Design method of a dressing-free CBN profile grinding wheel for grinding external helical gears

Abstract

The invention discloses a design method of a dressing-free CBN forming grinding wheel for grinding a modified external helical gear, the method comprising: designing a tooth shape and structure of a dressing-free CBN forming grinding wheel by modifying the tooth surface parameters of an involute external helical gear; selecting the particle size of a CBN abrasive according to the roughness requirement of the tooth surface of the modified involute external helical gear; reducing the tooth profile of the grinding wheel in proportion to the size of the selected CBN particles according to the tooth shape and structure of the dressing-free CBN forming grinding wheel, and designing the base profile of the dressing-free CBN forming grinding wheel; processing the base according to the designed base profile of the dressing-free CBN forming grinding wheel and uniformly attaching the selected CBN abrasive to the base by a single-layer suspension electroplating process; using a diamond grinding wheel to finely grind and dress the electroplated CBN grinding wheel blank, and completing the manufacture of the dressing-free CBN forming grinding wheel for the modified involute external helical gear. The invention can realize the high-efficiency, high-life, and low-cost forming grinding of involute external helical gears.

Description

Technical Field

[0001] The invention belongs to the technical field of design and preparation of profiled grinding wheels, and relates to a design method of a dressing-free CBN profiled grinding wheel for grinding profiled external helical gears. Background Art

[0002] Profile grinding is a precision gear grinding technology, which is widely used in gear transmission systems such as automobiles, engineering machinery, aerospace, wind power, high-speed rail, and energy equipment. It is mostly used for grinding shaft parts with structural interference, and is irreplaceable in the production process of transmission gear grinding for internal gears, large modulus (Mn>10) wind power, heavy machinery, etc. Ordinary profile grinding uses corundum grinding wheels. Due to the structure and characteristics of corundum grinding wheels, the grinding wheels must be installed through rods. The influence of many factors such as the linear speed, service life, dressing frequency, and outer diameter of the grinding wheels leads to low efficiency of profile grinding. CBN abrasives, as the currently known superhard material with hardness second only to diamond, are ideal gear grinding materials. Compared with ordinary corundum abrasives, they have obvious advantages and are suitable for efficient profile grinding of gears. They are the development direction of profile grinding technology.

[0003] CBN grinding wheels can be divided into dressable grinding wheels (sintering process) and non-dressable grinding wheels (single-layer electroplating process) according to the way they are used. When grinding external helical gears with dressable CBN profile grinding wheels, the machine tool needs to use a special grinding program and diamond rollers to dress the grinding profile. Due to the high hardness of CBN abrasives, the diamond rollers wear more severely, making it impossible to achieve stable and low-cost applications. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a design method for a dressing-free CBN profile grinding wheel for grinding modified external helical gears, and to achieve high-efficiency, long-life, and low-cost profile grinding of involute external helical gears through the principles of external helical gear grinding, high-order tooth profile modification principles, and single-layer suspension electroplating technology.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A design method for a dressing-free CBN profile grinding wheel for grinding a profiled external helical gear comprises the following steps:

[0007] Step 1, designing the tooth shape and structure of the non-dressing CBN forming grinding wheel by modifying the tooth surface parameters of the involute external helical gear;

[0008] Step 2, selecting the particle size of the CBN abrasive according to the roughness requirement of the modified involute external helical tooth surface;

[0009] Step 3, according to step 1, the tooth shape and structure of the dressing-free CBN formed grinding wheel are obtained, and the tooth profile of the grinding wheel is proportionally reduced according to the size of the selected CBN particles, so as to design the base profile of the dressing-free CBN formed grinding wheel;

[0010] Step 4, according to the base profile of the non-dressing CBN forming grinding wheel designed in step 3, use a high-precision profiling lathe or curved surface grinder to process the base, and use a single-layer suspension electroplating process to evenly attach the CBN abrasive selected in step 2 to the base;

[0011] Step 5, using a diamond grinding wheel to finely grind and dress the electroplated CBN grinding wheel blank in step 4, thereby completing the manufacture of the dressing-free CBN forming grinding wheel for the modified involute external helical gear.

[0012] The present invention also includes the following technical features:

[0013] Specifically, the modified involute external helical gear tooth surface parameters include: modified involute external helical gear tooth parameters and modified involute external helical gear high-order tooth profile modification design parameters;

[0014] The modified involute external helical gear tooth parameters include: normal module , Number of teeth , normal pressure angle , Helix Angle , Tip circle diameter , tooth root diameter , Normal circular tooth thickness , effective starting circle curvature radius , effective end circle curvature radius , axis angle , meshing center distance ;

[0015] The high-order tooth profile modification design parameters of the modified involute external helical gear include: the modification segment point coordinates of the workpiece gear , , , the drum shape of the arc segment , Pressure angle correction , parabola segment tooth tip modification amount .

[0016] Specifically, in step 1, the coordinate parameters of the modification curve are calculated according to the high-order tooth profile modification design parameters:

[0017] Combine the following formulas (1), (2), and (3) to calculate the center coordinate point of the arc modification segment in the high-order tooth modification parameters of the involute external helical gear: , arc radius , we get the coordinate equation of the arc of the arc modification segment, that is, the modification control points of the arc modification segment satisfy the arc curve:

[0018] (1)

[0019] (2)

[0020] (3)

[0021] The slope of the shaping curve at the junction of the arc shaping segment and the parabola shaping segment is calculated according to the following formula (4): :

[0022] (4)

[0023] Combine formula (4) and the following formulas (5) and (6) to calculate the coefficients of the parabola equation: , , , that is, the shaping control points of the parabola shaping segment satisfy the parabola curve:

[0024] (5)

[0025] (6)

[0026] According to the fitting accuracy of the shaping curve, the shaping segment is discretized into The modified gear end face tooth profile is divided into segments and the control points after discretization are calculated. The horizontal coordinate of the discrete modification control point is the modification amount at the corresponding diameter of the processed gear. The modification amount of the tooth thickness is converted into the end face tooth profile of the workpiece gear to obtain the discrete points of the modified gear end face tooth profile. The spline curve is used to fit the end face tooth profile curve with high-order tooth profile modification.

[0027] Specifically, in step 1, according to the established meshing coordinate system of the modified involute external helical tooth surface and the dressing-free CBN profile grinding wheel, the meshing coordinate system includes the coordinate system corresponding to the modified involute external helical tooth surface The coordinate system corresponding to the dressing-free CBN profile grinding wheel , determine the parametric equation of the modified involute external helical tooth surface in the coordinate system;

[0028] Modified involute external helical tooth surface in the coordinate system The equation in is:

[0029] (7)

[0030] By converting the coordinates to Coordinate system, multiply the transformation matrix around the X axis on the left:

[0031] (8)

[0032] (9)

[0033] in, It is the center distance between the dressing-free CBN profile grinding wheel and the tooth surface of the modified involute external helical gear; It is the point after the modified involute external helical tooth surface is modified The radius at yes The polar angle at The modified involute external helical tooth surface is around the coordinate axis Angle of rotation, facing The positive direction of the axis is counterclockwise, which is positive, and the reverse direction is negative; is the helicoid parameter; for Pressure angle of the end plane; contact point exist The coordinate points of the coordinate system are ,exist The coordinate points of the coordinate system are ; Parameters Indicates the number of points on the curve. The larger the value, the higher the accuracy of the fitted curve.

[0034] Specifically, the grinding principle of the dressing-free CBN profile grinding wheel must satisfy the requirement that the slopes of the arc and the EF curve at the contact point are equal. The curve EF is the section line of the gear entity at the QQ section, and the QQ section is the section through the point Along the perpendicular axis The cross-section of the dressing-free CBN profile grinding wheel cut by the plane;

[0035] The contact line condition equation is:

[0036] (11)

[0037] (12)

[0038] in, It is the axial intersection angle between the modified involute external helical tooth surface and the dressing-free CBN profile grinding wheel; The helix angle of the base circle of the modified involute external helical tooth surface; The contact line condition equation is about The transcendental equation of the modified involute external helical tooth surface is , , , , , , As known parameters, given a Can calculate the point Values, and use iteration and binary search algorithms to quickly calculate a series of parameter values.

[0039] Specifically, according to the contact line condition equation, , calculated by the following formula (13) value, Substituting the value into formula (9) we can calculate Contact point in coordinate system ;

[0040] (13).

[0041] Specifically, the following formulas (14) and (15) are used to calculate , :

[0042] (14)

[0043] (15)

[0044] in, , The coordinate points of the shape line are calculated by using a spline curve to fit the shape line of the grinding wheel.

[0045] Specifically, in step 2, the CBN particle size is comprehensively selected based on the surface roughness of the modified involute external helical tooth surface, the electroplating process, the CBN grinding wheel dressing amount, and the application experience of CBN grinding wheel grinding the modified involute external helical tooth surface.

[0046] Specifically, the tooth surface roughness requirements are ≤Ra0.1, Ra0.2, Ra0.4, Ra0.6, Ra1.0, and Ra1.6, respectively, and CBN particles with grit sizes of 325 / 400, 270 / 325, 230 / 270, 200 / 230, 170 / 200, and 140 / 170 are selected for manufacturing the dressing-free CBN forming grinding wheel.

[0047] Compared with the prior art, the present invention has the following technical effects:

[0048] The present invention adopts a single-layer suspended forward electroplating process to manufacture a dressing-free CBN forming grinding wheel. During the grinding process of the forming grinding wheel using a more commonly used ordinary corundum abrasive (or microcrystalline corundum abrasive), there is no grinding wheel dressing process, which greatly reduces the single-piece processing time of the forming grinding gear, improves production efficiency, and reduces the investment cost of equipment and dressing tools.

[0049] The dressing-free CBN forming grinding wheel of the present invention has higher wear resistance than common corundum abrasive (or microcrystalline corundum abrasive), the service life of a single grinding wheel is increased by dozens of times, and the tooth profile of the processed gear is well maintained.

[0050] The dressing-free CBN profiled grinding wheel of the present invention generates no sparks during the grinding process, has a low risk of local thermal damage, can increase the residual compressive stress value of the tooth surface after grinding compared with ordinary corundum abrasive wheels, and improves the fatigue resistance life and service characteristics of the gear.

[0051] Compared with common corundum abrasive grinding wheels, the dressing-free CBN profiled grinding wheel of the present invention can be designed as an integral rod type, does not require a shank and a mounting hole, and the outer diameter of the grinding wheel can be manufactured to be smaller, so it can be applied to gears with narrower back-cut structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 In order to avoid dressing, CBN profile grinding wheel is used to grind and modify involute external helical gears.

[0053] Figure 2 To avoid dressing of CBN profile grinding wheel structure diagram.

[0054] Figure 3 It is a high-order tooth profile modification curve.

[0055] Figure 4 It is the meshing coordinate system of the involute external helical gear and the profile grinding wheel.

[0056] Figure 5 To avoid trimming the CBN profile grinding wheel tooth profile coordinate system.

[0057] The meaning of each number in the figure is:

[0058] 1. Modification of tooth surface of involute external helical gear, 2. Trimming-free CBN profiled grinding wheel, 3. CBN abrasive; 4. Trimming-free CBN profiled grinding wheel substrate, 5. Nickel electroplating layer, 6. Trimming-free CBN profiled grinding wheel rotating surface profile. DETAILED DESCRIPTION

[0059] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0060] Embodiment 1:

[0061] like Figures 1 to 5 As shown, this embodiment provides a design method for a dressing-free CBN profile grinding wheel for grinding a profiled external helical gear, comprising the following steps:

[0062] Step 1, designing the tooth shape and structure of the non-dressing CBN forming grinding wheel by modifying the tooth surface parameters of the involute external helical gear;

[0063] Known modified involute external helical gear tooth parameters: normal module , Number of teeth , normal pressure angle , Helix Angle , Tip circle diameter , tooth root diameter , Normal circular tooth thickness (or calculated from span, common normal, displacement coefficient, etc.), effective starting circle curvature radius , effective end circle curvature radius , Installation parameters (axis angle , meshing center distance );

[0064] The high-order tooth profile modification design parameters of the modified involute external helical gear are known: the modification segment point coordinates of the workpiece gear , , , the drum shape of the arc segment , Pressure angle correction , parabola segment tooth tip modification amount , Figure 3 As shown;

[0065] 1) Calculate the coordinate parameters of the modification curve according to the high-order tooth profile modification design parameters;

[0066] Combine formulas (1), (2), and (3) to calculate the center coordinate point of the arc modification segment in the high-order tooth modification parameters of the involute external helical gear. , arc radius , we can get the coordinate equation of the arc of the arc modification segment, that is, the modification control points of the arc modification segment satisfy the arc curve.

[0067] (1)

[0068] (2)

[0069] (3)

[0070] (4)

[0071] According to formula (4), the slope of the shaping curve at the junction of the arc shaping segment and the parabola shaping segment is calculated: .

[0072] (5)

[0073] (6)

[0074] Combining equations (4), (5), and (6) to calculate the coefficients of the parabola equation , , , that is, the shaping control points of the parabola shaping segment satisfy the parabola curve.

[0075] According to the fitting accuracy of the shaping curve, the shaping segment is discretized into The horizontal coordinate of the discrete modification control point is the modification amount at the corresponding diameter of the processed gear. The modification amount of the tooth thickness is converted into the end face tooth profile of the workpiece gear to obtain the modified gear end face tooth profile discrete points. The spline curve is used to fit the end face tooth profile curve with high-order tooth profile modification.

[0076] 2) According to Figure 4 The established meshing coordinate system of the modified involute external helical tooth surface and the dressing-free CBN profile grinding wheel determines the parametric equation of the modified involute external helical tooth surface in the coordinate system; the meshing coordinate system includes the coordinate system corresponding to the modified involute external helical tooth surface The coordinate system corresponding to the dressing-free CBN profile grinding wheel ;

[0077] Modified involute external helical tooth surface in the coordinate system The equation in is:

[0078] (7)

[0079] By converting the coordinates to Coordinate system, multiply the transformation matrix around the X axis on the left:

[0080] (8)

[0081] (9)

[0082] in It is the center distance between the dressing-free CBN profile grinding wheel and the tooth surface of the modified involute external helical gear; It is the point after the modified involute external helical tooth surface is modified The radius at yes The polar angle at The modified involute external helical tooth surface is around the coordinate axis Angle of rotation, facing The positive direction of the axis is counterclockwise, which is positive, and the reverse direction is negative; is the helicoid parameter; for Pressure angle of the end plane; contact point exist The coordinate points of the coordinate system are ,exist The coordinate points of the coordinate system are ; Parameters Indicates the number of points on the curve. The larger the value, the higher the accuracy of the fitted curve.

[0083] QQ section is through point Along the perpendicular axis The cross-section of the dressing-free CBN profile grinding wheel cut through the plane, is the radius of the circle at the end section contact point on the profile grinding section, satisfying:

[0084] (10)

[0085] Curve EF is the section line of the gear entity at the QQ section. The grinding principle of the dressing-free CBN profile grinding wheel must satisfy that the slope of the arc and the EF curve at the contact point is equal, which is a basic condition.

[0086] The contact line condition equation is:

[0087] (11)

[0088] (12)

[0089] (13)

[0090] in It is the axial intersection angle between the modified involute external helical tooth surface and the dressing-free CBN profile grinding wheel; Modified involute external helical tooth surface base circle helix angle;

[0091] Formula (11) The contact condition equation is about The transcendental equation of the modified involute external helical tooth surface is , , , , , , is a known parameter, that is, given a You can calculate the point This involves solving transcendental equations. Software can be written to quickly calculate the series of parameter values ​​using algorithms such as iteration and dichotomy. Calculate using formula (13) value, Substituting the value into formula (9) we can calculate Contact point in coordinate system .

[0092] (14)

[0093] (15)

[0094] , The coordinate points of the shape line are calculated by using a spline curve to fit the shape line of the grinding wheel. The shape line is drawn using CAD software, and the structural diagram of the non-dressing CBN forming grinding wheel is drawn according to the specifications, installation dimensions, structural restrictions and other constraints of the forming gear grinding machine, and the structural design of the non-dressing CBN forming grinding wheel is completed;

[0095] Step 2, selecting the particle size of the CBN abrasive according to the roughness requirement of the tooth surface of the modified involute external helical tooth;

[0096] The CBN particle size is selected based on the surface roughness of the modified involute external helical tooth surface, the electroplating process, the CBN grinding wheel dressing amount, and the application experience of CBN grinding wheel grinding the modified involute external helical tooth surface. The larger the CBN particles, the longer the service life, but the roughness of the tooth surface after grinding is lower. For example, if the tooth surface roughness requirement is Ra0.4, it is recommended to use CBN particles with a particle size of 230 / 270 for the manufacture of non-dressing CBN forming grinding wheels. Table 1 is the corresponding relationship between tooth surface roughness and CBN particle size;

[0097] Table 1 Correspondence between the roughness of the modified involute external helical gear and the CBN particle size

[0098]

[0099] Step 3, designing a dressing-free forming grinding CBN grinding wheel substrate;

[0100] The dressing-free CBN profiled grinding wheel is manufactured by a single-layer suspension electroplating process, and the size of the CBN particles is relatively small. In order to maintain the sharpness of the grinding wheel and increase its service life, the dressing amount of the CBN particles must be reduced. Therefore, the design and manufacturing precision of the CBN grinding wheel matrix are very high. According to step 1, the tooth profile of the dressing-free CBN grinding wheel is obtained. According to the size of the selected CBN particles, the tooth profile of the grinding wheel is proportionally reduced to design the matrix profile of the dressing-free CBN profiled grinding wheel, such as Figure 2 shown.

[0101] Step 4, manufacturing a substrate and attaching CBN abrasives to the substrate using an electroplating process;

[0102] According to the matrix line designed in step 3, use a high-precision profiling lathe or curved surface grinder to process the matrix to ensure that the dimensional accuracy meets the design requirements. The dressing-free CBN forming grinding wheel uses a single-layer suspension electroplating process to evenly fix the CBN abrasive selected in step 2 on the matrix designed in step 3, completing the fixation of the CBN particles on the matrix;

[0103] Step 5, using a diamond grinding wheel to dress the tooth profile of the rotating surface of the CBN grinding wheel;

[0104] Use a diamond grinding wheel to fine-grind the electroplated CBN grinding wheel blank in step 4, remove high points, and level the working surface of the grinding wheel to ensure that the final grinding wheel profile conforms to the profile of the effective working part of the grinding wheel designed in step 1 and meets the design tolerance requirements, completing the manufacture of the dressing-free CBN forming grinding wheel for the modified involute external helical gear.

[0105] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0106] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0107] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A design method for a dressing-free CBN profile grinding wheel for grinding external helical gears, characterized in that: The following steps are involved: Step 1, designing the tooth shape and structure of the non-dressing CBN forming grinding wheel by modifying the tooth surface parameters of the involute external helical gear; Step 2, selecting the particle size of the CBN abrasive according to the roughness requirement of the modified involute external helical tooth surface; Step 3, according to step 1, the tooth shape and structure of the dressing-free CBN formed grinding wheel are obtained, and the tooth profile of the grinding wheel is proportionally reduced according to the size of the selected CBN particles, so as to design the base profile of the dressing-free CBN formed grinding wheel; Step 4, according to the base profile of the non-dressing CBN forming grinding wheel designed in step 3, use a high-precision profiling lathe or curved surface grinder to process the base, and use a single-layer suspension electroplating process to evenly attach the CBN abrasive selected in step 2 to the base; Step 5, using a diamond grinding wheel to finely grind and dress the electroplated CBN grinding wheel blank in step 4, thereby completing the manufacture of the dressing-free CBN forming grinding wheel for the modified involute external helical gear; The modified involute external helical gear tooth surface parameters include: modified involute external helical gear tooth parameters and modified involute external helical gear high-order tooth profile modification design parameters; The modified involute external helical gear tooth parameters include: normal module , Number of teeth , normal pressure angle , Helix Angle , Tip circle diameter , tooth root diameter , Normal circular tooth thickness , effective starting circle curvature radius , effective end circle curvature radius , Axis Angle , meshing center distance ; The high-order tooth profile modification design parameters of the modified involute external helical gear include: the modification segment point coordinates of the workpiece gear , , , the drum shape of the arc segment , Pressure angle correction , parabola segment tooth tip modification amount ; In step 1, the coordinate parameters of the modification curve are calculated according to the high-order tooth profile modification design parameters: Combine the following formulas (1), (2), and (3) to calculate the center coordinate point of the arc modification segment in the high-order tooth modification parameters of the involute external helical gear: , arc radius , we get the coordinate equation of the arc of the arc modification segment, that is, the modification control points of the arc modification segment satisfy the arc curve: （1） （2） （3） The slope of the shaping curve at the junction of the arc shaping segment and the parabola shaping segment is calculated according to the following formula (4): : （4） Combine formula (4) and the following formulas (5) and (6) to calculate the coefficients of the parabola equation: , , , that is, the shaping control points of the parabola shaping segment satisfy the parabola curve: （5） （6） According to the fitting accuracy of the shaping curve, the shaping segment is discretized into The horizontal coordinate of the discrete modification control point is the modification amount at the corresponding diameter of the processed gear. The modification amount of the tooth thickness is converted into the end face tooth profile of the workpiece gear to obtain the modified gear end face tooth profile discrete points. The spline curve is used to fit the end face tooth profile curve with high-order tooth profile modification. In the step 1, according to the established meshing coordinate system of the modified involute external helical tooth surface and the dressing-free CBN profile grinding wheel, the meshing coordinate system includes the coordinate system corresponding to the modified involute external helical tooth surface The coordinate system corresponding to the dressing-free CBN profile grinding wheel , determine the parametric equation of the modified involute external helical tooth surface in the coordinate system; Modified involute external helical tooth surface in the coordinate system The equation in is: （7） By converting the coordinates to Coordinate system, multiply the transformation matrix around the X axis on the left: （8） （9） in, It is the center distance between the dressing-free CBN profile grinding wheel and the tooth surface of the modified involute external helical gear; It is the point after the modified involute external helical tooth surface is modified The radius at yes The polar angle at The modified involute external helical tooth surface is around the coordinate axis Angle of rotation, facing The positive direction of the axis is counterclockwise, which is positive, and the reverse direction is negative; is the helicoid parameter; for Pressure angle of the end plane; contact point exist The coordinate points of the coordinate system are ,exist The coordinate points of the coordinate system are ; Parameters Indicates the number of points on the curve. The larger the value, the higher the accuracy of the fitted curve. The grinding principle of the non-dressing CBN profile grinding wheel must satisfy the requirement that the slope of the arc and the EF curve at the contact point are equal. Curve EF is the section line of the gear entity at the QQ section, and the QQ section is the section through the point Along the perpendicular axis The cross-section of the dressing-free CBN profile grinding wheel cut by the plane; The contact line condition equation is: （11） （12） in, It is the axial intersection angle between the modified involute external helical tooth surface and the dressing-free CBN profile grinding wheel; The helix angle of the base circle of the modified involute external helical tooth surface; The contact line condition equation is about The transcendental equation of the modified involute external helical tooth surface is , , , , , , As known parameters, given a Can calculate the point Values, and use iteration and binary search algorithms to quickly calculate a series of parameter values.

2. The design method of the dressing-free CBN profile grinding wheel for grinding profiled external helical gears according to claim 1, characterized in that: According to the contact line condition equation, , calculated by the following formula (13) value, Substituting the value into formula (9) we can calculate Contact point in coordinate system ; （13）。 3. The design method of the dressing-free CBN profile grinding wheel for grinding profiled external helical gears according to claim 2, characterized in that: Calculate using the following formulas (14) and (15): , : （14） （15） in, , The coordinate points of the shape line are calculated by using a spline curve to fit the shape line of the grinding wheel.

4. The design method of the dressing-free CBN profile grinding wheel for grinding profiled external helical gears according to claim 1, characterized in that: In the step 2, the CBN particle size is comprehensively selected based on the surface roughness of the modified involute external helical tooth surface, the electroplating process, the CBN grinding wheel dressing amount, and the application experience of the CBN grinding wheel grinding the modified involute external helical tooth surface.

5. The design method of the dressing-free CBN profile grinding wheel for grinding profiled external helical gears according to claim 4, characterized in that: The tooth surface roughness requirements are ≤Ra0.1, Ra0.2, Ra0.4, Ra0.6, Ra1.0, and Ra1.6, respectively corresponding to the selection of CBN particles with particle sizes of 325 / 400, 270 / 325, 230 / 270, 200 / 230, 170 / 200, and 140 / 170 for manufacturing the dressing-free CBN forming grinding wheel.

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