What are the main components of a tube mill?

A tube mill is not a single machine but a complex assembly of interconnected components that work in unison to produce welded steel tube. Each part has a distinct and critical function in the continuous production process. Shijiazhuang Faith Machinery Co., Ltd. integrates these key components to create a cohesive and efficient manufacturing system.

1. Uncoiler and Payoff Reel
This is the starting point of the mill. It is a motorized unit that holds the master coil of steel strip. It controls the unspooling of the strip, often with a braking mechanism to maintain back tension, which is crucial for a stable material feed into the mill.

2. Strip Feeding and Leveling Station
This station typically includes entry pinch rolls that pull the strip from the uncoiler. It also houses a precision leveler, which is a machine with a set of small-diameter work rolls that bend the strip in alternating directions to remove any coil set, crossbow, or twists. A flat strip is fundamental to achieving a uniform tube shape and a consistent weld.

3. Forming Section
This is the core of the tube mill where the shaping occurs. It consists of a series of individual roll stands mounted in a cascade. Each stand contains two or more contoured rolls made from hardened steel. The rolls in the first few stands start the edge forming, and each subsequent stand progressively bends the strip until it becomes a complete cylinder. The design of the roll sequence is a precise engineering calculation.

4. Welding Station
This station is responsible for creating the longitudinal seam. Its key elements include:

• High-Frequency Welder: The power source that generates the high-frequency current.

• Impedance/Contact System: Either an induction coil or contact shoes that transfer the HF current to the strip edges.

• Squeeze Roll Unit: A set of two rolls that apply precise pressure to forge the heated edges of the steel together, completing the weld.

5. Flash Trimming Unit
Located immediately after the welder, this unit contains carbide-tipped tools or blades that shave off the excess weld material (flash) from both the inside and outside of the tube. This is necessary for a smooth surface finish and to prepare the tube for subsequent processes like galvanizing.

6. Sizing Section
Similar in appearance to the forming section, the sizing section is comprised of several stands of rolls. However, the function here is different. These rolls are calibrated to cold-work the welded tube to its final, exact outer diameter and to ensure perfect roundness and straightness along its entire length.

7. Flying Cutoff Saw
This is a critical component for finishing. It is a saw mounted on a moving carriage that travels alongside the tube at the same speed. When a predetermined length is reached, the saw clamps onto the tube and makes a clean, square cut. It then returns to its starting position to repeat the cycle without stopping the production line.

8. Control System
A centralized Programmable Logic Controller (PLC) and Human-Machine Interface (HMI) panel act as the brain of the tube mill. It allows operators to monitor and control all parameters, including line speed, welding power, and cut length, ensuring repeatability and facilitating quick changeovers between different tube sizes.

9. Run-out and Handling Equipment
This includes the conveyor tables, straighteners, and automatic stacking systems that receive the cut-to-length tubes and prepare them for bundling, inspection, and shipment. The robust integration of all these components by Shijiazhuang Faith Machinery Co., Ltd. ensures a reliable and productive tube manufacturing system.