What is Roll Forming_Roll forming machine--Nitchen Equipments Group|metal forming machine|metal roofing machine|guardrail machine|steel deck

Roll Forming

Roll forming, also spelled rollforming, is a continuous bending operation in which a long strip of metal (typically coiled steel) is passed through consecutive sets of rolls, or stands, each performing only an incremental part of the bend, until the desired cross-section profile is obtained. Roll forming is ideal for producing parts with long lengths or in large quantities.

Roll Forming Stand

roll forming process.

Roll forming machines are now being produced so that for similar products such as stud and track profiles, a new set of profile rolls is not required. This is achieved by the mill being split along its center line and the web, flange and ear sizes are set using a control panel which moves the mill rafts centrally to increase or decrease the aforementioned features.

Roll forming lines can be set up with multiple configurations to punch and cut off parts in a continuous operation. For cutting a part to length, the lines can be set up to use a pre-cut die where a single blank runs through the roll mill, or a post-cut die where the profile is cutoff after the roll forming process. Features may be added in a hole, notch, embossment, or shear form by punching in a roll forming line. These part features can be done in a pre-punch application (before roll forming starts), in a mid-line punching application (in the middle of a roll forming line/process) or a post punching application (after roll forming is done). Some roll forming lines incorporate only one of the above punch or cutoff applications, others incorporate some or all of the applications in one line.

Roll Forming Process

The process of roll forming is one of the simpler manufacturing processes. It begins with a large spool of metal strips, usually between 1 in. and 20in. in width, and 0.004 in. and 0.125 in. thick. This is held by a device called a dispenser. The metal strip is then unrolled and fed into a machine starting with the stock feeder which is connected to the cutoff attachment. After the cutoff attachment, the metal strip is fed into the forming rolls. These mating die-set rolls are constructed to form the desired shape in stages sequentially by means of various shaped rolls. The layout of these rolls can be flower shaped as mentioned previously, progressive upper/lower rolls, side rolls, or as overhung spindle rolls. These different roll configurations are used according to the job that needs to be done.

Roll Forming Rates

The production rate depends greatly on the material thickness and the bend radius, it is also affected by the number of stations or steps required. For bend radii of 50 times the material thickness of a low carbon steel .07 in thick can range from 85 feet per minute through eight stations to 55 feet per minute through 12 stations or 50 feet per minute through 22 stations.
The time taken for one product to take shape can be represented by a simple function. The function is as follows: Formingtime = L + n(d) / V where V is the velocity of strip through rolls (fpm), L is the length of the piece being rolled (ft), d is the distance between forming stands (ft), and n is the number of forming stands.

In General roll forming lines can run from 5 feet per minute to 500 + depending on the application. In some cases the limiting factor is the punching or cutoff applications.