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Journal Article

Thermal Analysis of Traction Contact Area Using a Thin-film Temperature Sensor

The purpose of this paper is to construct the thermal analysis model by measuring and estimating the temperature at the traction contact area. For measurement of temperature, we have used a thin-film temperature sensor. For estimation of temperature, we have composed the thermal analysis model. The thin-film temperature sensor was formed on the contact surface using a spattering device. The sensor is constituted of three layers (sensor layer, insulation layer and intermediate layer). Dimensions of the sensor were sufficiently smaller than the traction contact area. The sensor featured high specific pressure capacity and high speed responsiveness. The thermal analysis model was mainly composed of three equations: Carslaw & Jaeger equation, Rashid & Seireg equation and heat transfer equation of shear heating in oil film. The heat transfer equation involved two models (local shear heating model at middle plane, homogeneous shear heating model).
Technical Paper

Development of Sealing Material Used in the Body Welding Shop

1 The principal characteristics required of sealing materials used in the body shop have focused on their adhesion to oily steel sheets and quick curing performance. Means for attaining these characteristics have been narrowed down to a basic resin system and a curing system. Various techniques have been studied to ensure proper anti-corrosion performance at the sealer application boundaries and thin application areas. They include the addition of anti-corrosion fillers, the provision of conductivity (through electro-deposition), and the application of a micro foam film over the application boundaries. Thus, prospects for attaining the same level of anti-corrosion performance as existing materials have been achieved.
Technical Paper

Experimental Analysis of Acoustic Coupling Vibration of Wheel and Suspension Vibration on Tire Cavity Resonance

It is difficult to improve tire cavity noise since the pressure of cavity resonance acts as a compelling force, and its low damping and high gain characteristics dominate the vibration of both the suspension and body. For this reason, the analysis described in this article aimed to clarify the design factors involved and to improve this phenomenon at the source. This was accomplished by investigating the acoustic coupling vibration mode of the wheel, which is the component that transmits the pressure of cavity resonance at first. In addition, the vibration characteristic of suspension was investigated also. A speaker-equipped sound pressure generator inside the tire and wheel assembly was developed and used to infer that wheel vibration under cavity resonance is a forced vibration mode with respect to the cavity resonance pressure distribution, not an eigenvalue mode, and this phenomenon may therefore be improved by optimizing the out-of-plane torsional stiffness of the disk.
Technical Paper

Development of a Method to Predict the Rupture of Spot Welds in Vehicle Crash Analysis

This paper describes a new method to predict the rupture of spot welds, suitable for vehicle crash simulation. In a crash simulation used for vehicle development process, the calculation is performed assuming that the spot welds in the vehicle do not rupture. However, if some spot welds rupture in test of a prototype vehicle, the simulated deformation and test deformation may not match, resulting in inaccurate estimation of deformation from simulation. Therefore accuracy of predicting the rupture of spot welds is crucial in accurately estimating the deformation and improving reliability of vehicle crash simulation results. The new method to predict the rupture of spot welds which relates axial and shear forces and bending moment of spot weld to stress around nugget has been developed by authors. Based on developed method, the rupture risk of spot welds has been estimated. The new method was applied to estimate the spot weld rupture using three types of specimens.
Technical Paper

A Robustness-Focused Shape Optimization Method for Intake Ports

Merging a CAE shape optimization system and a concept Taguchi method SN-ratio index, a robustness-focused automated shape optimization method has been developed. Applying this method to diesel intake ports, with mold position tolerance set as the error factor, SN-ratio was defined for swirl stability. As a result of the optimization provided by a multi-objective genetic algorithm, simultaneous improvement of flux, swirl rotation and SN ratio was achieved.
Journal Article

Narrow-Band Omnidirectional Structural Color

Automotive pigments consist of absorptive materials which absorb most of the wavelengths of light in the visible range (400-800 nm) except one particular range which gets reflected and seen as color. This coloring mechanism based on light absorption due to their molecular structure generally reflects a broader range of wavelength with a moderate reflectivity (50-60%). However in nature we find many magnificent colors in insects, butterflies, birds and fishes. These colors in nature are not based on the abortive pigments, but on the nanoscopic regular structures that interfere light reflected from those periodic sites. Since animals contain no solid metals, to produce metallic-like reflections they also rely on interference of light.[1] Most common and well-known form of animal reflector is the multilayer type where alternating high and low refractive index layers are formed. Such nanostructure assembly can reflect light up to 100%.
Journal Article

Development of Hardening Depth Evaluation Technique using Eddy Current – Establishment and Introduction of In-line Hardening Depth Inspection System –

A hardening depth evaluation technique using eddy current has been developed, which can be applied to a mass production line for destructive (cutting) inspections. Using this technique, changes in the hardness of the induction-hardened structure can be detected based on the changes in magnetic permeability. This technique reduces the thermal effect and improves measurement accuracy through a multi-frequency exciting method and a difference method algorithm.
Technical Paper

Analysis of Degradation Mechanism of Lead-Free Materials

The use of lead-free (Pb-free) solder and plating in onboard electronic components has accelerated rapidly in recent years, but solutions have yet to be found for the issues of whisker generation in tin (Sn) plating and crack initiation in Pb-free solder, despite widespread research efforts. Analysis of the whisker generation mechanism has focused on internal energy levels and crystal orientation, and analysis of the crack initiation mechanism in Pb-free solder has examined changes in the grain boundaries of Sn crystals.
Technical Paper

Development of Robot Control Method for Curved Seal Extrusion

The glass-integrated Curved Seal Extrusion (hereafter called “CSE”) is a new technology for manufacturing automobile-window mole. This technology is to extrude and stick mole directly on 3-D shaped window-glass by using the combination of a multi-axes robot and an extruding machine. This process could not be realized through the previous robot technology whose primary purpose was transporting goods, which did not necessitate real-time speed control. This time, we adopted a robot for the purpose of processing plasticity molding. For the purpose of improving formability, productivity, and appearance quality, we optimized the robot's movements and devised a method to vary the molding speed of the extruding machine. Furthermore, we have established a mass production technology by developing the optimum robot control method.
Technical Paper

Metallic Powder Coating for Aluminum Wheels

From the viewpoint of measures for environmental issues, the amount of solvents in paint for aluminum wheels needs to be minimized. Environmentally friendly powder coatings have been used widely for primer coating and clear coating, but there is no precedent for its use for base coating. This time, we optimized the condition of surface treatment of pigment and hardening behavior of constituent resin in the melting process and succeeded in developing a metallic powder coating for aluminum wheels that fulfills the appearance and the quality requirements of aluminum wheels.
Technical Paper

Development of New Sound Insulator Damping Coat

Presently, asphalt sheets are utilized as a sound insulator for floor panels. However, there is a rising demand for the development of a totally new sound insulator twofold: to meet weight reductions and to improve the manufacturing process. In order to meet these criteria, unique sprayable material, which exhibits highly stable insulation performance over a broad temperature range, was developed. Liquid sound dampers are the next-generation in sound insulation material, which not only exhibits high sound insulation performance for an insulator, but also raises expectations for radical weight reductions due to its dynamic application capabilities.
Technical Paper

Integrated Robot System Operation for Achieving High Productivity

The integration of robot system operation is the most important and interesting issues for robot end users. Increasing robot operations by a growing variety of robots, applications, and models is a serious problem in maintaining high productivity and reducing maintenance cost. In the practical development of the Toyota global body assembly line (GBL), we designed a special robot operation and man-machine interface system based on the experience of robot operators. The Toyota Integrated Robot Operation System (IROS) offers remarkable advantages in the application of practical body assembly lines.
Technical Paper

Joining Technologies for Aluminum Body-Improvement of Self-piercing Riveting

The experimental research vehicle ES3 body was realized by using various aluminum-joining technologies: MIG welding, laser welding, self-piercing riveting. These technologies were applied selectively to make full use of their individual characteristics, according to the body structure and joined materials. Of these technologies, self-piercing riveting is advantageous in several respects. Aiming to expand the application range of riveting technology, we developed a die that prevents cracks in joining aluminum casting, and a method to improve rivet driving in thick, multi-pile portion. We further studied the feasibility of aluminum rivets. This paper outlines the ES3 body structure and it's joining technologies used and introduces the further improvements we developed concerning self-piercing riveting.
Technical Paper

New Frictional Testing Method for Stamping Formability - Development of Dr. STAMP (Direct & Rapid, Surface Tribology Analyzing Method for Press) Method -

Galvannealed steel sheet (GA) is very extensively used for vehicle panels. However ζ-phase (FeZn13) in GA coat causes poor stamping formability. Previously, there were no easy methods to evaluate the influence of ζ-phase on the frictional characteristics other than the X-ray diffraction method. This study will discuss the development of a new testing method: Dr. STAMP Method that is both efficient and convenient with pin-on-disc tester.
Technical Paper

Fatigue Life Prediction Method for Laser Screw Welds in Automotive Structures

This paper describes the development of a fatigue life prediction method for Laser Screw Welding (LSW). Fatigue life prediction is used to assess the durability of automotive structures in the early design stages in order to shorten the vehicle development time. The LSW technology is a spot-type joining method similar to resistance spot welding (RSW), and has been developed and applied to body-inwhite structures in recent years. LSW can join metal panels even when a clearance exists between the panels. However, as a result of this favorable clearance-allowance feature of LSW, a concave shape may occur at the nugget part of the joint. These LSW geometric features, the concavity of nuggets and the clearance between panels, are thought to affect the local stiffness behavior of the joint. Therefore, while assessing the fatigue life of LSW, it is essential to estimate the influence of these factors adequately for the representation of the local stiffness behavior of the joint.
Journal Article

Development of Fracture Model for Laser Screw Welding

This paper describes the development of a fracture finite element (FE) model for laser screw welding (LSW) and validation of the model with experimental results. LSW was developed and introduced to production vehicles by Toyota Motor Corporation in 2013. LSW offers superb advantages such as increased productivity and short pitch welding. Although the authors had previously developed fracture FE models for conventional resistance spot welding (RSW), a fracture model for LSW has not been developed. To develop this fracture model, many comprehensive experiments were conducted. The results revealed that LSW had twice as many variations in fracture modes compared to RSW. Moreover, fracture mode bifurcations were also found to result from differences in clearance between welded plates. In order to analyze LSW fracture phenomena, detailed FE models using fine hexahedral elements were developed.
Journal Article

Development of Paint Booth: “New Paint Mist Collection Method”

1 Inside a paint booth to spray paint on vehicle bodies, bumpers, and other parts (hereinafter referred to as “works”), air whose temperature and humidity are controlled by air-conditioner is supplied by blower fans through filters. Dust-eliminated and regulated air flow is sent downward from top to bottom (hereinafter referred to as “downflow”) in the painting booth. Conventionally, paint which does not adhere to work in spraying (hereinafter referred to as “paint mist”) is collected while flowing at a high speed through a slit opening called venturi scrubber in a mixture of air and water. However, this mist collecting system using venturi scrubber requires a large space with a large amount of pressure loss while consuming substantial energy. By radically changing the mist collecting principle, we developed a new compact system with less pressure loss aiming to reduce energy consumption by 40% in a half-size booth.
Technical Paper

Development of Hybrid Model for Powerplant Vibration

This paper covers the application of hybrid vibro-acoustic simulation methods to shorten the design cycle of power-plant components. A comparison is made between Frequency Response Function based and Modal based algorithms for the generation of a predictive powerplant assembly model. The effectiveness of design modifications is evaluated by loading the original and modified predictive models with experimentally identified excitation forces. The procedure is validated by correlation with experimental data.
Technical Paper

Silicon Nitride Turbocharger Rotor for High Performance Automotive Engines

Toyota Motor Corporation has mass-produced turbochargers with silicon nitride ceramic rotors since October, 1989. Those turbochargers have been introduced into Celica and MR-2 which are Toyota sporty-type passenger cars. The designing of ceramic rotor was carried out in order to ensure the strength and durability of the component as well as to obtain the same aerodynamic characteristics as in the metal rotor. A moment of inertia was reduced by 60% using ceramic rotor which improved turbocharger response. The ceramic rotor was joined to metal shaft by new method which compensated problems in both shrink fitting and active brazing methods. High temperature strength of silicon nitride material was improved by controlling the amount of sintering additives and sintering conditions. The ceramic injection moulding was employed to mass-produce rotors with complicated shape, applying optimun binder compositions and moulding conditions.
Technical Paper

Development of New Headliner Material and the Manufacturing Process

A molded headliner made from polypropylene, which we developed for the first time in the world, was adopted in May 1987 for TOYOTA COROLLA. The new material with high stiffness and light weights, has a sandwich structure consisting of PP-sheets and a PP-foam sheet. We have thus succeeded in the production of the new headliner in which each layer is laminated without any adhesive. A unique resin used for PP-sheets as surface skins was developed with high impact, thermal and fire resistances. Further, a PP-form core sheet with soft-feel and good moldability was also developed. As a result, we established proper conditions of molding this material and succeeded in producing stable superior parts with high quality and short cycle-time. Finally new molded headliner is comparable to the suspended type headliner in respect to weight and production cost.