Metallic card wire

Abstract

The metallic card wire (100) includes a rib portion (110) and a plurality of teeth (115). The teeth have a tip segment (117), a front portion (120), a back portion (130), two sides (141, 142) and an interconnection section connecting the back portion of a tooth to the front portion of the previous tooth. The teeth lean in the card wire longitudinal direction. The teeth's front portion leans towards the longitudinal direction. The front portion includes an undercut segment where the included angles of the tangents to the front portion with the longitudinal direction of the card wire are smaller than the included angles of the tangents to the front portion with the longitudinal direction of the card wire between the undercut segment and the tip segment. At least one side of the teeth includes at least a first structural element for increasing the frictional force of fibers relative to the side of the teeth and positioned closer to the tip segment compared to the undercut segment's position.

Claims

1. Metallic card wire comprising: a rib portion and a plurality of teeth; wherein individual ones of the plurality of teeth have a tip segment, a front portion, a back portion, two sides and an interconnection section; wherein the interconnection section connects the back portion of a tooth of the plurality of teeth to the front portion of a previous tooth of the plurality of teeth; wherein the tip segment is where the front portion and the back portion merge; wherein the teeth are leaning in a longitudinal direction of the card wire; wherein the front portion is where the teeth are leaning towards the longitudinal direction of the teeth, wherein at least one side of the teeth comprises at least a first structural element comprising an indentation and/or protrusion configured to increase a frictional force of fibers relative to the at least one side of the teeth, wherein the at least a first structural element comprising an indentation and/or protrusion is positioned closer to the tip segment compared to any undercut segment; wherein the front portion comprises the undercut segment; wherein the undercut segment is a segment of the front portion of the card wire, wherein in the undercut segment included angles of tangents to the front portion with the longitudinal direction of the card wire are smaller than included angles of tangents to the front portion of the card wire with the longitudinal direction of the card wire in a zone between the undercut segment and the tip segment.

2. A metallic card wire as in claim 1, wherein the at least a first structural element comprises an indentation in the at least one side of the teeth.

3. A metallic card wire as in claim 2, wherein the indentation is a groove.

4. A metallic card wire as in claim 2, wherein a largest depth of the indentation is more than 0.03 mm.

5. A card wire as in claim 1, wherein the at least a first structural element comprises one or more protrusions from the at least one side of the teeth.

6. A card wire as in claim 5, wherein the protrusion is a ridge.

7. A card wire as in claim 5, wherein a largest height of the protrusion is more than 0.03 mm.

8. A metallic card wire as in claim 1; wherein the back portion has a tangent forming a back angle with the longitudinal direction of the card wire; wherein the zone of the front portion above the undercut segment has a tangent forming a tip angle with the rib portion; wherein the undercut segment is configured to retain fibers; wherein the undercut segment has a tangent forming an included undercut angle with the longitudinal direction of the card wire; wherein the undercut angle is at each point in the undercut segment greater than a maximum of the back angle and smaller than a smallest value of the tip angle to allow rotary punching.

9. A metallic card wire as in claim 1, wherein the front portion comprises at least three sections including a first section extending from the tip segment of the tooth in the direction of the rib portion and a second section extending below the first section toward the rib portion, wherein the second section comprises the undercut segment; wherein the second section comprises a straight part and a curved segment, the straight part has a minimum length of 0.10 mm and the straight part has an angle between 10 and 30 degrees relative to the longitudinal direction of the card wire, and the straight part is followed in the direction of the rib portion by the curved segment wherein the curved segment has a radius of at least 0.18 mm; and the front portion comprises a third section from an end of the second section to an interconnection section.

10. A metallic card wire as in claim 1, wherein the undercut segment is a bottom part of an embossment on the front portion of the metallic card wire.

11. A metallic card wire as in claim 1, wherein the back portion comprises an embossment.

12. A metallic card wire as in claim 1, wherein one or both sides of the teeth comprise one or more additional structural elements, located at a height of the undercut segment and/or below the undercut segment.

13. A metallic card wire as in claim 1, wherein both sides of the teeth have over their surface a mat appearance as caused by a blasting operation with abrasive particles.

14. A metallic card wire as in claim 1, wherein both sides of the teeth have over their surface a roughness value Ra between 0.2 and 0.33 μm.

15. A metallic card wire as in claim 1, wherein a thickness of the teeth at a tip is less than 0.25 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a longitudinal view of a metallic card wire according to the invention.

(2) FIG. 2 shows the cross section of the card wire of FIG. 1.

(3) FIGS. 3 and 4 show examples of alternative cross sections of metallic card wires according to the invention

(4) FIGS. 5 and 6 show other examples of teeth of card wires according to the invention.

DETAILED DESCRIPTION

(5) In the figures, same numerals indicate same objects.

(6) FIG. 1 shows a longitudinal view of a metallic card wire 100 according to the invention.

(7) FIG. 2 shows the cross section of the card wire of FIG. 1. The metallic card wire comprises a rib portion 110 and a plurality of teeth 115. The teeth 115 have a tip segment 117, a front portion 120, a back portion 130, two sides 141, 142 and an interconnection section 150, connecting the back portion 130 of a tooth to the front portion 120 of the previous tooth. The front portion 120 comprises an undercut segment 160. The undercut segment 160 is a segment of the front portion 120 of the card wire 110 where the included angles y of the tangents to the front portion with the longitudinal direction of the card wire are smaller than the included angles ε of the tangents to the front portion of the card wire with the longitudinal direction of the card wire in the zone between the undercut segment and the tip segment 117. One side 141 of the teeth comprises a longitudinal groove 174 parallel with the rib portion 110. The groove 174 is positioned closer to the tip segment 117 compared to the position of the undercut segment 160. The depth of the groove 174 at its deepest point is e.g. 0.06 mm from the plane of the side 140 of the teeth. In a preferred embodiment the groove has at its deepest part a section that is substantially flat. The teeth 115 have two additional longitudinal grooves 195, 196; wherein one additional longitudinal groove 195 is located at the height of the undercut segment 160 and one additional longitudinal groove 196 is located below the undercut segment 160.

(8) The back portion 130 of the exemplary card wire 100 of FIG. 1 has a tangent forming a back angle β with the longitudinal direction of the card wire 100. The zone above the undercut segment 160 has a tangent forming a tip angle μ with the longitudinal direction of the card wire 100. The undercut segment is capable of retaining fibers. The undercut segment has a tangent forming an included angle γ, the undercut angle γ, with the longitudinal direction of the card wire. The undercut angle γ is at each point in the undercut segment 160 greater than the maximum of the back angle β and smaller than the smallest value of the tip angle μ in order to allow rotary punching. The thickness of the tooth at the tip A is e.g. 0.25 mm or e.g. 0.20 mm. As an example, the maximum of back angle β is 20°; the undercut angle γ is 35° and the smallest value of the tip angle μ equals 50°.

(9) FIG. 3 shows an example of an alternative cross section of a metallic card wire according to the invention. Both sides 141, 142 are provided with a longitudinal groove 174 between the undercut segment 160 and the tip segment 117. Additionally and optionally, the teeth can e.g. be provided with a longitudinal groove 195 at the height of the undercut segment 160 and/or below the undercut segment 160.

(10) One or more grooves on the teeth can be replaced by longitudinal ridges, e.g. as shown in the cross section of an inventive metallic card wire in FIG. 4. One side 141 is provided with a longitudinal ridge 175 between the undercut segment 160 and the tip segment 117. Additionally and optionally, the teeth can e.g. be provided with a longitudinal ridge 197 at the height of the undercut segment 160. It is also possible to provide one or more ridges below the undercut segment 160, and/or to provide ridges at both sides; and/or to provide combinations of ridges and grooves.

(11) FIG. 5 shows an example of a tooth of a card wire according to the invention. The tooth shows on one of its sides 141, above the undercut segment 161 (which is in this wire parallel with the longitudinal direction of the card wire, but could be any other type of undercut segment) an indentation 176.

(12) FIG. 6 shows an example of a tooth of a card wire according to the invention. The tooth shows on one of its sides 141, above the undercut segment 161 (which is in this wire the bottom part of an embossment 192 on the front portion 120 of the metallic card wire, but could be any other type of undercut segment) a longitudinal groove 174. Optionally, the tooth can have an embossment 193 in the back portion 130 of the card wire. Optionally, the tooth can have a longitudinal groove 195 at the height of the embossment 192.

(13) Each of the examples of card wires shown can be treated to provide the sides of the teeth (and possibly the sides of the card wire) over their surface with a mat appearance as caused by a blasting operation with abrasive particles; and/or to provide the sides of the teeth (and possibly also the sides of the card wire) to have over their surface a roughness value Ra between 0.2 and 0.33 μm. Such surface can be achieved by means of a blasting operation with abrasive particles as is known in the art.