US2561968A - Device for cutting off the ends of weft threads - Google Patents

Description

.Eufiy 24, 1951 H. BOSSHARD DEVICE FOR CUTTING OFF THE ENDS OF WEFT THREADS Filed June 16, 1949 INVENTOR GSSHARQ HANS Patented July 24, 1 951 assists DEVJICE FORYVCUTTING OFF THE ENDS .WEFT THREADS Hans Bosshard, Frauenfeld, Switzerland Application June 16, 1949, Serial No. 99,560 In Switzerland June 22, 1948 Claims. (01. 139--3-03) Devices which have long been known, associated with the stretching roller of automatic weaving looms, make it possible to out on or shear off the weft thread left on changing .aspool, i. e. on exchanging a shuttle. Nevertheless ends of weft thread remain at spaced intervals along the edge of the cloth, whether they are torn off or out 01f, which ends give the. finished cloth an unsightly appearance. Before the cloth is finished it must, therefore, be freed from these ends of weft thread. This is done in various ways, for example by burning off, which is not without danger, or by hand with scissors. Lately expensive and complicated machines have been constructed which serve this purpose but are not completely satisfactory because in this case also the machine must be minded and the'woven cloth must be subjected to a further working step, which in the last analysisis equivalent to an increase in price or in cost of production.

It is an object of the presentinvention to remove these disadvantages. The present inven tion, therefore, relates to a device for cutting off the end of the weft thread left on changing the spool of an automatic weaving loom with which the device is associated, characterised in that the end piece of the stretching roller cylinder reaches as far as the cutting plane in between the lower stationary shearing blade lying next to the edge of the cloth and the upper mov able shearing blade co-operating therewith, and in that the tensioning wheels of the stretching roller reach so near to the end face of the end piece that the edge of the cloth is guided to reach the said cutting plane. the weft thread is automatically cut off immediately at the edge of the cloth.

In this way the end of The annexed drawing shows one embodiment I by way of example of the subject of the invention.

Fig. l is a rear elevational view.

Fig. 2 is a cross section showing the arrangement of shearing blades adjacent the edge of the cloth taken on the line 2--2 of Fig. 1.

Fig. 3 is a side view showing the construction of a movable shearing blade spaced further away.

According to Fig. 1 the stretching roller consists in the usual way of a cylinder I which is secured by means of a screw spindle 2 passing therethrough to a frame-part 3 connected to the frame of a weaving loom. The cylinder i is provided with a series of tensioning wheels 4 which are provided on their periphery with fine teeth or pins which are intended to engage in the cloth. These tensioning wheels 4 are disposed in the usual way as shown in Fig. 1 with the planes of their discs inclined to the axis of the securing spindle 2 and are mounted to rotate freely about this spindle. The end of the cylinder I at the side of the cloth is formed by an end piece 5. Above the cylinder is disposed a stretching roller guard 6 which is rockably mounted on the frame in the usual way and serves to guide the length of' cloth, not shown. The length of cloth which is thus pulled under the guard 6 over the cylinder I progressively in ac-- cordance with the-progress of the weaving is thus pressed on to the small teeth or pins of the tensioning Wheels 4 and thus causes these tensioning wheels to rotate about the axis of the spindle 2 whereby the cloth is held stretched sideways and the edge of the cloth'is guided exactly over the cylinder l' in a line lying at right-angles to the axis of the cylinder.

According to the present invention the tensioning wheels 4 reach so near to the end face 7 of the end piece 5 that the edge of the cloth is guided to reach as far as the plane of this end face I. At the same time the said end face 1 lies in the cutting plane of the pair of shearing blades nearest to the edge of the cloth. This pair consists of the lower stationary shearing blade 8 and the upper, vertically movable blade 9, so that the end piece 5 reaches as far as the stationary shearing blade 8. The arrangement of the said shearing blades 8 and 9 canbe seenclearly from Fig. 2. The shearing blade 9 is carried in the usual way by a holder H] which is rockably mounted about an axle I I fixed to the frame and parallel to the axis of the spindle 2 and is provided with a lever arm l2 directed obliquely downwards which is caused to move to and fro by any desired means as shown by the double arrow I 3. This movement is most simply derived from the lay of the weaving loom which swings periodically forwards and backwards with a quick return motion. As may be seen from Fig. 2, the movable shearing blade 9 is cut out i in sickle form on the side directed towards the end piece 5 of the cylinder so that it can swing past the end piece 5 of the cylinder unhindered. As a result the edge of the cloth is pressed downwards by the roller margin of the guard B so strongly that it runs immediately above the shearing edge '1. Consequently ends of weft thread projecting from the edge of the cloth come directly on to the shearing edge 'I' where they are sheared off by the co-operating lower edge of the movable shearing blade 9.

As shown in Fig. 1 there are also two further pairs of shearing blades spaced further from the 'edge of the cloth consisting of the stationary shearing blades [5 and the movable shearing blades 16. As shown in Fig. 3 the last-mentioned movable shearing blades Hi are provided with lower edges I5 so short that they do not suffice to shear off the weft thread. These pairs of shearing blades [5, H3 at the most need come into action in the'event of a failure of the first pair of shearing blades 8, 9 and may, therefore, if desired be provided with shearing edges of appropriate lengths.

As may be seen from the foregoing, during the weaving operation the movable shearing blades carry out shearing movements uninterruptedly in rapid sequence, for example corresponding to the shuttle movement so that every projecting weft thread is cut off with certainty close to the edge of the cloth. In order to return the movable shearing blades a spring can also be used which is strong enough to separate the blades from one another even when this is rendered difficult by a thread being clamped therebetween. When using such a spring the bell-crank lever 12 need only be driven positively in one direction, for example by the lay movement, i. e. only to the right as shown in Fig. 2.

What I claim is:

1. In a device for cutting off the end of the Weft thread left on changing the spool of an automatic weaving loom with which said device is associated, at least one stationary shearing blade and co=cperating therewith a movable. upper shearing blade, said upper shearing blade being controlled by a periodically oscillating member of said loom, a stretching roller cylinder provided with a series of tensioning wheels engaging the length of cloth from below and having an end piece arranged with its end face reaching to the cutting plane of said pair of shearing blades and the said tensioning wheels being arranged to reach so near to the said end face of the end piece that the edge of the cloth lies in the cutting plane of the pair of shearing blades.

2. In a device according to claim 1, said movable shearing blade being cut out in sickle shape on a side facing the said end piece of the cylinder.

3. In a device according to claim 1, in which a guard is provided for said stretching roller reaching as far as said movable shearing blade.

4. In a device according to claim 1, in which a guard is provided for said stretching roller reaching downwards to the level, of the shearing edge of said stationary shearing blade.

5. In a device for cutting off the end of the weft thread left on changing the spool of an automatic weaving loom with which said device is associated, at least one stationary shearing blade and co-operating therewith a movable upper shearing blade, said upper shearing blade being controlled by a periodically oscillating member of said loom, a stretching roller cylinder providedwith a series of tensioning wheels engaging the length of cloth from below and an end piece arranged with its end face reaching to the cutting plane of said pair of shearing blades, and the said tensioning wheels. being arranged to reach so near to the said end face of the end piece that the edge of the cloth lies in, the said cutting plane of the pair of shearing blades, and further pairs of shearing blades spaced from said first-mentioned pair of shearing. blades, the lower edges of the movable blades of said. further pairs of blades being so short that they do not suffice to shear the weft thread.

HANS BOSSHARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,157,397 Imbach Oct. 19, 1915 FOREIGN PATENTS Number Country Date 182,366 Switzerland Feb. 15, 1936 626,046 Germany Oct. 14, 1934 685,575 France Apr. 1, 1930

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