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 that is exposed to special demands. For this application Johannes Hübner Giessen developed a special looper encoder, which boasts a considerably longer lifetime thanks to especially designed-in features.
Rolling mills /Looper: Special looper encoders withstand the most extreme operating conditions in hot roll stands
Pilger mill in tube rolling mills - hot and cold pipe detection
Special looper encoders withstand the most extreme operating conditions in hot roll stands
- Subject to high loads from shock, temperature and cooling emulsions
- Heavy-duty ball bearings with special lubrication
- Increased lifetime
- Reduced downtime
Loopers in hot rolling mills are working under extremely rough conditions.
- 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 that is exposed to special demands.
- The setting angle up to only about 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.
- Formerly used standard encoders have not reached the required lifetime.
Looper encoder with heavy-duty ball bearings and special lubrication for long lifetime.
The Hübner Giessen solution
- For this application Johannes Hübner Giessen developed a special looper encoder, which boasts a considerably longer lifetime thanks to especially designed-in features.
- These contain oversized bearings with the dynamic load rating increased by 40% as well as a special radial shaft sealing ring with an additional protective lip.
- To guarantee the best signal quality the bearings are not primarily designed for high speeds, but rather for high shock loads up to 450 g.
- The min. degree of protection is IP66/ IP67 with an operating temperature up to 100 °C.
Products and Accessories
Case Study Number
- The increasing flexibility of production lines requires a high adaptability of sensors. Continually changing object geometries, different temperatures and very high radiation or surrounding temperatures are no rarity.
- In a pilger mill those rough conditions can be found, among others in the production of seemless steel pipes. The raw steel blocks, each weighing a few tons are heated up first in a round oven at a temperature of 1300 °C.
- After descaling of the surface, the steel block is prepunched in a hole press with a strength from a converted 2000 t. In the next sloping rolling mill the growing pipe rotates between two rollers that are positioned at an angle to each other. The punching is widened to the size of the mandrel diameter.
Previous solution / Competitor product
- The sensor that was installed at this application is the HMD OKA 2038.38 G with tube OL 19.
- The signal of the infrared sensors controls the movement of centering device and abutment. The point of view is restricted by the tube and prevents disturbances by steam in the cooling phase.
- An optimum adaptation to the operating conditions is given due to the adjustable response temperature. The HMD with self-learning response temperature (Auto-Teach function) is suited to continually changing conditions.
- The compact sensor with a stainless steel housing can withstand surrounding temperatures of up to 75° C. The use of a cooling jacket raises this up to 200° C.
- Alternatively sensors with fibre optic cables are available which permit an application at ambient temperatures up to 600° C without cooling.
- High temperature stability
- Recognition of hot objects at big distances
- Self adjustment with Auto-Teach or step switch for the response temperature
Product Part number
- OKA 2038.38 G
- Piros swivel stand HM2
- Tube OL 19
- Pilot light unit (for alignment) DAK 308 + OL 26
- Different cable lengths (e.g. 15 m)
compared to previous solution or competition
Other Solutions in Hot Rolling Mills – Finishing Mills