Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: lubrication; rupture; journal bearings; Reynolds equation; thin films; cavitation. Includes bibliographical references (p. 72-76).

Thesis (M. Diploma (Mechanical Engineering))--Cape Technikon, 1992. / Radius hardening on journals of forged steel Diesel engine crankshafts is performed in order to increase fatigue life characteristics. This requirement may be necessary if the demands for engine power are to be increased, but where the existing crankshaft design is close to its fatigue limit, such that an increase in loading will cause it to'fail. Induction hardening of journal radii changes the make-up of the material from a coarse to a fine crystalline structure which alters the features of crack propagation. As a consequence of this higher loads can be applied onto the crankshaft without ultimately resulting in catastrophic material failure. Extending the induction hardened zone from the bearing surfaces into the radii of journals, culminates in process difficulties which are not experienced in non-radius hardened Hardening of journal radii induces crankshafts. as well as releases stresses in the crankshaft webs. This results in a deformation of the crankshaft which can be measured in the form of journal runout. Such a problem cannot be overcome by straightening the crankshafts in order to reduce runout, since this will cause Straightening hand induces the radii to crack once hardened. in the unhardened state on the other stresses which will be released again after hardening. This results in an increase in runout. High runout indicates that stresses have been induced into the crankshaft material. This is undesirable since this will make critical manufacturing processes such as grinding, governing of journal lengths, uncontrollable. It can furthermore result in creep of the crankshaft long after the manufacturing date. This results in crankshaft deformation, noticeable through an increase in runout. Since the crankshaft cannot be straightened after hardening, the consequence is that it will be unusable. The process must therefore be developed in such a manner, that all variables which can contribute towards stress induction resulting in journal 'runout, must be investigated and resolved.

This thesis reports an investigation of the generation of heat on, and the prediction of temperature of high-speed, dry-film lubricated, stainless steel bearing balls.

This thesis is a treatise on optimal assembly methods for double row ball bearings. As with common single row bearings, double row ball bearings, consist of four general components, namely, an inner ring, an outer ring, a complement of balls and a cage or retainer to keep the balls separate. Unlike single row bearings, however, double row ball bearings have two complements of balls in two distinct parallel races. Although this double row configuration is desirable in a number of applications, it makes the bearings more difficult and expensive to assemble. In addition, current manual assembly procedures require a great deal of digital manipulation, leading to concern about carpal tunnel syndrome and other long-term repetitive motion injuries. This thesis attempts to develop an improved assembly process for all types of double row bearings. Although the work is intended to be general, the Torrington 5203 double row ball bearing is adopted as a specific application example. This bearing's assembly difficulties and additional cost are a result of its manual Conrad assembly method and a rubber O-ring and groove used solely for bearing assembly. In the assembly process, the O-ring supports the upper balls temporarily until the two rings can be aligned concentrically, thus snapping the balls into the bearing races. This thesis addresses the replacement of the rubber O-ring and explores opportunities for bearing assembly automation. Design synthesis of a retractable or reusable assembly component to replace the rubber O-ring supporting the upper balls during assembly is presented. A large group of design concepts are developed and evaluated, resulting in a small group of feasible designs. These feasible solutions are then tested, and a design that has the potential immediate implementation in an improved manual assembly process is proposed. In addition, two design concepts are presented as candidates for possible implementation in an automated assembly process. / Master of Science

published_or_final_version / Industrial Engineering / Master / Master of Philosophy

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