Switching accuracy at the crane hoist by compact incremental encoder with electronic over speed switch
The EGS series of electronic overspeed switches from Johannes Huber Giessen are the ideal solution for heavy -duty applications that demand the highest levels of precision and reliability. These devices make it possible to monitor both overspeeds and underspeeds across the complete speed range with utmost precision.
Higher switching accuracy at the crane hoist by compact incremental encoder with additional electronic overspeed switch
Pilger mill in tube rolling mills - hot and cold pipe detection
- Modern replacement solution for mechanical overspeed switches
- Compact design with an incremental output and electronic overspeed switch
- Pre-programmed switching speed
- Easy mechanical and electrical exchangeability
Before: Tacho generator with attached mechanical overspeed switch for speed measurement and monitoring at the hoist of a RMG crane.
- A tacho generator and an additionally attached mechanical overspeed switch are responsible for speed measurements and overspeed monitoring at the hoist. Due to its design the mechanical overspeed switch has a switching tolerance of ± 75 rpm, which leads to inaccuracy at the desired switching point. Moreover, the mechanical overspeed switch only reacts to speeds of 700 rpm and above. The signal quality of the tacho generator does not o er the precision required in today’s world. The customer wished for a replacement solution that corresponds to current state of the art technology.
Products and Accessories
After: Significant more precise speed monitoring by the incremental encoder FG 2 with integrated electronic overspeed switch.
Based on the experience gained from previous modernization projects the implemented solution saw the installation of an incremental encoder FG 2 with an integrated electronic overspeed switch (option S). In addition to the incremental position value this compact encoder solution o ers a switching speed set ex works. The electronic overspeed switch provides signifi cantly more accurate overspeed monitoring. The switching speed of 2550 rpm was adopted from the previous solution 1:1. Not only is the overall length now distinctly shorter, this solution requires no changes to the existing mechanical interface. The entire conversion was implemented quickly and easily.
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