Straightening machine are heavy machines mostly employed in metal working industries to straighten different type of metal objects like rolled beams, sheets, wire rod, strips, metal studs, tubes, channels, h-beams, and hyper-beams etc. These metal objects tend to get curved and twisted due to various reasons like temperature changes, curly hair, and other factors which can affect their quality and performance.
The ability of a straightener to process a wide range of material thickness and widths is an important consideration in selecting the equipment for a given application. However, the potential variation in material properties makes it impossible for a single straightener to meet the needs of all applications. To compensate for the wide variations in material properties, a straightener is usually equipped with one or more back-up rollers which are positioned across the machine width. These back-up rollers help minimize stress and deflection on the work rollers.
Since the work-roll penetration required to back bend a material to an acceptable level of flatness varies depending on a combination of factors, it is difficult to establish a specific optimum roller depth setting. Once the optimum depth setting has been established for a particular material, it is critical that the work-rolls be consistently returned to this position each time the machine is run.
To ensure proper positioning of the work-rolls, most straighteners are provided with a method of calibration for the upper work-roll depth settings. This method typically consists of a scale and pointer or dial indicators that are used to calibrate the position of the work-rolls during a straightening operation. For greater accuracy, alternative methods of positioning the work-rolls may be used such as mechanical or digital indicators.
The power required to operate a straightener is determined by the maximum yield strength of the material being processed, the machine width, and the maximum line speed. The power requirement increases as the width of the material being processed becomes larger. The amount of power required to overcome the forces acting on the work-rolls during the straightening process is also affected by the material’s plastic ratio.
To increase the efficiency of a straightening system, it is advantageous to design the system with multiple sets of pressure rollers that are capable of exerting a large bending moment. This is particularly important in tube and pipe production systems, where the leading and trailing ends of the product are often bent by extrusion or rolling operations. The multiple sets of pressure rollers enable a large bending moment to be applied at the first set of pressure-rolls and lessen the linear moments at the other pairs of pressure-rollers. This results in better straightening of the leading and trailing ends of the product with lower energy usage. In addition, the use of multiple sets of pressure-rolls reduces the stress on the work-rolls and reduces the probability of their breakage. This is especially important for higher-speed, high-quality straighteners. For higher-speed applications, a special type of straightening machine is necessary which can handle the increased line speed and torque loads associated with the increased throughput requirements.