Method of forming axles with internally thickened wall sections

A method for forming an elongated tube having internally thickened wall sections, comprising:

• extruding a short, tubular, metal blank into an elongated tube of substantially uniform cross-section with a substantially uniform cross-sectional thickness wall;
• forming one end of the extruded tube with an opening corresponding to the cross-sectional shape of the interior wall of the elongated tube cross-section;
• providing a tubular ring of an axial length substantially equal to the length of a pre-determined increased wall thickness location of the wall of the tube, that is, a section of the tube wall to be thickened;
• said ring being formed of an outside circumference that corresponds to, but is slightly greater than the internal shape of the tube and having an interior opening of selected shape, size and location so as to define desired tube wall thicknesses along the circumference of the ring when the ring is positioned at a desired axial location within the tube;
• inserting the ring into the tube opening and positioning the ring to overlap the section of the tube wall to be thickened while orienting the ring within the tube portion for creating desired wall section thicknesses at pre-determined circumferential locations relative to the tube wall;
• fixing the tube wall to the interior, overlapped wall portion of the tube for forming an inwardly thickened, combined ring wall and tube wall section at said pre-determined location.

A method for forming an elongated tube with at least one inwardly thickened wall section, comprising:

• preparing a tubular blank of a pre-determined length for forming the tube by extrusion;
• positioning the blank within a die having an elongated die opening for receiving the tube;
• pushing the tube with a punch, through the die opening for extruding the blank through an end portion of the die;
• said punch being formed of a cross-sectional shape that is smaller than the interior cross-sectional shape of the die to provide a space between the punch and the wall forming the opening in the die;
• stopping end-wise extrusion movement of the blank in a forward direction while continuing the pressure upon the blank in the forward direction to cause the blank to rearwardly extrude, that is, relative to the movement of the punch, into the space between the punch and the die to form an elongated tube extrusion in said space;
• removing the punch and removing the extruded tube from the die;
• and
• inserting at least one short, tubular ring within the extruded tube and fixing the ring within a location that is pre-determined for thickening a portion of the tube wall inwardly;
• said ring having an exterior peripheral surface engaged with the wall forming the interior surface of the tube for forming a combined thickened, radially inwardly extended, wall section within the tube;
• said ring being pre-formed with an interior opening of selected shape, size and location so as to define desired tube wall thicknesses along the circumference of the ring when the ring is positioned at a desired axial location within the tube.