A Laser Processing Method and Device for Micro-Texturing of Gear Tooth Surfaces

Abstract

The present invention discloses a laser processing method and device for gear surface micro-texture. The processing method includes the following steps: establishing a finite element simulation analysis model for the surface contact characteristics of a gear pair under different working conditions; establishing a simulation analysis model for elastohydrodynamic lubrication of the gear pair under different working conditions to obtain the elastohydrodynamic lubrication characteristics of the gear pair; establishing a mapping relationship between pulsed laser processing parameters and the shape and size of the tooth surface micro-texture, building a laser processing device for tooth surface micro-texture that can adapt to various tooth profile shapes, and obtaining a precise processing process for the gear surface micro-texture. The device includes a base, a lifting platform, a lifting drive device, and a drive device for the gear pair to be processed. The lifting platform is located above the base, and the drive device for the gear pair to be processed is installed on the lifting platform, and the lifting of the lifting platform relative to the base is realized through the lifting drive device. It has the advantages of simple processing technology, strong controllability, adaptability to different types of gears, and no pollution.

Description

Technical Field

[0001] The present invention relates to the field of gear surface machining, and particularly to a laser machining method and device for gear surface micro-texture. Background Technique

[0002] Gear transmission has the advantages of strong transmission capacity, high transmission efficiency, good reliability, compact structure, good adaptability, etc., and is the most important transmission form in industrial production. In some precision electromechanical equipment and large mechanical devices, gears often serve as the core transmission components, directly affecting the operation status of the entire system. This requires gears to have extremely high transmission reliability and transmission accuracy. However, during the meshing transmission process of the gear pair, the working environment in the mutual contact area of the tooth surfaces is very harsh. Factors such as stress concentration, untimely heat dissipation, and poor lubrication conditions will all cause the friction and wear between the gear pair to increase, resulting in a significant reduction in the overall stability, reliability, and accuracy of the equipment, and even making the system unable to continue operating. Therefore, researching the anti-friction and lubrication technology for gear pairs and its application is of great significance to the development of the manufacturing industry.

[0003] In order to improve the friction and lubrication performance of gear pairs, after years of research, scientists have achieved a series of important results in aspects such as lubrication mechanism, high-performance lubricants, surface modification technology, and physical and chemical properties of materials, thus forming anti-friction methods such as lubricant modification, surface quenching, shot peening, carburizing and nitriding, functional coating modification of the overall gear structure, and material improvement. Among these methods, surface micro-texture machining has the unique advantages of good anti-friction effect, strong operability, and low cost, which also makes the surface micro-texture technology become a hot research direction in the field of gear anti-friction and lubrication.

[0004] The anti-friction and lubrication mechanism of tooth surface micro-texture mainly includes the following six aspects:

[0005] (1) Improve lubrication conditions. Due to the volatility of the lubricating oil, gears sometimes face poor oil lubrication conditions during the transmission process. At this time, the micro-texture plays the role of a "micro oil storage tank", which can supplement a small amount of oil to the tooth surface contact area to avoid the occurrence of dry friction, which is usually called "secondary lubrication". Under rich oil lubrication conditions, scholars have proposed the hydrodynamic lubrication theory. When the lubricating oil enters and exits the micro-texture driven by another tooth surface, due to the space divergence and space contraction effects, the oil pressure at the entrance of the micro-texture will decrease, and the oil pressure at the exit will increase; the existence of cavitation phenomenon makes the entrance pressure decrease to the cavitation pressure at the lowest, while the exit pressure will continue to increase. This internal pressure of the oil can be used to bear a part of the external pressure, improving the load-bearing capacity of the gear; at the same time, due to the continuous dynamic change of the oil film pressure, the oil film thickness increases compared with that without micro-texture, thus improving the friction and lubrication performance of the tooth surface.

[0006] (2) Reduce tooth surface wear. Due to the existence of the ploughing effect, it is inevitable that surface abrasive particles will fall off during the meshing transmission of gears. If the fallen abrasive particles cannot be discharged in time within the closed space of tooth surface meshing, scratches or micropits will be generated on the gear surface. Over time, the abrasive particles will cause serious damage to the tooth surface. Micro-textures can serve as "temporary storage pools" for abrasive particles to reduce the contact and wear between the abrasive particles and the gear pair. At the same time, they can also prevent the volume and hardness of the abrasive particles from continuously increasing under the extrusion of the gear pair, avoiding greater harm.

[0007] (3) Prevent the extension of tooth surface microcracks. Stress concentration areas are inevitable on the contact surface of the gear pair, and stress concentration often causes microcracks on the surface. When the generation area of the microcracks continues to increase, the "pitting" phenomenon will occur. The existence of surface micro-textures can prevent the continuous extension of microcracks in space. At the same time, the processing process of micro-textures will add a small amount of residual stress to the tooth surface. These residual stresses can cancel out the stresses caused by external loads, thereby reducing the stress concentration phenomenon on the tooth surface and preventing the expansion of the crack area from the root, which is beneficial to maintaining good tooth surface quality and lubrication conditions.

[0008] (4) Accelerate tooth surface heat dissipation. Under extreme working conditions such as high speed and heavy load, the contact surface of the gear pair often generates a relatively high temperature, which not only affects the working reliability of the entire equipment, but also may increase the viscosity of the lubricating oil, seriously reducing its lubrication performance. The existence of micro-textures increases the contact area between the tooth surface and air or lubricating oil, which can greatly improve the heat dissipation efficiency of the tooth surface and improve the lubrication conditions.

[0009] However, due to the special geometric structure of the gear and its own material properties, most micro-texture processing methods are not applicable to the processing of gear surface micro-textures. At present, the main processing methods for gear surface micro-textures include laser etching method, electrochemical etching method, conventional machining method, and abrasive air jet method. Among them, the electrochemical etching method requires complex processing equipment, the required chemical reagents are easy to cause environmental pollution, and it is difficult to accurately control the morphology and geometric parameters of the micro-textures; the microstructures left by the conventional machining methods (such as gear grinding and shaving) have a small scale, and the improvement effect on the anti-wear and lubrication performance of the gears is weak; the microstructures processed by the abrasive air jet method have a small size and are difficult to accurately control, and the dust pollution and noise pollution are serious during the processing process.

[0010] Compared with traditional machining, laser processing is a new type of non-contact machining method, which has the advantages of high processing efficiency, green and pollution-free, flexible and safe, and wide range of applicable materials. The laser etching method is the mainstream method in the field of tooth surface micro-texture processing. This method uses a short-pulse or ultra-short-pulse laser to etch the tooth surface. The surface temperature of the irradiated area of the light spot rises steeply, and the metal is directly vaporized or melted to achieve material removal, thereby generating surface micro-textures.

[0011] CN 108145396 A discloses a processing method for a micro-textured self-lubricating gear. The specific approach is as follows: Using a composite device consisting of a numerically controlled tool grinder, a laser marking device, and a high-pressure gas nozzle, appropriate laser parameters are set to machine a groove array with parallel and equally spaced distribution on the tooth surface. This processing method features high efficiency and high precision, can optimize the lubrication performance of the gear to a certain extent, and extend the service life of the gear. However, the improvement in the lubrication performance of the gear by the grooves with parallel and equally spaced distribution in this method is limited.

[0012] CN 111730211 B discloses a device for laser processing the surface of an involute cylindrical gear. By controlling the rolling motion of the collar on the electromagnetic chuck through an electric push rod, according to the property that the normal line of the involute of the gear base circle is always tangent to the gear base circle, the requirement that the laser beam is always perpendicular to the tangent of the tooth profile of the involute cylindrical gear is achieved, and the shape and depth of the machined grooves can be kept unchanged. However, this device is only applicable to the surface laser processing of involute cylindrical gears. Summary of the Invention

[0013] The purpose of the present invention is to provide a method and a precise processing device for micro-texturing the tooth surface of a gear, which use non-uniformly distributed textures to improve the anti-wear performance and lubrication performance of the gear and are applicable to the micro-texturing processing of tooth surfaces with various tooth profile shapes.

[0014] The laser processing method for the micro-texture of the gear tooth surface provided by the present invention includes the following steps:

[0015] (1) Establish a finite element simulation analysis model for the surface contact characteristics of the gear pair under different working conditions;

[0016] (2) Establish a simulation analysis model for elastohydrodynamic lubrication of the gear pair under different working conditions to obtain the elastohydrodynamic lubrication characteristics of the gear pair;

[0017] (3) Establish a mapping relationship between the pulsed laser processing parameters and the shape and size of the micro-texture on the tooth surface, build a laser processing device for the micro-texture of the tooth surface that can adapt to various tooth profile shapes, and obtain a precise processing technology for the micro-texture on the gear surface.

[0018] When implementing the above method, in step (1), a variety of pre-processing parameters are set to obtain the contact area, contact stress, and strain contact characteristics of the gear pair under different working conditions. The contact stress distribution and contact area of the gear pair are analyzed through experiments, and the finite element simulation analysis model for the surface contact characteristics of the gear is verified and corrected according to the experimental results.

[0019] When implementing the above method, in step (1), the micro-texture is only machined in the actual contact area of the gear pair, and the morphology of the micro-texture on the tooth surface includes but is not limited to pits and grooves.

[0020] When the above method is implemented, in step (2), a variety of pre-treatment parameters are set to obtain the elastohydrodynamic lubrication characteristics of the oil film thickness and oil film pressure on the surface of the gear pair under different working conditions.

[0021] When the above method is implemented, in step (2), based on the elastohydrodynamic lubrication characteristics of the surface of the gear pair under different working conditions, the size and spacing of the gradient-distributed tooth surface micro-textures are optimized. The optimization objective is to improve the uniformity of the oil film thickness and oil film pressure in the contact area of the gear pair. The optimization means is to set surface micro-textures with relatively small size and relatively small spacing in the area with small oil film thickness and large oil film pressure; set tooth surface micro-textures with relatively large size and relatively large spacing in the area with large oil film thickness and small oil film pressure.

[0022] When the above method is implemented, in step (3), a simulation model for pulse laser processing of tooth surface micro-textures is established to study the forming mechanism of surface micro-textures under the action of pulse laser ablation, and the forming size of tooth surface micro-textures under the action of different pulse laser parameters is obtained.

[0023] The processing device of the present invention applicable to the above processing method includes a base, a lifting platform, a lifting drive device, and a gear pair to be processed drive device. The lifting platform is located above the base, and the gear pair to be processed drive device is installed on the lifting platform, and the lifting of the lifting platform relative to the base is realized through the lifting drive device.

[0024] When the above device is implemented, a guiding column is arranged between the lifting platform and the base; the lifting drive device includes a first servo motor, a gear, a rack, and a pillar. The first servo motor is horizontally arranged on the lifting platform, connected to the gear through a coupling. The rack is vertically installed on the pillar, and the pillar is fixed on the base, and the gear meshes with the rack; the gear pair to be processed drive device is a horizontally arranged second servo motor, and the driving wheel of the gear pair to be processed is connected to the output shaft of the second servo motor through a coupling, and the driven wheel meshes with the driving wheel.

[0025] The method for processing gear tooth surface micro-textures using the above processing device provided by the present invention includes the following steps:

[0026] (1) Arrange the galvanometer of the laser directly above the driven wheel of the gear pair to be processed, so that the laser irradiates vertically downward.

[0027] (2) The first servo motor of the lifting drive device and the second servo motor of the gear pair to be processed drive device cooperate to control the height of the lifting platform and the phase of the driven wheel, so that the laser is always focused on its tooth surface during the rotation of the driven wheel, so as to ensure that the processed tooth surface micro-textures have the same depth.

[0028] During the laser processing, the output power of the laser light source and the height of the laser galvanometer of the laser are kept constant all the time to ensure the dimensional accuracy of the micro-texture on the tooth surface;

[0029] (4)After processing one tooth surface, the laser light source stops irradiating, and the two servo motors work together to make the next tooth to be processed enter the same initial phase as the previous tooth, and at the same time make the lifting platform return to the initial height when processing the tooth surface of the previous tooth;

[0030] (5)After all the tooth surfaces on one side of all the teeth of the driven wheel are processed, the galvanometer of the laser is horizontally moved to directly above the other side of the tooth surface, and the second servo motor of the driving device of the gear pair to be processed is controlled to work in the reverse direction to reverse the driven wheel, and refer to steps (2)-(4) to realize the processing of the micro-texture on the other side of all the teeth.

[0031] When the above method is implemented, when the size or type of the gear pair to be processed changes, the servo motors of the lifting drive device and the driving device of the gear pair to be processed are coordinated according to the geometric structure parameters of the gear pair to realize the laser processing of the gear tooth surface. The coordination parameters mainly include the absolute speed, relative speed and rotation direction of the servo motor.

[0032] The laser processing method for the micro-texture on the gear tooth surface proposed by the present invention, as well as the matching tooth surface laser pulse strengthening processing device, have the advantages of simple processing technology, strong controllability, adaptability to different types of gears, and no pollution. Compared with the uniform spacing distribution method of the micro-texture covering the entire tooth surface, based on the gear transmission contact characteristic simulation model and the elastohydrodynamic lubrication characteristic simulation model, the present invention proposes a new micro-texture distribution method: the micro-texture on the tooth surface is only distributed in the actual contact area of the gear pair tooth surface; the micro-texture spacing is gradient-distributed. It has the following advantages: (1) Avoid the ineffective processing of redundant micro-textures and improve the processing efficiency; (2) The gradient distribution of the micro-texture spacing can make the oil film thickness and oil film pressure in the lubrication process more uniform, thereby improving the lubrication and drag reduction characteristics of the gear pair. In addition, the present invention also proposes a laser processing device for the micro-texture on the gear tooth surface, which can realize the fine processing of the micro-texture on the gear tooth surface only by using the servo motor to coordinate and control the height of the lifting platform and the tooth phase. The present invention can provide a reference for improving the surface performance in different fields. Description of the Drawings

[0033] Figure 1 It is a schematic diagram of the parametric model of the preferred embodiment of the present invention.

[0034] Figure 2 is Figure 1 The research scheme flowchart of the tooth surface micro-texture zoning model of the model.

[0035] Figure 3a and Figure 3b is Figure 1Schematic diagram of the tooth surface micro-texture partition model and micro-texture morphology of the model.

[0036] Figure 4 Flow chart of the research plan for the tooth surface micro-texture gradient distribution design model.

[0037] Figure 5a and Figure 5b For the tooth surface micro-texture spacing gradient distribution model.

[0038] Figure 6 Flow chart of the research plan for the precise machining process of the gear tooth surface micro-texture.

[0039] Figure 7 Schematic diagram of the structure of the laser processing device for the gear tooth surface micro-texture.

[0040] Figure 8 Schematic diagram of the usage state of this embodiment. Detailed implementation manners

[0041] In order to improve the anti-wear performance and lubrication performance of the surface of the gear pair, the present invention proposes a new tooth surface micro-texture distribution model: (1) The tooth surface micro-texture is only distributed in the actual contact area of the gear pair surface; (2) The tooth surface micro-texture has a gradient distribution of spacing. By establishing a simulation model of the contact characteristics of the gear pair and a simulation model of the elastohydrodynamic lubrication characteristics, supplemented by experimental verification or correction, the actual contact area of the tooth surface contact, the optimal size and spacing of the micro-texture gradient distribution are obtained. Using the laser processing device for the gear tooth surface micro-texture, selecting appropriate laser processing parameters, and through the coordinated control of the height position of the tooth in the vertical direction and the phase of the tooth, the fine processing of the gear tooth surface micro-texture is realized.

[0042] Next, taking Figure 1 The tooth surface micro-texture processing of the helical gear pair shown as the specific implementation object of the present invention will be further described.

[0043] As Figure 2 In the research plan shown, using software platforms such as SolidWorks and CATIA to perform parametric modeling on the helical gear pair, and importing the geometric model into a finite element simulation software platform such as ANSYS, setting the material of the helical gear as an elastic body, and setting the Young's modulus and Poisson's ratio according to the material properties, and then performing mesh division on the parametric model. Subsequently, add constraint conditions to the model, and load working condition parameters such as input torque, input speed, and load. Perform finite element simulation calculations on the model, and obtain the contact characteristics such as contact stress, strain, and contact area of the helical gear pair through post-processing.

[0044] On the helical gear transmission experimental platform, the contact stress distribution and contact area on the helical gear pair are experimentally analyzed by using the methods of pasting strain gauges at the test points and applying red lead powder on the tooth surface; the experimental analysis results are compared with the analysis results of the above-mentioned simulation model of the surface contact characteristics of the helical gear pair to verify and correct the model.

[0045] Based on the simulation analysis model of the surface contact characteristics of the helical gear pair, parameters such as input torque, input speed, and load are changed to analyze the influence law of different working conditions on the surface contact characteristics of the helical gear pair, and the contact stress distribution and contact area of the helical gear pair under common working conditions are obtained.

[0046] As Figure 3a and Figure 3b shown, a tooth surface micro-texture zoning model is established based on the contact characteristics of the helical gear pair, and the morphology of the tooth surface micro-texture includes pits and grooves. The specific method is as follows: Based on the contact characteristics of the helical gear pair surface under different working conditions, the design of the gear surface texture model is carried out. In order to reduce the gear bending strength as little as possible and avoid problems such as the initiation and propagation of micro-cracks on the gear surface, surface micro-textures are only processed in the actual contact area of the helical gear pair surface to improve the processing efficiency and accuracy of the surface micro-textures.

[0047] As Figure 4 shown in the research plan, based on the finite element simulation analysis model of the surface contact characteristics of the gear pair, the tangential velocity, relative sliding velocity, entrainment velocity, comprehensive curvature radius, and normal line load distribution of the gear contact interface are calculated; according to the basic equations of elastohydrodynamic lubrication, including the Reynolds equation, film thickness equation, deformation equation, viscosity-pressure equation, density-pressure equation, and load balance equation, etc., a gear elastohydrodynamic lubrication simulation model is established; through finite element simulation analysis, the elastohydrodynamic lubrication characteristics such as oil film thickness and oil film pressure on the gear pair surface are obtained.

[0048] Based on the elastohydrodynamic lubrication simulation model of the helical gear pair, parameters such as input torque, input speed, and load are changed to analyze the influence law of different working conditions on the elastohydrodynamic lubrication characteristics of the helical gear pair, and the elastohydrodynamic lubrication characteristics such as oil film thickness and oil film pressure of the helical gear pair under common working conditions are obtained.

[0049] As Figure 5a and Figure 5bAs shown in the figure, a gradient distribution model of tooth surface micro-texture is established based on the elastohydrodynamic lubrication characteristics of helical gear pairs. The morphology of the tooth surface micro-texture includes pits and grooves. The specific method is as follows: According to the elastohydrodynamic lubrication characteristics of the helical gear pair surface under different working conditions, an optimization design of the gradient distribution of the tooth surface micro-texture based on the elastohydrodynamic lubrication characteristics of the gear pair is carried out; in order to ensure the uniformity of the oil film thickness and oil film pressure in the contact area of the gear pair, surface micro-textures with relatively small sizes and relatively small spacings are set in the areas with small oil film thickness and large oil film pressure; surface micro-textures with relatively large sizes and relatively large spacings are set in the areas with large oil film thickness and small oil film pressure, so as to construct a gradient distribution design scheme of the tooth surface micro-texture. Preferably, the radius of the pit and the groove width of the groove are initially set to 20 - 200 μm, and the spacing gradient of the pit and the groove is initially set to 50 - 200 μm. Further, the geometric dimensions and spacings of the surface micro-textures with gradient distribution are optimized. The specific method is as follows: First, the trial-and-error method is used to obtain the micro-texture size range and gradient range that can make the oil film thickness and oil film pressure relatively uniform, and then data points are selected in this range for a full-factor experiment, so as to obtain the best gradient distribution scheme of the tooth surface micro-texture that makes the oil film thickness and oil film pressure uniformity in the entire contact area of the gear pair optimal.

[0050] As Figure 6 shown in the research scheme, based on the mechanical properties and constitutive equations of the gear material itself, a simulation model for machining surface micro-textures by the pulsed laser strengthening method is established, and the forming mechanism of the surface micro-textures under the action of pulsed laser strengthening is studied from aspects such as temperature field, phase transformation, and deformation, and the forming dimensions of the surface micro-textures under the action of different pulsed laser strengthening parameters are obtained. The mapping relationship between the pulsed laser strengthening parameters and the surface micro-texture dimensions is established by methods such as orthogonal experiments, main effect analysis, and nonlinear fitting.

[0051] In order to ensure that the laser can machine surface micro-textures with a consistent depth on the curved surface contour of the tooth surface, the present invention proposes a gear tooth surface micro-texture laser processing device that can adapt to various tooth profile shapes, as Figure 7 shown. The structural composition and working principle of this device are as follows:

[0052] As Figure 7 shown, the processing device mainly includes a base 1, guide columns 2, a lifting platform 3, support columns 4, a rack 5, a lifting drive gear 6, a driving wheel 7, a driven wheel 8, servo motors 9 and 10, an upper housing 11, and a lower housing 12.

[0053] The lifting platform 3 is located above the base 1. Guide columns 2 are respectively arranged at the four corners of the base corresponding to the lifting platform, and each guide column passes through the base to guide the lifting of the lifting platform and ensure the stable lifting of the lifting platform.

[0054] The support column 4 is fixed at the middle position on the left side of the base. In order to enhance the stability of the support column, support bars 6 are symmetrically arranged on both sides of it for limiting and reinforcement.

[0055] The rack 5 is fixed to the inner side of the support column 4, and the servo motor 9 is fixed to the lifting platform 3. The lifting drive gear 6 connected to the output shaft thereof through a coupling meshes with the rack 5. When the servo motor 9 works, the lifting of the lifting platform is realized.

[0056] The servo motor 10 is fixed to the lifting platform 3. The output shaft thereof is connected to the driving wheel 7 of the gear pair to be processed through a coupling. The driven wheel 8 of the gear pair to be processed meshes with the driving wheel 7. Other transmission structures driven by the gear pair to be processed are encapsulated by the upper housing 11 and the lower housing 12. The upper and lower housings are detachably connected through fasteners, and the lower housing is fixed to the lifting platform.

[0057] The driven wheel 8 is the gear to be processed. The laser scanner galvanometer of the laser is located directly above the driven wheel, and the laser light source irradiates vertically downward to process the tooth surface.

[0058] In order to make the micro-textures processed by this device have the same depth, a programmable cooperative control system for the servo motor and the processing device is developed, so that the servo motors 9 and 10 cooperate under the instruction of the central controller to regulate the height of the lifting platform 3 and the phase of the gear to be processed, so that the laser can always focus on its tooth surface when the driven wheel 8 rotates, as Figure 8 shown.

[0059] Specifically, the parameters of the laser are initially set as follows: the laser scanning speed is 100 - 2000 mm / s, the number of scans is 1 - 10 times, the output current is 1 - 10 A, the pulse repetition frequency is 10 - 50 kHz, the pulse width is 1 - 10 μs, the spot diameter is 10 - 50 μm, the laser wavelength is 355 nm, and the output power of the laser is 5 - 20 W.

[0060] During the laser processing, the output power of the laser light source and the height of the laser scanner galvanometer always remain unchanged to ensure the dimensional accuracy of the tooth surface micro-texture; after processing one tooth surface, the laser light source stops irradiating, and the two servo motors work together to make the next tooth to be processed enter the same initial phase as the previous tooth, and at the same time make the lifting platform 3 return to the initial height when processing the tooth surface of the previous tooth.

[0061] After processing one side tooth surface of all the teeth, only need to control the laser scanner galvanometer to horizontally move to directly above the other side of the tooth surface, and control the driven wheel 8 to rotate in the reverse direction through the servo motor 10, then the processing of the other side of all the tooth surfaces can be realized with reference to the above process.

[0062] When the size of the helical gear pair changes, only need to change the cooperative parameters of the two servo motors according to the geometric structure parameters of the helical gear pair, then the laser processing of the tooth surface micro-texture of the replaced gear can be realized. The cooperative parameters of the two servo motors mainly refer to the absolute speed, relative speed and rotation direction of the motors.

[0063] On the laser processing device for micro-texture on the gear tooth surface, the mapping relationship between the pulsed laser strengthening parameters and the geometric dimensions of the helical tooth surface micro-texture is established, and the tooth surface micro-texture consistent with the gradient distribution tooth surface micro-texture design model is processed. Using experimental equipment such as optical microscopes and scanning electron microscopes, the differences between the tooth surface micro-texture design model and the actual dimensions are compared and analyzed, and the tooth surface micro-texture design model is repeatedly corrected. On this basis, the laser processing technology for the helical gear tooth surface micro-texture is optimized to form a precise processing technology method for the helical gear surface micro-texture.

[0064] Generally speaking, in order to improve the anti-wear performance and lubrication performance of the gear pair surface and solve the problem of uneven oil film thickness and oil film pressure on the tooth surface, the present invention proposes a new tooth surface micro-texture distribution model:

[0065] (1) The tooth surface micro-texture is only distributed in the actual contact area of the gear pair surface, aiming to reduce the gear bending strength as little as possible and avoid the initiation and expansion of tooth surface micro-cracks, while improving the processing efficiency and accuracy of the surface micro-texture; (2) The tooth surface micro-texture has a gradient distribution, aiming to improve the uniformity of the oil film thickness and oil film pressure in the contact area of the gear pair. By establishing a contact characteristic simulation model and an elastohydrodynamic lubrication characteristic simulation model of the gear pair, supplemented by experimental verification or correction, the actual contact area of the tooth surface contact, the optimal dimensions and spacing of the micro-texture gradient distribution are obtained.

[0066] When a conventional laser processing device processes gears, the laser focal length is fixed and the relative height between the laser light source and the gear remains unchanged, resulting in inconsistent depths of the tooth surface micro-texture processed. To solve this problem, the processing device in the present invention selects appropriate laser processing parameters and cooperatively controls the height position of the tooth in the vertical direction and the phase of the tooth by a servo motor to achieve consistent depths of the micro-texture on the gear tooth surface.

Claims

1. A laser processing method for gear tooth surface micro-texture, comprising the following steps: (1) Establish a finite element simulation analysis model for the surface contact characteristics of a gear pair under different working conditions; (2) Establish a simulation analysis model for elastohydrodynamic lubrication of a gear pair under different working conditions to obtain the elastohydrodynamic lubrication characteristics of the gear pair; (3) Establish a mapping relationship between pulsed laser processing parameters and the shape and size of the tooth surface micro-texture, build a laser processing device for tooth surface micro-texture that can adapt to various tooth profile shapes, and obtain a precise processing technology for the gear surface micro-texture; In the step (1), set a variety of pre-processing parameters to obtain the contact area, contact stress, and strain contact characteristics of the gear pair under different working conditions, analyze the contact stress distribution and contact area of the gear pair through experiments, and verify and correct the finite element simulation analysis model of the surface contact characteristics of the gear surface according to the experimental results; In the step (2), set a variety of pre-processing parameters to obtain the elastohydrodynamic lubrication characteristics of the oil film thickness and oil film pressure on the surface of the gear pair under different working conditions; In the step (2), based on the elastohydrodynamic lubrication characteristics of the surface of the gear pair under different working conditions, optimize the size and spacing of the gradient distribution tooth surface micro-texture. The optimization goal is to improve the uniformity of the oil film thickness and oil film pressure in the contact area of the gear pair. The optimization means is to set surface micro-textures with relatively small size and relatively small spacing in the area with small oil film thickness and large oil film pressure; set tooth surface micro-textures with relatively large size and relatively large spacing in the area with large oil film thickness and small oil film pressure; In the step (3), establish a simulation model for pulsed laser processing of tooth surface micro-texture, study the forming mechanism of surface micro-texture under the action of pulsed laser ablation, and obtain the forming size of tooth surface micro-texture under the action of different pulsed laser parameters.

2. The laser processing method for gear tooth surface micro-texture according to claim 1, characterized in that: In the step (1), only process the tooth surface micro-texture in the actual contact area of the gear pair. The morphology of the tooth surface micro-texture includes but is not limited to pits and grooves.

3. A processing device applicable to the processing method described in claim 1 or 2, characterized in that: The device includes a base, a lifting platform, a lifting drive device, and a drive device for the gear pair to be processed. The lifting platform is located above the base, and the drive device for the gear pair to be processed is installed on the lifting platform. The lifting of the lifting platform relative to the base is realized through the lifting drive device; A guide post is arranged between the lifting platform and the base; the lifting drive device includes a first servo motor, a gear, a rack, and a pillar. The first servo motor is horizontally arranged on the lifting platform and is connected to the gear through a coupling. The rack is vertically installed on the pillar, and the pillar is fixed on the base. The gear meshes with the rack; the drive device for the gear pair to be processed is a horizontally arranged second servo motor. The driving wheel of the gear pair to be processed is connected to the output shaft of the second servo motor through a coupling, and the driven wheel meshes with the driving wheel.

4. A method for processing gear tooth surface micro-texture using the processing device described in claim 3, comprising the following steps: (1) Arrange the galvanometer of the laser directly above the driven wheel of the gear pair to be processed so that the laser irradiates vertically downward; (2)The first servo motor of the lifting drive device and the second servo motor of the driven gear pair drive device for the gear to be machined cooperate to regulate the height of the lifting platform and the phase of the driven wheel, so that the laser is always focused on its tooth surface during the rotation of the driven wheel, ensuring that the tooth surface micro-textures machined have the same depth; (3)During the laser machining process, the output power of the laser light source and the height of the laser scanner of the laser are always kept unchanged to ensure the dimensional accuracy of the tooth surface micro-textures; (4)After machining one tooth surface, the laser light source stops irradiating, and the two servo motors work together to make the next tooth to be machined enter the same initial phase as the previous tooth, and at the same time make the lifting platform return to the initial height when machining the tooth surface of the previous tooth; (5)After all the tooth surfaces on one side of all the teeth of the driven wheel are machined, move the scanner of the laser horizontally to directly above the other side of the tooth surface, and make the second servo motor of the driven gear pair drive device work in the reverse direction to control the reverse rotation of the driven wheel, and refer to steps (2)-(4) to realize the machining of the micro-textures on the other side of all the teeth.

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