Abstract: A method of and apparatus for forming spirally-shaped indentations in tubular products. An internal shaft is formed with a spirally-shaped female die and an outside die consists of a single metal ball magnetically suspended from the outside die holder in registry with the spiral formation on the internal female die. The tube to be formed extends between the two dies and is clamped to prevent rotation but permitted to move in either axial direction. A threaded insert in the external die is advanced axially and then locked to predetermine the maximum indentation to be impressed into the tubular product. Thereafter, a reversible motor drives a holder for the external die and the internal shaft in unison to form a spiral indentation in the tubular product.

Abstract: A method of and apparatus for forming projections on tubular members or the like in which the tube forming apparatus rotates with respect to the tubular article being formed. A mandrel is provided with camming wedge members which actuate spherical forming members when the mandrel is reciprocated. Each spherical forming member projects through an aperture in a housing member which closely surrounds the mandrel. In this manner the spherical forming members engage a tubular article on the mandrel and force the contacted portion of the tubular article into a die member. The mandrel, housing member and spherical forming members are then rotated with respect to the tubular article to be formed whereby a predetermined projection is formed on the tubular article.