Surface accuracy achieved by upsetting of preforms generated by laser rod end melting

Brüning, Heiko; Vollertsen, Frank

doi:10.1051/matecconf/20152109006

Cited by 2 publications

(3 citation statements)

References 6 publications

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“…Finally, it is possible to mold fine surface structures after the forming stage, such as the surface roughness of the die, see [Brü14a], down to feature sizes of 500 nm which is investigated in [Brü15c]. In Fig.…”

Section: Formabilitymentioning

confidence: 99%

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Micro Forming Processes

Kuhfuß¹,

Schattmann

Jahn

et al. 2019

Lecture Notes in Production Engineering

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The projects of this chapter describe micro forming processes that are studied as single processes but can also be combined as process chains. Proven examples are material accumulation and succeeding rotary swaging, or rotary swaging and extrusion.Micro forming differs from macro forming due to scaling effects, which can mean both challenges and benefits. Problems may arise from the handling of fragile parts or adhesive forces between the micro parts or friction effects.Benefits from scaling effects are made use of in the project "Generation of functional parts of a component by laser-based free-form heading". The aim is a material accumulation that is generated from short duration laser melting. This material accumulation gives the basis for succeeding cold forming operations. The first powerful application for the new technology was upsetting. In the macro range, upset ratios of about 2.3 are achievable, but this is reduced in the micro scale due to earlier buckling of the components. In the micro scale, where cohesive forces can exceed the gravitational force, the molten material forms a droplet that remains adhered to the rod. Thus, upset ratios of up to 500 were reached. The process development was accompanied by a mathematical model and allows for a deep insight into the thermodynamics of laser-induced material accumulation in the micro range.The laser molten material accumulation could, for example, be further processed by micro rotary swaging. Though rotary swaging has been known in the macro range for a long time and is nowadays an intensively used process in the automotive industry to produce lightweight components from tubular blanks, there are only a few scientific works that have addressed material characteristics like the work hardening or residual stress that are linked to the process and machine parameters and the resulting material flow. Due to micro scale specifics that follow from the kinematics, i.e. relatively smaller stiffness against part buckling and wider tool gaps in the opened state, the feed rates achievable cannot compete with high throughput technologies that produce 500 parts per minute and more. One major aim of the project "Rotary swaging of micro parts" was to increase the productivity for the main process variants, namely infeed and plunge rotary swaging. This demanded also process modeling to understand how parameter variations like friction between tools and the work in the different zones of the swaging tools affect the process.From the modeling and simulation, separate process variations were deduced and investigated. For infeed swaging, a special workpiece clamping allows for compensation of the pushback force, which results in a 10-fold increase of the maximum feed rate. For plunge rotary swaging, an approach was tested to close the tools gaps during opening using elastic intermediate elements that encapsule the workpiece against the forming dies and enable a 4-fold increase of the radial feed rate. 28 B. Kuhfuss et al.Micro rotary swaging could become a base technology ...

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Section: Formabilitymentioning

confidence: 99%

“…For a process chain, the outcome can be calculated by a series of tolerance functions. An example of data useful for tolerance engineering is given in Brüning [Brü15c] and is described by using upsetting of preforms with cone shaped cavities. In this example, four different dies are compared regarding their forming results.…”

Section: Change Of Scattermentioning

confidence: 99%

Micro Forming Processes

Kuhfuß¹,

Schattmann

Jahn

et al. 2019

Lecture Notes in Production Engineering

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“…Laser rod end melting results in a rounding of the end of cylindrical rods for rods with a maximum diameter of 1 mm [4]. After the generation of the spherical geometry at the rod end in the master forming stage, this part can be used as a preform for a micro cold forming operation in a subsequent process stage for the production of metallic micro parts such as screws or springs [5].…”

Section: Introductionmentioning

confidence: 99%

Deburring and rounding of sheet metals and functionally relevant edges of parts using laser radiation

Kumstel

Lüken

2018

MATEC Web Conf.

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The manufacturing of sheet metal parts or component edges often leads to burrs. Due to different requirements regarding the appearance, haptics, tribology et cetera the edges have to be deburred or rounded in a subsequent process. Especially for complex geometries, automated post-processing has been difficult up to now. Laser remelting is one possible solution. It is fully automated and suitable for most 3D geometries. During laser remelting the laser beam is focused on the surface, thus a thin surface layer up to 100 μm is melted. The surface tension in the liquid state is smoothing out the surface and the edge resolidifies rounded. The radius of the rounding is adjustable by the chosen process parameters, especially laser power PL and feed speed vfeed. Furthermore the resulting roughness and the gloss level are controllable via the process parameters. Typical processing speeds are 100 mm edge length per second. First studies with industry partners showed promising results. Laser remelting of push belts for the torque transmission in CVTs lead to an increase of fatigue strength by up to 200% which enables a higher torque.

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Surface accuracy achieved by upsetting of preforms generated by laser rod end melting

Cited by 2 publications

References 6 publications

Micro Forming Processes

Micro Forming Processes

Deburring and rounding of sheet metals and functionally relevant edges of parts using laser radiation

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