Experimental report on use of additive technologies in special vehicles development.

Valentan, Bogdan ; Brajlih, Tomaz ; Drstvensek, Igor 等

Abstract: Field of special vehicles is a rapid growing and rapid changing field of industry. When we need to produce a large number of different parts, we meet modern additive technologies. Use of additive technologies helps us to produce random parts at very reasonably price in less time then usually. Lack of materials and advanced manufacturing technologies were reason, that in past years additive technologies were not used in development and production of special vehicles. This paper presents usage of additive technologies in development of hybrid powered vehicle.

Key words: additive technologies, special vehicles, rapid manufacturing, advanced manufacturing.

1. INTRODUCTION

Automotive industry these days has some problems with response on daily problems like environment pollution and high fuel costs. At this point any debate why this is so is pointless but this position is a good opportunity for smaller more flexible undertaking that can start with small series ecological acceptable vehicle production. Basis is well known from an electrical motor, to assistant human drive and also these days so praised hydrogen fuel cell (which is by opinion of many men only attempt to stay dependent on fix "H 2" stations). Paper will present some new approach in developing parts for one of these "future" vehicles.

2. ADDITIVE TECHNOLOGIES

Additive technologies are this days known as the "technologies of the future". Each day a more and more different technologies are presented, and many more are in development. In the basic principle Additive technologies is nothing more, then building a part by layers. It started with SLA (Leong, K.F. 1993), which is still one of the typical presenters. Through time different materials were needed and so different variations were developed. Now, development is concentrated in producing finished parts from several materials from plastic to metal (steel, titanium ...).

3. HYBRID VEHICLE DEVELOPMENT

In development of new vehicle we need to develop some parts, which are standard, but unique for every vehicle. In this paper development of four major parts will be presented:

Steering mechanism

Transmission

Force measuring

Bodywork.

3.1 Steering mechanism

Standard steering mechanism is a well known Ackerman mechanism that is commonly used in almost every of today's cars. Ackerman mechanism has some issues, it does not steer vehicle on ideal path and it needs bar that uses space between booth steering wheels. Our solution is steering by Bowden cables. Bowden cables were used for steering at very beginning of automotive industry, but were replaced by Ackerman mechanism because used ropes were not stiff enough for stable driving. Presented solution (Drstvensek et al. 2005) uses new stable steel ropes, and better solution for guidance of steel rope. For mould pattern PolyJet[TM] part (Figure 1) was used and small series was made with SRM (Drstvensek et al. 2005) and IC (Efunda, 2007) process (Figure 2).

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3.2 Transmission

Transmission in a car is optimized on vehicle weight and produced torque. In super light hybrid vehicle we cannot use standard transmission, since we need more gears and less weight. Since our vehicle (Valentan, 2006) has two wheels in front and one in rear we head some options:

* Rear wheel drive

* 3x3 drive

* Front wheel drive.

Decision on rear drive combined with transmission from mountain bike and some parts from scooter did prevail. Some parts in construction were made on a SLM machine (Rehme et al., 2007) directly from stainless steel (Figure 3). Rapid prototyping machines for metal part production are still relatively new and development is still running at high speed.

3.3 Force measuring

Vehicle has a hybrid drive. Secondary electric drive (el. motor and storage battery) and primary human powered drive (bicycle like). Fore intelligent regulation of primary drive force measuring was implemented in vehicle frame. Measuring spot was defined with FEA simulations (Figure 4).

3.4 Bodywork

Bodywork is crucial component that has a function of protection from weather influence and is one of the most important parameters in attracting customers. All components were designed in CAD software Catia V5, which is a splendid tool for a free form design; on the other hand, man must be a designer to produce great looking part, so our project has here some room to improve. 1:10 scale model was build by PolyJet[TM] procedure (Figure 5) for shape evaluation and some further aerodynamic tests in wind tunnel.

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4. CONCLUSION

Some major advantages of using modern additive technologies must be pointed out. First: For prototype and small series production this production techniques produced much cheaper parts in extreme short times (from CAD model to part in couple of hours). Second: These parts are fully applicable and have the same property (quality) than the parts produced by conventional production methods. Third: With those parts we can make final test on components and so in real life (not only in CAD model) confirm or deny our thesis.

5. REFERENCES

Leong, K.F., Rapid Prototyping and Manufacturing: Fundamentals of Stereo lithography, McGraw Hill (New York) 1993.

Drstvensek, I., Drstvensek, S., Valentan, B., Balic, J. Mathematical background of development of steering mechanism for human powered vehicle. V: KYTTNER, Rein (ur.). Proceedings of the 5th International conference of DAAAM Baltic, Industrial engineering--adding innovation capacity of labor force and entrepreneur, Tallinn, Estonia. Vienna: International DAAAM; Tallinn: DAAAM Baltic, cop. 2006, p. 25-28.

Drstvensek, I., Brajlih, T., Klenovsek, M. Casting of intake pipes by silicone rubber molding. V: GYENGE, Csaba (ur.). Annals of MTeM for 2005 & Proceedings of the 7th International conference Modern technologies in manufacturing, 6th -8th October 2005, [Cluj-Napoca]. Cluj-Napoca: Technical university, Faculty of machine building, Department of manufacturing engineering, 2005, p. 195-198.

Investment Casting, Available from: http://www.efunda.com/processes/ metal_processing/invest_ casting.cfm, 2007-06-05

Valentan, B. Development of hybrid drive vehicle with flexible regulation of torque of assistant drive. V: OLABI, Abdul Ghani (ur.). VAFSEP 2006 : proceedings of the International conference on vehicles alternative fuel systems & environmental protection, Dublin: Dublin City University, cop. 2006, p. 192-197, ISBN 1-872327-58-3

Rehme, O; Schwarze, Dieter; Ritt, Stefan; Emmelmann, C. (2007). Selective Laser melting of customized implants with cellular surface structures for optimized elasticity and improved Osseo integration, In: The 1st DAAAM International Specialized Conference on Additive Technologies, Ed. Igor Drstvnsek, Branko Kataliniae, p. 4952, DAAAM International, ISBN: 3-901509-61-5