Metal working – Means to assemble or disassemble – Puller or pusher means – contained force multiplying operator
Patent
1984-02-27
1986-11-18
Rosenbaum, Mark
Metal working
Means to assemble or disassemble
Puller or pusher means, contained force multiplying operator
264273, 26432212, 301105R, 301 63PW, B21K 140
Patent
active
046227318
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for the production of a hub for a spoke-wheel, particularly of the kind intended for use in a wheelchair.
When manufacturing a hub for a spoke-wheel, the conventional technique is to manufacture the hub of metal in such a manner that the hub is given a tube-shaped central part with flanges at both ends. These flanges have holes for securing of the spokes. When hubs are manufactured for bicycles these hubs are produced in large series, therefore the tooling cost for them is of lesser importance.
For bicycle hubs and for hubs in similar two-wheeled vehicles the bearings of the wheel axles are often designed in such a manner that the tube-shaped central portion of the hub is provided with bearing cups being open towards the ends of the hub, such bearing cups receiving often without ball races a number of ball-bearing balls. The wheel axles pass through and are threaded; they have screwed-on bearing bodies that are approximately conical, which work together with the balls installed in the cups and which are held there by means of check-nuts. This design is simple and cheap to manufacture, but is less suitable, for example, in a wheelchair. The situation is that a wheel in a two-wheeled vehicle is subjected to radial stresses only, while the stresses in the axial direction may be completely disregarded. However, in a wheelchair, considerable axial stresses often occur. Thus, the bearing design used in a bicycle hub cannot be used in a hub intended for a wheelchair. This, in turn, entails that one cannot use this manufacturing method and benefit from the low manufacturing prices of a bicycle hub.
In a wheelchair wheel the axle-bearing usually includes a through-going axle with deep groove bearings which are pressed into a collar-equipped bearing-seat of the hub. Assuming that the ball-bearings are properly adjusted they can when carrying heavy loads, both axial and radial, achieve a long working life. However, a careless or even wrong assembly may cause axial stress in the bearing and strongly deteriorate the operation of the bearings and quickly destroy them. A very high precision is required both in the axle, in the possible collars upon the axle, as well as in the hub and its bearing-seats. Manufacturing of a special hub for a wheelchair must take place in relatively short series, with the result that the prices will be very high. It is therefore natural to look for new methods, when we are concerned with the choice of a design and material for a wheelchair hub.
With appearance on the market of new high-resistant plastics it appears attractive to try to produce a wheelchair hub of such a plastic material. The problem here is, however, the design of the hub, which when manufactured by means of injection molding necessitates the use of highly complicated and therefore very expensive tools.
Furthermore the stress upon a hub used in a wheelchair can often be very high, therefore extremely high requirements must be set forth both in respect to the design of the hub and to the methods used in its manufacture. Particularly heavy resistance problems can be encountered in flanges with holes serving for attachment of spokes to the hub.
As indicated above the precision in a hub can also be critical, if the required bearing function must be satisfied. Among special problems here are the shrinkage phenomena that take place in certain plastics. Therefore it is hardly possible in a hub produced of plastic to ensure an absolutely accurate distance between the collar-surfaces which determine the axial position of the ball-bearings in the bearing-seat. Some after-adjustments are therefore normal.
TECHNICAL PROBLEM AND OBJECT
It is an object of the present invention to provide a method for manufacturing a hub, which is intended to be used in a wheelchair and which may be produced having the required strength and precision without high tooling cost, mainly by the injection molding process.
TECHNICAL SOLUTION
This purpose is achieved according to the invention by a
REFERENCES:
patent: 1748452 (1930-02-01), Martins
patent: 4193639 (1980-03-01), Pauly et al.
patent: 4295256 (1981-10-01), Paschl
Echols P. W.
Enco Miljo Forsaljning AB
Rosenbaum Mark
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