The present invention relates to a method of fixing a ferrule onto a laid-up cable.
Conventionally in window regulators, automobile and horticultural machines and the like, ferrules for use in Bowden cables and the like have been crimped or soldered onto the cable. Such arrangement does not permit ready replacement of the cables outside well equipped factory or workshop premises, due to the requirement for a press or the like to form the crimp.
Surprisingly, I have been able to bond cables into plain bore metal ferrules which have been internally roughened as by threading with a self tapping screw. This is a delicate operation.
I have noted US patent application No. 2004/088847, whose abstract is as follows:
A wire rope and socket combination comprises a wire rope socket, a rope formed of strands of twisted wires extending into the wire rope socket, selected strands of the twisted wires being bent over 180 degrees within the wire rope socket to provide a selected breaking strength; and babbit securing the rope in the wire rope socket. A method of constructing a wire rope socket, the method comprising the steps of: bending selected strands of a rope formed of twisted wires over 180 degrees to form bent strands; inserting the rope and bended strands into a wire rope socket; and pouring molten babbitt into the wire rope socket to secure the rope in the wire rope socket.
Bending back strands of a cable, particular a small diameter cable as used in a window regulator is awkward to my mind.
The object of the present invention is to provide an improved method of fixing a ferrule on a cable.
According to one aspect of the invention there is provided a method of fixing a ferrule onto a laid-up cable, the method consisting in the steps of:
According to another aspect of the invention, there is provided a kit of parts comprising:
The cable can be of polymeric material, but will normally be of metal, preferably stainless steel. The ferrule can be of polymeric material or other engineering materials, but will normally be of metal, typically stainless steel, aluminium or copper. The adhesive will normally be of the type setting by polymeric action, typically a two part epoxy type or other high strength adhesive. Solder may be used as the adhesive where the materials of the cable and the ferrule are compatible with solder.
The ferrule can be evenly tapered internally, possibly with a straight bore section at one or other end. Alternatively, the ferrule can be stepped with one or more steps in its internal bore.
The invention is particularly applicable to repair of the cables of a window regulator in an automobile, in which case the ferrules and the cable are sized and shaped to be used in a window regulator.
To help understanding of the invention, specific embodiments thereof will now be described by way of example and with reference to the accompanying drawings, in which:
Referring to the drawings, a multi-strand stainless steel cable 1 typically of 1.5 mm diameter has a ferrule 2 threaded on it—that is threaded in the manner of a needle on a thread as opposed to screw-threaded. The ferrule is of polypropylene and has a stepped bore, with a small bore portion 3 and a large bore portion 4. The ferrule is 4.2 mm in outside diameter and 6.00 mm in length. The small diameter bore portion is 2 mm long and 1.7 mm in internal diameter, whilst the large diameter bore portion is 4 mm long and 2.7 mm in internal diameter. The large diameter portion is arranged at the end of the ferrule adjacent an end 5 of the cable.
To secure the ferrule to the cable, at its end the latter is first cleaned with isopropyl alcohol to remove any lubricant remaining from its laying up. For a short length of approximately twice the length of the ferrule, the cable is unlaid at its end 5. The result is that the strands of the cable splay out, typically beyond the external diameter of the ferrule. Epoxy resin 6, suitably BONDMASTER available from www.glueline.co.uk, is applied to the cable at the ferrule and the splayed end. To ensure that the adhesive is coating the cable as it passes through the ferrule and the internal bores of the ferrule, this is worked back and forth along the cable. When the adhesive is well distributed, the cable is drawn through the ferrule to introduce the splayed end into the larger diameter portion. Normally the cable will tighten on the smaller diameter portion at the beginning of the splaying, with the splayed strands resting against the large diameter bore at the orifice 7 of this. At the step 8 between the diameters, the adhesive will have been drawn in to occupy any air space that would exist between the cable and the ferrule in the absence of the adhesive. It should also be noted that the use of the large bore portion increases the surface area within the ferrule for the adhesive to adhere to.
Alternatively, it is possible to draw more of the cable through the ferrule, once the cable has tightened on the smaller diameter portion at the beginning of the splaying. The can be achieved particularly by turning the cable in the direction of the twist/lay of the strands. This partially reforms the cable allowing it to be withdrawn into the small bore portion while keeping the cable splayed within the large bore portion. This can allow the drawing of the cable until the splayed end is flush with the end of the ferrule. In addition, this process will squeeze the adhesive out from between the stands helping to fill the internal bores of the ferrule and exclude any air pockets.
Once the adhesive has set, the ferrule will be secured to the end of the cable, with sufficient strength for normal use of the cable, due to mechanical locking of the splayed end and adhesive combination in the stepped ferrule, even if the waxy nature of the polypropylene should tend to inhibit adherence with the ferrule as such. The cable can be trimmed back to the length of the ferrule at 9.
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Number | Date | Country | Kind |
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0800782.5 | Jan 2008 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/GB2009/000139 | 1/16/2009 | WO | 00 | 8/25/2010 |
Number | Date | Country | |
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61063137 | Feb 2008 | US |