Improving the efficiency of metal-bonded diamond abrasive end tools by improving manufacturing technology

OBRABOTKAMETALLOV MATERIAL SCIENCE Том 20 № 3 2018 EQUIPMEN . INSTRUM TS Vol. 3 No. 2 2021 Fig. 3. Тhe macrostructure of the welded joint area of the investigated diamond grinding head Dependence of the strength of the connection of the shank 6 mm with the working diamond layer of the grinding head 12 mm on the connection method and body material Method of the case bonding to the working diamond layer Case material Case hardness after quenching and (tempering), HRC Tensile joint efficiency between the case and the working partsв, MPa Note Traditional diffusion sintering technology High-speed steel R6M5 (prototype) 62(55*) 200 ± 20 Separation between the case and the working diamond part Condenser welding using an intermediate case Steel U8 62(56) 350 ± 35 Weld rupture Steel 60 61(55) 400 ± 36 Weld rupture Steel 45 54(48) 500 ± 30 Weld rupture Steel 35 45(42) 520 ± 35 Weld rupture * – hardness of the case made of steel R6M5 after sintering and hot pressing at 700 ° С investigated diamond heads according to our proposed method, a copper-plated steel screw stud 3 (Fig. 1) is pressed into the diamond layer, which provides both significant mechanical adhesion by the diamond layer and greater interatomic adhesion due to the larger diffusion sintering surface to a metal bond. The highest values of joint efficiency, provided by the case condenser welding to the working diamond part, are observed in the grinding heads with shanks made of medium-carbon steel of 35 and 45 grades. The tensile joint efficiency between the case made of quenched steel 45 and the M6 stud pressed into the diamond part is 500 MPa, and the joint efficiency limit between the case made of quenched steel 35 and the M6 stud is 520 MPa. At that, it is important that the joint efficiency between the case and the diamond part in these grinding heads is not lower than the intermediate case tensile strength, which is a welding stud of 4.8 strength class, which, as noted above, in accordance with the requirements of GOST should not have a strength limit below 400 MPa. As can be seen from the table, a tensile fracture of the investigated grinding heads, manufactured using the method of condenser welding, occurs in the region of the weld. Measurements of the shank made of