GB2063580A

GB2063580A - A device for stripping the outer insulation from a circular cable

Info

Publication number: GB2063580A
Application number: GB8010285A
Authority: GB
Original assignee: Siemens Telefongyar Kft
Current assignee: Siemens Telefongyar Kft
Priority date: 1979-11-16
Filing date: 1980-03-27
Publication date: 1981-06-03
Also published as: FR2469814A1; SU927136A3; CS215137B2; FR2469814B1; SE8002605L; PL227874A1; PL134738B1; DE3015606A1; DD152447A5; HU178768B; DE3015606C2; CH651426A5; GB2063580B

Abstract

The present invention relates to a device for stripping the length of the outer insulation of cables having a circular cross-section and to a method of using the device. In order to avoid the problems of known stripping devices which are not self-centring, a stripping device is provided which comprises cutters 1, having curved edges 1b, and being arranged in pairs, each pair of cutters being movable in a radial groove of a holder 2. Control cams 3 are provided which have cam grooves 3a in the form of curved slots. The slots 3a serve to move the cutters 1 by means of guide pins 1a provided on each cutter. In use, relative rotation between the cam plates 3 and the holder 2 causes the cutters 1 to move in the radial grooves of the holder 2, whereby the cutters 1 cut into the outer insulation of a circular cable which has previously been inserted into the device along the axis of the device. The cam slots may follow a logarithmic spiral. <IMAGE>

Description

SPECIFICATION A device for stripping the outer insulation from a circular cable The invention relates to a device for stripping a length of the outer insulation of cables having a circular cross section and to a method of using the device.

A known stripping device provided with several cutters has been described in British Patent Specification No. 1,289,936. In this known device, me cutter edges are arranged in a common plane and the cutters are rotated around the cable by repeatedly describing a full circle. The device is not self-centring and in the event of faulty adjustment, the cutters are over-rotated, cut deeper than the thickness of the outer insulation to be stripped, causing damage to the insulation layers of the inner wires. Such damage can affect the impedance.

In accordance with the present invention, there is provided a device for stripping the outer insulation from a circular cable, comprising cutters having curved cutting edges, a cutter holder on which the cutters are movably mounted, the cutter edges being arranged in the same plane as each other, a pair of cam plates arranged one on each side of the cutter holder and formed with curved cam surfaces co-operating with the cutters to move the curved cutting edges inwards and outwards in response to rotation relative to the cutter holder, a housing containing the pair of cam plates and the cutter holder and fast in rotation with the pair of cam plates or the cutter holder, an operating lever for rotating the cutter holder or the pair of cam plates, respectively, relative to the housing and an abutment for limiting the relative movement of the cam plates and the cutter holder to limit the inwards movement of the cutter edges.

In using the device described above, a cable is inserted into the device along the axis and the abutment is adjusted to determine the inwards movement of the cutting edges.

Thereafter the operating lever is rotated relative to the housing until it reaches the abutment to cut through the outer insulation forming an incision bounded by a polygon having curved sides. The invention is based on the recognition of the fact that the polygonal circumference formed by the individual cutting edges results in a self-centring effect arising from the transfer of the force to the cutting edge meeting the least resistance.

Consequently, by using the device of the present when cutting the outer insulation of a cable having an uneven surface, the inner insulation does not get damaged, the cutters penetrating the outer insulation being adjustable to the size needed for the highest operational safety.

Furthermore, the invention is based on the recognition of the fact that the polygon with curved sides can be formed by the motion of movable cutters and the device for forming the polygonal circumference can be modelled on a chuck. The force in the angles of friction for the optimum angle of pressure can easily be determined.

The literature relating to the optimum angle of pressure may be found in Chapter 7 of the book entitled "Principles of Mechanics" by L.

Buzas, published by the Technical University of Budapest. Accordingly, assuming a constant angle of pressure, maintenance of the optimal value of the same under given kinetic circumstances, based on the known principle, can be obtained by forming the cam grooves in accordance with a logarithmic spiral. The relating literature can be found in the book of dr. Kalaszi, entitled "Technology of Machine Building", Part Ill, Mass production. Profiles confined by polygonal circumferences are mostly used at shaft couplings between mechanical elements, being most advantageous when compared to splined shaft couplings.

The invention is also based on the fact that the polygon with curved sides formed by the motion of the movable cutters remains concentric even after having been rotated. A reference to this phenomenon may be found on pages 237 to 238 of the Technical Encyclopaedia, publication of the Academy of Budapest, 1970; its mathematical confirmation is contained in the Transaction of the Professorate Mechanical Elements of the Technical University of the Heavy Industry, Miskolc, entitled "Applicaton of the polygonal profile in practice", published 1 973.

The geometry of the polygons have been described in the publications of Prof. Dr.

techn. R. Musyl, Graz/Macshinenbau 1975/1/2, Konstruktion 1962/6/, from which it becomes obvious, that on the polygonal arches transfer of the moment can be advantageously realised.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an exploded view of the cutters, the holders and the elements controlling the movements of the cutters; Figure 2 shows the mutual position of the cutters in an assembled state; Figure 3 is a fragmentary part-sectional view of the assembled stripper, also showing a cable arranged in the bore; and, Figure 4 shows a sectional view of singlecore or multi-core cables provided with a multiple insulation after having been stripped.

The invention will first be described by identifying the reference numerals in the figures. In Fig. 1, number 1 indicates the cutters, number 2 designates a holder for the cutters, 3 refers to control cams and 3a to cam grooves in the control cams. In order to facilitate comprehension, the centre line (no reference numeral) is also shown, passing through the components in accordance with the order of assembly.

In Fig. 2, the cutters 1 have been illustrated, the reference ''f'' standing for the flat surface of the cutters, ss denotes the sharpening angle of the cutters.

The reference numerals of the components shown in Fig. 3 will be explained in connection with the assembled parts and the fragmentary part-sectionai view, respectively.

Number 1 indicates the position of the cutters. Number 2 relates to the holder, 3 to the control cams and 4 to a cylindrical housing.

Numeral 4b indicates the coupling known in itself, 5 stands for an operating lever for effecting mutual rotation between the cutter holder and the pair of cam plates, 6 indicates a strap for adjusting the distance by which the movable cutters may be displaced, 6a indicates a fixing screw for fixing the adjustment strap 6 into a desired position and 7 refers to the cover on the cylindrical housing.

Fig. 4 shows the general arrangement of the cable cross-section, in which ss D stands for the total outer diameter of the cable, d stands for the diameter of the leading core of the cable or in case of a multi-core cable for the diameter of an inner thinner cable, ss D1 stands for the polygonal circumferential line, resulting from ss D after having performed the procedure by using the device according to the invention.

The operation of the illustrated embodiment of the invention will now be described.

Fig. 1 shows the moving components arranged in their mounting positions. The holder 2 is provided with radial grooves which lie perpendicular to each other. The movable cutters 1, having curved edges 1 b, are arranged in pairs, two cutters being movable in each of the radial grooves. Furthermore, cams 3 are provided, the plane of each cam being parallel with the plane of the holder. Each of the cams 3 is provided with a curved slot 3a which serve to move the cutters 1 by means of guide pins 1 a provided on each of the cutters.

Fig. 2 shows the cutters in their mutually assembled position in the holder 2.

In Fig. 3, the arrangement is shown in a fragmentary part-sectional view. A cylindrical housing 4 houses the holder 2 with the cams 3 arranged parallel to one another on each side of the holder. The cam plates 3 are connected to the housing 4 by any suitable connection, in this case screws 4b. The cutters 1, the cutting edges 1 b of which are in a single plane, may move in the radial and mutually parallel grooves of the holder 2. The guide pins 1 a of the cutters 1 are arranged in the curved slots 3a of the cam plates 3. The holder 2 is freely located between the fixed cam plates 3 by means of the guide pin 1 a of the cutters 1. An operating lever 5 is connected to a flange of the holder 2 in a known manner, and by moving the operating lever 5 the holder 2 may be displaced, while the cutters 1 are seated in the curved slots 3a of the cam plates 3.When the holder is displaced, the cutters are also displaced in an arc, corresponding to the arc of the slots 3a, and cut into the outer insulation of a circular cable which has previously been inserted into the device along the axis of the device. The depth of the incision may be adjusted according to the particular requirements of any cable by means of the strap 6, and may be fixed in a desired position by the fixing screws 6a.

In Fig. 4, the general sectional view of a cable may be seen, where D stands for the total outer diameter of the cable, D, for the polygonal line confined by the arcs to be obtained by using the device in accordance with the invention, while d indicates the other insulated cores of the cable. The outer insulation layer which has been stripped using a device embodying the invention corresponds to the layer thickness between D and D1, and it can be seen that the insulation layer of the cores inside the cable are not damaged.

Claims

1. A device for stripping the outer insulation from a circular cable, comprising cutters having curved cutting edges, a cutter holder on which the cutters are movably mounted, the cutter edges being arranged in the same plane as each other, a pair of cam plates arranged one on each side of the cutter holder and formed with curved cam surfaces cooperating with the cutters to move the curved cutting edges inwards and outwards in response to rotation relative to the cutter holder, a housing containing the pair of cam plates and the cutter holder and fast in rotation with the pair of cam plates or the cutter holder, an operating lever for rotating the cutter holder or the pair of cam plates, respectively, relative to the housing and an abutment for limiting the relative movement of the cam plates and the cutter holder to limit the inwards movement of the cutter edges.

2. A device for stripping the outer insulation from a circular cable as claimed in Claim 1, wherein the holder is provided with two radial grooves on each side in which grooves the cutters are slidable, and in which each cam plate comprises two cam slots each following a logarithmic spiral, each cam slot being associated with a respective cutter.

3. A method of stripping a cable by means of a device as claimed in Claim 1 or Claim 2, which comprises inserting a cable into the device along the axis of the device, adjusting the abutment to determine the inwards movement of the cutting edges and rotating the operating lever relative to the housing until it reaches the said abutment to cut through the outer insulation, making an incision bounded a polygon having curved sides.

4. A device for stripping the outer insulation from a circular cable, constructed, arranged and adapted to operate substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.