US 3499304 A
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4 Marh 10,1970 M.NAUJOKS 3,499304.
FLAT KEYS FOR CYLINDER LOCKS Filed April 19, 1967 FIG.4
INVENTOR United States Patent Ofice' 3,499,304 Patented Mar. 10, 1970 3,499,304 FLAT KEYS FOR CYLINDER LOCKS Manfred N aujoks, Velbert, Rhineland, Germany, assignor to C. Ed., Schulte G.m.b.H., Velbert, Rhineland, Ger- Filed Apr. 19, 1967, Ser. No. 632,085 Claims priority, appliscation Ggrmany, Apr. 21, 1966,
ch 38, Int. Cl. E051) 19/04, 19/16 US. Cl. 70-406 4 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The invention relates to a flat key for cylinder locks of closing mechanisms with variations in profile. In known fiat keys parallel ribs are provided along the side faces of the keys and are fully or partially omitted as required in order to vary the profile. The master key of the set has no ribs at all and can thus easily be counterfeited by rubhing down the ribs. Moreover the ribs must have an adequate width sogiven the standardised height of the keyonly a small number of them can be arranged on each face. The number of variations which can be used in practice depends on the number of ribs.
Some known flat keys for cylinder locks of closing mechanims with variations in profile are provided with grooves on each face. With this construction the master key contains most grooves and each of the subordinate keys contains less. This makes it considerably more difficult to counterfeit the master key, since it already contains the most grooves. The side faces of the key cannot readily be rubbed down to the bottom of the grooves, particularly if the grooves extend substantially as far as the plane of the key, since in this case they would be coplanar with the bottoms of the grooves on the other side. Here again the number of variations in profile depends on the number of grooves.
In both constructions gaps have to be left between the projections or between the grooves, and these gaps still further diminish the side surfaces available for the provision of projections or grooves. A flat key for cylinder locks is therefore already known, wherein the projections are shaped like saw teeth.
SUMMARY OF THE INVENTION The invention aims to provide a fiat key for cylinder locks of closing mechanisms with variations in profile in which such drawbacks are avoided. This is achieved, according to the invention, substantially in that the keys have ribs which are known per se and omitted from the master 'key and grooves which are also known per se and present in their full complement in the master key, and that the projections and grooves which are present and omitted where necessary, are arranged in alternating sequence. This is a simple way of providing fiat keys of this type, admitting of a particularly large number of variations in profile. The alternating sequence of projections known per se and grooves known per se makes full use of the parts of the lateral surfaces between two projections or grooves for theprovision of additional grooves or projections.
It is an advantage for projections on one side of the key to be opposite grooves on the other side. This is a simple method of giving the key an adequate wall thickness over its whole width in spite of the provision of grooves.
It is particularly advantageous for the depth of the grooves to extend at least almost as far as the center plane of the key. By this simple step the bottoms of the grooves on one side are made substantially coplanar with the bottoms of the grooves on the other side of the key, and it is impossible to counterfeit a master key by abrading the parts between the grooves.
An example of the invention is illustrated in the drawings, in which:
FIG. 1 shows a key cross section with all the possible ribs and grooves for the variations in profile,
FIGS. 2 and 3 show two examples of derived variations in profile, and
FIG. 4 shows a cross section through the associated master key.
The key 10 according to the invention as illustrated in the drawings has a guiding portion 11 at the back containing a guide groove 12. The portion 11 with the groove 12 is identical in all keys in a series. In order to produce additional series of keys more than one guiding groove 12 may be provided in the portion 11, and the groove 12 may be located in a different position and/or on the other side of the key.
The remainder of the side faces of the key 10 each have three grooves 13, 14, 15 and 16, 17, 18 and three ribs 19, 20, 21 and 22, 23, 24, the grooves 13-18 alternating with the ribs 19-24. This is a simple way of ensuring that the key has a particularly large number of different cross sectional shapes.
For the variations in profile the grooves 13-1-8 and/or ribs 19-24 may be omitted where required, in part or wholly. Of the large number of possible key cross sections two examples are illustrated in FIGS. 2 and 3. In the section shown in FIG. 2, for example, the grooves 13, 14 and 16 and the ribs 21, 23 and 24 are provided, Whereas in FIG. 3 the key section is provided with the grooves 13, 14 an 17 and the ribs 21, 22 and 24.
In the master key illustrated in FIG. 4 all the grooves 13-18 are present and all the ribs 19-24 omitted. The key 10 will thus fit into all the locks in that series.
As will be seen particularly from the figures illustrated, the projections 19-24 on one side of the key 10 are opposite the grooves 13-18 on the other side. By this simple method the key 10 is given an adequate wall thickness over its whole width in spite of the grooves 13-18. The method further enables the grooves 13-18 to be taken relatively deep into the key 10 and to extend :at least nearly as far as the center plane of the key. This is an easy way of preventing the master key from being counterfeited by abrading the parts of the cross section between the grooves.
As already mentioned, the embodiment illustrated is only an example of the invention. The invention is not restricted to it and many other constructions and applications are possible. For example, the key section shown in FIG. 1 could be used in mirror image to produce a further series of keys.
1. A set of cylinder lock keys consisting of a master key, and at least one other key operative in conjunction With a lock, each of said keys comprising a strip-shaped body portion having opposite marginal zones, said master key being free from projections and comprising only grooves in each of said marginal zones with the grooves in one of said marginal zones being oifset relative to the grooves in the other of said marginal zones, and said I other key being provided in at least one of the marginal 3 zones thereof with at least one projection and in said marginal zones with a number of grooves which is smaller than the number of grooves in the marginal zones of said master key.
2. A set of keys as defined in claim 1, wherein said master key comprises three of said' grooves in each of said opposite marginal zones of said body portion thereof.
3. A set of keys as defined in claim 1, said body portions being flat and said marginal zones having respective edge faces provided with said grooves.
4. A set of keys as defined in claim 1, said strip-shaped body portions being longitudinally bisected by a center line, and at least some of grooves in the opposite marginal zones extending at least substantially to said center line.
4 References Cited UNITED STATES PATENTS 608,069 7/1898 Noack 70375 r 1,782,464 11/1930 Falk 70406 FOREIGN PATENTS 355,710 8/1961 Switzerland.
1,186,776 2/1965 Germany.
10 MARVIN A. CHAMPION, Primary Examiner R. L. WOLFE, Assistant Examiner