Rotary compressor having a combined vane-roller structure including a ferrosoferric oxide film on a surface of a coupling groove of the roller

A method for manufacturing a rotary compressor, the rotary compressor including a cylinder that defines an inner space configured to receive refrigerant, the cylinder further defining a vane slot that is connected to the inner space and extends in a radial direction of the cylinder, a roller that is disposed in the inner space of the cylinder, that has a ring shape, and that is configured to compress the refrigerant in the cylinder, the roller defining a coupling groove has a circular arc shape and is recessed from an outer circumferential surface of the roller toward a center of the roller, and a vane disposed in the vane slot and configured to move along the vane slot, the vane being configured to couple to the couple groove of the roller and to divide the inner space of the cylinder into a suction space and a compression space, the method comprising:

• providing powder for sintering;
• compacting the powder in a mold having a shape corresponding to the roller;
• sintering the compacted powder;
• performing a primary shaping process to adjust a shape of the roller detached from the mold;
• based on performing the primary shaping process, steaming the roller;
• and
• based on steaming the roller, performing a secondary shaping process to further adjust the shape of the roller,
• wherein the roller comprises a ferrosoferric oxide (Fe3O4) film disposed on a surface defining the coupling groove,
• wherein the roller is made of SMF 4040 steel comprising 0.2 to 1.0 wt % of carbon (C), 1 to 5 wt % of copper (Cu), iron (Fe), and impurities,
• wherein the vane is made of SUJ2 bearing steel or STS440 stainless steel,
• wherein the SUJ2 bearing steel comprises 0.95 to 1.10 wr/o of C, 0.15 to 0.35 wt % of silicon (Si), 0.5 or less wt % of manganese (Mn), 0.025 or less wt % of phosphorus (P), 0.025 or less wt % of sulfur (S), 1.30 to 1.60 wt % of chromium (Cr), 0.25 or less wt % of Cu, 0.25 or less wt % of nickel (Ni), 0.08 or less wt % of molybdenum (Mo), Fe, and impurities, and
• wherein the STS440 stainless steel comprises 0.6 to 0.75 wt % of C, 1.0 or less wt % of Si, 1.0 or less wt % of Mn, 0.04 or less wt % of P, 0.03 or less wt % of S, 16.0 to 18.0 wt % of Cr, Fe, and impurities.