Eccentric rotary swaging

Ishkina, Svetlana; Schenck, Christian; Kuhfuß, Bernd; Moumi, Eric; Tobeck, Kiron

doi:10.1007/s12541-017-0122-4

Cited by 11 publications

(11 citation statements)

References 11 publications

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“…These results correspond to the martensite content, which was more influenced by the feed velocity if flat-shaped dies were applied [Ish17b]. Additionally, the number of strokes was higher with lower feed velocity.…”

Section: Resultssupporting

confidence: 68%

“…As a result, the transformed martensite showed a strong reduction compared to the amount of martensite after conventional rotary swaging. Thus, pre-forming of the workpieces in this special way affected work softening, reduction of yield stress, and increase of the plastic strain [Ish17b]. The grain boundaries were detectable in the core area of the processed workpieces while they were not visible any more in the outer regions (Fig.…”

Section: Resultsmentioning

confidence: 90%

“…In contrast, using flat-shaped and double-flat-shaped dies decreased the required forces significantly (curves II and III press force, F extruded part are below curve NS). This difference can be explained by various aspects, for example a change of the microstructure, a reduction of the grain size or martensite and carbide formation [Ish17b]. The microstructures are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The use of the eccentric flat-shaped dies changed the process kinematics by means of radial displacement of the center-line during the process and thus resulted in a higher shear strain. Due to a significant reduction of the grain size and the martensite content compared to the rotary swaging using double-flat-shaped dies [Ish17b], a reduction of the required press force during extrusion could be observed (Fig. 2.41, curve IV below curve III).…”

Section: Resultsmentioning

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: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Micro Forming Processes

Kuhfuß¹,

Schattmann

Jahn

et al. 2019

Lecture Notes in Production Engineering

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“…It can be used at preparation of semi-finished products with both a calibrated diameter as well as predefines material properties of the parts. To modify the microstructure of swaged rods with small diameter about 1 mm an approach of eccentric rotary swaging was applied [5]. The eccentric machined parts featured very fine grains.…”

Section: Introductionmentioning

confidence: 99%

Eccentric rotary swaging variants

Toenjes

Ishkina²,

Schenck

et al. 2018

MATEC Web Conf.

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Rotary swaging is an incremental cold forming process that changes beneath the geometry also the microstructure and mechanical properties of workpiece. Especially a new process design with Eccentric Flat Shaped Dies (EFSD) influences both the kind and amount of stress and plastic strain and consequently the material structure and hence the material and workpiece properties. Eccentric rotary swaging typically provides a helical material flow. According to the process parameters the microstructure features a typical eddy pattern with a spiral shaped grain orientation. The forming process can be carried out in one or more process steps. In a multi-stage process, it is possible to change the feed direction and, hence, the material flow helix direction. This approach can be used as a possibility to improve the homogeneity of the workpiece and material properties. In addition, for this aims an intermediate heat treatment in multi-stage forming operations could be realised. Following the goal of optimising the final properties, the question arises how these mechanical and thermal treatments affect the material microstructure and the forming properties of the workpiece and how they interact. Experiments were conducted with austenitic stainless steel rods of grade AISI304. The effects of the varied feed direction, feed velocity and heat treatment between the forming operations are discussed.

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Development of residual stresses by infeed rotary swaging of steel tubes

et al. 2021

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Additionally to the achievable tight geometrical tolerances, rotary swaging can influence intrinsic material properties by work hardening and residual stresses generation. Although residual stresses should be usually avoided, they can be used on purpose to improve the performance properties of a produced part. To find prospective process settings, 2D FEM simulation of the rotary swaging process was developed and revealed the development of residual stresses distributions in E355 steel tubes in the whole longitudinal section. Besides the closing time, also geometric features of the dies were varied. It was found that the closing time affects the residual stresses significantly at the surface, but not in the depth of the part. By shortening the calibration zone, the axial tensile residual stresses near the outer surface could be lowered, while compressive residual stresses near the inner surface remained almost unaffected. By applying a higher die angle, the tensile axial residual stresses were increased while reducing the compressive axial residual stresses. Experimental investigations of residual stresses were performed by X-ray diffraction which revealed a good agreement between simulation results and physical measurements. With these findings, the rotary swaging process can be optimized for shaping residual stresses profiles to improve the performance properties of the produced parts.

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Eccentric rotary swaging

Cited by 11 publications

References 11 publications

Micro Forming Processes

Micro Forming Processes

Eccentric rotary swaging variants

Development of residual stresses by infeed rotary swaging of steel tubes

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