Patent Publication Number: US-9404285-B2

Title: Cylinder guard for deadbolt lock

Description:
RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 14/091,383, filed on Nov. 27, 2013, entitled “Cylinder Guard for Deadbolt Lock” which claimed the benefit of U.S. Provisional Patent Application Ser. No. 61/731,145, filed Nov. 29, 2012, entitled “Cylinder Guard for Deadbolt Lock.” These applications are hereby expressly incorporated by reference in their entirety into the present application. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to deadbolt locks and particularly to deadbolts that are resistant to attack. More particularly, the present invention relates to a cylinder guard for a deadbolt lock. 
     BACKGROUND 
     One way in which would-be intruders attempt to gain access to a locked structure is by direct attack against a deadbolt lock. For example, they may apply repetitive downward blows against the deadbolt cylinder guard or escutcheon, using a vertical impactor. Depending upon the lock grade, fewer or greater blows in the neighborhood of 75 ft-lbf may be used to breach the lock. This occurs when the upper portion of the guard or escutcheon is indented enough to pull the upper portion away from the door to such an extent that the intruder can manipulate any exposed lock mechanism by hand or with a screwdriver, while manually attempting to withdraw the bolt from the strike by end pressure. Existing protection systems include the use of various die-cast zinc guard or multi-piece steel guards. However, they entail considerable costs to manufacture and may not provide the most robust of security. 
     SUMMARY 
     According to one aspect, the invention provides a guard pressed out of a single piece of steel. This yields significant cost savings. In addition, the guard includes stiffeners that strengthen the regions of the guard which are normally most vulnerable, namely the interface of the guard with the door. Also, the guard of the present invention may include a crush zone to attenuate the amount of energy of an attack that reaches this interface. 
     According to some embodiments, the cylinder guard includes a one-piece member defining a generally cylindrical wall having a predetermined thickness and a longitudinal axis and having a face portion and an inner portion. The face portion defines an annular lip, and the inner portion defines a doubled portion at a first terminus thereof. The doubled portion further defines a radial flange extending radially outwardly, an axial flange, and an end surface at the first terminus. 
     According to a further aspect, the invention provides a cylinder guard for a deadbolt lock having stiffeners formed on an end surface thereof. The stiffeners may include a plurality of indentations equally spaced about the end surface. The stiffeners can be defined by radially-extending or circumferentially-extending indentations. 
     In some embodiments, the cylinder guard has a crush zone intermediate the face and inner portions thereof for attenuating the energy from an attack that is transferred to the axial and radial flanges formed on the rear portion. 
     In another aspect, depending on the circumstances, the invention provides a cylinder guard for a deadbolt lock having a blow-deflecting portion in a crush zone intermediate the face and inner portions thereof. 
     In a still further aspect, the invention provides a method of making a cylinder guard for a deadbolt lock including the steps of stamping a generally cylindrical body having a longitudinal axis from a single piece of steel having a predetermined thickness, forming a flange extending radially outwardly from one end of the body, and forming a double-wall portion between the one end and the flange. 
     Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrated embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be described hereafter with reference to the attached drawings which are given as non-limiting examples only, in which: 
         FIG. 1  is a perspective view of a deadbolt lock containing a cylinder guard according to an embodiment of the present invention. 
         FIG. 2  is a perspective view of a deadbolt lock not containing a cylinder guard according to an embodiment the present invention after undergoing a typical attack. 
         FIG. 3  is a perspective view of a deadbolt lock containing a cylinder guard according to an embodiment of the present invention after undergoing a typical attack. 
         FIG. 4  is a perspective view of a deadbolt lock with the cover removed and showing a conventional die-cast zinc cylinder guard. 
         FIGS. 5A and 5B  are front and rear perspective detail views, respectively, of the die-cast zinc cylinder guard of  FIG. 4 . 
         FIG. 6A  is a cross-section, taken from the side, of a deadbolt lock sub-assembly including yet another conventional die-case zinc cylinder guard, augmented by an adapter. 
         FIG. 6B  is a perspective detail view of the adapter of  FIG. 6A . 
         FIG. 6C  is a cross-sectional view of the adaptor of  FIG. 6B  taken along line  6 C- 6 C. 
         FIG. 6D  is an enlarged sectional detail view of the adapter of  FIG. 6B  taken at the area circled in  FIG. 6C . 
         FIG. 7A  is a perspective view of a conventional multi-piece steel cylinder guard subassembly. 
         FIG. 7B  is a cross-sectional detail view taken along line  7 B- 7 B of  FIG. 7A . 
         FIG. 8  is a perspective view taken from one end of one embodiment of a cylinder guard of the present invention. 
         FIG. 9  is a perspective view taken from one end of another embodiment of a cylinder guard of the present invention. 
         FIG. 10  is a perspective view taken from the other end of yet another embodiment of a cylinder guard of the present invention. 
         FIG. 11  is a perspective view of the cylinder guard of  FIG. 8  taken from the other end. 
         FIG. 12  is a side elevational view of the cylinder guard of  FIG. 11 . 
         FIG. 13  is a cross-sectional view of the cylinder guard of the present invention taken along line  13 - 13  of  FIG. 12 . 
         FIG. 14  is a left side elevational view of the cylinder guard of  FIG. 12 . 
         FIG. 15A  is an enlarged sectional detail view of the circled area of  FIG. 13 . 
         FIG. 15B  is an enlarged detail view of the circled area of  FIG. 12 . 
         FIG. 16  is a cross sectional view taken from the side of a deadbolt lock containing a cylinder guard according to an embodiment of the present invention mounted on a door. 
         FIG. 17  is a perspective view of another embodiment of a cylinder guard for a deadbolt lock of the present invention. 
         FIG. 18  is an enlarged detail perspective view, partially in cross-section, of the cylinder guard of the present invention taken along line  18 - 18  of  FIG. 17 . 
         FIGS. 19A through 19E  are schematic views of various steps in a method according to according to an embodiment of the present invention of making a cylinder guard for a deadbolt lock of the present invention. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the invention, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     As shown in  FIG. 1 , a deadbolt lock  10  includes a brass cover  12 , a cylinder  14 , and is mounted on a door  16  so that a lock bolt  18  is positioned to lock the door. 
     The results of a typical attack on the lock  10  not having a cylinder guard according to the present invention are shown in  FIG. 2 . Downwardly-directed blows by an impactor against the deadbolt lock  10  have produced a dent  20  in the cover  12 , thereby creating a gap  22  between the rear of the deadbolt lock and the door  16 . This gap  22  now permits an intruder to gain access to the lock mechanism (not shown), thereby breaching the lock&#39;s security. Including a cylinder guard of the present invention, however, enables the deadbolt lock  10  to withstand the attack.  FIG. 3  shows that the downwardly-directed blows have produced a dent  20 , but have failed to separate the rear of the deadbolt lock  10  from the door  16 , thereby preserving the lock&#39;s security. 
       FIG. 4  illustrates a deadbolt lock  10 , with the cover  12  removed to reveal a conventional die-cast zinc cylinder guard  24 . Details of the zinc cylinder guard  24  are shown in  FIGS. 5A and 5B . 
     Another conventional zinc die-cast cylinder guard  25  is shown in  FIG. 6A . An adapter  26  is disposed between the zinc guard  25  and the door  16 , and is required to support the zinc guard against attack. As shown in  FIGS. 6B, 6C and 6D , adapter  26  includes indentations  28  formed on adapter flange  30  axially inwardly from an inner end  31  of inner channel  32  and radially-inwardly of an outer rim  34  of adapter flange  30 . The indentations  28  are designed to strengthen the inner channel  32 . 
     A conventional two-piece steel guard subassembly  36  is illustrated in  FIGS. 7A and 7B . Two-piece steel guard assembly  36  includes a steel back plate  38  and a steel guard member  40 . Guard member  40  includes a radially-inward lip portion  42 . A thin cover  44  holds the back plate  38  against the guard member  40 . For that purpose, cover  44  includes a back lip  46  and a cover lip portion  48  engaging the back plate  38  and lip portion  42  respectively, as can be seen in  FIG. 7B . This subassembly yields a cylinder guard which is less robust at the typical region of attack. 
     One embodiment of a cylinder guard  50  of the present invention is shown in  FIGS. 8, 11, 12, 13, 14, 15A, 15B and 16 . With particular reference to  FIG. 13 , the guard  50  includes a generally cylindrical wall  52  defining a longitudial axis  53 , a face portion  54  having a face end  55 , and an inner portion  56 . The inner portion  56  defines a doubled portion  58  disposed at a first terminus  60  of the inner portion  56  of the wall  52 . The doubled portion  58  is created by the wall  52  bending axially away from the first terminus  60 , thereby forming an outer wall  61 , as shown in more detail in  FIG. 15A . The outer wall  61  extends radially outwardly at a second terminus  62  to form a radial flange  64 . 
     With continued reference to  FIGS. 13 and 15A , and with additional reference to  FIG. 12 , the diameter of radial flange  64  is 2.371 inches and the diameter of the outer surface  63  generated by the outer wall  61  is 2.096 inches in some embodiments, while the distance between the innermost surface  65  of radial flange  64  to the face end  55  of the cylinder guard is 0.887 inch in some embodiments. 
     With further reference to  FIG. 15A , the doubled portion  58  includes an inner face portion  66  defined by two arcuate portions  68 . In some embodiments, the arcuate portions  68  have radii of 0.067 inches. The face portion  66 , wall  52  and outer wall  61  of doubled portion  58  together define an axial flange  67 . 
     Now referring to  FIG. 13 , the wall  52  also defines a crush zone  69  intermediate the face portion  54  and the inner portion  56  of the cylinder guard  50 . The purpose of the crush zone  69  is to cause the face portion  54  to collapse under the blows of an attack, thereby attenuating the amount of energy that can be transferred to radial flange  64  and axial flange  67 . In one embodiment of the cylinder guard  50 , the crush zone  69  is created at least by using a very malleable steel, namely ASTM 1008 DS or DDS drawing steel or deep drawing steel. In another embodiment of the cylinder guard  50 , the entire cylinder guard wall  52  is formed of a single piece of such steel, in the range of from 0.055 inches to 0.066 inches thick. 
     Still referring to  FIG. 13 , the crush zone  69  further includes a blow-deflecting portion  70  disposed intermediate the inner portion  56  and a radially inwardly-extending lip  71  disposed at the face end  55  of the cylinder guard  50 . In one embodiment, the blow-deflecting portion  70  extends linearly axially towards the lip  71  and radially inwardly, essentially forming a conical portion having an outer surface at an angle α with the horizontal. The purpose of the blow-deflecting portion  70  is to cause, as much as possible, the blows from an attack to glance away from the inner portion  56  of the wall  52 . In one embodiment, the angle α is 14°. However, it is believed that a gradually curvilinear convex surface for the blow-deflecting portion  70  should also work. 
       FIG. 10  illustrates another embodiment of the cylinder guard  50 ′, in which an array of through-slots  72  is formed in the crush zone  69 . In the embodiment shown, the through-slots are rectangular and are disposed at least partially in the blow-deflecting portion  70 . In one illustrative embodiment, from 6 to 8 through-slots  72  are disposed circumferentially equidistance about the crush zone  69 . For example, there could be 6 through-slots  72 , each having a length of 0.4 inches and a width in the range of from 0.060 to 0.120 inches. In some cases, the through-slots  72  begin about midway in the blow-deflecting portion  70  and extend axially rearwardly. The purpose of the through-slots  72  is to enhance the blow-distorting effects or crushability of the crush zone  69 . 
     Referring now to  FIGS. 8, 11-14 and 15A and 15B , an embodiment of the cylinder guard  50  is shown that includes an array of stiffeners  76  disposed circumferentially equidistantly about the inner face portion  66  of the wall  52 . The stiffeners  76 , in the form of radial indentations  78 , increase the surface area of the axial flange  67 , thereby increasing the moment of inertia in the region of the inner portion  56  of wall  52 , against which an attack would likely be directed (see  FIGS. 2 and 3B , and  FIG. 16 ) and more specifically, at the area of the axial flange  67 . In some cases, the stiffeners  76  include from 15 to 26 radial indentations  78  having a base  82  defining an arcuate cross-section, as can more particularly be seen in  FIGS. 13, 14, 15A and 15B . In some cases, the diameter of the arcuate cross-section  82  is 0.080 inches. 
     Another embodiment of the cylinder guard is shown in  FIG. 9 , in which stiffeners  76  are defined by a plurality of equally-spaced circumferential indentations  80  formed in the axial flange  67 . In this embodiment, the circumferential indentations  80  have generally triangular cross-sections. 
     Although an embodiment of the cylinder guard  50  has been described as being formed of a single piece of steel, principles of the present invention may also be applied to a multi-piece guard. For example, the multi-piece conventional guard  36  with thin cover  44  can be made more robust in withstanding a typical attack by equipping the guard  36  with an axial and vertical flange, as can be seen in  FIGS. 17 and 18 . Here, in the embodiment shown, a multi-piece steel guard  90  using principles according to the present invention includes a steel guard member  40 , a significantly modified steel back plate  38 ′ and a modified cover  44 ′ connecting the steel back plate to the steel guard member. 
     In this embodiment, the steel back plate  38 ′ is formed of a single piece of steel, which in some embodiments could be from 0.045 inches to 0.055 inches thick. Back plate  38 ′ defines an axial flange portion  92  and a radial flange portion  94 , located adjacent the outer circumferential rim  96  of the back plate. Referring to  FIG. 18 , the axial flange portion  92  is in turned defined by a radially-inner axial portion  98  together with a generally parallel radially-outer axial portion  100  joined by a radial portion  102 . The radial portion  102  serves as an inner face portion  66 ′ for the axial flange portion  92 . A plurality of back plate stiffeners  104  are formed equidistantly circumferentially about the inner face portion  66 ′. In some cases, back plate stiffeners  104  are formed by radial indentations  106  having bottom surfaces  108  with generally arcuate cross-sections. The radial flange portion  94  extends radially outwardly from the axial flange portion  92  to engage the guard member  40 . Back lip  46 ′ of cover  44 ′ extends radially inwardly to retain plate  38 ′ against guard member  40 . The back lip  46 ′ of the cover  44 ′ and the radial flange portion  94  cooperate to form a radial flange that abuts a door  16  upon installation of the deadbolt lock  10 . 
     Thus, employing principles of the present invention, stiffeners  104  have increased the surface area of the axial flange portion  92 , thereby increasing the moment of inertia in the region of the guard  90  against which an attack is usually directed, and thereby decreasing the chances that the deadbolt&#39;s security will be breached by repeated blows of such an attack. 
     A method for making a one-piece steel cylinder guard  50  according to an embodiment of the present invention is illustrated in  FIGS. 19A-19E , which schematically depict the side views of the guard during an important portion of the progression of stamping performed by a multi-station tool. In some embodiments, a 200-ton punch press is used to punch the parts out of ASTM 1008 DS or DDS deep drawing steel strip have a thickness of from 0.055 inches to 0.066 inches. 
     As shown in  FIGS. 19A-19E , a cup-shaped body  110  is initially formed and maintained throughout most of the process. A generally cylindrical body open at both ends is formed towards the end of the process when a bottom portion  112  of the body is removed.  FIG. 19A  shows the cup-shaped body  110  having been formed with a radial flange  114  at substantially right angles to the cup-shaped body. In  FIG. 19B , the flange  114  has been simultaneously bent axially rearwardly to a predetermined angle A 1  and formed with a curved portion  116  at the end of the flange  114 , the curved portion having a predetermined radius R 1 . In  FIG. 19C , the flange  114  has been axially bent still farther to a predetermined angle A 2  less than A 1 .  FIG. 19D  shows that the flange  114  has now been bent axially rearwardly to an extent that inner and outer generally parallel wall portions  118 ,  120 , respectively, are formed, while simultaneously bending curved portion  116  so that the radially-outer end  122  thereof is substantially perpendicular to the axis A of the body  110 , and so that the outer end  122  is joined to the outer wall portion  114  at a predetermined radius R 2 , where R 2  is less than R 1 .  FIG. 19E  illustrates the flange radius R 3  having been reduced to the desired finished radius of 0.030 inches. 
     Therefore, the one-piece steel cylinder guard  50  and the method for making it according to an embodiment of the present invention have provided robust protection against attack upon a deadbolt lock, at considerable savings in material cost and manufacturing time over conventional cylinder guards. 
     Although the present disclosure has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the present disclosure and various changes and modifications may be made to adapt the various uses and characteristics without departing from the spirit and scope of the present invention as set forth in the following claims.