Abstract:
A caster assembly for supporting an article comprising a housing, a ball bearing, and a bearing retaining member, wherein the housing has a bore extending completely through a central region thereof such that a first opening and a second opening are created on opposite faces of the housing, the first opening defining an annular inner shoulder with a reduced diameter, the ball bearing having a diameter slightly less than a diameter of the bore such that the ball bearing is adapted to rotate within the bore, the diameter of the annular inner shoulder at the first opening being less than the diameter of the ball bearing to allow partial emergence of the ball bearing from the first opening yet preventing the ball bearing from completely exiting the first opening, the bearing retaining member being affixed to the housing at the second opening to retain the ball bearing within the bore.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to casters, and more particularly to casters used to facilitate movement and relocation of articles. Casters are affixed upon each corner of an article (e.g., a caster on each of four corners) such that a load on a set of casters is balanced. More specifically, the present invention relates to an easy to manufacture, affix and use caster that may be used with a variety of articles including furniture, appliances, computer components and other articles. 
     2. Prior Art 
     Casters are well-known in the art for facilitating movement and relocation of various-sized articles for a variety of applications. Known caster designs are typically affixed to an article by its manufacturer prior to use of the article by a consumer or end-user. An example of a caster design that is installed during the article&#39;s manufacturing process is disclosed in U.S. Pat. No. 5,136,751 to Coyne et al. entitled “Wheel Assembly”. 
     Often times in the art it is desirous to utilize a sphere instead of a wheel for the caster design to facilitate ease of movement in any direction on a horizontal surface without changing the orientation of the caster. Moreover, spherical caster design art is typically less complex and expensive to manufacture because they consist of fewer parts. An example of a spherical caster design is disclosed in U.S. Pat. No. 3,893,700 to Dunmyer entitled “Mobile Device”. The caster design of Dunmyer utilizes a spherical caster to facilitate movement. Its construction is comprised of a caster body and a sphere retained in a circular horizontal groove within a recess of the caster body by use of a ball bearing ring that locks onto the recess. 
     Other caster designs are configured to be attached to an article after the article&#39;s manufacturing process. The caster design disclosed in U.S. Pat. No. 3,559,802 to Eidus entitled “Caster Assembly” describes a caster that may be easily added to an article by use of adhesive, as opposed to the use of a screw, bolt or other fastening device. The Eidus caster design utilizes a ball bearing retained within a caster block by use of a separate retaining ring through which the ball bearing extends. In another described embodiment, the caster block and retaining ring are made integral, wherein the spherical opening of the caster block flexes to accept the ball bearing. 
     Therefore, there appears a need in the art for an easy to manufacture, easy to use caster that is reliable and avoids the problems of the known art. There is also a need in the art for a caster that is simple in construction and easy to manufacture. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, the primary object of the present invention is to provide a multi-purpose caster that is durable, inexpensive to manufacture, easy to affix to an article, and easily facilitates movement of the article. 
     Another object is to provide a caster that may be attached to an article by use of an adhesive to provide means for movement of the article. 
     Yet another object is to provide a multi-purpose caster that may be easily manufactured using conventional techniques of injection molding. 
     Still another object is to provide an inexpensive method to manufacture and assemble a multi-purpose caster. 
     These and other objects of the present invention are realized in the preferred embodiment of the present invention, described by way of example and not by way of limitation, which provides for a caster assembly for supporting an article comprising a housing, a ball bearing and a bearing retaining member. 
     In brief summary, the present invention overcomes and substantially alleviates the deficiencies in the prior art by providing a caster comprising a housing with an inflexible opening and a bearing retaining member, both of which retain a ball bearing within a bore of the caster housing. 
     Additional objects, advantages and novel features of the invention will be set forth in the description which follows, and will become apparent to those skilled in the art upon examination of the following more detailed description and drawings in which like elements of the invention are similarly numbered throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a caster in accordance with the present invention. 
     FIG. 2 is a cross-sectional view of a caster taken along line  2 — 2  in FIG. 1 in accordance with the present invention. 
     FIG. 3 is a plan view of a caster from the prospective of the side from which the ball bearing emerges from the caster in accordance with the present invention. 
     FIG. 4 is a plan view of a main body of a caster without a ball bearing and bearing retaining member from the prospective of the side opposite the side shown in FIG. 3 in accordance with the present invention. 
     FIG. 5 is a perspective view of a caster in use on an article in accordance with the present invention. 
     FIG. 6 is a cross-sectional view of a caster taken along line  2 — 2  in FIG. 1 in accordance with an alternate embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, the preferred embodiment of the caster of the present invention is illustrated and generally indicated as  10  in FIG.  1 . Caster  10  may comprise a basic housing  12 . Housing  12 , as shown in FIG. 1, is preferably of a stepped shape, wherein principal top surface  14  is not flush with extension top surface  20  but rather is interrupted by principal side wall  18 . The non-rectangular design of the present invention saves material cost while keeping optimal surface area on the faces of housing  12 . Principal side wall  18 , in its preferred embodiment as shown in FIG. 1, may be observed to be at an inclined angle on its exterior side of 15 degrees from the perpendicular of its intersection with extension top surface  22 . However, the inclined angle of housing side wall  24  may vary from 0 to 45 degrees depending on application use and desired ornamental design; for example, principal side wall  18  may be perpendicular to extension top surface  20 . An angle of 15 degrees is preferred because ideally housing  12  consists of an optimal amount of material while still retaining a durable shape. 
     Housing side wall  24  is shown in FIG. 1 as being perpendicular to principal top surface  14 . Housing side wall  24  may alternatively be at an angle of less than 90 degrees, or as a further alternative, flush with portions of housing  12  (e.g., principal top surface  14 ) so that housing  12  is in a decorative design such as a star, sphere or oblong rectangle. Housing  12  may also be rectangular in shape as principal top surface  14  is flush with extension top surface  20  so as to form a continuous top surface, and principal side wall  18  is flush with extension side wall  22  so as to form a continuous side wall. 
     A portion of ball bearing  16  may be observed protruding from housing  12  in FIG.  1 . Ball bearing  16  is preferably composed of chrome-plated steel and of a type commonly available so as not incur significant materials cost during assembly of the present invention. However, it will be appreciated in the art that ball bearing  16  may be of other materials commonly substituted for ball bearings that are capable of use with the present invention, including stainless steel, glass, plastic, and vulcanized rubber. However, chrome-plated steel is the preferred material for the present invention because it generates an optimal amount of friction between ball bearing  16  and bearing retaining member  28  enabling caster  10  to move smoothly along a surface when a small force is applied to the corresponding article and to cease movement of the article when the force is no longer applied. 
     An adhesive or alternate connection means, such as adhesive tape  26  preferably of the double-sided variety, is shown in FIG. 1 attached to caster  10  at housing underside  30 . Adhesive tape  26  may cover all or a portion of housing underside  30  so as to provide sufficient tackiness to attach caster  10  to an article (as shown in FIG.  5 ). However, the present invention may use other means of affixing caster  10  to a desired article including by use of a hook and loop material such as Velcro®, or by use of screws or nails through housing  12 . It will be appreciated that the use of adhesive tape  26  with the present invention provides the easiest means for caster affixation. 
     Turning now to FIG. 2, a cross section of caster  10  may be viewed. Evident are various portions of housing  12  including principal top surface  14 , principal side wall  18 , extension top surface  20  and extension side wall  22 . Ball bearing  16  may be observed to be retained in bore  40  of housing  12 . Bore  40  is of sufficient diameter to accept and retain ball bearing  16  so that it is able to freely rotate within bore  40 . 
     First opening  32  may be observed to have protruding ball bearing  16 . The diameter of first opening  32  is smaller than the diameter of ball bearing  16  so as to retain ball bearing  16  within bore  40 . Bore  40  is configured to have shoulders  42  at the interior of first opening  32  to provide an annular seat in which to retain ball bearing  16 . 
     A bearing retaining member in the form of plug  28  may be used to seal housing  12 . Plug  28  as shown in FIG. 2 presses against ball bearing  16  so as to retain it within bore  40  and seated against shoulders  42  so that a portion of ball bearing  16  is exposed outside of housing  12 . Plug  28  is preferably flush with housing underside  30 , so that adhesive tape  26  has a continuous surface to cover. Plug  28  is preferably made of the same material as housing  12 , and may be constructed of plastic through known plastic molding techniques. 
     Housing  12 , as well as plug  28 , is preferably plastic and constructed by a plastic molding process, as would be understood by those having skill in the art. An example of this manufacturing process for housing  12  is as follows: First, two molding plates are milled out to the dimensions of housing  12  to form a mold cavity with a stationary and movable molding plate. The smallest side of the caster, principal top surface  14  in the preferred embodiment, is entered the furthest inside part of the mold cavity toward the movable side so that housing  12  can be ejected from the mold cavity. When the mold is closed, melted plastic is injected through the stationary side of the mold to fill the mold cavity. Housing  12  is allowed a short period of time to cool. Thereafter, the movable side of the mold opens and the finished housing  12  is ejected. Plug  28  may be constructed via a similar method as will be appreciated in the art. 
     However, housing  12  and plug  28  may also be manufactured by a milling machine process, as would be understood by those having skill in the art. An example of this manufacturing process for housing  12  is as follows: The manufacturer first obtains an industry standard piece of rectangular plastic stock. The mill head of the milling machine is set to 15 degrees, and the plastic stock is aligned with the mill bit (contained within the mill head) and set for a proper cut. One side of the plastic stock is milled, and then the plastic stock is then rotated 180 degrees in the milling machine and cut on the opposite side thereby defining principal top surface  14  and principal side wall  18 . The mill head is then reset to 0 degrees, and the excess material is milled off of the stock so that extension top surface  20  is perpendicular to the principal top surface  14  as shown in FIG.  2 . The plastic stock is then cut into pieces, each piece forming an individual housing  12 . The pieces of plastic stock are then milled on extension side walls  22  so that housing  12  has the final desired dimensions. 
     The mill bit in the milling machine is then changed to a roundover bit so that bore  40  may be drilled in housing  12 . Next, the drilling configuration of the milling machine is set so that bore  40  will be drilled to a preset depth within housing  12  such that the bit will partially pierce through the side of housing  12  to create first opening  32  and shoulders  42 . Housing  12  is then placed on the mill table against a stop such that housing  12  may be automatically centered and drilled to the desired preset depth. When the roundover bit is removed from housing  12 , bore  40  and shoulders  42  may be observed. Thereupon, the manufacturing of housing  12  in this alternate manufacturing technique is complete for use with the present invention. 
     FIG. 3 provides a plan view of the present invention from the prospective of the side of caster  10  from which ball bearing  16  emerges. Principal top surface  14 , ball bearing  16 , principal side wall  18  and extension side wall  22  may be observed from this view. 
     FIG. 4 provides a plan view of housing  12  from the perspective of housing underside  30  of the present invention without ball bearing  16 , plug  28 , or adhesive tape  26 . The view of FIG. 4 more clearly shows shoulders  42  of first opening  32 , and the contrast of the diameter of first opening  32  and second opening  34 . 
     Caster  10  be may observed in FIG. 5 with its intended use affixed to an article  48 . Four casters  10  may be observed to be affixed to the underside of article  48  so as to provide the benefits of the present invention. 
     Another embodiment of the present invention may be observed in FIG. 6 using an alternative bearing retaining member. Instead of using plug  28  (see FIG. 2) to retain ball bearing  16  within bore  42 , the alternate embodiment of the present invention uses biasing member  36  and plate  38 . Biasing member  36  is shown in FIG. 6 as a spring. Biasing member  36  is inserted into bore  42  and is retained within bore  42  by use of plate  38 . Plate  38  is affixed to housing underside  30 , thereby providing a flush surface for which to affix adhesive tape  26 . Plate  38  is preferably of the same dimensions as main body underside  30 , but may be larger or smaller depending upon the desired application of the present invention. 
     It should be understood from the foregoing that, while particular embodiments of the invention have been illustrated and described, various modifications can be made thereto without departing from the spirit and scope of the invention. Therefore, it is not intended that the invention be limited by the specification; instead, the scope of the present invention is intended to be limited only by the appended claims.