Tadashi Nishihara

Measurement of Die Temperature During Friction Stir Forming

The authors, focusing on the superb formability and form transfer available through Friction Stir Welding (FSW), have proposed an application for microforging in the form of Friction Stir Forming (FSF). In this study, measurements of the die temperature during FSF of 6061-T6 aluminium alloys are conducted under a range of forming parameters. Surface temperatures of the die are estimated by extrapolation. A maximum die temperature of approximately 740 K is observed.

Cylindrical Pin Embossment on A5083 Aluminum Alloy Substrate Fabricated by Friction Stir Forming

This paper reports friction-stir forming (FSF) of cylindrical pin embossments on JIS A5083 aluminum alloy medium gauge plate. A substrate material was put on an emboss die and conducted friction stirring on its back surface. The die has 1mm diameter and 0.5mm deep fine holes at 1.5mm pitch on its top, and the material successfully filled them due to high pressure and heat caused by friction stirring. Three tools having different shoulder diameter were utilized to investigate the deformable area with a single pass. As a consequence, faster spindle speed, slower tool feed rate, and larger tool shoulder contribute to a wider range of completely formed pins. Extrusion of the material to the die cavity seemed to be mostly limited under the area of the shoulder. The ratios of the band width of the complete pins to the shoulder diameter were increased with the larger diameter of the shoulder of the FSF tool. Therefore, a larger shoulder was more effective for wide-range embossing with a single pass. In addition, we evaluated the shape of formed pins with a non-contact 3D measurement system. Accuracy of the height of the completely formed pins was within ±0.013mm, which was comparable with machining.

Friction Stir Forming of A5083 Aluminum Alloy Gear-Racks with WC Particles Embedded in Tooth Surface

This paper proposes a new forming process for gear racks featuring a tooth-surface stiffening layer. The proposed process is as follows. First, a JIS A5083P aluminum alloy plate on which a surface modifier of WC particles and vaseline paste had been applied was put on a gear-rack die. Next, friction stirring was conducted on the back surface of the plate. The material then deformed and precisely filled the cavity of the die. WC particles were embedded into the surface of the aluminum alloy matrix due to high pressure and heat caused by friction stirring. The forming conditions and the corresponding results, including the distribution of WC perticles on the tooth surface, are investigated in the study. WC particles were embedded near the surface mechanically, and only a very few particles were observed inside the matrix. With an undefill condition, WC particles are concentrated on the rear surface of the tooth, which contacts the tail side of the die. In contrast, No significant particle density differences were observed among the profile of teeth with a fully filled condition in the die cavity.

Friction stir forming for mechanical interlocking of insulated copper wire and Zn-22Al superplastic alloy

In this study, a novel method of friction stir forming (FSF) was conducted for mechanical interlocking of Zn-22Al superplastic alloy and thin copper wire insulated by polyimide. The potential development of a composite material capable of transmitting electrical energy or electric signals was studied experimentally, and it was concluded that FSF can successfully interlock insulated copper wire with Zn-22Al superplastic alloy. The authors suggest the possibility that FSF could join sheets of Zn-22Al alloy by pressure welding and superplastic forming and diffusion bonding (SPF/DB). Trials of FSF were carried out on a modified vertical milling machine. The results are discussed in terms of microstructure observations, hardness distributions, and temperature measurements.

Cylindrical extrusions on A5083 aluminum alloy plate fabricated by friction stir forming

This paper reports fabrication of cylindrical extrusions on an aluminum alloy medium gauge plate utilizing friction-stir forming (FSF). A material plate is placed on the die, and friction stirring is conducted on its back surface. The material deforms due to high pressure and heat caused by the friction-stir process, and the die pattern is transferred precisely. The processes have been mainly focused on mechanical joining and microforming; however, they seem hopeful for bulk products as well. The authors applied the process for generating various bulk-product shapes. In this paper, a 3mm-thick JIS A5083P-O aluminum alloy plate was put on a die having 2-9mm-diameter holes, and friction stirring was conducted on its back surface. The material successfully filled the cavities to form the cylindrical extrusions. The authors investigated the volume, the maximum height with different spindle speeds, tool feed rates, and tool passes. A faster spindle speed and lower tool feed rate were found to contribute to taller extrusions. The maximum height of the extrusions was l5.23mm for the 2mm-diameter hole with spot FSF but without tool traveling, i.e., with 0mm/min tool feed. For holes of less than 5mm in diameter, extrusions produced by spot FSF were taller than those produced by FSF with tool travel because the tool plunge contributes to raising forming pressure. However, for hole diameters exceeding 5mm, extrusions produced by FSF with tool traveling were taller than those produced by the former because tool feeding creates greater material volume.This paper reports fabrication of cylindrical extrusions on an aluminum alloy medium gauge plate utilizing friction-stir forming (FSF). A material plate is placed on the die, and friction stirring is conducted on its back surface. The material deforms due to high pressure and heat caused by the friction-stir process, and the die pattern is transferred precisely. The processes have been mainly focused on mechanical joining and microforming; however, they seem hopeful for bulk products as well. The authors applied the process for generating various bulk-product shapes. In this paper, a 3mm-thick JIS A5083P-O aluminum alloy plate was put on a die having 2-9mm-diameter holes, and friction stirring was conducted on its back surface. The material successfully filled the cavities to form the cylindrical extrusions. The authors investigated the volume, the maximum height with different spindle speeds, tool feed rates, and tool passes. A faster spindle speed and lower tool feed rate were found to contribute to tal...

Production of a Superplastic Vibration-Damping Steel Sheet Composite Using Friction Stir Forming

This study proposes a novel method of manufacturing composite vibration-damping steel sheet with Zn-22Al superplastic alloy using friction stir forming (FSF). Trials of mechanical interlocking of steel sheet with Zn-22Al superplastic alloy using FSF were carried out on a modified milling machine. The results are discussed in terms of residual microstructures and mechanical properties. We concluded that cladding steel sheet with Zn-22Al superplastic alloy using FSF results in superplastic forming and diffusion bonding.

Friction Stir Forming of Aluminum Alloy Gear-Racks

Friction-stir-forming (FSF) of gear-racks of JIS A5083 aluminum alloy is reported in this paper. We put a material plate on a gear-rack die and conducted friction stirring on its back surface. The material deformed and precisely filled the fine cavity of the die due to high pressure and heat caused by friction stirring. This study investigates the forming conditions and the corresponding results, including the material fill ratio in the tooth. It is thought that the deformation volume of the material is key for the fill ratio, and the shoulder diameter of the tool in a single-pass process or the path area in a multi-pass process affects it as well.

Local Manufacture of MMC Using FSW

Friction stir welding (FSW) has been generating interest in association with friction stir processing (FSP), a new technique that employs FSW tooling. FSP is being investigated as a thermo-mechanical processing tool to transform a heterogeneous microstructure into a more homogenous microstructure.However, very little data is available on the use of FSW for processing composite materials. In this study, a novel method of local manufacture of metal matrix composites (MMCs) using FSW is proposed and its application to friction stir spot welding (FSSW) is described. Trials investigating local manufacture of aluminum oxide particulate reinforced 6063 Al by friction stirring were carried out on a modified milling machine. The results are discussed in terms of weldability and residual microstructure.

Shim adjustment and supporting cell relocation with a multipoint supported deep-drawing die

Purpose of this paper is that authors report a new die structure and an adjustment method in comparison with the traditional shim adjustment. The authors developed a multipoint supported die and suggest supporting cell relocation as adjustment method. The authors evaluate distribution of imposed load on supporting cells and their deformation at the slide-stroke-end. They also evaluate product accuracy with a 3D scanner. To make load distribution and height of the cells uniform in a time, we must find some goal function for adjustment to satisfy the above two goals, or develop the dedicated structure and procedure to adjust them in a time. The suggested multipoint support system and supporting cell relocation is one of the methods to adjust them in a time. Numerical simulation should be applied to reduce time of trial blows in future. Suggested die structure is hopeful to carry out more accurate large deep drawings. More and more accurate deep drawings are required today and the suggested die structure will contribute to it. [Received 7 Nov 2005; Accepted 30 Dec 2006]

An experimental study on the dynamic characteristics of cylinder head gaskets for diesel engine: dynamic characteristics in heating and cooling temperature cycle by abrupt change of water during steady operation

Abstract Experiments on a small, one-cylinder high-speed diesel engine were performed by changing the temperature of cooling water and also by changing the material and configuration of the cylinder head gaskets. Three kinds of cylinder head gaskets were made. The temperature was abruptly changed and the temperatures at several points of the cylinder head gasket and its peripheral region, the relative displacement between cylinder head and cylinder block, the loads of the cylinder head bolts, the indicator diagram, the pressure of gasket surface and combustion gas leakage were measured. The sealing characteristics in the transient state and the steady state of the cooling water temperature were investigated from an experimental standpoint. The effect of the temperature differences between the cylinder head, cylinder block and head bolts on the loads of the head bolts and the relative displacement between the cylinder head and cylinder block were observed for the test gaskets.