Flexibility In An Accurate Form: New Coupling Series For Servo Drives

2023 Author : Hannah Pearcy | [email protected] . Last modified: 2023-05-24 11:12

Servo drives can be found in many industrial applications: automation systems, packaging and machine tools, industrial robots or in the automotive industry. Shaft couplings for these demanding applications must be reduced according to inertia, offer universal displacement compensation and work with high precision. For these special tasks, R + W has developed the new clutch series SCL, a backlash-free multi-plate clutch with light aluminum clamping hubs, which is designed for torques from 25 Nm to 100 Nm.

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The servo multi-plate clutch is suitable for dynamic drive tasks with frequent starting and stopping as well as reversing operation, where the focus is on absolute positioning accuracy. Their hubs are made of aluminum, which results in a low weight and a low moment of inertia. The plates themselves are made of high-strength stainless steel (spring steel, as with all plate coupling series from R + W) and have a high power density.

High-strength screws are used to attach the plate pack, which transmit the torque via friction locking - absolutely free of play. This means that there is no micro movement in the connection of the slat, which leads to a high overall rigidity. The shaft-hub connection is only offered as a non-positive connection with a clamping hub, split clamping hub and conical clamping hubs.

Prevent bearing damage

Due to the double-cardanic design, the plate pack of the plate clutch compensates both angular and axial shaft misalignment, but also lateral shaft misalignment. Low restoring forces in all three types of offset prevent excessive heating of the bearings. The couplings therefore offer the great advantage of preventing bearing damage.

The design of the multi-plate clutch has two clear advantages over bellows clutches. On the one hand, it can compensate for slightly more shaft misalignment thanks to its flexible slats. On the other hand, due to its modular structure, it is suitable for storage, so that it is also available at short notice. This is a decisive advantage in the event of a malfunction.

Bellows versus servo plate clutch

The metal bellows coupling is a proven connection for applications where precision is required e.g. B. in highly dynamic servo axes of machine tools, woodworking machines, packaging machines, automation systems, printing machines, sheet metal working machines or gear cutting machines. The compact coupling transmits the torque absolutely free of play and can compensate for axial, lateral and angular shaft displacements - but only within a certain range.

Mass moment of inertia optimized

All multi-plate clutches from R + W score with their small size. Recesses in the area around the fastening screws ensure an optimized hub profile: This reduces the amount of material used, which in turn reduces weight and results in a low moment of inertia - extremely important for dynamic positioning and feed tasks. This is especially true for the SCL, whose compact size offers designers flexibility.

During assembly, the individual slats are arranged offset by 90 ° to each other, which is easily and precisely possible by optically marking each slat. As a result, the rolling direction of the steel used has no negative effect on the torsional rigidity of the coupling. The special spring steel was developed exactly for this task and therefore has a high tensile strength with elastic properties at the same time. He is thus equipped for the forces acting on him when transmitting torque.

Multi-disc clutches from R + W are delivered fully assembled. Users and designers do not have to worry about the assembly of the couplings, but can concentrate on their installation. The assembly is always carried out by experienced R + W employees, which reduces errors and saves time. The corrosion resistance of the coupling can be easily increased and achieved by anodizing. The couplings can also be colored according to customer requirements using the same procedure. This is much easier to do compared to painting work.

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The right coupling for everyone

Multi-disc clutches from the SCL series offer precise torque transmission for servo drives with smaller torques. They are offered for torques between 25 Nm and 300 Nm. R + W offers single gimbal and double gimbal versions. These couplings are built for permanent operation over the entire life of the system.

Additional information on the criteria for choosing the right coupling

For every application there is the optimal component to connect the input and output. The focus is on process reliability and perfect machine design. Couplings and cardan shafts are used in the field of mechanical power transmission. These are represented in almost every form in today's machine and plant construction and are responsible for the exact torque transmission. In addition to this main task, the different coupling types have other properties for connecting the input and output in machines and systems. B. also used to compensate for design-related shaft misalignments. Depending on the type of coupling and size, you can compensate for it to different degrees. This property must be taken into account when making the selection. Other factors for the design and dimensioning are: type of application, drive type, installation space and various physical variables (torque (see above), torsional stiffness, spring stiffness or moment of inertia). The often technically characterized sales or the design department at the coupling manufacturers can help answer and calculate these points.

Practical applications

"We have delivered various prototypes of the new servo multi-plate clutches to Austria and South Korea," reports Jörg Stang, sales manager at R + W. There they are mainly used as a replacement in laser engraving or machine tools for complex special solutions. "Any scenario in which increased flexibility is required is ideal for the SCL product series," explains Stang. Finally, the couplings offer higher offset compensation, a modular design, the possibility of using them even in aggressive media and high temperatures, and easy handling. (ud)

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