STUDY ON EDGE FRACTURE OF ABRASIVE GRAIN DURING GRINDING WITH APPLYING THE THEORY OF MARKOV PROCESS (3RD REPORT) - EFFECTS OF GRAIN DEPTH OF CUT UPON FRACTURE CHARACTERISTICS OF CUTTING EDGE

In grinding processes, in which the grain edge fracture predominates o ver its attritious wear, the dependence of the fracture characteristic s upon the grain depth of cut must be taken into account, since grain depth of cut is not constant but varies with relative location of the grain edges on the wheel surface. Therefore, the effects of grain dept h of cut upon the onset probability of edge fracture, the height loss of grain tip, and the transition probability of edge shape are investi gated. From a series of fracture tests of WA single grain by grinding, the probability density of height loss at constant grain depth of cut is found to be conformed with a gamma distribution. Another fracture test with a special wheel having 125 abrasive grains on a certain circ ular line on the wheel is also conducted, and it is found that the fra cture onset probability and the height loss are proportional to grain depth of cut. The proportional constants are obtained experimentally a s the maximum likelihood estimators. Two series of fracture tests of s ingle grain under the same grinding conditions but with different grai n depth of cut are further conducted, and it is found that the transit ion probabilities of grain edges are independent of grain depth of cut .