Investigation On Tribological Behavior Of Drawing Mold By Composite Laser Surface Texturing

Mold is one of the basic equipment in metal processing industry,In addition,sheet metal deep drawing plays an important role in various industries.The tribological system between drawing mold and workpiece has an important effect on the forming quality of workpiece and the service life of drawing mold.Therefore,it is of theoretical and engineering significance to study the tribological properties of the drawing mold and workpiece.Research suggests that,the mold surface after composite laser texturing in sensitive areas can be set to achieve the optimal distribution of the friction properties,resulting of controlling the material flow in plastic deformation and the quality of sheet.The durability of composite laser texturing on mold surface is critical to engineering applications.In this paper,the influence of composite laser surface texturing on tribological behavior is investigated experimentally.On the basis of this,the surface textures were fabricated by using laser texturing technology.It is expected that tribological properties are optimized,wear loss of the mold surface is reduced,the service life of mold is prolonged,and the quality of workpiece is improved.The main research content of the paper is as follows:(1)Processing experiments of laser composite texture.Firstly,the composite textures were processed on Cr12 samples,and the effects of laser power and pulse width on texture parameters were investigated by using the single factor alternate method.Secondly,the metallographic and hardness tests were conducted,and all of that were compared for un-textured and textured samples.It is shown that,the diameter and height of the bulge textures both increase with the laser power increases.When pulse width increases,the diameter of bulge texture increases,however,the height firstly increases and then decreases.The diameter of the pocket texture increases with laser power and pulse width increase.There is non-simple linear relationship between the pocket depth and laser power,pulse width.Besides,the metallurgical organization and hardness of texture is more densely and higher than that of substrate,respectively.(2)Tribological experiments of the bulge textures of cold working die steel were carried out.Pins with different textures and area ratios were processed,and the effects of laser texturing on friction and wear properties were investigated by using the single factor alternate method.In addition,the working parameters of load and velocity were analyzed experimentally.Tests shows that the friction coefficient and wear volume increase with the area ratio of crown-shaped texture increases.For the crater textures,a laser texturing with 27.3%-area ratio is likely to have a better tribological property,which shows both the friction coefficient and wear volume reduced sharply.In all samples,a 27.3%-area ratio of crater textures presented the smallest friction coefficient.A 7.6%-area ratio of crown-shaped texture is shown smallest wear volume.Furthermore,when the load increases,the friction coefficient firstly decreases and then increases.Velocity also has an important effect on friction coefficient,friction coefficient increases with velocity increases.(3)Tribological experiments of bulge texture of hot working die steel were conducted.Pins with different area ratios and heights were processed on 5CrNiMo,and the effects of M-shaped textures on friction and wear properties were carried out.Results shown that the area ratios of textured surfaces has no significant effect on friction coefficient after stabilization.Yet,the fluctuation of friction coefficient and wear volume decrease with area ratio increases.Meanwhile,the average friction coefficient reduces with decrease of laser texturing height.A laser texturing structure with 45%-area ratio and 3.5?m-height is likely to have a better tribological property,which shows that the friction coefficient reduced by 85% and the wear volume reduced by 99%.The proportion of wear volume in running-in stage is 58%~62% of the whole process.Finally,at the running stage,the main wear mechanism is the scratch wear,and the main wear mechanism is adhesive wear at stabilization stage.