The skip-car control mechanism utilised to date included two mechanical, geared cam limit switches that are time consuming to program. 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.
MAG with large split pulse wheel for improved control accuracy
Pilger mill in tube rolling mills - hot and cold pipe detection
- Custom-made attachment solution with pulse wheel diameter of 1300 mm
- Easy retrofit solution thanks to split pulse wheel and adapter ring
- Significantly higher resolution in comparison with original tooth wheel scanning solution
- Optimized sensor systems compensate eccentricity to ensure the drive pulley runs true
Before: The resolution of the existing inductive tooth wheel scanning solution is no longer sufficient for high-precision speed control.
Challenges
- The objective is to improve the accuracy of the closed-loop speed control system on a Koepe winder with an integrated motor. The resolution of the existing inductive tooth wheel scanning solution no longer meets customer requirements, so that a new sensor system is needed. The Koepe principle utilizing an integrated motor sees a drive pulley rotate around a fixed axle. Consequently, the magnetic scale of the speed measuring sensor cannot be attached to a rotating shaft. The task was made even more difficult by the fact that the drive pulley runs out of true (eccentricity) by several millimetres, which is something the measuring system must compensate.
After: The tailor-made magnetic encoder system MAG 1300 provides 2460 square pulses per revolution.
Solution
- An encoder system was developed to meet the exact requirements of the application. This consists of a pulse wheel with a diameter of 1300 mm and a magnetic scale. The pulse wheel has a split design consisting of two halves to considerably simplify installation. Both pulse wheel halves are precisely bolted to an equally split adapter ring fastened to the drive pulley. The sensor system is well-protected in a scanning head, which is fastened to a fixed part of the Koepe winder with a special bracket. Optimized at the maximum gap between the pulse wheel and scanning head the measuring system supplies 2460 square wave pulses per revolution.
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
Case Studies
Other Solutions in Hot Rolling Mills
Sample case study title lorem ipsum here
Short description of the problem solved, maybe include the client name.
Sample case study title lorem ipsum here
Short description of the problem solved, maybe include the client name.
Sample case study title lorem ipsum here
Short description of the problem solved, maybe include the client name.
