共查询到19条相似文献,搜索用时 109 毫秒
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非自由切削的流屑角及其分叉 总被引:5,自引:1,他引:5
非自由切削流屑角η反映切削刃各部分之间的干涉程度,主要与切削层开关有关,并依照使切削功率最小的原理取值,排屑干涉引起的流屑角对切削力的影响系数kη=1+0.76η^2。在一定的切削条件下,切屑流人有不确定性,流屑角出现分叉现象。 相似文献
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在切削加工中,切削液主要起冷却、润滑、清洗排屑以及防锈作用,还能提高加工效率和加工质量。但随着经济的发展,人们环保意识的增强,切削液的负面效应正逐步被重视。从经济环保等角度看,不使用切削液的干切削加工才是理想的绿色制造工艺方法。但干切削加工时摩擦力大,切削力大,切削温度高,完全的干切削对刀具的材料、结构、几何角度等工艺条件要求极为苛刻,使它的应用范围受到了很大限制。目前对刀具的冷却仍是最常用、最有效的方法。从刀具的磨损机理上分析,切削时产生的摩擦高温是造成刀具磨损的主要原因。切削液的主要作用也是通过液体气… 相似文献
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切削温度与刀具磨损、工件加工表面完整性及加工精度密切相关,其变化规律反映出高速切削过程本质的重要方面。本文应用数值模拟,对高速切削加工过程中切屑、工件和刀具三方面的温度随切削速度、进给量、切削深度的动态变化进行了研究,探讨了其变化规律,其结论有助于优化高速切削工艺及建立高速切削数据库。 相似文献
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钛合金因其性能的优越性,在航空、航天、石油、化工、汽车等工业生产领域得到了广泛应用,但在数控加工钛合金过程中,存在切削效率低下,刀具耐磨性差,切屑排屑困难等加工难题。为此,笔者通过反复研 相似文献
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圆弧刃切削的非自由系数及其改善 总被引:12,自引:4,他引:12
建立了含非自由切削干涉参数的圆弧刃切削力公式,定义了非自由切削的非自由系数。通过对圆弧刃、分段圆弧刃、开分屑槽圆弧刃的分析和切削试验,揭示了干涉系数θ的影响及圆弧刃分段多数对降低非自由系数的作用。 相似文献
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航空工业铝合金零件的加工对刀具有很高的要求,刀具在具有高性价比的同时还必须满足高质量加工的需求。南于整体硬质合金刀具具有非常锋利的切削刃和槽型,其在铝合金精加工中切削力小,并且具有容屑空间大.排屑顺畅等优点,因此整体硬质合金刀具逐渐取代了传统的高速钢刀具。 相似文献
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Characteristics of ultrasonic vibration-assisted ductile mode cutting of tungsten carbide 总被引:1,自引:1,他引:0
K. Liu X. P. Li M. Rahman 《The International Journal of Advanced Manufacturing Technology》2008,35(7-8):833-841
In this study, investigations were carried out to evaluate the characteristics of ultrasonic vibration-assisted cutting of
tungsten carbide material using a CNC lathe with CBN tool inserts. The cutting forces were measured using a three-component
dynamometer, and the machined workpiece surfaces and chip formation were examined using a SEM. The experimental results showed
that the radial force F
x
was much larger than the tangential force F
z
and axial force F
y
. The SEM observations on the machined workpiece surfaces and chip formation indicated that the critical condition for ductile
mode cutting of tungsten carbide was mainly the maximum undeformed chip thickness when the tool cutting edge radius was fixed,
that is, the ductile mode cutting can be achieved when the maximum undeformed chip thickness was smaller than a critical value.
Corresponding to the chip formation mode (ductile or brittle), three types of the machined workpiece surfaces were obtained:
fracture free surface, semi-fractured surface and fractured surface. It was also found that the cutting speed has no significant
effect on the ductile chip formation mode. 相似文献
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针对钛合金难加工特点,将液氮作为冷却介质直接喷向切削区进行钛合金TC4低温车削加工,测量其切削力、表面粗糙度和刀具磨损,并与干切削在相同实验条件下对比,分析低温切削对钛合金的影响。实验结果表明:低温切削钛合金,主切削力有所增大,但进给方向力减小,刀具磨损状况与表面质量得到改善,断屑相对容易。 相似文献
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Strain rate in high-speed metal cutting is high, and properties of chip flow under high strain rate conditions are different under low cutting speed conditions. Shear stress and shear strain rate have a linear relationship; hence, the behavior of chip flow during high-speed metal cutting is more similar to fluid than to solid. Therefore, metal cutting should be analyzed by using fluid analytical method. This article investigated the fluid-like properties of chip flow during high-speed metal cutting and determined velocity, pressure, and strain rate distributions on rake face and shear plane. A speed stagnation point is located some distance from the tool tip on the rake face. The location of this point influences the life of the cutting tool and the quality of the finished surface. The pressure peaks, decreases along the rake face, and then reaches zero at some point away from the tool tip. This point represents the separation of the chip from the tool. The total stress on the shear plane is the sum of tensile stress, pressure stress, and shear stress. The strain rate is related to velocity; its value rapidly increases at the tool tip and the free surface corner and then decreases. 相似文献
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A study of the effect of tool cutting edge radius on ductile cutting of silicon wafers 总被引:1,自引:1,他引:1
K. Liu X. P. Li M. Rahman K. S. Neo X. D. Liu 《The International Journal of Advanced Manufacturing Technology》2007,32(7-8):631-637
Ductile mode cutting of silicon wafers can be achieved under certain cutting conditions and tool geometry. An experimental
investigation of the critical undeformed chip thickness in relation to the tool cutting edge radius for the brittle-ductile
transition of chip formation in cutting of silicon wafers is presented in this paper. Experimental tests for cutting of silicon
wafers using diamond tools of different cutting edge radii for a range of undeformed chip thickness are conducted on an ultra-precision
lathe. Both ductile and brittle mode of chip formation processes are observed in the cutting tests. The results indicate that
ductile cutting of silicon can be achieved at certain values of the undeformed chip thickness, which depends on the tool cutting
edge radius. It is found that in cutting of silicon wafers with a certain tool cutting edge radius there is a critical value
of undeformed chip thickness beyond which the chip formation changes from ductile mode to brittle mode. The ductile-brittle
transition of chip formation varies with the tool cutting edge radius. Within the range of cutting conditions in the present
study, it has also been found that the larger the cutting edge radius, the larger the critical undeformed chip thickness for
the ductile-brittle transition in the chip formation. 相似文献