Cut To Length Lines: CTL
Cut To Length Line , commonly called CTL or Blanking Line, is very important equipment in steel industry. Steel is the backbone of modern industrial production. Global steel production has tripled over the last 50 years. Global production of crude steel was 1864 million ton in 2020. Global production of hot rolled flat products was in the range of 800 MT, which constitutes
about 43% of global steel production.
Steel is hot rolled into coil forms by very large steel manufacturing facilities spread around the world. Each facility can manufacture more than 10 million tons of hot rolled coils in a year.
Role of Steel processing Centers and Cut to length (CTL Lines).
Steel service centers play a vital role in bringing the steel products to the consumers. Most consumers require steel in the form of flat sheets and plates for making sheet rolled products, welded sheet industrial and household products like washing machines, refrigerators, storage
cabinets, steel drums and manufacturing steam boilers, ships, machinery, vessels and countless products for household consumption and industry.
Cut To Length Line: CTL Lines or blanking Line:
The large and heavy coils weighing up to 40 MT are to be unwound, straightened, flattened, and cut in length to the precise sizes which industry require, stack and bundle them. The process is performed by Cut to Length Lines. CTL lines can be divided into two broad categories.
Continuous CTL – cut to Length Line
The strip is fed out of the teel coil and passed through coil straightener and a leveler. To improve flatness, especially in case of thinner cold rolled steel, the strip is fed through a second leveler or a stretch leveler. The strip is dropped into a looping pit which acts like an accumulator. Looping pit helps in continuous flow of material through the leveler avoiding its marks when continuous material flow is interrupted while cutting the strip at shear. Through a feed cum measuring roll which feeds the exact length of at end of the looping pit, the strip is fed to a shear. The shear can be stationary or flying type. The continuous CTL is preferred when lighter gauges are cut to
length generally less than 3mm thick.
Stop-Go Cut to length CTL
Stop-Go Cut to Length Lines is less expensive than continuous CTL’s and are designed to cut the HR Strips from 4 mm to 20 mm. Its equipment layout is like that of continuous CTL except that it does not have looping pit and an additional equipment ” Dumble Rolls” is added before the leveler. The Dumble Rolls have concave – convex shape and are used to help leveler for strip thicknesses above 8 mm. These CTL are ideal for heavy-gauge applications. These lines are not suitable for thinner gauges especially for cold rolled strips materials because visible roll marks can appear where material stops in the leveler. A flying shear can be installed to increase production especially in the case of heavy gauge. With better controls, the speeds can be synchronized to make these lines high productive continuous lines.
Electrical Systems of Cut to length Lines “CTL” AC motors & Variable Voltage Variable Frequency “VVVF” along with PLC are used in modern Cut to length lines to perform all essential functions like speed adjustment, speed control, speed synchronization, Cut to Length settings, manual and automatic feed, continuous cutting. precise length control, interlocks and alarms etc. All operations are centrally controlled on the console, which is convenient, safe and reliable. Latest state of the arts multiple AC regenerative drives of ABB ACS 880 modules or of Siemens S 120 drives are used for electrical controls of Cut to length Lines ” CTL”