数控机床改造方案的选择

近年来,随着国内各种类型机床改造需求的扩大,机床改造已经逐渐形成了一个产业,其中绝大部分是数控机床的改造,也有一部分业务来自非数控机床的升级改造。作为一个稳步发展的专业公司,我们在运用西门子系统,进行数控机床改造以及为机床厂提供设计服务两个方面,取得了较大的成果     

论机床的数控化改造

本文主要对机床数控化改造整个过程中需要考虑的问题进行了论述,重点叙述了机床数控化改造方案的确定,改造实施过程中以及改造完成后的验收等内容的注意事项。对机床数控化改造工作具有一定的指导作用。 由于数控机床高加工精度、高生产率的特点,在制造业中的应用比例越来越大,有效地保证了产品质量和产量。购置新的数控机床是提高机床数控化效率的途径,对旧机床进行数控化改造也是提高机床数控化效率的重要途径。机床数控化改造可降低采购数控机床的成本,为企业节约资金。近几年,随着国内各种类型机床改造需求的扩大,机床改造已经逐渐形成了一个产业,其中绝大部分是对旧数控机床的数控化改造,也有一部分是对普通机床的数控化改造。现将机床数控化改造过程中应注意的问题介绍如下,供大家参考。     

论机床的数控化改造

本文主要对机床数控化改造整个过程中需要考虑的问题进行了论述,重点叙述了机床数控化改造方案的确定,改造实施过程中以及改造完成后的验收等内容的注意事项。对机床数控化改造工作具有一定的指导作用。 由于数控机床高加工精度、高生产率的特点,在制造业中的应用比例越来越大,有效地保证了产品质量和产量。购置新的数控机床是提高机床数控化效率的途径,对旧机床进行数控化改造也是提高机床数控化效率的重要途径。机床数控化改造可降低采购数控机床的成本,为企业节约资金。近几年,随着国内各种类型机床改造需求的扩大,机床改造已经逐渐形成了一个产业,其中绝大部分是对旧数控机床的数控化改造,也有一部分是对普通机床的数控化改造。现将机床数控化改造过程中应注意的问题介绍如下,供大家参考。     

普通机床数控化改造思路探讨

为了提高普通机床的加工性能和加工效率,通过分析数控改造单元的工作原理,提出了普遍适用的数控化改造思路,成功地实现了对一般机床的数控化改造.经加工试验表明,改造后的机床提高了机床性能和加工效率,扩大了机床的使用范围,降低了工人的劳动强度,具有较高的性价比和实用性.     

ACCU ROLL轧管机导盘车床的改造

阐述导盘车床的用途,导盘车床改造的原因,改造方案,改造后的使用效果。     

ACCU ROLL轧管机导盘车床的改造

阐述导盘车床的用途,导盘车床改造的原因,改造方案,改造后的使用效果.     

行星式研磨抛光机的设备改造设计

本课题对原有LZM-6B型行星式单臂研磨抛光机进行了某些方面的改造:采用封闭式龙门箱形的主体式结构以提高机床的刚度及稳定性;改善机床工作环境采用球头轴承浮动连接,保证加载均匀。通过改造后抛光机性能实验可以得到,在各种研磨工艺参数相同的情况下,抛光机在改造前后的去除率差别不大,但改造后抛光机对工件加工的表面粗糙度明显优于改造前的。研究结果表明该设备的改造设计,可以较低的成本加工出高精密度的产品,极大地满足了生产与科研的需要。     

NO.7-Ⅱ型村田自动络筒机节电改造

介绍村田自动络筒机改造前状况及改造思路,电气改造选型,安装、变频参数设定及日常维护,改造后效果.     

大型商业综合体不停业母线槽改造施工技术研究与应用

以上海正大广场机电改造总承包工程（标段三）项目为背景,阐述了大型商业综合体在不停业条件下进行母线槽改造施工的难、特点及应对措施;同时,对改造过程中的合理化施工顺序、送电保障措施等核心技术进行了总结,形成了大型商业综合体不停业母线槽改造的整套施工技术。     

NO.7-Ⅱ型村田自动络简机节电改造

介绍村田自动络筒机改造前状况及改造思路,电气改造选型,安装、变频参数设定及日常维护,改造后效果。     

Effects of prebuckling deformations on the elastic flexural-torsional buckling of laterally fixed arches

The effect of the prebuckling in-plane deformations on the elastic flexural-torsional buckling of laterally fixed circular arches is studied in this paper. The finite strains and the energy equation for the flexural-torsional buckling of arches have been derived based on an accurate orthogonal rotation matrix. A closed form solution for the elastic flexural-torsional buckling resistance of laterally fixed arches in uniform bending, including the effects of the prebuckling deformations, is obtained. It is found that the notion that the prebuckling deformations increase the flexural-torsional buckling moment of an arch or of a beam is not necessarily correct for a laterally fixed arch or beam in uniform bending, in deference to a laterally pinned arch. When a laterally fixed arch is subjected to positive uniform bending, the effects of the prebuckling deformations decrease the buckling moment, and the reduction of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When a laterally fixed arch is subjected to negative uniform bending, the effects of the prebuckling deformations decrease the absolute value of its buckling moment when the included angle is very small, but increase the absolute value of the buckling moment when the included angle exceeds a certain value. The increase in the absolute value of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When the ratio of the out-of-plane to the in-plane second moments of area of the cross-section is not small, both the reduction of the buckling moment of a laterally fixed arch in positive uniform bending and the increase of the buckling moment of a laterally fixed arch in negative uniform bending, are substantial.     

车门静态强度的有限元分析模拟

轿车门系统结构设计与优化是整车开发过程中的重要环节。车门的强度直接关系到整车在冲击、碰撞等载荷下的安全问题,车门结构静态强度的计算分析,在车门结构设计进程中非常重要。文中首先简要介绍了静态强度所涉及到的非线性有限元的基本理论,然后以某中高级轿车前车门为例,利用计算机辅助分析车门的静态强度,考虑变形的非线性因素,通过对车门的非线性有限元求解来分析车门强度,由计算所得到的车门强度性能指标来指导车门的结构设计。     

DESIGN AND ANALYSIS OF NOVEL ACTIVE ACTUATOR TO CONTROL LOW FREQUENCY VIBRATIONS OF SHAFT SYSTEM

Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrations is designed. The actuator employs electro-hydraulic system and can provide a high and circumferential load. To initialize new research, the characteristics of various kinds of active actuators to control rotor shaft vibration are briefly introduced. The purpose of this paper is to introduce the preliminary results via presenting the structure, functions and operating principles, in particular, the working process of the electro-hydraulic system of the new actuator which includes a set of high speed electromagnetic valves and a series of sloping cone-shaped openings, and presenting the transmission relationships among the control parameters from control signals into the valves to active load onto shaft. The course of the work is dynamic, and a series of spatial forces and moments are put on the shaft to get an external resultant force to reduce excitations that induce vibration of shafts. By checking states of vibration, the actuator can control the impulse width and the interval of injection time for applying different control force to a vibration shaft in two circumference directions through the regulating action of a set of combination directional control valves. The results from simulating analysis and experiment show evidence of that this design can satisfy the case of active process of decreasing of flexural and torsional vibrations.     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.     

The effect of basic nitrogen compounds on the tribological performance of sulphurised olefin

The effect of the molecular structure of basic nitrogen compounds on the lubricating properties of sulphurised olefin has been investigated using a Timken tester. X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Analysis (EDAX) were used to study the chemical states of sulphur and nitrogen on the rubbed surfaces and the reaction rates of sulphur and iron separately. It was found that the antiwear and friction reduction properties of sulphurised olefin are greatly influenced by the different molecular structures of the basic nitrogen compounds. A composite additive package containing basic nitrogen compounds with sulphurised olefin can produce either synergistic or antagonistic effects, due to the influence of the different molecular structures of the basic nitrogen compounds. XPS analysis revealed that a tribochemical protective film containing nitrogen and sulphur was formed on the rubbed surface. EDAX analysis indicated that the reaction rates between elemental sulphur and iron were influenced by the different molecular structures of the basic nitrogen compounds. It was found that the apparent reaction rates of elemental sulphur and iron are related to the tribological characteristics of the additive package.     

PHENOMENON OF CARVED DRIVING WHEELS

A newly found phenomenon of carved driving wheels of a rear-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions,which distribute regularly and uniformly. Everyday,the tractor tows a trailer which are times heavier than the tractor,and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation,which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer,the slip ratio of the tractor’s driving wheels is very large. Therefore,there is severe torsional self-excited vibration in the tractor’s drivetrain,and the self-excited vibration results in severe and regular fluctuations of the rear wheel’s velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time,the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration,and this times explained the existence of three damaged regions. At last,it points out that the phenomenon can be avoided when the torsional damping is large enough.     

Computer simulation of turbine oil oxidation. 2: Consumption of a hindered phenol antioxidant in laboratory oxidation tests and in service

The computer simulation study of consumption of di-tert-butyl p-cresol (DBPC) was extended to the oxidation of hexadecane/tetralin model oils under conditions of laboratory oxidation tests and in service. The oxidation lives of the model oils in the ALCOA oxidation test and the ASTM D2272 rotary bomb and D943 turbine oil oxidation tests were successfully predicted from the simulation study. The oxidation behaviour of the model oils is compared to that of a turbine oil used in actual service units. The model oil having 6 mass % of tetralin showed almost identical oxidation behaviour to the turbine oil when the same amount of DBPC was added (0.6 mass %). The calculation shows that the direct oxidation of antioxidants is the main process of antioxidant consumption in the laboratory oxidation tests as well as in the model oxidation system without metal catalysts. In most of the service units which operated at moderate conditions the calculation shows that the direct oxidation of antioxidants is also the main, process. As a consequence, the rate of antioxidant consumption does not depend much on the tetralin content in the model oils. The oxidation behaviour of the model oils in the service units which operate under severe conditions, such as in the high temperature regions of turbines, is calculated by setting a flow reactor model. The results of this calculation show in this case that the turbine oil degradation occurs mostly in the high temperature regions and that the rate of antioxidant consumption increases with an increased amount of tetralin in the model oils. This strong dependence on base oil composition can be attributed to the increased importance of antioxidant consumption through the inhibition of oxidation.     

OUT-OF-PLANE COMPRESSIVE PROPERTIES OF HEXAGONAL PAPER HONEYCOMBS

The compressive behaviour of paper honeycombs is studied by means of an experimental analysis. Experiment results show how geometry aspects of hexagonal paper honeycombs,e.g. the height of paper honeycomb,the thickness and length of honeycomb cell-wall,the drawing ratio of hexagonal honeycomb,affect the compressive properties of the paper honeycombs. It is in good agreement with the theory model. The constraint factor K of the critical buckling stress is mainly determined by the length of honeycomb cell-wall. It can be described as K=1.54 for B type paper honeycombs and K=3.32 for D type paper honeycombs. The plateau stress is the power exponent function of the thickness to length ratio of honeycomb cell-wall,and the experiment results show that the constant is 13.2 and the power exponent is 1.77. The research results can be used to characterize and improve efficiently the compressive properties of paper honeycombs.     

PROTOTYPE SURFACE MICRO- PRECISION IN FUSED DEPOSITION MODELING PROCESS

To aim at prototype parts fabricated with fused deposition modeling (FDM) process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is explained with three aspects concretely including the principle error of rapid prototyping (RP) process, the inherent characteristics of FDM process, and some micro-scratches on the surface of the extruded fiber. Based on the micro-characters of section shape of the FDM prototype, a physical model reflecting the outer shape characters is abstracted. With the physical simplified and deduced, the evaluating equations of surface roughness are acquired. According to the FDM sample parts with special design for experimental measurement, the real surface roughness values of different inclined planes are obtained. And the measuring values of surface roughness are compared with the calculation values. Furthermore, the causes of surface roughness deviation between measuring values and calculation values are respectively analyzed and studied. With the references of analytic conclusions, the measuring values of the experimental part surface are revised, and the revised values nearly accord with the calculation values. Based on the influencing principles of FDM process parameters and special post processing of FDM prototype parts, some concrete measures are proposed to reduce the surface roughness of FDM parts, and the applying effects are better.     

聚酰亚胺对聚四氟乙烯基自润滑复合材料摩擦磨损性能的影响

研究了不同聚酰亚胺(PI)含量的聚四氟乙烯(PTFE)基自润滑复合材料的摩擦磨损性能,并分析了干摩擦和预浸油润滑两种条件下的磨损表面形貌和磨损机理.研究表明:PI的加入在于摩擦状态下能显著提高复合材料的减摩性能,并且随着含量的增加效果更加明显;但其抗磨损作用并不明显,其磨损量取决于复合材料的协同作用,而玻璃纤维和MoS2减磨作用明显;在预浸油润滑条件下,由于油润滑占主导地位,复合材料基体减摩效果不能充分体现.