Numerical Simulation And Experimental Research On The Formability Of Laser Textured Gear Precision Forging Die

Precision forging near-net forming process is gradually becoming the main production method of gears due to high production efficiency,high material utilization rate,and excellent precision of forgings.However,the forging process of gears still has some problems such as unstable forging quality and poor tool life.The surface micro-texturing technology can change the friction condition of the contact interface between the metal blank and the forging die and provide a new method for improving the quality of the forging and the life of the forging die.This paper systematically carried out numerical simulation and experimental research on the formability of the forging die which was processed out textured by laser.Firstly,taking the hot forging near-net forming process of the differential planetary gear as the research object which was made of 20CrMnTi,the orthogonal test was designed to achieve a set of optimal process parameters,at the same time the related information was obtained according to this optimal process parameters.Secondly,based on the Deform-3D,the tribological characteristics and the flow law of the metal billet were studied,and the different combinations of friction coefficient schemes were simulated to achieve their load peak value and maximum wear value.Then,on the basis of the research above,three different micro-groove texturing?round,triangular,rectangular?were designed on the bosses and rounded corners of the toothed die.As so as the maximum forming load value,the maximum wear of the non-texturing toothed die and different types groove-texturing toothed die were compared.Based on this,the temperature field and stress field distribution of the surface layer of the micro-groove texturing toothed die with different cross-sections were studied.Finally,the laser processing technology and friction properties of the surface micro-groove texturing were experimentally studied and a bench test for precision forging of the laser micro-texturing toothed die was carried out.The research work and results obtained in this paper were summarized as follows:1)The forging process of planetary gears was analyzed,as so as designing orthogonal test to obtain a set of optimal process parameters:billet temperature 1100?,preheating temperature of die 300?,forming speed 30mm/s,friction coefficient 0.30.The results showed that the cavity could be filled perfectly,but the toothed die has the largest forming load value after the end of one forging which can reach 304.53KN and the wear value of the surface layer of the toothed die could reach 3.37×10^-68)8)which seriously affects the life of the toothed die.2)When the friction coefficient in the surface of toothed die was 0.10 and the back cone die and the upper die were both 0.30,forming load and wear value were reduced by about 15.82%and 20.18%,respectively,compared to which obtained under the condition of the same friction coefficient of the forging die.3)The micro-groove texturing of the circular and rectangular sections could effectively reduce the maximum wear value of the cavity surface of the toothed die,27%and 2.37%respectively.4)The temperature changed intensely in boss area,followed by the root area,they were prone to plastic deformation failure.The temperature changed mildly in addendum area,which was prone to brittle cracking.The micro-groove texturing could avoid the high-rise of the temperature on the toothed die and improve the surface heating condition.As the area of cross-sectional increased,the heat dissipation effect was improved and the velocity of temperature-rising in the surface of the toothed die could be slowed effectively.5)The effective stress of the toothed die on the addendum area was maximum.Compared with the non-textured toothed die,the effective stress of the micro-grooved texturing with circular cross-section was reduced by about 5.83%.6)As the number of pulse repetitions and the laser power increased,the depth of the micro-grooves increased and the width tended to decrease or increase slowly.Samples with micro-groove texturing were coated with a solid lubricant,which shows an excellent anti-friction characteristics.7)By filling composite micro-lubricants in the micro-texturing on the specific surface of the toothed die could effectively improve the friction during the forming process,reduce the flow resistance of the blank and improve the quality of the forgings effectively.