GB705294A - Improvements relating to the drying by induction heating of colours, lacquers, and the like on metal bodies - Google Patents

Abstract

705,294. Drying in electromagnetic fields. DAIMLER-BENZ AKT.-GES. June 1, 1951 [June 1, 1950], No. 13098/51. Class 34(2) [Also in Group XI] Lacquers or artificial resin layers on the metal skin of bodies for vehicles or on other hollow bodies of large surface and irregular form are dried by inducing eddy currents in said bodies by induction coils of electro magnets which are placed within or outside the bodies. The windings or electromagnets are divided into parts movable in relation to each other and all the parts are in direct conducting connection with the A.C. source. In Fig. 1, the body 10 is run on a wheeled carriage 11 into an induction coil 12 shaped to surround the body and carriage and divided to have hinged end coils 16, 17 tapering to surround closely the tapering ends of the body: The coils may be wound on thin tank containing a liquid dielectric, the tank pasteboard supports, which closely . surround the body and prevent heat loss and radiation therefrom so that the current to most turns of the coil can be switched off before the body is dry. In Fig. 3, electromagnets 20 with adjustable poles 22 to '24 shaped .to conform to the arched outer body surface are energized by a winding 21 on a laminated iron core 25. Alterriatively, substantial flat spiral induction coils are placed near the outer surface of the body, and short solenoids of a cross section conforming to a window are inserted in the window openings. In Fig. 5, the body is heated by running thereinto induction coils 30, 31 through the space for the windscreen and through that for the rear luggage boot. These coils are mounted on formers and current flows through both in the same direction so that the total induced current flows in the same direction in the metal skin. Alternatively a car body with no floor is lowered on to a vertical coil shaped to the inner body surface and is also heated by an induction coil about its outer surface. In a production line in Fig. 7, the bodies 10 are run on rails 13 to a turntable 40, whence they are introduced one into each 'compartment 39 on a roundabout structure 37. A horizontal coil 30 on the inner wall of the radial compartment thus projects into the body through its windscreen aperture. The hinged side walls 38 carrying solenoids for the window are then closed, and finally an outer wall 45 carrying a coil 31 is run in on an undercarriage to close the compartment, said coil 31 entering the body through the boot opening. On locking the walls, the current is switched on and the turntable 37 containing in the centre at 47 a suction plant and the electrical gear, is rotated at such speed, that when a complete rotation has been made, the other compartments having also been filled, the body is dry and is moved back to the turntable 40 and the production line.