Influence of main cutting edge structure on hole defects in CFRP/titanium alloy stacks drilling

2021 ◽  
Vol 69 ◽  
pp. 503-513
Author(s):  
Xin-Yi Qiu ◽  
Zhen Yu ◽  
Chang-ping Li ◽  
Qiu-Lin Niu ◽  
Shu-Jian Li ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Cutting Edge ◽  
Edge Structure ◽  
Hole Defects

scholarly journals Study on Design, Manufacture and Cutting Performance of Circular-arc Milling Cutters for Machining Titanium Alloy

2021 ◽  
Author(s):  
Tao Chen ◽  
Liu Gang ◽  
Li Rui ◽  
Lu Yujiang ◽  
Wang Guangyue
Keyword(s):  
Titanium Alloy ◽  
Surface Quality ◽  
End Milling ◽  
Geometric Model ◽  
Cutting Edge ◽  
Grinding Wheel ◽  
Side Milling ◽  
Edge Structure ◽  
Circular Arc ◽  
Milling Forces

Abstract Titanium alloy is widely used for manufacturing structural parts of high-end equipment due to its excellent mechanical properties, despite difficulty in being machined. Nowadays, titanium alloy parts are mostly machined by ball-end milling cutters (BEMC), but the cutting edge structure of the BEMC limits the improvement in machining efficiency and surface quality of the parts. In this paper, a circular-arc milling cutter (CAMC) with large-curvature cutting edge was proposed; the differential geometry method was used for establishing the geometric model for the contour surface of the CAMC and the mathematical model for the spiral cutting edge line; the conversion matrix between grinding wheel and workpiece coordinates was introduced to derive the equation of grinding wheel trajectory when the rake face of the CAMC was ground; the self-designed CAMC was ground and tested in accuracy. The comparative research was conducted experimentally on the side milling of titanium alloy TC4 with the CAMC and BEMC, and consequently the variation laws of milling forces, wear morphology and machined surface quality were obtained about the two types of milling cutters. The results indicated that the CAMC can effectively reduce the main milling force and keep the milling process stable. Moreover, the CAMC was worn slower and produced better surface quality than the BEMC.

scholarly journals Experimental Study of tool Wear Mechanisms in Conventional and High Pressure Coolant Assisted Machining of Titanium Alloy Ti17

2013 ◽  
Vol 554-557 ◽  
pp. 1961-1966 ◽  
Author(s):  
Yessine Ayed ◽  
Guenael Germain ◽  
Amine Ammar ◽  
Benoit Furet
Keyword(s):  
High Pressure ◽  
Titanium Alloy ◽  
Tool Wear ◽  
Titanium Alloys ◽  
Tool Life ◽  
Wear Mechanisms ◽  
Cutting Forces ◽  
Cutting Edge ◽  
Rake Face ◽  
High Pressure Coolant

Titanium alloys are known for their excellent mechanical properties, especially at high temperature. But this specificity of titanium alloys can cause high cutting forces as well as a significant release of heat that may entail a rapid wear of the cutting tool. To cope with these problems, research has been taken in several directions. One of these is the development of assistances for machining. In this study, we investigate the high pressure coolant assisted machining of titanium alloy Ti17. High pressure coolant consists of projecting a jet of water between the rake face of the tool and the chip. The efficiency of the process depends on the choice of the operating parameters of machining and the parameters of the water jet such as its pressure and its diameter. The use of this type of assistance improves chip breaking and increases tool life. Indeed, the machining of titanium alloys is generally accompanied by rapid wear of cutting tools, especially in rough machining. The work done focuses on the wear of uncoated tungsten carbide tools during machining of Ti17. Rough and finish machining in conventional and in high pressure coolant assistance conditions were tested. Different techniques were used in order to explain the mechanisms of wear. These tests are accompanied by measurement of cutting forces, surface roughness and tool wear. The Energy-dispersive X-ray spectroscopy (EDS) analysis technique made it possible to draw the distribution maps of alloying elements on the tool rake face. An area of material deposition on the rake face, characterized by a high concentration of titanium, was noticed. The width of this area and the concentration of titanium decreases in proportion with the increasing pressure of the coolant. The study showed that the wear mechanisms with and without high pressure coolant assistance are different. In fact, in the condition of conventional machining, temperature in the cutting zone becomes very high and, with lack of lubrication, the cutting edge deforms plastically and eventually collapses quickly. By contrast, in high pressure coolant assisted machining, this problem disappears and flank wear (VB) is stabilized at high pressure. The sudden rupture of the cutting edge observed under these conditions is due to the propagation of a notch and to the crater wear that appears at high pressure. Moreover, in rough condition, high pressure assistance made it possible to increase tool life by up to 400%.

Strength of Cutting Tool in Titanium Alloy Machining

2016 ◽  
Vol 685 ◽  
pp. 427-431 ◽  
Author(s):  
Victor Kozlov ◽  
Jia Yu Zhang
Keyword(s):  
Titanium Alloy ◽  
Cutting Force ◽  
Cutting Tool ◽  
Flank Wear ◽  
Cutting Edge ◽  
Contact Load ◽  
Internal Stresses ◽  
Compression Stress ◽  
Clearance Angle ◽  
Specific Contact

In this paper, contact conditions between cutting tool and work material, strength of cutting tool are analyzed. Experimental and theoretical studies of contact load distribution on the artificial flank wear-land that appears on the cutter in a free orthogonal turning disk of titanium alloy (Ti-6Al-2Mo-2Cr) are described. Calculations of internal stresses by the method of finite elements show that for the sharp cutter the main stresses into cutting wedge near to the cutting edge are compression stresses, very large (10 000 MPa) and exceed ultimate compression stress for cemented carbide. Decreasing of main stress with appearance of wear on the flank explains ability working of cutter even at large wear on the flank. Increasing of cutter’s break off probability with appearance of large wear on the flank is explained by increasing of zone where the internal stresses are large enough (more or equal 3 000 MPa) and increasing of defects probability into this zone, which serves as source of cracks. Abbreviation and symbols: m/s – meter per second (cutting speed v); mm/r – millimeter per revolution (feed rate f); MPa – mega Pascal (specific contact load as stress σ or τ); hf – the width of the flank wear land (chamfer) of the cutting tool, flank wear land can be natural or artificial like in this paper [mm]; xh – distance from the cutting edge on the surface of the flank wear land [mm]; σh – normal specific contact load on the flank land [MPa]; τh – shear (tangential) specific contact load on the flank land [MPa]; HSS – high speed steel (material of cutting tool); Py r – radial component of cutting force on the rake face [N]; Pz – tangential component of cutting force [N]; γ – rake angle of the cutting tool [°]; α – clearance angle of the sharp cutting tool [°]; αh – clearance angle of the flank wear land [°]; b – width of a machined plate or disk [mm]; σ-UTS - ultimate compression stress [MPa]; σUTS - ultimate tensile stress [MPa].

Calculation of Contact Stresses during Titanium Alloy Cutting

2018 ◽  
Vol 769 ◽  
pp. 364-370
Author(s):  
Victor Kozlov ◽  
Jia Yu Zhang ◽  
Ying Bin Guo ◽  
Sai Kiran Sabavath
Keyword(s):  
Titanium Alloy ◽  
Feed Rate ◽  
Cutting Tool ◽  
Contact Stresses ◽  
Cutting Edge ◽  
Initial Time ◽  
Small Magnitude ◽  
Normal Contact Stress ◽  
Normal Contact ◽  
Flank Surface

The paper presents data about distribution of contact stresses on a rake surface and flank-land of a cutter in free orthogonal turning of a disk made from a titanium alloy (Ti-6Al-2Mo-2Cr). On the cutting edge of the bar blade, there is a normal force Nρ, directed perpendicularly to a transient surface, with a large magnitude of specific linear force qN r= 182.6 N/mm, but the tangential force on the cutting edge Fρis equal to zero. On the rake surface, there are uniformly distributed shear contact stresses with very small magnitude of τ ≈ const ≈ 25 MPa, irrespective of feed rate, which speaks about plastic character of the contact on the rake surface. The greatest normal contact stress on the rake surface σmax≈ 1009 MPa, irrespective of feed rate. The greatest magnitude of normal contact stresses on the flank surface chamfer near the cutting edge σh max= 3400-2200 MPa confirms the hypothesis about recovery of a transient surface sag after separation of a formed element of a chip, and explains increased wear of the cutting tool on the flank surface at initial time. Normal σhand shear τhcontact stresses on the flank surface chamfer are essentially diminish with a distance from the cutting edge. It explains working ability of the cutting tool even at very large wear on the flank surface (hf> 3 mm). Our experimental data allows calculating the components of cutting force and contact stresses on the rake and flank surfaces of cutting tools during titanium alloy (Ti-6Al-2Mo-2Cr) machining.

Research on Helical Milling Specialized Tool Based on Chip-Splitting Mechanism

2014 ◽  
Vol 1061-1062 ◽  
pp. 497-506 ◽  
Author(s):  
Qing Liang Chen ◽  
Xue Mei Chen ◽  
Zuo Heng Duan ◽  
Wen Yuan Cun
Keyword(s):  
Titanium Alloy ◽  
Service Life ◽  
Cutting Edge ◽  
Helical Milling ◽  
End Mill ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Milling Tool ◽  
Hole Making ◽  
On Chip

Compared with conventional push drilling, helical milling (orbital drilling) shows great advantages in aeronautical hard-machining materials hole making. However, helical milling of titanium alloy and carbon fiber reinforced plastic (CFRP) under dry cut condition still faces challenges such as burr of titanium alloy hole exit and CFRP hole delamination. In order to solve these problems, an innovative helical milling tool with distributed multi-point front cutting edge is designed based on the chip-splitting mechanism and tool movement feature. The description of cutting edge movement track and simulation of chip shape is used to analyze different functions of front and peripheral cutting edges, the chip-splitting result and the specialized tool's service life. The helical milling experiments are aimed to test the performance of the specialized tool compared with that of traditional end mill. Results show that the specialized tool can machine titanium hole free of burr and CFRP hole without delamination under dry cut condition. The specialized tool has a longer service life with its machining capacity amounting to 80 titanium holes and 65 CFRP holes..

Effect of Micro-Textured Tool Parameters on Forces, Stresses, Wear Rate, and Variable Friction in Titanium Alloy Machining

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Kaushalandra Patel ◽  
Guoliang Liu ◽  
Suril R. Shah ◽  
Tuğrul Özel
Keyword(s):  
Titanium Alloy ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Tool Wear ◽  
Cutting Forces ◽  
Cutting Edge ◽  
Tool Geometry ◽  
Texture Parameters ◽  
Variable Nature ◽  
Variable Friction

Abstract Micro-textures applied to cutting tool surfaces provide certain advantages such as reducing tool forces, stresses, and temperature hence overall friction between the tool–chip contact and improving chip adherence and associated tool wear. This study explores the effect of micro-texture geometry parameters fabricated on the rake face of tungsten carbide inserts that were tested in dry turning titanium alloy Ti-6Al-4V. The effects of micro-texture geometry on the cutting forces, tool stresses, tool temperatures, tool wear rate, and variable friction coefficient were studied with 3D finite element (FE) simulations. The simulation model was validated comparing cutting forces predicted and measured. The results indicated some effects of micro-textured tool geometry parameters being significant and others are not as significant. The experiments reveal that the effects of micro-groove width, depth, and distance from cutting edge are found to be significant on cutting forces, but the spacing is not as much. The effect of increasing feed rate on cutting force and tool wear was significant and suppressed the advantages offered by micro-grooved texture tool geometry. The simulation results indicate that the effect of micro-texture parameters such as groove depth and distance from cutting edge is significant on tool temperature and wear rate. The variable nature of friction coefficient was emphasized and represented as functions of state variables such as normal stress and local temperature as well as micro-texture parameters.

scholarly journals Predictive modelling of cutting forces in end milling of titanium alloy Ti6Al4V

2016 ◽  
Vol 232 (9) ◽  
pp. 1523-1534 ◽  
Author(s):  
Yun Chen ◽  
Huaizhong Li ◽  
Jun Wang
Keyword(s):  
Titanium Alloy ◽  
Predictive Model ◽  
End Milling ◽  
Mechanistic Model ◽  
Orthogonal Cutting ◽  
Cutting Edge ◽  
Material Strength ◽  
Force Model ◽  
Serrated Chip ◽  
Titanium Alloy Ti6al4v

A cutting force model, based on a predictive model for orthogonal cutting, is developed for force predictions in end milling of titanium alloy Ti6Al4V. The model assumes a semi-stationary process for the serrated chip formation. The Johnson–Cook material model that couples strain hardening, strain rate sensitivity and thermal softening effects is applied to represent the material strength. A thermal model considering the tool thermal properties is integrated to account for the high temperature rise due to the low thermal conductivity of Ti6Al4V. To extend the predictive model to milling, the end mill is discretised into several axial slices, and an equivalent cutting edge is used to include the end cutting edge effect caused by the first axial slice. The model is assessed by comparing its prediction with the experimental results and a mechanistic model for verification. The results show that the proposed model outperforms the mechanistic model with higher accuracy in force prediction.

Finite Element Analysis of the Influence of Cutting Edge Radius on Mechanical-Thermal Distribution in High-Speed Cutting TiAl6v4

2010 ◽  
Vol 458 ◽  
pp. 295-300
Author(s):  
Yi Hang Fan ◽  
Min Li Zheng ◽  
Shu Cai Yang ◽  
Wei Zhang ◽  
De Qiang Zhang
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Equivalent Stress ◽  
Cutting Edge ◽  
Plastic Deformation Zone ◽  
Edge Structure ◽  
High Speed Cutting ◽  
Cutting Edge Radius ◽  
Thermal Distribution ◽  
Edge Radius

On the basis of analyzing the cutting edge structure and cutting edge radius measurement of high-speed insert, thermal - mechanical coupling finite element method (FEM) is used in this paper, to obtain the effect law of different cutting edge radius on the mechanical-thermal distribution of high-speed cutting TiAl6V4. At last, cutting experiments are carried out to verify FEM results. There is a clear exposition of the intrinsic reason why the cutting edge radius has influence on the mechanical -thermal distribution of high-speed cutting process. The results indicate that the experimental results have a good agreement with FEM; with the cutting edge radius increases, cutting force increases; cutting temperature is not monotonic, but there exists an optimum edge radius that makes temperature lowest; cutting edge changes the plastic flow of materials around tool tip and broaden plastic deformation zone. The cutting edge radius has a greater impact on equivalent stress.

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