METHOD AND APPARATUS FOR GRINDING THE SLIDE SURFACE OF SKATES

Abstract: An automatic sharpening of the slide surface of a skate to desired profile with regard to at least two dimensions x and y in a coordinate system is disclosed. A grinding wheel (18, 119) is by guide means (14, 15) movable in x-direction in the longitudinal direction of the slide surface and by guide means (20, 11) movable in y-direction. Frstly, a scanning of the existing profile of the slide surface is carried out by means of the grinding wheel which with a substantially constant abutment pressure forceably is moved along the slide surface, during which movement the x- and y-coor­ dinates of the profile are continuously recorded in a mem­ ory. After eventual correction of the coordinates in the mem­ ory the grinding is carried out by forcing the grinding wheel in rotating state to repeat the recorded coordinates upon impulses from the memory.

Description: The present invention relates to a method for automatically sharpening the slide surface of a skate to restore the sliding surface after wearing to a desired profile with regard to at least two directions x and y in a coordinate system, one of said directions corredponding to the longitudinal direction of the slide surface, using a rotatable grinding wheel, said grinding wheel being movable by guide means in said x- and y-directions. The invention also relates to an apparatus for automatically sharpening the slide surface of a skate to restore the sliding surface after wearing to a desired profile with regard to at least two directions x and y in a coordinate system, one of said directions corresponding to a longitudinal direction of the slide surface comprising a rotatable grinding wheel for grinding said profile, driving means for rotating the grinding wheel, guide means for providing a movement of said grinding wheel in said x-and y-directions. Such method and apparatus are known from US-A-3 735 533. Advanced skaters and experts have found that the individual skate-style demands a particularly formed sliding surface of the skates. The sliding surface can be regarded as a grind profile - the outer contour of the sliding surface in a latteral view - and as the grind cross section - the sliding surface in a section from the front. Grind profile and grind cross section do not need to be symmetrically equal for right and left skate. It has also recently been discovered, that the sliding effect of the skate increases if a straight sliding surface is ground in existing grind profile. Thus, the sliding surface is unique for each skater and demands, particularly among professional skaters, an extensive work to be found out by experiment. Particularly in connection with ice-hockey, bandy and speed-skating, it has been discovered, that the sharpening degree of the sliding surface is of importance for the sliding resistance of the skate, i.e. a too sharp sliding surface yields a partially high contact pressure tending to deform the ice in a way unfavourable for the sliding resistance. This deformation depends of course on the hardness of the ice but above all on the force that the skater develops during the skating. When a skater has found the grinding adapted to his skating and the ice surface, it is of greatest importance, that the grind profile and the grind cross section is maintained upon renewed sharpening of the sliding surface. Skate grinding demands today more or less an expert who manually grinds the sliding surface of the skate. For grinding a straight sliding surface a number of "planning models" having different long straight surfaces exist. The exact grind profile is impossible to obtain or maintain. A sliding surface as individually formed as possible can with this manual method be produced today. It is in US-A-3,735,533 disclosed an automatically operating grinding or sharpening machine for skates. This machine is, however, only built up as a coin-operated automatic machine and for grinding two skates after that a correct number of coins has been inserted into a coin-mechanism. The machine is very complex, among other things due to the fact that it requires a multitude of controls. It can nevertheless only grind in accordance with a fixed program and it performs only hollow grinding (concave cross-section). The number of times the grinding wheel performes grinding depends on what switch has been set, "good", "fair" or "poor" and that a correct number of coins has been inserted. The grinding direction is always the same. The main object of the present invention is to provide a technique allowing an automatically performed mechanical sharpening of the slide surface of a skate as well as a controlled individual change of grind profile and/or cross-section of the skate. Another object of the invention is to provide a technique allowing an optional detailed configuration of grind profile and grind cross-section. A further object of the invention is to provide a technique allowing a successful sliding surface to be maintained upon repeated sharpening. Still another object of the invention is to provide a technique allowing a change of the grind profile of a skate with regard to the positioning of a desired straight sliding surface with minimum machining grinding on the skate blade. Still another object of the invention is to provide a technique that can be used during a long time without particular service with maintained acceptable ability to sharp and change the grind profile/grind cross-section of the skate blade. Said objects are achieved by a method and an apparatus having the characteristics stated in claims 1 and 5, respectively. Compared to above mentioned known automatic skate sharpening machine a method and an apparatus according to the invention is essentially simpler and moreover all the different kinds of grinding as are individually wished can be performed by the invention. The only moment required to be carried out is to position the skate in an skate holder and thereafter start the grinding cycle via a manual starting device or, if the apparatus according to the invention should be constructed as a coin operated apparatus, a coin-accepting device. Thereupon, the existing profile of the skate blade is scanned at the same time as at least a recording in a memory, preferably an electronic memory, of measured x- and y-values takes place continuously from a 0-position, which is the position where the device, the grinding wheel, used for the scanning first contacts the skate blade after movement in y-direction from its starting position. From the 0-position the grinding wheel is moved only in contacting state without grinding during said recording of the x- and y-values in the memory, whereupon the grinding wheel returns to the 0-position. After eventual correction of the measured x- and y-values in the memory to desired profile, the grinding wheel is put into rotation and the grinding wheel is guided during grinding of the sliding surface of the skate with adequate machining (0.05 - 0.1 mm) along the path determined by the recorded (and eventually corrected) x- and y-values. A total grinding cycle to desired grinding profile can include several grindings with appropriate machining for each grinding and the number of grindings can be choosen in advance. The invention also yields the possibility to grind at least one straight slide surface along a part of the profile and this straight slide surface can optionally be positioned along the profile. Via for instance a key board the grind profile recorded in the memory is completed with at least two x-values (x1 and x2) from the 0-position. The grinding takes place according to the recorded x- and y-values with the exception that the grinding wheel grinds along the shortest way between the completed x-values. The number of grindings can be adapted so that machining to the desired grind profile (x, x1, x2, y) is obtained. Moreover the invention makes possible to, besides ordinary symmetric grind cross-section in hollow grinding, displace the grinding also in z-direction in the coordinate system and accordingly obtain an unsymmetrical grind cross-section, which can fit certain skaters' skating style. Such a displacement is obtained in a simple way by arranging the grinding wheel adjustable in z-direction. The technique according to the invention also allows, that an individually obtained desired grind profile can be stored, for instance be recorded on magnetic tape, for repeated use. It is from the above evident, that the method and the apparatus according to the invention can be made more or less advanced. In the common case the x- and y-coordinates are recorded during the scanning of existing profile and the grinding takes place in accordance with this recording, eventually after a certain correction to desired profile. It is also possible to let the apparatus suggest a certain grind profile. In a more advanced construction the technique according to the invention also allows a guiding of the grind process with regard to the grind cross-section. Moreover, the invention allows a storage of an obtained desired grind profile for future repeated grinding. The invention is in the following described more in detail in some embodiments with reference to the accompanying drawings, wherein: Fig. 1 is a side view of an embodiment of a machine according to the invention having a skate inserted into a skate holder, Fig. 2 shows the machine according to Fig. 1 from above and with the skate removed, Fig. 3 is a section along the line III-III in Fig. 1 and with the skate removed, Fig. 4 illustrates schematically a particular grind process, Fig. 5 shows a side view of the back portion of a skate holder in another embodiment and more in detail, Fig. 6 shows the back portion of the skate holder seen from above, Fig. 7 shows in a view corresponding to Fig. 6 the back portion of the skate holder in another position, Fig. 8 illustrates somewhat schematically an adjusting device forming part of the skate holder, Fig. 9 shows in larger scale the encircled area in Fig. 8, and Fig. 10 shows exemplified an electrical circuit for different operations. The skate sharpening machine shown in Figs 1-3 consists of a holder 2, 3, 5, 6 for a skate A having a skate blade 1 and arranged in a stand 8a, 8b, 9, 10. A grinding device is also journalled in the stand and includes a grinding wheel 18 movable in both x- and y-direction. The skate blade 1 is with its one end positioned in a recess 13a in the holder component 2, whereupon a manually operated holder component 3 via a handle 4 is moved into abutment against the other end of the skate blade to the position 3' shown with dash-dotted lines, thereby positioning this end in a recess 13b in the holder component 3. Thereupon, a motor to a driving device 30 (Fig. 2) is started and pulls a dog means 31 towards the holder component 3. At the same time as the dog means 31 is moved, the position for recording the length of the skate blade is indicated. Pivotally arranged heals 5, 5' in the holder support the skate blade 1 together with shoulders 6 included in the holder. When the holder component 3 is pressed against the blade 1, the holder components 2 and 3 spring inwardly about 5 mm, which causes a breaker 34 to be influenced by guiding arms 35, thereby switching off the current to the drive means 30. At the same time as the holder components 2 and 3 spring inwardly, the support heals 5 and 5' are activated by set means 33a and 33b, which causes the heals 5 and 5' to be pivoted away to the position shown with dash-dotted lines in Fig. 2. When the heals 5 and 5' are pivoted away, the electronique indicates that the skate is locked and in a position for grinding. A motor 25 starts and moves the entire grinding device with the grinding wheel 18 in x-direction during guidance of roller pairs 14a-d along guides 15a, 15b. When the periphery of the grinding wheel 18 reaches the front portion of the skate blade 1, the grinding device is pressed in y-direction against the influence of a gas spring 36 which holds the entire weight of the grinding device in the cradle which is guided by roller pairs 20a-d along guides 11a and 11b. The gas spring 36 forces the grinding wheel to abut the skate blade with a substantially constant force independent of the position in y-direction along the blade. See also Fig. 3. Such a resilient arrangement of the grinding unit, for instance as exemplified with the gas spring arrangement, with a constant pressure of the grinding wheel against the blade during the following scanning of the profile of the blade is a pre-requisite for correct scanning of the existing profile of the blade. The motor 25 for the movement of the cradle in x-direction via a spindle 12 also drives via the spindle a marking disc 23 cooperating with a puls transmitter 24 for delivering pulses to the control center of the machine, where the length of the skate blade is stored in an electronic memory. At the same time as memory storage of the movement of the grinding wheel as scanner in x-direction takes place, a memory recording of the wheel movement in y-direction takes place by the fact that a stationary ball screw 28a (Fig. 3) is forced to rotate during the movement of the grinding unit in y-direction, and this screw has also a marking disc 28 and a pulse transmitter 29. Thus, from a 0-position, which is the position where the grinding wheel 18 first is brought into contact with the skate blade after movement in y-direction from its starting position, the existing profile of the skate blade is scanned during movement of the grinding wheel in only following state without rotation and during simultaneous continuous recording in a memory of measured x- and y-values, whereafter the grinding wheel returns to the 0-position. After eventual correction of the measured x- and y-values in the memory to desired profile the grinding operation takes place. A motor 26 is connected to the screw 28a via an electric magnet 27. The grinding motor 16 drives the grinding wheel 18 via a transmission 17 and the grinding operation is started from the 0-position. The grinding wheel is during the grinding of the slide surface of the skate guided with appropriate machining grade along the path determined by the recorded (and eventually corrected) x- and y-values. A total grinding cycle to desired grind profile can include several grindings with a machining grade for each grinding, and the number of grindings can be selected in advance. After required number of grinding movements the machine stops and returns to the starting position as well as the different holder components. The skate is removed from the machine whereupon the other skate is inserted and the recorded measure and the grinding process is repeated. Thus, during the measure and scanning cycle the connection between the ball screw mechanism 28a and the motor 26 is off and the ball screw mechanism is connected to the pulse transmitter 29 which records the movement of the grinding wheel 18 in y-direction. During the machining grinding cycle the connection between the ball screw mechanism and the motor is switched on and the earlier recorded pulses guide the driving of the motor for movement of the grinding wheel in y-direction synchronously with the recorded movement in x-direction. The grinding process described above is the one which can be performed in the simpliest machine built on the technique according to the present invention. When desired to perform a more advanced grinding of a skate, for instance a change of grind profile or a displacement of a straight portion of the slide surface, the machine can be completed with a guidance via for instance a key board. The grind profile of the cross-section can also be varied by abutting different scrapers 32 arranged on rotatable drum 22 against the grinding wheel 18 before the measure and scanning cycle. After that the periphery of the grinding wheel has adopted the form of the scraper, a certain maximum abutment force will be exceeded, which results in the ceasing of the scraping. Grinding and displacement of the straight portion of the slide surface can in limited extent also take place with the use of a "standard grinding program", provided that an excenter mechanism 7 included in the holder for the skate is readjusted. In this case a minimum machining will take place in the front or back of the skate blade depending on whether the displacement of the straight surface is wished forwardly or backwardly. In Figs 1 and 3 there is also shown exhausting means 19 which both collects and discharges machining and grinding particles to a collecting container. Said exhausting means can preferably be connected to the suction side of a fan. Fig. 4 schematically illustrates a particular grinding process obtained by completing, as mentioned above, the machine with a guidance via for instance a key board in order to grind or move at least one straight portion on the grind profile. The excentrics 7a and 7b make possible an optional positioning or movement of at least one straight slide surface on the grind profile and such that a minimum machining of the skate blade is obtained. The grind profile recorded in the memory can via for instance the key board be completed with at least two x-values x1 and x2 from the 0-line. The grinding takes place according to the recorded x- and y-values with the exception that the grinding wheel grinds along the shortest way between x1 and x2. The number of grindings can be adapted such that the machining t to the desired grind profile x, x1, x2, y is obtained. Figs 5-7 show an embodiment of a skate holder according to the invention preferred for the time being. Only one end portion of the holder is shown. The holder component 102 corresponding to the holder component 2 in previously described embodiment is fixed, while opposite holder component 102 corresponding to holder component 3 in the previous embodiment is running freely. A holder component 103 is arranged inside each holder component 102 and consists of two angle clamp pieces 105 provided with rolls 116, tension springs 104 and pivots 107, about which the clamp pieces 105 are pivotable. Moreover, a support arm 109 provided with an excentric 113 in one end is arranged below the clamp pieces 105 and the support arm is pivotable about a pivot 112. The support arm 109 is in the other end provided with an oblique groove 110 cooperating with a guide pin 111. Two supports 108 connected to the holder component 102 via arms 108a are furthermore arranged above the excentric 113. The skate in inserted with the blade end abutting against the holder component 103. The blade is guided down into correct position, is adjusted by the supports 108 and rest upon the excentric 113. By means of a handle corresponding to the handle 4 in previously described embodiment the freely running holder component 102 is moved against the opposite end of the blade. Driving means corresponding to driving means 30 in previous embodiment is activated and pulls a dog corresponding to the dog 31 against the holder component 102. The force is transmitted via the skate blade to pins 114 and springs 115. Upon the spring action rolls 116 are influenced such that the clamp pieces 105 are pivoted about the pivots 107 and the jaws 106 clamp firmly the skate blade and straighten it vertically. After a certain spring action the arm 109 is influenced and via the oblique groove 110 and the guide pin 111 the arm is pivoted outwardly. This position is shown in Fig. 7. The grinding wheel has now free passage for its operations. When maximum clamp force has been obtained in the clamping between the jaws 106 a plate 117 abutting the outside of the holder component 102 has reached a limit switch 118 and the set function is ceased. The skate is locked. After finished grinding cycle the set means returns to starting position, the springs 115 press the holder component 103 back to its initial position, the springs 104 open the clamp pieces 105, and the guide pin 111 moves the arm 109 back to the starting position. Figs 8 and 9, finally, show exemplified a setting means included in the skate holder in order to obtain unsymmetrical grind cross-sections besides a symmetrical cross-section. The grinding wheel 119 is via the transmission 120 driven by driving motor 121. A shaft 122 is pivotably arranged by means of a handle 123 from a symmetrical 0-position for the grinding wheel either to the left or to the right, as illustrated in Fig. 9 to an unsymmetrical V-position or H-position for the cross-section. Fig. 10 illustrates the electrical circuit for the machine. The circuit is per se conventional and therefore not described. The invention is not limited to the embodiments described above but can be modified in different ways within the scope of the following claims. Thus, the technique according to the invention for instance also allows that an individually obtained "successful" grind profile can be stored on for instance a magnetic card in code form and such a card can later on be used upon repeated grindings of the skates. The machine can furthermore be developped to a coin and note activable automatic machine provided with means for receiving and scanning payment means, wherein after correct payment a skate-receiving space in the machine becomes available. The technique according to the invention can also be developped in such a way that a manually programmable computer, communicatable via a key board, is connected to the machine. In the memory of such a computer it is possible to store information about ice, air moisture, temperature, skater's weight, type of skating to be practiced, skate manufacture, etc, and the computer calculates an appropriate grind profile and an appropriate grind cross-section.

Claims: A method for automatically sharpening the slide surface of a skate to restore the sliding surface after wearing to a desired profile with regard to at least two directions x and y in a coordinate system, one of said directions corresponding to the longitudinal direction of the slide surface, using a rotatable grinding wheel, said grinding wheel being movable by guide means in said x-and y-directions, characterized in the steps of: forcing said grinding wheel in a non-grinding state with a substantially constant contact pressure at measuring points against the slide surface for scanning and determining a plurality of x- and y-coordinates for the existing profile of the slide surface by moving said grinding wheel in said x- and y-directions; recording during said scanning the x-and y-coordinates in a memory; forcing the grinding wheel in rotating grinding state against the slide surface and governing, during the machine grinding of the slide surface, in response to signals from the memory, the movement of the grinding wheel in x- and y-direction according to the path determined by the x- and y-coordinates recorded in the memory. A method according to claim 1, further comprising the steps of correcting the scanned recorded coordinates in the memory before the grinding. A method according to claim 1 and 2, further comprising grinding at least a straight slide surface along a portion of the profile. A method according to any of the preceding claims, further comprising the step of adjusting the grinding wheel in a direction perpendicular to the longitudinal extension of the slide surface, i.e. in the z-direction of the coordinate system. An apparatus for automatically sharpening the slide surface of a skate to restore the sliding surface after wearing to a desired profile with regard to at least two directions x and y in a coordinate system, one of said directions corresponding to a longitudinal direction of the slide surface comprising a rotatable grinding wheel (18,119) for grinding said profile, driving means (26,121) for rotating the grinding wheel, guide means (14 , 15,20,21) for providing a movement of said grinding wheel in said x-and y-directions, characterized in means for disconnecting said driving means (16,121) during scanning by said grinding wheel (18,119) in said non-grinding state of the existing profile of said slide surface, means (36) for creating a substantially constant pressure of the grinding wheel against the slide surface at a plurality of measuring points during said scanning, and for determining x-and y-coordinates at said measuring points, means (23,24,28,29) for recording in a memory said x- and y-coordinates corresponding to the scanned profile of said slide surface, means for connecting said driving means of the grinding wheel during a subsequent grinding operation, and means (26,27,28a) connected to said recording means for controlling, during said grinding operation, the movement of the grinding wheel in x- and y-direction according to the path determined by the recorded x- and y-coordinates. An apparatus according to claim 5 including means (7,X1,X2) for grinding at least a straight slide surface along a portion of the profile. An apparatus according to claim 5 or 6, including adjustment means (122,127) for parallel displacement of the grinding wheel (119) in the z-direction of the coordinate system. An apparatus according to any of claims 5-7, wherein said means for recording the x- and y-coordinates comprises a marking disc (23,28) and pulse transmitter (24,29). An apparatus according to any of claims 5-7, including support means (109) for temporary support of the skate blade (1) after positioning of the skate in the machine, two means (103) movable relative to each other in the x-direction for movement towards each other after the positioning of the skate thereby to cause said two means to abut against the ends of the skate blade, with the securement of the skate blade and said support means being adapted to be simultaneously removed with the slide surface of the skate blade being exposed. An apparatus according to any of claims 5-9, including means for receiving and scanning payment means for access to the machine.

Inventors: EK, ROBERT
Applicants: EK, ROBERT
Application year: 1985
Main classification: B24B9
IPC codes: B24B3, B24B49