Abstract:
A cable drum, having a substantially cylindrical drum body with drum walls arranged at its axial ends and a groove arrangement arranged on the drum body, enables winding of a cable in a rotational direction clockwise as well as counter-clockwise thereto. The groove arrangement has parallel areas in which the grooves are parallel to the circumferential direction and incline areas in which the grooves are slanted at an angle relative to the circumferential direction of the drum body. All grooves in the parallel areas have identical groove width. The grooves in the incline areas cross one another.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a cable drum comprising a substantially cylindrical drum body having drum walls arranged on its axial ends, and comprising a groove arrangement provided on the drum body which has at least one parallel area in which grooves extend parallel to the circumferential direction of the drum body and at least one incline area in which grooves are slanted about an angle relative to the circumferential direction of the cylindrical drum. All grooves in the parallel areas have the same groove width. 
     2. Description of the Related Art 
     From patent document GB 776,007 a cylindrical cable drum is known which has two areas with oppositely positioned grooves on its periphery, wherein the grooves are displaced relative to one another in the axial direction and have a length which is less than one half of the circumference. 
     Patent documents JP 09156887 A and JP 11263592 A disclose cable drums which have on both ends screw-shaped grooves with opposite orientation so that a cable is wound in axially opposite directions on both drum sides so that axial forces on the cable drum are reduced. 
     Patent document WO 86/01189 discloses a cable winding device with a cylindrical drum wherein the drum has first circumferential grooves at least about a portion of its periphery for receiving the innermost cable layer. Moreover, second grooves are provided which have a reduced diameter in comparison to the first grooves and which are capable of receiving an end strand which is connected to the innermost end of the cable but has a correspondingly reduced diameter. The second grooves are formed such in the base of the first grooves that the innermost cable layer is progressively unwound from the first end of the drum to the oppositely positioned second end and the end strand, after unwinding of the cable, is unwound progressively from the second end to the first end of the drum. 
     SUMMARY OF THE INVENTION 
     The invention has the object to provide a cable drum of the aforementioned kind with which a cable can be wound onto the drum in the clockwise direction as well as in a direction opposite thereto. 
     This object is solved by a cable drum of the aforementioned kind having grooves which cross one another the incline area. 
     The grooves which are crossing one another in the incline areas enable that a cable can be wound onto the drum in the clockwise direction as well as in a counter-clockwise direction. In this way, it is not necessary to provide different cable drums for different winding directions, as has been the case in the past. The cable drums according to the invention can be employed significantly more universally. 
     According to one embodiment of the invention, it is suggested that the pitch, i.e., the displacement of neighboring grooves in the longitudinal direction, matches approximately 1 to 1.1 times the diameter of the cable to be wound and that the grooves that are positioned adjacent to one another in the longitudinal direction of the cable drum contact one another. In this connection it is expedient that on the drum body two parallel areas and two incline areas are arranged. In this case, the parallel areas can have an axial displacement relative to one another which corresponds to half the pitch. In this way, for one winding of the cable about the drum a displacement is achieved which corresponds to 1 to 1.1 times the diameter of the cable so that the cable is wound tightly onto the drum. In an especially advantageous embodiment, the incline areas cover overall approximately 20% to 30% of the outer surface area of the drum body. 
     Moreover, in order to achieve a uniform winding action, it can be provided that in the parallel area filler wedges are arranged on one drum wall which prevent that a cable winding of the second cable layer wound at the drum wall is wound so as to have a diameter which is smaller than that of the second cable layer. A further embodiment of the invention provides that on a second drum wall a ramp wedge is provided which lifts the cable from a first cable layer onto a second cable layer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the invention will be explained in the following in more detail with the aid of the drawing. It is shown in: 
     FIG. 1 a schematic illustration of a cable drum; 
     FIG. 2 a developed view of a groove arrangement of the drum body of the cable drum of FIG. 1; 
     FIG. 3 the developed view of FIG. 2 with the cable path for a first rotational direction; and 
     FIG. 4 the developed view of FIG. 2 with the cable path for a second rotational direction. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a schematic illustration of a cable drum  1  with a drum axis  22 , a drum body  21 , an upper drum wall  12  and a lower drum wall  13 . A cable can be wound onto the drum body  21  of the cable drum  1 . 
     In FIG. 2, a developed view of the drum body  21  of the cable drum  1  is illustrated wherein the cable body  21  is provided with a groove arrangement. The surface of the drum body  21  in the circumferential direction is divided parallel to the drum axis  22  into four areas: two parallel areas  2 ,  3  in which grooves  4  and  5  extend parallel to the drum walls  12  and  13  and two incline areas  6  and  7 . The incline areas  6  and  7  have grooves  8  and  10  which are slanted at a positive angle to the horizontal and grooves  9  and  11  which are slanted at a negative angle to the horizontal. The parallel areas  2  and  3  cover approximately 35% to 40%, respectively, of the surface area of the drum body  21  and the incline areas  6  and  7  cover approximately 10% to 15%, respectively. 
     The grooves  4  and  5  in the parallel areas  2  and  3  have a width a. The pitch c by which the neighboring grooves  4 ,  5 ,  8 ,  9 ,  10 , and  11  are displaced relative to one another in the longitudinal direction of the cable drum  1  matches approximately 1 to 1.1 times the diameter of the cable to be wound. Since the neighboring grooves  4 ,  5  contact or touch one another in the longitudinal direction of the cable drum  1  within the parallel areas  2 ,  3 , the groove width a corresponds to the pitch c. The parallel areas  2 ,  3  are displaced in the axial direction by an axial displacement b which matches half the pitch c. The grooves  8 ,  9 ,  10 , and  11  are slanted such that they adjoin with one end the grooves  4  of the parallel area  2  and with the other end adjoin the grooves  5  of the parallel area  3 . The grooves  8  and  9  cross one another in the incline area  6  and the grooves  10  and  11  cross one another in the incline area  7 , respectively. As a result of the axial displacement b of the parallel areas  2  and  3  relative to one another, the grooves  4  adjoin directly the upper drum wall  12  and the lower drum wall  13  while a spacing of the size of the displacement b is provided between the grooves  5  and the upper drum wall  12  and the lower drum wall  13 . 
     At the location of this spacing, a filler wedge  14  is arranged in the parallel area  2  and a filler wedge  15  is arranged in the parallel area  3  at the upper drum wall  12 . The filler wedge  14  has a width which matches the pitch c and the filler wedge  15  has a width which matches the axial displacement b. A ramp wedge  16  is arranged on the lower drum wall  13  and extends from the incline area  7  via the parallel area  3  to the incline area  6 . The function of the filler wedges  14  and  15  and of the ramp wedge  16  will be explained infra. 
     When winding the cable in a direction from the left to the right of FIG. 3, the cable extends along the cable path  18  from the cable inlet opening  17 , where the end of the cable secured on the cable drum  1  exits from the interior of the drum body  21 , via an upper groove  4  to the incline area  7 , from there in a groove  11  to a groove  5 , which is displaced downwardly by the displacement b, and via a groove  9  to the parallel area  2  where, after having been wound once about the drum body  21 , it extends in a second groove  4  displaced downwardly by the pitch c relative to the upper groove  4 . All further windings of the cable extend along a corresponding downwardly displaced cable path and thus form the first cable layer. 
     When the cable has reached the lowermost groove  4 , it is lifted in the incline area  7  by the ramp wedge  16  onto a diameter which is larger by approximately twice the diameter of the cable so that a second cable layer can be wound onto the first cable layer. The second cable layer is wound in a direction counter to that of the first cable layer from the lower drum wall  13  toward the upper drum wall  12 . As soon as the cable has reached the upper drum wall  12 , the filler wedges  14  and  15  prevent that the cable can be wound into the spacing between the drum wall  12  and the upper cable winding of the first layer. 
     In FIG. 4 a cable path  20  is illustrated which results when winding the cable in the opposite rotational direction, i.e., when winding the cable in FIG. 4 from the right to the left. The cable extends from the cable inlet opening  19  via a groove  4  to groove  8  in the incline area  6 , from there in a groove  5  in the parallel area  3  via a groove  10  in the incline area  7  to the parallel area  2  where, after having being wound once about the drum body  21 , it extends in a groove  4  below the first groove  4 . 
     As a result of the mirror-symmetrical configuration of the filler wedges  14  and  15  and of the ramp wedge  16  relative to the center of the parallel area  2  in which the inlet openings  17  and  19  are located, the function of the wedges is ensured for both rotational directions. 
     In another embodiment, the inlet openings  17  and  19  can be arranged in the upper drum wall  12  in the parallel area  2  wherein the inlet opening  17  adjoins the incline area  6  and the inlet opening  19  adjoins the incline area  7 . With this embodiment, the filler wedge  14  is no longer needed because the cable rests against the upper drum wall  12  over the entire width of the parallel area  2 . 
     While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.