Investigation of MS and Anti-segregation Process HSS Flat Broaching Tools

An investigation has been carried out to compare th e cutting performance and tool life evaluation of high speed steel broach samp les. The comparison has been done between conventional M2 and Anti-Segregation Process (ASP) ASP53 and ASP30 high speed steel broach samples. The ASP53 was a development material. The cutting performance was evaluated by measuring the c utting forces and calculating the specific cutting energy, an indicator of cutti ng performance. As the roughness of the machined surface is an important criter ion in the evaluation of performance of a tool, the surface roughness of the workpiece was studied as a function of undeformed chip thickness. The workpiec e material was 150M36 alloy steel used in manufacture of automobile engines. Th e performance tests were conducted at two cutting speeds, which were 0 7 m/min and 10.5 m/min respectively. This allowed a better understanding of the effect of cutting speed on tool performance. The wear tests were performed at a cuttin g speed on 10.5 m/min. The cutting edges of ASP broach samples were finer compared to that of M2. Ther e was no practical difference in the cutting forces and the specific cutting ene rgy while cutting with MS, ASP30 and ASP53 broach samples. The ASP30 and ASP53 tools have a better surface roughness on the machined surface than that of M2 at both cutting speeds. The ASP30 gave 2.25 times the life and an improved surfac e finish compared to M2 steel. The ASP53 gave 1.3 times the life of M2 steel. These results should prove useful to the tool designer and manufacturing enginee r.

GH4169涡轮盘榫槽电解拉削仿真及其试验研究

榫槽是航空发动机涡轮盘上的重要结构,电解拉削是实现该结构高效、低成本制造的潜在解决方案。为了掌握电解拉削加工参数对轮廓精度和表面质量的影响规律,建立了电解拉削多场耦合模型,阐明了工具阴极长度对加工间隙产物分布的影响规律,获得了优选的工具阴极长度参数。开展了平面电解拉削加工试验,探究了进给速度和加工间隙对工件表面质量和型面进出口去除量差的影响规律,确定了较优的加工参数。试验结果表明,采用优化的加工参数可以获得较好的表面质量并有效控制了型面进出口去除量差。最后,采用优化的参数开展了典型涡轮盘榫槽结构单元件的电解拉削加工试验,试件具有较好的表面质量和轮廓重复精度。

基于AD与TRIZ的加工中心主轴松拉刀机构优化设计

数控加工中心在加工过程中常出现主轴松刀力不足或无法松刀的现象。针对此问题,通过TRIZ系统组件分析明确现有松拉刀机构各组件间作用关系,利用因果链分析得出影响松刀的根本原因,最终应用TRIZ理论中的物场模型分析方法和AD独立性原理提出优化设计方案。根据新方案计算出实际工况下的主轴松刀力和螺杆强度,并对松刀杆进行建模和仿真。结果表明:最大位移量为6.995μm,最大应力为45.24 MPa,符合结构设计要求。最后,经过现场实物测试,当液压力为5 MPa时,松刀行程、松刀力以及打刀量均符合生产要求,验证了优化设计方案的合理性。

Assessment of water-based cutting fluids with green additives in broaching

In order to improve the cutting performance in broaching,the lubrication and cleaning effects offered by water-based cutting fluids with green additives need to be studied from the viewpoint of green manufacturing.Therefore,water-based solutions with castor oil,surfactant(linear alkylbenzene sulfonate,LAS),and nanographite were prepared by ultrasonic agitation and sprayed into the zone of broaching via atomization.The performances of the cutting fluids,in terms of the viscosity,specific heat,wetting angle,and droplet size,were evaluated to discuss their effects on the broaching load.Among the fluids,the addition of LAS into oil-in-water(WO-S),where its cutting fluid with 10 wt.%castor oil and 1.5 wt.%surfactant,exhibited the lowest broaching force.With regard to the lubricating and cleaning mechanisms,WO-S has good wettability and permeability,and hence,can lubricate the cutting edge of the tool to decrease the cutting load,cool the cutting edge to keep it sturdy,and clean the surface of the cutting edge to keep it sharp.The results reveal that the simultaneous addition of castor oil and LAS had remarkable effects on the lubrication and cleaning,and resulted in a broaching load reduction of more than 10%compared to commercial cutting fluids.However,the addition of nanographite could not improve the lubrication owing to its agglomeration.

Correction of Wave Surge Forces to Improve Surf-Riding/Broaching Vulnerability Criterion Check Accuracy

Surf-riding/broaching is one of the five stability failure modes to be included into the International Maritime Organization(IMO) second generation intact stability criteria(which are risk-based stability criteria)that can ensure the safety of ships in actual seaways more effectively. This study focuses on the influence of wave surge force prediction accuracy on surf-riding/broaching vulnerability criterion check result. Firstly, it is demonstrated that the wave surge force prediction method adopted in the current vulnerability criterion check procedure is not accurate and may lead to wrong conclusions. The experimental data from captive model test and the numerical result based on 3D panel method both indicate that the diffraction effect must be considered to correctly predict the wave surge forces. Besides, sophisticated methods are not suitable for Level 2 vulnerability criterion check due to their complexity. Therefore, an empirical formula for wave surge force correction based on sample ship calculation results is proposed. The proposed empirical correction formula can effectively improve the vulnerability criterion check accuracy and thus contribute to the design and safety of the ships which are vulnerable to this stability failure mode.

Penetration and lubrication evaluation of vegetable oil with nanographite particles for broaching process

With increasing environmental concerns,the substitution of mineral oil-based cutting fluid has become an urgent issue.Using vegetable soybean oil as base fluid,nanofluid cutting fluids(NFCFs)were prepared by adding different weight concentrations of nanographite particles(NGPs),and their penetration and lubrication performances were studied.A novel simulated tool-chip slit with micrometersized geometry was manufactured to evaluate and quantify the penetration rate of the NFCFs by image analysis approach.Moreover,a large number of comparative experiments on the closed-type broaching machine were carried out to compare the performance of the proposed NFCFs and a commercial cutting fluid in terms of cutting force,workpiece surface roughness,and metal chip.It is found that there is an optimal NGP concentration in NFCF for practical cutting applications.When the concentration of NGP is 0.4 wt%,the broaching process lubrication exhibits an ideal mixed lubricate state,resulting in minimal friction resistance,and thus,both the cutting force and chip curling angle reach their corresponding best values.Moreover,the proposed NGP-based vegetable-oil cutting fluid exhibits excellent environmentfriendliness and low-cost consumption in the minimal quantity lubrication(MQL)method;this demonstrates its potential for replacing the traditional broaching cutting fluid.

The influence of wave surge force on surf-riding/broaching vulnerability criteria check

This study focuses on the influence of the wave surge force on the assessments of the surf-riding/broaching vulnerability criteria according to the new proposal of the IMO Second Generation Intact Stability Criteria. A code is developed for the criteria check and the sample ship calculations show that the accuracy of the wave surge force estimation has a significant influence on the assessment result. For further investigation, the wave surge force measurement through a captive model test is made for a purse seiner to validate the numerical model, the effects of the wave steepness and the ship forward speed on the wave surge force responses are also discussed. It is demonstrated that the diffraction effect is important for the correct estimation of the wave surge force. Therefore, it is recommended to include this effect in the assessment procedure.

燃机透平轮盘用拉刀的断裂分析

机械零件或加工用工具的尺寸、形状或材料性能都会因某种因素的影响导致失效问题的发生^([1、2]),只有客观地评价可能导致产品生产的全部潜在失效形式,才能成功地设计并生产出能够防止过早出现失效现象的产品。现通过采用现代化的分析技术手段对燃机透平轮盘用拉刀在前期试验验证过程中突然断裂的问题进行了深入分析和探讨,以作为后续提升拉刀制造水平,避免重大产品质量事故的发生提供科学的判断依据。

航空涡轮盘拉削刀具健康监测系统设计

针对航空涡轮盘拉削刀具生产周期长、造价昂贵、监测困难以及易出现损伤等问题,设计并构建了拉削刀具健康监测系统。根据拉床行业的特点、痛点及实际需求等,提出了系统的总体框架。基于加速度传感器及振动监控器,设计了拉床在线、在位的振动信号采集系统,实现了拉削过程中刀具振动信号的连续、实时采集。基于C++语言与Qt开发平台,开发了刀具健康监测系统,实现了对振动信号的实时分析处理及刀具健康监测。

基于稠密卷积网络的拉刀磨损在线预测方法

拉削是汽车制动钳支架槽的重要加工工艺。但加工过程中,若不能及时发现拉刀磨损异常,则会导致零件批量报废。本文提出一种拉刀磨损在线预测方法,采用拉刀信号振动特性,有效区分拉削过程与拉削间隙,并基于稠密卷积网络(DenseNet),构建拉刀磨损在线识别模型。结果表明:该方法自适应特征提取效果良好,泛化性和准确率均可实现实际加工过程拉刀磨损在线预测,对提高拉削生产效率和降低制造成本具有重要意义。

高精度工具磨床电主轴精度超差的原因及解决措施

针对某国产品牌电主轴在实际应用中易出现回转精度超差的问题,分析造成电主轴产生精度超差的主要原因是电主轴的气密封效果不佳,使得前端轴承及碟形弹簧进油受污染,从而导致电主轴前端轴承失效、轴芯磨损和拉刀力衰减过快。通过提升气密封压力值和改善轴芯材质及拉刀机构,解决了电主轴内部进油、轴芯磨损和拉刀力衰减过快的问题,使电主轴使用寿命提升1倍以上。

数控卧式铣镗床高速主轴松拉刀机构优化设计与应用

方滑枕类数控卧式铣镗床因其行程较大,主轴尺寸较长,拉刀机构安装在主轴内部,在松刀及主轴旋转时,拉刀机构会产生较大的变形量,对主轴产生较大的振动。通过静力学分析及振动学理论将现有拉刀机构进行优化,经实际工程应用证明:优化后的拉刀机构主轴整体性能明显改善。

钢筋混凝土卸载深梁加固技术研究

针对某煤矿卸载站卸载深梁的安全性问题,提出了一种混凝土梁体新的加固方法——内削外补法,形成了梁体内削外补的加固技术。针对该种加固技术的特点、施工条件和工期的要求,选择了一种高性能水泥基灌浆料。考虑掺水率和养护龄期等因素,进行了混凝土与灌浆料界面黏结剪切性能试验。以卸载深梁为原型,进行了内削外补加固缩比梁的正截面抗弯性能试验。研究结果表明:采用内削外补法对梁体进行加固可以明显提高梁的承载力。

碳纤维复合功能表面刀具拉削性能实验研究

在拉削加工过程中,切屑会暂时存储在刀具的容屑槽中,划伤工件的已加工表面。传统的微结构刀具由于被动纳屑、效率低下,造成磨屑溢出,会影响拉削性能,为此,通过研究细胞纤毛结构的自清洁特性原理,提出了一种添加碳纤维材料的新型微结构刀具,并对碳纤维复合功能表面刀具的拉削性能进行了实验研究。首先,采用激光加工的方式,在键槽拉刀表面制备倒三角形微结构作为底层微结构,填充硅胶作为结合层,通过碳纤维束仿生纤毛组织与结合层紧密连接,制备了新型微结构刀具;然后,同单一倒三角织构刀具,在干切、水冷、油冷条件下进行了对比切削试验;最后,分别从切屑形态、加工质量、拉削负载等方面对新型微结构刀具的拉削性能进行了分析。研究结果表明:相较于单一倒三角形微结构,新型微结构刀具拉削产生的切屑形态弯曲程度升高了近44.6%,已加工工件表面质量提高了50.7%,拉削负载同理论曲线误差降低了69%;同时发现,新型微结构刀具的切屑形态与表面粗糙度存在98.7%的相关性,这说明,针对新型微结构刀具,凭借切屑形态就能对加工工件表面质量进行准确预测。

铣削工艺参数对镍基粉末高温合金650℃低周疲劳寿命的影响

研究了不同铣削工艺对疲劳损伤的影响规律。对采用4种工艺加工的试样进行了650℃高温空气环境下的低周疲劳试验。分别采用粗糙度表征方法、背向散射电子衍射技术和纳米压痕测试以获得试样的表面粗糙度、残余应力和加工硬化。测试结果表明,采用电火花线切割方法加工的试样疲劳寿命最高(平均80360循环),有最低的表面粗糙度(0.226)和残余应力;而钝刀具加工的试样疲劳寿命最低(平均43978循环),相较于电火花线切割试样的疲劳寿命下降了45%。扫描电镜表征结果表明,疲劳裂纹主要由粗大的非再结晶晶粒和加工缺陷引发。铣削加工方法和参数对疲劳损伤程度和疲劳寿命有重要影响。

燃气轮机轮盘硬质合金可转位拉刀研制与应用

文章针对燃气轮机透平轮盘槽拉削刀具存在的问题开发出1种新的硬质合金可转位拉刀,提高轮盘槽拉削效率。重点对拉削刀具余量分配、容屑系数、齿升量等设计方法进行介绍,并对高温合金材料试块拉削效果进行了试验验证,为燃汽轮机透平轮盘高效加工提供了1套有效办法。

涡轮盘榫槽拉床主溜板结构优化设计与仿真

发动机涡轮盘榫槽的拉削加工中,主溜板的质量和刚度会大幅影响拉床的动态特性、工件的加工质量以及刀具的寿命。以主溜板为研究对象,建立了拉床主溜板切削模型,进行了静力和模态仿真分析,以及基于SIMP法的拓扑优化,提出并对比了两种主溜板结构优化方案,得到了动态特性更好的主溜板结构模型。

Pro/E行为建模技术在拉削式丝锥设计中的应用

行为建模技术主要通过求解目标变量满足设计要求,采用可行域搜索和迭代求解的优化方法,选择更精准的参数控制设计目标,从而得到更加高效和完善的设计。拉削式丝锥属于一种高效螺纹加工刀具,结构紧凑,有多条容屑槽,使得切削平稳排屑流畅,一次拉削就能加工出成型的螺孔。丝锥截面形状对刀具寿命和材料损耗影响最大,在设计中引入行为建模技术,以目标驱动参数作为控制参数得到最优的设计方案。

拉刀刀匣制造工艺研究

通过分析拉刀刀匣的结构和制造工艺性,确定了刀匣的加工工艺路线,提出减小工作台对工件的吸磁作用、改制负角度的砂轮、分段磨削以及U形槽敞口值预修正的方法,解决了拉刀刀匣在加工过程中鼓肚和敞口的问题。通过上述技术手段优化后的刀匣加工精度满足要求,可为类似结构产品的制造方法提供参考。