Abstract:
A blanked plate-like metal member for use as an element of a belt in a continuously variable transmission has an recess including an undercut therein. A stream of a liquid mixed with particle members is ejected toward an edge to be beveled of the recess thereby to bevel the recess. After the edge is beveled by deburring the edge, the recess is finished by removing a bulge formed on an outer surface of the edge by deburring the edge.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of beveling a plate-like metal member. 
     2. Description of the Related Art 
     Plate-like metal members to be beveled include elements of a belt for use in continuously variable transmissions, for example. As shown in FIG. 5 of the accompanying drawings, an element  1  of such a transmission belt comprises a body  2  for contacting a pulley of a continuously variable transmission (not shown), and a head  4  joined to the body  2  by a narrow neck  3 . The element  1  is blanked out of a metal plate (not shown). The body  2  has a pair of symmetrical saddles  5 , and the head  4  has a pair of ears  6  spaced respectively, from the saddles  5  with gaps therebetween. The element  1  includes undercuts  3   d  defined at upper and lower ends of the neck  3 . A pair of laminated rings  8  each comprising a stack of metal sheet rings  7  is held in engagement with the respective saddles  5 . Although not shown, the transmission belt comprises an annular array of stacked elements  1  that are held together in an annular shape by the laminated rings  8 . 
     If the neck  3  of the element  1  has sharp edge corners  3   a  or is burred at edge corners  3   a  when the element  1  is blanked, then the metal sheet rings  7  tend to be damaged by contact with the neck  3 . To avoid such damage, it has been customary to deburr and bevel the edge corners  3   a  of the neck  3 . 
     It is known in the art that, as shown in FIG. 6 of the accompanying drawings, a rotating grinding belt  60  is held in sliding contact with the edge corners  3   a  of the neck  3  of the element  1  to deburr and bevel the edge corners  3   a  of the neck  3 . 
     According to the known process, each element  1  is supported on a rotary disk  61 , and rotated thereby while the edge corners  3   a  of the neck  3  are being held against the grinding belt  60 . As shown in FIG.  7 ( a ) of the accompanying drawings, the grinding belt  60  passes between an upper edge  5   a  of one of the saddles  5  and a lower edge  6   a  of the corresponding ear  6  into abutment against the neck  3 . Therefore, the width of the grinding belt  60  is of such dimension that it can pass between the upper edge  5   a  of the saddle  5  and the lower edge  6   a  of the ear  6 . 
     However, if the upper edge  5   a  of the saddle  5  is slightly arcuate in shape, then the distance e between the crest of the upper edge  5   a  of the saddle  5  and the lower edge  6   a  of the ear  6  is relatively small, and a range f of the neck  3  which is beveled by the grinding belt  60  having passed through the distance e is smaller than a range g of the neck  3  which is held in contact with the metal sheet rings  7  of the laminated ring  8 . Specifically, the rings  7  of the laminated ring  8  engaging the saddle  5  slide along an extension h (see FIGS.  7 ( a ) and  7 ( b )) of the upper edge  5   a  of the saddle  5  into abutting engagement with the neck  3 , as shown in FIG.  7 ( b ) of the accompanying drawings. At this time, a lower one of the rings  7  abuts against a range i outside of the beveled range f. Therefore, the conventional beveling process using the grinding belt  60  fails to bevel the entire range g of the neck  3  which is contacted by the laminated ring  8 . As a result, the rings  7  are not fully protected against damage because they tend to contact the range i of the neck  3  where burrs and sharp edge corners remain unremoved. 
     According to the conventional beveling process using the grinding belt  60 , furthermore, as shown in FIG. 6, the elements  1  supported on the rotary disk  61  are beveled one by one. Consequently, a large number of elements  1  are beveled with poor efficiency in a prolonged period of time. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a method of beveling a plate-like metal member at a predetermined position thereof reliably and efficiently. 
     According to the present invention, there is provided a method of beveling a blanked plate-like metal member having an recess including an undercut therein, comprising the step of ejecting a stream of a liquid mixed with particle members toward an edge to be beveled of the recess thereby to bevel the recess. 
     When the stream of the liquid mixed with particle members is ejected toward the edge to be beveled of the recess including the undercut, the particle members collide with the edge to be beveled, polishing, removing burrs from, and beveling the edge of the recess. 
     The particle members have such directivity that they collide accurately with the recess in the plate-like metal member. Therefore, the recess can reliably be beveled even if it is located in a relatively narrow region. When the particle members collide with the edge to be beveled, they impart a residual stress in the edge, thereby increasing the mechanical strength of the edge. 
     The plate-like metal member may comprise an element of a belt for use in a continuously variable transmission. A plurality of such elements are stacked in an annular form and held together by sheet rings, providing the transmission belt. The element comprises a body for contacting a pulley of the continuously variable transmission, and a head joined to the body by a narrow neck, the body having a saddle engageable by the sheet rings, the head having an ear spaced from the saddle with a gap therebetween. The recess is defined by an upper edge of the saddle, a side edge of the neck, and a lower edge of the ear. The stream is ejected toward the edge to be beveled which extends in a range between a point of intersection between the side edge of the neck and an extension of the lower edge of the ear and a point of intersection between the side edge of the neck and an extension of the upper edge of the saddle. 
     Since the particle members are ejected with directivity, they can collide accurately with a point of intersection between the side edge of the neck and the extension of the upper edge of the saddle. The particle members can therefore reliably deburr and bevel the edge to be beveled which extends in the range between the point of intersection between the side edge of the neck and the extension of the lower edge of the ear and the point of intersection between the side edge of the neck and the extension of the upper edge of the saddle, which range would be contacted by the sheet rings on the side edge of the neck. Therefore, the sheet rings are reliably prevented from damage by contact with the neck. Furthermore, because the mechanical strength of the neck is increased by the residual stress that has been developed in the neck by the impinging particle members, the neck is further protected against damage by contact with the neck. 
     After the edge is deburred thereby to bevel the recess, the recess is finished by removing a bulge formed on an outer surface of the edge by deburring the edge. Therefore, the recess is given a highly accurate beveled shape. The recess may be finished by barrel polishing. 
     A stack of the plate-like metal members may be moved in a direction along the stack while recesses in the plate-like metal members are being exposed to one side, and the stream may be ejected toward edges to be beveled of the recesses thereby to bevel the recesses. Therefore, many plate-like metal members can be beveled simultaneously with increased efficiency. If the plate-like metal members comprise elements of a belt for use in a continuously variable transmission, then the stack of elements may be moved in a direction of the stack, and the stream may be ejected toward edges to be beveled of the recesses thereby to bevel the recesses. Consequently, may elements can be beveled simultaneously with increased efficiency. 
     At this time, the stream may be ejected toward edges to be beveled on one diagonal line of the neck of a stack of the elements to bevel the edges while moving the stack of elements in a direction along the stack, then the stack of elements may be turned 180° about an axis along the direction, and the stream may be ejected toward edges to be beveled on the other diagonal line of the neck of the stack of the elements to bevel the edges while moving the stack of elements in the direction along the stack. In this fashion, the four edge corners of a pair of recesses defined in each element can efficiently be beveled. 
     The particle members may be made of a material selected from the group consisting of glass, alumina, steel, cast iron powder, and zirconia. The particle members made of the above material are mixed with the liquid, and the stream of the liquid is ejected to the edge to be beveled. Since the particle members collide accurately with the edge to be beveled because of the directivity they have, the edge can be beveled well. 
     The particle members may be crushed upon collision with the edge to be beveled. The particle member that can be crushed upon collision with the edge to be beveled may comprise glass beads. The glass beads are broken by the impact at the time they collide with the edge. The fragments of the glass beads thus broken are pressed again against the edge by the stream of the liquid for reliably and efficiently beveling the edge. 
     The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate a preferred embodiment of the present invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of an apparatus used to carry out a method of beveling a plate-like metal member according to the present invention; 
     FIG. 2 is a fragmentary view showing a portion of an element as a plate-like metal member to be beveled by the method according to the present invention; 
     FIG. 3 is an enlarged fragmentary perspective view, partly broken away, of an edge of a neck of the element shown in FIG. 2; 
     FIG.  4 ( a ) is a fragmentary cross-sectional view of an edge corner of the neck; 
     FIG.  4 ( b ) is a fragmentary cross-sectional view of the edge corner of the neck as it is beveled; 
     FIG.  4 ( c ) is a fragmentary cross-sectional view of the edge corner of the neck as it is finished; 
     FIG. 5 is a front elevational view of an element; 
     FIG. 6 is a schematic view of an apparatus used to carry out a conventional method of beveling a plate-like metal member; 
     FIG.  7 ( a ) is a fragmentary view showing a portion of the element shown in FIG. 6 which is beveled by the conventional method; 
     FIG.  7 ( b ) is a fragmentary view showing the portion of the element shown in FIG. 7 that is poorly beveled and tends to damage a laminated ring. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An element  1  of a belt for use in continuously variable transmissions, as a plate-like metal member to be beveled, will first be briefly described below with reference to FIG.  5 . The element  1  is blanked out of a metal plate, and comprises a body  2  and a head  4  joined to the body  2  by a narrow neck  3 . The body  2  has a pair of symmetrical saddles  5 , and the head  4  has a pair of ears  6  spaced respectively from the saddles  5  with gaps therebetween. The element  1  includes undercuts  3   d  defined at upper and lower ends of the neck  3 . The transmission belt comprises an annular array of stacked elements  1  that are held together in an annular shape by a pair of laminated rings  8  each comprising a stack of metal sheet rings  7 . The laminated rings  8  are held in engagement with the respective saddles  5 . 
     According to the illustrated embodiment of the present invention, the neck  3  of the element  1  is beveled. FIG. 1 shows a beveling apparatus  9  used to carry out a method of beveling a plate-like metal member according to the present invention. The beveling apparatus  9  comprises a rotatable holding means  10  for holding a stack of elements  1  and a rotating means  11  for rotating the holding means  10 . The holding means  10  is movable back and forth in the direction along which the elements  1  are stacked, by a displacing means (not shown). The beveling apparatus  9  includes a pair of ejection nozzles  12  disposed one on each side of the holding means  10 . As shown in FIGS. 2 and 3, each of the ejection nozzles  12  ejects a stream of water  14  mixed with glass beads  13  as particle members toward the neck  3  of the element  1  that is held by the holding means  10 . As shown in FIG. 1, each of the ejection nozzles  12  is inclined to the neck  3  of each of the stacked elements  1 . 
     For beveling the neck  3  of the element  1  with the beveling apparatus  9 , a stack of elements  1  are held by the holding means  10 , as shown in FIG.  1 . Then, the stream of water  14  mixed with glass beads  13  are ejected from each of the ejection nozzles  12  toward the neck  3  of each of the elements  1 , while at the same time the holding means  10  is moved in the stacked direction of the elements  1  by the displacing means. In this manner, the elements  1  held by the holding means  10  are deburred and beveled in a relatively short period of time. 
     Since the glass beads  13  ejected from each of the ejection nozzles  12  have directivity, the glass beads  13  can be oriented to pass accurately between the ear  6  and the saddle  5  of the element  1  and applied accurately to an edge corner  3   a  of the neck  3 , as shown in FIG.  2 . Furthermore, the glass beads  13  can be applied accurately to a region of the neck  3  with which the rings  7  of the laminated ring  8  engaging the saddle  5  possibly slide along the extension h of the upper edge  5   a  of the saddle  5  into abutting engagement, i.e., a point j of intersection between the edge corner  3   a  of the neck  3  and the extension h of the upper edge  5   a,  as shown in FIG.  2 . 
     More specifically, as shown in FIG. 3, the stream of water  14  and the glass beads  13  ejected from the ejection nozzles (see FIG. 1) collide with the edge corner  3   a  of the neck  3 , and fragments  15  of the glass beads  13  which are broken upon collision are pressed again against the edge corner  3   a  of the neck  3  by the stream of water  14 . In the illustrated embodiment, the glass beads  13  have a diameter of 0.1 mm, and the stream of water  14  is ejected under a pressure of about 200 Mpa. The elements  1  are moved at a speed of 500 mm/min. by the displacing means, and the distance from the ejection nozzle  12  to the edge corner  3   a  of the neck  3  is 50 mm. 
     As a result, a burr  3   b  (see FIG.  4 ( a )) on the edge corner  3   a  of the neck  3  is ground off by the glass beads  13  and their fragments  15 , as shown in FIG.  4 ( b ), thus beveling the edge corner  3   a  of the neck  3  leaving a small bulge  3   c  on the surface of the neck  3 . Since a residual stress is developed in the edge corner  3   a  of the neck  3  thus beveled by collision with the glass beads  13 , a beveled surface of high mechanical strength is produced on the edge corner  3   a  of the neck  3 . 
     As shown in FIG. 2, each of the ejection nozzles  12  faces a point p of intersection between the edge corner  3   a  of the neck  3  and an extension k of the lower edge  6   a  of the ear  6 . Since the ejection nozzle  12  can apply the glass beads accurately to the point p of intersection, the edge corner  3   a  of the neck  3  can be deburred and beveled in a relatively wide range g between the points j, p of intersection. 
     As shown in FIG. 1, the ejection nozzles  12  are oriented to face the respective edge corners  3   a  on one diagonal line of the neck  3  of each of the stacked elements  1  held by the holding means  10 . After the edge corners  3   a  on one diagonal line of the neck  3  have been beveled by the respective ejection nozzles  12 , the elements  1  are turned 180° about the axis of the stack by the rotating means  11  through the holding means  10  to bring the edge corners  3   a  on the other diagonal line of the neck  3  into facing relationship to the respective ejection nozzles  12 . The edge corners  3   a  on the other diagonal line of the neck  3  can now be beveled by the respective ejection nozzles  12 . 
     After the edge corners  3   a  of the necks  3  of the elements  1  are beveled, the elements  1  are detached from the holding means  10 . The elements  1  are then finished by barrel polishing. As a consequence, the elements  1  from which the bulge  3   c  has been removed from the surface of the neck  3  and which are hence highly accurate in dimensions are produced. 
     In the illustrated embodiment, the glass beads  13  are employed as particle members. However, particle members may be made of alumina, steel, cast iron powder, ceramics such as zirconia, etc. 
     The method according to the present invention been described as being applied to beveling elements of belts for use in continuously variable transmissions. However, the method according to the present invention is also applicable to beveling other plate-like metal members having recesses defined by edges that need to be beveled. 
     Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.