Hiromichi Onikura

Fabrication of Micro Carbide Tools by Ultrasonic Vibration Grinding

Abstract This paper deals with the fabrication of micro cylindrical tools and micro flat drills of ultra-fine grain cemented carbides by grinding with ultrasonic vibration. The concept of this grinding is to reduce the grinding forces such that they will not cause any breakage to the micro tools. The grinding operations are performed using the end face of an offset grinding wheel. In grinding with ultrasonic vibration, better results in aspect ratio and tools of smaller diameter than conventional grinding are obtained. Due to the lower tensile strength of carbides, grinding under compressive force has made it possible to grind to a diameter of 11 μm with a length of 160 μm.

Fabrication of Electroplated Micro Grinding Wheels and Manufacturing of Microstructures with Ultrasonic Vibration

This study presents the fabrication of micro cylindrical diamond gr inding wheels with diameters from 100 to 500 μm by electroplating of diamond grits in a W atts bath and the manufacturing of micro-structured surfaces assisted by ultrasonic vibration. As a substrate material for micro electroplated wheels, ultra-fine grain cemented carbide was chosen to make the tools more rigid. The fabrication process of the micro wheels consists of cle aning the substrate surface and electroplating the diamond grits. In the present work the electrolyt ic degreasing is performed in addition to the conventional cleaning. This degreasing is found to be effec tive to enhance the adherence between substrate material and electroplated layer. The best adherence is obtained at a degreasing time of 5 min. Using the fabricated wheels, drilling and grooving of sil ic n and stainless steel were performed. In these machining processes application of ultrasonic vibration helps to reduce the wheel loading and sometimes minimizes the dropping of grits from the tool sur face.

Development of a Deep-Hole Boring Tool Guided by Laser

Summary A laser-guided BTA tool has been developed with the purpose of preventing the axial hole deviation in deep hole boring. To examine the performance of this system, two kinds of experiments were carried out using prebored duralumin work-piece. The first experiment was to examine if the tool can be precisely manipulated by computer. The second was to investigate if the tool can follow the target. The target is located in front of the tool and its position changes in the normal plane to the machining axis. The results show that the tool can turn its course to correct hole deviation.

Development of a high-performance laser-guided deep-hole boring tool : optimal determination of reference origin for precise guiding

Abstract A laser-guided deep-hole boring tool using piezoelectric actuators was developed to prevent hole deviation. To extend the depth of controllable boring further, the following were improved. The tool’s guiding error, caused by misalignment of the corner cube prism and the mirror in the optical head from the spindle axis, was eliminated using an adjustment jig that determined the reference origins of the two position-sensitive detectors (PSDs) precisely. A single-edge counter-boring head is used instead of the double-edge head used up to now. The former was thought to be better in attitude control than the latter. A new boring bar, which was lower in rigidity and better in controllability of tool attitude, was used. Experiments were conducted to examine the performance of the new tool in detail and to determine its practical application, using duralumin (A2017-T4) workpieces with a prebored 108-mm diameter hole. The experiments were performed with a rotating tool–stationary workpiece system. Rotational speed was 270 rpm and feed was 0.125 mm/rev. Tool diameter was 110 mm. As a result, controlled boring becomes possible up to a depth of 700 mm under the stated experimental conditions. 700 mm is the maximum machinable length of the machine tool. The tool can be put to practical use.

Development of a High-Performance Deep-Hole Laser-Guided Boring Tool: Guiding Characteristics

A laser-guided BTA tool using piezoelectric actuators was developed to prevent hole deviation. Three kinds of experiments were conducted to examine the performance of this tool using a duralumin workpiece with a prebored hole. The first experiment was performed to examine the conditions of the hole deviation in normal deep hole boring. The second was to examine whether the tool could go straight through without shifting toward a thin wall on one side of the workpiece. The third was to examine whether the tool could go straight through without advancing along an obliquely prebored hole. The results showed that the tool could be guided to go straight through despite the disturbances.

Development of a deep-hole, laser-guide boring tool: the boring of workpieces with a thin wall and an inclined prebored hole

Abstract A laser-guided BTA tool has been developed to prevent axial hole deviations. Four kinds of experiments were conducted to examine the performance of this tool in detail and to determine its practical application using a duralumin (A2017-T4) workpiece with a prebored 108-mm diameter hole. The first experiment was performed to examine the conditions of the hole deviation in the case of normal deep-hole boring. The second was to examine whether the tool corrects for the stated hole deviation. The third was to examine whether the tool can go straight through to the target without shifting toward a thin wall ( t = 0.7 mm ) on one side of the workpiece. The fourth was to examine whether the tool can be guided toward the target without affecting a prebored hole, which was inclined to radial direction at 100 μm for a hole length of 100 mm. The experiments were performed with a rotating tool-stationary workpiece system. Rotational speed was 270 rpm and feed ws 0.125 mm/rev. Tool diameter was 110 mm. The results show that the tool can be guided to go straight through toward the target despite the disturbances.

Development of an Optical Hole-Diameter Measuring Instrument

An optical hole-diameter measuring instrument has been developed. The instrument, which consists of two laser diodes, a photo sensitive detector, two condenser lenses and some mirrors, is intended to measure, based on trigonometry, the distances to the hole wall on two sides alternately. The fundamental analysis and experiment showed that it was possible to measure the distances to the object having not only a mirror-like plane surface but also a rough cylindrical surface. Using the instrument, which was manufactured on trial, it was found that the hole-diameter between 9.5 and 11.0 mm could be measured within accuracy of 23 μm.

Fabrication of Micro Ni-W Electroplated Diamond Tools and Their Application to Grooving of Brittle Materials : Improvement of Tool Quality and Machining Performance

The present paper intends to improve the tool quality and the machining performance of micro cylindrical Ni-W electroplated diamond tools. From the grooving tests of silicon the following results were obtained. The scatter of diamond grit density on the tool surface can be prevented through the intermittent pouring of electroplating solution into the solution with grit supported by a filter. Ni strike plating before electroplating is useful for extending the tool life, but it can result in the degradation of roughness on groove side surface. Tool wear may result from the removal of bond material due to generated chip and dropped diamond grit, therefore the usage of harder bond material and the heat treatment of bond material are recommended. For a constant tool diameter there exists a suitable grit diameter from the viewpoint of machining efficiency and groove roughness. In grooving of quartz glass, chippings of 10-20μm may occur on the groove edges, which can be prevented by the application of axial ultrasonic vibration to the tool.

Improvement in Drilling Performance of Micro Compound Tool

The present paper deals with the development of micro compound tools and their application to the micro drilling. The micro compound tool consists of a micro drill part and an electroplated part with a nominal finishing diameter of 100 µm and they are fabricated by grinding and electroplating processes. Fabricated tools are used in drilling tests with or without ultrasonic vibration. Influences of drill part geometry on burr formation and influences of diamond grit size on peeling of the electroplating layer are investigated. As the results, secondary cutting edges do not seem to have remarkable ability for reduction of burrs. And large size of diamond grit at the electroplated part of a micro compound tool with a small difference between a diameter of electroplated part and a diameter of drill part seems to be effective in preventing peeling of the electroplating layer and improving drilling performance.

An Optical Fiber Probe for 3-D Micro Metrology

This paper presents a system of 3-D micro structure measurement that uses an optical fiber probe of 5 µm in diameter. The probe is deflected when it comes into contact with a measured surface, and this deflection is measured optically. In this research, we optimize design parameters of optical system using ray tracing, and a prototype of the measuring system is fabricated on trial to verify the simulation results. Then, its measuring accuracies are examined by using the basic experimental apparatus. As a result, it is clarified that the resolution of the fiber probe is better than 10 nm. Also, the utility of this system is confirmed by measuring the shape of a 600 µm diameter ruby sphere.