Toshimichi Moriwaki

Development of 2DOF Ultrasonic Vibration Cutting Device for Ultraprecision Elliptical Vibration Cutting

A new ultrasonic vibration cutting device for ultraprecision elliptical vibration cutting has been developed. The elliptical vibration cutting device developed utilizes combination of bending and longitudinal modes of vibration of the stepped vibrator to generate circular or elliptical vibration locus at the cutting tool edge. The design principle as well as the structure and the performance of the elliptical vibration cutting device is introduced here. The experimental results of diamond cutting of Co-Cr-Mo Alloy proved that good surface quality with roughness of 20 nmPV can be obtained stably with the elliptical vibration cutting device developed.

Cutting Temperature Measurement in Turning with Actively Driven Rotary Tool

In this paper, turning with actively driven rotary tool was investigated. The influence of machining conditions such as tool rotational speed and inclination angle on the cutting edge temperature is examined experimentally. The temperature was measured by a thermocouple of constantan wire and work material. Experimental results show that the cutting temperature decreases with increasing tool rotational speed to a minimum value at a certain tool rotational speed and then increase. Next, the minimum temperature recorded by tool rotation was approximately 150oC lower than that the cutting with a non-rotating tool. Finally, the cutting temperature also decreases with the increase of inclination angle to a minimum value at an inclination angle.

Machinability of CBN Tool in Turning of Tungsten Carbide

Tungsten Carbide have extremely high hardness and wear-resistivity compared with conventional steel materials, and it is expected that the Tungsten carbide can be applied widely to dies and molds in the near future. In order to develop an efficient machining method of Tungsten Carbide for the dies and molds, series of cutting experiments were carried out to turn the sintered Tungsten Carbide materials with CBN tool. The selected sintered Tungsten Carbide workpieces are those containing Tungsten Carbide grains with mean grain size of 5μm, and 15wt%, 20wt% and 22wt% of Cobalt binder. The sintered CBN tool selected contains super-fine grains of CBN with mean grain size of 1μm. The cutting speed was varied from 10m/min to 60m/min, and the tool wear and the surface roughness were measured. It is concluded that the tool wear is less when cutting the sintered Tungsten Carbide containing larger amount of Cobalt binder. The surface roughness of about 2μm in Rz is obtained.

Development of a Support System of Operation Planning for Parallel Kinematic Machine Tool

Compared to conventional serial kinematic machine tools, parallel kinematic machine tools have advantages for high speed and multi-degrees of freedom positioning. However, they cannot simply achieve high speed cutting because of their relatively complex structures. In order to achieve high speed cutting on parallel kinematic machine tools, it becomes important to optimize the tool trajectories and the workpiece position. In this study, the strut motion controlling a spindle unit is simulated while cutting. And external forces, which are gravity, friction and inertia forces, acting each strut are estimated by solving the kinematic model. The tool posture, the feed direction of ball-end milling and the workpiece setup position are evaluated based on the estimated external forces during a cutting operation. Also, an evaluation method of vibrational stiffness is proposed by employing the unit vector of each strut direction obtained from the simulator developed above. The proposal method is validated by the hammering tests in various conditions. It is confirmed that the support system developed in this study can realize to reduce the variation of external forces and the influence of vibration during a cutting operation on a parallel kinematic machine tool.