Working with Baumüller, WEIMA Maschinenbau GmbH developed a high throughput single shaft crusher with high-torque drive
The WEIMA shredders ensure that materials made of plastic, wood, paper, metal, biomass and waste are quickly reduced to the required size. The principle of this machine is best compared with that of an outsize file shredder. End users value a high throughput rate and maximum machine availability.
Recycling involves the processing and reuse of waste. The objective is to produce new products from old materials. Each person uses all kinds of different materials such as metals, oil, wood, plastics and many more in daily use. Yet the availability of these raw materials is limited. Waste plants therefore process waste to generate reusable products. This creates a cycle, which helps to reduce the impact on nature and the environment and also promotes the ecological idea.
Shredding large quantities of plastic? No problem for WEIMA!
The company WEIMA Maschinenbau GmbH, based in the German town of Ilsfeld in the State of Baden Württemberg, has specialized in plants for reducing the size and compacting raw materials. Among other things, the company produces machines for reducing the size of plastic waste. These plants are used by large waste recycling companies and plastics producers – as is the case with a current customer. After the size reduction, its plastic parts, the size of which, depending on the screen hole size, is only two to six centimeters, are sorted, melted and formed into plastic pellets. This is added in the production of high-quality injection molded parts. From these, new products such as flower boxes, plastic tables and such like can be manufactured.
The WKS 2200 crushing mill with a throughput rate of up to 4,000 kg per hour was specially optimized to the customer’s requirements. It thus has a hydraulic screen cage that can be swung upwards as well as an inspection flap on the opposite side. This simplifies maintenance. In addition, the color design was adjusted for the customer. The precise size is also particularly important. The ultimate particle size of the crushed material should be as homogeneous as possible. This is important for the next process steps. This requirement was met by very good speed consistency of the Baumüller drive. High machine availability and low energy consumption are other criteria that were also decisive for the choice of drive concept: “By using direct drive technology, we were able to reduce the energy consumption by 30 percent”, said design manager Stefan Roth.
In the WKS 2200 the WEIMA company uses a Baumüller direct drive concept. This consists of a DST2-315 high-torque motor with solid shaft and a servo drive type b maXX 5500.
How the single shaft crusher works
The machine operates according to the following principle: The waste is pushed against the rotating rotor by a hydraulic pusher. This has special blades and cuts the materials as soon as it gets between the rotor cutting blades and the fixed counter-blades. The particle size of the crushed waste is defined by a screen attached below the rotor. The holes are smaller or larger, depending on the customer’s wishes. “And the machine’s throughput rate depends on the screen hole size and other cutting configurations”, explained project manager Stefan Reuß.
Advantages achieved by doing without hydraulics for the drive motor
Eschewal of hydraulics produces many advantages: There are fewer wearing parts, since there is no need for the hoses and the transmission. In addition, an enormous amount of energy can be saved and the noise level is also reduced. “The greatest advantage is the energy efficiency of the motor. It is also very easy to control. And we have the advantage that the torque increases with reducing speed, which suits the size reduction process very well and is an enormous advantage”, continued Stefan Reuß.
A belt was used for the direct drive transmission; the belt transfers the force to the rotor and therefore drives the cutting tool. This solution allows for the compensation of vibrations and maintenance work is minimized. The DST2-315 high-torque motors are ideally suited for crushing mills due to their good true-running characteristics. They are also robust, space-saving and energy-efficient.
WEIMA rotor ensures homogeneous size reduction results
The innovative rotor with cutting gap adjustment ensures optimum cutting geometry. The result: More homogeneous size reduction results, universal usability, high throughput rates, lower energy consumption, lack of susceptibility to solid impurities and low wear.
If the discharged material contains foreign particles, this is not critical: This is because the machine’s integrated safety engineering triggers an emergency stop immediately, i.e. The shredder stops, the inspection flap can be opened and the foreign body can be removed quickly and safely. On starting up a high torque is then necessary, which is easily generated by the direct drive technology.
Compact drive technology
For the development of the new WKS 2200 shredder, WEIMA worked with Baumüller as a competent partner. Apart from space-saving, compact, water-cooled components, for WEIMA the decisive factors were the applications know-how and high torques that can be generated from the standstill condition with the Baumüller torque motors.
Baumüller has supported us since 2017. In Baumüller, we have found a partner who supplies all that we need from a single source. We looked for drives in which we can run within a large speed bandwidth. In this case, we run within a range of 0 to 160 revolutions at the rotor.
Stefan Roth, Design Manager of WEIMA Maschinenbau GmbH
Thanks to the perfect interaction of controller, frequency converter and motor, we were able to reduce the energy consumption of the plant by 30 percent. The Baumüller b maXX 5500 servo converters control the high-torque DST2-315 motor. Baumüller also undertook the drive dimensioning and initial commissioning of the shredder. Due to the rotor shaft link via the belt, the Baumüller motor must be able to absorb radial forces of up to 40,000 N. This can be ensured easily due to a special bearing and the corresponding validation on the basis of vibration measurements.
The WKS 2200 crushing mill of WEIMA Maschinenbau GmbH developed by this partnership is energy efficient, compact and has a high throughput rate. It offers many special features, for example, the inspection flap, a rocker pusher and the rotor with cutting gap adjustment. The machine has a wide speed range and therefore enables very homogeneous crushing. Working with Baumüller, a plant was created which completely does without hydraulics in the drive motor and therefore means a large reduction in machine maintenance costs and significantly increased energy efficiency.