Production of bent pipe having small curvature

Abstract

Abstract PURPOSE:To form a bent pipe without limitation on the radius of curvature by bending a long-sized straight pipe which is smaller in diameter than a desired bent pipe in the directions opposite from each other at plural required points and expanding further the pipe within a female die of which the curved part is the same in shape and size as the desired bent pipe. CONSTITUTION:The required central part of a straight pipe which is smaller in diameter than an intended bent pipe 11 and is longer by about >=2 times than said pipe is curved at a right angle at two points in the directions opposite from each other by a known method, by which a primarily formed pipe 12 is manufactured. The space between the curved parts is made about two times as much as one straight part of the pipe 11. The pipe 12 is loosely fitted in a bulging die 13 which is equal in diameter to the pipe 11 and of which the curved part has the same shape and size as the shape and size of said pipe. The pipe is bulged by said die and a secondarily formed pipe 17 is cut at cutting lines A, B and the desired bent pipe 11 is obtd. A curved surface 14 receives compressive stress and a curved surface 15 receives tensile stress, and a surface 16 deforms slipperily with no damage on the surfaces 14, 15. The bent pipe adapted to the purpose of use is thus obtd. without limitation on the radius of curvature.

Inventors

• 👤 Masanobu Nakamura
• 👤 正信 中村

Bibliographic Details