Manufacturing method for thermoplastics

A method for integrally joining tubular bodies such as for manufacturing bobbins for spinning and twisting machines comprising the steps of:

• fabricating two differently shaped component bodies, each having at least one tubular mating male and female-end section, respectively, of thermoplastic material with the female end section of one to mate with the male end section of the other body in a linear coaxial body alignment at a common radial junction;
• said male section and said female section having the same outer diameters for axial assembly with a continuous cylindrical surface;
• the thickness of the tubular wall of the male section being substantially larger than that of said female section;
• the end sections having an outer shoulder running at an angle to the wall thereof from its surface toward its longitudinal axis to a distance of about one half of the thickness of the wall of the male section to form symmetrically shaped inner radial frictional edges of said shoulders abutting in assembly upon each other in alignment in intimate contact with each other;
• the female section continuing from the inner radial edge of said shoulder rearwardly into its tubular inner surface with a frusto-conical hollow surface at an acute taper angle to form with the inner surface of its linear wall a corresponding obtuse angled edge;
• the male section having a frusto-conical surface protrusion continuing from the inner radial edge of said shoulder toward its axis at an acute taper angle same as that of the frusto-conical surface of the female section to meet with the said obtuse angled edge of said male section in said radial inner edge junction and in an intimate contact alignment with the frusto-conical projection of said male section in assembly;
• the taper of the frusto-conical protrusion of said male section continuing as a pocket side from the said radial inner edge junction at an acute pocket-angle for a distance about equal to the thickness of the tubular wall of the female section, to form with the inner wall surface of the female section upon assembly a radial pocket, whereby on axial frictional rotation of one section relative to the other the surfaces of the radial edges and of the frusto-conical surfaces melt and integrally fuse said sections, with surplus thermoplastic material overflowing into said pocket.