Piston, method of construction, and piston body portions thereof

A method of constructing a piston, comprising:

• providing an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end having a tapered peak;
• providing a lower crown portion having at least one annular lower rib extending to a free end having a tapered peak and a pair of pin bosses configured for receipt of a small end of a connecting rod therebetween;
• moving the upper crown portion and the lower crown portion toward one another and initiating peak-to-peak contact between the upper crown portion and the lower crown portion at their respective tapered peaks;
• and
• forcing the upper crown and the lower crown further toward one another after making the initial peak-to-peak contact at their respective tapered peaks and while relatively rotating the upper and lower crowns to generate heat through mechanical friction sufficient to plastically displace and fuse the contacting surfaces in the form of a friction weld joint between the free ends of the at least one upper rib and the at least one lower rib free end.