Method of manufacturing a tube and a machine for use therein

A method of manufacturing a tube having a hollow interior for housing an axle shaft, which transmits rotational motion from a prime mover to a wheel of a vehicle, with the tube formed in a machine having a fixed base and a press structure movable toward the fixed base, a first die assembly coupled to the fixed base, a second die assembly coupled to the fixed base, a first mandrel coupled to the press structure, a second mandrel coupled to the press structure and spaced from the first mandrel, a third die assembly coupled to the fixed base, and a third mandrel coupled to the press structure and spaced from the first and second mandrels, said method comprising the steps of:

• placing a first billet into a cavity of the first die assembly;
• placing a first pre-formed billet having a bore defined in one end thereof into a cavity of the second die assembly;
• and
• moving the press structure toward the fixed base after the steps of placing the first billet into the first die assembly and placing the pre-formed billet into the second die assembly such that the first mandrel contacts the first billet in the first die assembly and the second mandrel contacts the first pre-formed billet in the second die assembly to complete the steps of;
• forming the first billet within the cavity of the first die assembly to produce a second pre-formed billet having a bore defined in one end thereof;
• extruding the first pre-formed billet within the cavity of the second die assembly to produce a first extruded tube having a hollow interior;
• removing the second pre-formed billet from the cavity of the first die assembly;
• removing the first extruded tube from the cavity of the second die assembly;
• placing the second pre-formed billet into the cavity of the second die assembly;
• placing a second billet into the cavity of the first die assembly;
• placing the first extruded tube into a cavity of the third die assembly;
• and
• moving the press structure toward the fixed base after the steps of placing the second billet into the first die assembly, placing the second pre-formed billet into the second die assembly, and placing the first extruded tube into the third die assembly such that the first mandrel contacts the second billet in the first die assembly, the second mandrel contacts the second pre-formed billet in the second die assembly, and the third mandrel contacts the first extruded tube in the third die assembly to complete the steps of;
• forming the second billet within the cavity of the first die assembly to produce a third pre-formed billet having a bore defined in one end thereof,
• extruding the second pre-formed billet within the cavity of the second die assembly to produce a second extruded tube having a hollow interior, and
• drawing the first extruded tube within the cavity of the third die assembly to produce the tube having a wall that has a thickness that is reduced relative to the first extruded tube;
• wherein the thickness of the wall of the drawn tube is of from 3 to 18 millimeters and the tube has a yield strength of at least 600 MPa.

A manufacturing system for manufacturing a tube that has a hollow interior for housing an axle shaft, which transmits rotational motion from a prime mover to a wheel of a vehicle, with said manufacturing system comprising:

• a machine comprising:
• a fixed base;
• a first die assembly coupled to said fixed base and defining a cavity therein with said first die assembly configured to hot forge a bore in an end of a billet to produce a pre-formed billet;
• a second die assembly coupled to said fixed based spaced from said first die assembly and defining a cavity therein with said second die assembly configured to hot forge the pre-formed billet into the tube;
• a press structure moveable toward and then away from said fixed base with said press structure comprising;
• a first mandrel aligned with said cavity of said first die assembly, and
• a second mandrel aligned with said cavity of said second die assembly;
• wherein said first and second mandrels move simultaneously with each other as said press structure moves towards and then away from said fixed base such that said first mandrel enters said cavity of said first die assembly and said second mandrel enters said cavity of said second die assembly as said press structure moves towards said fixed base;
• and
• wherein the length of the second mandrel is at least 600 millimeters.