Page 16 - february

METALWORKING EQUIPMENT AND TOOLS

CHOICE OF CUTTING PLATES MATERIAL FOR TURNING OF
RESTORABLE JOURNALS OF LARGE CRANKSHAFT

The restoration of the journals of large-sized crankshafts using the PRS technology,
which consists in local welding of a hardened repair sleeve (RS) to the pre-processed journal
of the shaft, was carried out on a Skoda lathe. Before welding RS, the journey was processed
to the calculated size, and after welding it must be processed with an accuracy of 6 - 7 grades
and a roughness Ra = 0.2 ... 0.4 microns. There was a plan to combine all the technological
transitions associated with the implementation of the PRS technology on one lathe. This task
was solved step by step.
At the first stage, it was necessary to resolve issues related to blade processing welded
with RS. This article is devoted to these questions. The welded RS has a difficult-to-machine
surface. Its hardness is 46 ... 50 HRC for steel 30HGSA, and for steel 60S2A 52 ... 56 HRC,
in addition, uneven hardness is concentrated in the zones of the butt weld, electric rivets and
heat-affected zones, the outer surface of the neck being repaired has holes in the middle
zone, which resulted in periodic shock loading on the tool. The listed technological factors
significantly complicated the solution of the task.

Table.
Optimum cutting plates for turning of restorable
crankshaft journals using hardened repair sleeves.

repair sleeve material type of turning

rough turning finishing turning fine turning

30KhGSA GC4235 GC4225 GC1525
(46 – 50 HRC) coated carbide coated carbide coated cermet

60S2A GC3215 GC3210 GC3210
(52 – 56 HRC) coated carbide coated carbide coated carbide

16 Stanochniy park