A CURVED COMB SEGMENT

Description

Technical Field

[0001] The present invention relates to the field of textile manufacturing, in particular to combing of fibers.

Background Art

[0002] Important processes in the production of textiles are the carding and combing processes, whereby dirty natural fibers are refined to a coherent, smooth web that is suitable for spinning. When preparing fibers for spinning it is necessary to arrange the fibers in a uniform state in terms of density and thickness and remove impurities, and this is achieved by a carding process, which is possibly followed by a combing process. Carding produces a thin fiber sheet of uniform thickness, the sheet being subsequently condensed to form a thick, continuous, untwisted strand called sliver.

[0003] In a case where very fine yarns are desired, carding is followed by combing, which is a process that removes short fibers, leaving a sliver composed entirely of long fibers, all laid parallel and smoother and more lustrous than uncombed types. Carded and combed sliver is then spun.

[0004] In general the carding process comprises a main drum covered with toothed wire or needles. Around this main drum, a number of fixed flats are installed. These fixed flats also comprise toothed wire or needles which interact with the main drum. In the carding process these two surfaces, the main drum and the fixed flats are in movement and there is a continuous exchange of fibers from and to the drum and from and to the fixed flats.

[0005] The carding process may be followed by a combing process. In the combing process a circular comb interacts with a fixed flat comb. The circular comb usually comprises at least one comb segment upon which teeth are provided for combing the fibers. The fixed flat comb holds a bundle of fibers and the circular comb is rotated so that its teeth penetrate through the bundle of fibers in order to remove all loose fibers. In contrast with the carding process where both the drum and the fixed flats are in movement, only the circular comb is in movement.

[0006] Positioning teeth on a comb or on a comb segment can be done in several ways. [0007] A possible positioning of the teeth is described in EP-A1 -1533404, wherein the teeth are positioned along a straight line which is slanted with respect to the comb's processing direction.

[0008] The above cited teeth positioning, while being efficient, could be improved in its effectiveness since, upon combing fibers, in parallel with the comb's processing direction so-called gutters are created between the teeth, wherein fibers sticking together could not be individualized, and short fibers or dirt are accumulated. This results in a bad and ineffective combing operation.

Disclosure of Invention

[0009] Given the above, it is now an objective of the present invention to provide for an improved comb segment and an improved method for manufacturing such, in order to render the combing process more effective.

[0010] In particular, it is an objective of the present invention to provide a comb segment avoiding gutter formation, resulting in individualized fibers relieved from dirt and short fibers.

[0011] The present invention meets the above objectives by providing a comb segment comprising a plurality of teeth formed on a surface of the segment. These teeth are arranged along at least one virtual line curved within said surface and extending in the comb segment's processing direction.

[0012] By positioning the teeth along a virtual line curved within the comb segment's surface and extending in the comb segment's processing direction, gutter generation is minimized.

[0013] In particular, the comb segment may be a curved wire piece having teeth.

[0014] The present invention is further directed to a comb device comprising at least one comb segment in accordance with the invention.

[0015] Further, the present invention is directed to a method of fabricating comb segments comprising the steps of: i) providing a wire having teeth, and ii) punching the wire into wire pieces, followed by a step iii) to curve the wire pieces.

Preferably, the curving may take place during the punching step. [0016] During punching, the wire pieces are plastically deformed to form the curving.

Brief Description of Figures in the Drawings

[0017] FIGURES 1a, 1b, 1c all show a comb segment in accordance with the invention. [0018] FIGURES 2a, 2b, 2c and 2d all show other embodiments of a comb segment in accordance with the invention. [0019] FIGURE 3 shows a perspective view of a comb segment in accordance with the invention. [0020] FIGURES 4a and 4b show comb devices in accordance with the invention.

[0021] FIGURES 5a and 5b show perspective views of a comb device according to the invention. [0022] FIGURE 6 shows a preferred embodiment in accordance with the invention. [0023] FIGURE 7 illustrates the basic working of a comb process.

Mode(s) for Carrying Out the Invention

[0024] A person skilled in the art will understand that the embodiments described below are merely illustrative in accordance with the present invention and not limiting the intended scope of the invention. Other embodiments may also be considered.

[0025] As a first object, the present invention provides a comb segment comprising a plurality of teeth formed on a surface of the segment. The teeth are arranged along at least one virtual line curved within this surface and extending in the comb segment's processing direction. By positioning the plurality of teeth along at least one virtual line curved within the comb segment's surface and extending in the comb segment's processing direction, gutter generation is avoided or at least minimized. Indeed, upon combing, each tooth along such virtual line interacts with the fibers at a different location with respect to the interaction location of the other teeth arranged along the virtual line. Consequently, each tooth along such virtual line separates fibers which have not been separated yet by the other teeth. This results in better individualized fibers and better removal of dirt and short fibers.

[0026] FIGURES 1a, 1b and 1c all show comb segments 10 with different virtual lines. As shown in FIGURES 1a, 1 b and 1c, the curves 12, 14, 16 of the at least one virtual line along which the plurality of teeth is arranged may have at least one radius.

[0027] In a preferred embodiment, the curve of the virtual line along which the plurality of teeth is arranged may have one radius. In such case, the curve 14 is a circular segment such as shown in FIGURE 1 b.

[0028] Optionally, the virtual line 16 may comprise a plurality of circular segments in prolongation to each other, such as shown in FIGURE 1c.

[0029] In another embodiment, the curve 10 may have a plurality of radii. In such case the curve may comprise at least one oval segment (FIGURE 1a), or at least two circular segments with different radius, or any combination of oval and circular segments.

[0030] Referring to FIGURES 2a, 2b, 2c and 2d, in an embodiment of the invention, the comb or carding segment 20 may comprise a plurality of toothed wire pieces 22, 24, 26, 28 formed on a surface of the segment 20. These toothed wire pieces 22, 24, 26, 28 are arranged along a plurality of virtual lines curved within said surface and extending in the comb segment's processing direction which is referred to by arrow 29. Preferably, the virtual lines may be extending parallel to each other, as illustrated in FIGURES 2a, 2b, 2c and 2d.

[0031] In accordance with the present invention and as shown in FIGURE 3, the comb segment may be a curved wire piece 30 having teeth 32. Such wire piece 30 may have an appropriate cross-section which, depending on the application, may be square, rectangular, or take an L-form. The basis leg of the L may form a heel or foot 34 and the top leg of the L may house the teeth 32. In accordance with the present invention, the profile may be curved such that the teeth are arranged along a curved virtual line extending in the comb or carding segment's processing direction 36.

[0032] Referring to FIGURES 4a and 4b, the present invention provides a comb device 40 as a second object. This comb device comprises at least one comb segment 42, 44 in accordance with the first object of the invention.

[0033] The comb device 40 may comprise one comb having a plurality of toothed wire pieces arranged along a plurality of curved virtual lines. Further in accordance with the invention, the comb or carding device

[0034] may comprise a plurality of comb segments 44, each having a plurality of toothed wire pieces 46 arranged along at least one curved virtual line (FIGURE 4a) or along a plurality of parallel curved virtual lines 48 (FIGURE 4b).

[0035] Referring to FIGURES 5a and 5b, preferably, the comb device 50 may comprise a plurality of curved wire pieces 52 having teeth 54.

[0036] Turning now to FIGURE 6a, in a preferred embodiment of the present invention, the comb device has at least one virtual line may take the form of a circular segment with a radius chosen such that the height H of the circular segment is equal or greater than the pitch formed by subsequent comb segments 62.

In case the comb segment is a curved wire piece having teeth 64, the radius of the circle may be chosen such that the height H of the circular segment is equal or greater then the pitch formed by subsequent curved wire pieces.

[0037] Alternatively or in addition and as illustrated in FIG 6b, the radius of the circle may be chosen such that the height of the circular segment H is equal to or greater than the thickness B of the wire heel or foot 66. It is hereby understood that the wire heel or foot is thicker than the teeth on top of the wire.

[0038] These mentioned minimum values are required to avoid the above- mentioned gutter formation.

[0039] Referring to FIG 7, which illustrates a combing apparatus, the combing is done along following lines. A carded bundle of fibers 72 is fed by means of a feeding cylinder 74 stepwise, i.e. length by length. Each length is hold fixedly clamped, amongst others by fixed comb 75, to allow the circular comb 76 to go several times through the bundle 72 during rotation of comb

body 78 in order to remove as much as possible all loose fibers. The combed bundle of fibers is led further by means of cylinder 80.

[0040] As a third object, the present invention provides a method of fabricating comb segments comprising the steps of: i) providing a wire having teeth, and ii) punching the wire into wire pieces having teeth, whereby a step is provided iii) to curve the wire pieces. [0041] Preferably the wire pieces are curved while punching. During punching, the wire pieces are plastically deformed to form the curving. [0042] A wire having teeth may be made as follows. Starting product is a wire rod (usual diameters are 5.5 mm or 6.5 mm) with a steel composition along the following lines:

- a carbon content ranging from 0.30 % to 2.0 %, e.g. from 0.5 to 1.2 %; e.g. from 0.6 to 1.1 %;

- a silicon content ranging from 0.10 % to 2.5 %, e.g. from 0.15 to 1.60 %;

- a manganese content ranging from 0.10 % to 2.0 %, e.g. from 0.50 to 0.90 %;

- a chromium content ranging from 0.0 % to 2.0 %, e.g. from 0.10 % to 1.50 %; e.g. from 0.10 % to 0.90 %;

- a vanadium content ranging from 0.0 % to 2.0 %, e.g. from 0.05 % to 0.60 %, e.g. from 0.10 % to 0.50 %;

- a tungsten content ranging from 0.0 % to 1.5 %, e.g. from 0.1 % to 0.70 %.

In some compositions either chromium or vanadium is present. In some other compositions both chromium and vanadium are present. The amounts of sulphur and phosphorous are preferably kept as low as possible, e.g. both below 0.05 %, e.g. below 0.025 %.

[0043] The wire rod is cold and dry drawn until the desired non-round profile is reached.

Rolling can be carried out by means of Turks-heads or by means of rolls. Drawing can be done by means of profile drawing dies. The profile

depends upon the precise application can be square, rectangular, or take an L-form. The basis leg of the L forms the foot and the top leg of the L will house the eventual teeth. After this profiling, the teeth are formed in the profile wire by means of a laser operation, a cutting operation or a punching operation. The teeth may take various forms and have varying pitches, depending upon the precise application. The forming of the teeth may be followed by a deburring operation. Thereafter the formed saw toothed wire is subjected to some heat treatments, which aim at stress-relieving the foot of the toothed wire and at hardening the teeth.

Therefore, the entire toothed wire is heated until a temperature in the neighbourhood of 600 ⁰ C and the teeth get an additional heating until they reach a temperature of about 900 °C. Thereafter the entire wire is quenched so that the foot is stress relieved and the teeth are hardened since the teeth are subjected to a much greater jump in temperature. The global heating until 600 °C can be done by means of induction heating or by means of a gas burner. The heating of the teeth until 900 °C can be done by means of an additional gas burner, or by passing the teeth through a plasma arc or torch. The quenching operation can be done in an oil bath or in a bath of polymers. More information about the manufacturing of toothed steel wires can be found in WO-A- 2006/128745. The step of punching the wire into wire pieces may be performed with a punching stamp conceived such that the wire pieces are curved.