CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. national stage application of PCT/JP2008/073494 filed on Dec. 24, 2008, and claims priority to, and incorporates by reference, Japanese Patent Application No. 2007-337779 filed on Dec. 27, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a blade member used, for example, in a razor, and an apparatus for working the edge of the blade member. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventionally, the edge of this type of blade member is worked with a razor strop to remove burrs. This reduces the sharpness of the edge and degrades the cutting quality. Also, the hardness and rigidity of the edge are reduced. 
       Patent Document 1: Japanese Examined Patent Publication No. 54-28379 
     Patent Document 2: Japanese Laid-Open Patent Publication No. 2007-61212 
     DISCLOSURE OF THE INVENTION 
       [0004]    According to the technique disclosed in Patent Document 1, a cutting blade is subjected to ion implantation to improve the hardness. According to the technique disclosed in Patent Document 2, an edge is subjected to reactive-ion etching to increase the sharpness. 
         [0005]    Accordingly, it is an objective of the present invention to provide a blade member having a superior edge by improving the processing techniques of ion beam treatment and plasma ion implantation, and a working apparatus capable of efficiently working such edges. 
         [0006]    In accordance with a first aspect of the present invention, a blade member is provided in which edges of a group of blades are subjected to ion beam treatment using a plasma ion gun in a vacuum chamber, in which argon is used as a medium. The pressure of the argon gas is 0.1 to 1 Pa, a bias voltage applied to the blade group is 0.1 to 1000 V, and the processing time is 5 to 300 minutes. This increases the sharpness of the edge, so that the cutting quality is enhanced. 
         [0007]    In accordance with a second aspect of the present invention, a blade member is provided, in which, in a vacuum chamber, edges of a group of blades, of which the edge angle is 10 to 35 degrees and the height of burr is 0.1 to 10 μm, are subjected to plasma ion implantation of nitrogen plasma using a plasma ion implantation gun, and thereafter, the edges are subjected to ion beam treatment using a plasma ion gun, in which argon is used as a medium. 
         [0008]    Accordingly, the ion beam treatment is performed in the same vacuum chamber subsequent to the plasma ion implantation, thereby working the edge efficiently. This allows the rigidity to be increased while leaving a hardened layer on the edge. Also, the entire edge line of the edge  11  is uniformly finished, so that the cutting quality is enhanced. The plasma ion implantation and the subsequent ion beam treatment may be repeated. 
         [0009]    In accordance with a third aspect of the present invention, a blade member is provided in which edges of a group of blades are subjected to ion beam treatment using a plasma ion gun in a vacuum chamber, in which argon is used as a medium. The ion beam treatment is performed to a depth of 0.1 to 1.5 μm from the pointed end of the edge and to a depth of 0.1 to 1.5 μm in the direction of the thickness of the edge. This increases the sharpness of the edge  11 , so that the cutting quality is enhanced. 
         [0010]    In accordance with a fourth aspect of the present invention, a blade member is provided in which, in a vacuum chamber, a plurality of blade groups, each of which is formed by laminating a plurality of blades in a horizontal direction and passing a skewer through the blades, are caused to rotate while orbiting relative to each other. The edges are subjected to ion beam treatment using a plasma ion gun, in which argon is used as a medium. In this case, each blade group spins while orbiting about the plasma ion gun. Thus, ion beam treatment is evenly performed on the entire blade. Therefore, the sharpness of the entire edge is averagely increased, so that the cutting quality is enhanced. 
         [0011]    In accordance with a fifth aspect of the present invention, an edge working apparatus for a blade member is provided that includes, in a vacuum chamber, a rotating body and a plurality of plasma ion guns arranged in parallel. The rotating body causes a plurality of blade groups, each of which is formed by laminating a plurality of blades and passing a skewer through the blades, to rotate while orbiting. The edges of each blade group are subjected to ion beam treatment using the plasma ion guns, in which argon is used as a medium. In this case, each blade group spins while orbiting about the plasma ion gun. Thus, ion beam treatment is evenly performed on the entire blade group. 
         [0012]    In accordance with a sixth aspect of the present invention, a blade member is provided in which edges of a group of blades are subjected to ion plasma implantation of nitrogen plasma using a plasma ion implantation gun in a vacuum chamber, in which the pressure of the nitrogen is 0.5 to 5 Pa, a bias voltage applied to the blade group is 0.1 to 1000 V, a filament current is 100 to 200 A, and the processing time is 10 to 1000 minutes. In this case, the hardness of the edge is increased so that the rigidity is enhanced. 
         [0013]    In accordance with a seventh aspect of the present invention, a blade member is provided in which, in a vacuum chamber, edges of a group of blades, of which the edge angle is 10 to 35 degrees and the height of burr is 0.1 to 10 μm, are subjected to ion beam treatment using a plasma ion gun, in which argon is used as a medium, and thereafter, the edges are subjected to plasma ion implantation of nitrogen plasma using a plasma ion implantation gun. In this case, the edge is worked efficiently by sequentially performing the ion beam treatment and the plasma ion implantation in the same vacuum chamber, so that a sufficient hardened layer is formed on the entire edge to improve the rigidity. The ion beam treatment and the subsequent plasma ion implantation may be repeated. 
         [0014]    In accordance with an eighth aspect of the present invention, a blade member is provided in which edges of a group of blades are subjected to plasma ion implantation of nitrogen plasma using a plasma ion implantation gun in a vacuum chamber. The plasma ion implantation is performed to a depth of 0.1 to 1.5 μm from the pointed end of the edge and to a depth of 0.1 to 1.5 μm in the direction of the thickness of the edge. In this case, the hardness of the edge is increased so that the rigidity is enhanced. 
         [0015]    In accordance with a ninth aspect of the present invention, a blade member is provided in which, in a vacuum chamber, a plurality of blade groups, each of which is formed by laminating a plurality of blades in a horizontal direction and passing a skewer through the blades, are caused to rotate while orbiting relative to each other. The edges are subjected to plasma ion implantation of nitrogen plasma using a plasma ion implantation gun. In this case, each blade group spins while orbiting about the plasma ion implantation gun. Thus, plasma ion implantation is evenly performed on the entire blade group. Therefore, the hardness of the entire edge is averagely increased, so that the rigidity is enhanced. 
         [0016]    In accordance with a tenth aspect of the present invention, an edge working apparatus for a blade member is provided that includes, in a vacuum chamber, a rotating body, a plasma ion gun, and a plasma ion implantation gun. The rotating body causes a plurality of blade groups, each of which is formed by laminating a plurality of blades and passing a skewer through the blades, to rotate while orbiting. The working apparatus subjects the edges of each blade group to ion beam treatment using the plasma ion guns, in which argon is used as a medium, and subjects the edges of each blade group to plasma ion implantation of nitrogen plasma using the plasma ion implantation gun. In this case, each blade group spins while orbiting about the plasma ion gun and the plasma ion implantation gun. Thus, ion beam treatment is evenly performed on the entire blade group. Also, the plasma ion implantation is evenly performed on the edges of each blade group. Further, the ion beam treatment and the plasma ion implantation are performed in the same vacuum chamber. Thus, these processes can be subsequently performed, so that the edge can be worked efficiently. For example, one of the ion beam treatment and the plasma ion implantation may be performed after the other. Also, the plasma ion implantation and the subsequent ion beam treatment may be repeated. Alternatively, the ion beam treatment and the subsequent plasma ion implantation may be repeated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a diagram schematically showing a working apparatus for the edge of a blade member according to one embodiment; 
           [0018]      FIG. 2  is an explanatory diagram showing the principles of ion beam treatment; 
           [0019]      FIGS. 3(   a ) and  3 ( b ) are explanatory diagrams showing the principles of plasma ion implantation; 
           [0020]      FIGS. 4(   a ),  4 ( b ),  4 ( c ), and  4 ( d ) are explanatory diagrams each schematically showing a working procedure of the edge of a blade; 
           [0021]      FIG. 5  is an explanatory diagram schematically showing the thickness of the edge of the blade according to the present invention at a position spaced from the pointed end by a predetermined distance; and 
           [0022]      FIG. 6  is a graph showing the results of felt cutting tests performed on the blade of the present invention and a conventional blade. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    One embodiment of the present invention will now be described with reference to the drawings. 
         [0024]      FIG. 1  schematically shows a working apparatus  1 , which has a vacuum chamber  2 . A blade mounting stage  3  is provided in a lower portion of the vacuum chamber  2 . In an upper portion of the vacuum chamber  2 , plasma ion guns  4  and a plasma ion implantation gun  5  are arranged in parallel. Each plasma ion gun  4  performs ion beam treatment using argon as medium, while the plasma ion implantation gun  5  performs plasma ion implantation using nitrogen plasma. An orbit base  6  is supported by the blade mounting stage  3 . The orbit base  6  functions as a rotating body that rotates about an orbital axis  6   a . Spinning bases  7  are supported on the orbit base  6 . Each spinning base  7  functions as a rotating body that spins about a rotational axis  7   a . A group of blades  9  is attached to each spinning base  7 , so as to be located about the orbital axis  6   a . The blade group  9  includes a plurality of blade members, which are blades,  10 . A skewer  8  is passed through the blades  10  such that the blades  10  laminated along a horizontal direction H. The direction in which the blades  10  are laminated is perpendicular to the orbital axis  6   a  and the rotational axes  7   a.    
         [0025]    When the orbit base  6  and the spinning bases  7  rotate, each blade group  9  spins and orbits. In this state, each blade group  9  is subjected to ion beam treatment and plasma ion implantation in accordance with working procedures shown in, for example,  FIGS. 4(   a ), ( b ), ( c ), and ( d ). The orbit base  6  and the spinning bases  7  do not need to rotate in the same direction (forward rotation), but may be rotated forward and reverse alternately. 
         [0026]    A plurality of blades  10  ( 10 A) are coupled along the longitudinal direction to form a belt-like blade material in a first working procedure shown in  FIG. 4(   a ). In the blade material, a burr  12 , which has a height from 0.1 to 10 μm, is removed by a razor strop, so that the edge  11  is made very slightly dull. Then, the belt like blade material is cut into the blades  10  ( 10 B). Thereafter, the edge  11  of each blade  10  ( 10 C 1 ) is subjected to an ion beam treatment, so as to be sharpened. Further, the edge  11  of each blade  10  ( 10 D 1 ) is subjected to plasma ion implantation, so as to be hardened. The thickness of the belt-like blade material is preferably 0.05 mm or more. 
         [0027]    In a second working procedure shown in  FIG. 4(   b ), a burr  12 , which has a height from 0.1 to 10 μm, is removed by a razor strop from the edge  11  of the connected blades  10  ( 10 A) in a belt-like blade material. The edges  11  are thus made very slightly dull. Then, the belt like blade material is cut into the blades  10  ( 10 B). Thereafter, the edge  11  of each blade  10  ( 10 D 2 ) is subjected to a plasma ion implantation, so as to be hardened. Further, the edge  11  of each blade  10  ( 10 C 2 ) is subjected to ion beam treatment, so as to be sharpened. 
         [0028]    In a third working procedure shown in  FIG. 4(   c ), a similar belt-like blade material having coupled blades  10  ( 10 A) is cut into blades  10  without removing a burr  12  on the edge  11  with a razor strop. Thereafter, the edge  11  of each blade  10  ( 10 C 3 ) is subjected to an ion beam treatment, so as to be sharpened, and the burr  12  is removed. Further, the edge  11  of each blade  10  ( 10 D 3 ) is subjected to plasma ion implantation, so as to be hardened. 
         [0029]    In a fourth working procedure shown in  FIG. 4(   d ), a similar belt-like blade material having coupled blades  10  ( 10 A) is cut into blades  10  without removing a burr  12  on the edge  11  with a razor strop. Thereafter, the edge  11  of each blade  10  ( 10 D 4 ) is subjected to a plasma ion implantation, so as to be hardened, while leaving a burr  12  having a height that is half the height of a burr that is not stropped. Further, the edge  11  of each blade  10  ( 10 C 4 ) is subjected to ion beam treatment, so as to be sharpened, and the burr  12  is removed. 
         [0030]    In the edge  11  that is worked though the working procedure of  FIG. 4(   c ) or the working procedure of  FIG. 4(   d ), alternate crests  13   a  and troughs  13   b  form a wavy edge line  13 . The height difference between the crests  13   a  and the troughs  13   b  is 0.1 to 1 μm. In each 10 μm section of the edge  11 , five to thirty crest  13   a  or troughs  13   b  are formed. The edge angle θ of the edge  11  is preferably 20 degrees or less particularly when the edge  11  is not stropped, and more preferably 16 degrees or less. After the ion beam treatment or the plasma ion implantation, the vacuum chamber  2  is cleaned. 
         [0031]    As shown in  FIG. 2 , which illustrates the principles of the ion beam treatment, argon gas is introduced into each plasma ion gun  4 , and enters a plasma state, where the argon gas is ionized into argon ions (Ar + ) and electrons e − . Argon ions are extracted by a magnetic filed (not shown) and applied to the edge. The argon ions work the edge by flicking off metal from the edge, thereby sharpening the edge. In the ion beam treatment, the ionization voltage is set to 2 to 3 kV. The bias voltage to the blade groups  9  is set to 0.1 to 1000 V. The argon pressure is 0.1 to 1 Pa, and the processing time is set to 5 to 300 minutes. The ion beam treatment is performed over a distance of 1 to 30 μm along the two edge surfaces  11   b , to a depth of 0.1 to 1.5 μm from the pointed end  11   a  of the edge  11 , and to a depth of 0.1 to 1.5 μm along the thickness of the edge  11 , as shown in  FIG. 5 . The temperature of the edge  11  is increased to 150° C. or higher. 
         [0032]      FIGS. 3(   a ) and  3 ( b ) illustrate the principles of the plasma ion implantation. When a current is applied to a tungsten filament W while nitrogen gas is being injected into the vacuum chamber  2 , the nitrogen gas enters a plasma state. In this state, negative bias is applied to the blade to cause nitrogen plasma (N + ) to hit and be implanted into the edge. This generates Fe 4 N, thereby hardening the edge. In the plasma ion implantation, the filament current is set to 100 to 200 A, the discharge current is set to 100 to 300 A, the bias voltage to the blade groups  9  is set to 0.1 to 1000 V, the nitrogen pressure is 0.5 to 5 Pa, and the processing time is set to 10 to 1000 minutes. The discharge current refers to a current applied between the ion gun and the blade group to cause nitrogen plasma (N + ) to hit and be implanted into the edge. 
         [0033]    The plasma ion implantation is performed over a distance of 0.1 to 3 mm along the two edge surfaces  11   b  in the entire length of the edge  11 , to a depth of 0.1 to 1.5 μm from the pointed end  11   a  of the edge  11 , and to a depth of 0.1 to 1.5 μm along the thickness of the edge  11  as shown in  FIG. 5 . The temperature of the edge  11  is increased to 200° C. or higher, and the hardness of the edge  11  becomes 1200 to 2000 Hv. 
         [0034]    In the edge  11 , which has been worked through any of the procedure of  FIGS. 4(   a ),  4 ( b ),  4 ( c ),  4 ( d ) as described above, the distance (depth) from the pointed end  11   a , which is formed by the intersecting edge surfaces  11   b , is expressed by L, and the thickness between the edge surfaces  11   b  at the distance L is expressed by T. The values of the thickness T at the distance L are shown in table 1. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Blade thickness of ideal shape 
               
             
          
           
               
                 Distance L from 
                 Thickness 
                   
               
               
                 the pointed end 
                 T (μm) 
               
             
          
           
               
                 (μm) 
                 Tmin 
                 Tmax 
               
               
                   
               
             
          
           
               
                 0.5 
                 0.4 
                 0.5 
               
               
                 1 
                 0.65 
                 0.85 
               
               
                 2 
                 1.1 
                 1.4 
               
               
                 4 
                 2.1 
                 2.5 
               
               
                 10 
                 4.0 
                 4.5 
               
               
                 20 
                 6.5 
                 7.5 
               
               
                 30 
                 9.0 
                 11.0 
               
               
                 50 
                 14.0 
                 16.5 
               
               
                   
               
             
          
         
       
     
         [0035]    That is, the ideal shape of the edge  11  is achieved when, at each position of the distance L from the pointed end  11   a  of 0.5 μm, 1 μm, 2 μm, 4 μm, 10 μm, 20 μm, 30 μm, 50 μm, the thickness between the edge surfaces  11   b  of the blade  10  is between the maximum thickness Tmax (0.5 μm, 0.85 μm, 1.4 μm, 2.5 μm, 4.5 μm, 7.5 μm, 11.0 μm, 16.5 μm) and the minimum thickness Tmin (0.4 μm, 0.65 μm, 1.1 μm, 2.1 μm, 4.0 μm, 6.5 μm, 9.0 μm, 14.0 μm). 
         [0036]    Up to 4 μm of the distance L from the pointed end  11   a , the edge  11  is relatively thick and the durability is increased. In a region where the distance L from the pointed end  11   a  is 4 μm or greater, the edge  11  is relatively thin, so that the cut resistance is reduced. 
         [0037]    The edge  11  is subjected to film forming process to form a film of DLC (Diamond Like Carbon) or TiCrAlN to improve the strength of the edge  11 . Also, the pointed end  11   a  of the edge  11  is rounded with a radius of curvature of 20 to 50 nm, thereby preventing the edge  11  from biting into skin. The edge  11  is also coated with fluorocarbon resin. 
         [0038]    In the felt cutting test shown in  FIG. 6 , the blade  10  of the present invention, which had been subjected to the above described additional treatment, and a prior art blade that had been subjected to the same additional treatment after being stropped, were tested for felt cutting. Every time cutting is performed, the cutting load was measured and the average value was calculated. As a result, the cutting load of the blade  10  according to the present invention was less than that of the conventional blade, and the cutting quality and the related durability of the blade  10  according to the present invention were improved. 
         [0039]    In the organoleptic test shown in Table 2, the blade  10  of the present invention, which had been subjected to the above described additional treatment, and a prior art blade that had been subjected to the same additional treatment after being stropped, were tested for shaving feel five times by thirty triers under the same conditions. Each time, the cutting quality was evaluated on a scale of one to five, and the average of the evaluation by the thirty triers was calculated. As a result, the points of the blade  10  of the present invention were higher than those of the conventional blade, and the cutting quality of the blade  10  of the present invention were improved. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Organoleptic Test 
               
             
          
           
               
                   
                 Number of shavings 
                 Present Invention 
                 Conventional 
               
               
                   
                   
               
               
                   
                 1st time 
                 4.2 
                 3.7 
               
               
                   
                 2nd time 
                 4.2 
                 3.9 
               
               
                   
                 3rd time 
                 4.0 
                 3.8 
               
               
                   
                 4th time 
                 4.0 
                 3.8 
               
               
                   
                 5th time 
                 3.9 
                 3.6
In a vacuum chamber, the edge of each blade group is subjected to an ion beam treatment under predetermined conditions using a plasma ion gun and argon as a medium, and is subjected to a plasma ion implantation of nitrogen plasma under predetermined conditions using a plasma ion implantation gun. As a result, it is possible to provide a blade member having an edge of a cutting quality enhanced by increasing the sharpness, a blade member having an edge of a rigidity enhanced by increasing the hardness, and a working apparatus capable of working those edges efficiently.