We have been asked how object detection can be successful on narrow conveyor belts in the area of feeding technology when the installation space, conveyor width and object position place special demands on the sensors.
In the application described, white matt plastic parts with a height of approx. 30 mm are to be reliably detected. The parts are fed individually via a spiral conveyor onto a conveyor belt that is only 54 mm wide.
This means that the available distance between the sensor and reflector is also only around 54 mm.
The application is made even more difficult by the fact that the plastic parts are not positioned on the belt. The front edge is therefore not defined – the component can be on any side, with recesses or irregular contours towards the front. This rules out purely edge-based detection; object detection must function independently of position, contour and orientation.
For this type of application, wenglor recommends a classic retro-reflex sensor in a miniature design that works independently of the object shape and position.
The P1KL002 red light retro-reflex sensor is specifically suitable here.
Retro-reflex sensors work with a separate reflector. As long as the light beam passes undisturbed from the sensor to the reflector and back, the output remains inactive. As soon as an object – regardless of its geometry – interrupts the beam, reliable switching takes place. It is precisely this principle that makes them ideal for applications with an undefined leading edge.
The P1KL002 is a universal retro-reflex sensor with red light and is specially designed for tight installation situations. It is particularly impressive at close range below 100 mm with a very small light spot, which means that even small or narrow objects can be reliably detected.
Another advantage:
White is the ideal object color for optical sensors. In this case, the matt white plastic part even represents an “ideal object”, as it reflects the emitted light very well or reliably interrupts it.
A reference reflector is used as the reflector. Depending on the reflector type, the P1KL002 can even be mounted up to 10 mm away from the sensor. This makes the solution ideal for extremely narrow conveyor belts.
In the accompanying video, model P1KL006 was used as an example, combined with a reflector with a macro structure.
The setup was carried out with a sensor-reflector distance of approx. 60 mm, which was due to the conditions at the office workstation.
Among other things, the following were detected:
Both objects were reliably detected regardless of their position and contour – a good example of how robust this sensor concept is in real-life use.
For object detection on very narrow conveyor belts with an undefined object position, a retro-reflex sensor with a miniature design is the technically cleanest and most reliable solution.
With the P1KL002, wenglor offers a sensor that works reliably even with minimal distance between sensor and reflector, changing object orientation and difficult contours – ideal for applications in feeding and conveyor technology.
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