钢管电火花刻槽机的设计

为满足设备小型化、便于携带的要求,设计了钢管电火花刻槽机。该刻槽机采用单片机芯片控制脉冲电源,处理键盘输入和故障报警,并控制步进电动机实现自动进给和分离的可调流量的冲油装置。该设备适用于钢管的现场刻槽。     

钢管电火花刻槽机的设计

为满足设备小型化、便于携带的要求,设计了钢管电火花刻槽机.该刻槽机采用单片机芯片控制脉冲电源,处理键盘输入和故障报警,并实现步进电机的自动进给和冲油装置的流量调节控制.该设备适用于钢管的现场刻槽.     

电火花加工可调节工作液槽的设计

针对传统电火花加工中工作液槽存在的问题，设计了电火花加工可调节工作液槽，实现了电火花加工中工作液槽的可调节和工作液的可过滤循环。通过设置液槽伸展层，可以根据工件的大小上下推动液槽伸展层，使液槽伸展层在加工液槽主体内伸缩，以调节整个工作液槽的大小，保证加工时工件能够完全浸入工作液槽，保障最终的加工效果。通过设置抽吸循环管，可以打开循环水泵抽吸，基于循环过滤件内的过滤网实现过滤，降低工作液内杂质含量，提高工件加工表面质量。所设计的电火花加工可调节工作液槽结构简单，操作方便，有利于提高工件加工表面质量和经济效益，应用效果良好。     

扭杆弧形槽精密微细电火花加工工艺研究

针对扭杆弧形槽的加工要求,分析了机械误差对加工精度的影响,设计了合理的装夹方案,降低了机械误差对制造精度的影响;通过正交试验法分析了电加工参数对弧形槽表面粗糙度的影响,采用最优加工参数,可得到Ra=0.1μm的弧形槽表面;研制了扭杆电火花加工刚度在位测量装置,该装置能解决扭杆加工中既要满足面形精度又要满足加工刚度的要求。     

混气与混粉电火花加工机理的分析

分别介绍了混粉电火花加工和混气电火花加工的特点，以及关于混粉和混气电火花加工的机理解释，对这两种加工方法的机理进行了分析比较，从而得出两种加工方法侧重点不同的结论，即同普通电火花加工相比，混粉电火花加工易于降低表面粗糙度，而混气电火花加工速度相对较快。     

基于神经网络的电火花加工工艺效果预测模型

针对电火花加工的工艺特点及其复杂性,提出了一个基于神经网络的电火花加工工艺效果的预测模型,可映射出电参数和加工结果之间的关系。计算机仿真结果显示了其良好的预测精度,最后分析了引起预测误差的原因。     

微细电火花线切割加工误差分析

微细电火花线切割加工过程中,加工时施加的张力、火花放电引起的放电力、材料蚀除过程中的爆炸力以及放电通道中的瞬时压力等共同作用使电极丝产生偏移,从而引起加工误差,影响加工精度。为了减小加工误差,从材料力学的角度分析了丝的变形大小以及来源,得出减小误差的方法。此外从几何角度分析拐角切割的形位误差,提出通过精确控制导向器的轨迹来满足加工精度要求的方法,为自适应控制提供了理论依据。     

基于电火花脉冲电源电参数的预测模型

针对电火花加工的工艺特点及其复杂性，提出了一个基于神经网络的电火花加工工艺效果的预测模型，可反映出电参数和加工结果之间的关系。Matlab仿真结果显示了其良好的预测精度，最后分析了引起预测误差的原因。     

微细电火花成形加工设备关键技术研究

基于微细电火花加工的要求,对微细电火花成形加工设备中的关键技术进行研究,成功研制了一套高精度的微细放电加工设备产品,包括一台微细电火花加工机床和一台精密脉冲电源。优化机床关键零/部件的结构后,机床的变形小,运动精度高;电源放电稳定,控制精确。经加工试验表明,该设备加工效果较好,加工精度和稳定性较高,加工出的窄槽工件的尺寸精度可达到5μm,加工直径为300μm的小孔,其圆度误差达到3μm,可满足微细电火花加工的要求。     

浅析电火花线切割加工和电火花成型加工的特点

本文通过电火花线切割加工和电火花成型加工的三要素,电火花加工和铣削加工的比较,电火花线切割加工和电火花成型加工的共同特点和不同特点的阐述,从不同角度分析了两种不同的电火花加工方法的特点,对实际加工方法的选择和应用起到了指导作用。     

Design of precision angular indexing system for calibration of rotary tables

The indexing table was developed for angle measurements on machine tools. The measuring techniques, which have been reviewed in this paper, are currently available in manufacturing engineering to calibrate the angle measurement. The measuring principles of each equipment are outlined and their capabilities are also discussed. The new indexing table using 6 points kinematic concept and employing ball and vee grooves location was designed and manufactured to calibrate angle errors of rotary tables using a laser interferometer. The manufacturing method was evaluated to manufacture the accurate vee grooves. A special cam was designed and manufactured to translate rotation movement into lift-up and rotation movement. A CNC machining centre and indexing head were used to manufacture the cam. All parts of the new indexing table were manufactured with a manufacturing tolerance according to drawings, squareness and parallelism checked to obey the 6 points kinematic concept. Also these factors controlled the repeatability of the new indexing table. After installing the new indexing table, the performance was evaluated using rotary table operating in both the horizontal and vertical orientations.     

紫外平面刻划光栅杂散光数值分析及测试

杂散光是光栅的重要技术指标,它直接影响光栅的信噪比,紫外波段的杂散光对光谱分析尤为不利.为了考察平面刻划光栅用于光谱仪器时产生的杂散光,采用标量衍射理论数值分析了杂散光产生的原因.数值模拟结果表明,紫外平面刻划光栅刻槽周期随机误差以及刻槽深度随机误差是杂散光的主要来源,而光栅杂散光对光栅表面小尺度随机粗糙度并不敏感.提出了平面光栅光谱仪出射狭缝相对宽度的概念,数值分析了仪器出射狭缝高度及出射狭缝相对宽度与杂散光强度的关系,从而分别为在光栅制作工艺中从根源上降低光栅杂散光以及在光栅应用过程中从使用方法上降低光栅杂散光提供了理论依据.最后,为了与采用滤光片法测得的光栅杂散光实验值进行比较,给出了理论求解杂散光总强度的求和公式,并对4个不同波长的杂散光进行了多次测量.结果表明,当刻槽周期随机误差、刻槽深度随机误差和表面随机粗糙度分别取0.8 nm、 0.5 nm和1.2 nm时,理论值和实验值的相对误差可控制在13%左右.     

Flow dynamics of a spiral-groove dry-gas seal

The dry-gas seal has been widely used in different industries.With increased spin speed of the rotator shaft,turbulence occurs in the gas film between the stator and rotor seal faces.For the micro-scale flow in the gas film and grooves,turbulence can change the pressure distribution of the gas film.Hence,the seal performance is influenced.However,turbulence effects and methods for their evaluation are not considered in the existing industrial designs of dry-gas seal.The present paper numerically obtains the turbulent flow fields of a spiral-groove dry-gas seal to analyze turbulence effects on seal performance.The direct numerical simulation(DNS) and Reynolds-averaged Navier-Stokes(RANS) methods are utilized to predict the velocity field properties in the grooves and gas film.The key performance parameter,open force,is obtained by integrating the pressure distribution,and the obtained result is in good agreement with the experimental data of other researchers.Very large velocity gradients are found in the sealing gas film because of the geometrical effects of the grooves.Considering turbulence effects,the calculation results show that both the gas film pressure and open force decrease.The RANS method underestimates the performance,compared with the DNS.The solution of the conventional Reynolds lubrication equation without turbulence effects suffers from significant calculation errors and a small application scope.The present study helps elucidate the physical mechanism of the hydrodynamic effects of grooves for improving and optimizing the industrial design or seal face pattern of a dry-gas seal.     

紫外平面刻划光栅杂散光数值分析及测量方法

杂散光是光栅的重要技术指标,它直接影响光栅的信噪比,尤其紫外波段的杂散光对光谱分析更为不利。为了考察平面刻划光栅在光谱仪器中使用时产生的杂散光,采用基于传统Fresnel-Kirchhoff衍射方程导出的杂散光相对强度表达式,数值分析了杂散光产生的原因。数值模拟结果表明,紫外平面刻划光栅刻槽周期随机误差以及刻槽深度随机误差是杂散光的主要来源,而光栅杂散光对光栅表面小尺度随机粗糙度并不敏感。另外,提出了平面光栅光谱仪出射狭缝相对宽度的概念,并数值分析了仪器出射狭缝高度及出射狭缝相对宽度与杂散光强度的关系。此理论分析方法分别为如何在光栅制作工艺中从根源上降低光栅杂散光以及在光栅应用过程中从使用方法上降低光栅杂散光提供了理论参考依据。最后,为了与采用滤光片法测得的光栅杂散光实验值进行比较,给出了理论求解杂散光总强度的求和公式,并对四个不同波长的杂散光进行了多次测量,使理论值和实验值的相对误差控制在13%左右。     

铣削凸轮轴半圆键槽夹具设计

笔者设计的夹具是用于在卧式铣床上对于凸轮轴铣半圆键槽的专用夹具,主要由夹具体、定位元件（V型块）、夹紧元件（压板）、夹紧机构（斜楔联动夹紧）等组成。在设计中,分析了零件图、夹具的结构特点、夹具工作原理,计算了定位误差、夹紧力,从而保证了该专用夹具能够用于加工该工件的可靠性、高效性。     

Research on the technology for outer race elliptical groove grinding with basin-like grinding wheel

A new grinding method that outer race elliptic track in ball basket constant velocity joint is ground by means of basin-like grinding wheel is proposed herein. Aiming at the grinding process with basin-like grinding wheel, the paper establishes the mathematical model, optimizes the parameters by using restrictive random direction method, studies the processing principle in detail, and analyzes the machining errors. The simulation results indicate that the theoretical error of elliptical groove ground by basin-like wheel will be reduced to the level of 0.001 mm. Then, the grinding experiments of elliptical grooves with the basin-like grinding wheel were completed, and the measurements of the grooves by portable arm coordinate measuring machine were carried out, which validates the feasibility of this grinding technology.     

A Study on the Mechanism of Generating Wear Track Grooves

The mechanism of generating wear track grooves on metallic materials was investigated to elucidate the cause of similar wear track appearance based on pin-on-disk wear test results. As previously shown, most wear tracks on metallic materials appear similar in appearance irrespective of test conditions and materials. This phenomenon is attributed to the similar scales of prominent grooves in wear tracks, as wear tracks have common characteristic groove sizes in terms of width and depth. The ploughing by transfer particles adhering to counter surface initially generates these grooves, which become larger along with the growth of transfer particles. Pin-on-disk wear tests revealed that transfer particles adhering to the pin surface stopped growing at a certain size upon being enclosed by ridges forming along the sides of grooves on the disk and penetrating the pin surface. This final transfer particle size determines the characteristic scales of wear track grooves. We supposed that this enclosure by ridges terminated particle growth. Based on this supposition, the formation of ridges had a key effect on determining the sizes of grooves. Ridges form when the grooves grow to a certain size; thus, characteristic grooves could be expected to be a bit larger than this size. Therefore, these processes generate the characteristic scales of wear track grooves which lead to similar wear track appearance.     

Investigation of boiling heat transfer characteristics of two-phase closed thermosyphons with various internal grooves

The boiling heat transfer characteristics of two-phase closed thermosyphons with internal grooves are studied experimentally and a simple mathematical model is developed to predict the performance of such thermosyphons. The study focuses on the boiling heat transfer characteristics of a two-phase closed thermosyphons with copper tubes having 50, 60, 70, 80, 90 internal grooves. A two-phase closed thermosyphon with plain copper tube having the same inner and outer diameter as those of grooved tube is also tested for comparison. Methanol is used as working fluid. The effects of the number of grooves, the operating temperature, the heat flux are investigated experimentally. From these experimental results, a simple mathematical model is developed. In the present model, boiling of liquid pool in the evaporator is considered for the heat transfer mechanism of the thermosyphon. And also the effects of the number of grooves, the operating temperature, the heat flux are brought into consideration. A good agreement between the boiling heat transfer coefficient of the thermosyphon estimated from experimental results and the predictions from the present mathematical model is obtained. The experimental results show that the number of grooves and the amount of the working fluid are very important factors for the operation of thermosyphons. The two-phase closed thermosyphon with copper tubes having 60 internal grooves shows the best boiling heat transfer performance.     

复杂槽形槽筒数控加工编程技术

使用通用CAD/CAM软件难以直接解决空间复杂槽形零件的数控加工编程问题,必须采用针对性很强的数控编程方法才能达到目的。以8头纺丝槽筒零件为例,分析了空间复杂槽形零件的结构特点,制定了相应的数控加工方法,提出了针对性很强的基于CAD环境的数控加工编程技术,成功解决了此类零件数控加工与编程问题。     

Theoretical and experimental studies on boiling heat transfer for the Thermosyphons with various helical grooves

Boiling heat transfer characteristics of a two-phase closed thermosyphons with various helical grooves are studied experimentally and a mathematical correlation is developed to predict the performance of such thermosyphons. The study focuses on the boiling heat transfer characteristics of two-phase closed thermosyphons with copper tubes having 50, 60, 70, 80, 90 internal helical grooves. A two-phase closed thermosyphon with plain copper tube having the same inner and outer diameter as those of grooved tubes is also tested for comparison. Water, methanol and ethanol are used as working fluid. The effects of the number of grooves, various working fluids, operating temperature and heat flux are investigated experimentally. From these experimental results, a mathematical model is developed. In the present model, boiling of liquid pool in the evaporator is considered for the heat transfer mechanism of the thermosyphons. And also the effects of the number of grooves, the various working fluids, the operating temperature and the heat flux are brought into consideration. A good agreement between the boiling heat transfer coefficient of the thermosyphon estimated from experimental results and the predictions from the present mathematical correlation is obtained. The experimental results show that the number of grooves, the amount of the working fluid and the various working fluids are very important factors for the operation of thermosyphons. Also, the thermosyphons with internal helical grooves can be used to achieve some inexpensive and compact heat exchangers in low temperature.