A novel surface roughness model for potassium dihydrogen phosphate (KDP) crystal in oblique diamond turning

Zhang, Shuo; Zong, Wenjun

doi:10.1016/j.ijmecsci.2020.105462

Cited by 26 publications

(6 citation statements)

References 29 publications

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“…In addition, considering that the large cutting edge radius promotes the plastic side flow and increases the height of tool marks [ 52 , 53 ], the goal of the tool-edge passivation process should be keeping the cutting edge as sharp as possible while removing the tool-edge micro defects completely. Figure 11 a shows the measured result of the sharp edge before passivation; obviously, there is a micro defect, as marked by the red box on the cutting edge.…”

Section: Resultsmentioning

confidence: 99%

Micro Defects on Diamond Tool Cutting Edge Affecting the Ductile-Mode Machining of KDP Crystal

Zhang

Zong

2020

Micromachines

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As a soft-brittle material, the machined surface quality of potassium dihydrogen phosphate (KDP) crystal is heavily affected by the edge quality of the diamond cutting tool. However, nanoscale micro defects inevitably occur on the freshly sharpened tool edge, and the machining mechanism for KDP crystal remains unclear. Therefore, in this work, three types of tool-edge micro defects are classified according to their cross-sections, including the blunt-edge, crescent-edge, and flat-edge micro defects. Moreover, the smoothed particle hydrodynamics (SPH) method is employed to reveal the material removal mechanism of KDP crystal with consideration of different tool-edge micro defects, and the flat-edge micro defects are subdivided into flat edge A (similar to flank wear) and flat edge B (similar to chamfered edge) on the basis of their effects in machining. The simulation results indicate that the surfaces machined by crescent edge and flat edge A are unsmooth with large-size defects due to the disappearance of hydrostatic pressure beneath the cutting edge. As for the blunt edge and flat edge B, the machined surfaces are smooth with a favorable increment of hydrostatic pressure for processing brittle materials, which indicates that a solution to eliminate the tool-edge micro defects is necessary, e.g., the passivation method. For keeping the cutting edge as sharp as possible in removing the tool-edge micro defects completely by passivation, the effect of tool shank depression angles on the geometries of the passivated cutting edge is investigated, and a high-quality cutting edge with a micro chamfered edge is obtained after passivation at a depression angle of 60° and re-sharpening of the rake face. Finally, the tool cutting performance after passivation is validated through fly-cutting experiments of KDP crystal. The chamfered edge can produce the best defect-free surface with the minimum surface roughness.

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Section: Resultsmentioning

confidence: 99%

Micro Defects on Diamond Tool Cutting Edge Affecting the Ductile-Mode Machining of KDP Crystal

Zhang

Zong

2020

Micromachines

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“…where the surface surrounding the contact point of the tool and machining surface is convex, as depicted in Figure 7c. The mathematical model linking the tool radius R, the residual height h, and the machining row distance L is shown in Equation (18).…”

Section: Calculation Of Toolpath Parametersmentioning

confidence: 99%

“…However, for optical freeform surfaces with complex surface shapes, the traditional toolpath planning method has problems, such as large machining errors and difficult control of machining quality when applied to ultra-precision turning [18,19]. Therefore, there is an urgent need to develop a toolpath planning method for freeform ultra-precision diamond turning to improve the high-precision manufacturing of complex optical freeform parts.…”

Section: Introductionmentioning

confidence: 99%

A Toolpath Planning Method for Optical Freeform Surface Ultra-Precision Turning Based on NURBS Surface Curvature

Wang,

Bai,

Gao

et al. 2023

Machines

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As the applications for freeform optical surfaces continue to grow, the need for high-precision machining methods is becoming more and more of a necessity. Different toolpath strategies for the ultra-high precision turning of freeform surfaces can have a significant impact on the quality of the machined surfaces. This paper presents a novel toolpath planning method for ultra-precision slow tool servo diamond turning based on the curvature of freeform surfaces. The method analyzes the differential geometric properties of freeform surfaces by reconstructing NURBS freeform surfaces. A mathematical model is constructed based on the parameters of different positions of the freeform surface, toolpath parameters, and tool residual height. Appropriate toolpath parameters can be calculated to generate the optical freeform ultra-precision slow tool servo diamond turning toolpath. Compared with the toolpaths generated by the traditional Archimedes spiral method, the ultra-precision slow tool servo diamond turning toolpath planning method proposed in this paper can generate more uniform toolpaths on the freeform surfaces and keep the residual tool height within a small range.

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“…In order to reveal its ductile material removal mechanism, theoretical models have been established to predict the critical cutting depth and load at the BDT cutting states [23,24]. A kinematic model and wavelet analysis method have been constructed to predict the surface roughness under various combinations of cutting process parameters by incorporating the ductile plasticity and brittle crack characteristics [25,26]. Building on the insights gained from the fundamental nano-indentation, the optimal ductile material removal with shallow subsurface damage was identified on the (001) plane [27].…”

Section: Introductionmentioning

confidence: 99%

On a Novel Modulation Cutting Process for Potassium Dihydrogen Phosphate with an Increased Brittle–Ductile Transition Cutting Depth

Yang,

Chen,

Zhao

2023

Machines

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Potassium dihydrogen phosphate (KDP) has garnered considerable attention due to its diverse applications across various scientific and engineering domains. Although promising machining performance enhancements have been achieved in ultra-precision diamond cutting, the brittle–ductile transition (BDT) depth for KDP crystals is essentially at the nanometer range and limits the further improvement of machining efficiency. In this paper, a novel ultra-precision diamond cutting process based on tool trapezoidal modulation is proposed for the first time to investigate the BDT characteristics of KDP crystals. By intentionally designing the tool modulation locus, the uncut chip thickness and cutting direction in the cutting duty cycle are kept constant, which provides a new strategy for probing the BDT mechanism and enhancing the machining performance. The BDT depth is significantly increased compared to the conventional ultra-precision diamond cutting owing to its unique modulation machining advantages. The significance of this paper lies not only in the improvement of the machining efficiency of KDP crystals through the proposed modulation cutting process, but also in the possibility of extending the relevant research methods and conclusions to the machining performance enhancement of other brittle optical crystals.

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A novel surface roughness model for potassium dihydrogen phosphate (KDP) crystal in oblique diamond turning

Cited by 26 publications

References 29 publications

Micro Defects on Diamond Tool Cutting Edge Affecting the Ductile-Mode Machining of KDP Crystal

Micro Defects on Diamond Tool Cutting Edge Affecting the Ductile-Mode Machining of KDP Crystal

A Toolpath Planning Method for Optical Freeform Surface Ultra-Precision Turning Based on NURBS Surface Curvature

On a Novel Modulation Cutting Process for Potassium Dihydrogen Phosphate with an Increased Brittle–Ductile Transition Cutting Depth

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