Title: Device for making tuft fabric

Description: The present invention relates to devices for making figured fabrics comprising a thread looped on itself, which are generally known under the term of "tuft".

A device of this kind comprises essentially means for controlling the feed rate of each thread or group of threads via a grooved pulley rigid with a friction roller, the said pulley and roller assembly being rotatably mounted on a movable support whereby the roller may be caused to engage either one of a pair of cylinders constantly driven at different speeds, each one of the various supports being controlled by one of the hooks of a jacquard.

In actual practice the supports of these pulley and friction roller assemblies generally consist of rocking levers, each lever being connected on the one hand with a fixed cross-beam via a return spring and on the other hand with the corresponding hook of the jacquard via a compensating spring. When the hook is at its lowermost position the return spring urges the roller for rolling engagement with one cylinder, the roller pressure depending on the reaction of the said return spring, and when the hook is raised, the compensating spring having a suitable force causes the lever to pivot whereby the roller engages the other cylinder against the force of the said return spring, the pressure exerted by the roller against the other cylinder being in this case equal to the reaction differential between the two springs.

The results obtained with this arrangement are particularly satisfactory, and the only inconvenience thereof is that the loops thus obtained can have only two different lengths.

The improvements constituting the present invention aim at avoiding this inconvenience and at permitting of weaving tuft fabrics wherein the loops may have up to four different lengths.

The device according to this invention is characterized in that each movable support is responsive to means adapted to cause the said support to be shifted transversely so that it may engage another pair of cylinders, whereby the corresponding thread can be subjected to four different tension values.

This transverse movement of each support is obtained by pivoting a bell-crank lever having one end connected with the said support while its other end is connected with cord attached on the one hand to the hook of the jacquard adapted to actuate the movable support and on the other hand to a suitable return spring.

A typical example of the manner in which the present invention may be embodied in actual practice is diagrammatically illustrated in the accompanying drawing, in which:

FIG. 1 is a diagrammatic side elevational view of a Verdol jacquard incorporating the improvements according to this invention.

FIGS. 2 to 4 are diagrams illustrating the mode of operation of the device through its various positions.

FIG. 5 is a fragmentary section showing on a larger scale details of the friction roller.

The machine illustrated diagrammatically in FIG. 1 is adapted to form loops on one side of a relatively thick fabric 1. The manner in which these loops are formed will be briefly summarized hereinafter.

The fabric travels intermittently in the direction of the arrow 2 and the needle 3 is driven through the fabric each time the latter is stationary. The needle 3 receives from a spool or bobbin 5 a thread 4 passing through its needle eye. As the needle is driven through the fabric, it carries along the thread 4 to form a loop 7 underneath, as shown, and the loop is retained by a hook 35 during the upward stroke of the said needle 3. Then the fabric 1 is fed one step forwards and the hook 35 is disengaged from the previously formed loop, whereafter the needle 3 is again driven through the fabric to form the next loop. If the tension of thread 4 is moderate, the length of the loop thus formed is equal to the length of the preceding loop since the needle does not exert any tractive effort on the loop. In contact thereto, if a certain tension is applied to the thread 4 the next loop will consist partly of thread fed from the spool or bobbin 5 and partly of thread taken from the preceding loop, so that the resulting loop will have a reduced height. Under these conditions, the two successive loops thus formed will be substantially as shown at 7' and 7, respectively.

Of course, the machine operating the needle 3 comprises a full row of such needles in order to form loops throughout the width of fabric 1.

The support or rocking lever 10 is connected at 14 with a cord 15 of a Verdol jacquard provided with vertically movable griffe frames, wherein each hook 20 is adapted to be moved horizontally by a needle 22 controlled by a pusher 22a adapted to be selectively driven by a grid 22b under the control of a feeler needle 22c selected in turn by a band of perforated paper 23. It will be noted that in order to avoid the presence of a spring liable to be more or less troublesome, the operative connection 14 is obtained by interposing on the cord 15 a vertically elongated loop 15a engaged by a pin (designated by the reference numeral 14) rigid with the lever 10 and leaving a sufficient freedom to this lever. The reference numeral 16 designates on the other hand the return spring associated with the said cord 15. The aforesaid lever 10 is pivotally connected at 11 to one end of a bell-crank lever 36 having its two arms disposed at 90.degree. to each other and its apex pivoted by means of a pin 37 to a fixed bracket. The up and down movements of hook 20 and cord 15 determine a tilting displacement of lever 10, whereby the roller 8 supported thereby will alternately engage the cylinders 12 or 13 in order to impart two different tensions to the thread 4.

The end of lever 10 opposite to the end carrying the friction roller 8 is connected with a resilient blade 29 adapted to snap very rapidly through its position of unstable equilibrium.

The other or opposite arm of the bell-crank lever 36 is connected on the one hand at 38 with another cord 15' associated with a hook 20' and on the other hand with a resilient blade 29' having the same function as blade 29. In this case also a connecting loop 15a' having an elongated vertical aperture is provided to impart to the said lever 36 a sufficient freedom to make it responsive to its blade 29'. The cord 15' is urged downwards by a tension spring 16'. When the hook 20' is at its upper position, i. e. when it cooperates with the frame 21, the lever 10 is so positioned that its roller 8 lies between cylinders 12 and 13, whereby it may engage either of them. As illustrated in FIG. 2, the roller 8 bears against cylinder 13 when hook 20 is at its uppermost position and against cylinder 12 when this hook 20 rests on the bottom board 25 (FIG. 3).

If the hook 20' comes to rest on this bottom board 25, the corresponding arm of the bell-crank lever 36 is lowered in order to actuate lever 10, whereby the corresponding roller 8 will engage a third cylinder 39 parallel to the previous ones 12 and 13. This cylinder 39 is driven at a different speed with respect to the other two cylinders 12 and 13, so that is this specific instance the roller 8 will impart a third tension to the thread 4 (see FIG. 4).

A fourth cylinder 40, shown in dash lines in FIG. 1, may be provided above this third cylinder 39; this fourth cylinder is adapted to be engaged by the said roller 8 when the hook 20' lies on the bottom board 25 and when the other hook 20 is at its upper position. Thus, a fourth thread tension value is obtained and consequently, if desired, loops having four different lengths may be formed during the weaving process. Of course, in this case the cylinder 13 is displaced to the left so that the said fourth cylinder 40 can be positioned ahead of the upstanding arm of bell-crank lever 36.

As illustrated in FIG. 5, the roller 8 comprises essentially an outer race 41 rotatably mounted about a shaft 42 rigid with lever 10, with the interposition of an anti-friction bearing 43, and the said race 41 has a groove 41a formed in its outer cylindrical surface and provided with a resilient tyre 44 of substantially annular configuration, made from a suitable material such as a natural or synthetic elastomer. Preferably, the outer peripheral surface of this tyre has transverse ribs or grooves formed therein to facilitate the passage of knots possibly formed in the thread 4 between one of the cylinders and the said tyre 44.

Preferably, the jacquard is of the double lift and open shed type so that the hooks can be kept at their upper position during several successive cycles.

Without any further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.