Sensors for extreme conditions in brick factories

  • Der gesamte Produktionsablauf bei Zeller ist elektronisch gesteuert. Die dazu notwendigen Signale liefern Sensoren von Leuze electronic.

  • Reflexions-Lichttaster an der Traverse des Portalkrans überwachen die Rangierfläche von oben, um freie Abstellflächen zu finden.

  • Distanz-Messgeräte überwachen die Positionierung des Portalkrans und den gleichmäßigen Antrieb seiner Achsen.

  • Der anfallende Staub beim schneiden der Steinwollmatten für den ThermoPlan® MZ8, beeinträchtigt nicht die Funktion der Sensoren.

Proven cooperation

Sensors demonstrate reliability under the most demanding conditions in a brick factory

There are few manufacturing processes in which the level of strain placed on sensors in machines and automation systems is as great as it is in brick factories. These sensors are subject to high mechanical loads, soiling and thermal effects. For more than 20 years, ZELLER POROTON has been relying on the robust designs and high function performance reserves of sensors from Leuze electronic.

The production of bricks for house construction is hard work. From the moist clay to the packaging of the fired bricks, materials and processes strain the work environment of man and machine. Fire, air, earth and water have always comprised this building material, which has a history that stretches back millennia. For ZELLER POROTON as well, the company history begins with the extraction of clay from sites near Alzenau. What has changed since the founding of the Lower Franconian family business in 1808 is the further development of the natural product with respect to quality, shape and processing.

Today, the entire production sequence at Zeller is controlled electronically. From the blank to the final product, the individual bricks can be tracked, observed, and, at the same time, be recorded in the central computer with all necessary data by means of a computer. "We develop and construct many of the automatic processes ourselves," explained factory manager Heinz Kunzmann: "We know best what requirements arise from the, in some cases, extreme process conditions. Furthermore, we want to put our know-how to work for us!"

For more than 20 years now he relies on sensor systems from Leuze electronic in a wide range of designs, from diffuse reflection light scanners to throughbeam photoelectric sensors and optical data transceivers as well as optical distance measurement devices. "The products function reliably, even under the hard environmental conditions encountered in brick production," confirmed Kunzmann satisfied, and mentioned in this context the optical data transceivers that he mounted in 1990 in side-tracking skates in front of the ovens.

Process reliability with performance reserve

Particularly well suited are the B series device versions, as they are used in the form of throughbeam photoelectric sensors (LSR25 B) in an automation system for the production of the new ThermoPlan® MZ8. This product is a building brick that combines the clay brick and rock wool building materials, with the advantages of each. For this purpose, a specially developed, stable sleeve of pure brick ceramic is filled with high-quality rock wool® elements and both securely bonded to one another. The result is maximum thermal insulation, good soundproofing, very good stability, outstanding moisture characteristics and good fire protection properties.

With the automation systems developed by Kunzmann, the rock wool mats are fed in from a roll, cut, and then pushed into the chambers in the brick ceramics. During this process, the throughbeam photoelectric sensors from Leuze electronic detect the start and end of the mats and monitor the stack heights. What Kunzmann particularly values in the devices is their robust construction with an extremely stable and tight housing. Also important for him is the performance reserve, which ensures reliable object detection in the environment that is laden with rock wool dust.

The automatic cutting and filling system for the MZ8 is safeguarded with Multiple Light Beam Safety Devices of type ROBUST. Transmitters and receivers of the three-beam system are functional units with separate transmitter and receiver profile. With their integrated optics heating and protection class IP 67, the active optoelectronic protective devices are also designed for operation in rough environmental conditions.

Hard conditions are encountered even in the shipping area

Kunzmann shows another automation solution whose function is dependent on the reliability of the Leuze electronic sensors in the transfer station near the shipping area. Placing high demands on the sensors here are, above all, the stretch-wrapped stacks of bricks, large detection distances and, not least of all, temperature influences in the outdoor area where, depending on the time of year, it can be bitterly cold. In this transfer station, a gantry crane with an appropriately dimensioned gripper transports the pallets of bricks that arrive via a conveying belt from the production area to free storage spaces. From there, forklifts load the stacks onto trucks. "By means of the control, the system knows which stacks are stored on which spaces, but not which of these pallets have already been retrieved by a forklift," explains Kunzmann. For this reason, he mounted 18 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 5000 millimeters, 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 of the stretch-wrap material do not affect the sensors. Using this system, up to 800 pallets can be unloaded per day.

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

"While dust and heat are the primary factors contributing to hard working conditions during operation, in the loading area, it is the low temperatures during the cold parts of the year," says Kunzmann as he outlines the extreme strain placed on man and machine in the brick factory.

Toegepaste producten

  • Branche/vakgebied

    Mounting/handling technology (feeding), conveyor and storage systems (cranes)

  • Taakomschrijving

    Optical data transmission, Access guarding, Presence inspection, Distance, Positioning

  • Applicatie

    Sensors for extreme conditions in brick factories