EP0467809A1 - Clamping device for retaining weft thread in dummy shuttle looms - Google Patents

Abstract

The invention involves giving the grooved movable jaw (8) an oblique orientation as a result of the positioning of its shaft (7) in relation to the stationary jaw (6a), so as to generate a self-clamping effect on the end of the thread (17) which has just been inserted into the shed and, on the contrary, to allow the controlled slip of the end which has remained fixed to the catch (18) of the false shuttle (14). <IMAGE>

Description

The present invention relates to weaving machines with fixed weft reserves and it refers more particularly, but not exclusively, to those in which the picks are deposited in the step by a weft pass member launched in the manner of the shuttle of 'a conventional weaving machine, organ generally designated for this reason under the name of "false shuttle" which will be used below.

We know that in the trades of the genre in question, the false shuttle is equipped with clamping jaws which open for a moment during the start of the shot so as to allow the introduction of the thread of one of the two weft reserves fixed which is brought to it by an appropriate presenting body. These jaws close immediately to ensure the drive of the wire with the false shuttle in the direction of the opposite side of the loom. On arrival, the jaws open to release the wire, but the latter must be kept axially tensioned so that it can be clamped in step by the louver of the loom; this restraint is operated by one or the other of two lateral gripper devices, the device concerned obviously having to open as soon as the crowd is closed.

The clamp devices used in practice are generally of the type described in Patents FR-A-2,087,725 and 2,202,965 in the name of FABRE. These are pliers whose jaws are elastically pressed against one another in order to ensure permanent retention of the wire, these jaws opening by force during the passage of the false shuttle under the stop effect of a lug provided for this purpose on the latter. The two jaws are carried by a carriage associated with a small actuating cylinder, so that they can be eclipsed upwards at the appropriate time, that is to say when the false shuttle enters the not, with the weft thread pinched between its jaws.

It is understood that the proper functioning of such a system necessarily implies on the one hand an energetic pinching of the wire between the jaws of the clamp device, on the other hand a very high precision in the moments of opening and closing of this device , any unexpected advance or delay in the operation of the movable jaw having the effect of creating a weaving defect. It is to this problem that the invention intends to respond, which relates to the clamp device which is defined in claim 1.

In fact, the invention consists in giving the movable jaw, provided ridged, an oblique orientation with respect to the fixed jaw provided smooth, this orientation being capable of generating a self-tightening effect on the strand of wire which has just been inserted. in the pitch and to allow on the other hand the axial sliding of the strand of wire which remained integral with the false shuttle.

• Fig. 1 est une vue latérale en élévation d'un dispositif de pince établi conformément à l'invention ;
• Fig. 2 est une vue en perspective de ce dispositif supposé démonté de son support, en vue de montrer le côté dudit dispositif opposé à celui qui apparaît en fig. 1 ;
• Fig. 3 est une coupe horizontale schématique illustrant la coopération du dispositif de pince avec le mécanisme de mâchoires de serrage porté par la fausse navette.
• Fig. 4 est une coupe horizontale à échelle très agrandie, apte à bien faire comprendre l'effet déterminé par le mors mobile sur le fil.

The appended drawing, given by way of example, will allow a better understanding of the invention. On this drawing :

• Fig. 1 is a side elevation view of a clamp device established in accordance with the invention;
• Fig. 2 is a perspective view of this device which is assumed to be removed from its support, with a view to showing the side of said device opposite to that which appears in FIG. 1;
• Fig. 3 is a schematic horizontal section illustrating the cooperation of the clamp device with the clamping jaw mechanism carried by the false shuttle.
• Fig. 4 is a horizontal section on a very enlarged scale, capable of making clear the effect determined by the movable jaw on the wire.

In fig. 1 the reference 1 designates a relatively massive support, intended to be fixed on a structure (not shown) positioned at the edge of the selvedge, on the upper part of the comb of a loom. This bracket 1 is integral with two vertical extensions 1 is arranged so as to form wings for the vertical displacement of a carriage 2. The latter is fixed on the lower end of the movable rod 3 of a small pneumatic actuator 4 made integral support 1.

As more particularly shown in fig. 2, on the carriage 2 is fixed a blade 5 oriented vertically downward to carry a small frame 6 whose lower end, provided thinned, is profiled to form a fixed jaw 6 a . The frame 6 is shaped to define two superimposed bearings 6 b inside which a vertical shaft 7 is mounted; the lower end of the latter carries a pivoting jaw 8.

It should be observed here (see FIGS. 3 and 4) that while the face of the fixed jaw 6 a which is turned towards the movable jaw 8 is provided smooth, the corresponding face of this jaw 8 has a series of ridges , referenced 8 a in fig. 4. Furthermore and above all, it can be seen that this movable jaw 8 is oriented obliquely relative to the fixed jaw 6 a , the shaft 7 which carries it being offset towards the center of the loom.

Between the two bearings 6b is engaged the axially split end of an arm 9 (fig. 2) which passes through an opening in the blade 5 so as to be made integral with the shaft 7, by pinching using 'a radial screw such as 9 a . On the upper part of the shaft 7 is wound a coil spring 10, one end of which is introduced into a hole in the adjacent bearing 6 b while the opposite end is made integral with a ring 10 a tightened so adjustable on said axis. This spring 10 thus tends to rotate the shaft 7 and the arm 9 and to apply the ridged jaw 8 against the smooth fixed jaw 6 a , the application pressure being capable of being adjusted by operating the ring 10 a .

For the actuation of the arm 9, a lever 11 with an angled profile is provided (fig. 1) which pivots at 11 a on a horizontal bar 1 b attached against the extensions la of the fixed support 1. One of the two parts of the lever 11 is intended to come to bear against the arm 9 in the manner which will be described later, while the other is coupled to the movable rod 12 of a small pneumatic control cylinder 13 fixed on the support 1, parallel to the cylinder 3-4 associated with the carriage 2.

Before explaining the operation of the clamp device which has just been described, it will be recalled, with reference to FIG. 3, that the false shuttle, referenced 14, is equipped with a usual cutting system 15 and a clamping jaw mechanism 16, clean, under the effect of elastic means associated with an adequate positive control system, to pinch the weft thread 17 to be inserted in the pitch. At the outlet of the clamp 16, the wire 17 normally comes around a lug 18, which, in the usual constructions as well as in the case of the present invention is intended to operate the control of one and the other of the two clamp devices mounted laterally on the comb at the edge of the selvedges, when the false shuttle 14 or other weft pass member out of the crowd.

When the false shuttle 14 enters the crowd, the wire 17 is tightened by the mechanism 16 and is passed around the lug 18, it being observed that the clamp device towards which said false shuttle is located at this time at the low position illustrated in fig. 1 (cylinder 3-4 in extended position). Under these conditions, at the exit of the crowd and while the tightening mechanism 16 has already released the wire 17, the lug 18 strikes the movable jaw 8 which opens to allow passage to said lug. As soon as the latter has passed, the jaw 8 closes again under the effect of the spring 10, which has the effect of pinching the wire 17 between the two jaws 6 a and 8 of the device according to the invention.

It is therefore understandable that any traction exerted on the strand of the wire 17 which has just been introduced into the pitch by the false shuttle 14 (arrow F1 of fig. 4) results in an increase in the clamping force as a result of the obliquity of the movable jaw 8. This self-tightening effect radically avoids any untimely sliding of the pick before the leaf has clamped the latter in the fabric produced.

On the contrary, this same obliquity of the movable jaw 8 allows the strand of the wire 17 between the jaws 6 a and 8 and the lug 18 which has passed said jaws to slide, because any axial traction in the direction of the arrow F2 of fig. 4, however, tends to open the aforementioned jaws.

These self-tightening effects on the one hand and controlled sliding on the other hand constitute a guarantee of clamping efficiency, as well as security avoiding any weaving defect in the event that the cutting of the wire by the cutting system 15 would intervene with a slight delay.

For the rest, the clamp device according to the invention operates in the usual way, in the sense that when the false shuttle enters the crowd again with the wire 17 held by the clamping system with jaws 16, the two jacks 3 -4 and 12-13 are controlled by contraction so that the clamp device is brought into position high to allow the passage of the lug 18 of the false shuttle 14 smoothly from the movable jaw 8, on the other hand that the lever 11 comes to actuate the arm 9 to rotate the shaft 7 and the aforementioned jaw 8, releasing thus the strand of wire 17 which was retained.

Claims (1)

Gripper device for retaining the weft thread in weaving machines with fixed weft reserves, of the type comprising a fixed jaw (6 a ) and a mobile jaw (8) which are associated with elastic means (10) tending to keep them in the pinching position and which are actuated at the opening by a lug (18) carried by the false shuttle or other weft pass-through member (14) after placing the pick in the pitch, characterized in that the shaft (7) which carries the movable jaw (8), provided ridged, is offset towards the center of the loom so that said jaw is oriented obliquely relative to the fixed jaw (6 a ) provided with smooth wall, so that any effort axial exerted on the strand of wire (17) which has just been inserted into the pitch generates a self-tightening effect, while any axial force exerted on the strand of wire (17) which has remained integral with the lug (18) on leaving the crowd, on the contrary, causes the movable jaw to open by allowing the sliding lé wire.

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