Method for terminating a twisted pair screened cable

Abstract: A coaxial connector has a preformed intermediate socket contact assembly having crimping buckets for receiving bared conductor ends and crimping windows permitting a crimping tool to enter and crimp the buckets to facilitate the attaching of the connector to a cable.

Description: The invention relates to co-axial connectors for forming cable terminations. The invention relates more particularly although not exclusively to connectors for single twisted pair screened cables for use in data highway systems for example. An example of a connector of this type is disclosed in EP-A-0 190 843. The present invention provides cable terminations in the form of a free connector assembly and/or a fixed connector assembly for connection together or for connection to anchored cooperating respective assemblies including dummy loads and matched impedances. The main physical dimensions of connectors are generally laid down by International Standards so that free and fixed connectors of different suppliers or manufacturers will cooperate with connectors of all other suppliers. Thus, all designs are restricted in practice to comply with such Standards. Further, in all cases careful separation of and electrical screening of the inner conductors is essential. At present connectors are made up of a number of prepared and distinct parts which are either electrical conducting or highly electrically resistive as appropriate which fit together and to which the conductors and a screen of a cable are secured at the terminations. At present the connectors are assembled onto the end of a cable by a laborious, usually manual, process of step by step assembly in which the conductors are connected in turn during that assembly to the required parts. It is an object of the invention to provide a method for terminating a single twisted pair screened cable. According to the invention there is provided a method for terminating a single twisted pair screened cable, comprising the steps of providing a free or fixed connector assembly having a dielectric housing for an intermediate contact assembly which includes two longitudinally extending electrical contacts, an inner contact which at one end forms an inner crimp bucket and at the other end a pin or socket, and similarly a middle contact which extends parallel with said inner contact and which forms, at the same end as the inner contact, a middle crimp bucket and at the other end thereof a socket or pin, the dielectric housing being provided with crimping windows in line with said crimp buckets; bearing the end of each wire of a twisted wire pair and inserting each wire of the twisted pair into a respective crimp bucket; crimping each crimping bucket on the respective wire with a single crimping tool having jaws which are able to extend simultaneously through said crimping windows, said tool being positioned about said housing and operated to insert simultaneously said jaws into said windows to compress both said crimp buckets onto their respective wire so as to form an electrical contact between the crimp buckets and the wires. According to the invention the method is preferably carried out with a free or fixed connector assembly having an intermediate socket contact assembly or an intermediate pin assembly respectively, the assembly having crimping windows in a middle dielectric body of the assembly to permit a crimping tool to extend in use through the windows and to compress an inner contact crimp bucket and a middle contact crimp bucket onto respective conductor ends to secure the conductors thereto. Preferably, the crimp buckets are provided with chamfered path entries to facilitate the entering of the exposed ends into the buckets. One or both buckets may have a transverse aperture positioned in line within the window enabling the end of the conductor to be viewed through the aperture before applying a crimp to the bucket. Preferably, the buckets are generally side by side so that bared ends of the conductor can be prepared with equal lengths for connection to the assembly. An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross sectional elevation of a free connector assembly; Figure 2 is a cross sectional elevation of a fixed connector assembly; Figure 3 is a part sectioned enlarged elevation of an intermediate socket assembly; and Figure 4 is a part sectioned enlarged elevation of an intermediate pin assembly. Referring to the drawings, the general overall dimensions of the assemblies are governed by International Standards and they join up together to provide cable terminations to connect two cables (not shown) together. The intermediate socket assembly and the intermediate pin assembly are preformed for connection to the twin conductors of each cable. In Figures 1 and 2 the parts forming the intermediate assemblies are clearly shown. The intermediate socket contact assembly consists of an inner contact 1 (which extends to and has formed therein an inner crimp bucket 1A), an inner dielectric sleeve 2, a middle contact 3 (which extends to and has formed therein a middle crimp bucket 3A), a middle dielectric sleeve 4, and a middle dielectric moulding 5. In Figure 3, it will be seen that the moulding 5 has two windows 9 in line with the buckets 1A and 3A. It will also be noted that the moulding 5 is chamfered at 5A to provide conductor lead-ins for the buckets 1A and 3A. Similarly, the intermediate pin assembly has an inner contact 1 (extending to an inner crimp bucket 1A), an inner dielectric sleeve 2, a middle contact 3 (extending to a middle crimp bucket 3A), a middle dielectric 4 and a middle dielectric moulding 5. The moulding 5 has two windows 9 (see Figure 4). In use, a cable ferrule is fitted over the end of a cable to be terminated and then prepared conductor ends, which are equal in length, are presented to the intermediate assemblies. The bared conductor ends are fed past the chamfers at 5A and enter inside the appropriate buckets 1A and 3A and are held there. A crimping tool is then fitted around the moulding 5 and its jaws entered simultaneously through the two windows 9 to apply crimping pressure to deform the buckets and electrically secure the conductors to the inner and middle contacts respectively. After crimping, appropriate outer contacts of generally conventional form are then crimped to the ferrule, trapping the cable screen in the normal way. The outer body is provided with screwed connecting parts of conventional form so that the free and fixed connector assemblies can be brought together and screwed up to provide together a screened cable connection. However, it will be noted that a shaped friction pad 6, pressing against a sealing gasket 7 when the assemblies are brought together, offers a novel closure aid. Using the friction pad characteristics an initial longitudinal pressing contact is positively discernible by an operator when the assemblies are screwed together and thereafter, by applying a closing torque to the screw connection (which torque is laid down in the International Standards), it is ensured a more certain and secure connection is made than was otherwise always possible. In many applications apart from laid down International Standards, various tools are also well-known and Officially approved. In this context, the preferred crimping tool used with the described connector is an H308 crimping tool. This tool can be used with jaws suitably designed and adapted to enter the windows 9 as described. Naturally, jaws can be designed where preferred to force a double or triple crimp into each bucket. The jaws of this same tool can be designed and used to crimp the screen in a second crimping action. Thus, only one crimping tool is required. It is possible to provide an aperture 8 at or near the root of one or both of the crimping buckets of each intermediate assembly. This enables the end of one or both conductors to be viewed through the window 9 and the aperture 8. Before the crimp is applied it can, in this way, be visually ascertained that the forward end of the conductor has at least entered well down into the bucket. It will be appreciated that the described connector is much easier to use to terminate a cable than presently used connectors because the conductors are the same length and bared by the same amount at their ends; this can be done according to a pattern or against a suitable template. The chamfers at 5A ensure an easy passage of the conductors into the crimp buckets and there is only one crimping operation. Prior connectors invariably consisted of many loose parts which had to be assembled individually for each cable termination or termination repair. During use in the field or while in an equipment, say in an army vehicle or aircraft, it is virtually impossible to keep in place and manipulate a number of small and delicate parts. By providing the connectors with an assembly, such as the free or fixed connector assembly as described, a sound termination is relatively easy to achieve in a factory or in the field. It will be appreciated that the embodiments of the invention can be provided for cables having more than two conductors. In such cases, the contact assemblies of Figures 3 and 4 are formed with three or more windows 9, a separate window 9 for each conductor. Similarly as described, this enables a crimping operation to be carried out after the assemblies have been prepared so that only the few loose parts are needed in kits for actual cable terminations to be achieved. This means that satisfactory terminations can be carried out even in difficult environments at points of need and "in the field" where required.

Claims: A method of terminating a single twisted pair screened cable, comprising the steps of providing a free or fixed connector assembly having a dielectric housing (5) for an intermediate contact assembly which includes two longitudinally extending electrical contacts (1,3), an inner contact (1) which at one end forms an inner crimp bucket (1A) and at the other end a pin or socket, and similarly a middle contact (3) which extends parallel with said inner contact and which forms, at the same end as the inner contact (1), a middle crimp bucket (3A) and at the other end thereof a socket or pin, the dielectric housing (5) being provided with crimping windows (9) in line with said crimp buckets (1A,3A); bearing the end of each wire of a twisted wire pair and inserting each wire of the twisted pair into a respective crimp bucket (1A,3A); crimping each bucket (1A,3A) on the respective wire with a single crimping tool having jaws which are able to extend simultaneously through said crimping windows, said tool being positioned about said housing (5) and operated to insert simultaneously said jaws into said windows (9) to compress both said crimp buckets (1A,3A) onto their respective wire so as to form an electrical contact between the crimp buckets and the wires.

Inventors: BREESE ALAN, BREESE, ALAN
Applicants: ELECTRONIC COMPONENTS LTD, AB ELECTRONIC COMPONENTS LIMITED
Application year: 1988
Main classification: H01R17
IPC codes: H01R13, H01R9