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Spherical bearing arrangementsSpherical bearing arrangements description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070181228, Spherical bearing arrangements. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001]The present invention relates to a spherical bearing arrangement and a method of manufacture thereof. BACKGROUND AND DESCRIPTION OF RELATED ART [0002]A spherical bearing arrangement comprises a spherical ball mounted in a housing. The ball is mounted in the housing such that it can rotate freely in all directions but without allowing any (or at least very minimal) translational movement relative to the housing. The ball is sometimes mounted in the housing such that there is a predetermined torque or clearance between the ball and housing. Such spherical bearing arrangements are well known and find application in the aerospace and automotive industries. [0003]The preferred method of mounting the ball in the housing is to swage (i.e. deform) at least a portion of the housing onto and around the ball to entrap it therein--thereby preventing relative translational movement. After swaging, the outer surface of the ball and the inner surface of the housing conform closely to one another so as to form a bearing interface--thereby affording relative rotational movement. To ensure close conformity of the two surfaces post-swaging (i.e. after swaging), a machining step is sometimes carried out on the inner surface of the housing pre-swaging (i.e. before swaging). [0004]In order for the housing to be effectively swaged onto the ball, the material from which the housing is made must be sufficiently ductile to withstand the deformation caused by the swaging process. It is widely accepted, therefore, that housings having a high ductility are the most suitable for the swaging process. By high ductility is meant that ductility is in the order of 10% and greater. [0005]Prior art bearing housings are manufactured from a stock `billet` of metal. A billet of metal simply comprises a large block of a cast metal (or a mixture of metals, according to the customer's requirement). The billets are delivered to the bearing housing manufacturer and are then machined (e.g. cut, milled, drilled etc) to create the bearing housing to swage onto the ball. It will be appreciated that a large volume of material is removed in this process (sometimes >80%). [0006]However, due to the nature of the casting process, the cast billets tend to have a large grain size which contributes to their having a low ductility. By low ductility is meant that ductility is in the region of less than 10%. Furthermore, the grain structure of cast materials is not uniform, which acts further to reduce the ductility thereof. [0007]When a swaging operation is performed on cast articles having such low ductility, the articles tend to crack and fail; at the very least, the swaging is not performed to a satisfactory, repeatable, level. In the case where the article is a housing for a spherical bearing arrangement, it is a strict requirement that certain characteristics of the resultant bearing arrangement (e.g. torque, clearance etc.) are maintained within a narrow, predetermined range. Any manufactured bearing arrangements having characteristics falling outside of these ranges need to be re-worked or even scrapped, at high financial cost. [0008]Accordingly, to avoid cracking or otherwise mechanical failure of the bearing housing during the swaging process--which can result in the characteristics of the bearing falling outside of the predetermined range(s)--it is accepted that the cast billet must first be mechanically worked in order to increase its ductility to a suitable level where swaging can be performed with satisfactory, repeatable, results. [0009]Such mechanical working of the billet material involves at least one process of, for example, forging, extruding and rolling. Following such processes having been carried out, the resultant worked material has a small equiaxed grain structure, which acts to increase the ductility of material to a level that is sufficient to allow for swaging to be effectively carried out, without the risk of cracking or mechanical failure occuring. [0010]Furthermore, to ensure a suitable level of ductility of the worked material is achieved, only billet metals and materials having a relatively high initial ductility are considered. Examples of such metals are steel and copper/bronze. Indeed, even if materials having a low initial ductility are mechanically worked in an attempt to increase the ductility thereof, these operations still do not result in a material having a ductility suitable for swaging. Materials having a low initial ductility, therefore, are simply not considered as being suitable for mechanically working to elevate ductility or for swaging operations per se. [0011]It will be appreciated that the separate "mechanical working" operations of forging, extruding, rolling and/or machining etc add many additional steps to the manufacturing process over that of the initial casting and the later machining to form the bearing housing ready for swaging. In addition, materials having a high ductility such as steel and copper/bronze are expensive in comparison to other materials having a relatively lower ductility. However, such methods and materials have hitherto been accepted as necessary in order to manufacture a housing having the desired ductility to enable the housing to be effectively swaged around and onto the ball without the risk of cracking or mechanical failure. SUMMARY OF THE INVENTION [0012]It is an object of the present invention to seek to overcome at least some of the aforementioned problems. [0013]Accordingly, one aspect of the present invention provides a method of manufacturing a spherical bearing arrangement, the method comprising: providing a ball and a cast bearing housing; elevating the ductility of the cast bearing housing; and swaging the housing onto the ball whilst the ductility is elevated, the ductility lowering after swaging. [0014]Preferably, the method further comprises: performing at least one machining operation on the cast housing prior to swaging thereof. [0015]Advantageously, the method further comprises: performing at least one machining operation on the resultant spherical bearing arrangement. [0016]Conveniently, the elevation of the ductility is performed by heating the housing. [0017]Preferably, the ductility is lowered after swaging by cooling the housing. [0018]Advantageously, the ductility of the housing prior to elevation is less than 10%. [0019]Conveniently, the ductility of the housing prior to elevation is less than or equal to substantially 9%. [0020]Preferably, the ductility of the housing prior to elevation is less than or equal to substantially 8%. [0021]More advantageously, the ductility of the housing prior to elevation is less than or equal to substantially 7%. Continue reading about Spherical bearing arrangements... Full patent description for Spherical bearing arrangements Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Spherical bearing arrangements patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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