Device for altering lock cylinder to receive a new key

[57] ABSTRACT

A device for altering a lock cylinder to receive a new key comprises a plate which is adapted to be secured to the entrance opening of the lock cylinder and which is formed with one or more projections in order to define a new configuration of the key access opening in order to alter the lock so that it must receive a new key. The entrance plate is formed with a projection which may be selectivey located in respect to the previous access opening and the key which previously fit into the lock must be altered to define a recess to accommodate the projection in order that it may be received in the lock.

Claims, 4 Drawing Figures

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PATENTED JUN 51973

3,736,780

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3,736,780

DEVICE FOR ALTERING LOCK CYLINDER TO RECEIVE A NEW KEY

SUMMARY OF THE INVENTION

This invention relates in general to the construction of locks and in particular, to a new and useful device for altering a lock cylinder so that it can no longer receive the ‘usual’ key which has been changed.

At the present time, it is known to provide devices in the form of plugs which fit into the openings of lock cylinders and provide a shortening of the access opening or an alteration of the access opening so that the usual key which is employed for opening the lock will no longer fit. A disadvantage of such devices, however, is that they are sometimes difficult to insert and to remove and in addition, they require extensive key change in order to permit operation of the lock with the revised or changed key.

The present invention is an improvement over the prior art inasmuch as it provides a simple plate element which may be secured directly to the front face of a lock cylinder in a position to outline the key access opening and to provide a projection at one or more locations which varies the opening size so that a new key must be provided to enter into the key opening to open the lock. The plate is designed with a projection, for example, which is located so that the previously fitting key may be easily modified by forming a groove therein of the size of the projection so that it will be usable in the lock. All other keys which have not been modified, however, will not fit into the lock.

The modification plate may comprise, for example, a plate of the size of the small key access cylinder and it may be easily installed on the face of the lock cylin- ₃₅der by riveting it in place after rivet receiving holes are first drilled therein. The exterior of this small plate may be covered by cover plate to hide the opening holes and securing rivets and to provide an aesthetic appearance.

Accordingly, it is an object of the invention to pro- 40 vide an improved device for altering a key lock in a simple and easy manner so that it will accept only a restructured key.

A further object of the invention is to provide a closing plate for the entrance to a key lock which includes 45 one or more strategically placed projecting elements providing an altered entrance opening which can be penetrated only by a key formed to accommodate the projection.

A further object of the invention is to provide a key ⁵⁰lock locking plate which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. ⁵⁵For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawing and descriptive matter in which there is illustrated a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an exploded perspective view of a cylinder lock with a conventional key which is provided with tap holes for receiving a lock altering plate constructed in accordance with the invention;

FIG. 2 is a front perspective view of a lock altering plate of the invention;

FIG. 3 is a perspective view of a covering plate for the altering plate shown in FIG. 2; and

FIG. 4 is an exploded perspective view similar to FIG. 1 showing a revised lock and key therefor with the altering plate thereon as constructed in accordance with the invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings in particular the invention embodied therein comprises a cylinder lock generally designated 10 having a key access cylinder 12 which extends to a front lock face 14 and which is shown as being provided with two rivet receiving openings or holes 14 and 16 which are drilled therein for example. The cylinder lock 10 is of a conventional type and it accepts a key generally designated 18.

In accordance with the invention the cylinder lock 10 is easily altered in accordance with the invention by securing a lock altering plate generally designated 20 to the front face 14 at a location to cover the cylinder 12. The altering plate 20 is secured in position by rivets or ²⁵ other suitable securing devices 22 which extend through openings 24 of the plate 20 and are tightly fastened in the openings 14 and 16 of the cylinder 12.

In accordance with a feature of the invention, the altering plate 20 is provided, for example, with one or more projections 26 which extend inwardly into the key access slot or opening 28 which overlies the access opening 30 of the cylinder lock 10. The projection 26 is shown as being a triangular projection which is oriented in any one of a plurality of positions along the height of the key access slot 28 and which may be of a special configuration as selected in order to provide a controlled altering of the cylinder lock 10. In the embodiment shown, a key 18' having a triangular shaped groove 32 of a size to accommodate the projection 26 may now be provided to unlock the cylinder 10. The key 18' may be a modification of the key 18 which may be simply formed by forming the triangular groove 32 along its length as necessary. Of course, another configuration such as a circular projection, rectangular projection or the like may be provided instead of the triangular projection 26 and it may be located in any location in the opening 28.

A cover plate generally designated 34 is also provided which may be of a metal material of a material such that it can be crimped over the altering plate 20. It is provided with a straight rectangular access opening 36 or if desired it can be manufactured to precisely match the opening 28 with the projection 26 of the altering plate 20. The plate 34 enhances the appearance of the lock and it also covers the rivet heads or bolt heads 22.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.