An Investigation of the Grinding-Hardening Induced by Traverse Cylindrical Grinding

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Thai Nguyen ◽  
Mei Liu ◽  
Liangchi Zhang ◽  
Qiong Wu ◽  
Dale Sun
Keyword(s):  
Heat Transfer ◽  
Base Material ◽  
Hardened Layer ◽  
Transfer Model ◽  
Molten Material ◽  
Grinding Method ◽  
Small Pitch ◽  
Cylindrical Workpiece ◽  
Grinding Hardening ◽  
Traverse Grinding

This study investigates the formation of the layer hardened on a cylindrical workpiece by grinding-hardening using the traverse grinding method. A finite element heat transfer model, that took into account the helical trajectory of the of the grinding heat source movement, was developed. The hardened layer was found featuring a wavy profile as a result of the heat conduction from an adiabatic plane crossing the middle of the trajectory pitch. The accumulation of the grinding heat within a small pitch can lead to the welding of the molten material with the base material. Enlarging the pitch by reducing the workpiece speed will increase the time of heating, allowing the heat to penetrate deeper and to expand wider in the workpiece, thus thickening the hardened layer.

Heat Transfer in Grinding-Hardening of a Cylindrical Component

2011 ◽  
Vol 325 ◽  
pp. 35-41 ◽  
Author(s):  
Thai Nguyen ◽  
Liang Chi Zhang ◽  
Da Le Sun
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Hardened Layer ◽  
Transfer Model ◽  
Plunge Grinding ◽  
Cylindrical Component ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Grinding Hardening ◽  
Good Agreement

A three-dimensional finite element heat transfer model incorporating a moving heat source was developed to investigate the heat transfer mechanism in grinding-hardening of a cylindrical component. The model was applied to analyze the grinding-hardening of quenchable steel 1045 by two grinding methods, traverse and plunge grinding. It was found that the heat generated can promote the martensitic phase transformation in the ground workpiece. As a result, a hardened layer with a uniform thickness can be produced by traverse grinding. However, the layer thickness generated by plunge grinding varies circumferentially. The results are in good agreement with the experimental observations.

Prediction of the Hardened Layer in Traverse Cylindrical Grinding-Hardening

2011 ◽  
Vol 697-698 ◽  
pp. 13-18 ◽  
Author(s):  
Thai Nguyen ◽  
Liang Chi Zhang
Keyword(s):  
Heat Transfer ◽  
Hardened Layer ◽  
Annealing Process ◽  
Grinding Wheel ◽  
Transfer Model ◽  
Moving Heat Source ◽  
Workpiece Material ◽  
Cylindrical Grinding ◽  
Grinding Hardening ◽  
Good Agreement

A finite element heat transfer model incorporating a moving heat source has been developed to predict the temperature field in traverse cylindrical grinding. The model was then applied to analyse the grinding-hardening of quenchable steel 1045. It was found that in the region where the grinding wheel had an entire contact with the workpiece, material would experience a heating-cooling cycle, enabling the generation of a uniform hardened layer. In the transient regions at the two ends of the workpiece where the wheel-workpiece contacts were partial, the material was not hardened but experienced an annealing process. The results were in good agreement with the experimental observations.

Quality and Control of Grinding-Hardening in Workpieces

2012 ◽  
Vol 522 ◽  
pp. 87-91 ◽  
Author(s):  
Ju Dong Liu ◽  
Wei Yuan ◽  
Jin Kui Xiong ◽  
Song Wei Huang
Keyword(s):  
High Hardness ◽  
Hardened Layer ◽  
Surface Grinding ◽  
Depth Of Cut ◽  
Insignificant Effect ◽  
Grinding Method ◽  
And Control ◽  
Grinding Hardening ◽  
Table Speed

On the basis of the surface grinding-hardening test, studied on the quality of grinding-hardening in 65Mn steel. The results show that grinding method has insignificant effect on the microstructure and the high hardness value of the completely hardened region at different locations alone the direction of length. The completely hardened region is composed of fine acicular martensites, residual austenites and a little carbides, and the high hardness value is between 760-820HV. As the changing of grinding method, the uniformity and depth of the hardened layer changed accordingly. The quality of grinding-hardening could be improved with big depth of cut, small table speed and combined with the grinding method of up-down grinding or down-up-down grinding which could effectively control the depth and uniformity of the hardened workpieces.

Orthogonal Experimental Study on the Grinding-Hardened Layer’s Depth and its Uniformity of 45 Steel

2013 ◽  
Vol 668 ◽  
pp. 898-901 ◽  
Author(s):  
Wei Yuan ◽  
Ju Dong Liu ◽  
Zhi Long Xu
Keyword(s):  
Orthogonal Experiment ◽  
Hardened Layer ◽  
Depth Of Cut ◽  
Average Value ◽  
Actual Application ◽  
Grinding Method ◽  
Grinding Conditions ◽  
Grinding Hardening ◽  
Table Speed

Based on the orthogonal experiment of grinding-hardening machine, this paper studied the influence of depth of cut ap, table speed vw and grinding method gm on the grinding-hardened layer’s depth and its uniformity of 45 steel. The results show that, depth of cut ap is the significant factor affected the average value of grinding-hardened layer’s depth, but the influence of grinding conditions on the uniformity are very limited. In actual application, it should adopt ap=0.6mm, vw=0.4m/min and up-down grinding method to enhance the quality of grinding-hardened layer.

On the Profile and Microstructure Variations of Grinding-Induced Hardening Layer in A Cylindrical Workpiece

2014 ◽  
Vol 1017 ◽  
pp. 3-8 ◽  
Author(s):  
Mei Liu ◽  
Thai Nguyen ◽  
Liang Chi Zhang ◽  
Qiong Wu ◽  
Da Le Sun
Keyword(s):  
Finite Element Method ◽  
Material Removal ◽  
Hardened Layer ◽  
Carbide Precipitation ◽  
The Finite Element Method ◽  
Tempering Temperature ◽  
Mechanical Process ◽  
Cylindrical Workpiece ◽  
Grinding Hardening ◽  
Microstructural Examination

Grinding-hardening is a thermo-mechanical process capable of simultaneous material removal and surface enhancement. However, there are difficulties in dealing with cylindrical workpieces, because of the complex 3D-helical movement of the grinding-induced heat source. This paper investigates the effects of some key grinding parameters on the profile and microstructure variations of the hardened layer generated by a traverse cylindrical grinding, both experimentally and numerically. It was found that the ratio of the longitudinal wheel feed to the rotational speed of the workpiece R is most influential on the hardened layer profile. A larger R results in a thicker hardened layer but a more pronounced discontinuity of two adjacent hardening zones. Although a smaller R yields a relatively thinner hardened layer, the non-uniformity could be minimised by the overlapping of the grinding heating. The microstructure of the hardened layer can be altered by the tempering in subsequent grinding heating. A thermal analysis with the aid of the finite element method in conjunction with an experimental microstructural examination showed that the temperature distribution in the tempered region would lead to a variation of the precipitated carbide, and that a higher tempering temperature could result in a higher degree of the carbide precipitation and a more significant reduction of hardness.

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

An Engine Heat Transfer Model for Comprehensive Thermal Simulations

2006 ◽  
Author(s):  
Filip Kitanoski ◽  
Wolfgang Puntigam ◽  
Martin Kozek ◽  
Josef Hager
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Thermal Simulations
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