Abstract
In order to get further study for the effect of abrasive grains to the wall of the workpiece during polishing process, a new method of discrete element that carry out the numerical simulation with DEM is put forward, and the visual calculation is performed for the abrasive grain movement in the nozzle. The interaction of particles-particles or particles-workpiece wall during the polishing process and the tracks of single grain in the workpiece are analyzed by observing the distribution of abrasive grain in the workpiece at different time. The surface removal mechanism of abrasive grains to the workpiece material is discussed by analyzing the collision process of particles to the workpiece wall. The wear level of the abrasive grains to the inner surface of the workpiece is studied through the force of abrasive grain to the workpiece wall consumption, and finally explore the cutting effect of particles to workpiece wall. As a consequence, the abrasive flow processing experiment is carried out. The surface roughness of the large hole and small hole of the nozzle are detected by stylus measurement. The conclusion shows that the surface roughness for the large hole and the small hole before the experiment is1.741 μm and 1.201 μm, its 0.801 μm, 0.651 μm after it. Further roughness tests are performed on the surface of the pores by means of a grating surface measuring instrument. The result indicates that the surface roughness reduces from 2.67 μm to 0.697 μm, 0.728 μm, 0.782 μm. Apparently, the surface roughness of the hole is sharply reduced, which has a smooth and flat inner surface, the effectiveness and reliability of the abrasive flow are verified.
Highlights
The nozzle is one of the most important and critical parts of the engine, whose function is that put the diesel or gasoline into the cylinder through the nozzle, and start the engine by the high-pressure injection, the oil atomization, spark plug ignition [1-4]
It can be seen that part of abrasive grains flow out of the hole while some just remain in the hole, because a number of kinetic energy is consumed by means of collisions and fluid resistance during abrasive particles flow into the workpiece cavity
The stress rapidly increases in the first collision state, which mainly because that the abrasive grains crash the wall at a high speed so that there is a quick stress increase on the surface of the workpiece
Summary
The nozzle is one of the most important and critical parts of the engine, whose function is that put the diesel or gasoline into the cylinder through the nozzle, and start the engine by the high-pressure injection, the oil atomization, spark plug ignition [1-4]. Abrasive grain polishing technology can effectively solve the traditional processing methods that cannot do [5-11]. Abrasive flow is able to promote in the workpiece surface relative movement by the hydraulic cylinder drive piston to move up and down under pressure. The workpiece surface gets a greater shear force, which can achieve the surface material micro-removal to reach the purpose of polishing. THE RESEARCH OF POLISHING NOZZLE QUALITY BASED ON DISCRETE ELEMENT METHOD. The change of the surface quality of the workpiece is the result of the joint action of the various stresses, mainly by the micro-cutting effect caused by the relative movement of the abrasive grains and the workpiece. The polishing process of the abrasive grains can be analyzed and calculated though the discrete element method
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