Dynamic balancing lab report
Static and dynamic balancing ppt
Without the inserts, the blocks become four identical masses for simple balancing tests. Definitions For this experiment it is particularly important to understand and know when to use the definitions of some key terms related to the balancing of rotating masses. They then add weights supplied to a cord wound round the pulley to measure accurately the moment of each balance block. Finally set the equiment in length with L", and use the same angle in static balancing Figure 2. Set the equipment in those degrees, Figure 3. The rig has a motor attached to drive the shaft during the test for dynamic balancing. Dynamic Balance The case for dynamic balancing is very similar to that of static balancing. Figure 1. The test assembly includes a balanced steel shaft mounted horizontally on low friction bearings. An electric motor and belt turns the shaft to test for dynamic balancing. The two remaining lines can be extended until they intersect and the lengths can then be measured 4.
Before the eccentric masses were moved the system was also tested using this method. The table of bearing Figure 3.
Static and dynamic balancing conclusion
For static balance: 1. Introduction The aim of the laboratory was to find out how to produce a static and dynamic balance for a simple rotating system. Having already achieved part a through static balance, we must now consider part b. Figure 5. Static balance describes the process where primary forces caused by unbalanced mass components in a rotating object may be resolved into one plane and balanced by adding a mass in that plane only. Like Figure 1. The equation for the sum of moments acting on the shaft is therefore given by: Thus to achieve complete dynamic balance the sum of the moments in the reference plane must be equal to zero: This can once again be solved by using a closed vector diagram to find the critical arrangement of the masses on the shaft to achieve dynamic balance. We shall consider a rigid shaft supported by bearings A and B at each end as in figure 1 Appendix. The results that I collected are reasonably accurate. Seeing the behaviour of the shaft and masses before making the calculated changes is very noticeable. Definitions For this experiment it is particularly important to understand and know when to use the definitions of some key terms related to the balancing of rotating masses. A balancing machine has its bearings connected to sensors displacement or acceleration type depending on the design of the machine which detect the "heavy" point, in relation to a datum on the unit, whilst it is being rotated. Figures Figure 1. An unbalanced rotating machinery will create a lot of consequences such as shorter lifespan, energy consumption and failure of parts. Set the equipment in those degrees, Figure 3.
Excessive vibration in rotating machinery can cause unacceptable levels of noise and more importantly, substantially reduce the life of shaft bearings.
An electric motor and belt turns the shaft to test for dynamic balancing.
These moments act in a different plane to the centripetal forces acting on the shaft. Apparatus and Methods.
This will indicate that the masses are at the correct angles, relevant to their mass-radii values statically balancedas well as being the correct axial distance apart from each other.
The shaft is carrying 4 eccentric masses, and with radii of rotation, and then the sum of the forces is given by: Since remains constant it can be removed from the equation meaning that the static balance of the system is only affected by the mass-radii configuration of the system.
The rig was tested to determine the degree improvement of balance by eye and applying a force and moving the position of the rig by hand.
Impeller balancing pdf
The vector diagram will be closed if the system is statically balanced. Once again the system was tested before and after the position of the eccentric masses had been optimised. Dynamic Balancing briefing sheet, University of Warwick, department of engineering Figure 7. Analysis of Results. Therefore setting the angles and axial distances of the masses, reading off the angles on the vector diagrams and setting the compass to mark out the length of the sides on the vector diagrams all contributed towards the degree of inaccuracy in the results. Each block contains a different and removable circular insert, allowing students to create four blocks of different mass and moment. The whole balancing rig is operated manually using analogue dials and measuring equipment. Students remove the belt to check for static balance the shaft should remain static at any angular position. This laboratory will show what theory can be used to reduce unbalanced forces that cause vibration in rotating machinery.
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