FR2810682A1 - METHOD FOR MANUFACTURING MESH IN A NON-WOVEN FIBER TABLECLOTH, AND NEEDLES FOR IMPLEMENTING SAID METHOD - Google Patents

Abstract

The invention relates to a method of making stitches (1) in a web of non-woven fibers (2) with needles (4) with a free opening hook (7) comprising: a movement in which the needles (4) to hook (7) are extracted from the web of fibers (2), each needle (4) returning a first group (30) of fibers, a movement in which the needles (4) with hook (7) enter the web of fibers (2), each first group (30) forming a loop (32) around the needle (4) with hook (7), a movement in which the needles (4) are extracted from the web of fibers (2), each needle (7) bringing a second group (33) of fibers through the loop (32) formed by the first group (30), the repetition of the movements (c), (d), (e), the second group ( 33) becoming a first group (30), according to the invention part of the needles (4) with hook (7) comprises at least two open hooks (7) and, each group of fibers (30, 33) raised is constituted by sub-g roups (31, 34) of fibers, each sub-group (31, 34) of fibers being raised by one of the hooks (7) of the associated needle (4).

Description

method of manufacturing meshes in a non-woven fiber web

  The invention relates to a method of manufacturing stitches in a web of non-woven fibers, and needles to implement said method. More particularly, the invention relates to a method of manufacturing stitches in a web of nonwoven fibers with hook needles with free opening, and hook needles with free opening for

implement said method.

  Methods are known for manufacturing stitches in a sheet of nonwoven fibers with hook needles with free opening. US3646781 describes a manufacturing method of this type comprising: (a) a forward movement in which the hook needles penetrate the sheet of nonwoven fibers, (b) a back movement in which the hook needles are extracted from the sheet of fiber, each needle bringing a first group of fibers associated (c) a transverse movement of the nonwoven web with respect to the movements of the needles, defining the length of the stitches produced (d) a second forward movement in which the hook needles penetrate the nonwoven fiber web, each first group of fibers forming a loop around the associated hook needle, (e) a second return movement in which the needles are extracted from the fiber web, each needle bringing back a second group of fibers through the loop formed by the first set of associated fibers (f) the repetition of movements (c), (d), (e), the second group of fibers

  becoming a first group of fibers for the next stitch.

  The method of US3646781 aims to join together several layers of nonwoven fibers. The groups of fibers belong to a first layer, and the mesh is produced on another layer using the groups of fibers of the first layer. The needles used are needles each comprising an open hook which, in the return movements, captures a group of fibers. The mesh resulting from US3646781 does not have the regularity and the esthetics desired in certain applications of nonwoven mesh. This is mainly due to the lack of control over the quantity of fibers in the group of fibers contained in the hook. Indeed, to have a resistant mesh, the hook is dimensioned to bring back a significant quantity of fibers. This important dimension of the hook implies that during certain of the return movements the hook hooks part of the fibers of the group of fibers of the mesh in formation. This results in damaged meshes not allowing the regularity and the desired esthetics in certain applications of non-woven mesh. The aim of the present invention is to propose a method of the type US 3646781 in which the regularity, and the aesthetics of the mesh are

  significantly improved compared to the mesh resulting from US3646781.

  To this end, the invention relates to a method of manufacturing stitches in a sheet of nonwoven fibers with hook needles with free opening comprising: (a) a forward movement in which the hook needles penetrate into the sheet of non-woven fibers -woven, (b) a backward movement in which the hook needles are extracted from the sheet of fibers, each needle bringing back a first group of fibers associated (c) a transverse movement of the sheet of nonwoven fibers with respect to the movements needles, defining the length of the fabric stitches (d) a second forward movement in which the hook needles penetrate the sheet of nonwoven fibers, each first group of fibers forming a loop around the associated hook needle, ( e) a second return movement in which the needles are extracted from the fiber web, each needle bringing a second group of fibers through the loop formed by the first g group of fibers associated (f) repetition of movements (c), (d), (e), the second group of fibers

  becoming a first group of fibers for the next stitch.

  According to the invention at least part of the hook needles comprises at least two open hooks superposed longitudinally, and each group of fibers wound up is constituted by sub-groups of fibers, each

  fiber subgroup being wound up by one of the hooks of the associated needle.

  Thus, for a constant number of fibers in a group, the multi-hook needle method according to the present invention makes it possible to substantially reduce the depth of each of the hooks and therefore to reduce the

  risk of catching a hook in the mesh during manufacture.

  Advantageously, each hook of a multi-hook needle is calibrated to statistically contain a countable and predetermined quantity of fibers of the nonwoven web, depending on the predetermined average diameter of the fibers of the nonwoven web. The invention also relates to a needle hook to make

  mesh in a nonwoven fiber web according to the method described above.

  Each hook has a depth of between 1 and 6 times the

  predetermined average diameter of the fibers of the nonwoven web.

  Each hook has a total height of between 1 and 8 times the

  predetermined average diameter of the fibers of the nonwoven web.

  Each hook has a return of between 0 and 2 times the diameter

  predetermined means of the fibers of the nonwoven web.

  The hook needle includes between 2 and 10 hooks.

  The hooks are arranged on a length of the needle less than

0.5 mm.

  Other advantages and characteristics of the present invention

  will result from the description which follows with reference to the accompanying drawings

  in which: Figure I is a schematic representation of the hook area

  of a needle according to the present invention.

  Figures 2A to 2D are schematic representations of the steps

  of a method according to the present invention.

  Figure 3 is a schematic view of a piece of nonwoven web

  meshed according to the present invention.

  The invention relates to a method for manufacturing meshes 1 in

a sheet of nonwoven fibers 2.

  The sheet of non-woven fibers 2 consists of fibers. The titer of the fibers which can be used is within a range going from 0.1 tex to 2 tex. Tex is a textile unit expressed in grams per kilometer, 1

  tex is equal to 1 gram per kilometer.

  The number of fibers necessary for the production of a mesh 1 having a good aesthetic / resistance compromise is between 1 O for fibers of average diameter 45 μm and 50 fibers for fibers of diameter

medium 9 pm.

  The average fiber diameter is calculated using the titer and the

fiber density.

  The constituent materials of the fibers are for example: - cotton, density = 1500 kg / m3 - polyester, density = 1400 kg / m3 - polyamide, density = 1150 kg / m3

  - polypropylene, density = 900 kg / m3.

  The machine used to implement the method according to the invention comprises means (not shown) for transporting the sheet 2 of nonwoven fibers in a transport direction 3, and needle activation means 4 comprising a holder needle (not shown) on which is mounted at least one needle 4, and which is driven by a movement 5a, 5b substantially reciprocating in a direction 6 perpendicular to the sheet of nonwoven fibers 2 and parallel to the needle 4 between a stitched position in which the needle 4 is stitched in the fleece of nonwoven fibers 2 and a retracted position in which the needle 4 is pulled out of the fleece

  non-woven fibers 2. A plurality of needles 4 can be mounted on the holder

  needle. The needles 4 can be aligned in a plane P1 perpendicular to the sheet of nonwoven fibers 2 and to the direction of transport 3. In an alternative embodiment shown in FIG. 3, the needles 4 can be arranged in staggered rows with respect to said plane P1 perpendicular to the water table

  of non-woven fibers 2 and to the direction of transport 3.

  The needles 4 used are open hook needles 7. According to the invention, the needles 4 comprise at least two open hooks 7 superimposed longitudinally in the direction 6. the openings 8 of the hooks 7 are directed upstream of the machine. In this way, in the stitched position and in combination with the transport movement, the filling of the hooks 4 with the fibers of the nonwoven fiber web 2 is facilitated. the open hooks 7 of the needles 4 according to the invention are calibrated to statistically contain a countable and predetermined quantity of fibers of the sheet of nonwoven fibers 2, depending on the average diameter

predetermined fibers.

  The number of open hooks 7 carried by a needle 4 is included

between 2 and 10.

  An open hook 7 has a depth P of between 1 and 6 times the predetermined average diameter of the fibers of the nonwoven web 2. the predetermined average diameter of the fibers is calculated using the fiber count and

  the density of the material of the fibers.

  Each open hook 7 has a total height H of between 1 time

  and 8 times the predetermined average diameter of the fibers of the nonwoven web.

  Each hook open 7 to a return R between 0 and 2 times the

  predetermined average diameter of the fibers of the nonwoven web 2.

  The distance E between the point of the needle 9 and the first open hook 7 must be as small as possible, for example 1 mm for stamped steel needles. Similarly, the distance D between two consecutive hooks must be the

  as small as possible, for example 0.1 mm for stamped steel needles.

  Finally the zone Z in which the hooks are shaped will be of the order

5mm.

  In an illustrative example of a needle 4 according to the invention, a

  stamped steel needle 4 intended to mesh a sheet of non-polyester fibers

  woven 2 of title 2 tex comprises 10 open hooks 7 spaced from each other by 0.1 mm, each open hook 7 having a height H of four times the average diameter of the fibers. The average diameter of a 2 tex polyester fiber is about 40 µm. zone Z of the 10 hooks occupies 2.6 mm from needle 4. the

  first hook is shaped 1 mm from the tip 9 of needle 4.

  In one embodiment, the needles 4 have, in cross section, a general triangle shape. The open hooks 7 are shaped on one of the edges coming from the angles of the triangle. The needles 4 are mounted on the needle holder so that the stop comprising the open hooks 7 points upstream of the machine. The upstream of the machine is defined as the entry zone 10 of the non-meshed fiber web 2. The gauge of the needles 4 is between 1/42 for fibers of small diameter and 1/32 for fibers of large diameter. The unit of the gauge is the inch (1

inch = 2.5399 cm).

  The steps of the method according to the invention are as follows (a) a forward movement 5b in which the needles 4 with hooks 7 penetrate into the sheet 2 of nonwoven fibers until the stitched position, (b) a return movement 5a in which the needles 4 with hooks 7 are extracted from the sheet 2 of nonwoven fibers to the retracted position, each needle 4 bringing back a first group 30 of associated fibers, each first group 30 of reassembled fibers is constituted by sub- groups 31 of fibers, each sub-group 31 of fibers being reassembled by one of the hooks 7 of the needle 4

associated.

  (c) a transverse movement of the nonwoven ply 2 in the direction of transport 3, defining the length L of the stitches 1 produced (d) a second forward movement 5b in which the needles 4 with hooks 7 penetrate into the ply 2 of nonwoven fibers, up to the stitched position, each first group of fibers 30 forming a loop 32 around the needle 4 with hooks 7 associated, (e) a second return movement 5a in which the needles 4 are extracted from the sheet 2 of non-woven fibers to the retracted position, each needle 4 bringing a second group of fibers 33 through the loop 32 formed by the first group 30 of associated fibers, each second group 33 of reassembled fibers consists of under -groups 34 of fibers, each sub-group 34 of fibers being reassembled by one of the hooks 7 of the associated needle 4, (f) the repetition of the movements (c), (d), (e), the second group 33 of fibers becoming a first group 30 of fibers in. on the next stitch 1. The hooks 7 of the needles 4 have been calibrated as indicated above so that they statistically contain a countable and predetermined quantity of fibers of the sheet 2 of nonwoven fibers, depending on the

  predetermined average diameter of the fibers of the fleece of nonwoven fibers.

  Thus, while having a determined number of fibers ensuring the solidity of the mesh 1, the mesh defects are substantially limited by transporting the said number of fibers in several hooks 7. The result is a solid mesh 1 having a regularity and a reproducibility substantially improved compared

with single crochet needles.

  Of course, the present invention is not limited to the exemplary embodiments shown. Many variations are possible without them

  are outside the scope of the present invention. For example, the shape of the hooks can be different from that shown in the figures without departing from the scope of the present invention.

Claims (9)

  1. Method of manufacturing meshes (1) in a non-woven fiber web   woven (2) with hook needles (4) with free opening (7) comprising: (a) a forward movement (5b) in which the hook needles (4) penetrate the sheet of non-woven fibers ( 2) to a stitched position, (b) a backward movement (5a) in which the hook needles (4) (7) are extracted from the sheet of nonwoven fibers (2) to a retracted position, each needle (4) bringing back a first group (30) of associated fibers, (c) a transverse movement of the fleece of nonwoven fibers (2) in a direction of transport (3) of the fleece of nonwoven fibers ( 2), defining a length (L) of the knitted stitches (1) (d) a second forward movement (5b) in which the hook needles (4) (7) penetrate into the sheet of nonwoven fibers (2), up to '' in the stitched position, each first group (30) of fibers forming a loop (32) around the needle (4) with hook (7) associated, (e) a second return movement (5a) in which l the needles (4) are extracted from the sheet of nonwoven fibers (2) up to the retracted position, each needle (7) bringing a second group (33) of fibers through the loop (32) formed by the first group (30) of associated fibers, (f) repetition of the movements (c), (d), (e), the second group (33) of fibers becoming a first group (30) of fibers for the mesh (1 ) following, characterized in that at least a portion of the hook needles (4) (7) comprises at least two open hooks (7) superposed longitudinally, and in that each group of fibers (30, 33) raised is constituted by fiber sub-groups (31, 34), each fiber sub-group (31, 34) being wound up by one of the hooks (7) of the associated needle (4). 2. Manufacturing method according to claim 1 characterized in that the hooks (7) of the needles have been calibrated to statistically contain a countable and predetermined quantity of fibers of the sheet of nonwoven fibers (2), depending on a diameter predetermined means of   fibers of the nonwoven fiber web (2).   3. Crochet needle for making stitches in a sheet of nonwoven fibers (2) according to the method of either of claims 1 or 2. 4. Hook needle according to claim 3 characterized in that each hook (7) at a depth (P) between 1 and 6 times the diameter   predetermined means of the fibers of the web of nonwoven fibers.   5. hook needle according to claim 3 or 4 characterized in that each hook (7) at a total height (H) of between 1 and 8 times   the predetermined average diameter of the fibers in the non-woven fiber web woven (2).   6. hook needle according to any one of claims 3 to 5 characterized in that each hook (7) to a return (R) between 0 times and 2 times the predetermined average diameter of the fibers of the ply of non-woven fibers (2).   7. Hook needle according to any one of claims 3 to 6   characterized in that it comprises between 2 and 10 hooks (7).   8. hook needle according to any one of claims 3 to 7 characterized in that the hooks (7) are arranged on an area (Z) of   the needle (4) less than 0.5 mm.   9. hook needle according to any one of claims 3 to 6 characterized in that it has a triangular cross section, the hooks (7) being shaped in one of the edges   longitudinal from the angles of the triangle.