Application - Industrial gearbox (Santasalo)
Environment - Indoor machine shop
Size - Ø: Bushing 460 mm (17.32 in.), Bearing seat 440 mm (18.11 in.) H7, Length: 150 mm (6.10 in.)
Ø: Bushing 430 mm (16.93 in.), Bearing seat 420 mm (16.55 in.) H7, Length: 75 mm (2.95 in.)
Method - Boring
Product - MPB60tbA
Customer - DB Santasalo
An industrial gearbox (Santasalo) was transported to DB Santasalo in Göteborg, Sweden, for refurbishment of its main bearing seats. Throughout its operational life, the gearbox undergoes continuous cycles, causing wear on the bearings and their seats. Over time, this wear becomes significant enough that renovation is necessary to prevent total gearbox failure. The wear caused the bearing seats to become oval, requiring restoration to perfectly circular seats. This renovation demanded high-accuracy machining to meet H7 tolerances.
Solution
The solution involved refurbishing the bearing seats by line-boring both positions and installing pre-fabricated shrink-fit metal bushings as the new bearing seats. The bore diameter was 460 mm (17.32 in.) for one bushing and 430 mm (16.93 in.) for the other. When the bushings had been fitted they were bored to Ø 440 mm (18.11 in.) as well as 420 mm (16.55 in.). The final dimensions of the new bearing seats.
To mount the boring bar, a metal ring was attached to the gearbox face. This ring allowed the U-shaped mounting supports to be welded without directly welding to the gearbox, avoiding potential damage to any gearbox components. Two support bearings were used, mounted with dual-arm mounting plates welded to the metal ring.
To ensure high-accuracy machining, the MPB60tbA traversing boring bar was aligned using dial gauges, measuring at four different angles across two positions. With its high rotational speed and precise control, the boring process was completed swiftly and with maximum precision, minimizing downtime and providing a high-quality, cost-effective solution for the customer. The whole procedure of setup, machining and teradown was managed within one working day.
The gearbox was reassembled, ensuring that the customer could rely on it for many more operational cycles in the coming years.
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