Process and apparatus for heat treatment of workpieces by quenching with gases

US5630322A · kind A · utility

Assignee

• ALD VACUUM TECHNOLOGIES GMBH · DE

Inventors

• Paul Heilmann · Maintal, DE
• Klaus Loser · Seligenstadt, DE
• Friedrich Preisser · Heitersheim, DE

Key dates

• Filing date: Jun 6, 1995
• Grant date: May 20, 1997
• Expiry date: Jun 6, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D1/773
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Workpieces are quenched by gases in a heat-treatment system (1) and the circulated gases are recooled on cooling surfaces (12, 15) in at least one heat exchanger (11, 14), the cooling surfaces (15) of the heat exchanger (14) are cooled by a primary refrigeration unit (20) and a refrigerant to temperatures below 0.degree. C., preferably to temperatures below -20.degree. C. or even below -40.degree. C., to increase the intensity of the quenching. To reduce the size and power of the refrigeration unit (20), the quenching gas is sent in succession through at least one heat exchanger (11) cooled with water and at least one heat exchanger (14) cooled by a refrigerant. To reduce the size and power of the refrigeration unit (20) even further, this unit and a secondary refrigerant are used initially to cool down a storage volume of the primary refrigerant, such as a cooling brine, being stored under little or no pressure, to a temperature below 0.degree. C., whereupon this primary refrigerant is sent through the heat exchanger (14), at least one of which is present.