Method of finishing a displacement chamber in a rotary fluid device

Claim 1

A method of finishing the inner surfaces of a displacement chamber open at one end of a rotary gear pump or similar rotary fluid displacement device for mounting a pair of interengaging rotors having equal diameters therein, in which said inner surfaces include a pair of semicylindrical laterally displaced upright surface portions having each a diameter substantially equal to that of said rotors and a substantially oval-shaped bottom wall surface normal to said upright surface portions, said method comprising the steps of advancing through said open end of said chamber a rotating finishing tool with its axis of rotation aligned with the axis of one of said semicylindrical surface portions and having at least one bit having a cutting edge parallel to said axis of rotation and spaced therefrom a distance equal to the radius of said semicylindrical surface portion and at its lower end at least one cutting point aligned with said cutting edge to thus finish said one semicylindrical surface portion; moving, after said cutting point has reached said bottom wall surface, said chamber and said rotating finishing tool transversely relative to each other so that the axis or rotation moves along a plane including the axes of said upright semicylindrical surface portions until the axis of said rotating tool is aligned with the axis of the other of said pair of semicylindrical surface portions to thereby finish part of said bottom wall surface with said cutting point of said one bit; simultaneously subjecting said bottom wall surface to the finishing action of another cutting point provided on said finishing tool in a common plane normal to said axis of rotation with said cutting point of said one bit and arranged spaced from said axis of rotation such a distance that said other cutting point finishes during said transverse movement that part of said bottom wall surface which is not finished by said cutting point of said one bit; and retracting said rotating finishing tool along the axis of said other of said semicylindrical surface portions so as to finish said other semicylindrical surface portion.

Claim 2

A method of finishing the inner surfaces of a displacement chamber open at one end of a rotary gear pump or similar rotary fluid displacement device for mounting a pair of interengaging rotors having equal diameters therein, in which said inner surfaces include a pair of semicylindrical laterally displaced upright surface portions having each a diameter substantially equal to that of said rotors and a substantially oval-shaped bottom wall surface normal to said upright surface portions, said method comprising the steps of advancing through said open end of said chamber a rotating finishing tool with its axis of rotation aligned with the axis of one of said semicylindrical surface portions and having at least one bit having a cutting edge parallel to said axis of rotation and spaced therefrom a distance equal to the radius of said semicylindrical surface portion and at its lower end at least one cutting point aligned with said cutting edge to thus finish said one semicylindrical surface portion; moving, after said cutting point has reached said bottom wall surface, said chamber and said rotating finishing tool transversely relative to each other so that the axis or rotation moves along a plane including the axes of said upright semicylindrical surface portions until the axis of said rotating tool is aligned with the axis of the other of said pair of semicylindrical surface portions to thereby finish part of said bottom wall surface with said cutting point of said one bit; simultaneously subjecting said bottom wall surface to the finishing action of another cutting point provided on said finishing tool in a common plane normal to said axis of rotation with said cutting point of said one bit and arranged spaced from said axis of rotation such a distance that said other cutting point finishes during said transverse movement that part of said bottom wall surface which is not finished by said cutting point of said one bit; and retracting said rotating finishing tool along the axis of said other of said semicylindrical surface portions so as to finish said other semicylindrical surface portion.