Application - Press crown
Environment - Indoor manufacturing industry
Size - Ø 228 to 235 mm (8.98 to 9.25 in.) Bushings, Ø 215.95 mm (8.50 in.) x8 Bearing seats, Length 130 to 190 mm (5.12 to 7.48 in.)
Method - Boring
Product - MPB60tbA
Customer - DB Santasalo
A major Scandinavian industrial manufacturer required a complete renovation of one of its press crowns. The manufacturer scheduled a four-week shutdown for annual maintenance, during which DB Santasalo was contracted to perform the renovation. The task involved boring new bearing seats for two crankshafts, including two center bearing seats and two off-center bearing seats per crankshaft. Given the scale of the project, the scheduled shut down and the fact that the press crown endures millions of cycles under continuous 24/7 operation, the renovation required swift machining with extremely high precision.
Solution
The application and the installation of the boring bar were meticulously measured using a
portable measurement arm with probe to ensure the exact positioning of the bores. This
process was repeated before, during, and after the boring to maintain accuracy.
To achieve a stable setup, U-shaped spacers were welded directly to the press crown.
Five bearing supports, utilizing both single and double mounting plates, ensured a sturdy
installation of the MPB60tbA machine. The boring process was executed smoothly and
rapidly, with high precision. The bore to fith bushings ranged between Ø 228 to 235 mm
(8.98 to 9.25 in.) with a length between 130 to 190 mm (5.12 to 7.48 in.). The final bore for the
bearing seats were Ø 215.95 mm (8.50 in.) for all eight seats.
Aligning and measuring, however, proved to be the most time-consuming aspects of the
renovation due to the numerous bearing seats that needed realignment and reboring. After
boring and realigning the bearing seats, metal bushings were installed.
The final stage of the renovation involved planing the bushings to ensure they were flush
with the surrounding surface. A phasing tool was attached to the boring bar to achieve a
perfectly flush surface.
While one crankshaft’s bearing seats were being bored and renovated, the other crankshaft’s
head was adjusted and machined to specification, and vice versa. The entire process of
measuring, setup, boring, phasing, and teardown of both crankshafts was completed within
10 full working days.
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