Patent Document

RELATED APPLICATIONS  
       [0001]     This application makes a claim of domestic priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 60/366,254, filed Mar. 22, 2002, the disclosure of which is hereby expressly incorporated by reference. This application is further a continuation of co-pending U.S. patent application Ser. No. 10/393,343 filed Mar. 21, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed to a tool sharpener, and, more particularly to an automated tool sharpener especially for use in sharpening drills.  
       BACKROUND  
       [0003]     Tool sharpeners for sharpening the tips of drills and the cutting faces of other cutting tools have heretofore been developed in the art. Such tool sharpeners extend the operating life of drills and other cutting tools, in that a tool having dull cutting surfaces will not perform with the desired precision or speed, and, if not sharpened, must be discarded even though the tool has a considerable amount of usable material left to work with.  
         [0004]     Particularly in industrial applications, the drills or other cutting tools are expensive items, and where change out and resharpening is not part of the normal equipment operating procedure, there is a tendency to try to prolong the useful life of the drill by using it after it has dulled and is not performing optimally. This adversely affects the quality of the products being produced. Accordingly, commercial grade or industrial grade tool sharpeners have been developed in order to prolong the useful life of drills and other cutting tools, and in order to permit the equipment to be operated substantially continuously with a drill or cutting tool of proper sharpness.  
         [0005]     A recent example of a commercial-grade tool sharpener is disclosed in U.S. Pat. No. 5,400,546, which is assigned to the assignee of the present application. The disclosure of that patent is hereby expressly incorporated by reference herein. That tool sharpener has enjoyed considerable commercial success, and is capable of providing highly precise sharpening of a drill. The sharpener does, however, require that several operations be carried out manually, or involve manual manipulations, including aligning the drill properly in the chuck (aided by an alignment device on the sharpener), tightening the drill in the chuck, and then manually manipulating the chuck and drill in one or more sharpening or dressing ports.  
         [0006]     Use of this sharpener is somewhat labor intensive, and despite the fact that the design of the sharpener greatly reduces the potential for operator error, and limits the degree of possible error which can result in an improperly sharpened drill, that possibility continues to exist.  
         [0007]     Modern cutting tools are high performance, complex and expensive devices that can not readily be sharpened manually without a great deal of effort and skill.  
         [0008]     Accordingly, a need has been identified by the present inventors to provide a tool sharpener that automates most, if not all, of the operations necessary to properly sharpen a drill or other cutting tool. The automation of the majority of the operations results in the sharpening operation being less labor-intensive and less prone to sharpening errors committed by the person operating the sharpener. This will also permit a less-skilled laborer to be entrusted with the tool sharpening function, resulting in potentially reduced labor costs.  
       SUMMARY OF THE INVENTION  
       [0009]     In accordance with preferred embodiments, a method and apparatus are provided for sharpening a tool, such as a drill bit.  
         [0010]     A tool sharpener includes a tool holder subassembly which retains and presents the tool against a grinding wheel subassembly. A sensor locates a cutting edge of the tool while the tool is retained by the tool holder. A circuit, preferably comprising a programmable processor, determines a web thickness of the tool from the located cutting edge.  
         [0011]     The cutting edge is preferably located by detecting at least first and second points at different radii along the cutting edge. A cross-feed subassembly preferably moves the sensor into position, and the tool holder subassembly preferably rotates the tool to facilitate detection of each of the at least first and second points.  
         [0012]     The tool holder subassembly thereafter preferably presents the tool against the grinding wheel subassembly in response to the determined web thickness of the tool.  
         [0013]     These and various other features and advantages which characterize the claimed invention will become apparent upon reading the following detailed description and upon reviewing the associated drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is an exploded perspective view of the tool sharpener according to a preferred embodiment.  
         [0015]      FIG. 2  is a perspective view of the tool sharpener according to a preferred embodiment, with the cover elements removed.  
         [0016]      FIG. 3  is an exploded perspective view of the infeed stage subassembly in accordance with a preferred embodiment of the invention.  
         [0017]      FIG. 4  is an exploded perspective view of the swing subassembly according to a preferred embodiment of the invention.  
         [0018]      FIG. 5  is an exploded perspective view of the grind motor assembly according to a preferred embodiment of the present invention.  
         [0019]      FIG. 6  is an exploded perspective view of the chuck assembly according to a preferred embodiment of the present invention.  
         [0020]      FIG. 7  is an exploded perspective view of the grinding wheel subassembly according to a preferred embodiment of the present invention.  
         [0021]      FIG. 8  is an exploded view of the alignment subassembly according to a preferred embodiment of the present invention.  
         [0022]      FIG. 9  is a top plan view showing the alignment subassembly in use in determining the drill diameter.  
         [0023]      FIG. 10  is a perspective view showing the alignment subassembly in use in determining the length of the drill protruding from the chuck.  
         [0024]      FIG. 11  is a front elevation view of the grinding wheel assembly with a drill positioned for sharpening.  
         [0025]      FIG. 12  is a perspective view of the vacuum system according to a preferred embodiment of the present invention.  
         [0026]      FIG. 13  is a perspective view showing a drill undergoing the honing process following sharpening of the drill.  
         [0027]      FIGS. 14A and 14B  are schematic illustrations of the user interface provided for operator input in commencing the sharpening process. 
     
    
     DETAILED DESCRIPTION  
       [0028]      FIG. 1  illustrates the tool sharpener according to a preferred embodiment in an exploded or breakaway view. The casing or housing  100  comprises a main base  102  and an electronics housing  104  which connects to the main base to complete the overall base.  
         [0029]     A three-piece cover  106  is provided in this embodiment. A side cover element  108  and rear cover element  110  are secured in fixed position overlying main base  102  and electronics housing  104 . The third cover element is a guard door  112  which is pivotably mounted to rear cover element  110 . Guard door  112  has a semi-circular peripheral wall  114 , as does rear cover element  110 . The guard door  112  is sized such that it can pivot between an open position in which it substantially overlies the rear cover element  110 , leaving grinding chamber  10  exposed to the external environment, and a closed position in which the grinding chamber  10  is substantially closed off or sealed off from the external environment.  
         [0030]     The guard door  112  is preferably provided with a window  113  on an upper surface thereof, which permits an operator to view the sharpening operation with the guard door closed.  
         [0031]     The cover  106  is preferably provided with an operator interface. As shown, side cover element  108  is provided with a touch screen  118  and one or more operator input buttons  120  at the front portion of the cover. Details regarding the function and operation of the operator interface will be discussed later in this specification. The side cover element  108  may preferably also be provided with an elongated (rectangular) recess  122  having a rubber or polymeric mat  124  disposed on a floor thereof, which may be used to hold tools or drills awaiting sharpening and/or tools or drills that have been sharpened. The recess is also preferably sized such that the recess can be used to determine whether a particular drill is too long to be sharpened in the unit. This may be accomplished by forming the recess such that it can receive therein drills or tools up to the maximum length that can be accommodated in the grind chamber.  
         [0032]     A further external feature of the device is the provision, in main base  102 , of a grinding wheel storage recess  126 . This recess is preferably sized to retain a plurality of spare grinding wheels, and/or grinding wheels having different grinding characteristics, in a series of slots  128  provided in the recess. The slots  128  are adapted to retain the additional grinding wheels in an upright, spaced-apart relation.  
         [0033]     Turning to the internal operating components of the tool sharpener,  FIGS. 1 and 2  illustrate that the sharpener preferably employs an infeed stage subassembly  200 , a cross-feed stage subassembly  300 , a swing subassembly  400 , a grinding wheel subassembly  500 , a chuck subassembly  600 , and an electronics subassembly  700 .  
         [0034]     The infeed stage subassembly  200  is operably connected to the chuck subassembly  600 , and is adapted to move the chuck in an “axial” direction (along an axis parallel to the axis on which the grinding wheel rotates) toward or away from the grinding wheel subassembly  500 . The cross-feed stage subassembly  300  is operably connected to the grinding wheel subassembly  500 , and is adapted to move the grinding wheel subassembly in a “transverse” direction (normal to the axis on which the grinding wheel rotates), in order to position the grinding wheel  502  and/or honing brush  510  relative to the tool being sharpened.  
         [0035]     Both the infeed stage subassembly and the cross-feed stage subassembly operate using step motors and lead screws to drive guide covers along guide rails. Looking first at the infeed stage subassembly  200  (see  FIGS. 1, 2  and  3 ) a motor-end plate  202  and a switch-end plate  204  are mounted in main base  102 , with a guide rail  206  extending therebetween. The guide rail may preferably be mounted to rail supports  208 ,  210  disposed at the two end plates. A step motor  212  is mounted at one end of the subassembly, and is operatively coupled to a lead screw  214  extending within the subassembly  200  from motor end-plate to a distance sufficient to give guide cover  216  the necessary range of motion along the axial direction.  
         [0036]     An infeed stage sensor  218  ( FIG. 3 ) is mounted by sensor mount  220  to the switch-end plate  204 . The function of this sensor will be discussed later in the specification.  
         [0037]     Referring now especially to  FIG. 3 , it can be seen that the moving components of the infeed stage subassembly  200  are preferably to be fully enclosed. It was determined, in designing the infeed stage subassembly  200 , and cross-feed stage subassembly  300 , which are more generically referred to as “linear stages”, that known schemes for protecting bearing components, including the guide rail, would not provide adequate protection in this environment. The infeed stage subassembly is thus provided with two bellows elements  222 ,  224 , which are secured between the motor-end plate  202  and a facing end of guide cover  216 , and between the switch end plate  204  and the end of the guide cover  216  facing that plate. The assembly of the two end plates  202 ,  204 , the two bellows elements  222 ,  224  and the guide cover  216  completely surrounds and isolates the guide rail  206  and virtually eliminates the intrusion of grinding debris into this area. The bellows elements  222 ,  224 , may be constructed in a known manner, with rigid or semi-rigid mounting plates  226  at the two ends, and a flexible or pliant material forming the bellows.  
         [0038]     The cross-feed stage subassembly  300  is constructed in much the same way as is infeed stage subassembly  200 . A main difference is that the infeed stage subassembly is mounted to main base  102  such that the lead screw moves guide cover  216  in an axial direction, whereas the cross-feed stage subassembly  300  is oriented at a right angle to the infeed stage, so that the guide cover  316  is moved in the transverse direction. The other main difference is that these two subassemblies are operatively coupled to different subassemblies or components disposed within grinding chamber  10 .  
         [0039]     The cross-feed stage subassembly has a motor end plate  302 , a switch-end plate  304 , a guide rail  306 , rail supports (one shown at  308 ), a step motor  312 , a lead screw  314  operatively coupled thereto, and a guide cover  316 . The cross-feed stage subassembly  300  will also preferably have a fully enclosed guide rail, employing bellows as does the infeed stage subassembly. These are not shown in  FIGS. 1 and 2 , however, in order that the internal components may be seen.  
         [0040]     Turning back to the infeed stage subassembly, it can be seen that infeed guide cover  216  is operatively coupled to lead nut  228  ( FIG. 3 ), and thus guide cover  216  moves along lead screw  214  as step motor  212  turns the lead screw  214 . As can best be seen in  FIG. 2 , guide cover  216  has a swing step motor  404  mounted to an upper surface thereof. Swing step motor  404  is operatively coupled, through an opening between wall  130  of main base  102  and side cover  108 , to a housing  406  of swing subassembly  400 . The swing step motor  404  and swing subassembly  400  (which houses chuck subassembly  600  as well) are thus moved in the axial direction by infeed stage subassembly  200 .  
         [0041]     Swing step motor  404  operates to swing or tilt the swing subassembly  400 , to tilt the tool to be sharpened in a substantially vertical plane normal to an axis of rotation of the shaft of step motor  404 . This allows the tool or drill being sharpened to be presented at a range of angular orientations relative to the grinding wheel  502 . Swing step motor  404  is operatively connected to and is controlled by central processor  20 , as are all of the step motors employed in the sharpening device.  
         [0042]      FIGS. 2 and 4  are used to illustrate the swing subassembly  400  in greater detail. The housing  406  of swing subassembly houses chuck subassembly  600  and a belt drive system  408  for rotating the chuck, and the drill or other tool held therein, about the longitudinal axis of the drill or other tool.  
         [0043]     Swing subassembly housing  406  has a mounting flange  410  extending forwardly therefrom, which is used to mount housing  406  to step motor  404 . Positioned above mounting flange  410  is a tool rotation step motor  412  having a shaft  414  protruding through opening  416  in housing  406 . The step motor shaft  414  is operatively connected to drive gear  418 , and a drive belt  420  loops around drive gear  418  and a chuck drive gear  604  disposed on chuck subassembly  600 , and passes over idler roll  424 . In this manner, tool rotation step motor  412 , under the control of central processor  20 , can rotate the chuck  600 , and thus the tool retained therein, about the longitudinal axis of the tool, in order to present different parts of the tool point surface to the grinding wheel during sharpening. The tool rotation step motor is also used at the beginning of the sharpening cycle to properly orient the drill to the proper grind position.  
         [0044]     The swing subassembly  400  also contains a solenoid  422  which is operable to lock the chuck to prevent the chuck from rotating during the time that the operator is installing and removing the drill. The solenoid  422  is automatically actuated to lock the chuck when the guard door  112  is open, and when no sharpening cycles are active. This makes the loading and unloading of the drill or other tool by the operator a very simple exercise, in which the drill is inserted into the central opening  608  of chuck  600 , and chuck knob  610  is turned to tighten the chuck jaws  612  against the drill (see also  FIG. 6 ).  
         [0045]     The grinding wheel subassembly  500  is operatively coupled to and carried by the cross-feed stage subassembly  300 . In particular, a grind motor  504  is mounted to the guide cover  316 , and a drive shaft  506  and drive pulley  508  ( FIG. 5 ) extend through a wall  132  in main base  102 , and into the grind chamber  10 . The drive pulley is operatively coupled to grinding wheel  502  and honing brush  510 , such that the drive pulley will rotate these elements. Honing brush  510  may be secured to grinding wheel  502  in a preferred embodiment, and thus would be operatively coupled to the drive pulley via the grinding wheel.  
         [0046]     Grinding wheel  502  and honing brush  510  are preferably enclosed within a grind housing  512  comprising a rear housing member  514  and a front cover  516  which, when joined to rear housing member  514 , encloses all but a small portion of the grinding wheel and honing brush. The front cover  516  is designed to be easily removable from rear housing member  514 , in order that the grinding wheel and/or the honing brush may be replaced as necessary or as desired.  
         [0047]     Grind housing  512  is preferably shaped to provide a lower chamber  518  adjacent the area in which grinding wheel  502  and honing brush  510  are located. Front cover  516  has an opening and an annular protrusion  520  adjacent this chamber  518 , in order to permit a vacuum hose  522  ( FIGS. 11, 12 ) to be fastened thereto. Main base  102  has an opening  134  leading to an exterior of the unit, to allow the vacuum hose  522  to connect at one end to protrusion  520 , and to extend out of the unit to a quiet, low speed vacuum system  524 . The vacuum system pulls the debris generated in the sharpening operation and falling into chamber  518  out of the sharpener. The vacuum system  524  preferably includes a filtration system  526  which protects the operating parts of the vacuum system from the potentially damaging grit and debris, and further protects the machine operator from any health risks associated with this debris.  
         [0048]     Front cover  516  has a slot  530  extending laterally from a point near the center of the grinding wheel  502  out past the outer peripheral edge of the grinding wheel. This slot  530  thus exposes a portion of the grinding wheel  502  and honing brush  510 , to permit those elements to engage a tool to be sharpened and honed, as desired. Slot  530  must be of sufficient width to accommodate the larger drill and tool diameters, and to provide adequate clearance for the grinding wheel, taking into account the range of angles that the drill points will be sharpened to and the position of the drills when presented to obtain such angles. The slot  530  is preferably not oversized to any extent, in that this would result in more of the debris from the sharpening operation possibly escaping into the grind chamber  10 .  
         [0049]     Grind motor  504  is provided with a cooling shroud  560 , through which cooling air is passed, in order to lower the operating temperature of the motor. This will have the effect of maximizing motor performance and increasing brush life. In the present design, it was found to be advantageous to employ a small amount of bleed air from the vacuum system, introduced into the shroud at a vacuum nipple  562 , which passes between the shroud  560  and the motor casing (inside of shroud  560 ) and is exhausted. The drawing of this air over the motor casing was demonstrated to be an effective way of maintaining the motor temperature under a specified maximum temperature.  
         [0050]     Another feature of the grind motor  560  is that the current drawn by the motor, which may preferably be a DC motor operating on  115 / 230  VAC supply and having a nominal current consumption of 1.5 A, is monitored in order to determine and control the force being exerted on the grind wheel while a drill or other tool is being sharpened. The rate of change and magnitude of the grind motor current consumption is then used to modulate (e.g., slow down and possibly stop) the motion of the infeed stage subassembly, the swing subassembly, the tool rotation subassembly, and the cross feed stage subassembly simultaneously. This will operate to prevent excessive grinding pressure being exerted, which leads to degradation of the grinding wheel surface, as well as to overheating and burning of the tool. The control of this coordinated motion will be dependent on both the diameter of the tool and the material from which the tool is made.  
         [0051]     A compact chuck subassembly  600  is illustrated in  FIG. 6 . Once assembled, this chuck subassembly is fitted onto swing assembly  400 , as is best seen in  FIGS. 2 and 4 . Chuck subassembly  600  comprises a chuck knob  610  and a chuck spindle  614  which retain therein a plurality (preferably six) chuck jaws  612  and their respective jaw springs  616 . The chuck jaws are maintained in their radial orientation by slots  618  provided on an internal tapered surface of chuck spindle  614 , as well as by radial slots  620  provided on backing screw or closing screw  622 . A jaw spring retainer  624  is also provided at the rearward end of the jaw springs  616 .  
         [0052]     An annular drive gear  604  is mounted to the exterior of the chuck spindle  614 , so that the chuck subassembly can be rotated during the sharpening process. A bearing structure  628  is also mounted to the chuck subassembly  600  to facilitate rotation thereof once mounted in swing subassembly housing  406 .  
         [0053]     A diameter detect rod  630  is attached to backing or closing screw  622 , which will, once chuck subassembly  600  is fully assembled, protrude through the chuck spindle  614 . Since backing screw  622  is moved forward as the chuck knob is turned to tighten the chuck jaws onto the drill which has been placed in the chuck, the distance to which diameter detect rod  630  protrudes from the chuck subassembly will have a direct relation to the diameter of the drill retained therein. This feature is advantageously used to detect the diameter of the drill to be sharpened without the need for very sophisticated and expensive sensors.  
         [0054]     Mounted to the exterior of grind housing  512  is an alignment subassembly  550 , which includes an alignment plunger assembly  552 , a fiber optic sensor  554 , and a material take off sensor  556 . The alignment subassembly is used by the tool sharpener, in conjunction with the central processor  20 , to automatically determine certain pertinent parameters or details of the drill or other tool to be sharpened. Alignment plunger assembly  552  is used to aid in sensing the length of the portion of diameter detect rod  630  protruding from chuck subassembly  600 . This is accomplished by advancing the swing subassembly housing  406  toward alignment plunger  552 , with the alignment plunger  552  positioned to engage the tip of the advancing diameter detect rod. Once contact is made, the plunger is pushed into plunger housing  553 , and trips or triggers a switch  551  in the alignment plunger assembly  552 , and a signal is sent to the infeed stage subassembly to cease advancing the swing subassembly. The length of the protruding portion of rod  630  is determined by the position at which the swing subassembly housing is stopped. Central processor  20  is programmed to be able to correlate this stopped position to a length of the protruding portion of rod  630 , and also to correlate this length to a diameter of the drill or other tool retained in the chuck. The thus-determined drill diameter information is later used by the central processor in controlling the various aspects and stages of the sharpening process.  
         [0055]     The length of the portion of the drill  01  protruding through chuck subassembly  600  is also automatically determined through the use of alignment plunger  552 . In this case, the alignment plunger  552  and the drill  01  are brought into axial alignment by shifting the alignment plunger transversely, and the drill  01  is advanced into contact with the front surface of plunger  552 , triggering the switch  551  in the pin, and halting the advance of the swing assembly. Again, the position of the swing subassembly housing on the infeed stage assembly is used by central processor  20  to determine the length of the portion of the drill extending forwardly or sticking out of chuck subassembly  600 . This information is used by central processor  20  in controlling the amount of infeed to use during the sharpening process, which controls how much material is to be ground off in the sharpening process.  
         [0056]     The fiber optic sensor  554  is employed to characterize (or crudely map or image) the cutting edge of the drill to be sharpened. The fiber optic sensor  554  is preferably constructed and installed on the subassembly to have a focal point on the order of several millimeters, for example seven millimeters, in front of the lens  555  of the sensor. The cross-feed subassembly  300  is used to move the sensor into axial alignment with the drill, and the infeed subassembly is used to move the cutting edge of the drill into the focal region of the fiber optic sensor  554 . These steps, as are nearly all others, are preferably performed automatically, under the control of central processor, which has these pre-sharpening data gathering routines programmed or embedded therein.  
         [0057]     The fiber optic sensor  554  is used to detect multiple points along the cutting edge of the drill  01  as the drill is rotated into different positions. Processor  20  is provided with an embedded algorithm or program that is capable of determining the web thickness of the drill using the data obtained by the fiber optic sensor. In addition, this data enables processor  20  to determine the orientation of the drill being held by the chuck. The processor  20  is then able to send a command to the tool rotation step motor  412  to rotate the drill as necessary to properly orient the drill for the ensuing sharpening operation. The processor  20  uses the calculated web thickness in controlling the position of the drill during the sharpening operation.  
         [0058]     As a further pre-sharpening data gathering step, material take-off (MTO) sensor  556  is used to determine when the drill will first contact the grinding wheel, so that the processor  20 , infeed stage subassembly  200 , and grind motor subassembly  500 , will have advance notice as to when the contact and grinding will actually begin as the drill is advanced toward the grinding wheel. In this step, cross-feed stage subassembly  300  moves laterally to axially align the MTO sensor  556  with the drill  01 . Processor  20  controls swing subassembly to position the drill at the appropriate orientation to sharpen the drill to the angle selected by the operator. The infeed stage subassembly advances the drill into contact with MTO sensor  556 , which has a switch  557  that operates to cause cessation of the advance of drill  01 . Processor  20  is thus able to determine from the stopped position of the swing subassembly when contact will first be made between the thus-positioned drill and the grinding wheel.  
         [0059]     This feature is especially useful when a drill is to be sharpened to a different point angle than it originally had. When this information is known, the processor  20  can slow the infeed rate just prior to the anticipated contact, so that the drill is not advanced at an excessive speed, and the processor can begin monitoring the current reading of the grind motor, so as to further control the infeed rate to prevent excessive pressure being exerted on the grind wheel. This further prevents overheating and burning of the cutting edge of the drill. The use of the disclosed MTO sensor  556  is an inexpensive way to obtain this initial process control.  
         [0060]     The limit switches used in the various subassemblies merit special discussion. Limit switches are provided in each of the infeed stage and cross-feed stage subassemblies, the switches being mounted in sensor housings or mounts  220 ,  802 , for the infeed and cross-feed stages, respectively, as well as in the swing subassembly (not shown), and in the chuck or tool rotation subassembly, where the switch is designated at  806  ( FIG. 4 ). These switches are preferably inexpensive optoelectronic sensors, however, with the control logic employed, these inexpensive sensors will allow fast and highly accurate operation.  
         [0061]     The fast, accurate operation is obtained by using two sensing stages. First, a digital logic level is used, whereby motion into the limit switch may be fast, and is digitally detected, albeit not with high accuracy. Once a preset digital trip point is hit, the speed is reduced and the sensing changes to an analog sensing. Motion of the slowed element is then stopped at a preset analog voltage, which is highly accurate and precise.  
         [0062]      FIGS. 14A  and B illustrate an example of the operator interface  900  presented at console  118 .  FIG. 14A  is the main setup screen, and  FIG. 14B  represents a subsequent screen that is presented to the operator after the operator has initially selected the “quick start” feature at the main setup screen, which is expected to be used in most instances in sharpening drills. The other choices presented on the main startup screen are provided for advanced users to customize the sharpening operation to their specific and unique needs.  
         [0063]      FIG. 14A  shows a point angle selection button/icon  902 , a material removal icon  904 , a drill diameter size icon  906 , a web thickness selector icon  908 , a hone selection icon  910 , a point type grind selector icon  912 , a split point selector icon  914 , a relief angle selector  916  (for lip relief), a drill material selector icon  918 , a memory open icon (for settings stored in memory)  920 , the “quick start” icon  922 , and a maintenance icon  924 .  
         [0064]     As noted previously, the central processor is programmed with defaults and automated routines to handle most of these functions and selections automatically. For example, the material removal in the sharpening process has a default value (used in the “quick start” routine, and if not otherwise overridden in manual mode) that will minimize the amount of material removed in the sharpening process, for example, in the range of about 0.005 to 0.008 inches. This will prolong the life of the drill, by permitting more resharpenings. However, if the cutting edge of the drill is damaged, as by a nick or gouge, then additional drill material would need to be removed in order to present a uniform new cutting edge. In such instances, the material removal icon would be pressed, in order to provide the operator with additional choices as to the amount of material that is to be removed during the sharpening operation.  
         [0065]     In continuing with the example of the primary mode of operation, the operator would insert a drill to be sharpened into the chuck, and the operator would tighten the chuck and close the guard door  112 . The operator would then touch the “quick start” icon  922 , and would be presented with the interface or screen illustrated in  FIG. 14B . At this screen, the operator would select one of four standard point styles or types (conic or facet: no split or X-split), and one of the two point angles (defaults to  1180 , toggles to  135  upon touching). The operator would then press a “cycle start” button (one of those shown at  120 ), and the tool sharpener will automatically sharpen the drill. Without any overrides being made, the automated sharpening process will include the following steps (which have previously been described in discussing the components that perform the steps): 
        determining the diameter of the drill to be sharpened;     determining the length of the portion of the drill protruding from the chuck;     determining the web thickness of the drill;     properly orienting the cutting edge of the drill for the sharpening procedure;     determining the point of infeed at which contact will be initiated between the drill and the grinding wheel;     controlling the infeed stage subassembly, the swing subassembly, the tool rotation subassembly, and the crossfeed stage subassembly as necessary to grind the cutting edge of the drill to remove material therefrom in sharpening the drill;     monitoring the current drawn by the grind motor in order to control the amount of pressure being exerted on the grinding wheel; and     when a honing step is to be performed, moving the grinding wheel assembly laterally to present the honing brush to the newly sharpened drill cutting edge.        
 
         [0074]     The central processor  20  in this tool sharpener is also capable of storing a number of custom sharpening routines programmed by the operator by using the various options presented at the main setup screen on console  118 .  
         [0075]     The sharpener is preferably provided with both cubic boron nitride (CBN) and diamond coated or plated wheels, which are standard in the field. The wheel coatings, typically known as a superabrasives, permit the sharpening of high strength steel (HSS), cobalt and carbide cutting tools.  
         [0076]     Additional features and functions provided by the tool sharpener described and shown herein will be readily apparent to those having ordinary skill in the art upon reading this disclosure. The foregoing discussion of the preferred embodiments of the invention is for illustrative purposes only, and is not intended to limit the scope of the invention.

Technology Category: b