Tools – Tool jaw – Jaw features
Patent
1997-11-07
2000-06-20
Meislin, D. S.
Tools
Tool jaw
Jaw features
411385, 411433, 470 9, B25B 702
Patent
active
060764376
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a screw designed to be installed and removed rapidly. It also relates to a manufacturing process and a tool for the removal thereof.
BACKGROUND OF THE INVENTION
The invention encompasses all screws designed to provide for attachment or assembly by virtue of being installed in a threaded hole in a complementary part. This is true, for example, of screws designed to work in conjunction with a nut, or of those intended to fasten at least two pieces together by virtue of being screwed into the threads of a threaded hole provided within at least one of these pieces.
One disadvantage of these conventional screws lies in the fact that the installation and removal thereof may entail relatively long, laborious operations.
In fact, the installation of a screw requires the following operations, performed in this order: 1) engagement of the screw threads into the threads of the complementary piece; 2) rotation of the screw until the screw head rests on one of the pieces; 3) tightening of the screw into the complementary piece by effecting a certain number of turns or partial turns once the screw head rests on the piece.
Removal of the screw requires the following operations: 1) loosening; 2) rotation of the screw to disengage the threads from the threading in the complementary piece; 3) removal of the screw from the complementary piece.
In fact, the rotation step (the second step involved in the installation or removal summarized above) are the most lengthy. This may be bothersome when the screws are, for example, designed to fasten individualized parts on a machine tool. It is desirable in this case that the stoppage of the machine, as required in order to replace these parts, be as short as possible, so as to reduce operating costs, while not decreasing excessively the production capacity thereof.
The present state of the art includes devices which allow fastening or disassembly in a short time. However, these known devices normally provide inferior fastening quality: they exhibit either pronounced sensitivity to vibrations or inferior mechanical strength.
Thus, for example, quarter-turn or bayonet-type locking devices are known, in which a lug borne by an attachment rod is engaged and locked, following a slight degree of rotation, in a slot-and-cam mechanism which locks another part in place.
These devices exhibit a certain level of elasticity, which makes them unsuitable for attaching pieces subjected to vibrations, for example.
Thus, the invention concerns a device which can be installed and removed rapidly, but which does not possess the disadvantages of conventional devices.
SUMMARY OF THE INVENTION
According to the invention, a screw comprising a cylindrical body and threads, wherein the thereads are arranged so as to be able to adopt two positions: a first position in which the threads project outwardly beyond an outer circumference of the cylindrical body, and a second position in which the threads are retracted into the cylindrical body such that the threads do not project outwardly beyond the outer circumference of the cylindrical body. Further, the screw comprises means (12; 13; 14; 26, 27, 29; 32, 33, 34, 35) for moving the threads from the second position to the first position, and means (29; 36, 37, 38) for locking the threads in the first position and for unlocking the threads locked in that first position, thereby allowing the threads to retract into the cylindrical body.
The invention thus makes it possible to retain the advantages of screws and to do away with their disadvantages, primarily by eliminating the long, laborious rotation steps involved when the screw is inserted or removed: In the present invention during insertion, the threads are unlocked and are able to retract into the cylindrical body, thus making it possible to drive in the screw until the screw head rests in a supported position without having to rotate the screw. Then after the head becomes supported, it suffices simply to place the threads in their projecting position and then to perform the tighte
REFERENCES:
patent: 1536241 (1925-05-01), Sroka
patent: 2087114 (1937-07-01), Pearlstein
patent: 3561316 (1971-02-01), Karges
patent: 4787139 (1988-11-01), Sweet
patent: 5217464 (1993-06-01), McDonald
Meislin D. S.
Sidel S.A.
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