42 



ARMATURE CONSTRUCTION 



FIG. 30 



hole is required, then the operation of punching it out may be 

 combined with the process of clamping the disc, in which case the 



hand-wheel above the 

 centre of the disc is 

 replaced by a lever, 

 operating both punch 

 and clamp. But in 

 such a case as the 

 plate of Fig. 28, where 

 two additional slots 

 are required, the 

 middle hole and these 

 two slots are most con- 

 veniently slotted out 

 beforehand on an 

 eccentric press. To 

 produce from the plate 

 of Fig. 28 the annular 

 disc of Fig. 29, first the 

 outer and afterwards 

 the inner circumfer- 

 ence must be cut, thus 

 necessitating two set- 

 tings of the carriage, C, 

 on the tool-bed. 



It is impracticable, 

 by means of circular 

 shears, to cut circles 

 of less than 100 mm. 

 diameter ; and hence 

 for a disc, such as that 

 shown in Fig. 30, the 

 central hole and key- 

 way should be stamped 

 out beforehand. From 

 discs such as those of 

 Figs. 29 and 30, the 

 next operation is to 

 punch out slots on the 



periphery, thus obtaining the finished armature core plates shown in 

 Figs. 31 and 32. When, as in the process we are now describing, the 

 slots are punched out one at a time (or, in some cases, two or more 



FIG. 32. 



Diagrams showing process of stamping Armature 

 Core Plate. 



