Joints and connections – With opening for access to connector or operator – To threaded component
Patent
1983-03-10
1985-07-23
Arola, Dave W.
Joints and connections
With opening for access to connector or operator
To threaded component
403 12, 403 14, F16B 1700
Patent
active
045306141
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a framework having hollow sections as bar elements which are joined at separate junction members.
BACKGROUND OF THE INVENTION
Frameworks whereby the junction members have several connecting pieces for the uniform bar elements are known, e.g. from German Printed Specification No. 28 19 632, said connecting pieces forming three-dimensional or plane angles. In the open ends of the connecting pieces threaded holes are provided, centrally punched plates are mounted at the end of the bar element, and a cap screw is inserted in each punched plate with its head positioned inside the bar element. The screw is screwable into the threaded holes on the side of the connecting piece. Finally the bar elements, the plates and the connecting pieces have a smooth exterior profiling in order to yield a framework free of recesses and projections.
In the case of the German reference a cap screw with a polygonal shank portion is provided, over which a coupling piece in the shape of a plate, cooperating with the polygonal shank portion is slipped. This coupling piece can be acted upon from the outside by means of a wrench or the like, permitting the tightening of the screw.
However, in this embodiment one cannot apply sufficient tightening force to the screw, since it is not possible to apply a large enough lever arm for the actuation of the coupling part.
OBJECT OF THE INVENTION
The object of the present invention is to provide an improved three-dimensional framework whereby a higher tightening force can be applied to the screw through the use of a common screwdriver and cap screws commonly found on the market, the additional coupling part being eliminated all together.
SUMMARY OF THE INVENTION
This object is attained according to the invention with a tubular guiding piece supported inside of the bar element, forming a sliding duct for the head of the screw running inside of the bar element and slightly curved with respect to the wall of the corresponding bar element, said pipe ending in an opening for the passage of the screw in the wall of the bar element.
Through a combination of these features, it is possible to introduce high-stress screws, commonly available on the market, into the tubular guiding piece and into the corresponding hole, in order to join the connecting piece and the bar element. The screw is then firmly tightened by means of a common impact screwdriver whereby the shank of a knuckle joint adapted to the tubular guiding piece is slipped on the impact screwdriver. In this manner sufficient initial torque can be transmitted, since the screw can be tightened mechanically. The high-strength screw tightened under high force is secured without additional securing parts.
In order to offset the weakening of the bar elements as a result of the existence of the screw-passage opening in the wall, it is proposed to connect the guiding piece at its outlet side with the wall surrounding rim of the screw-passage opening of the bar element. The connection is carried out advantageously through welding. For installation purposes, it is advantageous that the inner and outer cross-section of the guiding piece be round.
It is especially advantageous that the clear inside diameter of the guiding part be only slightly larger than the outside diameter of the head of the cap screw and that the cap screw be of the polygonal socket-screw type.
This way it is possible to insert relatively large cap screws with respect to the available inside section and to drive them by a corresponding tool.
It has proven particularly advantageous for fabrication to attach the guiding piece to the back of the plate and to connect the plate to the rim of the open end of the bar element.
For this purpose, the guiding piece is welded advantageously to the back of the plate and the plate is then welded to the rim of the open end of the bar element.
This construction makes it possible to final-weld the complete bar element including the necessary guiding pieces and to hot-galvanize this complete part
REFERENCES:
patent: 3198562 (1965-08-01), Smith
patent: 3675312 (1972-07-01), Herman
patent: 4044511 (1977-08-01), Lingle
patent: 4082470 (1978-04-01), Alberts
patent: 4092904 (1978-06-01), Schreiber
patent: 4190375 (1980-02-01), Berry
patent: 4249830 (1981-02-01), Day
Arola Dave W.
Dubno Herbert
Ross Karl F.
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