Machine component configuration for enhanced press fit and press fit coupling method

A method of coupling together machine components comprising the steps of:

• press fitting an end of a first machine component in an assembly direction into a bore in a second, different machine component;
• wherein the press fitting step includes forming a fluid seal between the first machine component and the second machine component by way of a non-directional surface finish disposed along a portion of a length of the first machine component which is positioned within the bore;
• and
• wherein the press fitting step further includes inhibiting removal of the end of the first machine component from the bore by way of a directional surface finish disposed along a different portion of the length of the first machine component which is also positioned within the bore;
• wherein the press fitting step further includes establishing a first press fit strength between the first machine component and the second machine component in the assembly direction based on an interaction between the directional surface finish and the bore, including sliding a machined corner of the directional surface finish against a cylindrical inner wall of the bore in the assembly direction;
• wherein the press fitting step further includes establishing a second, greater press fit strength between the first machine component and the second machine component in a disassembly direction which is opposite the assembly direction based on an interaction between the directional surface finish and the bore, including contacting the directional surface finish with the cylindrical inner wall such that catching of the machined corner against the cylindrical inner wall in the disassembly direction resists decoupling of the first and second machine components.

A pin configured for coupling together machine components comprising:

• a cylindrical body defining a longitudinal axis and having a first end, a second end and an axial length extending between said first and second ends, said body further including an outer diameter;
• wherein each of the first and second ends of said body includes a first surface finish and a second, different surface finish disposed on said outer diameter, the respective surface finishes extending along different portions of the axial length of said body at each of the first and second ends;
• said first surface finish comprising a non-directional surface finish configured to form a fluid seal between said pin and a bore of a machine component having a press fit with the corresponding end of the pin;
• said second surface finish comprising a directional surface finish configured to inhibit removal of said pin from the corresponding bore, the directional surface finish including an axially asymmetric surface finish element having a first machined surface, a second machined surface separate from the first surface, and a machined corner positioned adjacent the second machined surface;
• the first end and the second end of the pin each having means, including the first machined surface, the second machined surface and the machined corner, for establishing a first press fit strength between the pin and the machine component in an assembly direction and a second press fit strength between the pin and the machine component in a disassembly direction which is greater than the first press fit strength;
• the first machined surface sloping toward the longitudinal axis in an outboard direction and defining a first line in a section plane which includes the longitudinal axis, the first line including a plurality of points on the corresponding first machined surface;
• the second machined surface sloping toward the longitudinal axis in an inboard direction and defining a second line in the section plane, the second line intersecting the first line at the machined corner and including a plurality of points on the corresponding second machined surface, and the second machined surface having a common edge with the first machined surface at the machined corner;
• and
• a slope of the second surface is steeper than a slope of the first surface, relative to the longitudinal axis, such that the second line slopes more steeply toward the longitudinal axis than the first line.