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.
Home Case Studies Bearingless encoder system MAG withstands permanently extreme environmental conditions in the roll stand
Bearingless encoder system MAG withstands permanently extreme environmental conditions in the roll stand
Pilger mill in tube rolling mills - hot and cold pipe detection
- Designed for high shock and vibration loads, aggressive cooling emulsions
- Tailor-made solution features an installation width of just 10 mm
- Special stainless-steel ring ensure a long service life
- Interference-free speed measurements of the metal strip for optimum drive control
Sensors for strip speed measurement are exposed to extreme ambient conditions in the area of the measuring roll.
Challenges
- The actual feedback value of the effective speed of the metal strip is required to effectively regulate the roll stand drives. It is possible to measure this value using suitable sensors located at the drive measuring roller between the stands. Shock and vibration loads as well as aggressive cooling emulsions mean the devices need to withstand extreme environmental conditions. In addition, limited installation space made it necessary to adapt the sensor system. Due to the loads mentioned above a measuring system installed to date was unable to supply interference-free speed signals.
Tailor-made MAG system solution with extremely slim design and special
Stainless steel bandage to protect the MAG pulse wheel.
Solution
- Following discussions with the end customer Johannes Hübner Giessen installed a suitable measuring system with magnetic sensor technology that could be adapted to suit the conditions. The selected MAG 260 consists of a pulse wheel with an outside diameter of 260 mm as well as a scanning head with completely encapsulated electronics sealed to IP67. The bearingless system is unaffected by shock and vibration; it supplies interference-free signals even when exposed to extreme high quantities of aggressive liquids and vapours. Without using the reference pulse it was possible to implement the extremely slim 10 mm design width as needed.
Products and Accessories
Case Study Number
- TP3
Challenge
- 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
- N/A
Solution
- 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.
Customer Benefits
- Maintenance-free
- 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
Brand
- Proxitron
Accessories
- Piros swivel stand HM2
- Tube OL 19
- Pilot light unit (for alignment) DAK 308 + OL 26
- Different cable lengths (e.g. 15 m)
Customer Testimonial
compared to previous solution or competition
