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The cost of the investment is often a barrier that prevents many companies from testing this new technology and its advantages (flexibility, reduction of time-to-market, die free production, etc.).
Fagor Arrasate’s modular concept makes it possible to start with a single laser module and add more in the future to increase the productivity of the line.
Laser cutting allows almost any desired part to be cut in almost any condition, but this flexibility means there are more parameters to manage.
Fagor Arrasate’s solution has been configured to maximise productivity to the highest quality standards in a userfriendly way.
The laser cell is a completely modular and scalable “blackbox” that can be composed of up to 3 laser units. A first advantage is the reduction on spare parts and number of different references, but the main one is that it facilitates the distribution of the workload between the laser heads, allowing higher throughputs and better part tolerances.
To better illustrate the performance of the modular concept, we can compare two scenarios, one in which each part is cut simultaneously by two laser heads and one in which each part is cut by a single head. In both cases the same performance is achieved, although in the second scenario tolerances of ±0.4 mm are achieved, compared to the first one´s ±0.7 mm.
To obtain this gain in cutting quality without losing tolerances, the dimensions of the working area for each laser are 1500mm in X direction.
This range allows cutting the entire contour within the limits of the working area in a single pass and moving on to the next part immediately without losing time as this second part is already within the working area.
The following image compares a cutting area of 1200mm travel with a cutting area of 1500mm travel.
In the first case, the laser will have to wait until the next part is within the cutting zone, while in the second case, the laser could already start on its second part, increasing throughput.
This advantage also helps with large parts, such as large trapezoids.
The main obstacle we must overcome with the modular configuration is the telescopic conveyor, as increasing the travelling stroke in X usually leads to a considerable lengthening of the entire line. In our case, the compact, self-developed telescopic conveyor makes it possible to maximise the cutting area without enlarging the layout.
Our highly dynamic telescopic conveyor can provide an acceleration up to 3,5G with movements permanently synchronized with the laser head.
This conveyor, whose speed is adapted to the speed of the coil, can operate in both start-stop and continuous mode. It features intelligent strategies such as the “expand hole” (X-Gap) that allows the evacuation of the scrap chutes through the conveyor.
This solution has also an impact on the quality of the parts, especially if we compare it to traditional blade tables or its motorized variant as we avoid marks due to direct interaction between the laser, the material and the blades, where material projections appear when cutting close to a blade, not necessarily above it.
The telescopic conveyor we developed overcomes all these problems.
The transport belts are protected from scattered laser stream by means of two guards designed to delay material deposition and extend their service life.
In addition, as an option, each laser unit can be equipped with an automatic cleaning system for the guards.
In the same way, conveyor belt cleaning systems can be installed for parts with higher requirements, such as skin parts.
Halfway between productivity and quality, we would like to point out that the two telescopic conveyors of each cutting unit are driven independently of each other. This allows intelligent strategies such as the “Expand Hole” (X-Gap) to evacuate small and medium-sized scraps that could lead to collisions in subsequent steps. The maximum size of the workpiece to be evacuated through the expanded hole is 500mm.
The laser gantry is the element that generates the cutting path and ultimately creates the cuts moving along the programmed path by means of linear motors for X and Y with a positioning speed of up to 150m/min and an acceleration of 3.5G. Its travel strokes are capable of covering the entire cutting area defined by the telescopic conveyors.
Our own patent pending edge detection system has been developed with the objective of continuously measuring the deviation of the strip and compensate this offset in the laser head. This allows high quality unions while cutting combined parts.
Again, maintaining the same philosophy of modularity, each laser unit is equipped with 1 or 2 ultra-highdefinition 3D sensors. They are continuously aligned with the laser head for edge measuring and a pair of mechanical guides at the entrance of each laser unit to set a reference.
The correction principle is based on having a fixed reference given by the pair of mechanical guides and a moving measurement system that detects the position of the edge.
As the measuring system is aligned with the laser head, the Y-deviation of each point is continuously corrected. But this system not only corrects for possible geometrical errors of the parts.
As the measurement system is a 3D UHD sensor, it gives both the Y and Z of the sheet metal in real time. Using the combination of both measurements the laser can be commanded to attack the part directly from the outside of the part reducing the cycle time.
This is especially remarkable on omegas or trapezoids, where the cycle time is very short and reducing a few tenths of a second has a big impact.
Together and in close collaboration with Fagor Automation’s R&D department, a specific CNC has been created for the laser cutting line and high-speed cutting control (HSC) algorithms have been developed. They are modified to the particularities of the sheet metal in motion and easily configurable to adapt to all types of part families, which translates into higher productivity.
Designed with the same modularity concept as the laser cell, the CNC solution can be easily adapted to 1, 2 or 3 cutting heads. The laser modulation status can be managed independently for each laser, ensuring good part quality in terms of burrs.
It is a system with an integrated synchronous PLC that allows the possibility of adding real-time applications, such as the web edge deviation correction system, which allows for improved cutting tolerances.
Moreover, thank to this integrated concept, a digital twin has been developed to calculate off-line productions rates without interrupting production and to allow programmers to choose between different strategies.
Distribution of the 1st workload
Distribution of the 2nd workload