Bearing with built-in angle measurement

A radial thrust bearing has been developed with an integrated angle measurement system for use on machine tool rotary tables and spindle heads

The Unitec RTB AMS from RA Rodriguez includes a graduated stainless steel scale that fits on the bearing’s washer ring and two sensor inductive sensor heads on the outer ring at 180[degrees] to the centre line. During rotation, the sensors detect the slots on the scale and generate a 1 Vpp output signal for the machine CNC system that allows the angle to be continuously monitored. The scale slots, set at intervals of 1mm, are protected from dirt ingress by a metal cover.
The bearing is available in seven sizes with bores from 150mm to 460mm. One reference point is provided as standard, but on request, distance coded reference marks can be specified at any angle from 40 deg to 15 deg depending on bearing size. Absolute position can be determined by detecting either the single reference point or two distance coded marks during rotation. Total accuracy of the system for the 460mm bore size is up to 3 arc seconds.

Ultrasonics keep trains on the rails
US researchers claim to have identified an improved way of finding defects in steel railway tracks.
A team led by Francesco Lanza di Scalea – professor of structural engineering at the University of California, San Diego – has used laser beam pulses to gently ‘tap’ on steel rails.
A prototype vehicle rolls down the track delivering ultrasonic laser beam taps at one-foot intervals. Microphones are positioned a few inches above the rail and 12 inches from the downward-pointed laser beam. They detect any reductions in the strength of the ultrasonic signals, which indicates surface cuts, internal cracks and other defects.
A prototype vehicle equipped with the UCSD technology detected at least 77% of internal defects and at least 61% of surface cuts in a recent test run.
According to the Federal Railroad Administration, track defects account for about one-third of the 2,200 annual train derailments in the U.S.
The UCSD team claims that its method is an improvement on existing methods because it sends the ultrasonic pulse along the rail, rather than firing it from above.
“Our pulsed-laser technique is potentially very effective at finding internal rail defects,” said Lanza di Scalea.

Industrial and scientific imaging
The regular series of free technical seminars offered by UK Industrial Vision Association (UKIVA) during Photonex this month (18 and 19 October) will have a slightly different emphasis this year.
The theme of ‘industrial and scientific imaging’ reflects the association’s recent expansion of its scope of activity to actively encourage companies involved in scientific imaging applications to become members. UKIVA members Alrad Imaging, Firstsight Vision, Flir Systems, Framos Electronics, Multipix Imaging and Lambda Photometrics will be contributing to the seminars.
Topics will include extraction of 3D information from 2D images, updates on megapixel CCD and CMOS sensor and camera technology and explanations of the different camera sensor technologies with real-world examples from industry and science, as well as infra-red imaging for machine vision.

Vision sensor checks the beer
Vision sensors are being used in a Vienna brewery to check beer cans in boxes and bottles in crates to ensure they contain the correct number.
The technology used is the ‘Checker 101’ system from Cognex, supplied through the image processing department of Cognex partner Schumachtl.
Each box of cans is passed along a running conveyor belt equipped with the sensor to determine whether it contains 24 correctly inserted cans before the box is shrink wrapped. The beer bottle crates are inspected in a similar manner. The Checker can differentiate whether the bottles have light or dark tops, performing an additional quality inspection. The sensor automatically adjusts to the respective product according to whether there is an 18, 20 or 24 bottle crate on the lie. The operating staff do not have to modify the checking station when changing the job type. Crates are inspected at a rate of approximately one per second.

Tom Shelley

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