Process

Abstract

A process for the handling of a tow of fibers during manufacture and subsequent processing prior to splicing is described. The process includes the step of applying a clip to the free end of the tow, prior to transport of the tow. The fiber is preferably a carbon fiber precursor, and the clip is preferably removed and the tow spliced prior to the steps of oxidation and carbonization to form the carbon fiber.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an improved process for the handling of fibres during manufacture and subsequent processing and to an improved clip, which clip is particularly suitable for use in the improved process.

[0002] It is known in the manufacture of fibres for the manufacturer of the fibres to supply fibres for further processing to their customers in cans or cartons. When the carton or can is full of fibre, the tow or bundle of fibres is cut and the ends are tied in a knot to stop the tow fraying. In use and before further processing, it is generally necessary for the customer to splice the new tow of fibre to a tow currently in use. Because of the knotting of the end of the new tow, the customers have to discard the first 2 to 3 meters of fibre before they have a section suitable for splicing. The discarding of a length of tow each time a new tow is used is clearly undesirable.

[0003] It is a particular requirement in the manufacture and subsequent processing of acrylic fibre that the tow of fibres is presented in a form having a rectangular cross-section. The processing of acrylic fibre includes the steps of oxidation and carbonisation, during which process steps the tow is processed at high temperature in a furnace. If the tow frays or does not have a regular rectangular cross-section then any fibres or fibre ends which protrude from the surface of the tow are burnt off in the furnace and the fibre tow is damaged. In the conventional process described above, in which the end of the tow is knotted, it is particularly important to cut off and discard a sufficient length of fibre so that the cut end presents a rectangular cross-section.

[0004] It is also known to provide clips for, in particular, the temporary sealing or closing of flexible containers, for example storage bags used in domestic freezers. These clips comprise two substantially straight portions joined at one end by a simple hinge. The free ends of the two substantially straight portions together form a simple hook and clasp mechanism. The two substantially straight portions are profiled in cross-section to provide an array of engaging grooves and ribs which co-operate on closing of the clip over the opening of a flexible container to substantially seal the container and retain any contents therein. Known clips are generally made of plastics material and vary in cross section and length, depending on the size of container with which they are intended to be used.

[0005] It is an object of the present invention to provide a novel process for the handling of fibres during manufacture and subsequent processing in which the above disadvantages are reduced or substantially obviated.

[0006] It is a further object of the present invention to provide a novel means for preventing fraying of the end of a tow of fibres in which the above disadvantages are reduced or substantially obviated.

BRIEF SUMMARY OF THE INVENTION

[0007] The present invention provides a process for the handling of a tow of fibres during manufacture and subsequent processing prior to splicing characterised in that said process includes the step of applying a clip to the free end of said tow, prior to transport of said tow. In a preferred embodiment of the process according to the invention, two clips are applied to the end of said tow, the first close to said free end of said tow and the second spaced along the length of said tow, preferably between 20 and 40 cm from said first clip, more preferably approximately 30 cm from said first clip.

[0008] The process according to the invention is of particular application in the handling of carbon fibre precursors, for example acrylic fibres, prior to oxidation and carbonisation to form the carbon fibre.

[0009] The present invention further provides a clip for holding an end of a tow of fibres, which clip comprises two substantially straight portions joined at one end by a hinge, the free ends of said two substantially straight portions together forming a clasp mechanism characterised in that the inner surfaces of said two substantially straight portions are flat and smooth along at least part of the length thereof and in that spacing means are provided on said inner surface of at least one of said substantially straight portions of said clip, such that when said clip is closed, said two substantially straight portions are spaced one from the other by a predetermined amount.

[0010] In a preferred embodiment of a clip according to the invention, said inner surfaces of said two substantially straight portions are flat and smooth along at least the major part of the length thereof.

[0011] In a further preferred embodiment of a clip according to the invention, said spacing means comprise two pairs of projecting pins provided on said inner surface of one of said substantially straight portions of said clip, the first pair being arranged close to said hinge and the second pair being arranged close to said free end of said substantially straight portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] An embodiment of a clip for holding an end of a tow of fibres will now be further described with reference to the accompanying drawings, in which:

[0013] FIG. 1 is a plan view of a clip in the open position;

[0014] FIG. 2 is a side view of the clip of FIG. 1; and

[0015] FIG. 3 is a side view of the clip of FIG. 1 in the closed position;

DETAILED DESCRIPTION

[0016] A clip shown generally at 10 comprises a first substantially straight portion 2 and a second substantially straight portion 4. Portions 2 and 4 are connected by a hinge 6 which is integral with the portions 2 and 4. The portion 4 terminates at its free end in a hook portion 8. The portion 2 terminates at its free end in a clasp portion 12. The hook portion 8 is adapted to engage with the clasp portion 12 when the clip 10 is in the closed position.

[0017] A first pair of pins 14 project from the inner surface of the clip portion 2, close to the clasp portion 12. A second pair of pins 16 project from the inner surface of the clip portion 2, close to the hinge 6. The inner surface of the clip portion 2 between the first pair of pins 14 and the second pair of pins 16 is flat and smooth, as is the inner surface of the clip portion 4 between the hook portion 8 and clasp portion 12.

[0018] As can be seen from FIG. 3, when the clip is in the closed position as shown in this Figure, the inner surfaces of the clip portions 2 and 4, together with the two pairs of pins 14 and 16, together define a space 18 for receipt of the tow of fibre.

[0019] A tow of fibres is stored in a container. A pair of clips 10, 10′ are applied to the tow of fibres, with the fibres being located within the spaces 18, 18′ of the clips 10, 10′.

[0020] The clips according to the invention may be of any suitable size, but a particularly useful length of clip has been found to be 170 mm, measuring between the pairs of pins, with a pin height of 8 mm.

[0021] The clip may be made of any suitable material and synthetic plastics materials such as polypropylene have been found to be particularly suitable.

Claims

1. A process for the handling of a tow of fibres during manufacture and subsequent processing prior to splicing wherein said process includes the step of applying a clip to the free end of said tow, prior to transport of said tow.

2. A process according to claim 1 wherein two clips are applied to the end of said tow, the first close to the free end of said tow and the second spaced along the length of said tow.

3. A process according to claim 2 wherein said second clip is spaced from said first clip by between 20 and 40 cm.

4. A process according to claim 3 wherein said second clip is spaced from said first clip by approximately 30 cm.

5. A process according to claim 1 wherein said process further includes the step of cutting the end of said tow of fibre adjacent to said clip or said clip closest to said free end of said tow.

6. A process according to claim 1 wherein said fibre is a carbon fibre precursor.

7. A process according to claim 6 wherein said fibre is an acrylic fibre.

8. A process according to claim 6 wherein said clip is removed and said tow spliced prior to the steps of oxidation and carbonisation to form said carbon fibre.

9. A clip for holding an end of a tow of fibres, which clip comprises two substantially straight portions joined at one end by a hinge, the free ends of said two substantially straight portions together forming a clasp mechanism wherein the inner surfaces of said two substantially straight portions are flat and smooth along at least part of the length thereof and in that spacing means are provided on said inner surface of at least one of said substantially straight portions of said clip, such that when said clip is closed, said two substantially straight portions are spaced one from the other by a predetermined amount.

10. A clip according to claim 9 wherein said inner surfaces of said two substantially straight portions are flat and smooth along at least the major part of the length thereof.

11. A clip according to claim 9 wherein said spacing means comprise two pairs of projecting pins provided on said inner surface of one of said substantially straight portions of said clip, said first pair being arranged close to said hinge and said second pair being arranged close to said free end of said substantially straight portion.

12. A process according to claim 1 wherein said clip or clips is a clip according to claim 9.