Abstract:
A food product slicer with a rotatable slicer knife includes a knife sharpener and a control for providing a timed sharpening operation. The control effects rotation of the slicer knife for a set knife sharpen time period when a knife sharpen input of the slicer is triggered.

Description:
CROSS-REFERENCE 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/045,072, filed Apr. 15, 2008, the entirety of which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This application relates generally to food product slicers used for slicing bulk food products and, more specifically, to a food product slicer including a timed slicer knife sharpening operation. 
       BACKGROUND 
       [0003]    Food product slicers having circular slicer knives are commonly used in restaurant and grocery businesses, among others. The use of slicer mounted knife sharpening assemblies to sharpen the peripheral edge of the slicer knife when necessary is also known. Many operators have difficulty determining when the slicer knife needs to be sharpened. The nature and extent of use of the slicer can vary widely, making the determination even more difficult. It would be desirable to provide a food product slicer that incorporates a feature that automatically identifies when the slicer knife should be sharpened. 
       SUMMARY 
       [0004]    In one aspect, a slicer for use in slicing a food product includes a slicer body, a slicer knife mounted for rotation relative to the slicer body, the slicer knife having a peripheral cutting edge, and an associated knife drive motor. A food product carriage is mounted to the slicer body for reciprocating movement back and forth past a cutting zone of the slicer knife. A controller is operable to initiate a sharpen knife annunciator based upon at least one operating parameter of the slicer, the controller associated with the knife drive motor to effect operation thereof. A knife sharpen input device is associated with the controller, upon actuation of the knife sharpen input device the controller causes the knife drive motor to be energized for a set knife sharpening time period. 
         [0005]    In another aspect, a slicer for use in slicing a food product includes a slicer body, a slicer knife mounted for rotation relative to the slicer body, the slicer knife having a peripheral cutting edge, and an associated knife drive motor. A food product carriage is mounted to the slicer body for reciprocating movement back and forth past a cutting zone of the slicer knife. A knife sharpen input device, knife sharpen light element and sensor for detecting movement of the food product carriage are provided. A controller is associated with the knife drive motor, the knife sharpen input device, the knife sharpen light element and the sensor. The controller is programmed to (i) monitor the sensor to maintain a count of food product carriage slicing strokes, (ii) effect illumination of the knife sharpen light element when the count reaches a set threshold, (iii) upon actuation of the knife sharpen input device, effect operation of the knife drive motor for a set time period, after which operation of the knife drive motor is automatically stopped. 
         [0006]    In a further aspect, A method of knife sharpening in connection with a food product slicer having a rotatable slicer knife involves: (a) illuminating a time-to-sharpen button on determining that the slicer knife should be sharpened; (b) subsequent to step (a), actuating the time-to-sharpen button to initiate a delayed operation of a slicer knife motor to effect rotation the slicer knife; (c) subsequent to step (b), moving a sharpener into contact with a cutting edge of the rotating slicer knife; (d) subsequent to step (c), automatically stopping the knife motor after a set time period has passed; and (e) subsequent to step (d), flashing the time-to-sharpen button to identify successful completion of the sharpening operation. 
         [0007]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side elevation of a food product slicer; 
           [0009]      FIG. 2  is a partial cross-section of a manual knife sharpener assembly; 
           [0010]      FIG. 3  is a partial cross-section of a powered knife sharpener assembly; 
           [0011]      FIG. 4  is a block diagram of a slicer control arrangement. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Referring to  FIG. 1 , a food slicing machine  10  includes housing  12  that, with other components such as an internal casting form part of the slicer body (often times also referred to as a base). Slicing machine  10  also includes a circular slicing knife  14 , gauge plate  16 , product supporting carriage  18  and a cover plate  20 . The circular slicing knife  14  is mounted to the slicer body for rotation about an axis  22  by a motor or other drive (not shown). A peripheral cutting edge  24  of the knife is exposed in a cutting region  15  of the knife that is proximate the gauge plate  16  (e.g., generally extending from approximately a seven o&#39;clock position to an eleven o&#39;clock position in the illustrated embodiment, with other variations possible). The gauge plate is movable transversely with respect to a plane defined by the peripheral edge  24  of the knife to control slice thickness, and can be located in a “zero” position wherein it is slightly raised above the cutting zone of the peripheral edge  24 . The food product carriage  18  includes tray  26  mounted on support arm  28 , which in turn may be pivotally mounted to a transport  30  that extends into the housing. The transport  30  is supported internal of the housing for linear, reciprocating movement back and forth past the slicer knife  14  in any suitable manner, variations of which are known in the art. Carriage movement may be implemented manually or automatically (e.g., as by a drive motor and belt system, by hydraulics or by other means). As food product is moved past the cutting edge of the knife in a slicing stroke, the food product on the tray  26  slides across the outwardly facing surface of the cover plate  20 , which surface may be formed with raised ridges to improve slidability. 
         [0013]    The illustrated cover plate  20  covers the peripheral cutting edge  24  of the slicer knife  14  from about a one o&#39;clock position  32  to about a seven o&#39;clock position  34 . The peripheral cutting edge  24  is shown in shadow beneath the cover plate  20 . In a twelve o&#39;clock region  36  of the slicer knife  14 , the cover plate diameter decreases to provide a space or opening at which the edge of knife can be sharpened. The cover plate  20  also extends over a ring guard  38  (only inner edge shown in shadow in  FIG. 1 ) that is disposed about the peripheral cutting edge along at least a portion of the non-cutting zone of the circular slice knife, leaving a gap between ring guard and the peripheral cutting edge as shown. The ring guard may be fixed to the housing  12  in a stationary manner, or may be fixed to the housing to permit some movement for cleaning as described in U.S. Pat. No. 5,509,337. In either case, the ring guard is positioned to protect the cutting edge  24  of the slicing knife  14 . In the illustrated embodiment, the ring guard  38  does not extend into the twelve o&#39;clock zone  36  of the slicer knife, but such zone is provided with a knife guard member  40  that moves to permit sharpening by a sharpener assembly  42  (shown only in outline in  FIG. 1 ). For example, knife guard member  40  may pivot about an axis  100  during sharpening. A small gap is provided between the knife guard member  40  and the peripheral edge  24  of the knife as shown. 
         [0014]    The configuration of the sharpening assembly  42  provided in connection with a given slicer can vary widely. Referring now to  FIG. 2 , a sharpener assembly similar to that described in U.S. Pat. No. 5,591,072 is shown. A cover  150  is coupled to a stationary block member  152 . A mounting post  154  extends from the bottom of block member  152  and may include outwardly projecting pins (not shown) for positioning in the side slots of a mount opening (not shown) that may be formed in a mount arm (not shown) of the slicer body. The block member  152  includes a through passage or cavity  160  extending from end to end thereof and in which an actuator body  162  is slidably positioned for engaging a plunger assembly  164 . The actuator body and plunger assembly operate substantially as described in U.S. Pat. No. 5,591,072 such that when actuator body  162  is moved toward the knife (e.g., to the right in  FIG. 2 ), the springs of the plunger assembly  164  are compressed and the shaft  166  is moved toward the knife  14  so as to move the sharpening stone, in the form of wheel  168 , toward the knife  14  into a sharpening position in contact with the edge  24  of the knife  14 . A stone retaining screw or bolt  169  is provided to hold the sharpening wheel  168  in place while at the same time allowing it to rotate. Alternatively, a screw may extend outward from within the block member  152  and member  169  may be a nut threaded onto the screw. As shown, the top of block member  152  includes mount posts  170 ,  172  for receiving fasteners  174 ,  176  to mount the cover  150  to the block member  152 . 
         [0015]    In one embodiment, an actuating handle or lever (not shown) may be provided for contacting the rear side  188  of the block member  152  to push the block member toward the knife  14  and move the sharpening wheel  168  from its standby position, which is the position shown in  FIG. 2 , to a sharpening position. As seen, when the stone  168  is moved toward the knife  14 , the head  189  of the bolt  169  will contact the side of the knife guard member  40  prior to the working surface  192  of the stone  168  contacting the knife  14 , which will pivot the knife guard member out of the cutting edge guarding position and into the cutting edge sharpening position. The sharpening assembly may also include a truing stone (not shown) that pivots to the right side of the knife  14  (as viewed in  FIG. 2 ) when the actuator body  162  is moved to the right to its fullest extent, as is generally shown and described in U.S. Pat. No. 5,591,072. An interlock (not shown) may be provided in connection with the knife guard member  40  to hold the knife guard member in its cutting edge guarding position, in which the sharpener assembly  42  may include an interlock actuator (not shown) for automatically disabling the interlock during a sharpening operation, to permit the knife guard member to move to its cutting edge sharpening position. A solenoid or other powered actuator (e.g., motor drive, pneumatic actuator or linear actuator) may also be provided for moving the knife guard member  40 . Alternatively, as shown in U.S. Pat. No. 4,817,480, the sharpener may be associated with the carriage when needed for sharpening. 
         [0016]    Referring to  FIG. 3 , an alternative embodiment of the sharpener assembly is shown in which a solenoid  340  is positioned at the end of an elongated block member  152 ′. The solenoid  340  includes a coil  342  that, when energized, moves plunger  344  to the right for moving the actuator body  162 . A spring  346  biases the plunger  344  into the illustrated position. Thus, the  FIG. 3  embodiment provides for automated sharpening (e.g., by pressing an input button that causes energization of the solenoid  340 ). The solenoid  340  may be energized for a set period of time such that sharpening takes place for a set period of time (e.g., such as in a range of 4 to 8 seconds, or whatever time period may be determined appropriate based upon testing). This feature assures adequate sharpening and a that same time avoids excessive sharpening that can wear the knife more quickly than desired. A similar feature could be implemented using other types of powered sharpeners. Moreover, a manually actuated sharpener could be modified to include a mechanically implemented timeout feature by which the sharpening time period could be controlled or set to be within a desired range. 
         [0017]    Referring to  FIG. 4 , an exemplary slicer control system diagram  400  is shown. A controller  402  (which may include a processor and memory, such as flash memory) is connected with a solenoid  404  that may be provided for moving the knife guard member  40 . Alternatively, solenoid  404  could be eliminated where the knife guard member  40  is manually movable as described above. Controller  402  is also connected with solenoid  340  associated with the sharpener assembly  42  ( FIG. 3  embodiment). Where the sharpener assembly  42  is manual, solenoid  340  may be eliminated. Controller  402  is connected with a knife drive in the form of motor  406 , and is also connected with a carriage drive in the form of motor  408 . The carriage  18  may be selectively uncoupled from motor  408  to also permit manual movement of the carriage. Controller  402  is also connected with a user interface display  410  and with a user input in the form of one or more input keys or switches  412 . If the display  410  is of the touch sensitive type, the display may function as a user input in addition to or in place of user input  412 . A motor encoder  414  provides feedback to the controller  402 , from which the controller can determine knife rotations if needed. Alternatively, an encoder or other sensor  416  may be associated with the knife  14  itself to track knife rotation. A sensor  418  provides feedback to the controller  402  regarding carriage position and/or movement. Sensor  418  may be as simple as an end of stroke switch or may take the form a more complex encoder arrangement. Different types of sensors, mechanical, optical or magnetic may also be sued. A motor load sensor  420  may also be provided for the knife motor  406 . A control system such as that illustrated may be configured to automatically determine when to sharpen the slicer knife in any one of a variety of techniques, as will now be described. 
         [0018]    In one technique, the controller  402  tracks a count of slicing strokes of the food product carriage  18 , based upon the feedback from sensor  418 , in order to determine when to sharpen the knife. Specifically, based upon knife testing it can be determined that, on average, a slicer knife needs to be sharpened after a given number of slicing strokes. The controller tracks the count of slicing strokes and when the count exceeds the given number, the controller outputs a knife sharpen signal (e.g., causing a buzzer or other audio annunciator  422  to output a sound, causing an LED or other visual annunciator  424  to output a visual signal and/or causing a sharpen message to be displayed on the display  410 ). In one implementation, the visual annunciator  424  may be incorporated into one of the user input buttons or switches that acts as knife sharpen trigger to the controller. Where the sharpener is manual, the slicer operator can then initiate a manual sharpening operation and actuate the user input  412  to reset the slicing stroke count once sharpening is completed. Alternatively, a sharpen sensor  426  could be mounted on the sharpener  42  to trigger a feedback to the controller  402  upon sharpening (e.g., after the sharpening wheel  168  has been fully extended for some minimum period of time). 
         [0019]    Where the sharpener is automated (as by solenoid  340 ), the knife sharpen signal could cause sharpening to take place automatically, without requiring operator input. For example, the controller  402  could automatically initiate sharpening after the slicing stroke count reaches the given number, provided the slicer is not in use (e.g., after the slicer knife and carriage have been stopped for a set time period). Alternatively, the operator may be required to trigger automated sharpening via actuation of the user input  412 , which could simultaneously serve to reset the count. 
         [0020]    In one implementation of the slicing stroke counting technique, the slicing strokes are only counted when the knife is running (e.g., as determined by the motor  406  being energized or based upon the feedback from encoder  414  or sensor  416 ). In another implementation of the slicing stroke counting technique, the slicing strokes are only counted when the knife is running and when a load on the knife driver exceeds a threshold level (e.g., as determined by the feedback from load sensor  420 ). In yet another implementation of the slicing stroke counting technique, multiple slicing stroke counts can be tracked according to food product sliced. An algorithm may be used to evaluate the multiple counts in a cumulative manner, with the algorithm taking into account the impact the type of food product has on dulling of the knife (e.g., it takes less slicing strokes of cheese to dull the knife when compared to turkey slicing strokes). In the latter implementation, the user input  412  can be utilized by the operator to input the type of food product being sliced (as by entering a product look-up (PLU) number). Alternatively, the slicer may include RFID capabilities as described in the PCT application published under International Publication No. WO 2005/004071 A1, by which the slicer can automatically determine the product being sliced based upon a sensed RFID tag of the food product. 
         [0021]    In another technique, the controller  402  may count rotations of the slicer knife  14  (as determined by feedback from encoder  414  and/or sensor  416 , or as determined by assuming a certain running speed for the knife, tracking knife on time and calculating knife rotations) in order to determine when to sharpen the knife. Specifically, based upon knife testing it can be determined that, on average, a slicer knife needs to be sharpened after a given number of knife rotations takes place. The controller tracks the count of knife rotations and when the count exceeds the given number, the controller outputs the knife sharpen signal. In one implementation of the knife rotation counting technique, knife rotations are only counted when a load on the knife driver exceeds a threshold level (e.g., as determined by the feedback from load sensor  420 ). In another implementation of the knife rotation counting technique, knife rotations are only counted when the food product carriage is moving (as determined by the feedback from sensor  418  or by energization of motor  408 ; where sensor  418  is an end of stroke sensor switch, the carriage may be considered to be “moving” (as that term is used herein) provided the sensor  418  is repeatedly tripped within a set time period, such as being tripped every 3-6 seconds for example). 
         [0022]    In yet another technique, the controller  402  may count the running time of the slicer knife (as determined by the knife motor  406  being energized or ad determined by feedback from encoder  414  and/or sensor  416 ) in order to determine when to sharpen the knife. Specifically, based upon knife testing it can be determined that, on average, a slicer knife needs to be sharpened after running for a certain period of time. The controller tracks a time count corresponding to knife running time and when the count exceeds the given number, the controller outputs the knife sharpen signal. In one implementation of the knife running time counting technique, the run time is only counted when the food product carriage is moving (as determined by feedback from sensor  418  or by energization of motor  408 ). 
         [0023]    In determining whether the count for the selected knife use characteristic exceeds a set count, the count could be a count up from zero to the set count (in which case count reset is back to zero) or the count could be a count down from the set count to zero (in which case count reset is back to the set count). 
         [0024]    In tracking the count of the selected knife use characteristic, in one embodiment the controller may actually maintain a digital count value in memory, with the value being incremented or decremented as the case may be. Other types of digital counter implementations could also be used. In another embodiment the controller may include an analogue counter, such as one in which voltage pulses (e.g., one pulse corresponding to one count) are input to an integrator. When the voltage output of the integrator reaches a specific voltage, the set count is considered to be reached Other types of analogue counters could also be used. Accordingly, as used herein, it is not necessary for a digital number to be stored and incremented/decremented in order for an apparatus to fall within the scope of the meaning of the term “track a count” or “tracking a count” as used in the claims. 
         [0025]    In another embodiment, when the annunciator indicates that the knife needs to be sharpened, the operator could press a button that results in a knife sharpen signal. The slicer controller may responsively trigger operation of the slicer knife motor for a specific period of time (e.g., a time period known to provide suitable knife sharpening). In one implementation the slicer knife motor may be energized immediately in response to the knife sharpen signal and continuously energized for a suitable time period (e.g., 20 seconds, 15 seconds etc.). During the set time period the slicer operator manually moves the sharpener into sharpening position and waits for the knife motor to stop, at which point the operator moves the sharpener back the standby position and the sharpening operation is completed. The count is reset and the sharpen knife annunciator is de-energized. In another implementation the slicer knife motor may be maintained in an off/unenergized condition for a set time period after the knife sharpen signal (e.g., a timer period sufficient to enable the slicer operator to prepare to sharpen, such as 10 seconds, and then the slicer knife motor is energized for a set time period). During the pause between the knife sharpen signal and energization of the knife motor, the slicer operator manually places the knife sharpener into the sharpening position. Upon completion of the set time period the sharpener is moved back to the standby position and the sharpening operation is complete. The count is reset and the sharpen knife annunciator is de-energized. 
         [0026]    In one example, the operator may be required to continue the button press during the full length of the knife sharpening operation in order to maintain energization of the slicer knife motor and assure that the count is reset. In this example, even though the button is pressed, slicer knife motor energization would be stopped after the set time period. If the button is not pressed for the full, set time period, the controller assumes that the sharpening operation was not completed and the count is not reset and the sharpen knife annunciator is maintained on. 
         [0027]    On specific implementation technique is as follows: When the number of carriage cycles or slicing strokes reaches a set count for sharpening, a time-to-sharpen button on the slicer is illuminated to indicate to the operator that sharpening is needed. To sharpen, and with the knife off, the operator pushes and holds the time-to-sharpen button. There will be a delay (e.g., about 2 to 6 seconds, such as about 3 seconds) before the knife blade begins to rotate. The operator manually engages and holds the knife sharpening stone assembly into contact with the edge of the rotating knife and waits until the knife motor automatically stops (e.g. the time period for automated knife rotation could be set at about 10 to 20 seconds, such as about 15 seconds). Once knife rotation is ceased by the slicer controller, the operator releases the sharpening stone assembly, moving it out of contact with the knife edge and releases the time-to-sharpen button. The time-to-sharpen light will flash once or twice and then turn OFF, reflecting successful completion of the sharpening operation and the time-to-sharp count will also be reset. It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible.