BLADE SHARPENING

Abstract: A skate blade sharpening machine includes an adjustable full-width dressing wheel (75) rotated by a separate electric motor (77) against the grinding wheel (13) of the skate sharpening machine.

Description: BLADE SHARPENING The invention relates to a method and apparatus for sharpening the blades of ice skates and like devices. It is known that the shape of an ice skate blade can influence the skater's performance. Hence, for any keen skater or for a professional such as an ice hockey player or figure skater, selecting a shape and maintaining it by sharpening is an important activity. A skate blade can be curved in the direction' from one to the other end of the blade and it can also be hollow ground, i.e. in croSs-section it can have a concave surface facing the ice from one to the other side of the blade. This curved concave surface is called the "hollow". The hollow can have a radius of several centimetres (inches) and it can be a simple curve or quite complex, for example, there may be two flat lands one each side of the concave portion or there may be two or more concave curved grooves extending alongside one another. To form and maintain the required shape, a skate blade sharpening machine is required. Such a machine is basically a specialised type of grinding machine with a narrow, electric motor driven grmding wheel and a clamp for holding a skate of which the blade is to be sharpened. A suitable mechanism, sometimes automatic, is provided for relatively moving the skate and grinding wheel to sharpen the skate blade. The relative movement is in the direction of the length of the blade and parallel to the plane of, but transverse to, the axis of rotation of the grinding wheel. To obtain a hollow ground blade, the periphery of the grinding wheel is curved in a manner complementary to the concave edge of the blade. Of course, whether for flat or hollow ground blades, the periphery of the grinding wheel has to be kept to an accurate shape by the operation of dressing the wheel. For example, as disclosed in US A-5287657 (see Figure 17) a grinding wheel in a skate sharpening machine may be dressed by a single point diamond headed pin which is moved across the periphery of a grinding wheel, either straight or along a curved path. One object of the invention is to provide an improved method and apparatus for dressing a grinding wheel in a skate blade sharpening machine. According to the invention in one aspect there is provided a method of dressing a blade sharpening apparatus, which apparatus comprises a platform, a motor mounted on the platform and for rotating a grinding wheel to sharpen the blade, the grinding wheel extending generally parallel to and above the platform, the method comprising: • advancing a dressing wheel to the grinding wheel; • adjusting the height of the dressing wheel to that of the grinding wheel; • moving the dressing wheel until the periphery thereof contacts the edge of the grinding wheel; and • rotating the grinding wheel and the dressing wheel until the grinding wheel has been dressed to a predetermined profile. Preferably the method includes the step of rotating the dressing wheel at a faster speed than that at which the grinding wheel is rotated. According to the invention in a second aspect there is provided a dressing tool accessory for a blade sharpening apparatus which comprises a platform, a motor mounted on the platform and for rotating a grinding wheel to sharpen the blade, the grinding wheel extending generally parallel to and above the platform, the dressing tool accessory comprising: • a support to be located on the skate sharpening apparatus platform; • a motor mounted on the support and for rotating a dressing wheel; • means for adjusting the position of the dressing wheel vertically so that the periphery of the dressing wheel contacts the edge of the grinding wheel and can be rotated to dress the grinding wheel. Preferably the accessory includes means for moving the accessory horizontally to move the dressing wheel towards or away from the grinding wheel. Preferably the dressing wheel comprises a disc having a body and a peripheral portion of bonded diamond particles, the disc having a thickness substantially corresponding to that of the grinding wheel. According to a third aspect of the invention there is provided a blade sharpening apparatus comprising a platform, a motor mounted on the platform and arranged to rotate a grinding wheel to sharpen the blade, the grinding wheel extending generally parallel to and above the platform, a dressing tool mounted on the platform and movable in and out of engagement with the grinding wheel, the tool comprising a dressing wheel, and a motor for rotating the wheel, means for adjusting the dressing tool vertically until the dressing tool is in vertical alignment with the grinding wheel and means for moving the dressing wheel horizontally for the edge of the dressing wheel to contact the periphery of the grinding wheel. In yet another aspect the invention provides footwear having a blade which has been sharpened by a grinding wheel which has been dressed by a method as disclosed herein. It is a significant advantage of this invention that because one can align the dressing wheel with precision with respect to the grinding wheel, the dressed grinding wheel has a highly accurate profile. Not only is their little deviation from the intended profile but our evaluations have shown that a skater can increase his speed of travel. It is surprising that by dressing or truing the wheel in this way faster skating can be achieved. For a better understanding of the invention, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 is a front elevation of a first embodiment of blade-edge forming apparatus for ice-skating footwear; Figure 2 is a plan view corresponding to Figure 1 ; Figure 3 is a plan view of a dressing roller; Figure 4 is a sectional view on the line IV - IV in Figure 3; Figure 5 is a front elevation of a second embodiment of blade-edge forming apparatus for ice-skating footwear; Figure 6 is a plan view corresponding to Figure 5; Figures 7 and 8 are two diagrammatic views of respective skate blade sharpening machines; and Figures 9 and 10 are graphs showing the profile obtained using apparatus of the invention and a single point tip dresser respectively. The apparatus of Figures 1 and 2 comprises a rigid flat rectangular platform 1. A rectangular housing 2 is fixed on to the base plate by screws (not shown). One side 4 of the housing 2 is aligned with one edge 5 of the platform 1. Two opposite end walls 6 of the housing 2 extend up from the top 7 of the housing to define a shallow space 8 containing a collar 9 and screw 10 mounted at the upper end of the vertically arranged output shaft 1 1 of an electrical drive motor 12. The motor 12 is contained in the housing 2 with the shaft 11 extending up through the top 7 of the housing. Typically the motor will be an electric motor with variable speed control. The motor means can however be hydraulic, pneumatic or of any other convenient character. Mounted on the shaft 1 1 between the screw 10 and collar 9, there is a relatively narrow grinding wheel 13, the collar being relatively wide as shown so as to support the wheel. The grinding wheel 13 lies between the top portions of the end walls 6 of the housing 2. The grinding wheel of the blade sharpening apparatus may be of any convenient design. It has been discovered that the grinding wheel preferably has a high level of porosity because this will avoid over-heating of the blade. The apparatus is intended for use with a range of grinding wheel diameters, say between about 15 cm and about 22.8 cm (six and nine inches), so the distance between the walls 6 are set to permit the upper limit of this diameter range. Mounted on the platform 1, is a grinding wheel profile dressing assembly 20. The assembly 20 comprises a flat rectangular steel mounting base 21 of which the bottom surface 22, as well as the top surface 14 of the platform 1, are smoothly finished so that the mounting plate 21 makes good sliding contact with the base plate. At the front end of the base plate are two full depth slots 23 engaged with respective dowels 15 extending up from the top surface 14 of the platform 1. The dowels 15 are equi-spaced from the axis 16 (Figure 2) of the shaft 11 of motor 12 and they and the slots 23 are positioned so that, while the dowels and slots are fully engaged, the mounting plate 21 is accurately located so as to extend directly towards the axis 16. Fixed to the mounting plate 21 by screws 25 there is a slide assembly of the kind known as a "Parker Slide". This comprises a rectangular slideway defining member 27 on and over which there is a sliding member 28. The sliding member 28 has depending side walls 29 to form a space in which lies the slideway defining member 27. The inner surfaces of the side walls 29 and the adjacent sides of the slider member 27 are in close sliding contact for reciprocal movement of the member 28. An end wall 31 limits rearward sliding movement of the member 28 relative to the member 27. A threaded micrometer screw 32 with a knurled knob 33 at its outer end is engaged with a screw-threaded hole 34 in the wall 31 and the inner end of the screw 32 is coupled to the member 28 such that the screw can rotate with respect to the member 28 but linear movement of the screw is transmitted to the member. One end of a metal strip 40 is fixed to one side of the vertical wall of the member 27 by a screw 41. The strip 40 extends alongside one side wall 29 of the member 28. An elongate through slot 42 is formed in the strip and screw 43 extends through the slot into the wall 29. The screw 43 may be tightened to lock the member 28. Fixed to the upper surface of member 28 or integrally formed therewith, there is a further rectangular slideway defining member 50, the long sides of this member defining a slideway which extends orthogonally with respect to direction of movement of the member 28. Similarly there is a further sliding member 52 with downwardly depending sidewalls 53 mounted on and over the member 50 so that the member 52 can slide with respect to the member 50. An end wall portion 54 limits the movement of the member 52 and a micrometer screw 55 with a knurled knob 56 is engaged in a threaded hole in the wall portion 54 and has its end engaged with the sliding member 52. A strip 57 similar to the strip 40 is fixed to the wall portion 54 by a screw 58 so that it extends alongside the member 52 and again a screw 59 similar to screw 43 extends through the slot in the spring strip and is engaged with the member 52. Fixed to the upper surface of the sliding member 52, or integrally formed therewith, there is an upwardly extending support member 60. Another rectangular slideway defining member 61 is fixed to the face 62 of the member 60 nearer the grinding wheel so that its long sides defining a slideway extending vertically with respect to the platform 1. As with the slideway defming and matching sliding members described earlier, a sliding member 63 having sidewalls 64 is mounted on and over the slideway defining member 61, the latter having an extending end wall 65 carrying a micrometer screw 66 engaged with the sliding member 63. A slotted strip 67 is fixed to the wall 65 by screw 68 and a locking screw 69 extends through the slot in the strip 67 and is engaged with the member 63 so that, by tightening the screw 69, the vertically linear sliding 'movement of the member 63 can be locked. An intermediate support plate 70 is fixed to the sliding member 63 by screws 71 and, in turn, a dresser wheel spindle assembly 72 is fixed to the plate 70 by screws 78. The dresser wheel spindle assembly 72 comprises a hollow rectangular housing 73 having an opening 74 at one side, the opening facing the periphery of the grinding wheel. Witxiin the housing but with part of its periphery extending out of the opening 74 and engaged with the periphery of the grinding wheel, there is a dresser wheel 75. The wheel 75 is mounted for rotation about a vertical axis on the output shaft 76 of an electrical drive motor 77. The dresser wheel 75, shown in Figures 5 and 6, is about three inches in diameter by about 1.58 cm (0.625 inches) in depth. An accurately bored and ground centre hole 80 is formed through the wheel for engagement with the shaft 76. Three countersunk holes 81 are provided equi-spaced around the centre hole for enabling the wheel to be securely fixed in place on the shaft by screws (not shown) engaged with corresponding screw- threaded holes (not shown) in the load- spreading collar 79 fixed to the shaft 76. The periphery of the wheel 75 is carefully and accurately pre-machined in accordance with any particular profile desired by the user, e.g. an ice-skater, or according to one of a series of pre-selected profiles from which the user might choose. In the illustrated example, the periphery of the wheel has a cross-sectional shape comprising two flat lands 82 at respective sides of a central inwardly curved shallow groove 83. The groove is about 0.9.4 cm (0.37 inches) deep at its centre and it corresponds to part of a circle having a radius of about 12.7 cm (five inches). In other examples, the periphery might have a cross-sectional shape having two side by side grooves. In each case bonded abrasive diamond particles 84 are bonded to the surface of the groove. The function of the dresser wheel is to cause the periphery of the grinding wheel to have a shape counter to that of the dresser wheel, or to re-dress the grinding wheel to that shape so that the ice-skate blade can be accurately ground to the same shape as the dresser wheel. In the embodiment of Figures 1 and 2, the function of the Parker slide assembly is to enable the dresser wheel to be positioned very accurately relative to the grinding wheel. The micrometer screws are used to adjust the dresser wheel to the correct position and the screws engaged with the slotted strips then tightened to fix the position. The height of the dresser is adjusted to that of the sharpening blade and then moved forward until the rim of the dresser wheel contacts that of the sharpening wheel. The two wheels are rotated, the dresser wheel faster, to true the sharpening blade. In the second embodiment of the apparatus shown in Figures 5 and 6, those parts which are identical to parts in the first embodiment of Figures 1 and 2 are given the same reference numbers. This generally includes the housing for the grinding wheel motor, the grinding wheel and the dresser wheel spindle assembly. However, the platform 100 does not have the locating dowels of Figures 1 and 2. Instead, there is provided a base plate 101 having a downwardly depending portion 102 overhanging the side 103 of the base plate 100 and fixed thereto by hand-turnable screws 104, i.e. screws with grippable heads '105. A spacer member 106 is provided between the side of the base plate 100 and the portion 102, the screws 104 extending through matching holes in the spacer member. Fixed to the base plate 101 is a slideway defining member 27 and slider member 28 like those of Figures 1 and 2 but the sideways axis slideway and slider member and the vertical axis slideway and slider members are absent which reduces the cost. Instead, an upright support member 110 is fixed direct to the slider member 28. The position of the slider member 28 relative to the slideway defining member 27 is again set by a micrometer screw 32 with a knurled knob 33, this giving fine adjustment of the position of the dresser wheel assembly towards and away from the grinding wheel 13. meanwhile, coarse adjustment of the position, to allow for different grinding wheel diameters say, is achieved by choosing appropriately the width of the spacer 105. Several spacers of different widths can be provided for the user to choose from. For the smallest size of grinding wheel the spacer could be discarded. Depending on the range of adjustment given by the micrometer screw 32, it may be possible to have just one size of spacer to accommodate the larger sizes of grinding wheels and to remove the spacer for smaller wheel sizes. The upright support member 110 comprises positions defining a slideway 1 1 1 onto which there is fitted a sliding member 1 16 such that the member 1 12 can move up and down relative to the member 1 10. A member 114 is fixed to the top of sliding member 1 12 by screws 1 18 so as to extend over the top of the member 110. A Stilson screw 113 is engaged between the member 114 and the member 1 10, a Stilson screw being one with a head 1 15 loosely captured in one member (the member 114 in this case) and engaged with a threaded hole in the member 110 so that, by turning screw head 115, the sliding member 114 is adjusted vertically relative to member 110, when the member 116 is at the desired vertical position, it can be locked in position by tightening screws 112 engaged in slotted holes 119 in member 110 and screw- threaded holes in member 114. The dresser wheel spindle assembly is fixed to the sliding member 1 16by screws 117. The grinding wheel dressing apparatus described and shown in Figures 1 to 7, may be used simply to dress or redress grinding wheels for use in separate skate blade sharpening apparatus. The apparatus shown is retrofitted to an existing skate blade sharpening apparatus. Of course an original equipment machine may include this apparatus. The operator of the dressing apparatus may carry a stock of dresser wheels 75 having different profiles, e.g. chosen for speed skating, figure skating or ice hockey and he will then be able to supply a range of different dressed or redressed wheels of different sizes and characteristics according to customer requirements. Alternatively, the apparatus shown or appropriate modifications thereof could form an integral or exchangeable part of blade sharpening apparatus. Here, integral means that a grinding wheel profile dressing mechanism comprising one or more profiled dressing wheels, selector mechanism and drive motor could be integrated into skate sharpening apparatus, e.g. to replace a single point dressing mechanism, of the known kind mentioned earlier herein. By exchangeable, is meant the use of a dressing assembly occasionally in place of the skate holding fixture of a skate sharpening machine to re-dress the grinding' wheel of that machine. In Figure 7, dressing apparatus like that of Figures 1 to 4 has the dresser assembly 20 removed and replaced by a skating boot 200 held in a blade holding fixture 201. The fixture 201 comprises a block 202 in sliding engagement with the base plate 1 and a clamp 203 with a clamp screw 204 which secures the blade 205 of the boot 200. The edge of blade 205 is at the same height above base plate 1 as the periphery of grinding wheel 13. To sharpen the blade 205 the fixture 201 with the boot 200 and blade 205 is translated in the long direction of the blade in contact with the wheel 13. Whenever the wheel 13 is to be redressed, the fixture 201 is removed and exchanged for the dressing assembly 20. In Figure 8, an automatic blade sharpening apparatus (only partly shown) comprises a blade clamping mechanism 300 which holds a blade 301 for movement into engagement with a grinding wheel 302 driven by motor 303. Periodically, a wheel dressing assembly 304 like either of the assemblies 20 of Figures 1 to 6 is moved by an automatic drive assembly 305 so that the diamond dresser wheel 306 of the dressing assembly engages the wheel 302. A number of evaluations were carried out to test the efficiency of the dressing tool of the invention. EXAMPLE 1 Two blades were sharpened to an intended profile using a skate sharpening apparatus having a grinding wheel of known type. In each case the blade was sharpened to the intended type. In one case the wheel was tried using a diamond point tip, in the other using the dressing tool accessory of the present invention. The profiles of both blades were examined and the extent of deviation from the intended profile was measured. The results are shown in the graphs of Figures 9 and 10. It will be seen that in the case of the dressing, according to the instant invention, the deviation was less than 0.2 micron, whereas in the other case the result was over 1 micron. EXAMPLE 2 The speed of the skaters using blades was measured by a radar technique. The results showed that a blade sharpened by a grinding wheel dressed according to the invention travelled 4 km/hour faster than one dressed using a diamond point tip. Such a speed increase is a great advantage to the professional and amateur skater.

Claims: CLAIMS 1. A method of dressing a blade sharpening apparatus, which apparatus comprises a platform, a motor mounted on the platform and for rotating a grinding wheel to sharpen the blade, the grinding wheel extending generally parallel to and above the platform, the method comprising: • advancing a dressing wheel to the grinding wheel; • adjusting the height of the dressing wheel to that of the grinding wheel; • moving the dressing wheel until the periphery thereof contacts the edge of the grinding wheel; and • rotating the grinding wheel and the dressing wheel until the grinding wheel has been dressed to a predetermined profile. 2. A method according to Claim 1, including the step of rotating the dressing wheel at a faster speed than that at which the grinding wheel is rotated. 3. A method according to Claim 1 or 2, wherein the blade sharpening apparatus includes a platform, and the dressing tool has a base which is placed on the platform following which the height of the dressing tool is adjusted relative to the platform. 4. A dressing tool accessory for a blade sharpening apparatus which comprises a platform, a motor mounted on the platform and for rotating a grinding wheel to sharpen the blade, the grinding wheel extending generally parallel to and above the platform, the dressing tool accessory comprising: • a support to be located on the skate sharpening apparatus platform; • a motor mounted on the support and for rotating a dressing wheel; • means for adjusting the position of the dressing wheel vertically so that the periphery of the dressing wheel contacts the edge of the grinding wheel and can be rotated to dress the grinding wheel. 5. An accessory according to Claim 4 includes means for moving the accessory horizontally to move the dressing wheel towards or away from the grinding wheel. 6. An accessory according to Claim 4 or 5, wherein the dressing wheel comprises a disc having a body and a peripheral portion of bonded diamond particles, the disc having a thickness substantially corresponding to that of the grinding wheel. 7. Blade sharpening apparatus comprising a platform, a motor mounted on the platform and arranged to rotate a grinding wheel to sharpen the blade, the grinding wheel extending generally parallel to and above the platform, a dressing tool mounted on the platform and movable in and out of engagement with the grinding wheel, the tool comprising a dressing wheel, and a motor for rotating the wheel, means for adjusting the dressing tool vertically so that the dressing tool is in vertical alignment with the grinding wheel and means for moving the dressing wheel horizontally for the edge of the dressing wheel to contact the periphery of the grinding wheel. 8. Footwear having a blade which has been sharpened by a grinding wheel which has been tried by a method according to Claim 1.

Inventors: MCHUGH DONALD, SCHONFELD JEFFREY BOYD, MCHUGH, DONALD, SCHONFELD, JEFFREY, BOYD
Applicants: MCHUGH DONALD, SCHONFELD JEFFREY BOYD, UNICORN ABRASIVES LTD, MCHUGH, DONALD, SCHONFELD, JEFFREY, BOYD, UNICORN ABRASIVES LIMITED
Application year: 1999
Main classification: B24B3
IPC codes: A63C3, B24B3, B24B53