Loading in 5 sec....

Vibration Isolation OverviewPowerPoint Presentation

Vibration Isolation Overview

- 120 Views
- Uploaded on
- Presentation posted in: General

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

Vibration Isolation Overview

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Vibration Isolation Overview

- Session 3
- Examples

Choosing the right partExample

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 1Design 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.

Natural Frequency

Natural Frequency can be found in the Dynamic Characteristics table on each data sheet

ƒn ≈ 2,40 Hz

ƒn ≈ 2,32 Hz

Natural Frequency

Natural Frequency can be found in the Dynamic Characteristics table on each data sheet

ƒn ≈ 1,76 Hz

ƒn ≈ 1,61 Hz

Recommended Airmount Design Height 125 mm

- Isolation = 97,25% - Isolation = 97.75%

- Design Height = 125 mm- Design Height = 140 mm

- List Price = €249,87 - List Price = €281,31

Style 21Style 21-2

- Isolation = 98.5% - Isolation = 99%

- Design Height = 240 mm - Design Height = 265 mm

- List Price = €221,13 - List Price = €321,74

Comparing IsolatorsTwo 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 IsolatorsBy 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 %Comparing Isolators natural frequency of air springs (improve isolation)

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 %Rule Of Thumb - Maximum Reservoir size = 3 x Spring Internal Volume

The Reservoir should have a flow path with Minimal Restrictions

Increasing Isolation %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 PlacementIndividual captured-air springs of gravity

Three point regulated system

Three point leveled system

PlumbingCaptive Air Inflation of gravity

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.

3 Point Regulated System of gravity

MarshMellow Isolation Problem of gravity

Isolate a vibrating screen which weighs a total of 40 of gravitykN, 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 #M1Design Parameter Sheet of gravity

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.

MarshMellow of gravity 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

MarshMellow of gravity 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

Selection Guide – Load of gravity

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

MarshMellow of gravity 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.

Selection Guide – Stroke of gravity

The 0200 MarshMellow can carry the load for our application but cannot accommodate the stroke requirement

MarshMellow Example Problem of gravity

Step 4 –

Determine Isolation Effectiveness

What do we know about the relationship between natural frequency and isolation effectiveness?

Natural Frequency of gravity

Natural Frequency can be found in the Dynamic Characteristics table on each data sheet

2,93 Hz

3,17 Hz

Vibrating Screen: of gravity

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 onePrecision Grinder = 1150 kg of gravity

4 Mounting Points

Isolate from other equipment in plant (assume 10 Hz)

Select Airmount that provides Maximum Isolation

Application Example # ISO 2Questions? of gravity

- Quiz Time

The of gravityEnd

(of this presentation)