平衡式双排轴向柱塞泵缸体力学性能分析

为优化平衡式双排轴向柱塞泵缸体的力学性能,分析了缸体的受力情况,建立其力学模型和仿真模型,进行了有限元分析,得出不同结构参数下缸体的应力和应变的响应曲面,优化了缸体结构模型。分析不同载荷下应力应变曲线图,结果表明:平衡式轴向柱塞泵缸体具有良好的力学性能,缸体的轴向最大应变和径向最大应变主要取决于外排的变形;相比于仅外排和仅内排的缸体,双排缸体的径向和轴向应变远小于仅外排和仅内排缸体应变之和,表明平衡式轴向柱塞泵缸体双侧的力存在相互抵消情况,其结构相比普通轴向柱塞泵有一定的优势。     

Optimising the T6 heat treatment for gravity cast AlSi7MgCu0.5 alloy V8 cylinder heads

Alternatives to the Standard T6 heat treatment that relied on a 5-h solution heat treatment at 490 °C were investigated in effort to reduce the heat treatment cycle time for the manufacture of AlSi7MgCu0.5 alloy V8 cylinder heads without sacrificing the mechanical properties while providing extra capacity in the heat treatment plant. The optimum T6 heat treatment process was identified to be a SHT at 545 °C for 1 h followed by ageing treatment at 180 °C for 3 h. Mechanical properties of the cylinder heads thus manufactured were markedly superior while the total heat treatment duration was reduced by 2.5 h with respect to the Standard heat treatment. This implied a capacity increase of %61 and rendered the undertaking of a major customer order possible.     

基于二次曲线拟合的轮对压装机压力标定方法

在实际轮对组装过程中,为了消除一系列因素对油缸显示力值准确性的影响,确保油缸力值显示的准确可靠性。详细分析了控制软件显示界面中油缸压力的显示误差。介绍了二次曲线拟合的方法及其在压力标定中的实际应用。对比了在标定前后油缸显示压力的误差值。结果表明:使用二次曲线拟合方法对轮对压装机压力标定,可以有效提高油缸力值显示的准确性。     

基于PLC的对称式爬壁机器人的设计

针对壁面作业的特殊性,爬壁机器人必须具备吸附和移动两个基本功能,设计了一种气压驱动、真空吸附、灵活移动的对称式爬壁机器人。该机器人主体部分由有机玻璃构成,既可以减少机器人的质量又可以增加机器人的整体刚度;主要部件是气缸和真空吸盘,采用三菱FN系列PLC控制,由X方向和Y方向上的主气缸及Z方向上的副气缸相互配合完成本体移动、吸盘组吸附和脱离及其他辅助功能。通过对机器人的整体控制实现机器人作业,可降低人工工作的劳动强度,防止工人在壁面作业时出现安全事故。     

RESULTS RESULTING FROM AUTOFRETTAGE OF CYLINDER

Autofrettage is used to introduce advantageous residual stresses into wall of a cylinder and to even distributions of total stresses. Basic theory on autofrettage has been functioning for several decades. It is necessary to reveal profound relations between parameters in the theory. Therefore, based on the 3rd strength theory, σej/σγ, σej/σγ, σej/σγ, σej/σγ and their relations, as well as p/σγ, are studied under ideal conditions, where σej/σγ is equivalent stress of total stresses at elastoplastic juncture/yield strength, σej/σγ is equivalent stress of total stresses at inside surface/yield strength, σej′/σγ is equivalent stress of residual stresses at elastoplastic juncture/yield strength, σej′/σγ is equivalent stress of residual stresses at inside surface/yield strength, p/σγ is load-bearing capacity of an autofiettaged cylinder/yield strength. Theoretical study on the parameters results in noticeable results and laws. The main idea is： to satisfy ｜σej′｜=σγ the relation between kj and k is k^2ln kj^2 -k^2 -kj^2 ＋2=0, where k is outside/inside radius ratio of a cylinder, kj is ratio of elastoplastic juncture radius to inside radius of a cylinder; when the plastic region covers the whole wall of a cylinder, for compressive yield not to occur after removing autofiettage pressure, the ultimate k is k=-2.218 46, with k=-2.218 46, a cylinder＇s ultimate load-bearing capacity equals its entire yield pressure, or p/σγ =（k2 -1）/k2=lnk; when kj≤√e =1.648 72, no matter how great k is, compressive yield never occurs after removing Pas; the maximum and optimum load-bearing capacity of an autofrettaged cylinder is just two times the loading which an unautofrettaged cylinder can bear elastically, or p /σγ = （k2 - 1） / k2, thus the limit of the load-bearing capacity of an autofrettaged cylinder is also just 2 times that of an unautofrettaged cylinder.     

yankee烘缸与高温热风气罩结合用于纸幅干燥节约能量、提高质量和增加产量

该文论述新颖热风气罩与传统yankee烘缸,联合使用于生活用纸纸幅干燥取得很好效果,在提高热风温度25%～30%的情况下使过程的干燥速率加快30%～50%。运种新颖热风气罩是在老式平台的基础上对其结构设计和材料强度进行优化和改进而成,从而能突破传统干燥过程里空气受到温度限制,从而在作业过程里实现节约能量、提高质量和增加产量。     

16V240ZJ柴油机机体疲劳寿命评价方法的研究

本文以16V240ZJ柴油机机体为研究对象,进行了疲劳安全评价方法的比较分析,提出了更为合理的应力幅计算方法。首先进行机体的有限元结构强度分析,并针对疲劳破坏的危险部位使用正应力法、主应力法以及Mises应力法进行了应力幅计算。分析讨论结果明确发现了目前计算应力幅多采用的主应力法和Mises应力法所存在的尚需解决的问题。同时。提出了更为合理的正应力分析方法,并且结合焊接工艺影响因素等,分析讨论了其对疲劳寿命的评价方法影响,为机车车辆的设计制造提供了重要的依据。     

柴油机增压后机体的改进设计

利用有限元分析技术对某机型柴油机增压后的机体、缸盖、曲轴、主轴承盖、缸套等柴油机主要零部件的组合部件进行了结构强度和刚度分析。根据分析结果对薄弱部位作了改进设计,并对改进后的设计进行了效果评估,结果表明,改进后的机体取得了预期的效果。     

T-Stress solutions for a semi-elliptical axial surface crack in a cylinder subjected to mode-I non-uniform stress distributions

This paper presents the T-stress solutions (T₁₁ and T₃₃) for semi-elliptical axial surface cracks in a cylinder subjected to mode-I non-uniform stress on the crack surface. Two cylindrical geometries with inner radius (R_i) to wall thickness (t) ratios R_i/t = 5 and 10 were considered. The T-stresses were applied along the crack front for normalized crack depth values a/t of 0.2, 0.4 and 0.5 and aspect ratios a/c of 0.2, 0.4, 0.6 and 1.0. Three stress distribution; uniform, linear and parabolic were applied to the crack face. In addition to these solutions, concrete formulation of the superposition principle is given for the T₃₃-stress, which is known as an elastic parameter that describes the out-of-plane crack tip constraint effect. Then, the validity of the formulation was shown through application of our T-stress solutions to the problem of an axial semi-elliptical surface crack in a cylinder subjected to internal pressure, and checking that the principle of superposition holds for the problem.     

减小圆柱形坯料镦粗鼓形的模拟研究

镦粗过程中,圆柱体坯料易在侧表面形成鼓形,应用先进的DEFORM锻造有限元软件对一般平板镦粗、套环内镦粗、毛坯凹形端面镦粗和锥形板镦粗进行了数值模拟,并将所得到的模拟结果进行了比较.发现套环内镦粗工艺、毛坯凹形端面镦粗和锥形板镦粗能不同程度地减小鼓形,其中毛坯凹形端面镦粗减小鼓形效果最为明显,另外它和锥形板镦粗都在很大程度上提高了镦粗毛坯的变形均匀性.这对镦粗工艺的制定和工艺方案的选择,具有一定的参考价值.