Composite worm grinding wheel and dressing method thereof

Abstract

The invention discloses a composite worm grinding wheel and a dressing method thereof.The composite worm grinding wheel is composed of a surface micro-structured grinding wheel body and a fine grinding wheel body which are axially connected into a whole, the surface micro-structured grinding wheel body adopts ultrasonic vibration to assist a single-point diamond pen in dressing, and a large number of separated-continuous oblique curve micro grooves are dressed in the tooth side face; cutting force, heat production and the temperature of a contact area are reduced by reducing the contact layer, the effective blade grinding number of the grinding wheel during grinding is increased, and the problems of blockage of the grinding wheel and thermal damage to the surface of a workpiece are effectively solved; a fine grinding working face is formed on the outer side tooth face of the fine grinding wheel, and the problem that the surface roughness is large is solved by using grinding materials with the large particle size number. The device integrates the functions of rough grinding and accurate grinding, machining is completed through one-time clamping, repeated clamping and positioning errors are reduced, materials are efficiently removed, chip removal and heat dissipation are improved, the machining precision and size consistency are improved, and the contradiction that efficiency, heat dissipation and surface quality are difficult to consider in the generating grinding process is solved.

Description

Technical Field

[0001] This invention belongs to the field of precision gear grinding technology, specifically, it relates to a composite worm gear grinding wheel and its dressing method. Background Technology

[0002] Worm wheel grinding, as a highly efficient and precise continuous generating grinding method, has significant advantages in gear manufacturing. However, when the wheel linear velocity is high, grinding burns are easily generated on the gear surface. To achieve efficient grinding without thermal damage, the chip formation process needs to be optimized to minimize the friction between the grinding wheel and the workpiece. In traditional grinding, millions of abrasive grains come into contact with the workpiece every second, but only a portion of these grains have a cutting effect. The remaining grains generate heat through friction, causing elastic and plastic deformation. To maximize the number of active abrasive grains and ensure that the static cutting edge is as close as possible to the dynamic cutting edge, structured grinding wheel design has been developed. Structured grinding wheels refer to creating a special structure on the grinding wheel surface to reduce the static cutting edge, thereby reducing cutting force, machining power consumption, and heat generation in the contact area. This provides an effective technical approach to overcome the bottleneck of grinding thermal damage. Researchers are attempting to design novel matrix-structured grinding wheels by combining matrix structuring and grinding wheel surface structuring. Nguyen et al. designed a grinding wheel with internal micropores and a continuously grooved surface, allowing grinding fluid to directly act on the grinding zone through these micropores and surface grooves. Compared to traditional grinding wheels, this effectively reduces machining temperature and alleviates workpiece surface burns. Barmouz et al., based on fluid dynamics concepts, designed a structured grinding wheel with built-in Venturi cooling channels and surface grooves. Grinding experiments verified that this wheel not only provides high fluid velocity in the workpiece interaction area but also significantly reduces grinding force. Tawakoli, through structural treatment of the grinding wheel, using a 25% contact layer, effectively reduced cutting force, heat generation, and contact area temperature. However, these methods may lead to increased surface roughness, making it impossible to simultaneously achieve efficient chip removal, heat dissipation, and high surface quality during grinding.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a composite worm grinding wheel and its dressing method. This composite worm grinding wheel includes a surface micro-structured grinding wheel and a fine grinding wheel. The surface micro-structured grinding wheel is dressed using ultrasonic vibration-assisted single-point diamond pen dressing, with numerous separated-continuous oblique curve micro-grooves arranged on the tooth side. The outer tooth surface of the surface micro-structured grinding wheel forms a rough grinding working surface, reducing the contact area to lower cutting force and contact area temperature, effectively avoiding grinding wheel clogging and thermal damage to the workpiece surface. The outer tooth surface of the fine grinding wheel forms a fine grinding working surface, using a larger abrasive grain size to solve the problem of high surface roughness and improve workpiece quality. Simultaneously, the integrated structure allows for rough and fine grinding of the workpiece in a single clamping operation using the surface micro-structured grinding wheel and the fine grinding wheel, reducing repeated clamping and positioning errors between different processes. While achieving efficient removal and good chip removal and heat dissipation performance, it further improves the workpiece's machining accuracy and dimensional consistency, thus effectively solving the problem of simultaneously achieving efficient removal, chip removal and heat dissipation, and high surface quality during generating grinding.

[0005] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0006] A composite worm gear grinding wheel includes a surface microstructured grinding wheel and a fine grinding wheel. The abrasive grit size of the surface microstructured grinding wheel is smaller than that of the fine grinding wheel. The surface microstructured grinding wheel and the fine grinding wheel are two integral parts, and to improve workpiece processing efficiency, the length ratio of the surface microstructured grinding wheel to the fine grinding wheel is 3:2.

[0007] Furthermore, the surface microstructured grinding wheel has an abrasive particle size of 60-80, and the fine grinding wheel has an abrasive particle size of 80-120.

[0008] Furthermore, the surface microstructured grinding wheel employs ultrasonic vibration-assisted single-point diamond dressing to create numerous separated-continuous oblique curve microgrooves on the tooth flanks. The front portion of the composite worm grinding wheel of this invention reduces cutting force, heat generation, and contact zone temperature by decreasing the contact layer, thereby increasing the effective number of grinding edges during grinding. Simultaneously, the orderly arrangement of separated-continuous oblique curve microgrooves on the tooth flanks of the worm grinding wheel creates chip channels during grinding, effectively promoting chip removal and further preventing wheel clogging and workpiece surface burns. However, since this method increases the surface roughness of the workpiece, a fine grinding wheel is added in the rear portion to address this issue.

[0009] Furthermore, the material of the surface microstructured grinding wheel is alumina, and the binder is a ceramic binder.

[0010] Furthermore, the surface microstructured grinding wheel dressing uses an ultrasonic vibration-assisted single-point diamond pen. Using ultrasonic vibration-assisted dressing can promote the removal of grinding debris during the dressing process and effectively reduce the burning phenomenon during the dressing process. At the same time, ultrasonic vibration-assisted single-point diamond pen dressing causes the grinding wheel abrasive grains to break multiple times, generating more new grinding edges at the tip of the abrasive grains, which is beneficial to improving the material removal rate of the grinding process.

[0011] Furthermore, the ultrasonic vibration-assisted single-point diamond pen dressing method specifically includes the following steps:

[0012] Step 1: Install the worm wheel to be dressed on the rotatable spindle, and keep its axis parallel to the motion coordinate system of the dressing device; install the diamond pen on the dressing device that can realize radial feed, axial feed and ultrasonic vibration functions, with the diamond pen tip pointing towards the working surface of the worm wheel.

[0013] Step Two: Adjust the spatial orientation of the dressing device so that the diamond pen forms a helix angle β in the radial direction of the worm wheel that is consistent with the helical direction of the grinding wheel, and cause the diamond pen to superimpose a micro-amplitude ultrasonic frequency along this helix angle direction during the dressing process. The ultrasonic vibration frequency f... u The range is 20–22 kHz, the amplitude A is 5–10 μm, and the helix angle β is 20°–30°.

[0014] Step 3: Control the linear velocity V of the worm grinding wheel s The feed rate is 5-10 m / s, and the diamond pen is simultaneously controlled to make a reciprocating linear feed motion along the generatrix of the worm wheel, with a feed speed V. z The radial penetration rate is 0.1–0.3 mm / s, and its radial penetration α r The diameter is 15–25 µm, and the maximum radius of its pen tip is r. d The diameter is 0.02–0.10 mm. During the dressing feed path, the diamond pen superimposes ultrasonic vibrations along the radial leftward helical angle β, causing the diamond pen to generate periodic cutting action within the contact area, thus forming a sloping curve micro-groove with a certain inclination angle on the grinding wheel tooth surface. After the diamond pen completes the machining of one sloping curve micro-groove, to achieve separation between the micro-grooves, a periodic on / off control method for the ultrasonic vibration is adopted during the dressing process. The gating frequency f for the ultrasonic vibration on / off cycle is... g The frequency ranges from 0.2 to 0.8 Hz. After the diamond dressing tool completes the dressing of one tooth surface, the worm wheel feeds axially for one tooth width, causing the diamond dressing tool to repeat the vibration dressing process, thereby forming a depth d on the grinding wheel tooth surface. g The axial spacing P is 16–28 μm. g The diameter is 0.2–1.0 mm, the inclination angle α is 5°–8°, and the groove width w gIt consists of a continuously-separated arrangement of micro-sloping grooves ranging from 37 to 138 µm.

[0015] Step 4: Adjust the dressing device so that the diamond pen performs ultrasonic vibration along the radial right side at a helical angle −β. Repeat the dressing process in Step 3 to form a sloping curve micro-groove on the other side of the worm wheel tooth surface in the opposite direction to the aforementioned one, thereby forming sloping curve micro-grooves on both sides of the worm wheel tooth surface; control the grinding wheel rotation speed V s Adjusting the feed rate V z Ultrasonic vibration frequency f u And the amplitude A, to achieve the depth d of the micro-groove. g Axial spacing P g And precise control of the tilt angle α; after dressing, the surface of the worm wheel forms a series of micro-grooves arranged along the helical direction.

[0016] Furthermore, the linear velocity V of the grinding wheel s Adjusting the feed rate V z Ultrasonic vibration frequency f u Amplitude A, helix angle β, and the gating frequency f for ultrasonic vibration on / off g To achieve the depth d of the inclined curve micro-groove g Axial spacing P g、 Inclination angle α and groove width w g Control relationships:

[0017] ;

[0018] ;

[0019] ;

[0020] ;

[0021] In the formula, App=2A is the peak-to-peak value of ultrasonic vibration, and α r This refers to the radial penetration depth of the diamond pen.

[0022] The fine grinding wheel is the rear part of the composite worm wheel, and uses an abrasive grit size of 80-120 to perform fine grinding on the workpiece, so as to solve the problem of large surface roughness after processing by the surface micro-structured grinding wheel; its material is alumina and the bonding agent is ceramic bonding agent, taking into account both elasticity and strength; since it is an integral part of the surface micro-structured grinding wheel, its dimensional parameters are consistent with those of the surface micro-structured grinding wheel.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0024] This invention utilizes a micro-structured grinding wheel on its front surface to machine a sloping-curved micro-groove structure with a separation-continuity characteristic. Based on the gear meshing principle, the worm wheel and the gear being machined are in point contact along the tooth profile. The sloping-curved micro-grooves distributed radially along the grinding wheel ensure sufficient grinding surface in the circumferential direction when in contact with the gear. Simultaneously, the sloping-curved grooves radially penetrate the tooth tip and root, providing a continuous path for coolant and chips, thereby promoting chip removal and heat dissipation, and reducing the temperature and cutting force in the contact area. Furthermore, during grinding wheel dressing, the relative motion resulting from the rotation, feed, and ultrasonic vibration superposition between the diamond pen and the grinding wheel determines that the diamond pen's trajectory is a parametric curve. The sloping-curved grooves, through stable control of the dressing parameters, exhibit good repeatability and machining consistency. The sloping-curved micro-grooves are arranged in a continuous-separation manner, with effective abrasive particles participating in material removal in the tooth surface area between adjacent grooves, allowing the grinding wheel to maintain material removal efficiency while possessing good chip removal and heat dissipation performance.

[0025] The present invention preferably controls the inclination angle of the microgrooves within the range of 5° to 8°. When the inclination angle of the microgrooves is less than 5°, the groove direction tends to be close to the axial direction, and its unfolding length in the grinding direction is insufficient, resulting in insignificant chip removal and heat dissipation effects. When the inclination angle is greater than 8°, the groove deviates too much from the grinding contact trajectory, which easily introduces periodic cutting impacts, leading to a decrease in grinding stability and affecting tooth profile accuracy. The depth and axial spacing of the microgrooves are matched with the feed of the diamond grinding wheel and the generating motion of the grinding wheel. If the groove depth is too small, it will result in insufficient chip space, making it difficult to exert the chip removal and heat dissipation effects of the structured grinding wheel. If the groove depth is too large, it will significantly reduce the number of effective abrasive grains, leading to a decrease in grinding stability. The width of the microgroove is determined by the geometric parameters of the diamond tip and the depth of cut of the diamond tip. An appropriate groove width can increase the chip-carrying space and the cooling medium flow channel without significantly weakening the bearing capacity of the grinding wheel, thereby improving chip removal and heat dissipation conditions during the grinding process. On the other hand, an appropriate groove width can ensure that a sufficient number of evenly distributed effective grinding edges are retained on the grinding wheel tooth surface, avoiding the problem that the number of grinding edges is significantly reduced due to excessive groove width or that the effect of the microgroove is not obvious due to excessive groove width. This structure can significantly reduce the accumulation of grinding heat in the contact area, reduce workpiece surface burns or thermal cracks caused by overheating, and thus improve the quality of the grinding surface and the processing stability.

[0026] This invention employs an ultrasonic vibration-assisted single-point diamond pen dressing process during the dressing of microstructured surface grinding wheels, which significantly improves dressing efficiency and grinding wheel surface quality. By introducing ultrasonic vibration during the dressing process, the diamond pen and grinding wheel surface periodically come into contact and separate, reducing the instantaneous contact force and frictional heat accumulation in the dressing area. This effectively promotes the removal and discharge of grinding debris during the dressing process, thereby reducing the risk of grinding wheel clogging and burning. Simultaneously, under the action of ultrasonic vibration, intermittent impacts are generated between the diamond pen and the abrasive grains, causing multiple micro-crack propagation and fracture on the surface of the grinding wheel abrasive grains, forming a large number of new micro-cutting edge structures. This significantly increases the number of effective cutting edges on the grinding wheel surface, which is beneficial to improving the material removal rate in the grinding process.

[0027] This invention incorporates a fine grinding wheel structure at the rear of the grinding wheel. The rough grinding section primarily handles most of the material removal from the workpiece, requiring high chip removal and heat dissipation capabilities. The fine grinding section mainly corrects the increased surface roughness introduced by rough grinding. Comparative analysis of different length ratios reveals that a 3:2 axial length ratio between the rough grinding section and the fine grinding section ensures efficient material removal during rough grinding while providing sufficient correction space for the fine grinding stage. This achieves a balance between processing efficiency and tooth surface quality in a single setup. By integrating the fine grinding wheel onto the same grinding wheel body, efficient material removal, chip removal, heat dissipation, and high surface quality can be simultaneously achieved during generating grinding.

[0028] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0030] Figure 1 This is a schematic diagram of the composite worm gear grinding wheel of the present invention;

[0031] Figure 2 This is a schematic diagram of the ultrasonic vibration-assisted single-point diamond pen trimming of the present invention;

[0032] Figure 3 This is an enlarged schematic diagram of the oblique curve micro-groove of the present invention.

[0033] In the diagram: 1. Surface micro-structured grinding wheel, 11. Coarse grinding surface, 12. Inclined micro-groove, 13. Small abrasive grains, 2. Fine grinding wheel, 21. Fine grinding surface, 22. Large abrasive grains, 3. Dressing device, 31. Diamond pen, 32. Amplitude bar, 33. Piezoelectric ceramic actuator, 34. Worktable, 35. Data transmission line, 36. Ultrasonic generator.

[0034] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

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

[0038] Example 1

[0039] See appendix Figures 1 to 3 This embodiment describes a composite worm gear grinding wheel and its dressing method. The composite worm gear grinding wheel includes a surface micro-structured grinding wheel 1 and a fine grinding wheel 2. The abrasive of the surface micro-structured grinding wheel 1 is a small-grained abrasive 13, and the abrasive of the fine grinding wheel 2 is a large-grained abrasive 22. The surface micro-structured grinding wheel 1 is dressed using an ultrasonic vibration-assisted single-point diamond pen, and a large number of separated-continuous oblique curve micro-grooves 12 are dressed on the tooth side. The grooves 12 mainly serve to collect chips and dissipate heat. The dressing device 3 consists of a diamond pen 31, an amplitude transformer 32, a piezoelectric ceramic actuator 33, a worktable 34, a data cable 35, and an ultrasonic generator 36.

[0040] See Figure 1 In this embodiment, along the axial direction of the composite worm grinding wheel, the outer tooth surface of the surface micro-structured grinding wheel 1 forms a rough grinding working surface 11, and the outer tooth surface of the fine grinding wheel 2 forms a fine grinding working surface 21. When the composite worm grinding wheel grinds the workpiece, the rough grinding working surface 11 on the surface micro-structured grinding wheel 1 first performs rough grinding on the workpiece. After the rough grinding is completed, the fine grinding working surface 21 on the fine grinding wheel 2 performs fine grinding on the workpiece, realizing continuous and integrated processing of multi-stage grinding. This integral composite structure reduces the repeated clamping and positioning errors of the workpiece between different processes. While achieving efficient removal and good chip removal and heat dissipation performance, it further improves the processing accuracy and dimensional consistency of the workpiece, thereby effectively solving the problem that it is difficult to simultaneously achieve efficient removal, chip removal and heat dissipation and high surface quality in the generating grinding process.

[0041] The composite worm gear grinding wheel has a diameter of 350 mm, a length of 200 mm, a pressure angle of 20°, and a helix angle of 20°. The surface micro-structured grinding wheel 1 is made of alumina, with a ceramic bond, an abrasive grit size of 60, and one head. Its length is 120 mm. The surface micro-structured grinding wheel 1 is dressed using an ultrasonic vibration-assisted single-point diamond pen 31 method, which includes the following steps.

[0042] Step 1: Install the worm wheel to be dressed on the rotatable spindle and keep its axis parallel to the motion coordinate system of the dressing device 3; install the diamond pen 31 on the dressing device that can realize radial feed, axial feed and ultrasonic vibration functions, with the tip of the diamond pen 31 pointing towards the working surface of the worm wheel.

[0043] Step Two: Adjust the spatial orientation of the dressing device so that the diamond pen 31 forms a helix angle β of 20° in the radial direction of the worm wheel, consistent with the helical direction of the grinding wheel. During the dressing process, the diamond pen 31 undergoes micro-amplitude vibrations at an ultrasonic frequency superimposed along this helix angle direction. The frequency f of the ultrasonic vibration is... u The amplitude A is 21 kHz and the peak amplitude is 10 µm, respectively.

[0044] Step 3: Control the worm grinding wheel to move at a circumferential linear velocity V s The rotation speed is 4.25 m / s, while the diamond pen 31 is slowly fed along the generatrix of the worm gear at a speed V. z The speed is 0.2 mm / s, and its radial penetration α r It is 16µm, and its maximum tip radius r d The thickness is 0.05mm; during the trimming of the feed path, the diamond pen 31 is stacked along the radial left side at a helical angle. The ultrasonic vibration causes the diamond pen 31 to produce a periodic cutting action in the contact area, thereby forming a slanted curve micro-groove 12 with a certain inclination angle on the grinding wheel tooth surface. By periodically controlling the ultrasonic vibration to turn on and off, the selected frequency f g Set to 0.4Hz to adjust the axial spacing P between adjacent microgrooves. g The depth is 0.5mm; after the diamond pen 31 completes the dressing of one tooth surface, the worm wheel feeds axially for one tooth width, causing the diamond pen 31 to repeat the vibration dressing process, thereby forming a depth d on the grinding wheel tooth surface. g The groove width is 18μm, the inclination angle α is 6°, and the groove width is w. g The structure consists of 12 micro-sloping grooves arranged in a continuous-separated pattern with a diameter of 73 μm.

[0045] The inclination angle α and axial spacing P of the inclined curve micro-grooves g Groove depth d g and groove width w g The relationship between the ultrasonic vibration parameters and the trimming motion parameters is as follows:

[0046] ;

[0047] ;

[0048] ;

[0049] ;

[0050] Step 4: Adjust the dressing device 3 so that the diamond pen 31 forms a helical angle - to the right radially. The direction is subjected to ultrasonic vibration, and the dressing process of step three is repeated to form a sloping curve micro-groove 12 on the other side of the tooth surface of the worm grinding wheel in the opposite direction to the above, thereby forming a bidirectional sloping curve microstructure on the tooth surface of the worm grinding wheel; after dressing, the surface of the worm grinding wheel is formed with multiple sets of micro-sloping curve micro-grooves 12 arranged in the spiral direction.

[0051] The fine grinding wheel 2 is the rear part of the composite worm wheel. It has a diameter of 350mm, a length of 80mm, and an abrasive grit size of 120. Its material is alumina and the bonding agent is ceramic. It takes into account both elasticity and strength and can complete the fine grinding of the workpiece to solve the problem of large surface roughness after processing by the surface micro-structured grinding wheel 1.

[0052] At the linear velocity v of the grinding wheel s =20m / s, grinding depth a pUnder the condition of 60 μm, when grinding with the surface microstructured grinding wheel 1, the normal grinding force and tangential grinding force are reduced by 20% to 30% compared with continuous grinding wheels. This reduction in grinding force is mainly attributed to the inclined curve micro-groove structure in the abrasive layer of the surface microstructured grinding wheel 1: on the one hand, the micro-groove significantly increases the chip space on the grinding wheel surface, reducing chip accumulation in the grinding zone; on the other hand, due to the presence of the groove, the grinding contact layer is reduced, and the abrasive grain protrusion height at the groove edge is larger, improving the self-sharpening property of the grinding wheel during the grinding process. Therefore, under the same grinding parameters, the surface microstructured grinding wheel 1 needs to overcome less cutting resistance, thus exhibiting a lower overall grinding force.

[0053] At the linear velocity v of the grinding wheel s =20m / s, grinding depth a p Under the condition of 60 μm, the grinding temperature of the surface microstructured grinding wheel 1 is significantly lower than that of the continuous grinding wheel. When using the surface microstructured grinding wheel 1, the maximum temperature in its grinding zone is reduced by 30% to 40% compared to the continuous grinding wheel. The maximum temperature in the grinding zone of the continuous grinding wheel is 600 to 650℃, while the maximum temperature in the grinding zone of the surface microstructured grinding wheel 1 is reduced to 380 to 420℃. This temperature reduction effect is mainly due to the guiding effect of the micro-sloping grooves on the flow of grinding fluid and air, which improves the heat dissipation conditions in the grinding zone and effectively reduces the retention of chips in the grinding zone, thereby inhibiting heat accumulation and significantly reducing the risk of burns or thermal damage to the workpiece surface.

[0054] At the linear velocity v of the grinding wheel s =20m / s, grinding depth a p Under the condition of 60 μm, the surface roughness Ra value of the workpiece after continuous grinding wheel grinding is 0.55–0.65 μm, while the surface roughness Ra value of the workpiece after grinding with surface microstructured grinding wheel 1 is 0.75–0.90 μm. Because the number of abrasive grains participating in grinding on the surface of surface microstructured grinding wheel 1 is relatively small, the average cutting thickness of a single abrasive grain increases, and the stability of the material removal process is slightly lower than that of continuous grinding wheel, resulting in an increase in surface roughness after grinding. After processing with the second half of the fine grinding wheel 2, the surface roughness Ra value of the workpiece can be further reduced to 0.35–0.45 μm, significantly improving the surface quality of the workpiece and achieving a composite processing effect of efficient rough grinding removal and high-quality fine grinding shaping.

[0055] Example 2

[0056] See appendix Figures 1 to 3This embodiment describes a composite worm gear grinding wheel and its dressing method. The composite worm gear grinding wheel includes a surface micro-structured grinding wheel 1 and a fine grinding wheel 2. The abrasive of the surface micro-structured grinding wheel 1 is a small-grained abrasive 13, and the abrasive of the fine grinding wheel 2 is a large-grained abrasive 22. The surface micro-structured grinding wheel 1 is dressed using an ultrasonic vibration-assisted single-point diamond pen, and a large number of separated-continuous oblique curve micro-grooves 12 are dressed on the tooth side. The grooves 12 mainly serve to collect chips and dissipate heat. The dressing device 3 consists of a diamond pen 31, an amplitude transformer 32, a piezoelectric ceramic actuator 33, a worktable 34, a data cable 35, and an ultrasonic generator 36.

[0057] See Figure 1 In this embodiment, along the axial direction of the composite worm grinding wheel, the outer tooth surface of the surface micro-structured grinding wheel 1 forms a rough grinding working surface 11, and the outer tooth surface of the fine grinding wheel 2 forms a fine grinding working surface 21. When the composite worm grinding wheel grinds the workpiece, the rough grinding working surface 11 on the surface micro-structured grinding wheel 1 first performs rough grinding on the workpiece. After the rough grinding is completed, the fine grinding working surface 21 on the fine grinding wheel 2 performs fine grinding on the workpiece, realizing continuous and integrated processing of multi-stage grinding. This integral composite structure reduces the repeated clamping and positioning errors of the workpiece between different processes. While achieving efficient removal and good chip removal and heat dissipation performance, it further improves the processing accuracy and dimensional consistency of the workpiece, thereby effectively solving the problem that it is difficult to simultaneously achieve efficient removal, chip removal and heat dissipation and high surface quality in the generating grinding process.

[0058] The composite worm gear grinding wheel has a diameter of 350mm, a length of 200mm, a pressure angle of 20°, and a helix angle of 25°. The surface micro-structured grinding wheel 1 is made of alumina, with a ceramic bond, an abrasive grit size of 60, and has one head. Its length is 120mm. The surface micro-structured grinding wheel 1 is dressed using an ultrasonic vibration-assisted single-point diamond pen 31 dressing method, which includes the following steps.

[0059] Step 1: Install the worm wheel to be dressed on the rotatable spindle and keep its axis parallel to the motion coordinate system of the dressing device 3; install the diamond pen 31 on the dressing device that can realize radial feed, axial feed and ultrasonic vibration functions, with the tip of the diamond pen 31 pointing towards the working surface of the worm wheel.

[0060] Step Two: Adjust the spatial orientation of the dressing device so that the diamond pen 31 forms a helix angle β of 25° in the radial direction of the worm wheel, consistent with the helical direction of the grinding wheel. During the dressing process, the diamond pen 31 undergoes micro-amplitude vibrations at an ultrasonic frequency superimposed along this helix angle direction. The frequency f of the ultrasonic vibration is... u The amplitude A is 21 kHz and the peak amplitude is 10 µm, respectively.

[0061] Step 3: Control the worm grinding wheel to move at a circumferential linear velocity Vs The rotation speed is 4.5 m / s, while the diamond pen 31 is slowly fed along the generatrix of the worm gear at a speed V. z The radial penetration rate is 0.15 mm / s, and its radial penetration α r It is 18µm, and its maximum tip radius r d The diameter is 0.05 mm. During the dressing feed path, the diamond pen 31 superimposes ultrasonic vibrations along the radial left side at a helical angle of 25°, causing the diamond pen 31 to generate periodic cutting action in the contact area, thereby forming a slanted curve micro-groove 12 with a certain inclination angle on the grinding wheel tooth surface. By periodically controlling the opening and closing of the ultrasonic vibration, the selected frequency f is... g Set to 0.5Hz to adjust the axial spacing P between adjacent microgrooves. g The depth is 0.3mm; after the diamond pen 31 completes the dressing of one tooth surface, the worm wheel feeds axially for one tooth width, causing the diamond pen 31 to repeat the vibration dressing process, thereby forming a depth d on the grinding wheel tooth surface. g 20μm, tilt angle α is 7°, groove width w g The structure consists of 12 micro-sloping grooves arranged in a continuous-separated pattern with a diameter of 77 μm.

[0062] The inclination angle α and axial spacing P of the inclined curve micro-grooves g Groove depth d g and groove width w g The relationship between the ultrasonic vibration parameters and the trimming motion parameters is as follows:

[0063] ;

[0064] ;

[0065] ;

[0066] ;

[0067] Step 4: Adjust the dressing device 3 so that the diamond pen 31 forms a helical angle - to the right radially. The direction is subjected to ultrasonic vibration, and the dressing process of step three is repeated to form a sloping curve micro-groove 12 on the other side of the tooth surface of the worm grinding wheel in the opposite direction to the above, thereby forming a bidirectional sloping curve microstructure on the tooth surface of the worm grinding wheel; after dressing, the surface of the worm grinding wheel is formed with multiple sets of micro-sloping curve micro-grooves 12 arranged in the spiral direction.

[0068] The fine grinding wheel 2 is the rear part of the composite worm wheel. It has a diameter of 350mm, a length of 80mm, and an abrasive grit size of 120. Its material is alumina and the bonding agent is ceramic. It takes into account both elasticity and strength and can complete the fine grinding of the workpiece to solve the problem of large surface roughness after processing by the surface micro-structured grinding wheel 1.

[0069] At the linear velocity v of the grinding wheel s =20m / s, grinding depth a p Under the condition of 60 μm, when grinding with the surface microstructured grinding wheel 1, the normal grinding force and tangential grinding force are reduced by 25% to 35% compared with the continuous grinding wheel. This reduction in grinding force is mainly attributed to the denser and more inclined inclined curve microgroove structure in the abrasive layer of the surface microstructured grinding wheel 1: on the one hand, the smaller axial spacing significantly increases the chip space on the grinding wheel surface, reducing chip accumulation in the grinding zone; on the other hand, the increased groove inclination angle enhances the flow guidance effect of the grinding fluid and improves the lubrication conditions. Under the above working conditions, the surface microstructured grinding wheel 1 needs to overcome less cutting resistance, exhibiting lower overall grinding force and a smoother cutting process.

[0070] At the linear velocity v of the grinding wheel s =20m / s, grinding depth a p Under the condition of 60μm, the grinding temperature of the surface microstructured grinding wheel 1 is significantly lower than that of the continuous grinding wheel. When using the surface microstructured grinding wheel 1, the maximum temperature in the grinding zone is reduced by 35% to 45% compared to the continuous grinding wheel. The maximum temperature in the grinding zone of the continuous grinding wheel is 600 to 650℃, while the maximum temperature in the grinding zone of the surface microstructured grinding wheel 1 is reduced to 350 to 400℃. This temperature reduction effect is mainly due to the enhanced guiding and heat dissipation effect of the optimized micro-curved grooves on the flow of grinding fluid and air. The denser groove structure improves the fluid permeability and convective heat transfer efficiency in the grinding zone, while further reducing the residence time of chips and frictional heat generation in the grinding zone, significantly inhibiting heat accumulation, and greatly reducing the risk of burns or thermal damage to the workpiece surface.

[0071] At the linear velocity v of the grinding wheel s =20m / s, grinding depth a pUnder the condition of 60μm, the surface roughness Ra value of the workpiece after continuous grinding is 0.55~0.65μm, while the surface roughness Ra value of the workpiece after grinding with surface micro-structured grinding wheel 1 is 0.80~0.95μm. Because the number of abrasive grains participating in grinding on the surface of surface micro-structured grinding wheel 2 is further relatively reduced, the average cutting thickness of a single abrasive grain is slightly increased, resulting in a slight increase in surface roughness after grinding. After the second half of the finishing grinding with grinding wheel 2, the surface roughness Ra value of the workpiece can be further reduced to 0.37~0.47μm, significantly improving the surface quality of the workpiece and achieving a composite processing effect of efficient rough grinding removal and high-quality finishing.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A composite worm gear grinding wheel, characterized in that, The composite worm gear grinding wheel consists of a surface micro-structured grinding wheel (1) and a fine grinding wheel (2) connected axially. The abrasive grain size of the surface micro-structured grinding wheel (1) is smaller than that of the fine grinding wheel (2). The tooth side surface of the surface micro-structured grinding wheel (1) is decorated with a large number of separated and continuous oblique curve micro grooves (12) that have chip-receiving and heat dissipation functions. The outer tooth surface of the surface micro-structured grinding wheel (1) forms a rough grinding working surface (11), and the outer tooth surface of the fine grinding wheel (2) forms a fine grinding working surface (21).

2. The composite worm gear grinding wheel according to claim 1, characterized in that: The length ratio of the surface microstructured grinding wheel (1) to the fine grinding wheel (2) is 3:

2.

3. The composite worm gear grinding wheel according to claim 1, characterized in that: The surface microstructured grinding wheel (1) has an abrasive grit size of 60-80, and the fine grinding wheel (2) has an abrasive grit size of 80-120.

4. The composite worm gear grinding wheel according to claim 1, characterized in that: The surface microstructured grinding wheel (1) and the fine grinding wheel (2) are bonded together by a binder, which is a ceramic binder. The surface microstructured grinding wheel (1) and the fine grinding wheel (2) are made of alumina.

5. A method for dressing a composite worm grinding wheel as described in any one of claims 1-4, characterized in that, The surface microstructured grinding wheel (1) is dressed using an ultrasonic vibration-assisted single-point diamond pen (31). The specific dressing steps are as follows: Step 1: Install the worm wheel to be dressed on the rotatable spindle and keep its axis parallel to the motion coordinate system of the dressing device; install the diamond pen (31) on the dressing device that can realize radial feed, axial feed and ultrasonic vibration functions, with the tip of the diamond pen (31) pointing to the working surface of the worm wheel. Step 2: Adjust the spatial orientation of the dressing device (3) so that the diamond pen (31) forms a helical angle β in the radial direction of the worm wheel that is consistent with the helical direction of the grinding wheel, and make the diamond pen (31) superimpose ultrasonic vibration in the direction of this helical angle during the dressing process; Step 3: Control the rotation of the worm wheel and simultaneously control the diamond pen (31) to make a linear feed motion along the generatrix of the worm wheel; in the dressing feed path, the diamond pen (31) superimposes ultrasonic vibration along the radial left helical angle direction to form a slanted curve micro-groove (12) with an inclination angle α on the grinding wheel tooth surface; during the dressing process, the adjacent micro-grooves (12) are separated by periodically opening and closing the ultrasonic vibration; Step 4: Adjust the dressing device (3) so that the diamond pen (31) performs ultrasonic vibration in the direction of the radial right helical angle. Repeat step 3 to form a slanted curve micro-groove (12) with opposite direction on the tooth surface of the worm wheel. Slanted curve micro-grooves are formed on both sides of the tooth surface of the worm wheel. After dressing, a worm wheel surface is formed with multiple sets of micro-slanted curve micro-grooves (12) arranged in the helical direction.

6. The trimming method according to claim 5, characterized in that, The frequency f of the ultrasonic vibration u The frequency range is 20–22 kHz, the amplitude A is 5–10 μm, and the helix angle β is 20°–30°.

7. The trimming method according to claim 5, characterized in that, In step three, the linear velocity V of the worm grinding wheel is controlled. s The feed speed V of the diamond pen (31) is controlled to be 5-10 m / s. z The radial penetration rate is 0.1–0.3 mm / s, and its radial penetration α r The diameter is 15–25 µm, and the maximum radius of its pen tip is r. d It is 0.02 to 0.10 mm.

8. The trimming method according to claim 5, characterized in that, In step three, the gating frequency f of the periodically switching the ultrasonic vibration on and off is... g The frequency range is 0.2 to 0.8 Hz.

9. The trimming method according to claim 5, characterized in that, In step three, after dressing one tooth surface, the worm wheel is fed axially for one tooth width, and the dressing process is repeated until a depth d is formed on the grinding wheel tooth surface. g The axial spacing P is 16–28 μm. g The diameter is 0.2–1.0 mm, the inclination angle α is 5°–8°, and the groove width w g The structure consists of continuously-separated oblique curve microgrooves (12) with a diameter of 37–138 µm.

10. The trimming method according to claim 5, characterized in that, In step three, the linear speed V of the grinding wheel is controlled. s Adjusting the feed rate V z Ultrasonic vibration frequency f u Amplitude A, helix angle β, and the gating frequency f for ultrasonic vibration on / off g To achieve the depth d of the inclined curve micro-groove g Axial spacing P g Inclination angle α and groove width w g The adjustment and control relationship are shown in the following formula: ； ； ； ； In the formula, A pp =2A represents the peak-to-peak value of ultrasonic vibration, α r The radial penetration of the diamond pen (31) is given.

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