QuickChange™
Flexibility for singles and packs
The QuickChange™ system enables a single crane to use a range of different magnet spreader beams.
The lower spreader beams are remotely coupled with the permanently installed upper spreader beam, and the mechanical and electrical connection is made automatically.
Such as the system bellow:
A slim magnet system designed for single beams is used to enter in-between narrow stacks in the warehouse. Storage can be arranged compact and high, resulting in small space consumption and high handling speeds.
Figure 1: QuickChange™ system with lower spreader beams for handling individual sections
Change spreader beam in shortes time
This customer gets his sections delivered by train in packs weighing up to 8,000kg. Handling of such packs surpass the capacity of the slim single beam magnet system above.
A second magnet system featuring large magnets with a deep magnetic field is used to move the packs. A common interface allows to interchange the two magnet systems. Coupling and decoupling to the crane is done at the press of a button, both mechanically and electrically.
Figure 2: Automatic decoupling of the spreader beams for individual sections
The crane operator interchanges the two magnet systems within a few seconds. No manual work on any hook or plug is required.
Figure 3: Quick interchange of two different magnet systems
Removing residual magnetism
Leaving no traces
Demagnetisation
Residual magnetism in steel can cause serious problems. The material may ‘stick’ to machine, small pieces of steel (washers, bolts, swarf etc) can adhere to the transported material or welding arcs can be ‘blown‘ or ‘deflected‘.
Efficient demagnetisation of the load is essential. Our magnet controllers perform extensive and fast demagnetization processes. This reduces residual magnetism to a minimum in the shortest possible time.
What happens when steel becomes magnetised?
Ferromagnetic materials which have never been exposed to a magnetic field consist of randomly ordered magnetic domains such as shown below in Figure 1. Steel, when in this state, does not show any magnetic effects (corresponds to point a in Figure 3).
Figure 1: Magnetic domains positioned at random (material demagnetised)
When the material above is exposed to an external magnetic field, the magnetic domains start to align. The stronger the outer magnetic field, the better alignment we get. If all of the domains are aligned as shown in Figure 2, the material is magnetically saturated (Point b in Figure 3). Saturated steel goes allong with magnetic field strength of about 2.4 Tesla.
Figure 2: All magnetic domains aligned (material magnetically saturated)
Unfortunately, the magnetic domains do not return to their random state when the external magnetic field is removed. This results in residual or permanent magnetism remaining in the material (see remanence Point c in Figure 3).
To remove such residual magnetism a demagnetisation process needs to be applied. The external field is not just removed but follows a certain fluctuation in time and strength. The magnetic domains are kind of ‘shaken‘ which causes their uniform alignment to fall apart. Such method needs to match the magnetic properties of the material. Mild steel quickly loses its magnetism, a material property refered to as ‘soft magnetic‘. Quality steel on the other hand, is ‘hard magnetic‘ and more difficult to demagnetise.
RDS (Reverse Degauss System)
RDS demagnetisation is designed for quick elimination of residual magnetism in mild steel. Applying a negative magnetic field causes the magnetic domains to gradually adopt a random alignment. When the opposing field is turned off (Point d in Figure 3), the residual magnetism is elimated to a vast extend.
Figure 3: Hysteresis of soft magnetic mild steel
DDS (Downcycle Degauss System)
DDS reduces the residual magnetism for hard magnetic materials. A series of polarity changes in a magnetic field with decreasing amplitude is applied as shown below in Figure 4:
Figure 4: Typical magnet current during DDS demagnetisation
The magnetic domains are effectively ‘shaken‘ into a random state, residual magnetism is reduced down to typically 5 mT corresponding to about 0.1% of field strength of saturated steel. This is well bellow the critical levels causing the problems above. Figure 5 shows the resulting hysteresis:
Figure 5: Hysteresis of hard magnetic quality steel
FE method
Magnets do not only need to lift weights, they also must be safe in case of application specific imperfections and disturbances. Magnets are never in perfect contact to the load. Dirt, ice, metal chips, packing materials, strappings, surface coatings and also load deflections force an air gap between magnet and load.
Such effects must be taken into account to make a magnet not only strong but also safe. Magnetic fields must penetrate such air gaps and match customer specifications also in the presence of such imperfections. For magnet design, TRUNINGER uses finite element simulations to optimize existing magnet designs as well as to develop new, customer-specific magnet solutions. Lifting force, magnetic penetration depth and air gap compatibility can be simulated for smooth implementation of customer specifications from theory to practice.
Figure 1: FE-simulation, I-beam bundle under lifting magnet
Advantages
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Features of our lifting magnet technology.
Our systems incorporate a wide range of features for all purposes. Combining these elements in close cooperation with our customers, we construct individual magnetic lifting solutions that best match the requirements.
Convince yourself of the various functions and possibilities of our lifting magnet technology!
