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PRODUCTS
LINEAR MOTION
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new range of precision ball splines enables high-speed operation in compact spaces
Thomson Industries has introduced a line of precision ball splines that enable robust delivery of rotary and linear motion on a single shaft. These new components give designers more flexibility to compress an assembly, extend a stroke, distribute a load, or otherwise meet modern automation demands. “Ball splines have provided an elegant, single
shaft solution for integrating rotary and linear motion on a single shaft assembly but did require some extra effort and lost some ground to pre-packaged, multi-shaft solutions. Meeting today’s industrial automation demands,
however, requires more design flexibility than pre-packaged assemblies can provide, and we are proud to be offering machine builders this new family of ball splines for high-precision applications,” said Eduard Schweinfort, product line manager EMEA & Asia at Thomson. Ball splines exploit the low-friction torque
transmission capabilities of rolling balls and augment that by adding one or more axial grooves, also known as splines, along the assembly shaft. That opens a low-friction path through which the balls move to facilitate low-friction axial displacement, while also transmitting torque.
The new line of Thomson high-precision ball
splines is ideal for high-speed operation in compact spaces such as laboratory automation or semiconductor pick-and-place assembly. They can automate functions that a human might otherwise perform, like opening the cover of a sample jar and pouring it in a test tube. And they are especially cost-effective in industrial robotic applications that require high-speed, precise integration of rotary and linear motion without the wide freedom of movement of robots. Thomson precision ball splines facilitate rotary
and linear motion on the same shaft. The precision ball splines are available
immediately in lengths up to 300mm; diameters between 6 and 30mm standard. Larger diameters of 40 and 50mm are available upon request. They can handle basic loads up to 55,064N and torsional loads up to 2,984N·m, speeds up to 10,000 rpm, and precision of ±17 microns with or without flanges. Thomson also has extensive customisation capabilities to tap holes, add step-down assembly for a radial bearing, build in coaxial holds, or provide just about any modifications a user may need to integrate the ball spline unit into their machine.
Thomson Industries
www.thomsonlinear.com
ADVERTORIALS New NSK ball screw for next-generation, high-accuracy machine tools
NSK has developed a new type of ball screw that exhibits reduced motion errors to deliver higher surface finish quality for machine tools used in mould and die machining and other surface-critical applications. By eliminating or reducing the time needed for secondary burnishing or polishing applications, the new ball screw also contributes to higher productivity, while simultaneously reducing the amount of drive torque to save energy. In recent years, builders of machine tools such as five-axis milling machines have been demanding increased accuracy to produce higher quality mould and die surfaces, where the ball screws used in these machines must further improve motion accuracy. When a ball screw reverses direction, sudden fluctuations in friction cause ‘quadrant glitch’
motion errors with two peaks, leaving streak marks on the machined surface and reducing surface quality. Numerous studies conducted on quadrant glitches show that it is possible to correct the first peak through numerical control (software-based servo controller compensation). Although it is more difficult to fully compensate for the second peak due to the combined effects of more factors (compared with the first peak), NSK can now present the machining industry with a solution to this problem. Using real digital-twin simulation and friction analysis, NSK has developed a new ball screw
with an optimised internal design. Key to this outcome was the company’s understanding of the underlying mechanism of friction fluctuations in ball screws. Among its many features, the new ball screw stabilises drive torque and reduces friction fluctuations when reversing its direction of motion, thereby improving motion accuracy and reducing quadrant glitch motion errors. The result is a near elimination of the second peak. Indeed, up to 20% less friction fluctuations also contributes to reducing the height of the first peak. Through a combination of NSK’s new ball screw and software servo controller compensation,
machine tool manufacturers can assure their customers of significant improvements in machined surface quality. Furthermore, the enhanced surface quality eliminates or reduces the need for any previously required burnishing or polishing processes, reducing lead times, while lower drive torque contributes to energy savings. All of these benefits provide machine tool builders with the opportunity to pitch unique selling points to potential customers. To maximise convenience for machine tool manufacturers, the mountings of NSK ball screws
with quadrant glitch control are fully interchangeable with those of conventional products, allowing adoption without costly equipment changes. The ball screw will be available in shaft diameters from 25 to 63mm, with leads from 5 to 30mm. Preload types will include: offset preload (Z preload), double nut preload (D preload) and spring-type double nut preload (J preload).
36 DESIGN SOLUTIONS NOVEMBER 2022 6 3 DESIGN SOLUTIONS NOVEMBER 2022 Motion error during circular interpolation machining (with servo controller compensation)
Feature
Enlarged view of machined surface (simulated image) NSK Europe Ltd. u
www.nskeurope.com
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