DE1057193B - Electrical compression sleeve connector - Google Patents

Description

GERMAN

The invention relates to electrical compression sleeve connectors with transverse grooves on the inner jacket.

Many types of wire that are commonly used to make electrical connections have a layer of a tough, elastic insulating coating. In addition, bare electrical wires become common dirty or develop layers of corrosion, such as oxides or sulfides, which reduce the contact resistance noticeably increase or even insulate the conductor. When a connection between conductors To be made that have such outer layers or films, it is first necessary to apply the insulating coating in any way to penetrate or scrape off before making electrical contact with low Ohmic resistance can be established.

Up to now it has been customary to strip or through such dirty or coated wires individually To clean loops, for example wire cutters or similar tools were used. For certain wire coatings, this process is feasible, but time consuming and expensive. For other wire coatings, e.g. B. certain hard and elastic insulating films, this method has because of the mechanical difficulties of completely removing the coating without damaging the conductor, proved impractical. This is especially true with relatively fine wire.

Attempts have now been made with connectors without the use of solder, in which the connections have relatively sharp teeth or prongs. The teeth are designed so that when used be driven by compressive force through the insulation cover. Some tough coatings will be but now hardly penetrated by the teeth of such connections.

The object of the invention is to create an electrical compression sleeve connector on the inner jacket lying Ouernuten, which allows good electrical contact with wire, which is a coating of relatively non-conductive material, and in which this good contact under unfavorable operating conditions is maintained.

This is achieved according to the invention in that the transverse grooves have the cross-sectional shape of a trapezoid with legs converging to the bottom of the groove. The groove edges are preferably slight so that they form sharp burrs that cut into insulating coatings on the conductors. the According to the invention, outer shear edges of these grooves are preferably approximately 0.254 to 0.500 mm apart, with the base of each groove being approximately half as wide and approximately half as deep.

In the drawing shows

Fig. 1 is a plan view of a partially opened

30th

35

Applicant:

AMP Incorporated,
Harrisburg, Pa. (V. St. A.)

Representative:
Dr.-Ing. H. Ruschke ₁ Berlin-Friedenau,
and Dipl.-Ing. K. Grentzenberg,
Munich 27, Pienzenauerstr. 2,
Patent attorneys

Claimed priority:
V. St. v. America June 12, 1953

Kemper Martel Hammell, Harrisburg, Pa. (V. St. A.),
has been named as the inventor

Drawn electrical compression sleeve connector according to the invention, which is pressed onto a twisted conductor is,

Fig. 2 shows on an enlarged scale and broken off the longitudinally cut, grooved wall of the Compression sleeve connector according to Fig. 1,

Fig. 3 is a plan view of the ferrule connector prior to curling and

4 shows, on an enlarged scale, the longitudinally cut connecting wall with a different type of groove and the associated embossing tool.

Fig. 1 shows an electrical line connection designated as a whole by 2. Its clamp part 4 is crimped onto the stranded wires 6 of the insulated stranded cable 8. The ring tongue 10 (Fig. 3) of the connection is used to attach a terminal or the like. Each stranded wire 6 can with an oxide, sulfide, Oil or wax layer or be coated with insulating material of the cable insulation 9.

The connecting wall in Fig. 1 has a number of grooves 12, the edges of which are at an acute angle form so that the edges of coatings of the individual stranded conductors of the wires 6 on the circumference penetrate and can shear into the metal of these individual conductors, so that during the crimping or Upsetting operation contact with the current-carrying

909 510/341

Parts of this stranded conductor is made. The clamp part 4 is pressed inwardly against the conductor under sufficiently strong pressure that the metals are deformed. The sides of the grooves cut the inner surface of the ferrule part at an acute angle depending on the metals used, so that the sheared surfaces of the conductors are clamped in the grooves with such a pressure that the surfaces of the conductors and grooves are firmly held together and protected against corrosion . The crimping pressure presses the wire down against the groove base. As a result of this support on the ground, it is prevented that the shearing process weakens the wire in a critical manner after it has penetrated the insulating layer. Any further crimping after the wires have reached the bottom merely results in an embossing of the conductor material.

Since the grooves 12 have inclined side surfaces, the parts of the wires 6 pressed into the groove area are held under compressive stress, so that uninterrupted pressure contact between the connecting sleeve and the conductors is ensured. However, this essentially prevents the ingress of moisture and thus corrosion.

It has now been found λνο ^ εη that the dimensions of the grooves are decisive for the shear effect. The width 11 of the groove 12 between the shear edges in FIG. 2 is particularly important for achieving a good shear effect. Furthermore, the depth 13 of the groove 12 and the width of the land 15 between two grooves (see FIG. 3) also become important, as will be described below.

If the groove width is very small, the shear effect is insufficient. In this case, too, the wire 6 is only slightly pressed into the groove during the crimping process. As a result, a groove side must be used which allows the conductor material to flow unhindered into the groove and a sufficient shear effect with respect to the insulating layer or the coating is achieved.

On the other hand, the groove width must not be too large, so that there is still a sufficiently large number of Ring grooves housed within the clamp part, verden, which is necessary to an effective Establish mechanical and electrical connection.

In order to achieve high-quality connection results, the groove width may deviate by a maximum of approximately 508 mm from the diameter of the individual conductor 6 . In the case of solid wire, the groove width can be relatively smaller than in the case of stranded wire.

As an example of larger wires, a terminal with single conductor diameters of 0.305 to 0.508 mm is provided with grooves approximately 0.381 mm wide. The size of the gap between the shear edges of the grooves is generally between approximately 0.254 and 508 mm, even if the individual conductors are larger or larger than these width limits. Zin of such size range also allows let a relatively large number of grooves in the swing member may be cut.

There is, however, a limit to the number of mare rings in the ferrule part, since a more powerful one "Web" between the shear edges of adjacent grooves! Is required to establish a connection with the desired to ensure high strength and low, stable electrical resistance. So the distance from groove center to groove center for), 254 to 0.508 mm wide grooves must be at least 0.635

to 0.762 mm, and in general the width of the webs should not be smaller than the groove width.

As a result of the inner inclination of the side walls of each groove 12 , the conductor material, which is driven into the grooves by the crimping pressure, experiences a compressive stress and thus maintains a tight seal against the groove side walls through its own elasticity, that is, the conductor material flowing into the groove encounters one continually

ίο decreasing cross-sectional area, so that this material is compressed. As can be seen, the crimping pressure and the tendency of the sheared wire part to tighten against the groove sides is partly determined by the inclination given to the groove sides.

To achieve a good shear, the side surfaces of the groove must form a relatively acute angle towards the bottom of the groove, e.g. B. the indicated in Fig. 2 with 16 angle include.

The optimal angles according to the invention are between 5 and 60 °. The angle must be small for tougher layers surrounding the conductor and larger for soft or fragile coatings. For example, in the case of a layer of extremely tough and elastic insulating coating, an angle of approximately 5 ° has proven to be very good. On the other hand, in the case of a conductor with a copper sulfide layer, a large angle of 50 ° was found to be satisfactory. The groove depth 13 in Fig. 2 must be sufficiently large to ensure that the wires 6 sit firmly in the connection. The groove depth must also be large in order to ensure that each insulating layer is sheared through before the wires 6 fill the grooves.

In general, the optimum groove depth is roughly half the diameter of a single conductor 6. For a wire having nineteen single conductors, each about 0.368 mm in diameter, a groove depth of about 0.152 mm has been found to be quite advantageous. Terminals with these groove depths are not only limited to use with the particular individual conductor diameters specified, but are also generally suitable for use in a wider conductor size range. The optimum groove depths are approximately 0.127 and 0.254 mm, with larger depths being used for enameled wire and especially for polyvinylmethylalemaillien.

For the predominantly occurring applications, relatively small wires that are contaminated with dirt or Corrosion layers are coated, fasteners can be used which have a groove width of approximately 0.254 mm and a groove depth of approximately 0.127 mm and an angle of about 50 °.

3 shows a connector of the type described above which can be used without solder and in which the ferrule part 4 is rolled up. Several parallel grooves 12 are cut across the conductor contact surface of the ferrule part. The extension parts 3 and 5 of the clamp part 4 are bent upwards and then pressed around one or more conductors under strong pressure, so that an intimate connection between the conductor and the clamp part is created. The bending and crimping can be carried out by tools particularly suitable for this purpose, such as are generally known in the art of non-solderable connectors. When the ferrule part 4 is pressed around the conductor, the sharp edges of the grooves 12 shear through any insulation, dirt, etc. on the conductor and thereby make intimate contact.

Claims (1)

ι ob '/ iys clock with the wires 6, as described with reference to FIGS. To ensure a good shearing action, it is necessary that the sides of the groove coincide as precisely as possible with part of the leg surfaces of the angle 16. The grooves can be formed by machining or punching, but the tools, whether they are cutting or embossing tools, must be as sharp as possible to ensure efficient shear edges. In Fig. 4, an under-worked embossing tool is shown in a somewhat exaggerated and enlarged manner, with which sharp groove edges are formed. The embossing tool is undercut along the base at 22 so that the edges 26 of the groove 30, when the tool is pressed against the flat clamp part blank 4, are formed as sharp shear edges. While the invention is not limited to any particular metal or combination of metals, it is important that the metal of the shear edges be harder than the metal of the wire with which contact is to be made. Soft annealed copper is therefore too soft for most purposes. According to the invention, it has been found that copper or brass of 60 to 70 Rockwell hardness -15-works well with copper wire of hardness 50 or less. If the grooves are embossed in the metal, the shear edges can be worked out particularly sharply. The outward pressure of the central individual conductors presses the outer individual conductors permanently into the toothed grooves, so that a wedged mechanical connection and an effective electrical connection between the conductor and the groove walls is obtained. Experience has shown that an extremely good corrosion-resistant connection of the type described is formed without such a large reduction in the wire cross-section as was previously required for line connections of the same high strength. An important concomitant of the tightly wedged mechanical connection that arises from the electrical point of view of the invention is that the wires are prevented from sliding in the crimped connection when they are heavily used, such as. B. with sharp dropping in the vicinity of the clamp part. This results in better corrosion resistance and also better conductivity of the connection. Comparative tear "pull-out" tests (i.e., a measurement of the force required to pull the conductor out of the connector) provided an indication of the improvement achieved by the invention. Two types of line connections were tested under the same conditions. Group I consisted of normal commercial, non-solderable lead connections of the ferrule type with V-shaped prongs, and group II included non-solderable lead connections of the clamp type, which were designed according to the invention. The average tensile strength for Group II was 103.87 kg that for Group I was 71.44 kg, i.e. that is, an improvement in pull-out strength of approximately 45% was achieved. Line connections according to the invention are not only advantageous in the case of stranded conductors, but also in the case of solid wire conductors, and indeed even in those with a relatively large diameter. For example, two or three solid wire conductors with a diameter of 1.524 mm, each coated with polyvinylmethylal or polyvinyl formal resin (which may contain a smaller or larger proportion of polyvinyl acetal), can be connected by the connector according to the invention if the groove width between the shear edges is approximately 0.305 mm, the Groove depth about 0.203 mm and the groove angle of the groove is about 5 °. With such an arrangement, the groove edges shear cleanly through the resin, creating a stable, non-corrosive, low ohmic electrical connection between the conductors and the connector. Such a result is not achieved with the known line connections. The invention has shown that with relatively deep grooves in the clamp part and vigorous movement of the cable 8 protruding from the clamp part (see right-hand side in FIG. 1), damage to the single stranded wires can occur, for example through breakage in the sheared area. This disadvantage can be avoided by progressively changing the depth of the groove in the ferrule part, starting from the cable entry point, i. H. for example, a first groove depth of approximately 0.0508 mm, a second of 0.1016 mm, a third of approximately 0.1524 mm and so on. In such an embodiment, the grooves with a smaller depth do not shear through the wire as far. Nevertheless, the required pressure restraint and good electrical contact remain. The line connections according to the invention can, in addition to the annular grooves according to FIGS. 1 and 3, advantageously also be formed with serrations or corrugated teeth. For example, good results are obtained if the inner surface of the ferrule part is provided with a number of impressions or grooves, such that the inner surface bears frustoconical or pyramidal structures. If the cable cores are arranged helically with respect to the cable axis, it may be advantageous to cut the grooves of Fig. 3 at such an angle to the ferrule part axis that each groove 12 is so that they the helical twist of the wire exactly or approximately at right angles cuts. This improves the clamping of the cable cores, that is to say increases the “pull-out” strength of the cable. The grooves can also be cut practically parallel to the ferrule part axis, however the angle of inclination and the width of each groove are gradually changed from a minimum in the vicinity of the inlet opening of the conduit connection to a maximum at the end. In such an arrangement, the cable cores form a conical part in the longitudinal direction of the clamp part. The depth of such a longitudinal groove can also be changed from a minimum in the vicinity of the inlet opening to a maximum at the end of the line connection in order to avoid breaking the cable cores in the event of excessively violent movement of the cable leading out of the ferrule part. Claims-. 1. Electrical compression sleeve connector with transverse grooves on the inner jacket, characterized in that that the transverse grooves have the cross-sectional shape of a trapezoid with converging to the groove bottom Own thighs.