对42CrMo钢锻件白点缺陷的超声波探伤

介绍对大型钢锻件的超声波检测情况，对检测中发现的白点缺陷进行了全面的验证分析。     

锻件产生白点缺陷的问题分析与预防措施

介绍了白点缺陷的形貌特征，阐述了锻件产生白点缺陷的影响因素与形成机理，提出了自点缺陷的预防措施。     

超声法检测轴类锻件中的白点缺陷

对几种轴类锻件中检测到的白点缺陷进行分析探讨，提出白点缺陷定性的几种判定方法．同时对几种工件白点缺陷进行了解剖分析。     

锻件白点的产生及与锻造的关系

白点是锻件在锻后冷却过程中产生的一种内部缺陷,是锻件的致命缺陷.分析白点缺陷形成原因,有利于预防白点的产生,提高锻件的质量.     

大型不锈钢锻件锻造表面缺陷的火焰清理技术

本文介绍了在碳钢和普通合金钢大锻件锻造表面缺陷火焰清理技术基础上发展的大型不锈钢和其它高铬钢锻件锻造表面缺陷火焰清理技术,阐述了其原理及应用,并对这一技术在提高大型不锈钢锻件的精度、节约能源和原材料等方面的经济效益进行了分析。     

锻件内部脆性夹杂物边界裂纹锻合的应力条件

大型锻件内部脆性夹杂物边界裂纹是影响大型锻件疲劳寿命与冲击性能的主要缺陷。热锻变形过程中,脆性夹杂物周围区域的应力场是影响边界裂纹闭合的主要因素之一。为研究应力场的影响,给出平均相对球应力的定义及其数学表达式,并借助数值模拟研究不同应力场的平均相对球应力对脆性夹杂物边界裂纹的影响。结果表明,只有当脆性夹杂物周围区域的应力场的平均相对球应力代数值小于其临界值,并产生一定大小的变形量,才能使脆性夹杂物边界处的原生裂纹锻合。利用专门设计的试件和型砧,在Gleeble-3180热模拟试验机上进行热压缩变形试验,扫描电镜上观察压缩后试件内部脆性夹杂物边界裂纹的情况。试验结果支持数值模拟结果。     

预防大型锻件缺陷的方法

分析了锻件生产过程中，在锻造、热处理以及炼钢中经常产生缺陷的原因，并提出了预防措施。     

大型锻件锻合内部空洞性缺陷及优化工艺规程的研究

由大钢锭锻成的大型锻件,内部空洞性缺陷在周围基体压应变作用下,变形而闭合,在105℃以上焊合。坯料拔长过程的应变分布和砧宽比及压下量相关,合理选择工艺参数和操作程序,优化工艺规程,使钢锭内部有均匀足够的变形量,可以锻合全部空洞性缺陷,获得密实高质的大型锻件。     

Impedance analysis of forging process and strategy study on compliance for forging manipulator

In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the forging manipulator clamp and the forging blank into account, which will impact on safety of manipulator body and quality of forging blank. This paper presents an impedance model to describe the load and formulates compliance strategies correspondingly to reduce the mutual reaction load for forging manipulator. Firstly, an FEM model of forging process is built. Meanwhile, the clamp of forging manipulator is added to the model as movement constraint and interaction part between the manipulator and the forming process. Secondly, a typical forging process is simulated by changing the movement constraint, and then an impedance model is established to describe the relationship between the load and movement constraint. Finally, two kinds of compliance strategies are formulated according to the impedance model, one is called free compliance, and the other is initiative/passive compliance. The simulation results show that compliance strategies reduce the load amounting to 5 000 kN in z direction between the manipulator clamp and the forging blank obviously, which may lead to serious accidents, such as the capsizing of forging manipulator, the fracture of manipulator clamp, and so on. The proposed research simulates the more real forging process, gets the initiative/passive compliance strategy which is more simple and suitable to the real producing and better for forming a forging process planning and control system in the modern production, and improves the quality and efficiency of heavy forging.     

防锈铝合金5083锻件的焊接方法

介绍了防锈铝合金5083的力学性能,分析了其在低温阀门上尤其是在空气分离设备上应用的特点。论述了铝合金阀门的焊接工艺方法。     

电缆挂钩托片的级进模设计

分析了电缆挂钩托片的工艺性，设计了一种级进模，可以使进料机构和卸料机构大大简化。     

深型腔模具精密加工技术的研究与实现

针对淬硬工具钢切削性能差、深型腔模具加工廓形精度不易保证等问题,提出了一种深型腔模具精密高速加工工艺优化技术.该技术根据构建的加工刀轨长度以及刀具悬伸长度与型腔加工廓形误差之间的数学模型,计算随加工刀轨长度变化的廓形误差值,设计瞬时的螺旋线加工刀轨,运用曲线过渡法,生成了适合深型腔模具精密高速加工的优化刀轨.基于米克朗Duro800高速加工机床,对内星轮模具型腔进行精密加工,结果表明,加工精度可提高IT1～2级,表面粗糙度Ra≤0.8.     

热模锻压力机上差速器十字轴的小飞边锻造

介绍了一种十字轴的小飞边锻造的工艺方法,具有材料利用率高、废品率低及简单实用的特点,在实际锻造生产中具有推广价值.     

Comparison between cold rotary forging and conventional forging

Cold rotary forging is an innovative incremental metal forming process, which is obviously different from the conventional forging process in many aspects, such as the metal flow, degree of inhomogeneous deformation of workpiece and force and power parameters. In the current work, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece is developed under the ABAQUS software environment and its validity has been verified by the experiment. Based on the reliable 3D FE model, the cold rotary forging and conventional forging process are simulated and their difference in the forming process has been thoroughly clarified. The research results may help to understand the cold rotary forging process better. Furthermore, they provide valuable guidelines for further theoretical analysis and experimental studies on the cold rotary forging process.     

Prediction of debris flake thickness

Earlier work has shown that plateaux of very fine-grained material can develop on the surface of a sliding test specimen. In the same tests, flake debris particles had the same chemical composition and structure as the plateau material, and it seems likely that the debris were generated from the plateaux. In this paper we describe a calculation which can yield a prediction of debris flake thickness. The work is based on an energy-based model of friction for coated systems. The basic idea is simple: one compares the friction coefficient μ₁ defined when plateaux are firmly attached to the base material, with the friction coefficient μ₂, defined when sliding occurs between the plateaux and the base material. Delamination occurs when μ₂<μ₁ and this in turn occurs when the plateaux exceed a critical thickness. The plateaux then delaminate by a local shear process and flake debris can be generated. Predictions are consistent with observed flake thicknesses.     

The prediction of maximum forging load and effective stress for different material of bevel gear forging

The manufacture of gears by applying hot or cold bulk forming processes is a quite widespread production method due to its well-known basic advantages such as material and time cost reduction and the increased strength of the teeth. However, the associated process planning and tool design are more complicated. In the precision forging of gears, the workpiece volume, the die design, the power requirement and careful processing are more critical than traditional forging technology. For complete filling up, predicting the power requirement is an important feature of the near net-shape forging process. In this paper, a finite element analysis is utilized to investigate the material properties such as yielding stress, strength coefficient and strain hardening exponent effects on forming load and maximum effective stress. The adductive network was then applied to synthesize the data set obtained from the numerical simulation. The predicted results of the maximum forging load and maximum equivalent stress of bevel gear forging from the prediction model are consistent with the results obtained from FEM simulation quite well. After employing the prediction model one can provide valuable references in prediction of the maximum forging load and maximum equivalent stress of bevel gear forging under a suitable range of material parameters.     

船用锻件的质量控制

根据各船级社规范中对产品质量的有关要求，结合生产实践经验，对船用锻件的质量控制进行了探讨。     

DK-20连杆精密级锻造工艺的应用

通过分析传统工艺锻造连杆的主要质量问题,从改进工艺方案、优化模具设计与制作、控制生产操作过程的标准化作业等方面着手,采用预锻加终锻、热态平面精压两项修整措施对制件的厚度尺寸进行了精确控制;通过控制制坯尺寸来调节产品终锻成型时的变形抗力,利用变形抗力的变化解决了模锻中心、模膛中心、模块中心三心不重合给锻造生产带来的不利影响;采用先进的加热手段,减少氧化的加热方法及合理的工艺、工序设计保障了制件的表面质量;通过对操作过程的标准化作业控制增强了产品质量的稳定性。这一系列的改进较好的解决了用普通蒸汽-空气模锻锤生产锻件时锻件表面质量差、厚度尺寸达不到设计要求、锻件尺寸精度等级低等质量难题。