技术文摘专栏

【摘要】：按照行星螺杆挤出机的结构特征建立几何模型,在等温流场假设条件下,采用仿真模拟方法模拟了行星螺杆挤出机内物料的流动模式。为了表征行星螺杆挤出机的塑化混炼能力,     

基于残高控制的异形截面螺杆螺旋槽的精加工刀路规划

异形截面变螺距螺杆作为功能件应用广泛。在分析异形截面变螺距螺杆的结构特征与技术要求的基础上,设计了四轴数控铣削加工该螺杆的方案,并采用流线曲面驱动,规划了螺旋槽的精加工刀路;构建了残余高度与刀具直径、切削行距之间的几何关系。检测结果表明:该加工方案加工过程稳定,加工出的螺杆精度可达到技术要求。     

螺杆转子的数字化测量和数据处理技术

分析了螺杆转子数字化测量的技术,通过研究螺杆转子的结构特征和三坐标测量时的误差产生原因,采用路径逐步优化的测量方法。同时提出了测量数据处理方法,使三坐标测量更加精确,并通过测量实例验证了该方法的有效性。     

单螺杆挤出机并联式稳压装置的模拟计算

研制了单螺杆并联式稳压装置,建立了高聚物为等温幂律流体稳压装置的数学模型,用MathCAD软件对该模型进行了数值模拟。给定主螺杆末端的压力波动,计算了稳压螺杆对压力波动的调节能力,分析了影响稳压螺杆稳压效果的各种因素。结果表明:若固定稳压螺杆转速,通过自动调节稳压螺杆中高聚物熔体的存留长度,可补偿主螺杆压力和产率波动的97.6％;若调节稳压螺杆的转速,则可完全补偿主螺杆压力和产率的波动。     

螺杆压缩机噪声控制措施的研究

对螺杆压缩机进行了变工况条件下全面的性能试验,研究了螺杆压缩机的性能特征,分析了螺杆压缩机性能的主要声源.为解决螺杆压缩机噪声高的难题,对压缩机的隔声罩设计进行了改进.吸声材料进行了优化选择,加强了螺杆压缩机排气噪声控制.     

螺杆空压机变频节能改造的经济分析和技术方案

比较了普通螺杆空压机和变频螺杆空压机的运行状况和特点,分析了螺杆空压机变频节能改造的技术要点和可获得的经济效益,同时提出了螺杆空压机变频节能改造的技术方案。     

新型交叉轴双螺杆膨胀机转子的设计与受力性能研究

针对现有双螺杆膨胀机螺杆转子在工作过程中承受的轴向力较大的问题,提出采用交叉轴锥形螺杆转子结构,减小螺杆转子轴向力;建立了交叉轴锥形螺杆转子三维模型;使用双螺杆膨胀机的工作过程模型,确定了工作情况下螺杆转子所受的温度和压力载荷;使用ANSYS软件对螺杆转子在温度和压力作用下的变形和轴向力进行了分析。结果显示,交叉轴锥形螺杆结构对减小双螺杆膨胀机转子轴向力有较好的效果。     

变螺距螺杆的通用机床加工

介绍了变螺距螺杆在通用机床上的加工原理,解决了通用机床无法加工变螺距螺杆的问题,大大降低了变螺距螺杆的加工成本,为变螺距螺杆的设计和应用铺平了道路。     

采煤机长螺杆断裂原因分析及解决措施

为有效防治采煤机长螺杆的断裂故障,基于采煤机长螺杆的构成,分析了采煤机长螺杆断裂故障现象,通过对采煤机长螺杆材料强度与刚度的校核,结合现场调研,找出了故障原因,并提出了一系列具体的改进措施.通过应用这些措施,显著增强了采煤机长螺杆组件的可靠性,提高了采煤机的开机率,促进了采煤机的生产效率.     

非对称型线螺杆压缩机试验研究小结

螺杆压缩机的耗功大是这一类型压缩机的主要缺点,这影响了螺杆压缩机的广泛使用。一九七二年初我厂与通用机械研究所组成了螺杆压缩机试验研究小组,进行了非对称型线螺杆压缩机的试验研究工作,至今已取得了一定的成绩,并为螺杆压缩机的进一步发展创造了条件。     

暗杆楔式闸阀阀杆密封结构改进

阐述了一种带压可更换阀杆密封填料的暗杆楔式闸阀结构，分析了其工作原理和性能。     

Kinematics and dynamics of deployable structures with scissor-like-elements based on screw theory

Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element（SLE）. First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.     

双螺杆与单螺杆压缩机,谁更好一点?

螺杆压缩机有双螺杆与单螺杆压缩机两种不同的结构。就两者工作与结构特点进行剖析，从理论与实际上做一比较。     

重载静压丝杠螺母结构设计

为满足重型单柱移动立式车床横梁升降结构承重大、效率高的要求,开发研制了重载静压丝杠螺母结构。该结构具有承载能力大、摩擦系数非常小、可靠性高、传动效率高和噪声小的特点。     

基于PLC的挤出机进料段内螺纹加工控制系统研究

针对普通车床在塑料挤出机进料段内螺纹加工时存在效率低和内螺纹螺距超过500 mm时无法自行加工的问题,将采用触摸屏、PLC和其位置单元设计开放式控制系统的技术应用于研制高效数控专用铣床中。开展了内螺纹螺旋线理论方程和现有加工过程的分析,建立了专用铣床在内螺纹加工过程中各个轴之间的运动关系,提出了"采用威纶触摸屏MT8000和松下FP2可编程逻辑控制器及其插补型位置单元,设计内螺纹加工的专用铣床及其控制系统"的方法;在理论上对内螺纹加工铣床的可行性和加工效率进行了评价,并进行了控制系统的试验和生产实践。研究结果表明,所研制的数控铣床在进料段内螺纹加工时的效率提高了25%以上,达到了预期设计要求,同时加工系统还具备"操作界面简单、容易上岗"等特点。     

Three-dimensional modeling for predicting the vibration modes of twin ball screw driving table

As a redundant drive mechanism, twin ball screw feed system has the advantage of high stiffness and little yaw vibration in the feeding process, while leads to increased difficulty with vibration characteristics analysis and structure optimization. Only low-dimensional structure and dynamics parameters are considered in the existing research, the complete and effective model for predicting the table＇s vibrations is lacked. A three-dimensional（3D） mechanical model of twin ball screw driving table is proposed. In order to predict the vibration modes of the table quantitatively, an analytical formulation following a comprehensive approach is developed, where the drive system is modeled as a lumped mass-spring system, and the Lagrangian method is used to obtain the table＇s independent and coupled axial, yaw, and pitch vibration modes. The frequency variation of each mode is studied for different heights of the center of gravity, nut positions and table masses by numerical simulations. Modal experiment is carried out on the Z-axis feed table of the horizontal machining center MCH63. The results show that for each mode, the error between the estimated and the measured frequencies is less than 13%. The independent and coupled vibration modes are in accordance with the experimental results, respectively The proposed work can serve a better understanding of the table＇s dynamics and be beneficial for optimizing the structure parameters of twin ball screw drive system in the design stage.     

滚柱丝杠副的啮合计算

滚柱丝杠副是近年来发展起来的新型传动部件，它的工艺性和使用性能均高于滚珠丝，介绍了滚柱丝杠的结构。通过建立丝螺纹曲面和滚柱曲面方程，研究丝杠和滚柱之间的啮合关系，从而为机构参数的选择提供理论上的依据。     

The effect of dynamic behavior on surface roughness of ball screw under the grinding force

The dynamic behavior of a ball screw under a moving grinding force and the resulting ball screw surface roughness are investigated. The system includes a ball screw, a headstock, a tailstock, a steady rest, a grinding wheel, and a wheel head. Equations of motion of the system are derived through Lagrangian approach combined with global assumed mode method in this study. The transient responses of the system due to a moving force are evaluated using Runge?CKutta method. Results show that the steady rest can reduce 90% vibration in a grinding process. An equation is proposed to predict the maximum response by the cutting depth. Then we simulate the grain height distribution on the grinding wheel, considering transient response on the ball screw and the grinding wheel. Lastly, the ball screw surface roughness could be simulated via calculating the depth of all working grains. The purpose of using grinding process is that the ball screw needs fine surface roughness. The ball screw surface roughness is influenced by the grain size more than the structure numbers can be.     

基于粒子群算法的螺旋输送机多目标优化设计

以螺旋输送机的重量最小和输送效率最大作为数学模型的2个目标函数,螺旋体的结构参数为设计变量,建立了螺旋输送机的多目标优化模型,并用粒子群算法编程求解数学模型。求解优化结果表明,螺旋输送机的重量减少8.2%,输送效率提高4.5%,对螺旋输送机的优化设计具有一定的指导意义。     

卷筒双阶螺旋绳槽的加工工艺

以320t水电站门式起重机的卷筒为例，简要介绍了双阶螺旋绳槽的结构及特点、制造工艺。重点介绍了在数控天桥铣上加工成形的工艺。