喜歡就充值下載吧，，資源目錄下展示的全都有，，下載后全都有，dwg格式的為CAD圖紙，有疑問咨詢QQ：414951605 或1304139763 ScienceDirectAvailable online at Available online at ScienceDirectProcedia Manufacturing 00 (2017) 000000 * Paulo Afonso. Tel.: +351 253 510 761; fax: +351 253 604 741 E-mail address: psafonsodps.uminho.pt 2351-9789 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. Procedia Manufacturing 29 (2019) 3693742351-9789 2019 The Authors. Published by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (https:/creativecommons.org/licenses/by-nc-nd/4.0/)Selection and peer-review under responsibility of the organizing committee of SHEMET 2019.10.1016/j.promfg.2019.02.150 2019 The Authors. Published by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (https:/creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the organizing committee of SHEMET 2019.Keywords: Laser Fusion Cutting, High Dynamic Form Cutter, Thin Sheet Metal, Remote Laser Cutting 1. Introduction Fast fusion cutting of thin metal sheets can be conducted by means of CO2 lasers and solid state lasers. A CO2 laser with 1300 W power is utilized to cut various metals with a sheet thickness of 0.2 mm ranging from can steel to aluminum 1. In the case of aluminum and zinc a maximum speed of up to 250 m/min can be achieved as a linear cut with decent cutting edge quality. Fast linear cutting of electrical steel was carried out by means of 2500 W CO2 laser power with maximum speed of 150 m/min for 0.23 mm thick material 2. A single mode fiber laser with 3000 W was * Corresponding author. Tel.: +49-351-83391-3229; fax: +49-351-83391-3300. E-mail address: andreas.wetzigiws.fraunhofer.de 18th International Conference on Sheet Metal, SHEMET 2019 Fast Laser Cutting of Thin Metal Andreas Wetziga,*, Patrick Herwiga, Jan Hauptmanna, Robert Baumannb, Peter Rauschera, Michael Schlossera, Thomas Pindera, Christoph Leyensa,b aFraunhofer IWS, Winterbergstr. 28, 01277 Dresden, Germany bTU Dresden, 01062 Dresden, Germany Abstract Since the emergence of high power single mode fiber lasers cutting velocities of more than 100 m/min can be achieved easily on a straight cut. Results of laser fusion cutting of thin sheet metal with a 2 kW single mode fiber and 4 kW laser will be introduced. Several thicknesses of electrical sheets, aluminium sheets and high strength steel sheets have been cut with maximum speeds of 150 m/min. The cutting quality in terms of cutting edge appearance, burr formation, and kerf width has been analysed. In the case of 2D contour cutting high cutting speeds cannot be accomplished due to steady decelerating and accelerating of the cutting machine. Two alternative concepts will be presented which help to realize high cutting speeds on a contour cut: The first concept shifts the machine movement for filigree structures to high dynamic light weight linear axes whereas the second concept forbears to use cutting gases and allows therefore the usage of galvanometer driven fast mirrors to move the laser beam. 370 Andreas Wetzig et al. / Procedia Manufacturing 29 (2019) 369374used to cut electrical sheet (0.3 mm thickness) up to a speed of 400 mm/min 3. It is reported a burr height of more than 5 m for cutting speeds beyond 200 m/min that can be reduced by a concentric arrangement of the laser beam to the gas nozzle. The present paper will describe the results on linear laser cutting obtained by using both a single mode fiber laser with 2 kW power and a multi mode fiber laser with 4 kW power on electrical sheets, aluminum sheets, and high strength steel sheets. The maximum cutting speed was limited to 150 m/min. However, if it comes to cutting of a real 2D contour the average cutting speeds are limited to 25 m/min regardless of the available laser power and sheet thickness 4. This is due to the limited axes dynamics of a typical 2D flatbed cutting machine 5. However, two different concepts will presented which are overcoming these limitations: The first concept shifts the machine movement for filigree structures to high dynamic light weight linear axes (High Dynamic Form Cutter) whereas the second concept (Remote Laser Cutting) forbears to use cutting gases and allows therefore the usage of galvanometer driven fast mirrors to move the laser beam 6. The basic principles of both concepts will be explained and several examples will be provided in order to demonstrate the chances and limitations of these alternative laser cutting concepts. 2. Fast linear laser cutting 2.1. Experimental setup The kind of cut material is listed in Table 1. The main reason to cut electrical steel and aluminum with the laser is to qualify an alternative cutting technique which will be able to replace the mechanical shearing cut which causes miscellaneous problems like tool wear and surface damage of the band material. Both materials are typical for band material that must be trimmed and cut into strips for further processing in a very fast manner. Due to high hardness the high strength steel can only be cut by means of a contact free tool like the laser. Table 1. Various sheet metal cut with fiber laser. Type of material Thickness m Thickness m Thickness m Electrical steel 200 270 300 Aluminum 300 500 - High strength steel 800 - - Table 2 shows the optical setup of two used lasers including the resulting focal diameter and Rayleigh length which is measure for the depth of focus. These values were only calculated. The ratio of 1:1.25 for example means the ratio of the focal length of the collimation optics to the focusing optics. The goal was to identify the type of laser and the optical setup which provides the best results in terms of speed, quality, and process stability. Table 2. Optical setups used for fast . 2 kW SM Fiber Laser M2 = 1.1 4 kW MM Fiber Laser M2 = 4.5 Optical Setup 1:1.25 1:2 1:1,25 Focal Diameter 25 m 38 m 64 m Rayleigh Length 435 m 970 m 660 m The cutting trials were carried out on a flatbed cutting machine with a maximum speed of 150 m/min with N2 (10 bars pressure) as cutting gas and 1.8 mm gas nozzle diameter. Andreas Wetzig et al. / Procedia Manufacturing 29 (2019) 369374 3712.2. Results and discussion Fig. 1 shows the cutting speed versus laser power for various optical configurations for cutting of electrical steel. Fig. 2 shows a similar graphics for the case of Aluminum. The minimal needed laser power was determined while the cutting speed was kept constant at predefined levels, i.e. at 30, 60, 90, 120, and 150 m/min. It is obvious that more laser power is needed to cut thicker material. It can be also seen that more laser power is needed with increasing focal diameter because more laser power is required to melt the material within an increasing kerf width. It is remarkable that this effect is more pronounced for cutting of Aluminum which is likely due to the higher heat conductivity. However, for both electrical steel and Aluminum and both fiber laser types in each optical configuration a laser power level of 2 kW is sufficient for a cutting speed of 150 m/min. In the case of cutting high strength steel only the 4 kW multi mode fiber laser was used for cutting. Due to lacking sheet flatness the cutting speed was restricted to 60 m/min while utilizing a laser power of 2.5 kW. The cutting quality is presented in Fig. 3 that shows the most critical applications: the thickest sheet of each material cut with the highest speed of 150 m/min with the smallest focal size. Although the appearance of the cutting edge looks quite different dross could be avoided even for the most critical cases as to be seen in Fig. 3. Therewith, laser fusion cutting with fiber lasers has been proven in general an alternative cutting technique which is able to replace mechanical shear cutting. 0120306090120150Laser Power kWCutting Speed m/minElectrical SteelSM 200m 1 : 1,25SM 200m 1 : 2SM 270m 1 : 1,25SM 270m 1 : 2SM 300m 1 : 1,25SM 300m 1 : 2MM 200m 1 : 1,25MM 270m 1 : 1,25Fig. 1. Cutting speed versus laser power for various thicknesses of electrical steel. 0120306090120150Laser Power kWCutting Speed m/minAluminiumSM 300m 1 : 1,25SM 300m 1 : 2SM 500m 1 : 1,25SM 500m 1 : 2MM 300m 1 : 1,25MM 500m 1 : 1,25Fig. 2. Cutting speed versus laser power for various thicknesses of aluminum. 372 Andreas Wetzig et al. / Procedia Manufacturing 29 (2019) 369374 3. 2D contour cutting 3.1. High Dynamic Form Cutter The concept of the high dynamic form cutter is to reduce the moving masses dramatically to less than 2 kg by an integration of fast linear axes into the cutting head (Fig. 4). The working envelope is 60 mm by 60 mm in the x and y direction with a maximum acceleration of 3g respectively and 20 mm stroke in z direction 6. Thus, the average cutting speed is up to three times higher compared to a conventional machine based on Cartesian axes. The increase depends on the so called agility (Fig. 5) which is a degree of fineness of a certain contour. The agility is defined as the sum of all angles of a contour divided by the sum of all lengths that equals the agility factor with the unit /mm 5. Agilities between 10 and 30 /mm can be assumed for typical metallic punching and bending parts. Subsequently, the usage of the HDFC enables average cutting speeds that are typically at least 5 m/min higher compared to the average speed that can be achieved by means of conventional axes (Fig. 5). The cutting quality is similar to cutting with lower speeds in terms of cutting edge appearance and dross formation. The only drawback is the limitation of the working envelope which is not critical for punching and bending parts. Fig. 3. left: electrical steel 300 m 1.2 kW SM, middle: high strength steel 800 m 2.5 kW MM, right: Al 500 m 1.0 kW SM Fig. 4: Schematic of HDFC. Fig. 5: Average processing speed depending on contour fineness. Andreas Wetzig et al. / Procedia Manufacturing 29 (2019) 369374 3733.2. Remote laser cutting Remote laser cutting is using a fiber laser with single mode beam quality that allows cutting or rather ablation without a cutting gas by providing the required power density at the focal point. The process is characterized by a cyclic ablation of the cut kerf material as shown in Fig. 6. The process uses a mix of molten and vaporized material in the process area. The single ablation depth depends on material, laser power, laser intensity, feed rate, and existing groove 7. A conventional laser cutting head as well as Cartesian axes which is used for the relative motion between laser and work piece is not needed any more. In fact, fast galvanometer axes are taking over the movement of the laser beam resulting into path speeds on the work piece of up to 1000 m/min (Fig. 7). Depending on the material thickness several laser passages are necessary. As a result, material thicknesses from 0.05 up to 0.5 mm for many metal materials used in industry can be remote cut by means of single mode fiber laser with final velocities between 50 and 1000 m/min. Fig. 8 shows the resulting cutting speed for different laser power and identical focus size for a single path speed of 1000 m/min as a function of the material thickness for cutting of stainless steel (1.4301) 8. On the other hand, there are several drawbacks compared to conventional fusion cutting. Burr may occur on the top side of the sheet instead of the bottom side. Secondly, the extremely high velocity of a single laser path causes contour deviations that can be reduced both by smart cutting strategies and by anticipating path planning. Also, the working field is limited to 100 mm by 100 mm which is still sufficient for the majority of typical metallic punching and bending parts 9. Fig. 9: Laminate for winding former, laser cut. Fig. 8: Effective cutting speed depending on laser power and thickness for steel (1.4301). Fig. 7: Schematic of beam manipulation by galvanometer-driven mirrors. Fig. 6: Cyclic ablation of remote laser cutting. 374 Andreas Wetzig et al. / Procedia Manufacturing 29 (2019) 3693744. Summary and outlook State of the art high power fiber lasers are allowing cutting speeds of 150 m/min and beyond. The most interesting application in the case of linear cutting is slitting and trimming of band material. Next steps will be to reach feed rates of up to 500 m/min by means of more powerful lasers and to work at the same time on the implantation into an industrial environment. To maintain stable cutting quality for several hundreds of kilometers cutting length seems to be the most challenging factor. Both concepts of the High Dynamic Form Cutter and remote laser cutting have been for the first time realized within an inline reel to reel laser cutting machine for metal strips 4. However, the full potential of fast 2D laser cutting is by far not tapped. There are several reasons why laser cutting can be the method of choice even for high volume parts: On one hand, the general trend to apply steel grades with higher material strength precludes punching as manufacturing method. On the other hand, punching technology is associated with certain design limits which means that intricate contours are difficult to achieve. Even alternative manufacturing technologies like etching are out of question due to environmental concerns and technological limitations. The laminate for winding formers which is shown in Fig. 9 represents such a typical contour that can only be achieved by a laser cutting process. Many more similar contours made of thin sheet metal are supposed to be cut by means of fiber lasers in the future. 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