EP0274455B1 - Negative dobby machines wth oscillating swing levers - Google Patents

Description

The present invention relates to negative dobbies of the oscillating balance type, intended for controlling heald frames on weaving machines.

We know that in the dobbies of this type (see FR-A 2 565 605) the actuation of each heald frame is operated against springs or other elastic means which tend to recall the frame envisaged in one of the two ends of its alternative vertical stroke. As illustrated schematically in Figure 1 of the drawing appended hereto, which figure is a schematic cross section of a traditional dobby, each frame C is coupled by a cable and / or a pulling arm 1 to a suspension lever 2 articulated and 3 on the frame 4 of the dobby. A connecting rod 5 connects each lever 2 to a balance-carrying lever 6, the set of levers 6 being pivotally supported on a common axis 7; each lever 6 is equipped at its free end with a balance 8 provided at its ends with articulated hooks 9.

To oscillate each balance 8 around its hinge axis 10 carried by the corresponding lever 6, there is provided an actuating mechanism comprising two cross members 11 which are carried by two lateral rockers 12 so as to come to bear against the heel of the hooks 9. Any actuation mechanism, for example formed by arms 13 coupled to the rockers 12 and wedged eccentrically on a transverse shaft 14, impart to said rockers a continuous oscillating movement around their fixed pivot 15.

In conventional constructions, each of the two articulated hooks 9 carried by each balance 8 is profiled so as to cooperate with a corresponding retaining member 16 in the form of a hook, which swivels around a common axis 17 under the effect of a reading device 18 of the peg or perforated paper type, which device contains the weaving program for the production of the envisaged fabric.

This embodiment has significant drawbacks from a practical point of view.

It will first be observed that, as a result of the respective positioning of the parts 9 and 16 of each pair, joined to the orientation of the attachment faces of said parts, the latter work in bending, so that to avoid any deflection with regard to the very significant efforts to which said parts are subjected in operation, it is necessary to provide large sections which obviously increase the masses that the reading device 18 must operate. Therefore, the springs associated with the hooks 16 (referenced 16a in Fig. 1) or incorporated into the device 18 must be provided more powerful; simultaneously the selection time (i.e. the operating rhythm of the reading device) must be extended, which reduces the speed of the dobby.

In addition and as illustrated more precisely in Figure 2 of the accompanying drawing, which figure shows on a large scale the situation with regard to the lower hook of one of the scales 8 of a traditional dobby, the unfavorable trajectory of the parts 9 and 16 requires the provision of larger declawing strokes which slow down the speed of operation of the dobby. Indeed, as regards the horizontal displacement of each hook 9, declawing, that is to say the distance that said hook must make beyond the hooked position to allow its release from the corresponding hook 16, is equal, not to the value d1 corresponding to the only functional clearance, but to the value d2 owing to the obliquity necessarily imparted to the bearing faces.

This increase in the declawing stroke must be taken into account both at the level of the actuation mechanism 13-14 associated with the flip-flops 12 and at that of the reading device 18, so that it influences unfavorable to the speed of operation of the dobby.

It is to all of these drawbacks that the present invention intends to remedy, which relates to the dobby defined in claim 1.

In fact, the invention essentially consists in constituting the pivoting retaining member associated with each of the two hooks carried by each balance, in the form of a lock disposed between the bearing face of the hook in question and the hinge pin. of the latter on the corresponding scale.

As illustrated in fig. 3 of the accompanying drawing, which figure is a cross section similar to that of FIG. 1, but representing on a larger scale the part modified in accordance with the invention, each retaining lock is advantageously formed by a reference lever 19, pivotally carried on one or the other of two common transverse axes 20, similar to axes 17 of the conventional construction according to FIG. 1. This lever 19 has two radial arms, one of which is coupled by an independent pusher 21 to the reading device 22 of the dobby, while the other is profiled at its free end to cooperate with the bearing face provided in the corresponding hook, referenced 23, of the balance 8 envisaged.

Fig. 4 shows on a still larger scale the lower hook 23 of one of the scales and the retaining latch 19 which is associated with it. The pivot axis 20 which carries each latch 19 being disposed between the bearing face 23a of the hook 23 and the pivot axis 24 of said hook on the scale 8, this latch works in compression, it can have a very reduced mass compared to that of conventional hooks 16 working in bending.

In accordance with a particularly advantageous arrangement of the invention, things are arranged so that each common axis 20 is located, not strictly on the straight line which connects the bearing face 23a to the pivot or axis 24, but to slightly offset outwardly from said straight line. This offset generates a torque which tends to rotate the lock in the direction indicated by the arrow F, which has the effect of applying the internal face of the hook 23, preferably provided for this purpose with a boss 23b against the axis. common 20; note that to ensure a better support of the hook 23, the latch 19 is partially indented around the axis 20.

This support position is balanced, so that the stable equilibrium position is thus kept permanently.

• - alors que dans la construction classique, compte tenu de l'inclinaison de la face d'appui 9a par rapport à la ligne de force X-Y passant obligatoirement par les axes 24 et 17, la trajectoire T1 du bec de crochet 16 se rapproche de la face d'appui précitée, en obligeant donc à augmenter le jeu de dégriffage illustré en d2 en fig. 2,
• - dans le cas du verrou 19 dont l'axe d'articulation 20 est situé entre la face d'appui 23a et l'axe 24, la trajectoire T2 est substantiellement tangente à ladite face 23a en autorisant de la sorte un jeu de dégriffage minimal.

Whichever solution is adopted, it should be noted that, as illustrated in fig. 5, on which we have simultaneously shown the conventional construction (broken line) and the construction according to the invention, the trajectory of the latches 19 during their rotation is much more favorable than in the case of the previous construction and allows this reduces the declawing clearance, allowing an increase in the speed of operation of the dobby without increasing the risk of declawing faults. We actually see:

• - whereas in conventional construction, taking into account the inclination of the bearing face 9a with respect to the line of force XY necessarily passing through the axes 24 and 17, the trajectory T1 of the hook beak 16 approaches the abovementioned bearing face, thus forcing to increase the declawing clearance illustrated in d2 in fig. 2,
• - In the case of the latch 19, the hinge axis 20 of which is situated between the bearing face 23a and the axis 24, the path T2 is substantially tangent to said face 23a, thereby allowing minimal declawing play .

Returning to the structural plane, it will be observed that in the solution envisaged in FIG. 3, the control of each latch 19 is obtained using an independent pusher 21 actuated by the reading device 22. It is however possible to adopt the actuation mode illustrated diagrammatically in FIG. 6 of the drawing, using a reading device 25 which comprises for each balance 8 a single pusher 26, possibly doubled by an identical pusher intended for reverse gear. The free end of each pusher 26 is coupled to the midpoint of a beam 27 which is articulated with the two retaining latches 19 associated with the envisaged balance. Springs or other elastic means 28 tend to hold each latch 19 applied against a fixed stop 29, while two movable stops 30 are provided carried by a balance 31 which a central shaft 32 drives with a continuous oscillating movement, in synchronism with the oscillating movement of the above-mentioned rockers 12. It will be noted that the stops 29 and 30 are common to all of the locks 19 of the dobby.

It is understood that when one of the stops 30 applies the actuating arm or tail of one of the latches 19 against the corresponding fixed stop 29, the pusher 26 can, if the program of the device 25 so provides, push back the flail 27 which tilts and comes to pivot the opposite latch, which is at this moment free to move angularly as a result of the spaced position of the stop 30 which is associated with it.

It should be observed that each of the two axes 20 on which the latches 19 of each row are articulated is preferably mounted in the teeth of a support 33 in the form of a comb, as shown in FIG. 3. Each axis 20 is thus perfectly supported and can in fact have a reduced diameter despite the importance of the forces exerted on it. Furthermore, the bottom of the teeth of the supports or combs 33 is suitable for forming a guide for the angular displacement of the spouts 23 in the case where the cross member 11 associated with the latter would not bear perfectly flat against the rear heel of the spout considered.

Claims (3)

1. Negative dobby of the type incorporating swinging levers, in which each of the levers (8) is provided at its ends with articulated hooks (9, 23) adapted to cooperate with a pivoting retaining member angularly controlled by a reading device (18, 22, 25), characterized in that each pivoting retaining member is constituted by a bolt (19) disposed between the bearing face (23a) of the corresponding hook (23) and the pivot pin (24) of the latter on the lever (8) envisaged.

2. Dobby according to Claim, characterized in that each of the pins (20) which rotatably support one of the series of bolts (19) is offset laterally towards the outside with respect to the straight line joining the bearing face (23a) of each hook (23) to the pivot pin (24), so as to generate in operation a torque which tends to apply the inner face of said hook (23) against the corresponding pin (20).

3. Dobby according to either one of Claims 1 and 2, characterized in that each articulated hook (23) abuts directly against the pin (20) which rotatably bears the bolts (19).

Images