不锈钢微钻削的切屑形成与仿真分析

切屑问题是不锈钢材料微钻削加工的主要难点之一。不锈钢微钻削生成的切屑易缠绕在微钻上,断屑和排屑非常困难。通过实验观察了0Cr18Ni9不锈钢微钻削过程中产生的切屑形态,考察了切削速度和进给速度对切屑形态的影响规律;借助有限元软件对切屑的形成过程进行了仿真分析和理论分析。     

超声振动钻削切屑形成机理及实验研究

针对难加工材料钻孔不易断屑、加工难度高等问题,采用超声振动技术进行加工.对振动钻削的切屑形成机理进行分析,建立了切削刃的运动轨迹方程,推导出了不同相位差下的切削刃运动轨迹和切屑厚度方程,研究了切削厚度变化情况和断屑特性,得到了振动钻削中的完全几何断屑的条件.最后,通过201不锈钢钻削实验,对得出的切屑进行对比分析,验证了断屑条件,进而实现了对难加工材料钻孔切屑的有效控制.     

高强度材料车削机械断屑器设计分析

针对304奥氏体不锈钢为代表的典型高强度、车削加工难断屑材料,设计了一种具有主动机械动力的切屑二次折断装置.断屑装置由直流电机提供动力,在切屑流向断屑器时,通过旋转的内断屑刀和固定的外断屑刀共同作用折断切屑.实验和仿真对比,分析了304奥氏体不锈钢在不同切削用量下使用该断屑器辅助车削和干切削时切屑形态,以及在各切削用量下使用断屑器辅助车削的优化效果,并得出断屑器取得良好断屑效果及最大程度降低前刀面温度的优化切削参数.验证了其在不同切削用量下均能够稳定可靠地断屑,避免了切屑缠绕问题,降低了刀具车削时前刀面的温度并提高了生产效率.     

常用钻型枪钻加工不锈钢的切削性能试验

针对枪钻加工不锈钢深孔时容易出现切屑黏刀、缠刀、不易排出等问题。提出从钻型角度分析不同枪钻钻型加工不锈钢的切削性能特性,通过使用标准型枪钻、双外刃枪钻、带断屑槽的单外刃枪钻进行不锈钢钻削试验,解决不锈钢加工中存在的问题,同时对这三种钻型在加工不锈钢时的切削性能进行对比和总结。获得适合加工不锈钢的较优钻型,并为生产实践中加工不锈钢枪钻钻型选择提供参考。     

错齿BTA深孔钻削切屑变形断裂影响因素研究

利用错齿BTA深孔钻削切屑弯曲变形规律,对导致错齿BTA内排屑深孔钻切屑断裂的影响因素进行了分析,通过试验研究了错齿BTA深孔钻削切屑的变形断裂随刀齿钻削半径、钻削工艺参数、断屑台尺寸的变化规律。研究结果表明,刀齿钻削半径对切屑厚度影响很大,随钻削半径的增大,各刀齿切屑厚度增大,切屑厚度最大值点均位于刀齿切屑大径边缘且中心齿、中间齿、外齿的切屑厚度最大值依次减小;与转速相比,进给量对切屑厚度和切屑应变增量的影响更大,随进给量增大,切屑厚度增大,切屑应变增量增大;随断屑台宽度减小、高度增大,切屑应变增量增大,断屑条件改善。     

振动工作台切削性能与工艺效果研究

加工硬铝材料的振动钻削试验表明,振动钻削断屑效果良好,在完全几何断屑的加工条件下,断屑是稳定的;在不完全几何断屑加工条件下,也有明显的断屑效果。研究结果表明,此时的切屑变形系数较常规钻削增加,切屑在从钻头和孔壁之间排除时,更容易折断,同时,可以在较宽的加工参数范围内获得断屑效果。切削力的测试结果也表明了在振动切削状态,振动导致切削力的峰值增加。     

FBT断屑钻头

<正> 断屑钻顾名思义是切屑短,即不出长屑的钻头(简称CB钻头)。这种钻头是英国Firth Brown公司的专利产品,结构简单,断屑槽型是沿着钻沟全长铣制而成,对钻头切削刃性能、寿命无不良影响,重磨也与普通钻头一样。钻削时,切屑顺着钻沟流动,接触到断屑槽时,切屑就卷曲或被断成碎片。切屑变成碎片或卷曲后,可防止其堵塞,使切屑流动通畅。碎片切屑极易从孔中排出,尤其在水平钻孔时更为有效。切属不堵塞于钻沟内,可避免加工过程停顿,便于连续钻孔。同时,切屑短,冷却液易流出,可带走大量切削热,这对钻尖极为有利,可提高钻孔效率。从图中的截面形状可知,断屑槽型增加了横截面面积,     

错齿BTA深孔钻削切屑变形及刀屑接触长度分布规律研究

断排屑问题一直是错齿BTA内排屑深孔钻削的难点,通过建立切屑流经断屑台的几何变形模型分析了刀屑接触长度对错齿BTA钻削切屑的变形断裂的影响,采用有限元分析软件DEFORM-3D建立了错齿BTA钻头钻削仿真模型,对各刀齿切屑的形成及变形规律进行了分析,研究了刀屑接触长度随刀齿钻削半径分布规律及其随钻削条件的变化规律,并利用实验对仿真结果进行了验证分析。结果表明,仿真结果可信,刀齿钻削半径对切屑的变形及刀屑接触长度影响很大,刀屑接触长度随钻削进给量增大而增大,随转速增大而减小,随工件材料强度增大而增大。     

深孔加工振动断屑装置设计

针对深孔加工过程中切屑形态不稳定所形成的排屑不畅问题,基于振动钻削理论,设计振动断屑装置,有效控制切削形态,保证顺利排屑。通过给刀具施加轴向周期振动,振动断屑装置可实现变切厚钻削和钻头轴向振动,使切屑易断,并在一定程度上提高了表面加工质量。通过实验探究了切屑形态与切削参数的关系,分析了振动断屑装置的最佳工作参数。     

机械式轴向深孔振动钻削系统的设计

深孔的钻削加工过程中,经常生成带状切屑,堵塞在孔内,对加工质量产生影响,特别是经常发生卡钻或断钻事故。如在钻削过程中,对切屑进行周期性断屑,并与负压抽屑装置配合使用,解决了深孔加工过程中断屑排屑困难的问题。设计一种机械式深孔振动钻削装置,对深孔进行振动钻削,可通过改变电机的转速调整其钻削频率,改变滑块的位置可调整振幅,显著特点是结构简单,振幅与频率调整方便,提高深孔的加工质量。     

45钢深孔枪钻切削试验与切屑形态分析

切屑形态对枪钻深孔加工中孔成型精度影响极大,钻尖切屑易堵塞在V型排屑槽中或缠绕在钻头上,合理的断屑和排屑是保证加工顺利进行的前提。选用硬质合金枪钻对45钢进行深孔加工试验,采用单因素试验法研究切削速度和进给量对切屑形态的影响规律。试验表明:切削速度较低时,主要为带状切屑;切削速度较高时,主要为单元切屑;当切削速度保持不变时,随着进给量的增大,切屑的主要形状从长带状向单元切屑逐渐转变;当进给量保持不变时,随着切削速度的增大,切屑尺寸从大变小再变大。     

小直径深孔振动钻削钻头的研究

分析了小直径深孔振动钻削对钻头的要求；设计了一种新型内排屑深孔钻头；分析了该钻头的结构和刃磨特点，进行了振动钻削试验。试验表明，合理匹配切削参数和振动参数，可实现断屑可靠且排屑顺畅，能钻出尺寸精度高、表面粗糙度参数值小、直线度较高的深孔。分析了用新型钻头进行振动钻削提高工艺效果的原因，表明该种钻头具有良好的工艺性能。     

硬质合金麻花钻钻削不锈钢Q345深孔的试验研究

整体硬质合金钻头在加工塑性材料时断屑、排屑比较困难。分析实际加工条件和被加工材料的特征后,替换了原来使用的进口"皇冠"钻头。本文介绍替换的试验过程、结果,经试验验证超过了客户期望的寿命。     

Novel micro-deep-hole drill with variable web thickness and flute width

This study proposes a novel micro-deep-hole drill with variable web thickness and flute width to effectively improve the problem of tool breakage and chip clogging during micro-deep-hole drilling. Firstly, the failure form and failure mechanism of micro-drill are explored by performing drilling experiments, and it is found that the torsion fracture and bending fracture are the main premature failure modes of micro-deep-hole drilling tools. The static simulation analysis of micro-drill is further conducted to investigate the influence of geometric parameters on the stiffness and strength of high-aspect-ratio micro-drill, and the results indicate that the web thickness ratio and flute width have significant effects on drill tip stiffness and spiral groove root strength. To balance the rigidity, strength and chip evacuation capability of micro-deep-hole drilling tools, the new micro-drill with variable web thickness and flute width is developed, supplemented by comparative experiments. The results confirm that the new micro-drill has better chip removal ability, greatly reduces the drilling force, torque, drill tip wear and material peeling phenomenon, and significantly enhances the machining quality of hole wall.     

Dry and minimum quantity lubrication high-throughput drilling of compacted graphite iron

This research studies the sustainable and high-throughput drilling of compacted graphite iron (CGI), a high strength, lightweight material for automotive powertrain applications. CGI drilling experiments were conducted using a 4 mm diameter coated carbide drill at 26.5 mm/s feed rate. In two repeated tests under three lubrication conditions: dry, dry with through-the-drill compressed air, and through-the-drill minimum quantity lubrication (MQL), the drills were able to produce a maximum of 1,740, 3,150 and 2,948 holes, respectively, before the breakage of the drill. The Joule–Thomson effect due to the expansion of high pressure air from through-the-drill holes at the drill tip, chip shape, chip size and chip speed are investigated. Flank wear of the drill cutting edge is measured and results are correlated to drill life. Results indicate that dry machining of CGI is technically feasible. Chip evacuation and advanced tool cooling are important factors that affect drill life for high-throughput sustainable dry drilling of CGI.     

提高加工不锈钢微钻寿命的试验研究

微钻由于直径很小所以在加工过程中常常遇到排屑不顺利、磨损严重、崩刃、甚至断刀等问题,严重的影响了刀具的使用寿命。在加工不锈钢时情况更严重。本试验通过对微钻钻尖的几何参数优化,显著改善了微钻的钻削情况,从而提高了微钻的使用寿命。本文介绍微钻钻尖的几何参数优化、实验过程、结果,以及对不锈钢钻削机理的初步认识。     

Experimental analyses to investigate the feasibility and effectiveness in using heat pipe-embedded drills

This paper presents an experimental investigation to verify the feasibility and effectiveness of heat pipe cooling in drilling operations. The basic idea is to insert a heat pipe at the center of the drill tool with the evaporator close to the drill tip and the condenser at the end of the drill. Consequently, the heat generated at the tool–chip interface can be removed by convection heat transfer. Experimental studies were involved in three cases, including solid drill without coolant, solid drill with coolant, and heat pipe drill. Drilling tests were conducted on a CNC machining center with full immersion cutting. The cast iron square block was used as the workpiece, and the high-speed steel was chosen for the drill tool material. Flank wear is considered as the criterion for tool failure, and the wear was measured using a Hisomet II Toolmaker’s microscope. The tests were conducted until the drill was rejected when an average flank wear greater than 0.10?mm was recorded. The results demonstrate that using a heat pipe in the drilling process can effectively perform thermal management comparable to the flooding coolant cooling used pervasively in the manufacturing industry, extending the tool life of the drill.     

硬地层单牙轮-PDC钻扩联合钻头破岩特性

提出了新型单牙轮-PDC钻扩联合钻头,先依靠单牙轮破岩钻孔,释放地应力,产生岩石损伤,再助推PDC钻头刮切破岩。运用有限元法,建立钻扩联合钻头、双级PDC和常规PDC钻头破岩的非线性动力学模型。通过对岩石本构关系进行D-P准则描述以及确定岩石破碎的判据,分析钻扩联合钻头钻进硬地层的破岩机理,开展了3种钻头动态破岩过程的对比研究。结果表明：钻扩联合钻头在钻进过程中井底井壁的岩石应力得到明显释放,大大提高了岩层可钻性;在硬地层中钻扩联合钻头钻进速度提高的主要原因是拉应力破岩;钻扩联合钻头在硬地层钻进过程中的扭转振动大大降低,破岩效率更高,钻头寿命更长;由于单牙轮领眼破碎岩石的作用,钻扩联合钻头对井底岩石的冲击破碎能力更强,在硬地层中钻进更快。研究结果为新型单牙轮-PDC钻扩联合钻头的研发提供了参考。     

Model-based operating recommendations for high-speed spindles equipped with a self-vibratory drilling head

The drilling of deep holes requires the chips to be evacuated using retreat cycles and lubrication, which is problematic for both productivity and the environment. An alternative response to the chip evacuation problem is the use of a vibratory drilling head, which enables the chip to be split thanks to the axial self-excited drill, and hence it can easily be evacuated from the hole. The vibratory drilling head is composed of a specific tool holder with adjustable axial stiffness. In this paper, a dynamic high-speed spindle/drilling head/tool system model is elaborated on the basis of rotor dynamics predictions. The dynamic properties of interfaces between system components are identified by the receptance coupling method and integrated into the model. The model is validated by comparing the numerical FRF with experimental results. Then adequate self-vibratory cutting conditions are established by integrating the model-based tool tip FRF into the chatter approach of Budak-Altintas. Spindle rolling bearing lifespan is also investigated in order to guarantee a rational use of the spindle-tool set with respect to industrial lifespan.