Space-optimized bearing locknuts
The requirements placed on machine and tool construction continue to grow. Power-driven tools and work spindles, for instance, are expected to handle higher and higher speeds. Simple shaft nuts (for instance in accordance with DIN 981) or systems with radial locks quickly reach their limits at high speeds. Vibrations occur due to asymmetry, resulting in a loss of bearing preload or even a system failure if the nuts come loose due to a combination of vibration and high levels of centrifugal force.
Spieth is the right solution partner for these applications. Thanks to the unique Spieth principle, locknuts from the technology leader ensure optimal alignment of the locknut on the thread, offer the highest breakaway torque on the market, and ensure outstanding axial run-out and reliable bearing retention even at high speeds. With decades of application experience, Spieth can design solutions tailored to meet customer requirements that can be installed even in the smallest spaces – such as in power-driven tools, work spindles, rotary tables or oil-free rotary screw compressors.
Maintain precision and smooth performance to keep things running – even with limited space
Modern machining centers work with high speeds and high cutting parameters for maximum volume removal rates and the best possible productivity. In particular in high speed cutting (HSC), components can be exposed to high loads due to high levels of dynamism during accelerating and braking. High-quality work spindles need to ensure the best possible precision, smooth running properties, long service life and easy maintenance. In addition, spindles need to be designed to be more and more compact and save space. Locating and locking the bearing is an elementary demand on the overall spindle bearing system. DIN and standard components are often insufficient when developing and producing modern high-performance spindles, to fulfill increasing requirements.
For bearing applications where space Is limited, Spieth has collaborated with a major spindle manufacturer to develop a special locknut exactly tailored to the customer’s specific requirement.
The challenge was to place a locknut in the very limited space that could offer the best possible locking values (breakaway torque) even at high speeds. The customer had already had bad experiences with shaft nuts coming loose in the past, resulting in a loss of precision, higher wear, and ultimately spindle failure. Their first emergency solution was to secure the nuts using glue, although this resulted in a significant amount of additional installation effort and caused problems during maintenance. The customer wanted to eliminate any gluing in their new planned design.
The “Spieth design” is especially well suited for high speeds: the one-piece locknut consists of a load and locking section which are connected to one another by a membrane. When the axial locking screw is tightened, the thread flanks of the locknut and shaft thread align perfectly to eliminate any play on the thread flanks. At the same time, the locknut is centered on the thread and achieves an extremely high level of concentricity with outstanding locking values. Thanks to this principle, Spieth locknuts can be used to precisely adjust the required preload force, keeping operations constant and reliable even with high levels of dynamism.
Installation and removal of Spieth locknuts is fast, precise and simple. This results in shorter assembly times, optimized service processes, better user-friendliness and ease of maintenance.
At the same time, Spieth engineers were able to modify the geometry of the locknuts so that the customer can eliminate peripheral equipment such as spacers they used in the past – the space-optimized locknuts take over their function. This saves installation space and reduces the diversity and number of components, in turn improving the precision of the spindle and lowering costs.