Roll forming refers to the use of rotating rolls with a smooth surface or a certain shape to calender raw materials to obtain a certain shape product. In the process of food processing, many materials need to be rolled, such as pressing in the production of biscuits, noodles in the production of confectionery, pressing and forming in the production of noodles and instant noodles, etc.
Different products have different technological requirements for the rolling operation. In the production of biscuits, the purpose of rolling is to make the dough form a dough with uniform thickness, smooth surface, fine texture, moderate cohesion and plasticity; in the process of candy processing, the purpose of rolling is to make the massecuite have a certain shape The sugar bars of the specifications can eliminate the bubbles in the sugar bars to facilitate the operation, and the formed sugar bars are quantitatively accurate.
During the rolling operation, the material directly contacts the roll and deforms. The thickness of the material before rolling is ho, and the thickness of the material after rolling is called the absolute reduction, and a is called the contact angle or feeding angle. During the rolling process, the inside of the material layer presents different flow states due to different pressure directions. In the initial stage of rolling in the front section of the roll work area, the radial pressure of the roll on the material layer is relatively small. Due to friction, the surface speed of the material layer is close to the surface speed of the roll, while the internal flow is opposite to the surface of the material layer. The value is even greater than the value of the forward movement speed of the material surface. After entering the rolling pitch, the pressure of the roll increases sharply. The pressure inside the material layer is close to the pressure on the surface, and the relative movement between the surface and the inside of the material layer decreases, and the overall movement speed increases. The pressure of the roll causes the material to flow forward relative to the surface. The forward movement speed of the center part of the material layer is higher than the surface speed of the roll, and the radial pressure of the roll drops rapidly.