基于灰色系统理论的球头铣刀螺旋铣孔切削参数优化

螺旋铣孔工艺技术是适用于典型难加工材料的制孔工艺技术。本文基于球头铣刀钛合金螺旋铣孔试验,测量了三向切削力,分析了切削参数对径向力和轴向力的影响,以减小径向切削力、轴向力切削力和提高切削效率为优化目标。利用灰色系统理论计算了灰色关联系数、灰色关联度和平均灰色关联度,得出了试验范围内多目标优化的最优切削参数组合。     

基于ABAQUS的钛合金螺旋铣孔仿真及试验验证

为了提高螺旋铣孔的制孔质量,需要预测加工过程中的切削力大小规律。通过ABAUQS/Explicit求解器模块对螺旋铣孔进行试验验证,分析并建立了钛合金螺旋铣孔仿真中的一系列模型,提出综合位移分离法和能量分离法来定义材料的分离属性。针对螺旋铣孔的特殊运动路径,运用连接器与边界载荷条件协同模拟实现。通过仿真模拟得出螺旋铣孔加工中切削力的变化规律,同时分析了最大应力应变的属性和分布特点。     

基于斜角切削理论的钛合金螺旋铣孔切削力建模

通过分析螺旋铣孔的加工原理和计算加工过程中的运动向量,结合侧刃和底刃对切削力的影响,建立了螺旋铣孔过程的切削力解析模型。提出了基于斜角切削的切削力系数辨识方法,并根据斜角切削过程几何关系推导出摩擦角、剪切角、剪切应力的约束方程。开展切削力系数辨识试验和钛合金螺旋铣孔试验对仿真值进行验证,结果表明,切削力的仿真值与试验值误差较小,平均误差为9.55%,从而验证了斜角切削系数辨识方法的有效性和切削力模型的正确性。     

钛合金螺旋铣孔与传统钻孔的加工质量对比

对钛合金进行了螺旋铣孔与传统钻孔试验,研究了两种孔的加工质量及影响因素。结果表明:钛合金螺旋铣孔的质量相对较高,表面粗糙度相对较小;对于螺旋铣孔工艺,轴向每转进给量是影响孔表面粗糙度的主要因素,切向每齿进给量是影响孔圆度的主要因素,螺旋铣孔参数对孔径的影响不大;对于传统钻孔工艺,轴向每转进给量是影响孔表面粗糙度、圆度和孔径的主要因素。     

CFRP/Ti叠层材料螺旋铣孔与钻孔的刀具磨损对比与分析

针对螺旋铣孔与传统钻孔刀具磨损的问题,对CFRP/Ti叠层材料进行螺旋铣孔与传统钻孔试验。在相同加工效率及切削速度的基础上,对两种工艺加工孔的切削力及刀具后刀面磨损长度进行了测量。结果表明:制孔过程中,螺旋铣削制孔的切削力明显小于钻削制孔的切削力;加工过程中,螺旋铣削制孔的切削力比钻削制孔的切削力更加平缓;同等参数条件下,螺旋铣削加工到24孔时刀具失效,传统钻削加工到18孔时刀具失效;螺旋铣削制孔的刀具比钻削制孔的刀具更加耐磨,加工孔数更多。     

CFRP单向板超声振动辅助螺旋铣孔孔壁的质量试验

通过普通螺旋铣及超声振动辅助螺旋铣(Ultrasonic vibration helical milling,UVHM)加工CFRP单向板的单因素对比试验,分析了孔0°、45°、90°、135°处的纤维破坏形式及孔壁形貌不同的原因及切削力周期性变化及FX的幅值大于FY的幅值的原因,其中135.处的孔壁处受加工参数影响较大,且质量最差,基于此着重研究了 135.处孔壁质量随加工参数的变化规律.结果表明,与普通螺旋铣相比UVHM的切削力大幅降低,降幅达50％,且UVHM加工孔的孔壁质量更优;孔壁质量随着加工参数的变化均有一定的变化规律.     

CFRP单向板超声振动辅助螺旋铣孔孔壁的质量试验

通过普通螺旋铣及超声振动辅助螺旋铣(Ultrasonic vibration helical milling,UVHM)加工CFRP单向板的单因素对比试验,分析了孔0°、45°、90°、135°处的纤维破坏形式及孔壁形貌不同的原因及切削力周期性变化及FX的幅值大于FY的幅值的原因,其中135.处的孔壁处受加工参数影响较大,且质量最差,基于此着重研究了 135.处孔壁质量随加工参数的变化规律.结果表明,与普通螺旋铣相比UVHM的切削力大幅降低,降幅达50％,且UVHM加工孔的孔壁质量更优;孔壁质量随着加工参数的变化均有一定的变化规律.     

钛合金插铣加工切削力试验及工艺参数优化

钛合金整体叶盘结构复杂,制造难度大。应用插铣技术加工整体叶盘能够有效解决上述问题,插铣工艺参数的优化对发挥插铣加工优势具有重要作用。通过插铣钛合金试验研究,探讨工艺参数对切削力的影响规律;根据试验数据建立切削力预测模型,并对模型进行检验;最后以切削力与金属去除率为目标,基于MATLAB进行工艺参数优化,可为钛合金整体叶盘高效切削提供理论参考及技术支持。     

CFRP及叠层结构螺旋铣孔专用刀具切削性能评价

碳纤维增强复合材料(CFRP)及由钛合金Ti-6Al-4V和CFRP组成的金属复合材料叠层结构广泛应用于现代航空工业。大型客机结构件之间主要通过铆接和高锁螺栓连接,根据波音与空客公司发布的数据显示,最新一代B787与A380上装配孔的数量已超百万,装配过程中的制孔效率与质量直接决定了客机整体装配效率及关键结构件的疲劳寿命,从而间接影响了客机的生产成本以及飞行可靠性。随着飞机数字化装配的快速发展,传统的钻孔工艺会产生很多加工缺陷,工序复杂,加工孔质量不能满足要求,因此,有必要优化制孔工艺,设计新型专用刀具。本文通过研究螺旋铣孔运动学特性,分析螺旋铣孔的工艺特点,设计了一种新型螺旋铣孔专用刀具,并以加工过程的轴向切削力、出入口加工质量以及刀具磨损为评价指标,验证该新型专用刀具的切削性能。结果表明,专用刀具在干切削条件下能够实现复材孔无分层、钛合金孔无毛刺加工,大幅提高刀具寿命,解决了传统立铣刀对CFRP及CFRP/钛合金叠层结构进行螺旋铣孔时刀具寿命低、加工质量差等问题。     

螺旋铣孔技术的原理及其应用

螺旋铣孔技术相对于传统钻孔技术具有很大的优势,在航空制造业中得到了应用。本文在对比了传统钻孔与螺旋铣孔特点的基础上,分析了螺旋铣孔的切削过程与切屑形成机理,并在钛合金的孔加工中得到验证。试验结果表明,螺旋铣孔加工钛合金时,切向力与法向力随着每齿轴向进给量的增加而增大,随着每齿切向进给量的增加而减小;由于不同的切屑流向而形成2种不同的切屑,并与切屑形成的机理相吻合。     

飞机壁板柔性装配螺旋铣孔单元的研制

针对现代飞机壁板高效精密制孔的需求,研制一种面向大型航空组件柔性装配的新型螺旋铣孔单元。首先,通过对国内外现有机身自动制孔系统的技术分析,并结合壁板装配制孔的作业特点,引入一种新兴的制孔技术——螺旋铣孔。其次,对螺旋铣孔运动进行功能分解,展开了螺旋铣孔单元的模块化设计,确定了偏心调节模块的传动方案,设计了铣刀结构与装夹方式。最后,基于螺旋铣孔单元样机,对航空铝合金和碳纤维复合材料进行了切削试验,结果表明铣孔质量基本满足飞机装配的精度要求。     

HOLE MAKING USING BALL HELICAL MILLING ON TITANIUM ALLOYS

In this article, results of helical ball milling for hole making on Ti-6Al-4V alloy are presented and compared with drilling. Two different machining strategies were tested with a ball end mill. In the first strategy only a helical milling path was used to achieve the nominal diameter. The second strategy has two stages; first, helical milling considering a diameter 50 µm below the nominal, and second, the tool flank of the ball end mill were used to remove the stock left with a single contouring operation. Experimental tests were performed taking into account the process time, final quality of holes, hole diameter, roughness and burr formation at tool entrance and exit. With helical milling two advantages were concluded: the process is versatile because one tool is suitable for a range of diameters and negligible burrs are produced. However hardness in the zones close to hole internal surfaces machined with the ball end mill tool decreases with respect to twist drilling. The information obtained from this research work defines suitable cutting parameters for the helical milling process in the titanium alloy Ti-6Al-4V with ball end mills.     

Surface topography and roughness in hole-making by helical milling

Helical milling is used to generate holes with a cutting tool traveling on a helical path into the workpiece in which the diameter of the hole can be adjusted through that of the helical path. Based on an improved Z-map model, a 3D surface topography simulation model is established to simulate the surface finish profile generated after a helical milling operation using a cylindrical end mill. The surface topography simulation model incorporates the effects of the relative motion between the cutting tool and the workpiece, in which the effect of the insert runout error of the cutting tool is considered. Furthermore, the roughness parameters are deduced from simulations of the 3D surface topography. The experimental result shows that the proposed simulation algorithm can predict well the surface roughness in a helical milling operation. The surface topography simulation model is used to study the effects of cutting conditions such as the tangential feedrate, the diameter of the cutting tool and the hole, the insert runout error of the cutting tool, as well as the revolution of the cutting tool around the axis of the hole on the surface finish profile. It is found that the surface quality can be improved by optimization of the cutting conditions. As a result, the proposed model will be helpful in determining the cutting conditions to meet surface finish requirements in helical milling operation.     

Prediction of cutting forces in helical milling process

The prediction of cutting forces is important for the planning and optimization of machining process in order to reduce machining damage. Helical milling is a kind of hole-machining technique with a milling tool feeding on a helical path into the workpiece, and thus, both the periphery cutting edges and the bottom cutting edges all participated in the machining process. In order to investigate the characteristics of discontinuous milling resulting in the time varying undeformed chip thickness and cutting forces direction, this paper establishes a novel analytic cutting force model of the helical milling based on the helical milling principle. Dynamic cutting forces are measured and analyzed under different cutting parameters for the titanium alloy (Ti–6Al–4V). Cutting force coefficients are identified and discussed based on the experimental test. Analytical model prediction is compared with experiment testing. It is noted that the analytical results are in good agreement with the experimental data; thus, the established cutting force model can be utilized as an effective tool to predict the change of cutting forces in helical milling process under different cutting conditions.     

2250轧机传动轴头高精度圆弧面的高效精加工

某公司重点产品2250轧机传动轴轴头材质特殊,加工长度长,且圆弧面上有孔,使加工时刀具处于断续切削状态,传统的镗削工艺方案加工困难。通过改进工艺方案,采用先进的数控螺旋插补铣削再镗的工艺使产品加工效率和质量均得到提高。     

CFRP/TC4叠层材料低频振动钻削试验研究

低频振动辅助切削技术是基于传统切削给刀具加上有规律并可控的振动,从而达到减小切削力、提高加工精度和延长刀具寿命的目的。将低频振动辅助切削技术应用到CFRP/钛合金叠层材料制孔中,在孔径、孔壁粗糙度和入口质量等制孔质量方面与传统钻削进行对比试验研究。结果表明,振动钻削在制孔质量上具有明显的优势。     

Delamination analysis of the helical milling of carbon fiber-reinforced plastics by using the artificial neural network model

As carbon fiber-reinforced plastics are widely used in aeronautical and aerospace industries, the improvement of their processing quality is a crucial task. In recent years, helical milling, a brand new machining process that results in better hole quality with one-time machining, has been attracting increasing attention. Based on full factor experimental design, helical milling experiments were performed by using a special cutter. Using the data obtained from the experiments, the correlation between the delamination and the process parameters was established by developing an artificial neural network (ANN) model. MATLAB ANN Toolbox was used for modeling. The effects of the process parameters on delamination at the exit of the machined holes were analyzed by using this model and the predicted results. The significance of the process parameters in the improvement of the hole quality in helical milling was also assessed.     

钛合金高速旋转超声椭圆振动侧铣削切屑特征和刀具磨损研究

难加工材料钛合金在采用传统铣削方式时,随着切削速度的增加,切削力和切削温度都迅速增加,使得切削条件恶化并加速刀具磨损,从而导致刀具过早失效。将超声椭圆振动加工技术引入到高速铣削中,进行了钛合金高速旋转超声椭圆振动侧铣削试验。从切屑特征以及刀具后刀面磨损两个方面研究了高速超声椭圆振动铣削参数匹配对钛合金加工的影响。首先基于高速超声椭圆振动铣削过程中刀具-工件的运动学特点推导出高速超声椭圆振动铣削加工参数与振动参数间的匹配关系,然后利用本实验室自行研制的超声椭圆振动铣削装置进行了不同参数匹配关系下的验证性切削试验。试验结果表明：合理的参数匹配使得超声椭圆振动铣削在高速条件下依然能够实现分离型断续切削加工。相比普通铣削加工,分离型的高速超声椭圆振动铣削能够获得更加微细的切屑,切削热能够被及时地带走;良好的切削条件使得刀具的后刀面磨损均匀而缓慢,从而延长刀具的使用寿命;高速超声椭圆振动铣削能够有效地提高生产效率。