RANDOLPH RESEARCH PRESS RELEASE 03/07/2005
NEW BEARING-SEAL PERMITS SAFE MOTION TRANSFER THROUGH PRESSURE VESSEL WALL
A new elastomeric bearing-seal system achieves an absolute hermetic seal and permits transferring angular motion +/-15 degrees or more through the wall of highly pressurized vessels. Developed by Randolph Research Co., Akron, Ohio, the new system with the LAMIFLEX® trademark has recently been granted US and Canadian patents.
Designers of deep submergence pressure vessels have generally not considered configurations having sealed shafts penetrating their walls, fearing seal failure under extremes of pressure. But this simple new system provides a way to do that with inherent safety and backup for applications such as control actuation or release mechanisms.
The LAMIFLEX Bearing-Seal has no sliding seal-surfaces that could fail; i.e., no packings, lip or face seals. Limited rotation (not continuous) develops a smooth frictionless spring-like torque reaction. The angular extent of rotation depends upon the height and other factors -- it is accomplished strictly through the resilience of rubber. The new design has been tested at pressures of 10,000 psi for more than a million cycles at +/-15 degrees with no leakage.
The bearing-seal development is based on the principle of high-load laminated elastomeric bearings. Originated by Randolph Research for helicopter use in place of ball or roller bearings, these elastomeric bearings have long been used to support rotor blades against tons of centrifugal thrust while their pitch angles are oscillated hundreds of times per minute without need for lubrication. Ease and smoothness of movement in that high-load situation permit some helicopters to avoid using hydraulic boost on their control sticks.
This sectional view depicts the wall of a pressure vessel penetrated by a vertical shaft. A LAMIFLEX bearing-seal surrounds the shaft. Its load faces are seated between the bottom of a cylindrical recess in the wall and a flanged part of the shaft and are sealed by static O-rings. The conical type shown has many thin cupped laminations of metal (white) that are interleaved with rubber layers (black). All layers are bonded together to form a unified stack.
The large arrows on top represent hydrostatic fluid pressure (multiple tons per square inch) pushing down on the shaft and its flange and thereby pressing the bearing-seal down against the recess in the wall. The external fluid also passes through and pressurizes the annular gaps surrounding the peripheries of the flange and the bearing-seal. Because of the unitary bonded construction of the bearing-seal an hermetic seal is achieved, i.e., there is no path for lateral fluid flow from the periphery toward the aperture.
Thicknesses of the rubber and metal layers are greatly exaggerated for clarity. Typically, the layers (one hundred or more) are only a few thousandths of an inch thick. The thinness of the rubber layers prevents their being squeezed out under the high load. Torsional angles developed between any two metal layers result from parallel movement in the rubber layers between them, adding up to large angles between the loading faces of the bearing-seals, with an opposing spring torque resulting from the rubber shear stress. Dimensions are determined by the user’s parameters.
To provide a doubled barrier, a second, tandem LAMIFLEX bearing-seal (not shown) can be built-in as an independent seal between a taller cylindrical recess and the top of the shaft flange. Even further backup can be provided by a normally unpressurized conventional O-ring placed in series below, as shown.
More, including flat and other-shaped units, can be found at randolphresearch.com or by contacting William Hinks at whinks@randolphresearch.com or 330-666-1667.