Hideyuki Mizutani

Influence of Cutting Edge Shape on Residual Stresses of Cut Surfaces (2nd Report, Effects of Nose Radius and Cutting Edge Roundness)

In order to obtain basic information on the improving the surface integrity of machined surfaces, the relationship between the residual stress of cut surfaces and the cutting edge shapes of cutting tools was examined. We used cutting tools that had various nose radiuses and cutting edge roundnesses to perform dry facing on a lathe. The residual stresses of the cut surfaces were measured by X-ray diffraction method. We found that when the rake angle was about zero degrees, the nose radius barely affected the residual stresses of the cut surfaces. However, when the negative rake angle was large, the nose radius significantly affected the residual stress. The residual stresses of the cut surfaces shifted compressive side when there was an increase in cutting edge roundness. The residual stress of a cut surface is kept in a high compressive state even though the cutting force decreases greatly due to grinding removing the rake side part of the cutting edge roundness.

In-feed Internal Honing of Fine Ceramics. Honing Processes of Various Fine Ceramics.

The purpose of this study is to improve the machined surface roughness and machining efficiency of fine ceramics by in-feed honing. The results obtained are as follows. The honing force shows a considerable change which corresponds to the difference in the surface generation phenomenon. Transient honing time shows a tendency to decrease as the fracture toughness of the workpiece decreases. In the honing of brittle materials, a very small interference depth between the cutting edge and workpiece makes the work surface have better roughness characteristics. In order to improve the honed surface roughness, in the case of honing with a metal-bonded stick, it is effective that the cutting surface of the honing stick be dressed by a etch method after truing with a diamond wheel grinding.

Study on Grinding Force Ratio.

The purpose of this study is to elucidate the root cause of a change of the grinding force ratio, which is the ratio of the tangential force and the radial force. In the grinding tests of this study, the interference shape per cutting edge and the state of the cutting surface of the wheel were changed systematically. The following results were obtained: ( 1 ) When the state of the cutting surface of the wheel and the peripheral wheel speed are held constant, the product of the interference length and the maximum interference depth per cutting edge of abrasive grain decides the grinding force ratio. ( 2 ) The grinding force ratio shows a rise with the increase of successive cutting edge spacing, and the increase of the rate of the area of grain flank reduces the grinding force ratio. ( 3 ) The grinding force ratio in a series of experiments is decided by the quotient of the product of values of interference condition per cutting edge and the rate of area of grain flank in the cutting surface of the wheel.

Study on Cutting Force Ratio.

In metal cutting, it is a well-known fact that the value of Q/P, which is the ratio of the tangential force Q and the radial force P, is remarkably different in machining and grinding. In this paper, considering machining and grinding collectively, investigation on the effects of basic factors which produce such differences systematically was carried out by a simple model experiment. The results of the experiment made it cleat that compared to machining, in grinding, all values of the basic factors such as interference depth of cutting edge and workpiece, cutting speed, cutting edge condition, etc. are in the direction toward reducing the cutting force ratio. Moreover, the results of an overall grinding test showed that the force ratio in grinding is controlled by the product of the interference length and the maximum interference depth per cutting edge of the abrasive grain on the cutting surface of the grinding wheel.

Effect of Fe, Si content on the machinability of 5056 alloy.

Dry cutting tests of 5056 alloys which were added Fe (0.014-0.19wt%) and Si (0.006-0.07wt%) were made using high speed steel (SKH4) and sintered carbide tool (K10). Effect of these elements on the machinability was studied from the viewpoints of cutting resistance, built up edge, cut surface roughness, tool wear and chip disposal.(1) Under a low cutting speed, machined surface of all specimens were rough and scaly for forming of built up edge. However, under a high cutting speed, feed marks on machined surface appeared clearly and its roughness value was low. Especially the finished surface of alloy which contains less Fe and Si approximated to the theoretical value.(2) Following the increase of Si content which formed metallic compound Mg2Si in this alloy, the tool wear rates on flank and rake face were rapid. In increasing Fe content which formed metallic compound Al-Fe, the rake face wear progressed rapidly. But, it was less affected with the flank wear rates.

Effect of Mg content on the machinability and the cut surface quality of Al-Mg alloy.

Cutting test were carried out for the two main groups in the cutting tests, one is regular type turning with a high speed steel tool and with a carbide tool, another is mirror finished cutting with a diamond tool.Cutting force was found rather low in the none Mg alloy and in 4.41% Mg alloy cutting when the cutting speed was higher than 2m/s and Mg content was more than 2.48% built up edge was almost disappeared. Chips disposal was improved slightly by containing Mg in the alloy. In the regular type turning, depth of affected layer of cut surface was decreased by increasing Mg content. On the other hand, affected layer of mirror finished surface was so small depth and the surface roughness (Rmax) of 0.02-0.03μm was generated in the mirror finished cutting of every kind of alloys in this test. Reflection factor of the mirror finished surface of rich Mg content was better than that of little Mg content.