Experimental Study of Distortion Phenomena in Manufacturing Chains

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Causes for distortion phenomena during heat treatment are inhomogeneous or asymmetric distributions of mass, alloying elements, microstructure, and residual stresses. These causes generate a distortion potential of the work piece which could be set free during the final heat treatment. But for a concrete calculation of the distortion potential it is necessary to know the interrelationships between the changes in dimensions and shape and the strains within the work piece. If these functional interrelationships are known it is possible to estimate the strains which are necessary for observed distortion effects. For elementary geometries like shafts, plates, and rings the distortion potential generates characteristic distortions. For simple shafts e. g. mostly "banana forms" can be observed, whereas for cylindrical rings often an oval shape governs the out of roundness. This practical experience for cylindrical rings will be analyzed in a more detailed way. The knowledge of the interrelation of geometry and strains in combination with energy considerations enables a quantitative expression of the distortion potential of cylindrical rings.

Section: Discussionsupporting

confidence: 79%

Section: Bending Casementioning

confidence: 99%

Section: Deformation Of a Circular Segment Due To Expansionmentioning

confidence: 99%

Section: ð4-2þmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Ring geometry as an important part of distortion potential

Frerichs¹,

Lübben²,

Hoffmann³

et al. 2012

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Identification of process parameters affecting distortion of disks for gear manufacture Part I: casting, forming and machining

Clausen¹,

Frerichs

Kohlhoff

et al. 2009

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Towards determining the influence parameters on the distortion of gear wheels made from the steel grade 20MnCr5 (SAE 5120), in this work the analysis of the distortion of disks is presented. The parameter identification was performed by means of the design of experiments (DoE). According to a comprehensive approach to distortion engineering, the entire manufacturing chain was considered from casting to the final heat treatment. Due to the complexity of this manufacturing chain the investigation was divided into two parts, the processes before the final heat treatment and the final heat treatment process itself. Here, in part I, the results of the investigation of the processes before the final heat treatment are discussed while in part II the results of the final heat treatment are presented. Releasing the accumulated distortion potential of the influence parameters of the processes from casting to cutting by a standard case hardening led to characteristic size changes of the disks. For the shape changes the cutting strategy showed a high influence on the change of dishing. Assuming that the cutting strategy can continuously be varied there should be a strategy for which no change of the dishing occurs, which would provide the means for compensation of distortion.

Identification of process parameters affecting distortion of disks for gear manufacture ‐ Part II: heating, carburizing, quenching

Clausen

Frerichs

Kohlhoff

et al. 2009

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In this work the applied approach to ‘Distortion Engineering’ is based on the consideration of the entire manufacturing chain of disks, from casting to the final heat treatment, made from the steel grade 20MnCr5 (SAE 5120). Part II presents the results of the investigations concerning the final heat treatment parameters on the distortion of the disks, whereas part I describes the effect of the influence parameters from casting to cutting. The disk geometry was selected, in order to reduce the expected complexity of influence parameters in gear wheel distortion. The parameter identification took place by means of the design of experiments (DoE). Volume flow rate of quenching gas, hardening temperature and carburizing depth have the expected effect on the volume change of the disks. In addition, occurring differences in the size changes of the inner and the outer surfaces were detected. For the shape changes it was found, that the choice of the loading tool shows the main influence. Furthermore a change in the loading tool does clearly affect the dishing behavior of the disks. Whereas, a relevant influence of the carburizing depth on the shape changes of disks could not be identified in this investigation. As a conclusion from the results presented in part I and II it is assumed that the identified parameters of disk distortion also effect the distortion of gear wheels.