Title of Invention

A SHED-FORMING MECHANISM AND A LOOM FITTED WITH SUCH A MECHANISM

Abstract

The inventive mechanism for forming a loom comprises at least one length-adjustable and/or removable rod (3'') which is provided with a first part (33) comprising a pin (32) sliding in a tubular part (31) and means (50, 60, 62, 70) for locking said pin (32) in operating position in the tubular part (31). The inventive rod is provided with a sheath (40) whose internal volume (V41) forms a housing for receiving and centring the pin (32) with respect to the tubular part (31). Said sheath is arranged inside the tubular part (31) and holds at least one locking means (50, 70) in operating position with respect to the tubular part (31).

Full Text

1 A SHED-FORMING MECHANISM AND A LOOM FITTED WITH SUCH A MECHANISM The invention relates to a mechanism for forming the shed of a loom. It relates in particular to pulling mechanisms in which connecting rods are used for transmitting motion to heddle frames, which motion that is generated by a dobby or a positive weave mechanism. The invention also relates to a loom fitted with a mechanism of the above-specified type. In the field of forming sheds on looms, it is known to use connecting rods that couple moving drive members with vertically movable heddle frames mounted on the loom. For example, FR—A—2 836 488 discloses that a force-transmission connecting rod can comprise a tubular portion in which there is engaged an endpiece provided with an eyelet for coupling to an oscillating lever or a drive arm. In order to take account of the numerous configurations in which shed-forming mechanisms can be installed, it is also known to provide for such connecting rods to be adjustable in length, having a portion carrying an eyelet and forming a shank that is designed to be inserted and locked inside a tubular portion by using a screw that co-operates with a captive nut in the tubular portion and that exerts on the shank a pressure force against a strip that is also disposed in the shank. That approach requires retaining means to be provided inside the end of the tubular portion, both for the nut and for the strip that receives the bearing force. Such an approach also requires shank guide means to be provided to avoid interfering movements in a transverse direction perpendicular to that along which the retaining force obtained by the nut is applied. These stresses lead to an elaborate structure for the end of the tubular portion of the connecting rod, thereby increasing its cost price, but without the precision that is obtained being satisfactory, in practice. In addition, those structural arrangements can make it 2 difficult to insert the shank fully into the tubular portion, thereby leading to a minimum length for the connecting rod that cannot be shortened below a limit value. The invention seeks more particularly to remedy those drawbacks by proposing a novel shed-forming mechanism in which the connecting rod(s) can easily be adjusted in length depending on the configuration of the loom, while being of a cost price that remains economic, and while the accuracy with which connecting rod lengths can be adjusted and the reliability of the connecting rod(s) comply with the requirements of the technical field and enable the loom to operate at high speed. To this end, the invention provides a shed-forming mechanism for a loom, the mechanism comprising at least one connecting rod that is adjustable in length and/or removable, comprising a first portion provided with a shank suitable for sliding in a tubular portion, and retention means for retaining the shank in position in the tubular portion, the mechanism being characterized in that the connecting rod is fitted with a sheath having an internal volume that forms a housing for receiving and centering the rod relative to the tubular portion, the sheath being placed inside the tubular portion and serving to hold it in position relative to the tubular portion of at least one of the retention means for holding the rod in the tubular portion. By means of the invention, the sheath inserted in the end of the tubular portion of the connecting rod performs a plurality of functions, namely centering the rod relative to the tubular portion and positioning one or more retention means, while the tubular portion is smooth and without portions in relief, thus making it much easier to fabricate. According to advantageous but non-compulsory aspects, a shed-forming mechanism may incorporate one or 3 more of the fowling characteristics taken in any technically feasible combination: . the sheath is elastically deformable, at least in part; • the sheath carries or forms at least one member for centering said tubular portion relative to the inside surface; the member is advantageously constituted by an elastically deformable tab formed integrally with a portion of said sheath forming the above-mentioned housing for receiving and centering the shank, this tab being designed to bear against the inside surface of the tubular portion; • the sheath is made of synthetic material, preferably by injection molding, in particular it is made of injection-molded plastics material; • the above-mentioned retention means comprise a strip retained by said sheath in said tubular portion by co-operating shapes, said strip being designed to receive said shank bearing thereagainst. Under such circumstances, the face of said strip that is to receive the shank pressed thereagainst and the face of said strip that faces towards the inside surface of the tubular portion are provided with portions in relief for increasing grip between said strip and the shank and between said strip and the tubular portion. These portions in relief preferably comprise teeth that extend in a direction that is generally transverse relative to a longitudinal axis of the tubular portion. In a variant, these portions in relief may be spikes, crossed grooves, knurling, etc. It is also possible to provide for the hardness of the portions in relief to be greater than the surface hardness of the shank and/or of the tubular portion, at least in those zones of the rod and the tubular portion that are to come into contact with the portions in relief. This aspect of the invention serves to increase the coefficient of friction between the strip and the shank and/or between the strip and the tubular 4 portion, by the portions in relief making micro-indentations in the surfaces of the shank and/of the tubular portion. This makes it possible to transmit high loads using the mechanism of the invention; • the retention means comprise a clamp mounted on the sheath and/or the tubular portion, together with a screw suitable for exerting a force on the clamp and through an opening formed in the sheath, the force serving to block the shank and being directed along a direction that extends generally transversely relative to a longitudinal axis of the tubular portion. The invention also provides a loom fitted with a shed-forming mechanism as described above. Such a loom is easier to install and to operate than a prior art loom. In particular, it is easier to adjust the shed-forming mechanism. The invention can be better understood and other advantages thereof appear more clearly in the light of the following description of an embodiment of a mechanism applying the principle of the invention, given solely by way of example and described with reference to the accompanying drawings, in which: • Figure 1 is a diagram showing the principle of a loom in accordance with the invention; • Figure 2 is a principal longitudinal section view of one of the connecting rods of the Figure 1 loom; • Figure 3 is a view analogous to Figure 2 showing a connecting rod being assembled; and • Figure 4 is an exploded perspective view of a portion of the connecting rod of Figures 2 and 3. In Figure 1, a dobby 1 serves to drive a plurality of heddle frames of a loom M, only one heddle frame being shown under the reference 2. The frame 2 is driven with reciprocating vertical motion F1. To do this, an actuator arm la of the dobby 1 is coupled, by an obliquely-extending connecting rod 3, to a first oscillating lever 4, itself connected by a connecting rod 3' to a second 5 oscillating lever 4. The two levers 4 and 4' are hinged about respective axes 5 and 5' that are stationary relative to the structure 6 of the loom. Each of the levers 4 and 4' is connected to the frame 2 by connecting rods 3". As many arms la and sets of connecting rods 3, 3', and 3" and of levers 4 and 4 are provided as there are heddle frames to be driven. A connecting rod 3" is shown in Figures 2 to 4, and comprises a tubular portion 31 designed to receive in its inside volume V31 a shank 32 belonging to an elongate part 33 that defines an eyelet 34 for coupling to the frame 2. The portion 31 defines an eyelet 35 for coupling the connecting rod 3 to the lever 4. The connecting rod 3" is adjustable in length and removable. A sheath 40 is designed to be inserted in the end zone V31 of the volume V31, i.e. the portion of said volume that is closest to the end 36 of the portion 31 remote from the eyelet 35, the end through which the shank 32 penetrates into the volume V31. The sheath 40 is made by injection molding a synthetic material, in particular polyamide or polyacetal, and as a result it presents a certain amount of elasticity. The sheath is a single piece and its main body 41 defines a through opening that is elongate and of transverse dimensions that match the cross-section of the shank 32 and that enable said shank to be guided in translation with small clearance while it is being inserted into the opening, with the sheath 40 being mounted in the portion 31. The inside volume V41 of the central opening in the body 41 constitutes a housing for receiving and guiding the shank 32 while it is being put into place, and after it has been put into place. The sheath 40 is also provided with a collar 42 that comes to bear against the end 36 of the portion 31 in 6 order to limit the insertion movement of the sheath 40 into the volume V31 in the direction of arrow F2. The overall cross-section of the portion 31 is rectangular with its long sides being referenced 311 and 312 and its short sides 313 and 314. The transverse dimensions of the sheath 40 are designed to enable the sheath to be centered by pressing against the inside surface 37 of the portion 31. To do this, the sheath 40 is provided with two elastically deformable tabs 43 and 44 that are formed integrally with the body 41 and that are designed to bear respectively against the short sides 313 and 314, thus enabling the middle axis X41 of the housing V41 to be maintained generally parallel with the longitudinal axis X31-X'31 of the portion 31. The width l40 of the sheath 40 is substantially equal to the distance d31 between the long sides 311 and 312, such that the sheath is held laterally pressed against the inside faces of these sides when it is inserted in the portion 31. The width of the sheath 40 is accurately fitted to the volume V31 by means of four wedges that are oblique relative to the axis X41, diverging towards the collar 42 and distributed in pairs against the side faces of the body 41, two of which are visible under reference 47 on the side face 41a of the body 41 that faces towards the observer of Figure 4. The sheath 40 is also provided with two openings 45 and 46 designed to face respectively towards the short sides 313 and 314 when the sheath 40 is in place in the portion 31. A clamp 50 is applied against the sheath 40 and comprises a first branch 51 for pressing against the outside of the side 313 when the sheath is in place in the portion 31. The clamp 50 also comprises a second branch 52 that extends generally in a direction parallel to the axis X41 and that terminates by a lip 53 extending generally perpendicularly to the branch 52. When the 7 clamp 50 is in place, its branch 52 extends in register with the opening 45 and its lip 53 is directed towards the side 313. A rectangular nut 60 is placed between the branch 52 and the side 313 and receives the shank 61 of a screw 62 that passes through a hole 38 formed in the side 313. Thus, tightening the screw 62 in the tapping 63 of the nut 60 enables the position of said screw to be controlled in a direction Y-Y' perpendicular to the axis X-X' and parallel to the sides 311 and 312. This makes it possible to exert a thrust force F3 on the branch 52 that is directed towards the side 314, this force being transmitted to the shank 32 when it is engaged in the volume V41. A strip 70 is placed in the opening 46 and its face that faces towards the volume V41 is referenced 71, and its face facing towards the side 314 is referenced 72. The faces 71 and 72 are parallel and provided with respective teeth 71a and 72a, of hardness greater than the surface hardness of the surface 37, at least in the region of the side 314 that is closest to the end 36, and also harder than the surface of the shank 32. The teeth 71a and 72a extend in a direction A-A' perpendicular to the axis X31-X'31 and to the direction Y-Y ' . The strip 70 is provided with two stubs 73 enabling it to bear against stubs 48 and 49 formed by the sheath 40, so as to prevent the strip 70 from passing through the opening 46 even though its surface 71 is exposed through the opening 4 6 and towards the volume V41 in the configuration of Figure 3, thus enabling it to receive the shank 32 pressed thereagainst under the effect of the force F3. Thus, the volume V41 constitutes a housing for receiving the shank 32, while the elements 50, 60, 62, and 70 enable the retaining force F3 to be exerted on said shank in the direction Y-Y1. 8 Under the effect of the force F3, the shank 32 is pressed firmly against the teeth 71a of the strip 70, while the teeth 72a are pressed firmly against the side 314 of the portion 31. Given the relative hardnesses of these teeth compared with the surface hardnesses of the parts 31 and 32, the teeth form micro-indentations in the facing portions, thereby significantly increasing the coefficient of friction between the parts 32 and 70, and between the parts 70 and 31, in the longitudinal direction of the parts 31 and 32, particularly since the direction A-A' is perpendicular to the axis X31-X'31. Nevertheless, good results can be obtained by replacing the teeth 71a and/or 72a by teeth that are oblique or crossed, by knurling or by spikes. The tabs 43 and 44 and wedges 47 enable the sheath 4 0 to be centered in the volume V31. They can deform elastically in order to accommodate any mis-alignment between the central axis X32-X'32 of the shank 32 and the axis X31 x 31* The length L41 of the opening in the body 41 is sufficient to guide and support the shank 32 effectively, both while it is being inserted along the direction of arrow F4 and while it is retained by the force F3. In practice, this length L41 is not less than the long dimension of the nut 60 or of the strip 70. The connecting rod 3" is assembled and adjusted in length by inserting the strip 70 partially into the opening 4 6, while the clamp 50 is hooked on the sheath 40, and the nut 60 is pressing against the branch 52. The elements 50 and 60 are held in position by the branch 51 hooking onto the sheath 40. There is no risk of the strip 70 migrating towards the volume V41 since it is retained by co-operation between the portions 48, 49, and 73. Thereafter, the sheath 40 as fitted in this way is inserted in the portion 31 in the direction of arrow F2. The screw 62 is then engaged in the tapping 63 making it impossible to lose the elements 40, 50, 60, and 70. 9 Thereafter, the shank 32 is inserted into the sheath 40 and the portion 31 in the direction of arrow F4 until the desired length is obtained for the connecting rod 3", after which the screw 62 is tightened in order to exert the retaining force F3. By loosening the screw 62 it is possible subsequently to modify the length of the connecting rod or to remove it. The tubular portion 31 is particularly simple to make and therefore inexpensive. The other connecting rods 3 and 3" of the loom M could be provided on the same principle as the connecting rods 3". In a variant, some of the connecting rods need not be adjustable in length or suitable for removal. The invention is not restricted to looms having positive dobbies, but applies to looms having negative dobbies, with the connecting rods situated above the frames, and to mechanical looms having cam mechanisms. 10 CLAIMS 1. A shed-forming mechanism for a loom, said mechanism comprising at least one connecting rod that is adjustable in length and/or removable, comprising a first portion provided with a shank suitable for sliding in a tubular portion, and retention means for retaining said shank in position in said tubular portion, the mechanism being characterized in that said connecting rod (3) is fitted with a sheath (40) having an internal volume (V41) that forms a housing for receiving and centering said rod (32) relative to said tubular portion (31), said sheath being placed inside said tubular portion and serving to hold it in position relative to said tubular portion of at least one (50, 60, 70) of said retention means. 2. A mechanism according to claim 1, characterized in that said sheath (40) is elastically deformable, at least in part. 3. A mechanism according to either preceding claim, characterized in that said sheath (40) carries or forms at least one member (43, 44, 47) for centering said tubular portion (31) relative to the inside surface (37). 4. A mechanism according to claim 3, characterized in that said member is an elastically deformable tab (43, 44) formed integrally with a portion (41) of said sheath forming said housing (V41) , said tab being designed to bear against said inside surface (37). 5. A mechanism according to any preceding claim, characterized in that said sheath (40) is made of synthetic material, preferably by injection molding. 6. A mechanism according to any preceding claim, characterized in that said retention means comprise a strip (70) retained by said sheath (40) in said tubular 11 portion (31) by co-operating shapes (48, 49, 73), said strip being designed to receive said shank (32) bearing thereagainst. 7. A mechanism according to claim 6, characterized in that the face (71) of said strip (70) that is to receive said shank (32) bearing thereagainst, and/or the face (72) of said strip facing towards the inside surface (37) of said tubular portion (31) is/are provided with portions in relief (71a, 72a) for increasing adhesion between said strip and said shank and/or said tubular portion. 8. A mechanism according to claim 7, characterized in that the hardness of said portions in relief (71a, 72a) is greater than the surface hardness of said shank (32) and of said tubular portion (31), at least in the zones of said shank and/or said tubular portion that are designed to come into contact with said portions in relief. 9. A mechanism according to any preceding claim, characterized in that said retention means comprise a clamp (50) mounted on said sheath (40) and/or said tubular portion (31), together with a screw (62) suitable for exerting a force (F3) on said clamp and through an opening (45) formed in said sheath, said force (F3) serving to block said shank and being directed along a direction (Y-Y1) that extends generally transversely relative to a longitudinal axis (X31-X'31) of said tubular portion. 10. A loom (M) fitted with a shed-forming mechanism (1- 70) according to any preceding claim.

Documents:

03378-kolnp-2006-abstract.pdf

03378-kolnp-2006-claims.pdf

03378-kolnp-2006-correspondence others-1.1.pdf

03378-kolnp-2006-correspondence others.pdf

03378-kolnp-2006-correspondence-1.2.pdf

03378-kolnp-2006-description(complete).pdf

03378-kolnp-2006-drawings.pdf

03378-kolnp-2006-form-1.pdf

03378-kolnp-2006-form-2.pdf

03378-kolnp-2006-form-26.pdf

03378-kolnp-2006-form-3.pdf

03378-kolnp-2006-form-5.pdf

03378-kolnp-2006-international publication.pdf

03378-kolnp-2006-international search authority report.pdf

03378-kolnp-2006-pct form.pdf

03378-kolnp-2006-priority document.pdf

3378-KOLNP-2006-(05-12-2011)-AMANDED CLAIMS.pdf

3378-KOLNP-2006-(05-12-2011)-CORRESPONDENCE.pdf

3378-KOLNP-2006-(05-12-2011)-FORM-13.pdf

3378-KOLNP-2006-(05-12-2011)-OTHERS.pdf

3378-KOLNP-2006-(30-07-2013)-ABSTRACT.pdf

3378-KOLNP-2006-(30-07-2013)-ANNEXURE TO FORM 3.pdf

3378-KOLNP-2006-(30-07-2013)-CORRESPONDENCE.pdf

3378-KOLNP-2006-(30-07-2013)-DESCRIPTION (COMPLETE).pdf

3378-KOLNP-2006-(30-07-2013)-DRAWINGS.pdf

3378-KOLNP-2006-(30-07-2013)-FORM-1.pdf

3378-KOLNP-2006-(30-07-2013)-FORM-2.pdf

3378-KOLNP-2006-(30-07-2013)-OTHERS.pdf

3378-KOLNP-2006-(30-07-2013)-PETITION UNER RULE 137.pdf

3378-KOLNP-2006-CORRESPONDENCE 1.1.pdf

3378-kolnp-2006-form 18.pdf

abstract-03378-kolnp-2006.jpg