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Rolling Diaphragms

rolling diaphragm ierRolling Diaphragms are special diaphragms shaped like top hats which provide the properties both of bellows and diaphragms. 

BF Diaphragms have deep folding parts, which enable a smooth rolling action. 
A long stroke is possible, and the effective pressure receiving area will be maintained the same throughout the operation. 
In addition, these diaphragms can respond to minute pressure variations, greatly contributing to improving the performance of equipment in the air pressure and liquid pressure control fields. 

The composition of the BF Diaphragms can be set as rubber only or as a composite with a fabric. In either case, the diaphragms have the characteristics of being extremely thin with good flexibility. 
Available BF Diaphragm types are the M3 (bead) type and the M4 (flat) type, depending on the flange structure. 
BF Diaphragms are available in a wide variety of sizes depending on the cylinder diameter and stroke amount. 
In addition, we will select the optimum rubber material in response to the fluid in contact and environmental conditions. 

Features of Fujikura Rubber’s BF Diaphragms 

  1. Enables use without lubrication.
  2. Rolling action of the diaphragms allows no friction loss in addition to extremely small hysteresis loss. 
  3. There is no leakage. (To be exact, however, there will be a minute permeation through the rubber membrane.)
  4. The effective pressure receiving area will constantly stay the same throughout the full stroke. 
  5. Because the folding parts are narrow, they can be designed for extremely low pressure (250Pa) applications to high pressure (9.81MPa) applications.
  6. A long stroke can be realized for the diameter.
  7. Because the membrane rigidity is low, it will not be necessary to consider the BF Diaphragm in the spring calculation.
  8. Because the BF Diaphragm will move with a rolling action, it will not be necessary to pay special attention to the surface finish, materials, and hardness of the piston and the cylinder. 
  9. Even if there is a small amount of eccentricity or deviation between the piston and the cylinder, no major obstruction will be caused in the equipment action.
  10. Rubbers with resistance can be selected for any kind of contact liquids.
  11. There will be little damage due to vibration fatigue.
  12. The product will have a long lifetime due to the rolling action.
  13. There is an automatic centripetal action. (If the piston is pushed in one particular direction, the pressure will cause a restoring force that will act to return the piston to the center line.)
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