GB769313A - Improvements in or relating to percussion machines - Google Patents

Abstract

769,313. Reciprocating motors. NICOTRON DEVELOPMENTS, Ltd. July 14, 1955 [April 14, 1954], No. 34786/53. Class 35. A percussive tool comprises a first part operatively connected to a working implement, a second part movable with respect to the first part, a core of magnetic material disposed in each part in such manner that a gap is formed between the cores, an energizing winding disposed between the cores and a spring to urge the parts in opposite directions, the arrangement being such that when the winding is energized by a peaky current the core of the first part is attracted to the core of the second part and a large impulse of short duration is imparted directly to the working implement. As shown in Fig. 1, a first part 1A, operatively connected to a working implement 1 has a stamped or laminated core 19, each piece so shaped that it curves away from the radial direction so that the thickness increases as the distance from the centre increases and the space between each piece is the same. A second part 1B is slidingly fitted to a central sleeve 4 of the part 1A and carries a core similar to that of the part 1A. An energizing winding 20 is situated in a recess formed in the cores, the ends 20A being brought outside the casing, and a spring 14 urges the parts in opposite directions. An adjustable rod 16 secured to the part 1A by a nut 17 is in contact with the working implement. In operation, the working implement is pressed against the work by means of handles attached to the part 1B and the coil energized. At a peak in the current the part 1A is moved towards the part 1B and the rod 16 strikes the working implement 1, the part 1B is also attracted towards the part 1A and the return spring 14 causes the part 1B to produce a secondary impact on the nut 10. In a modification, Figs. 3 and 4, one series of stampings 33 is secured to a central sleeve 27 and a second series 34 is secured to an outer casing 35, both series of stampings forming ions and having recesses to accommodate a coil 25 in the form of a two start helix, one part, 25A, being wound along one thread of the helix and after reversing the other part 25B wound back along the other thread. The sleeve 27 is urged outwardly by a spring 45 at the end carrying the working implement, the other end floating within a casing 46. Any rotational movement of the sleeve is prevented by a pin 41 co-operating with a groove in a supporting ring 43. A diagram of a circuit to produce a peaky current is also given, Fig. 5 (not shown).