GB2087759A - Method of producing metal strip combs, particularly for yarn - Google Patents

Abstract

A method of manufacturing strip combs, which find application particularly in yarn preparation, for example in needle-bar combers, comprises a punching process by which combs (11, 12) are manufactured from steel strip. This process consists in punching an opening, which forms the interstices (16) between two neighbouring comb teeth (14) directed with their points towards each other, in a metal strip (10) perpendicularly and centrosymmetrically to its longitudinal axis, the strip being twice the width of a finished strip comb. This punching is repeated after each advance of the strip (10) through the pitch distance of the teeth (14). <IMAGE>

Description

SPECIFICATION Method of producing strip combs The present invention relates to a method or producing strip combs from a metal strip, especially steel plate.

Strip combs are used in, in particular, the field of yarn preparation, where for example they are carried by carrying rods and form the drafting field of a comber having the task of rendering parallel and uniform and refining the loose fibre webs of predominantly randomly disposed individual fibres.

The conventionally used combs usually consist of individual needles of predominantly round crosssection, which are assembled into needle strips by soldering, gluing or welding and which are in turn so connected with the carrier rods by soldering, gluing or welding or in other suitable manner that each needle is held individually. Also widely used are inherently stable strip combs, again consisting of needles of round cross-section, which are generally fixed by gluing their shanks in a sheet metal profile which is fastenable to the carrier rod by means of screws or rivets.

The needles of such combs are subjected to relatively high stresses during use, especially when unavoidable irregularities, for example knots, occur in the fibre to be processed. This has the consequence of individual needles breaking off or breaking out of their anchorings, so that relatively frequent repair is inevitable. With the multiplicity of needles present in a needle field and the high rate of wear of these parts in high performance machines, it is important that repair or exchange of defective parts can be carried out free of problems. However, a prerequisite for this is that, apart from the need for good access, the exchange elements are produceable in economical manner.

One step in this direction is described in DE-PS 959 624, in which apparently stamped flat needles are used, such needles being inserted into a receiving groove of a carrier rod in, for example, alternation with spacer plates constructed in correspondence with the needle foot. The dimension determining the spacing of the needles from each other is in that case the sheet metal thickness of the intermediate product.

Although the in situ exchange of defective needles is possible with this flat needle and the production of the individual needles is relatively economic, the manipulation of the individual needles is awkward.

In order to counter this disadvantage, it is desirable to provide an element which comprises several needles, is self-supporting and which is connectible in a simple mode and manner with a carrier body.

However, this given rise to problems in punching technology, as the individual needles or comb teeth in such a case must be inserted with their width extending transversely to the fibre stream, i.e. the web width of these teeth may only be very small.

In US-PS 2409 565 there is disclosed an integrally produced comb element which is preferably produced from a dimer in a moulding process. As explained above, however, the individual needles are in use subjected to substantial stress, which obliges their production from metal, preferably steel.

Although the production of comb segments out of steel or other metals is mentioned in the US-PS, there is no explanation of how this is to be achieved.

There is therefore a need for a production method for strip combs wherein an economical production of combs out of steel plate is possible with the use of a punching process.

According to the present invention there is provided a method of producing metal strip combs with spaced apart substantially square-section teeth integrally connected with a web and having inwardly tapering free end portions, the method comprising the steps of providing a metal strip having a width equal to at least twice the required width of a finished strip comb and punching in the strip a series of transverse openings each so extending substantially perpendicularly to and symmetrically of the longitudinal axis of the strip as to form the interstices between a respective pair of adjacent teeth in a first comb and between a respective pair of adjacent teeth in a second comb, the teeth of each such comb being directed towards those of the respective other comb.

A method exemplifying the present invention may have the advantage that strip combs with teeth of such a fineness ratio of thickness to width as, for example, 1:1, can be produced by this punching process with relatively little effort in terms of production technique, the combs being capable of insertion with their width extent transversely to the fibre stream. The provision of exchange elements with a number of teeth simplifies exchange in the event of a defect.

An example of the present invention will now be more particularly described with reference to the accompanying drawings, in which: Figure 1 is a perspective view from above of part of a punching tool for the performance of a method exemplifying the invention, and Figure 2 is a plan view showing the production of a pair of strip combs by the tool of Figure 1.

Referring now to the drawings, in Figure 1 there is shown a punching tool which comprises a cutting plate 1 with an opening 2 corresponding to the outline of the area bounded by the mutually facing flanks of two neighbouring comb teeth or tines 14 (Figure 2) with their free ends directed towards each other. A second opening 3, terminating at a lateral guide edge 6 of an intermediate plate 5 for a metal strip 10, serves for the generation of a stepped edge 17 which, during advance of the metal strip 10, serves as an abutment contacting the abutment corner 4.

Arranged opposite the cutting plate 1 is a guide plate (not shown) which is equipped with the same openings as the plate 1 and in which a centre cutting die 7 and a lateral cutting die 8 are guided. The guide plate resiliently bears firmly against a die receiving plate (not shown) which serves as a mount for the die 8.

In use of this tool, a flank of two teeth 14, directed with their free ends towards each other, is at first formed in the metal strip 10. During this first work stroke, a stepped edge 17 is simultaneously formed at one edge of the metal strip 10 by means of the lateral cutting die 8. The edge 17 limits subsequent advance of the strip 10 through abutment at the abutment corner 4 in such a manner that during each subsequent working stroke a respective tooth 14 with a point 15 is produced through punching out each interstice 16 between two neighbouring teeth 14 of each ofthe strip combs 11 and 12, while an automatic separation of the two combs 11 and 12 takes place.

The strip combs so produced are deburred in a suitable manner, for example by a combination of mechanical and chemical abrasion or by electrochemica polishing. The combs can, for use, be split up into segments each comprising a limited number of teeth, for example 25. This has the advantage that only that segment, which is retained in suitable manner by its web 13, with defective teeth need be exchanged.

The tool can also be equipped with several cutting dies, i.e. with several utilities, so that several interstices 16 can be punched simultaneously. In this case, their spacing from each other corresponds to at least twice the pitch of the teeth.

Claims (6)

1. A method of producing metal strip combs with spaced apart substantially square-section teeth integrally connected with a web and having inwardly tapering free end portions, the method comprising the steps of providing a metal strip having a width equal to at least twice the required width of a finished strip comb and punching in the strip a series of transverse openings each so extending substantially perpendicularly to and symmetrically of the longitudinal axis of the strip as to form the interstices between a respective pair of adjacentteeth in a first comb and between a respective pair of adjacent teeth in a second comb, the teeth of each such comb being directed towards those of the respective other comb.

2. A method as claimed in claim 1, wherein the step of punching comprises punching said openings in a succession of separate steps.

3. A method as claimed in claim 2, wherein the metal strip has a width greater than twice the required width of a finished strip comb and the method further comprises the step of so reducing the width of a respective length portion of the strip to be equal to twice said required width during each of said separate punching steps as to provide a temporary registration shoulder in one longitudinal edge of the strip for limiting advance of the strip.

4. A method as claimed in any one of the preceding claims, wherein the strip is made of steel.

5. A method of producing metal strip combs with spaced apart substantially square-section teeth integrally connected with a web and having inwardly tapering free end portions, the method being substantially as hereinbefore described with reference to the accompanying drawings.

6. A strip comb when produced by a method as claimed in any one of the preceding claims.