Patent Publication Number: US-2012024125-A1

Title: Loop cutter knife fixture with replaceable blades

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to improvements in devices and methods for cutting food products such as vegetable products, and particularly such as raw potatoes and the like, into spiral or helical shaped pieces. More particularly, this invention relates to a rotatably driven knife fixture having relatively inexpensive and easily changed cutting blades. 
     Production cutting systems and related knife fixtures are generally well known in the art for cutting vegetable products such as raw potatoes into spiral or helical shaped pieces, preparatory to further production processing steps such as blanching and parfrying. In this regard, one typical production system comprises an hydraulic cutting system wherein a so-called water knife fixture is mounted along the length of an elongated tubular conduit. A pumping device is provided to entrain the vegetable product such as raw potatoes within a propelling water flume for cutting engagement with knife blades of the water knife fixture. The vegetable product is pumped one at a time in single file succession into and through the water conduit with a velocity and sufficient kinetic energy to carry the vegetable product through a relatively complex knife fixture which includes rotary cutting blades, including slab and strip blades, to sever the product into a plurality of smaller pieces of generally spiral or helical shape. The cut pieces are then carried further through a discharge conduit for appropriate subsequent processing, including cooking or blanching, parfrying, freezing and packaging steps, for subsequent finish processing and serving to customers as loops, twirls, curly fries, etc. 
     Examples of such hydraulic cutting systems and related rotary knife fixtures are found in U.S. Pat. Nos. 5,168,784; 5,179,881; 5,277,546; 5,343,791; 5,394,780; 5,394,793; 5,473,967; 5,992,287; and Re. 38,149, all of which are incorporated by reference herein. Persons skilled in the art will recognize and appreciate that mechanical production feed systems may be employed in lieu of hydraulic feed systems, as described in U.S. Pat. Nos. 5,097,735; 5,167,177; 5,167,178; and 5,293,803, which are also incorporated by reference herein. 
     One common problem associated with rotary knife fixtures designed to cut potatoes and the like into spiral or helical pieces relates to the need for periodic re-sharpening of the slab and strip blades. In many cases, the knife fixture is formed with a unitary construction to provide a robust or sturdy component that can survive a production environment for several years. However, the knife fixture must be periodically removed and the blades thereof re-sharpened to maintain production cut quality over an extended period of time. Typically, the entire knife fixture is removed and replaced by another knife fixture with sharpened slab and strip knives, while the slab and strip knives of the removed knife fixture are re-sharpened. This knife fixture changeover process is relatively costly, since it is necessary to remove the entire knife fixture from the cutting apparatus, and to maintain multiple and relatively expensive spare knife fixtures with re-sharpened slab and strip knives in order to maintain several parallel cutting lines in production service. 
     The present invention is directed to an improved rotary knife fixture of the type used to cut a raw vegetable product such as a potato into spiral or helical shaped strips, wherein the slab and strip knives are conveniently formed from an inexpensive material such as sheet metal or the like, and are adapted for quick and easy disassembly from the knife fixture for re-sharpening, and for similar quick and easy assembly of a re-sharpened set of cost-efficient slab and strip knives with the knife fixture for resumed production. As a result, it is necessary only to maintain spare re-sharpened slab and strip knives for quick and easy assembly with the knife fixture. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a rotary knife fixture is provided for cutting vegetable products such as raw potatoes into spiral or helical loops, wherein the rotary knife fixture includes a blade holder supporting separately mounted slab and strip knife blades formed conveniently from a relatively inexpensive material, such as sheet metal or the like. 
     The rotary knife fixture includes a circular blade holder adapted to be rotatably driven within a vegetable product flow path, such as along an hydraulic flow conduit. The blade holder includes a cylindrical central core cutter in combination with a spiral base plate defining a radial slot between axially spaced upstream and downstream ends thereof. Small slits are formed in this blade holder for seated reception of preferably multiple U-shaped strip blades, which are in turn overlaid by a generally pie-shaped slab blade having a sharpened knife edge exposed at the radial slot of the blade holder. This slab blade is clamped onto the blade holder at an inner end thereof by seating within a radially open notch formed in the central core cutter, and at an outer end thereof by preferably multiple clamp screws. 
     The slab and strip knife blades are thus carried by the blade holder for rotation in the production flow path to cut respectively a generally helical slab from each vegetable product and then to split that slab into multiple helical loops of different diametric sizes which are discharged for further processing. When the slab and/or strip blades require re-sharpening, the cost-efficient slab and strip blades are disassembled quickly and easily from the blade holder, and replaced by similar new or re-sharpened slab and strip blades for resumed production. 
     In one preferred form of the invention when the knife fixture in used in an hydraulic cutting system, the blade holder additionally has at least one and preferably multiple open passages formed therein to accommodate relatively unrestricted flow of the hydraulic fluid, such as water, therethrough without requiring fluid bypass of the knife fixture. These open passages may take the form of axially open slots formed in the blade holder, with each slot preferably formed on a common radius. 
     Other features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate the invention. In such drawings: 
         FIG. 1  is a schematic diagram depicting an hydraulic cutting system of a type utilizing a rotatably driven knife fixture constructed in accordance with the present invention; 
         FIG. 2  is an enlarged perspective view illustrating a drive motor and cog belt for rotatably driving the knife fixture of  FIG. 1 ; 
         FIG. 3  is an exploded perspective view showing rotatable mounting of the knife fixture within a rotary bearing unit; 
         FIG. 4  is a front side perspective view of the knife fixture; 
         FIG. 5  is an exploded perspective view of the knife fixture of  FIG. 4 ; and 
         FIG. 6  is a rear side perspective view of the knife fixture. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in the exemplary drawings, an hydraulic cutting system comprises a conventional so-called water knife fixture referred to generally in  FIG. 1  by the reference numeral  10  for cutting vegetable products such as whole potatoes  12  into spiral or helical shaped strips  14  for subsequent processing. The present invention comprises a rotary driven knife fixture  10  ( FIGS. 2-6 ) for installation into the cutting system and for rotatable driving by means of a drive motor  11  or the like. The knife fixture  10  includes a relatively inexpensive or cost-efficient slab blade  16  in combination with at least one and preferably multiple strip blades  18  adapted for relatively quick and easy disassembly from the knife fixture  10  when blade re-sharpening is required, and for similarly quick and easy assembly of new or re-sharpened blades  16 ,  18  with the knife fixture  10  for resumed production. 
       FIG. 1  shows the cutting system in the form of an hydraulic cutting system comprising a tank  78  or the like for receiving a supply of vegetable products, such as the illustrative raw whole potatoes  12  in a peeled or unpeeled state. These potatoes  12  are delivered via an inlet conduit  30  to a pump  32  which propels the potatoes in single file relation within a propelling water stream or flume through a tubular delivery conduit  34  into cutting engagement with the blades (not shown in  FIG. 1 ) of the water knife fixture  10 . In a typical hydraulic cutting system, the potatoes are propelled through the delivery conduit  34  at a relatively high velocity of about 40-60 feet per second to provide sufficient kinetic energy whereby each potato is propelled through the knife fixture  10  to produce (as will be described in more detail herein) the desired elongated spiral or helical cut strips  14 . In this regard, the delivery conduit  34  may include a centering alignment device (not shown) for substantially centering each potato  12  on a longitudinal centerline of the flow passage extending through the associated knife fixture  10 , in a manner known to persons skilled in the art. The cut strips  14  travel through a short discharge conduit  36  to a conveyor  38  or the like which transports the cut strips  14  for further processing, such as blanching, drying, batter coating, parfrying, freezing, etc. 
     Persons skilled in the art will recognize and appreciate that alternative form cutting systems may be used, to include, by way of example, mechanical cutting systems wherein the vegetable products such as potatoes are mechanically delivered via a chute or hopper or the like to the knife fixture  10 . In either case, the knife fixture  10  is mounted along a production path and is rotatably driven for engaging and cutting the incoming products into the desired spiral or helical shaped strips. 
     The present invention recognizes that periodic re-sharpening of the cutting blades of the knife fixture  10  is required to maintain production cut quality over an extended period of time. In accordance with the invention, the slab and strips blades  16 ,  18  of the knife fixture  10  are formed from a relatively inexpensive or cost-efficient material, such as sheet metal or the like, and are adapted for quick and easy disassembly from and similarly quick and easy clamp-on assembly with the remaining components of the knife fixture  10 . Accordingly, comparatively dull slab and strip blades  16 ,  18  can be removed quickly and easily, when required, and replaced by new or re-sharpened slab and strip blades  16 ,  18  in a similarly quick and easy manner. This enables production to continue with minimal interruption for blade change-over. In addition, there is no requirement for obtaining and/or maintaining multiple and relatively costly spare knife fixtures. Instead, it is only required to obtain and/or maintain multiple sets of the comparatively inexpensive slab and strip blades  16 ,  18 . 
       FIGS. 2-3  show installation of the illustrative knife fixture  10  into a rotary bearing unit  20  is a position in-line with a production path for the vegetables such as the potatoes  12  ( FIG. 1 ). In this regard, the illustrative knife fixture  10  comprises a blade holder including an outer support ring  22  of generally circular shape, and having cross sectional area sufficient for providing a relatively stiff or sturdy structure capable of withstanding the rigors of a production environment over an extended period of time. This outer ring  22  includes a upstanding or forwardly projecting drive tab  23  having a size and shape to fit within a matingly shaped drive notch  24  formed in a rotatable bearing housing  25 . 
     As shown in  FIG. 3 , the bearing housing is rotatably carried within a bushing  26  carried on an enlarged plate  27  adapted for in-line installation along the production path. A flange plate  28  overlies the bearing housing  25  for sandwiching the housing  25  against an internal shoulder  29  within the bushing  26 . A driven ring  30  is mounted in turn onto the bearing housing  25  for rotation therewith. A rear-side bushing  31  is adapted for secure mounting onto a rear or aft side of the enlarged plate  27 , and includes a forwardly presented shoulder  40  for rotatably supporting and retaining the outer support ring  22  of the knife fixture  10  in place, during cutting operation. 
     The driven ring  30  of the rotary bearing unit  20  includes a circumferential array of detents  41  for registry with teeth  42  of a cog-type drive belt  43 . This drive belt  43  is in turn reeved about a drive gear  44  on an output shaft  45  of the drive motor  11  ( FIG. 2 ). Accordingly, the drive motor  11  positively drives the driven ring  30  and associated bearing housing  25  secured thereto at a known speed, preferably on the order of about 6,000 rpm in the case of the illustrative hydraulic cutting system, for correspondingly rotatably driving the knife fixture  10  by means of the inter-engaged tab  23  and notch  24 . Importantly, the cog-type drive belt  43  beneficially insures constant-speed rotatable driving of the knife fixture  10  notwithstanding periodic impact engagement of the water-propelled potatoes therewith. 
     The blade holder of the knife fixture  10  further comprises a base plate  50  extending radially inwardly from the outer support ring  22 , and terminating at a generally centrally positioned tubular core cutter  52  having a sharpened knife edge  53  formed at a front or upstream end thereof. Importantly, this base plate  50  has a generally spiral or helical shape wherein an upstream end or leading edge thereof is spaced axially about ¼ inch from a downstream end or trailing edge thereof, thereby defining a radially open slot  54  between these axially spaced leading and trailing edges. In other words, the base plate  50  is formed to extend generally spirally through one turn between these axially spaced leading and trailing edges defining the radial slot  54  ( FIG. 4 ). 
     A generally pie-shaped region, shown in the illustrative drawings to occupy an arcuate span of about 60 of the base plate  50  comprises a shallow recess  56  formed therein at a position adjacent the leading edge of the base plate  50  defining the radial slot  54  ( FIG. 4 ). In turn, within this shallow recess  56 , there is at least one and preferably multiple shallow recessed seats  58  of generally rectangular shape, the opposite ends of which include relatively small slits  60  formed to extend generally perpendicular to a radius of the base plate  50 . 
     At least one and preferably multiple, generally U-shaped strip blades  18  are provided to extend downwardly through the small slits  60  in the base plate  50 , wherein each pair of these strip blades is preferably interconnected by a short, generally rectangular bight or base piece  62 . As shown best in  FIG. 5 , the illustrative drawings show two bights  62  sized and shaped for nested respective reception into the pair of recessed seats  60 , with the opposite ends of the two bights or base pieces  62  being integrally joined with an associated pair of strip blades  18  which extend downwardly through slits  60  and a short distance beyond the base plate  50  ( FIG. 6 ). Each of these multiple strip blades  18  includes an axially extending sharpened edge presented in a direction toward the adjacent slot  54 . 
     The installed pair of bights  62  each coupled to an associated pair of the strip blades  18  are suitably and easily clamped in-place onto the base plate  50  by the overlying clamp plate including the slab blade  16 . As shown best in  FIGS. 4-5 , this clamp plate  16  has a generally pie-shaped configuration for nested reception into the shallow pie-shaped recess  56  on the base plate  50 , with a radially inner end retained within a radially open notch  64  formed in the side of the core cutter  52 , and with a radially outer end clamped securely onto the outer support ring  22  by means of an arcuate clamp segment  66  and at least one and preferably multiple mounting screws  68 . In this clamped position, the clamp plate defines the slab blade having a relatively sharp cutting edge  16 ′ exposed at the radially open slot  54  by projecting circumferentially a short distance beyond the underlying leading edge of the base plate  50 . 
     In operation, the knife fixture  10  is mounted along the product production flow path and is rotatably driven by the drive motor  11  at a speed and torque sufficient to cut each incoming potato  12  or the like into the desired spiral or helical shaped pieces  14 . The slab blade  16  initially engaging and cuts each incoming product into a spiral slab, whereby the trailing strip knives  18  in turn separate this spiral slab into multiple spiral or helical strip-shaped pieces  14 . With four of the strip blades  18  as shown, persons skilled in the art will appreciate that each incoming potato  12  or the like is cut into as many as five spiral pieces of different diametric size. The core cutter, of course, cuts a straight and generally centered strip of round cross sectional shape from each incoming potato  12 . 
     When blade removal for re-sharpening is indicated, the knife fixture  10  is removed from the rotary bearing unit  20  for quick and easy removal of the slab and strip knives  16 ,  18 . Removal from the rotary bearing unit  20  is accomplished quickly and easily by slide-out removal of the rear-side bushing  31  ( FIG. 2 ). Then, the arcuate clamp segment  66  ( FIGS. 4-5 ) is quickly and easily removed to permit lift-off removal of the clamp plate with the slab blade  16 , thereby exposing the underlying bights or base pieces  62  carrying the strip knives  18 . The strip knives  18  are easily lifted from the base plate  50  and removed from the base plate  50 , together with the slab blade  16 , for re-sharpening. Importantly, during this blade sharpening interval, the knife fixture  10  may be placed back into production service by installing a new or previously re-sharpened set of slab and strip blades  16 ,  18  onto the base plate  50  of the knife fixture  10  followed by replacement of the re-assembled knife fixture  10  into the rotary bearing unit  20 . 
     In accordance with one alternative preferred form of the invention, the knife fixture  10  may be adapted particularly for use in an hydraulic cutting system without requiring bypass flow of a propelling fluid such as water. In this regard,  FIGS. 2-6  show the base plate  50  of the knife fixture  10  to include multiple axial flow openings  70  each formed preferably on a common radius. These flow openings  70  beneficially accommodate through-flow of a propelling fluid stream in an hydraulic cutting system as shown, without requiring any fluid bypass flow arrangement. 
     A variety of modifications and improvements in and to the rotary knife fixture  10  of the present invention will be apparent to those persons skilled in the art. Accordingly, no limitation on the invention is intended by way of the foregoing description and accompanying drawings, except as set forth in the appended claims.