GB2187341A

GB2187341A - Method for terminating an electrical lead

Info

Publication number: GB2187341A
Application number: GB08704019A
Authority: GB
Inventors: Geoffrey Robert Corbett
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1986-02-27
Filing date: 1987-02-20
Publication date: 1987-09-03
Anticipated expiration: 2007-02-20
Also published as: GB2187341B; GB8704019D0; GB8604926D0

Abstract

A method of terminating an electrical lead comprising the steps of baring a predetermined length of the end region of the core (16) of the lead (15), engaging the bared end of the lead (15) in the groove of a crimpable metal clench (11) of U-shaped cross-section, crimping a first pair of tags (12) of the clench (11) onto the sheath of the lead (15), crimping a second pair of tags (13) of the clench (11) onto the bared region of the core (16) of the lead (15), engaging the crimped clench (11) in the groove of the U-shaped cross-section attachment region of a terminal member (17) such that the base portion of the crimped clench (11) seats in the base portion of said attachment region, crimping a first pair of tags (19) of the attachment region of the terminal (17) onto the first tag region of the crimped clench (11) so that the first tags (19) of the attachment region of the terminal engage the crimped first tags (12) of the clench (12), and, crimping a second pair of tags (21) of the attachment region of the terminal (17) onto the second tag region of the crimped clench (11) so that said second tags (21) of the attachment region of the terminal engage the crimped second tags (13) of the clench (11). The invention also resides in a clench for use in terminating an electrical lead, a lead so terminated, and a lead equipped with a clench. <IMAGE>

Description

SPECIFICATION Method for terminating an electrical lead This invention relates to a method of applying an electrical terminal to an insulated electrical lead and to an apparatus for use in such termination and a lead so terminated.

It is known to terminate an insulated electrical lead by baring an end region of the conductive core of the lead and attaching a terminal to the bared end of the lead by crimping a first portion of the terminal around the insulating sheath of the lead and simultaneously crimping a second, integral portion of the terminal around the bared core. Terminals, formed by stamping and bending planar metal sheet are produced in a range of terminal types and within each terminal type there is a range of predetermined sizes, the first and second crimpable portions of the terminal being sized in accordance with a known range of lead sheath and core diameters.

There is a current trend towards leads of reduced diameter by comparison with existing leads, the diameter reduction being consequent upon a reduction in both core diameter for a given amperage rating and a reduction in insulating sleeve thickness.

Existing terminals designed for use with existing larger diameter leads cannot satisfactorily be crimped around the sheath and core of the newer smaller diameter leads in that mechanically secure and electrically efficient connection cannot be ensured. Moreover, the design and production of new tools necessary for the manufacture and crimping of a new range of terminals may be prohibitively expensive and time consuming particularly noting that a complete terminal redesign would probably be necessary.It would, for example, be impractical simply to incorporate a reduced size lead connection (crimpable) region in an otherwise unchanged terminal since to obtain a reduced size crimp the material of the terminal would need to be thinner than that of existing terminals and this would give rise to problems in manufacturing and achieving adequate performance in the mating region of the terminal. Moreover the crimp region would in some cases need to be lengthened and this together with the need to redesign the mating region would give rise to problems of compatability with existing terminals with which the new terminal must mate in use. Furthermore many terminals are intended to be received in moulded synthetic resin housings of various types ranging from simple individual insulating covers to complex multi-way plug and socket connectors.A change in housing design would be consequent upon a change in terminal design and because of restrictions on the speed of moulding it is usual to utilize a plurality of identical moulds simultaneously (often in a multi-impression tool); thus the retooling costs consequent upon a housing design change can be very high. It is therefore an object of the present invention to provide a method of terminating the newer small diameter leads with existing terminals.

In accordance with the present invention there is provided a method of terminating an electrical lead comprising the steps of: baring a predetermined length of the end region of the core of the lead, engaging the bared end of the lead in the groove of a crimpable metal clench of Ushaped cross-section, crimping a first pair of tags of the clench onto the sheath of the lead, crimping a second pair of tags of the clench onto the bared region of the core of the lead, engaging the crimped clench in the groove of the U-shaped cross-section attachment region of a terminal member such that the base portion of the crimped clench seats in the base portion of said attachment region, crimping a first pair of tags of the attachment region of the terminal onto the first tag region of the crimped clench so that the first tages of the attachment region of the terminal engage the crimped first tags of the clench, and, crimping a second pair of tags of the attachment region of the terminal onto the second tag region of the crimped clench so that said second tags of the attachment region of the terminal engage the crimped second tags of the clench.

The invention further resides in a clench for use in the above method, an electrical lead equipped with a clench, and an electrical lead terminated in accordance with the above method.

One example of the invention is illustrated in the accompanying drawings wherein Figure 1 is a side elevational view, partly in section, of a crimpable clench, Figure 2 is a view in the direction of arrow A in Fig. 1, Figure 3 is a view in the direction of arrow B in Fig. 1, Figure 4 is a diagrammatic view illustrating a lead equipped with a clench being introduced into the attachment region of a terminal, and Figure 5 is a view similar to Fig. 4 but illustrating the attachment region of the terminal crimped around the clench.

Referring to the drawings, there is provided a clench 11 which is of generally U-shaped cross-section, and which is produced from planar copper sheet by a stamping operation.

The clench 11 is elongate, and adjacent one end the side walls of the clench define a first pair of crimpable tags 12. Adjacent the opposite end of the clench the side walls define a second pair of crimpable tags 13, the tags being of greater length, in the direction of the length of the clench, and of lower height, than the tags 12. The base portion of the clench between the tags 13, is provided in its inner surface with a pair of parallel transverse grooves 14 the opposite ends of which extend upwardly into the inwardly presented faces of the tags 13. The spacing between the tags 12 is greater than the spacing between the tags 13.

The dimensions of the clench 11 are chosen to suit a particular electrical lead, the spacing between the tags 12 being chosen to accept the outer diameter of the sheath of the lead, and the spacing between the tags 13 being chosen to receive the core, but not the sheath of the lead.

A range of clenches will be provided to suit the range of newer, small diameter leads.

The clench is attached to its respective lead 15 in the following manner. A predetermined length of the insulating sheath at one end of the lead 15 is stripped from the conductive core 16 of the lead to leave a predetermined length of the core 16 bare. The bared end of the lead is then inserted into the open face of the appropriate clench so that a still insulated region lies between the tags 12, and a bared region of the core extends between the tags 13. The base of the clench is stepped upwardly in the region of the tags 13 so that both the sheath and the bared core can lie against the base portion of the appropriate region of the clench. A crimping tool is then used simultaneously to crimp the tags 12 onto the sheath of the lead and the tags 13 onto the bared core of the lead.During the crimping operation the bared core is deformed downwardly into the grooves 14 to provide a mechanical locking action resisting stripping of the crimped clench axially from the end of the lead.

The thickness of the material of the clench 11 and the nature of the crimping action performed on the tags 12, 13 is such that the crimped clench provided regions corresponding in size to the sheath and bared cored regions respectively of a conventional, larger diameter lead. Thus a lead equipped with the clench 11 can have a conventionally sized terminal crimped thereto as if the terminal was being crimped to an electrical lead of the size which the terminal was designed to accommodate. As is clear from Fig. 4 the terminal 17 is conventional, and includes a connector portion 18 which may, as shown, be a blade portion or which alternatively may be a female LUCAR (Reg. Trade Mark) portion arranged to receive a blade. The contact portion can of course take other known forms.Integral with the contact portion 18, at one end thereof, is a lead attachment region which is of U-shaped cross-section and is elongate having a first pair of crimpable tags 19 at its end remote from the connection portion 18, and a second pair of crimpable tags 21 intermediate the tags 19 and the portion 18.

In order to attach the terminal 17 to the lead 15, the end of the lead 15 carrying the crimped clench 11 is positioned within the attachment region of the terminal 17 with the base portion of the clench seated in the base of the groove defined by the attachment region of the terminal 17. Thereafter, a conventional crimping tool (normally used for crimping the attachment region of the terminal 17 around an appropriate lead), is used simultaneously to crimp the tags 19 onto the tags 12 of the clench and to crimp the tags 21 onto the tags 13 of the clench. The final form is illustrated diagrammatically in Fig. 5, and it will be appreciated that if desired the inner surface of the base region of the terminal between the tags 21 may be formed with transverse grooves equivalent to the grooves 14 of the clench.While it is preferred that the tags 12 and 13 are criped simultaneously and subsequently the tags 19 and 21 are crimped simultaneously, it is to be understood that the tags 12, 13 may in some circumstances be crimped separately as may the tags 19, 21.

It will be recognized that the use of a clench avoids the necessity for redesigning terminals, housing mouldings, and tools for producing and applying terminals, in order to suit the new smaller diameter leads. Aithough it is necessary to design and produce tools for manufacturing and applying the clench, it will be recognized that only one clench is needed for each lead size, whereas a wide variety of different terminal forms are applicable to each lead size. Thus a clench appropriate to a particular lead size can be used to permit that lead to be terminated by anyone of a wide variety of different forms of existing terminal. The provision of the clench ensures a mechanically secure and electrically efficient connection of the terminal to the small diameter lead.

Claims

1. A method of terminating an electrical lead comprising the steps of: baring a predetermined length of the end region of the core of the lead, engaging the bared end of the lead in the groove of a crimpable metal clench of Ushaped cross-section onto the sheath of the lead, 'crimping a first pair of tags of the clench crimping a second pair of tags of the clench onto the bared region of the core of the lead, engaging the crimped clench in the groove of the U-shaped cross-section attachment region of a terminal member such that the base portion of the crimped clench seats in the base portion of said attachment region, crimping a first pair of tags of the attachment region of the terminal onto the first tag region of the crimped clench so that the first tags of the attachment region of the terminal engage the crimped first tags of the clench, and, crimping a second pair of tags of the attachment region of the terminal onto the second tag region of the crimped clench so that the said second tags of the attachment region of the terminal engage the crimped second tags of the clench.

2. A method of terminating a lead substantially as hereinbefore described with reference to the accompanying drawings.

3. A clench for use in the termination of an electrical lead comprising a metal component of U-shaped cross-section having a first pair of crimpable tags adjacent one end of the component and a second pair of crimpable tags adjacent the opposite end thereof.

4. A clench as claimed in claim 3 wherein the base of the region carrying the tags to be crimped around the bared core of the lead is formed with transverse grooves into which the material of the bared core is deformed during crimping.

5. A clench as claimed in claim 3 or claim 4 wherein the base is stepped between the two pairs of tags so that both the bared core of the lead and the sheath of the lead can simultaneously engage the base of their respective region of the clench.

6. A clench substantially as hereinbefore described with reference to the accompanying drawings.

7. A lead terminated by the method as claimed in claim 1 or claim 2.

8. A lead fitted with a clench as claimed in anyone of claims 3 to 6.