Yoshiyuki Kaneko

Approximation of Thermal Deformation Behaviour of a Machine Tool to Improve its Process Precision

This paper presents a stochastic method to approximate the thermal deformation of a machine tool, by using the temperature changes of the body. The method examines the relationship between the thermal deformations and temperature changes of plural positions on a machine tool, and determines the appropriate temperature measuring points. In addition, the approximate equation of the thermal deformation is drawn by t-test, which uses those influential temperature changes as parameters. This study shows that the approximation equation of the thermal deformations can be expressed in a simple form with few parameters, and remarkably improve cutting processing.

Vibration Control of Relative Tool-Spindle Displacement for Computer Numerically Controlled Lathe With Pipe Frame Structure

A new computer numerically controlled (CNC) lathe with a pipe frame bed has been developed. This structure is expected to have enough space between the truss bars to solve the space problem and have enough rigidity for machine tools. Therefore, a CNC lathe whose frame consists of pipes, joints, and diagonal braces has been developed with enough rigidity and space utility for chip evacuation. From the viewpoint of machine tool usage, real-time vibration control theory is applied to control the relative displacement between the tool post and the spindle to suppress specific relative vibration modes.

Development of a tandem-table-type CNC lathe with four-axis synchronized control

In the present study, we describe a newly developed CNC lathe for realizing non-axisymmetric curved-surface-turning (NACS-turning). The newly developed lathe can be controlled along four axes (X1, X2, Z, and C) and has a three-linear-motor drive system for the X1, X2, and Z axes to control precise, high-speed motion. The tandem table unit, which moves along the X1 and X2 axes, can move at a maximum acceleration of 98.1 m/s2 synchronously with the spindle rotational position. Therefore, in order to realize high-speed cutting motion of a machining curved surface as well as suppress the vibration transmission, the inertial forces are made to cancel each other. In the present study, the fundamental dynamic performance and vibration suppression effects of the tandem table were examined.

Development of CAM System for 3D Surface Machining With CNC Lathe (Tool Path Generation Considering Acceleration)

This study developed a method called non-axisymmetric curved surface turning (NACS-Turning) for a CNC lathe composed of a turning axis and two translation axes. The NACS-Turning method controls the three axes synchronously. This new machining method can reduce the lead time for non-circular shapes such as cam profiles or pistons for internal combustion engines. In our previous report, we presented an outline of a machining principle and a CAM system for NACS-Turning. However, at the same time, we found the problem that the X-axis slide exceeds the allowable acceleration. Therefore, it is preferable that the acceleration is verified during the cam application, and the tool path is generated within the allowable acceleration range. Therefore, this paper first describes the determination method of machinable conditions for NACS-Turning in the cam application. Next, based on the result, relationships between the acceleration of the X-axis slide and machining conditions are clarified. Finally, the experimental procedure showed that our proposed method does not exceed the allowable acceleration of the X-axis slide.© 2014 ASME

Development of Pipe Structure Frame for CNC Lathe – Adaptation of Thermal Displacement Control

The miniaturization of many machine parts for machine tools is desired for the purpose of effective utilization of space, energy saving, and realization of desktop factory. To develop a compact and miniaturized NC machine tool, new downsized small parts such as hydraulic parts, pneumatic parts, electric parts and mechanical parts must be developed. These parts are not always satisfied for the practical usage in the present industrial level. Therefore, in spite of many requirements toward the miniaturization of the machine tool from the market, the miniaturized NC machine tool has not been put to practical use. The old-style structure of machine tools is one of the reasons of obstacle to solve this problem. We have proposed a newly developed ultra small size CNC lathe by using the pipe frame structure. The heat transfer between pipe elements and connecting block is affected strongly to the axial displacement. Therefore, the heat transfer between pipes can be insulated by the heat control on the connecting block. The thermal displacement control is realized by using the Peltier devices set on the connecting block. The results on the thermal displacement control of this structure and the effects on the cutting results are reported.

Vibration Control of Relative Tool-Spindle Displacement for CNC Lathe With Pipe Frame Structure

A new CNC lathe with a pipe frame bed has been developed. One requested improvement for machine tools is their downsizing by minimizing the number of mechanical parts. Some researchers aim to construct a desktop factory. This trend has been attracting a lot of attention lately in the industrial field. When a machine tool bed is designed using castings and/or welded steel plate structures to comply with this request, it is difficult to ensure space for chip evacuation because of the space limitations of solid body components. This led us to develop another type of structure for machine tools.A pipe frame bed has the ability to solve this problem. As represented by bridge trusses and flexible space structures, truss structures are traditional and fundamental in their design. This structure is expected to have enough space between the truss bars to solve the space problem. However, rigidity is the most significant issue for machine tools. Therefore, the desired rigidity is ensured by the use of diagonal braces.Based on this design concept, a CNC lathe whose frame consists of pipes, joints, and diagonal braces has been developed with enough rigidity and space utility for chip evacuation. From the viewpoint of machine tool usage, the rigidity and stable dynamic characteristics of the structure must be obtained. Then, real-time vibration control theory is applied to the relative displacement between the tool post and the spindle. Active vibration control is used to suppress specific relative vibration modes.In this paper, the effects of vibration control are evaluated by comparing the relative vibratory motion between the tool post and the spindle. Over 50% suppression has been achieved by applying vibration control to the target vibration mode. Additionally, using this control, the machined profile has been improved, and the roundness and harmonic analysis of the workpiece showed over 30% improvement.Copyright