Chapter 4: Sheet Metal Forming 4.5 Forming Operation Shafizan Bt. Shariffuddin School of Manufacturing Engineering UniMAP

Slip-roll Forming Machine All forming machines have the same general function; namely that of forming sheet metal into cylindrical shapes of various diameter.

Figure 1. Slip-roll forming machine showing the upper roll release.

Slip-roll forming machine consists of a base, three rolls and the housing. The operation handle turns the two front rolls by means of gears enclosed in the housing. The two front rolls act as feeding or gripping rolls, while the rear roll gives the proper curvature to the work. The grooves in the front and rear rolls are used for forming objects with wired edges. The release roll allows the work to be removed by opening the upper roll. See Figure 2 and 3.

Figure 2. Forming a cylinder with a wired edge. Figure 3. How cylinder is formed.

Forming Cylinder Cylindrical shapes are formed by inserting the work between the two front rolls. See Figure 3 and 4. The front rolls are adjusted by turning the screws to allow just enough clearance between the rolls to avoid smashing the locks flat so that they cannot hook together. The curvature of the cylinder is controlled by raising the rear roll for a smaller radius or lowering it for a larger radius.

Figure 4. Starting and forming cylindrical shapes.

Forming Cylinder with Wired Edges When forming pails, cans, and other round articles with wired edges, the wire should extend past the metal slightly at one end. The wire at the other end should be slightly shorter that the metal to form a pocket to receive the wire from the other end. A short piece of wire should be inserted to prevent the pocket from being smashed.

Continue to form the cylinder to the curvature desired until the ends meet. Insert the end of the wire into the pocket of the wired edge where the short piece of wire has been removed, and continue until the seam has passed through the rolls. See Figure 3.