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In line with engineering research focusing on metal tools, techniques to record the attribute of 'edge sharpness' on stone tools can include both mechanical and micro-geometric approaches. Mechanically-defined sharpness techniques used in lithic studies are now well established and align with engineering research. The single micro-geometrically-defined technique—tip curvature—is novel relative to approaches used elsewhere, and has not explicitly been tested for its ability to describe the attribute of sharpness. Here, using experimental flakes produced on basalt, chert, and quartzite sourced at Olduvai Gorge (Tanzania), we investigate the relationship between tip curvature and the force and work required to initiate a cut. We do this using controlled cutting tests and analysis of high-resolution microCT scans. Results indicate cutting force and work to display significant dependent relationships with tip curvature, suggesting the latter to be an appropriate metric to record the sharpness of lithic tools. Differences in relationship strength were observed dependent on the measurement scales and edge distances used. Tip curvature is also demonstrated to distinguish between the sharpness of different raw materials. Our data also indicate the predictive relationship between tip curvature and cutting force/work to be one of the strongest yet identified between a stone tool morphological attribute and its cutting performance. Together, this study demonstrates tip curvature to be an appropriate attribute for describing the sharpness of a stone tool's working edge in diverse raw material scenarios, and that it can be highly predictive of a stone tool's functional performance. [ABSTRACT FROM AUTHOR]

The aim of the work is to create a computer program in the 3D CAD system T Flex CAD allowing the creation of parametric models for the design and construction of a modular hob cutter for the selected gearing. The thesis includes the analysis of the problem of hob cutters for the production of spur gearing with an involute profile, the analysis of the initial surface and the shape of the tool cutting edge for the involute surface, the determination of the basic profile of the cutting edge of the hob cutter (geometry of the basic worm, geometry of the cutting edge) and the calculation of the design parameters of the tool. The individual calculations will be programmed in the 3D CAD system T Flex CAD, which will allow to generate a specific 3D model of the hob cutter based on the change of input requirements for the production of a given spur gear (module, engagement angle, tooth inclination angle), with the possibility of displaying the required tool in a 2D view in its base, normal and side planes, which will be in the form of a standard technical drawing. This paper presents the preparation (unification calculations, introduction) before the final version of the computer program for the creation of the parametric tool models. [ABSTRACT FROM AUTHOR]

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The ball joint parts made of forged steel are quite important in the suspension system. The quality of production of ball joint parts is very important because of their role. Some basic defects can be found in the hole edge form. These defects affect the hole quality of ball joint parts. In this study, the effects of cryogenic processing on the wear of AISI D2 punches and the effects of punch wear on the hole edge geometry of hot forged AISI 1040 steel ball joint parts were investigated. The hole geometry changes are generally associated with punch wear and process parameters. For the purpose of investigation, piercing was carried out using an eccentric press with AISI D2 tool steel punches on 6.0 mm-thick ball joint pieces. The punches were traditionally heat treated. Some of the punches were cryogenic-treated at -145 °C in addition to the conventional heat treatment. Weight loss values were measured to assess the punch wear, and SEM and OM images were analysed. At the end of the industrial piercing process, it was found that the D2 tool steel punch wear decreased with cryogenic process applied and the size changes in the hole edge geometry of the punched 1040 hot forged steel parts turned out to be less marked. [ABSTRACT FROM AUTHOR]

Although extensive focus has been placed on the ballistic performance of projectiles with certain macroscale geometries and dimensions, the microscale geometries are not as rigorously standardized. The localized stress concentrations arising from microscale geometries introduce multiaxial and locally concentrated stress states within the constituent material of the soft-armor target, which can result in premature failure that is not predicted with existing models. In this study, the microscale edge/corner geometries of right circular cylinder (RCC) projectiles are varied, and their respective ballistic performance was determined via experiments to examine the effects of the localized stress concentrations. Target panels were examined post-mortem and the effects of these localized stress concentrations on the failure modes were quantified. Experiments results indicate that stress concentrations drastically reduce the ballistic performance of the soft armor targets, and the fabric targets appear to fail without significant strain energy absorption. [ABSTRACT FROM AUTHOR]

The paper deals with the dependence of cutting force on the breaker of an indexable cutting insert (ICI). The experiment monitored individual cutting force components for different insert breakers, cutting speeds and feed rates during machining. The cutting depth remained constant. The tool holder, material and coating of the indexable cutting insert was also identical. [ABSTRACT FROM AUTHOR]

For the shaping of welded straight-seam large-diameter pipe in the TESA 1420 production line, methods are proposed for calculating the geometric parameters of the edge of the blank and the profile of the deforming tool. The edge geometry obtained on an edge-bending press is compared when using surface tools of involute and single-radius type. For tools of single-radius type, edge geometry consistent with the required shaping quality may be produced. For the edge-bending presses, a method of calculating the edge geometry in loading and unloading is outlined. The height of the bent edge, the residual radii of curvature, and the coordinates of the loading and unloading points at the external and internal edge contour of the pipe blank are determined. The coordinates of the edge formed by a tool with an involute profile are also calculated. The involute tool profile is universal on passing from one type of tool to another within a standardized group. The calculation permit conversion from an involute edge profile to a multiradial profile, followed by determination of the fixed coordinates of the points of the blank after springback. On the basis of those coordinates, the output edge geometry is estimated. Within the 1220-1420 mm standardized group, the longitudinal edge deformation for the 1220 × 10 mm type is calculated. Standardization is found to be much simpler with a single- radius tool profile. For edge-bending presses, a method of calculating the edge parameters of the pipe blank when using a tool with an involute contact profile is developed and tested in industrial conditions. Single- radius calibration of the profile of the edge-bending tool is proposed, such that fixed time coordinates are ensured. These are analogous to the coordinates with an involute punch profile. The blank's weighted mean radius of curvature maximizes the agreement of the coordinates of the blank profile at fixed points in both approaches. (The maximum discrepancy is no more than 6-7%.) [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation on turning hardened DF-3 tool steel (∼58HRC) with PVD-TiN coated mixed ceramic. We focused on the effect of chamfer and honed edge geometry on tool wear, tool life, cutting forces and surface finish of the machined workpiece. The effects of the process parameters on performance characteristics were investigated using ANOVA. It was found that longer tool life was recorded with chamfered edge geometry at various cutting conditions. The typical damage observed as flank and crater wear for ceramic tools and abrasive wear was found as the main mechanism.The optimal cutting speed was 155 m/min, with which a tolerable tool life and volume of material removal was obtained for both edges geometry. Finer machined surface was left by chamfered tool with feeds and speeds in the range of 0.125-0.05 mm/rev and 155-210 m/min, respectively; also, cutting forces decrease with increased cutting speed. The obtained consequence of cutting forces shows that tool wear has a considerable effect on cutting forces and greater forces values recorded with honed tools. [ABSTRACT FROM AUTHOR]

In this work we demonstrate the advantages of conformal mapping methods for the design of capacitive sensor setups. If the setups are modeled appropriately, the respective Laplace equations can be solved utilizing conformal mapping methods. These methods yield the equations de-scribing the electric field of the sensor setups. The field equations contain the distinct geometric properties of the sensor setups. An in depth analysis of these equations permits the optimization of the sensor setups with respect to their sensitivities. This approach also facilitates the application of efficient signal processing methods. In addition, we propose a method which expands the application range of conformal maps produced by the Schwarz-Christoffel transform. This method permits the analysis of more complex sensor setups [ABSTRACT FROM AUTHOR]

Abstract: The erosive wear of borosilicate glass edges by the unidirectional low velocity impacts of abrasive balls was investigated. Glass edges were chamfered with included angles of 120° and 135° to eliminate macro-scale edge chipping, and as a result wear appeared as a narrow band along the edge. The rate of wear decreased during an initial transition stage to a steady-state wear rate. Fundamental differences were observed between edge wear by abrasive and smooth spherical media. An earlier numerical model was adapted to predict the evolution of the edge profile by applying random indentations to the edge, evaluating the possibility of chip formation, and modifying the edge profile accordingly. The predictions of the model compared quite well with the experimentally measured amounts of wear of 120° and 135° edges at normal impact velocities and impacts directed outward from the edge. [Copyright &y& Elsevier]

Abstract: This paper presents investigations on hard turning with variable edge design PcBN inserts. Turning of hardened AISI 4340 steel with uniform and variable edge design PcBN inserts is conducted, forces and tool wear are measured. 3D finite element modelling is utilized to predict chip formation, forces, temperatures and tool wear on uniform and variable edge micro-geometry tools. Predicted forces and tool wear contours are compared with experiments. The temperature distributions and tool wear contours demonstrate the advantages of variable edge micro-geometry design. [Copyright &y& Elsevier]

Abstract: Stringent control on the quality of machined surface and sub-surface during high-speed machining of Inconel 718 is necessary so as to achieve components with greater reliability and longevity. This paper extends the present trend prevailing in the literature on surface integrity analysis of superalloys by performing a comprehensive investigation to analyze the nature of deformation beneath the machined surface and arrive at the thickness of machining affected zone (MAZ). The residual stress analysis, microhardness measurements and degree of work hardening in the machined sub-surfaces were used as criteria to obtain the optimum machining conditions that give machined surfaces with high integrity. It is observed that the highest cutting speed, the lowest feedrate, and the moderate depth of cut coupled with the use of honed cutting edge can ensure induction of compressive residual stresses in the machined surfaces, which in turn were found to be free of smeared areas and adhered chip particles. [Copyright &y& Elsevier]

The quality of cuts performed on titanium sheets using high tolerance plasma arc cutting (HTPAC) process was investigated under different process conditions. A 5 mm thick sheet of grade 2 commercially pure titanium was cut using several feed rates in the dross-free feed rate range and with the adoption of oxygen or nitrogen as cutting and shielding gases. When oxygen was used as cutting gas higher feed rate and geometry attributes (unevenness and kerf width) of better quality were achieved due to the oxidation reaction. The quality features of the cutting edge of HTPAC of commercially pure titanium were integrated with considerations on microstructural features related to the formation of a wide layer severely affected by plasma-induced thermal cycle and by interaction with the cutting gas. In fact, all cutting edges displayed an external layer of oxide, under which a thin layer of oxygen-enriched α-case was noticed for cuts performed with oxygen. The thickness of the total heat affected zone (HAZ) overcame 1 mm for all the cuts in nitrogen and for the slowest cut in oxygen. Temperature measurements during the passage of the torch defined the thermal cycles of the cutting process in several locations of the sheet. These are characterised by high heating rates (above 2000 K/s within the HAZ) and low cooling rates (150–580 K/s within the HAZ). An analytical model was applied to simulate the thermal effects of the material interaction with the torch in the case of slow cuts with oxygen. A comparison between predicted thermal cycles, experimental measurements and microstructural observations confirmed the reliability of the estimation in terms of extension of microstructural modifications. [Copyright &y& Elsevier]