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《机械工程学报》2017,(13)
针对自由曲面模具的铣削加工,提出一种综合考虑曲面曲率、刀具前倾角和侧偏角的瞬时铣削力预报方法。基于曲面几何特征,研究了进给方向、行距方向曲率半径对刀具切削角度的影响,以及刀具前倾角和轴向切触角对未变形切屑厚度的影响;基于微分思想,将自由曲面加工中任意刀齿切削周期内的切触区进行离散,结合三维次摆线切削轨迹建立未变形切屑模型,得到适合于自由曲面三轴球头铣削的瞬态铣削力,该模型能够综合考虑曲面曲率特征变化、刀具工件切触角度变化;基于二次曲面模具模型进行铣削加工试验,试验测试结果表明,预报的铣削力和试验测量结果在幅值上和变化趋势上具有一致性,在平稳切削时最大铣削力预测误差值在12%以内,验证了该方法能有效地预报自由曲面模具的球头铣削的瞬态铣削力。 相似文献
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《计算机集成制造系统》2016,(4)
针对复杂自由曲面变曲率、大扭曲的特征及其铣削性能难预测的问题,提出加工过程的集成优化的切削性能分析方法,在曲面多轴铣削工作流程中综合评价和提高切削加工效率和质量。建立了自由曲面体零件多轴加工集成优化铣削模型,集成切削加工刀位轨迹计算、切削仿真与机床运动仿真、切削力预测、工艺参数优化工作流程及其输入输出文件,实时从输出文件中解析提取计算结果参数,有效分析预测切削参数与切削力对加工效率和质量的影响,实现复杂自由曲面铣削过程的集成与全局优化。将该方法应用于大型混流式水轮机叶片的数控铣削性能分析,并与生产数据进行对比,进一步验证了所提加工过程集成优化方法可有效分析和预测大型自由曲面的数控铣削性能。 相似文献
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在曲面模具拼接区域球头铣刀铣削过程中,刀具载荷变化大,瞬态铣削力有突变现象,影响模具拼接区域的加工精度和表面质量。为了预测拼接区域球头铣刀的瞬态铣削力,首先,建立考虑冲击振动的球头铣刀三维次摆线轨迹方程,得到瞬时未变形切屑厚度模型;然后,基于铣削微元的思想,建立凸曲面双硬度拼接模具球头铣刀的瞬态铣削力模型,该模型能够综合考虑拼接区冲击振动、硬度变化、刀具工件切触角度变化对瞬态铣削力的影响;最后,进行凸曲面拼接区域球头铣刀铣削加工实验。实验结果表明,预报的瞬态铣削力和实验测量结果在幅值上和变化趋势上具有一致性,在平稳切削时最大铣削力预测误差值基本在15%以内,验证了该模型能有效地预报凸曲面模具拼接区域球头铣刀的瞬态铣削力。 相似文献
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球头铣刀三维曲面加工的铣削力预报 总被引:1,自引:0,他引:1
针对球头铣刀三维曲面加工,提出一种考虑进给方向和刀具切触界面任意变化的铣削力预报方法。基于微分的思想,将曲面加工中单个齿频周期内的切削过程看成是切削条件恒定的微小稳态加工,进而将整个三维曲面加工视为一系列微小稳态加工的组合。根据各微小稳态加工的始、末刀位点坐标,建立进给转向角和进给倾斜角模型,刀具切触界面应用基于逻辑数组的Zmap方法确定,并修改了未变形切屑厚度模型的参数,使其适应三维曲面加工中刀具切触界面和进给方向的任意变化。分别进行凸圆弧曲面、凹圆弧曲面和自由曲面三个铣削加工试验,数值计算及试验测量结果表明,提出的方法能够很好地描述曲面加工中进给方向及刀具切触界面的变化,预报的铣削力和试验测量结果在幅值和变化趋势上都吻合良好,从而验证了该铣削力预报方法的有效性。 相似文献
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常规的铣削加工工艺在工艺规划中具有不确定性,影响工艺质量。针对铣削加工工艺的质量问题,研究人员设计了多种加工工艺。基于NSGA-Ⅱ的多轴铣削加工工艺,与基于切削稳定性与表面质量约束的多轴铣削加工工艺的应用较为广泛。因此,设计了复杂曲面零件超精密多轴铣削加工工艺。选择小楔角铣削加工刀具,选用0°前角作为刀具楔角,结合刀柄结构缩小回转半径,实现铣削刀切削稳定的目标。规划复杂曲面零件超精密多轴铣削走刀轨迹,将多轴轮廓铣的刀轴位姿与投影方向进行调整,在复杂曲面零件表面生成光滑轨迹,确保铣削加工质量。采用仿真实验,验证了该工艺的铣削质量更佳。 相似文献
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Hendriko Hendriko Gandjar Kiswanto Jos Istiyanto Emmanuel Duc 《Machining Science and Technology》2018,22(1):163-179
A simulation system was developed that deals with cut geometry and machining forces when a toroidal cutter is used during semifinishing in five-axis milling. The cut geometry was calculated using an analytical method called analytical boundary simulation (ABS). ABS was implemented to calculate the cut geometry when the machining used an inclination angle and a screw angle. The effect of tool orientation on the cut geometry was analyzed. The accuracy of the proposed method was verified by comparing the cut lengths calculated using ABS with cuts obtained experimentally. The result indicated that the method was accurate. ABS was subsequently applied to support a cutting force prediction model. A validation test showed that there was a good agreement with the cutting force generated experimentally. 相似文献
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The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milling process, it is necessary to incorporate the cutter runout parameters into the prediction model of cutting forces. However, the determination of cutter runout parameters is still a challenge task until now. In this paper, cutting process geometry models, such as uncut chip thickness and pitch angle, are established based on the true trajectory of the cutting edge considering the cutter runout effect. A new algorithm is then presented to compute the cutter runout parameters for flat-end mill utilizing the sampled data of cutting forces and derived process geometry parameters. Further, three-axis and five-axis milling experiments were conducted on a machining centre, and resulting cutting forces were sampled by a three-component dynamometer. After computing the corresponding cutter runout parameters, cutter forces are simulated embracing the cutter runout parameters obtained from the proposed algorithm. The predicted cutting forces show good agreements with the sampled data both in magnitude and shape, which validates the feasibility and effectivity of the proposed new algorithm of determining cutter runout parameters and the new way to accurately predict cutting forces. The proposed method for computing the cutter runout parameters provides the significant references for the cutting force prediction in the cutting process. 相似文献
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虚拟制造中基于刀具变形的复杂曲面加工误差预报 总被引:1,自引:0,他引:1
复杂曲面加工过程中刀具的弹性变形是产生曲面加工误差的重要原始误差。着重研究了虚拟制造环境下基于球面铣刀弹性变形的曲面加工误差预报模型。研究并建立了球面铣刀加工复杂曲面的切削力模型和刀具弹性变形模型,在此基础上,分析了曲面生成机理,提出了利用曲面变形敏感系数建立刀具弹性变形对法向加工误差的影响关系。利用该模型可以在实际切削加工前对曲面加工误差进行预报,用以进行误差补偿或切削参数优化。最后,以二维半圆形拉伸曲面为例通过切削实验对本文提出的模型进行了验证。 相似文献
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高硬度合金材料因其较高的比强度、优异的耐腐蚀和耐热性能,广泛应用于各个领域。但在实际加工过程中,由于热导系数低、弹性模量小、单位面积切削力大、刀-屑接触面积小等特性,其加工一度成为研究的难点与热点。从传统铣削和微铣削的不同加工机理出发,对高硬度合金材料铣削力建模并进行探讨。阐述了铣削力系数、铣削速度、刀刃圆弧半径、刀具跳动和挠性变形对铣削力预测的影响,分析了高硬度合金材料铣削力预测中的一些热点与难点以及目前铣削力建模存在的问题。 相似文献
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钛合金型腔圆角加工容易发生切削负载增大和颤振等现象,导致圆角表面质量较差,难以实现钛合金高效加工。通过钛合金型腔圆角铣削试验,基于铣削力和圆角表面质量检测,分析内圆角铣削特征和原理,并优化铣削参数。试验表明:采用小切削宽度的高速加工,可实现钛合金内圆角的高效加工;在Vc=90m/min,ft=0.06mm/t,ap=20mm,ae=1mm切削参数组合下,切削力相对较小,加工效率高,切削表面质量高。 相似文献
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切削力预测是制定与优化加工工艺的重要环节。针对曲线端铣加工过程,提出一种基于斜角切削的切削力建模方法。将刀具沿轴向微分,以曲线微分几何计算微元刃上的工作基面。在微元刃的工作法平面参考系中,应用最小能量原理,构建微元刃中力矢量、速度矢量、流屑角、法向摩擦角、法向剪切角及剪应力等切削参数之间的约束。以单齿直线铣削试验对切削参数进行标定,其中法向摩擦角、法向剪切角及剪应力等可表示为瞬时未变形切屑厚度的函数。选取高强度钢PCrNi3MoVA试件,分别进行圆弧和Bézier曲线端铣加工试验。试验结果表明,曲线端铣时切削力的变化与瞬时进给方向和曲线曲率相关。切削力预测值的幅值大小和变化趋势与试验值一致,验证了该切削力建模方法的有效性。 相似文献
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Z. C. Wei M. L. Guo M. J. Wang S. Q. Li J. Wang 《Machining Science and Technology》2013,17(5):688-711
AbstractThe force prediction is the precondition of improving equipment utilization ratio and optimizing process for CNC machining. Cutter-workpiece engagement (CWE) and in-cut cutting edge (ICCE) are the keys. In this article, a new analytic method of CWE and ICCE is proposed for ball end milling of sculptured surface and the prediction model of milling force is established. The sculptured surface is discretized into a series of infinitesimal inclined planes corresponding to cutter location points. The geometry relationships of cutter axis, feed direction and inclined plane are defined parametrically. The boundary curves and the boundary inflection points of the CWE are obtained by intersecting spatial standard curved surfaces with rotation transformation of coordinate system. The effective intersection points of the CWE and the cutter edge curve in Xc-Yctwo-dimensional plane are the upper and lower boundary points of ICCE. Based on the instantaneous chip thickness considering arbitrary feed direction, the force prediction model for ball end mill of three-axis surface milling is established. Simulation and experiment show that CWE and ICCE calculated by analytic method are well consistent with those of solid method. The predicted cutting forces match well with the measurements both in magnitude and variation trend. 相似文献