The requirement for passivation of the cutting edge of the tool is to uniformly passivate the cutting edge, thereby improving the machining efficiency of the tool. However, the wear of the brush increases the difficulty of the edge passivation process.
The fact that the edge passivation of the cutting edge of the tool can improve the production efficiency and the quality of the workpiece has been known for a long time. According to different processing conditions, the edge passivation process can increase the tool life by up to 5 times. In addition, the cutting edge passivation of the cutting edge also increases the microhardness of the surface of the workpiece being machined.
In the brush passivation process, the most important process parameters affecting the edge treatment effect are the lateral feed amount aZ (ie, the vertical distance of the brush outer edge relative to the cutting edge edge) and the cutting speed VC. Increasing either of these two parameters increases the amount of material removed, which increases the edge rounding value, while other conditions are constant. Increasing the cutting speed increases the kinetic energy of the abrasive particles, and the increase in kinetic energy is proportional to the square of the cutting speed, which causes the radius of the rounding of the cutting edge to increase rapidly. Other influencing parameters include the duration t of the brush edge and the size of the abrasive particles.
The difficulty of the cutting edge passivation process is whether the resulting rounding of the edges is uniform and whether the desired rounding can be achieved because they must be set according to the material being processed. When the edge is passivated by the brushing process, the wear of the brush causes a deviation in the shape of the cutting edge. Therefore, the purpose of this study was to determine the wear mechanism and the effect of process parameters on brush wear.
In view of the complex shape of the cutting edge, only one edge radius value is not sufficient to fully describe it. Denkena proposes a method for describing the shape of the cutting edge in detail: the cutting edge shape of the cutting edge is described by means of the partial line segments Sα, Sγ and Δr of the cutting edge, and the ratio of Sα to Sγ is expressed by introducing the shape factor κ. In this research work, a contact probe was used to measure the shape of the cutting edge.
Brush movement and process parameters
The movement of the brush is described by the process parameters (cutting speed VC, feed rate aZ, reciprocating speed VP, and blade mounting angle φB). The position of the machining plane is determined by the direction of rotation of the brush and the orientation of the cutting tool. Here, the blade face into which the brush is cut is referred to as an entry face, and the blade face from which the brush is detached is referred to as an exit face.
The shape of the free end of the bristles is determined by the trimming of the brush. During dressing, the brush slides over a polycrystalline diamond cutting edge that is placed obliquely to the direction of motion. Due to the action of the force and the relative movement of the dressing process, a double bevel is formed at the end of the bristles which does not cause significant changes to the passivation process. With the help of a high-speed camera, it can be observed that the material removal process of the edge passivation is divided into four stages: in the first stage, the brush contacts the entry face of the tool; in the second stage, the free end of the bristles begins due to the rotational movement of the brush. Moving upwards, while the bristles are elastically deformed and slipped over the cutting edge; in the third stage, due to the shape of the ends of the bristles, the bristle ends are in full contact with the cutting edges and the material removed from the cutting edges is withdrawn Take away on the face. In the fourth stage, the cutting process ends and the bristles leave the cutting tool surface and continue its circular motion.
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