Methods and designs for balancing a stranded termination assembly
Pat. 10,718,405 U.S. class 1/1 Int. class F16G 11/12
Inventor: Richard Campbell, Havana, FL.
Assignee: Bright Technologies, LLC., Havana, FL.
This patent presents devices and methods for loading a cable in order to create a desired distribution of the load among the cable’s constituent strands. Strand terminations are applied to many — and possibly all of — the cable’s strands. The ultimate goal is to connect the strand terminations to a collector in order to create an overall cable termination. The relationship between each strand termination and the collector is allowed to “float” using the inventive process while the cable is tensioned and an appropriate spatial relationship between each strand tensioner and the collector is determined. Once the appropriate relationship is found, it is configured to be repeatable (such as by recording its position for later application to the same or similar collector).
Figure 8 shows an exemplary device used to gather all the strands into a unified whole and thereby create an overall cable termination.
Collector 34 includes twelve receivers 38, each of which is configured to connect to a single strand termination (In other embodiments a receiver may be configured to connect to multiple strand terminations). Collector 34 typically includes some type of load-transferring feature designed to transfer a load from the collector to some external element.
Loading flange 36 is a simple example of a load-transferring feature. The collector in this example is very simplistic and is unlikely to represent a design that would actually be used. However, it does serve well to clearly illustrate the inventive features.
Figure 9 shows an exemplary connection between a termination on a strand and the collector.
Loading stud 24 is passed through opening 46 and through receiver 38 in collector 34. Receiver 38 includes a hemispherical concave portion sized to accept hemi bearing 44. Hemi bearing 44 and receiver 38 form a ball-and-socket connection that allows the termination to rotate with respect to collector 34. This is a sophisticated type of connection that won’t be included in many embodiments. Many embodiments will simply use a washer bearing against a flat surface on collector 34. Still other embodiments won’t use a threaded stud and will instead simply mate two surfaces together to make the connection.
Nut 40 can be selectively tightened on loading stud 24 (the threads are not shown in the view) in order to urge washer 42 against hemi bearing 44 and hemi bearing 44 against receiver 38. To apply the inventive method, collector 34 is ordinarily placed in a loading fixture that holds it in position. The far end of the cable to which the strand belongs is likewise held in place (such as by winding it around a capstan or some other means, such as applying an overall cable termination to the far end). A substantial tensile load is then applied to the cable as a whole. Those skilled in the art will then appreciate that by tightening or loosening nut 40 a user can fine tune the tension on the particular strand to which loading stud 24 is attached (as well as its position with respect to collector 34). The ball-and-socket connection in this embodiment allows the strand termination to align itself with the strand during this process.
Figure 10 shows an assembly of collector 34 and all twelve strands.
The reader will observe that twelve loading studs 24 are in position and a nut 40 is connected to each stud (The loading studs 24 shown in figure 10 are longer than depicted in figure 9 in order to give an additional range of adjustment. Also — the threads on the exterior surface of the loading studs are again omitted for purposes of visual clarity). This view illustrates the advantage of including a ball-and-socket connection in some of the embodiments. As each strand emerges from the cable’s braided construction it assumes a particular angle with respect to the collector. Some diverge more than others, and the ball-and-socket connection accommodates this divergence. Of course, one could carefully determine a fixed angle to use for each strand. However, this is difficult as cable construction varies even within the same braiding scheme.
The ball-and-socket connection should properly be viewed as one example among many possible connection types. The reader is referred to commonly-owned U.S. Pat. No. 8,371,015 for additional examples regarding the application of an attachment to a sub-component of a larger cable. The term “collector” in this context should be viewed broadly as anything that is used to collect a tensile load from two or more strand terminations. It may be a unified piece as shown but may also be an assembly of multiple pieces. Further, a “stand-in” collector may be used to pre-load the cable and adjust each of the strand terminations (as described subsequently) and the strand terminations may ultimately be connected to an entirely different collector.
It is not common for a user to take an assembly for a large cable such as shown in figure 10 and place it into service without pre-loading the assembly and testing it. It is important to pre-load the assembly to settle the strands and other components into a stable configuration before the cable is placed into service. In this context it is desirable to know a particular cable’s maximum working load in the service environment it is destined to enter. The pre-load process might apply a tension to the cable that is equal to 100% or even as much as 150% of the expected maximum working load.
While most large cables are pre-loaded as a whole, the present invention seeks to pre-load the cable at the strand level and manipulate the strand termination to collector connections in order to create a desired apportionment of the overall load among the constituent strands. Without careful preloading a large cable assembly will very likely have an uneven distribution of load to each individual strand. The inventive process significantly reduces this phenomenon.
One could use the configuration of figure 10 to progressively tighten all twelve nuts and thereby place an initial load on the cable. Such a process would be unlikely to produce an optimal result, however. The present invention obtains advantages by individually applying tension to the strands in a large, multi-stranded cable.