Research On Truing And Grinding Performance Of Flute Grinding Wheels For Carbide Cutting Tools

Due to their high hardness, high wear resistance and high thermal rigidity, solid carbide cutting tools can be used for getting workpiece with high precision and high quality surface while cutting at a high speed. And it has been widely used in the aerospace, automotive, mold, electronics and other industries for efficient high-precision CNC machining. The spiral flute of solid carbide cutting tools is machined by slotted-wheel through the technology of deep creep feed grinding. In this process, the material removal is the biggest, and the processing efficiency is low.What’s more, slot grinding tends to cause big peripheral edge collapse, which influences the quality of circumferential edge. In addition, slot grinding determines the quality of circumferential rake face. In order to resolve peripheral edge collapse and improve machining efficiency in the actual production of co-operative enterprise,this paper investigates the process of truing and grinding and finds out the existing problems in the present production. Then, this paper studies related improvements. At last, this paper studies the efficiency and quality of the slot grinding. The main research contents and contributions of this paper are as follows:(1)This paper investigates the process of truing before grinding, and studies the surface topography of grinding wheel, machine load, the circumferential edge collapse, the surface topography and roughness of circumferential rake face both before and after dressing. The survey found that the medal bond slotted-wheel was used for grinding directly without dressing by the oilstone after truing by the silicon-carbide abrasive wheel. The experiments show that the process of truing has some effect of dressing, but the height of grain protrusion is low. The slotted-wheel can be used for batch stable production after truing through the process of grinding twice of the flute, but the efficiency is low.(2)This paper studies the difference of two organizational kind slotted-wheels in their structure and grinding performance. One of the two is produced by Japan(the wheel I) and the other one is produced by Germany(the wheel II).The result shows that the grains of the wheel I is relatively coarse and with a clear edge. The grains ofthe wheel II is relatively good and irregular. The bond of the two wheels’ is compound binder which is bronze bond mostly, but the bond of the wheel II contains some resin. The wheel I is easier to be truing but more difficult to dressing than the wheel II. It is easy to produce the big circumferential edge collapse during grinding for the wheel I both before and after truing or dressing. It takes a long time to enter stable grinding to the wheel I and it takes a short time to enter stable grinding to the wheel II. And it is easy for the wheel II to prevent the big circumferential edge collapse. It is not a good idea for the wheel I to grinding the flute by one time under the existing process of truing or dressing, but the wheel I can do it.(3)Silicon carbide grinding wheels which is harder and coarser, have higher truing efficiency. However, silicon carbide grinding wheels which is softer and finer, have a better effect to dressing. It must to add the process of dressing after truing. It can improve the protrusion height of the grains, and improve the sharpness of the wheel and reduce the load of machine obviously.(4)The defect of the circumferential edge collapse produced by slot grinding can be effectively removed by the subsequent clear edge technology. Therefore, the grinding depth and the feed rate can be increased if the load is permited during grinding.Enterprises original grinding process is relatively conservative. After investigation, it finds that the process of the Slot grinding can be finished by one time insteading of two times. Although the load will be increased, but the amount and rate of the increase is in the affordable range of the machine. The circumferential edge collapse and the roughness of the tools produced by the process of the Slot grinding by one time meet quality requirements. The process also enables stable batch production. The efficiency of the Slot grinding is greatly improved by changing grinding times from two to one.