HEALD FRAME FOR WEAVING LOOMS OF ASYMMETRICAL CONFIGURATION

Abstract: In a heald frame for weaving looms, wherein the two heald slide bars consist of standard elongated sections, the lower heald slide bar (5) is formed of an elongated section of width smaller than that of the elongated section forming the upper heald slidebar (6).

Description: The present invention concerns a heald frame for weaving looms characterized by an extremely simple structure, the asymmetrical configuration of which has proved to be surprisingly advantageous. It is known that, in weaving looms, the problem arises of giving to the heald frames a structure apt to guarantee, without any excessive weights, a rigid behaviour of such frames in dynamic conditions. In substance, it is necessary to avoid, or anyhow reduce to a minimum, the relative strains which, in dynamic conditions, tend to produce themselves between the heald slide bars forming each frame (generally, elongated extruded sections), so as to reduce the dynamic flexural component which causes the breaking of the stitches mounted on the frames. In the past, said problem has been solved by inserting an intermediate tie rod connecting the two heald slide bars of the frame, so as to keep the distance between them constant during the working of the loom, or by stiffening the structure of the frame through increase of the moment of inertia of the heald slide bars, or finally by using, to form the heald slide bars, special composite materials of high rigidity and low weight. The first two of these solutions have besides proved to be very scarcely practical, particularly as they create undesired bulks, they can cause interferences with the warp yarns, and they considerably increase the mass and thus the inertias of the heald frames, while the third one involves excessive costs, taking into account the specific field of application. It is also known, from CH-A-335 006, to realize a heald frame for weaving looms with the lower heald slide bar - onto which act the heald frame control members - formed of an elongated section of width greater than the width of the elongated section forming the upper heald slide bar of the frame, which is not subjected to strains. Also this heald frame structure does not solve, however, the problem considered heretofore, as it is not apt to modify the dynamic working conditions of the heald frame. The present invention now proposes instead an original and fully unexpected solution to the above problem, by giving to the heald frames a configuration which guarantees an extremely advantageous behaviour of such frames in respect of the strains in dynamic conditions. In substance, the present invention concerns a heald frame for weaving looms, of the type wherein the two heald slide bars consist of standard elongated sections, characterized in that the lower heald slide bar onto which act the members controlling the motion of the heald frame is formed of an elongated section of width smaller than that of the elongated section forming the upper heald slide bar. Preferably, in practice, the first (lower) of said heald slide bars is formed from a standard type extruded section, 96 mm wide, while the second (upper) of said heald frame slide bars is formed from a standard type extruded section, 120 mm wide. The invention is now described in further detail, with reference to the accompanying drawing, which shows an embodiment of the heald frame for weaving looms according to the invention, as compared to the known type heald frames. In said drawing: Figs. 1 and 2 are front views showing a first and a second type of conventional heald frame; and Fig. 3 is a front view of the heald frame according to the invention. With reference to the drawing, it can be seen how the conventional heald frames have a symmetrical configuration, being formed by a pair of identical heald slide bars consisting of elongated narrow sections 1 and 2 (fig. 1), for example of the standard type having a width of 96 mm, or of elongated wide sections 3 and 4 (fig. 2), for example of the standard type having a width of 120 mm. These heald frames have the drawbacks already described heretofore. The heald frame according to the invention is instead formed with the asymmetrical configuration shown in fig. 3, by using - to form the lower heald slide bar meant to be connected to the loom, and thus the bar onto which act the members controlling the motion of the heald frame - a standard type elongated narrow section 5, having a width of 96 mm, and by instead using - to form the upper heald slide bar - a standard type elongated wide section 6, having a width of 120 mm. With this special asymmetrical configuration - quite unforeseeable since, going by intuition, one would have thought to obtain an advantage by extending the width of the lower heald slide bar, rather than that of the upper one - the already considered problems are efficiently solved. Surprisingly in fact, the dynamic behaviour of the frames is thereby considerably improved - as has been experimentally proved - without giving rise to weight and bulk increases apt to cause inconveniences. This behaviour can be explained by observing that, while in the case of conventional symmetric heald frames, the strains in both heald slide bars are generally directed in different senses, as well as being of different intensity, in the case of the asymmetrical heald frame according to the invention, both heald slide bars flect in the same sense, even if to a slightly different extent one in respect of the other: in this way, the frame behaves dynamically, keeping substantially unvaried distances between corresponding points of the two heald slide bars (no or practically no relative flexure); the breaking of the frame stitches, which easily occurs in the case of conventional frames - unless their structure is strengthened - is thus prevented in the frame according to the invention, without having to resort to the disadvantageous devices of known technique, with evident considerable progress. It should actually be noted that the proposed solution, as well as being extremely economic, in that it uses interchangeable parts which are already widely used in this field of technique, also keeps the weights and inertias low, in that it strengthens the structure of only one of the heald slide bars of the frame and, above all, it does not introduce any kind of supplementary bulks. It has also been found that the heald frame according to the invention behaves particularly well at the high speeds, even in the case of working with unbalanced weaves, as indispensable in certain types of weaving.

Claims: Heald frame for weaving looms - of the type comprising two heald slide bars (5, 6) formed by elongated sections of different width, onto the lower of said bars (5) acting the members which control the vertical up and down motion of the heald frame - characterized in that the lower heald slide bar (5), onto which said control members act, is formed of an elongated section of width smaller than the width of the elongated section forming the upper heald slide bar (6). Heald frame as in claim 1), wherein said lower heald slide bar (5) is formed from a standard type extruded section, 96 mm wide, while said upper heald slide bar (6) is formed from a standard type extruded section, 120 mm wide.

Inventors: FANTONI, PAOLO, PEZZOLI, LUIGI
Applicants: VAMATEX S.P.A.
Application year: 1989
Main classification: D03C9
IPC codes: D03C9