Influence of tribological conditions on cold forging of gears

Kiener, Christoph; Neher, R.; Merklein, Marion

doi:10.1007/s11740-017-0785-9

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…Both of these areas necessitate material removal by machining, which reduces material utilisation of the process and also calls for additional production steps [7]. [8,9]).…”

Section: Cold Extrusion Of Gearsmentioning

confidence: 99%

Numerical study on cold extrusion of gears varying the extrusion shoulder geometry

Deliktas

2023

Materials Research Proceedings

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Abstract. Cold forging processes, such as cold extrusion and in particular the Samanta process, provide a considerable potential for improvement in gears production. The method behind the Samanta process is based on the principle of cold extrusion in stacks. After partial forming of a workpiece, another workpiece is inserted into the die in order to eject a completely formed gear in the direction of the punch movement. Although this operating principle offers great potential for high-volume production, the industrial relevance of this process is limited by disadvantages such as high tool loads, limited gear accuracy and deformations on both face ends of the gear wheel. In order to overcome the technological challenges associated with the Samanta process, the die geometry was adapted. In this case the die operating surface was modified in terms of an extended forming zone length combined with an undercut in the tooth cavities of the die. In this paper the numerical results for this novel process regarding the correlations between geometric die parameters and resulting process data, such as punch force, contact pressure and die filling, are presented. The spline-based tool was methodically varied between one linear and two square (concave, convex) designs and was numerically evaluated using Deform 3D™ software.

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“…Both of these areas necessitate material removal by machining, which reduces material utilisation of the process and also calls for additional production steps [7]. [8,9]).…”

Section: Cold Extrusion Of Gearsmentioning

confidence: 99%

Numerical study on cold extrusion of gears varying the extrusion shoulder geometry

Deliktas

2023

Materials Research Proceedings

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“…The aim is the identification between the friction factor m as input and the resulting cup height ratios r as output, which are corresponding to the ratio of upper cup to lower cup. For the simulation, the model validated in [19] is used in the software simufact.forming. The cup extrusion is simulated with different values of m in the relevant range from 0 to 0.2, where the friction factors are expected.…”

Section: Identification Of Tribological Propertiesmentioning

confidence: 99%

Component residual stress control in forward rod extrusion by material flow and tribology—experiments and modeling

Jobst¹,

Floros

Steinmann

et al. 2021

Forsch Ingenieurwes

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The forward rod extrusion of ferritic stainless steel X6Cr17 (DIN 1.4016) is here investigated with the objectives to experimentally identify and numerically verify the effect of the lubrication system and die opening angle on residual stresses. Three lubricants – MoS2, soap and polymer – are considered whose tribological properties are characterized via double cup extrusion tests. The effect of material flow is also studied by forming in conical dies featuring three different opening angles. The extrusion experiments revealed a decrease in the near-surface tensile stresses with decreasing friction for all the considered opening angles. An opening angle of 2α = 90° led to the highest tensile residual stresses. Both an increase to 2α = 120° and a decrease to 60° resulted in reduced tensile stresses and even a shift to compressive stresses.Furthermore, a previously developed numerical model of forward rod extrusion is optimized and validated against the experimentally measured residual stresses. The effect of the spatial and temporal discretizations of the model on the predicted residual stresses is investigated. Based on the experimental and numerically verified results, the recommendation to reduce friction in forward rod extrusion is derived as a means to obtain a less detrimental to the lifecycle of extruded parts residual stress state.

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“…Therefore, the tools are exposed to the operation of many destructive factors, which cause their wear, both premature and after a longer operation time. The areas especially subjected to wear are the working surface and the surface area of the tool, and so, most of the mentioned destructive mechanisms refer to those areas of the tool [ 11 , 12 ]. Exploitation is an indispensable phenomenon accompanying the production of products and is most often associated with the maximum use of a machine/system/tool in a specific time, after which it ends with their partial or complete wear.…”

Section: Introductionmentioning

confidence: 99%

“…Exploitation is an indispensable phenomenon accompanying the production of products and is most often associated with the maximum use of a machine/system/tool in a specific time, after which it ends with their partial or complete wear. Therefore, in the technical literature, a lot of space is devoted to the issue of exploitation and a number of studies have been carried out on the determination of significant parameters affecting this phenomenon, as well as industrial research and development works that allow researchers to increase the exploitation time [ 11 , 12 , 13 ]. The most commonly occurring and main destructive mechanisms include abrasive wear [ 14 ] and plastic deformation, during warm forging [ 15 , 16 , 17 ], as well as plastic deformations in the case of hot forging [ 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Structural Features of Fatigue Crack Propagation of a Forging Die Made of Chromium–Molybdenum–Vanadium Tool Steel on Its Durability

Hawryluk,

Lachowicz,

Łukaszek-Sołek

et al. 2023

Materials

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The paper presents the results of tests on a die insert made of non-standardised chrome-molybdenum–vanadium tool steel used during pre-forging, the life of which was 6000 forgings, while the average life for such tools is 8000 forgings. It was withdrawn from production due to intensive wear and premature breakage. In order to determine the causes of increased tool wear, a comprehensive analysis was carried out, including 3D scanning of the working surface; numerical simulations, with particular emphasis on cracking (according to the C-L criterion); and fractographic and microstructural tests. The results of numerical modelling in conjunction with the obtained results of structural tests allowed us to determine the causes of cracks in the working area of the die, which were caused by high cyclical thermal and mechanical loads and abrasive wear due to intensive flow of the forging material. It was found that the resulting fracture initiated as a multi-centric fatigue fracture continued to develop as a multifaceted brittle fracture with numerous secondary faults. Microscopic examinations allowed us to evaluate the wear mechanisms of the insert, which included plastic deformation and abrasive wear, as well as thermo-mechanical fatigue. As part of the work carried out, directions for further research were also proposed to improve the durability of the tested tool. In addition, the observed high tendency to cracking of the tool material used, based on impact tests and determination of the K1C fracture toughness factor, led to the proposal of an alternative material characterised by higher impact strength.

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Influence of tribological conditions on cold forging of gears

Cited by 6 publications

References 9 publications

Numerical study on cold extrusion of gears varying the extrusion shoulder geometry

Numerical study on cold extrusion of gears varying the extrusion shoulder geometry

Component residual stress control in forward rod extrusion by material flow and tribology—experiments and modeling

Structural Features of Fatigue Crack Propagation of a Forging Die Made of Chromium–Molybdenum–Vanadium Tool Steel on Its Durability

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