Abstract: The invention concerns a device for the transport of metallic work pieces, in particular, during the heat treatment process. In order to suggest a device that makes cost savings and increased transport capacity possible, an invention is suggested with a device for the transport of metallic work pieces comprising a heat-insulated and vacuum-proof transport chamber for heated transports, a transport device for cold transports and a common drive for the transport chamber and the transport device.

Abstract: In order to refine a method for electric heating of furnaces for heat treating metallic workpieces, especially vacuum furnaces usable for plasma carburizing or nitriding, in which the heater elements of a furnace are supplied with a heating voltage that is generated in the secondary circuit of a three phase transformer connected to the three phase power network such that a comparatively small reactive power component can be obtained in a simple and economical manner, it is proposed that the primary coil windings of the three phase transformer be switched in the delta connection during a first heating phase and in the star connection during a second heating phase, whereby the switchover time from the delta connection to the star connection is determined as a function of operating parameters characteristic for the heating process.

Abstract: In order to refine a method for electric heating of furnaces for heat treating metallic workpieces, especially vacuum furnaces usable for plasma carburizing or nitriding, in which the heater elements (8a, 8b, 8c) of a furnace are supplied with a heating voltage that is generated in the secondary circuit of a three phase transformer (6) connected to the three phase power network such that a comparatively small reactive power component can be obtained in a simple and economical manner, it is proposed that the primary coil windings of the three phase transformer (6) be switched in the delta connection during a first heating phase and in the star connection during a second heating phase, whereby the switchover time from the delta connection to the star connection is determined as a function of operating parameters characteristic for the heating process.

Abstract: A method for heat-treating metallic workpieces, in which a flow of cooling gas is generated in a vacuum furnace by a fan in order to quench the workpieces, with the fan being driven by a rotary current motor that is operated with a predetermined supply voltage above a minimum pressure in the vacuum furnace which is determined with regard to the motor power of the rotary current motor. In order to additionally develop this method such that a simple and inexpensive improvement of the quenching effect is achieved, the fan is started at a pressure in the vacuum furnace which is lower than the minimum pressure, with the rotary current motor being operated with a second, lower supply voltage until the minimum pressure in the vacuum furnace is reached.