基于拟合车削的内螺旋滚道成型方法研究

针对滚珠丝杆副的关键结构内螺旋滚道难加工、加工成本高等问题,提出了一种拟合车削的新型加工工艺,并构建了一个经济型的内螺旋滚道加工系统.通过拟合车削算法生成拟合车削点,圆弧形车刀以拟合车削点为基点进行层层拟合车削,从而完成内螺旋滚道的加工.经加工试验,该系统的加工精度为0.001mm,经该系统加工的内螺旋滚道的表面粗糙度可达Ra0.8,证明该加工工艺的可行性并具有较大的应用价值.     

玻璃磨削中电镀金刚石工具的磨损

以镍钴合金为结合剂制备了电镀金刚石工具,对平板玻璃进行了磨边实验,用扫描电子显微镜观察电镀金刚石工具的磨损状态。在玻璃加工过程中,金刚石工具的磨损分为金刚石磨损和结合剂磨损两种情况。金刚石的磨损形式包括：破碎,磨平以及脱落。结合剂的磨损为：在金刚石颗粒的前方形成较深的凹坑,两侧形成较浅的凹坑,金刚石磨粒的后面则形成结合剂的隆起。随着磨削过程的进行,工具的结合剂逐渐被磨除,玻璃磨屑的颜色也相应的由白色向黑色变化。研究结果表明,制备电镀金刚石工具时,电镀结合剂与金刚石磨粒磨损应保持同步,充分发挥金刚石工具的切削作用。     

基于Fluent两种螺旋槽密封微间隙三维流场分析

应用UG三维建模软件建立两种不同形式的螺旋槽密封结构,用Gambit软件对其进行网格划分,并利用流体动力学求解工具Fluent对两种形式螺旋槽密封的微间隙三维流场进行了模拟仿真。研究表明：两种形式的螺旋槽均可以产生明显的动压效应;在一定转速范围内端面总压随着转速升高而增强;开于密封端面间的螺旋泵送槽相比于同类开于外径处的螺旋槽流体动压效应更为明显,形成的流体润滑膜更为稳定。     

Study on swarf when sawing granite with diamond wire

The diamond wire-sawing process was developed to cut granite in both quarries and block processing plants. In this paper, swarf was collected from different areas along the sawing arc when sawing three granites. The particle size distribution and the morphology of the swarf were investigated systematically, along with the swarf formation mechanism in sawing. Granite swarf formation was dominated by transgranular fractures based on the morphology of sawn granite chips and the analysis of sawn chip size. A long cutting arc increased the movement among the swarf, tool, and workpiece, thereby inducing a secondary fracture in the sawn chip.      

螺旋槽铣削加工过程中油气冷却技术的应用研究

为了降低螺旋槽铣削加工过程中切削温度,分析油气冷却技术的作用机制,通过传统浇注式冷却与油气冷却的对比试验表明:在螺旋槽铣削加工中应用油气冷却技术,对降低切削温度、延长刀具寿命、提高螺杆表面加工质量、降低加工成本等具有重要意义。     

Performance evaluation of a new screw conveyor for metal swarf

The unconventional screw conveyor tested allows all kinds of metal swarf, which can vary widely between fine particles (dust in dry condition or sludge when wet) and long spiral or helical ribbons, to be transported satisfactorily.Tests were carried out to investigate the influence of assorted metal swarf types on screw performance when the device works in steady, near clogging, dry or wet conditions.The equipment efficiency parameter was characterized.Investigations were executed to check capacity, efficiency, torque and axial force connection versus screw rotation speed.     

上游泵送螺旋槽机械密封优化设计

不同尺寸密封环结构参数选取也不一样。通过Fluent软件仿真出压力分布,探讨3个主要参数的选取趋势。为了进一步提高螺旋槽上游泵送的密封性能,对螺旋槽的结构进行优化,保持坝区和堰区不变, 仅改变螺旋槽底部形状及螺旋槽形态,将等深螺旋槽变成收敛型渐深槽。对比分析等深槽、不等深槽的密封性能,结果表明：收敛型锥度不等深槽密封性能最佳。在此基础上,研究结构参数对收敛型渐深槽密封性能的影响     

基于BP神经网络与遗传算法的固结磨具制作工艺参数优化

目的 利用BP神经网络技术与遗传算法寻找固结磨具制作最优工艺参数组合,实现固结磨具制作工艺参数的快速寻优.方法 设计磨粒粒径、磨粒质量分数、成型压力、烧结温度的正交工艺参数表,按正交表工艺参数制作蓝宝石晶片加工用的Cr2O3固结磨具,并且设计不同固化温度下制作的固结磨具的硬度与抗压强度测试试验,验证自制的固结磨具加工的...     

不锈钢磨屑的微观结构及分离工艺的研究

为了从不锈钢磨屑中分离不锈钢金属,在磁选分离的基础上,分别采用水和碱的饱和溶液对磨屑进行了浸洗,分析了磨屑的微观结构,探索了不锈钢磨屑的电炉熔炼工艺。结果表明,磨屑中除含有主相Ni-Cr-Fe和Fe-Ni固溶体之外,还含有一定量SiC、Al2O3等物相。在磨屑中不锈钢金属呈细长的丝带状,部分金属丝与块状的砂轮磨粒缠绕在一起,造成磁选分离效果不佳。采用碱的饱和水溶液浸洗可有效地去除磨屑中的油污和灰尘。在电炉熔炼条件下,由于砂轮磨粒含量高,烧结态磨粒阻止了液化金属的聚集长大,导致电炉熔炼分离效果不理想,甚至难以正常进行。     

An NC rough turning method of an enveloping toroidal worm

Due to the inefficiency of the grinding method, the enveloping toroidal worm is usually pre-processed using the turning method of the hindley worm. The difference between the turning and the grinding method leads to the great and inhomogeneous allowance during the subsequent grinding process of the enveloping worm. A new rough turning method was presented based on discretization of the spiral surfaces of the worm. The spiral surface was cut by the tool tips of a turning tool along the discrete points calculated from the mathematical model. The grinding allowance was equalized and the grinding time decreased significantly. The spiral groove of the worm was cut layer by layer in the tangential and radial directions of the rotation of the turning tool tip. The distance between the rotation axis of the tool and that of the worm was changed gradually so that the entire height of the tooth could be cut. A series of rotating angles of the worm and the turning tool were determined for programming an NC turning machine tool. The generation process of a plane enveloping toroidal worm was simulated in an numerically controlled simulation system. The grinding allowance was obtained and analysed. Trial manufacturing was performed and the results showed that the grinding allowance could be equalized and the manufacturing efficiency could be increased.     

Development of a High-Porosity Fixed-Abrasive Pad Utilizing Catalytic Effects of TiO2 on Polyurethane Matrix

A new method of manufacturing a high-porosity fixed-abrasive pad for grinding aluminum disks has been developed. In this development, it was discovered that the addition of ultrafine TiO₂ powders into polyurethane during the polymerization process can induce foaming of the polyurethane itself, which results in the highly porous structure of the grinding pad. The utilization of this effect for manufacturing fixed-abrasive pads make a porosity above 50% possible. The developed high-porosity pad provides not only load-free grinding, but also a wide selection of abrasive grains and a much finer surface roughness of 19.3 nm Rz compared with the polyvinyl alcohol (PVA) stone that is generally used for grinding aluminum hard disk drive (HDD) substrates.     

孕镶金刚石钻头破碎花岗岩岩屑粒径分布研究

收集微钻实验过程中孕镶金刚石钻头破碎花岗岩所产生的岩屑,分析其粒径分布,定量研究金刚石参数、钻进参数对岩屑粒径分布的影响。结果表明:岩屑粒径在一定范围内呈单峰值分布,粒径尺寸集中分布在40～100 μm,粒径分布基本符合对数正态分布规律;金刚石粒度、浓度,钻压和转速对岩屑的粒径分布有较大的影响。      

Solid-state recycling of aluminium alloy swarf through cold profile extrusion and cold rolling

In this study, the possibility of solid-state recycling of aluminium alloy machining swarf using cold extrusion and a subsequent cold rolling process is investigated. Cast Al-Si alloy swarf was cold compacted into billets and successfully profile-extruded into square bars with a rectangular cross-sectional aspect ratio of 1:1.8 under an extrusion ratio of 4 or more. After annealing, the extruded bars underwent multi-pass cold rolling into 1-mm thick strips with a total rolling reduction of 85%. Optical microscopy demonstrated that in material recycled using only an extrusion process, coarse residual voids existed in regions where insufficient plastic strain was introduced, causing a visible expansion of the material during heat treatment. However, uniaxial tensile tests showed that extrusion-recycled material had a higher mechanical strength than the original aluminium alloy, implying sufficient bonding among the individual pieces of machining swarf. It was also found that the strength and density of material recycled through extrusion and an additional rolling process were superior to material recycled using extrusion only. Moreover, it was observed that the ductility of the recycled materials was inferior to that of the original aluminium alloy.     

Spiral-structured fixed-abrasive pads for glass finishing

Loose-abrasive machining with cerium oxide (ceria) slurry is traditionally employed for finishing glass. However, the use of slurries can have a detrimental impact on the environment. Fixed-abrasive machining has received attention as an alternative technology; however, conventional fixed-abrasive tools are inefficient. In this study, spiral-structured pads with fixed-abrasive layers and abrasive holding layers are introduced to increase the quality and efficiency of fixed-abrasive tools. The finishing experiments revealed a much higher finishing efficiency and good surface quality compared to those obtained in conventional polishing with ceria slurry.     

金刚石绳锯切割花岗石过程中岩屑粒度分布研究

对三种不同花岗石绳锯切割过程中不同弧区位置的岩屑进行了采集,并对其粒度进行了分析。实验结果表明:三种花岗石岩屑粒度分布曲线均大致为单峰分布,符合罗辛-拉姆勒分布规律,大部分岩屑颗粒尺寸集中在20~100μm之间,花岗石岩屑的粒度分布不仅与加工弧区的长度有关,还受到花岗石的原始粒径的影响。     

游离和固结金刚石磨料抛光手机面板玻璃的试验研究

选取不同粒径的金刚石微粉,采用游离磨料和固结磨料两种抛光方法加工手机面板玻璃,比较其材料去除率和抛光后工件表面粗糙度。结果表明：在相同的抛光工艺参数下,磨粒粒径在游离磨料抛光中对材料去除率和抛光后表面质量作用显著,而在固结磨料抛光中作用不显著;采用金刚石固结磨料抛光垫抛光能获得表面粗糙度约为Ra1.5 nm的良好表面质量,并在抛光过程中较好地实现了自修整功能。     

Innovations in Abrasive Products for Precision Grinding

This paper is a review of recent developments in the design and manufacture of precision, fixed-abrasive tools. The role of each component within the “engineered composite” is also discussed, with examples showing how the components have been enhanced to achieve their current high levels of performance. The paper also looks at examples where innovations in the abrasive tool have enabled the development of innovative abrasive processes. A vision of future abrasive product developments is also presented by the authors.     

管材螺旋槽成形模具设计

采用冲压模具实现了管材螺旋槽成形.根据曲轴毛坯的特殊形状和成形工艺,在其螺旋槽成形模具设计中,使用浮动定位机构实现了曲轴毛坯在模具中的定位,依靠斜楔斜滑块机构完成螺旋槽成形,采用汽缸辅助斜楔斜滑块机构实现了成形凹模在模具中的定位与复位,并给出了螺旋槽工作尺寸的计算.该模具在生产中取得了良好的效果.     

斜齿轮注射模设计

通过分析斜齿轮结构特点,常规脱模比较困难,采用螺旋顶杆顶塑料齿轮,依靠螺旋顶杆按螺旋槽轨迹转动,顶着塑料齿轮朝着螺旋槽轨迹同步转动和前进,齿轮顺利从模具内脱模。经过生产实践,模具结构设计合理,使用可靠。     

复合地层中不同刃形滚刀与岩石接触行为研究

目的 滚刀截面形状即刃形对滚刀综合性能影响显著,研究不同刃形的滚刀在复合地层中的载荷变化特点,把握各型滚刀应用于复合地层时的优势与劣势,对于减少滚刀失效、降低刀盘偏载具有重要指导意义。方法 通过滚刀破岩试验获取和对比3种刃形的滚刀(平顶、圆顶和螺旋槽滚刀)在软硬复合地层中的切削力、破岩体积等关键指标,同时建立滚刀破岩有限元数值模型,探究滚刀刃形影响其切削岩石性能的机理和规律。结果 在复合地层中工作时,平顶滚刀所需的法向力均值最高,其余滚刀则相近。这是由于圆顶和螺旋槽滚刀破岩时仅有部分表面参与接触,接触面积均小于平顶滚刀,应力集中效应明显,从而降低破岩法向力。螺旋槽滚刀在切削不同强度岩石时的法向力差距最小;圆顶滚刀的法向力标准差的值最小。3种滚刀均形成了粉末状和片状岩石碎片,平顶和圆顶滚刀形成的岩石碎片总体积相近而螺旋槽滚刀略低。结论 复合地层软硬岩强度相差较大时,可选用螺旋槽滚刀以减轻刀盘偏载;硬岩部分强度较高时,推荐选用圆顶滚刀,以减小切削力和载荷冲击。