Ortlieb Präzisionssysteme recognized and followed the trend towards electric drives at an early stage. With its EML electromechanical release unit, the company is meeting the demand from customers in the machine tool and spindle construction industry for "fluid-free machines".

With a 30 percent shorter release time for the tool holder, productivity can be increased, which, in addition to the advantages of fluid-free operation, also contributes to the interest in purchasing a suitably equipped machine tool - even if this is associated with higher acquisition costs. The increase in productivity is particularly significant where parts with short cycle times per tool are machined.

The tool is clamped by springs via a force-enhancing mechanism. To release it again, a force must be applied against the spring. The EML requires a smaller installation space than pneumatic solutions. Hydraulic units require a lot of energy and also carry the risk of leaks. The use of EML, on the other hand, guarantees leakage-free operation and also opens up new possibilities in the area of chip detection and clamping force control. The electrical input and output variables can be easily measured. Further processing of the process data in line with Industry 4.0 ensures improved production, control of tool life and optimized throughput times.

Hollow shank taper clamping systems

Hollow shank tapers (HSK) as tool holders are not only suitable as a separation point within the tool system, but also as an interface for direct mounting in machine spindles and tool carriers. The spring assembly is supported on the bearing shaft and presses the threaded bush to the right. This is bolted to the drawbar and thus exerts a tensile force on it. The tension bolt is attached to the other end of the tension rod. The clamping segments grip into the hollow cone of the tool insert and are spread open by the draw bolt, pulling the hollow cone into the fit. Due to the special geometry, the force is increased and the threaded bush is pushed to the left when the tool is changed. The draw bolt also moves to the left. The clamping segments loosen and contact the draw bolt. The draw bolt then docks onto the tool insert and presses it out of the taper seat.

The role of the release unit

The release unit now has the task of moving the drawbar against the spring force during tool changes. Due to the high rotational speeds during milling, it has proven useful to arrange the release unit in a stationary position. During the milling process, it is not in contact with the rotating parts. As cooling lubricant must be supplied during machining, a rotary feed-through is required, which is usually located behind the release unit. The release unit must therefore have a bore through which a rotating pipe leads to the rotary union.

The core drive element of the EML is the planetary roller gear spindle (PWG) with its high force density and stability. Its simple design makes it possible to develop high axial forces from low motor torque with just a few components in a small installation space. With these so-called ASCA servo spindles, Ortlieb offers a technology that was originally developed by the German Aerospace Center and made ready for series production by Ortlieb. With the spindles, small pitches in the millimeter range can be achieved with a long service life. This allows new mechatronic drive solutions to be implemented that were previously not possible.

Jutta Jerabek, Marketing and PR at Ortlieb / am