综采面硬岩深孔松动致裂爆破技术试验研究

针对综采面坚硬岩石割煤机切割效率低的问题,根据工程地质特征,采用大直径深孔爆破,增加岩体裂隙、破坏其整体性,再用割煤机切割的施工方案。爆破后,割煤机切割的岩石呈块状落下,切割速度提高了50%~55%、截齿消耗减少40%~46%,并降低了粉尘量,取得了良好的爆破效果。同时,对爆破的有害效应进行了监测和分析,结果表明深孔松动爆破不会对巷道及支护结构产生危害。     

关于异型零件的数控火焰切割机编程及切割

通过对一些典型异型零件的计算机编程和实际切割经验来说明异型零件编程的一些经验体会及切割时所采取的工艺措施。散近代火焰切割机所切割零件的形状尺寸、切割质量及材料利用率的高低主要是由零件编程决定,特别是异型零件切割程序编写的是否适宜将直接影响零件的切割质量、材料利用率的高低及切割的效率。数控火焰切割机在作业现场主要功能是切割,只能利用图库编写零件的单个切割,无法实现食割。笔者经过几年的编程实践,对零件的切割编程有所体会,现用我厂年产量较大一些典型异型零件的切割编程介绍编程的一些经验,体会及切割时的工艺措施。     

综采面硬岩深孔松动致裂爆破技术试验研究

针对综采面坚硬岩石割煤机切割效率低的问题,根据工程地质特征,采用大直径深孔爆破,增加岩体裂隙、破坏其整体性,再用割煤机切割的施工方案。爆破后,割煤机切割的岩石呈块状落下,切割速度提高了50%⁵5%、截齿消耗减少40%55%、截齿消耗减少40%⁴6%,并降低了粉尘量,取得了良好的爆破效果。同时,对爆破的有害效应进行了监测和分析,结果表明深孔松动爆破不会对巷道及支护结构产生危害。     

用氧-乙炔焰切割不锈钢

<正>在少量加工不锈钢时,采用氧-乙炔火焰切割是简易可行的。切割时,预热火焰要大而集中,氧气压力要比一般切割碳钢工件大15~20%。采用中性火焰切割时,首先要用火焰加热工件边缘,待其呈红色熔融状态,再打开氧气阀,稍稍抬高割嘴,熔渣便从切口流出。此时应使割嘴作一定幅度的前后、上下摆动。嘴头摆动的频率为每分钟60~80次左右,振幅10~15毫米,割嘴与工件夹角为70~80°。     

浅谈掘进机伸缩保护筒的改善加工

随着我国工业化进程的不断发展,煤炭行业也稳步提高,目前井下普遍使用的巷道掘进设备多以悬臂式掘进机为主,掘进机截割部中伸缩保护筒又是其重要的部件之一。伸缩保护筒的作用是保护伸缩内筒,与切割减速器相联,支撑切割部。伸缩保护筒的质量好坏影响掘进机正常工作运行。因为伸缩保护筒的结构特点是薄壁工件,所以很难加工。本文是从加工工艺方面对伸缩保护筒的加工质量进行分析研究。     

掘进机数字化自动截割系统

通过高精度矿用位移传感器采集截割头动作数值,可编程序控制器自动控制截割头动作,实现巷道立面的数字化切割。系统已成功应用于本公司EBH360型掘进机。     

关于割煤机的技术应用采煤

割煤机在采煤运用中，一直以来都以其便携、重量轻、可单人操作、功能强大、适用范围广、使用寿命长等诸多优点被广大的煤矿业采煤人员广泛应用，其适用露天的煤矿、硫磺矿、石膏矿的施工作业，可以切割煤层、岩石、混凝土、钢筋混凝土、管道、砖石、石头和其它石材等诸多物质，被视为矿业工作中最理想方便的工具。本文经过对割煤机和对其使用技术的研究，特对割煤机在采煤应用中出现的一些问题提出了分析，并对其作出了一些建议。     

核电管道用316LN不锈钢等离子切割工艺参数优化研究

为解决AP1000核电挤压成形厚壁管道等离子切割表面和切口成形质量差、裂纹多、后续加工量大等问题,本文搭建了大功率等离子切割试验平台,并针对20～100 mm厚核电管道用316LN不锈钢板材,采用控制变量法研究了等离子切割过程中主要工艺参数对切割质量的影响规律。研究结果表明:切割电流175～210 A,切割速度770～830 mm/min,气体压力0.56～0.64 MPa,喷嘴高度7.1～7.8 mm为20 mm厚316LN不锈钢等离子切割质量较好的工艺窗口; 在等离子切割过程中,4个主要工艺参数对切割质量的影响规律曲线均为凹型;切割电流和切割速度之间的相互匹配显著影响切割的表面质量,切割速度对后拖量影响较大,喷嘴高度对切缝宽度及切口成形影响较大。将本文实验方法及工艺参数对切割质量的影响规律应用于60～100 mm厚316LN不锈钢切割工艺参数的优化研究,获得了中厚板等离子高质量切割的工艺窗口,实验验证表明,切割表面质量和切口成形质量均有明显提升,满足后续加工工艺要求,且去除量较小,可为核电厚壁不锈钢管道的高质量切割提供工艺参考。     

TRIZ理论在掘进机截割头设计中的应用

为了进一步提高掘进机的截割性能、降低截齿的磨损损耗,在学习了发明问题解决理论(TRIZ)的基础上,运用其中的冲突概念和冲突解决原理及问题求解等方法,针对如何优化截割头截齿排布、如何提高截割效率、如何改善截齿受力、如何降低截齿磨损等问题进行了TRIZ解析,并在第15条发明原理(动态特性原理)的启发下,得到了特定的解决方案——截齿变角度螺旋线排布,据此思想并结合常规的截割头设计手段,研发了3款截齿以不同方式变角度螺旋线排布的截割头,与原截割头一并进行了切割比能耗的试验,试验结果表明J23截割头性能比较高效、稳定,在此基础上稍加改动即可定型量产.     

小型甘蔗收获机切割器振动对切割力的影响

针对小型甘蔗收获机切割器振动导致破头率高的问题,通过设计不平衡质量块构建切割器的激振源,模拟切割器的动不平衡,实现了刀盘的可控振动,并通过力学计算、仿真验证了试验的可行性。通过仿真及物理试验平台砍蔗试验,探究了刀盘振动对切割力,以及切割力对宿根切割质量的影响关系及作用机理。仿真表明,当切割力最大时,轴向切割力约占总切割力的92.6%;试验表明,振动对切割力影响显著,在1.02~1.20 mm振幅范围内切割力呈线性上升趋势;轴向切割力与宿根切割质量的相关系数为0.91~0.95,刀盘振动对甘蔗宿根切割质量的影响主要是通过轴向切割力的作用来实现的。     

Development of a knowledge-based expert system for solving metal cutting problems

In metal cutting, the problems need to be well analyzed in order to take precautions before any unexpected results are encountered. This process plays a significant role in achieving consistent quality and in controlling the overall cost of manufacturing. However, it is a difficult task that needs an expert who has a great deal of information and experience in metal cutting. In the present paper, a knowledge-based expert system (COROSolve) that investigates problems that are encountered in three main metal cutting areas: turning, milling and drilling is developed. A great deal of metal cutting operations such as external/internal turning with negative/positive inserts, aluminum turning, parting bars/tubes, grooving, profiling, recessing and threading operations in turning; face milling, square shoulder milling, end milling, multi-purpose milling and side and face milling operations in milling; and drilling operations that use solid drills or drills with indexable inserts in drilling are taken into consideration. COROSolve gives recommendations for the cutting data (i.e., cutting speed, depth of cut, and feed) and updates the problem, cause and remedy database, thus the number of problems that the system can handle is increased.     

Construction heuristics for generating tool paths for laser cutters

This paper deals with generating paths for cutting irregular parts nested on thin or thick metal sheets. The objective is to minimise the total time required to cut all parts from the metal sheet explicitly taking the cost of piercing and pre-cutting into account. The problem is modelled as a generalised travelling salesperson problem with special precedence constraints. A set of construction heuristics is presented that incorporates the constraints originating from inner–outer contours, common cuts, piercing points and pre-cuts. Computational tests on a set of real-life cutting problems show that our solution approach is able to generate tool paths that for thick plates spend on average 33.4% less time than those generated by a commercial package for air movements, pre-cuts and sharp angle macros with cutting and piercing times being equal.     

Investigating the Tool Life, Cutting Force Components, and Surface Roughness of AISI 302 Stainless Steel Material Under Oblique Machining

The aim of this work is to investigate the machinability of austenitic AISI 302 stainless steel under oblique cutting. This can be achieved by studying the cutting forces, analysis of tool life, and investigation of the surface roughness at different cutting conditions and nose radius. A factorial experiment and analysis of variance technique are used in which several factors are evaluated for their effects on each level. The machinability experiments are based on design of experiments to obtain empirical equations for machinability values for machining conditions such as speed, feed, depth of cut, and nose radius. The parameters considered in the experiments were optimized to attain maximum tool life using a response graph and a response table. Based on the response models, dual response contours (tool life and surface roughness as a response and metal removal rate) have been plotted in cutting speed-feed planes. Evaluating the effect of the predominant variables influencing the value of tool life is very important for improving the machined product quality.     

截割厚度与截线距对镐型截齿破岩力学参数的影响

基于对一种砂岩的直线截割试验,研究截割厚度和截线距对镐型截齿破岩力学参数的影响。单因素回归表明:截割力、法向力与截割厚度成正比,线性拟合和幂函数拟合均能很好地描述它们之间的统计学关系;随着截割厚度的增加,法向力截割力比值呈线性减小;随着截线距的增加,截割力和法向力呈线性增加,法向力截割力比值呈幂函数减小。载荷波动性系数随着截线距与截割厚度比值的增大呈线性减小。多元线性回归表明:截割力、法向力与截割厚度和截线距之间有极强的统计学关系;载荷波动性系数与截割厚度及截线距之间存在显著的统计学关系,且与截割厚度成正比,与截线距成反比。对比发现,Evans的理论模型较Roxborouth等、Goktan的改进模型对截割力有更好的预测性能。     

碳纤维蜂窝复合材料加工表面质量影响研究

为研究碳纤维蜂窝复合材料切削过程中切削宽度和切削方向对表面质量的影响,本文开展了高速切削碳纤维蜂窝实验,分析了切削过程中切削力的变化特征,获得了切削宽度和切削方向对切削力的影响规律。同时,观测了碳蜂窝典型表面缺陷形貌,分析了不同切削宽度和切削方向下表面缺陷的分布规律。进一步以蜂窝壁损伤面积占比作为表面质量的评价方法,定量研究了切削宽度和切削方向对于碳蜂窝表面质量的影响。实验结果表明：在碳纤维蜂窝复合材料加工过程中,减小切削宽度和改变切削方向可有效降低加工损伤。切削力随着切削宽度的增大呈现出增大的趋势;毛刺、撕裂、孔壁破损以及孔壁开胶等损伤现象也随着切削宽度的增大而增加。此外,碳纤维蜂窝复合材料的表面质量还与切削方向有关,相较于沿双层孔壁方向切削,当切削宽度分别为5、10及15 mm时,沿垂直于双层孔壁方向切削的损伤分别减小了22.5%、13.4%和8.7%。     

Effect of Oxygen in Laser Cutting Process

Laser cutting has become an acceptable process in automated sheet metal industry. Efficiency and quality can be maintained with laser cutting. However, oxygen assisted cutting may influence the metallurgical structure of the cut edges. Consequently, in the present study, oxygen diffusion into solid substrate in the vicinity of the cut edge is considered together with the metallurgical changes at the cut surface. To achieve this, an experiment is designed and conducted to cut stainless steel workpiece with a CO₂ laser beam at different oxygen pressures. To determine the elemental distribution in the vicinity of the cut edges, Micro-Particle Induced x-Ray Emission (μ-PIXE), Nuclear Reaction Analysis (μ-NRA) and EDS are carried out. It is found that no oxygen peak is evident at the cut edge and Cr, Al and Si are enriched locally.     

Model for thermodynamic point identification in laser cutting

In recent years, laser cutting has been introduced and developed to such an extent that it is now thought to be one of the leading and indispensable manufacturing tools. At the present time, dross‐free and accurately‐cut parts are basically regarded as the major targets to aim for, because the costs and efforts associated with dross removal by postprocessing cut parts are considerable. Therefore, control of dross formation during laser cutting is an important factor in maintaining edge quality. The initial aim of this paper is to describe the importance of physico‐mechanical material properties that need to be taken into account in modeling of laser material processing in order to control melting of the material.     

碳纤维增强复合材料单向层合板直角自由切削热特性试验

为揭示碳纤维增强复合材料(CFRP)切削温度与切削要素之间的关系,采用直角自由切削对CFRP单向层合板进行了切削试验,并采用OMEGA-0.05mm高灵敏K型热电偶对切削温度进行测量,讨论了切削参数、刀具几何参数及材料参数对切削温度的影响。结果表明:对切削温度的影响程度由高到低的参数依次为切削速度、切削厚度、刀具后角和钝圆半径,切削参数对温度的影响效应不受纤维方向角的影响;不同于金属材料,CFRP纤维方向角对切削温度影响突出,顺纤维方向上的切削温度明显高于逆纤维方向上的,切削温度在θ=90°时达到最大值,且为θ=0°时的2倍;CFRP切削回弹对刀具后刀面与已加工表面的接触状况影响较大,从而影响切削温度,加剧了切削温度的各向异性特征,且第3变形区切削热对切削温度影响突出;CFRP切削温度范围窄,最大切削温度在300℃左右,将导致切削质量对温度变化更为敏感。     

Bandsägen für die Steinbearbeitung – aktuelle Technologieentwicklung

Bandsawing machines for stone cutting – state of the art Due to an EU‐research‐project BaSST a new process was developed to cut slabs and tiles in granite, marble and sandstone out of a huge stoneblock by means of a bandsaw. Such natural stones are very hard, the cutting forces generated to the sawband have to be limited. This was realized with a pivoting sawband, which allows to vary the effective length of engagement depending of the dimension of the material. Simoultaneausly a sawband with diamond cutting segments was developed and tested. Over a long period of optimization a long lifetime of the sawband was reached. The end of the service life was determined by normal wear of the cutting segments and not by breakage of the sawband together with very high cutting rates and excellent cutting surfaces. The outstanding advantage of this new cutting process is a high flexibility for the production, so far unknown till now, a very good cut quality and a remarkable reduced waste of material due to the thin sawband. The number of slabs cut from a block can be doupled due to the thin kerf of the sawband. The new cutting process allows to cut slabs and tiles from a block in a very economic way and under best environmental conditions.     

A study of parameters affecting the continuous CO2 laser cuts

Abstract

This work attempts to discover, by experimentation, some of the parameters governing cutting efficiency in perspex of a continuous CO₂ laser. The experimentation took the form of taking cuts in specimen pieces with the laser. While varying the parameters of speed of cut and position of the focal plane of the laser beam relative to the surface of the perspex, all other parameters were kept constant. These experiments produced conclusive ideas of the optimum position of the focal plane and the best speeds for cutting perspex at the same time producing the best cut quality obtainable. When the theoretically predicted minimum cut width is compared with the experimentally obtained results, the agreement is found to be almost exact.