WO2009030551A1

WO2009030551A1 - Self-cleaning comb needle

Info

Publication number: WO2009030551A1
Application number: PCT/EP2008/059340
Authority: WO
Inventors: Lieven Vangheluwe; Hans Verbauwhede
Original assignee: Nv Bekaert Sa
Priority date: 2007-09-06
Filing date: 2008-07-17
Publication date: 2009-03-12

Abstract

A needle or a saw-toothed stamped part (10) for a comb comprises a shaft (12) and a tip (14, 16). The tip (14, 16) has an end part (14) and a middle part (16). At least the end part (14) is chamfered (15) with a working angle α smaller than 90° relative to the theoretical movement plane (13) of the material being combed. The middle part (16) has a concave curved part (17) as seen against the direction of movement of the material being combed. The chamfered end part and the concave curved part help to avoid accumulation of dirt on the needle or on the saw-toothed stamped part (10).

Description

SELF-CLEANING COMB NEEDLE

FIELD OF THE INVENTION

The present invention relates to a needle or a saw-toothed part in the field of textile manufacturing, in particular combing of fibers.

BACKGROUND OF THE INVENTION

One of the most important processes in the production of textiles is the carding and combing process, whereby dirty natural fibers (e.g. cotton or wool) 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 and/or 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. In such case where very fine yarns are desired, carding is followed by combing, 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.

In general the combing process comprises a main drum covered with saw- toothed wires or needles. Around this main drum, a number of fixed combs are installed. These fixed combs also comprise saw-toothed wires or needles which together with the main drum comb the fibers.

The geometry of the needles or saw-toothed wires and their position relative to the material being combed and to surrounding combing equipment parts is chosen dependently on their specific job in the combing process and on the material being combed. Hence, the geometry of the needles or saw-toothed wires and their position influence the accumulation of impurities, dirt or short fibers on the needles or saw teeth, which is a common problem in combing. Indeed, due to this accumulation of impurities, dirt and short fibers, frequent cleaning of the needles or saw teeth is required, typically every 8 hours, each time resulting in an interruption and increasing cost of the fiber production process. Further, the manual cleaning process includes the risk of damaging the fixed combs leading to a reduced life time of the fixed comb.

Many attempts to alleviate the above problem are described in the state of the art. For example, in EP-B1 -1 222 327, a fixed comb is described wherein the needles of the fixed comb have a working angle of more than 90° relative to the theoretical movement plane of the sliver being combed, which extends without deflection between a nipper element before the fixed comb and a pair of rollers after the fixed comb.

Another example of an attempt to alleviate the problem of dirt accumulation is described in DE-A1 -100 33 169, wherein the needle geometry shows two slanted parts with different angle relative to the theoretical movement plane of the fibers to avoid dirt accumulation.

DE 39 37 899 C1 discloses a needle or saw toothed part for a comb. The end part shows chamfered parts.

CH 679 590 A5 discloses a fixed comb element with needles. The end part of the needle shows an inclination angle with respect to the theoretical middle plane of the moving web material to be combed.

CH 693 956 A5 discloses a fixed comb for a combing machine. The end part of the needle shows two angles α and β with respect to the theoretical middle plane of the moving web material to be combed. The lower angle α is greater than 90° whereas the higher angle β is smaller than 90°. Dirt risks to be accumulated in the middle of the end part where the lines defining the angles α and β meet. Given the above, there is clearly a need for a needle or saw tooth geometry minimizing or even eliminating the common problem of accumulation of impurities, dirt and short fibers on the needles or saw teeth.

Therefore, it is an objective of the present invention to provide a needle or saw- toothed stamped part minimizing or even eliminating the problem of accumulation of impurities, dirt or short fibers on the needles or saw teeth.

It is also an objective of the present invention to provide a comb for combing using needles or saw-toothed stamped parts less or even not suffering from dirt accumulation.

It is further an objective of the present invention to enhance the combing process efficiency and decrease fiber production cost.

SUMMARY OF THE INVENTION

The present invention meets the above objectives by providing a needle or a saw-toothed stamped part for a comb. The needle or part comprises a shaft and a tip. The tip has an end part and a middle part. At least the end part is chamfered with a working angle α smaller than 90° relative to the theoretical movement plane of the material being combed. The middle part has a concave curved part as seen against the direction of movement of the material being combed. Both the champered end part and the concave curved part help to remove dirt and to avoid accumulation of dirt.

In the context of the present invention, the terms "theoretical movement plane of the material being combed" refer to the theoretical middle plane of the web material to be combed.

Further, the invention is directed to a linear comb comprising a plurality of needles or saw-toothed stamped parts in accordance with the invention. BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 is a first embodiment of a needle or a saw-toothed stamped part for a comb in accordance with the present invention.

FIG 2 is another embodiment of a needle or a saw-toothed stamped part for a comb in accordance with the present invention.

FIG 3 schematically shows how accumulation of dirt is avoided.

FIG 4, FIG 5 and FIG 6 all show other and different embodiments of a needle or saw-toothed stamped part in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

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.

Referring to FIG. 1 , as a first embodiment, the present invention provides a needle or a saw-toothed stamped part 10 for a comb. The needle or part 10 comprises a shaft 12 and a tip 14, 16.. The tip 14, 16 has an end part 14 and a middle part 16. The end part 14 is chamfered with a working angle α smaller than 90° relative to the theoretical movement plane 13 of the material being combed.

In the context of the present invention, the tip 14, 16 of the needle or saw- toothed stamped part 10 intrudes into the material to be combed and actually combs the material, while the shaft 12 is used to fix the needle or saw-toothed stamped part in a comb (not shown). By making the tip 14, 16 of the needle or saw-toothed stamped part 10 at its end part 14 chamfered with a working angle α smaller than 90° relative to the theoretical movement plane of the material being combed, impurities, dirt, and short fibers are forced towards the end of the tip by the movement of the material being combed, thereby minimizing or even avoiding accumulation on the needles or saw-toothed stamped parts. Hence, the impurities, dirt, and short fibers are forced towards the co-operating circular comb of the combing machine, which is automatically cleaned usually every rotation. By minimizing accumulation on the needles or saw-toothed stamped parts, the fiber production process does not have to be interrupted frequently anymore, thereby decreasing fiber production cost.

The working angle α may be between about 85° and about 45°, preferably about 60°.

In an embodiment according to the present invention, the end part 14 of the tip may be chamfered according to a straight line 15 as illustrated in FIG 1.

In another embodiment according to the present invention and as illustrated in FIG 2, the end part 22 of the tip may be chamfered according to a concave curve 24 against the direction of movement 28 of the material being combed. The angle α is formed by a straight line 26 tangent to the concave curve 24.

Referring to both FIG 1 and FIG 2, a needle or a saw-toothed stamped part 10, 20 for a comb has a middle part 16, 27 with concave curved part 17, 29 as seen against the direction of movement 28 of the material being combed. Preferably, the concave curved cut 17, 29 may correspond to a circular segment. The concave curve against the direction of movement of the material being combed provides a way for remaining dirt of short fibers, which can not be forced towards the end of the tip by the movement of the material being combed, to evacuate from the tip's end part.

In a preferred embodiment in accordance with the present invention and referring again to FIG 1 , the chamfered end part 15 meets the concave curved part 17 in a lower boundary point or line 18. The concave curved part 17 meets the shaft 12 in a higher boundary point or line 19. The lower boundary point or line 17 is shifted over a distance x in the direction of movement with respect to the higher boundary point or line 19 in order to avoid dirt accumulation. By extending the curve at one side to create a shift x between both boundary points 18, 19, the impurities, dirt and short fibers may have a longer evacuation path, such that the dirt and impurities are pushed upwards first. The impurities will then fall down via the space created by the shift x onto the circular comb. The latter is normally automatically cleaned.

Referring to FIG 1 , suitable dimensions of a self-cleaning comb geometry according to the invention are:

A: 0.5 mm - 3 mm, preferably 1.3 mm

B: 3 mm - 8 mm; preferably 5 mm C: 0.5 mm - 3 mm; preferably 1.5 mm

R: 2 mm - 6 mm; preferably 3.5 mm x: 0.1 mm - 2 mm; preferably 0.5 mm.

FIG 3 illustrates how any dirt 30 is split into a lower part 32 which is guided away by the chamfered end 33 and a higher part 34 which is guided away by the concave cut part 35 until its end. There it falls down and, thanks to the shift x, is not hindered in its falling down.

FIG 4 shows an embodiment of a saw-toothed stamped wire part or needle 40 with a bigger shaft 42.

FIG 5 shows an embodiment of a saw-toothed stamped wire part or needle 50 which an inclined shaft 52.

FIG 6 shows an embodiment of a saw-toothed stamped wire part or needle 60 with an even bigger and tapering shaft 62 .

The needle or saw-toothed stamped part may be of steel, preferably steel having the following composition: - 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 sulfur and phosphorous are preferably kept as low as possible, e.g. both below 0.05 %, e.g. below 0.025 %.

A saw-toothed stamped wire part in accordance with the invention may be manufactured as described below:

A wire rod with the above-mentioned steel composition is cold and dry drawn until an intermediate diameter ranging from 2.0 mm to 4.0 mm. The round wires are rolled or drawn until the desired non-round profile is reached. Rolling can be carried out by means of Turks heads or by means of rolls. The drawing here is a profile drawing by means of profile drawing dies. After this profiling, the saw 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 application. In case of a needle, the final geometry of the needle is obtained by means of a laser operation, a cutting operation or a punching operation. Thereafter the formed saw toothed wire or needle is subjected to some heat treatments which aim at stress-relieving the foot of the saw toothed wire and at hardening the teeth. Therefore, the entire saw toothed wire is heated until a temperature in the neighborhood of 600 ⁰C and the teeth get an additional heating until they reach a temperature of about 900 ⁰C. 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 ⁰C can be done by means of induction heating or by means of a gas burner. The heating of the teeth until 900 ⁰C 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.

The needles or saw-toothed stamped parts may receive a finishing and/or coating treatment in order to provide a smooth surface and/or a surface on which impurities have less tendency to stick onto.

In a preferred embodiment of the present invention, a linear comb is provided comprising a plurality of needles or saw-toothed stamped parts having a shaft and a tip, wherein the chamfered end part meets the concave curved cut of the middle part in a boundary point or line, said boundary point or line being shifted over a distance x with respect to the front part of the shaft.

Claims

CLAIMS:

1 . A needle or a saw-toothed stamped part (10) for a comb, said needle or part comprising a shaft (12) and a tip (14, 16), the tip (14, 16) having an end part (14) and a middle part (16), at least said end part (14) being chamfered (15) with a working angle α smaller than 90° relative to the theoretical movement plane (13) of the material being combed, characterized in that said middle part (16) has a concave curved part (17) as seen against the direction of movement of the material being combed.

2. A needle or a saw-toothed part (10) for a comb according to claim 1 , wherein said working angle α is between about 85° and about 45°, preferably about 60°.

3. A needle or a saw-toothed part (10) for a comb according to claim 1 or 2, wherein said end part (14) is chamfered according to a straight line (15).

4. A needle or a saw-toothed part (20) for a comb according to claim 1 or 2, wherein said end part (22) is chamfered according to a concave curve (24) against the direction of movement (28) of the material being combed.

5. A needle or a saw-toothed part (10) for a comb according to one of the preceding claims, wherein said concave curved part (17) corresponds to a circular segment.

6. A needle or a saw-toothed part (10) for a comb according to one of the preceding claims, wherein said chamfered end part (14, 15) meets said concave curved part (17) in a lower boundary point or line (17) and wherein said concave curved part (17) meets said shaft (12) in higher boundary point or line (19), said lower boundary point or line (17) being shifted over a distance x in the direction of movement with respect to said higher boundary point or line (19) in order to avoid dirt accumulation.

7. A linear comb comprising a plurality of needles or saw-toothed stamped parts according to any of the above claims.