METHOD FOR SECURING TUBES TO TUBE LATTICED PLATES Russian patent published in 2000 - IPC

FIELD: plastic metal working, namely processes for securing tubes to tube plates of heat exchanging apparatuses. SUBSTANCE: method comprises steps of making on outer end portions of tubes annular protrusions with trapezoidal cross section; placing tube in tube opening having annular grooves with rectangular cross section; matching annular protrusions of tubes with annular grooves of tube opening; fixing tube against its possible motion for subsequently securing it to tube plate by applying compression effort to inner surface of tube. Trapezoidal protrusion has large base equal to width of annular groove. Tube is fixed at local expansion of it by inner pressure applied in position of inner annular protrusion for filling with its material volume of annular groove. Tube is simultaneously secured to two tube plates due to placing at both ends of tube cone punches with calibrating portions and moving punches one towards another. EFFECT: enhanced quality of tube joints, namely improved tightness characteristics of joints. 7 dwg