| The copper-based powder metallurgy material used to manufacture the brake pads of the train,the third body formed during the braking process is an important factor that affects the friction performance.When the surface shape of the brake pads is different,it affects the shape of the third body and interferes with the friction coefficient.Therefore,clarifying the relationship between the third body and the surface state has become a problem in understanding the friction performance of the brake material.In this paper,for triangular brake pads,five types of division are performed on the friction surface of the brake pads.Use the inertia reduction test bench to test the friction coefficient,wear amount,friction surface hardness,brake disc surface temperature field,and observe the friction surface under the conditions of braking pressure 0.5MPa and 0.75 MPa,braking speed 50-200km/h Morphological features,to achieve the purpose of exploring the relationship between the surface segmentation morphology and friction coefficient under different friction conditions.The main conclusions of the study are as follows:(1)The split shape of the brake pad surface affects the friction and wear performance.When the number of dividing grooves increases from 0 to 2,as the number of surface dividing grooves increases,the friction coefficient stability increases and the amount of wear decreases.In the speed range of 160-200km/h,increasing the dividing groove can increase the friction coefficient of the material.(2)As the number of braking increases,the friction coefficient of the brake pads increases,but the degree of increase is related to the split form.Under the brake pressure of 0.5MPa,the two split forms perpendicular to the friction direction have the largest increase.During the second and third braking,the friction coefficient increases by 5.6% and 6.9%,respectively.1.During the third braking,the friction coefficient increases by 2.3% and 3.6%;under the brake pressure of 0.75 MPa,the increase in the primary split form perpendicular to the friction direction has the largest increase.During the second and third braking,the friction coefficient increases by 6.2%.And 7.9%;the one-time split shape parallel to the friction direction is the smallest.During the second and third braking,the friction coefficient increases only 0.6% and 1.5%.(3)The surface hardness of the brake pad is related to the position of the dividing groove.The upper surface hardness of the dividing groove is greater than the lower surface hardness,and the fluctuation range of the upper hardness is large.This is due to the existence of the groove,and a large number of third body particles enter the groove,making the surface of the lower surface of the dividing groove third body The continuity is reduced,the compactness is reduced,and the coverage of the substrate is reduced;the hardness of the left area of the dividing groove is greater than the right area,and the surface hardness of the left area fluctuates greatly,because the centrifugal effect causes the third body to move to the left area.(4)As the number of brake disc surface divisions increases,the width of the highest temperature band of the brake disc increases.At a pressure of 0.75 MPa and a speed of 80 km / h,the width of the high-temperature zone divided perpendicular to the rubbing direction and parallel to the rubbing direction was increased from 7 mm to 35 mm and 50 mm,respectively;at a pressure of 0.75 MPa and a speed of 200 km / h,it was perpendicular to The division of the rubbing direction and the width of the high-temperature zone of the disc surface parallel to the rubbing direction were increased from 10 mm to 60 mm and 45 mm,respectively. |
