Abstract:
A seal and lock mechanism employs a cable and a mechanism for securing a free end of the cable to the seal by a wedging action within a tapered housing bore employing wedging means such as balls and the like. The wedging action is enhanced by roughening the surface of the wedging means or otherwise improving their resistance to displacement with respect to the surface of the cable.

Description:
This invention relates to security seals, and more particularly, to a seal and lock employing a cable and a mechanism for securing a free end of the cable to the seal by a wedging action within a tapered housing bore employing balls and the like. 
     Of interest is commonly owned U.S. Pat. No. 5,222,776, incorporated by reference herein, which discloses a security seal and lock of which the present invention is an improvement. In this patent, a housing has a path for receiving a cable free end to be secured to the housing, the other cable end also being secured to the housing. A tapered cavity is in the housing through which the path passes. The path is defined by cable entrance and exit holes in the housing and a channel in the cavity. A pair of balls are in the cavity and are biased by a spring toward the entrance hole and the small transverse dimension of the cavity. 
     The path is such that it is intercepted by the balls which are used for locking the cable to the housing to preclude withdrawal of the cable. The entrance hole is offset from the exit hole transversely to the general cable insertion direction. The balls and the offset holes provide a path for the cable during insertion which path is inclined relative to the General insertion direction. In practice, insertion of the cable along the path through the housing is required to lock the cable free end to the housing. Withdrawal of the inserted free end is precluded by the balls jamming against the inserted cable. 
     Also of interest is commonly owned U.S. Pat. No. 5.820.176, incorporated by reference herein, which discloses a security seal and lock of which the present invention also is an improvement. The invention of the &#39;176 patent comprises a housing having a longitudinally extending bore with opposing first and second ends, at least the second end being in communication with the ambient about the housing through an aperture in the housing, the bore having a transverse dimension that decreases in direction from the first end to the second end. The housing has a channel of a transverse width in communication with and along the bore and forming a continuous path with the aperture. A first ball in the bore has a diameter smaller than the bore transverse dimension adjacent to the first end and larger than the bore transverse dimension adjacent to the second end. Bias means are in the bore at the first end for biasing the ball towards the second end. An elongated circular cylindrical flexible member is included having a free end for insertion into the bore at the second end through the aperture, the channel having a depth of at least 30% of the diameter of the elongated member. The bias means, bore, ball and elongated member are arranged such that a force on the elongated member to withdraw the cable free end from the housing bore toward the second end wedges the ball to the elongated member to the housing in the bore. Thus, the channel guides the elongated member, preferably a stranded cable having a nominal diameter of about {fraction (1/16)} inches or less, during insertion, provides a path for the member, decreases the degree of interference between the ball and the member during insertion and contributes to reducing the insertion load on the member. 
     The present inventors have found that although the prior designs are perfectly acceptable for cable sizes of a diameter of {fraction (1/16)} inches or less, they may experience difficulty with cables having a diameter in excess of {fraction (1/16)} inches or more. The larger cables have been found to be difficult to clamp. This resulted from an inadequate locking cooperation between the cable, the balls and the housing. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a security seal and lock which generates improved clamping between the lock housing and the locking cable. 
     Another object of the present invention is to provide a security seal and lock which is operable for use with locking cable having a diameter in excess of {fraction (1/16)} inches. 
     These objects and others are achieved by the security seal and lock of the present invention as to which the clamping and locking of the stranded cable within the housing is enhanced by increasing the frictional forces between the cable and the balls. In one aspect of the invention, the balls are provided with a rough surface finish as distinguished from the smooth polished surface finishes which have been known and practiced in the art. A second aspect of the invention contemplates coating the balls with a soft plastic to act as a friction generating surface. The invention also contemplates having the balls engage the housing in substantially a multi-point contact such as to enhance the clamping forces thus reducing the ability of the balls to rotate, which rotation might permit defeating the seal. 
    
    
     THE DRAWINGS 
     A more complete understanding of the present invention may be had from the following detailed description, particularly when read in light of the accompanying drawings, wherein: 
     FIG. 1 is a side elevational view of a seal and lock according to an embodiment of the present invention; 
     FIG. 2 is a front end view of the seal of FIG. 1; 
     FIG. 3 is a cross sectional view of the seal of FIG. 2 taken through the plane  3 — 3 ; 
     FIG. 4 is a cross sectional view through the plane  4 — 4  of FIG. 3; 
     FIG. 5 is a cross-sectional view through the plane  5 — 5  of FIG. 3, and 
     FIG. 6 is a cross-sectional view similar to the view of FIG. 3 but of a second embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, a security seal and lock according to the invention is shown and designated generally by the reference numeral  2 . 
     Seal and lock  2  comprises a preferably metal housing  4 , preferably cast zinc, and a stranded shackle cable  6 , preferably of metal such as steel. The term “cable” as used in this detailed description and in the claims includes stranded or solid shackle cables made of metal or other suitable material. The cable for this preferred embodiment is a stranded cable having a nominal diameter in excess of {fraction (1/16)} inches (1.6 mm). Cable  6  has a first end  8  secured permanently to and internally of the housing such as by swaging. The other end of cable  6 , second end  10 , is inserted into the housing to be locked therein by the locking mechanism designated generally by the reference numeral  12  (FIG.  3 ). In use, the second cable end  10  is passed through one or more hasps  14 ,  16  for securing and/or locking respective structures  18  and  20 . 
     Housing  4 . FIG. 3, has a chamber  22  for receiving the cable  6 . Formed in chamber  22  of housing  4  is a boss  24  having a first bore  26  or conduit formed therein for receiving the first end  8  of cable  6  therethrough. Bore  26  is normally linear prior to and during the insertion of cable  6  therethrough. First bore  26  extends fully through boss  24  to accommodate the insertion of cable  6  from outside the housing through the boss and into the housing. In use, the first cable end  8  is passed through bore  26  into chamber  22 . With the cable so positioned, it is secured within first bore  26  by swaging using, a typical swaging tool thereby forming swaged depressions  30  in the housing. Depressions  30  give a user visual evidence that the lock/seal has been secured and the cable firmly locked therein. 
     Also formed in the housing is a generally conical second bore  32  (FIGS.  3  and  4 ). The bore  32  has its largest diameter adjacent to the distal end  34  of housing  4  and its smallest diameter adjacent the proximal end wall  28  of housing  4 . Formed in proximal end wall  28  is an aperture  35  which accommodates passage of cable  6  from outside the housing  4  into the second bore  32 . A first channel  36  is formed in the bottom of second bore as seen in FIG.  3 . Channel  36  extends substantially the full length of second bore  32  and is shaped and dimensioned to be able to receive as much as 50% of the diameter of cable  6  therein. 
     Conical bore  32  preferably has a 3° taper along its length relative to its major axis  38  so that the bore conical angle is 6°. First channel  36  slopes downwardly in the bottom of bore with respect to the major axis  38  of bore  32  from the proximal end  28  to the distal end  34  of housing  4 . 
     The distal end  34  of housing  4  is generally open. However, for the reasons described below, it is provided with a closure  56  comprising a plate having spaced openings  58  and  60  formed therein. Closure  56  is received in channel  61  formed in the distal end  34  of housing  4  and is secured thereon by bending the edge  42  of housing  4  around the perimeter of closure  56 . 
     As best may be seen in FIGS. 4 and 5, bore  32  has an inverted V-shaped groove formed therein which defines a second channel  33  therein. As is discussed in greater detail hereinafter, V-shaped channel  33  defines edge surfaces  37  for cooperating with securing balls  52 ,  54  so as to establish multi-point contact between the housing  4  and the cable  6  during locking. This multi-point locking, contact generates locking forces which inhibit rotation of the balls in either the clockwise or counter-clockwise directions as seen in FIG.  5 . Such inhibition resists any tendency of cable  6  to be rotated within housing  4 , which rotation often occurs during attempts to defeat the seal. The multi-point locking contact is particularly effective with respect to larger diameter cable, e.g. Cable having an effective diameter in excess of {fraction (1/16)} inch. 
     The locking balls  52 ,  54  are of differing diameters such that they each can engage the edges of groove  33  of bore  32  and the surface of cable  6  at the same time. 
     Disposed between ball  52  and closure  56  is a spring  50  which biases the ball  52  toward the smaller end of conical bore  32  such as to tend to hold the ball  52  in contact with V-shaped groove  33  and cable  6 . Spring  50  may be a coil spring as shown, or any other form of known biasing means which can perform the desired function of urging ball  52  toward the smaller end of conical second bore  32 . Balls  52 ,  54  are preferably steel balls which are provided with a roughened surface. In this regard, it has been found that a ball surface roughened to fifty (50) microfinish or more provides resistance to movement between the balls and the cable such as to improve locking and resistance to removal for purposes of defeating the seal. 
     In operation, with the first end of cable  6  secured by swaging in first bore  26 , the free second end  10  of cable  6  is passed through the hasps  14  and  16  (FIG.  3 ). Free end  10  is then inserted into aperture  35  at proximal wall  28 . The cable immediately then enters first channel  36 . As the cable  6  advances along the channel path, it engages the underside of first securing ball  54 . At least 50% of the diameter of cable  6  extends upwardly out of first channel  36 , as a result continued advance of the cable tends to lift the ball  54  out of the channel and toward the distal end  34  of the housing and to depress the cable downwardly into first channel  36 . This movement of ball  54  continues until its displacement is such as to permit the cable  6  to pass along the channel  36  and under ball  54  substantially unimpeded. 
     Continued passage of cable  6  in channel  36  causes the second end  10  of the cable  6  to engage the underside of second securing ball  52  in the same manner. Thus, ball  52  also is caused to be displaced upwardly out of first channel  36  and toward the distal end  34  of the housing  4 . Such movement of ball  54 , however, is against the bias of coil spring  50 . Continued passage of cable  6  along channel  36  permits the passage of second end  10  through aperture  60  and out of the housing  4  to establish the desired sealing relationship. 
     Because of the conical shape of bore  32 , the diameter of balls  52  and  54 , and the slope of channel  36  down to the left as seen in FIG. 3, the insertion passage of cable  6  through the housing  4  is resisted substantially only by the force of spring  50  acting against ball  52 . This force is not significant. Just the opposite occurs upon an attempt to withdraw the cable  6  from the housing, i.e. an attempt to displace cable  6  from left to right as seen in FIG.  3 . 
     Considering the locking of cable  6  against withdrawal, it best can be seen in FIG. 3 that movement of cable  6  from left to right, as would occur during withdrawal, causes balls  52  and  54  to be displaced to the right. As the rightward displacement continues, and because of the decreasing diameter of bore  32  from left to right, balls  52  and  54  are also displaced downwardly against cable  6 . Such downward displacement forces cable  6  to be crushed into channel  36  such that at some point the crushing force is sufficient to preclude further movement of cable  6 . It is locked in position and cannot move. In this regard, the balls are initially engaged between cable  6  and second channel  33  at three or four points, i.e. at the edges  37  of channel  33  and either on one or two strands of the cable  6 . To the extent that the locking forces are sufficient to cause crushing of the cable, the loci of the points of engagement between the balls and the cable can only be adequately described as plural. Once cable  6  is inserted into the housing and through channel  36 , the only way to free the seal and lock  2  from hasps  14  and  16  is to cut the cable  6 . 
     As noted above, one aspect of the present invention contemplates providing balls  52 ,  54  with a roughened surface. Such a roughened surface provides two advantages in support of the locking and sealing function of the device. First, it resists sliding of cable  6  with respect to the surface of the balls  52 ,  54 . Secondly, it resists sliding of balls  52 ,  54  with respect to the edges  37  of second channel  33 . Thus, the roughened surface resists the sliding of balls  52 ,  54  on the edges of second channel  33  which otherwise would permit rolling of balls  52 ,  54  in response to rotational displacement of cable  6  which, of course, might defeat the seal. 
     As an alternative to roughing the ball surfaces, it has been found that coating the balls with a polymer improves the resistance to movement between the balls and the edges of second channel  33 , as well as between the balls and the cable. It is recognized that such plastic material may be caused to strip from the ball surface. However, for lighter applications the plastic coating has been found to be effective. 
     Referring now to FIG. 6, there is shown a security lock and seal in accordance with a second embodiment of the invention, designated generally by the reference numeral  102 . 
     Seal and lock  102  is substantially identical to the seal and lock of FIGS. 1-5 with the exception that it utilizes a single ball  152  to effect locking and securing of the cable  106 . 
     Security locks and seals using only a single ball are appropriate for use in light load situations. The ball  152  is provided with a gripping surface using either roughing or plastic coating to achieve the desired resistance to slippage. The operation of seal and lock  102  is the same as that as described with respect to seal and lock  2  of FIGS. 1-5. 
     What has been described in the detailed description is a preferred embodiment of the invention. It will be recognized that various departures from the preferred embodiment can be made without departing from the spirit and scope of the invention.