Slitter with sharpness retention capability

Claim 2

A slitter assembly for slitting a traveling web of material, comprising, a rotatable slitter band having an annular slitting lip of a predetermined radial thickness, the circumferential and one radial surface of said band lip forming a sharp corner which extends in a circle about the axis of said band, a rotating slitter blade adjacent the band such that the band and the blade overlap a predetermined amount along a line connecting the centers of the band and blade, the blade also having a lip of predetermined radial thickness, the thickness of each lip being approximately one-third the distance of said overlap along said line connecting the centers of the band and blade, the circumferential and one radial surface of said blade lip forming a sharp corner which extends in a circle about the axis of said blade, the approach side of the band and blade being tilted inwardly toward each other such that the two said sharp corners intersect each other at substantially a point which is on the web approach side of the slitter assembly, the arrangement being such that when the lips wear inwardly from the sharp corners in an axial direction, the lips will engage along a line located rearward of the location of the original said point, wherein the thickness of said lip determines the distance, in the direction of travel of the web, between the said original point and the said line, and wherein said lip thickness also determines the upper limit of lateral separation between the two lips at the location of the original said point after wear has taken place.

Claim 3

A slitter assembly according to claim 1, wherein the diameter of the band and blade are 8.0 inches and 8.5 inches, respectively, and wherein the said distance of overlap is approximately 0.034 inches and the thickness of each lip is approximately 0.011 inches.

Claim 4

A slitter assembly according to claim 1, wherein the diameter of the blade and band are approximately 8.0 inches and 10.5 inches, respectively, and wherein the said distance of overlap is approximately 0.062 inches and the thickness of each lip is approximately 0.020 inches.

Claim 5

A slitter assembly according to claim 1, wherein at least one of said blade or band is disc-shaped and the said lip thereof is bounded on its outer side by the outer peripheral surface of the disc and wherein said lip is bounded on its radial inner side by an annular recessed portion formed in the radial face.

Claim 6

A slitter assembly according to claim 4, including a plastic filler material in said recessed portion.

Claim 7

A slitter assembly for slitting a traveling web of material, comprising, a rotatable slitter band having an annular slitting lip of a predetermined radial thickness, the circumferential and one radial surface of said band lip forming a sharp corner which extends in a circle about the axis of said band, a rotating slitter blade adjacent the band such that the band and the blade overlap slightly along a line connecting the centers of the band and blade, the blade also having a lip of predetermined radial thickness, the circumferential and one radial surface of said blade lip forming a sharp corner which extends in a circle about the axis of said blade, the approach side of the band and blade being tilted inwardly toward each other such that the two said sharp corners intersect each other at substantially a point which is on the web approach side of the slitter assembly, the arrangement being such that when the lips wear inwardly from the sharp corners in an axial direction, the lips will engage along a line located rearward of the location of the original said point, wherein the thickness of said lip determines the distance, in the direction of travel of the web, between the said original point and the said line, and wherein said lip thickness also determines the upper limit of lateral separation between the two lips at the location of the original said point after wear has taken place, and wherein each lip comprises a radial inner portion of a first hardness and an outer layer of much greater hardness, the outer layer being approximately 0.002 inches to about 0.015 inches and the inner portion being approximately 0.015 inches to 0.025 inches.

Claim 8

A slitter assembly for slitting a traveling web of material, comprising, a rotatable slitter band having an annular slitting lip of a predetermined radial thickness, the circumferential and one radial surface of said band lip forming a sharp corner which extends in a circle about the axis of said band, a rotating slitter blade adjacent the band such that the band and the blade overlap slightly along a line connecting the centers of the band and blade, the blade also having a lip of predetermined radial thickness, the circumferential and one radial surface of said blade lip forming a sharp corner which extends in a circle about the axis of said blade, the approach side of the band and blade being tilted inwardly toward each other such that the two said sharp corners intersect each other at substantially a point which is on the web approach side of the slitter assembly, the arrangement being such that when the lips wear inwardly from the sharp corners in an axial direction, the lips will engage along a line located rearward of the location of the original said point, wherein the thickness of said lip determines the distance, in the direction of travel of the web, between the said original point and the said line, and wherein said lip thickness also determines the upper limit of lateral separation between the two lips at the location of the original said point after wear has taken place, and wherein each lip comprises a radial inner portion of a first hardness and an outer layer of much greater hardness, the outer layer being approximately 0.002 inches to about 0.015 inches and the inner portion being approximately 0.015 inches to 0.025 inches.

Claim 9

A slitter assembly for slitting a traveling web of material, comprising, a rotatable slitter band having an annular slitting lip of a predetermined radial thickness, the circumferential and one radial surface of said band lip forming a sharp corner which extends in a circle about the axis of said band, a rotating slitter blade adjacent the band such that the band and the blade overlap slightly along a line connecting the centers of the band the blade, the blade also having a lip of predetermined radial thickness, the circumferential and one radial surface of said blade lip forming a sharp corner which extends in a circle about the axis of said blade, the approach side of the band and blade being tilted inwardly toward each other such that the two said sharp corners intersect each other at substantially a point which is on the web approach side of the slitter assembly, the arrangement being such that when the lips wear inwardly from the sharp corners in an axial direction, the lips will engage along a line located rearward of the location of the original said point, wherein the thickness of said lip determines the distance, in the direction of travel of the web, between the said original point and the said line, and wherein said lip thickness also determines the upper limit of lateral separation between the two lips at the location of the original said point after wear has taken place, and wherein the radial thickness of each said lip is between 0.010 inches and 0.015 inches.

Claim 10

A slitter assembly for slitting a traveling web of material, comprising, a rotatable slitter band having an annular slitting lip of a predetermined radial thickness, the circumferential and one radial surface of said band lip forming a sharp corner which extends in a circle about the axis of said band, a rotating slitter blade adjacent the band such that the band and the blade overlap slightly along a line connecting the centers of the band the blade, the blade also having a lip of predetermined radial thickness, the circumferential and one radial surface of said blade lip forming a sharp corner which extends in a circle about the axis of said blade, the approach side of the band and blade being tilted inwardly toward each other such that the two said sharp corners intersect each other at substantially a point which is on the web approach side of the slitter assembly, the arrangement being such that when the lips wear inwardly from the sharp corners in an axial direction, the lips will engage along a line located rearward of the location of the original said point, wherein the thickness of said lip determines the distance, in the direction of travel of the web, between the said original point and the said line, and wherein said lip thickness also determines the upper limit of lateral separation between the two lips at the location of the original said point after wear has taken place, and wherein the radial thickness of each said lip is between 0.010 inches and 0.015 inches.

Claim 11

A slitter assembly according to claim 7, wherein the lip extends inwardly from said sharp corner in the axial direction for approximately 0.062 inches.

Claim 12

A slitter assembly according to claim 8, wherein the radial face of each disc opposite from that face having the lip formed thereon is generally flat, and wherein the said sharp corner of the lip is spaced axially from said flat face less than a central part of the disc.

Claim 13

A slitter assembly according to claim 7, wherein the toe-in angle between the blade and the band is between 0.7* and 1.0* .

Claim 14

The slitter assembly of claim 7, wherein each lip is of substantially uniform hardness throughout its radial thickness.

Claim 15

Apparatus for slitting a traveling web comprising: a blade member and a band member, each having an axis of rotation with a concentrically circular outer portion thereabout, a peripheral hardened slitter edge on said outer portion, a face surface extending radially inwardly a predetermined distance from said slitter edge toward said axis of rotation; said axis being in parallel horizontal planes, and offset from one another in vertical planes at an included angle, with at least one of said blade and band members being offset with the respect to the direction of web travel so that at least one of said blade and band members intercepts said web at a small toe-in angle; said blade is positioned with its axis of rotation vertically above the axis of said band a distance such that the respective face surfaces overlap a distance at least as great as their combined radial extension; pressure means supporting said blade and band members about their axes of rotation and urging them together on the side toward said oncoming web so that point contact is maintained at the inTersection of said hardened edges and line contact extending from said point contact is maintained between each said hardened edge and the corresponding face surface on the other member.

Claim 16

Apparatus for slitting a traveling web comprising: a blade member and a band member, each having an axis of rotation with a concentrically circular outer portion thereabout, a peripheral hardened slitter edge on said outer portion, a face surface extending radially inwardly a predetermined distance from said slitter edge toward said axis of rotation; said axis being in parallel horizontal planes, and offset from one another in vertical planes at an included angle, with at least one of said blade and band members being offset with the respect to the direction of web travel so that at least one of said blade and band members intercepts said web at a small toe-in angle; said blade is positioned with its axis of rotation vertically above the axis of said band a distance such that the respective face surfaces overlap a distance at least as great as their combined radial extension; pressure means supporting said blade and band members about their axes of rotation and urging them together on the side toward said oncoming web so that point contact is maintained at the inTersection of said hardened edges and line contact extending from said point contact is maintained between each said hardened edge and the corresponding face surface on the other member.

Claim 17

Apparatus as set forth in claim 12, wherein: said included angle is such that when said hardened slitter edges are in the range of from about 0.002 to about 0.015 inches, a gap of less than about 75 microinches opens on the oncoming side of the slitting members when the hardened edges are worn.

Claim 18

Apparatus as set forth in claim 12, wherein: said included toe-in angle between said blade and band members is between from about 0.7* to about 1.0* .

Claim 19

Apparatus as set forth in claim 12, wherein: said slitter edges on said blade and band members are each of substantially equal hardness: said hardened edges are more wear resistant than said face surfaces of said blade and band members.

Claim 20

Apparatus as set forth in claim 15, wherein: said slitter edge of said blade and band members are hardened to a depth of from about 0.002 to about 0.015 inches.