Search

The thermal deformation of cutting tool in metal cutting gives unfavorable influences on the accuracy of required geometries of workpieces and the life of cutting tool. Various attempts have been made on the experimental evaluation of thermal deformation of the cutting edge and the thermal stress in the cutting tool. In this paper theoretical analyses on the thermal deformation of cutting tool and the thermal stress in it are carried out by using the finite element method. And the investigation in this paper showed that the effect of the thermal displacement of the cutting edge could not be disregarded in the case of fine machining on the accuracy of required geometries.

This paper describes the effects of the artificially controlled shear angle on the metal cutting process. From the experiments in which commercially pure lead is cut with various controlled shear angles, constant cutting speed, and depth, and various rake angles, the following results were obtained.(1) Taking rake angle (α) as parameter and increasing the controlled shear angle (φ), the points (φ, β-α) move along a right convex curve on the φ vs β-α plane on which critical points giving a minimum value of cutting force (Fc, min), lie in the vicinity of Merchant's Line.(2) The variation of φ does not influence the friction force on the rake face (CF), and the angle which gives a minimum cutting force (Fc min) gives a maximum value of coefficient of friction on the rake face.(3) Hydrostatic pressure on the shear plane increases with the increase of φ, and does not influence the shear stress on it.(4) It has been confirmed either the shear plane model does not agree with the cutting mechanics for low cutting speed or the angle φ is such that the total cutting power is not minimum.

The finite element method is applied to the analyses of the distribution of normal stresses on the tool rake face, stress-strain distribution in the tool and the static deformation of cutting edge. The following results are obtained:(1) The acting force on the distance of 10 percent of chip contact length near the cutting point is about 25 percent of total cutting force.(2) The cutting edge is deformed in both directions of the cutting and the depth of cut in cutting process, and the displacement of cutting point is nearly proportional to the value of clearance angle.(3) Maximum principal shearing stress is produced in the rake face except the cutting edge for a cutting tool which has less clearance angle.

Stress-strain distributions in the cutting plastic zone are analysed by using the Visioplasticity method with a digital computer.Steady-state flow patterns for these analysis are obtained from the cutting of alpha brass with a 30 deg. rake angle tool, 13.6 mm/sec cutting tool speed and 1.5 mm depth of cut.The plastic behavior in metal cutting is discussed from obtained results.

In this paper the problem of optimum sequence of operations in the multi-stage manufacturing system (for example, some machining centres or NC machine tools combining some operations) is studied for achieving minimum total cutting cost. In order to determine the optimum sequence of operations in the multi-stage manufacturing system, dynamic programming has been applied to its numerical model, which is obtained by relating the optimum sequence of operations to the optimum job allocation for each operation, and it is pointed out that dynamic programming is a powerful tool for determining the optimum sequence of operations in the multistage manufacturing system.