Clamp body for electrical connector clamps

In order to increase the clamping effect in an electrical screw connector used in industrial applications to fix or hold an electrical conductor, the support and contact surfaces for the electrical conductor are textured. According to the invention, the texturing of the support and contact surfaces for the electrical conductor is carried out by various production methods using embossing or stamping tools.

TECHNICAL FIELD

The invention relates in general to the realm of fundamental electrical components from the world of electronic equipment consisting of electrically-conducting connector elements. One of these connector elements from the realm of connector terminals is in its simplest form the screw connector. In screw terminals, electrical conductors are brought into mutual mechanical and electrical contact in clamp bodies by means of clamp screws and suitably-shaped clamping elements.

BACKGROUND INFORMATION

In industrial connector equipment, a large number of differing clamp bodies for screw terminals have proved themselves by the billions, and are the most frequently-used connector equipment. Clamp bodies for the electrical screw terminals consist as a rule of a clamp pocket with essentially U-shaped cross section (EP 0 334 975), or an approximately rectangular housing with at least one threaded part and/or a threaded hole, into whose threads a clamping screw may be threaded. The high clamp body may also be in the shape of a pull strap. All clamp bodies have in common the fact that they include a clamp body recess, hereafter referred to as a cavity that serves to receive the electrical conductor, whereby the conductor may consist of single-wire or multiple-wire (fine wire) conductors.

The electrical conductor is clamped within this cavity by means of the clamp screw. Clamping of the electrical conductor may also be achieved by means of a current bus or rail inserted between the clamp screw and the electrical conductor. In order to increase the clamping effect of the electrical conductor, the current rail may be textured on the side facing toward the electrical conductor. Also, the floor surface of the cavity of the clamp body may be textured. So, for example, clamp bodies for electro-technical screw terminals are known from EP 0 082 285 B1 and from DE 203 05 314 that include walls projecting inward within the cavity between which recesses are located.

These clamp bodies with textured recess floors are produced, for example, from stamped plate steel or copper alloys using forming equipment. In this type of clamp body, which is formed of several pieces corresponding to the above-mentioned tasks, the cavity-plate or pocket-plate thickness selected acts disadvantageously on the deformation of the oblique floor walls during loading by the clamp screw. These deformations lead to a clear reduction of permissible clamping forces, whereby secure clamping because of the setting of the conductor connection is not ensured.

An additional embodiment example of a conventional clamp body may be taken from the State of the Art, for example from the “CLIPLINE Terminal 2002” TN12 5123461/10.04.02-00 product catalog of the company Phoenix Contact & Co. KG. The clamp bodies shown therein made of a tension-crack corrosion-resistant high-value copper alloy possess a crosswise drilled hole oblique to the floor of the cavity for optimum affixing of electrical conductors. This hole is created by a metal-cutting procedure within the clamp body, and is a penetrating hole that passes obliquely through the entire clamp body. Such an embodiment example of State-of-the-Art clamp bodies produced by means of a metal-cutting procedure may be taken fromFIG. 1. The hole perpendicular to the cavity aperture is so located that the surface in the floor of the cavity, as well as adjacent oblique surfaces that represent the connection to the side walls and which normally extend flat from the one side of the cavity aperture to the other side of the cavity aperture, are interrupted by the drilled hole. This interruption serves to texture the cavity in order to increase the clamping effect between the electrical conductor and the clamp body. The drilled hole passing through the clamp body in the area of the floor surface of the cavity weakens the sidewalls of the clamp body exceedingly, i.e., the forces arising from the tension moment of the clamp screw may act disadvantageously on the geometric shape of the clamp body. The hazard of plastic deformation exists along with that of having no stable clamping action. Further, positive function upon several actuations of the screw terminal cannot be ensured. The metal-cutting processing procedure thus acts disadvantageously on the mechanical strength of the clamp body.

SUMMARY

It is therefore the task of the invention to produce a clamp body of the type mentioned at the outset such that the afore-mentioned disadvantages of the known configuration are avoided, and particularly, a lower-cost clamp body with simple functional geometry for electrical screw terminal is provided. Also, the manufacture of the clamp body should allow a higher output level per time unit, whereby the clamp body corresponds not only to the torque requirements of the standard, but also, because of the special manufacturing procedure, allows resistance to deformation that is greater than the standard device available on the market and is useable specifically for small clamp bodies, e.g., in row-terminal configurations for plug connectors.

This task is solved by the invention with a clamp body of the named type by the distinguishing characteristics disclosed and recited herein. In order to manufacture clamp bodies with these characteristics of the invention that achieves uniform and safely-applied clamping force, and moreover that typically are resistant to vibration under loads found in industrial applications in screw terminals for long time periods such as moving machine parts, it is proposed to use a procedure for clamp body manufacture, particularly during production of the recesses in the cavity of the clamp body, that does not reduce the resistance of the clamp body to deformation, but rather maintains or even increases it. The structuring of the surfaces within the cavity causes the values of the IEC Norm 60 947-1/EN 60 947 regarding secure connection of the conductor not merely to be fulfilled, but actually exceeded. The textured surfaces within the cavity act as support surfaces and contact surfaces for the electrical conductor.

In order to increase the strength of the clamp body and the firm seat of the electrical conductor for technical application, it is recommended by the invention to use the following manufacturing procedure in the production of textures in the form of, for example, recesses in the surfaces. Recesses that represent deepened recesses within the cavity of the clamp body for electro-technical screw terminals in floor and sidewalls. These deepened recesses that ensure the firm seat of the electrical conductor in interaction with the current rail are technically known as beads.

During production of the beads in the clamp body, one takes advantage of the properties of the material of which the clamp body consists. As a rule, the clamp bodies are of brass, but other metals such as steel are conceivable. Copper alloys may be cold-shaped, and are therefore well suited to pressing, stamping, hammering, striking, and chasing. These material properties are advantageously used during the production of the beads.

Production of the beads is by means of embossing equipment. This embossing equipment is considerably cheaper because production of the beads may be achieved within a fully-automated cycle process. The cycling process during embossing is significantly shorter with respect to the metal-cutting process. For example, the clamp bodies that have already passed through various manufacturing steps are supplied to an automatic embossing machine that may be driven mechanically and/or pneumatically. The clamp bodies are positioned exactly and automatically tensioned in a tool device. Simultaneously, a embossing tool moves horizontally into the part to be stamped and/or into the cavity of the clamp body. The clamp body may also be so supplied to the embossing tool by the automatic supply device that proper embossing position is achieved. The embossing may be, for example, made of tool steel, and may be heated. Further, the embossing tool possesses a texture on its underside whose shape and/or relief corresponds in size and shape to that of the desired beads within the clamp body. The embossing tools may be engraved on many sides and are flexibly interchangeable so that any conceivable texture may be produced on the embossing tool and embossed into the clamp body. The shape and size of the texturing of the surface of the floor and sidewalls within the cavity of the clamp body may be adapted to the technical requirements such as, for example, various clamping effects on different electrical conductors. Not only the creation of recesses in the shape of beads, but also the creation of raised projections is possible because of cold shaping in the embossing technique. For example, raised projections in the form of crowned projections or a combination of recesses and raised projections that provide optimum clamping effect on the electrical conductor used. For example, micro-textures are available for clamping fine-wire conductors in clamp bodies. I.e., the texture and shape of the support surface and contact surface for the electrical conductor within the clamp body determines the clamping effect, and thus the extraction forces on the clamped conductor.

The embossing process itself may be achieved, for example, by adding a pressure spindle vertical to the embossing stamp. This pressure needle is driven through the drilled hole of the clamp screw using pneumatically-driven reciprocation, and acts with hydraulically-generated pressure on the embossing tool. The texture of the embossing tool is thus pressed into the contacted surface of the clamp body. Next, the pressure spindle returns to its initial position, and the clamp body is ejected from the tensioning device.

A stamping machine that optimizes the cycling time of the embossing may also be advantageously used to create the embossing texture. Further, this procedure distinguishes itself by a high cycle rate, which reduces the cycling time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference Index List

A clamp body1known from the State of the Art is shown inFIG. 1as an example with a first aperture2to receive a clamp screw (not shown) with a second aperture (3) to receive an electrical conductor (not shown) into a cavity4that is formed by the inner surfaces5,6,7,8. The inner surfaces5,6serve the electrical conductor as support surface and contact surface. The inner surfaces5,6may possess a texture9. This texture is created through the drilled hole10that extends obliquely through the entire clamp body1and/or perpendicular through the sidewalls12. The drilled hole10causes the normally two-dimensional penetrating inner surfaces5,6,7to be interrupted. The interruption forms a recess11caused by the drilled hole10, for example in the oblique surface6that is also present in the inner sidewall surface7and the floor surface5. The drilled hole10is a penetrating drilled hole10that passes through the two sidewalls12and the cavity4.FIG. 1thus shows a perspective view of a clamp body1that possesses inner surfaces within a cavity4whose textures were created by means of a metal-cutting process.

The invention relates to a procedure and a device to produce a clamp body of copper alloy for electro-technical screw terminals with textured surfaces within the cavity that serve as support surfaces for the electrical conductor, whereby the textured surfaces were created using embossing equipment.

Application of the production procedure and the device are shown as an example inFIG. 2. The device15consists of an embossing tool16located inFIG. 2within the aperture3of the cavity4of the clamp body1and the embossing position18. The embossing tool16possesses a texture17on its underside (the side facing toward the floor surface5of the clamp body1). A pressure spindle19is located within the aperture2of the clamp body1that serves to receive the clamp screw that presses perpendicularly onto the embossing tool16. The texture17contained within the embossing tool16is reproduced in one or more inner surfaces of the cavity4by means of the force transfer from the pressure spindle19onto the embossing tool16. In the example ofFIG. 2, into the oblique surfaces6,6′. The transfer of the texture17from the embossing tool16into the surfaces6,6may be accomplished by means of pressing, striking, hammering, or driving. The pressure spindle19can thus operate on the embossing tool16using different techniques. After the texture17is transferred to the surfaces of the cavity4, the clamp body1is ejected from the tensioning device (not shown). A clamp body1thus produced is shown inFIG. 4.

AsFIG. 3shows, the texturing9of the inner surfaces of the clamp body1may also be by means of impact equipment. The pressure spindle19is then itself the bearer of an embossing texture17, and serves as embossing stamp20, whereby the embossing tool16is not required. The embossing stamp20is guided through the aperture2and forms by means of impact equipment a deepened recess11on the oblique surfaces6,6of the floor surface5and, as applicable, on the sidewall surfaces7,7′. For this, the clamp body1is positioned in a tensioning device (not shown), is inclined by a few degrees from the perpendicular axis23of the embossing stamp20. The angle of inclination24may vary between 0° and 10°. The embossing stamp20may advantageously be inserted through the aperture2into the cavity4of the clamp body1at this angle of inclination24with respect to the perpendicular axis23of the embossing stamp20. This angle of inclination24causes first the inner side(1)21of the cavity4to become textured on surfaces5,6,7, and second, by pivoting the embossing stamp20or the tensioning device, the inner side(2) on surfaces5,6′,7′. During this process of texturing the inner surfaces, the material of the clamp body1may also be driven by moving the embossing stamp20from side(1) to side(2).

A clamp body produced using the manufacturing procedure and device perFIG. 2is shown inFIG. 4. In principle, the clamp body1consisting of a copper alloy is a geometric body consisting of four walls. Consisting of two perpendicular sidewalls12, an upper wall13in which the aperture2is located for a clamp screw (not shown), and a floor wall14across from the upper wall13that extends perpendicular to the sidewalls12. All walls are formed as one piece. The outer shape of the clamp body1may possess different thickness28and shape27in the floor area. A cavity4is located in the center of the clamp body1that is accessible from two sides through apertures3that are located on the front face29and the rear face30, and is formed by inner surfaces. The cavity4serves to receive the electrical conductor (not shown), and possesses various support surfaces and contact surfaces to clamp and contact the electrical conductor. Two support surfaces7,7′ extend parallel to the perpendicular sidewalls12. The support surface of the floor5is perpendicular to the support surfaces of the sidewalls7,7′. Two additional oblique support surfaces6,6are positioned between the floor surface5and the sidewall surfaces7,7′ to increase the contact of the electrical conductor with the support surfaces of the cavity4. The oblique support surfaces6,6′ connect the floor surface5with the sidewall surfaces7,7′ at an angle of approximately 45°. The oblique surface6,6′ was textured using an embossing tool16to increase the clamping effect. The embossing stamp texture17of the embossing tool16creates a texture9in the oblique surface6,6′. This texture9is implemented, for example, as a recess11, and is also known as a bead. The production of several beads11in an oblique surface6,6′ is also conceivable.

The texture17of the embossing tool16may also create a raised projection in the oblique surface6,6′ in the form of a crown-shaped projection25(seeFIG. 5). Also, a combination of recesses11and crown-shaped projections25may be created as a texture9in the oblique surfaces6,6′ for further increase of the clamping effect for electrical conductors, particularly in special applications.FIG. 6shows this textured implementation form. An alternating series of crown-shaped projections and recesses11creates waved textures in the oblique surfaces6,6′, whereby the material pressed into the recesses11may be used to raise the crown-shaped projections25. The texturing of the sidewalls7,7′, advantageously with micro-textures26is possible using embossing equipment, whereby the depth of the micro-texture may lie within the range of 1 micrometer to 0.1 millimeter. For this, the clamp body1requires merely that it be rotated through 90°, the embossing tool be guided into place, and textured as before using procedure described above, whereby the pressure spindle19is not guided through the aperture2, but rather projects along the front face surface29of the clamp body1up to the embossing tool16that is projecting from the cavity4.

The present invention is not intended to be limited to a device or method which must satisfy one or more of any stated or implied objects or features of the invention and should not be limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the allowed claims and their legal equivalents.