Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1981-01-23
1984-07-24
Moon, Charlie T.
Metal working
Method of mechanical manufacture
Assembling or joining
29509, 29520, 29522R, 138 89, 138 92, 264249, B23P 1102
Patent
active
044610653
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a fastening device for fastening a cover of thermoplastic material to a tubular component.
In one known fastening device of this type, the cover projects at least partly with a tight fit into the tubular component and the tubular component is provided with a number of bores in that region which is covered by the projecting part of the cover. In this case, fastening is carried out by inserting a heated pin through the bores into the constituent material of the cover so that it is softened and forced by displacement into the bore. The pin is then withdrawn again so that the cover is held fast by the material forced into the bores. A fastening device of this type generates only a limited retaining force per bore.
The object of the present invention is to provide a fastening device of the type mentioned at the beginning which generates a considerably higher retaining force.
According to the invention, this object is achieved by a pin of a non-thermoplastic material which projects through each bore into the material of the cover and which is held thereby
The pin is preferably made of metal.
The pin should have a smaller diameter than the bores so that the material displaced by the heated pin has enough room to penetrate into the bore.
According to another aspect of the invention, the pin comprises at least one peripheral groove around its circumferential surface to provide the pin with a firmer hold.
It is favourable for the pin to be tapered at both ends to make it easier to press into the constituent material of the cover.
The present invention also relates to a method of fixing a cover of thermoplastic material to a tubular component, the cover projecting at least partly with a tight fit into the tubular component and the tubular component being provided with a number of straight-through bores in that region which is covered by the projecting part of the cover.
According to the invention, the cover is positioned as required in the tubular component, pins smaller in diameter than the bores are produced from a non-thermoplastic material and, after heating to a temperature above the softening temperature of the thermoplastic material, a pin is pressed through each bore into the constituent material of the cover.
To fasten a cover comprising a shoulder surface which, in the inserted position of the cover, rests on an edge of the tubular component, it is favourable for the cover to be inserted preheated into the tubular component and to be fastened in this preheated state. When the cover subsequently cools, it contracts so that the shoulder surface of the cover presses against the edge of the tubular component.
One example of embodiment of the invention is described in detail in the following with reference to the accompanying diagrammatic drawings, wherein:
FIG. 1 is an axial section through a tube closed by a cover with a cover fastening.
FIG. 2 shows a fastening device on a larger scale.
FIG. 1 shows a cylindrical tube section 1, for example an iron return element of an electric motor, of which one end opening is closed by a cover 2 of plastic. The cover 2 is substantially disc-like and, around its outer periphery, comprises a recess 3 forming a circular peripheral region 4 which fits tightly into the interior of the tube section 1. The recess 3 is axially delimited by an annular shoulder surface 5 which rests on the end face 6 of the tube section 1.
That part of the cover 1 which lies inside the tube section changes into an annular collar 7 which rests on the tube section 1.
As can be seen in particular from FIG. 2, the fastening device comprises a number of radial bores 8 which are uniformly distributed around the circumference of the tube section 1 at the level of the annular collar 7. A metal pin 9 is inserted into each of these bores, being tapered at its ends by chamfers 10 and being provided at its center with an annular groove 11.
The cover 2 is made of a thermoplastic material, the pins 9 of brass and the tube section 1 of iron.
To fasten the cover to the tube section, the co
REFERENCES:
patent: 2421105 (1947-05-01), Warren, Jr.
patent: 2679913 (1954-06-01), Scott
patent: 3458618 (1969-07-01), Burns et al.
patent: 3578027 (1971-05-01), Zapfi
Interelectric AG
Moon Charlie T.
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