"A complete carbon steel slitting machine consists of several key components, including Entry Coil Storage、Entry Coil ID Changeover、Slitter Tooling Changeover、Edge Trim Scrap Handling、Loop Slit Tension、Exit Coil OD Banding、Slit Coil Packaging. This article will focus on loop slit tension control in carbon steel slitting lines. KINGREAL SLITTING hopes that this in-depth analysis of these components will provide you with a more comprehensive understanding of carbon steel slitting machines."
1. Basic Concepts of Loop Slit
In metal coil production, the center of the coil is typically thicker than the edges, a design known as a "crown." During slitting in a carbon steel slitting line, the thicker center strips are wound to a larger diameter than the thinner edge strips. This phenomenon often forces operators on traditional carbon steel slitting machines to pad the thinner strips with paper or cardboard to maintain the same diameter as the thicker strips. This not only increases operational complexity and poses safety risks, but can also cause the strip to bend after cutting (called "skew"). This is because the strip must be separated at an angle and then straightened under the tension of the winding drum.
To understand this issue, KINGREAL SLITTING need to understand the physical properties of the coil. Due to the material structure, the increased thickness in the center causes the strip to have different winding diameters after cutting. This uneven winding not only affects subsequent processing but can also lead to inconsistent product quality, making subsequent processing and inspection more difficult. Therefore, how to effectively manage and control the tension during the slitting process has become a pressing issue in the industry.
2. Innovation in Ring Cutting Technology for Carbon Steel Slitting Line
To address the above issues, modern carbon steel slitting machines have introduced a combined ring pit and tension frame system. This technology is a revolutionary advancement. Ring cutting produces compact, upright coils without the use of fillers such as cardboard, thus avoiding quality issues caused by fillers.
The key to ring cutting lies in applying appropriate post-tension. Proper tension control ensures the integrity of the strip while reducing consumables and maintenance costs. Several different tension control methods have been developed, and the appropriate equipment depends primarily on the type of material being processed. For example, for softer materials, tension control requirements may not be as stringent as for harder materials. However, for high-strength steel or other hard materials, more precise tension management is required to prevent damage.
2.1 The Importance of Annular Grooves
The design of the circular grooves allows for more uniform winding of the strip after slitting. By ensuring the appropriate depth of the circular grooves, the strip tension in the carbon steel slitting line can be effectively controlled, avoiding quality issues caused by excessive or insufficient tension. Furthermore, the presence of the circular grooves reduces noise and vibration during the cutting process, improving the stability of the entire slitting machine.
3. Tension Control Methods for Carbon Steel Slitting Machine
3.1 Shim-Type Tension Frames
The shim-type tension frame is the most common type of tension control device. It applies tension to the strip using a sheet covered with felt. This design is simple and relatively inexpensive, reducing maintenance costs due to the relatively affordable felt material. A Velcro-like attachment system allows for quick replacement of felt sheets, ensuring operational flexibility. Furthermore, larger sheets evenly distribute tension, reducing the risk of damage to the strip.
In practical carbon steel slitting line applications, the shim-type tension can accommodate various material thicknesses and types. For specialized materials, operators can adjust the density and thickness of the felt to achieve optimal tension control. This flexibility has made it a standard feature on many carbon steel slitting machines.
3.2 Rotating Tension
The rotating tension is another widely used tension control method in carbon steel slitting lines. It applies tension to the strip using rollers, effectively reducing scratches and is generally more suitable for materials requiring high surface quality. This type of tension can apply tension using pneumatic cylinders or screw jacks, while braking force may come from water-cooled brakes or electric drag generators. Polyurethane rollers are suitable for dry strips, while non-woven rollers are suitable for oily strips. The new dual design not only saves space but also allows roller changes to be completed in just two minutes, significantly improving carbon steel slitting machine efficiency.
The design of the rotating tension not only focuses on applying tension but also considers how to minimize surface damage to the material. By precisely controlling the roller speed and applied pressure, scratches and deformation during the cutting process can be effectively avoided, thereby improving the quality of the final product.
3.3 Coil Leveler
In addition to the two methods mentioned above, a coil leveler is another innovative tension control solution widely used in efficient slitting machines. It stretches multiple strips after partial slitting to reduce apparent strip length variations and, therefore, the need for craters. This method is particularly effective in cutting lines that require shallow craters. However, stretching multiple strips can result in a reduction in width, a phenomenon known as "necking." Necking is more severe when deeper craters are required, and can even result in a width reduction exceeding 0.040 inches.
The use of a coil leveler allows the material to be initially adjusted and optimized before entering the slitting process, ensuring uniform and stable tension during the cutting process. The introduction of this device significantly improves the overall efficiency and product quality of the carbon steel slitting line.
4. Required Annular Pit Depth
The actual required annatal pit depth depends on two primary factors: the material length within the coil and the thickness variation between strips of varying thicknesses. A calculation formula can help operators determine the required annatal pit depth. This calculation not only improves production efficiency but also ensures product quality.
Specifically, the formula for calculating annatal pit depth typically considers the difference between the strip's outer and inner diameters, and its maximum and minimum thicknesses. Properly calculating the annatal pit depth helps maintain appropriate tension during the cutting process, avoiding damage to the strip caused by excessive or insufficient tension. By precisely controlling these parameters, operators can effectively reduce production uncertainty and improve the final product's yield rate.
As a carbon steel slitting machine manufacturer with over 20 years of experience, KINGREAL SLITTING has extensive experience in machine design and manufacturing. KINGREAL SLITTING is constantly innovating our carbon steel slitting lines through market research and visits to existing customers, aiming to meet the ever-changing needs of our customers.
