Patent GB-1436541-A (GB)
Title: Weaving
IPC: D03D47/26
Filed: 1972-05-10
Abstract: 1436541 Looms; shedding CAMBRIDGE CONSULTANTS Ltd 10 May 1973 [10 May 1972 26 Jan 1973] 21902/72 and 4147/73 Heading D1E In a loom, warp yarns are fed from the warp beam 12 so as to produce a slack and each yarn is either shed pneumatically by blowing air through passage 30, Fig. 2, through which the warp threads pass, to move the slack in selected warp threads to the shedding area or tensioned in the shed area by blowing through passage 62, to allow the shuttle 22 to pass between them. The passages 30, 62 may be formed in unit 16, 14 across the width of the shed, each controlled individually to produce travelling wave sheds. For beating-up all of the warps are drawn taut between the fell 46 and passages 30 by blowing air through passages 62 away from the fell, and the warps are then clamped by an electromagnetic clamp 45. Air is supplied to passages 30, 62 through passages 32, 64 respectively communicating with manifolds 34, 66. The slack warps may be separated from the taut to form a clean shed by using the coanda effect, i.e. air issuing from passages 30, Fig. 3 in the direction of the fell tends to adhere to an inclined surface 40, entraining the slack warps with it. Alternatively, Fig. 10, conduits 218, 220 positioned near the exit of yarn passages 202 may direct jets of air into those issuing from passages 220 to divert them and the entrained warp yarns, by momentum transfer onto inclined surfaces 214, 216. By using two inclined surfaces Fig. 10 two sheds may be formed above and below a central warp shed, air supply to conduits 218, 220 being controlled to produce the desired pattern on each surface of the fabric, and wefts can be inserted above and below the central warp sheet. This may also be done utilising the Coanda effect, (Figure 9, not shown) or, by using the Coanda effect to produce one shed and momentum exchange to produce the other (Figure 11, not shown). In an alternative embodiment, Figure 15, shedding is controlled by clamps 234, which in each shedding unit, prevent selected ones of the warps from being shed by pressing them against bars 240, to produce a dobby type control of shedding. Alternatively brakes individual to each warp may be provided to give full pattern control. Picking motions; shuttles, shuttle races Shuttles 22 may be picked by a linear induction motor, Fig. 3 comprising coils 82 and 84 beneath a V-shaped track 80, 81. The shuttle 22 is of a combination of ferromagnetic material e.g. iron or nickel and a non-ferromagnetic conductor, such as aluminium held in a moulded plastics body so that the shuttle is supported by the coils 82, 84 above tracks 80, 81. Shuttles are stored in a hopper 92 in the dummy shuttle loading mechanism prior to insertion, the hopper being topped up under the control of a photoelectric device 94 When they fall beneath a certain level. The shuttles are fed down to the track 80, 81 by worm screws 96 which engage in grooves 98 in the sides of the shuttles. The final turns of screws 96 are toothed as at 102 to engage corresponding teeth in the shuttle grooves 98 to project the shuttles into the shed as they leave screws 96. Selvedges may be formed by having a number of thermoplastic warp yarns at the edges of the warp sheet, and turning over the ends of the weft by a mechanism (not described) onto the thermoplastic yarns and applying 'heat and pressure to cause the weft to be secured. Stop motions; controlling shedding. In the event of detectors (not described) on the weft carrier loading mechanism detecting a weft yarn of incorrect length or one that leaves no portion protruding from the shuttle for the selvedge mechanism to catch a signal is sent to the shedding control system to delay the formation of travelling waves by one cycle so that the defective shuttle does not lay a weft as it is picked. Shedding; pattern cards. Dobby type control of shedding may be provided using fluid logic circuits (Fig. 16, not shown) controlled from manifolds (250) to which air is supplied by pneumatic control valves programmed, for example, by a punched tape reader, tape recorder or conventional dobby programming unit. Various perforated plattens (252) may be used to control exit of air from the manifolds (250) to vary the shedding pattern. Jacquard type shedding control may be provided by controlling air supply to air jets which deflect the warps by means of a perforated metal sheet or roll (268) Figs. 17 and 18 (not shown) moved stepwise to bring apertures (212) therein in line with control ports (266). Beat-up motions, reeds; lays. In one embodiment, Fig. 2, wefts are beaten-up by resilient fingers 112 helically arranged on a rotating cylinder 110 which fingers are guided as they they enter the warp by grooves formed in the surface of element 16. In another embodiment, Fig. 12, wefts are beaten-up automatically by warps 44 which have been shed, and as they are drawn taut draw the weft up inclined surface 228 to the fell. In a further embodiment Figs. 19 and 26, the reed consists of a series of blocks 308 attached to a flexible sheet 310, each block having channels 318 through which the warps pass and acting as channels 30 in the embodiment of Figures 1-5. The blocks 308 are actuated by pneumatic pistons and cylinders 314 to move up to the fell behind the shuttles, as the warps are clamped by clamp 45. In yet another embodiment, Fig. 21, the reed consists of a series of shims 334 fixed in a rubber block which is rotatable about a shaft 336, the shims defining channels at the edges 338 which are closed above by a stationary member 332, and through which the warp threads pass, the channels acting as the passages 30 in the embodiment of Figures 1-5. Beating-up is carried out 'by flexing the shims by virtue of shear deformation of the rubber behind the shuttle by means of pneumatic piston 314.