affect the lubrication performance factors (1) the influence of rolling temperature: no lubrication conditions, when the rolling temperature rose from 900 ℃ to 1200 ℃ units of friction decreased from 320MPa to 40MPa. The reason is due to partial melting of the metal deformation resistance reduction and oxide scale. (2) the influence of the lubricant quantity: When the rolling temperature of 1200 ° C, the number of lubricants never to 30g/m2, the unit friction from 30MPa to 6MPa. (3) the impact of the number of oxide scale: in the rolling temperature of 1200 ° C and non-lubricated conditions, the oxide scale the amount of from 0 to 30g/m2, friction increased from 40MPa to 87MPa; when the temperature is lowered to 900 ° C, with or without lubrication, the friction increases as the temperature is the softening point of some of the oxide scale. (4) the impact of the the mandrel original temperature: in the capillary into the mill with cold mandrel rolling moment, the melting of the lubricant contact with the cold mandrelWorld Steel Pipe , immediately cooled and crystallized, the cause of it with the mandrel metal clenched, the friction coefficient increases. Mandrel temperature, mandrel grip force decreased gradually to a stable value. Therefore, the mandrel is necessary to preheat to 250 ~ 300 ℃.
The main purpose of the whole process lubrication is able to successfully pull out the mandrel, at the same time can make off the stick of the motor load is reduced by about 50% to improve the steel pipe inner surface quality. The main lubricant for the suspension of 20% sodium tripolyphosphate.
use of anti-friction agent to reduce the hot-rolled steel roll with rolling friction technology. The process of hot-rolled steel is a solid billet by the piercing mill, pipe mill hot-rolled into the waste pipe, and then given (less) diameter made of finished pipe. Deformation is conducted in 1250 to 850 ° C under high temperature, large deformation, the local wear larvae L head and short head of the pipe mill to withstand the friction of a long time, and the deformation process of a large number of new students face in close contact with the head surface in the deformation process is fully enclosed in the blank of high temperature, the friction conditions are relatively poor. Therefore, hot-rolled steel, used in process lubricants should be able to ensure the steel pipe inner and outer surfaces of good quality, easily from the capillary with the head or the mandrel, non-corrosive steel pipes and tools, can reduce the equipment load, apply the operation to easy mechanization, resource-rich and non-toxic smoke-free and so on. Early to use the technology lubricating the pipe rolling mill is cast into the salt into the capillary. Process lubricants not only used in the pipe mill wear larvae L machine are the machine, continuous pipe mill, is also gradually be applied to the cycle-type pipe rolling mill.
automatic rolling process lubrication short head rolling, lubrication head with capillary contact deformation zone, special equipment for the powder lubricant injected into the capillary, the capillary inner wall of the spray within a plunger and head to the orientation between the head and head, and then immediately into the deformation zone. The use of lubricants can increase the immediate life, improve the surface quality of steel tube, to increase the elongation factor. The lubricant used is the phosphate or graphite lubricant.
several typical steel process lubricants (1) of graphite and a variety of mineral oil lubricant, mineral oil medium, lubricant is graphite. However, in the course of the burning of fossil oil to the metal surface by carbon, but also cause environmental pollution; graphite loss of wear resistance at high temperatures. Therefore, this type of lubricant will gradually be eliminated. (2) graphite + salt lubricant, eliminating the pollution of mineral oil, greatly reducing the flue gas of the workshop, and also significantly reduce the off-core machine load. (3) salts, lubricants, is a smoke-free lubrication is more mature chloride and phosphate mainly in contact with the surface of the formation of a layer of phosphide or chloride film to prevent the adhesion of the metal. When the lubricant in the molten state to form a semi-liquid friction conditions, thereby reducing the friction coefficient, and in the case of thin film rupture, can quickly re-covering layer of liquid lubricating film. Therefore, this is the most reliable and most effective lubricant.
themandrel mill lubrication capillary and long mandrel in the ring deformation of the region more than one roll rolling, lubrication long mandrel and the inner wall of the capillary into the deformation zone mainly composed of graphite lubricant to prevent bonding of the capillary and mandrel. The lubricant is applied before the mandrel into the capillary, the liquid lubricant spray injection system on a mandrel and cured film World Pipe network informed. There will be after the exit of the mandrel directly immersed in a tank equipped with a liquid lubricant dipped in a layer of lubricant, lubricant stick covered mandrel waste heat drying. The lubrication process is key to making graphite evenly and firmly glued to the mandrel surface. The tripolyphosphate lubricant is also fairly good results. The use of lubricants, the coefficient of friction of the contact surface between the metal and the mandrel can be reduced 50% to 33%, an extension of the steel increases, reducing the metal may be too full of pass, reduce waste, but also the main motor energy consumption reduced by 15% to 20%, and poor lateral wall thickness along the length of steel reduced by 18%, longitudinal differential wall thickness reduced by 6% to lo%, 0.5 ~ l The times to improve the life of the roll, but also to the mandrel surface temperature is reduced, thereby reducing the mandrel wear and improve the quality of steel pipe inner surface.
punch perforation of process lubrication, billet phase for Piercing Plug spiral forward and produce axial and tangential slip. Head to produce 30 to 50 ° C temperature rise in the strong friction and lubrication, therefore, must be in the top head. Lubrication methods: (1) head surface oxide film at high temperature lubricant; (2) water-cooled head, by the piston pump to a pressure of 0.8 ~ 1.2MPa lubricating fluid (or water) transmission to the punch head lubrication; (3) apply lubricant to the top of his head, and heating and drying. Stainless steel perforated molybdenum-based head and the top head coated with glass powder for lubrication. As a result of lubrication, can wear the sub-L 10% reduction in lubrication to improve the metal bite into, bite into the time 10%, also adds a product rate of folding (see inside and outside the fold) reduced by 50%, the steel tube surface 90% of the uneven wall thickness reduced by 80%, and head of life and surface quality improved from 50% to 100%. More effective lubricant is l0% salt 25% hydrated lime suspension.
Hot-rolled steel processing lubrication (technological lubrication in hot rolling of steel tube and pipe)