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Technical Paper

Laser Welding of EGR Coolers - A New Process Technology for Heat Exchanger Manufacturing

2001-05-14
2001-01-1753
Laser welding is a joining process, which is comparatively new to industrial production and especially to heat exchanger manufacturing. Due to the high energy density of the laser beam, the process is characterized by faster welding speeds with deep penetration as compared to the conventional welding processes. Therefore laser welding technology is widely used in the automotive industry on a variety of different applications. This paper describes the application of laser welding as possible joining technology for exhaust gas heat exchangers made of stainless steel. The cooled exhaust gas recirculation (EGR) technology shows good potential for meeting the actual and future emission targets of diesel engines combined with acceptable fuel consumption. It will be shown that the selection of the base metal and the joining technology are extremely important for the durability of the product because of the severe operating environment the EGR cooler must endure.
Technical Paper

The Effect of Process Damping On Stability and Hole Form in Drilling

2001-09-10
2001-01-2605
A dynamic model of drilling is used to study the effects of process damping on tool stability and hole form. The formulation leads to an eigenvalue problem yielding cutting speed and depth of cut combinations that produce borderline stable solutions to the equations of motion. The addition of process damping is seen to lead to the instability of low-frequency modes that resemble those found in practice.
Technical Paper

Machined Component Quality Improvements Through Manufacturing Process Simulation

2001-09-10
2001-01-2607
New manufacturing technologies such as high speed machining (HSM) are being developed to produce high quality aerospace components. While our developing understanding of machining dynamics is enabling precise control of cutting tools to provide for high dimensional accuracy, residual stresses present in aluminum mill products can compromise the ability to machine dimensionally accurate components from these stock materials. The advantages of precise tool control can be lost if the metal being cut moves during machining. And, even a perfectly machined part that distorts when it is released from the machine bed will cause problems upon assembly. Thus, ensuring the quality of the mill product becomes an enabling technology for advanced manufacturing approaches such as HSM.
Technical Paper

Frequency Response Measurement of Cutting Tools for Aerospace Applications

2001-09-10
2001-01-2606
In order to increase the metal removal rates and productivity of cutting tools in aerospace applications, it is important to understand the dynamic characteristics of the machine-tool-workpiece combination, typically expressed as a Frequency Response Function (FRF). It is exactly the lack of this understanding that leads to problems with chatter, for example. Many users of machine tools find the measurement procedures and the computations difficult, and they do not perform them. While considerable progress has been made in easing the computational burden only recently has the measurement become easier. This paper describes 2 new techniques which reduce the skill level required to make the measurement
Technical Paper

Using Mass Balance Techniques to Manage Nutrition of Hydroponically-Grown Sweetpotato [Ipomoea batatas (L.) Lam]

2001-07-09
2001-01-2274
A mass balance nutrient management approach was used in controlled environment studies, to determine an appropriate nutrient solution replenishment regime for the growth of sweetpotato in nutrient film technique (NFT). Four stem cuttings (15-cm long) were planted into each of three gray PVC-1 (0.15×0.15×1.2 m) troughs in a walk-in growth chamber under a 14/10 h photoperiod, 28/22°C and 70% relative humidity. Photosynthetic photon flux at canopy level averaged 450-μmol m−2 s−1. Plants were grown with a modified half-Hoagland starter solution with an extra 3 mM of N for the first 4–6 weeks to accelerate vegetative growth, after which three refill solutions containing 1.5 (A), 4.5 (B), 0.75 (C), or 3 (A), 4.5 (B), and 6 (C) mM NO3−1-N and K, respectively, were used once per week until harvest. The level of N and K in the refill solutions did not significantly influence the number of storage roots produced.
Technical Paper

Water Condensate Retention and “Wet” Fin Performance in Automotive Evaporators

2001-03-05
2001-01-1252
Water condensate retained inside an automotive evaporator has remained as one of the primary sources of unpleasant “odors”, which in turn can drive up the warranty cost for automotive manufacturers. The “wet” evaporator fin can also underperform due to the presence of condensate blocking the air passage. Moreover, condensate retention can be a potential factor of freezing up evaporators. Thus, an evaporator fin must be designed such that it can shed and drain water condensate as well as provide an excellent heat transfer capability. While the importance of water retention is well known, there seems lacking of a comprehensive way to evaluate the water retention characteristics of a particular product. In this work, attempts were made to answer four questions: (1) What is the mechanism that controls water condensate retention characteristics in an automotive evaporator? (2) Can different water retention evaluation methods reveal the same characteristics?
Technical Paper

Force Response during Tire Tread Detachment Event

2004-03-08
2004-01-1075
A series of tests were conducted utilizing a tire test machine built to measure forces during a tire tread separation event. Tires were prepared by cutting between the two steel belts inward from the shoulder area. Cuts were varied in size and location to generate different types of tread separation events (ex: long, short, partial, inboard, and outboard). The tests document the longitudinal and lateral forces generated while the tread is detaching during different types of tread separation events. The results demonstrate that magnitude and duration of forces depend upon the nature of the tread separation event. Additional documentation includes high speed and real time video of the tread separation events to provide insights into tread detachment modes and mechanisms of measured force response.
Technical Paper

Ballistic Armoring of Passenger Cars on the Assembly Line Adds Quality and Passengers Comfort by Using Advanced and Light Weight Composite Materials

2004-03-08
2004-01-1518
Light weight composite materials were developed to provide ballistic protection to automobiles against handgun bullets and to increase passengers comfort by the elimination of UV radiation and reduction of infra-red solar energy and interior noise, without compromising the driving performance of the car. Structural designs were incorporated to be able to armor the car on the assembly line with the added benefits of turn-over time, cost reduction and quality of the finished assembly. Weight reduction of armor materials have been achieved with CrystalGard® and YellowGard®. For windows and windshield, CrystalGard® 17mm provides better ballistic protection against NIJ Level IIIA with a 27% weight reduction than the standard 21mm glass solution by using a double layer of polycarbonate. SolarBlock® eliminates the UV radiation and reduces 95% of the infra-red solar energy for added passengers comfort.
Technical Paper

Development of Non-Lead-Added Free-Cutting Steel for Automobile Parts

2004-03-08
2004-01-1526
A new, free-cutting steel, hereafter referred to as “non-lead-added free-cutting steel”, has been developed with the intention of replacing currently applied lead containing free cutting steel. The ultimate goal of this project is to provide a new lead-free steel grade that will contribute to the removal of environmentally harmful substances from automobile parts. In this project, we have targeted the development of a material that would demonstrate levels of machinability and other mechanical properties equivalent to those of the conventional free-cutting steel to which sulfur (S), lead (Pb) and calcium (Ca) or combinations, thereof have been added. The fine dispersion of sulfide, modified by adding Mg and Ca, is most effective in enhancing the chip breakability that would otherwise deteriorate due to the absence of lead. The practical application of the non-lead-added free-cutting steel has rendered the goal of total removal of lead from special steel products highly obtainable.
Technical Paper

Orbital Drilling - Implementation and Evaluation

2004-09-21
2004-01-2813
This paper deals with issues about Orbital drilling implementation and evaluation. The paper summarizes and includes the so far written papers about Orbital drilling. In a previous paper, a conclusion was made, orbital drilling is a suitable method for drilling high quality holes in the specific space application that was studied. The conclusion for further development was then to look more specifically into the process development, i.e. cutting parameters, new cutters, new coatings on cutters etc. Then the investigation and feasibility study started. The project went from early prestudy to fully implemented industrialized solution of the PODU at SAAB Ericsson Space (SES) in Linköping, Sweden. More detailed description on how the project did it is explained in the paper. The early conclusions made after pre- and final acceptance tests of the PODU at SES shows that Orbital drilling is a comprehensive method compared to conventionally drilling methods.
Technical Paper

The Surface Analysis of Powder Metallurgy (P/M) Components Machined by Diamond-Like Carbon (DLC) Coating Cutting Tools

2003-03-03
2003-01-0452
The surface analysis is one of the most important factors of the metal machining process due to the tolerance and geometry requirements. The characteristic of powder metallurgy (P/M) surface geometry is the main issue here, because the porous structure affects the surface quality. A discontinuous cutting path and some vibration occur when cutting tool passes from the edge of one pore to that of another. The amorphous material such as Diamond-like carbon (DLC) coating has been applied on the cutting inserts to improve the machinability. This paper will evaluate the surface finish of the P/M components by employing a DLC cutting insert. Due to the specific physical properties of DLC coating, it is important to understand the effects of DLC coated insert on the surface roughness at different cutting speeds and feedrates. This work investigates the factors of friction between the cutting tools, workpiece and observes how the coating material affects the finish surface.
Technical Paper

Estimation of Engine Combustion Parameters Under Induction Coil Disturbances

2003-03-03
2003-01-1054
The paper outlines a possible approach to disturbance compensator design for the combustion diagnostics systems using sensors affected by the ringing disturbances originated from the electronic hardware containing the induction coils. The compensaton is based on the semi-physical approach. The advantage of the given compensation method compared with cutting techniques is demonstrated for a generic combustion LS estimation system in terms of comparative analysis of estimation results with and without compensator.
Technical Paper

Relation Between Aluminum Die-Casting Conditions and Dimensional Stability

2003-03-03
2003-01-0830
High dimensional accuracy of die-cast part enables net-shape forming or machining reduction. That is one of the strategies to get sharp cost cutting in any aluminum die-casting applications, including engine and power train parts of automobile. However, it had been difficult to specify the key technology for dimensional stability. This project has digitized relation between manufacturing conditions and dimensional stability by a dynamic analysis, based on transferability theory of Quality Engineering1). The most important factor has been die-cast part's temperature at ejection, taking error of mass production in account. If we kept the temperature constant, we could die-cast a part with equivalent accuracy to a die.
Technical Paper

Development of Automatic Road Repair Vehicle - Field Robot

2002-03-19
2002-01-1447
A serious issue in road surface repair is the need to work in narrow streets and the corresponding difficulty of doing a good job. At present, this type of work is extremely time-consuming and expensive and the repairs do not last long enough. In this study, we developed a field robot that implements a new concept for the fast cutting and shaving of pavement. Movement in a narrow space is facilitated by a newly developed special steering device that enables turns from 30°to the right to 90°to the left. This field robot is a promising tool that should speed up and automate the cutting of pavement for maintenance and repair.
Technical Paper

PVD-Wear Resistant Coatings of Homogeneous and Graded Ti(C,N): Residual Stresses and Mechanical Performance under Hertzian Load

2002-03-19
2002-01-1407
Ceramic protective coatings on cutting tools for steel machining are state of the art in industrial applications. Several concepts to improve the efficiency of machining processes as for instance high-speed or dry cutting yield increasing demands regarding the wear and corrosion resistance of the protective tool coatings. The generic process characteristics of PVD-coating techniques offer opportunities to tailor the coatings in terms of microstructure and residual stress states by adjusting appropriate process parameters. Besides chemical composition and microstructure the residual stresses in the coatings strongly influence their in-service performance and, are therefore important to assess and to correlate with process parameters.
Technical Paper

Edge Trimming of CFRP Composites with Diamond Coated Tools: Edge Wear and Surface Characteristics

2002-04-16
2002-01-1526
The work presented here illustrates the wear behavior of CVD diamond coated carbide tools during the machining of carbon fiber-reinforced composites. Cutting experiments were conducted on a CNC milling machine for edge trimming of a 9-mm thick multi-layered carbon fiber-reinforced epoxy laminate in a climb cutting configuration. The effects of feed speed and diamond film thickness on the wear behavior of the coated tools were determined. In addition, characteristics of the worn cutting edge were studied using optical and scanning electron microscopes. It was shown that diamond coated tools generally performed better than the uncoated tools under all conditions. Uniform wear by abrasion of the diamond film, without exposing the substrate, was obtained when cutting at low feed speeds with thicker coatings. At higher feed speeds the wear of the coated tools was characterized by abrasion through the diamond film and exposure and wear of the substrate.
Technical Paper

Advanced Technology in Future Metal Cutting for Airframe Manufacturing

2002-04-16
2002-01-1515
Metal cutting is a substantial constituent of airframe manufacturing. During the past several decades, it has evolved significantly. However, most of the changes and improvement were initiated by the machine tool industry and cutting tool industry, thus these new technologies is generally applicable to all industries. Among them, few are developed especially for the airframe manufacture. Therefore, the potential of high efficiency could not be fully explored. In order to deal with severe competition, the aerospace industry needs improvement with a focus on achieving low cost through high efficiency. The direction of research and development in parts machining must comply with lean manufacturing principles and must enhance competitiveness. This article is being forwarded to discuss the trend of new developments in the metal cutting of airframe parts. Primary driving forces of this movement, such as managers, scientists, and engineers, have provided significant influence to this trend.
Technical Paper

Results of Analytical Modeling of 3-D Machining Processes with Flat Faced Tools

2002-04-16
2002-01-1514
A generalized upper bound model for calculating the chip flow angle in oblique cutting using flat faced tools with single cutting edge and multiple or curved cutting edges has been developed. The chip flow angle and chip velocity are obtained by minimizing the cutting power with respect to both these variables. The chip flow angles predicted by this model show good agreement with experimental values of chip flow angles for various tool geometries and cutting conditions. The model has the potential to be extended to the more complex machining processes such as drilling and milling.
Technical Paper

Simulation of Complex Movement Sequences in the Product Development of a Car Manufacturer

2003-06-17
2003-01-2194
Cutting development times in car manufacturing means bringing forward the knowledge processes. Simulations based directly on CAD data reduce or replace time-consuming hardware loops significantly and therefore make a significant contribution to this. Ergonomic product design is an area that is challenged as far as the further development of virtual methods is concerned. Simulation of the static and quasi-static positions of passengers inside the car is the current state of the art in ergonomic product design. For this reason, interest is strongly focused on the simulation of complex movement processes within the context of enhancing simulation tools. For the car manufacturer, the manner in which people enter and leave the car is of particular interest. Getting into the car is the customers' first actual contact with it. It may also develop into a serious problem for car drivers, as they get older.
Technical Paper

Fast and economic stiffness evaluation of mechanical joints

2003-10-27
2003-01-2751
Car body structures and the joints between beam members have a great impact on global vehicle stiffness. With the method presented in this paper it is possible to experimentally assess the stiffness of joints by a robust and economic means. The stiffness of a beam can easily be found experimentally just by cutting it in two and using the cross-sections to calculate the polar moment of inertia. When it comes to a joint, there are no formulae or explicit expressions describing its behavior. Therefore, measurement of its mechanical behavior has to be made. The dynamic joint method presented here does not need levers or a costly, rigid set-up, but an economical free-free set-up and cast-on weights. Furthermore, the same method can be emulated by FEM when a digital model exists.
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