Tinkle-free knitted wire mesh filters and methods for making such filters
“Tinkles” (also known as “gotchas”) (see reference number 20 in FIGS. 1 and 2 ) are portions of knitted metal loops produced when a tube of knitted wire mesh is cut into individual pieces. In the prior art, tinkles have been considered a fact of life and the approach has been to try to shake them out of the mesh or immobilize them on or in the mesh. By producing a knitted tube ( 11 ) having alternating segments ( 12,13 ) of knitted rows of yarn and knitted rows of wire, completely tinkle-free knitted socks are produced which are used to produce completely tinkle-free knitted wire mesh filters. Knitted wire mesh filters that cannot release tinkles because they do not have any tinkles can be used in such applications as fuel filters and airbag filters.
1. A method of making a plurality of knitted wire mesh filters each of which is free of tinkles comprising:
(I) producing a knitted tube that comprises (i) a plurality of knitted segments comprising knitted rows of wire, said knitted segments being referred to as knitted wire segments, and (ii) a plurality of knitted segments comprising knitted rows of yarn, said knitted segments being referred to as knitted yarn segments, the knitted wire segments alternating with the knitted yarn segments;
(II) producing a plurality of separated knitted wire segments without cutting any loops of knitted wire and thus without producing any tinkles, where a separated knitted wire segment is a knitted wire segment that has been separated from the knitted tube of step (I); and
(III) producing the plurality of knitted wire mesh filters from the plurality of separated knitted wire segments, each of the plurality of knitted wire mesh filters comprising a plurality of knitted rows of wire and being tinkle free;
wherein step (II) comprises treating the knitted tube or a separated portion thereof to remove yarn.
2. The method of claim 1 wherein the knitted tube or the separated portion thereof is treated with a solvent in which (i) the wire is insoluble and (ii) at least a portion of the yarn is soluble.
3. The method of claim 2 wherein:
(i) the yarn comprises fibers that are bonded to one another by an adhesive;
(ii) the fibers are insoluble in the solvent; and
(iii) the adhesive is soluble in the solvent.
4. The method of claim 3 wherein the adhesive comprises polyvinyl alcohol and the solvent comprises water.
5. The method of claim 4 wherein the fibers comprise a polyester polymer.
6. The method of claim 1 wherein the breaking strength of the yarn is equal to or greater than 50 percent of the yield strength of the wire times the wire's cross-sectional area.
7. The method of claim 1 wherein the knitted tube is produced using a circular knitting machine.
8. A method of making a plurality of knitted wire mesh filters each of which is free of tinkles comprising:
(I) producing a knitted tube that comprises (i) a plurality of knitted segments comprising knitted rows of wire, said knitted segments being referred to as knitted wire segments, and (ii) a plurality of knitted segments comprising knitted rows of yarn, said knitted segments being referred to as knitted yarn segments, the knitted wire segments alternating with the knitted yarn segments;
(II) producing a plurality of separated knitted wire segments without cutting any loops of knitted wire and thus without producing any tinkles, where a separated knitted wire segment is a knitted wire segment that has been separated from the knitted tube of step (I); and
(III) producing the plurality of knitted wire mesh filters from the plurality of separated knitted wire segments, each of the plurality of knitted wire mesh filters comprising a plurality of knitted rows of wire and being tinkle free;
wherein the knitted wire segments are connected to one another by non-knitted sections of wire that span the intervening knitted yarn segments and step (II) comprises:
(A) cutting knitted yarn segments and non-knitted sections of wire to free knitted wire segments from the knitted tube; and
(B) treating the freed knitted wire segments to remove the yarn.
9. The method of claim 8 wherein the cutting of step (II)(A) is performed on-line as the knitted tube is being produced.
10. The method of claim 8 wherein the cutting of step (II)(A) is performed off-line on a completed knitted tube.
11. The method of claim 8 wherein the freed knitted wire segments are treated with a solvent in which (i) the wire is insoluble and (ii) at least a portion of the yarn is soluble.
12. The method of claim 11 wherein:
(i) the yarn comprises fibers that are bonded to one another by an adhesive;
(ii) the fibers are insoluble in the solvent; and
(iii) the adhesive is soluble in the solvent.
13. The method of claim 12 wherein the adhesive comprises polyvinyl alcohol and the solvent comprises water.
14. The method of claim 13 wherein the fibers comprise a polyester polymer.
15. The method of claim 8 wherein the breaking strength of the yarn is equal to or great than 50 percent of the yield strength of the wire times the wire's cross-sectional area.
16. The method of claim 8 wherein the knitted tube is produced using a circular knitting machine.