Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Headed fastener element with nut – washer – securing means or cap – Wedge-securing means
Patent
1994-09-20
1996-11-05
Saether, Flemming
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Headed fastener element with nut, washer, securing means or cap
Wedge-securing means
411368, 411999, F16B 1900
Patent
active
055709826
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a screw hole in furniture fittings, especially in metal hardware for furniture, in which a screw provided with a truncoconical countersink head and having a thread of a given outside diameter is preinstalled, wherein the hole has a countersink shaped to complement the truncoconical head of the screw and adjoined by a substantially cylindrical section to accommodate the shaft of the screw. The invention also concerns a method for the production of such holes in hardware made of thin sheet metal.
In hardware that is to be fastened by screws to pieces of furniture, e.g., mounting plates for furniture hinges, it is common practice to preinstall the screws on the hardware part, so that when the latter is mounted on a cabinet wail the hardware part needs only to be placed at the intended mounting position with its preinstalled screws aligned with the holes predrilled in the furniture and the screws to be driven in with a screwdriver. To achieve sufficient strength in the screw connection, screws with relatively coarse threads are used, so-called "Euro screws" being increasingly used of late, the threads of which have a relatively coarse crest, which on the one hand permits the screws to be driven with comparatively little effort into holes in wood materials, but due to the comparatively deep penetration of the threads into the walls of the hole they can withstand heavier loading and still permit repeated installation and removal of the hardware.
To assure that the preinstalled screws will be held securely in the preinstallation position, i.e., will neither drop out nor tilt away from their position at right angles to the hardware surface, a relatively tight fit must be provided between the top end of the screw's shaft and the hole.
This has been accomplished in the case of thick hardware (DE-PS 34 44 851) by making the wall of the hole holding the shaft of the screw slightly smaller than the outside diameter of the shaft of the screw, so that the crests of the threads can easily penetrate into the wall of the hole during preinstallation and cut a shallow holding thread by themselves, so to speak.
2. The Prior Art
In the case of hardware of thin sheet metal, in which the hole thus has such a short length that a thread holding the screw securely can hardly be produced, a solution to this has been found (DE-PS 36 22 001) in which a circular area extending over about 270.degree. is stamped out of the area of material adjoining the hole or, more correctly, the punched hole, and shaped out of the plane of the sheet metal to correspond to the pitch of the screw thread. Thus a thread is formed which suffices to hold the screw, especially above-mentioned Euro screw, securely in the punched hole. Of course, free space must be available to correspond to the thread formed out of the plane of the material, i.e., sheet-metal hardware of this kind must be embossed at least in the area of the punched fastening holes to form the necessary hollow space. When the screws are driven into the corresponding holes, the unthreaded section at the upper end of the screw shaft adjoining the screw head and having a diameter smaller than the outside diameter of the threads comes into the reach of the punched thread and the screw can then turn freely without binding, i.e., the piece can be screwed tightly onto the corresponding cabinet wall in the required manner.
The invention is addressed to the problem of devising a configuration for screw holes in hardware parts which will permit secure preinstallation of flat-head screws, and which on the other hand will be usable both in hardware of great material thickness and especially in hardware of thin sheet metal, while it will be possible for the part in question to be forced with its bottom into tight contact with the cabinet wall without routing out the area around the mounting hole. At the same time the hardware piece provided with the holes in question is also to be installable even without preassembly and with s
REFERENCES:
patent: 2010853 (1935-08-01), Dyer
patent: 2272170 (1942-02-01), McDowell
patent: 3339952 (1967-09-01), Beckman
patent: 3556570 (1971-06-01), Cosenza
patent: 3878042 (1975-04-01), Curulla
patent: 4768259 (1988-09-01), Rock
patent: 5069051 (1991-12-01), Olah
DIN 7952, Jan. 1972 "Blechdurchzuge mit Gewinde" (Sheet metal anchorage with threads), pp. 146-152.
MEPLA-Werke Lautenschlager GmbH & Co. KG
Saether Flemming
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