, and the contact angle of point B is the acute angle between the O1B line and the X1 axis. The contact angle of point B is α, and the contact angle of point B is greater than the contact angle of point A. In order to ensure that the contact part between the rolling element 2 and the raceway 5 on the outer ring of the bearing is processed, select point C on the raceway when the contact angle is slightly greater than the maximum load. Point C is the starting point of processing. The contact angle of point C is the acute angle between the O1C line and the X1 axis, and the contact angle of point C is greater than the contact angle of point B. Select point D on the raceway where the contact angle is slightly smaller than the initial contact point to end. Point D is the end point of the processing. The contact angle at point D is the acute angle between the O1D line and the X1 axis. The contact angle at point D is smaller than the contact angle at point A. The center of curvature O1 and points A, B, C, and D are all on the same X1Z1 vertical plane. The laser 15 takes the raceway curvature center O1 as the origin and swings along the raceway from the starting point C to the ending point D on the X1Z1 vertical plane. The contact angle changes from the contact angle at point C to the contact angle at point D.

[0037] The laser light source of laser 15 adopts Gaussian heat source, which has high heat in the middle and low heat on both sides. At the same time, Gaussian heat source is also affected by the irradiation distance. When the Gaussian heat source irradiates the plane vertically, the middle is close to the Gaussian heat source, the heat received is more, and the depth of the hardened layer is deep. The two sides are far from the Gaussian heat source, the heat received is less, and the depth of the hardened layer is shallow. Therefore, an elliptical hardened layer with uneven depth will eventually be formed on the circular raceway. When the Gaussian heat source irradiates the circular raceway of the four-point contact ball bearing, the two sides of the circular raceway are close to the light spot and receive more heat. Combined with the characteristics of the Gaussian heat source itself, the heat received by the circular raceway is evenly distributed, and finally a hardened layer with uniform depth is formed.

[0038] The present invention adopts a spiral swing laser scanning strategy to perform phase change hardening processing and gap groove texture heat improvement method. The laser scanning path is composed of two directional movements. One movement is provided by the turntable 11, and it performs constant speed circular motion along the Z axis of the bearing rotation center. The other movement is provided by the six-degree-of-freedom industrial robot 10 that clamps the laser 15. With the center of curvature O1 of the arc raceway on the outer ring of the bearing 1 as the center of the circle, it swings along the curvature radius of the raceway in the X1Z1 vertical plane. The two movements are combined into a spiral swing laser scanning to complete the laser phase change hardening processing and gap texture processing of the raceway surface. A gap is formed between the two laser spots output by the laser 15, and then a groove texture is added at the gap. Specifically:

[0039] During processing, the turntable 11 is kept in a constant speed circular rotation motion, and the speed of the turntable is v. Figure 4 As shown, the starting position of the raceway surface machining is at point C, and the contact angle at point C is 4°-5° greater than the contact angle α at point B, starting from point C. Figure 4 , the laser 15 starts working and starts processing at the processing starting position C. The laser 15 swings along the curvature direction of the raceway at the center of the raceway curvature O1. The output laser spot scans the raceway surface. The rotating table 11 rotates at an angular velocity of w1 and the time for one rotation is t. Figure 5 and Figure 6 As shown, the laser 15 is located at the center O1 of the raceway curvature for irradiation, and the light spot irradiates the surface of the raceway 5 on the outer ring of the bearing, forming a laser spot 12 on the raceway surface. The laser spot 12 generates a phase change hardening area on the raceway. The turntable 11 rotates one circle to generate a first circle of laser phase change hardening area 18. The turntable 11 rotates one circle again to generate a second circle of laser phase change hardening area 19. The second circle of laser phase change hardening area 19 on the raceway surface has the same structure as the first circle of laser phase change hardening area 18, but the position is different. The two adjacent circles of laser phase change hardening areas do not contact each other, and there is a gap in the middle, that is, the first circle of laser phase change hardening area 18 and the second circle of laser phase change hardening area 19 do not contact each other, and there is a gap in the middle, which is called the phase change hardening gap.

[0040] On the X1Z1 vertical plane, the angle formed between the two ends of the laser spot 12 and the connecting line of the raceway curvature center O1 is θ, and the angle formed between the two ends of the phase change hardening gap and the connecting line of the raceway curvature center O1 is θ1. The angular velocity w of the laser 15 swinging along the raceway curvature direction at the raceway curvature center O1 is w=(θ+θ1) / t. When the turntable 11 starts to rotate, the six-degree-of-freedom industrial robot 10 drives the articulated laser 15 to swing on the X1Z1 vertical plane, that is, with the curvature center O1 of the raceway 5 on the outer ring of the bearing as the center of the circle, the turntable 11 rotates one circle, and the swing angle of the laser 15 is (θ+θ1). The rotational motion of the turntable 11 and the swinging motion of the laser 15 are combined to form a spiral scanning method, such as Figure 6 As shown, the first circle of the raceway laser phase change hardening process is completed, that is, the first circle of laser phase change hardening area 18 is completed; then the composite motion is repeated to process the second spiral laser phase change hardening circle on the raceway surface, that is, the second circle of laser phase change hardening area 19, and the same analogy is repeated, and the spiral swing laser scanning of the laser 15 is formed by the composite of the two motions, and finally the laser phase change hardening process from point C to point D is completed. The contact angle of the end point D at the end position of the processing is 4°-5° smaller than the contact angle of the initial contact point A.

[0041] When all the laser phase change hardening is completed, there is a phase change hardening gap on the raceway surface between two adjacent circles of laser phase change hardening, and the phase change hardening gap is spiral on the raceway surface. At this time, the laser 15 stops working, and the turntable 11 also stops working. After changing the power and spot size of the laser 15, the turntable 11 and the laser 15 start working again, outputting the second laser spot 13. The second laser spot 13 starts scanning in the middle area of ​​the phase change hardening gap surface, and processes a spiral groove-shaped texture on the phase change hardening gap surface of different circles, that is, the groove texture 16, as shown in FIG. Figure 6 As shown, the groove texture 16 is also spiral-shaped.

[0042] When the power of the laser 15 is changed, the power of the laser spot 2 13 output by the laser 15 is greater than the power of the laser spot 1 12 output by the laser 15. When the power spot size of the laser 15 is changed, the arc length of the laser spot 2 13 irradiated on the raceway surface is equal to the arc length of the phase change hardening gap in the X1Z1 vertical plane. Since the power of the output laser spot 12 is relatively small, the arc length of the first circle laser phase change hardening area 18 and the second circle laser phase change hardening area 19 is smaller than the arc length of the laser spot 12; and since the power of the output laser spot 2 13 is relatively large, the arc length of the laser phase change hardening area generated by the laser spot 2 is greater than the arc length of the laser spot 2 13, and the arc length of the laser spot 2 13 is greater than the arc length of the groove texture 16.

[0043] When processing the groove texture 16, the laser 15 scans in the same way, which is composed of two movements. The first movement is a constant speed circular motion around the central axis O provided by the turntable 11, and the second movement is a circular motion along the raceway in the X1Z1 vertical plane provided by the six-degree-of-freedom industrial robot 10. The rotation speed of the turntable 11 is still v, and the groove texture 16 is processed along the center of the phase change hardening gap. The contact angle formed by the laser 15 is fine-tuned to ensure that the center position of the processed groove texture 16 coincides with the center of the phase change hardening gap. The laser 15 is still located at the center of the raceway curvature O1. After the light spot is irradiated onto the raceway surface, the angle formed by the two ends of the light spot and the raceway curvature center O1 is θ, and the angle formed by the two ends of the raceway surface at the phase change hardening gap and the raceway curvature center O1 is θ1. The time for the turntable 11 to rotate one circle is t, and the angular velocity of the laser 15 swinging along the raceway curvature direction at the raceway curvature center O1 is w=(θ+θ1) / t.

[0044] While the laser spot 13 scans the phase change hardening gap to form the groove texture 16, a heat affected zone is generated for phase change hardening. Figure 6 As shown, on the X1Z1 vertical plane, since the arc length of the laser phase change hardening area generated by the laser spot 13 is greater than the arc length of the laser spot 13, and the arc length of the laser spot 13 is greater than the arc length of the groove texture 16, the size of the laser spot 13 is equal to the gap size left on the raceway surface between two adjacent circles of laser phase change hardening, so that the phase change hardening area of ​​the groove texture 16 is connected with the laser phase change hardening areas 18 and 19 to generate a gap laser phase change hardening area 17, as shown in FIG. Figure 5 As shown, the first and second laser phase change hardening areas 18 and 19 are combined with the gap laser phase change hardening area 17 therebetween to complete the laser phase change hardening process of the entire raceway surface, ensuring the hardness uniformity and hardness depth of the contact area between the rolling element 2 and the raceway surface, and largely avoiding the generation of soft bands. At the same time, the presence of the groove texture 16 facilitates the flow of the lubricant, allowing the lubricant to carry away metal debris and impurities.

[0045] After the laser phase change hardening and groove texture 16 are processed, the electronic circular runout meter is connected to the robot arm, installed on the six-degree-of-freedom industrial robot 10, and connected to the computer. The raceway surface is divided into M equal parts in the circumferential direction of the raceway, and the roughness of the laser phase change hardening circumferential direction is measured. The measurement method is composed of two movements. One direction is provided by the turntable 11, which stops after rotating 360o / M. The other direction is driven by the six-degree-of-freedom industrial robot 10 to swing the electronic circular runout meter along the circumferential direction of the raceway in the YZ vertical plane, measuring from the starting point C to the end point D. After the measurement is completed, the electronic circular runout meter is separated from the raceway surface, the turntable 11 rotates 360o / M and stops, and the electronic circular runout meter contacts the raceway surface and measures from point C to point D. By analogy, after measuring each laser phase change hardening roughness in the circumferential direction, the turntable 11 rotates 360o / M and stops. The roughness measurement of the entire raceway processing surface is completed, and the hardening uniformity of the raceway surface is analyzed.

[0046] After the processing and inspection of the upper raceway 5 of the outer ring of the four-point contact ball bearing is completed, there is no need to make too many changes. The six-degree-of-freedom manipulator 10 only needs to change the rotation center of the laser 15 to the center of curvature of the lower raceway 6 of the outer ring of the bearing, and then the lower raceway 6 of the outer ring of the bearing can be processed. The rotation direction of the laser 15 is consistent in the two processing processes, and the speed of the laser 15 is consistent with that of the turntable 11. It has the advantages of processing continuity, high efficiency, and high degree of automation, and it is easy to realize automated processing and improve processing efficiency.

[0047] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing, wherein the inner ring or outer ring of the bearing to be processed is coaxially fixed on the upper surface of a horizontal turntable (11), and a six-degree-of-freedom industrial robot (10) is arranged at the center of the bearing, wherein the method is characterized by: The following steps are involved: Step 1): A laser (15) is hinged at the end of the robot arm of the six-degree-of-freedom industrial robot (10) at the center of the raceway curvature, and the laser light source of the laser (15) adopts a Gaussian heat source; Step 2): The turntable (11) performs a uniform circular rotation along the central axis of the bearing, and the laser (15) swings from the starting point to the end point along the radius of curvature of the raceway in a vertical plane. The laser spot (12) output by the laser (15) scans the raceway surface. The turntable (11) rotates one circle to generate a spiral first circle laser phase change hardening area (18). The turntable (11) rotates one circle again to generate a spiral second circle laser phase change hardening area (19), and so on to complete the laser phase change hardening process; the two circles of laser phase change hardening areas do not contact each other, and there is a spiral phase change hardening gap in the middle; Step 3): Change the power and spot size of the laser (15), output laser spot 2 (13) to scan the middle area of ​​the surface of the phase change hardening gap, and process spiral groove textures (16) on the surface of the phase change hardening gap in different circles.

2. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 1 is characterized in that: On the vertical plane, the two ends of the laser spot 1 (12) form an angle θ with the connecting line of the center of the raceway curvature, and the two ends of the phase change hardening gap form an angle θ1 with the connecting line of the center of the raceway curvature. When the turntable (11) rotates one circle, the swing angle of the laser (15) is θ+θ1.

3. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 1 is characterized by: In step 3), the power of the laser spot 2 (13) output by the laser (15) is greater than the power of the laser spot 1 (12) output by the laser (15).

4. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 3 is characterized in that: On the vertical plane, the arc length of the second laser spot (13) irradiated on the raceway surface is equal to the arc length of the phase change hardening gap, and the arc length of the second laser spot (13) is greater than the arc length of the groove texture (16).

5. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 4 is characterized by: The arc length of the laser phase change hardening area generated by the laser spot 2 (13) is greater than the arc length of the laser spot 2 (13).

6. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 1 is characterized by: In step 3), when the groove texture (16) is processed, the scanning method of the laser (15) is the same as the scanning method in step 2).

7. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 1 is characterized by: When the bearing raceway is subjected to maximum load, the contact angle of the contact point B between the rolling element and the raceway is greater than the contact angle of the initial contact point A when the bearing raceway and the rolling element are assembled. The contact angle of the starting point of the swing of the laser (15) is greater than the contact angle of point B, and the contact angle of the ending point is less than the contact angle of point A.

8. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 7 is characterized by: The contact angle at the starting point is 4°-5° greater than the contact angle at point B, and the contact angle at the ending point is 4°-5° smaller than the contact angle at point A.

9. The laser phase change hardening processing method for the raceway surface of a four-point contact ball bearing according to claim 1 is characterized by: After the groove texture (16) is processed, the electronic circular runout meter is connected to the robot arm, and the six-degree-of-freedom industrial robot (10) drives the electronic circular runout meter to swing along the circumferential direction of the raceway in the vertical plane, and measures the surface roughness of the raceway from the starting point to the end point. At the same time, the raceway surface is divided into M equal parts in the circumferential direction of the raceway, and the turntable (11) stops after rotating 360o / M, and rotates 360o / M again after measuring the roughness of each circumferential direction, thereby completing the roughness measurement of the entire raceway processing surface.

10. A laser phase change hardening processing method for a four-point contact ball bearing raceway surface according to claim 9, characterized in that: After the roughness measurement and detection of the upper raceway of the bearing outer ring is completed, only the swing position of the laser (15) is changed to the curvature center of the lower raceway of the bearing outer ring to process the lower raceway of the bearing outer ring.

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