Method of assembling a pump having a noncircular joint

A method of assembling a cover to a housing of a pump, the method comprising:

• disposing a noncircular plate within a cavity at least partially defined by a noncircular lip;
• rotating a roll-forming tool about a longitudinal axis, the roll-forming tool including a central shaft having the longitudinal axis, a first axle having a first lateral axis that extends substantially perpendicular to the longitudinal axis, a second axle having a second lateral axis that extends substantially perpendicular to the longitudinal axis, a first roller rotatably coupled to the first axle and adapted to rotate about the first lateral axis, and a second roller rotatably coupled to the second axle and adapted to rotate about the second lateral axis, the first roller and the second roller being radially positioned with respect to the longitudinal axis and circumferentially spaced with respect to each other;
• while rotating the roll-forming tool, engaging the first and second rollers with the noncircular lip,
• applying a load to the noncircular lip, the load being applied parallel to the longitudinal axis;
• and
• continuing rotating the roll-forming tool about the longitudinal axis, the longitudinal axis remaining in a fixed position, wherein rotating the roll-forming tool causes the first and second rollers to concurrently operably engage the noncircular lip, deform the noncircular lip, and assemble the cover to the housing.