The dimensioning of the section bending machine in terms of mechanical components, support structure and drive is the most important factor to determinate the capacity of the machine and its durability. It must be considered that, also if through some expedients it is possible to “lighten” the machine, the section bending machines are subject to different kind of stress and it is not possible to substitute a correct mechanical dimensioning with punctual reinforcements. Let’s talk for example about the usage of support brackets, that should allow to reduce the section of shafts: it is evident that if on one side the usage of such devices reduces the deflection of shafts, on the other does not have any effect on the resistance against torsion, that is the most critical factor for the resistance against breakage.
The big machines must be always used for a correct size range of products, because not always are the right solution to bend the small profiles. The reasons have a nature:
• Geometric: the big machines are equipped with shafts and rolls with high diameters and clearly is not possible to bend the profiles at a smaller diameter than the one of the top roll. The distance between the rolls determinates the length of the straight part at the beginning and at the end of the profiles. Obviously the distance is higher in case of machines with higher capacity and so using a bigger machine to bend small profiles, the length of straight part will be longer compared to the one obtainable using a smaller size machine.
• Economic: the tubes, some hollow sections and special profiles in general require special rolls and dedicated equipment to be bent. The production cost of such special tools is as much high as big is the machine. It must be considered, moreover, that the time required to setup the machine for a specific production is increasing proportionally with the size of the machine, due to the fact that weights are higher and dedicated lifting devices must be used during operations. Considering what above, it is clear that the value of small profiles cannot compensate such expenses.