冷拔内螺纹管拉拔力的有限元计算方法

本文基于三维弹塑性大变形有限元分析理论,通过对内螺旋凸筋管冷拔成形过程进行有限元仿真,建立增量步与拉拔力的关系,提出了拉拔力的计算方法.经实验验证,理论计算值与实测值相吻合,可为拉拔模具和工艺参数的设计提供参考.     

Net shape formation of sub-micron alumina with reduced flaws by high-speed centrifugal compaction process

A new compacting method for powder materials is presented. High-Speed Centrifugal Compaction Process (HCP) utilizes centrifugal force of about 10,000 g for the compaction. HCP is suitable for net shape compaction of fine sub-micron and nano-powders. HCP possesses a unique compacting mechanism that is different from other colloidal processes including Pressure Casting (PC), and has a number of useful characteristics. HCP has a higher compacting speed than PC, wide applicability for net shape formation, as well as a defect removing function. Because of homogeneous and flawless green microstructure, HCP alumina shows superior sinterability and higher strength and hardness than most of other aluminas. This article is based on a presentation made in the symposium “The 3rd KIM-JIM Joint Symposium on Advanced Powder Materials“, held at Korea University, Seoul, Korea, October 26–27, 2001 under auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

振动机械的调整与质心的计算

以一台振动筛的故障处理为例,说明振动机械的激振与运动特点、调整原理及其应用。介绍用计算机计算参振零部件及设备质心的方法。     

提高钻杆接头冲击功的工艺方法

针对石油钻井关键产品高强度钻杆接头的使用要求,在保证强度指标要求非常高的前提下,研究摸索增加高温正火后再调质的工艺方法,以改善接头材料原始微观带状组织和纤维结构,细化晶粒,提高钻杆接头的冲击功,使该产品力学性能达到API标准的要求。     

气缸低速运动摩擦力模型的研究

对气缸摩擦力进行了全面和深入的分析，通过仿真模拟和实验拟合，提出了符合气缸低速运动摩擦特性的模型——指数函数模型。结果表明，采用该摩擦力模型，气缸运动的仿真模型精度更高，能够更好地描述气缸低速运动过程，对于气缸优化设计和气缸正常使用具有参考价值。     

锻压机械打击力测量误差的加速度补偿

提出了锻压机械打击力测量中存在的问题，介绍了常用的补偿法，并通过实验验证了加速度补偿法是消除锻压机械打击力测量误差的有效途径。     

应用BP神经网络的单机架可逆式冷轧机弯辊力预设定

针对单机架可逆式冷轧机生产过程中，由于不同热轧生产厂的热轧板形原料性能、板形差别较大、从而造成弯辊力预设定值和实际指标相差较大的问题，利用现场生产工艺数据丰富，采用人工智能BP神经网络的方法，通过大量数据输入进行训练，大大的提高了生产过程中弯辊力预设定值的准确性。     

Effect of ultrasonic power and bonding force on the bonding strength of copper ball bonds

Copper wire, serving as a cost-saving alternative to gold wire, has been used in many high-end thermosonic ball bonding applications. In this paper, the bond shear force, bond shear strength, and the ball bond diameter are adopted to evaluate the bonding quality. It is concluded that the ef/~cient ultrasonic power is needed to soften the ball to form the copper bonds with high bonding strength. However, excessive ultrasonic power would serve as a fatigue loading to weaken the bonding. Excessive or less bonding force would cause cratering in the silicon.     

An investigation of laser-assisted machining of Al2O3 ceramics planing

Laser-assisted machining (LAM), an alternative method of fabricating difficult-to-machine materials, uses primarily laser power to heat the local area (without necessarily evaporating or melting any material) before the material is removed. It not only efficiently reduces the cutting force during the manufacturing process but also improves the machining characteristics and geography with regard to difficult-to-machine materials, especially structural ceramics.This study on the application of laser-assisted machining to Al₂O₃ ceramics examines the measurements of cutting force and workpiece surface temperature as well as surface integrity and tool wear. Specifically, it uses the lattice Boltzmann method (LBM) to calculate the temperature distribution inside the ceramic workpiece during the LAM process and ensure that the laser energy causes no subsurface damage. The experimental results reveal that the LAM process efficiently reduces the cutting force by 22% (feed force) and 20% (thrust force) and produces better workpiece surface quality than conventional planing.     

滚切剪剪切力的实验研究

对直导向滚切剪的剪切力进行了实验研究，得到了计算最大剪切力的经验公式。