Tool Design Parameters Research Articles

On the critical failure mode transition depth for rock cutting with different back rake angles

The failure mode of rock under cutting exhibits a ductile-brittle transition as the depth of cut increases. The critical transition depth, beyond which energy consumed in brittle fracturing surpasses the energy consumed in plastic flow, is the key to differentiating between the ductile and brittle cutting modes and therefore is an important parameter to optimise tool design and operational parameters to meet specific application requirements. This critical failure mode transition depth depends not only on rock properties but also on cutting operational parameters, in particular, the back rake angle. In this work, a series of rock cutting tests were performed to investigate the influence of back rake angle on the critical failure mode transition depth. Size effect law is employed first to identify the critical transition depths, which are then compared with values derived from the analysis of specific cutting energy. It is found that the critical failure mode transition depth increases with the back rake angle. This suggests that the brittle fracture failure induced at large depth of cut can be inhibited by increasing the back rake angle. Cutting at a small back rake angle, on the other hand, is desirable if minimisation of the cutting energy is required in the application.

Modeling of tool blockage condition in cutting tool design for rotary ultrasonic machining of composites

Although superior in properties, composite materials still have problems in machining, such as delamination, cracking, burning, tool blockage, and cost and efficiency issues. These problems can prevent wide application of extraordinary composite materials. As an effective method in composite machining, rotary ultrasonic machining (RUM) process has been paid much attention to recently. The current studies on RUM tool design are mostly based on experiments. However, the insufficiency of RUM tool design theory would generally result in the tool blockage, which subsequently leads to the sharp increase in cutting force and poor machining quality in the engineer application. Besides, few investigations are made to combine tool design parameters with machining conditions to avoid tool blockage during RUM process. In this work, based on the RUM material removal mechanism, two models for the chip space and the chip length are built. Thus, the tool blockage condition in RUM is linked with the tool design parameters and the cutting parameters. Experimental study is performed for theoretical verification. Due to the differences in the modalities of the chip, two typical types of composites, C/SiC and CFRP T700, are selected to obtain their tool blockage conditions. The test results show that to prevent the occurrence of blockage, the chip space should be greater than the chip length in C/SiC milling, while in T700 milling, the chip space should be at least over 8 times greater than the chip length.

МОДЕЛИРОВАНИЕ ПАРАМЕТРОВ ЗОНЫ ЦИЛИНДРИЧЕСКОГО КОНТАКТА ПРИ ПЛАКИРОВАНИИ ГИБКИМ ИНСТРУМЕНТОМ

The paper considers new effective high production method of combined treatment of surfaces of machine industry goods using cladding with a flexible tool (CFT). As a rule, a wire wheel brush is used as such flexible tool. CFT is a combined method of modifying the surface of treated item involving the simultaneous deformational strengthening of surface and applying of coatings made of various materials with required functional properties. The paper presents the mathematical model of determining the geometry and energy parameters of the contact area when using cladding of cylindrical surfaces of treated items with a wire tool. The model is designed using the elliptic parameters method of the elastic rods theory. The model is based on the algorithm of the computational and analytical method containing the cycle of simultaneous selection of the angle identifying the position of a flexible element in the contact area and the modular angle the input parameter of which is the ordinate of the contact point in the fixed system of reference. The paper presents the analysis of the stressed state of wire tool bristles, which is the basic element of cladding assemblies. The authors considered the influence of wire tool design parameters and the cladding modes on the values of maximum actual stresses that occur in the bristles when sliding along the area of contact with the treated item. The paper presents the results of modeling of the stressed state of the wire tool bristles in the program implementing the method of finite element analysis and their comparative analysis with the results of calculation using the analytical method. Maximum discrepancy between the stress values calculated according to the proposed mathematical model and obtained using CAE-analysis was 12 %.

980MPa 초고장력 강판의 형상 동결성 향상을 통한 자동차 시트레일 부품 개발

This paper aims to ensure describe the a spring-back prevention technique for improving shape fixability by using an ultra-high strength steel sheet with 980 MPa to develop a lightweight seat rail parts. Ultra-high strength steel gives a potential for considerable weight reduction and a cost-effective way to produce energy efficient vehicles. The influence of a spring-back of seat rail parts on the shape fixability in forming processes was investigated to be solved by an adjustment of the appropriate tool design and process parameters. The computed results for improving shape fixability were in good agreement with the experimental results.

Specific Energy as an Index to Identify the Critical Failure Mode Transition Depth in Rock Cutting

Rock cutting typically involves driving a rigid cutter across the rock surface at certain depth of cut and is used to remove rock material in various engineering applications. It has been established that there exist two distinct failure modes in rock cutting, i.e. ductile mode and brittle mode. The ductile mode takes precedence when the cut is shallow and the increase in the depth of cut leads to rock failure gradually shifted to brittle-dominant mode. The threshold depth or the critical transition depth, at which rock failure under cutting changes from the ductile to the brittle mode, is associated with not only the rock properties but also the cutting operational parameters and the understanding of this threshold is important to optimise the tool design and operational parameters. In this study, a new method termed the specific cutting energy transition model is proposed from an energy perspective which is demonstrated to be much more effective in identifying the critical transition depth compared with existing approaches. In the ductile failure cutting mode, the specific cutting energy is found to be independent of the depth of cut; but in the brittle failure cutting mode, the specific cutting energy is found to be dependent on the depth of cut following a power-law relationship. The critical transition depth is identified as the intersection point between these two relationships. Experimental tests on two types of rocks with different combinations of cutting velocity, depth of cut and back rake angle are conducted and the application of the proposed model on these cutting datasets has demonstrated that the model can provide a very effective tool to analyse the cutting mechanism and to identify the critical transition depth.

Influence of tool design and process parameters on dissimilar friction stir welding of copper to AA6061-T651 joints

In the present investigation, two different tool designs along with different process parameters such as tool pin offset, welding speed and axial plunge load were used to produce dissimilar copper to aluminium (6061-T651) friction stir welding joints. Macrostructure and microstructure analysis, tensile test, hardness measurement test, scattered electron microscopy and electron-dispersive tests were performed to evaluate the weldability and weld properties of dissimilar copper–aluminium joints. The results revealed that defect-free dissimilar friction stir welding was achieved using a cylindrical tool pin profile. On the other hand, the taper tool pin profile was not found to be suitable for dissimilar friction stir welding system (FSW). Maximum tensile strength of 133 MPa and hardness of 181 HV (in the nugget zone) were obtained when FSW process parameters such as rotational speed, welding speed, tilt angle, tool pin offset and tool pin profile were kept at 1500 rpm, 40 mm/min, 2°, 2 mm and cylindrical profile, respectively. Axial plunge load value depended on the shoulder diameter as well as on the tilt angle. Axial plunge load range from 600 to 700 kgf was used to achieve defect-free copper to AA6061-T651 (of 6.3 mm in thickness) friction stir welded joint.

Experimental Investigations on Formability of Aluminum Tailor Friction Stir Welded Blanks in Deep Drawing Process

In the present work, tailor friction stir welded blanks (TFSWBs) were fabricated successfully using 2.0-mm-thick AA5754-H22 and AA5052-H32 sheet metals with optimized tool design and process parameters. Taguchi L9 orthogonal array has been used to design the friction stir welding experiments, and the Grey relational analysis has been applied for the multi objective optimization in order to maximize the weld strength and total elongation reducing the surface roughness and energy consumption. The formability of the TFSWBs and parent materials was evaluated and compared in terms of limiting drawing ratio (LDR) using a conventional circular die. It was found that the formability of the TFSWBs was comparable with that of both the parent materials without failure in the weldment. A modified conical tractrix die (MCTD) was proposed to enhance the LDR of the TFSWBs. It was found that the formability was improved by 27% using the MCTD.

Influence of Tool Design and Process Parameters on Friction Stir Weldability of AZ31B Magnesium Alloy

The contribution is dealing with suggestion of tool geometry affecting weldability of Mg alloy AZ31B at friction stir welding. Four welding tool made of tool steel H13 (X40CrMoV5-1) with different geometry have been used at welding. Weld joints with high quality have been performed at following parameters: tool revolutions 600 rpm, welding speed 40 to 120 mm/min, angle of inclination 3° and pressure force 38 kN. Area of weld metal accounted fine-grained structure with average dimension of grain 13 μm. Structure is formed by solid solution α - Mg, Al-Mn particles and compound MgAl3Mn2. Strength of weld joint reaches value 265 MPa. Fracture areas accounted character of ductile fracture.

Considering Anisotropic Material Behaviour of Sheet Metals for Ductile Fracture Prediction

In the manufacturing process of body in white components made from sheet metal it is state of the art to accompany the process by means of finite element analysis. A main criterion for determining a feasible tool design and process parameters is the prediction of material failure, which can be categorized in instability and ductile fracture. The ductile fracture failure mode is more likely to occur, as more advanced high strength steels and aluminium alloys are used for body in white components. Therefore various approaches have been presented to model ductile fracture over the past years. However, there is no guideline to determine which models are suitable for predicting ductile fracture. The same applies when it comes to choosing experiments and calibration of model parameters. A suitable model calibration is vital, as the fracture prediction depends on the determined model parameters. Usually an isotropic material behaviour is assumed for calibration of fracture models. However, sheet metals can show an anisotropic material behaviour due to the rolling process. Therefore it is arguable if an isotropic material model can be applied when fracture models are calibrated.

Evaluation and Validation of Methods to Determine Limit Strain States with Focus on Modeling Ductile Fracture

In the manufacturing process of body in white components made from sheet metal it is state of the art to accompany the process by means of finite element analysis. A main criterion for determining a feasible tool design and production process parameters is the prediction of material failure, which can be categorized in instability and ductile fracture. The ductile fracture failure mode is more likely to occur, as more advanced high strength steels and aluminum alloys are used for body in white components. Therefore different approaches have been presented to model ductile fracture over the past years. This task is more challenging when the material is exposed to arbitrary loading paths that can occur in deep drawing processes. However there is no guideline for sheet metal forming applications to determine which models for predicting ductile fracture are suitable, which experiments are necessary and how calibration of model parameters and validation of model prediction can be performed. Additionally there is no standard established that prescribes the evaluation of limit strain states from experiments. Suitable limit strain states are a basic requirement for prediction of ductile fracture as they are used for calibration of fracture models. In this paper, two methods for evaluation of limit strains are discussed and applied to tensile specimens with circular hole and circular cut outs made from aluminum alloy AlSi0.6Mg0.5. One validation experiment is used to investigate failure prediction that is based on limit strain states from different evaluation methods.

Numerical Analysis of Multi-Field Coupled Phenomena in Friction Stir Welding and Applications

Friction stir welding (FSW) is an advanced solid state joining technology, which was invented by TWI in 1991. During the process, large amount of heat is generated due to the friction between the tool and the material. As a result, the metal around the tool is softened as the temperature rises, and significant plastic flow occurs. So FSW is a complex process with multi-field coupled phenomena. Material flow plays a central role in FSW. But it is still difficult to reveal the material flow regime and joining mechanism during FSW process. Numerical simulation is a powerful tool for investigating the metal-flow-related complex phenomena during FSW. Meanwhile, numerical simulation could also help to optimize FSW tool design and FSW parameters. In this paper, we review the recent development in simulation of material flow during FSW. Then, the important issues in modeling multi field coupled phenomena during FSW are summarized, which include the heat generation mechanism, the temperature and strain rate dependent material’s behavior, and the interaction between tool and material. Finally, a comprehensive simulation model is presented, which enables advanced study on the coupled phenomena of heat generation, temperature distribution, material flow, and defects formation. This model has shown potential applications in simulating the relation between the transport of material and the macrostructure formation or defects formation. In spite of these progresses, simulation of material flow during FSW still need quite a lot of researches to fulfill industry requirement.

Studies on Effect of Tool Design and Welding Parameters on the Friction Stir Welding of Dissimilar Aluminium Alloys AA 5052 – AA 6061

This research paper deals with the characterization of friction stir welded dissimilar Aluminium alloys AA 5052 and AA6061. The coupons of above metals were friction - stir welded using cylindrical pin tool using at constant speed of 710rpm and at two different feed rates of 28 and 20mm/min. Macrographs showed proper mixing due to effective stirring of cylindrical tool pin while keeping the lower feed rate. Further, extensive micro structural examination showed variation of grain size in each zone and their influence on mechanical properties. Tensile test and hardness measurements were done as a part of mechanical characterization. Correlating mechanical and metallurgical properties it is deduced that the sample welded at lower feed rate performed better in terms of ductility.

Therblig-based energy supply modeling of computer numerical control machine tools

Abstract Machining processes are widely used in manufacturing industries and consume large amounts of energy. Research suggests that it is essential to characterize machining processes energy consumption for low carbon manufacturing. Therblig-based energy demand modeling methodology is a powerful tool to evaluate energy consumption of machining processes quantitatively. Here Therbligs are defined as a set of fundamental motions required for machine tool to perform an operation. However, there is a lack of power models of Therbligs, which makes calculation and optimization of energy consumption hard to carry on. This research aims to develop Therblig power models for calculating the energy supply of computer numerical control (CNC) machine tools using machining process parameters. Power of each Therblig is modeled taking machine tool design and operating parameters into account. The developed parametric power models of each Therblig are tested on two CNC lathes and the results showed that the developed models can provide reliable prediction of Therblig power of CNC machine tools.

Experimental Study and Simulation Analysis on Ball-End Cutter Milling Titanium Alloy Based on the Geometric Parameters Optimization

Titanium alloy materials are widely used in the field of aero-engine, the complex surface forming of key parts usually use the ball end mill. First, optimized and designed tool based on the main geometric parameters of the tool, the experimental researching on solid carbide ball end mill milling TC4 titanium alloy was performed based on orthogonal combination of geometric parameters. Second, made a concrete analysis of the milling force collected in the experiment, tool geometry parameters were optimized based on the theoretical and practical. Then analyzed the optimized tool milling force changing rules under finite element milling simulation. Influence of milling parameters on milling force was analyzed with the single factor experiment for the optimized tool, milling parameters were optimized by drawing the force curve. The above studies provide a reference for the actual production of titanium alloy semi-finishing and finishing in tool design and milling parameters selection.

Numerical Studies on Friction Stir Welding of Lightweight Materials

Friction stir welding (FSW) is a relatively new solid-state fastening method which is suitable for joining advanced lightweight metal sheets that are hard to weld. Latest literature relating to finite element analysis (FEA) of FSW process is reviewed in this paper. The recent development in FEA of FSW process is described with particular reference to three major factors that influence the performance of FSW joints: modeling technique, tool design and process parameters. The main FE methods used in FSW process are discussed and illustrated with brief case studies from the literature.

Modification of Initial Blank Shape to Minimize Earing in Deep Drawing Process

Earing is a common defect that occurs in deep drawing process due to non-uniform material properties within the plane of the sheet that is planar anisotropy. In this study, efforts were made to study the earing problem in deep drawing of cylindrical cups by finite element modeling using HYPERWORKS6.10. Interstitial Free (IF) steel sheet of 1.0 mm thickness has been considered as it has wide application in fabricating critical automobile components. Mechanical properties of IF steel along with tool design parameters were incorporated in the finite element modeling of deep drawing process.Significant earing was observed at rolling and transverse direction in the deformed cup from a circular blank. The cup heights were measured at several points with respect to the rolling direction of the sheet. To minimize earing, flow of material was observed at various steps during the simulation and accordingly initial blank shape had been modified. Modified blanks showed significant reduction in earing and improvement in thickness distribution in simulation.

Influence of process parameters in mechanical clinching with extensible dies

The influence of clinching tool design in joining metal sheets by the clinching process with extensible dies is investigated. The material flow during the clinching process was examined experimentally and numerically. The geometrical and mechanical characteristics of joints produced under different processing conditions, that is, forming loads, were used to calibrate and validate a 3D finite element model of the clinching process. Then, the model was utilized to evaluate the influence of clinching tool design parameters, namely the punch diameter, the punch corner radius, the fixed die depth, the fixed die diameter, and the die corner radius. The effects of design parameters on the cross section of a clinched joint, the required forming load and the joint strength were analysed and the appropriate processing window was determined. According to the achieved results, the main benefits and drawbacks of each configuration are discussed.

Application of axiomatic design principles to identify more sustainable strategies for grinding

It has become increasingly important for manufacturers to implement sustainability into tool and process design. Existing models that evaluate the sustainability of abrasive processes focus mostly on case studies of selected energy and resource streams and rarely contain holistic process models. This study uses basic principles of axiomatic design to fundamentally describe grinding technology in a way that can be used for life cycle assessment. The functional requirements of the machining process are linked to process, tool, and coolant design parameters based upon common process understanding. However, these connections leave space for future quantitative and qualitative formulae. Sustainability metrics are then connected to the axiomatic process model. This work represents a first effort in developing this type of model. Finally, the model is used to qualitatively evaluate the impact of grit size on process sustainability showing that the method is feasible to identify strategies to increase sustainability in grinding.

Microstructure and Mechanical Performance of Friction Stir Spot-Welded Aluminum-5754 Sheets

Friction stir spot welding (FSSW) is a recent trend of joining light-weight sheet metals while fabricating automotive and aerospace body components. For the successful application of this solid-state welding process, it is imperative to have a thorough understanding of the weld microstructure, mechanical performance, and failure mechanism. In the present study, FSSW of aluminum-5754 sheet metal was tried using tools with circular and tapered pin considering different tool rotational speeds, plunge depths, and dwell times. The effects of tool design and process parameters on temperature distribution near the sheet-tool interface, weld microstructure, weld strength, and failure modes were studied. It was found that the peak temperature was higher while welding with a tool having circular pin compared to tapered pin, leading to a bigger dynamic recrystallized stir zone (SZ) with a hook tip bending towards the upper sheet and away from the keyhole. Hence, higher lap shear separation load was observed in the welds made from circular pin compared to those made from tapered pin. Due to influence of size and hardness of SZ on crack propagation, three different failure modes of weld nugget were observed through optical cross-sectional micrograph and SEM fractographs.

Tool Design and Speed Parameters Effects on Microstructure and Tensile Strength of Friction Stir Welding (FSW) 5052 Al Alloys

there are some parameters in friction stir welding (FSW) technique such as tool design, tool rotation speed and tool travel which can be controlled in a precise manner thus controlling the energy input into the system. In this study the effects of these parameters were investigated on microstructure and tensile strength of 5052 aluminum alloy. Roll sheets of this alloy were welded by FSW method at different rotation speeds (400, 800, 1600 and 2500 rpm), welding speeds (50 and 100 mm/min) and tools shoulder diameters (14 and 20 mm). The microstructure results showed that the stir zone (SZ) and thermo-mechanically affected zone (TMAZ) had dynamically recrystallized and recovered respectively. Also the tensile strength of samples welded at tool rotation speeds of 400 and 800 rpm, travel speed 50 mm/min and tools shoulder diameter of 20 mm is similar to that of base metal. The tool rotation speeds of 400 rpm have a good welding ability with higher travel speed and lower tools shoulder diameter.