数控等离子切割机切割件的变形控制

针对数控等离子切割机切割件产生变形的原因,对切割件的变形进行了分析.根据数控等离子切割机的特点,在加工过程中正确选择切割的起点、切割方向、切割顺序、切割速度等工艺,可以有效提高切割件的加工质量,同时对单边工件、细长件、异型件以及特殊件的变形控制进行了详细地阐述.     

细长厚板件火焰切割变形的控制

重点介绍了细长厚板件的切割变形规律,通过采取"局部留桥"(即先留25 mm长一段不切断)的措施,完成长条板件的火焰切割和板条长边焰切坡口,并控制了火焰切割变形。     

数控火焰切割的热应力分析及变形控制

通过对几种典型零件在切割过程中的热应力分析，特别是对采用多割嘴（三只或四只）同时切割的分析，表明产生切割变形的主要原因是合应力的作用。分析合应力，找出影响零件尺寸精度的主要因素，改进切割程序，达到了控制切割变形的目的。     

数控等离子切割技术在凸轮加工中的应用

基于数控等离子切割的优势,针对凸轮零件轮廓特点,提出了一种以割代铣的加工方法。通过制定等离子切割工艺,编写数控程序,提高切割质量,控制热变形等措施,缩短了凸轮制造周期,节约了生产成本,减少了能源消耗。经过试验验证,此工艺方法达到了预期效果。     

等离子切割机直角切割工艺改善

采用等离子切割钢板时,由于等离子切割弧的形状不规则,在切割过程中等离子弧并不垂直于钢板表面,钢板上层先于下层被切割,直角零件常被切割成圆角零件,导致零件切割质量不合格。现对原有工艺进行改善,等割零件一次交检合格率提升至95%,减少了手工打磨时间,零件生产效率提高20%。     

等离子切割技术的最新发展

分析比较了气割、等离子切割、激光切割的切割厚度、速度、成本以及变形情况。阐述了等离子切割技术在提高消耗品寿命等方面的最新进展。     

氧矛切割技术

本文介绍一种独特的氧矛切割方法,切割过程中毋需采用氧乙炔焰加热,而是在细厚壁不绣钢管内通氧流,使钢管末端和割件在氧中燃烧进行切割。切割厚度可达3m。     

气割工艺分析

对切割氧气压力、切割速度及倾角、割嘴与割件距离等对切口表面的质量的影响因素进行了分析,并提出改进质量的措施。     

薄壁管件全自动相贯线切割工艺方法研究

全自动等离子切割凭借其高效、切割成型好、对操作者技能要求低等特点,在桥梁、锅炉容器、船舶等钢结构工程建设中得到越来越广泛的应用.为此针对某产品通风筒进行了大量的调研和全自动等离子切割试验,较全面的掌握了1 mm薄壁管件的等离子切割技术,保证了某产品通风筒的制造质量.     

考虑桥连接的钣金切割件加工路径优化方法

针对包含桥连接的钣金切割件加工路径问题，提出基于旅行商问题模型的钣金件切割路径优化方法，并确定了该方法下桥连接的定位。此方法针对钣金排样图，将轮廓基于图元特征拆分成N_i段子轮廓段加工图元，以遍历所有子轮廓段为目标规划切割路径，采用改进的蚁群算法获得包含桥连接定位点的切割路径，最后依据桥连接定位点确定全体桥连接位置。对排样好的钣金切割件进行仿真验证，并将含桥连接的传统广义旅行商问题切割方法与相关文献方法进行对比，表明了该方法能够有效地减少切割空程路径及切割过程中的启停次数，提高了加工效率。     

Modelling of dynamic cutting coefficients in three-dimensional cutting

A new theory to determine the dynamic cutting coefficients from steady state cutting data for three dimensional cutting has been developed. It is based on direct measurements of cutting forces, without any hypothesis relating to the steady state cutting. The experimental results show fairly good coincidence with the theoretical prediction of the stability limit.     

Three-dimensional cutting process analysis with different cutting velocities

This paper uses the large deformation large strain finite-element theory, the updated Lagrangian formulation and the incremental theory approach to develop a 3D elastic-plastic analytical model that examines metal cutting on the tool tip and twin nodes on the machined face. The geometric position and the critical value of strain energy density, combined with twin node treatment, are also introduced to serve as the continuous chip separation criterion.

Finally, the 3D low-velocity cutting condition of mild steel was explored to analyze changes in the appearances of the workpiece and the chip, the distribution of stress and strain, and the progress of changes in the cutting force. The impact of different cutting velocities and the initial conditions of the residual stress were studied to understand the impact of various cutting conditions on the machined workpiece. The numerical average cutting forces are compared with the experimental cutting forces with the different low-cutting velocities to verify that the 3D cutting model that has been developed is reasonable.     

Mechanics of metal cutting and cutting fluid action

The paper contains an analysis of orthogonal cutting where process geometry is described by the chip compression factor λ and where friction of the rake face is determined by the reduced tool-chip contact length n. The minimum energy principle is applied to a simple upper-bound field and an analytical relationship is found between λ and n. Experimental results, together with data from literature, are compared with the theoretical expression, and the range of validity of the model is discussed. The same model is proposed to explain the action of cutting fluids, a particular feature of the model being that fluid access to the rake face is not required. Three different mechanisms are suggested to account for lubrication in cutting, which generally speaking consists in restriction of the tool-chip contact area. It is proposed to adopt the reduced contact length in efficiency tests for cutting fluids. Experimental results are presented.     

陶瓷刀具在干切削加工中的应用

文章论述了陶瓷刀具的特点和切削性能,对陶瓷刀具在干切削中的使用进行了分析.     

Identification of the specific cutting force for geometrically defined cutting edges and varying cutting conditions

Cutting force modeling is a major discipline in the research of cutting processes. The exact prediction of cutting forces is crucial for process characterization and optimization. Semi-empirical and mechanistic force models have been established, but the identification of the specific cutting force for a pair of tool and workpiece material is still challenging. Existing approaches are depending on geometrical idealizations and on an extensive calibration process, which make practical and industrial application difficult. For nonstandard tools and five axis kinematics there does not exist a reasonable solution for the identification problem.In this paper a co-operative force model for the identification of the specific cutting forces and prediction of integral forces is presented. The model is coupled bidirectionally with a multi-dexel based material removal model that provides geometrical contact zone information. The nonlinear specific forces are modeled as polynomials of uncut chip thickness. The presented force model is not subjected to principal restrictions on tool shape or kinematics, the specific force and phase shift are identified with help of least square minimization. The benefit of this technique is that no special calibration experiments are needed anymore, which qualifies the method to determine the specific forces simultaneously during the machining process. In this paper, experiments with different cutting conditions are analyzed and systematically rated. Finally, the method is validated by experiments using different cutting conditions.     

The effect of vibration cutting on minimum cutting thickness

In the ultra-precision diamond cutting process, the rake angle of the tool becomes negative because the edge radius of a tool is considerably larger compared to the sub-micrometer depth of the cut. The effects of plowing due to the large negative rake angle result in an unstable cutting process without continuous chip. For this reason, it is important to determine minimum cutting thickness in order to enable greater machining accuracy to be obtained by fine and stable machining. It was previously reported that the critical depth of cut with a continuous chip was determined by the tool sharpness and the friction coefficient between a workpiece and a tool [S.M. Son, et al., Effects of the friction coefficient on the minimum cutting thickness in micro cutting, International Journal of Machine Tools and Manufacture 45 (2005) 529–535]. For the same edge radius of a tool, the higher the friction coefficient of the tool–workpiece, the thinner the minimum cutting thickness becomes. Therefore, it is believed that increasing the friction coefficient by a physical method would be effective to achieve thinner stable cutting. In this study, the possibility of reducing the minimum cutting thickness was investigated through changing the friction coefficient of a tool–workpiece. The vibration cutting method is applied to increase the friction coefficient. Experimental results show that the cutting technology is efficient for increasing the friction coefficient and decreasing the minimum cutting thickness. The minimum cutting thickness was reduced by about 0.02–0.04 μm depending on materials and vibration conditions.     

自动切管机切割路径的运动学分析

切管机是管材加工及应用行业的专用加工设备,管材的管-板相贯的几何特点给切割一次成形带来了很大的困难,基于一次成形的考虑,提出了管-板相贯求交的一个通用算法,根据这一算法设计的数控切管机成功地实现了这类坡口一次数控切割成形,并通过一个较为典型的例子作一详细的论述.     

切削温度与切削力综合测量的虚拟仪器

介绍了综合测量切削平均温度和三向切削力并对其进行分析处理的虚拟仪器.利用PCI-1 200卡采集热电偶测温仪和电阻应变式测力仪传输的数据.利用LabVIEW平台开发.具有显示 力和温度波形曲线、热电偶标定和测力仪刻度标定、确定切削温度和切削力指数公式的能力 .提出了基于切削力和切削温度信息的切削状态判定方法.