Product category:
Digital Readouts and Machine Measurement
News Release from: Renishaw | Subject: Encoder
Edited by the Manufacturingtalk Editorial
Team on 16 April 2007
Encoder combines two readheads
Renishaw has introduced the DSi (Dual SiGNUM interface) encoder which combines incremental signals from two readheads and utilises patented reference mark processing.
Renishaw has introduced the DSi encoder which combines two SiGNUM SR readheads on an RESM ring and outputs a customer located, angularly repeatable propoZ index position, which is completely unaffected by bearing wander or power cycling Precision rotary axes often demand very high accuracy without calibration or error-map compensation
This article was originally published on Manufacturingtalk on 7 Mar 2001 at 8.00am (UK)
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As a modular solution, DSi allows a second readhead to be added, which eliminates odd error harmonics including eccentricity and compensates for the effect of bearing wander.
The result is total installed error of typically +/-2.5 arc second (200 mm diameter RESM).
For ultimate precision, DSi combined with the ultra-high accuracy REXM ring offers better than +/-1 arc second total installed accuracy.
DSi provides the customer located and angularly repeatable propoZ reference (index) position, which is completely unaffected by bearing wander or power cycling.
The desired propoZ index position is selected by driving the axis to the chosen angle and simply pressing a button.
This feature makes alignment of the encoder's reference position to the T-slots on a machine tool rotary table, for example, faster and more precise.
The selected angle is then stored in the DSi's memory so the patented propoZ index is locked to that angle, ensuring perfect angular repeatability...
even if the centre of rotation of the axis moves whilst the DSi is switched off.
DSi makes adding a second SR readhead very easy.
By combining the incremental signals from the two readheads and using patented reference mark processing, the DSi appears to the controller as a single very high accuracy encoder.
Furthermore, DSi maintains the dynamic advantages of SiGNUM encoders.
As a non-contact system, SiGNUM RESM rings are taper-locked to the rotor shaft, ensuring a compact axis design and the elimination of coupling losses, oscillation, shaft torsion and other hysteresis errors that plague enclosed encoders.
Like the rest of the SiGNUM encoder range, DSi is capable of operating at speeds up to 4,500 rev/min and temperatures up to 85degC.
SiGNUM also benefits from rugged IP64 sealed readheads, dynamic signal processing for excellent reliability, and ultra-low cyclic error (+/-30 nm).
In addition, comprehensive SiGNUM software enables optimum set-up and real-time diagnostics via a PC's USB port. Request a free brochure from Renishaw ...
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