The bks ultrasonic edge sensor

is a fork sensor for scanning the edges of sound-impermeable materials such as foil or paper.
This is why the bks is ideally suited for the web control of highly transparent foils, light-sensitive materials, materials with greatly varying transparency and paper subject to high paper dust loads.

The functional principle

The fork’s lower leg is equipped with an ultrasonic transmitter which cyclically emits short sound impulses, which are detected by the ultrasonic receiver arranged in the upper fork leg. Material passing through the fork covers this sound path and thus attenuates the receiving signal depending on the coverage, which is evaluated by the internal electronics. An analogue signal is output in dependence of the coverage degree.

The analogue output can both deliver voltage 0–10 V as well as current 4–20 mA.

The operating range amounts to 8 mm (±4 mm).

Via the Teach-in button

on the edge sensor’s top, the zero position of the edge to be controlled is set. There are two options for calibration:

• completely freeing the fork from the web material,
• pressing the button for approx. 3 seconds until the two yellow LEDs flash alternately. Ready. Or
• aligning the web edge inside the fork with the two marks to ensure a 50% coverage of the sound path,
• then pressing the button for approx. 10 seconds until the two yellow LEDs remain lit. Ready.

The bks edge sensor has a fork width of 30 mm and a fork depth of 33 mm. Other fork widths and depths are available upon request. The housing side is equipped with two consistent bores for the edge sensor’s mounting. The electrical connection is established via an M12 circular connector.

Three LEDs

indicate the position of the web material inside the fork. For the application of light-sensitive materials, the LEDs can also be switched off.

The bks is pre-set and immediately ready for operation. Optionally, it can also be comprehensively parameterised with the help of the LinkControl adapter LCA-2 and LinkControl software .

With a fork width of only 30 mm and a depth of 33 mm, it has a very compact design. Its working range of 8 mm and its high accuracy of 0.1 mm permit a wide variety of applications.