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钻削奥氏体不锈钢的效果,除了与切削刃几何形状有关外,还与刀具涂层有关。
钻头的微观几何形状显著影响钻削效果
带有各种标准横刃修磨几何形状的麻花钻即将过时,取而代之的将是具有各种不同切削刃微观几何形状的钻头。在本研究中,试验钻头的刃口倒圆半径大致在7~14μm之间,其中有3支钻头在前刀面上增加了0.1mm的倒棱. 相似文献
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为了探究不同材料的钻削加工机理,对比分析了钛合金Ti6Al4V和铝合金Al7075-T651的钻削加工。通过有限元软件ABAQUS对钻削过程进行仿真研究,在有/无热力耦合工况下对工件应力应变、钻削力、摩擦力及能量等方面分析Ti6Al4V和Al7075-T651的差异。仿真结果表明,在非热力耦合模型中,铝合金出口处切屑以帽盖的形式去除,而钛合金则以C形切屑去除;在热力耦合的模型中,钛合金和铝合金的工件最大应力首先位于钻头横刃挤压处,随着钻头的深入,工件最大应力位于钻头主切削刃处;对比有/无热力耦合模型,发现钻削力受温度的影响最显著,其次为摩擦力,最后为塑性能,且铝合金比钛合金更容易受热软化效应的影响。 相似文献
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越来越多的加工车间正用整体硬质合金钻头取代枪钻加工深孔。
在过去枪钻占主导地位的深孔加工刀具市场中,能钻削深度达16—40倍孔径深孔的新一代整体硬质合金麻花钻正占有越来越大的份额。为了提高加工精度和排屑性能,这种整体硬质合金钻头采用了横刃和螺旋槽,并采用高密度硬质合金材料以提高硬度,从而使其能以比枪钻快5—10倍的速度进行钻削加工。 相似文献
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Various cutting techniques are available to drill holes, but drilling is the most common way in secondary machining of composite materials owing to the need for structure joining. Twist drills are widely used in the industry to produce holes rapidly and economically. Since the twist drill has a chisel edge, increasing the length of a chisel edge will result in an increase in the thrust force generated. Whereas, a saw drill has no chisel edge; it utilizes the peripheral distribution of the thrust force for drilling. As a result, the saw drill can achieve better a machining quality in drilling composite laminates than twist drill. The deviation of cutting edge that occurs in saw drill would result in an increase of thrust force during drilling, causing delamination damage when drilling composite materials in particular. A comprehensive model concerning delamination induced by the thrust force of a deviation saw drill during drilling composite materials has been established in the present study. For a deviation saw drill, the critical thrust force that triggers delamination increases with increasing β. A lower feed rate has to be used with an increasing deviation saw drill in order to prevent delamination damage. The results agree with real industrial experience. A guide for avoiding the drill deviation during drill regrinding or drill wear has been proved analytically by the proposed model, especially when the deviation ratio (β) affects the critical thrust force. This approach can be extended to examine similar deviation effects of various drills. 相似文献
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Liangshan Xiong Ning Fang Hanming Shi 《International Journal of Machine Tools and Manufacture》2009,49(7-8):667-677
The present study aims at the development of a new methodology for designing a curve-edged twist drill with an arbitrarily given distribution of the cutting angles along the tool cutting edge. The new methodology consists of 81 major mathematical equations and is developed using a method of mapping relevant planes and straight lines of a cutting tool (such as the cutting plane and the cutting edge) as corresponding image points and image lines on a projection plane. The developed methodology is used to intuitively and graphically analyze and determine the relationship between the orientation of the cutting edge and the cutting angles at each point on the cutting edge. A set of image points and image lines is established to calculate the cutting angles on the cutting edge of a twist drill, including the working tool rake angle, the working tool inclination angle, the working cutting edge angle, and the working normal rake angle. Three computer case studies are provided to show curved cutting edges that correspond, respectively, to a linear distribution of the working tool rake angle, a combined linear and uniform distribution of the working tool rake angle, and a linear distribution of the working tool inclination angle along the tool cutting edge. Finally, a set of metal drilling experiments is performed to compare the drilling torque and the thrust force between a conventional straight-edged twist drill and a new curve-edged twist drill that has a combined linear and uniform distribution of the working tool rake angle along the tool cutting edge. The experimental results show that the new curve-edged drill reduces the drilling torque by 28.5% and the thrust force by 24.6% on average. 相似文献
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Mathematical models of conical twist drill points usually require that the cutting edge of the drill be straight in three-dimensional space. This requirement restricts the clearance angle to undesirably small values near the chisel edge. By rotating the drill about its axis 5–10° before sharpening, the clearance angle near the chisel edge can be increased at the small penalty of having a slightly curved cutting edge. 相似文献
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A study of high-performance plane rake faced twist drills.: Part I: Geometrical analysis and experimental investigation 总被引:2,自引:1,他引:1
A study of a modified drill point design with plane rake faces for drilling high-tensile steels is presented. A geometrical analysis has shown that the modified drill point design yields positive normal rake angle on the entire lips and point relieving in the vicinity of the chisel edge. This drill geometry can be expected to reduce the cutting forces and torque, and hence reduce the possible drill breakages when drilling high-tensile steels. An experimental study of drilling an ASSAB 4340 high-tensile steel with 7–13 mm titanium nitride (TiN) coated high-speed steel (HSS) drills has shown that the modified drills can reduce the thrust force by as much as 46.9%, as compared to the conventional twist drills under the corresponding cutting conditions, while the average reduction of torque is 13.2%. Drill-life tests have also been carried out and confirmed the superiority of the modified drills over the conventional twist drills. In some cases, the conventional drills were broken inside the workpiece, while the modified drills performed very well under the same cutting conditions. To mathematically predict the drilling performance and optimise the drilling process using the plane rake faced drills, predictive models for the cutting forces, torque and power will be developed in the second part of this investigation. 相似文献
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Psang Dain Lin Chian Sheng Tzeng 《International Journal of Machine Tools and Manufacture》2007,47(15):2218-2229
Traditionally, twist drills are reconditioned by thinning the web so the correct chisel edge length is restored. Recently, thinning has been included in the original design of drills so as to reduce torque and tool force. Because the International Standards Organization (ISO) has a system which can comprehensively model conventional twist drills but cannot model thinning specifications, this paper presents a system for precise mathematical modeling and CNC control of a 6-axis grinding workstation for drill thinning. The presented method determines the position and orientation of the grinding wheel based on the evaluated rake and clearance angles of ISO standards for 2-flute twist drills. The mathematical model and background are discussed. For verification and demonstration, two experimental drills are produced to the identical ISO standard except that one is thinned. The modeling herein is of value to industry and research if incorporated into computer software for drill design and manufacture. It is suitable for linear notch-type cutting with controlled variable rake angle along the secondary cutting edge for purposes of thinning, notching, dubbing and advanced drill research. 相似文献
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This paper describes the performance characteristics of a new type of carbide head twist drill with four flutes, four major cutting edges, and one chisel edge. This drill shows great potential for significantly improving drilling accuracy and productivity. The drill produces holes that are as good as reamed holes. The body and point geometries and the cutting characteristics of the four-flute drill are described, along with the accuracies of hole location, angularity, size and roundness. Cutting forces, drill wear and chip morphology during cast iron drilling are also discussed. The four-flute drill deflects and vibrates much less than two-flute drills, especially in interrupted cutting cases. A patent is pending for this drill. 相似文献
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《International Journal of Machine Tool Design and Research》1985,25(3):209-227
Deficiencies in the definitions of some of the angles in the ISO on Cutting Tool Geometry have been noted and new definitions are proposed. It is shown that some of the trigonometrical relationships interrelating the various angles derived for the acute tool cutting edge angle do not apply when the tool cutting edge angle is greater than 90°, as can occur with certain cutting tools. A consistent set of relationships is presented for the total range of the cutting edge angle.Relationships are presented for the various angles on the cutting lip and chisel edge of a twist drill and the effects of radius and feed on the various parameters are shown diagrammatically. 相似文献
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《Journal of Materials Processing Technology》2014,214(4):1018-1026
In this paper, an improved mechanistic model is developed to predict the thrust force and torque for bone-drilling operation. The cutting action at the drill point is divided into three regions: the cutting lips, outer portion of the chisel edge (the secondary cutting edges), and inner portion of the chisel edge (the indentation zone). Models that account for the unique mechanics of the cutting process for each of the three regions are formulated. The models are calibrated to bovine cortical bone material using specific cutting pressure equations with modification to take advantage of the characteristics of the drill point geometry. The models are validated for the cutting lips, the chisel edge, and entire drill point for a wide range of spindle speed and feed rate. The predicted results agree well with experimental results. Only the predictions for the drilling torque on the chisel edge are lower than the experimental results under some drilling conditions. The model can assist in the selection of favorable drilling conditions and drill-bit geometries for bone-drilling operations. 相似文献
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Mathematical model for helical drill point 总被引:1,自引:0,他引:1
Helical drill points provide a superior cutting performance in drilling operations, particularly in micro-hole drilling. This paper presents a comprehensive and straightforward method for the design of helical drill points. The proposed method has three particular features. Firstly, a mathematical model of the helicoid grinding surface is developed. This model allows the normal and tangential vectors of the abrasive wheel to be obtained explicitly. Secondly, the mathematical models of the flute and flank surfaces are integrated and therefore the cutting and chisel edges can be obtained by numerical calculation. Finally, the derivation of the model is straightforward and expresses the drill's characteristics (e.g. the semi-point angle, chisel edge, lip clearance angle, heel clearance, angle tool cutting edge inclination, normal rake angle and normal clearance angle) in accordance with all current international standards. The proposed model is capable of describing a wide range of helical drills. The methodology presented in this study facilitates the production of helical drills on a 6-axis CNC grinding machine. 相似文献
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The effect of chisel length and associated pilot hole on delamination when drilling composite materials 总被引:1,自引:0,他引:1
Drilling-induced delamination often occurs both at the entrance and the exit of the workpiece during drilling of composite material. Investigators have studied analytically and experimentally that delamination in drilling can be correlated to the thrust force of the drill. With a pre-drilled pilot hole, the delamination can be reduced significantly. Early reference reported models of drilling-induced delamination, however, the effect of chisel edge length and pilot hole diameter on delamination is rarely discussed. The optimal range of chisel edge length with respect to drill diameter is derived in this paper. 相似文献