A method for grinding the convexity of tapered rollers based on the envelope principle

Abstract

This invention discloses a method for grinding the crown of conical rollers based on the envelope principle. On a centerless conical roller grinder, the axial profile of the grinding wheel is dressed into a convex arc curve. Based on the requirement of conjugate motion between this convex arc curve and the roller crown curve, a through-motion trajectory of the roller center is designed while maintaining the roller's posture. This causes the arc surface of the grinding wheel to perform conjugate motion relative to the roller crown surface, thereby forming the roller crown shape curve through the envelope method. Simultaneously, based on the geometric relationship and conjugate motion relationship between the roller and the guide wheel, a guide wheel radius variation curve is designed as the basis for machining the axial profile of the grinding wheel, ensuring the realization of the designed through-motion trajectory of the roller center. This method improves the grinding accuracy of the roller crown and reduces the difficulty and cost of guide wheel regrinding. This method can not only grind the arc-shaped crown of conical rollers but is also applicable to other shapes of crown, such as logarithmic crowns.

Description

Technical Field

[0001] This invention relates to the field of machining and manufacturing, specifically to a method for grinding the convexity of tapered rollers based on envelope distance. Background Technology

[0002] Tapered roller bearings are a widely used type of rolling bearing, and the manufacturing quality of the tapered rollers has a significant impact on the bearing's performance. The convexity of the tapered roller's rolling surface effectively avoids stress concentration between the roller and the raceway, improves elastohydrodynamic lubrication, and thus increases bearing life and performance. The main machining processes for tapered roller convexity are grinding and ultra-precision grinding. Grinding has a stronger material removal capacity than ultra-precision grinding; it is suitable for rollers with large convexities, while ultra-precision grinding is suitable for rollers with medium to small convexities. If high surface quality is required for rollers with large convexities, ultra-precision grinding can be performed after convexity grinding. There are two grinding methods for tapered roller convexity: centerless through-feed and plunge grinding. Centerless through-feed grinding is far more efficient than plunge grinding, but it is more difficult to control the convexity shape, and the actual convexity shape produced often fails to meet the requirements of high-end bearing rollers. While plunge grinding offers high convexity shape accuracy, its low processing efficiency is incompatible with the characteristics of mass production of tapered rollers.

[0003] The current principle of centerless through-feed grinding for tapered roller crown is as follows: the axial profile of the grinding wheel is dressed into a concave arc shape. By specially designing the axial profile of the guide wheel's helical working surface, the through-feed trajectory of the roller's center arc is controlled, and the roller's posture changes accordingly with the arc trajectory. This ensures that the roller's crown arc always matches the concave arc shape of the grinding wheel during the through-feed process. The method of forming the crown shape is essentially a forming method. However, in this method, the roller's posture is constantly changing during the through-feed process, requiring a continuous change in the inclination angle of the guide wheel's helical working surface. This leads to two limitations: firstly, the stability of the roller's through-feed motion is low; secondly, the machining difficulty and precision of the guide wheel's helical working surface are high, thus affecting the roller's machining accuracy. The reason for the low stability of the roller's through-feed motion in the existing method is that the change in the roller's posture during the through-feed process affects its motion stability. The reason why existing methods for machining the spiral working surface of the guide wheel are difficult, have low precision, and are costly is that not only does the diameter of this spiral working surface change along the axis of the guide wheel, but the inclination angle of its axial cross-section also changes. Therefore, when CNC grinding it, the guide wheel grinding machine needs four-axis linkage, namely, guide wheel rotation, guide wheel axial movement, grinding wheel radial movement, and grinding wheel axis oscillation in the horizontal plane. Among them, the oscillation of the grinding wheel axis in the horizontal plane greatly complicates the structure of the guide wheel grinding machine, resulting in high purchase and use costs, and the oscillation accuracy is difficult to meet the requirements for precise changes in the axial cross-section inclination angle.

[0004] The convexity of the roller is not an ideal convexity shape. High-end bearing rollers usually require a logarithmic convexity shape, which is something that the existing centerless through-grinding method for tapered roller convexity cannot meet. Summary of the Invention

[0005] This invention provides a method for grinding the convexity of conical rollers based on the envelope principle, in order to solve the problems of low quality of conical roller convexity grinding in existing centerless through-grinding methods, as well as the high difficulty, low precision, and high cost of guide wheel processing.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0007] A method for grinding the crown of conical rollers based on the envelope principle is disclosed. The roller crown is ground using a centerless grinder with a centerless through-feed grinding process. The axial profile of the grinding wheel is dressed into a convex arc curve with an appropriate radius. According to the requirement of conjugate motion between the convex arc curve and the roller crown curve, the through-feed motion trajectory of the roller center is designed under the condition that the roller posture remains unchanged. This causes the arc surface of the grinding wheel to perform conjugate motion relative to the roller crown surface, thereby forming the roller crown shape curve by the envelope method. At the same time, based on the geometric relationship and conjugate motion relationship between the roller and the guide wheel, the radius variation curve of the guide wheel is designed as the basis for the machining of the axial profile of the grinding wheel, so as to ensure the realization of the designed through-feed motion trajectory of the roller center.

[0008] Furthermore, for the convexity of a circular arc roller, the radius Rz of the axial profile arc of the grinding wheel is a value that is greater than the calculated radius R of the axial profile arc of the grinding wheel. z 'Integer values ​​between 1% and 5% smaller; where R is the calculated radius of the axial profile arc of the grinding wheel.' z The formula for calculating ' is as follows:

[0009]

[0010] In the formula, R z ' is the calculated radius of the axial profile arc of the grinding wheel, B is the width of the grinding wheel, R is the radius of the roller crown arc, L W Where α is the roller length and α is the roller half-cone angle.

[0011] Furthermore, for the convexity of an arc-shaped roller, in the normal plane of contact between the grinding wheel and the roller, the trajectory of the roller center is an arc, and the radius of the arc is equal to the axial profile arc R of the grinding wheel. z The sum of the radius R of the roller crown arc and the center of the arc are not concentric with the axial profile arc of the grinding wheel.

[0012] Furthermore, for the convexity of a circular arc roller, the guide wheel radius variation curve is a concave elliptical curve, and its equation is as follows:

[0013] In the formula, Y d Let X be the radius of any point on the guide wheel.d R is the distance from any point on the guide wheel to the center of its width. s R1 is the radius of the grinding wheel at the highest point of the axial profile arc, and B is the radius of the small end of the roller. d R is the width of the guide wheel. g R is the radius at the center of the roller's length. d h1 is the radius at the center of the guide wheel width, h2 is the center height of the tapered roller, h3 is the horizontal distance from the center of the tapered roller to the center of the guide wheel, and β is the horizontal distance from the center of the tapered roller to the center of the grinding wheel. s β is the angle of inclination of the line connecting the center of the roller and the grinding wheel relative to the horizontal plane. d Rz is the inclination angle of the line connecting the centers of the roller and the guide wheel relative to the horizontal plane, Rz is the radius of the axial profile arc of the grinding wheel, R is the radius of the roller crown arc, and L is the radius of the axial profile arc of the grinding wheel. W Where α is the roller length and α is the roller half-cone angle. a, b, and c are all intermediate variables.

[0014] Beneficial effects:

[0015] 1) The grinding method of the present invention can not only grind the arc-shaped convexity of tapered rollers, but also grind other convexities with smooth and continuous curve shapes such as logarithmic type, without any fundamental machining error;

[0016] 2) Compared with the existing centerless through-type arc convexity grinding method of conical rollers, the method of the present invention has higher precision in grinding convexity shape.

[0017] 3) Compared with the existing centerless through-type arc convexity grinding method for conical rollers, the method of the present invention has lower difficulty in machining the guide wheel, higher precision, and lower cost. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an existing centerless through-grinding method for tapered roller crown.

[0019] Figure 2 This is a schematic diagram of the existing method for CNC grinding of the guide wheel working surface in four-axis linkage.

[0020] Figure 3 This is a schematic diagram of the geometric relationship between the roller and the grinding wheel in the normal plane of contact between the grinding wheel and the roller.

[0021] Figure 4 This is a schematic diagram of the through-trajectory of the conical roller center in the normal plane of the contact between the grinding wheel and the roller.

[0022] Figure 5 This is a schematic diagram of the contact geometry between the tapered roller, the guide wheel, and the support plate.

[0023] Figure 6This is a schematic diagram of the roller penetration trajectory and the guide wheel radius variation curve within the normal contact plane of the roller-guide wheel.

[0024] Figure 7 This is a schematic diagram of the geometric relationship between the center coordinate systems of the grinding wheel and the guide wheel.

[0025] Figure 8 This is a schematic diagram of the principle of tapered roller crown envelope grinding.

[0026] Figure 9 This is a schematic diagram of the grinding point movement in tapered roller crown envelope grinding.

[0027] Figure 1 and Figure 2 middle:

[0028] 1' Grinding wheel, 2' Tapered roller, 3' Guide wheel, 4' Grinding wheel holder, 5' Worktable, 6' Spindle box;

[0029] Figures 3 to 9 middle:

[0030] 1. Grinding wheel; 2. Roller; 3. Support plate; 4. Guide wheel;

[0031] A. The center of the roller runs through the motion trajectory. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following uses the single-arc convexity envelope grinding method for tapered rollers as an example, and in conjunction with the accompanying drawings, the technical solutions in the embodiments of the present invention will be clearly and completely described, enabling those skilled in the art to better understand the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort, such as the centerless through-feature envelope grinding method for tapered rollers with multiple arcs of different radii combined with convexity, logarithmic convexity, etc., are within the scope of protection of the present invention.

[0034] The technical solution adopted in this invention is: a method for grinding the convexity of conical rollers based on the envelope principle. The roller convexity is ground using a centerless grinder with a centerless through-feed grinding method. The roller 2 is placed between the support plate 3 and the guide wheel 4. The grinding wheel 1 and the guide wheel 4 rotate together to grind the roller 2 located between them. The axial profile of the grinding wheel 1 is dressed into a convex arc curve with an appropriate radius. According to the requirement of conjugate motion between this arc curve and the roller convexity curve, the roller center through-feed motion trajectory A is designed under the condition that the roller 2 posture remains unchanged, so that the grinding wheel arc performs conjugate motion relative to the roller surface, thereby forming the roller convexity shape curve by the envelope method. At the same time, according to the geometric relationship and conjugate motion relationship between the roller 2 and the guide wheel 3, the guide wheel radius variation curve is designed as the basis for the axial profile machining of the grinding wheel, ensuring the realization of the designed roller center through-feed motion trajectory A.

[0035] Furthermore, for the convexity of a circular arc roller, the radius Rz of the axial profile arc of the grinding wheel is a value that is greater than the calculated radius R of the axial profile arc of the grinding wheel. z Using integer values ​​1% to 5% smaller ensures that the entire length of the roller crown arc is ground, and that the grinding wheel width is fully utilized. The calculated radius R of the grinding wheel axial profile arc is... z The formula for calculating ' is as follows:

[0036]

[0037] In the formula, R′ Z The radius of the axial profile arc of the grinding wheel is calculated, where B is the width of the grinding wheel, R is the radius of the roller crown arc, and L is the radius of the axial profile arc. W Where α is the roller length and α is the roller half-cone angle.

[0038] As an example, let's take the roller length L. w =32mm, roller half-cone angle α = 1°, roller crown radius R = 500mm; grinding wheel width B = 300mm, the calculated axial profile radius R of the grinding wheel is... z The value is 4687mm. Select an integer that is 1% to 5% smaller than the calculated value, i.e., Rz = 4600mm.

[0039] For a circular arc roller crown, the geometric relationship between the roller and the grinding wheel in the contact plane between the grinding wheel and the roller is as follows: Figure 3 As shown, the axial profile of the grinding wheel is an arc, with its center at O. z The radius of the arc is R z The grinding wheel width is B; the roller crown curve is a circular arc with its center at O. c The radius of the arc is R, and the center of the roller is O. g The total length of the roller is L w The nominal length of the generatrix of the roller conical surface is L. According to the principle of envelope grinding, Figure 3 In the middle, the center O of the roller convexity arcc The penetration trajectory is an arc, which is a concentric circle of the axial profile arc of the grinding wheel, and its radius is equal to the axial profile arc R of the grinding wheel. z The sum of the roller crown radius R; at any position where the roller passes through, the roller crown radius is tangent to the axial profile arc of the grinding wheel, and the inclination angle λ of the roller axis relative to the grinding wheel axis remains unchanged, which is equal to the roller half-cone angle α.

[0040] like Figure 3 As shown, assuming the width of grinding wheel 1 is fully utilized, when roller 2 is located at the right end of grinding wheel 1, the left endpoint G1 of the roller convexity arc and the right endpoint S1 of the grinding wheel axial profile arc are the two arcs tangent; when roller 2 is located at the left end of grinding wheel 1, the right endpoint G2 of the roller convexity arc and the left endpoint S2 of the grinding wheel axial profile arc are the two arcs tangent; and when roller 2 is located at the center of the width of grinding wheel 1, the midpoint G0 of the roller convexity arc and the midpoint S0 of the grinding wheel axial profile arc are the two arcs tangent, and this tangent point is also located at the center of the width of the grinding wheel. From this, the formula for calculating the radius Rz of the grinding wheel axial profile arc can be obtained.

[0041] Furthermore, for the convexity of the arc-shaped roller, in the contact plane between grinding wheel 1 and roller 2, the trajectory A of the roller center is an arc, the radius of which is equal to the radius R of the axial profile arc of the grinding wheel. z It is the sum of the radius R of the roller crown arc, but its center is not concentric with the axial profile arc of the grinding wheel.

[0042] like Figure 3 As shown, within the normal contact plane between the grinding wheel and the roller, the angle between the roller axis and the grinding wheel axis remains constant. This means that the penetrating motion of roller 2 is a translational motion; the center of roller 2 does not rotate relative to the center of the roller convexity arc. Therefore, the penetrating motion trajectory curve of the roller center is the same arc curve as the penetrating trajectory of the center of the roller convexity arc, with equal radii, only differing in the position of the center. As mentioned earlier, the center O of the roller convexity arc... c The penetration trajectory is an arc, which is a concentric circle of the axial profile arc of the grinding wheel, and its radius is equal to the axial profile arc R of the grinding wheel. z The sum of the radius R of the roller crown arc is given. Therefore, for a circular roller crown, in the contact plane between grinding wheel 1 and roller 2, the trajectory A of the roller center is an arc, and its radius is equal to the axial profile arc R of the grinding wheel. z It is the sum of the radius R of the roller crown arc, but its center is not concentric with the axial profile arc of the grinding wheel.

[0043] Obviously, once the positional relationship between the roller center and the center of the roller convexity arc is determined, the equation of the roller center's through motion trajectory can be written based on the arc equation of the through trajectory of the roller convexity arc center.

[0044] A schematic diagram of the through-motion trajectory A of the roller center within the normal contact plane of the grinding wheel and roller is shown below. Figure 4 As shown, the orthogonal coordinate system O s X s Y s Origin of coordinates s Located at the center of the grinding wheel, X s Along the axis of the grinding wheel, S1S2 is the axial profile arc of the grinding wheel, and the center trajectory arc C1C2 of the roller crown arc are equidistant lines of the axial profile arc of the grinding wheel, with the equidistant value being the radius R of the roller crown arc; O1O2 is the through trajectory arc curve of the roller center, R s The radius of the grinding wheel cross-section (the radius at the highest point of the axial profile arc of the grinding wheel); others are the same as... Figure 3 The same symbols in the same language have the same meaning.

[0045] like Figure 4 As shown, the center O of the roller convexity arc c The penetration trajectory is an arc, which is a concentric circle of the axial profile arc of the grinding wheel, and its radius is equal to the axial profile arc R of the grinding wheel. z The sum of the radius R of the roller crown arc and the center of the arc is the center O of the axial profile arc of the grinding wheel. z The center of the circle is in coordinate system O s X s Y s The coordinates in the equation are (0, -R) z +R s Therefore, in coordinate system O s X s Y s In the middle, the equation of the trajectory through the center of the roller convexity arc is:

[0046]

[0047] In coordinate system O s X s Y s In the process, the roller's through-feed motion is a translational motion; at any point during its through-feed, the roller's center O... g Coordinates and the center O of the roller convexity arc c The difference between the coordinates is the same, equal to the line segment O. c O g By projecting the data onto the two coordinate axes and obtaining the two projection values, we can then use the above equation for the trajectory of the roller center penetration through the arc of the roller convexity to write the equation for the trajectory of the roller center penetration motion as follows:

[0048]

[0049] Furthermore, for the convexity of a circular arc roller, the guide wheel radius variation curve is a concave elliptical curve, and its equation is as follows:

[0050] In the formula, Y d Let X be the radius of any point on the guide wheel. d R is the distance from any point on the guide wheel to the center of its width. s R1 is the radius of the grinding wheel at the highest point of the axial profile arc, and B is the radius of the small end of the roller. d R is the width of the guide wheel. g R is the radius at the center of the roller's length. d h1 is the radius at the center of the guide wheel width, h2 is the center height of the tapered roller, h3 is the horizontal distance from the center of the tapered roller to the center of the guide wheel, and β is the horizontal distance from the center of the tapered roller to the center of the grinding wheel. s β is the angle of inclination of the line connecting the center of the roller and the grinding wheel relative to the horizontal plane. d Rz is the inclination angle of the line connecting the centers of the roller and the guide wheel relative to the horizontal plane, Rz is the radius of the axial profile arc of the grinding wheel, R is the radius of the roller crown arc, and L is the radius of the axial profile arc of the grinding wheel. W Where α is the roller length and α is the roller half-cone angle. a, b, and c are all intermediate variables. They have no specific geometric meaning.

[0051] The guide wheel radius variation curve is related not only to the roller center through motion trajectory A, but also to the contact geometry between the roller and the guide wheel.

[0052] The contact geometry between roller 2, guide wheel 4, and support plate 3 is as follows: Figure 5 As shown in the figure: O g R is the center of the tapered roller. g The radius at the center of the roller's length; O d R is the center of the cross-section of the guide wheel. d The radius at the center of the guide wheel width; O d X d1 Y d1 Z d1 Let Y be the orthogonal coordinate system of the guide wheel center. d1 Z is the horizontal axis. d1 X is the vertical horizontal axis. d1 The horizontal longitudinal axis (the positive direction is perpendicular to the paper and outwards, not shown in the figure); O d X d2 Y d2 Z d2 Let Y be the orthogonal coordinate system of the guide wheel center. d2 Passing O d and O g Two points, X d2 With X d1 Coincidence; h1 is the center height of the tapered roller, h2 is the horizontal distance from the center of the tapered roller to the center of the guide wheel cross-section; β d For O g and Od The angle between the line connecting the two points and the horizontal plane (the support angle of the guide wheel to the roller). d X d2 Y d2 The plane is the normal contact plane between the guide wheel and the roller.

[0053] like Figure 6 As shown, within the normal contact plane between the guide wheel and the roller, the roller convexity can be considered as a circular arc curve. The guide wheel radius variation curve is the envelope of the roller convexity arc, which is the equidistant line through the roller center's motion trajectory A. The equidistant value is the roller's cross-sectional radius R. g . Figure 6 In the diagram, O1O2′ is the roller center through trajectory curve; D1D2 is the guide wheel radius variation curve, i.e., the envelope of the roller convexity arc curve.

[0054] By transforming the equation of the roller center through motion trajectory curve established in the normal plane of contact between grinding wheel 1 and roller 2 to the coordinate system of the guide wheel center in the normal contact plane between guide wheel 4 and roller 2, the equation of the roller center through motion trajectory in the normal contact plane between guide wheel and roller can be obtained, and thus the equation of the guide wheel radius change curve can be obtained.

[0055] The positional relationship between the orthogonal coordinate system of the grinding wheel width center and the orthogonal coordinate system of the guide wheel center is as follows: Figure 7 As shown. Figure 7 The symbols that appear in the text are the same as those in the previous figures, and they have the same meaning; Figure 7 China O s X s1 Y s1 Z s1 Let Y be the orthogonal coordinate system at the center of the grinding wheel width. s1 Z is the horizontal axis. s1 X is the horizontal axis of the plumb bob. s1 The horizontal longitudinal axis (the positive direction is perpendicular to the paper and outwards, not shown in the figure); O s X s Y s Z s Let Y be the orthogonal coordinate system of the grinding wheel center. s Passing O s and O g Two points, X s With X s1 Coincident; h3 is the horizontal distance from the center of the tapered roller to the center of the grinding wheel width; β s For O c and O g The angle between the line connecting the two points and the horizontal plane (the cutting angle of the grinding wheel to the roller). The normal contact plane between the grinding wheel and the roller is O. s X s Y s flat.

[0056] From the orthogonal coordinate system O at the center of the grinding wheel s X s Y s Z s Orthogonal coordinate system O at the center of the guide wheel d X d2 Y d2 Z d2 The transformation method is as follows: first, around X s Rotate the axis clockwise by β s Angle to coordinate system O s X s1 Y s1 Z s1 Then translate to the right by (h2+h3) to the center coordinate system O of the guide wheel. d X d1 Y d1 Z d1 In the middle, finally around X d1 The axis rotates counterclockwise (π-β) d Angle to coordinate system O d X d2 Y d2 Z d2 In this case, the total transformation matrix is ​​T:

[0057] The equation of the roller center's through-motion trajectory curve, established in the normal plane of contact between grinding wheel 1 and roller 2, is transformed to the coordinate system of the guide wheel center in the normal plane of contact between guide wheel 4 and roller 2. Note that the guide wheel radius variation curve is an equidistant curve of this trajectory curve, with the equidistant value being the roller's cross-sectional radius R. g Thus, the above guide wheel radius curve equation can be obtained.

[0058] The guide wheel radius variation curve is O s X s Y s The arc curve of the roller's center in the plane is projected onto O. d X d2 Y d2 The guide wheel radius variation curve is theoretically an ellipse, obtained by dividing the plane and equidistant from the cross-sectional radius of a roller.

[0059] Using the guide wheel radius variation curve for CNC grinding of the guide wheel axial profile can ensure the realization of the designed roller center through motion trajectory A, thereby ensuring the envelope grinding of the roller arc convexity.

[0060] The beneficial effects of the grinding method of the present invention and the technical principles underlying these effects are as follows:

[0061] (1) The method of the present invention can not only grind arc-shaped convexity, but also grind other smooth continuous curve shapes such as logarithmic type, without any fundamental machining error. Its technical principle is as follows.

[0062] The grinding principle of the conical roller crown envelope method of this invention is as follows: Figure 8 As shown, the axial profile of grinding wheel 1 is dressed into a convex circular arc curve with an appropriate radius. Based on the requirement of conjugate motion between this circular arc curve and the roller crown curve, the roller center through-motion trajectory A is designed under the condition that the roller 2 posture remains unchanged. This causes the grinding wheel arc to perform conjugate motion relative to the roller surface, thereby forming the roller crown shape curve using the envelope method. Regardless of whether the roller crown shape curve is a circular arc curve or other smooth continuous curves such as logarithmic curves, as long as the axial profile of the grinding wheel is a circular arc curve with an appropriate radius, under the condition that the roller posture remains unchanged, the conjugate motion trajectory curve between the two, i.e., the roller center through-motion trajectory curve, can be calculated based on the principle of conjugate surfaces. Thus, as long as the axial profile of the helical guide wheel is designed accordingly to ensure the roller center through-motion trajectory curve, envelope grinding of the roller crown shape can be achieved without any fundamental machining errors.

[0063] In envelope grinding, the theoretical crown shape curve of the roller is always tangent to the axial profile arc of the grinding wheel; the point of tangency is the grinding point. During the roller's penetration, the grinding point moves both along the axial profile arc of the grinding wheel and along the roller's crown curve. For example... Figure 9 As shown, as the roller penetrates, the grinding points on the grinding wheel are located successively at points a1, b1, and c1. Correspondingly, on the roller convexity curve, the grinding points are located successively at points a2, b2, and c2. Thus, if grinding points a2 and c2 are located at the two ends of the roller convexity curve, and grinding points a1 and c1 are located at the two ends of the grinding wheel width, grinding can be achieved across the entire width of the grinding wheel and the entire length of the roller convexity curve, thereby improving grinding efficiency and reducing uneven wear of the grinding wheel.

[0064] (2) Compared with the existing centerless through-type arc convexity grinding method of conical rollers, the technical principle of the present invention to grind convexity shape with higher accuracy is as follows:

[0065] Existing methods for centerless through-feature grinding of conical rollers with convex arcs include... Figure 1As shown, the principle of convexity grinding is to dress the axial profile of the grinding wheel 1' into a concave arc shape. The orientation and arc-penetrating trajectory of the roller 2' are controlled by the helical working surface of the specially designed guide wheel 3', ensuring that the convex arc of the roller 2' always matches the concave arc shape of the grinding wheel 1' during its penetration, thus forming the convex shape of the roller 2'. In this convexity grinding method, the orientation of the roller 2' is constantly changing during its penetration. Correspondingly, the tilt angle of the roller 2' axis relative to the axes of the guide wheel 3' and the grinding wheel 1' is also continuously changing. Therefore, the tilt angle of the axial cross-section of the helical surface of the guide wheel 3' must be continuously changing.

[0066] In contrast, the method of the present invention maintains a constant roller posture during the penetration process, resulting in higher penetration accuracy and improving the roller convexity shape accuracy. Furthermore, compared to the method of the present invention, existing methods involve more difficult and less precise guide wheel machining, which also reduces the penetration accuracy of roller 2 and consequently affects the roller convexity shape accuracy.

[0067] (3) Compared with the existing centerless through-type arc convexity grinding method for tapered rollers, the method of the present invention has lower difficulty in machining the guide wheel, higher precision, and lower cost. Its technical principle is as follows:

[0068] In existing methods, the diameter of the helical surface of guide wheel 3' varies along its axial axis, and the inclination angle of its axial cross-section also varies. Therefore, when CNC grinding the working surface of guide wheel 3', the guide wheel grinding machine needs four-axis linkage, namely, the rotation of guide wheel 3', the axial movement of guide wheel 3', the radial movement of grinding wheel 1', and the horizontal oscillation of the grinding wheel axis must be coordinated. Figure 2 As shown, this requires a more powerful CNC system. Furthermore, to achieve the horizontal oscillation of the grinding wheel axis, the guide wheel grinder needs to add a rotary support and rotary drive system under the transverse feed guide of the grinding wheel 1'. This significantly complicates the mechanical structure and CNC requirements of the grinder, leading to several problems: first, the support stiffness of the grinding wheel 1' system is low, affecting grinding quality and efficiency; second, increased costs result in a high price for the grinder; and third, the oscillation accuracy is not easily sufficient to meet the accuracy requirements of the guide wheel 3's axial cross-sectional tilt angle change.

[0069] The method of this invention for grinding the guide wheel 4 only requires two-axis linkage: the axial movement of the guide wheel 4 and the radial movement of the grinding wheel head. This satisfies the requirement that the diameter of the spiral guide wheel 4 changes axially, without requiring the grinding wheel axis to swing horizontally. Correspondingly, the guide wheel grinding machine does not require a rotary support and its drive system under the grinding wheel head, and the CNC system does not require four-axis linkage. Only three-axis linkage is needed: the rotation of the guide wheel 4, the axial movement of the guide wheel, and the radial movement of the grinding wheel head. In this way, the structure and CNC requirements of the guide wheel grinding machine are greatly simplified, and the rigidity of the grinding wheel support system is greatly improved. Therefore, the guide wheel is easier to process, has higher precision, and lower cost.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method of grinding the crown of a tapered roller based on the envelope principle, the crown of the roller being ground by means of a centerless through-feed grinding on a centerless grinder, characterized in that, The grinding wheel axial profile is modified to a convex circular arc curve with proper radius, and the center penetrating motion trajectory of the roller is designed under the condition that the posture of the roller is unchanged according to the requirement of the conjugate motion between the convex circular arc curve and the roller convex shape curve, so that the grinding wheel circular arc surface moves in the conjugate motion relative to the roller surface, thereby forming the roller convex shape curve in the enveloping method; meanwhile, according to the geometric relationship and the conjugate motion relationship between the roller and the guide wheel, the guide wheel radius change curve is designed as the basis for the grinding wheel axial profile processing, so as to ensure the realization of the designed center penetrating motion trajectory of the roller; For the circular arc roller convexity, the guide wheel radius change curve is a concave elliptical curve, and the equation is as follows: where Y d is the radius of the arbitrary point on the guide wheel, X d is the distance from the arbitrary point on the guide wheel to the center of its width, R s is the radius of the grinding wheel at the highest point of the axial profile arc, R1 is the radius of the small end of the roller, B d is the width of the guide wheel, R g is the radius at the center of the length of the roller, R d is the radius at the center of the width of the guide wheel, h1 is the center height of the tapered roller, h2 is the horizontal distance from the center of the tapered roller to the center of the guide wheel, h3 is the horizontal distance from the center of the tapered roller to the center of the grinding wheel, β s is the inclination angle of the line connecting the center of the roller and the center of the grinding wheel relative to the horizontal plane, β d is the inclination angle of the line connecting the center of the roller and the center of the guide wheel relative to the horizontal plane, Rz is the radius of the axial profile arc of the grinding wheel, R is the radius of the convexity arc of the roller, L W is the length of the roller, α is the half taper angle of the roller, , a, b, and c are all intermediate variables.

2. A method of grinding the crown of a tapered roller according to claim 1, wherein For the circular-arc-shaped roller crown, the grinding wheel axial profile circular-arc radius Rz is a ratio of the grinding wheel axial profile circular-arc calculation radius to the grinding wheel axial profile circular-arc calculation radius Rz0. The calculation formula is as follows: In the formula, R is the radius of the roller convexity arc, L W is the length of the roller, α is the half-cone angle of the roller.

3. A method of grinding the crown of a tapered roller according to claim 2, wherein For the circular-arc roller crown, the center trace of the roller is a circular arc in the normal plane of the contact between the grinding wheel and the roller, the radius of the circular arc is equal to the axial profile circular arc of the grinding wheel Rz The sum of the roller crown circular arc radius R The center of the circular arc is not concentric with the axial profile circular arc of the grinding wheel.

Images