Yasuhiko Ougiya

Rapid Generation of Surface Dimples Using End Milling

Rapid Generation of Surface Dimples using End Milling Shinichi KOGUSU, Takakazu ISHIMATSU and Yasuhiko OGIYA Structured surfaces on metal are often employed to enhance lubricating features, reduce the hydrodynamic drag force along wings and also decorate the metal surfaces for architectural ornament. It is important to note that even single movements of a ball-end mill parallel to the metal surface generate the indented surface on the metal surface based on the cutting condition. In this paper a technique to determine the cutting condition to generate the desired dimpled surface is proposed. The design specifications of the dimpled surface are the width of the dimples and the spacing between the dimples. The proposed technique was successfully used to decorate metal surfaces.

Efficient generation of dimpled surface using milling process

Metal surfaces can be decorated with tiny dimples to have various geometries over the metal surface. A conventional milling technique is often employed to generate desired dimples over the target surface. However, the technique requires a lot of milling time. A new technique to generate dimples using the milling was developed by authors, where the endmilling tool is operated only in the horizontal direction with the significantly high feed rate while the depth of cut is kept a significantly low value. In this paper, a new simplified algorithm to estimate the geometry of dimples is proposed. In addition, a technique to obtain the milling condition to generate the desired dimples is proposed. The technique was applicable to generate sub-millimeter size dimples.

Accuracy of triangulation method sensor with optical skid

To measure a profile on a machine accurately, it is necessary to remove influences caused by various disturbances such as vibration. Vibration between a workpiece and a sensor causes measurement error on machine measurements. Therefore, the authors proposed a sensor using triangulation with an optical skid to remove vibration error. It showed effectiveness against vibration. When the skid probe diameter is not much larger than the wavelength of the profile, the amplitude of the measured profile is smaller than the actual amplitude. This report presents reconstruction method for use with the profile surface of a workpiece with the optical skid sensor and describes effects obtained by simulations and experiments using reconstruction method.

Accuracy of Three-Dimensional Shape Measurement Using a Triangulation Method Sensor with Optical Skid

On-machine measurement is used in ultra-processing machining, but it is seldom used in precision machining. For on-machine measurement, it is necessary that the sensor not be easily affected by the moving error or environment vibration in the field of precision machining. A triangulation method sensor with the optical skid method made using a new design concept is proposed to remove the moving error and vibration. The optical skid method used two laser spots with different sizes: the small spot diameter is the stylus and the large spot diameter is the skid [1]. The difference between these two signals reflects the surface shape. The developed sensor comprises an optical source and two optical receiving systems. Each optical receiving system has an imaging lens and a detector. Instead of two laser spots of different sizes, two detectors with different sizes of receiving area serve as the optical skid. Results confirmed the possibility of reducing the influence of the vibration using the developed sensor. In on-machine measurements, measurement of the surface profile with long wavelength is often necessary. If the spot diameter of the skid is not much larger than the surface profile wavelength, then the smoothing effect of the skid is reduced. Therefore, the amplitude of the measured profile by the skid sensor is smaller than actual amplitude of the workpiece. This paper presents a method of reconstructing the surface profile from the measurement results and the obtained effects of the reconstruction method from simulations and experiments.

Effect of spindle speed control of air turbine spindle on milling for difficult-to-cut materials

In precision machining, machining efficiency is improved by high-feed, high-rotation milling using small-diameter ball end milling. Additionally, static air bearings having excellent properties including low friction, low vibration, high accuracy, and rapid response have been used widely to maintain cutting speed. However, insufficient investigations have been conducted of the stabilization of rotational speed during processing with an air turbine spindle used to drive the main shaft. We have been unable to conduct a systematic evaluation of the effects of changes of the rotational speed during processing on a machined surface with periodic cutting force. Therefore, this study controlled the rotational speed of the air turbine spindle using a high-precision, quick-response (HPQR) pneumatic pressure regulator to examine its effects on the material surface roughness. 1) Rotation-controlled milling was conducted with aluminum alloy and steel alloy, which has good machinability. Then its surface roughness was investigated. Aggravation of the surface roughness was prevented by maintaining the rotation speed: the cutting speed. 2) Rough milling for difficult-to-cut materials by the air turbine spindle without control was impossible. In the worst case, the rotation stopped because the spindle torque was insufficient. However, the rotation speed control of air turbine spindle resolved the torque shortage. An appropriate cutting speed was maintained throughout the milling process. These results demonstrated that the surface roughness was improved compared with non-controlled surface roughness.

Study on high-speed contactless 3D measurement for tooth plaster model

Now, in the dentistry domain, the tooth plaster model is genellary used to evaluate of medical treatment on a dentistry reform patient and to educate of a dental technicians skill. It is measured by the optical cutting system. However, it is difficult to use quantitative evaluation of a dental technicians skill because of total measurement time about 2 hours. If this time can be shortened till about 10 minutes, the number of times of total measurement / evaluation can be increased sharply, and improvement in the quality of medical treatment or skill education can be expected. In this paper, the cause of taking measurement time is analyzed and examined first. Next, the measurement system within 10 minutes is proposed using a 3-lines optical cutting and scanning method with measurement accuracy maintained. This system is developed and evaluated by a fundamental experiment.

Study on high efficiency milling of steam turbine blade

In response to global environmental issues, higher efficiency and improved operational reliability are increasingly being requested for steam turbines, essential equipment for thermal power generation. Its material is stainless steel, which is difficult to cut because of high work-hardening trend and high resistance to heat. As its complex shape and high accuracy requirement, conventional methods such as using a ball end mill have obstacles of achieve a high accuracy coexist with high efficiency. The main objectives of this study are to propose a new method called Linear Interpolation Milling(LIM) using a taper end mill and verify its validity both in theory and practice.

Decoration of metal surface by dimples using ball-end milling process

Structured surfaces are often employed to enhance physical properties of metal products. Dimples are usually generated on metal surface by a ball-end milling with a combination of tool movements in horizontal and vertical directions. It is important to note that only horizontal tool movements of ball-end milling with high feed rate can also generate the dimpled surface. Authors already proposed a technique to generate desired dimple shape on the metal surfaces using a machining center. Following the technique, decorating process of the metal surface has been achieved. In the generation processes deformation of the dimples is observed. The deformation of the dimples is considered using numerical model and the mechanism to cause the deformation is analyzed. In the experiment decorations are successfully achieved with various shapes of dimples on a metal surface by using a sub-millimeter ball-end mill.

A profile calculation method for form grinding wheels : theoretical analysis of error transmission and its application

When the values of coordinates and gradients at some points on a grinding wheel profile are given, a work tooth profile ground by the grinding wheel is analytically decided. By this method, transmission of errors (setting angle error, decrease in radius of grinding wheels by truing, positioning error, tooth profile error) from a grinding wheel to a work is analyzed. The transmission of errors is denoted by matrices. The quantity of errors is pointed out clearly according to the difference of specification of a work or a grinding wheel. A result that transmission of errors is decreased by selecting a best setting angle of grinding wheel is obtained.