Grinding wheel and method |
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申请号 | US12191043 | 申请日 | 2008-08-13 | 公开(公告)号 | US08485865B2 | 公开(公告)日 | 2013-07-16 |
申请人 | Mark Iain Pilkington; | 发明人 | Mark Iain Pilkington; | ||||
摘要 | A grinding wheel for grinding features into a work-piece and a corresponding method for grinding the features into the work-piece are disclosed herein. The grinding wheel includes an outer periphery with a first axial end having a first diameter. The grinding wheel also includes a second axial end spaced from the first axial end along a centerline axis. The grinding wheel also includes a plurality of discrete grinding projections for removing material from the work-piece. Each of the plurality of discrete grinding projections extends radially outward from the outer periphery and is positioned along the centerline axis in spaced relation to one another. The plurality of grinding projections have working heights that vary relative to one another. In the inventive method, a grinding wheel is rotated about an axis of rotation. The axis of rotation is arranged transverse to and spaced from a centerline axis of an arcuate surface of a work-piece. The grinding wheel and the arcuate surface are moved relative to one another and a plurality of grooves having variable depth are concurrently formed along at least a portion of a perimeter of the arcuate surface with the grinding wheel during at least part of the moving step. | ||||||
权利要求 | What is claimed is: |
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说明书全文 | 1. Field of the Invention The invention relates to a method for forming features in a work-piece with a grinding wheel and the like. 2. Description of Related Prior Art Grinding is a process by which material is removed from a work-piece by abrasion or friction. The process can be useful in shaping work-pieces that are too hard to be machined by conventional methods such as hardened tool steels and case or induction hardened components. A grinding operation can produce a work-piece having features with a high degree of dimensional accuracy and a superior surface finish. In summary, the invention includes a grinding wheel for grinding features into a work-piece and a corresponding method for grinding the features into the work-piece. The grinding wheel includes an outer periphery with a first axial end having a first diameter. The grinding wheel also includes a second axial end spaced from the first axial end along a centerline axis. The grinding wheel also includes a plurality of discrete grinding projections for removing material from the work-piece. Each of the plurality of discrete grinding projections extends radially outward from the outer periphery and is positioned along the centerline axis in spaced relation to one another. The plurality of grinding projections have working heights that vary relative to one another. In the inventive method, a grinding wheel is rotated about an axis of rotation. The axis of rotation is arranged transverse to and spaced from a centerline axis of an arcuate surface of a work-piece. The grinding wheel and the arcuate surface are moved relative to one another and a plurality of grooves having variable depth are concurrently formed along at least a portion of a perimeter of the arcuate surface with the grinding wheel during at least part of the moving step. Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: As will become clear from the detailed disclosure below, the exemplary grinding wheel and exemplary method disclosed herein can improve the efficiency and reduce the cost associated with processing features in arcuate surface by reducing cutting time. The exemplary grinding wheel and method can form grooves in the work-piece such that the finished work-piece defines teeth or splines having the dimensional accuracy and superior surface finish associated with grinding. In addition, the exemplary grinding wheel and method can form grooves in the work-piece as fast or faster than shaping and hobbing processes, without the relatively expensive and easily-worn tools associated with those processes. Thus, the exemplary grinding wheel and method can provide the advantages associated with grinding, shaping, hobbing without the disadvantages or trade-offs associated with these various processes. Referring now to Referring now only to Each of the plurality of discrete grinding projections 26-42 can extend radially outward from the outer periphery 14. The grinding projections 26-42 can be positioned along the centerline axis 24 in spaced relation to one another. The plurality of grinding projections 26-42 have variable working heights. Referring now to Generally, to perform a grinding operation, the grinding wheel 10 can be rotated about the axis 24 and moved across the work-piece 12 in a grinding pass such that the grinding projections 26-42 remove material from the work-piece 12 to form grooves. The axis 24 of the grinding wheel 10 can be arranged transverse to and spaced from a centerline axis 50 of the arcuate outer surface 48. With reference to the viewing perspective of In the exemplary embodiment of the invention, the working heights of the plurality of grinding projections 26-42 can increase from the first axial end 16 to the second axial end 20. In other words, the depth of penetration into the work-piece 12 can increase with each successive grinding projection from the grinding projection 26 to the grinding projection 42. During an initial stage of processing, the grinding wheel 10 can be passed across the work-piece 12 in several different ways to create the first grooves formed in the work-piece 12. As set forth above, the grinding wheel 10 and the work-piece 12 can be moved closer to one another so that the grinding projections 26-42 increasingly penetrate the work-piece 12 during a grinding pass. Referring now to To create the first grooves formed in the work-piece 12, the relative movement between the grinding wheel 10 and the work-piece 12 can be a single pass or can be a series of passes wherein a distance between the axis 24, 50 represented by arrow 60 is steadily decreased with each pass. The initial stage of processing, by a single pass or by multiple passes, can be complete when the first grooves are formed to respective depths defined by the respective grinding projection 26-42 (shown in A second initial groove 66 shown in A third initial groove 70 shown in A fourth initial groove 74 shown in A fifth initial groove 78 shown in A sixth initial groove 82 shown in A seventh initial groove 86 shown in An eighth initial groove 90 shown in A ninth initial groove 94 shown in After the initial stage in which the first grooves 62, 66, 70, 74, 78, 82, 86, 90, 94 are formed to varying depths, the grinding wheel 10 can be applied to create more grooves and to modify and finish the first grooves 62, 66, 70, 74, 78, 82, 86, 90. The groove 94 can be finished during the initial stage. In one method for removing additional material from the work-piece 12 after the initial stage, the grinding wheel 10 can be moved to position spaced from the work-piece 12 and the work-piece 12 can be rotated about the axis 50. The work-piece 12 can be rotated an angle equal to an angle between adjacent grinding projections 26-42. The grinding wheel 10 and work-piece 12 can then be moved closer together again so that the grinding projections 26-42 can remove material from the work-piece 12. Referencing again between Similarly, the grinding projection 30 in The grinding projection 40 can both deepen and widen the groove 86 from the cross-sectional perimeter bounded by the lines 88 and 52, to cross-sectional perimeter bounded by the lines 92 and 52, removing the material represented by area 108. The grinding projection 42 can both deepen and widen the groove 90 from the cross-sectional perimeter bounded by the lines 92 and 52, to cross-sectional perimeter bounded by the lines 56 and 52, removing the material represented by area 110. The grinding projection 42 can be viewed generally as a “finishing” portion of the grinding wheel 10 and the grinding projections 26-40 can be viewed generally as “forming” and/or “groove enlarging” portions of the grinding wheel 10. The various grinding projections 26-42 can be shaped such that at least some of the grinding projections 26-42 remove substantially the same depth of material from the work-piece 12. For example, the grinding projections 26-36 can define respective truncated-triangular cross-sections with working heights increasing at a substantially constant rate along the centerline axis 24. The grinding projection 38 can also increase in height over the grinding projection 36 at the same rate as the grinding projections 26-36. The grinding projections 38-42 define respective triangular cross-sections. The working heights among the grinding projections 38-42 can change relative to one another at a decreasing rate along the centerline axis 24. Generally, the desired precision of material removal increases at the second axial end 20 of the grinding wheel 10 and thus the rate of change in working height decreases. The plurality of grinding projections 26-42 can have variable widths. The widths of the exemplary grinding projections 26-42 increase from the first axial end 16 to the second axial end 20. The widths of the grinding projections 26-38 are substantially the same size along the centerline axis 24 and increase between the grinding projections 38-42 along the centerline axis 24. Each of the grinding projections 26-38 leave a small amount of material on opposite sides of the grooves so that any misalignment between the grinding projections 26-38 is not especially problematic. After the grinding projection 38, it can be desirable to remove an even amount of material all around the groove. Most of this material can be removed by the grinding projection 40, leaving just a small amount of material. The grinding projection 42 can remove this material with a lower depth of cut than the previous the grinding projection 40 to provide a good finished surface in the groove. During the second stage of use of the exemplary grinding wheel 10, grooves are can be concurrently formed, modified and finished. Grinding can simultaneously occur in which one groove is initially-formed, other grooves are enlarged, and one groove is finished. Initially forming and finishing can occur concurrently during the initial stage as well. The final stage of processing the work-piece 12 into a finished article can be accomplished in at least two different ways in the exemplary embodiment of the invention. After all the desired grooves are formed in the arcuate surface 48 about the centerline axis 50, the grinding projection 42 will be the only grinding projection engaged with the work-piece 12, resulting in less cutting force. If this change in cutting force is sufficient to create an accuracy problem, the process can be repeated around the already-formed work-piece 12 so that all of the grooves receive a final finishing cut with only grinding projection 42 engaged. Although this adds some cycle time it is still much faster overall than conventional methods. Alternatively, a small offset between the position of the axes 24, 50 can be applied during the initial stage and second stage. This offset can be eliminated during a final stage of grinding so that, for finishing, a known amount of material will be removed from each groove. With reference to An article was formed from a work-piece using a grinding wheel according to an exemplary embodiment of the invention. The article included one hundred and twelve splines and was previously conventionally machined using a shaping process. The shaping process required to produce the article lasted two hours and was difficult to integrate on a machining center, resulting in additional operations and machines in order to achieve the desired dimensional accuracy. When the grinding wheel according to an exemplary embodiment of the invention was applied, the article was produced in twenty minutes, an eighty-three percent reduction in processing time. Also, the grinding wheel according to an exemplary embodiment of the invention could be integrated on the machining center. Alternative embodiments of the invention can be practiced to produce different articles. The benefits derived or perceived from this example may not be realized in all embodiments of the invention. Furthermore, it is noted that the benefits set forth herein are not exhaustive, other benefits may be perceived in the practice of embodiments of the invention. The benefits associated with the exemplary embodiment and described herein are not limitations of the broader invention, but rather demonstrate industrial applicability. The abrasive grains and bond of the grinding wheel 10 can be selected based on the material of the work-piece 12, the operating environment in which the grinding wheel 10 is used, or any other consideration. The exemplary grinding wheel 10 is shown generally as a single, unitary structure. However, in alternative embodiments of the invention, the grinding wheel can be a plurality of grinding wheels fixed together. Also, a grinding wheel according to an embodiment of the invention could be formed to have different grinding properties along the axis of rotation. The hardness of the grinding wheel at one axial end can be different than the hardness of the grinding wheel at the other end. For example, the grinding wheel 10 can have a bond at the first axial end 16 that allows abrasives grains to fracture easily, classified as a “soil bond”, since a soil bond will allow the grinding wheel 10 to cut into the work-piece easily. The grinding wheel 10 can have a bond at the second axial end 20 that restricts the fracturing of the abrasive grains, classified as “hard bonds”, since a harder wheel can produce finer surface finishes. While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. |