Hardening a cylindrical hollow object preferably made of steel
AssigneeMannesmann Aktiengesellschaft
InventorsIngo von Hagen, Wilhelm Nickel, Christoph Prasser
Life of this patent
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Abstract
A method for hardening cylindrical hollows made of steel, includes heating followed by cooling, under utilization of a water bath while the hollow rotates about its longitudinal axis, and is partially immersed in the bath, the axis being parallel to the surface of the cooling bath; this method is improved by providing a particular rotation for the hollow as long as the temperature of the hollow is above the martensitic starting temperature; and drastically increasing the speed of rotation such that a significantly higher speed obtains as the martensitic transition temperature is reached.
Claims5
In a method for hardening cylindrical hollow objects made of steel, including a cooling procedure that follows a heat treatment, under utilization of a stationary coolant bath, in a tank preferably a water bath, the hollow object rotating about its longitudinal axis while being partially immersed in the cooling bath, the axis being parallel to the surface of the cooling bath, the improvement comprising:
- providing a particular rotation for the hollow object to be at least 40 revolutions per minute as long as an outer surface temperature of the hollow object is above the martensitic starting temperature;
- and
- drastically increasing the speed of rotation to at least twice the particular rotation such that a significantly higher speed obtains as the martensitic transition temperature is reached.
Dependencies are inferred from the claim text.