| The level of precision forging reflects the development of a country’s industrial technology and the strength of its comprehensive national strength.Cold forging is a forging technology with high precision and widespread application,but it is also relatively difficult.In the pre-treatment stage,phosphorus saponification is generally needed to form phosphorus saponification film on the workpiece surface to achieve the purpose of lubrication and rust prevention.However,phosphorus saponification will produce a large amount of industrial hazardous waste,seriously pollute the environment,increase the cost of post-treatment,the production line covers a large area,the reaction required high temperature,and the energy consumption is large.Under the background of advocating environmental protection,new ideas are urgently needed for cold forging pretreatment.Aiming at the friction lubrication in cold forging,a new lubrication method was proposed to replace the commonly used phosphorus saponification reaction in the pretreatment.The wet sandblasting combined with polymer lubricant spraying system was adopted to ensure the lubrication effect of cold forging,improve service life of the die,realize the automation of industrial production,green environmental protection,energy saving and emission reduction.But lubrication stability of polymer lubrication film is inferior to phosphorus saponification film,so how to improve the stability and lubricity of polymer lubrication film,has become a key issue.Firstly,the effects of dry and wet sandblasting on the surface of common steel materials were measured by roughness meter.The effects of them on the surface were visually analyzed by three-dimensional microscope.The results showed that the distribution of peaks and valleys on the surface of wet sandblasting was relatively stable.The Rsk value is less than 0,the variance value is also smaller than the dry blasting’s.The surface characteristics are mostly valley distribution,and there are few sharp solitary peaks.Compared with dry sandblasting,the average of Rku is closer to 3,the variance value is smaller,and the peak-valley character is relatively gentle,forming the concaveconvex character which is conducive to the adhesion of polymer lubricant.Theory of wettability shows that the surface treated with wet sandblasting has better hydrophilicity to the lubrication fluid and relatively higher bonding strength with the lubrication film.On this basis,the coating test was carried out,and the indentation method was used to further prove that the bonding strength of wet sandblasting on the polymer coating was stronger than dry sandblasting.According to the experimental results,a set of integrated equipment is designed.According to the process of the polymer lubricant forming lubrication film,the basic functions of the equipment include wet sandblasting,water washing,lubricant coating and drying.The mechanical structure includes the transmission structure and two circulation system structure,which is controlled by the PLC system.The stress distribution in the process of reverse extrusion was simulated and the equipment parameters were adjusted to prove the feasibility of the equipment and process from the theoretical point of view.The results of the cold forging experiment show that the backextrusion pressure of the workpiece treated with wet sandblasting combined with polymer lubrication is about 10% less than that treated with phosphorus saponification,and there is no scratch on the surface of the die.It shows that this lubrication technology can effectively improve the lubrication conditions of the cold forging process and prolong the life of the die.The industrial mass production results show that in the cold forging process of the parts used in this experiment,wet sandblasting combined with polymer lubrication technology can replace phosphorus saponification technology under certain conditions,improve the die life,green environmental protection,energy saving and emission reduction. |
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