Abstract:
Some implementations of the described invention provide an improved centerless grinding apparatus in which grinding is efficiently operated by reducing the idle time of the grinding wheel. While the described apparatus can comprise any suitable feature, in some cases, it includes a first regulating wheel and a second regulating wheel are axially aligned side by side. In some cases, a first grinding area is provided between the first regulating wheel and a first blade. In some cases, a second grinding area is provided between the second regulating wheel and a second blade. Additionally, in some cases, a grinding wheel is mounted on a grinding wheel Z-slide to be moved reciprocatively between the first grinding area and the second grinding area. In this way, grinding is efficiently operated by reducing the idle time of the grinding wheel.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to centerless grinding technique in which a work is grinded without supporting the rotation axis, the work being rotationally supported on the peripheral surface thereof. More particularly, the present invention relates to an infeed centerless grinding apparatus with an improved work efficiency when a number of works are continuously grinded. 
       BACKGROUND 
       [0002]    In a centerless grinding apparatus, a work is grinded by, in a state where the work is rotationally supported on the peripheral surface thereof between a fixed blade and a rotating regulating wheel instead of being supported on the rotation axis thereof, pushing a rotating grinding wheel against the peripheral surface of the rotating work. In an infeed centerless grinding apparatus, the rotating axis of the regulating wheel is disposed in parallel with the rotating axis of the grinding wheel. 
         [0003]    In  FIGS. 7A-7B  and  FIG. 8  is shown the basic configuration of the above-described centerless grinding apparatus. 
         [0004]      FIGS. 7A and 7B  illustrate a prior art centerless grinding apparatus which comprises a grinding wheel  22  and a regulating wheel  23  mounted on a bed  21  and a blade  24  disposed so as to be opposed to and spaced from the regulating wheel  23 . While a work is rotationally supported by the rotating regulating wheel  23  and the blade  24 , the work is grinded by bringing the grinding wheel  22  into contact with the rotating work. 
         [0005]    Assuming the straight line connecting the axial center of the regulating wheel  23  and the axial center of the grinding wheel  22  on the space of  FIG. 7A , the direction of straight line, which is horizontal, is set to an X axis. 
         [0006]      FIG. 8  illustrates a partially exploded perspective view of the centerless grinding apparatus shown in  FIG. 7A . On the bed  21  is mounted a regulating wheel slide  25  which is driven by a regulating wheel slide driving mechanism  25   a  in the forward and backward directions against the grinding wheel  22 . 
         [0007]      FIG. 9A-FIG .  9 C illustrate grinding work process using a conventional centerless grinding apparatus. As shown in  FIG. 9A , a first work Wa, supported by the regulating wheel  23  and the blade  24  in the grinding area  26 , is rotated in the reverse direction with respect to the regulating wheel  23 . 
         [0008]    The regulating wheel slide  25  mounted with the regulating wheel  23  and the blade  24  is driven by the regulating wheel slide driving mechanism  25   a  to move forward and backward in the directions indicated by the f-r arrow. The regulating wheel slide  25  is moved forward (in the direction of the arrow f) to bring the work Wa into contact with the grinding wheel  22  and to be fed for cutting in the same direction. The move, contacting and feeding can be relatively operated and, for example, the grinding wheel  22  may be mounted on a slide and driven to move in the direction of the arrow r. 
         [0009]    As shown in  FIG. 9B , after the first work Wa is grinded, the regulating wheel slide  25  is moved backward in the direction of the arrow r. The first work Wa is carried out as indicated by the arrow a by an unloader  6  and a second work Wb is carried in as indicated by the arrow b by a loader  7 . 
         [0010]    As shown in  FIG. 9C , after the first work Wa in carried out (in the direction of the arrow a) and the second work Wb is carried in (in the direction of the arrow b), the second work Wb is grinded. Afterward, the series of operations as shown in  FIG. 9A ,  FIG. 9B  and  FIG. 9C  are repeatedly performed. 
       SUMMARY 
       [0011]    In the prior art centerless grinding apparatus, the grinding wheel  22  after being grinded in the operation in  FIG. 9A  is kept in a standby state while the works are replaced in the operation in  FIG. 9B . This generates an idle time until the grinding operation in  FIG. 9C  is initiated. As an example, when the grinding wheel  22  spends a grinding time of 5 seconds and an idle time of 3 seconds, the net work efficiency is 62.5% (=5/(5+3)). If the idle time is reduced to 1 second, however, the net work efficiency will be 83.3% (=5/(5+1)). 
         [0012]    The inventor sought for, as a solution to the above-described problem, an apparatus in which the time for loading and unloading the work is shortened. In the centerless grinding apparatus, however, it is required that the loader carries in a work from above the grinder in a position sufficiently distanced from the grinder because grinding area is positioned between the large-sized grinding wheel and regulating wheel. This requirement causes the loader to have high weight center and, thus, the loader becomes instable. 
         [0013]    In addition to the above, as the diameter of the work becomes small, the chucking part for chucking the work mounted on the end of the loader is required to be made small such that it causes the rigidity of the loader to be reduced. 
         [0014]    The two problems described in the above become prominent particularly in that the accuracy of positioning of the work in the grinding area is lowered due to the vibration inevitably amplified by speeding up the operation of the loader. Particularly when the work has a low weight and when the work has an unbalanced weight, positioning of the work tends to be inaccurate due to the interference of the work and the grinder caused by the effects of the coolant pressure and the wind pressure (negative pressure) generated by the grinding wheel rotating at a high speed. Every time the positioning fails, it is required to adjust the loader and in some cases even the grinder is damaged. 
         [0015]    In consideration of the above problems, it is an object of the present invention to provide a centerless grinding apparatus in which the efficiency of the grinding operation is improved by 30%. In order to achieve this purpose, the present invention proposes a novel idea that the above problems can be solved by making the grinder to be moved instead of speeding up the operation of the loader. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic plain view showing a first representative embodiment of the present invention. 
           [0017]      FIGS. 2A-2C  each depict an explanatory view showing the grinding operation in accordance with the first embodiment of the present invention. 
           [0018]      FIG. 3  is a schematic plain view showing a second representative embodiment of the present invention. 
           [0019]      FIG. 4  is a schematic plain view showing a third representative embodiment of the present invention. 
           [0020]      FIG. 5  is a schematic plain view showing a fourth representative embodiment of the present invention. 
           [0021]      FIG. 6  is a schematic plain view showing a fifth embodiment of the present invention. 
           [0022]      FIG. 7A  and  FIG. 7B  each depict a front elevation view showing a prior art centerless grinding apparatus. 
           [0023]      FIG. 8  is a partially exploded perspective view of the centerless grinding apparatus shown in  FIG. 7A . 
           [0024]      FIGS. 9A-9C  each depict an explanatory view showing the grinding operation in the prior art centerless grinding apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  is a schematic plain view which illustrates a first embodiment of the centerless grinding apparatus according to the present invention. 
         [0026]    In the centerless grinding apparatus, a grinding wheel Z-slide  13  is mounted on bed  1 . On the grinding wheel Z-slide  13  is mounted a grinding wheel  2 . In  FIG. 1 , the direction in parallel to the direction of the rotation axis  2   a  of the grinding wheel  2  is set to a Z axis and the direction orthogonal to the Z axis is set to an X axis. 
         [0027]    The grinding wheel Z-slide  13  reciprocatively moves in the direction of the Z axis as indicated by the arrow L-R. On the bed  1  is also mounted a regulating wheel slide  5 . On the regulating wheel slide  5  is mounted a first regulating wheel  9  and a second regulating wheel  10  arranged parallel in the Z direction and aligned axially with respect to each other. 
         [0028]    A first blade  41  is disposed facing the first regulating wheel  9  at a distance. The first regulating wheel  9  and the first blade  41  forms a grinding area in which a work (not shown in the figure) is supported and the work is grinded by the grinding wheel  2 . The area is hereinafter referred to as a first grinding area  11 . The regulating wheel slide  5  is fed for infeed cutting in the direction of arrow f on the X axis. 
         [0029]    Similarly, a second blade  42  is disposed facing the second regulating wheel  10  at a distance. The second regulating wheel  10  and the second blade  42  forms a grinding area in which a work (not shown in the figure) is supported and the work is grinded by the grinding wheel  2 . The area is hereinafter referred to as a second grinding area  12 . The regulating wheel slide  5  is fed for infeed cutting in the direction of arrow f on the X axis. 
         [0030]    In  FIG. 1 , as a work is carried into the second grinding area  12  to be supported thereon and the regulating wheel slide  5  is moved in the direction of the f arrow, the work is brought into the proximity of the grinding wheel  2 , thereby being grinded by the grinding wheel  2 . 
         [0031]    During this grinding operation, the grinding wheel  2  may be traversed in its axial direction (the L-R direction in the figure) while it grinds the work. This grinding operation, hereinafter referred to as oscillation grinding, results in improvement of the surface roughness of the work as the cross hatch grinding traces formed on the surface of the work provides non-oriented uniform surface finishing. 
         [0032]    After the above grinding operation is finished, the grinding wheel Z-slide  13  is moved in the direction indicated by the arrow L to be brought into such position that the grinding wheel  2  faces the first grinding area  11 . In this position, another work is carried into the first grinding area  11  and grinded. 
         [0033]    Similar to the above, oscillation grinding is operated in the first grinding area  11  by traversing the grinding wheel  2  in its axial direction (the L-R direction in the figure) while it grinds the work. This oscillation grinding operation results in improvement of the surface roughness of the work as the cross hatch grinding traces formed on the surface of the work provides non-oriented uniform surface finishing. 
         [0034]    A feature of the first embodiment of the centerless grinding apparatus that the single grinding wheel is reciprocatively moved between the first grinding area and the second grinding area so as to grind the works in two grinding areas alternately. 
         [0035]      FIG. 2-FIG .  2 C depict some explanatory views showing the grinding operation in the first embodiment of the present invention. The grinding operation according to the present invention is a continuous infeed centerless grinding processes in which numerous works are grinded in sequence. 
         [0036]      FIG. 2A  illustrates a first process in which the grinding wheel  2  in disposed facing the first grinding area  11 . A first work Wa (not shown in the figure) is readily carried into the first grinding area  11 . While the grinding wheel  2  grinds the first work Wa in the first grinding area  11 , the loader  7  carries a second work Wb into the second grinding area  12  as indicated by the arrow b. 
         [0037]      FIG. 2B  illustrates a second process in which the grinding wheel  2  is moved in the right direction of Z axis so as to grind the work Wb in the second grinding area  12 . 
         [0038]    While the grinding wheel  2  grinds the second work Wb in the second grinding area  12 , the unloader  6  carries out (in the direction of the arrow a) the first work Wa which has been grinded in the first process. Accordingly, the loader  7  carries a third work Wc into the first grinding area  11  from which the first work Wa is removed. 
         [0039]    In the above-described second process, the first work Wa is already grinded and carried out and the second work Wb is being grinded in the second grinding area  12  while the third work Wc is carried into the first grinding area  11 . 
         [0040]    The unloader  6  and the loader  7  a may be made of independent members or may be made integrally. 
         [0041]      FIG. 2C  illustrates a third process in which the grinding wheel  2  is moved in the left direction of the Z axis to be and brought into the previous position as shown in  FIG. 2A . Accordingly, the grinding wheel  2  grinds the third work We in the first grinding area  11  while the unloader  6  carries out the second work Wb out of the second grinding area  12  and the loader  7  carries therein a fourth work Wd. 
         [0042]    By repeatedly performing the second process and the third process in the above-described way, number of works are continuously grinded. 
         [0043]      FIG. 3  illustrates a second embodiment of the centerless grinding apparatus according to the present invention. In the second embodiment, an integrally-made wide width regulating wheel  14  is employed which corresponds to the two regulating wheels  9  and  10  in the first embodiment and has more than double width of the grinding wheel  2 . This wide width regulating wheel  14  allows to have two grinding areas in right and left. 
         [0044]    In the instant embodiment, the grinding wheel  2  moves forward and backward along the Z axis in the direction indicated by the arrow L-R whereas the regulating wheel slide  5  mounted with the wide width regulating wheel  14  moves forward and backward along the X axis in the direction indicated by the arrow f-r so as to perform infeed cutting. 
         [0045]      FIG. 4  illustrates a third embodiment of the centerless grinding apparatus according to the present invention. In the third embodiment, an integrally-made wide width regulating wheel  14  similar to that in the second embodiment is employed. The wide width regulating wheel  14  in the instant embodiment is different from that in the second embodiment in that it is mounted on the regulating wheel Z-slide  15  which moves forward and backward in the L′-R′ direction along with the Z axis. 
         [0046]    In the instant embodiment, the grinding wheel  2  is mounted on a grinding wheel infeed slide  16  which moves forward and backward in the f′-r′ direction along with the X axis so as to feed a work for cutting to perform infeed centerless grinding. 
         [0047]      FIG. 5  illustrates a fourth embodiment of the centerless grinding apparatus according to the present invention. In the fourth embodiment, the above-described wide width regulating wheel  14  grinds a work W having a longitude length corresponding to the width of the wide width regulating wheel  14 . With this construction, the grinding area of the wide width regulating wheel  14  can be set in the range of the width of the wide width regulating wheel  14 . This allows the grinding wheel  2  to grind the work W with different cutting amount and cutting speed in the first grinding area  11  and the second grinding area  12  respectively. 
         [0048]    In the instant embodiment, the grinding wheel  2  performs oscillation grinding and moves forward and backward in the direction of the arrow L-R along the Z axis while the regulating wheel slide  5  mounted with the wide width regulating wheel  14  moves forward and backward in the direction of the arrow f-r along the X axis so as to feed a work for cutting. 
         [0049]    Using the grinding apparatus of the instant embodiment, it is possible to grind a long work efficiently without necessitating it to use two or more grinding apparatus or to change the set up of the grinding operation. 
         [0050]      FIG. 6  illustrates a fifth embodiment of the centerless grinding apparatus according to the present invention. In the fifth embodiment, the above-described wide width regulating wheel  14  in the third embodiment grinds a work W having a longitude length corresponding to the width of the wide width regulating wheel  14 . The grinding wheel  2  grinds the work W with different cutting amount and cutting speed in the first grinding area  11  and the second grinding area  12  respectively. 
         [0051]    In the instant embodiment, the grinding wheel  2  is mounted on a grinding wheel infeed slide  16  which moves forward and backward in the f′-r′ direction along with the X axis so as to feed a work for cutting to perform infeed centerless grinding. 
         [0052]    The wide width regulating wheel  14  performs oscillation grinding and the regulating wheel slide  15  mounted with the wide width regulating wheel  14  moves forward and backward in the direction of the arrow L′-R′ along the Z axis while the grinding wheel  2  moves forward and backward in the direction of the arrow f′-r′ along the X axis so as to feed a work for cutting. 
         [0053]    Using the grinding apparatus of the instant embodiment, it is possible to grind a long work efficiently without necessitating it to use two or more grinding apparatus or to change the set up of the grinding operation. 
         [0054]    In the centerless grinding apparatus according to the present invention, a single grinding wheel moves reciprocatively among two grinding areas. While the grinding wheel grinds a work in one grinding area, works are replaced in preparation for the next grinding process on the other grinding area where the grinding wheel is not present. This operation improves the substantial efficiency of the grinding processes because the idle time during replacement of the works is reduced. 
         [0055]    In the centerless grinding apparatus according to the present invention, it is possible to grind a long work efficiently without necessitating it to use two or more grinding apparatus or to change the set up of the grinding operation. 
         [0056]    It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to one skilled in the art without departing from the scope of the present invention. For example, the driving mechanism of the grinding wheel slide may be flexibly designed as long as it does not impair the an element of the present invention that one or both of the regulating wheel slide and the grinding wheel slide is moved in the axial direction thereof such that the grinding wheel is reciprocatively moved relative to two grinding areas.