WEFT STRAIGHTENING EQUIPMENT

Abstract: A weft straightening equipment comprises a pair of par­ allel chains (16) provided with pins (18) dragging the cloth between the chains; the chains are mounted so as to be diver­ gent towards their ends of outlet of the cloth and are provided with means which vary the convergency thereof, by making them rotate about vertical pivots as a function of lateral devi­ ations of the cloth detected by reading means (20) installed upstream the chains, as well as by means, installed down­ stream the chains, which detect the orientation of the wefts of the cloth and which allow to vary the mutual speed of rotation of the chains in order to straighten the wefts by pulling the cloth obliquely.

Description: The subject matter of the invention is a weft straightening equipment. The object of a weft strainghtening equipment, as revealed by the denomination thereof, is to straighten the wefts of a cloth coming from various working stations installed sequentially along a line, before the cloth itself faces new stations in which it is necessary for the cloth to be well straightened and oriented. At present time, the weft straightening eqipments are formed by apparatuses having a plurality of diagonal curve cylinders between which the cloth is made to pass by making it follow a sinuous way. The cylinders produce a progressive straightening of the wefts of the cloth, which, however, can advance freely, i.e. is not maintained stretched at the edges, and therefore, especially for certain heavy types of cloth no complete and uniform straightening of the wefts is obtained, as would instead be desiderable. US Patent No. 3.751.774 discloses an apparatus for correcting weft distorsions in a longitudinal travelling woven web, wherein the web is made to pass in a differential tenter frame having claims which grab the web and may be driven at different speeds so to straighten the wefts. The web passes over a traditional curved roll expander to allow the strainghtening of the web in the direction of its width. Such an apparatus has the drawback that said curved roll expander does not provide a sufficiently good width straightening which is indispensable for showing clearly the position and the orientation of the wefts when the web reaches reading means that should detect if the wefts are straight or not. The object of the invention is to provide a weft straightening equipment which will allow straightening the cloth in the direction of its width, thus obtaining an even and accurate straightening of all the wefts of the cloth during the advancement thereof. For these and other purposes which will be understood better from the following description, the invention provides a weft straightening equipment according to claim 1. The weft straightening of equipment according to the invention is described hereunder with reference to the annexed drawings in which: Fig. 1 is a diagrammatic sideview of the advancement system of the cloth along the weft straightening equipment; Fig. 2 is a sideview of the equipment according to the invention; Fig. 3 is a plan view of the equipment according to the invention. The cloth 10 passes between a series of transmission cylinders 11 and 12 and a series of curved cylinders 13 and 14 which start to straighten the wefts of the cloth in a known manner. Successively, the cloth passes through an edge-marking photoelectic cell 15, beyond which there are disposed two claim 16 mounted on rollers 17 and provided in their upper portion with pins 18 which grasp and retain the cloth along its lateral edges. Disposed beyond the chains 16 is an idle or motorized roller 19 followed by a grup of reading heads 20 which read the orientation of the wefts of the cloth. The chains 16 are rigidly connected, laterally, to outer shoulders 21 pivoted on the fixed structure 9 at 22 along vertical axes. Moreover, the front rollers 17 of the chains 16 are rigidly connected to pinions 23 which receive the movement from respective motors 24. The front rollers are rigidly connected also to gears (not shown) which mesh with a screw 25 made to rotate by a motor 26, thus allowing to above away from and to approximate to one another the ends of the chains 16 pivoted at 22. Finally, installed in a rear position is a support 27 of a screw or shaft 28 on which there are mounted in a sliding manner two orientation assemblies 29 for the orientation of the rear ends of the chains 16, which act onto the lateral shoulders 21 and hence onto the chains themselves. The operation of the equipment described hereinabove is as follows. First of all, by means of the screw 25, rotated by the motor 26, the desired distance between the front ends of the chains 16 is adjusted, and this in relation to the theoretical width of the cloth and to that which is desired to be obtained,by widening it,before the cloth comes out from the equipment. Obviously, the chains 16 will be adjusted at the entry of the cloth, i.e. in the rear portion, such as to make them converge at the inlet of the cloth, so that the cloth enters the equipment only slightly widened by the cylinders 13 and 14, upstream, but is progressively widened during the advancement between the diverging chains 16, in a condition retained along the edges by the pins 18. The widening , in addition to allowing the cloth to arrive in a well stretched condition to the successive stations, allows to put better in evidence the position and the orientation of the wefts when the cloth reaches to reading heads 20. These heads carry out a true analysis pf the orientation and the disposition of the wefts. Should they detect any anomaly relative to preset theoretical values, they act onto the righthand or lefthand motor 24, so as to vary the speed of rotation of the righthand or the lefthand chain, respectively, relative to the other one. Thus the cloth is displaced in a diagonal direction, inasmuch as the two chains which support it at the edges rotate at different speeds, and this process continues till its wefts return in line in accordance with the preset values. In fact, the reading heads 20, as soon as they detect again a correct orientation of the wefts, make again rotate the motors 24 at the same speed. The heads 20 act also onto the curved rollers 13 and 14, by making them rotate in order to make up also the remaining anomalies of the cloth, in addition to the horizontal orientation of its wefts. Prior to the start of the machine, the operator will have adjusted the convergency-divergency of the chains up to maximum values α (see Fig. 3) variable depending on the type of cloth and equipment. During this initial adjustment the chains 16 rotate on the pivots 21, near the heads 20, thus optimizing the desired convergent-divergent effect. During the advancement of the cloth, the edge-indicating photoelectric cells have the task of displacing the edge-indicating assemblies 29 so as to vary the convergency-divergency angle α of the chains in such a manner that though varying the position or the width of the cloth which is dragged, the edges of this latter will always be well gripped by the pins 18 of the chains, otherwise it would not be possible to straighten the wefts of the advancing cloth; in the sections where it is well retained in a stretched condition between the chains 16. The cloth 10, which during the advancement is also pressed by a brush assembly 30,after the straightening of its wefts, carried out as described hereinabove, comes out from the equipment, guided between the rollers 31, to continue its travel towards successive stations.

Claims: 1. A weft straightening equipment, of the kind comprising: a substantially plane line of advancement and lateral support of the cloth (10),which line is formed by chains (16) mounted side by side, made to rotay by motor means (24) and provided on their periphery with hooking pins (18) serving to hook the edges of the cloth (10) which advances between the chains (16); reading means (20) for reading the orientation and the position of the wefts of the cloth, installed downstream sais chains (16) and connected to variator means (24) intended to vary the relative speed of the chains as a function of and for the entire duration of the deviation of the position of the wefts of the cloth from preset theoretical values; characterized in that the chains (16) are mounted diverging from the inlet end of the cloth (10) towards the oulet end of the cloth; mechanical variator means (27-29) being provided which vary the convergency of the chains (16) as a function of the width and the position of the cloth which advances between the chains. 2. A weft straightening equipment as claimed in claim 1, characterized in that said variator means (27-29) are formed by lateral pushers (29) of shoulders (21) rigidly connected to the chains (16) and sliding transversally in respect of the chains themselves, actuated by edge-indicating photoelectric cells (15) installed at the inlet of the cloth between the chains. 3. A weft straightening equipment as claimed in claim 1 and 2, characterized in that the shoulders (21) are pivoted before the fixed structure (9) along vertical axes (22). 4. A weft straightening equipment as claimed in claim 1, characterized in that the distance of the chains (10) at the ends beyond which the reading heads (20) are installed, is adjustable by means of transversal screw (25), on which screw gears supported by supports (21) of the chains are screwed and which is rotated by motor means (26) on opposite directions in order to move away from and towards one another said ends of the chains. 5. A weft straightening equipment as claimed in claim 1, characterized in that the means (20) which read the orientation and the position of the wefts act also on the positioning of curved rollers (13-14), between the cloth passes, installed upstream said chains.

Inventors: BIANCO, MARIO
Applicants: BIANCO, MARIO
Application year: 1987
Main classification: D06C3
IPC codes: D06H3, D06C3