EP0947620B2 - Method of producing a heddle, heddle and shed forming device for a loom - Google Patents

Description

The invention relates to a method of manufacturing a loom for Jacquard loom harness.

In a crowd forming device for a jacquard loom, each hook is associated with an arcade to which several cords are connected, all of these cords constituting the harness of the Jacquard mechanism. In its lower part, each cord is hooked to the upper end of a bar which carries a grommet for passing a warp.

The healds are usually formed of metal rods. In particular, it is known to form a rail by joining two rods or metal strands which are then welded or brazed with tin over most of their length and nickel-plated to avoid possible oxidation of tin to induce dirt from the warp threads. The method of assembly of the bar by welding of the metal rods and nickel plating must be made with the utmost care, otherwise the bar may have surface irregularities may injure or sever, the neighboring warp son. In addition, if this assembly is not the most careful, the bar does not have sufficient strength to perform its function is to oscillate vertically, exerting a tensile force on a warp, several hundred times by minute.

Furthermore, an eyelet is disposed in an intermediate portion of the bar after the two strands that constitute it have been separated from one another. The height over which the two strands are spaced from each other can not be precisely controlled, so that the housing provided to receive a guide eyelet is too large in a direction parallel to the main axis of the smooth, to the point that the eyelet is badly or not held in position between the threads.

In addition, the eyelet must be brazed between the rods or strands to hold in place and withstand the reaction forces of the wires, which can generate variations in thickness or the formation of irregularities or "scratches" near the point passage of the wires. This can also have the effect of using the son or even lead to their break. To avoid these problems of abrasive wear, the smooth surfaces must be polished after placement of the eyelets, such an operation can be performed only manually given the usual dimensions of the rails.

For all the above reasons, the slats of the prior art are not entirely satisfactory from the technical point of view and are of relatively high manufacturing cost, in particular because of the finishing operations, which has a significant effect on the total cost of a crowd training device, including Jacquard type, which can count up to 10 000 smooth or more.

DE-A-1950903 teaches forming a slot in a steel strip, by means of a spacer tool, for the purpose of forming a frame rail. In the embodiment described, the band is provided with a stamping impression, then the band is shaped by means of the tool, so as to form a slot which is expanded by deformation of the material of which the band is made. . At the same time as the widening of the slot to its full width, it is fitted with the tool, an eyelet, before its subsequent fixing, for example by welding.

It is to these drawbacks that the invention more particularly intends to remedy by proposing a method of manufacturing a smoother more economical and more reliable than those of the prior art.

In this spirit, the invention relates to a method of manufacturing a bar according to claim 1.

Thanks to the invention, it is not necessary to use two juxtaposed rods of tin, because the receiving housing of a guide eyelet is formed in the single strand of wire that constitutes the smooth. The control of the dimensions of the notch can be carried out accurately according to the embodiment of this notch, which facilitates the establishment and maintenance of the eyelet, while it is no longer necessary to use a method of attachment that may result in the formation of surface irregularities of the stringer. The wear risks of the warp yarns are thus substantially reduced.

Since the notch is made in the single-strand filamentary element by cutting by means of a laser beam or a jet of water, a high precision is obtained in the dimensions of this notch, whereas high production rates can be obtained. to be reached.

According to alternative embodiments of the method of the invention, it consists in fixing the eyelet in the notch by gluing, tinning, welding, in particular laser welding, or crimping. Advantageously, laser is welded an external surface of the eyelet with the edges of the notch. In all cases, the risks of abrasive wear of the warp yarns are very significantly reduced.

According to another advantageous aspect of the invention, the eyelet has a periphery of thickness less than or equal to that of the monofibrous rod. This avoids any danger of interference in the eyelets between neighboring rods, during rotations of the rails around their respective longitudinal axes, insofar as the eyelets do not form angular projection outside the smooth.

According to a particularly advantageous aspect of the invention, the eyelet has an outer surface adapted to the conformation of the spaced edges of the notch. This aspect of the invention allows to consider fixing the eyelet in the notch by the methods mentioned above, which avoids deburring. According to the embodiments of the invention, the eyelet has an outer surface spindle-shaped or generally elliptical.

In addition, the eyelet may be welded punctually, at its outer surface, on the edges of the notch.

• la figure 1 est une vue schématique partielle d'un métier à tisser de type Jacquard ;
• la figure 2 est une vue à plus grande échelle en perspective du détail II à la figure 1 ;
• la figure 3 est une vue en perspective d'une partie d'une lisse conforme à l'invention, lors d'un premier stade de fabrication ;
• la figure 4 est une vue analogue à la figure 3 lors d'un second stade de fabrication ;
• la figure 5 est une vue analogue à la figure 3, lors d'un troisième stade de fabrication et
• la figure 6 est une vue analogue à la figure 3, lors d'un quatrième stade de fabrication.

The invention will be better understood and other advantages thereof will emerge more clearly in the light of the following description of a manufacturing method and a loom Jacquard type of loom consistent with its principle, given only by way of example and with reference to the appended drawings in which:

• the figure 1 is a partial schematic view of a Jacquard loom;
• the figure 2 is a larger-scale perspective view of detail II to the figure 1 ;
• the figure 3 is a perspective view of a portion of a rail according to the invention, during a first stage of manufacture;
• the figure 4 is a view similar to the figure 3 during a second stage of manufacture;
• the figure 5 is a view similar to the figure 3 at a third stage of manufacture and
• the figure 6 is a view similar to the figure 3 at a fourth stage of manufacture.

The figure 1 represents, very schematically, a Jacquard machine 2 of a loom. This mechanism controls several arches, of which only one, 4, has been shown which passes through a guide board 3. The lower end of this arch is associated with several cords 6. The set of cords 6 forms the harness of the loom . Each bead 6 is hooked to the upper end of a rail 8 for controlling the position of a warp wire 10. Each rail is fixed, by its lower part, to a spring 12 secured to a fixed anchor frame 14 thanks to a wired element 16.

The central part of the rail 8 visible at figure 2 corresponds to detail II at the figure 1 .

Each heddle 8 is formed of a threadlike element 20, the section 20 has is elongated or flattened. The element 20 consists of a single stainless steel rod whose width l is about 3 mm while its thickness e is about 1 mm. In practice, the width l can be between about 1 and about 5 mm, while the thickness e is between about 0.3 and about 1.2 mm. In some cases, lower ratings may be used. The length of the element 20 depends on the configuration of the loom. It is generally between about 300 and about 400 mm.

An eyelet 22 for guiding a warp 10, visible at the figure 1 , is in place in a notch 24 formed in a central part of the element 20.

The method of manufacturing the bar 8 is explained with reference to Figures 3 to 6 . At the stage of figure 3 the element 20 is a flattened rod. At the stage of figure 4 , forming, thanks to a cutting laser beam, the notch 24 whose dimensions can be determined with very high accuracy given the cutting mode used. The use of a laser beam makes it possible to dispense with the use of a mechanical system for forming a notch, such a mechanical system not being, in practice, not precise enough to allow the creation of a cut in a rail the dimensions of which have been indicated above while it is necessarily subject to wear detrimental to its accuracy.

In practice, the notch 24 has a length L ', parallel to the largest axis XX' of the heald 8, between about 8 and about 15 mm and a width l ', perpendicular to the axis XX', of the order of 0.1 to 0.3 mm. In some cases, lower ratings may be obtained. The notch 24 is formed by being perpendicular to the two largest faces 20b and 20c of the element 20.

Given the cutting mode used, the mechanical stresses exerted on the element 20 during the cutting operation are small. There is no created areas hardened or weakened during this operation.

The cutting operation could also be carried out, with the same advantages, by a water jet under pressure.

At the stage of figure 5 , The edges 24 a and 24 b of the notch 24, which are generally parallel to the axis XX ', are separated in two directions F and F' substantially perpendicular to the axis XX '. The generated deformation of the edges 24 a and 24 b is plastic, the edges 24 a and 24 b remain in the separated position shown in figure 5 . The width l 'of the notch 24 is then substantially increased to about 4 mm. Of course, the width of the obtained depends on the width l of the element 20 and the length L 'of the notch 24.

In this configuration and as shown in figure 6 It is possible to introduce into the notch 24, an eyelet 22 whose outer surface 22 a is adapted to cooperate with the edges 24 a and 24 b of the notch 24. The width l is chosen to be slightly less than that of the eyelet 22, for example from 0.1 to 0.3 mm, so that the establishment of the eyelet 22 takes place thanks to a small additional deformation of the arms 24 a and 24 b .

In this embodiment, the eyelet 22 has a spindle shape that corresponds substantially to the shape of the notch 24 shown in FIG. figure 5 , eyelet 22 being elongated in the direction of the notch 24, that is to say XX '.

The eyelet 22 is then immobilized in the notch 24 by cooperation of forms, that is to say by wedging. The final immobilization is obtained by four welding points 26 distributed over the area of contact between the eyelet 22 and the edges 24 a and 24 b, that is to say the surface 22 a. The number and position of the weld points 26 results from a choice of the practitioner according to the selected materials and dimensions. The welding of the elements 20 and 24 is performed on one side of the rail 20, by means of a YAG laser, by localized fusion of the elements 20 and 22. Of course, the welding could be performed on both sides 20b and 20c. c the smooth, in which case the number of weld points is doubled.

Alternatively, a crimping operation may be provided to reinforce the anchoring of the eyelet 22 within the notch 24.

Of course, the eyelet 22 can also be glued or tinned inside the corresponding notch.

The fact that the element 20 is made of stainless steel provides a nickel plating operation, which allows a reduction in the cost price of the smooth relative to known devices and avoids irregularities.

Whatever the embodiment, the eyelet 22 has, at its outer peripheral surface 22 has a thickness substantially equal to the thickness e of the rail 20. In practice, the thickness of the periphery 22 has the eyelet 22 is less than or equal to the thickness e , so that it can be installed without protruding angularly with respect to the faces 20b and 20c . The eyelet 22 has been shown flat. However, it can be bulging, in which case it is thicker than the element 20 in its central part.

The invention has been described with a smooth section uniformly flattened. However, it is applicable with other types of solid single-strand, including circular section, possibly flattened by crushing in the area intended to receive the eyelet.

An irregular section is also possible.

Claims (3)

1. Method for manufacturing a metal heald for a harness of a Jacquard-type loom intended to be hooked, by a first end, to a cord of said harness and, by a second end, to an elastic return means, characterised in that it consists in

   - producing, in a single-strand thread-like stainless steel element (20), by cutting out by means of a laser beam or a water jet, a notch (24) which is overall parallel to the largest axis (XX') of said thread-like element;

   - plastically deforming the edges (24a, 24b) of said notch by spreading them apart from one another over a width (l') which is slightly smaller than that of an eye (22), the outer surface (22a) of which is adapted to cooperate with said edges once they are spread apart and which is provided for guiding a warp thread (10);

   - arranging said eye between said spread-apart edges thanks to a small additional deformation of said edges in such a way that said eye is immobilised in said notch by cooperation of shapes and by jamming, and

   - permanently fixing said eye in said notch.
2. Method according to claim 1, characterised in that it consists in fixing said eye (22) in said notch (24) by gluing, tinning, welding, especially laser welding, or crimping.
3. Method according to claim 2, characterised in that it consists in spot-welding by a laser (26) an outer surface (22a) of said eye (22) to the edges (24a, 24b) of said notch (24).

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