For precise speed control in rolling mills the main drives of the roll stands and the coilers need to be equipped with an encoder. In addition, it is often necessary to provide increased protection for personnel during special operating modes, such as: For this application Johannes Hübner Giessen has been working with Motor OEMs for many decades to provide complete solution ie. Electrical and mechanical components.
Robust encoders ensure more precision and less downtimes
Pilger mill in tube rolling mills - hot and cold pipe detection
- Greater functional component reliability
- Higher converter plant availability
- More precise measurement signals despite shock and vibration loads
- Easy and time-saving programming
Before: Old skip-car control mechanism with two mechanical geared cam limit switches.
- The skip-car control mechanism utilised to date included two mechanical, geared cam limit switches that are time consuming to program. The mechanical overspeed switch utilized can prove problematical when subjected to shock and vibration loads. Neither of these components exhibits the required precision and as such are not suitable to meet the modern-day requirements of steel mill operations.
After: More precise signals because of robust combination of bearing block and heavy duty encoders.
- Upgrading to meet modern demands required suitable components for measuring actual values that are not only characterized by their high accuracy and functional reliability, but are also easy to program. Hübner Giessen replaced one of the geared cam limit switches with a series FG 4 K incremental encoder and an AMS 4 K type absolute encoder with integrated SSI interface. Fitting the devices to a bearing block increases their resistance to shock and vibration loads and compensates the mechanical tolerances of the installed, previous transfer gearbox. The other cam limit switch will also be replaced in a second modernizing step as will the mechanical overspeed switch be replaced by a programmable electronic overspeed switch.
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 – Roughing Mills