Для начала, roll wear limits product quality and roll service life in universal rolling production. По этой причине, this study uses on-site data and classic wear theories. Тем временем, it summarizes roll wear mechanisms and uneven wear distribution rules. Кроме, it analyzes key influencing factors in hot rolling. Более того, it also provides practical optimization and maintenance methods. В конечном счете, the results guide roll selection, cycle management and stable section steel production.
1. Введение
Прежде всего, section steel rolling adopts special pass rolling technology. Как результат, it produces complex three-dimensional metal deformation. In comparison, its friction and contact conditions are more complex than flat rolling.
Кроме того, roll wear accumulates continuously during mass production. Worse still, serious uneven wear causes dimensional deviation and surface defects. Более того, it also leads to unstable rolling states. Соответственно, mastering roll wear laws helps reduce roll consumption and improve production stability.
2. Main Wear Mechanisms of Universal Mill Rolls
To begin with, workers evaluate roll conditions by cumulative steel passing tonnage. Во время горячей прокатки, continuous sliding exists between hot blanks and cooled roll surfaces. Тем временем, forward slip and backward slip exist in every rolling pass.
Вообще говоря, metal wear has seven basic types. Конкретно, common forms include adhesive wear, corrosive wear, fatigue wear and abrasive wear. Фактически, actual roll wear comes from multiple coupled mechanisms instead of a single cause.
В частности, rolling load, speed and cooling conditions determine the dominant wear type. Once working conditions shift, the main wear mechanism will change and accelerate roll damage.
С одной стороны, hot rolling forms an oxidation environment with high temperature and cooling water. С другой стороны, the oxide layer weakens surface bonding strength. Следовательно, micro peeling and particle loss often occur on roll surfaces.
Apart from that, cyclic load and temperature fluctuation generate contact fatigue damage. Самое главное, adhesive wear and corrosive wear dominate section steel rolling. Тем временем, fatigue wear plays an auxiliary acceleration role.
Суммируя, roll wear capacity refers to maximum radial wear after fixed rolling tonnage. For reference, the Archard wear model supports quantitative analysis. Поэтому, wear volume increases with contact load and decreases with surface hardness.
3. Uneven Wear Distribution Law of Roll Passes
From long-term field detection, stable uneven wear features appear on section steel roll passes.
Прежде всего, wear degree rises gradually from pass side walls to inner corners. По этой причине, pass corners always form the maximum wear area. Тем временем, wear volume drops slowly from pass bottom edges to the center.
Общий, pass bottom wear is heavier than side wall wear. Кроме, the bottom surface also has better wear uniformity than side walls. Even though different rolling tonnages cause minor value differences, they never change the fixed uneven wear trend.
4. Multi-Factor Cause Analysis of Uneven Pass Wear
4.1 Differential Slip Causes Unbalanced Friction
Первый, special-shaped workpieces contact roll passes at different times. Таким образом, slip states vary greatly at the rolling outlet.
Noticeably, pass bottom corners have the smallest roll diameter and lowest linear speed. Соответственно, they produce the largest forward slip. Gradually, forward slip decreases with the rising roll diameter toward the pass center.
When roll speed matches workpiece speed, slip value becomes zero. Наоборот, larger roll diameters generate backward slip. As a consequence, mixed slip states create uneven friction distribution. Естественно, corners and bottom areas suffer concentrated wear.
4.2 Chilled Layer Loss Causes Uneven Hardness
Изначально, new rolls receive integral heat treatment. Следовательно, they form a 50–60 mm high-hardness chilled layer. На этом этапе, new passes have stable hardness and good wear resistance.
Тем не менее, repeated turning and grinding remove partial chilled layers. Впоследствии, some pass areas enter low-hardness transition layers. Одновременно, high rolling temperature changes surface metallographic structures.
Over long-term operation, local hardness differences keep expanding. По очереди, different pass positions show inconsistent wear resistance. Eventually, obvious uneven wear appears on roll passes.
4.3 Unbalanced Temperature Changes Deformation Resistance
Mathematically, workpiece deformation resistance follows a negative exponential temperature relationship: K=Me⁻ᵐT. Проще говоря, lower temperature brings higher deformation resistance and larger rolling load.
На практике, section steel blanks have unbalanced temperature distribution. Конкретно, web temperature is higher than flange temperature. Likewise, flange root temperature is higher than flange end temperature.
По этой причине, low-temperature flange areas bear greater friction and pressure. Соответственно, their matching pass positions wear faster. Evidently, temperature difference is a key cause of uneven pass wear.
4.4 3D Deformation Triggers Unstable Rolling Load
By definition, section steel rolling belongs to typical three-dimensional plastic deformation. As a matter of fact, web and flange have different reduction rates.
С одной стороны, large-deformation zones are restricted by small-deformation zones. С другой стороны, internal tension and compression change original metal flow rules. Even tiny reduction differences cause obvious rolling force fluctuation.
Due to unbalanced load distribution, each pass position bears different friction levels. In effect, this condition produces diversified wear rates on the whole pass surface.
5. Process Optimization and Scientific Maintenance Countermeasures
Based on the above wear mechanisms, this part provides targeted improvements. Broadly, it covers rolling parameters, roll processing and temperature control.
5.1 Optimize Rolling Parameters
В эксплуатации, adjust web and flange reduction ratios reasonably. Таким образом, metal extension and asynchronous slip can stay balanced. Как результат, uniform friction distribution reduces concentrated wear on corners and bottoms.
5.2 Standardize Turning and Grinding
First and foremost, control single turning depth to protect chilled layers. Periodically, detect pass hardness regularly. Кроме того, match high-hardness zones with high-load flange rolling areas.
Дальше, apply local strengthening on vulnerable corners and bottoms. With this method, local wear resistance can be greatly improved.
5.3 Improve Blank Heating Uniformity
To solve temperature gradient issues, optimize furnace temperature control and preheating processes. If the web-flange temperature gap shrinks, deformation resistance will stay stable. Thereby, rolling load and friction distribute evenly.
5.4 Update Roll Replacement Standards
When evaluating roll health, judge roll status by steel tonnage and actual radial wear. Throughout daily production, strengthen inspection on weak pass positions. Before defects or vibration arise, replace or regrind rolls in advance.
6. Заключение
Первый, universal mill rolls show typical uneven wear features. Конкретно, pass corners have the most serious wear, and pass bottom wear is heavier than side wall wear.
Второй, asynchronous metal slip and complex 3D deformation form the core cause of uneven pass wear. Without eliminating these two factors, uneven wear cannot be controlled fundamentally.
Третий, chilled layer attenuation, unbalanced hardness and uneven workpiece temperature jointly worsen wear differences. Altogether, these three auxiliary factors amplify local material loss on roll passes.
Четвертый, parameter optimization, standardized grinding and precise temperature control effectively suppress concentrated wear. In the long run, these measures stabilize product quality and cut total roll consumption.
