Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

Numerical simulation and experiment analysis of improving permeability by deep-hole presplitting explosion in high gassy and low permeability coal seam

Created a new damage model for explosive for LS-DYNA3D,taking advantageof the Taylor method aimed at the high gassy and low permeability coal seam,and numericallysimulated and analyzed the deep-hole presplitting explosion.The entire processof explosion was represented,including cracks caused by dynamic pressure,transmissionand vibration superposition of stress waves,as well as cracks growth driven by gas generatedby explosion.The influence of the cracks generated in the process of explosion andthe performance of improving permeability caused by the difference of interval between.explosive holes were analyzed.A reasonable interval between explosive holes of deepholepresplitting explosions in high gassy and low permeability coal seams was proposed,and the resolution of gas drainage in high gassy and low permeability coal seam was putforward.

Deep-Hole Inner Diameter Measuring System Based on Non-contact Capacitance Sensor

A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional mic...

Numerical simulation of deep-hole resistivity anomaly caused by drilling construction in Xinfengjiang geoelectric station

The Xinfengjiang reservoir in Guangdong Province is one of the large reservoirs that have triggered earthquakes of magnitude greater than 6.Numerous earthquakes have occurred since the impoundment of the reservoir,making it one of the most active seismic zones in south China.In 2015,a set of deep-hole resistivity anomalies was observed in the Heping geoelectric station in Dongyuan county,located near the Xinfengjiang reservoir.After a field investigation,we found that a planned well drilling construction of new measuring channels was being carried out during that corresponding period of time.After careful comparison and analysis on the basis of the collected raw data,we had a reason to believe that drilling construction,rather than the inducement of the Xinfengjiang reservoir,was the main culprit for those unusual georesistivity values.So as to verify the above conjecture,we constructed a series of 3D finite element models based on the geological and hydrological infor-mation around Heping station and analyzed the drilling disturbances,respectively.Some significant conclusions were finally drawn according to the precise numerical simulation.This study gives a good example by combining numerical simulation with engineering practice as a way to understand the root cause of georesistivity anomalies in reality.

基于有限元法的某深孔件模锻成形工艺研究

某深孔件是船用低速柴油机中的关键构件,由于其特殊的工作环境,该工件的制造技术有着极高的要求。精密模锻是一种可以改进锻件整体质量及提高产品性能的工艺,因此可以通过模锻工艺来加工该深孔件。本文采用有限元模拟软件对该深孔件在压力机上模锻成形过程进行了数值模拟仿真,分析了锻件的温度场及应力场的分布特征,从而指导该深孔件的实际生产。

小型折叠弹翼加工工艺研究

针对某型折叠弹翼机构中翼根和外翼平面度要求高,需对转轴深孔进行加工,以及薄壁结构容易导致变形等加工难题,提出了先粗铣,再钻深孔,最后以孔为基准精铣外形的加工策略,重点研究了深孔加工方法和翼面立式装夹精铣方法,并研究了其工艺参数。结果表明,所设计的工艺具有加工精度高、效率高且质量稳定的优点,为今后此类产品的加工提供了成功的经验。

特深孔钢件冷挤压工艺

通过对材料为45号钢连接拉杆的工艺性分析, 提出了可行的冷挤压成形方案, 在介绍深孔的挤压成形过程中, 着重阐述如何防止塑性较差的 45 号钢变形开裂以及超出设备限定顶出行程时的挤压方法。在此基础上,根据模具的整体结构, 设计各工序模具工作部分。最后通过试验证明该工艺的可行性, 并对存在问题进行分析, 同时提出相应的改进措施。将冷挤压工艺应用在连接拉杆生产中, 对同类零件的成形工艺及模具设计具有一定的借鉴作用。

轻气炮身管深孔加工工艺研究

针对某轻气炮身管的零件结构和材料特性,分析难加工深孔零件的加工难点,确定合理的加工工艺。通过试验,优选刀具材料和切削参数。从工装设计方面,采用保护架和弹性厚壁套等措施解决难加工深孔零件的加工变形。根据孔轴线偏斜影响因素分析,提出通过附加外力控制孔轴线偏斜量的方法。结果表明:采用该工艺加工身管,内径尺寸精度和表面粗糙度均达到相应技术要求,孔轴线偏斜量为0.9mm/m,解决了难加工深孔零件的加工变形和孔轴线偏斜问题。

深孔类零件的工装设计及刀具改进

针对深孔类零件的加工要求,分析工件的装夹和定位,同时给出其夹具的设计,并针对该零件的加工要求,从不同方面分析刀具选用,有效地解决了原加工方案的加工效率低、成本高等问题,最后提出了提升刀具性能的方法及检测环节注意事项。

薄壁长筒零件深孔镗削工艺与数控组合机床设计

文章对薄壁长筒类零件内孔镗削方法进行了分析,并设计了深孔镗削数控组合机床。同时机床的布局及主轴箱、弹簧夹头、深孔镗刀等关键部件进行了详细介绍。该机床的成功研制,解决了薄壁长筒零件深孔加工的难题,通过更换数控加工程序,更换夹头及刀具,调整液压中心架和导向架的轴向位置,该机床可以实现不同尺寸薄壁长筒类零件的内孔加工,运行效果良好。

带底深孔空心件热成形工艺改进分析

目的研究带底深孔空心件热成形工艺现状与改进措施。方法介绍分析了目前国内外所采用的新工艺、模具结构,新型润滑剂、强制润滑方法,新型模具材料、制造工艺及应用情况。结果采用压型、预冲孔、冲孔、拔伸工艺及模口导向的效果良好,通过高压将润滑剂从冲头内部流向冲孔冲头前端,可实现冲孔强制润滑,模具材料可用3Cr3Mo3VNb,4Cr2MoVNi,3Cr3Mo3W2V等,并采用表面强化等工艺。结论应用表明,上述改进措施可降低壁厚差,改进产品质量,并减小摩擦,降低成形力,比传统材料及工艺显著提高了模具寿命。最后指出了还需进一步解决的问题。

船舶机械零件的深孔工艺及其改进方法

很多机械零件具有深孔,如车床主轴、液压传动轴的油缸等。加工深孔时,刀具细长,钻头容易将孔钻偏,使孔中心歪斜;切屑不易排出,散热能力较差,刀具易磨损;当工件精度和光洁度要求较高时,受刀具刚度的限制,需要采取适当措施,以保证工件质量和生产效率。

重特大型工件深孔加工BTA装置的研制

经研究与实际应用,将BTA深孔钻加工技术移植到落地镗床上加工非回转体工件上的深孔,取得了成功,彰显出镗床用BTA深孔装置加工非回转体工件上深孔的特色。

侧壁带矩形孔圆筒形件拉深工艺研究

本文针对侧壁带矩形孔圆筒形件的结构特点,提出采取先冲孔后拉深成形的工艺方案.借助于计算机模拟和实验研究,比较了预冲孔的形状、大小对拉深成形的影响程度.结果显示:与不带侧孔的相同尺寸的圆筒形零件拉深相比.只要预制孔的形状合理,带侧孔一次拉深不但可以使拉深成形后侧壁孔的形状尺寸满足要求,而且能节省工序、获得更大的拉深高度,实现低碳成形目的.

长筒弹外壳加工工艺的改进研究

长筒弹外壳的加工产品质量对枪、炮管等金属管形火器发展有着非常重要因素影响,针对原有加工工艺出现的零件直线度、同轴度、圆柱度和表面进行粗糙度这四个精度管理方面存在的问题,进行加工工艺分析,发现存在刀杆强度不足、切削用量不合理、工件放置方式等影响加工质量的关键性问题,对现有工艺进行改进与优化形成新的工艺方案,通过加工实验及检验验证,新加工工艺方案对长筒弹外壳的加工精度及表面质量有大幅提升。

基于深孔加工技术的活塞销零件加工工艺改进

阐述了活塞销零件现行加工工艺与不足,介绍了常用的深孔加工技术,着重论述了深孔加工技术对现行活塞销零件加工工艺的改进,以及新工艺的特点和所取得的技术经济性。

薄壁深孔零件高精度夹具的研制

薄壁深孔零件，在加工时容易产生变形和制造误差，导致加工精度难以保证，针对此类问题，设计了一种薄壁深孔加工的专用夹具，克服了传统装夹时工件圆度、圆柱度难以保证的问题，在实际生产中，具有广泛的推广价值。

深孔带底部法兰筒形件成形工艺的研究

某深孔带底部法兰筒形件成形难度较大。针对该型锻件提出了一种镦挤复合成形工艺。利用高温压缩试验获得了锻件材料的真应力-真应变曲线。采用有限元模拟软件Deform-3D对深孔带底部法兰筒形件成形过程中金属流动进行了分析,根据载荷-行程曲线、等效应力分布图验证了模具结构合理性。等效应变分布图表明筒壁容易产生外观缺陷,应注意深孔挤压过程的润滑条件。通过工艺试验制得的深孔带底部法兰筒形锻件,产品外观无缺陷。

Cap rock blast caving of cavity under open pit bench

A laser technique based scanning system was employed to make a comprehensive scanning through borehole forunmapped cavity under open pit bench,then the three-dimensional data will be obtained,and these data were used for theoreticalanalysis and numerical simulation to analyze the stability of cap rock.Acoustic emission techniques were also adopted to carry outlong term real time rupture monitoring in cap rock.Therefore,a complete safety evaluation system for the cap rock was establishedto ensure safe operation of subsequent blasting processes.The ideal way of eliminating collapse hazard of such cavity is cap rockcaving through deep-hole blasting,thus,two deep-hole blasting schemes named as vertical deep-hole blasting scheme and one-timeraise driving integrated with deep-hole bench blasting scheme were proposed.The vertical deep-hole blasting scheme has moreexplosive consumption,but the relatively simple blasting net work structure can greatly reduce workloads.However,the one-timeraise driving integrated with deep-hole bench blasting scheme can obviously reduce explosive consumption,but the higher technicalrequirements on drilling,explosive charging and blasting network will increase workloads.

特深孔铝拉杆热挤压工艺与模具设计

对拉杆形状尺寸和材料性能进行了分析,针对拉杆材料(2A12)塑性差、孔特别深的特点,提出了分两道工序进行热挤压成形的方案,实现了在顶出行程为300 mm的3 150 kN通用油压机上成功挤出杆长450.5 mm、孔深397 mm的特深孔件,解决了挤出长度超过油压机顶出行程的问题,成形的零件外圆和内孔同轴度良好,为解决特深孔件的加工提供了一种可供借鉴的思路。