The electric hammer

Abstract

The power hammer has been in use for a long time and there are now on the market many types of power-operated hammers which may be roughly classed according to the nature of the power as follows: Pneumatic, steam, motor and pulley; cam or crank, and electropneumatic drives. The pneumatic drive includes all riveting hammers; the steam drive includes practically all forge hammers, some drop hammers, pile drivers and steam drills; the motor and pulley drive class, includes the greater part of drop hammers; the electropnuematic drive includes only small forge hammers. The pneumatic hammer, due to its lightness, holds the field of hand-operated riveting hammers and it is hardly possible that any other means will ever surpass air for driving hand-operated riveting hammers; the steam hammer holds its own in very large forging and drop hammers and it is doubtful whether any other kind of hammer can remove it from that place. The field for very large forging or drop hammers is however rather limited; they are used only in very large plants in which all sorts of power prevail. There is an immense field, however, for medium and small forging and drop hammers which are used to produce all the small automobile and other similar parts as well as name plates, jewelry apparel, etc. It is this field which the electric hammer is supposed to cover. The present methods of driving these hammers are cumbersome, complicated, costly and very unsafe for the workman. The electric hammer has been studied and developed by the writer to a point where it seems to show superiority to the present used hammers, in simplicity, safety, running expenses, cost of installation, cost of upkeep and in many cases in the original cost. The development shown herein is of the induction motor type. Instead of the usual arrangement of concentric armature and field, the slots are punched on long strips of iron in a straight line which makes the field and armature parallel. The armature and field still face each other but every part of the aramture is not always active under the influence of the field as is the case in the ordinary motor. In other words in a straight-line motor the armature or runner is continuously entering the field of action at one end and leaving it at the opposite end. This constitutes the main difference between the straight-line and the rotary motor. The rotating fields of an induction motor are here replaced by magnetic fields moving in a straight line. The principal elements of this straight-line induction motor hammer are shown in Fig. 3. The actual hammer as finally constructed is shown in Fig. 5 (back view) and Fig. 6 (front view.)