A New Route for Identification of Precipitates on Austenite Grain Boundary in an Nb-V-Ti Microalloyed Steel

The precipitates on austenite grain boundaries in an Nb-V-Ti microalloyed steel have been investigated by transmission electron microscope （TEM） examination of carbon extraction replica. The replica wa...     

Results of Laboratory Investigations into Operating Conditions of Cutting Tool

The results are presented for the investigations conducted on test stand in cutting artificial samples of rock with the ultimate compressive strength up to 105 MPa with and without the high-pressure water jet supply. The pick edge wear and dustiness during cutting are analyzed.     

Performance of Different Tool Steels for the Cutting of an CP1000 Advanced High Strength Steel

During the last decade, AHSS (Advanced High Strength Steels) have received growing attention in the construction of light-weight car bodies with excellent crash-performance. With the rising strength of these materials, the requirements for forming and cutting tools are also increasing permanently. To investigate the tool performance for such conditions, four different cold work tool steels (1.2379 ?C Sverker21, Sleipner, 1.2358 ?C Carmo and Caldie), one of them (1.2379 ?C Sverker21) additionally PVD-coated, were used in their typical heat treatment condition to compare the wear behavior and the cutting performance. The tests were performed on semi-industrial forming and cutting press under industrial process parameters on partially preformed test pieces of the steel CP1000. The measurement methods applied include optical as well as tactile measurement methods to measure the tool wear, optical methods to investigate the cutting zone and the burr formation at the workpiece as well as scanning electron-microscopy to characterize the tool surface regarding wear, fracture and adhesion of the zinc coating. Except for the lower alloyed surface hardened and nitride tool steel (1.2358 ?C Carmo), which showed early failure, all other tooling solutions easily reached 100,000 test pieces with good workpiece quality. Nevertheless, small partial fracturing at the cutting edge was found at all tools. Best results regarding wear, but especially lowest zinc adhesion were found at the PVD-coated tools.     

铝合金钻杆与钢接头可靠连接过盈量的计算及组装工艺

铝合金钻杆具有密度小、比强度高、耐腐蚀性强等优点,但其耐磨性较低。实际使用时,将铝合金钻杆杆体与钢接头组装在一起形成钻杆柱,由钢接头来承受拧卸操作。由于铝合金与钢在弹性模量、热膨胀系数、屈服强度等方面的差异,经常出现连接不可靠的情况。针对147 mm×13 mm的内加厚铝合金钻杆进行过盈量的理论计算,得出满足传递载荷及材料不产生塑性变形的过盈量范围是0.712～1.009 mm。同时对钻杆杆体及钢接头的组装工艺进行介绍。     

几种氮缓释材料对氮渗透损失控制的效果

采用平衡法(Batch技术)和柱法(流动或混合置换技术),就几种缓释材料对氮的渗透损失缓释效果进行评价分析;膨润土、海泡石、沸石都能较好地控制氮的渗透损失,吸水树脂和聚丙烯酰胺虽然加入量很少,但效果很好。     

注氮计算方法优化及注氮效果分析

分析了2种不同计算注氮流量方法的优缺点,通过统计分析采空区氧化带内漏风量与工作面通风量之间的关系,提出了以工作面通风量为主要影响因素的注氮流量计算方法,简化了计算步骤,为注氮流量计算提供了可靠的依据。通过实例应用比较注氮前后采空区自燃三带的变化情况。     

我国钎钢钎具工业发展现状及几点建议

我国的钎钢钎具工业经过近半个世纪的发展，在产量、产品类型、品种规格和质量方面都有了长足的进步，可以说，我国现在已是世界上常规钎具产品生产量最多的国家之一，也是一个钎钢钎具的生产大国。但是，我国钎钢钎具工业现状与国际先     

高速切削参数对刀具性能影响的数值仿真

应用数值仿真,分析了切削速度、切削深度和进给量对刀具温度、磨损的分布以及变化规律的影响。所得结果和分析结论,对选择合适的高速切削加工参数,提高刀具寿命具有一定的参考应用价值。     

切削用量对刀具声发射特性影响的研究

声发射是材料受到内力或外力作用而产生变形或断裂时,以弹性波的形式释放能量的现象,在车削过程中产生大量声发射。分析在切削过程中声发射信号的产生机理,利用SAEU2S声发射检测系统对车削过程进行动态检测。对同种材料进行切削,设置不同的主轴转速、进给量、背吃刀量,探究车削过程中声发射特性变化情况。分析结果发现随着主轴转速增加声发射现象增多,而进给量的增加声发射现象却在减少。在保证加工效率的情况下,适当减小主轴转速增加进给量,可以达到保护车刀的效果。     

Driving of Boreholes in Soil by an Impact Device with Annular Tool

The influence exerted by the basic parameters of an annular tool-equipped device with the impact and traction drives on the velocity of cyclic driving of boreholes in soil is considered. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznyk Iskopaemykh, No. 2, pp. 53–58, March–April, 2005.     

高速钢低温淬火在牙轮钻头上的应用

高速钢制作矿用牙轮钻头轴承系统的衬套,普遍存在破裂现象,通过低温淬火和优化工艺参数,韧性大幅度提高,工业试验的破裂率由传统的９０％～９６％下降到７％～１３％,钻头穿孔米道提高了１７％。     

PCBN刀具材料的性能及切削20CrMnTi合金钢试验研究

以CBN为原料、TiCN和Al为结合剂, 在1550 ℃、5.5 GPa高温高压条件下合成了不同CBN含量的PCBN刀具材料。对PCBN刀具材料进行了显微结构观察、力学性能(磨耗比、硬度)以及高速精密切削20CrMnTi合金钢的切削性能检测。结果表明, PCBN刀具材料的结合剂均匀分布在CBN颗粒周围, 致密性良好;PCBN刀具材料的硬度、磨耗比与CBN含量成正比, CBN含量70%时, PCBN的硬度和磨耗比均最大, 分别为32.97 GPa和7400;高CBN含量的PCBN刀具使用寿命更长。切削试验结果表明, PCBN刀具高速切削20CrMnTi合金钢时的磨损是黏结磨损、氧化磨损、扩散磨损以及局部剥落等各种磨损机制综合作用的结果。     

刀具磨损状态对车削温度影响的试验研究

采用单因素试验法对3种不同磨损状态的刀具分别进行了不同切削要素下的车削试验,利用红外测温仪及其采集系统获得了刀尖车削温度的时变规律。研究结果表明:在相同车削参数和工件尺寸的车削试验中,初期磨损的刀具温度随时间缓慢增加;中期磨损的刀具在小车削深度下温度随车削时间缓慢升高,其温度略高于初期磨损刀具,而在较大车削深度下,温度随时间变化显著;严重磨损的刀具在走刀后期温度随时间急剧升高     

Mixing of Acid Rock Drainage with Alkaline Ash Leachates: Formation of Solid Precipitates and pH-Buffering

Three metal-rich, acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH titration. Changes in pH and the loss of metals in solution due to precipitation of solid phases were tracked. Mineral equilibria and changes in pH and alkalinity were simulated using the geochemical code PHREEQC and the MINTEQv4 database, and the measured and simulated pH responses were compared. The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the mine water compositions (notably the levels of Fe, Al, and Mn). Zn precipitation had a distinct buffering effect at near-neutral pH for the mine waters not dominated by iron. The formation of solid Mg phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but not formation of solid Ca phases, despite high sulfate levels. The phases that precipitated were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn, and Mg. For the Fe-rich mine water, pH was poorly simulated with a simple MIX model, while alkalinity predictions agreed reasonably well with measured data. For the Al-rich mine waters, the simulated pH responses agreed well with the measurements. In an additional step, geochemical simulations were performed where selected proxy phases for major elements were forced to precipitate; this significantly improved the pH and alkalinity predictions. This approach may be more efficient than performing mixing experiments and titrations.     

Characterization of Iron Precipitates in a SAPS Limestone Layer for Flushing System Design

In successive alkalinity-producing systems (SAPS), the limestone tends to get coated with precipitates, reducing the permeability of the SAPS, the mine water treatment efficiency, and the service life of the SAPS. Further study of the precipitates are required to improve the design of flushing systems. In this study, the growth characteristics, particle size distribution, and chemical composition of these precipitates were determined. Based on their growth characteristics, precipitates were classified into four types, and the critical velocity of the precipitates, which is a design parameter of flushing systems, was evaluated through experiments. The resulting critical velocity was used to identify the minimum number of orifices required for lateral pipes in flushing systems.     

基于切削ZGMn13钢的TiN涂层硬质合金刀具的磨损破损研究

对ZGMn13奥氏体高锰钢切削过程中TiN涂层硬质合金刀具的磨损、破损机制进行了研究 ,获得了切削温度、后刀面磨损量与切削时间或切削速度的关系曲线 ,以及刀具前、后刀面显微磨损、破损形貌和化学变化     

接触式对刀仪在刀具长度补偿中的应用

刀具长度补偿是数控加工中心加工的重要操作内容,其准确性将直接影响零件的加工精度和机床的生产效率。为了提高加工中心的加工效率和精度,从实用角度介绍了接触式对刀仪在加工中心刀具长度补偿中的应用。