US 4,075,936 AGranted

Method and apparatus for making tobacco smoke filter

AssigneeAmerican Filtrona Corporation

InventorRichard M. Berger

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Abstract

Tobacco smoke filters and methods and means for making same wherein the products have both internal and external cavities, with the external cavities being of a limited nature so as to provide a substantially smooth outer surface for attaching conventional plug wrap without the need for an internal glue line. The external cavities comprise from about 5 to no more than 50 percent of the total outer surface of the inner filter member, preferably between about 20 and 30 percent. This enables the inner filter member to provide substantially uniform support to the overwrap. The outer cavities may be in the form of elongated, discrete, grooves, a knurled-like pattern or a continuous helical groove. The resultant filter has high filtration and correspondingly low pressure drop characteristics, with the technique of manufacture being such as to permit higher production speeds than with the prior art, resulting in lower manufacturing costs. The outer grooves are formed by various mechanical ironing or grooving techniques, by crimping or by utilizing jets of steam.

Claims15

Dependent claims

A method of making smoke filter means comprising the steps of:

a. providing a bondable filtering material including a multiplicity of fibrous members;
b. continuously passing said filtering material into and through an elongated bonding zone and, intermediate the passage of said filtering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous members of said filtering material to each other at spaced contact points thereby forming an elongated, smoke-permeable, rod defining a tortuous path for passage of smoke therethrough;
c. during the passage of said filtering material through said bonding zone, positioning a mandrel generally axially of said bonding zone to define an annular space through which said filtering material must pass;
d. reciprocating said mandrel in timed relationship to the passage of said filtering material through said bonding zone between a first position, at least as far forward in the path of travel of said filtering material as the point at which said filtering material is contacted by said bond activating agent, to thereby produce a smoke-permeable annular wall of bonded fibrous members as said filtering material passes said point, and a second position, sufficiently rearwardly of said point in the path of travel of said material to permit a portion of said filtering material to extend tranversely completely across said bonding zone before reaching said point, to thereby produce a smoke-permeable plug section of bonded fibrous members as said filtering material passes said point, said annular wall and said plug sections being integral with each other, whereby said rod is provided with intermittent inner cavity means totally enclosed and surrounded by said annular wall and by plug sections forwardly and rearwardly thereof;
e. covering said rod with a smoke-permeable plug wrap;
f. forming outer cavity means on the exterior surface of said rod, said outer cavity means being axially spaced from each other at least a position on either side of a transverse axis intermediate each inner cavity means, the area of said outer cavity means forming a minor portion of the total exterior surface of said rod;
g. overwrapping said rod with an overwrapping material so as to juxtapose portions of the inner surface of said overwrapping material with peripheral portions of the exterior surface of said rod to form sealed areas precluding passage of smoke thereacross;
and
h. transversely severing said overwrapped rod at selected locations to form filter elements.

6 more elements

A method of making smoke filter means comprising the steps of:

a. providing a bondable filtering material including a multiplicity of fibrous members;
b. continuously passing said filtering material into and through an elongated bonding zone and, intermediate the passage of said filtering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous members of said filtering material to each other at spaced contact points thereby forming an elongated, smoke-permeable, rod defining a tortuous path for passage of smoke therethrough;
c. during the passage of said filtering material through said bonding zone, positioning a mandrel generally axially of said bonding zone to define an annular space through which filtering material must pass;
d. reciprocating said mandrel in timed relationship to the passage of said filtering material through said bonding zone between a first position, at least as far forward in the path of travel of said filtering material as the point at which said filtering material is contacted by said bond activating agent, to thereby produce a smoke-permeable annular wall of bonded fibrous members as said filtering material passes said point, said annular wall and said plug sections being integral with each other, whereby said rod is provided with intermittent inner cavity means totally enclosed and surrounded by said annular wall and by plug sections forwardly and rearwardly thereof;
e. forming outer cavity means on the exterior surface of said rod by continuously moving said rod through a zone into which a plurality of radially extending, circumferentially spaced, jets of steam are intermittently projected, said outer cavity means being axially spaced from each other at least at a position on either side of a transverse axis intermediate each inner cavity means, the area of said outer cavity means forming a minor portion of the total exterior surface of said rod;
f. overwrapping said rod with an overwrapping material so as to juxtapose portions of the inner surface of said overwrapping material with peripheral portions of the exterior surface of said rod to form sealed areas precluding passage of smoke thereacross;
and
g. transversely severing said overwrapped rod at selected locations to form filter elements.

5 more elements

An apparatus for making smoke filter means comprising:

a. a source of a bondable filtering material including a multiplicity of fibrous members;
b. means defining an elongated bonding zone;
c. means for continuously feeding said filtering material into and through said bonding zone;
d. means for feeding a bond activating agent into said bonding zone and into contact with said filtering material at a point intermediate the path of travel of said filtering material through said bonding zone to bond said fibrous members of said filtering material to each other at spaced contact points, thereby forming an elongated, smoke-permeable, rod defining a tortuous path for passage of smoke therethrough;
e. elongated mandrel means having a forward end portion axially positioned within said means defining said bonding zone to define an annular space through which said filtering material must pass;
f. means for reciprocating said mandrel means within said bonding zone in timed relationship to the passage of said filtering material through said bonding zone between a first position wherein said forward end portion extends at least as far forwardly in the parth of travel of said filtering material as the point at which said filtering material is contacted by said bond activating agent, to thereby produce a smoke-permeable annular wall of bonded fibrous members as said filtering material passes said point, and a second position wherein said forward end portion extends sufficiently rearwardly of said point in the path of travel of said filtering material to permit a portion of said filtering material to extend transversely completely across said bonding zone before reaching said point, to thereby produce a smoke-permeable plug section of bonded fibrous members as said filtering material passes said point, said annular wall and said plug sections being integral with each other, whereby said rod is provided with intermittent inner cavities totally enclosed and surrounded by said annular wall and by plug sections forwardly and rearwardly thereof;
g. means for covering said rod with a smoke-permeable plug wrap;
h. forming means for forming outer cavity means on the exterior surface of said rod, said forming means producing outer cavity means axially spaced from each other at a position on either side of a transverse axis intermediate each inner cavity means with the surface area of said outer cavity means forming a minor portion of the total exterior surface of said rod;
i. means for overwrapping said rod with an overwrapping material so as to juxtapose portions of the inner surface of said overwrapping material with peripheral portions of the exterior surface of said rod to form sealed areas precluding passage of smoke thereacross;
and
j. severing means for transversly severing said overwrapped rod at selected locations to form filter elements.

8 more elements

An apparatus for making smoke filter means comprising:

a source of a bondable filtering material including a multiplicity of fibrous members;
b. means defining an elongated bonding zone;
c. means for continuously feeding said filtering material into and through said bonding zone;
d. means for feeding a bond activating agent into said bonding zone and into contact with said filtering material at a point intermediate the path of travel of said filtering material through said bonding zone to bond said fibrous members of said filtering material to each other at spaced contact points, thereby forming an elongated, smoke-permeable, rod defining a tortuous path for passage of smoke therethrough;
e. elongated mandrel means having a forward end portion axially positioned within said means defining said bonding zone to define an annular space through which said filtering material must pass;
f. means for reciprocating said mandrel means within said bonding zone in timed relationship to the passage of said filtering material through said bonding zone between a first position wherein said forward end portion extends at least as far forwardly in the path of travel of said filtering material as the point at which said filtering material is contacted by said bond activating agent, to thereby produce a smoke-permeable annular wall of bonded fibrous members as said filtering material passes said point, and a second position wherein said forward end portion extends sufficiently rearwardly of said point in the path of travel of said filtering material to permit a portion of said filtering material to extend transversely completely across said bonding zone before reaching said point, to thereby produce a smoke-permeable plug section of bonded fibrous members as said filtering material passes said point, said annular wall and said plug sections being integral with each other, whereby said rod is provided with intermittent inner cavities totally enclosed and surrounded by said annular wall and by plug sections forwardly and rearwardly thereof;
g. forming means comprising means for intermittently projecting radially extending jets of steam into contact with said rod as said rod is continuously moved past said jets for forming outer cavity means on the exterior surface of said rod, said forming means producing outer cavity means axially spaced from each other at a position on either side of a transverse axis intermediate each inner cavity means with the surface area of said outer cavity means forming a minor portion of the total exterior surface of said rod;
h. means for overwrapping said rod with an overwrapping material so as to juxtapose portions of the inner surface of said overwrapping material with peripheral portions of the exterior surface of said rod to form sealed areas precluding passage of smoke thereacross;
and
i. severing means for transversely severing said overwrapped rod at selected locations to form filter elements.

7 more elements

Dependencies are inferred from the claim text.