Papers by Keyword: Tool Geometry

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Authors: Kun Xian Qiu, Sheng Qin, Chun Xin Ge, Ming Chen
Abstract: Both aluminum alloy and titanium alloy have been widely used in aerospace, aviation, military and automotive industries. This research presents a study of modified drills for drilling aluminum alloy and titanium alloy. The modified drills can be expected to reduce the cutting forces and torque. A set of experiment was carried on to investigate the performance of the modified drills. A method to quantitative assess of the reduction of the thrust force and torque was given below, and the calculation shows that the modified drills can reduce the thrust force and the torque by as high as 21.16% and 90.48%, respectively, as compared to the conventional drills under the same conditions.
Authors: Matthias Schneider, Mathias Liewald
Abstract: Short cycle stretch forming (SCS) is an innovative stretch forming technology, developed by the Institute for Metal Forming Technology (IFU) at the University of Stuttgart. The SCS technology combines plane pre-stretching and deep drawing operations within the same stroke of the press ram. The sheet metal thickness is reduced, and the denting resistance as well as the yield stress are increased due to hardening effects.In this study, the SCS technology is applied to rotational-symmetric bodies. A process simulation of an SCS cupping process was carried out for producing tinplate cans. Based on these results, a tool was produced. First results showed that the metal thickness of cups for two-piece drawn and ironed (D&I) steel can bottoms can be reduced. With this technological goal, it is possible to save the material cost in series production.This paper analyses how batch fluctuations affect the thinning of cup bottoms in SCS cupping. Therefore, preliminary experiments have been conducted, using their results to improve the previously used FE process model. With the aid of this model, an FEA-based parametric study on the variation of material properties is conducted. To examine batch fluctuations, tensile tests have been taken into account, and initial material parameters for simulation, such as friction coefficient, initial blank thickness, Lankford parameter and hardening behaviour, have been varied.The results of this paper show that SCS cupping offers a promising potential for material savings and demonstrate the main effects of batch fluctuations.
Authors: X.S. Li, It Meng Low
Authors: Wen Ge Wu, Zhan Qiang Liu, Yun Ping Cheng
Abstract: The tool geometry such as rake angles and cutting edge inclination angles play significant roles in determining machining performance. The task of selecting cutting tool inserts and cutting conditions is traditionally carried out on the basis of the experience of process planners with the help of data from machining handbooks and tool catalogues. This situation urges the need for development of some intelligent tooling system to reduce these inefficiencies for optimum economic and technological machining performance. A model of turning tool mechanism having the function of controllability in changing the tool inclination angle and tool approach angle is described. The mechanism is realized through the use of three specific slopes which work simultaneously to compensate the tool tip deviation due to the change of inclination angles so that the tool tip always stays at working point in space. Based on the ‘classical’ oblique cutting operation, analytically simulated prediction of the tangential cutting forces were presented with MATLAB software.
Authors: Zhen Yu Shi, Zhan Qiang Liu
Abstract: In micromachining, the uncut chip thickness is comparable to the tool edge radius, and chip won’t be generated if the uncut chip thickness is less than a critical value, besides that, the minimum uncut chip thickness affect many factors such as the cutting force, the chip’s modality, the cutting surface quality, etc. In this paper, a geometric model is developed to predict the minimum uncut chip thickness values. The model accounts for the theory that the critical condition of producing chip is when the friction of the surface deformation asperities is zero. Two situations when the minimum value is larger or smaller than the tool edge radius respectively to predict the minimum value are discussed. The influences of tool edge radius and material’s property on the minimum uncut chip thickness are taken into account.
Authors: Rui Louro, Helena Gouveia, Paulo Brioso
Abstract: The Friction Stir Welding (FSW) process has a large industrial potential in the field of joining lightweight alloys. Due to the increasing industrial use of aluminium alloys the benefits provided by this technology are very appealing. However, this potential has not, until this time, become a reality due to the lack of relevant available information concerning the process. The lack of information is especially serious in regards to the welding tools. This component, whose importance in the FSW process cannot be overstated, has not been the subject of extensive published research due mainly to the difficulties related to the modelling of the FSW process, which means that all of the development in this field has to be conducted through a trial and error approach. This approach entails significant costs and success risks, thus reducing the capability of R&D institutions to carry out extensive research. The objective behind the work detailed in this paper is the assessment of the effects of the welding tool geometry and features in the weld quality and process productivity. The work was carried out via an experimental procedure, which consisted of carrying out several welds using different pin lengths, pin diameter, pin geometry and shoulder diameter. The geometries that were used are based on known geometries from literature and new concepts. Due to practical limitations the study was conducted using a 3mm thick AA 6082-T6 butt joint configuration. The quality of the welds was assessed through destructive and non destructive testing, namely a visual inspection, an x-ray and a macrographic examination. These results can then be used to correlate the effects of the different tool geometries with the weld quality and productivity. The process productivity can be, according to [1], directly related to the welding speed, this is due to the near absence of welding consumables in the FSW process, leading to the predominance of fixed costs. The results pertaining to this work enable a better comprehension of the manner by which the tool geometry influences the weld quality and the process productivity, thus providing a stepping stone in the ongoing task of optimizing and modelling of the FSW process. The results presented in this paper may also be useful when extrapolated to other materials and thicknesses.
Authors: Yuan Ching Lin, Ju Jen Liu, Ben Yuan Lin
Abstract: The effects of tool geometry on the microstructure and tensile shear strength of friction stir spot-welded A6061-T6 Al alloy sheets were investigated in the present study. Friction stir spot welding (FSSW) was carried out at a tool speed of 2500 rpm, plunging rate of 1 mm/s, and dwell time of 3 s. Four types of tools with the same shoulder shape and size, but different pin profiles (threaded cylindrical, smooth cylindrical, threaded triangular, and smooth triangular) were used to carry out FSSW. The mechanical and metallurgical properties of the FSSW specimens were characterized to evaluate the performance of the different tools. Experimental results show that the pin profile significantly alters the hook geometry, which in turn affects the tensile shear strength of the friction stir spot welds. The welds made using the conventional thread cylindrical tool have the largest elongation and yield the highest tensile strength (4.78 kN). The welds made using the smooth cylindrical tool have the lowest tensile strength. The welds made using the threaded triangular and smooth triangular tools both have a tensile-shear load of about 4 KN; however, the welds made using the threaded triangular tool have a better elongation than those made using the smooth triangular tool.
Authors: Zhen Yu Shi, Zhan Qiang Liu
Abstract: In this study, the effects of cutting tool geometry and workpiece hardness on surface roughness in finish hard turning of AISI 440C steel were experimental investigated. Four-factor (hardness, tool geometry, feed rate and cutting speed) two-level fractional experiments were conducted and analysis of variance (ANOVA) was performed. This study showed that the effects of workpiece hardness and tool geometry on surface roughness are statistically significant. Especially lower workpiece surface hardness and larger tool nose angle resulted in lower surface roughness because that the surface hardness influences the workpiece’s flow stress and the tool nose angle changes the contact area between the cutting tool and workpiece.
Authors: Sarwar Ali Abbasi, Ping Fa Feng
Abstract: Tool nose radius is an important geometrical parameter in the design of the tool. Due to its direct contact with the workpiece surface it have significant effect not only on the resulting surface quality but also on the tool life. Use of an end mill without nose radius can easily blend during machining due to a lot of stresses acting on the edge of the tool while the large nose radius end mill can increase the strength and rigidity of the tool but can also contribute in increasing the friction between the tool and the workpiece. Therefore careful selection of tool nose radius is important and especially important for Polycrystalline Diamond, PCD insert as this tool material has recently shown great success in terms of tool life, surface roughness and productivity over coated and uncoated carbide tools in high speed end milling of titanium alloy Ti-6Al-4V and with the use of correct tool geometry it can be further helpful in increasing tool life and surface quality. This study therefore investigates the effect of various nose radii’s (R0.1,0.2,0.4,0.8,1.2,1.6,2.4,3.2) and complete round insert end mill on cutting forces and heat distribution between tool and the chip for PCD insert and compare the results with multi-layer (Al2O3+TiAlN+TiN) coated carbide tool at high speed cutting conditions using 3-D finite element numerical simulations. Results have shown that both tools due to their difference in thermal and mechanical properties have different behavior under the conditions studied especially when the complete round insert tool is used. The use of small nose radius tool when nose radius rn is less than the axial depth of cut ap, the forces and the temperature remains quite low and slightly increases with the increase of radius until rn is smaller than ap but when rn gets larger than ap and only some portion of nose radius is involved in cutting, then forces and temperature increases considerably. While when complete round insert end mill is used the forces and temperature significantly drops (more than 50% than the largest nose radius tool studied) at the same ap for PCD insert but for multi-layer coated carbide tool it drops only slightly (20% than the largest nose radius tool studied). The reason for this difference lies in the fact that PCD tool has lower toughness, high hot strength and is more brittle than carbide tools and therefore maximum advantage can be taken only when small nose radius is used or when complete round insert tool is used as complete round insert have uniform stress distribution and also provides more stability for PCD tool material while large nose radius tool increases friction and also has more heat penetration in the tool thus resulting in higher cutting forces and temperature thus ultimately contributing in high wear of tool. While on the other hand carbide tools are only beneficial when smaller nose radius tool is used rather than round shape because of lower hot strength of the material.
Authors: Stefan Senge, Gerhard Hirt
Abstract: Hybrid structures made of aluminium and steel are used in an increasing amount to produce lightweight optimised parts, e.g. for the automotive industry. One option to produce these optimised components is a combination of a steel sheet with a reinforcing aluminium rib structure by high pressure die casting. Achieving a reliable junction between the different materials during the short casting time is a major challenge in creating these hybrid components. Improving this junction is the topic of an ongoing research study in which a form closure connection is enabled by structuring the steel surface prior to the casting process. In order to meet the demands of the later application, the surface structure has to ensure the filling during the casting as well as a stable form closure connection. Thus, deep groove structures with a perpendicular wall angel straight to the casting direction were identified, since a deeper structure increases the clamping area and a perpendicular wall angle improves the form closure connection. However, the production of this structure in a large scale and a short time becomes difficult using conventional structuring processes. In this work the capability of an adapted rolling process which consists of stacked discs with varying thickness and diameter was studied in order to manufacture these grooves. Several experiments were performed to determine the influence of the height reduction and rolling force on the resulting structure. First results obtained with the presented experiments show the good predictability of the resulting size of the structure depending on the thickness reduction and the rolling force normalised to one millimetre structured width.
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