David Elliott and Mick Robinson had a successful weekend at Darlington Locomotive Works. The main frames now have the bends in them, and the remaining frame plates have been set up and temporarily bolted to the main frames. The bends in the rear frames (needed to allow room for the Cartazzi wheelset to move sideways without the wheels hitting the frames) were achieved as follows:
A bending former was made up using a piece of steel plate normally used to the protect the inspectionpit boards from exceptionally heavy loads, to which was temporarily welded a hefty piece of rolled steel joist (RSJ) which forms part of the boiler cradle, a specially pressed former to provide the correct bend diameter and a spare piece of angle to brace the upright to the floor plate. This was carefully lined up with the inside of the required bend and secured to the rails by large tack welds.
The rig is set up around the frames to start the bending process – David Elliott
The former around which the bending will take place – David Elliott
The area of the frame to be bent was then heated using two large oxy-propane torches, two being required to reach the necessary dull red heat in the whole of the width of the 30mm plate being bent. Two complete bottles of oxygen were used, made possible by the loan of a second oxy-propane set from M Machine. The rear end of the frame was then formed into the correct place using the fork truck, the angle of the bend being checked with a laser profiled template CNC cut from the 3D model of the frames.
The first bend successfully completed – David Elliott
The rig re-set for the second bend – David Elliott
The completed bends – David Elliott
Mick Robinson warms up the next area to be bent – David Elliott
With the inner frames bent to shape, the Cartazzi frames could be bolted on – David Elliott
One of the frame joins and the threaded bolts securing the plates together – David Elliott