Abstract:
A fixture for securely holding a member such as a knife against a grinding element such as a grinding wheel during a grinding operation. The fixture includes a blank (knife) support assembly rigidly secured to the upper plate which is slidably supported on a lower plate which is rigidly attached to the grinding device. An adjusting mechanism is interconnected between the upper and lower plate for the slidable movement of the upper plate on the lower plate to retain the blank (knife) support assembly, and thus the knife edge, against the grinding device during the grinding operation.

Description:
FIELD OF THE INVENTION 
     The present invention is generally directed to a fixture for retention of a blade or the like against a grinding member during a grinding operation. The invention is more directly related to such a fixture which is adjustable to maintain a predetermined pressure between the grinding member and a blank (blade) for hollow grinding thereof. 
     BACKGROUND OF THE INVENTION 
     In a typical process of making a &#34;hand made&#34; knife, the knife maker generally holds the knife blank by hand against a rotating grinding wheel and grinds away the required amount of metal to hone the edge to the desired sharpness. During the process, the blank is moved normally across the edge of the grinding wheel while it is manually held against the grinding wheel by the operator. Not only is such an operation time consuming, but it also usually results in a knife having a non-uniform blade edge. 
     To overcome such deficiencies, applicant has provided a fixture which is attachable to a grinder or the like which holds the blade securely against the grinding wheel while permitting the operator to move the knife blank back and forth across the surface of the grinding wheel to provide for uniform hollow grinding of the edge to a predetermined thickness in a rapid and facile manner. 
     SUMMARY OF THE INVENTION 
     This invention relates to a fixture for adjustably retaining the edge of a knife or the like against a grinding device, such as a grinding belt or wheel, while hollow grinding the edge of the knife or the like. 
     It is an object of the present invention, therefore, to provide a fixture which may be used with a grinding device to assist in the hollow grinding of a blank of material to produce a hollow ground knife edge thereon. 
     It is another object of the present invention to provide such a fixture with adjusting means to permit the fixture to hold and retain the blank against the grinding device with a predetermined pressure during the hollow grinding operation. 
     It is still a further object of the present invention to provide such a fixture with a hardened wear surface against which the blank or workpiece engages during the hollow grinding operation. 
     It is still yet another object of the present invention to provide such a fixture which is adaptable for use with various types of bench grinders having circular grinding wheels, with belt grinders, and with drum sanders. 
     These and other objects of the present invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational view of a bench grinder having the fixture of the present invention attached thereto. 
     FIG. 2 is a pictorial view of the hollow grinding fixture of the present invention. 
     FIG. 3 is an exploded view of the hollow grinding fixture of FIG. 2. 
     FIG. 4 is a diagrammatic end view of the positioning of a knife blank relative to the grinding wheel. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As seen in FIG. 1, a bench grinder 10 is shown mounted to a support 12. The grinder is shown to include a rotatable grinding wheel 13 for engagement with a workpiece such as a knife blank, etc., to perform a hollow grinding operation thereon. A fixture 14 is secured to grinder 10 for maintaining the workpiece against the wheel during the grinding operation. The fixture 14 includes a top plate 16 slidably mounted on a bottom plate 18. The top plate has secured on the upper surface 20 thereof a workpiece holding assembly 22 for holding or supporting the workpiece against grinding wheel 13. The bottom plate 18 is provided with an angle bracket 24 secured thereto. Bracket 24 secures the fixture to the grinding device 10. An adjusting mechanism assembly 26 is secured to the upper and lower bodies to provide relative sliding movement therebetween. 
     As can be seen in FIG. 3 (which is an exploded view of the fixture), bottom plate 18 is substantially rectangular in configuration with a central raised guide 28 extending along the length thereof. The front portion 30 of plate 18 is provided with a tapped opening 32 therein for reasons explained hereinbelow. The aft portion 33 of plate 18 is provided with a cut-away section 34 to provide an opening to receive the wheel 12 of grinder 10. The cut-away section 34 removes part of the raised guide 28, leaving two edge portions 36 and 38 (FIG. 4). A tapped opening 40 is provided on the upper surface 42 of plate 18 for reasons explained hereinbelow. 
     Upper plate 16 is also substantially rectangular in configuration and includes upper and lower surfaces 20 and 46 and forward and aft portions 48 and 50, respectively. Lower surface 46 is provided with a grooved central surface 49 extending the length of plate 16. Groove 49 is disposed to snugly fit on the raised central guide 28 of plate 18 (FIGS. 2 and 3). The aft portion 50 of plate 16 is provided with a cut-away section 52, similar to the cut-away section 34 of plate 18, to provide an opening to receive wheel 12 of the grinder. 
     Upper surface 20 of plate 16 includes a slot 53 substantially in the center thereof and two pairs of dowels 54 and 56, each pair disposed on the spaced legs 58 and 60 formed by cut-away section 52. Workpiece holding assembly 22 (FIG. 2) is mounted to the upper surface 20 of plate 16. Workpiece holding assembly 22 includes a pair of spaced similar L-shaped members 62 and 64, respectively, mounted inspaced, end to end relation on spaced legs 58 and 60 of plate 20 by screws 66 and 67. L-shaped members 62 and 64 include upstanding portions 68 and 70 having respective rear surfaces 71 and 73. The two L-shaped members include horizontal legs 63 and 65 which are provided with elongated slots 72 and 74 into which the pairs of dowels 54 and 56, respectively, seat. A third elongated L-shaped member 76 extends transversely across surface 20 and includes an upstanding portion 78 having a rear surface 79. L-shaped member 76 is disposed in spaced relation with upstanding portions 68 and 70 of L-shaped members 62 and 64 to provide a space 80 therebetween to receive the workpiece therein. L-shaped member 76 further includes a horizontally extending leg 81 having an open ended slot 82 into which a shoulder bolt 84 is inserted. Bolt 84 extends through slot 53 of upper plate 20 and is disposed in threaded relation with tapped opening 40 (FIG. 3) of lower plate 18. Bolt 84 extends through a spring 86 and washer 88 for spring biasing upper plate 16 to lower plate 18. The elongated L-shaped member 76 is provided with spaced grooves 90 and 92 and is secured to plate 16 by screws 94 and 96 which respectively extend through slots 90 and 92 and into tapped openings 94 and 96 (FIG. 3) of plate 16. The underside surface 83 of horizontal leg 81 is provided with a pair of spaced grooves 85 and 87 into which the pairs of dowels 89 and 91 extend. Dowel pairs 54 and 56, associated with L-shaped members 62 and 64, and dowel pairs 89 and 91, associated with elongated L-shaped member 76, serve to maintain alignment of members 63, 64, and 76 so that the respective rear surfaces 71, 73, and 79 are disposed in substantially parallel relation. 
     To provide for relative sliding movement between the upper and lower plates, adjusting mechanism 26 is provided, and it includes an inverted L-shaped bracket 97 having a horizontally extending leg 98 and a downwardly depending leg 100. Leg 98 is secured to upper surface 20 of upper plate 16 by screws 102 and 104 which extend through openings 99 and 101 of bracket 97 and into tapped openings 106 and 108 (FIG. 3) of plate 16. Downwardly depending leg 100 is provided with an opening 110 (FIG. 3) through which a threaded rod 112 extends. Rod 112 extends into threaded engagement with tapped opening 32 of lower plate 18 (FIG. 3). A beveled nylon washer 114 is mounted on rod 112 intermediate a lock nut 115 and downwardly depending leg 100. A knurled knob 116 is secured on rod 112. 
     As can be seen in FIGS. 2, 3, and 4, upper surface 20 includes a transverse slot 122 extending in the space 80 between the L-shaped members. A carbide wear plate 124 (FIG. 2) is secured (by press fitting, etc.) in slot 122 and is disposed to engage the edge of the workpiece during the grinding operation. The wear plate may be replaced should it ever become worn. 
     FIG. 4 is a diagrammatic end view of the positioning of a knife blank relative to the grinding wheel, the L-shaped members 62, 64, and 76, and the wear plate 124. In operation, and as can be seen in FIG. 4, wheel 13 extends into the openings 34 and 52 at ends 58 and 60 of plates 18 and 20 for engagement with the edge of the knife blank. The blank is held firmly between members 62, 64, and 76 but is manually movable between the rear surfaces 71, 73, and 79 of the upstanding L-shaped members 68, 70, and 78. 
     It is to be understood that although the hollow grinding fixture of the present invention is discussed and shown herein as being used with a bench grinder, this is not to be taken in a limiting sense, as the fixture may also be used with other grinders, including square wheel belt grinders, drum sanders, and other types of belt grinders. 
     It is to be also understood that the bracket shown herein includes slots which provide for mounting the brackets to various types of grinding machines. While the bracket shown herein is provided with an L-shaped configuration, other types of brackets may be resorted it. The fixture of the present invention is preferably made of brass and steel, the lower plate being typically made of brass. Such materials prevent galling of the parts.