Scissor-Type Shear for Loom

The present invention relates to a fabric-cutting apparatus for a loom. More particularly this invention relates to automatic scissors-type shear for subdividing a fabric along the length of its warp.

A fabric is often produced on a loom having a width substantially greater than that which is desired in the finished goods. Frequently also the fabric is produced with a so-called false selvage which must be severed in the direction of the fabric warp from the fabric after weaving thereof. It is also known to deliberately drop several warp filaments and subsequently to transversely subdivide the fabric in the gap in the warp created by these dropped filaments.

Since the fabric normally advances at a relatively rapid rate from the preceding weaving, dyeing, or similar arrangement it is necessary to provide a fast-acting automatic shear to cut the advancing fabric along the desired warp line. In one known device an automatic cutter is provided which has a feeler that rides against the extreme outer edge of the fabric, with the blade or blades of the cutter spaced at a predetermined fixed interval from this outer edge. Although such a device is considerably more accurate than a simple fixed cutter, nonetheless minor variations in fabric width, often caused by unavoidable changes in weft tension or beating-up force allow a cut to be made which does not lie at a fixed distance from a given weft element so that an irregular fringe is produced. In such an arrangement it is also frequently very difficult to adjust the position of the cutter.

It is therefore an object of the present invention to provide an improved fabric cutter.

Yet another object is the provision of an improved scissor-type automatic shear for cutting a fabric in the direction of its warp as it is continuously advanced in this direction.

A further object is to provide a cutter or shear which can readily be adjusted automatically to track between a given pair of warp filaments.

These objects are attained according to the present invention in a device for cutting a fabric lengthwise between a pair of warp filaments as it advances continuously. This device comprises a support which carries a first blade and is pivotal about a vertical pivot axis. Guide means is provided including at least one feeler engageable with at least one of the warp filaments between which the cut is to be made for pivoting the support about the axis and thereby positioning the blade between the filaments. A second blade is pivoted on the support and means is provided for oscillating the second blade relative to the first blade for shearing the advancing fabric between the pair of filaments.

According to another feature of this invention the support is provided with a generally vertically oriented lever carrying the second blade and pivoted on the support about a horizontal axis. Between the upper end of the lever and the support there is provided a tension spring which urges the two blades of the shear together, and the bottom end of this lever carries a barrel-shaped roller having the shape of an ellipsoid of revolution with truncated ends. A continuously rotating cam has at least one lobe which on each revolution of the cam engages this roller and opens the shear.

According to yet another feature of this invention there is provided on the support an adjustable abutment against which the lever lies when out of engagement with the cam. This abutment is so positioned that the roller on the other end of the lever lies out of contact with the cam except when engaged by the lobe therof. Thus there is very little resistance to lateral displacement of the support and exact alignment between the pair of warp filaments between which the cut is to be made.

According to yet another feature of this invention the guide means is provided with a pair of feelers each constituted as a bent wire. One end of each wire is clamped on the support and the other end lies to a respective side of the blade and is positioned to run along a respective warp filament. These feeler ends adjacent the blades lie slightly downstream of the cutting portion of these blades. The clamp that secures the feelers to the support is adjustable so as to allow positioning of their ends at different spacings.

The cutting device according to the present invention therefore allows the blades exactly to track along the line between a given pair of warp filaments. In this manner it is possible to cut the fabric exactly between these filaments, even when the lateral or weftwise spacing of these two filaments varies somewhat.

The above and other objects, features, and advantages will become more readily apparent from the following, reference being made to the accompanying drawing, in which:

FIG. 1 is a side elevational view of the apparatus according to the present invention;

FIG. 2 is a top view of the apparatus of FIG.1;

FIG. 3 is a side elevation view of the support of the apparatus of FIG. 1;

FIG. 4 is a side elevational view of the lever and movable blade of the apparatus of FIG.1;

FIG. 5 is a top view of the lower end of the actuating lever of the apparatus; and

FIG. 6 is a top view partly in section illustrating the feelers of the apparatus.

As shown in FIGS. 1 and 2 the apparatus according to the present invention comprises a support 1 pivotal in ball bearings 4 about a vertical axis A defined by a pin 2 fixed in a block 26 secured by means of an Allen screw 27 on a fixed horizontal mounting shaft 3. Thus this horizontally elongated support 1 can swing about the vertical axis A and can be positioned anywhere along the rod 3.

On its outer end the support 1, as also shown in FIG. 3, is provided with blade 5 having a cutting edge 5'. Rivets 6 secure the blade 5 to the support 1 with the edge 5' inclined to the horizontal

An axle pin 7 pivotally carries a lever 8 to which is secured another blade 10 by means of three rivets 9. These rivets 9, like the rivets 6, are angularly equispaced about an axis A' perpendicular to the axis A and defined by the axle pin 7. The blade 10 has a cutting edge 10' which normally lies horizontal and across the edge 5'. At its lower end the lever arm 8 is provided with a pivot pin 11 defining an axis A" parallel to the axis A' and carrying a barrel-shaped roller 12. A motor 28 continuously rotates a shaft 14 carrying a two-lobe cam 13. The lobes 13' of this cam are engageable with the roller 12, but the lands 13" between these lobes 13' are normally engaged with the roller 12. This is effected by an abutment constituted by an eccentric disk 16 secured by means of a tightenable screw 25 to the support and engageable with the upper end of the lever 8. A tension spring 15 is connected between the support and the upper end of the lever 8 to normally urge the upper end of the lever 8 back against the abutment 16, thereby bringing the roller 12 as close as possisble to the cam 13. Thus rotation of the cam periodically pivots the lever 18 against the force of the spring 15 and thereby oscillates the edge 10' across the edge 5'.

A roller 24 draws a web, here a fabric 22 having a pair of spaced-apart web filaments 20 and 21, through the apparatus, with that stretch of the web 22 downstream down of the blades 5 and 10 being pulled into the mouth between these blades 5 and 10.

The support is further provided with clamping nuts 16 into which hook-shaped end 18a and 19a of a pair of feeler wires 18 and 19 are secured. The other ends 18b and 19b of these wires 18 and 19 are bent to extend vertically upwardly and lie on opposite sides of the blades slightly downstream of the location at which the edges 5' and 10' normally cross. The end 19b which is shaped so as to be semicircular in section, therefore rides against the weft filament 21, and the round end 18b of the wire 18 rides against the filament 20. This causes a fringe 23 to be produced which is always of identical length, as the guides 18 and 19 cause the support 1 to pivot about its axis A, keeping the blades 5 and 10 exactly aligned between the warp filaments 20 and 21.

The support 1 pivots very easily about the axis A because of the bearings 4, and also because the roller 12 only periodically engages the lobes 13'. Thus very little force need be exerted against the ends 18b and 19b in order to pivot the support 1 and perfectly align the blades 5 and 10 between the filaments 20 and 21.