Laser-based manufacturing concepts for efficient production of tailor welded sheet metals

Advances in Manufacturing, Sep 2014

Laser welding is an established manufacturing technology for a large variety of automotive applications due to its attractive properties such as low heat input, high precision and fast welding speed. Especially when welding high strength steels, which are dominantly used in today’s car body construction, the low heat input by laser welding bears significant advantages with regard to the properties of the weld seam. The exploitation of the full application potential of laser welding in mass production requires an appropriate manufacturing concept and corresponding auxiliary technologies. The present paper demonstrates the integration of laser welding into the surrounding manufacturing concepts by a modular setup with different levels of automation. This approach offers flexible solutions for individual needs thereby optimizing investment cost, labor cost and productivity. Recently available laser sources enable exceptionally high welding speed on thin gauged sheet metals but require efficient material handling concepts to utilize the full speed potential. Industrial concepts are presented offering efficient material handling and high process robustness for mass production welding.

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Laser-based manufacturing concepts for efficient production of tailor welded sheet metals

Marius Spottl 0 1 Hardy Mohrbacher 0 1 0 H. Mohrbacher (&) NiobelCon bvba, Schilde, Belgium 1 M. Spottl WISCO Lasertechnik GmbH, Ravensburg, Germany Laser welding is an established manufacturing technology for a large variety of automotive applications due to its attractive properties such as low heat input, high precision and fast welding speed. Especially when welding high strength steels, which are dominantly used in today's car body construction, the low heat input by laser welding bears significant advantages with regard to the properties of the weld seam. The exploitation of the full application potential of laser welding in mass production requires an appropriate manufacturing concept and corresponding auxiliary technologies. The present paper demonstrates the integration of laser welding into the surrounding manufacturing concepts by a modular setup with different levels of automation. This approach offers flexible solutions for individual needs thereby optimizing investment cost, labor cost and productivity. Recently available laser sources enable exceptionally high welding speed on thin gauged sheet metals but require efficient material handling concepts to utilize the full speed potential. Industrial concepts are presented offering efficient material handling and high process robustness for mass production welding. 1 Introduction Laser welded steel blanks have made a remarkable evolution from rather infrequent applications at the end of the 1980s to an indispensable semi-product in todays automotive body design. Within a decade, the design of laser welded blanks has evolved from very simple to rather complex layouts in order to comply with the continuously increasing challenges of weight reduction, engineering properties and cost [1]. Over the same period of time, companies active in this market and have developed various laser welding production concepts and related subtechnologies. Meanwhile, many of these have disappeared again since only those allowing to manufacture a superior product in terms of cost, quality and flexibility could survive in this highly competitive market. Principally two fundamental production concepts have been established. One concept uses a fixed laser head and moving the material along the head. The other concept moves the laser head over the material being in fixed position. Besides, hybrid concepts moving the head as well as the material in a coordinated way have also been realized for particular applications. Two key aspects control the optimization towards higher productivity and accordingly lower manufacturing cost: (i) material handling time and (ii) welding speed. A further important aspect towards reducing cost is to lower the part specific investment into tooling. For laser welding this concerns cutting dies as well as material handling and clamping devices. All these aspects have to be considered in combination when designing a welding machine for a particular application or market. Furthermore it is necessary to enhance process robustness to provide weld seams of consistently high quality. The operating window of stable processing conditions becomes smaller at higher welding speed. Therefore an innovative welding technology has been developed increasing process robustness without sacrificing welding speed or increasing heat input. 2 Laser welded blank production concepts For laser welded blank production various manufacturing concepts are used in the industry [1, 2]. These production concepts are the result of different production strategies and also of rapid parallel technology development by different players in the market. A production concept is basically characterized by way of achieving a relative displacement of laser beam and sheet material as well as by the manner of managing the material flow through the process. The driving forces behind any welding machine concepts are maximization of the utilization of the laser welding equipment, the optimization of production flexibility and the reduction of cost. Fixed-optics laser welding systems are characterized by a stationary welding head while the sheet assembly to be welded is passing underneath (see Fig. 1). This technology allows producing straight weld seams (see Fig. 2). Moving optics systems represent the opposite approach where the sheets to be welded are at rest while the laser welding head is executing a linear or free form trajectory (see Fig. 3). In this way weld seams of arbitrary shape such as circular, curved or angular ones can be made. The technology also allows producing complex blank assemblies, as shown in Fig. 4. Considering the part spectrum in todays automotive market, the vast majority of blanks require straight weld seams connecting two or three individual sheets. For the production of single straight welded assemblies, machines equipped with fixed optics are clearly the method of choice. Each additional straight weld in a blank design requires a corresponding additional pa (...truncated)


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Marius Spöttl, Hardy Mohrbacher. Laser-based manufacturing concepts for efficient production of tailor welded sheet metals, Advances in Manufacturing, 2014, pp. 193-202, Volume 2, Issue 3, DOI: 10.1007/s40436-014-0088-8