Leuze Sensors Automate Brick Manufacture

Sensors from Leuze Electronic have been used by Zeller Poroton to automate the manufacture of a building brick that combines the clay brick with rock wool. The company has long relied on various sensors from Leuze, from diffuse reflection light scanners to through-beam photoelectric sensors and optical data transceivers, as well as optical distance measurement devices. Leuze Electronic's through-beam photoelectric LSR 25B sensors are used throughout an automation system for the production of the Thermoplan MZ8 building brick.

A specially developed, stable sleeve of pure brick ceramic is filled with high-quality rock-wool elements and both securely bonded to one another, to produce a product giving maximum thermal insulation, good soundproofing and stability, good moisture characteristics and fire protection properties. Heinz Kunzmann, factory manager at Zeller Poroton, developed automation systems where a roll of rock wool is fed in, cut, and then pushed into the chambers within the brick ceramics. During this process, the through-beam photoelectric sensors detect the start and end of the mats and monitor the stack heights.

Kunzmann said he particularly values the devices' robust construction with stable and tight housing, and the performance reserve, which ensures reliable object detection in an environment laden with rock-wool dust. The automatic cutting and filling system for the MZ8 is safeguarded with Leuze Electronic's Robust multiple-light-beam safety devices. Transmitters and receivers of the three-beam system are functional units with separate transmitter and receiver profiles. With their integrated optics heating and protection class IP67, the active optoelectronic protective devices are designed for operation in rough environmental conditions.

Hard conditions are encountered even in the shipping area. Another automation solution is evident in the transfer station near the shipping area, which is dependent on the reliability of Leuze Electronic's sensors. High demands are made of the sensors, which look down onto stretch-wrapped stacks of bricks over large detection distances. Additional challenges are the temperature influences of working in an outdoor area where, depending on the time of year, it can be bitterly cold. In this transfer station, a gantry crane lifts the pallets of bricks that arrive on a conveying belt from the production area, across to free storage spaces from where forklifts load the stacks onto trucks.

Kunzmann mounted an HRT 96M/P-5000 diffuse reflection light scanner with background suppression on each side of the gantry crane's traverse. With a maximum scanning range of 5m, they monitor the transfer station from above. If six sensors arranged in a row do not detect a stack of bricks, the respective storage space is not occupied. Reflections off the stretch-wrap material do not affect the sensors, enabling the system to unload up to 800 pallets per day.

The gantry crane itself is positioned by means of two AMS200 optical distance measurement devices, which thereby ensure uniform speed. With these devices, positions can be detected at a range of up to 200m with millimetre precision. The distance data received in the distance measurement device is available as speed information, on the basis of which speed monitoring can also be performed.