Process for reducing the internal cross section of elastomeric tubing

• US 5,114,636 A
• Filed: 01/14/1991
• Issued: 05/19/1992
• Est. Priority Date: 07/31/1990
• Status: Expired due to Term

• Current Assignee: GE Inspection Technologies LP (General Electric Company)
• Original Assignee: Welch Allyn Incorporated
• Inventors: Evangelista, Michael L., Lia, Raymond A.
• Primary Examiner(s): Lowe, James
• Application Number:
  US07/640,493
• Time in Patent Office: 491 Days
• Field of Search: 264/281, 264/339, 264/DIG. 41, 264/DIG. 40, 264/230, 264/320, 264/571, 264/40.1, 264/235, 156/226, 156/227
• US Class Current: 264/40.1
• CPC Class Codes: F01B 19/00 Positive-displacement machines or engines of flexible-wall type
• CPC Class Codes: F15B 15/103 using inflatable bodies that contract when fluid pressure is applied, e.g. pneumatic artificial muscles or McKibben-type actuators
• CPC Class Codes: F16J 3/00 Diaphragms; Bellows; Bellows pistons connection of valves to inflatable elastic bodies B60C29/00; bellows or the like used in instruments G12B1/04; diaphragms for electromechanical transducers H04R7/00
• CPC Class Codes: Y10S 264/41 Processes of molding collapsible tubes

Abstract

A hydraulic or pneumatically actuated muscle has an elongated elastomeric tubular bladder covered by a tubular braid. The bladder has a fold or invagination along its length. The process for forming this bladder can employ a fixture in the form of a threaded rod. A tubular elastomer is wrapped into the v-shaped thread on the rod. Then the wrapped rod is subjected to heat to set a fold into the tubing. The invaginate bladder can be subjected to a second, mild heat treatment to reduce curling.

Claims

1. Process of reducing the internal cross section of an elastomeric tubing for forming an elastomeric bladder therefrom, the process comprising the steps of

wrapping said tubing into a helical thread on a generally cylindrical fixture which has said helical thread formed thereon;

subjecting said tubing to heat treatment while the tubing is wrapped on said fixture, including elevating the temperature of said tubing to a suitable predetermined elevated temperature for a sufficient time for thermally setting said elastomeric tubing, thus forming a longitudinal fold therein; and

removing said tubing from said fixture wherein the resulting tubing has said longitudinal fold therein which minimizes the internal cross-sectional area thereof.

2. Process according to claim 1 wherein said subjecting to heat treatment includes placing said fixture and tubing wrapped thereon into an oven.

3. Process according to claim 2 wherein said subjecting to said heat treatment includes directly monitoring the temperature of the fixture.

4. Process according to claim 1 wherein said predetermined elevated temperature is on the order of a characteristic heat thermal deflection temperature of the elastomeric tubing.

5. Process according to claim 1 further comprising, after said removing the tubing from the fixture,

wrapping said resulting tubing on a flat form and subjecting the tubing on said flat form to heat treatment at an elevated temperature lower than the first-mentioned temperature for a sufficient period of time to reduce curl of said tubing in its lengthwise direction.

6. Process according to claim 1 wherein said helical thread has a generally v-shaped profile.