Patent Publication Number: US-6219882-B1

Title: Glide assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention pertains to a glide assembly for use with the leg of piece of furniture, such as, for example, a chair, desk or a stool. 
     2. Description of the Prior Art 
     Glides are used upon legs of furniture to provide a wearing and sliding surface for the furniture, and for decorative considerations. Hollow tubular legs extending from a chair or table are specific examples of furniture legs and the glide is mounted upon the leg end so as to contact the floor. The glide provides a smooth wearing surface for the furniture leg thereby avoiding abrasive sliding by the relatively rough or sharp tube end. Glides are provided both as inside gripping and outside gripping with respect to the typically hollow tubular legs of the furniture. 
     Glides should have the ability to swivel or change the angle of inclination of the floor-engaging surface with respect to the furniture leg (that is, two degrees of freedom of movement, typically plus or minus 15 degrees) in order to present a level surface to the floor when the furniture leg tilts. Similarly, glides should have the ability to absorb impact as would be expected during the lifetime of the piece of furniture. It is important, however, to maintain sturdy construction and low manufacturing costs. Low manufacturing costs can typically be achieved by a design with a reduced number of parts. 
     An example of a prior art glide which is inner gripping is disclosed in U.S. Pat. No. 5,010,621 entitled “Glide Assembly with Inside Holding Clip”, issued on Apr. 30, 1991 to Bock and assigned to the present assignee of this application. This prior art glide assembly is inner-gripping with an outer sleeve for mounting upon the end of tubular member. The glide further has an interior upright pedestal with outwardly extending gripping prongs for insertion into the tubular member. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a glide which engages a tubular member, such as the leg of a chair, table or similar piece of furniture. 
     It is therefore a further object of the present invention to provide a glide with the ability to change the inclination of the floor engaging surface with respect to the furniture leg. 
     It is therefore a still further object of the present invention to provide a glide which can absorb impact during the expected life of the piece of furniture. 
     It is therefore a still further object of the present invention to provide a glide which includes a reduced number of components in order to reduce manufacturing costs. 
     These and other objects are attained by providing a glide which includes a circumferential flange that is shaped to spread evenly the loads into the shell. The varying thickness of the bottom and side walls connecting to the flange are designed to flex slightly to attenuate the impact loads as they are transferred to the shell. The glide also has a lip under the flange that allows the shell to be crimped around the glide with less stress induced into the glide while securely holding the glide. The shell design allows an increased crimp angle around the glide to hold it securely without excessively stressing the glide. The male portion of the pivot joint ball is incorporated into the shell. A rivet and a washer/retainer are designed to hold the shell securely to the ferrule while allowing the shell to swivel freely through the full range of plus or minus fifteen degrees. 
     The ferrule has a female portion of the ball joint stamped into its base to receive the ball portion of the shell. This provides a large surface area joint to transfer the loads from the glide to the leg with minimal stresses induced in either the ferrule or the shell. There is a large hole in the bottom of the ball to allow the rivet and shell space to swivel through the required range. The present invention can include an inside-holding or an outside-holding clip within the ferrule. 
     The inside-holding clip is pushed into the ferrule and includes upwardly pointing barbs on the three lower legs of the clip to engage the interior of the furniture leg and to resist being pulled back out. These three legs of the clip additionally are used to transfer the loads from the glide to the furniture leg. The inside-holding clip further includes three upwardly extending arms at a somewhat reduced radius with downwardly pointing barbs to engage the inside of the hollow tubular leg of the piece of furniture. The outside-holding clip includes circumferential ring to engage the outside of the furniture leg. An inwardly sloped flange is formed on the top of the ferrule to hide the outside-holding clip. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein: 
     FIG. 1 is a side cross-sectional view of the inside-holding embodiment of the present invention, with the leg of the furniture piece shown in phantom. 
     FIG. 2 is a top plan view, partly in phantom, of the inside-holding embodiment of the present invention. 
     FIG. 3 is a side cross-sectional view, partly in phantom, of the outer shell of the present invention. 
     FIG. 4 is a top plan view of the outer shell of the present invention. 
     FIG. 5 is a side cross-sectional view of the ferrule of the present invention. 
     FIG. 6 is a top plan view of the ferrule of the present invention. 
     FIG. 7 is a side plan view of the rivet of the present invention. 
     FIG. 8 is a top plan view of the rivet of the present invention. 
     FIG. 9 is a side plan view, partially in cross section, of the washer/retainer of the present invention. 
     FIG. 10 is a top plan view of the washer/retainer of the present invention. 
     FIG. 11 is a top plan view of the clip of the inside-holding embodiment of the present invention. 
     FIG. 12 is a side cross-sectional view of the clip of the inside-holding embodiment of the present invention along plane  12 — 12 . 
     FIG. 13 is a side cross-sectional view of the outside-holding embodiment of the present invention, with the leg of the furniture piece shown in phantom. 
     FIG. 14 is a top plan view of the outside-holding embodiment of the present invention. 
     FIG. 15 is a top plan view of the clip of the outside-holding embodiment of the present invention. 
     FIG. 16 is a side plan view of the clip of the outside-holding embodiment of the present invention. 
     FIG. 17 is a side cross-sectional view of an alternative embodiment of the rivet of the present invention. 
     FIG. 18 is a top plan view of an alternative embodiment of the rivet of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail wherein like numerals refer to like elements throughout the several views, one sees that FIG. 1 is a cross-sectional view of the inside-holding embodiment of the glide assembly  10  of the present invention and, similarly, FIG. 2 is a top view of the inside-holding embodiment of the glide assembly  10  of the present invention. 
     Glide assembly  10  includes a shell  12  which is shown in more detail in FIGS. 3 and 4. Shell  12  is rotationally symmetric about axis  13  (see FIG. 3) and includes an inclined circumferential flange  14 . The outer portion of inclined circumferential flange  14  includes circumferential lip  16  which is crimped to engage the outer circumferential bevel  18  of base  20 . Circumferential lip  16  is illustrated in solid lines in FIGS. 1 and 3 in the uncrimped position and in phantom in the crimped position engaging the outer circumferential bevel  18  of glide assembly  10 . Shell  12  further includes at the interior thereof the partially hemispherically shaped male portion  22  of ball joint  24 . The uppermost portion of partially hemispherically shaped male portion  22  includes aperture  26  centered on axis  13 . Base  20  is typically made of nylon and includes inclined walls  80  which descend from circumferential bevel  18  to lower planar surface  82  which is designed to engage the floor (not shown). The interior of base  20  can include impact pad  84  to absorb energy and to assist in the even distribution of the energy about circumferential flange  14  of shell  12 . 
     Glide assembly  10  further includes ferrule  30  which is illustrated in detail in FIGS. 5 and 6. Ferrule  30  is rotationally symmetric about axis  31 . Ferrule  30  includes cup portion  32  formed from upwardly directed cylindrical walls  34 . The leg of the furniture piece  100  is inserted into cup portion  32 . The floor  36  of ferrule  30  includes outer horizontal portion  38  which is perpendicular to upwardly directed cylindrical walls  34 . Immediately inward from outer horizontal portion  38  is partially hemispherically shaped female portion  40  of ball joint  24 . The upper portion of partially hemispherically shaped female portion  40  includes large aperture  42 . As will be described in more detail hereinafter, large aperture  42  of ferrule  30  is larger than aperture  26  of shell  12  in order to allow shell  12  and ferrule  30  to swivel with respect to each other. This incorporation of the ball joint  24  into portions of shell  12  and ferrule  30  provides for the elimination of the separate ball joint elements of the prior art thereby reducing manufacturing costs while maintaining a large surface area joint to transfer the loads from the glide assembly  10  to the leg of the furniture piece  100  with minimal stresses induced in either the ferrule  30  or the shell  12 . 
     FIGS. 7 and 8 illustrate rivet  50  which passes through apertures  26  and  42  to engage washer/retainer  55  (see FIGS. 9 and 10) thereby holding ferrule  30  to shell  12  and providing a swivel arrangement therebetween. Rivet  50  is rotationally symmetric about axis  51 . Rivet  50  includes lower dome  52  which engages underneath the interior portion of partially hemispherically shaped male portion  22  of ball joint  24  and is of complementary curvature thereto. Rivet  50  further includes upper crimping portion  54  which extends upwardly through large aperture  42  of ferrule  30  and central aperture  59  of washer/retainer  55  (see FIGS.  9  and  10 ). 
     Washer/retainer  55  is illustrated in FIGS. 9 and 10. Washer/retainer  55  includes central aperture  59  and downwardly extending rotationally symmetric walls  57 . As shown in FIG. 1, downwardly extending rotationally symmetric walls  57  are shaped to engage the upper portion of partially hemispherically shaped female portion  40  of ball joint  24 . However, downwardly extending rotationally symmetric walls  57  are preferably less curved than partially hemispherically shaped female portion  40  and the cross section may have portions that approach linearity. Further, the outer periphery of downwardly extending rotationally symmetric walls  57  include outwardly flared lip  61 . This configuration minimizes or eliminates binding of washer/retainer  55  while swiveling about partially hemispherically shaped female portion  40  of ball joint  24 . 
     Washer/retainer  55  as retained by rivet  50  has sufficient spring clamping action to hold shell  12  tightly to ferrule  30  while allowing full swiveling movement with aperture  42  of ferrule  30  throughout the required range of substantially plus or minus fifteen degrees. 
     FIGS. 17 and 18 illustrate rivet  90  which can be substituted for the combination of rivet  50  and washer/retainer  55 . Rivet  90  is rotationally symmetric about axis  91  and includes upper domed flange  92  which engages partially hemispherically shaped female portion  40  of ball joint  24  and is of complementary curvature thereto. Upper domed flange  92  has sufficient spring clamping action to hold shell  12  tightly to ferrule  30  while allowing full swiveling movement throughout the required range of substantially plus or minus fifteen degrees. Aperture  94  is formed at a central location in rivet  90 . Walls  96  of aperture  94  form a rivet portion to engage aperture  26  of shell  12 . Walls  96  forming the rivet portion are illustrated in the unriveted or uncrimped position in solid lines and in the riveted or crimped position in phantom in FIG.  17 . 
     Inside-holding clip  60  is illustrated in FIGS. 11 and 12. Inside-holding clip  60  includes a central circular support section  62  which further includes a slightly upwardly bowed interior portion  63  to accommodate the shape of rivet  50  and washer/retainer  55 . Three downwardly extending legs  64  and three upwardly extending arms  66  alternate around the circumference of central circular support section  62 . Downwardly extending legs  64  include a generally horizontal outwardly extending portions  68  which are sized to extend to the interior of cylindrical walls  34  of cup section  32  of ferrule  30  into which inside-holding clip  60  is inserted. Downwardly extending legs  64  further include downwardly extending portions  70  which grip the interior of cylindrical walls  34  of cup section  32  of ferrule  30  into which inside-holding clip  60  is inserted. Downwardly extending portions  70  of downwardly extending legs  64  further include upwardly and slightly outwardly extending barbs  72  cut from the material of downwardly extending portions  70  in order to increase the resistance to inside-holding clip  60  being pulled from ferrule  30  without substantially increasing the resistance to the initial insertion of inside-holding clip  60  into ferrule  30 . 
     Arms  66  extend upwardly at a radius somewhat recessed from that of legs  64  for engaging the interior of a hollow tubular leg of the furniture piece  100  and further include downwardly and slightly outwardly extending barbs  74  cut from the material of upwardly extending arms  66  in order to increase the resistance to furniture leg  100  being pulled from inside-holding clip  60  and ferrule  30  without substantially increasing the resistance to the initial insertion of furniture leg  100  into inside-holding clip  60  and ferrule  30 . 
     FIGS. 13-16 relate to an embodiment of glide assembly  10  which engages the outside of the leg of furniture  100  rather than the inside. FIG. 13 includes substantially the same base  20 , impact pad  84 , shell  12 , rivet  50  and retainer/washer  55  of the inside-holding embodiment of FIGS. 1-12. The ring-shaped outside-holding clip  97  replaces the inside-holding clip  60  and is placed immediately inwardly adjacent of walls  34  of ferrule  30 . Outside-holding clip  97  includes inwardly extending tooth-like protrusions  99  cut from the material of clip  97  and used to engage securely the outside of a tubular furniture leg  100 . Ferrule  30  includes walls  34  which include an upper inwardly sloped flange portion  35  to securely hold outside-holding clip  97  therewithin and further to aesthetically conceal clip  97  from view. 
     To assemble the glide assembly  10  of the present invention, typically impact pad  84  is inserted into base  80  and circumferential lip  16  of circumferential flange  14  of shell  12  is crimped around bevel  18  of base  80 . Rivet  50  and washer/retainer  55  (or rivet  90  of FIGS. 17 and 18) are then used to secure ferrule  30  to shell  12 . Inside-holding clip  60  or outside-holding clip  97  is inserted into cylindrical walls  34  of ferrule  30 . If outside-holding clip  97  is used, upper inwardly sloped flange portion  35  could be formed after the insertion of outside-holding clip  97  into ferrule  30 . 
     To attach glide assembly  10  to a piece of furniture, glide assembly  10  is typically pushed onto the end of the leg of the piece of furniture, with the inside-holding clip  60  or outside-holding clip  97  in its respective appropriate position. 
     Thus the several aforementioned objects and advantages are most effectively attained. Although a single preferred embodiment of the invention has been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.