Hot pressed magnets in open air presses
AssigneeGeneral Motors Corporation
InventorsKevin A. Young, Joseph J. Worden, Donald S. Kirk, Larry J. Eshelman
Life of this patent
Estimating the term…
Abstract
This invention describes a practice for the hot pressing and/or hot working of rare earth element-containing alloy powders using open-to-the-air presses. The rare earth-containing powder is pressed into a compact at ambient temperatures using a solid lubricant only on the die wall. This compact is then hot pressed in an open air press utilizing a heated die flooded with argon.
Claims6
A method of consolidating a rare earth element-containing powder alloy of B precursor composition into a fully densified permanent magnet body utilizing two pressing steps in at least one open-to-the-air press of the type comprising a die member defining a material-receiving die cavity with a die wall defining a predetermined cross-sectional configuration and opposing pressing members, at least one of which is adapted to move reciprocally in the die cavity to compress material placed there, said method comprising
- applying a solid lubricant film to the cavity-defining wall of a die which is at substantially ambient temperature,
- charging a predetermined quantity of a lubricant- and binder-free rare earth element-containing metal alloy powder to the lubricated cavity,
- consolidating the powder in the die by pressing member action at ambient temperature to form a green compact of generally self-sustaining strength and a density of about five grams per cubic centimeter or higher,
- flooding a die cavity of a heated die press with a dry inert gas to displace air from the cavity, the die being maintained at an elevated temperature for hot pressing the compact and the cavity being configured to receive a said green compact,
- placing a green compact in the heated, inert gas-containing die cavity while continuing the flooding of the cavity and
- pressing the green compact to a substantially fully densified body by pressing member action as the body is being heated to a hot working temperature, and
- removing the hot, fully dense body from the cavity into ambient air.
A method of consolidating a rare earth element-containing powder alloy of RE.sub.2 TM.sub.14 B precursor composition into a fully densified permanent magnet body ,/ utilizing two pressing steps in at least one open-to-the-air press of the type comprising a die member defining a material-receiving die cavity with a die wall defining a predetermined cross-sectional configuration and upper and lower opposing punches adapted to move reciprocally in the die cavity to compress material placed there, said method comprising
- applying a solid lubricant film to the cavity-defining wall of a die which is at substantially ambient temperature,
- charging a predetermined quantity of a lubricant- and binder-free rare earth element-containing metal alloy powder to the lubricated cavity onto the lower punch,
- consolidating the powder in the die by punch action at ambient temperature to form a green compact of generally self-sustaining strength and a density of about five grams per cubic centimeter or higher,
- flooding a die cavity of a heated die press with a dry inert gas to displace air from the cavity, the die being maintained at an elevated temperature for hot pressing the compact and the cavity being configured to receive a said green compact,
- placing a green compact in the heated, inert gas-containing die cavity while continuing the flooding of the cavity and
- pressing the green compact to a substantially fully densified body by punch action as the body is being heated to a hot working temperature, and
- removing the hot, fully dense body from the cavity into ambient air.
Dependencies are inferred from the claim text.