Plastic and nonmetallic article shaping or treating: processes – With printing or coating of workpiece – Coating or impregnating workpiece before molding or shaping...
Patent
1979-11-07
1983-01-04
Pavelko, Thomas P.
Plastic and nonmetallic article shaping or treating: processes
With printing or coating of workpiece
Coating or impregnating workpiece before molding or shaping...
156173, 156195, B29D 2312
Patent
active
043671896
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to plain bearings and methods of making them, and one object is to provide a method of making an improved marine stern tube bearing.
2. Description of the Prior Art
Such bearings have been manufactured in the past from asbestos yarn impregnated with a resin, but that material has not been easily machined to fit the shaft with which it is to be used, and in any case it is undesirable to use asbestos in machining operations.
SUMMARY OF THE INVENTION
According to the present invention in a method of making a bearing tube, fibre carrying a sticky resin, is wound on a former and a wear resistant compound is added to the sticky resin, and then the resin is caused or allowed to solidfy.
The fibre which may be in the form of a number or bunch of fibres, possibly of polyacrylonitrile, can be passed through a bath containing the resin, for example an epoxy, phenolic, polyester, or cresylic, resin, and wound around the former so that the resin will cause the fibres to stick together to build up the complete bearing which is conveniently in the form of a tube. If the wear resistant compound is added at the point of winding of the resin-carrying fibre, for example, in the form of a powder, which may includes one or more of the components P.T.F.E. (polytetrafluoroethylene), graphite and bronze, the wear resistant compound will be carried into the body of the tube, and thus will be well distributed throughout the body of the tube, and leaves a tube which can be effectively machined to size while still leaving a good finish.
It is of course also possible for the wear resistant compound, possibly in the form of a powder, to be included with the resin in the bath, but then the compound may not be added uniformly as the fibre is wound, and so it is preferred that the compound is added in powder form at a controlled rate at the point of winding so that the addition will be at a uniform rate.
A preferred wear resistant compound includes between 50% and 70% by volume of P.T.F.E., between 10% and 30% by volume of graphite, and between 10% and 30% by volume of bronze, or of tin/bronze.
The invention includes a bearing including wound fibres bonded together by a resin which incorporates a wear resistant compound, conveniently the compound being in particle or powder form, substantially evenly distributed throughout at least the part of the bearing adjacent a bearing surface.
The amount of the wear resistant compound is conveniently between 5% and 20% by volume of the bearing material which itself includes between 30% and 70% by volume of the sticky resin, and between 20% and 60% by volume of the fibre. The fibre can, for example, be polyacrylonitrile fibre sold under one of the Trade Marks "Courtelle", "Acrilan", and "Orlon".
One advantage of the bearing described is that it is resistant to oils and sea water without undue swelling.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be carried into practice in various ways, and one embodiment will now be described by way of example with reference to the accompanying drawings; of which:
FIG. 1 is a sketch with parts cut away of a stern tube bearing made in accordance with the invention for a marine propeller shaft; and
FIG. 2 is a sketch showing the tube of FIG. 1 being made.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 2, it can be seen how a mandrel or former 5, supported by a tail stock 2, is rotated by a motor and head stock 1, while fibres 8 are wound around the former. The fibres 8 first pass through a bath 7 of a sticky resin, and then, covered with the sticky resin, are led through a guiding head 4 to a point adjacent the surface of the rotating former. The head 4 is reciprocated along a guide 3 in synchronism with the rotation of the former from the head stock 1, so that the bundle or web of fibres 8 are wound in a desired wave form, as indicated generally in FIG. 1.
Immediately after the fibres have been laid on the former, wear resistant powder is applied
REFERENCES:
patent: 3623930 (1971-11-01), Grosh
patent: 3635256 (1972-01-01), McLarty
patent: 3965235 (1976-06-01), White
patent: 4021415 (1977-05-01), Chang
patent: 4077828 (1978-03-01), Strom
patent: 4080233 (1978-03-01), McCloskey
Associated Engineering Public Limited Company
Pavelko Thomas P.
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