US3190163A

US3190163A - Cutting device

Info

Publication number: US3190163A
Authority: US
Inventors: John J Bradley
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-01-06
Filing date: 1963-07-09
Publication date: 1965-06-22
Anticipated expiration: 1982-06-22

Description

June 22, 1965 J. J. BRADLEY 3,190,163

CUTTING DEVICE Filed July 9, 1963 2 Sheets-Sheet 1 I IiH v "MIHHH 3,190,163 CUTTING DEVICE I John J. Bradley, 125 W. Mission Road, Green Bay, Wis,

Filed July 9,1963, Ser. No. 293,761

Claims. (Cl. 83-342) This invention is a continuation-in-part of copending application No. 81,009, now abandoned and relates to a cutting device, and, more particularly, to a cutting device to progressively shear a traveling web.

Theinvention has to do generally with the art of transversely severing webs traveling at a high speedes would bethe case in the rewinding of toilet tissue, toweling, etc. In this field, the paper is produced at high speed on paper 7 machines and Wound into a sizable parent roll which may be as big as six feet in diameter and upwards of'eight feet in length. To provide this material in a marketable form for retail stores, it must 'be unwound and thereafter rewound into the conventional small rolls. Relative to toilet tissue, for example, the small rolls have a length of four and one-half inches in the United States and are transversely perforatcdeach four and one-half inches. Heretofore, the perforating operation has been a distinct limitation upon the speed attainable during the rewinding operation, and the provision of novelapparatus for over-' 3,190,163 Patented June 22, 1965 well-known frame details have been omitted from the. drawing herein, but it may be appreciated thatthe roll 10 is suitably journaled in a frame F for rotation when in partial wrapping engagement with a web traveling with it,

7 the frame F also supporting the member 11. The bladeequipped bedroll is suitably driven by gears, or thelike,

as at 10a.

coming this limitation constitutes an importantobjective of this invention. 7 V Another object of this invention is toprovide a unique blade element for use in a shear cutting device such as a shear cut perforator employed in conjunction with the processing of continuous webs.

Other objects and advantages of the invention may be seen in the details of construction and operation as set down in'this specification. V The invention will be explained in conjunction withan illustratiye'embodiment in the accompanying drawing, in which: i

FIG. .1 is an elevational view, partially in section, of

a portion of a rewinder machine which features the inventive construction and which is specifically adapted to transversely perforate a web traveling at high speed;

FIG. 2 is a top plan view of the upper element of FIG. 1 and which essentially includes means for supporting anvil blades; 3

H6. 3 is a side elevational View of the structure seen in FIG. 2; a V FIG. 4 is a fragmentary elevational view of the roll constituting the lower portion of the apparatus of FIG. 1 and which is essentially diagrammatic, showing the roll blade cutting edges in relation with the anvil blade cutting edge; FIG. 5 is an enlarged fragmentary view, partially in section, of the blades associated with the roll or rotating member seen in FIGS. 1 and 4;

FIG. 6 is a fragmentary sectional'view of the structure seen in FIG. 5;

FIG. 7. is a fragmentary elevational. view of one ofthe The bedroll lllis equippedwith a plurality of longitudinally-extending, circumferentially spaced-apart recesses 12. Each recessfprovides an elongated bearing surface 13 which rigidly supports a flexible blade 14 remote from the cutting edge 1421. The blade is held against the surface 13 by means of a clamping block 15, and is positioned and. sized so as to protrude slightly from the periphery or circumference of the roll 10. The recess 12 is equipped with an additional recessed portion 16, which operates to relieve the blade for flexing when the same enters into engagement with an anvil blade17 rigidly supported in a generally immovable fashion on the holder.

. As can be appreciated from a consideration of FIG. 4, the roll blades 14 are arranged with their cutting edges 14a parallel with the am's of the roll 10, while the devel:

oped position of the cutting edges 17a of theanvil blades 17 approximates a spiral. The, angle between the anvil blade cutting edge and the center line of'thebedroll 'is called the anvil blade helix angle in FIG. 4. The blade arrangement, bringsrabout a progressive point contact between the roll blades and the anvil blades,-the interference between the blades being adjusted to the order of ial rigidity as contrasted to the roll blade 14, a typical .anvil blade having a thickness of the order of and being solidly mounted, while the roll blade has a thick: ness of the order of' g and is mounted sothe cutting edge is flexible. t

Relative to the arrangement of the anvil blades 17, the

' same may be set down in the form shown wherein they blades of FIG. 5. and which shows, in various construe? 7 tion lines, the theory of operation of the developed blade;

FIG. 8 is a side elevationalview of the blade seen in FIG. 7; and V, a

FIG. 9 is a schematic View of the blade cutting edges having designated thereon some of the variables employed in the teaching of the invention. In the illustration given, and with particular reference to FIG. 1, the numeral lll designates generally a blade roll I or bedroll, and the numeral 11 designates generally an anvihsupporting member. these members are, in general, conventional and well known, and are provided as part of a rewinder machine. In the interest of brevity and ease of understanding, the

It will be appreciated that may approximate a single spiral or helix, whereby at one time only one anvil blade is engaged by one roll blade, Alternatively, the anvil blades may be stepped so that two or more anvil blades. are simultaneously engaged by their corresponding roll blades. However, it will be appre; ciated that relative to each anvil blade, there is only a point contact or engagement with its corresponding roll blade at any given instant. I V

Preferably, but not, necessarily, the roll blades are notched or-equipped with cut-outs as at 18 (see FIG. 5) to' provide bonds in 'the v/eb being'trans versely severed.

These notches or bond cut-outs may be in the anvil blades,

leaving the roll blades unnotched. These cut-outsthen result in the well-known perforations seen in toilet tissue, toweling, etc. V V The inventive bladeisseen in larger scale in FIGS. 5-7 and is characterizedby a central depression orrecessed portion as'at 19. This is conveniently obtained by hollow grinding one or both of the thinner, longitudi nally extending faces of the blade. 7 I

conventionally, both roll blades and anvil blades have straight cutting edges. Due to this fact, the anvil blade cutting edge does not form a segment of a true-helix but actually is a chord of a true helix. Accordingly, when the flexible roll blade passes in contact with the-anvil blade there is least interference between the blades at the points where the chord of the anvil blade touches the true helix at the ends of the blade, and there is a larger interference between the blades at the point where H V 3 1. the chord of the anvil blade deviates most from a true helix, i.e., at'the center of theblades. It has been determined that due to this factor and the ,factthat the roll blades are more flexible at their ends than in the; center, the contact force at the center of the blades is more than twice the contact force at the ends of the blades when the blades 'havebeen' properly set to cut throughouttheir entire length 'of contact Sincethe' anvil blades are set to out along their entire length, the contact force at the end of the blade is all that is -neede d to'cut the web. Thus *the centers of the blades are exposed to unnecessarily severe contact forces'which serve only to increase wearof both roll blades and anvil blades and subject the roll blades to severe bending and vibration stresses. Itihas been found that'the hollow ground shape of the contact force. between the roll blade 14 and the correspondinganvil blade 17 at all points of mutual contact, the

blades

14 and 17 being aligned, as can be appreciated from FIG. 4. Equally effective results of constant contact force between the

blades

14 and 17 can be realized by hollow-grindingthe anvil blade similarly, but on a different contour. Still further, the benefits of the invention can'be'realized by complementarily hollow-grind. ing both of the matableanviland roll blades.

To achieve the optimum contour, two factors must be considered in the hollow grinding. One factor involves compensatingffor the factthat the straight cutting edge of the anvil blade is not a true he1ix, but only an approximation of a true helix. With a straight blade; this,

causes greater blade deflection, and consequently greater contact force, in the center of the blade than at the ends of the blade.

. The second factor, involves compensating for the fact.

that it takes less force to produce a given deflection of the end of the blade than it takes to produce the same deflection 'at the, center of the blade. For instance, since the blade is stiffer at the center than at the ends,-the amount of deflection which is produced by interference between blade and anvil must be less in the center of. the

, A=otfsetof anvil cutting edge to 15 'roll blade is effective in maintaining nearly constant L =length of blade cutting edge contacting-a R radius .fromlthe centerline" ofqthe bedroll to the.

upon the cutting force requir d.. When' the helix angle was increased in an effort to increase the operating speed,

the greater departure 0f the anvil blade contour from 1 a true helix resulted inlexcessive roll blade wear-and:

premature roll blade breakage, but the greater anvil helix breaka'geof roll blades at higherspeeds.

To compensate for the departure of angle did-eliminate the previouslyexperiencedimmediate by the followingformulaz.

. 4]: cos 6 3. ERE m/eReeA r y cos 0 R =radiusof hollow-grind to compensate for anvil edge 7 'not being a segment of a true helix single anvil cutting e'dg'e of the; roll blade 6=the angle between (a) a line. on the widest surface of the blade perpendicular-to and passing through the cutting edge and (b) a line passing through the center-.,

line of the bedroll and cutting edge of the bladei.e., the blade-mounting angle 0 of FIG. 1. This may be chosen for optimum performanceas 45. Z 1 The composite grind at :19 is achieved by" a combina-.

tion' of the hollow grind on the radius R. coupledwith a shallower grind to. compensate'for the extra flexibility of the blade ends, as is designatedin FIG. 7 by the nu-; meral 20. "Thus, the extra flexibility of the blade ends is compensated-for by having the ends protrude: further from the bedroll and interfere more with the anvil than f the center spanso asttoresult inan equal cutting force along the entire roll'blade cutting edge. The roll blade blade than at the ends of thelblade if thecontact force at, both points is to be the same, I

.. In addition, there are several variablesfwhich must be considered in determining the exact depth andprofile of, the hollow grind to achieve the desired results. These are: (l) the anvil blade helix angle at which the anvils are set-the greater the helix angle, the deeperthe hollow grind needed; (2) the blade mounting. angle 6; (3) the distance the blade protrudes from the clamp in the bedroll; (4)-the radius from the centerline of the bedroll to. the cutting edge of the roll blade; and (5) the blade and anvil contact force'required to cut theweb satisfactorily this being dependent upon anvil helix angle and th paper web, or the like, being perforated. r

The variable of the anvil blade helix angle. is especial .14 may be'equippedwith flat surfaces 21 at the ends .there-. of for ease of manufacturing and mounting. However, the recessed portion extends substantially the entire length of the blade on a gradual curvature having its apex at, the center of the blade length. r

seen in FIG. 7, theblade may be ground along one. side, or both as in FIG. 5, depending onwhether the'blade': is to be reversed to providefour cutting edges.j lf'merely I one cutting edge is required, the hollow ground contour may be somewhatbeveled, as seen in FIG. 6., The blades 14 advantageously can be constructed of high speed tool steel; The maximum deviation from the straight. cutting edge occurs at thelongitudinalcenter; of i the blade'and for a 4 /2" long, V thick blade havinga ly significant in high speed operation, i.e., when the perforator is operated at speeds in excess of 2000 feet per minute. immediately at high speeds because of the, high rate of load propagation-along the cutting edge of the roll blade-- It was found that blade failure occurred width 'Vs atthe endsand amountsto 0.0075. for a -helix angle. of 0.400". per 4%", length and 27. circumference, bedroll. Inother words, the width of the blade: at the center is 0.735". For. a steeper helix angle, a greati er depth of hollow grinds is 'employedaccordingito the as contrasted to bending of theroll blade whereit is clamped within the bedroll recess. i By making the anvil helix angle greater, the rate of load propagation along the roll blade can be reduced,'i.e.-, the greater the angle 'by' which theline of the anvilcutting'edge deviates from parallel with the. axis of the bedroll, the lower the'speed of load movement along the roll blade cutting edge. As an'illustratiom'in previous designs, the helix angle was 0.2" per 4 /2" length. The 4%? length is selected'since, as indicated previously, this is thewidth of a'toiletrtissue web and provides an optimum blade length. With this helix angle of 0.2" per 4 /2 length, the perforating machine could be satisfactorily runupto 1500-1800. feet per minute-the top speed being somewhat dependent previously given equation. The notches 18 are about i.e.,"of the orderof 1 /2 to 2 bladethickness. Normally,

twenty-nine notches 18 are employed forea'ch blade 14.

" While, in the foregoing specification, I have set forth adetaile'd description of an embodiment of the invention for the purpose of illustration thereof, many variations in the anvil cutting 1 edge from being a segmentof a true helix, theroll blade. 14 is hollow ground on a radius Rwhicli is determined form anvil helix :angle a (i) said notches having generally parallel sides to receive portions of said web and thereby provide bonds in said (traveling web during perforation thereof, adjacent'notches being spaced, apart by a distance greater than the width of the notchesL' 2. A flexible blade adapted to coact with an angularly disposed anvil blade in perforating'a web traveling with said flexible blade, comprising a body 7 (A having the general shape of an elongated rectan gular solid and defining thereby two oppositely-disposed narrow elongated faces and two oppositelydisposed wide elongated planar faces,

(B) at least one of the narrow faces having a concave contour to provide an elongated, longitudinally tapered recessed portion extending substantially along the length of said one face and having the tapered recess apex centrally of the length of said one face,

(i) said concave contour having a greater radius of curvature adjacent the ends of the body to compensate for the greater flexibility of the blade ends relative to the blade center,

(C) said one face being equipped with longitudinally spaced-apart notches,

y (i) said notches having generally parallel sides to receive portions of said web and thereby provide bonds in said traveling web during perforation thereof, adjacent notches being spaced apart by a distance greater than the width of the notches. 1

3. A knife blade for a shear cut perforator, comprising a generally rectangular solid bodyhaving (A) four longitudinallye'xtending cutting edges, i

(i) each of said edges having a concave contour extending over most of its length,

(B) said body being equipped with transverse notches interrupting said concave contour, adjacent notches being spaced apart by a distance greater than the width of the notches.

4. In web perforating apparatus,

(A) a frame, e r

(B) a cutting roll mounted for rotation in said frame,

(i) means for rotating said roll, 7

(ii) said roll having a plurality of circumferentially spaced recesses therein and a rigid bearing a surface within each recess,

(C) a flat resilient blade rigidly supported upon the bearing surface in each recess and (i) having an inclined, outwardly-extending free portion provided with a cutting edge,

(ii) said roll being provided with'a further recess about each outwardly-extending free blade portion for relieving the same for flexing,

(iii) the inclination of each blade being such that it forms, with a radial line drawn from its cutting e edge to the rollcenter, an acute angle, p

(D) a blade-supporting member adjacent said roll adapted to support a blade for contact with the blades of said cutting roll,

(E) a fiat, anvil blade supported on said member and (i) having its cutting edge radially inward of the path of travel of the cutting edges of the roll blades, v 7

(ii) said anvil blade being arranged with its cutting edge at an angle to the cutting edge of eachroll blade to provide progressive point contact as the edges of said blade are brought into engagement during rotation of said roll in the perforatto a 6 ing operation, with the said resilient blade edge yielding during said engagement, V

(I) each of said roll blades being equipped V with a concave contour extending generally over the length of the cutting edges of the 1 roll blades whereby said anvilblade and roll blade develop a uniform cutting force during progressivepoint contact therebe- I tween,

(II) each roll blade being equipped with a plurality* of longitudinally spaced-apart, transversely-extending notches in its cutting edge.

p 5. In web perforating apparatus,

(A) a frame, 7 (B) a cutting roll mounted for rotation in said frame,

- )(i) means for rotating said roll, 7

(ii) said roll having a plurality'of circumferentially spaced recesses therein and a rigid bear ing surface withineach recess, (C) a flat resilient blade rigidly supported upon the bearing surface in each recess and (i) having an'inclined, outwardly-extending free portions provided with a cutting edge,

(ii), said roll being provided with a further recess about eachoutwardly-extending free blade portion for relieving the same for flexing,

(iii) the inclination of each blade being such that it forms, with a radial line drawn from its cuttingedge to the roll center, an acute angle, (D) a blade-supporting member adjacent said roll j adapted to support a blade for contact with the blades of said'cutting roll, (E) a flat anvil blade supported on said member and (i) having the cutting edgelradially inward of j the path of travel of the cutting edges of the roll blades,

(ii) said anvil blade being arranged with its cutting edge at an angle to, the cutting edge of each roll blade" to provide progressive point contact' Q as the edges of said blade are brought into engagement during rotation of said roll in the perforating operation, with the said resilient- (lIDsaid, chordal helicalconfiguration be-- ing developed by an axial offset of the anvil.

blades of the order of 0.4" per 4%." of

blade length. a

6. In web perforating apparatus,

(A) a frame, t

(B) a cutting roll mounted for; rotation in said frame,

(i) means for rotating said roll, (ii) said roll having a plurality of circumferentially spaced recesses therein and a rigid bearing surfacewithin each recess, i

(C) 'a plurality of flat-resilient blades rigidly supported upon the bearing'surface ineach recess in longitudinalalignment, each resilient blade (i)"having an inclined 0utwardly extending free jportion provided with a cutting edge,

(ii) said roll being provided with a further recess tion for relieving the same for flexing,-

(iii) the inclination of each blade being such that i it forms, with a radial line drawn from its cutting edge to thetroll center, an acute angle,

1(D) a blade-supporting member adjacent said roll radially inward of the path of travel of the cutting edges of the roll 7 t 7 --blades, o t w,

(ii) each'of said .anvil bladesbeing arranged with its cutting edge at an angle to the cutting edge of the blade it contacts to provide progressive 7 point contact as the edges'of said blades are a a brought into engagement during rotation of said roll in the, cutting operation, with'the said resilient blade edges yielding during said engagement,

,with a concave contour extending 'generally overthelength ofthe cutting edges vof-theroll'blades whereby said anvil blade and'roll blade developa uniform cutting force during progressive point contact i therebetween, a t (II) each'roll blade'being equipped with a about eachoutwardly extendingfree-blade por- 7 (I) each ofsaid roll blades beingequipped plurality, of longitudinally spaced-apart,

transversely-extending notches in its 'cutting edge, 7 (HI) said concave contour being "characterized by a radius whichis a function of t the amount of helix-providing offset be- "tween a given roll blade ,and its associated 'anvil blade, the length of the roll blade cutting edge contacting its associated anvil blade, and the radius from the axis of said 7 cutting roll to the roll blade cutting edge. 7. In web perforating apparatus,

(A) a frame, 7 (B) a cutting roll mounted for rotation in said frame,

(i) means for rotating said roll,

(ii), said, roll having a plurality of circumferentially spaced recesses therein and a rigid bearing surfacewithin each recess,

(C) a plurality of ,flat resilient blades rigidly sup, ported upon the bearingsurface tinleach recess in' i longitudinal alignment, each resilient blade (i) having an inclined outwardly-extending flee portion provided with a cuttingedge,

(ii) said roll being provided with a further recess about each outwardly-extending free blade portion for relieving the same fortflexing,

(iii) the inclinationof 'each blade being such that it forms, with a radial lineldrawn'from its cutting edge to the roll center, .an acute angle, (D) a blade-supporting member adjacent said 1011 adapted to support a plurality'of blades for contact with theblades of said rotating roll,

(E) a plurality of flat anvil blades supported on said member with each anvil blade arranged in ;a chordal helical relation with the roll blade it contacts, each of said anvil blades having its cutting edge radially inward of the path of travel of the cutting edges of "the roll blades, y a 7 (ii) each of said anvil blades being arranged with its cutting edge at an angle to the cutting edge of the blade it contacts to provide progressive point contacts as the edgespof said blades are 7 brought into engagement during rotation of said .ment,-

i "(1) each of said roll blades/ being equipped 'witha concave contour. extending generally over the length of. the, cutting'edge'fsof 1 thetroll bladeswhereby said ,anvil blades 1 and roll blade develop ,a uniform" cutting force,Qduringprogressivepoint contact therebetween t a f f (H) each, roll iblade being equipped witli a t I A plurality, of longitudinally spaced apart, transversely-extending"notches in its ;'cut.-

' dgeri theblade wherebysaid roll blades are operative tolcompensate for both; the debility of the roll blade ends ';'to the center thereof t 8. In web perforating apparatus, '(Al a eM o r a (B) a cutting roll mounted in saidframe, (i) means for rotating said roll,

as; compared (ii) said roll having a longrtudinally-extending recess in the outer Wall thereof with a rigid bearing surface Within said recess,

ported upon saidQbeariiig surface and 4 (i) having an inclined, outwardly-extending free V edge portion to serve as a cutting edge,

(ii) said roll being provided with a further recess said resilient blade,

(E) -flat straight anvil blade ri'gidl y supported on said memberand a 7 (i) having its cutting edge radially inward of the path of travel of the cuttingedge, of the roll blade,

(i) said anvil'blade being arranged with its cutting edge at 'an'angle tothe' cutting'edgetof said (roll bladeto provideprogr essive point contact as 'the edges of the blades are'brought into engagement during rotation of said 'rOll, in .the

I i [perforating operation, with the r'esilientfblade edge yi'elding during said engagement, a 'I (iii) said anvil bladehaving a cho rdalvhelical configurationrelative tosaid roll'blade, at least one of said roll and anvil blades, being (I) equipped with a concave contour extend- 9: In web perforating apparatus; 1

ing generally over the length of its, cutting edge, and at least one ofsaidrolliajnd anvil bladesibein g I (H) equipped with a plurality ofrlongitudiw nally spaced-apart, transversely-extending notches inns cutting edge.

"(A)afrarne;* 7 i (B) a cuttingr'oll mounted'in' said frame,

C(i) means forrotating said roll,

(ii) said roll having a longitudinally-extending recess in the'outer wall thereof with a rigid bear-t ing surface within said recess,

I (C) a flat straight resilientcutting blade rigidily supported upon said bearing surface and H (i) having an inclined, outwardly-extending free edge portion to'ser'v'e asa cuttingedge,

,iroll in the cutting. operatiomvvith' the said resilient blade edges yieldingduringsaid engage- (III), said concave contour having ;a' greater radius of curvature adjacent the ends of V parture of the flat anvil blades fromatrue 1 helimand forthe relativelygreater fleiri-V a flat straight resilient cuttin blade rigidly supn about. the outwardly-extending .frfee blade por-:

(ii) said roll being provided with a further recess about the outwardly-extending free blade portion for relieving the same for flexing, said blade being inclined with respect to a radial line drawn from its cutting edge to the roll center to form with said line an acute angle,

(D) a blade-supporting member adjacent said roll adapted to support an anvil blade for contact with said resilient blade, 7 l

(E) a flat straight anvil blade rigidly supported on said member and (i) having its cutting edge radially inward of the ing generally over the length of its cutting edge and a e (H) equipped with a plurality of longitudinally spaced-apart, transversely-extending notches in its cutting edge,

(HI) said concave contour being characterized by a radius which is a function of the following factors: i a

(a) the amount of helix-providing offset between the roll blade and anvil blade,

' (b) the length of the roll'blade cutting edge contacting the anvil blade, and

V (c) the radius from the axis of said roll to the roll blade cutting edge. 10. In web perforating apparatus, (A) a frame,

(B) a cutting roll mounted in said frame,

(i) means for rotating said roll,

(ii) said roll having a longitudinally-extending recess in the outer Wall thereof ,with a rigid bearing surface within said recess,

(C) a flat straight resilient cutting blade rigidly supported upon said bearing surface and a (i) having an inclined, outwardly-extending free edge portion to serve as a cutting edge,

(ii) said roll being provided with a further recess about the outwardly-extending free blade portion for relieving the same for flexing, said blade being inclined with respect to a radial line drawn from its cutting edge to the roll center to form with'said line an acute angle,

(D) a blade-supporting member adjacent said roll adapted to support an anvil blade for contact with said resilient blade, I V

(E) a flatstr'aight anvil blade rigidly supported on said member and a (i) having its cutting edge radially inward of the path of travel of the cutting edge of the roll blade,

(ii) said anvil blade being arranged with its cutting edge at an angle to the cutting edge of said roll blade to provide progressive point contact as the edges of the blades are brought into engagement during rotation of said roll in the perforating operation, with the resilient blade 7 edge yielding during said engagement,

(iii) said anvilblade having a chordal helical con-r figuration relative to said roll blade, at least one compensate for both the departure of said flat anvil blade from a true helix and for the relatively greater flexibility of the roll blade ends as compared to the center there References (Iited by the Examiner UNITED STATES PATENTS 7 1,977,647 10/34 Royal 83349 2,870,840 1/59 Kwitek Q 83 342 3,056,323 10/62 Kwitek 83- 342 3,073,196 1/63 Marcalus 83-34l ANDREW R. J'UHA'SZ, Primary Examiner. LEON PEAR, Examiner.

Claims

3. A KNIFE BLADE FOR A SHEAR CUT PERFORATOR, COMPRISING A GENERALLY RECTANGULAR SOLID BODY HAVING (A) FOUR LONGITUDINALLY-EXTENDING CUTTING EDGES, (I) EACH OF SAID EDGES HAVING A CONCAVE CONTOUR EXTENDING OVER MOST OF ITS LENGTH, (B) SAID BODY BEING EQUIPPED WITH TRANSVERSE NOTCHES INTERRUPTING SAID CONCAVE CONTOUR, ADJACENT NOTCHES BEING SPACED APART BY A DISTANCE GREATER THAN THE WIDTH OF THE NOTCHES.
4. IN WEB PERFORATING APPARATUS, (A) A FRAME, (B) A CUTTING ROLL MOUNTED FOR ROTATION IN SAID FRAME, (I) MEANS FOR ROTATING SAID ROLL, (II) SAID ROLL HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED RECESSES THEREIN AND A RIGID BEARING SURFACE WITHIN EACH RECESS, (C) A FLAT RESILIENT BLADE RIGIDLY SUPPORTED UPON THE BEARING SURFACE IN EACH RECESS AND (I) HAVING AN INCLINED, OUTWARDLY-EXTENDING FREE PORTION PROVIDED WITH A CUTTING EDGE, (II) SAID ROLL BEING PROVIDED WITH A FURTHER RECESS ABOUT EACH OUTWARDLY-EXTENDING FREE BLADE PORTION FOR RELIEVING THE SAME FOR FLEXING, (III) THE INCLINATION OF EACH BLADE BEING SUCH THAT IT FORMS, WITH A RADIAL LINE DRAWN FROM ITS CUTTING EDGE TO THE ROLL CENTER, AN ACUTE ANGLE, (D) A BLADE-SUPPORTING MEMBER ADJACENT SAID ROLL ADAPTED TO SUPPORT A BLADE FOR CONTACT WITH THE BLADES OF SAID CUTTING ROLL, (E) A FLAT ANVIL BLADE SUPPORTED ON SAID MEMBER AND (I) HAVING ITS CUTTING EDGE RADIALLY INWARD OF THE PATH OF TRAVEL OF THE CUTTING EDGES OF THE ROLL BLADES, (II) SAID ANVIL BLADE BEING ARRANGED WITH ITS CUTTING EDGE AT AN ANGLE TO THE CUTTING EDGE OF EACH ROLL BLADE TO PROVIDE PROGRESSIVE POINT CONTACT AS THE EDGES OF SAID BLADE ARE BROUGHT INTO ENGAGEMENT DURING ROTATION OF SAID ROLL IN THE PERFORATING OPERATION, WITH THE SAID RESILIENT BLADE EDGE YIELDING DURING SAID ENGAGEMENT, (I) EACH OF SAID ROLL BLADES BEING EQUIPPED WITH A CONCAVE CONTOUR EXTENDING GENERALLY OVER THE LENGTH OF THE CUTTING EDGES OF THE ROLL BLADES WHEREBY SAID ANVIL BLADE AND ROLL BLADE DEVELOP A UNIFORM CUTTING FORCE DURING PROGRESSIVE POINT CONTACT THEREBETWEEN, (II) EACH ROLL BLADE BEING EQUIPPED WITH A PLURALITY OF LONGITUDINALLY SPACED-APART, TRANSVERSELY-EXTENDING NOTCHES IN ITS CUTTING EDGE.