US2686359A - Method of attaching hauling lines to the ends of tubes - Google Patents

Description

Aug. 17, 1954 J. A. SPENCER 2,686,359

METHOD OF ATTACHING HAULING LINES TO THE ENDS OF TUBES Filed Jan. 23, 1951 5 Sheets-Sheet l Inventor James/Yrizzrkeacer A ttorneyg Aug. 17, 1954 J. A. SPENCER 2,686,359

METHOD OF ATTACHING HAULING LINES TO THE ENDS OF TUBES Filed Jan. 23, 1951 s Sheets-Sheet 2 F/GS. /4

- [I Inventor 1954 J. A. SPENCER 2,686,359

METHOD OF ATTACHING HAULING LINES TO THE ENDS OF TUBES Filed Jan. 23, 1951 3 Sheets-Sheet 3 .1" I W I, h

M48 42 43 so F/G 7. 2 30 "WNW" ai fi H 11 AQ/LW'H I] /O/ 40 31939 34 3 Inventor (/1227: es {721% 20 Spencer Attorney 5 Patented Aug. 17, 1954 METHOD OF ATTACHING I-IAULING LINES TO THE ENDS OF TUBES James Arthur Spencer, Erith, England, assignor to British Insulated Callenders Cables Limited, London, England, a British company Application January 23, 1951, Serial No. 207,284

Claims priority, application Great Britain February 9, 1950 1 Claim.

This invention relates primarily, but not exclusively, to the manufacture of electric cables and deals particularly with the application of the sheath by the method of pulling the cable body into an oversize tube and then drawing down the tube to make it an appropriate fit on the cable body inside it. This method is usually adopted at the present time only for sheaths of aluminium or aluminium alloy. The method comprises the steps of laying the tube out in an approximately straight line, pulling the cable body into the tube and then drawing down the tube. This method is described more fully in co-pending United Kingdom application 3,383/50.

For pulling the tube into position, and for drawing down the tube, it is necessary to make an attachment to one end of the tube. The invention deals with this and it will be seen that the method of making this attachment, and the form of the attachment, are also applicable for other drawing operations performed on tubes.

In accordance with the invention the attachment is carried out by placing that end of a drawbar, having a shoulder at or near its rear end, within the end part of the tube, with or without a cable body attached to it according to the requirements of the case, and symmetrically deforming the end part of the tube round the drawbar to bring it to a smaller effective internal diameter, forming in the centre a hole through which the draw-bar projects. The draw-bar here referred to may be a rigid bar or a flexible wire rope.

The preferable method of deformation of the end part of the tube is by radially inward compression at three or more equidistant places, preferably four places, carried out so as to produce a shape of tube, when seen in cross-section, consisting of three or more symmetrical lobes between which the wall of the tube approaches the axis of the tube to the desired extent for defining the aperture for the draw-bar. The deformation is substantially uniform over a sufficient axial length of the end part of the tube, which may be from one to two diameters, and from this end part it makes a gradual transition to the full diameter and circular form of the tube. The shouldered end of the draw-bar is located within the transition part and exerts a pull by pressing on this part.

It is found that with this type of end deformation and arrangement of draw-bar a sufliciently strong attachment to the tube is made. At the same time the deformation may produce a local overall reduction in the size of the tube. It will be appreciated that for the drawing operation the shouldered part at the rear of the draw-bar must be of such a size that the part of the tube within which it lies can pass through the die.

The invention will be described further with the aid of the accompanying drawings illustrating the method of attachment and various devices suitable for use in carrying out the method.

Figure 1 is a longitudinal view in elevation, partly in section, in which the end of the tube is crimped round a draw-bar.

Figure 2 is an end elevation of the crimped tube shown in Figure 1 with the draw-bar shown in section.

Figure 3 is a longitudinal view in elevation of the crimped tube.

Figure 4 is a side elevation, partly insection, and with certain parts shown broken away, of a crimping tool.

Figure 5 is a section on the line VV of Figure 4 looking in the direction of the arrows.

Figure 6 is a side elevation of the one of the jaws of the crimping tool and drawn to a larger scale.

Figure 7 is a longitudinal view in elevation, partly in section.

Figure 8 is a longitudinal view in section drawn to a larger scale.

Figure 9 is a rear end elevation of a detail.

The invention has been developed in connection with the application of an aluminium sheath to an electric cable body and will now be described in that connection. The process involves the pulling of a tube from its coiled state on a drum through a straightening device and carrying it forward until it is laid out in place to receive a cable body. In Figure 1 there is shown a method of attachment whereby that operation may be readily carried out. The reference numeral l indicates a hauling line and 2 indicates one end of a tube to which the attachment is to be made. To effect the attachment, a simple draw-bar 3 is used. This has at its rear end a threaded portion 4 upon which is screwed a collar or nut 5 which may be cylindrical or other convenient and appropriate shape. This collar provides a shoulder which is adapted to bear upon a number of internal abutments formed subsequently within the end 2 of the tube.

The draw-bar 3 with the collar 5 in position is inserted into the end of the tube for an appropriate distance and the end of the tube is then subjected to a crimping operation which provides the tube with a number of internal projections. The crimping is carried out by the tool shown in Figures 4 and 5 which is so designed as to be capable of exerting radially inward compression upon the tube at four places equally spaced around the circumference of the tube 2. The effect of the crimping of the tube is shown in Figores l, 2 and 3. As will be seen from Figure 2 the crimping operation results in so shaping the tube as to form four symmetrical lobes 6 between which the wall of the tube approaches the axis of the latter as indicated at 1. These latter portions I define an axially placed aperture 8 through which the draw-bar projects as indicated in Figure 1. From the latter figure it will also be seen that the portions 1 of the tube which lie in close proximity to the surface of the draw-bar extend longitudinally of the latter for a substantial length. From the portions I rearwardly thereof, the end part of the tube 2 makes a gradual transition, as indicated at 9 in Figure l, to the full diameter and circular form of the tube. The shouldered end of the draw-bar 3, as provided by the collar 5 thereon is disposed within the transition parts 9 and exerts a pull on the tube 2 by pressing on those parts.

To the front end of the draw-bar 3 is connected a shackle I and to the latter is connected the hauling line I. The front end of the drawbar 3 has an enlarged head I I for engagement by the shackle. The latter and the hauling line I are shown in Figure 8 and the shackle will be referred to later with reference to that figure and also to Figure 9.

The crimping tool shown in Figures 4 and 5 comprises four circumferentially and equally spaced jaws I2 which are mounted for radial sliding movement between two end plates I3. Each jaw is adapted to be forced inwards by the turning of a cam ring I4 in a clockwise direction as seen in Figure 4. The cam ring has four cam surfaces I5, one being provided for each jaw. Connection is made between the jaw and its cam surface by arranging for the latter to bear upon a roller I6 mounted upon a spindle I'I passing through extensions I8 of the tool and through narrow slots I9 formed in the end plates I3. The rollers I6 are maintained in contact with their respective cam surfaces I5 by springs 20 a pair being connected to each spindle at its ends and to pins 2| attached to the end plates I3. The latter are held in spaced relationship by a series of bosses 23 provided on the inner surface of each end-plate and by bolts 24 which pass through the end plates and bosses and have nuts 25. In Figure 5 the lines 26 indicate the meeting faces of the two sets of bosses. I3 has a circular aperture 21. The two apertures are arranged opposite each other and provide for the entry of the end of the tube to be crimped. On turning the cam ring I4 in the appropriate direction the four jaws I 2 are forced radially inwards against the surface of the tube to deform the latter in the manner described above. Each jaw has a rounded inner end 28 and rounded off corners 29 as indicated in Figure 6.

In the application of an oversize sheath to a cable body, the tube which will subsequently form the cable sheath, may be drawn off a drum and the tube laid out in a straight line, by the arrangement shown in Figure 1.

After the tube has been drawn off the drum, the deformed end of the tube is then cut off behind the shouldered end of the draw-bar so as to leave the tube open at its full diameter at that end. A hauling device of a kind different from that shown in Figure 1 is then attached Each end plate 4 to the conductor, or group of conductors, at the leading end of the cable body. This method of attachment will now be described with reference to Figures '7 and 8.

In Figure 7 there is shown a cable body comprising stranded conductors 30 provided with insulation 3 I, the latter having been removed from the ends of the conductors so as to expose the latter for a suitable length. Over the lending ends of the conductors there is placed a metal cylindrical sleeve 32. This sleeve has an outer diameter not greater than that of the insulation 3| and preferably is slightly less than the outer diameter of the insulation. The inner surface of the sleeve 32 comprises a serrated portion 33 and at its leading end the sleeve has a wall 34 of substantial thickness. Extending through that wall is an axially disposed passage 35, the wall of which is screw-threaded. Through this passage there extends a bar 36 having a screw-threaded portion 3'! and terminating at its rear end in a pointed portion 38. When the bar 36 is screwed through the end wall of the sleeve, the pointed portion is forced between the conductors 30 to force the latter outwards into tight contact with the serrated portion 33 of the sleeve 32, thus making a tight and secure connection between the bar 36 and the conductors 30. A collar 39 on the bar 36 has flats 50 to facilitate turning of the bar. The front end of the bar 36 has an enlarged head 40 for engagement by a shackle I0 provided with a hauling device I. By the aid of the latter, the cable body may now be drawn through the tube 2 to bring it into the position shown in Figure 7.

The shackle l0 shown in Figures 1, '7, 8 and 9 has in its side face a recess 4| which is open at the rear end of the shackle. In front of the recess 4| is a larger recess 42 also open on the side face of the shackle and communicating with the recess M, the two recesses forming between them an internal shoulder 43 forming an abutment for the head 40 of the bar 36. In Figure l, the shoulder provides an abutment for the head II of the draw-bar 3. A swivel connection is provided between the heads I I and the shackle II) in Figure 1 and between the head 40 and the shackle in Figure 8 by making the heads II and 40 of cylindrical shape and similarly shaping the bottom surfaces of the recesses in the shackle. The latter are shown at 44 and 45 respectively in Figure 9. The leading end of the shackle II] has a pin 48 which passes through an eye 4'! of the hauling device I, the eye being disposed in a slot 42 in the leading end of the shackle II).

The cable body may comprise a single conductor in which case the pointed portion 38 of the bar 36 will be utilised to force the strands thereof into secure contact with the serrated portion of the sleeve 32.

In Figure 7, the cable body is shown as having been drawn through the tube 2, the method of attachment made between the hauling device I and the cable body shown in Figure 8 having been utilised. In Figure 7 is shown the method of attachment made between the hauling device I, the cable body and the tube 2 whereby the cable body and the tube can be together drawn through a die to reduce the diameter of the tube to cause it to make a close fit with the cable body. In this case the end of the tube 2 is subjected to a crimping operation to form a number of internal projections as described above in connection with Figures 1, 2 and 3 and the shoulder which abuts against those projections is provided by the leading end of the shackle H) which is indicated by the numeral 48. In Figure '7 the draw-bar 3 of Figure 1 around which the tube 2 is crimped is replaced by the hauling device i which is a flexible wire rope and serves as a draw-bar.

In Figures 1 and 7 the crimping of the tube is accompanied by a reduction in diameter over the crimped portion. This is shown in Figure 3 and facilitates the introduction of the end of the tube into this straightening die or the drawing down die.

In Figure '7, the pulling of the cable body into the tube 2 is effected by a movement of the cable body from right to left and the dieing down of the tube on to the cable body is effected by a movement in the same direction. If, however, the dieing down is to be effected by a movement in the opposite direction, a hauling device must be attached at the opposite end of the cable body and the adjacent end of the tube crimped around the hauling device. The attachment to the cable body may be effected during the preparation of the cable for drawing in or at some other stage.

The hauling device I may form part of a towing line or it may be a strap having an eye at each end to the leading end of which a towing line may be connected.

What I claim as my invention is:

In the method of attaching a hauling line to an end of a tube of relatively soft metal so that the tube may be subsequently drawn off in an axial direction from a drum and be laid out on a support in a substantially straight line, placing that end of an elongated member having a shoulder located adjacent one end thereof within the end part of the tube, the said elongated member being of substantially smaller dimensions in cross-section than the diameter of the tube, and then subjecting the end of the tube to a substantial work-hardening operation by exerting radially inwardly directed pressure upon the outer surface of the tube simultaneously at a number of places spaced uniformly around the circumference of the tube, thereby forming a corresponding number of relatively wide and deep grooves separated by portions forming narrow ridges, and simultaneously reducing the efiective diameter of the tube Without deforming the elongated member, the grooves and ridges extending longitudinally of the tube substantially parallel with th axis thereof, and the grooves at their inner ends increasing in diameter to the full diameter of the tube, the said inner ends forming a number of internal shoulders for the abutment of the shoulder located adjacent the end of the elongated member when the latter is subjected to longitudinal tension, and the inner surfaces of the grooves combining to form a substantially axially disposed passage for the elongated member and through which the latter projects.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 378,976 Ritchie Mar. 6, 1888 880,563 McTear Mar. 3, 1908 1,761,521 Eastman June 3, 1930 2,002,220 Douglas May 21, 1935 2,182,663 Eby et a1. Dec. 5, 1939 2,405,201 Franck Aug. 6, 1946 2,480,280 Bergan Aug. 30, 1949

Images