Metal working – Method of mechanical manufacture – Process for making bearing or component thereof
Reexamination Certificate
1999-10-26
2002-12-17
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Process for making bearing or component thereof
C029S527100, C029S898000, C029S898040, C029S898055, C264S271100, C264S275000
Reexamination Certificate
active
06493939
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to assembly lines and conveyor systems, and, in particular, to a flange bearing for supporting a rotatable shaft.
In manufacturing, assembly lines and conveyor systems commonly utilize flange bearings to support cylindrical shafts upon which manufactured products are transported. The bearings are mounted to a support structure which forms a track or bed along which the products are conveyed. Each shaft is received in a bearing insert of a housing for the flange bearing. The flange bearing might comprise a square housing mounted using four bolts, one at each corner. Alternatively, the flange bearing might comprise an eye-shaped housing utilizing two bolts for mounting.
Cast iron was the common material used for manufacturing early flange bearing housings which were mounted by either two or four bolts. A solid body was formed which easily withstood the stresses imparted by the heavy and/or cyclic loads from the shaft supported therein. Further, the cast iron housing was usually either metal-plated or painted to resist corrosion from exposure to water, cleaning chemicals, spilled products or other contaminates, especially in the food processing industry. However, the housing exterior would eventually deteriorate or become unsightly, especially since stringent cleaning was required to meet sanitation specifications in the aforementioned industry.
A more recent type of flange bearing comprises an injection-molded plastic housing. In particular, if the housing is injection molded in the form of solid plastic, the housing would disadvantageously shrink and deform unpredictably upon cooling. In order to provide an injection-molded housing of the equivalent strength of cast iron with repeatable dimensional stability, it is necessary to increase the overall geometry slightly for strength and incorporate a ribbed structure for dimensional stability. the result is an “engineered plastic” housing providing the desired positional geometry incorporating ribs and cavities. In an engineered plastic housing, the ribs provide strengthening to resist stress fractures of the housing from the shaft loading, while maintaining the desired shape during the molding process.
In addition, the cavities of the engineered plastic housing are more difficult and time consuming to clean satisfactorily than a solid body housing. Plugs created to fill the cavities, thereby making cleaning easier, tend to settle after time and during temperature changes so that the outer surface of the housing body is no longer flush, and the same cleaning difficulties remain. Plugs are often made of a different material than the housing and consequently expand and contract at a different rate than the housing causing undesirable cracks, crevices and uneven surfaces.
In view of the foregoing, a need exists for an improved bearing housing that overcomes the problems mentioned.
SUMMARY OF THE INVENTION
The present invention overcomes the aforenoted disadvantages by providing a housing having a lightweight, substantially solid body including an encased reinforcing member. This member provides additional strength and aids in transmitting loads from a shaft supported by the housing radially outwardly to fasteners which are used to mount the housing. The body does not have recesses formed on its mounting surface which could harbor contaminates, and therefore thorough cleaning of the housing is made easy.
The reinforcing member is preferably a loop formed from a band of metal which surrounds the bolt holes and shaft opening of the housing. Ends of the metallic band may be fastened using a screw engaged through holes on the band ends. Alternatively, the band ends may be spot-welded together, or the band may be formed in a continuous loop. In another embodiment, the reinforcing member may comprise one or more substantially straight metallic strips encased within the body material.
An important feature of the present invention is the use of the reinforcing member to provide additional strength to a lightweight body. Stress fractures from heavy and/or cyclic loading from a shaft supported by the housing are less likely to occur as a result of the presence of the reinforcing member in the body. The member may be suspended within the housing material and helps provide transmission of the loading radially outwardly from the shaft to the fasteners.
Another important feature of the present invention is the formation of a substantially solid body which does not include recesses or cavities for the accumulation of dirt, grease or other contaminates. Thus, cleaning the housing to meet sanitation specifications is readily accomplished.
In one preferred embodiment, the housing comprises a generally parallelogram shaped flange bearing. Two bolts in holes in narrow portions of a housing body mount the bearing to a conveyor structure. A rotatable shaft is supported in a bearing insert received in an opening in the housing body. A cover is optionally placed over one end of the shaft to protect passersby and to warn of the moving part contained therein. Alternatively, the housing may comprise a substantially square flange bearing having four bolts for mounting.
A preferred method of manufacturing a reinforced housing of the present invention comprises the steps of:
a) preparing a mold for the housing including desired openings for receiving one or more fasteners and a shaft;
b) preparing a metallic band for insertion into a space of the mold, with the band forming a shape smaller than the mold's outer shape;
c) suspending the band within the mold;
d) pouring a thermosetting material into the mold to encase the band; and
e) cooling the material thereby creating a substantially solid yet lightweight body reinforced by the band contained within. In this method, Step b) may comprise using a screw engaged through holes in the ends of the band which is shaped into a loop. Alternatively, Steps b) and c) may comprise suspending one or more substantially straight metallic strips in the space of the mold as the reinforcing members, instead of a loop.
Further advantages and applications will become apparent to those skilled in the art from the following detailed description and the drawings referenced herein.
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Knobbe Martens Olson & Bear LLP
Omgba Essama
Valu Engineering, Inc.
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