CA2244263A1 - A die cutting insert for a rotary die cutter and the die cutter itself - Google Patents

Abstract

A die cutting insert (18) for a rotary die cutter is disclosed as well as the die itself. The insert includes a base (34) formed on a predetermined radius.
The base has first and second spaced apart ends (36, 38) and first and second oppositely aligned surfaces (40, 42). A knife (44) is formed about the periphery of the first surface (40). The knife (44) has a cutting edge (46) and first and second side walls (48, 50). The cutting edge (46) has a width of less than about .005 inches. In addition, the first side wall (48) is aligned approximately perpendicular to the cutting edge (46) while the second side wall (50) is aligned at an angle of at least about 15~ relative to the cutting edge. The insert (18) also includes means for removably attaching it to a die shaft. The means includes at least one aperture (56) formed adjacent to each of the first and second ends (36, 38). The apertures (56) extend completely through the base (34) and each is sized to receive a threaded bolt (60). The threaded bolts (60) can be torqued to a predetermined value to secure the insert to the die shaft (14). The rotary die cutter includes a die shaft (14) having one or more replaceable and/or interchangeable die cutting inserts (18) mounted thereto and is aligned to cooperate with a rotatable anvil roll (12).
The die shaft (14) and anvil roll (12) are arranged to form a nip (20) therebetween. Material (22) which is to be cut can pass through the nip (20) and will be cut into the desired shape (24) of the die cutting inserts (18).

Description

CA 02244263 l998-07-24 WO 97/27033 PCTrUS96/20711 A DnE CtrrrnNG nNSERT PDR A ROTARY DnE CUlllER AND l~E DnE CtrrrER rrSELF

FIELD OF THE INVENTION
This invention relates to a die cutting insert for a rotary die cutter and the die itself. More specifically, this invention relates to a replace~'-'e and/or i.,Lt r~hangeable die cutting insert for a rotary die which can be used to cut absoil,enL articles from a web of " ,alerial.

BACKGROUND OF THE INVENTION
A rotary die cutter includes a rol ' ~1~ anvil roll which cooperates with a ,ul~knife shaft assel"bly. The knife shaft asse,l,l~ly has an outer circumrerence with at least one die cutter A~so~:~'ed therewith. The knife shaft assembly cooperates with the anvil roll to form a nip through which a web of ~"ale,ial can pass. As a web of ",dle,ial passes between the nip, the die cutter will cut the ",al~,ial into a predetermined shape.
Since the nip between the anvll roll and the knife shaft asse",~ly is very small, it is necess~ry that the anvil roll and the knife shaft assembly be manufactured to very close ~ lerd,)ces. Rer~use of the close trllsrd"ces, most rotary die cutters utilize a solid die shaft having the die cutters integrally formed thereon. When repl-cer~le die cutting inserts have been mounted onto the circ~ lrer~ance of a ~uLdldble die shaft, it has been found that it becomes difficult to maintain the required close tolerances. In addition, it is difficult to attach the die cutting inserts without also introducing addilional forces which can cause the inserts to flex under load. Up until now, in order to assure that the nip I ~ ,.er,sion, t ",a;. ,s conaldl ll, it was necess~ry to regrind the die cutting inserts after they were mounted on the knife shaft asse",bly to assure that the correct nip dimension would be pr~senL. This was particularly necess~ry when two or more die cutting inserts were mounted about the outer periphery of a die shaft.
Rotary die cutters are used in many dirrarenL industries to cut many .lirrar~r~L types of ..,alerial. For e~cd",ple, rotary die cutters can be employed to cut paper, ~a.dbodnl, plastic, laminates formed of two or more layers, absorbent materials such as wood pulp 35 fluff, webs formed from natural or synthetic fibers, c e "- ~'os e fluff, tissue, cotton, rayon and various other types of woven and nonwoven ",ale~ials. Rotary die cutters are particularly useful in cutting a plurality of layers of different ,.,ale~ial which have been asse"l - ed to form an abso.i,enl article such as a sanitary napkin or a pantiliner. Such products are no""ally constructed from top to bottom, of a liquid-permeable cover sheet, one or more absorbent layers a liquid-i""~e~",-at'e baffle a layer of garment alla. h",ent 5 adhesive and a removable peel strip. The various layers are no"" ly bonded together by a construction adhesive and the article usually has a total 11 ~ '<~,ess of beh~cQn about 0.1 inches to about 1.0 inch.
Now a repl~cer - I e and/or i"l~r~hangeable die cutting insert for a rotary die cutter has been invented along with the die itself. Fach repl-ce- 'e and/or i"le~l-angeable die 10 cutting insert has a unique configuration and includes mounting means for properly securing it to the outer circu",rar~nce of a knife shaft assembly.

SUMMARY OF THE INVENTION
13riefly this invention relates to a repl-cer''e and/or il ,ler~ha,1geable die cutting 15 insert for a rotary die cutter and the die itself. The insert includes an arcua~ly shaped base formed on a pre-delé:l ", Ied radius. The base has first and second spaced apart ends and first and second opposilely aligned surfaces. A continuous knife is integrally formed about the outer periphery of the first surface. The knife has a cutting edge and first and second side walls. The knife edge has a l h kr~ess of less than about .005 20 inches and the first side wall is aligned appru,ci,na~ly perpendicular to the cutting edge.
The second side wall is aligned at an angle of at least about 15~ relative to the cutffng edge. The die cutting insert also includss a me- han;OI~ for removably attaching it to a die cutting shaft. The mecl-anis,n can include at least one aperture formed a~jacent to each end of the base. The apertures extend co" a ~ Iy through the base and are 25 designed to receive threaded boits. The bolts are select~d and sized to mate with the apertures and secure the base to the die cutting shaft.
The general object of this invention is to provide a repla~er 'e and/or r~l ,an~ die cutting insert for a knife shaft asser,.bly. A more spec.ific object of this invention is to provide a rotary die cutter having a (~: ~ anvil and a ru~ le knife 30 shaft asser"bly with one or more r~pl~ce: le die cutting inserts mounted to the outer circulllr~ lce of a die shaft.
Another object of this invention iO to provide a knife shaft asser"bly having r~plsce - - le and/or i"ler~;hangeable die cutting insert attached thereto which can be removed without requiring the inserts to be reground in order to obtain the right clearance 35 nip bE~rccn the anvil roll and the knife shaft assen,~ly.

-CA 02244263 l998-07-24 W 097/27033 PCTnUS96/20711 A further object of this invention is to provide a repl~cer le and/or i"Lerchal-geable die cutting insert which can quickly and easily be removed and/or attached to a die shaft.
Still anoll ,er object of this invention is to provide a l~pla,.2-'- e and/or 5 interchange '-'E die cutting insert which can easily be properly secured to a die shaft at a predetermined torque value.
Still further an object of this invention is to provide a rotary die cutter having a ,uia ~le anvil roll matin~ with a r~ ~hle knife shaft asse",bly to form a nip therebetween and having one or more ~-plac~- le and/or inler-;hangeable die cutting 10 inserts mounted about its outer circumrer~nce of the knife shaft.
Other objects and ad~ anla~es of the presenl invention will become more app~renL to those skilled in the art in view of the re ~ ;nQ desc, iplion and the accompanying drawings.

BRIFF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sche,..dlic of a rotary die cutter showing a .u le anvil roll cooperali. .g with a .~ le knife shaft asse.l,bly to forrn a nip therebetween and having a web of ",dL~rial passi.,~ through the nip.
Fig. 2 is a perspective view of a repl~ce 'e and/or inler-;l-angeable die cutting 20 insert.
Fig. 3 is a cross-sectional view taken along line 3 3 of Fig. 2 showing the cutting edges and the mounting holes for attaching the insert to a die shaft.
F4 4 is an q-. 5ade-~. cross-se- lional view of a portion of the repl~cer le and/or inler~;hangeable die cutting insert mounted to a portion of the outer circumre,er,ce of the 25 die shaft.

r~ETAlLED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Rere..ing to Fig. 1 a rotary die cutter 10 is shown which includes a (e le anvilroll 12 cooperali..g with a luh - e knife shaft asse,.~bly 13. The anvil roll 12 can be 30 constructed of a ferrous or non-ferrous metal and should have a smooth surface. The anvil roll 12 can be formed from a ...a~e, ial which is COfill)~ S ~" !e such as neoprene rubberorfromanon-ccsn-~,r ss leIlldlelial suchassteel. Formostal-pli~lions itis pretelled that the anvil roll 12 be a metal roll.
The knife shaft asser..bly 13 includes a die shaft 14 with an outer 35 circumrerence 16 and at least one repl~ce~hle and/or i. Iler. l ,angeable die cutting insert 18 mounted onto the die shaft 14. By repl~ce h,e it is meant that the insert 18 can be CA 02244263 l998-07-24 W 097/27033 PCT~US96/20711 unbolted and removed from the die shaft 14, cleaned reground or ."acl ~ ~ed in some fashion and then secured back onto the die shaft 14 in its original posilion. Byi, .ler ha,)geable it is meant that each of the die inserts 18 is ~p~hlQ of being mutually interchanged with any other insert 18. This i. I~el 1hanger - ~.y feature is very i" ,po, lant 5 bec~ ~ce up until now it has been virtually i-,-,c ~ Ie to produce ~., a~ ~ r ~ e and i..ler~l-an~eable inserts 18 for a rotary die cutter 10 while still maintaining the nip di",ension b~t veon the anvil roll 12 and the knife shaft assembly 13.
The knife shaft ass~" Ibly 13 can be constructed of a metal for e,~a" " ! e steel and should have an outer circu,.~terence mac1, ~ed to a very close l~ ance. The die 10 shaft 14 can have one or more preferably several die cutting inserts 18 mounted to its outer circu,..terence 16. As deFi ~ ~ in Fig. 1 there are four die cutting inserts 18 equally spaced about the outer circumrerence 16 of ths die shaft 14. The anvil roll 12 and the knife shaft asse",biy 13 cooperate to form a nip 20 therebetween through which a web of material 22 can pass. As the anvil roll 12 and the knife shaft asse,.lL,ly 13 are 1~ rotated in opposil~ directions the web of ,.,ale,ial 22 can pass throu~h the nip 20 and be cut by the die cutting inserts 18 into individual articles 24. The articles 24 can be Il anspo. Led by convenlional means such as a conveyor 26, to a loc~lion where they can be st~l .ed p~ ecl and later shipped. Any waste trim 30 frorn the rotary die cutter 10 can be 1 e~ lecl away from the nip 20 by a conduit 28 using vacuum air pressure gravity o mllêC hao;- means. The waste trim 30 can then be co ;ec ~ in a hopper 32 for F~ ~e recyding or some other means of ~I; pos~l Rerellillg to Fig. 2, a ,~place~ e and/or i"lér~;hal)~eable die cutting insert 18 is shown before it is secured to the die shaft 14. The repl-cer e and/or interchangeable die cutting insert 18 has an arcuatcly shaped base 34 forrned on a ~redelé""i,.ed radius.
The base 34 has first and second spaced apart ends 36 and 38 respectively and first snd second oppos~-ly aligned surfaces 40 and 42 respectively. The first surface 40 will face the anvil roll 12 when the inserts 18 are assemL led onto the knife shaft asser"bly 13. The second surface 42 will be concave so as to match the outer circ~""rerënce 16 of the die shaft 14 onto which the insert 18 is to be secured. It is cor.llnon to machine the second surface 42 to have a tolerance of plus or minus .0001 inches so as to f~ -. a proper allach.nent behvecn the die cutting insert 18 and the die shaft 14. If the second surface 42is not ".a- l ~ed to closely match the outer circ-",-re,ence 16 of the die shaft 14, then it is possible for addiLio~al cor."~ressive forces to develop as each insert 18 is secured to the die shaft 14. The p~esence of such compressive forces can alter the dimension of the nip 20, and this is Ul ,desil~ble.

CA 02244263 l998-07-24 Referring to Figs. 2 and 3 the die cutting insert 18is shown having a knife 44 which is integrally formed about the periphery of the first surface 40. Plererdbly the knife 44is a continuous ele."enl but could be se,-al~d if desired. The knife 44 has a cutting edge 46 and first and second side walls 48 and 50 respeclively. The cutting 5 edge 46 has a width of less than about .005 inches. Pleferdbly the width of the cutting edge 46is be lvJecn about .0005 to about .004 inches and most pref~,dbly the width is between about .001 to about .002 inches. The width of the cutting edge 46iS veryimpo, lal IL he~use if the l hl k ~ess becc " ~es too great it will be more difficult to cleanly cut the material 22 passi"~ through the nip 20. For exa""~ le instead of making a clean cut the cutting edge 46 could cor~r~ssed the r"aleiial 22 and allow the ",ale,ial 22 to be torn or broken and thereby produce a ragged cut.
As shown in Fig. 3, the first side wall 48iS aligned d,~pro~illldlely perpendicular to the cutting edge 46. In other words the first side wall 48iS coe~lensively aligned with the outside periphery 52 of the base 34. Frt:rerdbly the first side wall 48 will be aligned perpendicular that is at 90 degrees to the cutting edge 46. The second side wall 50iS
aligned in an angle of at least about 15~ relative to the cutting edge 46. The second side wall 50iS located inward of the first side wall 48 and terminates at a third surface 54.
The third surFace 54is located intermediate the hrst surface 40 and the second surface 42. The third surface 54is spaced below the first surface 40 by a distance ~d". The actual d;sla.)ce be~Y: ~en the first surface 40 and the third surface 54 can vary but normally will be about equal to the thickness of the article 24 which is to be cut. For example when cutting a ~""ur~- ' !e article having a total thickness of about .125 inches the ~ lance of ths third surFace 54 below the first surface 40 can be be~vocn about 0.1 inches to about .125 inches. The distance Ud" also r~p,t:se, ll~ the height of the 25 knife 44. The dislance "d~ can be arrecled by the type of Illdlelial22 which is being cut the thickness of the mdl~lial whether the material is compressible whether the Illdl~l ial is formed from a single layer or from a plurality of layers whether the layers are bonded togell,er by an adhesive as well as the particular ~I,ardcl~ri: lics of the ,..ale~al itself.
For eAdr"~'~ a the""opla~liG film may react dirr~re,.U~r to be cut than a fibrous nonwoven 30 web. It should also be noted that when cutting thinner n,alelials that the di~lance Ud"
could be less than the lh- kuess of the IlldLt:lial22 because the cut may not have to extend as far through the ,nalerial as with a thicker product. When cutting the lodlt:l ial 22, it is not necess~ry that the cutting edge 46 actually contact the anvil roll 12. In fact the life of the cutting die insert 18 can be extended when the cutting edge 46 does not 35 physically contact the anvil roll 12.

CA 02244263 l998-07-24 W O 97127033 PCTrUS96/20711 The second side wall 50 is aligned at an angle a of at least about 15~ relative to the cutting edge 46. Preferably, the angle a~ is between about 15~ to about 50~ relative to the cutting edge 46, and more pr~ferably, the angle aiS bet~r~ccn about 15~ to about 40~
relative to the cutting edge 46. It is i" "~o, Idnl that the second side wall 50 be angled relative to the cutting edge 4~3 at an angle a of at least about 15~ be~use the design of the insert 18 leaves very liWe support for the knife 44. Since the first side wall 48iS
appruxi"-dtuly perpendicularly aligned to the cutting edge 46, all support provided to the knife 44 will have to come from the ",alelial pfesenL between the first side wall 48 and the second side wall 50. If the angle aiS less than about 15~, there is a high probability 10 that the cutting edge 46 will crack or chip as the ~l~al~rial 22 is being cut becz~use the forces acting on the cutting ed~e 46 can become very high.
Rere,.il-g now to Figs. 3 and 4, the repla ~ = -ble and/or interchan3eable die cutting insert 18 further includes means for removably attaching the base 34 to at least a portion of the outer circumference 16 of the die shaft 14. It should be noted that the die shaft 14 15 can have one or more, and prt:re,dbly a plurality of f~F,'a~e~'le and/or inLerchallgeable die cutting inserts 18 mounted about its outercircu",rer~nce 16. The inserts 18 can be arranged so that they are equally spaced apart from one anoU ,er or they can be arranged such that the outer periphery of one will contact the outer periphery of an adjacenl insert 18. It is also ,~ e to mount the inserts 18 on the outer circ~ rer~,lce 16 of the die shaft 14 such that the inserts 18 are grouped around a portion of the outer circu,.lre~ence 16 while alioU-er portion of the outercircu."rert:,.ce 16 is void of any inserts. The particular arrangement and the spa~,i. ,g of the inserts 18 will depend upon the type of ,.,ale,i~l which is to be cut and the particular configuration of the articles which are to be cut.
One means for removably attaching the die cutting inserts 18 to the die shaft 14indudes forming at least one aperture 56 a~jacenl to each of the first and second ends, 3~S and 38 respectively. Pl~rerdl~ly, a pair of apertures 56 are formed adjacenl to each of the ends, 36 and 38 respectively, so as to permit each insert 18 to be cooeclly secured to the die shaft 14 without introducing unwanted forces into each insert 18. Each of the apertures 56 extends CGI I, If ' Iy through the base 34 from the third surface 54 to the second surface 42. The apertures 56 are not threaded but do contain a counterbore 58 located adjacenL to the third surface 54. Each cou. .~.L,ort: 58 is sized and configured to receive the head of a machine bolt 60, see Fig. 4, which will attach the insert 18 to the die shaft 14.
Rere n ~ to Fig. 4, a threaded machine bolt 60 is shown posilioned in one of theapertures 56. The bolt 60 is aligned with and threaded into a threaded bore or aperture CA 02244263 l998-07-24 W 097/27033 PCTrUS96/20711 62 formed in the die shaft 14. The bolt 60 contains a head 64 and a threaded shank 65.
The head 64 is larger than the lhreaded shank 65 and is designed to seat in the colllllellJGre 58 when the insert 18 is mounted onto the die shaft 14. When assembled, the head 64 will be flush with the third surface 54. Each of the machine bolts 60 can have a predele"";,led thread pitch. In addilion, the length of the threads and the number of lhl~ads per inch can vary depending upon oneJs aFFI ' ~n. The size and style of the bolts 60 can be select~d dependin9 upon the size and configuration of the rep~lacer'-le andtor illlel~:hangeable die cutting insert 18. It should be noted that it is desirable to tighten the bolts 60 to a relatively high torque setting, for e~dl"~ le betvJccn about 100 pounds per square inch (psi) to about 1000 psi. R~-:rerably, each bolt 60 is ligl .lened to a torque seffing of b~t /ocn about 200 psi to about 500 psi, and more prererdbly, bc~:-ecn about 400 psi to about 500 psi. To facilitate the torquing of the bolts 60, it is .~col~l,),ended that a fine thread be used instead of a course thread. One bolt size which works well in mounting an insert measuring about six inches in length, about two inches in width and about .75 inches in depth to a die shaft 14 is a bolt 60 having the following diameter (inches) and thread .3125-24 UAF. It is also advant~geou s to drill and tap the threaded bore 62 to a depth which is greater than the ll ~l ~aded length of the bolt shank 65 so that the bolt 60 will not bottom-out in the threaded bore 62. This dirrere:nce in length will allow the bolt 60 to be properly torqued during assembly.
In orderto properly secure the l.pla~a~le and/or inler,l-angeable die cuffing inserts 18 to the die shaft 14, the bolts 60 should be sized and configured to mate with each pair of the coaxially aligned apertures 56 and 62. It should be noted that when each of the die cuffing inserts 18 conta;.,s a single aperture 56 formed adjacenl to each end, 36 and 38 respectively, that only two threaded bolts 60 will be required to secure each insert 18 to the die shaft 14. However, when each of the die cutting inserts 18 contains two apertures 56 formed adjacent to each end, 36 and 38 respectively, four threaded bolts 60 will be required to secure each insert 18 to the die shaft 14.Referring again to Fig. 4, one of the Ihl~aded bores 62 is shown. It should be realized that there will be a plurality of threaded bores 62, one for each of the 3Q ~"e "~,onding apertures 56 forrned in each of the inserts 18. It is p~5c ' 'e to a"dnge the threaded bores 62 in the die shaft 14 such that various sizes of inserts 18 can be asse",' le~ onto the die shaft 14 at a later time. By forming more threaded bores 16 than needed and alldng;.lg them at dirr~rt:nL locations about the outer circ~""r~r~t1ce 16 of the die shaft 14, one can use a single die shaft 14 to ac~",modate two or more different style of die cufflng inserts 18.

CA 02244263 l998-07-24 W 097/27033 PCT~US96/20711 It has also been found to be exl,ernely advantageo~ ~c to forrn a cou"l~,L,ort 66 at the open end of each of the ll-,~aded bores 62. Each counle,bo,-: 66 begins at the outer circ~""rer~3nce 16 of the die shaft 14 and has a depth of at least about .05 inches.
r~re,dbly the depth will range from about .1 inches to about .2 Inches and more 5 pr~rerdLiy the depth will range behv~cn about .1 inches and about .15 inches. A depth of about .125 inches works well when the threaded bores 62 have a did",eler of about .3125 inches or greater. The presence of the cou"l~,L,ores 66 are in">o,lanL for they full~Liorls to relieve ccr"pressi~e s~csses in the metal from which the die shaft 14 is constructed. Such force can occur as the repl~cer ' le and/or i, ,II:r.;hallgea~ 'e die cutting inserts 18 are secured to the die shaft 14. It has been found that as a machine bolt 60 is threaded into the ll ,r~aded bore 62 and then torqued to a relatively high inch pound value thatthe metal forming the die shaft 14 on a ~": .sc. p:c scale can ~ctu-"y buckle or deform as the die shaft 14 is drawn up against the insert 18. By fo,.. ~ lg the counterbore 66 at the open end of the threaded bore 62 one can minimize the amount of 15 co""~ressive stresses and forces which are developed.
Refe"ing again to Fig. 2 the insert 18 can also contains a pin hole 68 formed atthe intersection of the central longih ~ 1inal axis X--X and the central transverse axis Y Y.
The pin hole 68 is designed to be coaxially aligned with a hole or bore formed in the die shaft 14 such that a pin can be inserted through the pin hole 68 and serve to physically 20 align the insert 18 onto the die shaft 14. Once the insert is aligned and held in posilion by a pin (not shown) the bolts 60 can be ll,,c:aded into the threaded bores 62. It should be noted that the pin hole 68 is an opLional feature and is presenL only for convenience in mounting the insert 18 onto the die shaft 14.
While the invention has been described in conjunction with several specific 25 embodiments it is to be u"der~Lood that many alL~" ,aLi~es modifications and va(ialions will be appar~nL to those skilled in the art in light of the aforegoing descriplion.
Accordingly this invent~on is intended to e",b,ace all such alL~:",~Li./es ",odiricaLiorls and vari~lions which fall within the spirit and scope of the appended claims.

Claims (20)

I claim:

1. A die cutting insert for a rotary die cutter comprising:
a) a base formed on a predetermined radius, said base having first and second spaced apart ends and first and second oppositely aligned surfaces;
b) a knife formed about the periphery of said first surface, said knife having acutting edge and first and second side walls, said cutting edge having a width of less than about .005 inches with said first sidewall being aligned approximately perpendicular to said cutting edge and said second sidewall being aligned at an angle of at least about 15 degrees relative to said cutting edge; and c) means for removably attaching said base to a die shaft, said means including at least one aperture formed adjacent to each of said first and second ends, said apertures extending completely through said base, and at least two threaded bolts sized to mate with said apertures and secure said insert to said die shaft.

2. The die cutting insert of claim 1 wherein said base has an outside periphery and said first sidewall is coextensive with said outside periphery of said base.

3. The die cutting insert of claim 1 wherein said second sidewall is located inward of said first sidewall.

4. The die cutting insert of claim 1 wherein said second sidewall terminates into a third surface which is located intermediate said first and second surfaces.

5. The die cutting insert of claim 4 wherein said third surface is spaced at least about .005 inches below said first surface.

6. The die cutting insert of claim 1 wherein said second sidewall is aligned at an angle of between about 15 degrees to about 50 degrees relative to said cutting edge.

7. The die cutting insert of claim 6 wherein said second sidewall is aligned at an angle of between about 15 degrees to about 40 degrees relative to said cutting edge.

8. The die cutting insert of claim 1 wherein said cutting edge has a width of between about .0005 to about .004 inches.

9. The die cutting insert of claim 8 wherein said cutting edge has a width of between about .001 to about .002 inches.

10. A replaceable and/or interchangeable die cutting insert for a rotary die cutter comprising:
a) an arcuately shaped base formed on a predetermined radius, said base having first and second spaced apart ends and first and second oppositely aligned surfaces;
b) a continuous knife integrally formed about the periphery of said first surface, said knife having a cutting edge and first and second side walls, said cutting edge having a width of less than about .005 inches with said first sidewall being aligned perpendicular to said cutting edge and said second sidewall being aligned at an angle of at least about 15 degrees relative to said cutting edge; and c) means for removably attaching said base to at least a portion of the outer circumference of a die shaft, said means including a pair of apertures formed adjacent to each of said first and second ends, all of said apertures extending completely through said base, and said means further including four threaded bolts sized to mate with said apertures and secure said insert to said die shaft.

11. The die cutting insert of claim 10 wherein said base has an outside periphery and said first sidewall is coextensive with said outside periphery of said base.

12. The die cutting insert of claim 10 wherein said second sidewall is located inward of said first sidewall.

13. The die cutting insert of claim 10 wherein said second sidewall terminates into a third surface which is located intermediate said first and second surfaces.

14. The die cutting insert of claim 13 wherein said apertures extend from said third surface to said second surface.

15. A rotary die cutter comprising:
a) a rotatable anvil roll;
b) a rotatable die shaft having an outer circumference with at least one replaceable die cutting insert mounted thereto, each of said die cutting insertscooperating with said anvil roll to form a nip therebetween, each of said die cutting inserts having an arcuately shaped base formed on a predetermined radius, said base having first and second spaced apart ends and first and second oppositely aligned surfaces, a continuous knife integrally formed about the periphery of said first surface, said knife having a cutting edge and first and second side walls, said cutting edge having a width of less than about .005 inches with said first sidewall being aligned approximately perpendicular to said cutting edge and said second sidewall being aligned at an angle of at least about 15 degrees relative to said cutting edge, and means for removablyattaching said base to a die shaft, said means including at least one aperture formed adjacent to each of said first and second ends, said apertures extending completely through said base, and at least two threaded bolts sized to mate with said apertures and secure said insert to said die shaft.

16. The rotary die cutter of claim 15 wherein said die shaft has a plurality of threaded apertures formed therein.

17. The rotary die cutter of claim 16 wherein each of said threaded apertures has a counterbore to relieve compressive stresses as said replaceable die cutting insert is secured to said die shaft.

18. The rotary die cutter of claim 17 wherein each of said counterbores has a depth of at least about .05 inches.

19. The rotary die cutter of claim 17 wherein each of said counterbores has a depth of about .125 inches.

20. A rotary die cutter comprising:
a) a rotatable anvil roll;
b) a rotatable die shaft having an outer circumference with at least one replaceable die cutting insert mounted thereto, each of said die cutting insertscooperating with said anvil roll to form a nip therebetween, each of said die cutting inserts having an arcuately shaped base formed on a predetermined radius, said base having first and second spaced apart ends and first and second oppositely aligned surfaces, a continuous knife integrally formed about the periphery of said first surface, said knife having a cutting edge and first and second side walls, said cutting edge having a width of less than about .005 inches with said first sidewall being aligned perpendicular to said cutting edge and said second sidewall being aligned at an angle of at least about 15 degrees relative to said cutting edge, and means for removably attaching said second surface of said base to at least a portion of the outer circumference of a die shaft, said means including a pair of apertures formed adjacent to each of said first and second ends, all of said apertures extending completely through said base, and said means further including four threaded bolts sized to mate with said apertures and secure said insert to said die shaft.