金刚石线切割单晶碳化硅锯切力的实验研究

从锯切力的角度对金刚石线锯锯切单晶SiC材料的加工过程进行了研究。得出了线速度、进给速度、线锯张紧力对锯切力的影响规律。从单位长度线锯材料去除量、锯切比能的角度讨论了锯切工艺对锯切力的影响机理。在金刚石线锯锯切单晶SiC过程中,锯切力随着线速度的增大而减小,随着进给速度的增大而增大,线速度与进给速度对锯切力的综合影响表现为:单位长度线锯材料去除量的增加会增大锯切力。单位长度线锯材料去除量对于金刚石线锯锯切单晶SiC材料的锯切比能具有显著的影响。     

焊接吊耳锯切质量评定指标及影响因素

焊接吊耳是钢结构制造过程中用于吊装的重要零件。结合传统的锯切原理,从结构上分析焊接吊耳的锯切,为减小留根量,在利用带锯条锯切焊接吊耳时需要采用水平锯切方式,同时不能使用传统的带锯条扭转装置,而应该增大张紧力保证锯切质量。并将切口表面粗糙度Ra和留根斜度的正切值ρ作为锯切焊接吊耳质量的评定指标。采用正交实验法研究张紧力、锯切速度以及进给速度对焊接吊耳锯切质量的影响。研究表明:张紧力和进给速度对Ra和ρ的影响最大,锯切速度对粗糙度影响较小;张紧力越大,进给速度越小,则锯切质量越好。     

Mechanistic cutting force model in band sawing

In order to establish a mechanistic model of cutting force, specific cutting pressure was first obtained through cutting experiments. The band sawing process is similar to milling in that it involves multi-point cutting, so it is not an easy matter to evaluate specific cutting pressure. This was achieved by making the thickness of workpiece smaller than one pitch of the saw tooth, analogous to fly cutting in the face milling process. Then the cutting force was predicted by analysing the geometric shape of a saw tooth. The tooth shape used was the raker set style that is generally used in band sawing. A set of teeth comprises three teeth, ranked as left, straight, and right. The mechanistic model developed in the research considered the shape of each tooth in a set. The predicted cutting forces coincided well with those measured in the validation experiment. Therefore, the predicted cutting forces in band sawing can be used for the adaptive control of saw-engaging feed rate in band sawing.     

金刚石绳锯加工弧区锯切力分布的研究

本文针对金刚石绳锯的柔性加工以及长锯切弧区的加工特点,采用弧区内分段的实验方法,在弧区七个位置选取了50 mm的微段,对每个微段进行锯切力的测量,进而总结出锯切加工弧区内锯切力的分布情况.研究结果表明:当线速度和进给速度较小时,整个弧区的锯切力的波动较小,随着线速度和进给速度的增大,弧区锯切力在整个弧区的波动随之变大;...     

基于多元非线性回归分析法的圆锯片锯切花岗岩锯切功率预测模型

根据φ350 mm金刚石圆锯片锯切花岗岩的实验数据,利用多元非线性回归分析法建立了金刚石圆锯片锯切花岗岩的锯切功率预测模型。通过实验数据与模型预测数据比较,验证了该预测模型的可行性。结果表明:多元非线性回归分析法预测模型的拟合效果较好,预测的锯切功率与实验锯切功率相比,相对误差绝对值的平均值仅为2.17%;影响圆锯片锯切功率的最主要因素为进给速度,其次为金刚石磨料的综合强度,最后为锯切深度。      

不同切削条件对带锯条横向振动位移的影响

利用MJ3210A型跑车带锯机锯切,针对普通杠杆压坨式自动张紧系统,根据L25正交试验法设计试验,以锯轮主轴转速、压坨重力、上下锯卡距离、树种、进料速度为主要因素,对完好带锯条锯切木材的横向振动位移信号进行采集测量,并对试验数据进行分析,发现影响带锯条横向振动位移因素的主次顺序为带锯轮转速>树种>进料速度>压坨重力>锯卡距离,各因素的影响规律均不是单调的,存在着一定的合理范围。通过对数据分析,得出使带锯条横向振动位移最小的优化组合切削方案为A 2B 4C 4E 1,即带锯轮主轴转速760 r/min,压坨重力95 N,锯卡距离600 mm,进料速度12 m/min,此时带锯条横向振动位移为1.239 mm。     

金刚石薄锯片高速锯切花岗石过程中的锯切力特性

本文对金刚石薄锯片高速锯切花岗石过程中的锯切力特性进行试验研究,在较宽的参数范围下,通过测量水平力、垂直力和主轴功率来计算切向力和法向力.对锯切力、力比、单颗金刚石承受的平均载荷进行了分析.结果显示,提高锯片的线速度使锯切力、力比和单颗金刚石磨粒承受平均载荷减小;在高速锯切时,锯切力随着锯切深度和进给速度的增加而增加,而进给速度对锯切力的明显影响要小于锯切深度,应选择小切深大进给的工艺参数组合;锯切力比随锯切深度的增加而增加,随进给速度的增加而减小;单颗金刚石磨粒承受平均载荷随着单颗粒金刚石最大未变形切削厚度的增大而线性增大.     

金刚石框架锯锯切研究(Ⅸ)-锯条张紧变形和应力的有限元分析

本文对国内外锯切张紧力的理论和测量研究结果、锯条的失稳倾斜进行了全面的综述，然后根据锯切力研究的数据，采用有限元法对不同加工条件下锯条锯齿焊接根部受力和锯条的变形等问题进行了研究。结果表明，在锯切过程中锯条与结块焊接边缘两侧出现应力最大值，因此较易产生疲劳裂纹；锯条的挠度随偏心力的增大而增大；不同结块位置上的锯条受到的力和变形是不同的；在通常的切削过程中，张紧力的存在可以保证锯条的刚性，但不可能因为锯条张紧力和切削力的抵消作用，使得锯条呈现直线状并切削。仅仅在合适的加工条件下，锯条在切削段的局部区域可能表现为相对较为平直和良好的切削接触状态。     

Practical implementation of cutting force model for step drill using 3D CAD data

As an extension of the cutting force model, which was developed by analyzing the forces on rake and relief face, a practical method of cutting force model is suggested. By a calibration test, cutting coefficients are determined, including the information on tool geometry, work material and cutting conditions such as cutting speed and feed rate. As inputs for the force model, normal rake angle and normal relief angle were obtained by a new method from the measured angles using a 3D CAD machine. This practical force model can be applied for machining CFRP successfully, which was proved from the experiments.     

Characteristics of cutting forces and chip formation in machining of titanium alloys

Chip formation during dry turning of Ti6Al4V alloy has been examined in association with dynamic cutting force measurements under different cutting speeds, feed rates and depths of cut. Both continuous and segmented chip formation processes were observed in one cut under conditions of low cutting speed and large feed rate. The slipping angle in the segmented chip was 55°, which was higher than that in the continuous chip (38°). A cyclic force was produced during the formation of segmented chips and the force frequency was the same as the chip segmentation frequency. The peak of the cyclic force when producing segmented chips was 1.18 times that producing the continuous chip.The undeformed surface length in the segmented chip was found to increase linearly with the feed rate but was independent of cutting speed and depth of cut. The cyclic force frequency increased linearly with cutting speed and decreased inversely with feed rate. The cutting force increased with the feed rate and depth of cut at constant cutting speed due to the large volume of material being removed. The increase in cutting force with increasing cutting speed from 10 to 16 and 57 to 75 m/min was attributed to the strain rate hardening at low and high strain rates, respectively. The decrease in cutting force with increasing cutting speed outside these speed ranges was due to the thermal softening of the material. The amplitude variation of the high-frequency cyclic force associated with the segmented chip formation increased with increasing depth of cut and feed rate, and decreased with increasing cutting speed from 57 m/min except at the cutting speeds where harmonic vibration of the machine occurs.     

皮带输送机用陶瓷托辊专用切割锯床设计

分析陶瓷材料加工传统工艺的不足,根据用户要求,针对陶瓷材质输送机托辊脆硬性高、加工难度大的特点提出采用专用锯床的多锯片一次性旋切方案,从而保证托辊两端面的平行度、成品率及加工效率。针对Al_2O_3陶瓷托辊设计了切割加工的专用锯床。阐述了专用锯床的整体结构,并对旋切方案、锯片更换机构及支撑座的设计、切割力与功率计算、工作过程作了详细介绍。     

烧结金刚石串珠绳锯切花岗石的锯切力研究

本文对烧结金刚石串珠绳在锯切花岗石过程中,锯切力及锯切后工件表面的轮廓进行了跟踪检测,研究了锯切过程中,锯切力随锯切参数的变化,以及锯切力与工件表面轮廓的相互关系。实验结果表明：锯切过程中,工件上所承受的锯切力Fh和Fv随着线速度Vs的提高而减低,随着进给速度吩的提高而增加。垂直力与水平力之间存在着良好的对应关系,垂直力与水平力比约为4．18。加工后工件轮廓偏差量随着工件所承受的垂直力的增加而增加,两者之间呈指数关系。     

铝合金建筑型材圆锯片锯切振动特性分析

在铝合金建筑型材圆锯片切削过程中，型材因受到圆锯片周期性冲击而产生振动和噪声，严重影响了加工效率以及加工质量。设计圆锯片锯切铝合金建筑型材单因素实验，研究不同进给速度下铝合金建筑型材的锯切振动特性。时域分析结果显示，振动信号会随着锯切位置的变化呈现出明显的分段特性，振动最剧烈阶段的振动加速度峰值是振动最平稳阶段的3倍以上，说明以横向翼板类结构为代表的典型型材结构会对振动信号产生显著影响。通过频谱分析，型材锯切振动的峰值频率与圆锯片转动频率不存在倍数关系，说明转动频率不是影响型材锯切振动的主要因素，并且振动能量会随着进给速度的提高逐渐由低频处向高频处转移。随着进给速度由25.0 mm/s提高到75.0 mm/s,进给方向振动加速度的峰值由1 669.91 m/s²逐渐增大至2 001.59 m/s²,提高了19.86%;垂直进给方向振动加速度的峰值由932.52 m/s²逐渐增大至1 097.30 m/s²,提高了17.67%。结果表明：铝合金建筑型材的各种组成结构对圆锯片锯切振动的影响远大于进给速度...     

金刚石框架锯锯切研究(Ⅵ)--在实验机上模拟框架锯锯切过程

测定金刚石框架锯锯切切削力，金刚石结块磨损和锯条变形等是十分重要也是非常困难的。在前面对锯切运动，锯切机理，锯切切削力和金刚石结块磨损研究的基础上，介绍了一种在实验室里用小型框架锯切实验机模拟框架锯锯切过程的实验方法，比较了用单锯条三节块和单锯条单结块锯切石材的实验结果，优选了结块分布间距，与金刚石框架锯锯切加工实验结果的比较表明，在实验机上用单锯条三节块锯切石材时，测量得到的处于中间的金刚石结块的切削性能，可以较好地反映实际加工中金刚石结块的切削状态，利用这一结果，可快速地通过简单的实验，评价金刚石锯条在实际加工中的切削力和金刚石结块磨损特性，其误差在20%以内。     

超声金刚石线锯复合加工工件的对比实验研究

使用改进的金刚石线锯加工机床,分别在有超声作用与无超声作用下对金刚石线锯切割工件的过程进行研究。结果表明:锯切力随金刚石线锯线速度的增大而变小,随工作台进给速度的增大而变大;相同条件下,超声金刚石线锯复合加工与单纯用金刚石线锯加工相比,加工过程中锯切力要小得多,工件加工轨迹直线度更好,表面粗糙度值更小,工件表面加工质量更好。      

金刚石绳锯切割混凝土的锯切力实验研究

对烧结金刚石串珠绳锯在锯切混凝土过程中锯切力的变化进行了跟踪检测实验,研究了锯切力随锯切参数及锯切长度的变化规律.实验结果表明:锯切过程中,工件上所承受的锯切力(水平力Fh和垂直力Fv)随着线速度vs的提高而减低,随着进给速度vf的提高而增加.锯切力随着锯切中工件长度L的增加而增加.垂直力与水平力之间存在着良好的对应关...     

Response surface methodology-based approach to CNC drilling operations

Drilling operation is fundamental in the manufacturing industry to drill holes especially in sheet metal parts. This paper presents a mathematical model for correlating the interactions of some drilling control parameters such as speed, feed rate and drill diameter and their effects on some responses such as axial force and torque acting on the cutting tool during drilling by means of response surface methodology. For this exercise, a three-level full factorial design was chosen for experimentation using a PC-based computer numerically controlled drilling machine built in-house. The significance of the mathematical model developed was ascertained using Microsoft Excel^® regression analysis module. The results obtained show that the mathematical model is useful not only for predicting optimum process parameters for achieving the desired quality but for process optimization. Using the optimal combination of these parameters is useful in minimizing the axial force and torque of drilling operations; by extension, other drilling parameters such as cutting pressure, material removal rate, and power could be optimized since they depend on the combination of drilling parameters which affect the axial force and torque.     

艾默生EV2000系列变频器在无缝钢管带锯机上的应用

介绍了艾默生EV2000系列变频器在攀钢集团成都钢铁有限责任公司精密轧管厂Φ400mm带锯机上的应用情况。在高速带锯机锯切圆形钢管坯料的生产线中,输入辊道电机采用集中变频控制,输出辊道电机采用变频控制,便于坯料的传输和精确定位;带锯机主电机也采用变频器和变频电机拖动,实现带锯条的无级调速,可以针对不同直径大小的坯料而选择不同的锯切速度。实际应用表明,该系列变频器运行良好,控制效果佳,故障率低且投资适中。     

Determination of process parameters through a mechanistic force model of milling operations

Mechanistic process parameters for the end milling operation are determined for 11L17 free machining steel, 2024 aluminum and 62-35-3 free machining brass by analyzing the measured cutting force data and using a mechanistic force model. It has been found that pressure and friction acting on the cutter-chip interface decrease with the increase of feed rate, while the cutting speed has a negligible effect on some of the material-dependent parameters. Process parameters are summarized into empirical equations as functions of feed rate and tool rotation angle for each workpiece material. The use of sampled force data in the computation of the process parameters reduces the amount of testing greatly compared to those methods that utilize only average force data.     

Statistical analysis of the effects of machining parameters and workpiece hardness on the surface finish of machined medium carbon steel

The objective of this study is to ascertain the effect of machining parameters and workpiece hardness on surface roughness of machined components and to develop a better understanding of the effect of process parameters on the machined surface. Such an understanding can provide insight into the problems of controlling the finish of machined surfaces when the process parameters are adjusted to obtain a certain surface finish. The collected data were analyzed using parametric analyses of variance (ANOVA) with surface finish as the dependent variable and hardness of the workpiece material, cutting tool position from the surface of the clamping device (chuck), depth of cut, cutting velocity, and cutting feed as independent variables. The results showed that surface roughness is significantly affected by the workpiece hardness, cutting feed, cutting speed, depth of cut, cutting tool position from the chuck, and their interactions with each other. The results suggest that feed rate and cutting speed can be adjusted to produce a certain surface finish when the position of the cutting tool from the surface of a clamping device or the hardness of the workpiece is changed.