GB1559526A - Looms - Google Patents

Description

(54) LOOMS (71) We, SULZER BROTHERS LIMITED, a Company organised under the laws of Switzerland, of Winterthur, Switzerland, do hereby declare this invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a loom having shed forming means comprising healds for moving warp threads.

In conventional looms of this kind the shed forming means takes the form of a shaft comprising heald frames in which the healds are suspended. Each heald frame comprises two heavy longitudinal shaft bars extending across the width of the loom, the longitudi- nal shaft bars being joined rigidly at their ends by transverse bars to form a heavy rigid rectangular frame. The heald frames are heavy to ensure adequate rigidity. This is particularly the case with looms with large weaving widths where there must be no risk of heald frames bending in operation. Since the heald frames must be of weighty construction, it is usually impossible to have the htald frames at a pitch of less than about 12mm, since thinner heald frames would not be rigid enough Also, operation with the conventional heavy heald frames is a factor contributing considerably to noise in the weaving shed.

In many looms, the shafts are rigidly connected to the shedding motion such as a tappet motion or dobby so that they are moved by the motion in both directions of their reciproctting motion. It has been proposed, see for example Paten Specification No. 1,395,653, for each shaft to be drawn in one direction by traction elements such as cords connected to one of the longi- tudinal bars of the shaft and to be moved in the opposite direction by springs connected to the other of the longitudinal bars. However, in each case, the healds are carried by the conventional, heavy, rigid heald frame to one bar of which the springs are attached.

According to the present invention, a loom has shed forming means comprising a plurality of spring elements connected to the loom frame and a plurality of parallel draw bars extending across the width of the loom and reciprocatable by the loom drive transversely of their length, each draw bar having connected thereto a row of healds each heald of which is connected to the respective draw bar by one end of the heald and each heald of which is connected by its other end either: a) to its own individual one of the spring elements, or b) to a heald rail to which is also connected other healds of the respective row and which is connected to one of the spring elements without the interposition of any other element extending parallel with the draw bars, the heald rail being of substantially lesser rigidity than the draw bars.

The invention makes it possible to construct a relatively lightweight shed forming means. At the ends of the healds remote from the draw bars, heavy shaft bars can be completely eliminated with either no transverse member or only a light heald rail. The draw bars themselves can be much lighter than the longitudinal bars of conventional shafts and can therefore be relatively thin even for large weaving widths.

The pitch of the draw bars can therefore be small and the combined dimension, front to back, of the complete group of draw bars can therefore be relatively small, with advantages for weaving. Since the reciprocat- ing weights are reduced and since shaft guides can possibly by omitted, there is probably also a reduction in noise.

Since the moving parts of the shed forming means are lighter than previously, the associated shedding motion, for example a tappet shedding motion, can be of correspondingly reduced dimensions.

In a preferred construction, each draw bar is connected to a parallel heald rail to which the ends of the associated healds are attached and there are heald rails to which the ends of the healds remote from the draw bars are connected. With this arrangement, depending upon the pull on the healds by the warp threads and upon the design of the spring elements and also upon weaving width, it is probably possible to use a single spring element for between 10 and 100 healds. Preferably, the heald rails are interconnected by cross-ties. This ensures a constant separation between the two heald rails. The healds placed on the heald rails can then be mounted loosely thereon, can be moved readily thereon and do not ex perience constant pulling by the draw bars and the spring elements, the tension being taken up by the cross-ties instead. Conveniently, the spring elements are connected directly with the cross-ties; for instance, the spring elements can be engaged in eyes in the cross-ties.

The invention may be carried into practice R various ways but a number of looms embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a simplified view of a first loom seen from the warp end; Figure 2 is a side elevation correspond ing to Figure 1; Figure 3 is a view to an enlarged scale of a detail of Figure 2; Figure 4 is a view in front elevation to an enlarged scale of part of the shed forming means of a second loom; Figure 5 is the corresponding section on the line of Figure 4; Figure 6 is a view in front elevation and similar to Figure 4 of part of another loom; and Figure 7 is a section on the line VlI-VII of Figure 6.

Referring now to Figures 1 to 3, a loom, for example a gripper shuttle weaving loom has a frame including two side uprights 2, 3 interconnected by a central beam 4. The loom 1 includes a warp beam 5, a bacic rest 7 and a cloth beam 11 and has warp threads 6, a shed 8 and cloth 9. A catcher 12 and one of the temples 13 can be seen in Figure 2. The gripper shuttle (not shown) for picking the weft thread into the shed 8 enters the catcher 12 after passing through the shed and is returned by a return conveyor to the picking side for a further pick.

For instance, up to 20 shuttles can be moving on the loom circuit.

Secured to the two uprights 2,3 are inclined support members 15, 16 interconnec- ted at the top by a box-like longitudinal member 17 to which a number of crossbearers 19 are secured by means of straps 18. The cress-bearers 19 are formed with grooves 20 receiving longitudinal bars 21 from which flexible rubber tubes 22 are suspended by means of hooks 23 ; the tubes 22 are distributed uniformly across the whole weaving width A. Fixed to the bottom end of each tube 22 is a spring loop 24 which passes through an eye 25 at the top end of a heald 26. A warp thread 6 extends through the usual heald eye 27 intermediate the length of the heald.

At the bottom end of the heald 26 is another eye 28 through which passes a heald rail 29 secured to a draw bar 32 by means of fasteners 31. As can be seen in Figure 3, each of the bars 32 has a greater dimension in its direction of reciprocation than transverse thereto.

Hooks 33 on lifting bars 34 arranged to reciprocate vertically in guides 35 extend up into the hollow draw bars 32 and engage cross pieces 60 in the bars. Each of the bars 32 is driven through a pair of lifting bars 34, a pair of links 41, a pair of bell-crank levers 43,44 oscilatable around pivots 42, a rod 45, a link 46, a two-armed rocking lever 48,49 pivotable around a pivot 47, a link 51, a cam follower arm 54 carrying a cam follower roller 52 and pivotable around a pivot 53, and an associated cam 56 rotatable around a pivot 55 and rotated continuously by the loom drive. The complete tappet shedding motion has the reference 50.

In operation the draw bars 32, the healds 26 thereon and the warp threads 6 are moved up and down in accordance with the weaving programme, as indicated by an arrow 57. In this movement the flexible rubber tubes 22 stretch and contract. When the tubes 22 contract, the elasticity of the tubes 22 raises the healds 26, warp threads 6 and bars 32, so that through the agency of the respective linkages 41 to 49,41,54 the rollers 52 are retained in engagement with the associated cams 56. The upwards movements of the bars 32 and the healds 26 and hence of the warp threads are controlled by the cams 56 but are non-positive whereas their downwards movements are directly produced by the cams 56 and are positive.

A stationary guide plate 59 ensures that the bars 32 cannot move to the left in Figure 1, so preventing the cross pieces 60 disengaging from the hooks 33.

During the descent of the bars 32, the two end portions 61,62 of the tubes 22 which have been pushed on to the tails of the hooks 23,24 will be stretched. An increased contraction stress is therefore applied to the parts 23,24 so that a reliable friction engagement is nroduced. Dnrina thP

Claims (1)

1. cross-ties.

   11. A loom as claimed in Claim 10 in which the spring elements are connected directly to the cross-ties.

   12. A loom having a shed forming means, the shed forming means being sub- stantially as described herein with reference to Figures I to 3 or to Figures 1 to 3 modified as described herein with reference to Figures 4 and 5 or to Figures 6 and 7 of the accompanying drawings.