US2897850A - Ladder webbing - Google Patents

Description

4, 5 M. STEPHENSON ETAL 2,897,850

LADDER WEBBING 2 Sheets-Sheet 1 Filed Nov. 1, 1955 11111111 nun FIG.

y Cu m 2 Sheetg-Sheet 2 Filed Nov. 1, 1955 b h h N m AvAvAvAvAveAv QUU IU H U INVENTORS MATTHIAS STEPHENSON JOHN SELLARS ATTO E N EYS States Patent 2,897,850 Patented Aug. 4, 1959 fiice LADDER WEBBING Matthias Stephenson, Sale, and John Sellers, Chorley, England, assignors to Thomas French & Sons Limited, Manchester, England, a British company Application November 1, 1955, Serial No. 544,259

11 Claims. (Cl. 139--384) This invention relates to the manufacture of woven ladder webbing, that is to say webbing comprising at least two woven main bands having a plurality of overlapping cross straps between adjacent main bands, the ends of which cross straps are secured to the main bands by the weft thereof during weaving. Such ladder web is hereinafter described as the kind referred to.

In all the known forms of earlier construction of ladder web of the kind referred to at least one end of some of the cross straps had a short unwoven (weftless) portion of about inch or more in the length of the strap, such portion being at least as long as any overlying overlap of consecutive cross straps. Woven ladder webbing of the kind referred to is used mainly in the construction of Venetian blinds and the disadvantages of such short unwoven portions of the cross straps are that they catch the eye and at first sight look like a weaving fault. Also the unwoven warp threads obviously provide less wearresistance for their essential function of supporting the slats of the blind.

It has hitherto been considered as impractical to introduce weft into the cross straps at the overlap in a ladder web having pairs of overlapping cross straps as this seems impossible without necessitating the use of six shuttles as compared with the generally accepted practical maximum of four shuttles. Such ladder web has therefore only had one cross strap of each pair woven leaving the other of the pair unwoven.

The object of the present invention is an improved ladder webbing in which the cross straps are, in effect, woven throughout their length including the overlying overlapping portions aforesaid without entailing the use of additional weft shuttles and the invention is based on a new appreciation of the Weaving problems involved.

The invention comprises the method of weaving ladder webbing of the kind referred to characterised in that at the overlying portions of two consecutive cross straps the same weft is laid alternately first in one cross strap and then in the other to form small groups of weft of at least three picks each and then severing the weft trails between such groups, whereby the said severed groups of weft give an almost fully woven effect at such portions of the cross straps.

The method aforesaid may be further characterized in that the small groups of weft are so arranged that there is one such group in each strap close against each of its ends where it joins the main band; or further characterised in that the cross straps are arranged in pairs in two rows and in that the changeover of the weft between the said small groups is effected so that the weft trails between them are located at the inner edges of the cross straps; or further characterised in that the weft trails between the groups are severed during weaving.

The invention also includes the product of the method aforesaid.

In the accompanying drawings:

Fig. '1 is a perspective .view of a short length of ladder webbing made in accordance with one example of the: invention, part of the upper main web being cut away where it would obstruct vision of the cross straps;

Figs. 2 and 3 are weaving diagrams which together make a complete repeat;

Fig. 4 is a fragmentary view showing the actual order of laying of the picks in the ends of the cross straps;

Fig. 5 is a cross section on KK, Fig. 3.

As can be seen from the drawings, the ladder webbing consists of upper and lower main bands a and b between which are pairs of cross straps arranged in two rows. For reasons which will be evident later, alternate pairs of cross straps are indicated as c, 0, while the intermediate pairs are indicated as d, 01.

As shown in the weaving pattern there are four rows of dots A, B, C and D which represent picks laid by individual shuttles of a 4-band loom. In order to avoid confusion, one longitudinal half of the ladder webbing with its row of cross straps c, d, is shown in the upper part of Figs. 2 and 3, while the other half with its cross straps c, d is shown in the lower part of Figs. 2 and 3. The warps for the main webs are omitted from the weaving diagrams so that the arrangement of the warps used for the cross straps is more easily seen. In the upper parts of Figs. 2 and 3 it can be seen that four sets of warps are used numbered 1, 2, 3 and 4, of which Nos. 1 and 3 are used for the cross straps 0, while Nos. 2 and 4 are used for the cross straps a. Similarly, in the lower part of Figs. 2 and 3, there are four sets of warps numbered 5, 6, 7 and 8 respectively, of which Nos. 5 and '7 are used to make the cross straps c and Nos. 6 and 8 are used to make the cross straps d. The cross strap a starts at e (Fig. 3) when the warps 1 and 3 are brought down and shed for weaving with picks A of the upper main band and ends at f (Fig. 2) where the warps are taken down further for weaving with picks D. The warps pass up with a short cross-over at g for shedding again with the picks A, the warps being ultimately cut at g. The cross strap d similarly starts at h (Fig. 2) and ends at i (Fig. 3), the short cross over of the warps which is subsequently out being at j.

The novel feature of the constructions occurs between it and f and between e and i respectively where the beginning of the cross strap d overlies the end of the cross strap 0 and where the beginning of the cross strap 0 similarly overlies the end of the cross strap d. Looking for example at the location between h and f, it can be seen that the warps 3 and 1 which between i and h have been shed with picks C to form the centre of the cross strap c are floated below four picks C while the warps 2 and 4 at the start of the cross strap d are shed therewith; then warps 2 and 4 are floated above four further picks C while warps 1 and 3 are again shed therewith; then warps 2 and 4 are shed with four further picks C while warps 1 and 3 are again below, and finally the warps 1 and 3, being the end of the cross strap 0, are shed with six picks C; after which the warps 2 and 4 are shed from f (Fig. 2) to :2 (Fig. 3) with picks C to form the centre portion of the cross strap d. Similarly, between e and i (Fig. 3) the warps 2 and 4 and the warps 1 and 3 are shed for alternate groups to picks C. Corresponding points e', f, g, h, i', and j for the cross straps c and d are marked on the lower part of Figs. 2 and 3 where the warps 5, 7 and 6, 8 are shed with the picks B simultaneously with the weaving of the cross straps c and d as above described.

As can be seen in Fig. 5, the weft picks C and B cross between the overlying cross straps at their inner edges. The cross over for the weft picks B are also shown in Fig. 4 but those for the weft picks C are omitted for clarity. It has been found that these wefts can be cut as take-up occurs by inserting a knife laterally between the cross straps during weaving of the overlap, the knife being withdrawn at other times to avoid damage to the cross straps.

In reiteration, Figs. 2 and 3 comprise one weaving diagram of the ladder webbing shown in Fig. 1. They are to be viewed as though the left end of Fig. 3 is adjoining the right end of Fig. 2, and the weaving thus proceeds from the left to the right of Fig. 2 and continues from the left to the right of Fig. 3. Initially, at the left end of Fig. 2 the central portions of a pair of cross straps c and c are being woven and when the right end of Fig. 3 is reached, the central portions of a second pair of cross strapsc and c are being woven. Consequently, Figs. 2 and 3 show a complete cycle in the repetitive weaving process and they can be considered as one drawing. V

The row of dots A, B, C and D in both Figs. 2 and 3 represent the picks of the loom. For the sake of clarity the ladder webbing has been longitudinally halved and the four rows of dots are repeated twice, the upper set illustrating the weaving thereon the rightcross straps c and d (Fig. 1) and the lower set illustrating the weaving thereon of the left cross straps 0' and d (Fig; l). The lines 1 through 8 represent warp threads, cross strap 0 being woven by warps 1 and 3, cross strap d by 2 and 3, cross strap 0 by and 7, cross strap d by .6 and 8. Wherever any of these pairs of lines (or warps) are embracing dots (or picks) in row A, they are being woven into the upper main band a of Fig. l. Wherever they are embracing dots in row D, they are woven into lower main band b of Fig. 1. Wherever they are embracing dots in row B, they are woven into cross straps c and d. And wherever they are embracing dots in row C, they are woven into cross straps c and d.

The repetitive weaving cycle for cross strapsc and d and cross straps c' and d is substantially identical; hence we shall consider only the weaving of cross straps c and d. Between j and h, warps 2 and 4 are woven into the wefts of upper main band a. Between h and 1, they are beginning to weave the cross strap d but are woven only with alternate spaced groups of wefts. (Therother alternate groups of wefts, which they skip, are woven into cross strap 0.) Between 1 and e, warps 2 and 4 are fully woven -to form the central portion of web d. Between eand i, they again arealternately woven with groups of wefts, as they were h and 3. Between i and j,war"ps 2 and 4 are woven into the wefts of lower main band b. j they cross over through cross strap c to upper main band a,

and the cycle is repeated.

Warps 1 and 3, meanwhile, have been weaving cross strap 6'. Between g and e warps -1 and 3 are woven into the wefts of upper main band a. Between e and i they begin to form the cross strap c'but are woven alternately with spaced groups of weft c which is also alternately being woven into cross strap d. Between i and Ii, theyare fully woven to form the central portion of cross strap 0. Between 11 and 1, they are alternately woven with cross strap d, and between f and g they are woven into lower main band 12. At g they cross over to upper main band a and start all over again. i

Fig. 5 shows how the wefts in the overlapping portions are carried from cross straps and c to cross straps d and d. Here the dots represent the warps and the lines B and C represent the respectivewefts. Neither the outer band warps or wefts are shown and thecross straps are again side by side as in Fig. 1 rather than one above the other as was the case in Figs. 2 and 3 where greater clarity .was thereby achieved. The section is also typical of the weave between 11 and f. This feature is further illustrated in Fig. ,4 and isfully explained in the ffirst paragraph of page 7 of the specification.

The invention is obviously not limited mall the details of the example above described and .sho.wn in the drawings, in so far as .such details may he modified without departing from thescope of the invention. For instance, the cross strap warp threads for binding in to the main hands by the shuttle picks A and D, are shown shed substantially 1 .ou-t, 3 in. could be changed to 2 out, 2 in or any other suitable shedding arrangement, but the preferred arrangement shown, i.e. 1 out, 3 in has the advantage, compared with the 2 out, 2 in, that there is less crowding of the warp threads in the main bands and hence less tendency for giving such main bands any appearance of irregularity of width.

In Fig. 4 the small groups of weft are shown in the positions which they should theoretically occupy with the gaps between, but infact the weft in these groups spread out automatically so that the gaps become far less visible and the first impression given to the eye is that the cross straps are all wbven to their ends.

We claim:

1. Ariiethod of weaving ladder webbing comprising at least two woven main bands having a row of only partially longitudinally overlapping cross straps between adjacent main bands, the ends of which cross straps are secured to the main bands by the weft thereof during weaving, characterised in that at the overlying portions of two consecutive'cross straps the same weft is laid alternately first ly between all the warps of one cross strap and then between all the warps of the other to form small groups of weft of at least three picks each and then severing the weft trails between such groups, whereby the said severed groups of weft give an almost fully woven effect at such portions of the cross straps.

2. A method of weaving ladder webbing as claimed in claim 1 further characterised in that the small groups of weft are so'arranged that there is one such group in each strap close against each of its ends where it joins the main band.

3. A method-of weaving ladder webbing as claimed in claim '1 further characterised in that two side-by-side rows of substantially identical cross straps are arranged between adjacent main bands and in that the changeover of the weft between the said small groups is effected so that the weft trails between them are located at the inner edges of the cross straps.

4. A method of weaving ladder webbing as claimed in claim l further characterised in that the weft trails between the groups are severed during weaving.

5. A method of weaving ladder webbing having at least two woven main bands and a plurality of longitudinally only partially overlapping cross straps, the ends of which cross straps are bound into the main bands by the weft of the latter during weaving, which comprises ernploying a pairof cross strap weft threads and weaving each of said cross strap weft'threads first into all of the warps of the central portion of a particular cross strap, then alternately into and between all of the warps of each of the overlying unbound-in portions of said particular cross strap and the next succeeding cross strap, then continuously into and between all of the warps of the central portion of said next succeeding cross strap and then alternately into and between all of the warps of each of the overlying unbound-in portions of said next succeeding cross strap and the next following cross strap, whereby each cross strap is provided with end portions adjacent its bound-in ends having a weft density of substantiallyone-half the weft density of its central portion, and then severing the weft trails between said overlapping portions of the cross straps.

6. A method of weaving-ladder webbing according to claim 5 in which the weft in each of said overlying portions of said cross straps is woven thereinto to form spaced groups ,of weft of at least three picks each.

7. Method of weaving ladder webbing according to claim .5 .in which the webbing contains two or more side-by-side rows of cross straps, each row containing a plurality .of longitudinallyonly partially overlapping cross straps in which the same cross strap weft threads are employed toweave all of .thecross straps, the weaving of side-by-side cross straps taking place at the same time.

8. Ladderwebbing comprising at least two Woven main bands having a plurality of longitudinally overlapping cross straps extending therebetween, the ends of the cross straps being bound into the main hands by the weft of the latter during weaving, each of said cross straps having a central portion all of the warps of which are fully woven and end portions adjacent its bound-in ends all of the warps of which are woven to a weft density of one-half that of said central portion.

9. Ladder webbing according to claim 8 in which the woven end portions of each cross strap contain spaced groups of weft of at least three picks each.

10. Ladder webbing according to claim 8 in which the end portions of each cross strap adjacent its bound-in ends are the portions of said cross strap that overly and underly the next Iadjacent cross straps on opposite sides thereof during weaving of the ladder webbing.-

11. Ladder webbing comprising at least two woven main bands having a row of only partially longitudinally overlapping cross straps between adjacent main bands, the ends of which cross straps are secured to the main hands by the weft of the latter during weaving, wherein weft is woven alternately first between all the warps of each overlapping portion of one cross strap and then between all the warps of the adjacent overlapping portion of another to form small groups of weft of at least three picks each, the weft trails of which are severed between such groups whereby the said severed groups of weft given an almost fully woven eifect at such portions of the cross straps.

References Cited in the file of this patent UNITED STATES PATENTS 1,815,196 French et al July 21, 1931 2,775,265 French et al Dec. 25, 1956 2,847,039 French Aug. 12, 1958 FOREIGN PATENTS 899,780 Germany Dec. 15, 1953

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