Model, Punching and Shearing Machine

model, scale 1:8, eccentric type punching and shearing machine

The two machines for punching and shearing are, as is usual, combined in one framing for convenience in working and to save floor space.

The machine is of the eccentric type. It has a massive cast iron framing with a deep gap at each end to enable the plate to be punched or sheared at a distance from its edge. Overhanging both gaps is a main shaft of large diameter, the speed of which is reduced by spur gearing in the ratio 1 : 10.5 from that of the first motion shaft, which carried fast and loose pulleys and a flywheel to provide momentum. Each end of the main shaft is turned down eccentrically and on the pin thus formed is fitted a block which slides in a horizontal slot in an apron situated between adjustable V guides; a reciprocating movement is thus given to the apron. To its lower face is bolted the shear blade or punch.

For punching there is a stop motion, consisting of a cam interposed between the block and the apron, which can be turned by handle. This allows of the exact adjustment of the plate under the punch, the latter coming down to the surface without being forced through. This mechanism is not required in the case of shears. An adjustable hinged forked piece between the punch and its bolster serves to strip the plate off the punch as it rises.

The punch and shears move continuously, but their working periods alter nate, so as to lessen the fluctuation in energy absorbed. Simple radial post cranes, each with a trolley for conveniently slinging the heavier pieces, are incorporated with the framing.