Slitting is a shearing process in which the width of an original, or master, coil is reduced into multiple narrower coils. A wide range of materials and thicknesses can be slit, ranging from thin foils to thick plate. Normally, the outside edges of the master coil are trimmed. This creates an accurate register cut, providing a reference point from which the other cuts can be made.
Slitting is performed on slitting lines which consist of four basic devices:
• The uncoiler, or pay-off reel, which tightly grips the master coil on its inside diameter using an expandable mandrel. The coil is fed into the slitter by either rotating or jogging the mandrel.
• The slitter, which consists of two parallel arbors mounted with rotary cutting knives. These knives partially penetrate the coil stock causing a crack or fracture on both sides of the stock, separating the material.
• A tensioning device, which is placed between the slitter and the subsequent recoiler. A tensioning device is needed because the master coil is crowned or larger in diameter in the center of its width than at the edges. Without a tensioning device the slit material from the center of the master coil would take up more quickly while the outboard strips would hang loosely.
• The recoiler, which takes up the slit coils on a driven, expandable mandrel. The recoiler mandrel is fitted with separator discs which prevent interleaving of the narrower coil widths.
Other slitting line equipment can include:
• Scrap disposal machinery
• Edge conditioning equipment
• Packaging devices
There are two basic types of slitting lines:
• The pull-through slitting line
• The loop slitting line
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