Minoru Arai

Machining Characteristics of Hard Materials

Abstract The hardening of steel rather lowers the cutting forces in many cases. This is the result of high shear angle and the saw-toothed chip formation due to the poor ductility of hard materials. Reinforcement of Al alloy with fiber also decreases the cutting forces. However, the hard materials wear the cutting tool rapidly and increase the forces, especially thrust force which causes size error. The profile of machined surface of hardened steel reflects the profile of cutting edge.

Burr Formation in Metal Cutting

Abstract Machining burrs formed in various cutting operations are rationally designated by the combination of two systems of classification: (1) by cutting edge directly concerned and (2) by the mode and direction of burr formation. The size of burr is shown to be reduced by (1) reducing the undeformed chip thickness, (2) selecting the cutting conditions so as to reduce the shear strain undergone by the chip and (3) designing the tool and workpiece geometry so as to strengthen the edge of workpiece and also to turn the direction of cutting force toward the workpiece.

Comprehensive Chip Form Classification Based on the Cutting Mechanism

For the logical control of chio farm in machining operation, chio forms are classified comprehensively, and the conditions to control the form are indicated. Cue to the developments in cutting tool and cutting technology, possible ranges of variation in the conditions and the form of chios produced have become very wide. To meet such situation, the chio form diagram presented before by one of the authors is expanded. Essential meanings of the direction of side curling and chio flow angle on the chio form and the proceeding of helical chio are made clear. A projection on tool face plays important role by changing the line of tool-chip separation and, accordingly, the form and proceeding of helical chip.

Chip control in finish cutting of magnesium alloy

Abstract Magnesium alloy is a useful material for the reason of light metal, but in finish cutting, chips are inflammable. This paper proposes a method of the chip control by skiving of magnesium alloy. Cutting conditions were investigated experimentally for generating of the tubular helical chips.

Semi-Empirical Equations for Three Components of Resultant Cutting Force

For the determination of adequate cutting conditions and the selection and design of both cutting tool and machine tool, not only the cutting force but also the feed force and thrust force must be known quantitatively. This paper presents the semi-empirical semi-theoretical equations for the three cdmponents of resultant cutting force. These equationa are dorived from theoretical equations by simplifying them using the empirical relations which exist in practical range of cutting conditions. Eaoh component is indicated as the function of depth of cut, feed, cutting speed, rake angle and opproach angle. For the work material, these equations include the specific forcesata standard set of cutting conditions, the coefficiantsof cutting speed and undeformed chip thickness, and the coefficientsof rake angle. These material constants are obtained from a series of cutting tests on each work material and approach angle.

Cutting Tool with Curved Rake Face — A Means for Breaking Thin Chips

Summary Thin chips produced in finish turning, facing and fine boring are very hard to be broken because of their flexibility, and cause trouble in chip control. At present, this is the largest barrier to the spread of unmanned machine tool operation. In this paper, this trouble is shown to be avoided when the chip is given a curved section. For this purpose, cutting tools with various types of curved rake face are tested. A double spherical pit on the rake face is found to be very effective for the chip breaking without sacrificing tool life.

Effect of Cutting Edge Roundness on Work Hardened Surface Layer in Metal Cutting

In the ultra-precision machining, the smaller the undeformed chip thickness is, the more the machined surface integrity is affected by the cutting edge roundness of the cutting tool. In this research, the work hardened surface layer was dealt with as an evaluation of the machined surface integrity and the effect of the mechanical factors on work hardening was investigated experimentally in orthogonal cutting. In the case of a rounded cutting edge, unlike a sharp one, it makes the generation mechanism of the work hardened surface layer complicated. In this research, the mechanical dominant factors were investigated by comparing the effect of the rounded cutting edge on the work hardened surface layer, which counts for much in ultra precision machining involved in small undeformed chip thickness, with that of the sharp cutting edge.