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Vibration Isolation Overview

Vibration Isolation Overview. Session 3 Examples. Choosing the right part Example.

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Vibration Isolation Overview

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  1. Vibration Isolation Overview • Session 3 • Examples

  2. Choosing the right partExample

  3. Isolate a vibrating screen which weighs a total of 69 kN, preferably with ONE isolator at each corner. The additional material load on the machine is 27 kN. The vibrating mechanism is rotating at a speed of 17 Hz with a total stroke of 19 mm. Airmount Example # ISO 1

  4. Design Parameter Sheet Step 1 – Review the Airmount Design Parameter Sheet. This will help remind you of all of the questions you should ask, and get the information you would need to get help from your Firestone representative.

  5. (69 kN + 27 kN) 24 kN 4 Airmount Example Problem Step 1 – Determine the load at each mounting point

  6. Selection Guide

  7. Airmount Example Problem Step 2 – • Determine isolation effectiveness • natural and forced frequency

  8. Natural Frequency Natural Frequency can be found in the Dynamic Characteristics table on each data sheet ƒn ≈ 2,40 Hz ƒn ≈ 2,32 Hz

  9. Natural Frequency Natural Frequency can be found in the Dynamic Characteristics table on each data sheet ƒn ≈ 1,76 Hz ƒn ≈ 1,61 Hz

  10. Isolation Effectiveness 21-2 21 113-1 113

  11. Airmount Example Problem Step 3 – • Determine design height

  12. Recommended Airmount Design Height 125 mm

  13. Style 113 Style 113-1 - Isolation = 97,25% - Isolation = 97.75% - Design Height = 125 mm - Design Height = 140 mm - List Price = €249,87 - List Price = €281,31 Style 21 Style 21-2 - Isolation = 98.5% - Isolation = 99% - Design Height = 240 mm - Design Height = 265 mm - List Price = €221,13 - List Price = €321,74 Comparing Isolators

  14. Why is Style 21 a better isolator than Style 113?

  15. Two parameters affect the natural frequency of air springs!!!!!!!!! The rate of change of the internal volume as a function of deflection, which causes a change in pressure The rate of change of the effective area of the air spring as a function of deflection which causes a change in load carrying capacity at a constant pressure Comparing Isolators

  16. By extension there are two things you can do to decrease the natural frequency of air springs (improve isolation) Reduce the rate of change of the internal volume as a function of deflection Reduce the rate of change of the effective area of the air spring as a function of deflection Increasing Isolation %

  17. Comparing Isolators

  18. To change the rate of change of effective area, just use a longer part. For instance use a 21 instead of a 113 To change the rate of change of volume (pressure), you can also use a longer part since it will have more volume, however You can also add a reservoir tank to further reduce the rate of change of the volume. Increasing Isolation %

  19. Rule Of Thumb - Maximum Reservoir size = 3 x Spring Internal Volume The Reservoir should have a flow path with Minimal Restrictions Increasing Isolation %

  20. Ideally, Airmount should be in the same plane as the center of gravity Rule of Thumb - The smallest distance between Airmounts should be twice the vertical height to the center of gravity Airmount Placement

  21. Individual captured-air springs Three point regulated system Three point leveled system Plumbing

  22. Captive Air Inflation Tank valves are used to individually inflate air springs for isolation applications. However, due to air permeation, you need to regularly inspect the pressure to insure that your system is working to it’s potential.

  23. 3 Point Regulated System

  24. Technigram No. 107 Valve part numbers on pg 25 of EMDG 3 Point Leveled System

  25. MarshMellow Isolation Problem

  26. Isolate a vibrating screen which weighs a total of 40 kN, preferably with ONE isolator at each corner. The additional material load on the machine is 22 kN. The vibrating mechanism is rotating at a speed of 20 Hz with a total stroke of 13 mm. MarshMellow Example #M1

  27. Design Parameter Sheet Step 1 – Review the MarshMellow Design Parameter Sheet. This will help remind you of all of the questions you should ask, and get the information you would need to get help from your Firestone representative.

  28. MarshMellow Example Problem Step 2 – Determine the load at each mounting point • For MarshMellows, it is necessary to determine both minimum and maximum load conditions Maximum Minimum

  29. MarshMellow Example Problem Step 2 – Determine MarshMellow load capabilities Minimum Load • MarshMellows must have at least 15% compression to be an effective isolator, therefore, there is a minimum amount of load required to be on the spring at all times Maximum Load • MarshMellows are a solid mount so there is a limitation to the energy input to the spring before it will fail from heat build up, therefore, there is a maximum amount of load for which it is rated

  30. Selection Guide – Load The 0187 MarshMellow will be at its maximum compression of 27.5% at 14,58 kN – Our maximum load is 15,5 kNwhich creates 29% compression The 0176 MarshMellow requires 10,22 kNfor 15% compression – Our minimum load is 10 kNwhich provides only 12% compression

  31. MarshMellow Example Problem Step 3 – Determine MarshMellow stroke capabilities MarshMellows are a solid mount and therefore can survive only a defined amount of movement. The amount of movement allowed is a function of: However, you don’t need to worry about this calculation since we have taken care of this in the selection charts.

  32. Selection Guide – Stroke The 0200 MarshMellow can carry the load for our application but cannot accommodate the stroke requirement

  33. MarshMellow Example Problem Step 4 – Determine Isolation Effectiveness What do we know about the relationship between natural frequency and isolation effectiveness?

  34. Natural Frequency Natural Frequency can be found in the Dynamic Characteristics table on each data sheet 2,93 Hz 3,17 Hz

  35. Isolation Effectiveness 0190 0122

  36. Vibrating Screen: Machine Weight = 2300 kg Material Weight = 700 kg 6 Mounting Points Operating at 12 Hz Throw of 10 mm Customer requested at least 90% isolation Select MarshMellow that provides Maximum Isolation Application Example # M2 – You work on this one

  37. Each MarshMellow Min Load = 3,76 kN Max Load = 4,90 kN

  38. Precision Grinder = 1150 kg 4 Mounting Points Isolate from other equipment in plant (assume 10 Hz) Select Airmount that provides Maximum Isolation Application Example # ISO 2

  39. Air Spring Marsh Mellow Steel Coil Rubber Wire rope Thin pads Isolation Mounts

  40. BEST WORST Isolation Mounts RATING:

  41. Questions? • Quiz Time

  42. The End (of this presentation)

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