Key Engineering Materials Vols. 291-292

Abstract: Machining of complex shape and deep micro cavity in die and mold is mostly carried out by electrical discharge machining process. However, it may not be able to sufficiently meet delivery deadline minimization and cost reduction of die and mold. Therefore, precision machining method using small radius ball end mill capable of machining deep cavities in miniature die and mold is proposed as a substitute for electrical discharge machining. This report presents such a result supported by experiment in which it has been proved that long tool life of ball end mill can be maintained by changing coating material and edge profile of small radius ball end mill experiencing form accuracy and get needed surface finish in workpiece. Therefore, for precision machining of die and mold as substitute for electrical discharge machining, it is proposed to perform deep precision machining using small radius ball end mill. This paper shows effect proved by experiment how cutting characteristics which occur by changing of coating material and edge profile of small radius ball end mill influence form accuracy and finishing surface of workpiece.

Abstract: This study aims at clarifying the relationship between the surface integrity of PTFE finished by an ultra-precision diamond cutting and the adhesion strength of a metal thin film. As the first step of this study, the basic properties such as surface integrity in the diamond cutting of PTFE and the effect of the surface roughness on the textile water repellency are demonstrated in this report. The following remarks were found. The measured roughness of finished surface largely exceeded the theoretical roughness, while the cutting force was very small comparing with aluminum and the flow type chips were formed. The surface with a smaller roughness tended to repel water.

Abstract: The toroidal drive offers the advantages such as a high horsepower-to-weight ratio, coaxial configurations, compactness and high operating efficiencies. It combines most of the positive attributes of a circular worm-gear drive and epicycle gear drive without their negative aspects due to the introduction of a set of rollers in meshing contact with rolling movement between a sun-worm and planet worm-gears, and between a stationary internal toroidal gear and planet worm-gears. However difficulties were encountered in machining the toroidal surface of the stationary internal toroidal tooth profile. This paper investigates the toroidal meshing surface and develops a mathematical modelling of the meshing surface and the conjugate surface using motion analysis of the epicyclic gear train. Then the enveloping and NC machining methods are proposed and based on these machining methods the stationary internal toroidal gear is manufactured. This results the comparative study of the tooth profile of manufactured toroidal gears by the proposed methods.

Abstract: Cylindrical cam mechanisms have many merits, such as compact configuration, low cost, high reliability, better performance of kinematics and dynamics, and they have been widely used in fields of automatization and mechanization. Cylindrical cam mechanisms are the spatial mechanisms. Traditional methods of design and machining for cylindrical cam were complex, and it was difficult to ensure the precision of machining cylindrical cams, so it is impossible to meet the requirement of the development of high-speed automatic equipments. The better method of machining for cylindrical cams is to use the NC milling machine with 3 moving coordinates and 1 revolving coordinate. The key to realize the machining method is to resolve the problem of calculating tool’s paths for NC machining from the motion rule of followers of cam mechanisms. In this paper, the programming principle and technology of NC machining for cylindrical cams were analyzed, the compensation of cutting-tool radius for NC machining was discussed, the method of calculation for motion rule of cam followers and method of programming of NC machining with 4-coordinates were proposed, through which perfect effect have been gained in practice.

Abstract: In this paper, the moving platform of the biglide parallel grinder with six degrees of freedom will keep moving horizontally at any time using parallelograms. Besides grinding the helical drill point, this grinder also can work as drilling and welding machine tool as well as a CMM. The joint-velocity Jacobian matrix is calculated. Moreover, the dynamic equations are derived by applying the Lagrangian formulation.

Abstract: NC machine tools, which are widely employed in manufacturing systems, are basically driven by NC programs. However, it requires extensive amount of time and efforts to generate high quality tool paths before a machining operation. An NC program for five-axis control machining is more difficult to generate because the motion of machine tool is more complicated. In this paper, a new architecture is proposed to autonomously control the machine tool without an NC program for more rapid and flexible machining. A technique called digital copy milling is developed to generate the tool paths in real time based on the principle of copy milling. It means that the cutting parameters can be adaptively controlled in order to maintain stable cutting process and to avoid the cutting troubles. In the experimental verification, the improved digital copy milling system for five-axis control milling successfully detected and avoided tool collision in real-time.

Abstract: FEM cutting simulation predicts that the plastic shock waves are generated that develop the high levels of hydrostatic stress in the shear zone when cutting speed exceeds the plastic wave speeds of the workpiece material. The orthogonal impact cutting testing machine was developed to confirm this phenomenon experimentally. In the testing machine, two guide rails are set up in parallel. The cutting tool and the workpiece are installed on the blocks that slide on the rail. Each block connected with the piston in the air tube by the pushrod is launched by the expansion of compressed air, and is accelerated rapidly. When the two blocks passes each other, cutting is done. This paper describes the details of the developed impact cutting testing machine and experimental results of cutting a pure lead at cutting speed up to 65m/s.

Abstract: In order to machine complex free surface parts, a micro NC (numerical control) three-dimensional machine tool is developed, integrated the PMAC control. Based on this NC machine tool, the influencing of the technological and tool’s parameters on machining accuracy of micro complex surface parts are analyzed, and the cause to lead to the machining errors is explained. Therefore, the cutting parameters and tool geometry parameters to machine micro complex surface, such as the human’s face, can be selected optimally. Finally, the micro complex human’s face is machined on this developed micro machine tool under optimal parameters. The experimental results show that the machined surface is smooth and continuous. The machined quality is satisfied.

Abstract: People apply quartz dynamometers to measure of milling force extensively. It is mainly made from piezoelectric quartz sensor. In this paper, the theory of the secondary piezoelectric effect is deduced by four kinds of piezoelectric equations. With the measuring the quartz stack secondary piezoelectric effect is verified. By theory and experiment we can show that the secondary piezoelectric effect makes elastic compliance constant of piezoelectric quartz smaller and do elastic stiffness constant of piezoelectric quartz bigger. Obviously, the secondary piezoelectric effect will have direct effect on the measuring precision of quartz dynamometers. So the investigations of secondary piezoelectric effect contribute to improving measuring precision of piezoelectric dynamometers.

Abstract: This paper investigates how to use shape memory alloy (SMA, Ni-Ti alloy) as a method of chucking parts. It is because tool holder can be simplified and miniaturized. SMA cannot be utilized as chucking tool because it is one-way direction, but it is possible to shrink and release a tool by changing temperature in case SMA is made of combing cylinder with alloy tool steel (SKD61 in JIS). In this report, prototype shrinking tool holder that used combing cylinder with SMA was developed and tried milling processes. As a result, it is clear that combing cylinder with SMA can endure cutting force.