With a special lifting system based on his SHE screw jacks Pfaff Silberblau is now shortening the service life of galvanizing plants in the steel industry. The temperature of the gear oil is monitored by a special sensor and kept at an optimal level by an active cooling circuit. At the same time, a contactless sensor continuously monitors the temperature on the spindle and only switches off the system if there is a risk of overheating.
Continuous strip galvanizing systems are used in the industrial production of galvanized sheet steel, for example for use in the packaging industry or in vehicle construction. Here, a sheet metal strip is continuously pulled through a zinc bath and then wound up. At the heart of these plants are zinc hearth furnaces, in which the metal is melted and kept in the liquid state. For most CGL (Continuous Galvanizing Line), two of these furnaces are available with different zinc alloys and are used as needed. For this purpose, the required oven is moved from its parking position on a rail system in the floor below the production line on the lifting and then lifted from this in the production line. In order to raise these ovens with a weight of around 500 t by 2 m, a strong and above all sturdy lifting system is necessary. But there is also the ever louder demand of the steel industry for shorter service lives. The shorter the cycle times of the lifting gear used, the more flexible and faster a production line can work.
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With a special solution Pfaff Silberblau now fulfills these high standards of an international steel producer. At the heart of the lifting system are four lifting elements of the size SHE 200 from Pfaff-silberblau, which are driven by a central motor via transfer case and cardan shafts. The peculiarity of the system of the drive technology specialist from Kissing is the constant monitoring of the temperatures, both of the oil for the gear lubrication and the spindle itself. A special sensor continuously records the temperature of the lubricant. When a preset limit is reached, an active cooling circuit keeps the system at the system-specific temperature level. The temperature of the spindle, which absorbs a very significant part of the heat generated, is permanently monitored by means of a non-contact temperature sensor. If this determines an impermissibly high value, the system switches off automatically and prevents overheating.
For the user, this means that he can operate the lifting system until a certain limit temperature is reached and the system switches off automatically. In conventional systems, on the other hand, a cooling time of up to eight hours is necessary after each cycle, which means expensive standstill phases which are avoided with this special solution. The cooling circuit of the lifting system consists of a pump unit, a flow and return and an oil-air cooler with mounted radiator fan. In addition, a level sensor polls the oil level in the screw jack, and the controller releases the jack when the fill level is confirmed.
Central lubricant pumpTo reduce manual maintenance while optimizing spindle lubrication, the lift has a centralized lubricant pump. Taking into account the respective direction of travel when lifting or lowering the load, it introduces the lubricant into the relevant areas of the spindle nut system.