Device and method for honing tapered rollers
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SCHAEFFLER TECHNOLOGIES AG & CO KG
- Filing Date
- 2024-07-11
- Publication Date
- 2026-05-27
AI Technical Summary
Existing honing methods for tapered rollers in rolling bearings lack the precision and efficiency to achieve close tolerances and high process reliability, particularly in maintaining a favorable relationship between processing efficiency and product quality.
A honing device with two parallel honing rollers and at least one honing stone, where the honing rollers have thread profiles that allow the central axes of tapered rollers to pivot within a horizontal plane, enabling a continuous or gradual change in skew angle, allowing for precise profiling of the rollers' lateral surfaces, primarily near the end faces and then the middle areas, resulting in a convex profile such as circular or logarithmic.
This approach enables precise control over material removal and profile shaping, ensuring high precision and reliability in the honing process, allowing for the creation of desired profiles like logarithmic or circular shapes with minimal deviation from the conical shape, while maintaining horizontal alignment of the rollers' axes throughout processing.
Smart Images
Figure DE2024100629_23012025_PF_FP_ABST
Abstract
Description
[0001] Device and method for honing key rollers
[0002] The invention relates to a method for honing tapered rollers intended for use in rolling bearings. Furthermore, the invention relates to a device suitable for carrying out such a honing method, designed according to the preamble of claim 1.
[0003] A generic device for machining tapered rollers by honing is known, for example, from EP 3 100 823 A1. According to EP 3 100 823 A1, rolling elements to be honed are transported by two driven supply drums, i.e., honing rollers. The rolling elements, designed as tapered rollers, are in contact with thread-like guide surfaces of the honing rollers. Honing stones, with which the tapered rollers are machined in a continuous process, are referred to as millstones in EP 3 100 823 A1. These guide surfaces are designed such that the angular relationship between the tapered rollers and the honing stones changes as the tapered rollers pass through the honing device.
[0004] WO 2021 / 239182 A1 discloses a device for honing spherical roller bearings for spherical roller bearings. In this case, too, the workpieces—here, spherical roller bearings—are advanced during machining by means of two honing rollers. According to WO 2021 / 239182 A1, at least one honing stone with a grooved honing surface is used for honing.
[0005] A method described in JP H07290347 A for grinding roller-shaped workpieces in a continuous process provides for the workpieces, which rotate about their own longitudinal axis and are simultaneously conveyed in their longitudinal direction, to be tilted about an axis transverse to their longitudinal axis during their feed, in particular to profile areas of the workpiece's peripheral surface that border a workpiece end face. The tilting of the workpieces is to be achieved with the aid of a ruler that guides the workpieces and has a recess.
[0006] DE 37 07 335 A1 discloses a device for short-stroke honing of barrel rolls. The barrel rolls are machined using this device in a continuous process and held at an angle to the transport direction, with a suggested skew angle between 3° and 30°.
[0007] In a device for machining rolling elements by honing described in US 2019 / 0076977 A1, the workpieces, i.e. rolling elements, undergo a tilting movement during their machining, which is intended to contribute to the creation of a logarithmic profiling.
[0008] The invention is based on the object of further developing the honing of tapered rollers compared to the aforementioned prior art, whereby a particularly favorable relationship between efficient machining and high process reliability with close tolerances of the end products, i.e. tapered rollers, is sought.
[0009] This object is achieved according to the invention by a device for honing tapered rollers having the features of claim 1. The object is also achieved by a method for honing tapered rollers intended for use as rolling elements according to claim 5. Embodiments and advantages of the invention explained below in connection with the honing method also apply mutatis mutandis to the device designed for honing and vice versa.
[0010] The honing device comprises two honing rollers arranged parallel to one another for supporting tapered rollers, and at least one honing stone engaging between the honing rollers for machining the tapered rollers. The honing rollers have thread profiles designed to convey the tapered rollers, with the feed direction of the tapered rollers being determined by the longitudinal direction of the honing rollers. The thread profiles of the honing rollers are designed such that the center axes of the tapered rollers conveyed by the honing rollers lie in a common plane parallel to the rotation axes of the honing rollers and, as the workpieces, i.e., tapered rollers, are conveyed, they undergo pivoting within said plane. This plane is arranged parallel to a reference plane in which the center axes of the two honing rollers lie.
[0011] Arranging the honing rollers at the same height means that the center axes of the workpieces, i.e., the tapered rollers, are pivoted in a horizontal plane. In particular, the center axes of the tapered rollers are pivoted exclusively in this plane. Compared to pivoting in a vertical plane, this allows for a much more precise control of the rolling element profile to be created by honing.
[0012] The thread profiles of the honing rollers can be designed in such a way that the tapered rollers' skew angle changes continuously in the feed direction. Alternatively, the thread profiles of the honing rollers can specify a tapered roller skew angle that changes gradually in the feed direction. The two honing rollers do not necessarily have exactly the same shape. Honing rollers are also generally referred to as transport rollers.
[0013] There are various ways of machining the honing rollers, which cause the skew angle of the rolling elements to change in the feed direction during honing.
[0014] A first option is to machine the honing roller by hard turning. In this case, the honing roller is machined using a turning tool with a large corner radius, for example. The turning tool is moved axially along the honing roller with a feed movement coordinated with the rotation of the honing roller, which corresponds to the pitch of the honing roller's profile per revolution. After each revolution of the workpiece—in this case, the honing roller—or after a defined, not necessarily integer, number of revolutions, the turning tool can be advanced radially by a small amount if stepped changes in the skew angle are intended. With this new setting of the turning tool, the feed movement and thus the machining process are continued. In the same setup, an axial stop surface for the tapered rollers can also be machined by turning.
[0015] A second option for precisely profiling the honing roll thread is grinding the honing roll. In this case, too, the profile of the honing roll can be changed gradually or continuously over the machining length. For dressing a grinding wheel during the grinding process, for example, a profile roller can be used, which is advanced and / or pivoted in the radial direction of the grinding wheel. The changing arrangement of the profile roller during the machining process is copied to the workpiece being ground, i.e., the honing roll.
[0016] Regardless of the machining technology used to machine the honing roll, the skew angle of the tapered rollers, which is imposed by the shape of the honing rolls, can decrease in the throughput direction during honing. In this way, the surface areas of the tapered rollers near their end faces are machined first, and only then primarily the central areas of the tapered rollers' lateral surfaces are machined, ultimately resulting in a convex profile of the lateral surface, which has a conical basic shape. The convex profile can be in the form of a circular or logarithmic profile.
[0017] During the honing process, the longitudinal axes of the tapered rollers are pivoted in a horizontal plane, for example, by an angle of at least 0.5°, but no more than 3°. A number of honing stones arranged in a row in a vertical plane are suitable for honing. The final profiling of the tapered rollers depends particularly on the geometry of the honing stones. Material removal, especially in the transition areas between the outer surface and the end faces of the tapered rollers, can also be controlled by the honing pressure acting on the workpieces.
[0018] An embodiment of the invention and a comparative example (not claimed) are explained in more detail below with reference to a drawing. These show, partly simplified:
[0019] Fig. 1 shows an embodiment of a honing device for machining tapered rollers in perspective view,
[0020] Fig. 2 Components of the arrangement according to Fig. 1 in plan view, including details in an exaggerated representation,
[0021] Fig. 3 shows partial components of the arrangement according to Fig. 1, namely two honing rollers and numerous tapered rollers guided between the honing rollers,
[0022] Fig. 4 shows a rolling element to be honed, precisely aligned in the longitudinal direction of the honing device, and a honing stone of the arrangement according to Fig. 1 in a front view,
[0023] Fig. 5 shows the components of the arrangement according to Fig. 4, also in a frontal view, wherein the rolling element, i.e. the workpiece, is in a horizontal plane parallel to the longitudinal axes of two honing rollers of the device according to Fig. 1 in comparison to the orientation according to Fig. 4, Fig. 6 shows the arrangement according to Fig. 5 in a side view,
[0024] Fig. 7 shows a non-claimed comparative example in a view analogous to Fig. 6.
[0025] The following explanations refer, unless otherwise stated, to both the embodiment according to Figures 1 to 5 and to the unclaimed comparative example according to Figure 6, which serves only for explanation. Parts which correspond to one another or have essentially the same function are identified by the same reference numerals in all figures.
[0026] A device for honing tapered rollers 2 for rolling bearings, i.e., tapered roller bearings, identified overall by the reference numeral 1, comprises two honing rollers 3, 4 that rotate in the same direction during operation of the honing device 1, wherein the rotation axes of the honing rollers 3, 4 are arranged parallel to one another at the same height. Each honing roller 3, 4 has a thread profile 5, 6, so that the honing rollers 3, 4 have an overall helical shape, with both honing rollers 3, 4 describing a right-hand thread. Likewise, configurations are possible in which both honing rollers 3, 4 describe a left-hand thread. In the exemplary embodiment, the thread profiles 5, 6 are designed as single-start threads. Alternatively, the thread profiles 5, 6 can be designed as multi-start threads.
[0027] A gap 7 is formed between the honing rollers 3, 4, into which gap the tapered rollers 2 are inserted, making contact with the thread profiles 5, 6. All longitudinal axes of the tapered rollers 2 are located above the center axis of the honing device 1 in a common horizontal plane. The center axis of the entire honing device 1 is at the level of the rotation axes of the honing rollers 3, 4. The horizontal plane in which the rotation axes of the honing rollers 3, 4 lie is referred to as the reference plane. Due to the co-rotation of both honing rollers 3, 4, the tapered rollers 2 arranged in a row are advanced in the longitudinal direction of the center axis, i.e. in the feed direction VR, and simultaneously rotated about their respective longitudinal axes. The end faces of the tapered rollers 2, designated 9, are spaced from one another, while the conical outer surfaces of the tapered rollers 2, designated 8, roll on the thread profiles 5, 6.
[0028] In vertical projection (Fig. 2), each longitudinal axis of a tapered roller 2 forms an angle yi, Y2, Y3, Y4 with the center axis of the honing device 1, which, as shown in Fig. 2 in an exaggerated representation, represents a skew angle that decreases in the feed direction VR. In fact, the change in the angle yi, Y2, Y3, Y4 in the feed direction VR is so small that it is not visible to the naked eye in the section shown in Fig. 3. In this section, the skew angle YI, Y2, Y3, Y4 varies in a range of approximately 2° to 1°.
[0029] Honing is performed using several honing stones 10 arranged one behind the other in the feed direction VR, which are arranged in a common vertical plane intersecting the central axis of the honing device 1. Each honing stone 10 has the basic shape of an elongated cuboid.
[0030] Due to the decreasing inclination of the barrel rollers 2 relative to the longitudinal direction of the honing device 1 during the honing process, initially mainly areas of the lateral surfaces 8 close to the end faces 9 are machined, and only later the areas of the lateral surfaces 8 of the tapered rollers 2 located centrally between the end faces 9 are machined. Overall, this results in a desired deviation from an exactly conical shape of the lateral surfaces 8. In the present case, a logarithmic profile of the tapered rollers 2 is generated. Alternatively, a circular spherical shape of the lateral surfaces 8 could be generated by changing the geometric and process parameters.
[0031] In any case, since the longitudinal axes of the workpieces, i.e., the tapered rollers 2, remain horizontally aligned throughout the entire machining process, a very precise determination of the material removal by honing is possible. For clarification, reference is made to the schematic Figures 4 to 7, in which the conicity of the rolling elements 2 to be machined is not visible.
[0032] In the arrangement according to Fig. 3, the central axis of the tapered roller 2 is aligned exactly parallel to the central axis of the entire honing device 1, perpendicular to the plane of the drawing.
[0033] No machining takes place in this orientation. Rather, machining takes place in the inclined position of the tapered roller 2, as sketched and exaggerated in Figures 4, 5, and 6. As can be clearly seen from these figures, a rotation of the tapered roller 2 about an imaginary vertical axis, which is equivalent to the longitudinal axis of the tapered roller 2 remaining in the same horizontal plane, would only lead to a slightly changed overall pattern regarding the contact between the workpiece 2, i.e., the tapered roller, and the tool, i.e., the honing stone 10.
[0034] In contrast, according to Fig. 7, which shows a comparative example, it is assumed that the center axis of the workpiece 2, i.e., the rolling element to be machined, is pivoted in a vertical plane, namely in the plane in which the honing stones 10 are arranged. Such pivoting, which is not provided for in the method according to the application, would lead to a drastic change in the contact between the workpiece 2 and the tool 10 during honing. In particular, the comparison between Figures 6 and 7 illustrates that the concept according to the application, of pivoting the longitudinal axes of the tapered rollers 2 exclusively in a horizontal plane parallel to the center axes of the honing rollers 3, 4, enables particularly high precision during honing.
[0035] 1 honing device
[0036] 2 tapered rollers
[0037] 3 Honing roller
[0038] 4 Honing roller
[0039] 5 Thread profile
[0040] 6 thread profile
[0041] 7 gap
[0042] 8 Shell surface
[0043] 9 Frontal surface
[0044] 10 Honing stone
[0045] Y1 ... Y4 angle
[0046] VR feed direction
Claims
Patent claims 1. A device for honing tapered rollers (2), comprising two honing rollers (3, 4) arranged parallel to one another for supporting tapered rollers (2), and a honing stone (10) engaging between the honing rollers (3, 4) for machining the tapered rollers (2), wherein the honing rollers (3, 4) have thread profiles (5, 6) designed to convey the tapered rollers (2), which are configured such that the center axes of the tapered rollers (2) conveyed in the feed direction (VR), i.e. parallel to the longitudinal direction of the honing rollers (3, 4), lie in a common plane which is parallel to the axes of rotation of the two honing rollers (3, 4), and undergo a pivoting within the common plane during conveyance in the feed direction (VR), characterized in that the common plane is arranged parallel to a reference plane in which the axes of rotation of the two honing rollers (3, 4) lie.
2. Honing device according to claim 1, characterized in that the thread profiles (5, 6) of the honing rollers (3, 4) provide a skew angle (yi, 2, ys, Y ) of the tapered rollers (2) which changes continuously in the feed direction (VR).
3. Honing device according to claim 1, characterized in that the thread profiles (5, 6) of the honing rollers (3, 4) provide a skew angle (yi, 2, ys, Y ) of the tapered rollers (2) which changes stepwise in the feed direction (VR).
4. Honing device according to one of claims 1 to 3, characterized in that the thread profiles (5, 6) of the honing rollers (3, 4) provide a skew angle (yi, 2, Y3, Y ) of the tapered rollers (2) which decreases in the feed direction (VR).
5. Method for honing tapered rollers (2), wherein tapered rollers (2) are advanced by two honing rollers (3, 4) during honing in such a way that the longitudinal axes of the tapered rollers (2) are wasted during honing in a plane which is arranged parallel to a reference plane in which the axes of rotation of the honing rollers (3, 4) lie.
6. Method according to claim 5, characterized in that the pivoting of the longitudinal axes of the tapered rollers (2) takes place exclusively in the said plane parallel to the reference plane.
7. Method according to claim 6, characterized in that the longitudinal axes of the tapered rollers (2) are bent during honing by an angle of at least 0.5° and a maximum of 2° in said plane.
8. Method according to claim 6 or 7, characterized in that by honing with the orientation of the longitudinal axis of each tapered roller (2) changing during the machining, a logarithmic profile of a lateral surface (8) of the tapered roller (2) is produced.
9. Method according to claim 6 or 7, characterized in that by honing with the orientation of the longitudinal axis of each tapered roller (2) changing during the machining, a circular spherical profile of a lateral surface (8) of the tapered roller (2) is produced.