重卡离合器压盘热应力有限元分析与改进

针时某公司生产的Ф430干式膜片弹簧式离合器,为解决其在使用中出现的压盘变形、烧蚀和开裂等导致部分零件提前失效的问题,采用有限元软件ABAQUS,根据起步时压盘的客观工况进行了热应力耦合仿真分析,并依据分析结果提出了空气冷却式压盘改进方案.结果表明,改进后的压盘在减轻质量的同时增加了压盘的刚度和强度,提高了压盘的工作性能.     

无损水射流插桩机压盘装置设计

根据水射流无损插桩施工技术要求,研制了一种与钢筋混凝土预制管桩配合使用的压盘装置。该压盘装置主要作用是连接管桩及供水系统、并起到承载吊具的作用。该压盘装置由压盘、连接螺栓组、吊耳连接弯管等几部分组成。可与直径500 mm或600 mm的管桩配合,承载不超过16 t。     

拖拉机上装什么样的差速器好

差速器的种类很多,下面对常用的几种差速器的性能,以及它们对拖拉机的适应性作一简要论述。 1.摩擦片式差速器这种差速器,实际上是普通差速器的变型。它可以利用普通锥齿轮差速器的许多标准零件。在差速器壳与半轴锥齿轮之间装有摩擦片6与压盘2,行星齿轮十字轴的端部做成V形面,与之相配的差速器壳上的轴承孔也为V形面。压盘和从动摩擦片用内花键与半轴齿轮上的花键连接,主动摩擦片上的外花键与差速器壳连接。     

塑料凳子中间小孔有何作用

正大家有没有注意到一个细节,不论何种形状的塑料凳子,中间都会开一个不大不小的圆孔,知道这是什么原因吗?如果不开孔,上下两个凳子之间会形成一个密闭的空间,空气压力导致拉开凳子会很困难,摞凳子的时候也很难摞紧实。那么为什么是圆孔而不是别的形状?因为,有尖角的孔受力时易裂开,而圆形孔容易做模具。另外,孔太大会影响结构的强度,孔太小又不利于手指的勾取。     

顶拔式拔根机初探

本文介绍了一种新颖的顶拔式拔根机的总体结构和工作原理,计算了拔根力和压盘沉陷量。利用顶拔原理可以采用较小功率的拖拉机拔出直径较大的树根,具有很大的实用价值。     

提高钻孔质量的几种方法

1钻孔加工易出现的质量问题在钻孔加工中,经常出现下列问题:①孔形不圆或为多边形;②孔径扩大或缩小;③产生锥形孔;④加工表面质量低。对上述问题,经我们分析和研究,总结出几种提高钻孔质量的方法。2提高钻孔质量的方法2.1避免孔形不圆孔形不圆的主要原因是由于钻头定心不稳产生的,而定心的稳定性取决于钻头锋角的大小和横刃长短。通常情况下,锋角要偏小,横刃要短。要减短横刃,可以加大横刃角。对加工精度要求较高的孔,可在钻孔前用中心钻先钻出定心孔,使钻头在钻孔时更稳定。当钻头刚切入工件就发现孔形不圆时,应立即停止钻削,并重新修磨钻…     

非结构集成材加工技术及质量控制

介绍了非结构集成材的分类，阐述了非结构集成材工艺流程、刨削加工、加工余量、操作技术及安装刀具的规则。确定了非结构集成材加工质量要求。     

发展竹业促进扶贫和经济发展

竹子生产周期短,容易加工,用途广泛,是最重要的非木材可再生资源。中国竹业的发展为广大发展中国家发展竹业提供了有益的借鉴。国际竹藤组织正作出新的努力,帮助东非国家发展竹业,促进扶贫和当地经济的发展。     

分离器制造工艺技术研究

介绍了超临界锅炉中分离器的主要结构特点及制造难点,对非径向管孔的加工、非径向管接头坡口的加工、非径向管接头的焊接等问题给出了详细的解决方案,并对分离器的整体制造工艺流程做了简要介绍。     

森林资源非空间数据的加工整合技术探讨

介绍了森林资源非空间数据所包含的主要内容。从数据的分类和编辑处理,数据标准化、数据检查和质量控制等角度探讨了森林资源非空间数据的加工处理方法。对进一步加强我国森林资源非空间数据的加工整合及共享提出了建议。     

Development of an air-injection press for preventing blowout of particleboard II: improvement of board properties using small-diameter holes for air injection

An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into boards during press heating. The air-injection press can manufacture boards from high-moisture-content particles by controlling blowouts of the boards. In this study, boards were manufactured from particles that had a moisture content of 25% by using the air-injection press, which reduced the required pressing time. Boards manufactured by injecting air through holes of 5 mm in diameter were of poor quality with a low internal bond strength of only 0.31 MPa. When the hole diameter was reduced to 1 mm, the internal bond strength increased to 0.44 MPa. A high air-injection pressure of 0.55 MPa also resulted in improved board properties over those for boards manufactured at lower pressures. This was probably because a large amount of binder was released from boards through the 5-mm holes, together with water vapor, during air injection; the small-diameter holes reduced the release of binder, resulting in better board properties.     

Development of an air-injection press for preventing blowout of particleboard I: effects of an air-injection press on board properties

An air-injection press was developed to prevent particleboard from blowing out during the manufacturing process. The air-injection press, which has holes punched in the heating plates, injects high-pressure air into the board through the holes of one plate and releases the air through the holes of the other plate. The high-pressure air forces out vapor trapped within the board, thus preventing blowout. The newly developed press reduced the pressing time required for manufacturing board from high-moisture-content particles. However, the manufactured boards exhibited mechanical properties and dimensional stability inferior to conventionally manufactured boards.     

Development of an air-injection press for preventing blowout of particleboard IV: effects of air-injection conditions on board performance and formaldehyde emission

An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into particleboard and discharges the air through the other plate during press heating. The press can manufacture particleboard from high-moisture particles by controlling blowout of the boards. In this study, the optimum diameter and spacing of the air-injection holes and the effects of pre- and post-pressing were investigated. An optimum hole diameter was not found for the modulus of rupture and thickness swelling for a spacing of either 25 or 50 mm. In terms of internal bond strength, the optimum diameter of the holes arranged at a spacing of 25 mm was 1 mm, but the internal bond strength was not changed by the diameter of holes spaced 50 mm apart. Air injection under all hole conditions reduced the formaldehyde emission from the board. Pre-pressing was tested for further increase in the modulus of rupture and internal bond strength, but was found to have no effect. More efficient use of the air-injection press was achieved by injecting air from the early stages of pressing.     

齿顶曲线误差对非圆齿轮副重合度的影响

以非圆齿轮插齿加工为例，分析了利用渐开线圆柱插齿刀加工非圆齿轮时齿顶曲线误差对非圆齿轮重合度的影响，为严格控制非圆齿轮副的重合度提供了理论保证。     

Development of an air-injection press for preventing blowout of particleboard (III): effects of pressing temperature on board performance

An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into particleboards and discharges the air and vapor through the other plate during press heating. The press can manufacture particleboards from high-moisture particles by preventing blowouts of the boards. In this study, the effects of pressing temperature were investigated by pressing boards at 190, 210, and 230°C. The internal bond strength increased from 0.43 to 0.60?MPa by raising the temperature from 190 to 210°C, but did not increase further when the temperature was raised to 230°C. Raising the temperature from 190 to 210°C also helped improve the thickness swelling. No relationship was found between the modulus of rupture and pressing temperature.     

基于虚拟样机的配流盘结构对柱塞泵压力的影响研究

以典型斜盘式轴向柱塞泵为载体,分析了其工作原理,利用AMESim搭建其虚拟样机软件的液压模型,并对其进行参数设置。利用所建模型,分别对泵在配流盘开设三角槽、偏转安装以及三角槽与偏转安装相结合三种情况进行仿真。通过对比柱塞腔油压及输出压力曲线,得出以下结论：在配流盘上开设三角槽和配流盘偏转安装对泵的柱塞腔油压及泵的输出压力冲击均有很好的减弱作用;同时采用开设三角槽与偏转安装这两种方式时,压力冲击减弱更加明显。该仿真结果可为轴向柱塞泵的减振减噪提供有益的参考。     

结构用集成材自动上下料装置真空吸附系统设计与试验

针对结构用集成材加工过程中上下料自动化程度低、劳动强度大、效率低等问题,设计了 一种真空海绵吸盘抓取结构用集成材自动上下料装置,实现结构用集成材的高效、自动化上下料作业.选用杉木结构用集成材在自动上下料装置上进行负压与供气压力关系试验和负压与海绵吸盘拉脱力试验.利用MATLAB软件,对试验数据进行最小二乘法函数曲线拟合...     

氧气含量对竹材炭化特性的影响

竹材炭化过程中,炭化温度和炭化时间是两个十分重要的工艺参数,同时炉内的氧气含量对竹材炭化也会产生较大影响。通过传感器实时测定并控制炉内氧分压,研究炉内氧含量对竹材炭化的影响。结果表明,随着炉内氧分压增加,得炭率下降。用电子显微镜和能谱仪分析观察竹炭的微观结构和残留物成份,揭示竹炭蜂窝状的微观结构;随着炉内氧分压增加,竹炭孔径变大,表明炭化过程中氧含量影响竹材炭化过程中细胞的收缩。     

油缸试压台架框架板的受力分析

介绍了油缸试压台架的工作原理，对台架的框架板进行了受力分析并加以计算，校核，以此为依据，对框架板进行了改进。     

Moisture content—water potential relationship of wood from saturated to dry conditions

Summary The water potential concept as applied to wood-water relations is presented. The gradient in water potential can be used as the driving force of moisture in wood in a model of drying in isothermal conditions provided the moisture content — water potential relationship is known. This relationship is established for aspen sapwood in desorption from saturated to dry conditions at 20, 35 and 50 °C for two specimen orientations. The tension plate, pressure plate and pressure membrane methods were used at high moisture contents and equilibration over saturated salt solutions was used at low moisture contents. The results obtained demonstrate that these methods can be used in combination in order to establish the relationship within the whole range of moisture contents. The equilibrium moisture contents obtained by the tension plate, the pressure plate and the pressure membrane methods for tangential desorption were slightly higher than those measured for radial desorption. The water potential increased with temperature at a given moisture content. This effect cannot be solely explained by the variation of surface tension of water with temperature.This research was supported by the Fonds pour la Formation de Chercheurs et l'Aide à la Recherche, Gouvernement du Québec, and by the Natural Sciences and Engineering Research Council of Canada