Card wire

Abstract

The card wire comprises a plurality of teeth inclined at an angle with the rib portion. The teeth have a front portion and a back portion joining at the tip of the teeth; and a base segment connecting the front portion to the back portion of the preceding tooth. The front portion is the inner portion of the tooth leaning towards the rib portion. The back portion is the outer portion of the tooth. The front portion comprises at least two undercut segments. The second undercut segment is spaced further away from the tip of the tooth than the first undercut segment. Each undercut segment has an undercut angle, being the minimum of the angles with the longitudinal direction of the card wire, of the tangents to each point of the part of the undercut segment goingwhen observed from the tipinwards from the front portion.

Claims

1. A card wire (100, 300, 400), comprising: a rib portion (103, 303, 403); and a plurality of teeth (105, 305, 405) along a length of the rib portion (103, 303, 403), wherein the plurality of teeth (105, 305, 405) are inclined at an angle with respect to the rib portion (103, 303, 403), wherein the teeth have a front portion (107,307,407) and a back portion (109, 309, 409), wherein the front portion (107, 307, 407) is an inner portion of the tooth leaning towards the rib portion (103, 303, 403) and the back portion (109, 309, 409) is an outer portion of the tooth, wherein the front portion (107, 307, 407) and the back portion (109, 309, 409) of the tooth join at a tip of the tooth (111, 311, 411); wherein the teeth have a base segment (113, 313, 413) connecting the front portion (107, 307, 407) of one of the teeth to the back portion (109, 309, 409) of a preceding tooth; wherein the front portion (107,307,407) comprises at least two undercut segments (120, 130; 320, 330; 420, 430) including a first undercut segment (120, 320, 420) and a second undercut segment (130, 330, 430); wherein the second undercut segment (130, 330, 430) is spaced further away from the tip of the tooth (111, 311, 411) than the first undercut segment (120, 320,420); wherein each undercut segment (120, 130; 320, 330; 420, 430) has an undercut angle (, ); wherein the undercut angle (, ) is the minimum of the angles with a longitudinal direction of the card wire of the tangents to each point of the undercut segment goingwhen observed from the tipinwards from the front portion (107, 307, 407); wherein the second undercut segment (130, 330, 430) has a larger undercut angle () than the first undercut segment ().

2. The card wire (100, 300, 400) of claim 1, wherein the difference between the undercut angle () of the second undercut segment (130, 330, 430) and the undercut angle () of the first undercut segment (120, 320, 420) is at least 8 degrees.

3. The card wire (100, 300, 400) of claim 1, wherein the first undercut segment (120, 320, 420) starts at a distance (A)measured perpendicularly to the longitudinal direction of the card wirefrom the tip of the tooth (111,311,411), of at least 0.15 mm.

4. The card wire (100, 300, 400) of claim 1, wherein the undercut angle () of the first undercut segment (120, 320, 420) is between 0 and 38 degrees.

5. The card wire (100, 300, 400) of claim 1, wherein the undercut angle () of the second undercut segment (130, 330, 430) is between 20 and 50 degrees.

6. The card wire (100) of claim 1, further comprising a third undercut segment (140) positioned further away from the tip of the tooth than the second undercut segment (130); and wherein the third undercut segment (140) has an undercut angle (y) which is larger than the undercut angle () of the second undercut segment (130).

7. The card wire (100) of claim 6, wherein the undercut angle (y) of the third undercut segment (140) is at least 8 degrees larger than the undercut angle () of the second undercut segment (130).

8. The card wire (100) of claim 6, wherein the undercut angle (y) of the third undercut segment (140) is between 30 and 50 degrees.

9. The card wire (100, 400) of claim 1, further comprising a linear part (161) in the front portion (107, 407) between the tip and the first undercut segment (120, 420).

10. The card wire (100, 400) of claim 9, wherein the linear part (161) of the front portion (107, 407) has an angle () with the rib portion (103, 403) of the card wire between 20 and 65 degrees.

11. The card wire of claim 1, wherein at least one of the first undercut segment, or the second undercut segment comprise in a portion of the undercut segment goingwhen observed from the tipinwards from the front portion a part that is substantially linear.

12. The card wire of claim 1, wherein at least one of the first undercut segment or the second undercut segment have a triangular shape or a scallop shape.

13. An apparatus comprising; a condenser roller (530, 540); wherein the condenser roller (530, 540) is covered with a card wire (100, 300, 400) as in claim 1; wherein the condenser roller (530, 540) is arranged to rotate in a direction opposite to a direction of orientation of the front portion (107, 307, 407) of the teeth of the card wire on the condenser roller.

14. The apparatus of claim 13, comprising a further roller having a surface (520) covered with a card wire; wherein the further roller is arranged to rotate so that the surface of the further roller closest to the surface of the condenser roller and the surface of the condenser roller closest to the surface of the further roller rotate in the same tangential direction; and wherein the condenser roller (530) is arranged to receive a web of fibers from the further roller (520).

15. The apparatus of claim 14, wherein the condenser roller (530) is configured to rotate at a lower surface speed than the further roller (520); and wherein the condenser roller (530) is configured to receive a full web of fibers present on the further roller (520).

16. A method of operating an apparatus comprising a condenser roller covered with a card wire comprising a rib portion and a plurality of teeth along a length of the rib portion, wherein the plurality of teeth are inclined at an angle with respect to the rib portion, wherein the teeth have a front portion and a back portion, wherein the front portion is an inner portion of the tooth leaning towards the rib portion and the back portion is an outer portion of the tooth, wherein the front portion and the back portion of the tooth join at a tip of the tooth, wherein the teeth have a base segment connecting the front portion of one of the teeth to the back portion of a preceding tooth, wherein the front portion comprises at least two undercut segments including a first undercut segment and a second undercut segment spaced further away from the tip of the tooth than the first undercut segment, wherein each undercut segment has an undercut angle (, ), wherein the undercut angle (, ) is the minimum of the angles with a longitudinal direction of the card wire of the tangents to each point of the undercut segment goingwhen observed from the tipinwards from the front portion, wherein the second undercut segment has a larger undercut angle () than the first undercut segment (), wherein the condenser roller is arranged to rotate in a direction opposite to a direction of orientation of the front portion of the teeth of the card wire on the condenser roller, the method comprising: rotating the condenser roller (530) at a lower surface speed than a further roller (520); and receiving by the condenser roller (530) a full web of fibers present on the further roller (520).

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a card wire according to the invention.

(2) FIG. 2 shows a detail of the card wire of FIG. 1.

(3) FIG. 3 shows another card wire according to the invention.

(4) FIG. 4 shows a card wire according to the invention with two undercuts.

(5) FIG. 5 shows an apparatus comprising rollers covered with card wire according to the invention.

DETAILED DESCRIPTION

(6) FIG. 1 shows a card wire 100 according to the invention. The card wire 100 comprises a rib portion 103 and a plurality of teeth 105 along the length of the rib portion 103. The plurality of teeth 105 are inclined at an angle with respect to the rib portion 103. The teeth have a front portion 107 and a back portion 109. The front portion 107 is the inner portion of the tooth 105 leaning towards the rib portion 103. The back portion 109 is the outer portion of the tooth. The front portion 107 and the back portion 109 of the tooth join at the tip 111 of the tooth. The base segment 113 connects the front portion to the back portion 109 of the preceding tooth. FIG. 1 shows a card wire 100 where the teeth 105 have a front portion 107 comprising three undercut segments. A first undercut segment 120, a second undercut segment 130 and a third undercut segment 140. The undercut segments 120, 130, 140 have a triangular shape with rounded tips of the triangle. Each undercut segment 120, 130, 140 has an undercut angle. The undercut angle is the minimum of the angles with the longitudinal direction of the card wire, of the tangents to each point of the part of the undercut segment goingwhen observed from the tipinwards from the front portion. The first (120), second (130) and third (140) undercut segment respectively have undercut angles , and . As an example, is 15 degrees, is 27 degrees and is 40 degrees. In another example is 15 degrees, is 20 degrees and is 40 degrees. In another example is 15 degrees, is 35 degrees and is 50 degrees. In another example is 15 degrees, is 35 degrees and is 45 degrees.

(7) In another example is 0 degrees, is 12 degrees and is 35 degrees. In another example is 8 degrees, is 20 degrees and is 45 degrees. In another example is 35 degrees, is 43 degrees and is 50 degrees.

(8) In another example, the card wire has a first undercut segment with an undercut angle 20 degrees and a second undercut segment with undercut segment 35 degrees.

(9) In the example of FIG. 1, the first undercut segment starts at a distance Ameasured perpendicularly to the longitudinal direction of the card wirefrom the tip of the tooth of 0.6 mm.

(10) The exemplary card wire 100 shown in FIG. 1 comprises between the tip 111 and the first undercut segment 120 a linear part 161 in the front portion 107. The linear part 161 has a smallest angle with the rib portion 103 of 60 degrees. In other examples, the linear part 161 has a smallest angle with the rib portion 103 of e.g. 55 or 50 degrees.

(11) The first (120), second (130) and third (140) undercut comprise in the part of the undercut segment goingwhen observed from the tipinwards from the front portion a part that is substantially linear. This is illustrated for the first undercut segment 120 in FIG. 2 which is showing a detail of the card wire 100 of FIG. 1. Same reference numerals of FIGS. 1 and 2 have the same meaning. The linear part B preferably has a length between 0.4 mm and 1 mm, e.g. 0.8 mm.

(12) FIG. 3 shows a card wire 300 according to the invention of which the two undercut segments 320 and 330 have a scallop shape. The card wire 300 comprises a rib portion 303 and a plurality of teeth 305 along the length of the rib portion 303. The plurality of teeth 305 are inclined at an angle with respect to the rib portion 303. The teeth have a front portion 307 and a back portion 309. The front portion 307 is the inner portion of the tooth 305 leaning towards the rib portion 303. The back portion 309 is the outer portion of the tooth. The front portion 307 and the back portion 309 of the tooth join at the tip 311 of the tooth. The base segment 313 connects the front portion to the back portion of the preceding tooth.

(13) As an example the undercut angles are equal to 15 degrees and equal to 28 degrees.

(14) The front portion 307 comprises between the tip 311 and the first undercut segment 320 two linear portions 363, 365. The linear portion 363 closest to the tip has an angle e.g. 22 degrees and the second linear portion 365 has an angle e.g. 60 degrees with the longitudinal direction of the card wire.

(15) In a preferred embodiment, the card wire of the invention has two undercuts, more preferably exactly two undercuts. FIG. 4 shows a card wire 400 according to the invention that has two undercuts. The card wire 400 comprises a rib portion 403 and a plurality of teeth 405 along the length of the rib portion 403. The plurality of teeth 405 are inclined at an angle with respect to the rib portion 403. The teeth have a front portion 407 and a back portion 409. The front portion 407 is the inner portion of the tooth 405 leaning towards the rib portion 403. The back portion 409 is the outer portion of the tooth. The front portion 407 and the back portion 409 of the tooth join at the tip 411 of the tooth. The base segment 413 connects the front portion to the back portion 409 of the preceding tooth. The wire 400 has a first undercut segment 420 and a second undercut segment 430. Each undercut segment 420 and 430 has an undercut angle. The first (420) and second (430) undercut segment respectively have undercut angles and . As an example, is 35 degrees and is 40 degrees. In another example is 35 degrees and is 43 degrees.

(16) FIG. 5 shows an apparatus 500 comprising a cylinder roller 510, a doffer roller 520 and two condenser rollers 530, 540 and a take-off roller 550. The apparatus 500 can be a part of a nonwoven card. The cylinder roller 510, the doffer roller 520 and the two condenser rollers 530, 540 and the take-off roller 550 are covered with card wire, respectively 512, 522, 532, 542 and 552. The first condenser roller 530 and/or the second condenser roller 540 can be covered with card wire according to invention, e.g. the card wires shown in FIG. 1, 3 or 4. In operation, the direction of rotation of the rollers is indicated by the arrows. The cylinder roller 510 carries a fiber web 514. At the intersection between the cylinder roller 510 and the doffer roller 520, part of the fiber web 514 is transferred from the card wire 512 of the cylinder roller 510 onto the card wire 522 of the doffer roller 520. The transferred fiber web is indicated by 526. However, the fiber web 514 is not completely transferred, a part of the fiber web 514, indicated with 515, is recycling on the cylinder roller 510.

(17) The first condenser roller 530 rotates at a lower surface speed, e.g. 20% lower, than the doffer roller 520. The condenser roller 530 rotates in the direction opposite to the orientation of the front portion of the teeth of the card wire on the roller (the same applies for the direction of rotation of the doffer roller 520 and of the second condenser roller 540). The fiber web 526 is completely transferred from the doffer roller 520 to the first condenser roller 530, where it is carried by the teeth of its card wire 532 and where the fiber web is indicated with reference numeral 536. The second condenser roller 540 rotates at a lower surface speed, e.g. 20% lower, than the first condenser roller 530. The fiber web 536 is completely transferred from the first condenser roller 530 to the second condenser roller 540, where it is carried by the teeth of its card wire 542 and where the fiber web is indicated with reference numeral 536.

(18) A take-off roller 550 covered with card wire 552 takes the web 546 off the second condenser roller 540 and transports the web 556 further.

(19) By the action of the condenser rollers 530 and 540, the web is condensed, making it denser and reorienting the fibers.

(20) The use of the card wire of the invention on the first and/or on the second condenser rollers eliminates the irregular bubbling or undulating appearance of the web in the intersection between the previous roller and the roller covered with card wire of the invention, without fiber loading occurring on the roller covered with the card wire of the invention.