# US 2009/0260721 A1 · Method of restrained-quenching of annular member > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260721 A1 - Document ID: US20090260721A1 - Status: Published application - Kind: A1 - Application number: 12/442,030 - Filed: 2007-08-21 - Published: 2009-10-22 - Earliest claimed: 2006-09-20 - Assignees: Ntn Corporation - Inventors: Chikara Ohki - Web page: https://patentgrep.com/patent/US20090260721A1 ## CPC - C21D 9/40: for rings; for bearing races - C21D 1/18: Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62) - C21D 1/673: for die quenching - C21D 9/08: for tubular bodies or pipes - C21D 2211/008: Martensite - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) ## Abstract A method of restrained-quenching of an annular member, that can readily ensure a sufficient effect of restraint, increase treatment efficiency of a quench hardening treatment, and suppress production cost of the annular member, includes a heating step, a first cooling step, a restraint step, and a second cooling step. In the heating step, a bearing ring formed as the annular member is heated to a temperature not lower than an A1 point. In the first cooling step, the bearing ring is cooled to a first cooling temperature not higher than an MS point. In the restraint step, the bearing ring is restrained with a restraint member. In the second cooling step, the bearing ring is cooled to a second cooling temperature lower than a restraint start temperature while it remains restrained. Then, in the restraint step and the second cooling step, the bearing ring is restrained at a ridgeline portion without the bearing ring and the restraint member being in contact with each other at an outer circumferential surface and an end surface of the bearing ring. ## Claims ### Claim 1 A method of restrained-quenching of an annular member, comprising the steps of: heating an annular member made of steel to a temperature not lower than an A1 point; cooling said annular member heated to the temperature not lower than the A1 point, from the temperature not lower than the A1 point to a first cooling temperature which is a temperature not higher than an MS point; restraining said annular member cooled to said first cooling temperature with a restraint member; and cooling said annular member restrained with said restraint member to a second cooling temperature which is a temperature lower than a restraint start temperature at which restraint with said restraint member is started and not higher than the MS point, while said annular member remains restrained with said restraint member, and in said step of restraining said annular member and said step of cooling said annular member to said second cooling temperature, said annular member being restrained such that said restraint member and said annular member are in contact with each other at a ridgeline portion which is a portion where an outer circumferential surface and at least one end surface out of one end surface and the other end surface of said annular member intersect with each other, without said annular member and said restraint member being in contact with each other at said at least one end surface and at said outer circumferential surface of said annular member. ### Claim 2 (depends on 1) The method of restrained-quenching of an annular member according to claim 1, wherein said restraint start temperature is not lower than 150° C. ### Claim 3 (depends on 1) The method of restrained-quenching of an annular member according to claim 1, wherein said second cooling temperature is not higher than 100° C. ### Claim 4 (depends on 1) The method of restrained-quenching of an annular member according to claim 1, wherein a cooling rate in said step of cooling said annular member to said second cooling temperature is not higher than 6° C./second. ### Claim 5 (depends on 1) The method of restrained-quenching of an annular member according to claim 1, wherein in said step of restraining said annular member with said restraint member and said step of cooling said annular member to said second cooling temperature, said annular member is restrained with said restraint member having a restraint member taper angle not smaller than 44.5 degrees and not greater than 45.5 degrees under load not lower than load L satisfying relation of L=3.175×(C2/C1)−1.754×S (1) where L represents a load (N), S represents a cross-sectional area (mm2) of one cross-section of two separated cross-sections in a cross-section of the annular member including an axis, C1 represents circularity (μm) of the annular member before restraint, and C2 represents circularity (μm) of the annular member required after quenching. ### Claim 6 (depends on 1) The method of restrained-quenching of an annular member according to claim 1, wherein said restraint start temperature is a temperature not higher than the MS point, and in said step of restraining said annular member with said restraint member and said step of cooling said annular member to said second cooling temperature, said annular member is restrained such that said restraint member and said annular member are in contact with each other at a ridgeline portion which is a portion where the outer circumferential surface and said one end surface of said annular member intersect with each other and said annular member and said restraint member are in contact with each other at said other end surface, without said annular member and said restraint member being in contact with each other at the outer circumferential surface and said one end surface of said annular member. ### Claim 7 (depends on 6) The method of restrained-quenching of an annular member according to claim 6, wherein said annular member has such a tapered shape that a thickness in a radial direction is different in an axial direction, and in said step of restraining said annular member with said restraint member and said step of cooling said annular member to said second cooling temperature, said annular member is restrained with the end surface of said annular member on a side greater in said thickness being defined as said one end surface and the end surface on a side smaller in said thickness being defined as said other end surface. ### Claim 8 (depends on 6) The method of restrained-quenching of an annular member according to claim 6, wherein said restraint start temperature is not lower than 150° C. ### Claim 9 (depends on 6) The method of restrained-quenching of an annular member according to claim 6, wherein said second cooling temperature is not higher than 100° C. ### Claim 10 (depends on 6) The method of restrained-quenching of an annular member according to claim 6, wherein a cooling rate in said step of cooling said annular member to said second cooling temperature is not higher than 6° C./second. ### Claim 11 (depends on 1) The method of restrained-quenching of an annular member according to claim 1, wherein said restraint start temperature is a temperature not higher than the MS point, and in said step of restraining said annular member with said restraint member and said step of cooling said annular member to said second cooling temperature, said annular member is restrained such that said restraint member and said annular member are in contact with each other at two ridgeline portions which are portions where the outer circumferential surface and two end surfaces of said annular member intersect with each other, without said annular member and said restraint member being in contact with each other at said outer circumferential surface and said two end surfaces of said annular member, and such that a restraint member taper angle and a thickness in a radial direction at said two end surfaces of said annular member satisfy relation of 0.9×(b/a)≦(sin β/sin α)≦1.1×(b/a) (2) where α and β represent restraint member taper angles on a side of one end surface and a side of the other end surface out of said two end surfaces of the annular member respectively, and a and b represent thicknesses in the radial direction at said one end surface and said other end surface out of said two end surfaces of the annular member respectively. ### Claim 12 (depends on 11) The method of restrained-quenching of an annular member according to claim 11, wherein said restraint start temperature is not lower than 150° C. ### Claim 13 (depends on 11) The method of restrained-quenching of an annular member according to claim 11, wherein said second cooling temperature is not higher than 100° C. ### Claim 14 (depends on 11) The method of restrained-quenching of an annular member according to claim 11, wherein a cooling rate in said step of cooling said annular member to said second cooling temperature is not higher than 6° C./second.