Unitary rear axle housing and method for manufacturing same

A method of forming a one-piece axle housing with an integral spindle, the spindle having a spindle cross sectional profile, the method comprising:

• a) providing a tubular blank having a first end and a second end and an inner surface with a uniform first inner diameter, an outer surface with a uniform first outer diameter, D1, and a uniform first wall thickness;
• b) providing a mandrel having a first end, a second end, a main body portion between the first and second ends, and a longitudinal cross sectional profile wherein:
• the mandrel main body has a generally constant outer diameter D4;
• and
• the mandrel first end comprises at least two reduced outer diameter sections, comprising a first reduced diameter, D6, section proximal to the first end and a second reduced diameter, D7, section located between the first reduced diameter D6 section and the first end;
• wherein diameters D6 and D7 are less than diameter D4;
• and wherein diameter D6 is less than diameter D7;
• c) increasing the wall thickness of a region of said blank, said region being located proximal to the first end of said blank;
• d) positioning the mandrel within the tubular blank to form a blank and mandrel combination, wherein the first end of the mandrel is positioned near the first end of the tubular blank and wherein the region of increased wall thickness of the blank is provided over section D6 of the mandrel;
• e) passing the blank and mandrel combination through a die having a die opening, said die opening having a diameter D9, which is greater than diameter D4 of the mandrel body and less than the outer diameter D1 of the blank, to force the inner surface of said blank radially inwards to conform to said mandrel cross sectional profile while providing a reduced uniform second outer diameter on said blank, wherein, said region of increased thickness of said blank is forced into section D6 of said mandrel;
• f) separating said mandrel from said tubular blank by drawing the mandrel through the second end of the blank;
• and
• g) forming the first end of the tube blank to provide said spindle cross sectional profile.