US3803963A

US3803963A - Cutter with stripper

Info

Publication number: US3803963A
Application number: US00190918A
Authority: US
Inventors: R Hunt
Original assignee: International Paper Co
Current assignee: International Paper Co
Priority date: 1971-10-20
Filing date: 1971-10-20
Publication date: 1974-04-16
Anticipated expiration: 1991-04-16

Abstract

A cutter blade is provided with resilient means having sections for engaging the web adjacent the cut being made and these sections exert oppositely directed tensile forces on the web on the opposite sides of the cut to assist in separating the cut edges being formed. The resilient means may also cushion the blade against vibration which would cause the blade edge to chip or dent. The blade may be made of a ceramic material encapsulated in a resilient sheath with only the cutting edge of the blade exposed for cutting the web.

Description

llited- States Patent 1191 Hunt [ Apr. 16, 1974 CUTTER WITH STRIPPER [75] Inventor: Robert F. Hunt, Concord, Tenn.

[73] Assignee: International Paper Company, New

York, NY.

22 Filed: on. 20, 1971 21 Appl.No.: 190,918

Obenshain 83/1 16 X Nassar 83/676 X 3,224,311 12/ l 965 Wagner.... 3,306,149 2/1967 John 3,543,402 .12/1970 Seager 130/346.53

Primary ExaminerFrank T. Yost Assistant Examiner-Horace M. Culver Attorney, Agent, or ;Firm-Fitch, Even, Tabin & Luedeka 57] ABSTRACT -A cutter blade is provided with resilient means having sections for engaging the web adjacent the cut being made and these sections exert oppositely directed tensile forces on the web on the opposite sides of the cut to assist in separating the cut edges being formed. The resilient means may also cushion the blade against vibration which would cause the blade edge to chip or dent. The blade may be made of a ceramic material encapsulated in a resilient sheath with only the cutting edge of the blade exposed for cutting the web.

7 Claims, 5 Drawing Figures PATENVEMPR 16 I974 ROERT E Haw? CUTTER WITH STRIPPER- This invention relates to a cutter for paper, nonwoven fabrics or other materials and to a cutting apparatus having a cutter with a cutting edge which cooperates with a support across which the material travels.

The cutter and cutting apparatus are described herein in connection with the slitting of long lengths of webs of paper or nonwoven fabrics travelling at high speeds and ultimately wound into large diameter rolls; but it is to be understood that the cutter and the apparatus may be used to out various other kinds of materials not mentioned herein. Presently, nonwoven or paper webs are slit longitudinally into two or more narrow webs as the web travels past arotating source cutter having a hardened steel blade with a circular, thin cutting edge projecting through the web to engage a rotating backup mandrel across which the web travels to a take-up winder. The thin cutting edge of the blade is usually biased to engage the mandrel. Some of the nonwoven fabrics formed of or with reinforcing filaments, for example, nylon filaments, have been found to be difficult to cut for extended periods of time.

Such nonwoven fabrics may be cut quite readily when the cutting edge is sharp, but the initial sharp edge of the cutting blade dulls with use, and the quality of cut deteriorates to where the web is not separated into narrow webs since portions of the web at the out are not completely severed through and fibers bridge the cut at spaced locations. More specifically, when severing webs of nonwoven fabrics formed of creped tissue and nylon reinforcing filaments conventional cutters have dulled so quickly that it has often been necessary to'project an additional blade into the cut to sever the bridging portions and complete the separation of the slit webs.

To improve the cutting life of the blade edge before it needs resharpening or replacement, attempts have been made to use harder materials, but this has not materially improved cutting efficiency. Materials such as ceramics and cermets have been applied to the cutting surfaces but these materials are brittle and tend to chip since the cross-sectional thickness of the cutting edge is thin and the resistance of such materials to chipping is less than metals fora thin cross-sectional cutting edge. While the surfaced blades have been found to resist wear by the web being out, these cutting edges have been marked by failure of the cutting edges apparently due to chipping caused by vibration or the chattering of the blade edge against the backup mandrel.

For some products, the kind and quality of cut edge is also important. For instance, paper or nonwoven fabrics which rub against or are in contact with the human skin, such as clothing, sheets or disposable diapers, preferably are formed with relative dull or nonsharp edges which will not cut or irritate the skin. Thus, disposable diapers have been saw cut from a continuous pad with a sawblade to prevent the formation ofa clean, sharp irritating cutting edge on the product. Thus, for some paper and nonwoven products, it is most desirableto produce a non-sharp and nonirritating edge for the sheet or web product.

Accordingly, an object of the invention is to provide a new and improved, as contrasted to the prior art, cutter and cutting apparatus.

These and other objects and advantages will become apparent from the detailed description taken in accordance with the accompanying drawings in which:

FIG. 1 is a fragmentary sectional view of a cutter and a cutting apparatus embodying the novel features of the invention;

FIG. 2 illustrates the cutter of FIG. I in a diagrammatic cutting operation;

FIG. 3 illustrates another cutter constructed in accordance with another embodiment of the invention;

FIG. 4 illustrates a further embodiment of the invention shown in elevation; and

FIG. 5 is a partial sectional view taken substantially along the line 55 of FIG. 4.

As shown in the drawings for purposes of illustration, the invention is embodied in a cutter 11 having a circular cutter blade 12 which is associated with or encapsu lated in a resilient means in the form of a sheath 13 of elastomeric material such as, for example, a rubber or a resilient, resinous plastic. This sheath is positioned adjacent a cutting edge 15 of the blade so that when the cutting edge 15 is brought into slitting position to cut a web 16, as illustrated in FIG. 2, moving across a backup means in the form of a cylindrical mandrel l7, portions or sections of the elastomeric sheath 13 are caused to flow laterally outwardly from and on opposite sides of the cutting blade edge 15 and thereby tension the sheet being cut. More specifically, the sections 18 adjacent the blade edge are compressed and flexed away from the blade edge and in so flexing exert forces on the web tensioning the same between the sections with the result that these flexed portions assist in breaking and pulling apart the fibers and filaments in the web and in separating them and thus separate the webs cut by the blade edge 15.

More specifically, as the blade edge 15 is brought into contact with the mandrel 17, the peripheral section of the sheath on opposite sides of the blade edge 15 are forced apart by the wedging action of the inclined side walls 20 of the blade 12. As the compressed sections 18 are engaged by the blade they are cammed and forced outwardly from the blade edge 15 while en gaging the web 16 at areas 16a and 16b (FIG. 2) on opposite sides of the cutting edge 15. As the sections 18 are compressed and cammed outwardly by the blade side walls 20, the areas and 1612 are subjected to forces tending to separate them as the cutting edge 15 breaks or crushes the fibers joining the web areas 16a and 16b. Hence, the outwardly directed forces from the sheath sections 18 assist in separating the fibers and in separating the web portions cut by the blade. As the fibers break or tear because of tension as well as being severed by the blade edge, the cut edges of the web are irregular with broken fibers in evidence, as in contrast, to sharp cutting edges where most of the fibers have sharply defined cuts.

As will be explained in more detail, the sheath means may be made in various ways to protect the cutting edge 15 by absorbing energy and dampening vibrations Y imparted to the blade. Also, the resilient sections 18 react against movement of the blade side walls 20 by fr'ictionally retarding the same and thereby retard the blade from moving along the mandrel 17. With some forms of sheath, the resilient material of the sheath is positioned between the blade and a supporting shaft therefore, to distribute and make more uniform any load applied by the shaft to the blade body.

Referring now more specifically to the drawings, the sheath 13 is formed of two annular rings 31 of resilient materials such as, for example, rubber or a resinous plastic material such as, for example, Adidreme, made by E. l. Du Pont de Nemours. The annular rings 31 may be bonded to opposite annular sides 32 of the knife body 33. The rings 31 abut inner annular walls 35 on the blade body 33 and are similarly bonded thereto. If the knife body 33 is formed of a metal the elastomeric material may be bonded directly thereto by known means. if the knife body 33 is fabricated from a ceramic as will be hereinafter described, a better bond may be obtained between the ceramic knife body 33 and the sheath rings 31 by first metalizing, i.e., applying a metal coating to the

walls

32 and 35 of the knife body 33, and then bonding the elastomeric rings 31 to the metal coatings.

To assist in the lateral outward displacement of the sections 18 relative to the inclined blade walls 20 on the knife body 33, these sections are free to slide relative to the inclined blade walls and are not bonded to the inclined blade walls 20 of the blade body. Also, in the illustrated embodiment of FIGS. 1 and 2, the cutting edge 15 is disposed radially inwardly of outer, annular, peripheral sheath surfaces 21 so that when the cutter is first positioned with the surfaces 21 abutting the web, the blade edge 15 will be disposed radially inward of the web and spaced therefrom by a gap such as, for example, three thirty-seconds of an inch. As the loading pressure for the cutter is continued, the cutting edge 15 continues toward the mandrel 17 and through the gap to abut the web 16 and then through the web 16 to engage the mandrel 17. As the cutter blade rtates, the sections 18 first engage the web and spread as the cutting edge moves into slitting engagement with the web traveling therepast.

When portions of the blade 11 rotate out of contact with the web 16, the compressed sections 18 on the sheath return to the position illustrated in FIG. 1. The gap between the sections 18 at the cutting edge 15 is defined by inwardly extending radial, parallel walls 49. The dimensions of the gap used may be quite small, for example, about one thirty-second of an inch in width between the parallel walls 49 and up to three thirtyseconds of an inch or more in depth depending upon the material being cut.

When the cutter body 33 is formed of a ceramic material, it is preferred that the cutting edge 15 have a slightly curved cross section, for example, formed with curved or arcuate radius of five to ten thousandths of an inch. Thus, the cutting edge 15 need not be a sharply honed fine edge as with conventional score cutting metal blades as the fibers are tensioned to separate when crushed and broken by the cutting edge 15. Also, rather than having a very finely tapered section between the walls 20, as in a metal section blade, the walls 20 may define a blunter cross section as illustrated. This construction results in additional strength against chipping. The wider angle B between the inclined blade walls 20 for a ceramic blade should be between about 45 and 90. With the ceramic blade the resilient compressed sections 18 frictionally retard movements of the cutting faces 20 out of their predetermined path and also act to absorb energy when being compressed by the blade. As the ceramic is hard, a Rockwell 45N hardness of 80 or more, it wears considerably less than does a softer metal steel blade.

The ceramic from which the blade is made is preferably a fine grained, smooth, fired element. Preferably, the crystal size of the particles in the ceramic are 10 microns or less and the fired element has a Rockwell 45N hardness of over about 80. Preferably, the ceramic has a surface finish in microinches (average) of 40 or less. The void volume after firing is preferably less than 12 percent and most desirably seven percent or less. Suitable ceramic materials from high purity aluminum oxide are manufactured by the Coors Porcelain Company of Golden, Colo. under the designations AD9O and AD999.

The mandrel 17 may be formed of a hardened steel or ceramic material. The illustrated mandrel 17 may be made of ceramic and in the form of a hollow cylinder.

having an outer cylindrical face to abut the blade edge 15. The illustrated multi-ply web may be, in this instance, formed of inner and outer plies of

creped tissue

53, 54 with inner reinforcing filaments in a layer 55. The reinforcing filaments may be of quite small size, for example, they may be made of nylon threads or a tow of nylon which has been spread into wide web and then secured to and between the respective plies of creped tissue.

In'the embodiment illustrated in FIGS. 1 and 2, the body of the cutter is formed with a central hub or flange having an inner circular wall 57 which may be attached to a rotatable supporting shaft 58. As the supporting shaft turns, wear will be distributed over the entire circumferential cutting edge 15. With the cutter illustrated in FIGS. 1 and 2, the ceramic body 33 is connected directly to the rotatable support shaft. Hence, the spring forces urging the cutting edge 15 to engage the mandrel are applied directly to the cutter body.

In the embodiment of the invention illustrated in FIG. 3, the sheath itself is formed with a circular hub portion 61 to fit on the supporting shaft, and the ceramic blade body 63 is, except for its cutting edge 15a, almost completely encapsulated in the elastomeric material. Thus, the force from the supporting shaft for urging the blade edge 15a against the mandrel 17 is applied through the compressible elastomeric medium, and the compressible medium is able to compress and expand to accommodate variations in loads applied by the shaft with a more uniform application of force at the blade edge. Stated differently, this additional cushioning of the blade body 63 from the supporting shaft results in a more even application of a load to the blade edge when the supporting shaft 58 is applying uneven loads or during vibration of the shaft and is desirable when a ceramic blade is employed.

As illustrated in FIG. 3, the sheath may be in the form of an annular body within which is a ring shaped blade body 63 having a circular, outer cutting edge 15a. The encapsulated blade body 63 is bonded along an inner circular wall 65 and a pair of radially extending side walls 67 to the surrounding sheath. The inclined blade side walls 20a are preferably not bonded to the adjacent sections 18a of the sheath. The gap between the sections exposes the blade edge 15a, and the sections 18a function as the similar sections 18 described in connection with the previously described embodiment of the invention. That is, these sections 18a of the sheath adjacent the inclined blade walls 20a are free to be displaced in the manner previously described for the sections 18a as the blade edge 15a is brought into engagement with the web and is caused to penetrate therethrough as it rotates and maintains engagement with themandrel. In the embodiment of FIG. 3, the

blade body 63 may be made of either metal or ceramic. When the body is formed of ceramic, it is preferred to metalize the radial side walls 63 so that the elastomeric may be tightly bonded thereto over wide areasthereof, rather than only at spaced points of contact.

Turning now to the further'embodiments of the invention illustrated in FIGS. 4 and 5, common numerals with a suffix b have been applied to this embodiment to elements which are identical to those previously described. In the embodiment of the invention of FIGS. 4 and 5, the ring shaped blade body 63b is smaller than the slitter body 63 (FIG. 3). With the forcing of the blade edge b against the mandrel and surfaces 21b against the web, the sections 18b will be compressed and displaced radially from the blade edge 15b as in previously described embodiments. As the sections 18b displace inwardly, they also flow laterally to tension the web.

In this instance, the sheath 13b has a particularly large portion or hub 61b intermediate the supporting shaft (not shown) which engages a sheath hub wall 69b and the blade body 63b. Thus, vibrations and uneven loads being applied will be cushioned in the elastomeric hub 61b and cutting edge 15b of the ceramic body is being protected against undue pressure or chattering which would cause the same to crack or chip.

By way of example only, dimensions for one specific embodiment of the invention will be given, namely for the embodiment illustrated in FIG. 5. The sheath has a 3.062 inch outer diameter with the blade edge 15b terminating three thirty-seconds inch radially inwardly of the outer circumference of the sheath. A inch diameter circular opening is provided at the hub. The width of the sheath is three-eighths inch between the outer flat side walls 73 of the sheath. In this instance, the angle B between the inclined blade walls 20b is 90. The internal cutter body 63b is formed of ceramic, while the outer resilient sheath material is formed of an elastomeric such as Adidreme. The sheath 13 is bonded to the ceramic by an adhesive such as an epoxy adhesive.

From the foregoing, it will be seen that the present invention provides a cutting blade which may be encapsulated in a resilient sheath to protect the blade edge from chipping or otherwise being damaged should the blade be vibrated relative to a supporting backup roller or mandrel. Also, it will be seen that the unique compressed portions operate to absorb energy and protect the blade, particularly if the same has a ceramic cutting edge. Thus, there may be provided a cutting device which includes an elastomeric body with a ceramic insert having compressed portions adjacent a cutting edge on the ceramic insert to protect the latter from chipping due to vibrations.

Moreover, the invention also discloses placing the web in tension between oppositely directed forces which act in directions transverse to the direction of the cut being formed so that the fibers are pulled apart and are torn rather than being sharply cut as would be irritating to the skin if the cut product is used in clothing or diapers. The cutter is also made so that the same may be made simply and cheaply.

While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

l. A cutter for cutting a piece of material comprising a blade body formed of a hard brittle non-metallic material, a circular cutting edge on said blade body for cutting the material, resilient means fastened to said blade body, and compressible sections on said resilient means for engaging said material and for being com pressed when said cutting edge is cutting the material for absorbing energy and dampening vibrations to prevent chipping of said circular cutting edge, said resilient means substantially encapsulating said blade body and being bonded thereto along radially extending walls of said body, said blade body being formed with inclined walls adjacent said cutting edge for camming said sections of the resilient means outwardly from said cutting edge.

2. A cutter in accordance with claim 1 in which said resilient means is formed of an elastomeric material and in which means bonds said elastomeric material to said blade body over a major portion thereof and in which said compressible sections are unbonded to said blade body and free to move relative to said cutting edge.

3. A cutter for slitting a web comprising an annular blade body formed of ceramic material, an outer continuous, uninterrupted circular cutting edge on said ceramic blade body for engaging and cutting the web, inclined side walls on said blade body adjacent said circular cutting edge, and elastomeric means fastened to said blade body for absorbing energy and dampening vibrations to prevent chipping of said circular cutting edge, said elastomeric means having portions thereof engaging said inclined walls of said blade body, said portions extending radially outward of said cutting edge and free to slide relative to said inclined side walls, said portions being compressible radially inwardly to slide along said side walls to expose said cutting edge for engagement with said web, and said portions being displaceable laterally relative to portions of said blade body in a direction transverse to that of the cut to tension the web during cutting.

4. A cutter in accordance with claim 3 in which outer, circular, web engaging surfaces on said elastomeric means project radially outwardly of said cutting edge until said cutting edge is forced into and through said web, said web engaging surfaces being displaced radially inwardly from the cutting edge by a distance equal to the thickness of the web.

5. A cutter in accordance with claim 4 in which the portions of said elastomeric means engaging said inclined surfaces are separated by a gap through which said cutting edge may move to engage said web.

6. A cutter in accordance with claim 3 in which said elastomeric means covers substantially all of said blade body except for the cutting edge.

7. A cutter in accordance with claim 3 in which said inclined walls on said blade body diverge outwardly from said cutting edge and include an angle of from 45 to

Claims

1. A cutter for cutting a piece of material comprising a blade body formed of a hard brittle non-metallic material, a circular cutting edge on said blade body for cutting the material, resilient means fastened to said blade body, and compressible sections on said resilient means for engaging said material and for being compressed when said cutting edge is cutting the material for absorbing energy and dampening vibrations to prevent chipping of said circular cutting edge, said resilient means substantially encapsulating said blade body and being bonded thereto along radially extending walls of said body, said blade body being formed with inclined walls adjacent said cutting edge for camming said sections of the resilient means outwardly from said cutting edge.

7. A cutter in accordance with claim 3 in which said inclined walls on said blade body diverge outwardly from said cutting edge and include an angle of from 45* to 90*.