Patent Publication Number: US-8978530-B2

Title: Cutting apparatus employing a magnet

Description:
TECHNICAL FIELD 
     The present invention relates to a cutting apparatus which is employed in connection with equipment for detecting defects in elongated articles and for cutting the defects from the articles as the articles are being processed in a high output production facility. 
     BACKGROUND OF THE INVENTION 
     The present invention as disclosed in the paragraphs which follow can be employed in connection with an inspection and cutting apparatus such as what is shown in U.S. Pat. No. 4,520,702. The content of this previous patent is incorporated herein by reference. U.S. Pat. No. 4,520,702 addressed a perceived problem then existing in the industry relative to the processing of elongated articles such as sliced potatoes utilized for frozen French fries, and wherein the elongated articles were first aligned in transversely spaced lanes and then passed beneath individual lane electro-optical cameras for inspecting the French fries for defects. In the previous prior art arrangements, if defects were encountered, one or more knives on a rotating wheel was projected or propelled from the wheel to cut the defect from the article. Various earlier U.S. Patents such as U.S. Pat. Nos. 3,543,035 and 3,664,337 describe such earlier devices. These prior art devices were deemed to be not very effective because it was very difficult to process large volumes of product utilizing the equipment illustrated in these previous prior art patents. U.S. Pat. No. 4,520,702 also describes various other prior art attempts to solve the perceived limitations on the processing of elongated articles that might have defects. The inventors in U.S. Pat. Nos. 4,520,702 and 6,923,028 for example, describe an invention which provides high volume inspection and cutting for removing defects from elongated articles with resulting equipment that is quite inexpensive and robust relative to its production capacity. 
     The device as shown in U.S. Pat. No. 4,520,702 for example, has been widely embraced by the food processing industry and has operated with a great degree of success through the years. While this apparatus as described in this prior art patent has operated quite reliably for several decades, there have been perceived shortcomings which have detracted from its usefulness. Chiefly, two perceived shortcomings have become evident through the continued use of the earlier mentioned apparatus. Firstly, and only occasionally, individual cutter knives employed in the apparatus as described in U.S. Pat. No. 4,520,702, when rotated at predetermined operational speeds occasionally will prematurely move or be ejected to a radially outwardly extended cutting position and engage the elongated food product being processed without first being deployed by the cutting apparatus. This premature deployment of a cutting knife to the radially extended cutting position could occasionally cause the cutting knife to become damaged. In addition to the foregoing, the cutting knives employed, to date, have been fabricated from a synthetic material, and due to normal wear and tear, and routine operating conditions, such prior art cutting blades occasionally break and need to be replaced. This type of wear related failure is expected, from time-to-time, in devices of this type, however, depending upon the product to be cut, and inspected, such replacement of cutting blades can sometimes be time consuming, and inconvenient during typical food processing plant operations. 
     Therefore, a principal object of the present invention is to provide an improvement to the inspection cutting apparatus as seen in U.S. Pat. No. 4,520,702 and which provides improved performance and other operational characteristics not possible, heretofore, in a device such as what has been described in this previous patent. 
     SUMMARY OF THE INVENTION 
     A first aspect of the present invention relates to a cutting apparatus which includes a cutter knife which is reciprocally moveable from a first non-cutting position, to a second, cutting position; a track member mounted adjacent to the cutter knife, and which mechanically cooperates with the cutter knife so as to define, at least in part, the first non-cutting position, and the second, cutting position of the cutter knife; and a magnet is mounted on the track member and which releasably magnetically restrains the cutter knife when the cutter knife is in the first non-cutting position, and the second, cutting position. 
     Another aspect of the present invention relates to a cutting apparatus which includes a cutter knife supported for reciprocal movement along a path of travel which has opposite ends; a source of fluid pressure selectively delivered to the cutter knife to move the cutter knife in a given direction along the path of travel from one end to the other; a track member positioned adjacent to, and mechanically cooperating with the cutter knife, and which is effective in defining the reciprocal movement of the cutter knife along the path of travel; and a magnet is mounted on the track member, and which is effective in magnetically attracting and partially restraining the cutter knife when the cutter knife is located at the opposite ends of the reciprocal path of travel. 
     Still another aspect of the present invention relates to a cutting apparatus which includes an axle; a circular knife support ring supported for rotation about the axle, and wherein the knife support ring has a peripheral edge, and further experiences centrifugal force when rotated; a plurality of cutter knives moveably supported by the knife support ring, and which are individually, radially, reciprocally moveable relative thereto; a source of fluid pressure selectively delivered to the respective cutter knives for selectively propelling the individual cutter knives along a path of travel which is radially, outwardly oriented relative to the knife support ring; an annular track member mounted on the axle, and located adjacent to the knife support ring, and wherein the annular track member has an outside peripheral edge, and further defines a plurality of tracks which mechanically cooperate with the plurality of cutter knives so as to cause the respective cutter knives to move radially inwardly, and outwardly, relative to the peripheral edge of the knife support ring, and along the path of travel, when the source of fluid pressure propels individual cutter knives radially outwardly relative to the knife support ring; and a magnet mounted adjacent to the peripheral edge of the of the annular track member, and which has a magnetic centripetal force which is effective so as to magnetically restrain the movement of the plurality of cutter knives in a radially outward direction relative to the knife support ring, and against the centrifugal force experienced by the knife support ring, and the respective cutter knives, when the knife support ring is rotated, and wherein the magnetic centripetal force acting on the respective cutter knives is overcome when the source of fluid pressure is applied to the respective cutter knives so as to move the respective cutter knives along the path of travel, and radially outwardly relative to the knife support ring. 
     These and other aspects of the present invention will be described in greater detail hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
         FIG. 1  shows a perspective, fragmentary view of an improved cutting apparatus of the present invention and showing the location of cutting knives in various orientations relative to the present cutting apparatus. 
         FIG. 2  is a perspective, side-elevation view of a knife support ring employed with the cutter apparatus of the present invention, and several cutting knives employed with the invention and which are positioned in various operational orientations. 
         FIG. 3  is a side elevation view of the circular knife support ring as seen in  FIG. 2 . 
         FIG. 4  is a transverse, vertical sectional view which is taken from a position along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a partial, side-elevational view which is taken from a position along line  5 - 5  of  FIG. 3 . 
         FIG. 6  is a fragmentary, exploded, side-elevational view of the magnet located on the annular track member, and several cutting knives as employed in the cutting apparatus of the present invention. 
         FIG. 6A  is a side elevational view of an alternative form of the cutting knife employed with the present invention. 
         FIG. 7  is a top plan view of the annular track member employed in the cutting apparatus of the present invention. 
         FIG. 8  is a top plan view of the magnet which is mounted on the annular track member, and which is employed in the cutting apparatus of the present invention. 
         FIG. 9  is a transverse vertical sectional view of a second form of a magnet which finds usefulness in the present invention, and which is taken from a position along line  9 - 9  of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     Referring now to a detailed study of  FIG. 1 , and following, it will be seen that the cutting apparatus  10  of the present invention includes a non-rotatable axle or support member which is generally indicated by the numeral  11 . The non-rotatable axle defines an internal cavity  12  which encloses some structural features of the prior art cutting apparatus (U.S. Pat. No. 4,520,702) which are not directly germane to the present invention, but which are more fully disclosed in U.S. Pat. No. 4,520,702. Readers are referred to that patent to understand the structure of the axle employed in this invention, and illustrated in this drawing. In particular, the present invention  10  and more particularly the internal cavity  12  of the fixed axle  11  is supplied with a source of fluid pressure generally indicated by the numeral  13 . This source of fluid pressure (typically compressed air) travels down the internal cavity, and is then selectively released by valve assemblies (not shown) through the apertures  14 . This fluid pressure is applied to, or against the respective cutting knives so as to move them from a first non-cutting position to a second cutting position. The specifics of the movement of the respective cutting knives, and their structures, will be discussed in greater detail, hereinafter. Readers are referred to U.S. Pat. No. 4,520,702 for details regarding the valve assemblies employed to selectively release fluid pressure to the cutting knives that will be described hereinafter. As earlier noted, the substance of U.S. Pat. No. 4,520,702 is incorporated by reference into this application. 
     A circular knife support ring  20  which is similar in structure to that described in U.S. Pat. No. 4,520,702 is employed in the cutting apparatus of the present invention. The circular knife support ring  20  has a main body  21  which defines a plurality of cutter knife stations  22 . The cutter knife stations allow the respective cutter knives, as will be described hereinafter, to be positioned in a predetermined annularly spaced relationship one relative to the others. This circular knife support ring further has an outside peripheral edge  23 , and an opposite, inside peripheral edge  24  which defines an aperture  25  of given dimensions as seen in  FIG. 2 . The aperture  25  is just slightly larger than the outside diametral dimension of the fixed axle  11 . The circular knife support ring  20  is operable to be drivingly rotated at a given operational speed about the fixed axle member  11  so as to position individual cutter knife stations  22  in substantial alignment, and in fluid receiving relation relative to the apertures. As seen in the side elevation view of the circular knife support ring  20 , as illustrated in  FIG. 3 , the plurality of cutter knife stations  21  are divided into several segments (6) which are spaced at approximately 60 degree orientations about the peripheral edge  23  of the main body  21 . Further detail regarding the construction, and rotation of the circular knife support ring can be found by reference to U.S. Pat. No. 4,520,702 which is incorporated by reference, herein. 
     Referring now to  FIG. 1 , and also to  FIG. 7 , it will be seen that the cutting apparatus  10  generally includes an annular track member  40  which is immovably mounted on the axle  11 , and is juxtaposed relative to the circular knife support ring  20 . The annular track member as seen in  FIG. 7  has a main body  41  which is defined by an outside, substantially circular peripheral edge  42 , and an opposite, inside peripheral edge  43  which defines an aperture  44  which has a diametral dimension which is just slightly greater than the outside diametral dimension of the fixed axle  11  upon which it is mounted. The annular track member  40  further defines a first substantially circular track or race  51  which is located in a predetermined, spaced relationship radially inwardly relative to the outside peripheral edge  42 . The first substantially circular track  51  has substantially uniform dimensions of both width, and depth, and is operable to mechanically cooperate with a feature or portion of the respective cutter knives which will be discussed in the paragraphs which follow. As seen in  FIG. 7 , it should be understood that the annular track member  40  further defines a second track  52  which has a first end  53  which diverges from the first circular track  51 , and further has a second or converging end  54  which rejoins the first circular track  51  at a predetermined location which is spaced from the first end  53 . The second track  52  occupies a portion of the region of the annular track member located between the first substantially circular track  51 , and the peripheral edge  42 . The second track  52  has a portion  52 A that is located closely near the peripheral edge  42  thereof. This is clearly illustrated in  FIG. 7 . As seen by reference to  FIG. 7 , there is a region  55  of the annular track member  40 , and which is located adjacent to the first or diverging end  53  of the second track  52  and this is where a magnet  60  is mounted. The magnet  60  will be discussed in greater detail in the paragraphs which follow. It should be noted from a study of  FIG. 7 , that the second track  52  does not have a substantially uniform width dimension, but rather the first or diverging end  53  has a width dimension which is greater than the second or converging end  54  thereof. 
     It will be appreciated by a study of  FIG. 7  that the respective cutting knives  80 , as will be discussed in the paragraphs which follow, are designed to matingly cooperate, and travel along the annular track member  40 , and more specifically, the first and second tracks thereof  51  and  52  and by doing so, the annular track member  40  defines, at least in part, a reciprocal course of movement for the respective cutter knives  80 . 
     Referring now to  FIGS. 6 ,  7  and  9 , it will be seen that the cutting apparatus  10  of the present invention includes a magnet which is generally indicated by the numeral  60 , and which is mounted in the region  55  of the annular track member  40 , and which is effective in magnetically attracting, and partially restraining the respective cutter knives  60 , as will be discussed hereinafter, when the respective cutter knives are located at the opposite ends of a reciprocal path of travel which will be described hereinafter. The first form of the magnet is designated by the numeral  60 . A second form of the magnet is designated by numeral  60 A in  FIG. 9 . The structural difference in these two forms of the magnet will be discussed below. However, it should be understood that each form of the magnet operates in substantially the same way to effect the novel features of the present invention. More specifically, and as will be discussed in more detail, hereinafter, the magnet  60  is mounted on the annular track member  40 , and is operable to releasably, magnetically restrain a cutter knife  60 , as will be described, hereinafter, when the cutter knife  60  is in either a first non-cutting position or a second cutting position. The magnet  60 , as used in the present invention, has a curved main body  61 , which has a first end  62 , and a second end  63 . As will be seen in the drawing, the main body  61  has a width dimension which diminishes when this width dimension is measured from the first end, in the direction of the second end  63 . Still further, the main body  61  has an outside facing sidewall  64  which has a curvature which is substantially similar to the curvature as measured along the circumference, or peripheral edge  42  of the annular track member  40 . As will be recognized by a study of  FIG. 7 , the inside facing sidewall  65  of the magnet  60  also defines a curved surface which has a curvature which may be similar, or different, from that of the outside facing surface  64 . As will be seen from a study of  FIG. 7 , the magnet  60  is located in the region  55  which is positioned between the first or diverging end of the second track  52 , and the outside peripheral edge  42  of the annular track member  40 . As seen in the drawings, the curvature of the inside facing sidewall  65  of the magnet is substantially similar to the curvature of the first diverging end  53  of the second track  51  as defined by the annular track member  40 . As will be seen by a study of  FIG. 8 , the magnet  60  exerts a magnetic force of greater than about 0.5 Newtons which is oriented in a direction that is generally radially inwardly oriented relative to the circular knife support ring  20 . Additionally, it will be seen from the drawings that the magnet  60  comprises a main body  61  which has a first portion  71 , and a second portion  72 , which are spaced one from the other ( FIG. 6 ). Again, the principal magnetic force  73  provided by the magnet  60  is oriented generally radially inwardly relative to the knife support ring  20 . Still further, the first and second portions of the magnet  71  and  72  are spaced from each other by a spacer  74  which positions the first and second portions in predetermined spaced relationship. The spacer is typically fabricated from polycarbonate. It has a thickness dimension of about 3 mm. As should be understood by a study of  FIG. 8 , the first form of the magnet  60  has a curved main body  71 . The magnet&#39;s overall shape is such that the magnetic force exerted by the magnet is variable when measured along the length dimension of the curved main body and generally, radially inwardly relative to the annular track member  40 . The generated magnet force diminishes when measured from the first end  62 , to the second end  63 . As seen in  FIG. 8 , the magnet  60  is located near to, and inwardly relative to the outside peripheral edge  42  of the annular track member  40 , and further occupies less than about 35 degrees of the circumference of the annular track  40 . It being understood that the circumference of the annular track member  40  is measured along the outside peripheral edge  42  of the annular track member  40 . 
     Referring now to  FIG. 9 , the second form of the magnet  60 A is illustrated in a vertical, sectional view. It will be understood that like numbers indicate like structures in this figure. In this second form of the magnet  60 A, the magnetic portion comprises a single magnet  66  mounted centrally of the unitary structure. Further, the magnetic portion  66  is sandwiched between two plastic synthetic spacers each indicated by the numeral  67 . Further, to complete the structure of the second form of the magnet  60 A, the structure discussed above, is sandwiched between a pair of spaced, stainless steel magnetic shunts  68 . Again, the second form of the magnet operates in substantially the same fashion as what has earlier been described. 
     Referring now to  FIG. 1 , and following, it will be seen that the cutting apparatus  10  of the present invention employs a plurality of cutter knives which are generally indicated by the numeral  80 , and which are selectively reciprocally moveable along a given path of travel which will be discussed, below, from a first non-cutting position, to a second, radially extended cutting position relative to the circular knife support ring  20 , and annular track member  40  within which the cutter knives mechanically cooperate. More specifically, the cutter knife  80  as seen in  FIG. 6 , and following, has a leg shape main body  81  which has a first, foot shaped end  82 , and which has a blade like edge  82 A, and a leg shaft  83  extends from the first foot shaped end  82  and terminates in a second end  84 . Still further, a projection or cam follower  85  is made integral with the leg shaft  83 , and extends normally outwardly relative thereto, and is disposed in the same plane as the first foot shaped end  82 . The projection, or cam follower  85  is operable to be received in move along, and otherwise mechanically cooperate with either the first circular track  51 , or second track  52 , which is defined by the annular track member  40 . The cam follower is located approximately mid-way between the first end  82 , and the second end  83 . The movement of one of the respective cutter knives  80  into these individual tracks ( 51 ,  52 ) defines, at least in part, a reciprocal course of travel for the individual cutter knives  80 . As seen in the drawings, a gap  86  is defined between the first foot shaped end  82  and the projection  85 . This gap defines the length of the course of travel of the respective cutter knives  80 . The present cutter knife  80  is substantially similar in its overall shape to the cutter knife described in U.S. Pat. No. 4,520,702 which is incorporated by reference herein. Further, the respective cutter knives  80  are received, and slideably supported in the individual cutter knife stations  22  as defined by the circular knife support ring  20 , and which further defines, in part, the course of travel of same. Therefore, the cutter knives  80  move along a course of travel which is substantially similarly to that earlier described in the aforementioned US Patent. More specifically, and by means of the selective application of the source of fluid pressure  13  to the second ends  84 , of the respective cutter knives  80 , the individual cutter knives  80  are moved radially outwardly relative to the circular knife support ring  20  such that the projections or cam follower  85 , which typically travels along the first substantially circular track  51 , moves outwardly, and in the direction of the second circular track  52  in the area where the second track  52  diverges from the first track  51 . As the projection or cam follower  85  moves into the second track  52 , the projection  85  is magnetically attracted toward the magnet  60  therefore ensuring that the cutter knife  80 , which is being rotatably carried by the circular knife support ring  20  continues to be guided along the second track  52  and is reliably moved radially outwardly to an extended cutting position by the continued rotation of the circular knife support ring  20  relative to the fixed annular track member  40 . The extended cutting position will be discussed, below. Upon the continued rotation of the circular knife support ring  20 , the cutter knife  80  which has been placed or moved into the second track  52  by the radially outward movement of the cutter knife  80  under the influence of the exerted fluid pressure  13 , and the rotation of the knife support ring  20  relative to the fixed annular track member  40 , eventually converges with the first track  51 , and is then effectively withdrawn from the extended cutting position, and is moved radially inwardly relative to the circular knife support ring  20 , to a withdrawn, non-cutting position, as will also be discussed below. In the withdrawn, or non-cutting position, the magnet  60  is also effective in magnetically restraining the main body  81  of the cutter knife  80  by magnetically attracting the first foot shaped end  82  so as to prevent premature movement of the cutter knife  80  radially outwardly, and into a cutting position. As earlier discussed, this premature movement of the cutter knives is caused, at least in part, by the centrifugal force experienced by the respective cutter knives  80  by the rotation of the circular knife support ring  20 . As should be understood, the magnetic force exerted on the first foot shaped end  83  is easily overcome by the force exerted by the source of fluid pressure  13  applied to the second end  84  thereof. 
     As seen in  FIG. 6A , a second form of the cutting blade  90  is shown. In this form of the invention, the cutter blade  90  is fabricated from a material, only a portion of which  91  is metallic, and which can be magnetically attracted, and interact with the magnet  60  as described above. Still further, in this second form of the invention, the cutting blade  90  may have a non-metallic portion  92  which is not magnetically attracted to the magnet, and which would still be effective in cutting various elongated food or other products, as earlier disclosed. However, and more typically, the individual cutter knives  80  will be fabricated from a uniform metal substrate which is magnetically attracted by the magnet and can be restrained both in the non-operational or non-cutting position, and the second cutting position as will be discussed below. The preferred form of the cutting knives are typically fabricated from  410  stainless steel, and have a typical length dimension of about 66 mm. and a thickness dimension of about 1.5 mm. In the present invention, the cutter knives  80 , as indicated above, are movable along a reciprocal path of travel  100  between a first, withdrawn or non-cutting position  101 ; and a second, extended or cutting position  102 , as seen in the drawings. As earlier noted, the magnet  60  or  60 A which is mounted on the annular track member  40  is effective in magnetically attracting and partially restraining the cutter knife when the cutter knife is located at the opposite ends of the reciprocal path of travel  100 . Still further, when the cutter knife  80  is in the first non-cutting position  101 , the magnet  60  or  60 A is effective in restraining radially outward movement which might be caused or occasioned by the centrifugal force experienced by the cutter knives  80  by the rotation of the circular knife support ring. On the other hand, when the source of fluid pressure  13  is selectively supplied to the second end  84 , it is sufficient to overcome the magnetic force acting on the first foot shaped end  83 , and moves the respective cutter knives  80  to the second, extended cutting position  102 . The magnet  60  or  60 A is effective in magnetically drawing, or acting upon the projection or cam follower  85  so that the cutter knives  80  proceed to, and are diverted into, the second track  52  as defined by the annular track member  40 , and therefore are reliably moved radially outwardly into an appropriate extended second cutting position  102  as seen in the drawings by the controlled rotation of the knife supporting ring  20 , and the interaction or cooperation of the projection or cam follower  85  with the second track  52 . As should be understood, and when no fluid pressure  13  is applied to the second end  84  of a cutter knife  80 , the projection or cam follower  85  remains in the first track  51  as the knife support ring  20  rotates relative to the fixed annular track member  40 . This maintains the cutter knife  80  in the first non-cutting position  101 . 
     Operation 
     The operation of the described embodiment of the present invention is believed to be readily apparent and is briefly summarized at this point. 
     In its broadest aspects, the present invention includes a cutting apparatus  10  having a cutter knife  80  which is reciprocally moveable from a first non-cutting position  101 , to a second cutting position  102 . A track member  40  is mounted adjacent to the cutter knife  80 , and which mechanically cooperates with the cutter knife so as to define, at least in part, the first non-cutting position  101 , and the second cutting position  102  of the cutter knife  80 ; and a magnet  60  is mounted on the track member  40  and which releasably magnetically restrains the cutter knife  80  when the cutter knife is in the first non-cutting position  101 , and the second cutting position  102 . 
     More specifically, the cutting apparatus  10  of the present invention includes a cutter knife  80  which is supported for reciprocal movement along a path of travel  100  which has opposite ends  101  and  102 . A source of fluid pressure  13  is provided, and which is selectively delivered to the cutter knife  80  to move the cutter knife in a given direction along the path of travel  100  from one end  101  to the other  102 . A track member  40  is provided and positioned adjacent to, and mechanically cooperates with, the cutter knife  80 , and which is effective in defining the reciprocal movement of the cutter knife along the path of travel  100 . Finally, a magnet  60  is mounted on the track member  40 , and which is effective in magnetically attracting and partially restraining the cutter knife  80  when the cutter knife is located at the opposite ends of the reciprocal path of travel  100 . 
     In particular, the present invention relates to a cutting apparatus  10  which includes an axle  11 , and wherein a circular knife support ring  20  is provided, and which is supported for rotation about the axle. The knife support ring  20  has an outside peripheral edge  23 , and further, when rotated, experiences centrifugal force. A plurality of cutter knives  80  are supported by the knife support ring  20 , and are further individually, radially, reciprocally moveable relative thereto. In the present invention, a source of fluid pressure  13  is provided, and which is selectively delivered to the respective cutter knives  80  for propelling the individual cutter knives  80  along a path of travel  100  which is radially, outwardly oriented relative to the knife support ring  20 . An annular track member  40  is fixedly mounted on the axle, and located adjacent to the rotatable knife support ring. The annular track member  40  has an outside peripheral edge  42 , and further defines a plurality of tracks  51  and  52 , which individually, mechanically cooperate with a portion of the plurality of cutter knives  80  so as to cause the respective cutter knives to move radially inwardly, and outwardly, relative to the peripheral edge  42  of the knife support ring  40 , and along the path of travel  100 , when the source of fluid pressure  13  propels individual cutter knives radially outwardly relative to the knife support ring  40 . Finally, the present invention includes a magnet  60  or  60 A which is mounted adjacent to the peripheral edge  42  of the of the annular track member  40 , and which has a magnetic force which is effective so as to magnetically restrain the movement of the plurality of cutter knives  80  in a radially outward direction relative to the knife support ring  20 , and against the centrifugal force experienced by the knife support ring  20 , and the respective cutter knives  80 , when the knife support ring  20  is rotated. Further, the magnetic force acting on the respective cutter knives  80  is overcome when the source of fluid pressure  13  is applied to the respective cutter knives  80  so as to move the respective cutter knives along the path of travel  100 , and radially outwardly relative to the knife support ring  20 . In the arrangement as seen in the drawings, the annular track  40  defines a first radially, inwardly oriented track  51  which is located in spaced relation relative to the peripheral edge  42  of the annular track  40 , and a second radially outwardly disposed track  52  which is located adjacent to the peripheral edge  42 . The second track  52  diverges from, and then converges with, the first track  51 . The magnet  60  or  60 A is located near the peripheral edge  42  of the annular track  40 , and adjacent to the location  53  where the second track  52  diverges from the first track  51 . A source of fluid pressure  13  which is selectively applied to the respective cutter knives  80  causes at least one of the cutter knives  80  to move out of or diverge from the first track  51 , and move into the second track  52  and be magnetically acted upon by the magnet  60  or  60 A so as to maintain the cutter knife  80  in a radially, outwardly, extended position  102  relative to the annular track member  40  as seen in the drawings, and travel along the second track  52 . As should be understood, the magnet  60  or  60 A has a variable magnetic force which extends generally radially inwardly relative to the annular track member  40 . The magnetic force exerted by the magnet  60  or  60 A on the cutter knife  80  diminishes as the cutter knife  80  increasingly diverges from the first track  51 , and moves along the second track  52  to a position where it may then converge back with the first track  51 . As earlier noted, the magnet  60  or  60 A is effective to, at least in part, magnetically hold the respective individual cutter knifes  80  in a given orientation so that the cutter knives  80  may only travel along the first track  51  when no source of fluid pressure  13  is applied to the individual cutter knifes  80 . Further, the magnet  60  or  60 A is effective to, at least in part, magnetically attract, and move, at least in part, the individual cutter knives  80  into the second track  52  when the source of fluid pressure  13  is applied to the individual cutter knives  80  so as to move the individual cutter knives radially outwardly relative to the knife support ring  20 , and the annular track member  40 . The respective cutter knives  80  which move into and along the second track  52 , are then delivered back to the first track  51  when the second track converges with the first track when received back into the first track, the respective cutter knives  80  are then located in the withdrawn non-cutting position  101 . 
     Therefore, it will be seen that the cutting apparatus of the present invention provides a convenient means whereby the perceived shortcomings in the performance of the prior art device as seen in U.S. Pat. No. 4,520,702 are effectively overcome, and thereby provides a cutting assembly having increased robustness and reliability over that which has been known heretofore. 
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.