Patent Publication Number: US-4369815-A

Title: Device for coupling a heddle frame to vertically reciprocating drive bars

Description:
The invention relates to a device for coupling heddle frames to vertically reciprocating drive bars. 
     An important procedure in weaving is the coupling of the heddle frames of a loom to the drive mechanism in order to ensure the shedding of the loom. Each individual heddle frame therefore must be provided with its own separate connection to the drive mechanism by means of drive bars, for instance to a dobby. Many appropriate designs are known. As a rule, the drive bars engage the lower beam of a heddle frame. 
     In known devices of this kind, the ends of the drive bars are individually mounted into associated receiving fittings at the heddle frame. When a number of frames are used in a loom, this model has the drawback of a long set-up time. Furthermore, assembly requires a certain mounting play for elements with the coupling location at the bearing of the drive bars, whereby the bearings may be worn out and undesired oscillation of the heddle frames may result. 
     Another known means for coupling the drive bars is disclosed in German Offenlegungsschrift No. 2,656,380, in that the drive bars are designed as claws, the two elastic bar parts permitting spreading by rotating a lever passing transversely through all the drive bars for the purpose of coupling. Due to the elastic connection of the claws, it is questionable as regards this design whether a reliable force-transmission free of play can be achieved. 
     These drawbacks for the first time are eliminated in part by the device disclosed in German Auslegeschrift No. 2,609,964. This is accomplished in that a first coupling component is provided at a beam of the heddle frame and a second coupling component at the drive bar. One of the drive components is provided with a catch inserted between two wall parts of the other coupling component. The two wall parts are a part of a sleeve-shaped component and form a channel into which the catch means can be inserted from above. The catch means is made to engage a claw shaped or toothed coupling component inside the sleeve by displacing the heddle frame sideways. There is no special locking of the parts mutually engaged, rather, it is the sideways guidance of the heddle frame in the machine together with drive bars also guided sideways in the loom which must ensure the coupling. While rapid coupling between the heddle frame and the associated drive bars is achieved in this manner, the drive bars must be appropriately supported or fixed in position to absorb the coupling forces, whereby the cited special guide means and additional crankrod-like coupling members between the drive bars and direction-changing levers of the drive mechanism becomes necessary. The high cost in construction thus resulting entails high financial costs, and the additional transmission members furthermore tend to oscillate. 
     The present invention presupposes devices of the last-cited kind, that is, couplings with one coupling part at the heddle frame and one coupling part at the drive bar, one of these coupling parts comprising a driver which can be inserted between two parallel walls of the other coupling part. The basic object is to create a coupling between the heddle frame and the drive bar that will ensure an easily handled and play-free connection, and that will consist of simple, easily manufactured parts. 
     The problem is solved by the invention in that: 
     (a) the driver is designed as a hook-shaped element with wedging surfaces extending transversely to the main direction of force of the drive bars and diverging toward the hook opening, 
     (b) a shaped piece receiving the hook-shaped element and provided with corresponding mating wedging surfaces is supported between the wall parts so as to be rotatable in a restricted manner, and 
     (c) the coupling member mounted to the drive bar is pivotal together with the bar in the plane of the heddle frame in order to engage the other coupling member, and can be locked in that position. 
     The diverging partial surfaces extending transversely to the main direction of the force ensure that when the two coupling parts are pivoted inwardly and together with the rotatable shaped piece, there will be play-free transmission of force from the drive bar to the heddle frame. The actual rotational support mandatory for operation is provided in the shaped piece itself. Therefore, the crankrod-shaped coupling member that is required in the cited previously known coupling means is eliminated in this case. 
     In a further design of the invention, the shaped piece also comprises another wedging surface extending approximately parallel to the main direction of the force and preferably even with a curved path. Together with a spring-loaded locking pawl mounted at the other coupling part, the wedging surfaces of the two coupling parts are so clamped mutually that clamping transversely to the main direction of the force is ensured and no adverse play is present between the coupling parts. 
     Another advantage of the device of the invention is that when pivoting the drive bars into the frame fittings, the locking pawls latch automatically and therefore manipulation of the individual coupling components is eliminated, whereby operation is substantially facilitated. The unlocking takes place simultaneously for all heddle frames by means of a slider passing transversely through a cut-out in the receiving fittings, the pawls being opened and the drive bars being released. Obviously, individual unlocking is possible in addition. 
     To ensure that the shaped piece at the one coupling part can be reliably inserted into the hook-shaped element at the other coupling part, provision is made for a stop or similar component, whereby the range of rotation of the shaped piece is restricted to the scope required for active operation. 
     Regarding the manufacturing cost of the device of the invention, the low number of simple individual parts results in low costs. Special parts to hold or guide the drive bars during the coupling process are not required. 
     It is immaterial to the essence of the invention which coupling part is associated to the heddle frame. For instance, the first coupling part can be mounted together with the hook-shaped element to a beam of the heddle frame, and the shaped piece of the second coupling part can be mounted rotatably to the drive bar or vice-versa. The number of required components and the coupling process itself remain unchanged. The quality of the drive connections so established also remains unaffected. 
    
    
     An illustrative embodiment of the invention is described below in relation to the drawing, in which: 
     FIG. 1 is a perspective of the overall device, and 
     FIG. 2 is a variation of the device, 
    
    
     The drawing shows only the coupling parts themselves and for the sake of clarity, their arrangement within a loom is omitted. The beam of a heddle frame is denoted by 6. To this beam is mounted the first coupling part 1a, which is designed like a hook with two wedging surfaces 1c and 1d. These two wedging surfaces run approximately transversely to the main direction 5 of the force and diverge with respect to the direction of the hook. The hook opening points in the direction of the heddle frame beam. As a matching component for the first coupling part, the second coupling part is mounted to a drive bar 4a. The second coupling part is composed of two wall parts 4c which extend parallel to and in extension of the drive bar 4a. For the sake of clarity, one of the wall parts is shown partially broken away. A shaped piece 2a is rotatably supported between the two wall parts. The support is indicated by the bearing ring 2b. The shaped piece 2a has wedging surfaces 2c and 2d corresponding to the wedging surfaces 1c and 1d of the hook-shaped element. The coupling motion of the two coupling parts is indicated by the dot-dash lines between the hook 1a and the shaped piece 2a. The coupling itself takes place for instance by pivoting the drive bar 4a into the coupling part, held fixed, of the heddle frame 6. 
     After the two coupling parts 1a and 2a are joined, these two components are automatically locked by a locking pawl 3a. The locking pawl 3a is spring-loaded as indicated by the spring 3b. The locking pawl 3a together with a further wedging surface 2e acts on the shaped piece 2a. The wedging surface 2e runs about parallel to the main direction 5 of the force of the drive bar. This wedging surface instead of being straight also can be curved toward the locking pawl 3a, in a concave manner. The centers of rotation and curvature of the locking pawl 3a and wedging surface 2e respectively are different, so that these two components provide clamping of the first coupling part 1a to the shaped piece 2a and play-free seating in the main direction 5 of the force. No securing pin or connecting pin passing through the device is at all required. 
     In order that there be no difficulties when the two coupling parts are coupled, the rotation of the shaped piece 2a about the bearing 2b is limited. To that end a recess 2f is provided in the shaped piece 2a and a pin 4b is provided as a stop means between the two wall parts 4c. The faces of the recess 2f together with the pin 4b limit the rotation of the shaped piece 2a to that range required for the functioning of the drive bar 4a during operation. 
     A passage 1b is provided at the hook-shaped element 1a to unlock the two coupling parts. Part of the locking pawl 3a, for instance the surmounting arm 3c, in the locked position covers the passage 1b. To unlock, a slide means 7 with a tapered end is introduced into the passage 1b. In this process, the slide means displaces the arm 3c of the locking pawl 3a and thus unlocks it. When all the heddle frames 6 of a loom are at the same height and all the fittings are aligned with their passages 1b, all the frames can be unlocked together. The unlocking of course can also take place in a variation of the same principle. Thus, in lieu of the passage 1b acting as a guide means for the slider 7, a guide means for the slider, for instance in the form of a protruding beak or the like, may be provided at the hook-shaped element 1a at the other coupling part, for instance at the drive bar 4a or at the wall parts 4c. 
     It is equally feasible to simultaneously apply all the coupling parts to all the heddle frames, or to separate the coupling parts, for instance by actuation bars similar to the slide means 7 and passing transversely through the set of all the heddle frames, by simultaneously pivoting for instance all the drive bars 4a; this variation is not shown in further detail. 
     FIG. 2 is a sketch of the basic principle of the invention, except that in this case, there is the difference of interchanging the arrangement of the two coupling parts 1a and 2a at the heddle frame 6 and drive bar 4a respectively compared to the embodiment of FIG. 1. 
     It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.