Fastener

Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Threaded fastener locked to a discreet structure – Member or portion thereof located between substructure and...

Patent

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Details

411 11, 411534, 411544, 83543, F16B 3924, F16B 4300

Patent

active

056673477

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to improvements to a fastener, and relates in particular, though not exclusively, to improvements to a threaded fastener suitable for fastening a grinding wheel, circular saw blade or carving disk and the like to the spindle of a power tool.


BACKGROUND TO THE INVENTION

Copending Australian Patent Application No. 85296/91 describes a threaded fastener suitable for securing a grinding wheel to the spindle of an angle grinder. The fastener comprises a first disk-shaped component having a first pressure transmitting surface adapted to bear against the grinding wheel, and a second disk-shaped component having a threaded hub non-rotatably fixed thereto. The first and second components are assembled on the hub so as to be rotatable with respect to each other, and the second component is adapted to apply an axially directed compressive force to press the first component against the grinding wheel when a torque is applied to the second component. A solid dry lubricant washer is provided between the first and second components in an annular recess immediately adjacent the hub, for reducing friction, when one of the components is rotated relative to the other. The lubricant washer insures that a significantly increased proportion of the torque applied to the second component is converted to compressive force transmitted through the first component to the grinding wheel.
While the performance of the above-described threaded fastener is entirely satisfactory and represents a great advance upon the art, the second component is typically of complex design and, as it normally carries the full clamping pressure of the nut, must be made from metal. This requires either a complex NC-machining process or the use of sintered powder metallurgy. It would be desirable if a part with such a complex shape could be made from plastics material by injection moulding or by die-casting. In practice, it has also proved difficult for a user to judge whether the fastener has been adequately tightened, due to the fact that the turning friction normally associated with tightening has been substantially eliminated. There is thus a danger of overtightening of the fastener.


SUMMARY OF THE INVENTION

The present invention was developed with a view to providing a number of improvements to the design of the above fastener.
According to one aspect of the present invention there is provided an improved fastener comprising: with respect to each other about a common axis, said first component having a pressure transmitting portion and a resilient flexing portion, said pressure transmitting portion being adapted to bear against an object to be fastened and being radially spaced from said common axis, said second component having a threaded portion provided in connection therewith and being adapted to apply an axially directed compressive force to press the pressure transmitting portion against said object when a torque is applied to said second component and wherein said flexing portion is adapted to allow the first component to flex when the pressure transmitting portion is pressed against said object so as to apply a clamping pressure to said object, said second component being provided with a recessed annulus within which said first component is rotatably received and wherein said recessed annulus is adapted to accommodate the flexing of the first component; and, provided between said first and second components to reduce friction therebetween when one of the components is rotated relative to the other whereby, in use, said solid dry lubricant material can ensure that a significantly increased proportion of the torque applied to said second component to fasten said object can be converted to said compressive force transmitted to the object through said pressure transmitting portion.
Preferably the improved fastener further comprises containment means provided in connection with said first and second components for containing said solid dry lubricant material therein whereby, in use, said sol

REFERENCES:
patent: 2675835 (1954-04-01), Kiekhaefer
patent: 2726524 (1955-12-01), Gorin
patent: 4006661 (1977-02-01), Sims, Jr.
patent: 4362449 (1982-12-01), Hlinsky
patent: 4687392 (1987-08-01), Bidwell
patent: 4776442 (1988-10-01), Young

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