Precision drive system for independently driven coaxial shafts, particularly to make coiled electric lamp filaments

Abstract

To reduce the moment of inertia and eliminate variations in speed of two xial, driven shafts, in which an outer shaft (8) surrounds a central spindle (2), which is particularly important for coiling filament material used in electric lamps, the motors are formed as essentially identical permanent-magnet rotor motors, in which permanent magnets are securely affixed to the central spindle and the surrounding shaft (8), respectively, the stators of which are retained in a common housing (6). The outer shaft carries a supply reel (3) for the filament to be coiled, whereas the inner shaft carries a winding head (7) and a reciprocating deflection roller arrangement for winding the filaments. A typical speed of operation is 1.5 seconds to wind a filament and 0.2 second pause between sequential filaments. Such filaments can be used, for example, in a general-service 60 W lamp. Preferably, the shafts are so arranged that the radial dimension of the inner diameters of the permanent-magnet rotors on the spindle (2) as well as on the surrounding hollow shaft (8) which carries the filament supply reel (3) are the same, thus at least approximately equalizing an already low rotary moment of inertia of the two shafts and motors.

Dependencies are inferred from the claim text.