GB258725A - Improvements in or relating to electromagnetically actuated hammers, drills, vibrators, and other reciprocating or vibrating tools or devices - Google Patents

Abstract

258,725. Grant, P. Sept. 5, 1925. Reciprocating machines; solenoids.-A reciprocating motor comprises three coaxial coils placed end to end, the outer pair of coils being connected to one and the middle coil to the other of two electrical supplies, alternating and continuous, and the outer coils having similar magnetic polarity at their adjacent ends. A movable core is placed within the middle coil, and a further core is fixed or spring-mounted within one or each of the outer coils. In the form shown in Fig. 1, the continuous and alternating-current coils 6 and 5, 7 respectively are clamped by bolts 10 between end plates 8, 9 and are enclosed between an outer casing 11, made of mutually insulated segments, and inner tubes 3 and separators 4 which surround a central guide tube 1 preferably of nonmagnetic material. If made of metal, the tube 1 is of high-resistance material or is split longitudinally. The two sets of coil leads are brought to terminal blocks 17, 18 on a cover over a hole 15 in the casing 11. The central loose core 19 receives constant polarity from the coil 6 and the end cores 20, 25 receive alternating polarities at their inner ends which are similar at any instant, due to the alternating-current coils 5, 7. The lower core 25 is fixed and is traversed by the shank 26 of the tool which projects beyond the inner end of the core. The upper core 20 is spring-supported against a cap 22 and is adjustable by means of nuts 23 on a tail rod 21. Fig. 3 shows a form in which the coils 5, 7 are separated from the central coil 6 by annular distancepieces 32a within which move the transverse polepieces 34, 35 of the central core 19. The lower end of this core has a hardened striker 38 bearing on the tool shank, and the upper end extends into a hole in the upper core 20 which is spring-supported, as in Fig. 1. The alternating-current bobbins are made of insulating tubes 39 and end plates 40 which are preferably of laminated soft iron and form magnetic pole faces. The coils are interlaced with soft iron strips or wires 41. A trigger switch 43 controls the main switch 44. Fig. 4 shows a form comprising two coils 48 and a split coil 49, respectively supplied with alternating and continuous current similarly directed in the coils 49 and oppositely in the coils 48. Fixed cores 51, 52 project into the ends of the coils which are spaced apart and preferably separated by a magnetic filling 50. The coils 49 impart constant polarity to the core 19 while the coils 48 give tne poles 51, 52 alternating polarities. whereby the core 19 is reciprocated. The invention is applicable to the operation of hammers, drills, chipping tools, riveters, pumps, compressors, pipe drivers, spades, shaking or ramming in moulding machines, shaking tables, and other purposes.