German automation specialist HEKUMA was looking for a servo drive system for a swivel arm that operates two side-by-side injection molding machines with high dynamics. Maximum torque density and excellent positioning accuracy were the decisive selection criteria. The firm’s design engineers favored our Galaxie® D Drive System. Thanks to its gearbox kinematics, which are superior on principle, Galaxie® D meets all of the customer’s requirements with ease.
HEKUMA: First in high performance automation systems in the environment of injection molding machines
HEKUMA GmbH of Hallbergmoos, near Munich in Germany, is a leading manufacturer of high performance automation systems for injection molding processes. The company’s core business areas comprise powerful take-out systems, injection molding machine and mold integration and complete, turnkey solutions for the take-out, processing, assembling, labeling, testing and packaging steps. Since HEKUMA was founded in1974, more than 5000 machines have been shipped to customers in the medical, automotive, packaging machinery and consumer goods industries.
Its decisive features are dynamic teeth instead of a rigid gear ring, tangential and hydrodynamic contact by multiple teeth over the full surface with mathematically precise synchronous running and a new type of bearing with a segmented outer race ring. All of these innovations add up to a novel design principle, with the result that the Galaxie® gearbox kinematics are clearly superior to established planetary, cycloidal, eccentric and standard strain wave gearboxes in all key technical disciplines compared to the market standard.
Totally new productivity opportunities are created in this way for high performance engineering. It is now up to engineers and designers to realize genuine developmental leaps.
The ability to provide excellent and constant positioning accuracy was a decisive factor for this swivel arm of HEKUMA’s injection molding machines. The Galaxie® D complies with this performance requirement owing to its high torsional rigidity and torsional backlash of less than one arcminute. The separate thrusted tooth kinematics mean that almost all of the individual teeth now engage simultaneously during torque transmission process and hence contribute to the stiffness. Furthermore, the flanks of the individual teeth and the ring gear are designed as a logarithmic spiral. Power is thus transmitted by multiple teeth in surface contact – with a significantly higher contact area ratio.
The second positioning accuracy aspect stipulated by HEKUMA concerns the torsional backlash. In theory, we could also have designed our Galaxie® D as a backlash-free version. However, the automation specialist’s designers opted for a reduced torsional backlash of less than one arcminute. In combination with the torsional stiffness, this enables the precision requirements to be optimally met, and any locking forces which occur during positioning are absorbed.
Due to the kinematic principle, our Galaxie® D can be used permanently without servicing or maintenance in the swivel arm of the injection molding machines. The toothing – which was designed as a logarithmic spiral principle – results in mathematically precise synchronous running. What’s more, the constant pressure distribution when loaded and the hydrodynamic lubrication prevent abrasion-induced wear particles and contamination of the lubricating substances in the gearbox. The lube oil is selected and added depending on the Galaxie® D’s mounting position.
To ensure that the mechanical precision benefits could also be converted into the highest levels of control positioning accuracy, a SEM90 rotary motor feedback system from SICK STEGMANN made its debut in the Galaxie® D for the HEKUMA application. This holistic-sensing multiturn system permits high-resolution position control of the servo drive. The mechanical multiturn captures up to 4096 revolutions. The sensor manages without a battery buffer, which is traditionally costly and time-consuming to replace at the end of its life. The SEM90 is connected via HIPERFACE to a SEW Eurodrive MOVIDRIVE inverter.
Positioning accuracy, compact design, high dynamics and freedom from maintenance – HEKUMA was utterly convinced by the sum of these features. The gearbox is now all set to be incorporated into other handling axes with specific requirements in terms of installation space, power density and precision.