Competence in customer solutions

Horizontal mills are used among other things for breaking up minerals, ores, coal or cement clinkers. They break up the raw material by hammering and grinding up to pulverization. The drives of the horizontal, 15 to 20 m long mills have to transmit considerable torques. The milling process is therefore what eats up most of the energy in production. The energy efficiency thus plays an important role in addition to the plant availability.

 

Efficient drive for hard tasks

 

Mechanical Drives presents a new central drive for tubular mills with the large gears by the name of HCPP. The double “P” in the name stands for two planetary stages. With this multi-planetary-stage concept the gear is able to transmit a power of up to 6,000 kW at the normal mill speeds. This is equivalent to a mill torque of approximately 3,700 kNm. At a maximum transmission of 100 four-pole motors which are less expensive than slow running drives can be used. The compact design contains a spur gear stage, the first planetary stage with three planetary gears and the second stage with three times two planetary gears.
Attention was paid above all to an optimized distribution of the transmission in all three stages. “The uniform distribution of load on all toothed parts makes the gear very reliable,” Detlef Essink, Engineering Head of the Heavy Duty Division at Mechanical Drives, ensures us. The flexibility in the add-on behaviour is another advantage: The drive shaft can be positioned in steps of 90°.
The use of sliding bearings is also totally new. “By using the three times two planets in the power takeoff stage and sliding bearings, the gears became more compact and feature a much smoother running behaviour,” Detlef Essink describes the advantages of these gears.

 

Finest grinding at high performance

 

Vertical mills are used especially for the breaking up of slag and raw meal in the building materials industry. They grind the raw material with a size of up to 30 mm into a very fine grain. Mechanical Drives meets the demands for high performances and maximum availability within the tightest of space with the new KMPP gears for vertical mills. These have the same planetary stage arrangement as the HCPP gears and also have a sliding bearing.
A bevel gear stage transfers the torque flow from the horizontal input shaft to a vertical intermediate shaft to drive the vertical mill. Despite the compact structure it is possible to align the bevel gear stage with a setting mechanism outside the gear. The readjustment of the support profile of the bevel gear stage in the installed state and the replacement of this drive component without removing and completely disassembling the gear are further advantages which come into effect during repairs and maintenance.

 

The perfect drive for the plastic industry

 

The demand for plastic components rises by more than 10 % every year. Extruders are used increasingly in the food and automotive industries. The demands on gears for twin-screw extruders are, in particular, a high torque that has to be transferred by two shafts with a small distance between the axles as well as the additional high axial forces which are fed into the gear by the process. The increasingly high screw speed places greater and greater demands on engineering and material, especially the roller bearings in the gear. The transmission power of a modern gear with a weight of more than 70 tons is more than 20,000 kW at a screw speed of up to 350 revolutions per minute. The axial forces produced correspond to a mass of 250 tons per drive shaft. These immense forces must be absorbed by the gear.
The challenge for the design of twin-screw extruder gears is to ensure that both drive shafts receive both the same twist angle and the same upset under load despite the different lengths and diameters of the two drive shafts and the different axial bearings. The accuracy required is in the micrometer range because the gear is designed for demanding continuous operation. Such a solution can only be used reliably in close cooperation with the customer.

 

A fertile partnership

 

One of the main reasons for Siemens’ takeover of Flender AG in 2005 was the attractive market for drive technology with its high growth rates. The decisive impulse behind the striving of the drive specialists to find system solutions and therefore to connect controllers, electrical systems and mechanics is the demand for integrated solutions. The one who is able to shine out from the masses of component providers as a system provider with technical sound concepts and total drive solutions will have a permanent edge on his competitors.
Part of this strategy is that the company has its own clutch plant. Flender produces mechanical clutches in the torque range between 15 and 10,000,000 Nm.

 

 

Two years of Flender products from Siemens

 

The connection with Siemens has led to a globally unique range of controllers with motors, clutches and gears. This enables Mechanical Drives to offer its customers homogeneous solutions and systems for the whole powertrain from one source.

 

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