US3174383A - Sealing devices for vending machines and like applications - Google Patents

Description

March 23, 1965 F, ||E|L 3,174,383

SEALING DEVICES FOR VENDING MACHINES AND LIKE APPLICATIONS Filed June 2l, 1961 United .States `Patent O 3 174 383 SEALING nnvrcns rionvnnnnno Macnntns AND LIKE APPLECATEONS Friedrich Heil, Frankfurt am Main, Germany, assigner to Telefonbau und Normalzeit Sandali., Frankfurt am Main, Germany, a firm of Germany Fiied .lune 21, 1961, Ser. No. 118,719

Claims priority, application Germany, Apr. 26, 1961, ll 20, 62

This invention relates to sealing devices for vending machines and like applications.

It is` one object of the invention to provide improved tamper resistant sealing means for vending machines and like applications. y

It is another object of the invention to provide sealing means for vending machines Vand like applications which make it extremely ditcult for unauthorized persons to get access to any particular piece of equipment while making it relatively easy for authorized persons to get access to the particular piece of equipment.

Still another object of the invention is to provide vending-machine-sealing-screw-means which are highly tamper resistant unless a special tool is applied for the removal thereof.

A further object of the invention is to provide a composite seal for vending machines and like applications wherein access to tamper resistant sealing-screw-means is normally precluded by a cap forming a part of an integral tamper resistant seal.

It has been proposed to seal vending machines by means of screws having a head breaking off when subjected to a predetermined torsion. Opening of the vending machine involves removal of the shaft of the screw which removal must be effected by a drilling operation.

Such drilling operation is a relatively difficult achievement or task for any unauthorized person tampering with the vending machine. It is, however, also a relatively difiicult achievement or task for any person authorized to obtain access to the vending machine.

It is, therefore, another object of the invention to provide an improved screw-seal predicated on the concept of precluding tampering by breaking off the head of a sealscrew, but being more readily adapted to give access to authorized persons than the aforementioned screw-seal.

The invention will be fully understood from the following description when read in connection with the accompanying drawings, in which:

FIG. 1 is an isometric view of a longitudinal section of a seal embodying the present invention in the process of being established;

FIG. 2 is an isometric view of a longitudinal section of seal embodying the present invention upon being established; and

FIG, 3 is an isometric view of a longitudinal section of a seal embodying the present invention in the process of being removed.

Referring now to the drawings, and more particularly to FIG. l thereof, reference numerals 7, 8 and 4 have been applied to indicate three superimposed plates forming part of the base structure of a vending machine, eg., a postage meter. The bush 3, 5 forms likewise a part of the base stmcture. Plate 4 is provided with a tapped or screw-threaded hole 4a into which shaft 1 of a screw is inserted. The screw comprising shaft 1 secures plates 7, it to plate 4 and thus prevents unauthorized lremoval of plates 7, it from plate 4. Plates 7, 8 may be cover plates controlling access to the setting mechanism of a postage meter, and plate 4 may be a portion of the housing for the setting mechanism of such a meter. Base plate 7 is provided with a rectangular or square cut-out or 3,174,383 Patented Mar. '23, 1965 ice recess 7a, and bush 3, 5 includes a portion 5 rectangular o-r square in cross-section fitting into the aforementioned cut-out or recessr7a. Thus rotation of bush 3, 5 around the longitudinal axis thereof relative to base plate 7 is effectively precluded. The portion of bush 3, 5 situated above base plate 7 is substantially toroidal and delines a screw-head receiving chamber or cavity 17 having a bottom surface 17a. The end of bush 3, 5 remote from plates 7, 3, i is provided with an undercut portion 18 including a surface parallel to plates '7, 8, 4 and a conical surface flaring outwardly in downward direction, i.e., toward plates 7, d. The rectangular or square portion 5 of bush 3, 5 inserted into aperture 7a defines a cylindrical passage 19 for the shaft 1 of a sealing screw. The entrance portion'Ztl of passage 19 is conical flaring outwardly in upward direction, i.e., away from plates 7, 8, 4, The screw-shaft 1 supports a first screw-head Zhaving Va peripheral undercut edge 2a spaced from base struc ture 3, 5, 7, 8, 4. Screw-head 2 andthe above base structure, i.e., the bush 3, 5 thereof, define jointly an emp-ty toroidal space 6 recessed behind screw-head 2. Reference numeral 9 has been applied to indicate a second screw-head projecting from the first screw-head 2 in a direction longitudinally of shaft 1. In the embodiment of the invention shown in FIG. l both screw-heads 2, 9 are in the shape off inverted frustum cones. As shown in FIG. 1 screw-head 2 is accommodated `in screw-head receiving chamber 17, whereas screw-head 9 projects beyond chamber or cavity 17 exposing its groove 9a for ready insertion of a screw-driver. Reference numeral 1t) has been applied to indicate the junction between screw-heads 2 and 9. This junction is a point of minimal torsional strength to cause breaking of the screw 1, 2, 9 at junction 11i when screw-head 9 is subjected by a screw-driver or like tool to a predetermined torsion. In the embodiment of the invention the weak point 1li of screw 1, 2, 9 has a smaller cross-sectional area than any other point of screw-head 2 and any other point of screwhead 9. The upper circular surface 2b of screw-head 2 is not provided with any recess giving access to any kind of screw-operating tool such as, for instance, a screwdriver. Therefore, after head 9 has been broken off by a person authorized to get access to the vending or like machine, shaft 1 cannot be-or can hardly be-unscrewed by an authorized person intending to improperly obtain such access. After head 9 has been 4broken off a cap or cover plate 11 is inserted into the open frontend of bush 3, 5. Cap or cover plate 11 is made of a soft metal as, for instance, lead. When pressure is applied to the front end of plate 11 the same expands and enters into the undercut portion 18 of bush 3, 5, thus forming a secondary seal tending to preclude access to the screw-head 2 in screw-head chamber 17. Seal plate 11 is also an indicator showing whether an unauthorized person has attempted to tamper with the Vending machine. When expanding cap 11 its rear side may rest against screwhead 2 thus forming a boss for expanding cap 11,

FIG. 2 shows the machine as being protected completely against unauthorized manipulation by means of sealing screw 1, 2 and sealing cap or plate 11.

A person authorized to get access to the vending machine may first remove seal or cap 11, and then remove screw 1, 2 by means of a special tool adapted to make one or more appropriate indentations into screw-head 2. Such a tool may be in the form of a chisel 12 shown in FIG. 3 including a pair of spaced prongs 13, 14 having sharp cutting edges. These prongs are adapted to pierce the screw-head 2 and to enter the toroidal empty space recessed behind top surface 2b of screw-head 2. Thus two slots 15, 16 are formed in screw-head 2. Now screw 2, 1 may readily be' removed either by turning chisel 12,

or substituting a screwdriver for chisel 12 having a geometry similar to that of chisel 12, i.e. including a pair of spaced prongs adapted to enter into slots 15, 16 in screw-head 2.

It will be understood that I have illustrated and described herein a preferred embodiment of the invention, and that various alterations may be made in the details thereof without departing from the spirit and scope of the invention as defined in the appended claim.

I claim:

A sealing device for vending machines and like applications comprising a base structure including a base plate, a recess in said base plate, a bush having a first portion projecting into said recess in said base plate and a second portion situated above said base plate and forming a screw-head receiving cavity having a lateral wall defining a circular shoulder, said cavity further having a bottom surface including a surface inclined to the axis of the bush, means for precluding a rotary motion of said bush around the axis thereof relative to said base plate, a screw including a screw-threaded shaft projecting through said bush into a portion of said base structure, a iirst screwhead on said shaft substantially in the shape 0f an inverted frustum of a cone complementary to said seated on said inclined surface, a second screw-head projecting from said rst screw-head in a direction longitudinally of said shaft, the point of junction between said rst screwhead and said second screw-head having a smaller crosssectional area than any other point of said first screwhead and any other point of said second screw-head, and said first screw-head having a base surface and part of said cone situated in a plane above said bottom surface of said cavity to provide a space between said irst screwhead and said bottom surface and below said shoulder dened by said lateral wall of said cavity, said base surface being substantially smooth and uninterrupted.

References Cited in the le of this patent UNITED STATES PATENTS 141,908 Ackerman Aug. 19, 1873 461,523 Phelps Oct. 20, 1891 2,054,060 Morris Sept. 8, 1936 FOREIGN PATENTS 18,369 Great Britain Aug. 16, 1906 684,821 Great Britain Dec. 24, 1952 31,850 Norway Feb. 28, 1920 `ERNEST W.. SWIDER Anesting Officer UNITED STATES PATENT oFFlCE CERTIFICATE 0F CORRECTION Patent No. 3,174,383 'March 23, 19.65

Friedrich Heil l It is hereby certified that error appears invtheabove numbered patent reqlrng correction and that the said Letters Patent should read as corrected below Column 3, line 24,. for "said" read fand Signed and sealed this` 24th: day of August 1965'.

(SEAL) Attest:

, EDWARD J. BRENNER Commissioner of Patents

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