A Straightening machine is a heavy mechanical device that is used for straightening different types of metal objects like wires, bars, beams, tubes, channels, rods and h-beams. These machines are widely used in metal working industries all over the world. These machines are available in various sizes and designs. These are highly advanced machines and are equipped with the latest technology and top grade raw materials to ensure the optimum performance of the device.
These devices can easily perform the task of straightening any rolled, drawn or extruded metals in cold condition. The basic working principle of these devices is that the work rollers of these machines are backed up by support journals and are capable of back bending the material to an acceptable level of flatness. The optimum straightening depth setting for the work rollers is determined by a combination of factors such as material thickness, type, roller diameter and center distance spacing. Once the optimum depth setting is determined for a specific material, it must be consistently returned to each time the straightener is run. Straighteners are often provided with a method of calibration for the upper work roller depth setting such as a simple calibrated scale and pointer or dial height indicator.
Besides the maximum straightening force and structure, the ability of a straightener to achieve an optimum level of flatness is also determined by the amount of stress that the work rollers apply to the material. This stress is a function of the maximum straightening force and the elastic-plastic deformation that occurs during the straightening process. The percentage of the total material thickness that is affected by plastic deformation is called the plastic ratio.
The higher the plastic ratio, the less stress is applied to the work rolls during the straightening process. This decrease in stress results in a more gradual and consistent straightening effect. The lower the plastic ratio, the more stress is applied to the work rolls during the process and this can result in a sharp, inconsistent straightening effect.
In addition to the above factors, the straightener capacity is also limited by the machinability of the material. The amount of pressure exerted on the work rolls by the material can vary throughout the length of a piece of material due to differences in its quality. Consequently, a single pair of work rollers cannot provide an adequate level of flatness on most materials. This is why straighteners are usually designed with multiple work rollers.
Danieli offers a range of multi-roll straighteners to meet the requirements of any application. These are available in three main types – vertical/horizontal axis multi-roll machines, two roll machines and 10 roll machines. Each design of the machine is carefully tailored to the profile to be straightened. As a result, the machine provides an excellent final bar/profile straightness down to 0.2 mm/m. Its high speed and reliability of operation are key features, together with easy operating and maintenance. The machines can be supplied in a variety of models, from bar diameters 4 mm to 250 mm.