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Case story: Looper
Heavy Duty Sensoric

INDUSTRY: Steel and rolling mills
FIELD: Hot rolling mills
APPLICATION: Looper
In hot rolling mills rolling stock is rolled in a malleable state at temperatures above the recrystallisation temperature (steel: 720 to 1260 °C; aluminium: 250-500 °C). This makes it possible to achieve high forming ratios (input to output thickness) of up to 1:250. Typical ingot thicknesses in a hot wide strip mill are 240 mm, while final thicknesses following the rolling process are min. 0.8 mm.
Task:

Loopers are normally used to control the tension of the metal strip between roll stands. The rotational angle of the looper is measured by a feedback encoder designed to meet special requirements. The setting angle of just 45° results in a partial load on the encoder bearings in conjunction with insufficient bearing lubrication. The encoder is subject to high levels of shock and temperature loads as well as oil/cooling emulsions/ water at the place of installation. The standard encoders used to date by the customer have been unable to offer the required service life.
Huebner solution:

For this application Johannes Huebner Giessen developed a special looper encoder, which boasts a considerably longer service life thanks to specially designed-in features. It has oversized bearings with the dynamic load rating increased by 40% as well as a special radial shaft sealing ring with additional protective lip. To guarantee the best-possible signal quality the bearings are not primarily designed for high speeds, but more for high shock loads up to 450g. The min. degree of protection is IP66/IP67 with an operating temperature range of up to 100 °C.
Products
Looper encoder with SSI interface (13 bit) – other interfaces available on request.
- Oversized bearings with steel bushing
- High strength, stainless steel reinforced shaft
- Special radial shaft seal / protective lip
- For temperatures up to 100 °C, shock proof to 450g
Customer benefits
Strip tension control with reliable encoder
- High plant availability
- Reduced maintenance/replacement requirements
- Good signal quality even when subjected to extreme shock and vibration loads
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