Balancing-static and dynamic
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This document discusses static and dynamic balancing of rotating objects. It defines unbalance as the uneven distribution of mass about the rotating centerline, which causes vibratory forces. Static balancing ensures the center of gravity remains stationary during rotation by aligning it with the axis of rotation. Dynamic balancing accounts for inertia forces by balancing out couples and moments involved in accelerating moving parts, resulting in zero net force or moment. The objectives of balancing are minimizing vibration and ensuring balanced forces and couples. Balancing techniques counteract centrifugal forces from one mass with a second mass. Examples include balancing single or multiple masses rotating in the same or different planes.
Balancing-static and dynamic
- 1. Balancing - Static and Dynamic COMPILED BY- ANUJ JHA B.TECH (FPE) 2014027007 FMP-201 THEORY OF MACHINES (2+1)
- 2. In Focus…… • Introduction (Need for balancing) • What is Unbalance? • Important Terms • Cause of Unbalance • Balance and unbalance video explanation • Balancing- Introduction • Balancing examples • Objectives of Balancing • Types of Balancing- • Static • Dynamic
- 3. Introduction (need for balancing) When man invented the wheel, he very quickly learnt that if it wasn’t completely round and if it didn’t rotate evenly about it’s central axis, then he had a problem! The wheel would vibrate causing damage to itself and it’s support mechanism and in severe cases, is unusable. The mass had to be evenly distributed about the rotating centerline so that the resultant vibration was at a minimum.
- 4. Unbalance……definition The condition which exists in a rotor when vibratory force or motion is imparted to its bearings as a result of centrifugal forces is called unbalance or the uneven distribution of mass about a rotor’s rotating centreline.
- 5. Important Terms…. Rotating centreline: The rotating centreline being defined as the axis about which the rotor would rotate if not constrained by its bearings. (Also called the Principle Inertia Axis or PIA). Geometric centreline: The geometric centreline being the physical centreline of the rotor. When the two centrelines are coincident, then the rotor will be in a state of balance. When they are apart, the rotor will be unbalanced.
- 6. Cause of Unbalance…. In the design of rotating parts of a machine every care is taken to eliminate any out of balance or couple, but there will be always some residual unbalance left in the finished part because of 1. slight variation in the density of the material 2. inaccuracies in the casting or 3. inaccuracies in machining of the parts.
- 7. Balance and unbalance video explanation
- 8. Balancing- Introduction Balancing is the technique of correcting or eliminating unwanted inertia forces or moments in rotating or reciprocating masses and is achieved by changing the location of the mass centres.
- 10. Objectives of Balancing The objectives of balancing an engine are to ensure: 1. That the centre of gravity of the system remains stationery during a complete revolution of the crank shaft 2. That the couples involved in acceleration of the different moving parts balance each other.
- 11. Types of balancing: a) Static Balancing: i) Static balancing is a balance of forces due to action of gravity. ii) A body is said to be in static balance when its centre of gravity is in the axis of rotation. b) Dynamic balancing: i) Dynamic balance is a balance due to the action of inertia forces. ii) A body is said to be in dynamic balance when the resultant moments or couples, which involved in the acceleration of different moving parts is equal to zero. iii) The conditions of dynamic balance are met, the conditions of static balance are also met.
- 12. Balancing of Rotating Masses The process of providing a second mass in order to counteract the effect of centrifugal force of the first mass is called balancing of rotating masses.
- 13. Different cases…. Balancing of single rotating mass rotating in the same plane. Balancing of single rotating mass rotating in the different planes. Balancing of different masses rotating in same plane. Balancing of different masses rotating in different planes.