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1.
非自由切削的流屑角及其分叉   总被引:6,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   

2.
在修磨圆弧铣刀时,可根据圆弧铣刀的使用情况来分析刀具的磨损。一般来说,圆弧铣刀用外圆切削刃切削的情况比较少见,主要集中在圆弧切削刃上,所以刀具磨损严重的部位在圆弧切削刃上。而外圆切削刃可作为圆弧切削刃的后备部分,所以修磨圆弧刃铣刀实际就是修磨圆弧刃的R圆弧切削刃处的前角、后角,使之重新变得锋利,而对外圆部分是不需要进行修磨的。因此在修磨圆弧铣刀时应做好以下几点。  相似文献   

3.
自由切削法与自由切削刀具   总被引:4,自引:0,他引:4  
在深入研究非自由切削的实质和规律性的基础上,揭示实现自由切削的条件,提出自由切削法,其要点是合理刀具的前刀面,以疏导刀刃各部件的排屑,消除排屑干涉,实现自由切削。给出了两种自由切削刀具的原理及其设计方法,分析并实验验证了其优越性。  相似文献   

4.
分析圆弧刃刀具切入过程、切削刃钝圆和进给量对加工质量的影响.对金刚石刀具的刀尖圆弧半径、圆弧切削刃钝圆半径、进给量与表面粗糙度之间的关系进行描述.结果表明:正确地选择刀尖圆弧半径、切削刃钝圆半径和进给量是获得高质量加工表面的有力保证.  相似文献   

5.
《工具技术》2009,(9):26-26
德国瓦尔特(Walter)公司开发的HehcheckProandPlus测量机现在已具备了对刀具的切削刃制备(即切削刃圆弧半径)进行精密测量的功能。刀具的切削刃制备作为延长刀具寿命的一种重要方法,已得到日益广泛的应用,但迄今为止,对切削刃制备的精密形貌进行测量还需要使用昂贵的专用测量仪器。为了解决这一问题,瓦尔特的Helicheck测量机在原有测量功能(包括刀具的几乎所有几何形貌特征,如刀尖圆弧半径、前角、螺旋角、径跳、倒棱宽度等)的基础上,又增加了自动测量切削刃圆弧半径的功能。该测量机利用新增的照相机(放大倍数1000倍)和分路LED(发光二极管)光束(安装在专用的、CNC控制的旋转轴上),能够对最小至5微米的切削刃圆弧半径进行测量。  相似文献   

6.
在圆弧刃刀具切削直线廓形时理论粗糙度计算的基础上,着重研究圆弧刃刀具切削圆弧廓形时理论粗糙度的计算方法。研究表明,工件已加工表面理论粗糙度取决于工件已加工表面的廓形、刀具切削刃形状和刀具切削运动方式,优化选取刀刃半径和刀具进给量后,可以有效地减小理论粗糙度值并提高切削效率。  相似文献   

7.
《工具技术》2015,(8):36-40
在不同切削材料、不同切削参数条件下,为提高扩孔钻的切削性能,其结构需要随之改变。提出由三段相互相切的圆弧构成扩孔钻容屑槽型。根据扩孔钻的切削特点和排屑要求,三段圆弧分别由切削圆弧、卷屑圆弧及容屑圆弧构成;切削圆弧构成的切削刃前角可根据被加工材料与切削参数的不同任意选取,刃瓣宽度根据扩孔钻的外径和强度取值,扩孔钻的芯径依据容屑槽需要的空间大小及扭转强度的要求确定。此结构根据加工材料特性选取所需要的前角、芯径、刃宽等参数,不会改变切削圆弧、卷屑圆弧和容屑圆弧两两相切的槽型设计。与直线切削刃相比,圆弧切削刃轴向力和扭矩低,所提出的结构既可以保证扩孔钻切削刃强度,又有足够的容屑空间,切屑容易卷曲并折断,避免了切屑碰伤已加工表面,且排屑流畅。对改进的扩孔钻结构,应用计算机仿真容易设计出扩孔钻槽铣刀刃形,以方便扩孔钻的设计、检验、制造。  相似文献   

8.
极薄车削中切屑形貌的实验分析   总被引:2,自引:0,他引:2  
赵奕  李旦  董申  周明 《中国机械工程》1999,10(7):721-723
采用圆弧刃金刚石车刀对铝和单晶锗进行超精密车削实验,对切屑在扫描电子显微镜下进行观察,当切削厚度达到纳米级时,得到了和常规切削同样的由剪切滑移的层状薄片堆积形成的连续带状切屑。但是切屑的变形系数远远大于常规切削下的切屑有系数,一般可达20以上。对实验结果的分析说明对单晶锗实现了最小切削厚度为20nm的稳定切削。  相似文献   

9.
铣齿断续切削机理的研究   总被引:2,自引:0,他引:2  
大模数齿轮铣削具有多刃断续切削和变切屑厚度等特点,属于典型的非自由强力切削.主要从切削力、切屑形态、表面质量等方面对铣齿断续切削的机理进行研究.采用指数经验模型,应用微段切削刃受力积分获得单个刀片瞬时合成转矩,随后考虑刀盘上刀片的分布情况,获得刀盘周期性的载荷,提出铣齿断续切削转矩的计算模型.应用间接测量的试验方法,采集三相异步电动机的主轴输入电流,重构得到切削力,另外通过试验测量出切削变形比,应用理论公式获得切削力.将试验数据和理论计算结果与计算模型进行比较,验证了铣齿加工切削转矩模型的正确性.对切削过程中的残余高度进行几何分析,获得其计算方法.初步完成对铣齿断续切削机理的分析,对铣齿加工精度提供指导作用.  相似文献   

10.
目前,现有的食品切断或切片机器都采用切削刃为直线刃或圆弧刃刀片。直线刃刀片切削时,因切削刃的切线垂直于(或接近垂直于)合成速度方向,因此切削性能差,表现为切削抗力大,有冲击,被切物体易变形。圆弧切刃刀片切削时,因刀片旋转,切削刃的切线不垂直合成速度方向。所以切削性能好,但切削效率低。两种刃片在切削时都需要被切削物体与刀片之间有轴向与径向进给运动。这使得以这两种刀片为刀具的机器结构复杂,切削效率低,耗能较多。涡旋弧切削刃刀片排除了直线刃刀片切削性差的缺点,保持了圆弧刃刀片切削性能好的优点,同时在切削时,可以减少径…  相似文献   

11.
A theoretical cutting force model for helical end milling with cutter runout is developed using a predictive machining theory, which predicts cutting forces from the input data of workpiece material properties, tool geometry and cutting conditions. In the model, a helical end milling cutter is discretized into a number of slices along the cutter axis to account for the helix angle effect. The cutting action for a tooth segment in the first slice is modelled as oblique cutting with end cutting edge effect and tool nose radius effect, whereas the cutting actions of other slices are modelled as oblique cutting without end cutting edge effect and tool nose radius effect. The influence of cutter runout on chip load is considered based on the true tooth trajectories. The total cutting force is the sum of the forces at all the cutting slices of the cutter. The model is verified with experimental milling tests.  相似文献   

12.
This article aims at predicting machining performances for oblique turning in relation to tool-nose radius. A new geometric analysis for the uncut chip area is proposed as function of depth of cut, feed rate, tool-nose radius, and edge direction angle. Cutting edge is discretized into increments and average uncut chip thickness, elementary direction angle and elementary depth of cut are determined for each one. A new thermomechanical model is developed for each increment which is supposed to be an oblique machining with single cutting edge. The predicted cutting force components are in good agreement with experimental data over a wide range of cutting conditions. In particular, the effect of tool-nose radius and cutting parameters on chip geometry, cutting temperature, and cutting force components are studied. It is underlined that tool-nose radius promotes the increase in radial force, however, its influence on the other parameters is negligible.  相似文献   

13.
马万太  樊树海  楼佩煌 《中国机械工程》2005,16(24):2171-2175,2202
研究了径向跳动对刀齿的实际切削半径、切屑形状以及切屑厚度的影响机理。研究了各刀齿沿刀刃螺旋线的切削微元实际切削半径的数学表示和变化规律,实际切削半径的变化改变了刀齿的切削路径,使各刀齿上切屑形状分布不均匀。建立了三维切削下切屑厚度的数学表示,提出了递延累加切屑厚度计算算法。实验验证表明,计算的切削力与测量结果能很好地吻合,瞬时切削力、切削力峰值、平均切削力的预测精度达到85%以上。  相似文献   

14.
This paper presents the development of a cutting force model for the micro-end-milling processes under various cutting conditions using a hybrid approach. Firstly, a finite element (FE) model of orthogonal micro-cutting with a round cutting edge is developed for medium-carbon steel. A number of finite element analyses (FEA) are performed at different uncut chip thicknesses and velocities. Based on the FEA results, the cutting force coefficients are extracted through a nonlinear algorithm to establish a relationship with the uncut chip thickness and cutting speed. Then, the cutting force coefficients are integrated into a mechanistic cutting force model, which can predict cutting forces under different cutting conditions. In order to account for the cutting edge effect, an effective rake angle is employed for the determination of the cutting force. A comparison of the prediction and experimental measured cutting forces has shown that the developed method provides accurate results.  相似文献   

15.
倪敬  孙静波  何利华  崔智  薛飞 《中国机械工程》2022,33(22):2733-2740
为了研究PTFE材料在切削过程中的成屑机理,设计了单因素正交切削实验以及准静态力学实验。首先,基于剪切平面理论和断裂理论,以切削速度、切削厚度为变量,提出了PTFE材料的连续切屑及切屑毛边成形机理;然后通过分析毛边高度和间距,探究切削参数对毛边形态的影响规律;最后,利用分形理论对切削力稳定性进行分析,揭示了毛边数量、出现频率与切削力稳定性的关系。结果表明,PTFE连续切屑的产生是因为切削过程中材料真实压缩应变未超过断裂屈服应变,毛边的产生则是因为切屑边缘片层状结构处裂纹的形核与扩展。此外,切削参数会影响毛边生成,在切削速度100 mm/min、切削厚度0.3 mm工况下,切屑毛边数量最少、出现频率最小,切削力最稳定。研究结果可为PTFE材料切削过程毛边抑制和表面加工质量优化提供参考。  相似文献   

16.
Dry machining is being recognized as ecological machining due to its less environmental impact and manufacturing cost. However, the choice of dry machining is mainly influenced by the workpiece material properties, machining operation and cutting conditions. The recent emergence of austempered ductile iron (ADI) can be considered a significant economic advantage to the increasing industrial demand for cost- and weight-efficient materials. However, due to its microstructure-induced inherent properties, ADI is considered hard-to-machine material. Thus, the dry drilling of ADI is investigated in this paper. The ADI material used in the present study is produced using an innovative process route for near net shape casting production. Drilling experiments are conducted on a DMU80P Deckel Maho five-axis machining centre using PVD-coated carbide tools under dry cutting environment. The dry drilling of ADI under different cutting conditions is evaluated in terms of specific cutting force and tool wear analysis. The influence of cutting conditions on chip morphology and surface roughness is also investigated. The experimental results revealed that the combination of the low feed rate and higher cutting speed leads to the higher mechanical and thermal loads on the tool's cutting edge, resulting in higher specific cutting force values. This behaviour is further supported by the chip morphology analysis, which revealed the formation of segmented chips at higher cutting speed with segment spacing increase with an increase in feed rate. Depending upon the cutting parameters, different modes of tool failures including crater wear, flank wear, chipping, breakage and built-up edge were observed. Surface roughness analysis revealed the influence of tool wear and chip morphology on the machined surface finish.  相似文献   

17.
18.
李飞  江铁强  姚斌  郑敏 《工具技术》2013,47(2):13-19
建立了钝圆刃口和倒棱刃口作用下的正交切削力模型,通过该模型反映刃口形状与切削力之间的关系,揭示了切削区工件塑性变形的本质。利用有限元方法研究了硬质合金刀具不同刃口作用下切削力的大小以及切削温度场分布并给出了刀具磨损具体值。此结果为从根本上掌握真实切削特性提供了理论依据并可对刀具刃口形状的设计提供有益的参考。  相似文献   

19.
Due to complex cutting edge profile of an involute cutter, calculations of chip width and consequently cutting force are quite problematical. This article presents a mechanistic approach in the prediction of cutting force components arising in the course of gear tooth cutting by an involute form cutter. To permit calculation of chip width (and so cutting forces), a discrete model is utilized and cutting force components are then derived using Kienzle approach. Moreover, several experiments are performed under different cutting conditions to prove the effectiveness and accuracy of the used method. The results have revealed that cutting force components can be predicted in form gear tooth cutting with a significant accuracy.  相似文献   

20.
基于实验Inconel718正交切削有限元仿真分析   总被引:1,自引:0,他引:1  
为研究犁削效应和前刀面粘压对Inconel718切削过程的影响.基于正交切削实验建立Inconel718有限元切削模型,模型结果同实验值对比以验证模型可靠性.通过改变刀具圆角半径和负前角参数,提取并比较不同的切削力时域曲线和刀具温度,分析犁削效应和前刀面粘压.研究表明犁削效应提高进给力数值,刀具圆角半径由0变为5μm,Inconel718切削进给力均值提高7%:前刀面粘压提高刀具和切屑温度,有利于切屑分离.但刀具负前角为-20°,切削加工不稳定.  相似文献   

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