Modern steel rolling production demands higher rigidity and dimensional accuracy for long steel products. Бар, wire rod and section steel production lines widely adopt the short stress line rolling mill for long steel production. This professional rolling equipment features high rigidity, stable precision and fast roll replacement. It also delivers simple adjustment and reliable operation. По этой причине, it replaces traditional housing rolling mills in most long steel workshops. Operators and maintenance staff can stabilize production quality by mastering its structure, working principle and adjustment methods. This article systematically explains the core characteristics and technical mechanisms of the short stress line rolling mill.
1. Basic Definition of Short Stress Line Rolling Mill
The short stress line rolling mill gains its name from its shortened internal stress loop. A stress loop refers to the closed force line formed by all loaded components under rolling pressure. Mechanical deformation is proportional to the stress path length. Поэтому, a shorter stress loop effectively reduces elastic deformation during rolling. It also improves overall mill rigidity and finished steel precision. Суммируя, the short stress line rolling mill achieves high-rigidity and high-precision rolling through optimized stress transmission design.
2. Overall Structure and Core Components
The rolling mill follows a clear power transmission sequence. Its complete transmission chain includes clutch, handwheel, gear ring, gear sleeve, support seat, bearing seat and upper and lower work rolls. Each component coordinates closely to complete steady rolling movement. According to functional division, the whole mill contains three core device groups.
2.1 Transmission Device
The transmission device consists of drive gears, worm and worm gear sets, manual handwheels, driving motors and transmission shafts. It transfers stable power input to the roll system. This device ensures synchronous and consistent rolling movement during mass production.
2.2 Screw-Down Roll Gap Adjustment Device
This device includes spherical washers, balance springs, lead screws, balance nuts and screw-down nuts. Workers rely on this assembly to adjust roll gap height. It directly controls the dimensional tolerance of finished long steel products.
2.3 Axial Adjustment Device
The axial adjustment unit covers gear rings, gear sleeves, end covers, thrust bearings, bearing seats and auxiliary parts. It fixes roll axial position and eliminates excessive axial play. It greatly improves rolling stability and guide service life.
3. Advantages and Disadvantages Versus Traditional Housing Mills
The short stress line rolling mill shows obvious technical superiority compared with conventional housing rolling mills. Тем временем, it retains certain structural limitations in actual operation.
3.1 Core Technical Advantages
Первый, it builds higher rigidity with shorter stress loops. It supports negative deviation rolling and saves raw material costs effectively. Второй, the double-threaded upright design realizes symmetrical centering adjustment. It keeps the rolling centerline fixed and avoids rolling accidents such as roll wrapping and steel bending. Третий, the mill provides flexible axial adjustment with tiny axial clearance. Четвертый, the built-in balance spring offers constant balancing force with compact internal layout. Пятый, the whole roll system allows offline pre-adjustment. It shortens on-site roll changing time and improves steel yield rate. Sixth, self-aligning bearing seats evenly distribute load on four-row cylindrical bearings. It significantly extends bearing service life.
3.2 Structural Disadvantages
The axial fixing structure interferes with the self-aligning mechanism of bearing seats. It reduces axial rigidity and easily causes roll axial shifting. Кроме того, the screw-down nut bears heavy rolling load. Its replacement process is extremely complicated. Maintenance teams must disassemble the entire roll set and worm gear box for replacement. This defect increases daily maintenance workload.
4. Radial Roll Gap Adjustment Principle
Radial adjustment refers to vertical roll gap calibration. It includes old manual structures and new optimized mechanical structures.
4.1 Radial Adjustment of Traditional Old-Type Mills
Old short stress line mills adopt pure manual operation. Workers rotate handwheels to drive worm and worm gear movement. The upright column rotates without vertical displacement. The matched screw-down nut moves up and down under thread restriction. It presses the spherical washer and pushes the bearing seat. Окончательно, the work roll moves vertically to complete roll gap setting.
4.2 Radial Adjustment of Modern New-Type Mills
New-generation mills use optimized worm and worm gear transmission. Each worm gear connects with one upright column through a flat key. The worm shaft installs inner and outer tooth clutches. The structure supports synchronous double-side pressing and independent single-side fine tuning. The spline jaw clutch transmits large torque and meshes smoothly. Более того, the worm gear mechanism realizes self-locking after adjustment. It guarantees high precision and reliable locking performance.
5. Synchronous Spring Balance System Principle
The internal balance structure determines mill rigidity and adjustment accuracy. The vertical column installs multiple functional parts from top to bottom.
5.1 Internal Component Arrangement
The standard assembly sequence includes synchronous spring, balance nut, screw-down nut and spherical washer. These components form a complete force balance system inside the bearing seat.
5.2 Force Balance Mechanism
The balance nut fits tightly with the column thread. The synchronous spring provides upward balancing force to lift the entire upper roll system. The force transfers from the bearing seat to the spherical washer. It eliminates thread clearance between the screw and nut. This structure improves overall mill rigidity and rolling precision effectively.
6. Vibration Reduction and Noise Reduction Design
Modern short stress line rolling mills replace traditional balance springs with elastic dampers. Elastic dampers absorb impact vibration during steel biting. They reduce equipment noise and stabilize rolling rhythm. Тем временем, the new design cancels hydraulic cylinders completely. It removes hidden troubles of hydraulic oil leakage. Однако, elastic dampers age gradually under long-term alternating load. Staff must inspect and replace damaged parts regularly to maintain damping performance.
7. Rolling Force Transmission Path
Clear force transmission analysis helps fault diagnosis and structural optimization. The standard rolling force path follows fixed order: work roll → rolling bearing → bearing seat → spherical washer → screw-down nut → vertical column. This stable force loop ensures uniform structural stress. It also provides accurate theoretical basis for equipment maintenance and strength design.
8. Axial Fixing and Adjustment Principle
Axial control restricts roll shifting while allowing flexible bearing seat self-alignment. It balances rigidity and adaptive deformation performance.
8.1 Axial Fixing Structure
Old mills rely on rectangular positioning blocks for axial limitation. New mills cancel rectangular blocks. They adopt close cooperation between axial fixing sleeves and bearing seats. The tiny assembly gap effectively limits axial movement of roll systems.
8.2 Axial Adjustment Method
Workers adjust the axial position by turning the worm shaft. The worm drives the end gear ring to rotate and realize fine axial calibration. Other structural designs remain consistent with traditional models.
9. Self-Aligning Principle of Roll Bearing Seats
Work rolls produce slight bending deformation under rolling load. Multiple spherical washer groups help bearing seats swing adaptively. The swing movement reduces bearing partial load and prevents bearing burnout. Spherical structures under screw-down nuts and between bearing seats provide multi-point floating adjustment. Although different spherical centers cannot eliminate deformation completely, they greatly relieve adverse effects of roll bending and extend bearing service life.
10. Assembly Technology for Horizontal Roll Installation
Workers place four equal-height gaskets between bearing seats and the mill base during assembly. The gaskets ensure consistent height of all screw-down nuts. This simple and reliable process keeps both ends of the work roll horizontal. It effectively guarantees overall assembly precision and rolling flatness.
11. Disassembly and Assembly Key Points
Maintenance personnel must follow standardized steps during mill overhaul. Первый, disconnect the transmission shaft from the work roll. Второй, disassemble the support seat and related components. The sequence of separating transmission parts first protects precision components from collision damage. It also improves operation efficiency and maintenance safety.
Заключение
The short stress line rolling mill for long steel production serves as core equipment for bar, wire rod and section steel workshops. Its high rigidity, stable precision and fast roll change bring remarkable economic benefits. Skilled mastery of structural composition, radial and axial adjustment principles, self-aligning mechanism and assembly standards helps operators maximize equipment performance. With continuous upgrading of rolling technology, the short stress line rolling mill will maintain irreplaceable advantages in modern long steel production lines.