METHOD OF FIXING HEAT EXCHANGE TUBES IN TUBE PLATES Russian patent published in 2013 - IPC B21D53/08 B21D39/06 F28F9/16 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used in fixing tubes in tube plates of heat exchangers. Shaped flanges are made at tubes and having tire and grooved sections. Note here that tire outer surface is grooved to produce cavity at flange inner surface. Said flange is fitted in tube bore that has major and auxiliary annular grooves. Major groove has sidewalls shaped to tongues formed by inclined side surfaces. Distance between generating lines of inclined surfaces is set with allowance for tire axial and radial sizes after complete expansion of the billet and interference between tire side surface and tongues. Interference between tire side surface over larger base and tongues exceeds that between tire side surface over smaller base and tongues. Tube is clamped to secure the flange. After final attachment, material of tongues is subjected to different-direction shear strain.

EFFECT: higher quality of joint.

9 dwg