METHOD FOR PIPE FUNNELING Russian patent published in 2002 - IPC

FIELD: pipe funneling. SUBSTANCE: the method for formation of a funnel on pipe of oriented plastic having an annular groove inside the funnel for a flexible gasket at production of a seal between the funnel and the smooth end of the other pipe consists in the fact that the pipe end section is fitted on the first member of the mandrel, which has a cylindrical shape and a diameter corresponding to the pipe inside diameter. The end section is fitted on the second member of the mandrel, which is located coaxially relative to the first member of the mandrel. The lower part of the funnel is formed by the second member of the mandrel. A groove is formed with the aid of a core in the area of the expanded end section. At fitting of the pipe end section on the first member of the mandrel it is heated to temperature T₁, that is higher than glass transition temperature T_e of amorphous plastic and higher than melting point T_m of crystal plastic. A groove is made on the mandrel cylindrical member in the area of the pipe end section, the area is positioned near the hole of the pipe end section. The temperature of the rest part of the pipe end section is maintained below the glass transition temperature and the melting point of crystals. The end section is fitted on the second member of the mandrel when the area of the pipe end section is at a temperature or the melting point respectively. At formation of the groove in the area of the expanded end section the temperature of this area is maintained above the glass transition temperature or the melting point. EFFECT: prevented concentrations of stresses in plastic in the process of funnel formation and adjusted degree of probable shrinkage in the axial direction at funnel formation. 20 cl, 14 dwg