Masahiko Jin

The utility of radially and ultrasonically vibrated dies in the wire drawing process

Abstract In the field of wire drawing, the use of high-viscosity lubricants, which would inevitably require the use of strong and non-environmentally friendly degreasing agents such as fluorocarbons or 1,1,1-trichloroethane, has been restricted in order to reduce environmental pollution. This problem can be solved, for example, by using low-viscosity lubricants such as water-soluble oil. However, this generally results in poor drawing performance which must be solved in some other way. In this study, first, a solution to the problem, wherein radially and ultrasonically vibrated wire drawing dies are utilized (RVD operation in short), is proposed to enable the use of low viscosity and, in particular, chlorine-free lubricants. Second, it is verified by both theory and experiment that the RVD operation is effective in increasing the critical speed in ultrasonic wire drawing by about 10 times that of the axially vibrated dies (AVD operation in short) that have been used conventionally.

Development of a practical ultrasonic vibration cutting tool system

Abstract In this study, a combination of countermeasures to prevent the chipping of the edge of a cutting tool is investigated. This chipping usually occurs when difficult-to-cut materials such as hardened steels are cut by means of a conventional ultrasonic vibration cutting (UC) method. The authors consider that the chipping is caused by a collision between the flank of a cutting tool and the machined surface of a workpiece when the tool moves backwards thereby contacting the workpiece. As a first countermeasure they propose a new UC device which has more rigidity and stability than the previous one that they used, even when subjected to high cutting resistance. As an additional countermeasure, in addition to using the new UC device, an attempt to is made to perform a cutting operation in which the vibrational direction of the cutting tool is inclined from the principal cutting direction by 10–30° toward the workpiece. It is found from the results that the chipping of the cutting edge can be effectively prevented and a good surface finish obtained by both continuous and intermittent cutting modes when cutting hardened steels.

Simulation of ultrasonic-vibration drawing using the finite element method (FEM)

Abstract In ultrasonic-vibration drawing, wires are drawn while ultrasonic vibration is applied to a drawing die. Prior studies provide experimental proof that ultrasonic-vibration drawing reduces drawing resistance, improves lubrication and prevents wire breakage. In the future, ultrasonic-vibration drawing is expected to contribute to the drawing of difficult-to-draw materials and operations, such as shaped wires, ultrafine wires, and the wire drawing operation in semidry or dry condition. However, a detailed analysis and understanding of the mechanism of improvement is not possible on the basis of conventional experimental observations because the ultrasonic-vibration processing phenomenon occurs at high speed. Therefore, we attempted to understand the processing mechanism of ultrasonic-vibration drawing using the finite element method (FEM). ABAQUS was used for the FEM. Drawing force and stress–strain distributions in drawn wires were analyzed. From these studies, we quantitatively clarified the mechanism of improved drawing characteristics, such as decreased drawing force.

Trial fabrication and cutting performance of c-BN-coated taps

In this study, the possibility of using a c-BN-coated tap for cutting a beta-type titanium alloy which has been known as one of the most difficult to cut materials was investigated. The beta-type titanium alloy is known to strongly adhere to the tools during the operation. The authors considered that the c-BN coating film, which is known to have good tribological characteristics, could be effective in preventing this adhesion for cutting operations of the beta-type titanium alloy. We fabricated c-BN-coated taps by means of a magnetically enhanced ion plating method and carried out tapping experiments to evaluate the performance of the tap. As seen from the results, the c-BN-coated taps proved to be effective in the cutting of beta-titanium alloys with improvement in the accuracy, tapping resistance and tool life over those in the case of commercially available conventional-coated taps.

Investigation Mechanism of V-Ring Indenter Geometry in Fine-Blanking Process

The V-ring indenter geometry (angle, height and position) was investigated by using the finite element method (FEM) to theoretically clarify the mechanism and its action in the fine-blanking process. The FEM simulation results indicate that very small or very large V-ring indenter angles, heights, and positions cause difficulty in the rotation of the material-flow and that the hydrostatic pressure is generated with great difficulty in the blanked material; therefore, crack formation occurs easily. The application of a suitable V-ring indenter angle, height, and position significantly suppresses the formation of rotating flow, which results in increased hydrostatic pressure, and crack formation is consequently prevented.

Die Design in Fine-Piercing Process by Chamfering Cutting Edge

The hole quality on sheet metal parts is directly dependent on the die design and process parameters. In conventional piercing process, the secondary operations such as shaving, reaming and grinding are needed for manufacturing the precise-dimensioned holed parts without any cracks, resulting in the increase of both production time and costs. The fine-piercing process, referenced to the fine-blanking principle, is used to produce the precise-dimensioned holed parts with smooth-cut surfaces over the whole material thickness in a single operation. However, it is difficult to achieve the suitable die design and process parameters for meeting the part requirements. In this study, the die design by chamfering punch cutting edge was investigated on both the experiments and the finite-element method (FEM). The results were compared with the results obtained when the conventional die design with the punch cutting-edge radius was used. The FEM-simulation results showed the amount of die-roll, smooth-cut surface, and cracks agreed well with the experimental results. The results showed that an application of punch cutting-edge chamfer results in a superior fine-pierced hole surface could be achieved. Furthermore, the mechanism and effects of the punch cutting-edge chamfer have been theoretically clarified on basis of the material-flow analysis and stress distribution.

Application of Back-Up Ring in Fine-Blanking Process

Considering the advantages of the fine-blanking process, the smooth-cut surface without further operation could be fabricated. However, one of the major problems of the fine-blanking is the occurrence of the die-roll formation. This problem is the main factor which affects the quality of the fine-blanked parts. In this study, to reduce the amount of die-roll formation, the application of back-up ring was proposed. The finite element method (FEM) was used to investigate the effects of back-up ring. In addition, the effects of bridge width were also investigated. The FEM simulation results illustrated that the mechanism of back-up ring and the effects of bridge width could be theoretically clarified base on the material flow analysis. The FEM simulation and experimental results showed the good agreement with each other. Therefore, the application of back-up ring could reduce the amount of die-roll formation on the fine-blanked parts. In this study, the amount of die-roll formation increased as the bridge width increase and it was constant at the bridge width of over 15 mm.

Grinding characteristics of mould steel with micro 3D structure in ultrasonically assisted precision grinding

This study aims to develop a high precision machining method for difficult-to-machine materials with micro 3D structure. For this purpose, ultrasonically assisted on-surface grinding technique has been proposed and experimental investigations involving difficult-to-machine material workpiece with micro strait ribs of several hundreds μm in width have been carried out using metal bonded diamond wheels. As a result, manufacturing of mirror surface on micro 3D structure can be achieved easily and the grinding forces are decreased by ultrasonically assisted grinding. Additionally, the correlation of the grinding characteristics and with the wheel surface topography during grinding process has also been demonstrated. The obtained results indicate the ultrasonically assisted grinding is extremely effective for high precision machining of difficult-to-machine materials with micro 3D structure.

A022 Surface Topography of Small Diameter Diamond Wheel in Ultrasonic Assisted Grinding

This paper aims to evaluate small diameter diamond grinding wheel surface topography in ultrasonic assisted grinding (UAG) process quantitatively and demonstrate the effect of the topography on grinding characteristics. In this study, a scanning electron microscope with four electron probes (3D-SEM) was used for 3D observations of the wheel working surface in on-surface UAG process. From these results, good wheel surface maintained in UAG process have been evaluated quantitatively by the number and the area of cutting edges. Additionally, these results are closely concerned to the low grinding forces and manufacturing of mirror workpiece surface easily, respectively.

Study on Ultrasonic-Vibration Milling Process (1st Report)-Investigation of Fundamental Cutting Performance and Application to Small-Diameter Ball-Nosed End Milling Process-

In this study, the authors investigated to improve the cutting performance of the milling process using a small-diameter ball-nosed end mill. The problems associated with this milling process are as follows: First, the shape accuracy and surface integrity of products and the tool life can easily be rendered inferior because of the occurrence of bending or vibration of the end mill owing to low rigidity of the tool. Second, a high level of surface roughness of the surface cut by the center web of the and mill can easily occur, because the cutting capacity of this cutting edge is poor and the cutting speed is low. In an effort to solve these problems, the authors investigate a countermeasure in which ultrasonic vibration is applied during end milling process. As results, bending of the small-diameter end mill is prevented, the shape accuracy and surface integrity of products are improved, and also the tool life is lengthened by ultrasonic end milling in which the end mill is axially vibrated with ultrasonic frequency. Thus, it is believed that ultrasonic-vibration milling is effective in the improvement of the cutting performance of the milling process using the small-diameter ball-nosed end mill.