tailieunhanh - Lecture Engineering drawing and design - Lecture 14: Mechanical elements – Bearings

Lecture 14: Mechanical elements – Bearings. The following will be discussed in this chapter: Rolling element bearings, bearing assembly, ball bearings, straight roller bearings, taper roller and needle bearings, bearing life, adjusted bearing life, bearing speeds,. | Design web Design web ME 1110 – Engineering Practice 1 Introduction What is a bearing? Engineering Drawing and Design - Lecture 14 • • • Mechanical Elements – Bearings • In general In machine design - a support or supporting element - a component that allows for relative motion between two bodies Your skeleton is the central structure that supports your body and its modules Your joints are bearings that allow different body modules to move with respect to each other Bearings allow machines or their parts to move Prof Ahmed Kovacevic • • • School of Engineering and Mathematical Sciences Room CG25, Phone: 8780, E-Mail: 1 Ahmed Kovacevic, City University London 2 Bearings can have many forms, but only two types of motions: Linear motion or rotary motion In all bearings, cleanliness and surface finish are most important There are many different types of bearings: • Sliding • Rolling • Flexing Ahmed Kovacevic, City University London • Fluid Film (hydrodynamic) Design web Design web Rolling element bearings Designed to take: - Pure radial loads Pure thrust loads Combination of the two kinds of loads Main parts: - Outer ring Inner ring Rolling elements (balls) Separator Selection of bearings: 3 Ahmed Kovacevic, City University London 4 Type and amount of load (axial - thrust, radial) Size, Speed Lubrication Life rating Ahmed Kovacevic, City University London Design web Design web Bearing assembly Ball Bearings Deep groove ball bearings: Take both radial and axial force Angular contact – axial force: 2 point; 4 point Steps in the bearing assembly: 1. 2. 3. 4. Thrust Ball bearings: Deep grove, angular contact The inner ring inserted into the outer ring Balls inserted in the remaining space Balls distributed equidistantly, rings concentric Retainer secures the balls Special, self aligning and combined Ball bearings Number and size of balls determine the bearing load - More balls -