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  Cross jointRelated Patent Categories: Abrading, Abrading Process, Roll, Roller, Shaft, Ball, Or Piston AbradingThe Patent Description & Claims data below is from USPTO Patent Application 20070077869. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] The present Application is a Divisional Application of U.S. patent application Ser. No. 10/660,754, filed on Sep. 12, 2003. BACKGROUND OF THE DISCLOSURE [0002] The present invention relates to a cross joint (joint cross coupling, universal joint) used in a steel rolling mill or the like. [0003] In, for example, a steel rolling mill, a cross joint is interposed between a roll and a drive shaft for driving to rotate the roll, a steel rolling processing of the steel material can be carried out by rotating to move the role in accordance with rotation of the shaft while the roll is allowed to move in an up and down direction relative to a steel material which is being rolled. The cross joint includes: a cross shaft member (cross) having four shafts arranged in a cross-like shape; and a cross bearing which has a plurality of cylindrical rollers as rolling members aligned at surroundings of the respective shafts of the member, and a bearing cup as an outer ring mounted to an outer side of outer peripheries of the rollers. Each of outer peripheral portions of the shafts is used as an inner ring race portion. Further, according to the cross joint, the roll and the drive shaft are connected to a first shaft and a second shaft comprising respective pairs of shafts arranged on straight lines in the four shafts respectively via the cross bearings and (rotational) torque from the shaft is transmitted to the roll via the cross joint. [0004] Meanwhile, according to the above-described conventional cross joint, such a cross shaft member and the bearing cup are provided, which are generally constituted by bearing steel of carburized steel or the like. [0005] However, when large torque acts on the cross joint such as in the steel rolling mill, the joint is used under a very severe condition and there is a concern that even when the bearing steel is used, malfunction is brought about at an early stage. In details, the cylindrical roller is rolled on the inner ring race portion or the like formed at the cross shaft member under high contact surface pressure and therefore, exfoliation is liable to be brought about at the race portion. Further, according to the cross member, since the roll and the drive shaft are respectively connected to the contiguous pairs of shafts and therefore, large bending stress may be operated to a shoulder portion between shaft root (shaft neck) portions thereof and fatigue breaking of bending fatigue breaking or the like is liable to be brought about at the member. SUMMARY OF THE INVENTION [0006] In view of the above-described conventional problem, it is an object of the invention to provide a cross joint capable of prolonging rolling fatigue life of a rolling portion (life of rolling bearing), capable of increasing a fatigue strength of the cross joint and therefore, capable of achieving long life formation (ling fatigue life). [0007] In order to solve the aforesaid object, an exemplary embodiment of the invention has a cross joint with a cross shaft member including four shafts, each having a neck portion and a race portion, and shoulder portions between two neck portions, rolling members adapted to rotate around the race portions, and bearing cups fitted to the respective shafts via the rolling members. The race portions and the shoulder portions are subjected to roller burnishing. [0008] In another exemplary embodiment of the invention, a race portion formed on the outer ring member is subjected to roller burnishing. [0009] In a further exemplary embodiment of the invention, a residual compressive stress at a depth of approximately 0.3 mm from each of the surfaces of the race portions and the shoulder portions subjected to the roller burnishing is equal to or larger than 800 MPa. [0010] In yet another exemplary embodiment of the invention, the cross shaft member and the bearing cup includes a carbon steel having a carbon content equal to or larger than 0.42 weight %. [0011] In another exemplary embodiment of the invention, a method of manufacturing a cross joint which includes: a cross shaft member including, a four shafts each having a neck portion and a race portion, and shoulder portions between two neck portions, rolling members adapted to rotate around the race portions, and bearing cups fitted to the respective shafts via the rolling members. The method includes subjecting the race portions and the shoulder portions to roller burnishing. [0012] In a further exemplary embodiment of the invention, a method includes subjecting a race portion formed on a bearing cup to roller burnishing. [0013] According to the above-described cross joint, by subjecting the race portion and the shoulder portion of the cross shaft member to roller burnishing, the hardness of each of surfaces of the race portion and the shoulder portion can be increased and a residual compressive stress immediately below the surface can be increased. Further, a roughness of each of the surfaces can also be decreased. [0014] According to the cross joint, the hardness of the surface of the race portion of the outer ring member can be increased and the residual compressive stress immediately below the surface can also be increased. Further, the roughness of the surface can also be decreased. [0015] According to the cross joint, in comparison with the above-described conventional product, the fatigue strength of the race portion and the shoulder portion can further effectively be increased. [0016] According to the cross joint, the fatigue strength substantially comparable to that of the conventional bearing steel can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG. 1 is an outline sectional view showing an essential portion of a cross joint according to an embodiment of the invention. [0018] FIG. 2 is a graph diagram showing a result of measuring a hardness at each depth from a surface of a race portion. [0019] FIG. 3 is a graph diagram showing a result of measuring a residual compressive stress at each depth from the surface of the race portion. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Continue reading... Full patent description for Cross joint Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Cross joint 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. Start now! - Receive info on patent apps like Cross joint or other areas of interest. ### Previous Patent Application: Polishing pad and polishing apparatus Next Patent Application: Chemical mechanical polishing devices, pad conditioner assembly and polishing pad conditioning method thereof Industry Class: Abrading ### FreshPatents.com Support Thank you for viewing the Cross joint patent info. IP-related news and info Results in 0.40716 seconds Other interesting Feshpatents.com categories: Computers: Graphics , I/O , Processors , Dyn. 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