Designed for the future - state-of-the-art shot blast system for descaling of crankshafts

Rösler Oberflächentechnik GmbH
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Rösler Crankshaft Blast Cleaning Machine

For thyssenkrupp Gerlach GmbH, Rösler developed an innovative shot blast system for the cleaning of crankshafts in continuous feed mode, with cycle times of 7.5 seconds. This sophisticated blast cleaning solution shines not only with its high productivity but also its easy adaptation to future new crankshaft designs.

With numerous international locations for its forging & machining business unit, thyssenkrupp Gerlach GmbH, headquartered in Homburg, Germany, is the global leader in the field of forged crankshafts. The plant in Homburg manufactures around 6 million crankshafts per year for a wide spectrum of different engines. When increased production volumes and the expansion of the product portfolio required investing in a new shot blast machine, the customer eventually chose a custom engineered RKWS 3/4 system from Rösler. Integration of the machine into an existing building with a very tight available space required placing the dust collector into a protected external area at a distance of about 40 meters (130 ft.) from the shot blast machine.

Continuous shot blasting in three chambers

With a diameter of about three meters (10 ft.) the circular design of the machine incorporates three separate blast chambers and does not require a foundation pit. In the first chamber two crankshafts are processed simultaneously, before and after a blast cycle of 7.5 seconds, getting transferred into the next chamber. Robots handle the loading and unloading of the work pieces. After one handling system has removed one set of blast-cleaned crankshafts, a second handling system places a set of raw parts into the specially designed work piece fixture. This is designed for work piece lengths of 300 – 500 mm (12 – 20”) and weights between 6.5 and 18 kg (14 – 40 lbs.). A quick connect system with disks allows for quick adaptation to different crankshaft types.

High intensity allows for quick achievement of SA 3 surface conditions

Each blast chamber is equipped with four Gamma 400 G turbines, featuring a “Y” design with an installed power of 22 kW each. Compared to conventional blast wheels this innovative high performance turbine produces up to 20% better blast cleaning results with considerably lower energy consumption. The special “Y” design of the throwing blades allows for the use of both blade sides, before they have to be replaced. With a clever quick-change system the blades can be replaced quickly without having to dis-assemble the turbine housing. The result: Much higher uptimes and drastically reduced maintenance costs!

To achieve an optimum blast pattern, the location and positioning of the turbines was determined by a computer simulation. This, combined with a high blast media throughput of 290 kg/minute (640 lbs.) per turbine, guarantees all-around blast cleaning results of SA 3, all of which occurred within the required cycle time of 7.5 seconds. Innovative magnetic seals prevent blast media from leaking out to the shop floor.

Optimum wear protection and easy maintenance

The wear protection of the RKWS 3/4 was specifically designed for its high blast media throughput. All three blast chambers are made from wear resistant manganese steel. Furthermore, critical areas which are directly exposed to the blast stream are protected with easy-to-replace protective manganese steel plates. The automatic media cleaning and replenishment system was also designed to cope with the exceptionally high media throughput.

Special attention was paid to maintaining high system uptimes and facilitating easy maintenance of the machine operating 24/7. To achieve this, a large maintenance platform was built allowing easy access to all service points, in addition to a special dismounting device which allows for easy and quick removal of the turbines for maintenance.

RKWS 3/4
RKWS 3/4

The circular design of the crankshaft blast cleaning machine incorporates three blast chambers. The large maintenance platform allows for easy and quick access to all service points.

RKWS 3/4

Each of the three blast chambers is equipped with four Gamma G turbines with an installed power of 22 kW each. The turbine location and positioning, which is determined by a computer simulation, guarantees perfect, all-around blast cleaning of the different types of crankshafts. The special work piece fixture is designed for crankshafts with lengths of 300 to 500 mm (12 – 20”) and weights between 6.5 and 18 kg (14 – 40 lbs.).

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