氧丙烷快速割嘴氧通道设计

针对氧丙烷快速割嘴工作特点,根据空气动力学原理,为氧丙烷快速割嘴氧通道型面曲线设计开发了工具软件,可以通过给定简单的参数,实现氧通道型面曲线的快速设计．利用所设计的软件完成了一个氧通道方案,并通过计算流体力学软件对氧通道流场进行了数值模拟,得到了割嘴氧通道在其设计工作状态下的氧气射流流场速度、马赫数、氧气质量分数等特性参数分布．结果表明,该割嘴氧通道在设计工作压力下工作性能良好．同时验证了所设计的工具软件的可靠性．     

低碳含碲硫易切削钢的轧制工艺研究与实践

针对实际生产中由于Te的熔点、沸点均较低,在冶炼、浇铸过程中极易气化,使其含量难以控制且回收率较低; Te大多富集在硫化物附近,进一步恶化含Te硫系易切削钢的热加工性,导致轧制过程中产生轧件劈头开裂的问题,利用Gleeble-3500热模拟试验机对含Te硫系易切削钢1214Te的高温塑性规律进行了研究,确定了最佳轧制工艺参数,并成功轧制了φ16 mm盘圆。轧材检验结果表明,1214Te盘圆的布氏硬度不大于170HBW;盘圆夹杂物形貌主要为椭球状或短棒状,分布较为均匀;在相同的切削加工条件下,1214Te盘圆切削效果优于硫系易切削钢1215MS。     

钢材切割现状及Fast切割软件的应用

现代切割技术有别于传统手工切割技术．它是基于现代计算机信息技术．针对不同的切割下料设备。对传统切割技术加以改进提高，发展成为以优化套料技术、钣金展开技术和数据库管理技术为代表的计算机辅助切割生产和管理软件。以有效提高钢材综合利用率，提高切割效率和切割质量．加强切割生产管理。     

PCBN刀具干湿切削加工淬硬钢时的磨损对比

本文研究了在一定切削参数下干、湿式切削加工淬硬钢时四种PCBN刀具的刀具寿命、磨损形式和磨损机理。通过扫描电子显微镜观察不同切削行程下刀尖形貌和刀具后刀面磨损量,并对刀具前后刀面进行能谱分析。结果表明湿式切削时的后刀面磨损量小于干式切削,说明刀具湿切比干切时具有较好的性能;PCBN刀具的磨损形式有前刀面磨损、后刀面磨损,其中前刀面磨损的表现形式为月牙洼磨损,磨损机理为机械磨损、氧化磨损和黏结剂磨损,而后刀面磨损机理有机械磨损、氧化磨损、黏结剂磨损和扩散磨损等;同时还发现CBN含量下降,刀具的后刀面磨损量也有下降趋势,即刀具的切削寿命有延长趋势。     

液化石油气在割焊技术中的应用

开发了一种液化石油气割焊设备，采用液化石油气进行切割与焊接，与乙炔相比，不但更具有经济性、安全性和高的切口质量，而且对环境污染少。它的开发与利用必将越来越为人们所重视。     

PcBN加工淬硬钢刀具材料的研究

介绍了立方氮化硼刀具材料( PcBN)的制备过程,并制备了六种不同配方的样品加工淬硬钢.通过切削实验和性能检测,发现PcBN刀片在加工淬硬钢时cBN浓度起着关键作用,切削同样的路程,低浓度PcBN的后刀面磨损量小.经扫描电镜观察,CoAl合金粉能够提高PcBN烧结刀具材料的致密度.测量耐磨性时,证明用于金刚石复合片PC...     

1215MS易切削钢铸坯皮下气泡原因分析及改进

分析1215MS高氧、高硫易切削钢铸坯皮下气泡分布特征及其产生原因,通过控制钢中总氧含量、调整结晶器电磁搅拌参数、改进保护渣理化性能等工艺技术,气泡缺陷得到明显改善,由此提高了钢材及其加工成品的表面质量。     

水下50 m激光切割30 mm厚钢板特性

在模拟50 m水深环境下进行中厚板激光切割,通过切割的宽度和断面粗糙度研究了氧气压力、喷嘴到工件的距离、切割速度等对切割质量的影响.结果表明,氧气压力较低时,切缝底部无法割透,下半部分有较多熔渣相连.随着氧气压力增加,切缝背面排渣能力明显增强,切缝平直度增加.与大气中切割不同的是氧气压力增大,切缝壁面反而光洁.喷嘴到工件的距离对切缝各部位尺寸影响均不明显,文中取平直度最佳的范围2~4 mm.随着切割速度增加,切缝下部宽度减小最明显,切割断面纹理线发生弯曲,在水下50 m环境中,切割30 mm厚钢板,最快切割速度可达到2.0 m/min.     

Prediction of the cutting temperatures of stainless steel with chamfered main cutting edge tools

The main purpose of this report is to predict the temperature of carbide tip's surface and study the cutting forces of turning stainless steel with sharp chamfered main cutting tools. The friction forces and frictional heat generated on elementary cutting tools are calculated by using the measured cutting forces and the oblique cutting analysis. The heat partition factors between the tip and chip are solved by using the inverse heat transfer analysis, which utilizes temperature on the carbide tip's surface measured by infrared as the input. The temperature of the carbide tip's surface is solved by finite element analysis (FEA) and compared with those obtained from experimental measurements. A good agreement demonstrates the accuracy of the proposed model.     

氧-天然气切割和焊接技术研究

研究了氧-天然气金属切割和焊接技术.结果表明:通过设计出优质快速切割喷嘴和双层焊接焊炬,采用合适的切割和焊接工艺规范和措施,氧-天然气切割和焊接技术能获得良好的切割质量和焊接质量,且能满足一般效率要求;与氧-乙炔气体相比,氧-天然气切割和焊接技术成本最低,具有显著的推广应用价值.     

Y15易切削钢孔洞分析及其预防

采用体视显微镜(SM)、金相显微镜(OM)、扫描电子显微镜(SEM)及能谱仪(EDS)等对Y15易切削钢孔洞形成的原因进行了分析.结果表明,孔洞两边的裂纹呈应力裂纹特征,是最后一次热轧后方坯冷速过快所致,而孔洞则产生于随后的冷拔过程中.通过将方坯轧后空冷改为进缓冷坑缓冷后,制作的零件再无孔洞出现.     

激光切割过程辅助气体动力学性能的数值模拟

激光切割过程中辅助气体的动力学性能对切缝形成过程具有重要影响.利用VOF算法和深度自适应激光热源,建立了能反映切割过程中辅助气体和切缝之间相互作用的多相流模型,结合切割试验对模型的有效性进行了验证.采用多相流模型分析了从打孔到稳定切割过程中切缝形貌、辅助气体动力学性能和温度场分布.计算结果表明,在未切透阶段,受切割前沿形状和切割深度等的影响,辅助气体动力学性能不断发生变化;当切割过程稳定后,辅助气体流场几乎不发生变化,切缝形状和温度场也不再改变;所建模型能够有效反映辅助气体动力学性能对切割深度和切缝宽度的影响.     

Improvement of corrosion resistance of high-velocity oxyfuel-sprayed stainless steel coatings by addition of molybdenum

To improve the marine corrosion resistance of stainless steel coatings fabricated by high-velocity oxyfuel (HVOF) spraying with a gas shroud attachment, the molybdenum (Mo) content of stainless steel was increased to form coatings with a chemical composition of Fe balance-18mass%Cr-22mass%Ni-2∼8mass%Mo. These coatings were highly dense, with <0.1 vol.% in porosity, and less oxidized, with 0.5 mass% in oxygen content at most. The corrosion mechanism and resistance of the coatings were investigated by electrochemical measurement, chemical analysis, and statistical processing. The general corrosion resistance of the coatings in 0.5 mol/dm³ sulfuric acid was improved with increases in Mo content, and the corrosion rate could be decreased to 8.8 × 10⁻² mg/cm² per hour (∼1 mm/year) at 8 mass% Mo. The pitting corrosion resistance of the coatings in artificial seawater was improved with increases in Mo content and was superior to that of the 316L stainless steel coating. The crevice corrosion resistance of the coatings in artificial seawater was improved and the number of rust spots at 4 mass% Mo was decreased to 38% of that for the 316L coating. Accordingly, Mo is highly effective in improving the corrosion resistance of the stainless steel coatings by HVOF spraying.     

Influence of the direction and flow rate of the cutting fluid on tool life in turning process of AISI 1045 steel

High-pressure coolant (HPC) delivery is an emerging technology that delivers a high-pressure fluid to the tool and machined material. The high fluid pressure allows a better penetration of the fluid into the tool–workpiece and tool–chip contact regions, thus providing a better cooling effect and decreasing tool wear through lubrication of the contact areas.The main objective of this work is to understand how the tool wear mechanisms are influenced by fluid pressure, flow rate and direction of application in finish turning of AISI 1045 steel using coated carbide tools.The main finding was that when cutting fluid was applied to the tool rake face, the adhesion between chip and tool was very strong, causing the removal of tool particles and large crater wear when the adhered chip material was removed from the tool by the chip flow. When cutting fluid was not applied to the rake face, adhesion of chip material to the face did occur, but was not strong enough to remove tool particles as it moved across the face, and therefore crater wear did not increase.     

Corrosion-fatigue behavior of an annealed AISI 1045 carbon steel coated with electroless nickel-phosphorus

The influence of an industrial electroless nickel-phosphorus deposit on the corrosion-fatigue properties of an annealed AISI 1045 steel has been investigated. For this purpose, three corrosive media were selected: distilled water and two NaCl solutions of different concentration (3 and 5%) in distilled water. Corrosion-fatigue tests were conducted at alternating stress levels ranging between 219 and 329 MPa at a frequency of 50 Hz. The corrosion-fatigue properties of the coated and uncoated substrates are very similar when testing is conducted in salty water. However, for testing in distilled water the corrosion-fatigue properties of coated substrates were diminished in relation to the uncoated material. The fractographic analysis of the fracture surfaces revealed the presence of fatigue marks within the electroless nickel-phosphorus deposit, which indicate that the fracture mechanism of the coating is associated to the cyclic loading of the material.     

不锈钢薄板光纤激光切割优化实验

激光切割是一个复杂的过程。为了研究光纤激光对304不锈钢薄板切割质量的影响,发现工艺参数对切割指标的影响规律,得到最优切割工艺参数,本文利用光纤激光器对1mm、2mm、3mm厚度的304不锈钢进行了激光切割实验。通过软件设计实验、板材切割、数据采集、软件分析等过程,利用三维曲面表达结果。实验表明:挂渣量的多少主要取决于焦点与功率,且两者都存在一个最佳范围;切缝宽度的大小主要取决于板厚与功率;粗糙度的大小主要取决于功率和焦点,两者也存在一个最佳范围;条纹间距主要取决于气压和功率,最终得到切割3种不同厚度板材的最优参数。     

M2高速钢钻头热处理工艺及切削性能

优化了M2高速钢钻头的热处理工艺参数。结果表明,最佳热处理工艺为1184℃淬火+370℃回火1次+560℃回火2次,此时的显微组织评级为晶粒度10级,回火程度1级,过热程度1级。应用该工艺制造的钻头平均钻削深度为3.04 m,标准差为1.77,变异系数为0.58,评为一等品。     

钢丝成形模设计

通过分析零件的结构特征,设计钢丝切断、压弯和卷圆在1副模具中完成,并运用弹簧复位装置,整副模具结构设计合理,动作稳定可靠,零件完全达到客户要求,可为同类型零件的模具设计提供参考。     

Turning of stainless steel with worn tools having chamfered main cutting edges

A force model is proposed in this study for a single-point tool with a chamfered main cutting edge incorporating a wear factor. The variations of shear plane areas occurring in the tool-worn situation are also used. Cutting experiments are conducted on stainless steel bars and the experimental data correlated closely with the theoretical values. A preliminary discussion is also made of the design of special tool holders and their geometrical configurations. The tool holders were milled using medium carbon-steel bars and these holders with the mounting tips were ground to fit various specifications.     

35CrMo钢气瓶热处理时爆裂失效分析

5CrMo钢气瓶在热处理时发生爆裂,对其样件进行宏观检验、微观分析、力学性能测试、化学成分分析,并对同批次气瓶进行现场模拟试验以及有限元分析。结果表明：密封气瓶内壁粘附的石墨和水在高温下生成的可燃气体与氧气反应发生爆炸,产生瞬时高压,导致气瓶爆裂。