28 n MACHINE-BUILDING April 2025 www.drivesncontrols.com Automated machine for cutting steel mesh is ‘world’s first’ The ASA (automatic cutting system) machine handles, cuts and stacks the reinforcing steel meshes automatically. The rst challenge is to lift a single mesh precisely from the top of a stack of them. The manufacturing tolerances of the structural steel meshes are measured in the centimetres – but handling requires an accuracy of better than 1mm. In addition, the individual meshes do not align neatly when stacked. The rst stage in the process is when a crane places a stack of meshes up to 1.5m high onto a roller conveyor. How accurately the meshes are positioned in the pile is critical. The more they deviate from the entered position, the longer the separation process takes. The measuring system recognises and deviations in position and calculates a new position. Hambi uses 3D image processing to identify six suitable pick-up points for each mesh. Grippers then lift the mat, but this leads to a second challenge – as the meshes are picked up, they bend. Three separate drives are therefore needed for each of the six pick-up points to move the grippers in three dimensions. The drives need to be controlled precisely and synchronously. When starting to process an order, the system is rst set up by a machine operator who enters data such as the mesh dimensions, pick-up points, and cutting lengths via a control panel. The grippers are set to suit the mesh spacing and width. The six grippers that pick up the mesh are guided by laser scanners that determine the exact position of the rods. After being picked up, the mesh is transported to a slide-in table. The grippers then move back to the starting position to pick up the next mesh. A carriage grips the mesh and pushes it into guillotine shears. The cutting lengths are de ned in the production order. On the other side of the shears, another set of grippers pick up the mesh. The shears then move down to cut the mesh. The mesh then moves on to a turning frame which lifts and inverts it, before placing it on top of another mesh to create a new pile. This process is repeated until the maximum stack height (800mm) or number of meshes of the order has been reached. A roller conveyor then transports the pile of meshes to an end stop, ready to be transported by a crane to a storage area. As well as the 18 drives needed to compensate for the deformation of the mats during the initial lifting process, four more are used to control the movement of the mats. Hambi is using servodrives and amps supplied by Mitsubishi Electric. The compact MR-J5 motors oer high dynamics. The servodrives are synchronised via a motion controller and can be coupled via intermediate circuits, making the system energy-ecient. The machine’s other automation components have also been supplied by Mitsubishi. They include FR-E800 frequency inverters used for simple conveying tasks, and a Melsec iQ-R safety PLC which supervises all of the machine’s operations. Image processing is handled by three C controllers. The CC Link IE TSN communications protocol is used for real-time operation and provides safety-related communications. The gigabit-bandwidth network integrates communications between the controller, motion controls and safety system. After almost two years of development, the rst ASA – which is 6m high and more than 40m long – was commissioned in the spring of 2024. It is operated via a Mitsubishi GOT touchscreen terminal incorporating buttons and switches that allow operation with gloves. Converting to a new mesh size is said to be easy using the terminal. Only a few tasks need to be carried out manually during set-up. In routine operation, the system can be operated by one person. n Cutting the reinforcing steel mesh used by the construction industry is a monotonous and laborious business. A German machine-builder called Hambi (as known as Terhoeven) has tackled this problem, coming up with what it believes if the world’s rst automated machine for separating, cutting, turning and stacking steel mesh. Hambi’s 40m-long automated mesh-cutting machine is the rst of its type in the world
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