When tasked by a welding gun manufacturer with providing a lower cost alternative to the planetary roller screws currently used for the actuation mechanism, yet without reducing performance or increasing energy consumption, NSK supplied its silent running ballscrews.
The company, however, had to take into account the fact that in welding guns an extremely high load is applied in a very short time and always in the same point of the stroke – so ensuring reliable operation requires the maximum number of load carrying balls at equal load distribution.
To meet the requirements, the company proposed a SFD3605-12 unit that conformed to the same dimensions as the existing design, plus reductions in operating friction and temperature, as a result of changing from rollers to balls. Moreover, these benefits have been achieved with a ballscrew that shows a 40% cost saving.
The components feature a ball recirculation technique which employs a deflector at each end of the ballnut to ensure that the load carrying balls are picked up tangentially, thus eliminating the direct ball-to-ball contact that causes noise and vibration. In addition, the improved design also provides smoother and more stable running at low speeds.
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