Device for cutting the primary insulation of a conductor of a power cable, primary insulation-penetrating contact clamp with such a device, and method for producing a toothbed of such a contact clamp.

Abstract

Device for cutting the primary insulation of a conductor of a power cable, in particular a high-voltage cable for nominal voltages up to 1 kV, wherein the device has a plunger arrangement in the form of a toothed bed, wherein the toothed bed has a cutting geometry which is formed at least in part by a superposition of at least two threads (6a, 6b) with different thread characteristics introduced into the body of the toothed bed, characterized in that the at least two threads (6a, 6b) introduced into the body of the toothed bed differ in the number of thread turns.

Description

[0001] The present invention relates generally to a device for cutting the primary insulation of a conductor of a power cable, in particular a high-voltage cable for nominal voltages up to 1 kV.

[0002] The device is particularly applicable for high-voltage cables in the low-voltage range to connect one multi-conductor cable to another multi-conductor cable, the device establishing the electrical contact and the mechanical connection between the conductors of the cables without prior stripping of the cables in question.

[0003] Current is transmitted via the device according to the invention in the final assembly state. Furthermore, the device serves to increase the pull-out forces.

[0004] The invention further relates to a primary insulation-penetrating contact clamp with at least one contact screw guided in a clamping body and a device at least partially opposite the end face of the contact screw for cutting the primary insulation of a conductor of a power cable, in particular a high-voltage cable for nominal voltages up to 1 kV.

[0005] Devices for connecting an electrically insulated cable to one or more other conductors are generally known. Such devices often have at least two clamping jaws made of electrically conductive material, which are connected to a clamping element. These clamping jaws have teeth designed to penetrate the insulation when the two clamping jaws are clamped together in order to establish an electrical connection with the electrical conductors. In this context, reference is made, for example, to German patent application DE 199 29 840 A1.

[0006] One problem with connection devices known from the prior art is that they are often not designed to withstand a pull-out force that is necessary and specified for the particular application.

[0007] The pull-out force is the critical force required to pull a conductor connected to a contact via a contact terminal out of the contact when the terminal is open. The pull-out force is a quality criterion for a mechanical and electrical connection between two conductors, such as one made with a contact terminal, and is typically determined as part of a supplementary quality check using a pull-out test.

[0008] On the other hand, a wide variety of high-voltage cables are currently used in the low-voltage sector, differing particularly in their primary insulation. The term "primary insulation" as used here refers to the insulation of the individual conductors, especially in a multi-core cable, such as a four-core cable in a power supply network.

[0009] This primary insulation consists of an electrically insulating material, especially plastic and / or paper. However, it is common for the plastic materials used for primary insulation to vary from cable to cable, both in terms of the specific plastic material and / or the thickness of the insulation. Recently, there has been an increasing trend towards using cables whose conductors have only relatively thin primary insulation in order to save material.

[0010] Apart from the different strengths (thicknesses) of the plastic insulation used as primary insulation, the plastic and / or paper materials commonly used as primary insulation have different mechanical and thermal properties that influence the force required for the teeth of a contact clamp to penetrate and enter.

[0011] Since high-voltage cables of the type considered herein differ significantly in the design of their primary insulation (thickness, number and material of the primary insulation or the individual layers of the primary insulation) due to the respective applications, a challenge lies in specifying a tool, for example in the form of a contact clamp, which can be adapted as efficiently as possible to differently designed primary insulations in order to effectively penetrate the primary insulation and make galvanic contact with the conductor or inner conductor of the high-voltage cable.

[0012] Document FR 2 784 805 A1 relates to a device for cutting the primary insulation of a conductor of a power cable with the features of the preamble of independent claim 1.

[0013] Another cutting device is known from the publication DE 697 02 383 T2.

[0014] The present invention is based on the objective of providing a device for cutting the primary insulation of a conductor of a power cable, in particular a high-voltage power cable in the low-voltage range, as well as a primary-primary-insulation penetrating contact clamp with such a cutting device, wherein the cable to be processed can be held exactly, and wherein effective contact points can always be introduced into the conductor even with different thicknesses of primary insulation of the conductor and with different materials of the primary insulation of the conductor.

[0015] In particular, a cable connection device, especially for the low-voltage range, is to be specified which is simpler in design and less expensive to manufacture than known devices, and which is to guarantee a completely safe electrical connection from both an electrical and a mechanical point of view.

[0016] With regard to the cutting device, this problem is solved by the subject matter of independent claim 1, wherein advantageous further developments of the cutting device are specified in dependent claims 2 to 8.

[0017] The problem underlying the invention is further solved by a primary insulation-penetrating contact clamp according to the subject matter of dependent claim 9.

[0018] Accordingly, the invention relates to a device for cutting the layers of a conductor of a power cable, in particular a high-voltage cable, wherein the cutting device comprises a plunger blade arrangement in the form of a toothed socket. According to the invention, it is particularly provided that the toothed socket of the plunger blade arrangement has a cutting geometry which is formed, at least in some areas, by a superposition of at least two threads with different thread characteristics incorporated into the body of the toothed socket.

[0019] The cutting device according to the invention is characterized in that the at least two threads introduced into the body of the tooth socket differ in the number of thread turns.

[0020] In addition, the at least two threads incorporated into the body of the tooth socket can differ by at least one of the following thread characteristics: - Thread pitch; - Incline angle; - Flank shape; - Flank diameter; - left- or right-hand thread; and / or - Thread depth.

[0021] The term "thread" as used herein generally refers to a profiled groove that runs continuously in a helical pattern, i.e., as a screw line, in the body of the tooth socket. This continuous depression is referred to herein as the "thread pattern" on the body of the tooth socket.

[0022] The threads that form the cutting geometry of the tooth bed are preferably produced by machining, although a non-machining (forming) production of the threads is also conceivable.

[0023] The cutting device according to the invention is characterized in particular by the fact that an improved contact ratio and improved contacting of the conductor of the power cable can be achieved even over the long term by means of the special cutting geometry of the toothed socket. By a suitable selection of the thread parameters, the cutting device is suitable for power cables with varying degrees of insulation and, in particular, also for power cables with primary insulation of varying hardness and thickness. The cutting device can be manufactured with a single machine, particularly a machining machine, with different cutting geometries by machining threads with different thread parameters and / or different directions of rotation into the body of the toothed socket.

[0024] The invention further relates to a primary insulation-penetrating contact terminal with at least one contact screw guided in a terminal body and a cutting device of the aforementioned type located at least partially opposite the end face of the contact screw. This can be, in particular, a connecting terminal, i.e., one used to connect two insulated cable conductors. However, the invention is also applicable to a branch terminal.

[0025] The contact screw can be a milling screw, meaning a screw with cutting edges and slots on its face to mill away the insulation of the cable conductors and remove the milled material. Mandrels or ring cutters are also suitable.

[0026] Unlike known contact clamps of this type, the contact clamp according to the invention uses a specially designed toothing pattern opposite the end face of the contact screw. Specifically, the toothing consists of teeth or cutting edges firmly arranged in the body of the tooth socket (such as in the clamping body), the geometry of which is formed, at least in some areas, by the superposition of at least two threads with different thread characteristics that are incorporated into the body of the tooth socket.

[0027] Alternatively, it is also conceivable that the tooth socket has a cutting geometry which is formed, at least in some areas, by an overlap of at least two threads introduced into the body of the tooth socket, which are arranged in opposite directions, at least in some areas.

[0028] In this way, the cutting geometry of the tooth socket can be optimally adapted to the respective application. This results in improved contact conditions, even for conductors of a cable with varying degrees of primary insulation.

[0029] According to embodiments of the invention, the cutting geometry of the tooth socket is formed by a superposition of a first thread and a second thread, wherein the first thread has first flanks and the second thread has second flanks, wherein the first flanks run parallel to each other and form the first cutting edges of the cutting geometry, and wherein the second flanks run parallel to each other and form the second cutting edges of the cutting geometry. In particular, it is provided in this context that the first and second cutting edges of the cutting geometry run at an angle to each other.

[0030] Preferably, the flanks of the first / or second thread are designed as pointed flanks, so that even particularly hard and / or thick (strong) cable insulations can be penetrated with a relatively low contact pressure.

[0031] Of course, other flank geometries are also conceivable, such as trapezoidal flanks.

[0032] Preferably, the tooth socket is cylindrical, at least in some areas. Alternatively, connectors or tooth sockets with a non-cylindrical or non-circular internal geometry are also conceivable.

[0033] The tooth socket serves primarily to hold the power cable, especially high-voltage cables, that is to be contacted or processed. This allows the power cable to be held precisely during contacting or processing.

[0034] The primary insulation-penetrating contact clamp according to the invention is particularly suitable for insulated conductors that may be mounted under voltage.

[0035] When contacting an insulated conductor, the toothed socket with its special cutting geometry is pressed into the insulation of the conductor via the contact screw.

[0036] The special cutting geometry of the tooth socket allows in particular the formation of an "aggressive" tooth geometry, which not only ensures reliable penetration of different types of primary insulation, but also guarantees sufficiently deep penetration into the conductor of the power cable. Consequently, the device according to the invention is not only suitable for cables with different primary insulations, but also guarantees an increased (critical) pull-out force, since the special tooth geometry ensures increased mechanical fixation with the corresponding conductor of the power cable.

[0037] Finally, the invention relates to a method for manufacturing a tooth socket of a primary insulation-penetrating contact clamp, wherein a base body, in particular made of metal, is first provided and a core hole is drilled into the base body. Subsequently, a first and a second thread are drilled into the core hole. It is particularly provided that the first and second threads overlap at least partially and have different thread characteristics and / or are designed to be at least partially opposed.

[0038] The invention is described in more detail below with reference to the accompanying drawings and exemplary embodiments.

[0039] They show: Fig. 1 schematically a longitudinal section view through an exemplary embodiment of the primary insulation-penetrating contact clamp according to the invention; Fig. 2 schematically a cross-section through a contact terminal according to Fig. 1. A contact element used on a larger scale; and Fig. Figures 3a-e show schematic and isometric views of prefabricated semi-finished products for the manufacture of a contact element for a contact terminal according to the present invention.

[0040] In Fig. Figure 1 is a schematic longitudinal sectional view of an exemplary embodiment of a primary insulation-penetrating contact terminal 1 for insulated cable conductors (in Fig. (1 not shown). The contact terminal 1 of this embodiment has at least one contact screw 3 guided in a clamping body 2 and a cutting device 5 located at least partially opposite the end face 4 of the contact screw 3. This cutting device 5 is occasionally also referred to as a "contact element".

[0041] The clamping body 2 of the contact terminal 1 can - as in Fig. Figure 1 shows a hollow cylindrical sleeve in which corresponding threaded holes are formed, in which the contact screws 3 are guided. The contact screws 3 may be provided with milled slots on their end face 4, although this is not essential to the invention.

[0042] Each contact screw 3 is opposite a cutting device 5 in the form of a contact element, which, for example, has the shape of a small droplet or cup with a toothed socket. The toothed socket comprises a cutting geometry as shown below with reference to the illustration in Fig. Sections 3a to 3e are described in more detail using examples.

[0043] The contact element 5 can preferably be made of a copper alloy, which results in a certain degree of inherent springiness. Of course, other materials are also conceivable, such as aluminum.

[0044] The cutting geometry of the tooth socket of the contact elements 5 is formed, at least in some areas, by a superposition of two threads with different thread characteristics that are incorporated into the body of the tooth socket. In particular, in the Fig. The holding tools 7 shown in Figures 3a to 3e are provided to form the cutting geometry of the tooth socket at least in some areas by an overlap of two threads 6a, 6b introduced into the body of the tooth socket, wherein these threads 6a, 6b are designed to run in opposite directions at least in some areas.

[0045] Specifically, the semi-finished product 7 is described according to Fig. 3a the cutting geometry is formed by a first left-hand thread 6a with a 5 mm pitch and three threads and by a second right-hand thread 6b with a 5 mm pitch and three threads.

[0046] In the embodiment according to Fig. 3b is the cutting geometry in the semi-finished product 7 formed by a first left-hand thread 6a with a 7 mm pitch and a second right-hand thread 6b with an 8 mm pitch and six threads.

[0047] In the embodiment according to Fig. 3c is the cutting geometry in the semi-finished product 7 formed by a first left-hand thread 6a with a pitch of 20 mm and a second right-hand thread 6b with a pitch of 20 mm and three threads.

[0048] In the embodiment according to Fig. 3d involves an overlap of left- and right-hand threads 6a, 6b, each with a pitch of 10 mm, and in the embodiment according to Fig. 3e uses an overlap of left- and right-hand threads 6a, 6b, each with a pitch of 15 mm.

[0049] The semi-finished products 7, as schematically shown in the Fig. Figures 3a to 3e are shown and can be manufactured with a single machining device, whereby different cutting geometries and, in particular, cutting geometries adapted to the respective application of the contact terminal 1 can be realized by varying the thread pitch, the thread pitch, the helix angle, the flank shape, the flank diameter and / or the thread depth.

[0050] The invention is not limited to the embodiments shown in the drawings, but results from a combination of all the features disclosed herein.

[0051] The contact clamp 1 according to the invention is particularly suitable for cable conductors of different diameters. Reference symbol list 1 contact terminal 2 clamping bodies 3 contact screws 4. Front side of the contact screw 5 Cutting device / contact element 6a first thread of the cutting geometry of the cutting device 6b second thread of the cutting geometry of the cutting device 7 Semi-finished product for the manufacture of the cutting device

Claims

Device for cutting the primary insulation of a conductor of a power cable, in particular a high-voltage cable for nominal voltages up to 1 kV, wherein the device has a plunger arrangement in the form of a toothed bed, wherein the toothed bed has a cutting geometry which is formed at least in part by a superposition of at least two threads (6a, 6b) with different thread characteristics introduced into the body of the toothed bed, characterized in that the at least two threads (6a, 6b) introduced into the body of the toothed bed differ in the number of thread turns. Device according to claim 1, wherein the at least two threads (6a, 6b) provided in the body of the tooth socket further differ by at least one of the following thread characteristics: - thread pitch; - helix angle; - flank shape; - flank diameter; - left-hand or right-hand thread; and / or - thread depth. Device according to claim 1 or 2, wherein a first thread (6a) of the at least two threads (6a, 6b) introduced into the body of the tooth socket has first flanks and a second thread (6b) of the at least two threads (6a, 6b) introduced into the body of the tooth socket has second flanks, wherein the first flanks run parallel to each other and form first cutting edges, and wherein the second flanks run parallel to each other and form second cutting edges. Device according to claim 3, wherein the first and second cutting edges are inclined to each other. Device according to claim 3 or 4, wherein the first and / or second flanks are designed as pointed flanks. Device according to one of claims 3 to 5, wherein at least one flank of the first and second flanks is designed as a trapezoidal flank. Device according to one of claims 1 to 6, wherein the tooth socket is at least partially cylindrical. Device according to one of claims 1 to 7, wherein at least one thread (6a, 6b) and preferably all threads (6a, 6b) introduced into the body of the tooth socket are introduced into the body of the tooth socket by a machining manufacturing process. Insulation-penetrating contact clamp (1) with at least one contact screw (3) guided in a clamping body (2) and a device for cutting the layers of a conductor of a power cable, in particular a high-voltage cable, at least partially opposite the end face (4) of the contact screw (3), wherein the device is a device according to one of claims 1 to 8. Contact clamp (1) according to claim 9, wherein the tooth bed has a surface opposite the end face (4) of the contact screw (3) that is at least partially concave, in which the cutting geometry is incorporated. Method for producing a tooth socket of an insulation-penetrating contact clamp (1), in particular an insulation-penetrating contact clamp (1) according to claim 9 or 10, wherein the method comprises the following process steps: - providing a base body, in particular made of metal; - producing a core hole in the base body; - producing a first thread (6a) in the core hole; and - producing a second thread (6b) in the core hole; wherein the first and second threads (6a, 6b) overlap at least partially and differ in the number of thread turns.

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