Cold forging, cold extrusion and other processes have a large amount of deformation and a great unit pressure. If the lubrication is not good, the die life will decline sharply. Low carbon steel, medium carbon steel, eutectoid steel, hypereutectoid steel, aluminum alloy (cold extrusion) large deformation, low alloy steel and bearing steel blank of cold forging, cold extrusion, drawing lubrication usually adopt blank phosphate coating (film) and metallic soap, fatty acids, graphite, disulfide key and organic polymer materials with the combination of lubrication technology, The combined lubrication process of oxalate coating (coating) and metal soap and other lubricants is adopted for cold forging and cold extrusion of stainless steel.
Phosphate and oxalate coating lubrication technology is a kind of lubrication technology that achieves excellent lubrication effect by forming reactive film as carrier and applying lubricant on the surface of blank. Carbon steel and low-carbon alloy steel mainly use phosphating to form the coating. When the filling content in the steel is more than 5%, it cannot be phosphating. Therefore, the surface treatment of stainless steel, irreduce-based alloy and Gaoming alloy uses oxalate to form the coating.
The metal is treated in a solution containing phosphate to form a metal phosphate chemical conversion film. This process is called phosphating, and the metal phosphate conversion film formed is called phosphating film.
The development of phosphating technology has a history of more than 100 years, widely used in automobile, military, electrical appliances, machinery and other industrial fields. Its main industrial use is to cover a layer of phosphating film on the surface of steel to prevent rust purpose, the second is wear resistance, friction and lubrication for use. On ChengZaiJian campaign such as gear, compressor, piston ring, special grain structure and hardness of the phosphating film can be used to have wear-resisting, less friction reduction effect, in the metal machining process, the main use of the phosphating film and its applying to other lubricant (such as metal soap) up to the lubrication function, to reduce the mold damage or improve the forming efficiency.
1. Annealing of forging blanks
The first process of blank pretreatment is low temperature annealing, which aims at reducing hardness and improving plasticity. For low carbon and medium carbon steel heating to Acl below 40C? 6O'C(generally recommended 67O 'C+15'C), after heat preservation, slow cooling. For eutectomized steel and overeutectomized steel blanks, spheroidizing annealing is used to spheroidize ferro carbide and other carbides, which are heated to 20C~30C below Acl or 2O'C above Au. 40C, after holding, isothermal cooling or slow furnace cooling.
2, alkali washing oil removal
Surface treatment includes alkali washing to remove mineral oil and animal and vegetable oil on the surface of blank and acid washing to remove rust. Before phosphating treatment, the blank surface must be treated clean to make the phosphate film firmly attached to the blank surface.
An alkaline solution for oil removal:
(1)Na()H(60? 100)g/L+ Na,C03(60~80)g/L + Na:,PO, (25? 80)g/L + Na2SiO3(10~ 15)g/L+ H2O IL
Treatment temperature 285"C, treatment time 15min? 20 min.
(2)NaOH50g/L + Na2CC).(50g/L + Na3PO430g/L + H2O IL
Treatment temperature 8O'C~1OO'C, treatment time 30min? 40 min.
Oil removal in alkaline solution is actually saponification reaction of NaOH and oil. The product is soap, must be washed with hot and cold water, otherwise it will affect the next step of pickling rust removal effect.
3, acid cleaning rust removal
Acid solution for rust removal:
(1)H2S04(120~180)g/L +NaCl(8~10)g/L+H2O IL
Chemical reactions :Fe2O3 + 3H2SO, -- Fe2(SO4),+3H2O
Treatment temperature 65 C -- 75°C, treatment time 5min? 15 min.
(2) strong HC1
The treatment temperature was room temperature and the treatment time was 5min~10mino
Chemical reaction: FezQ + 6HCl^FeCL, +3H2O
After rust removal, must be washed clean with hot and cold water, otherwise affect the next phosphating treatment effect.
4, phosphating treatment
Phosphate film is formed by phosphate and iron to produce chemical reaction groove of lubricant, the lubrication film and metal blank surface sticky With very strong, and has certain lubrication, porous phosphate film can absorb and store large amounts of the second phase (such as metallic soap), forming composite lubrication technology, thus greatly improving the lubrication effect.
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