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.
Overspeed switch EGSH 41 ensures safely limited speed in the mill stand
Pilger mill in tube rolling mills - hot and cold pipe detection
- Safeguards personnel carrying out necessary work in the danger zone
- Switching points set without intervening in the PLC programming
- Safety certified encoder simplifies risk assessment
- Complete solution including safety mechanical parts and installation service
Safety certified system solution consisting of heavy duty encoders and tailor-made mechanical attachments.
Challenges
- In addition to sensing speeds for motor control and protection it is also necessary to implement the safety function SLS (Safely-Limited Speed) for the main drive and for each coiler. The purpose behind this measure is to safeguard personnel in the danger zone as they carry out necessary inspection and maintenance work on machinery. The conceptual solution designed to implement SLS should also take into consideration reliable mechanical assembly.
Solution
- The first step was to document the requirements and the installation conditions at the customer’s site before drawing up an overarching concept for the different points of installation. System solutions consisting of safety-certified, hollow-shaft type overspeed switches EGSH 41 (SIL 2 / PL d) as well as attachments calculated for safety and guaranteed fault exclusion are at the core of our customized solutions. An additional encoder with incremental output for motor control and a speed switching output for motor protection were integrated in the system solution as required. Hübner specialists installed all of the system components and carried out control measurements to verify the accuracy of the installed equipment and documented the results.
Turnkey encoder modernization by engineering support package with site measuring, construction, mounting and commissioning support.
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
