FR2565421A1 - IMPROVEMENTS IN CRIMP DRUMS FOR ELECTRICAL CONTACTS - Google Patents

Abstract

1. Electrical contact comprising a crimping socket of the type produced by punching and shaping a sheet metal part to the general shape of a channel, whose flanges are intended to be folded over the wire at the instant of crimping, the bottom (1) of the channel comprising at least one tongue (2, 3) formed by punching and folded to substantially perpendicularly to the axis of the channel, the edges of the flanges (8, 9) being punched to form crenellations (10, 11) whose hollows (10) are situated opposite the tongues (2, 3), the teeth (11) being situated at the two sides of the tongues (2, 3), characterised in that : - tongues (2, 3) have and edge which is in the shape of a V open towards the opening of the channel, this edge being intended to penetrate into the insulation of the wire to the conductors (12) during crimping, and - the teeth (11) penetrate into the insulation of the wire to the conductors (12) during the course of crimping, - so as make electrical contact both through the tongues (2, 3) and through the teeth (11).

Description

The electrical contacts can constitute lugs, sockets, pins,

  clips, extenders, the contact itself being pluggable, built-in, spring, screw, etc. These contacts or contact parts can be mounted on the wires by screws, clamps, crimping, etc. In the case of crimping, this can be carried out on bare wire, by insulation displacement contact, by perforation of insulation. The present invention relates to any electrical contact comprising a barrel to be crimped by perforation of insulation. It is applicable both to single-strand wires, to the hair or to cables called ORFAL, formed of

  blades spiraled around a strand of cotton and particularly

frequently used in telephony.

  The advantage of crimping through insulation perforation is on the one hand that it avoids long and costly labor and ensures increased productivity during assembly, and on the other hand that it avoids damaging the conductor at during the stripping operation, which is particularly important for drivers

very fine.

  But it has the disadvantage that the contacts, which generally result from the flap of points or on points, are very random and often imperfect and that the resistance of the wire in the barrel is weak. Another solution is to push back the

  wires in transverse slots that cut the insulation.

  However, this solution is hardly applicable except to single-strand wires of defined section; the slots must in fact be sized according to the diameter of the wires, otherwise either the contact is not established or the wire is injured; this also results in the need for a range of devices corresponding to the different

wire diameters.

  The object of the invention is to remedy these drawbacks and to make contacts the barrel of which allows crimping of wires of various natures with great reliability both as regards the quality

  of contacts that retention of wires.

  The barrel according to the invention is of the type produced by cutting and forming a metal strip, by

  example in brass, according to a general taste

  shield whose edges or wings will be folded over the wire at the time of crimping and it is characterized in that the bottom of the gutter has at least one tongue

  cut and folded in a substantially perpendicular plane

  cular to the axis of the gutter, the edge of this lan-

  lookout having the shape of an open V towards the west

  greening of the gutter and the two edges of the wings of the gutter are cut into slots, the hollows of

  slots being located opposite or at the level of the lan

  guets in V. It follows from this constitution that when the wings of the gutter are folded over the wire, at

  when crimping, the wire remains centered by the lans

  V-shaped guets and the projecting parts of the slots penetrate into the insulation in conditions of maintenance of the latter which ensure the achievement of the desired contacts. In addition, the projecting parts of the slots

  being located between the tabs, the driver does not risk

  that not to be deteriorated. However, these areas correspond

  laying eggs on the bottom of the gutter, the insulation is pushed back into these holes which, joined to the course

  sinuous thus imposed on the wire ensures excellent retention.

  The invention also relates to the provisions below

  after: a) The projecting parts or teeth of the slots

  are bevelled like sharp tool blades.

  b) Two raised tabs and three projections or teeth of slots are provided along the length of the barrel.

alternately placed.

  c) At least one tab is raised with an obliquity towards the end of the gutter close to the electrical contact (clip, terminal, pin ...)

of which it forms the barrel.

  d) The ends of the branches of the V of the lan-

  lookouts are preferably pointed. The arrangements of the invention are described below with reference to the appended drawing in which an exemplary embodiment is shown: FIG. 1 is a top view of a brass clip provided with a barrel according to the invention;

  Figure 2 is a longitudinal sectional view

  nale of the same clip; Figure 3 is a bottom view; Figure 4 is a section on B-B of Figure 1, on an enlarged scale; Figure 5 is a slightly offset longitudinal section (along C-C of Figure 1) showing the results obtained after crimping; Figure 6 is a similar cross section taken at the teeth of the teeth

(according to A-A in Figure 2).

  Referring to Figures 1 to 4, we see that, in this example, the barrel is made by cutting and forming a brass sheet of 0.25 mm brass in

general shape of gutter.

  According to the invention, the bottom 1 of the gutter has two tongues 2 and 3 cut and raised approximately perpendicular to the axis of the gutter. As can be seen in Figure 2, at least one of the tabs can be tilted slightly towards

the contact part 4 of the clip.

  The edge of the gutters 2 and 3, opposite the folding area, is cut in an open V 5 (Figure 4) at

pointed ends 6 and 7.

  The wings 8 and 9 of the gutter 1 are created

  nelées: The hollows 10 of the slots are opposite or to the right of the tongues, while the teeth or projections

  11 are located on either side of the tongues 2, 3.

  The edges of the teeth 11 are thinned or tapered

in knife blades.

  The cuts made after crimping and which are the subject of Figures 5 and 6 show that: The teeth 11 of the slots penetrate into

  the insulation and ensure good contact with the conduc-

  teurs 12 held in place by the Vs of the tongues; the insulator 13 flows in the sticks of the wings 8 and 9 but also in the punctures 14, 15 left open by the cutting of the tongues 2 and 3. The driver takes the winding course shown; the edges of the V penetrate to the conductors 12, increasing the contacts; the points 6, 7 of the V also penetrate into the insulation and contribute to the contacts. The tensile strength is

  increased by a slight inclination of one of the lan-

  lookouts. The voltage drop and tensile strength tests give the following average results: 1) 7-wire cable - Acceptable current 380 mA Section 0.22 Contact resistance 1.2 ma Tensile strength 4.9 daN 2) ORFAL cable (3 strands) -allowed current 330 mA Contact resistance 5, 2 ma Tensile strength 4.06 daN The values sought are Contact resistance <20 mul Tensile strength> 3.30 daN s On sees that the results obtained are superior to the proposed goals. Contact resistance is practically negligible. It can be considered lower

  at 5 mQ with a typical value of the order of 2 ml.

  The tensile strength is close to the resistance to

  pulling the wire itself for a multi-strand.

  As explained above, the contact barrel according to the invention applies as well to lugs, pins, various sockets, as to a clip as shown and

  generally to any crimped electrical contact

  wise. In the preferred embodiment which is shown, there are provided two tongues 2, 3 cut in opposition and each wing 8, 9 has three teeth 11 on either side of these tongues. But it goes without saying that we can adopt a different number of tabs

  each framed between two teeth of slots.

256542-1

Claims (5)

  1. Electrical contact comprising a crimping barrel of the type produced by cutting and forming a metal strip in a general gutter shape, the wings of which are intended to be folded down on the wire at the time of crimping, characterized in that the bottom ( 1) the gutter has at least one   tongue (2, 3) cut and folded substantially per-   perpendicular to the axis of the gutter, the edge of this tongue having the shape of a V (5) open in the direction of the opening of the gutter and the edges of the wings (8 and 9) are cut into slots (10 , 11) whose recesses (10) are located opposite the V-shaped tongues, the teeth (11) being located on either side tabs.   2. Contact according to claim 1, character-   laughed in that the teeth (11) are bevelled.   3. Contact according to any one of the res-   previous indications, characterized in that the   half of the branches (6 and 7) of the V of the tongues are pointed.   4. Contact according to any one of the res-   previous indications, characterized in that at least   a tongue is folded with an obliquity in the direction tion of the contact.   5. Contact according to any one of the res-   dications previous, characterized in that there are provided two tongues (2, 3) and each wing has three teeth (11) of slots placed on either side of the   tongues alternating with the recesses (10).