Active control method for worm grinding wheel grinding surface texture based on micro-pulse grinding
By introducing micro-pulse grinding technology into the worm gear grinding process, a controllable mesh-like tooth surface texture is generated, which solves the problems of gear meshing noise and insufficient stiffness, and improves the surface quality and meshing performance of the gear.
Patent Information
- Application Number
- CN202311628735.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-28
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2043-11-28
AI Technical Summary
In the existing worm gear grinding process, the regular texture of the tooth surface along the tooth direction leads to greater noise and insufficient meshing stiffness during gear meshing, and is prone to pitting defects.
The worm gear grinding method using micro-pulse grinding generates a controllable mesh-like tooth surface texture by adding sinusoidal micro-pulse motion to the radial feed axis of a CNC gear grinding machine, thereby changing the texture distribution on the gear surface.
It effectively reduces gear meshing noise, increases meshing stiffness, reduces surface defects, and improves gear surface quality.
Smart Images
Figure CN117444322B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of machining, in particular to a worm grinding wheel gear grinding tooth surface texture active regulation method based on micro-pulse grinding. BACKGROUND
[0002] Gear is a very important basic transmission component in mechanical equipment, which directly affects the performance and reliability of mechanical equipment. High-speed low-noise transmission gear is a key component of automatic transmission of automobile, and the noise and vibration requirements of new energy vehicles on the transmission system are more stringent than those of fuel vehicles. Existing research shows that the gear tooth surface texture is closely related to the noise behavior of the gear, and the periodic regular texture of the gear tooth surface in the direction of the tooth will cause large meshing noise when the gear meshes. At the same time, it is also easy to produce tooth surface pitting defects, which will affect the noise excitation of gear meshing stiffness, gear impact, air and lubricating oil release, etc.
[0003] For worm grinding wheel gear finishing process, the formation of tooth surface texture in the machining process is determined by two macro and micro movements. Macroscopically, it is the double-parameter envelope movement of the worm grinding wheel relative to the gear, which determines the formation of the contact trace on the tooth surface. When the worm grinding wheel completes the entire axial stroke, several small contact traces will be formed on the tooth surface. Microscopically, it is the grinding movement of the abrasive grains on the worm grinding wheel relative to the tooth surface, which determines the grinding path and the shape of the grinding mark of the abrasive grains on the tooth surface. The abrasive grains on the worm grinding wheel grind the tooth surface along the grinding path on the contact trace, forming the entire tooth surface texture. The conventional worm grinding wheel grinding method will produce regular texture along the tooth direction on the tooth surface. Therefore, changing the worm grinding wheel grinding texture is crucial for reducing the vibration and noise of the gear. SUMMARY
[0004] Therefore, in order to change the parallel regular texture along the tooth direction generated by the worm grinding wheel continuous generation grinding, and further reduce the large meshing noise generated by the gear in meshing, the present application provides a method for generating controllable irregular texture based on micro-pulse worm grinding wheel grinding. In particular, the straight gear and the helical gear are ground to improve the meshing characteristics of the gear and reduce the meshing noise.
[0005] The present application realizes the following technical scheme: a worm grinding wheel gear grinding tooth surface texture active regulation method based on micro-pulse grinding, which is suitable for a numerical control gear grinding machine of a worm grinding wheel, the numerical control gear grinding machine comprising a radial feed shaft and an axial feed shaft, and the active regulation method comprising the following steps:
[0006] Step S1, fixing the gear to be machined on the machining table of the numerical control gear grinding machine, performing conventional grinding, and scanning and measuring the surface of the machined gear to obtain the tooth surface texture ditch height;
[0007] Step S2, a micro-pulse motion of a sine wave is added in the direction of the radial feed shaft, to generate a controllable meshed tooth surface texture on the tooth surface of the gear; the micro-pulse motion of the sine wave includes setting parameters of the micro-pulse motion and generating a micro-pulse grinding program; the parameters of the micro-pulse motion are formulaed as follows:
[0008]
[0009] wherein A1 is the original position of the radial feed shaft in the grinding process, A is the amplitude of the micro-pulse motion, ω is the frequency of the micro-pulse motion, and x is the interpolation point of the radial feed shaft in the NC program of the numerical control gear grinding machine;
[0010] A mapping relationship between the radial feed shaft and the tooth surface normal is defined, and the mapping relationship is as follows:
[0011]
[0012] wherein ΔS is the tooth surface normal direction change amount, Δx is the feed amount of the radial feed shaft, and α is the pressure angle of the division circle of the gear to be machined;
[0013] wherein the tooth surface normal direction change amount is the same as the groove height of the tooth surface texture, and the feed amount of the radial feed shaft is the amplitude of the micro-pulse motion;
[0014] Step S3, the generated micro-pulse grinding program is copied to the numerical control system of the numerical control gear grinding machine and replaces the original program, and the rotational speed n B and the axial movement speed υ f of the main shaft of the gear grinding machine are set, and the worm grinding wheel performs micro-pulse grinding according to the movement track of the micro-pulse grinding program;
[0015] Steps S1 to S3 are performed on one of the gears in different batches to obtain the micro-pulse grinding program and replace the original program, and the gears in the same batch are machined by the same micro-pulse grinding program.
[0016] As a preferred example, the surface of the machined gear is scanned and measured by a white light interferometer.
[0017] As a preferred example, the radial feed shaft is used to control the movement of the worm grinding wheel of the numerical control gear grinding machine in the radial direction of the gear.
[0018] As a preferred example, the axial feed shaft is used to control the movement of the worm grinding wheel of the numerical control gear grinding machine in the axial direction of the gear.
[0019] As a preferred example, in the micro-pulse grinding process, a contact trace line is generated on each tooth surface of the gear for each rotation of the gear.
[0020] As a preferred example, when the gear is a straight gear, the direction of the contact trace on the tooth surface of the worm grinding wheel is distributed along the involute end section shape during each meshing in and out of the worm grinding wheel and the gear.
[0021] As a preferred example, when the gear is a helical gear, the direction of the contact trace on the tooth surface of the worm grinding wheel is obliquely arranged during each meshing in and out of the worm grinding wheel and the gear.
[0022] As a preferred example, the oblique directions of the contact traces on the two tooth surfaces of the same tooth on the gear are oppositely arranged.
[0023] As a preferred example, the frequency and amplitude of the micro-pulse motion are realized by changing the NC program of the numerical control gear grinding machine tool.
[0024] As a preferred example, the gear after micro-pulse grinding is extracted, and the surface is scanned and measured to detect whether the generated tooth surface texture is reticular.
[0025] The beneficial effects of the present application are embodied in the following aspects:
[0026] 1. The micro-pulse grinding based worm grinding wheel gear texture active control method provided by the present application acquires specific information of the gear surface topography by using a white light interferometer, so as to determine the size of the amplitude of the micro-pulse, and can accurately control the texture of the gear surface. This helps to improve the performance of the gear, reduce surface defects, and improve the surface quality.
[0027] 2. The texture active control method of the present application can change the regular texture parallel to the direction of the tooth in the original worm grinding wheel gear grinding, generate controllable reticular tooth surface texture, thereby reduce the meshing impact and slow down the generation of noise, in order to meet the demand of gear vibration and noise reduction. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 It is a schematic diagram of the worm grinding wheel numerical control gear grinding machine tool and the directions of the plurality of numerical control shafts thereof;
[0029] Figure 2 It is a schematic diagram of each direction on a single tooth of a gear;
[0030] Figure 3 It is a surface topography diagram of a gear under a conventional grinding mode;
[0031] Figure 4 It is a part of the NC program of the micro-pulse motion;
[0032] Figure 5 It is a schematic diagram of the contact trace on the tooth surface of a gear;
[0033] Figure 6The surface topography of the gear under the micro-pulse grinding mode. DETAILED DESCRIPTION
[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.
[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments and is not intended to limit the present application. The term "or / and" used herein includes any and all combinations of one or more related listed items.
[0036] Please refer to Figure 1 In the embodiment, the machining equipment used is YW7232CNC numerical control gear grinding machine tool, which includes a bed, nine numerical control shafts and an electronic gear box. The numerical control gear grinding machine includes a computer control system which controls the movement of the above-mentioned shafts according to the instructions input to the machine tool controller, which uses Siemens 840Dsl system. In the process of gear grinding, there are mainly six shafts participating in the movement, which are respectively the grinding wheel frame rotary shaft A1, the grinding wheel rotary shaft B1, the workbench rotary shaft C1, the radial feed shaft X1 (relative to the radial direction of the gear), the tangential feed shaft Y1 of the grinding wheel and the axial feed shaft Z1 (relative to the axial direction of the gear).
[0037] In the embodiment, the parameters of the gear and worm grinding wheel involved are as follows: the modulus m n1 of the gear to be machined = 4mm, the number of teeth z1 = 35, the helix angle β1 = 30°, the normal pressure angle α n1 = 20°, the tooth width b n1 = 30mm. The modulus m n2 of the worm grinding wheel = 4mm, the number of heads z2 = 3, the helix angle γ2 = 2.596°. The worm grinding wheel gear surface texture active regulation method based on micro-pulse grinding includes the following steps:
[0038] Step S1, obtaining the surface topography of the gear under the conventional grinding mode: fixing the gear to be machined on the workbench of the numerical control gear grinding machine, and performing conventional grinding processing. Then placing the machined gear on the white light interferometer, and scanning the surface of the gear by the white light interferometer, so as to obtain the topography information of the gear surface. Through this step, the accurate data of the gear surface is obtained, including the tooth surface texture ditch height, the tooth surface concave-convex distribution and other information. For example,Figure 2 As shown, the worm grinding wheel continuously develops the tooth surface along the direction of the tooth surface, which is the direction of the tooth surface along the thickness of the gear. By Figure 3 The tooth surface topography shown can obtain the texture groove height of 2 μm under the conventional grinding processing.
[0039] Step S2, generating micro-pulse grinding NC program: the radial feed axis X1 is used to control the movement of the worm grinding wheel on the workpiece gear in the radial direction. The movement position of the radial feed axis X1 will affect the topography of the gear surface. By adding a sinusoidal micro-pulse motion to the radial feed axis X1, the original grinding motion position is changed, and the topography of the gear surface is changed. The motion formula of the radial feed axis X1 with micro-pulse grinding is as follows:
[0040]
[0041] In the formula, A1 is the original position of the radial feed axis X1 in the grinding process, A is the amplitude of the micro-pulse motion, ω is the frequency of the micro-pulse motion, and x is the interpolation point of the radial feed axis X1 in the NC program of the CNC gear grinding machine.
[0042] There is a certain mapping relationship between the feed amount of the radial feed axis X1 and the change amount of the normal direction of the tooth surface, and the mapping relationship is as follows:
[0043]
[0044] In the formula, ΔS is the change amount of the normal direction of the tooth surface, Δx is the feed amount of the radial feed axis X1, and α is the pressure angle of the division circle of the gear to be processed.
[0045] In order to prevent the topography of the gear surface from changing too much, the change size ΔS of the normal direction of the tooth surface is the same as the tooth surface texture groove height under the conventional grinding processing. The size of ΔS is set to 2 μm, so that the feed amount of the radial feed axis X1 is ΔX = 2 / sin20° = 5.8 μm, which is the size of the micro-pulse amplitude A.
[0046] Step S3, micro-pulse grinding generates controllable mesh tooth surface texture: the movement position of the radial feed axis X1 is changed by setting the value of the interpolation point of the radial feed axis X1 in the LEAD_CALC_DATA_SPF program of the CNC gear grinding machine. There are 0 to 105 interpolation points in the NC program (numerical control program), in order to avoid the truncation of the sine wave, the number of NC program interpolation points contained in one sine wave should be from 3, and always be odd. In this embodiment, 3 NC program interpolation points are taken as one sine wave period, and the pulse amplitude is 5.8 μm. The machine tool LEAD_CALC_DATA_SPF spline NC program is changed, part of which is as follows:Figure 4 The changed NC program is copied to a designated folder of the numerical control system in the gear grinding machine tool, and replaces the original program. The rotational speed n B = 3000 r / min and the axial movement speed υ f = 60 mm / min of the main shaft of the gear grinding machine tool are set. The machine tool is started, and the worm grinding wheel performs micro-pulse grinding processing according to the movement track planned by the new NC program, so as to generate controllable meshy gear surface texture on the gear surface. One of the gears in different batches is first processed by conventional grinding, and the micro-pulse grinding program is generated after the parameters required by micro-pulse grinding are obtained. The gears in the same batch can be processed by the same micro-pulse grinding program.
[0047] Based on the spatial meshing motion degree of freedom theory, the degree of freedom of worm grinding is analyzed. The worm grinding wheel and the workpiece gear are regarded as the meshing transmission of worm and gear, and the worm grinding wheel has the feeding motion along the axial direction of the workpiece gear. Therefore, the transmission between the workpiece gear and the worm grinding wheel is no longer the fixed gear ratio transmission. In the meshing motion of worm grinding, there are two independent motions, the rotation of the worm grinding wheel and the feeding motion along the axial direction of the gear, and the transmission between the worm grinding wheel and the workpiece gear is the double-degree-of-freedom meshing motion, so as to form the contact points on the gear surface. As shown in Figure 5 , the workpiece gear generates a contact trace on each gear surface of the gear with each rotation of the workpiece gear. At the same time, the motion of the worm grinding wheel along the axial feeding shaft Z1 direction makes the contact trace make spiral ascending motion along the cylindrical surface of the workpiece gear, until covering all the gear surfaces. The contact trace is related to the workpiece gear. When the workpiece gear is a spur gear, the contact points on the gear surface are distributed along the involute end section shape with each meshing in and out of the worm grinding wheel and the gear, that is, the contact trace is an involute. When the workpiece gear is a helical gear, the contact trace on the gear surface will be inclined, and the inclination directions of the left and right gear surfaces are opposite.
[0048] The present application creatively changes the surface texture of the gear by adding micro-pulse grinding on the radial feeding shaft X1. Since the motion state of each shaft of the grinding wheel is according to the given position motion in the LEAD_CALC_DATA_SPF spline file of the machine tool. When the axial feeding shaft Z1 moves a distance along the axial direction of the gear, the radial feeding shaft X1 will move according to the given micro-pulse grinding mode, so as to grind a contact trace on the gear surface. The contact trace will form a height difference in the normal direction of the gear surface due to the micro-pulse grinding mode, and macroscopically form the gear surface texture along the contact trace direction (since the radial feeding shaft X1 only affects the cutting amount of the gear along the radial direction of the gear, the cutting amount will change constantly by adding micro-pulse vibration on the radial feeding shaft X1, that is, it will be large and small from time to time, so as to change the texture of the gear surface in the macroscopic view).
[0049] As shown in Figure 6 The tooth surface machined by the micro pulse grinding is placed under the white light interferometer to detect the tooth surface morphology and obtain the tooth surface morphology generated by the micro pulse grinding. Compared with the tooth surface morphology generated by the conventional grinding, it is found that the micro pulse grinding can generate the reticular texture along the contact trace direction and the tooth direction respectively, change the single regular texture along the tooth direction under the conventional grinding mode, thereby helping to improve the performance of the gear, reduce the surface defects, improve the surface quality, and help to reduce the meshing impact and slow down the generation of noise.
[0050] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the description.
[0051] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the present application. It should be pointed out that for the ordinary skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.
Claims
1. A worm grinding wheel tooth surface texture active regulation method based on micro-pulse grinding, which is suitable for a numerical control worm grinding machine tool of a worm grinding wheel, the numerical control worm grinding machine tool comprising a radial feed shaft and an axial feed shaft, characterized in that, The radial feed shaft is used to control the movement of the worm grinding wheel of the numerical control gear grinding machine in the radial direction of the gear; the axial feed shaft is used to control the movement of the worm grinding wheel of the numerical control gear grinding machine in the axial direction of the gear; the active control method comprises the following steps: Step S1, fixing the gear to be processed on the machining table of the numerical control gear grinding machine, performing conventional grinding processing, and scanning and measuring the surface of the processed gear to obtain the tooth surface texture groove height; Step S2, increasing a sinusoidal micro-pulse motion in the direction of the radial feed shaft to generate a controllable mesh tooth surface texture on the tooth surface of the gear; the sinusoidal micro-pulse motion comprises setting parameters of the micro-pulse motion and generating a micro-pulse grinding program; the parameter formula of the micro-pulse motion is as follows: In the formula, A1 is the original position of the radial feed shaft in the grinding process, A is the amplitude of the micro-pulse motion, ω is the frequency of the micro-pulse motion, and x is the interpolation point of the radial feed shaft in the NC program of the numerical control gear grinding machine; The mapping relationship between the radial feed shaft and the normal direction of the tooth surface is defined, and the mapping relationship is as follows: In the formula, ΔS is the change amount of the normal direction of the tooth surface, Δx is the feed amount of the radial feed shaft, and α is the pressure angle of the division circle of the gear to be processed; The change amount of the normal direction of the tooth surface is the same as the tooth surface texture groove height, and the feed amount of the radial feed shaft is the amplitude of the micro-pulse motion; Step S3, copying the generated micro-pulse grinding program to the numerical control system of the numerical control gear grinding machine and replacing the original program, setting the spindle speed n of the gear grinding machine B and axial movement speed υ f , the worm grinding wheel performs micro-pulse grinding according to the movement trajectory of the micro-pulse grinding program; Steps S1 to S3 are performed on one gear in different batches to obtain the micro-pulse grinding program and replace the original program, and gears in the same batch are processed by the same micro-pulse grinding program.
2. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 1, characterized in that, The surface of the processed gear is scanned and measured by a white light interferometer.
3. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 1, characterized in that, In the micro-pulse grinding process, a contact trace line is generated on each tooth surface of the gear for each revolution of the gear.
4. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 3, characterized in that, When the gear is a spur gear, the contact trace lines on the tooth surface are distributed along the involute end section shape in each meshing-in and meshing-out process of the worm grinding wheel and the gear.
5. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 3, characterized in that, When the gear is a helical gear, the contact trace lines on the tooth surface are obliquely arranged in each meshing-in and meshing-out process of the worm grinding wheel and the gear.
6. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 5, characterized in that, The inclination directions of the contact trace lines on the two tooth surfaces of the same tooth on the gear are oppositely arranged.
7. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 1, characterized in that, The frequency and amplitude of the micro-pulse motion are realized by changing the NC program of the numerical control gear grinding machine.
8. The micro-pulse grinding based worm grinding wheel tooth surface texture active regulation method according to claim 1, characterized in that, The processed gear is extracted, and the surface thereof is scanned and measured to detect whether the generated tooth surface texture is meshed.