Method of quenching a ring-shaped article and apparatus therefor

Patent metadata

Field	Value
Publication number	US-8974613-B2
Application number	US-73385308-A
Country	US
Kind code	B2
Filing date	Sep 24, 2008
Priority date	Sep 28, 2007
Publication date	Mar 10, 2015
Grant date	Mar 10, 2015

Abstract

A method of quenching a ring shaped article includes heating the article to a quenching temperature; primarily cooling the article down to a deformation correction initiating temperature, which is higher than a martensitic transformation point; and secondarily cooling the article down to a temperature lower than the martensitic transformation point by, while a pair of receiving rolls are held in contact with an outer peripheral surface of the article for rolling motion about an axis of rotation parallel to a center of the article, pressing a press roll, rotatable about an axis of rotation parallel to the center of the article, against the outer peripheral surface of the article from one side of the article opposite to a point intermediate between the receiving rolls.

First claim

What is claimed is:

1. A method of quenching a ring shaped article, which comprises:
heating the ring shaped article to a quenching temperature, the heating comprising heating by induction heating the ring shaped article to a predetermined preheating temperature near to the quenching temperature, stopping the heating by induction heating and transferring the ring shaped article to a continuous heating furnace, and heating by soaking the ring shaped article, which has been previously heated to the preheating temperature, to the quenching temperature within the continuous heating furnace;
primarily cooling the ring shaped article, which has been heated to the quenching temperature, down to a deformation correction initiating temperature, which is higher than a martensitic transformation point; and
secondarily cooling the ring shaped article, which has been cooled down to the deformation correction initiating temperature, down to a temperature lower than the martensitic transformation point by, while a pair of receiving rolls are held in contact with an outer peripheral surface of such ring shaped article for rolling motion about an axis of rotation, which is parallel to a center of the ring shaped article, pressing a press roll, rotatable about an axis of rotation parallel to the center of the ring shaped article, against the outer peripheral surface of the ring shaped article from one side of the ring shaped article opposite to a point intermediate between the receiving rolls,
wherein the heating by induction heating includes providing a rotary table and a heating coil, placing the ring shaped article on the rotary table, arranging the heating coil such that a position of the heating coil is adjustable in a direction radially of the rotary table so as to straddle between inner and outer peripheral surfaces of the ring shaped article, and turning the ring shaped article, placed on the rotary table, about the center of the ring shaped article, and
the heating coil is of a downwardly oriented U-shaped configuration or has a structure in which two U-shaped conductors are so arranged as to permit their leg conductors to extend parallel to each other, one of the leg conductors having their free ends connected with each other through a connecting conductor.

2. The ring shaped article quenching method as claimed in claim 1 , in which an oil bath for cooling the ring shaped article during the primary cooling and an oil bath for cooling the ring shaped article during the secondary cooling are used separately.

3. The ring shaped article quenching method as claimed in claim 1 , in which the length of time during which the press roll is urged against the outer peripheral surface of the ring shaped article is within the range of 40 to 90 seconds.

4. The ring shaped article quenching method as claimed in claim 1 , in which the temperature of the ring shaped article at the time a deformation correction is initiated with the press roll urged against the outer peripheral surface of the ring shaped article is 20° C. to 50° C. higher than the martensitic transformation point.

5. The ring shaped article quenching method as claimed in claim 1 , in which the ring shaped article is a raceway ring of a bearing assembly.

Assignees

• Kamo Kunio
• Ntn Toyo Bearing Co Ltd

Inventors

• Kamo Kunio

Classifications

• C21D7/13

  by hot working · CPC title

• C21D1/63 Primary

  for bath quenching · CPC title

• C21D9/085

  Cooling or quenching · CPC title

• Y02P10/25

  Process efficiency · CPC title

• B21B1/00

  Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section (B21B17/00 - B21B23/00 take precedence; with respect to composition of material to be rolled B21B3/00; extending closed shapes of metal bands by simultaneous rolling at two or more zones B21B5/00; metal-rolling stands as units B21B13/00; continuous casting into moulds having walls formed by moving rolls B22D11/06); Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations · CPC title