When the rectangular aluminum square tube is rough and medium rolled, large deformation heat will be generated in the deformation zone. The cooling effect of the rolling oil is important for maintaining the roll shape and stable rolling. If the injection pressure and flow rate of the cooling oil are insufficient, the cooling effect will be affected. However, in the actual production process, the pressure and flow rate of the cooling oil are monitored. Generally, there will be no problems. In many cases, mechanical failures such as the filling of the nozzle of the rolling oil or the falling or rupture of the tubing connecting the nozzles cause the actual flow and pressure of the coolant injected in the working area to be insufficient, and the cooling effect is greatly reduced. Make the rectangular aluminum square tube in the corresponding area high, and the plate shape is loose and bulging. Therefore, the spray effect of the nozzle should be checked regularly, once the bulging phenomenon occurs. Stop the machine in time to check the working condition of the spray: This is one of the measures to prevent the drumming: the so-called plate shape parameter refers to the set target plate shape curve: the typical target plate is a parabola, that is, the secondary line of tightness and loose edges. , If necessary, you can make corrections as needed. The shape parameter value should be determined according to the online export shape and the next-order production situation. If the setting of the shape parameter of the pass causes the material to be convex, and the transition with the shape parameter of the next pass is inappropriate.
The heat of deformation in the middle of the rectangular aluminum square tube is relatively large, and the heat of the rectangular aluminum square tube is relatively large. The shape of the middle part of the material is loose, and the phenomenon of middle bulging may occur. Therefore, the setting of the plate shape parameters must ensure that the exit plate shape is flat and the middle part is slightly tighter than the sides, that is, to maintain a certain middle height, and a reasonable transition of the plate shape parameters between passes must be considered. The actual rolling deformation zone of the rectangular aluminum square tube is mostly in a mixed lubrication state. The boundary film ruptures of the micro convex body in the deformation zone due to the excessively high contact pressure, resulting in direct metal contact. At this time, a part of the pressure in the deformation zone is borne by the fluid. In the other part, the thickness of the oil film in the forming area is borne by the contacting micro-protrusions and decreases with the increase of the reduction rate. at the same time. In the high-speed rolling state, a large amount of deformation heat will cause the deformation temperature to rise, the thermal movement of the lubricating oil molecules will increase, and the directional adsorption will decrease. The strength of the oil film decreases, and even the oil film ruptures. The metal surface begins to scratch, and the absolute temperature at this time is called the rolling oil critical failure temperature Τ. If the local temperature of the deformation zone exceeds Τ, the boundary will rupture, leading to direct contact with the metal surface, which will increase the friction factor and wear, and the temperature of the deformation zone will also rise, which further promotes the rupture of the oil film. The percentage M of the area where the metal surface is in direct contact. It will increase rapidly, and the heat will accumulate rapidly in this place, causing the material surface at the outlet to become slab and bulge.
Process lubricating oil has different critical failure temperature T, and its temperature is related to the performance of lubricating base oil and the ratio of additives. The audible membrane formed by the additive molecules is stronger and can not break at higher temperatures, but the strength of the oil film and the critical failure temperature T formed by the additives of different proportions are different. The reasonable preparation of rolling oil is very important to enhance the strength of the oil film and increase the rolling speed. Generally, the preparation of rolling oil is based on the principles of high oil film strength, low viscosity, and low oil stain tendency. First, select the appropriate base oil and the appropriate proportion of additives, and at the same time, it should be adjusted according to the actual production conditions of each factory. Strictly control the various performance parameters of the rolling oil during the preparation process.
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