The invention relates to a locking mechanism. More particularly, it relates to a wedge bar locking mechanism for a casket that has only three principal components.
Wedge bar locking mechanisms are generally known in the art, and are described for example in U.S. Pat. No. 5,503,439 which is incorporated herein by reference. In a conventional wedge bar locking mechanism, as described in the '439 patent, a wedge bar is threaded at one end to a screw so that as the screw is turned, the wedge bar is caused to move longitudinally so that a series of catches spaced along the length of the wedge bar engage a series of corresponding escutcheons or rollers to pull the lid of the casket tightly closed. In this conventional mechanism, the discrete parts include a wedge bar, a screw, a bracket, and a bronze clip. The bracket is necessary to prevent rotation of the wedge bar, and the clip retains the screw in place in the bracket in order to prevent longitudinal movement of the screw.
While the above-described mechanism has been successful, it suffers from a number of drawbacks. First, both the wedge bar and the bracket require numerous stamping and bending operations in order to provide their complex shapes. Second, the bronze clip must be assembled to the bracket after the screw is inserted into the bracket. Being a separate piece, the clip can come out which may result in failure of the mechanism by permitting longitudinal translation of the screw. Third, the bracket has many complex bends which must conform to particular dimensions, and the slot to accommodate the screw and the bronze clip also must be precisely formed and dimensioned. Fourth, the assembly includes four separate components that must be separately made, contributing to the overall complexity and cost.
There is a need in the art for a wedge bar locking mechanism for a casket where the means for securing the screw in position in the bracket are not prone to detachment from the bracket, thus eliminating a key failure mode of the mechanism. Preferably, such an improved mechanism has fewer than four separate components, and will be simple and relatively inexpensive to manufacture.
A wedge bar locking mechanism is provided having a locking pin, a wedge bar and a bracket. The locking pin includes a reduced diameter portion and a threaded portion, wherein the threaded portion has a continuous helical groove disposed circumferentially about and extending longitudinally of the threaded portion. The wedge bar includes first and second longitudinally extending portions at a proximal end thereof, wherein the first and second longitudinally extending portions define a locking pin receiving space therebetween. At least one of the first and second longitudinally extending portions has at least one tooth extending into the pin receiving space defined between the first and second longitudinally extending portions. The tooth is dimensioned to extend into and be accommodated within the helical groove when the threaded portion is received in the pin receiving space. The bracket defines has a longitudinally extending slot to accommodate the wedge bar therein, and a longitudinally extending cylindrical portion defining a longitudinal cylindrical pathway adapted to accommodate the locking pin therein. The slot is effective to prevent the wedge bar from rotating as a result of torque supplied to the locking pin when the locking pin and the wedge bar are received, respectively, in the longitudinally cylindrical pathway and the slot.
A further wedge bar locking mechanism is provided, having a locking pin, a wedge bar and a bracket. The locking pin has a reduced diameter portion and a threaded portion, wherein the threaded portion has a continuous helical groove disposed circumferentially about and extending longitudinally of the threaded portion. The wedge bar has a longitudinally extending portion at a proximal end thereof, the longitudinally extending portion having at least one tooth dimensioned to extend into and be accommodated within the helical groove disposed in the threaded portion of the locking pin. The bracket defines a longitudinally extending slot adapted to accommodate the wedge bar therein, and a longitudinally extending cylindrical portion defining a longitudinal cylindrical pathway adapted to accommodate the locking pin therein.
Referring to
As can be seen in
The reduced diameter portion 22 is preferably provided via machining, for example using a lathe as is known in the art. The threaded portion 23 is preferably provided in the form of an Acme threaded rod, most preferably a #5 Acme threaded rod. The threads can be provided, for example, by turning on a metalworking lathe to provide a continuous helical groove 24 along the length of the threaded portion 23. The helical groove 24 is provided circumferentially about the outer surface of the threaded portion 23, and extending longitudinally along the length of the threaded portion. Alternatively, and less preferably, conventional screw threads can be used for the threaded portion 23. Acme threads are more preferred generally because they are larger threads (i.e. they have a lower thread pitch in terms of number of threads per inch) and they have a deeper groove which is highly suited for interlocking with appropriately dimensioned teeth 35 to effect longitudinal translation of the wedge bar 14 as explained below. This facilitates faster, more convenient and more reliable and repeatable locking of a casket because fewer turns are required, and because the teeth 35 will be securely retained in the groove 24 as the locking pin 12 is turned.
Alternatively, the locking pin 12 can be made from a plastic material having physical properties sufficient to withstand the mechanical and torsional stresses to which it will be subjected during use. In this embodiment, preferably the locking pin 12 is made, e.g. molded, via conventional techniques from a high strength ABS plastic or equivalent material, or other plastic material having comparable or superior physical strength.
Whether the locking pin 12 is made from metal or plastic, the helical groove 24 for the preferred embodiment extends longitudinally along the length of the threaded portion 23, but does not continue all the way to the ends. The helical groove terminates at hard stops located at either end of the threaded portion 23, respectively a proximal hard stop 25 located adjacent the reduced diameter portion 22, and a distal hard stop 26 located adjacent the distal end of the locking pin 12. The purpose of these hard stops will become evident below.
The wedge bar 14 is provided at its proximal end with a first longitudinally extending portion 31 and a second longitudinally extending cantilevered portion 32. The two portions 31 and 32 are cantilevered from the proximal end of the wedge bar 14, and define a locking pin receiving space 33 between them. The receiving space 33 is dimensional to accommodate the outer diameter of the threaded portion 23 of the locking pin 12. The first and second longitudinally extending cantilevered portions 31 and 32 are provided with a plurality of spaced teeth 35 extending generally into the receiving space 33. The spacing of the teeth 35 corresponds with pitch of the threads, preferably helical groove 24, of the threaded portion 23, and the teeth 35 are dimensioned to extend into and be securely accommodated within the helical groove 24 when the threaded portion 23 of the locking pin 12 is received in the receiving space 33. Optionally, only one of the extending portions 31 and 32 need be provided with teeth 35 as will be apparent below.
Referring to
In order for the locking pin 12 and wedge bar 14 to function as described in the preceding paragraph, the pin must be prevented from longitudinal motion or translation and the wedge bar must be prevented from rotational or angular motion. These functions are performed by the bracket 16 is will now be described. The bracket 16 is provided via conventional bending techniques, and is made from a single piece or sheet of metal. The bracket 16 is bent such that it defines a longitudinally extending vertical slot 41 to accommodate and permit translation, but not rotation, of the wedge bar 14 therein. Provided substantially centrally relative to the vertical extent of the slot 41 is a cylindrical portion 42 also extending longitudinally of the bracket 16, and defining a longitudinal cylindrical pathway adapted to accommodate the outer diameter of the locking pin 12.
Preferably, the threaded portion 23 and head portion 21 of the locking pin 12 are of the same or substantially the same diameter, so that each is accommodated abuttingly (though with minimal friction) within the cylindrical portion 42 of the bracket 16 having a substantially constant inner diameter. At least one, preferably a plurality (most preferably a pair) of retaining tabs 45 are provided extending radially inward from the interior surface of the cylindrical portion 42 into the cylindrical pathway at a location corresponding to the position of the reduced diameter portion 22 of the locking pin 12 when it is assembled in the cylindrical pathway of the bracket 16. In the illustrated preferred embodiment, tabs 45 are provided by punching through the bracket 16 wall in the cylindrical portion 42 thereof such that the punched portion of the wall material extends or is cantilevered radially inward of the cylindrical portion 42, still attached to the bracket wall, to provide the tabs 45. This method is preferred because it provides tabs 45 that are integral to the bracket 16, obviating the need for additional or separate tab components to be attached to the bracket 16. Punched tabs 45 can be provided via conventional techniques using a punch once the cylindrical portion 42 of the bracket 16 has been formed, e.g. via bending around a cylindrical template or dowel of suitable diameter. Less preferably, the tabs 45 can be provided as separate components fixed (e.g. brazed or welded) to the inner surface of the cylindrical portion 42 and extending radially inward of the longitudinal cylindrical pathway.
In operation, the locking pin 12 is received within the longitudinal cylindrical pathway defined by the cylindrical portion 42 of the bracket 16, and positioned such that the radially inwardly extending tabs 45 are received and accommodated within the reduced diameter portion 22 of the locking pin 12. The tabs 45 prevent the locking pin 12 from translating longitudinally as the pin is turned, and the vertical slot 41 prevents the wedge bar 14 from rotating as a result of torque supplied to the locking pin 12. In this manner, when the locking mechanism 10 is fully assembled as described herein, rotation of the locking pin results in longitudinal motion or translation of the wedge bar 14 via the cooperating teeth 35 and groove 24.
The locking pin 12 and wedge bar 14 are manufactured as described above and as shown in
The assembly of
As will be appreciated, the wedge bar locking mechanism according to the invention is of a simple and reliable design, and is made from only three principal components.
It is noted that the location of the reduced diameter portion 22 in the locking pin 12 is not critical. Though in the described embodiment it is located between the head and threaded portions 21 and 23, alternatively it can be located at any other location along the pin. For example, the reduced diameter portion 22 can be located at the distal end of the locking pin 12 such that the order from proximal to distal of the pin 12 is: head portion 21-threaded portion 23-reduced diameter portion 22; so long as the tabs 45 are correspondingly relocated to be accommodated within the reduced diameter portion 22 of the locking pin 12 in this new location to restrain translational motion of the pin 12.
In addition, though all components of the wedge bar locking mechanism 10 preferably are made from metal, they can be made from other materials, eg., high strength ABS plastic or equivalent material, or other plastic material having physical strength sufficient to withstand the forces to which each component will be subjected during repeated or recurring use. Sheet metal is strongly preferred for the bracket 16 due to the ability to form it via conventional bending techniques.
The disclosed wedge bar locking mechanism is particularly useful for locking a casket, though it is not intended to be limited solely to that application. Other boxes or containers having a closeable lid, as will be evident to those skilled in the art, also can be provided with the wedge bar locking mechanism according to the invention to effect reversible locking and unlocking thereof in a reliable and repeatable manner.
Although the invention has been described with respect to a preferred embodiment, it will be understood that various changes or modifications can be made without deviating from the spirit and scope of the invention as described above and as defined in the appended claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/469,104 filed May 9, 2003.
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Number | Date | Country | |
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20040222644 A1 | Nov 2004 | US |
Number | Date | Country | |
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60469104 | May 2003 | US |