Shaving cutter
United States Patent Taniguchi et al.  
 [ SHAVING CUTTER [75] inventors: Hiroshi Taniguchi, Kakogawa&#39;.  
 Toshikazu Yokoyama, Akashi, both of Japan [73] Assignee: Kobe Steel, Ltd., Kobe,Japan [22] Filed: Oct. ll, I973 [2|] Appl. No.: 405,737  
 [30] Foreign Application Priority Data Oct. [2. I972 47-lU2l05 [52] US. Cl 29/95; 29/103; 29/103 B; 90/|.6 A [5|] Int. Cl 826d 1/12; 823p l5/28 [58] Field of Search 29/103, 103 B, 95; JO/1.6 A  
 [56] References Cited UNITED STATES PATENTS 2,329.284 9/l943 Mentley 29/103 Apr. 8, 1975 [57] ABSTRACT A shaving cutter includes cutting teeth each being formed with lands and grooves in the opposite faces thereof; the lands providing cutting edges for a shaving operation and including two types of lands. One type of land being cut off substantially in an addendum region thereof and the other being cut off substantially in a dedendum region thereof. The cut off portion of the land being so arranged that it does not engage in the shaving operation, whereby the cutting face area is reduced so as to increase the depth of the cut, thus obtaining various advantages such as reduction of frictional distance, wear of the cutting edge, improved precision of shaving, shortening of the period of the cutting process, and the like.  
 8 Claims, 9 Drawing Figures SHAVING CUTTER BACKGROUND OF THE INVENTION l. Field of the Invention:  
  This invention relates to a shaving cutter and more particularly to a shaving cutter for shaving or finish cutting a gear.  
 2. Description of the Prior Art:  
  The shaving of a gear by a shaving cutter provided with helically arranged cutting edges is generally done by arranging a shaving cutter a and a gear b to be shaved in a skewed relationship with a crossing angle 8 of both axes, as shown in FIG. 1, so that the gear and the shaving cutter mesh with each other and drive the shaving cutter. In this prior art case, the gear is driven by the shaving cutter in a meshing manner, and furthermore, according to the conventional shaving method, the gear is moved in its axial direction D such that shaving is applied over the entire width of the gear.  
  The conventional shaving cutter includes a plurality of cutting teeth arranged helically therearound, one of which is shown in FIG. 2. As shown in FIG. 2, a tooth l is formed with a plurality of equidistantly spaced lands 2 each being arranged in a plane substantially perpendicular to the axis of the tooth and separated from adjacent lands by a groove 3 to define a cutting edge 4 extending over the addendum and dedendum portions of the tooth. Therefore, the tooth of this kind is adapted to perform shaving at both faces thereof at the same time and over the entire extension of each cutting edge. However, when the shaving is done by using a shaving cutter having a cutting tooth as shown in FIG. 1, especially when a gear is shaved with a small crossing angle B of the axis of the shaving cutter and the gear to be shaved as in the case of a shoulder gear, a large contacting surface exists between the shaving cutter and the gear, or more precisely, between the land portions 2 and the faces of the gear. In this case, the contact pressure is lower so that even when a predetermined infeed is applied to the shaving cutter, the cutting edge does not sufficiently cut into the face surface of the gear, thus reducing the amount of shaving and elongating the time required for accomplishing a predetermined amount of shaving. Therefore, the productivity of the shaving process is lowered. On the other hand, if the working pressure applied to the shaving cutter is increased to obtain an expected cutting amount, elastic deformation is caused in a mandrel holding the gear or in the gear itself, whereby the precision of finishing the face of the gear is very much deteriorated.  
 SUMMARY OF THE INVENTION Therefore, it is a primary object of this invention to reduce the contacting surface between the shaving cutter and the gear thereby to increase the contacting surface pressure therebetween, and thus to increase the depth of cut of the cutting edge of the shaving cutter into the face of the gear to be shaved.  
  Another object of this invention is to reduce the frictional distance of the cutting edge over the face of the gear by improving the depth of cut performance of the shaving cutter and by generating relatively thick chips, and thereby to suppress the wear of the cutting edge to a minimum and to elongate the life of the shaving cutter.  
  Still another object is to improve the precision of finishing the face of the gear by making uniform the contacting pressure between the shaving cutter and the gear in the contacting region over the entire process of shaving.  
  These and other objects are accomplished, according to this invention, by a shaving cutter comprising cutting teeth each being formed with lands and grooves in opposite faces thereof, the lands providing cutting edges to perform the shaving operation, wherein the lands include two types of lands, one being cut off substantially in an addendum region thereof and the other being cut off substantially in a dedendum region thereof, the cut off portion of the land being adapted not to engage in the shaving operation.  
  By preparing the lands of the cutting teeth formed with cut-off portions adapted not to engage in the cutting operation over substantially half the land, the contacting surface between the lands and the face of the gear is reduced to substantially half that in the conventional shaving cutter, whereby the contacting surface pressure in the shaving operation is doubled, and as a result, there are accomplished various improvements such as favorable depth of cut performance, reduction in wear of the cutting edge and accordingly an elongated life of the shaving cutter, increased shaving amounts accompanied by higher precision of shaving as well as shortening of the period of the shaving process. Furthermore, according to this invention, the contacting surface pressure in the shaving operation is uniforrnalized over the entire region of shaving by properly arranging the lands formed with the cut-off portions in two types according to particular configurations of the gears to be worked, whereby the precision of the shaving process is substantially improved.  
  In a simple arrangement of the lands according to this invention, the lands formed with the cut-off portions are arranged symmetrically on opposite faces of a cutting tooth. Regarding each face of the cutting tooth, the cut-off portions are arranged alternately in an addendum or dedendum region so that in the shaving operation each adjacent pair of lands operate in combination as if they constitute a conventional complete land.  
  According to a modification of this invention, the alternate arrangement of the cutting portions in the addendum or dedendum region is reversed with respect to the opposite faces of the cutting tooth.  
  According to a further modification, the lands formed with the cutting portions according to this invention may be arranged in a properly mixed manner together with the conventional complete lands wherein the complete lands may be positioned at the leading or trailing end of the cutting tooth or may be arranged alternately or in every third or fourth position with the lands formed with the cut-off portions according to this invention.  
  The features of the arrangements as mentioned above may be symmetrically reversed with respect to the cutting teeth arranged in series along a helical line, alternately, or in other proper exchanging manner in order to obtain a required uniformalization of the shaving process.  
 BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features and advantages of this invention will be more fully appreciated as the same becomes better understood from the following detailed description when considered in connection with the accompanying drawings, wherein like reference characters designate like or corresponding parts throughout the several figures;  
  FIG. 1 is a schematical view showing the relation of a shaving cutter in shaving operation and a gear to be shaved;  
  FIG. 2 is a perspective view showing a cutting tooth of a typical conventional shaving cutter;  
  FIG. 3 is a perspective view of a cutting tooth formed with lands arranged according to a fundamental embodiment of this invention;  
  FIG. 4 is a view in a perspective manner for illustrating the meshing relation between a gear to be shaved and the cutting tooth shown in FIG. 3&#39;,  
 FIG. 4A is a section along line AA in FIG. 4; and  
  FIGS. 5 8 show various modifications of the arrangement of the lands according to this invention with respect to a particular cutting tooth in a perspective manner.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 3, which shows a typical cutting tooth of a shaving cutter according to this invention, wherein a cutting tooth 10 arranged along the periphery of a shaving cutter C has a shape generally defined by enveloping surfaces 11 and 12 which also define the cutting faces of the cutting tooth. The cutting faces are cut off to form a plurality of equidistantly spaced grooves 14 each extending from the addendum to dedendum ends of the cutting tooth thereby to define lands 15 left therebetween. Each land is adapted to present cutting edges along opposite edges thereof. Of these lands, a land designated by reference numeral 15a is cut off in a region extending substantially from a middle portion of the phase to the addendum end to present a substantially flat relief portion 16 adapted not to engage in the shaving operation. To the contrary, a land designated by reference numeral 15b has a portion thereof cut off in the same manner but to present a relief portion 17 in a region extending substantially from a middle portion thereof to the dedendum end. Although the relief portions 16 and 17 are cut off along a plane, in the shown embodiment, they may be cut off along any curved surface.  
  The shaving operation of the cutting tooth shown in FIG. 3 is illustrated in FIG. 4. As shown in this figure, the shaving cutter C, having the cutting tooth 10, is firmly meshed with a gear G to be shaved and is forcibly rotated in the direction of arrow E, whereby shaving is performed during the meshing rotation. The gear G rotates following the rotation of the shaving cutter C and at the same time is transferred in the direction of its axis as in the conventional shaving process so as to apply the shaving to the entire surface extending over the width thereof. When the shaving cutter C and the Gear G are meshed with each other, as shown in FIG. 4, the lands 15 of the shaving cutter contact the face of the gear within a region defined by phantom lines L. However, since the lands 15b are formed with cut off portions 17 in their dedendum portions, the lands 15b do not come in contact with the face 6! of the gear. Thus, in this case, the area of the contacting surface between the shaving cutter and the gear is reduced by substantially a half as compared with the case of employing the conventional shaving cutter, as shown in FIG. 2, and accordingly, the contacting pressure per unit area in the shaving operation is doubled. Thus, the depth of cut performance of the cutting edges into the face of the gear is very much improved.  
  As the shaving cutter C rotates from the position shown in FIG. 4, the cutting edge of the land 15a slides with respect to the gear face Gl along a route R determined by a sliding component Ge in the direction of tooth contour and a sliding component G2 in the direction of gear space while applying the shaving action to the face of the gear. As the cutting operation proceeds from the condition shown in FIG. 4, the contacting region L moves toward the tip of the gear G. In this case, the addendum portion of the gear face Gl is shaved by the cutting edges of the lands 15a, while in the former half period of shaving of the gear face G1, the dedendum portion of the gear face is shaved by the cutting edges of the lands 15b. Therefore, by properly arranging the effective cutting edge portions of the lands 15a and 15b, the shaving of the gear face in the dedendum region by the lands 15b is continuously succeeded by the shaving in the addendum portion by the lands 15a. By the provision of the cut off relief portions 16 and 17, the shaving depth by the lands 15a and 15b is increased to be twice as much as compared with the conventional shaving cutter, whereby in case of shaving a same pre determined amount, the frictional distance over the face of the gear by the cutting edge of the land is sub stantially reduced when performed by the cutter according to this invention as compared with the conventional shaving cutter. Due to the reduction of the frictional distance, the wearing of the shaving cutter is correspondingly reduced and the life of the shaving cutter is elongated.  
  With respect to the opposite face G2 of the gear, the same shaving action is applied except that in this case the direction of progress of the shaving action is reversed, i.e., the addendum portion of the gear face G2 is first shaved by the lands 15a and then the dedendum portion is shaved by the lands 15b. When the direction of the meshing rotation of the shaving cutter and the gear is reversed at the end of the shaving action in one direction, the entire shaving operation is of course reversed as a whole.  
  FIG. 5 shows a second embodiment of the shaving cutter according to this invention, wherein the arrangements of the lands at the opposite faces of the cutting tooth are reversed with respect to each other.  
  In more detail, in FIG. 5, wherein the portions corresponding to those in FIG. 3 are designated by the same reference numerals, the face confronting the observer is formed with the lands 15a and 15b arranged in the same manner as in the cutting tooth shown in FIG. 3. The opposite face averted away from the observer is formed with lands at the positions where the lands 15b are formed in the cutting tooth shown in FIG. 3 and the lands 15b at the positions where the lands 150 are formed in the cutting tooth shown in FIG. 3. However, it will be understood that the shaving cutter shown in FIG. 5 operates in substantially the same manner as the one shown in FIG. 3.  
  FIG. 6 shows a third embodiment of this invention, wherein several complete lands 150 as in the conventional shaving cutter are combined with the lands 15a and 15b formed with the cut off relief portions according to this invention. By the provision of the complete land 15c, the meshing rotation of the shaving cutter and the gear is favorably controlled due to the improved guiding action by the complete land [50, whereby precision of the contour of the shaved gear is improved. An additional advantage of providing the complete lands [Se is that in manufacturing the shaving cutter the measurement of the tooth contour is made easier. In HO. 6, the other portions corresponding to those shown in FIGS. 3 and 5 are designated by the same reference numerals.  
  Substantially, the same advantages as obtained by providing the complete lands c at the leading and trailing edges of the tooth, as shown in FIG. 6, are obtained by arranging the complete lands 15c combined alternately with the lands 15a and 15b as shown in FIG. 7. Also in FIG. 7, the portions corresponding to those shown in FIGS. 3, 5 or 6 are designated by the same reference numerals.  
  F IG. 8 shows a further embodiment of this invention, wherein the face of the cutting tooth l0 confronting the observer is formed with the lands 15a and 15b substantially in the same manner as in the tooth shown in FIG. 3, while the other face averted from the observer is formed with the conventional complete lands 15c over the entire extent thereof. Such an unsymmetrical arrangement of the lands is favorably adapted to compensate the difference in shaving pressure in opposite faces of the cutting tooth for the difference in pressure acting in the driving face and the driven face in the driving operation of the shaving cutter when meshing with the gear. In other words, when shaving is done while the gear is rotated by using driven by the shaving cutter meshing therewith, the contacting pressure in the face of the driving side is different from that of the driven side, whereby if the area of the contacting surface is the same on the opposite faces of the cutting tooth, the cutting pressures acting per unit area on opposite faces of the gear are different from each other. Therefore, uniform shaving performance is not effected on both faces of the gear. By employing the cutting tooth as shown in FIG. 8 formed with lands properly arranged to be unbalanced with respect to the opposite faces thereof, the above-mentioned imbalance of the cutting pressure acting per unit area is compensated for and uniform shaving is effected on both faces of the gear. Also, in FIG. 8, the portions corresponding to those shown in the preceeding figures are designated by the same reference numerals.  
 Here it is to be noted that the application of the idea of this invention is not limited to any one of the shaving methods such as conventional, diagonal, underpass, branch cut, etc., and that this invention may be applied in various manners according to the particular conditions of design without departing from the spirit of this invention.  
  What is claimed as new and desired to be secured by Letters Patent of the United States is:  
  l. A shaving cutter comprising cutting teeth each being formed with lands and grooves in opposite faces thereof, said lands providing cutting edges to perform the shaving operation, said lands includes two types of lands, one being cut off substantially in an addendum region thereof and the other being cut off substantially in a dedendum region thereof, said cut-off portion of said land being adapted not to engage in the shaving operation.  
  2. A shaving cutter according to claim 1, wherein said two types of lands are arranged alternately in one face of the cutting tooth.  
  3. A shaving cutter according to claim 1, wherein the arrangement of the two types of lands is symmetrical regarding the opposite faces of the cutting tooth in a manner that one type of land formed in one face is backed by the same type of land formed in the opposite face.  
  4. A shaving cutter according to claim 1, wherein the arrangement of the two types of lands is reversed re garding the opposite faces of the cutting tooth in a manner that one type of land formed in one face is backed by the other type of land formed in the opposite face.  
  5. A shaving cutter according to claim 1, wherein the cutting off of the cut-off portion is formed substantially along a plane.  
  6. A shaving cutter according to claim 1, wherein said lands include a third type of land presenting complete cutting edges without said cutoff portion.  
  7. A shaving cutter according to claim 6, wherein said third type of complete lands are provided at the leading and the trailing edges of the cutting tooth.  
  8. A shaving cutter according to claim 6, wherein said third type of land presenting complete cutting edges is arranged on one face of said cutting tooth and said two types of lands are arranged on the opposite face of said cutting tooth.