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Heyligenstaedt is a German company founded in 1867 and is one of the most renowned tool manufacturers worldwide, particularly in the areas of rotating and milling. It has 200 employees and particularly distinguishes itself through contact with its customers, offering an entire range of specific products at excellent prices. Heyligenstaedt has commissioned another processing machine of the Heynumill type for formatting large-size mechanical components for a German automobile manufacturer. These parts had to be manufactured with great precision in the shortest possible cycle time.
In order to guarantee rigidity, precision and a high level of dynamism, the Heyligenstaedt company has decided to use the DualDrive by Redex-Andantex: "We had to boost performance", explains Ulrich Krause, sales manager of Heyligenstaedt . "Now we are able to achieve tolerances in magnitudes of just hundredths with perfect dynamism".
The line installed for a German automobile manufacturer is part of the vertical milling machine line with the Heynumill portal construction. The machines of this line have work tables up to 4m wide, of any design (palette tables, double tables, integrated round tables). Their drive capacity can reach up to 100kW and the maximum spindle speed is of 6000rpm. The entire Heynumill product range is equipped with DualDrive gears. Heynumill has two DualDrive systems for the drives of the X and Y axis. Another Redex product is used to actuate the main spindles - a two-step gearbox of the RAMmsd type offering high power density. The drive capacity can reach up to 100kW and the maximum spindle speed is 6000rpm.
"We really had to appreciate the quality of the technical consultation of Redex Andantex. The company met our expectations. From the financial point of view, this offer is certainly competitive", adds Ulrich Krause.
The concept of the DualDrive rack drive system is appealing due to two major characteristics.
First DualDrive is extremely stiff due to the optimised form of its reinforced drive bearings and its shaft drive pinions. As a result the gears offer high torsion rigidity levels and provide high rigidity in all other relevant axis directions allowing for double the accelerations and loads achievable with other solutions. The design of DualDrive makes it possible to achieve a considerable decrease in radial flexion, which is responsible for 60% of the entire deformation. This is achieved by optimising the diameter of the drive pinion so that the transferred torque has the best ratio to rigidity on the toothed rack. The bearing force primarily consists of two pre-tensioned and well-distanced taper roller bearings. It is built in such a way that the pinions can be carried as close as possible to the active load and is only separated by the width of the tensioning unit from the drive bearing. As a whole, the gear is unusually stiff, which allows higher resonance frequencies with machine axes with high dynamic requirements.
The second major property of the DualDrive drive gear is the elimination of play between both driving pinions by creating an electrical or mechanical pretension; achieving the highest possible precision. The pinion steering rack consists of 2 servo-planetary gears with parallel installation and twisted together either electrically or mechanically. In the case of Heyligenstaedt, electrical preload was selected. This solution offers the advantage of variable wiring. Electrical wiring offers means to control each gear with a separate servomotor and simultaneously creating an opposing force between the two drive pinions to eliminate the play and a resulting force which guarantees actuation of the system. It is also possible to create a mechanical pretension with which the pinions are twisted together. In this case, a single motor is sufficient to control both gears. An angular gear is integrated into each step-down gear and the patented pretension is mechanically set with a torsionally stiff coupling.
"The next Heynumill line, consisting of 6 machines, is in the works for an automobile manufacturer. The translation motions occur in the X-Y-Z direction, the milling capacity will be 67kW and the speed 6000rpm. "We would like to use the DualDrive system by Redex-Andantex also for other machine lines", concludes Ulrich Krause.
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