Drive solution for the paper industry

The procedure for paper manufacturing has changed very little since 105 AD, the date when the process was first recorded. Fibres are moistened in water and then scooped out with a sieve. This paper web is later pressed and dried. Today, gigantic paper machines are used in the various processing steps to turn the pulp into paper. This is an enormous challenge for machine constructors as individual components have to be able to withstand extreme pressures. Deprag Schulz GmbH & Co, in Amberg, Germany, manufactures air vane motors made from stainless steel which have provided an optimal drive solution for numerous areas of application.

The material processing of paper machines for example: pulp and wood pulp as well as waste paper fibres are mixed in a certain proportion depending on the type of paper and then diluted in water. Chemical bulking agent and material aids are also added. This aggressive liquid must be ‘stirred’ again and again. The motor used for this job has to be extremely robust. The Deprag air vane motors made from stainless steel are suitable because they are designed for use in extreme conditions. They are water-vapour resistant, insensitive to acids and heat, and are high-performance, durable machines.

How the air motors work

Air motors can be applied in a wide spectrum of fields due to their diverse design versions, simple construction, light performance weight, high speed ranges and explosion safety. The air motor works on a simple principle. The air created by the compressor causes the motor shaft to rotate.

In the vane motor the rotor starts to turn in the eccentric cylinder. The vanes held in the rotor slits are pushed to the edge of the cylinder wall by centrifugal force. This creates working chambers for the expanding air. The expansion of compressed supply air changes into kinetic energy and rotational movement is generated.

Advantages

There are many advantages to using air motors as a drive. The main benefit is the high performance density. Depending on design, they only need a fifth of the weight of a standard electric motor or a third of the size.

The generated performance is almost constant for this motor type over wide speed ranges. It can be operated over a wide range of varying loads. The motor performance can be adapted by altering the operational pressure and the speed can be smoothly controlled by throttling the air quantity. The air motor can be loaded until standstill without problems or any kind of damage. When the load is reduced it restarts immediately and successively as many times as required even at high duty cycles.

Another of the advantages of this type of drive is that air decompression cools down the friction heat created by the air motor. Therefore, it is cool when loaded and overheating is almost impossible. Additionally, the inner excess pressure prevents the intrusion of dust and dirt.

Oil-free operation of the air motor in dry run, as required by the food industry, is also possible with low performance loss.

All Deprag stainless steel motors are fitted with planetary gears as standard in stainless steel design. A 1.2 kW motor with a speed of 4500 U/min can also be delivered with various planetary gear speeds of 1250, 550, 350, 160 or 100 U/min as standard.

Air motors are claimed to be superior to standard electric motors in their compactness and performance. A 1.2 kW strength vane motor with integrated planetary gear with nominal torque of 350 U/min is only 268 mm long and 82 mm in diameter.

Using an air motor also eliminates the possibility of a short circuit; this is a further advantage over the electric drive. Deprag Schulz offers an ATEX-certified, stainless steel motor with integrated holding brake as standard.

“Whether used for material preparation in paper manufacture, the transporting unit of a paper machine or for cutting the base paper into strips, the stainless steel air vane motor is an all-purpose piece of equipment,” says product manager Dagmar Hierl. Deprag offers a large selection of stainless steel motors for the paper industry alone. These motors are attractive because of their robustness and high performance.