On the roughing mill exit, there is a lot of steam due to the spray header. The steam obstructs field of view of the traditional scanning type HMDs as result, occasionally the signal flickers for a millisecond. The next generation HMD 4.0 from Proxitron have intelligent software features which allows to set dual thresholds (hysteresis).
Slab Detection in Excessive Steam (HMD)
Pilger mill in tube rolling mills - hot and cold pipe detection
HMD under most aggressive environment
- Flicker free operation due to dual threshold (hysteresis) setting option
- Adjustable response temperature
- Withstand ambient 2000C (water-cooling) and 2900C (w/o water cooling)
- Diagnostic alarm feature
Challenges
- On the roughing mill exit, there is a lot of steam due to the spray header.
- The steam obstructs field of view of the traditional scanning type HMDs as result, occasionally the signal flickers for a millisecond.
Solution
- The next generation HMD 4.0 from Proxitron have intelligent software features which allows to set dual thresholds (hysteresis).
- The upper threshold setting say at 6000C and lower threshold setting at 2000C. So when slab at 10000C cross the field of view of the HMD 4.0 detects the slab but due to momentarily presence of steam, slab temperature may appear to be lower than 600C will not cause the signal to flicker.
- Only if the temperature goes below the lower threshold setting i.e. 200C will HMD shows slab is not present.
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
