Research on Active Pressurized Forced Lubrication Deep Drawing Process and Evaluation of Lubrication Effect
Abstract Friction and lubrication are important parameters that affect the quality of sheet metal forming, excellent lubrication condition and less harmful friction can reduce local thinning of sheet metal, delay fracture and improve surface quality. Aiming at the poor friction conditions and difficult lubrication in the flange area during deep drawing, an active pressurized forced lubrication deep drawing(FLDD) process was proposed in this paper. A hydraulic system was employed to flush high pressure lubricating oil into the contact gap between die and sheet in the flange area. The high pressure hydrostatic oil film in the contact gap can reduce the real contact area and improve the lubrication condition effectively. The equipment is simple, the cost is low, and lubricating oil pressure can be measured and controlled. Under the conditions of 20kN, 35kN and 50kN blank holder force(BHF), FLDD test of box parts was carried out with 5MPa and 9MPa pressure water-based lubricating oil. The horizontal comparison experiment was conducted with common lubricating media such as polyethylene film(PE film), high-purity molybdenum disulfide particles, vegetable oil and water-based lubricating oil under the same process conditions. Lubrication effect was evaluated by obtaining test data. Test results illustrated that the lubrication effect of high-purity molybdenum disulfide particles was the best and that of vegetable oil was the worst. The lubrication effect of water-based mineral lubricant was significantly improved after pressurization. The maximum forming height was increased by 17.97%, the maximum forming force was reduced by 8.9%, the maximum wall thickness thinning rate was reduced by 7%, and the lubrication effect of 9MPa pressure was superior to that of 5MPa. Although there is still a certain shortfall with special lubricating media such as high-purity molybdenum disulfide, FLDD process has definite application value in improving production environment, pollution control and automatic production.
