高速加工技术在变速箱箱体加工中的应用

高速加工系统主要由可满足高速切削的加工中心、高性能的刀具系统和控制系统组成。随着切削刀具技术的进步,高速加工已经得到了广泛的应用。在常规的切削速度范围内,切削温度随着切削速度增大而提高,在一定的速度范围内,切削温度太高,任何刀具都无法承受切削加工不可能再继续下去。但是,当切削速度再增高,切削温度反而降低,切削力也大幅度下降。在高速切削时,切削热的绝大部分被切屑带走,工件基本保持冷态,而切屑温度却要高得多。     

基于量热法与温度补偿技术的镍基合金切削热分配试验研究

设计量热法试验,测量了高速铣削镍基合金时切屑带走的热量,并对热量损失进行了补偿。通过测量切削力,得到主切削力的功率,并计算了不同切削速度下切屑与切削力的功率比。试验表明:随着切削速度的增加,切屑与切削力的热功率比也增加,切屑带走的热量增多;镍基高温合金切削时的切削热分配与碳钢切削时的切削热分配相比,其切屑带走的热量比例要小得多,相应地传入刀具的热量比例会比较高,这就会使得镍基高温合金在切削加工时会产生比较高的切削温度,刀具磨损也要严重的多。     

滚切铸铁齿轮使用冷却液的经验

切削加工中使用冷却液,可以减少刀具与工件间、切屑与刀具间,以及切屑与工件间的摩擦,减少切削时所产生的热量,因此减少了动力的消耗,提高了加工光洁度。另外,冷却液还会带走一部分热量,使工件与刀具的温度更加降低。由于温度的降低以及摩擦的减少,因而增加了刀具的寿命,同时可以提高切削速度以提高生产率。使用冷却液的这些优点,对于加工铸铁     

碳钢铣削热研究

本文基于量热计法研究碳钢铣削热在切屑、工件、刀具及环境中的量化分配,并通过测量切削力和设定的切削速度得到主切削力的功率,将算出的总热量与主切削力做的功相比较来评判量热法测量切削热的精确程度.     

弧网式过滤机在集中过滤中的应用

在金属切削过程中,为提高切削效率,提高工件的精度和降低工件表面粗糙度,延长刀具使用寿命,达到最佳的经济效果,就必须减少刀具与工件、刀具与切屑之间的摩擦,及时带走切削区内因材料变形而产生的热量.     

高速铣削中切削力的研究

在高速铣削试验的基础上，研究高速切削时切削速度对切削力的影响。结果表明，在切削速度较低的情况下，切削力随切削转速的增加而增大，但达到某一临界速度后，随着切削速度继续增大，剪切角增大，造成切向切削分力下降。不同刀具材料与工件材料的匹配在不同切削条件下有不同的临界切削速度。     

喷雾冷却在旋风铣螺纹中的应用

金属切削中,切屑的变形、刀具与切屑及刀具与工件之间的摩擦等会产生大量的切削热,从而引起工件的热变形,影响加工精度和刀具寿命。有时为了保证工件的加工精度和一定的刀具寿命,不得不采取降低切削速度、减小切削用量的方法,但降低了生产效率。要使刀具有一定的寿命和保证工件的加工精度并有较高的生产效率,最有效的途径就是采取有效的冷却方法使产生的热量迅速散发出去。     

高速切削钢材时的切削力试验研究

本文在高速车削的试验基础上，研究高速车削时切削速度对切削力的影响，结果表明，在切削速度较低情况下，切削力随切削速度的增加而增大，但达到某一临界速度后，随着切削速度继续增大，切削力下降，不同刀具材料与工件材料的匹配在不同切削条件下有不同的临界速度。     

高速铣削高强度钢切屑形态及影响因素研究

采用硬质合金涂层刀具高速铣削AF1410高强度钢,基于单因素试验法研究了切削参数对切屑形态和毛边形态的影响,分析了切屑锯齿间距、毛边几何参数随切削速度和进给量的变化规律.结果 表明:切削速度较低时,切屑自由表面形成上窄下宽、上深下浅的剪切滑移变形带,带内剪切变形较小,切削速度增加,绝热剪切变形增大,切屑自由表面形成平行的锯齿形态,锯齿间距随切削速度的提高而增大;在高速切削条件下,锯齿间距随进给量的提高而略有增大,切屑由顶部沿锯齿节间沟槽发生纵向撕裂形成毛边,毛边宽度和高度随切削速度先增大后减小,随进给量减小.     

弧网式过滤机在集中过滤中的应用

在金属切削过程中，为提高切削效率，提高工件的精度和降低工件表面粗糙度，延长刀具使用寿命，达到最佳的经济效果，就必须减少刀具与工件、刀具与切屑之间的摩擦，及时带走切削区内因材料变形而产生的热量。要达到这些目的，采用性能优良的切（磨）削液往往可以明显提高切削效率，降低工件表面粗糙度，延长刀具使用寿命，取得良好的经济效益。切削液作用有如下四个方面：冷却、润滑、清洗和防锈。     

H13淬硬模具钢精车过程的数值模拟

采用热力学耦合有限元方法研究了淬硬钢精车过程中切屑形成规律。运用H13 淬硬模具钢流动应力模型进行数值模拟,考查了H13淬硬模具钢精车过程中工艺参数对工件性能和刀具的影响。结果表明:切削速度愈高,进给量愈小,刀具刀尖半径愈大,则工件加工层上的静水拉应力愈小,表面质量愈好; 淬硬钢精车时径向力起主要作用,大于切削力;切削速度愈大,切削力和径向力则愈小,愈有助于改善工件加工层上的表面质量;切削速度、进给量和刀具刀尖圆角半径愈大,工件和刀具温度愈高,愈易导致刀具前刀面扩散磨损和刀具后刀面磨损。研究结论有助于优化H13淬硬模具钢精车过程中工艺参数选择和改进刀具镶片设计。     

基于ABAQUS的齿圈车削数值模拟研究

齿圈为传动系统中典型高精度弱刚度,本文针对该典型零件建立了三维有限元模型。工件采用了弹塑性材料模型,而刀具采用刚性材料模型,利用商业化软件ABAQUS,对所建立的模型进行了有限元分析,得到了齿圈车削时切屑的形成过程、切削热的分布以及切削力变化规律,将部分结果与理论规律做了比较,发现他们是吻合的。     

Cutting heat dissipation in high-speed machining of carbon steel based on the calorimetric method

The cutting heat dissipation in chips, workpiece, tool and surroundings during the high-speed machining of carbon steel is quantitatively investigated based on the calorimetric method. Water is used as the medium to absorb the cutting heat; a self-designed container suitable for the high-speed lathe is used to collect the chips, and two other containers are adopted to absorb the cutting heat dissipated in the workpiece and tool, respectively. The temperature variations of the water, chips, workpiece, tool and surroundings during the closed high-speed machining are then measured. Thus, the cutting heat dissipated in each component of the cutting system, total cutting heat and heat flux are calculated. Moreover, the power resulting from the main cutting force is obtained according to the measured cutting force and predetermined cutting speed. The accuracy of cutting heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting from the main cutting force. __________ Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(11): 1–4 [译自: 华南理工大学学报(自然科学版)]     

高速切削淬硬模具钢表面粗糙度的研究

通过正交设计方案,对淬硬到60HRC的冷作模具钢Cr12MoV进行高速车削表面粗糙度试验,分析了切削用量和刀具变量对表面粗糙度的影响规律,并建立了表面粗糙度的经验公式。表面粗糙度随着切削速度的增大而减小,随着进给量和背吃刀量的增大而增大,随着刀尖圆弧半径的增大,表面粗糙度先减小后增大。在相同条件下,陶瓷刀具加工后的工件表面粗糙度好于PCBN刀具;由表面粗糙度的经验公式可知,对表面粗糙度影响最大的因素是切削速度,其次是进给量和背吃刀量,而刀尖圆弧半径对其影响较小。     

Experimental investigation of machining characteristics and chatter stability for Hastelloy-X with ultrasonic and hot turning

Ultrasonic-assisted machining is a machining operation based on the intermittent cutting of material which is obtained through vibrations generated by an ultrasonic system. This method utilizes low-amplitude vibrations with high frequency to prevent continuous contact between a cutting tool and a workpiece. Hot machining is another method for machining materials which are difficult to cut. The basic principle of this method is that the surface of the workpiece is heated to a specific temperature below the recrystallization temperature of the material. This heating operation can be applied before or during the machining process. Both of these operations improve machining operations in terms of workpiece-cutting tool characteristics. In this study, a novel hybrid machining method called hot ultrasonic-assisted turning (HUAT) is proposed for the machinability of Hastelloy-X material. This new technique combines ultrasonic-assisted turning (UAT) and hot turning methods to take advantage of both machining methods in terms of machining characteristics, such as surface roughness, stable cutting depths, and cutting tool temperature. In order to observe the effect of the HUAT method, Hastelloy-X alloy was selected as the workpiece. Experiments on conventional turning (CT), UAT, and HUAT operations were carried out for Hastelloy-X alloy, changing the cutting speed and cutting tool overhang lengths. Chip morphology was also observed. In addition, modal and sound tests were performed to investigate the modal and stability characteristics of the machining. The analysis of variance (ANOVA) method was performed to find the effect of the cutting speed, tool overhang length, and machining techniques (CT, UAT, HUAT) on surface roughness, stable cutting depths, and cutting tool temperature. The results show both ultrasonic vibration and heat improve the machining of Hastelloy-X. A decrease in surface roughness and an increase in stable cutting depths were observed, and higher cutting tool temperatures were obtained in UAT and HUAT compared to CT. According to the ANOVA results, tool overhang length, cutting speed, and machining techniques were effective parameters for surface roughness and stable cutting depths at a 1% significance level (p ≤ 0.01). In addition, cutting speed and machining techniques have an influence on cutting tool temperature at a 1% significance level (p ≤ 0.01). During chip analysis, serrated chips were observed in UAT and HUAT.     

Cutting heat dissipation in high-speed machining of carbon steel based on the calorimetric method

The cutting heat dissipation in chips, workpiece, tool and surroundings during the high-speed machining of carbon steel is quantitatively investigated based on the calorimetric method. Water is used as the medium to absorb the cutting heat; a self-designed container suitable for the high-speed lathe is used to collect the chips, and two other containers are adopted to absorb the cutting heat dissipated in the workpiece and tool, respectively. The temperature variations of the water, chips, workpiece, tool and surroundings during the closed high-speed machining are then measured. Thus, the cutting heat dissipated in each component of the cutting system, total cutting heat and heat flux are calculated. Moreover, the power resulting from the main cutting force is obtained according to the measured cutting force and predetermined cutting speed. The accuracy of cutting heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting from the main cutting force.     

基于DEFORM 3D的钛合金高速车削有限元仿真

应用DEFORM 3D软件对钛合金高速车削进行仿真研究,分析了不同切削参数下切削力和切削温度的规律,研究发现背吃刀量和进给量对主切削力的影响较大,切削力与主切削力变化基本一致,切削速度对主切削力的影响不明显,但后者对切削温度具有显著影响;研究了工件和刀具温度场的变化规律以及工件所受应力和刀具的磨损情况,发现最高温度出现在切削刃邻近2mm区域内,且温度最高处刀具磨损程度最大,工件最大应力在第一变形区和工件接触区邻近。     

成形铣齿加工过程中的切削热模型

为了获得铣齿切削时切削区域的温升分布,在分别对铣削热产生和传出的机理,以及刀具和工件之间几何关系分析的基础上,得出包含对应虚拟镜像热源的热源模型。考虑到剪切面热源和刀屑接触面摩擦热源对工件、切屑和刀具的温升作用效果的不同,根据傅里叶导热定律推导出顶刃切削时相应热源的温升计算公式,分别对3者的温升分布进行计算可以获得整个切削区域的温升分布。结果表明,铣削过程中温度随切削的深入而升高,在不改变工件和刀具材料的情况下,进给速度是影响切削温度的主要因素,改变刀盘转速对温升的影响不大。     

高速硬态切削工件表层显微硬度与白层研究

高速和硬态切削使得工件已加工表面及其表层中出现特有的现象.研究结果表明,切削速度和材料硬度是决定高速和硬态切削工件已加工表面及其表层结构形成的主要影响因素,切削热使被切削材料产生高温软化,刀具挤压摩擦使被切削材料变形加剧,工件表层材料显微硬度分布发生改变,出现了硬脆的白层组织,白层组织的出现将对零件的使用将造成不利影响.随着切削用量和材料硬度增大,切削变形增大,切削温度升高,白层厚度增大,工件表层材料显微硬度提高.抑制白层组织产生的措施是对工件降温.