AutoCAD二次开发程序设计中圆弧连接方法的研究

圆弧连接的本质就是使圆弧与直线或圆弧与圆弧相切,在此研究了基于AutoCAD二次开发的圆弧连接程序化绘制方法,用VisualLISP语言编程建立了圆弧连接通用绘图程序。     

螺杆转子齿形中圆弧—圆弧包络线啮合副的研究

圆弧-圆弧包络线是螺杆转子中应用最广泛的基本组成段。阐述了圆弧-圆弧包络线的生成原理,分别采用几何法和基于齿廓法线法的解析法,推导出圆弧-圆弧包络线啮合副的型线方程及其啮合线方程,并以SRM圆弧对称齿形、SRM-D齿形等为例,展示了各种圆弧-圆弧包络线啮合副的典型组合及其改进过程,为转子型线的后续演化提供参考。     

椭圆加工中的圆弧拟合及加减速算法研究

很多数控机床不支持椭圆插补,因此椭圆加工一般采用圆弧拟合的方法转换成圆弧加工.采用椭圆的最优四圆弧逼近拟合算法,用数字积分法(DDA)进行圆弧插补.用小段割线拟合圆弧起点和终点的小段圆弧,将圆弧的加减速控制转换成直线的加减速控制,解决了DDA圆弧插补的加减速控制难题.     

圆锥滚子轴承套圈装配倒角的设计

介绍了纯圆弧、斜边+圆弧+斜边、小圆弧+大圆弧+斜边3种装配倒角形式,对比分析了各自的特点,认为小圆弧+大圆弧+斜边倒角是目前最适宜的装配倒角形式;并结合数学推导介绍了小圆弧+大圆弧+斜边装配倒角的设计方法及其车加工装配倒角坐标尺寸的计算方法。     

双圆弧齿轮

双圆弧齿轮是单圆弧齿轮的一项新发展,它与单圆弧齿轮相比,具有承载能力高,使用寿命长,传动噪音小,加工工艺装备简单等优点,因此是一项有发展前途的新型齿轮传动。一、双圆弧齿轮基本概念圆弧齿轮可以看成一段圆弧(母圆)沿着圆柱面上螺旋线(准线)运动而形成的圆弧螺旋曲面。母圆在法面内称为法面圆弧齿轮;     

六圆弧齿廓螺旋齿轮及其啮合特性北大核心

提出了一种新齿廓螺旋齿轮,称为六圆弧齿廓齿轮。与双圆弧螺旋齿轮单侧齿廓的两个工作圆弧相比,该齿轮单侧齿廓有六个工作圆弧,其中三个凸圆弧位于节线以上,三个凹圆弧位于节线以下,每两段工作圆弧之间都通过过渡圆弧连接。通过计算同一齿廓上六个啮合点之间的轴向距离,推导出了六圆弧螺旋齿轮的多点啮合系数、多对齿啮合系数以及合理齿宽的选择等,为后续六圆弧螺旋齿轮啮合特性的计算提供了方便。     

内圆弧的几种测量方法

在装配生产过程中,内圆弧的测量给测量工作带来诸多不便,通常利用百分表或卡钳来测量,尤其对该圆弧面经过刮研后,另一部件圆弧面与该圆弧面配合使用,而另一部件圆弧面的实际尺寸根据该圆弧面的实测尺寸而定,对于这种圆弧面利用卡钳或百分表测量非常不便,而下面几种测量方法比较简便。     

修磨圆弧铣刀

在修磨圆弧铣刀时,可根据圆弧铣刀的使用情况来分析刀具的磨损。一般来说,圆弧铣刀用外圆切削刃切削的情况比较少见,主要集中在圆弧切削刃上,所以刀具磨损严重的部位在圆弧切削刃上。而外圆切削刃可作为圆弧切削刃的后备部分,所以修磨圆弧刃铣刀实际就是修磨圆弧刃的R圆弧切削刃处的前角、后角,使之重新变得锋利,而对外圆部分是不需要进行修磨的。因此在修磨圆弧铣刀时应做好以下几点。     

六圆弧齿廓螺旋齿轮及其啮合特性

提出了一种新齿廓螺旋齿轮,称为六圆弧齿廓齿轮。与双圆弧螺旋齿轮单侧齿廓的两个工作圆弧相比,该齿轮单侧齿廓有六个工作圆弧,其中三个凸圆弧位于节线以上,三个凹圆弧位于节线以下,每两段工作圆弧之间都通过过渡圆弧连接。通过计算同一齿廓上六个啮合点之间的轴向距离,推导出了六圆弧螺旋齿轮的多点啮合系数、多对齿啮合系数以及合理齿宽的选择等,为后续六圆弧螺旋齿轮啮合特性的计算提供了方便。     

涡旋压缩机非对称单圆弧修正方法

为了提高涡旋压缩机排量,提出了一种涡旋齿型线的非对称单圆弧修正方法。阐述了修正圆弧的生成方法,建立了修正圆弧方程,证明了修正圆弧能实现完全啮合,推导了不同修正展角下排气体积计算公式,对比分析了采用单圆弧修正和双圆弧修正时涡旋压缩机的排气体积和排量。研究结果表明,与对称双圆弧修正方法相比,非对称单圆弧修正方法在同等修正展角下提高了涡旋压缩机排气体积,同等排气温度下提高了涡旋压缩机排量。非对称单圆弧修正方法为大排量涡旋压缩机的设计提供了参考。     

基于周期平均值外特性的脉冲MIG焊弧长稳定性研究

通过对脉冲熔化极惰性气体保护(Metal inert gas,MIG)焊脉冲平均电流电压变化率的计算,提出脉冲周期平均值外特性曲线,并对弧焊电源脉冲周期平均值外特性曲线和电弧静态性曲线的动态稳定工作点进行详细分析,得出利用脉冲平均值外特性控制脉冲MIG焊的控制策略。同时运用双闭环控制实现了基于弧压反馈的I/I模式控制数字化弧焊电源,此电源能在送丝速度稳定情况下自适应弧长扰动变化,实现脉冲弧焊过程一脉一滴熔滴过渡。通过弧长阶跃试验表明,脉冲弧焊过程中焊丝熔化速度快速跟踪弧长变化,具有良好的弧长动态调节性能,保持弧长动态稳定,即焊接过程稳定,焊缝成形良好,同时验证了分析过程正确性和设计过程的可行性。     

Real-time control of welding penetration during robotic GTAW dynamical process by audio sensing of arc length

This paper presents a new technology of real-time arc length monitoring and sag-depression prediction through arc sound signal, which is essential to realize the welding penetration control during gas tungsten arc welding of arc length. A set of automatic measurement and control system have been proposed to achieve real-time arc length control via audio sensing system. After preprocessing of arc sound signal, the piecewise linear models of arc sound signal were established under two different arc length variation 3–4 and 4–5–6 mm, analyzing the prediction errors of linear model, which were proved to be good enough for online monitoring of arc length in pulse GTAW. Based on the linear relationship between arc sound and arc length, the linear fitting model was implemented on predicting the surface height of weld pool. A segmented self-adaptive PID controller was proposed to achieve the monitoring and controlling of arc length;, the confirmatory experiments have been designed to test the control effect of arc-length monitoring based on arc sound signal.     

双钨极间接气体保护焊接电弧的数值模拟

间接电弧焊接是一种新型的焊接方法,具有高效、节能、焊接应力和变形小的优点。为了研究间接电弧的电弧参数的分布特点以及这种焊接方法热输入低的根本原因,利用有限元分析软件,建立双钨极间接电弧的三维有限元数学模型,计算得到双钨极间接电弧的温度、等离子体流速、电弧压力以及热流密度分布等特征参数;通过高速摄像拍摄到的电弧形态照片与计算得到的温度云图对比验证模拟结果的可信性。结果表明双钨极间接电弧面对称且向阳极方向偏转,呈上宽下窄的倒钟罩形态,阳极一侧的各项特征参数大于阴极一侧;与惰性气体钨极保护(Tungsten inert gas arc, TIG)焊接和等离子弧焊接相比,双钨极间接电弧被焊接工件不接电极,主要靠热流密度、等离子体流速、电弧压力等参数都比较低的弧柱区端部加热,造成工件焊接热输入低、熔深浅。     

Numerical analysis of arc characteristics in two-electrode GTAW

A two-dimensional numerical model is developed to describe the arc characteristics in two-electrode gas tungsten arc welding. The influence of different welding current, shielding gas, and shielding gas flow rate is investigated. The arc characteristics are analyzed by studying the distributions of physical quantities including arc temperature, electric potential, and total heat flux on the workpiece. The simulated results reveal that a higher arc temperature value is obtained in helium arc than in argon arc. For obtaining high arc temperature, there is an optimum range for shielding gas flow rate and too high or too low is not appropriate. In addition, the increase of welding current results in the increase of the maximum arc temperature, electric potential, and total heat flux. To validate the accuracy of simulated results, welding experiments are performed and the arc temperature is calculated by the spectral signal of arc plasma. The simulated results are compared with the experimental ones and there is a good agreement.     

使用对数算法的圆弧插补法

提出一种采用对数算法的圆弧插科方法，插补软件利用ＭＣＳ—５１汇编语言编制，算法简捷、精度高、实时性强。并对圆弧插补法的误差进行了分析。     

The acquisition and processing of real-time information for height tracking of robotic GTAW process by arc sensor

Aiming at the deficiencies of the vision technology that canot be used in the height tracking of the 3D weld seam during teaching-playback robot gas tungsten argon welding (GTAW) process, this paper designed a set of arc sensor system for height tracking of weld seam, which can effectively acquire arc voltage signals. The characteristic values of arc voltage signals are extracted and a linear relational model between arc voltage and arc length was established by using appropriate denoising algorithm. The experimental results demonstrate that the error between the arc length calculated by linear model and the real arc length was very small, which is accurate enough to meet the requirements of the follow-up height tracking and controlling during the welding robot GTAW process.     

Study on arc characteristics and their influences on weld bead geometry in narrow gap GMAW of 5083 Al-alloy

As an efficient process, narrow gap gas metal arc welding (NG-GMAW) was employed to join thick plates of 5083 Al-alloy. In this paper, arc characteristics in NG-GMAW of 5083 Al-alloy and their influence on the weld bead geometry were studied with synchronous acquisition system for various groove types, welding modes, welding current levels, and swing frequencies. The arc profiles were measured and appear to be entirely different compared with that in bead-on-plate GMAW process, meanwhile the arc size changes with varied welding mode, welding current, and arc swing frequency. Arc characteristics highly affect the weld bead geometrical parameters such as bead width, welding penetration, sidewall penetration, and weld surface concavity. Linear regressions were made between the arc characteristics and the weld bead geometrical parameters both in swing and non-swing arc process. It showed that a negative linear correlation exists between welding penetration and arc length, sidewall penetration, and arc warpage, while a positive linear correlation exists between weld surface concavity and arc warpage in non-swing arc process. In contrast, a non-linear correlation exists among them and the variation tendency remains the same in swing arc process.     

金刚石刀具刀尖圆弧波纹度的测量及评价

为实现金刚石刀具刀尖圆弧波纹度超精密测量,构建了基于原子力显微镜(AFM)和精密回转轴系的刀尖圆弧轮廓测量系统,研究了刀尖圆弧波纹度评价方法和控制测量系统引入误差的策略。提出了评价刀尖圆弧波纹度时截止波长的确定原则和方法,并介绍了刀尖圆弧波纹度测量原理及评价流程。讨论了精密回转轴系径向回转误差的测量和评定、刀具安装偏心和偏角误差的控制和原子力扫描系统Z向非线性误差的校准方法。最后,在构建的测量系统上测量了了金刚石刀具刀尖圆弧波纹度并对测量不确定度进行了分析。实验测量显示:所评价金刚石刀具的刀尖圆弧波纹度为0.106μm,测量不确定度为23.8nm,表明所构建的测量系统基本满足金刚石刀具刀尖圆弧波纹度纳米级测量及评价的需求,测量结果稳定可靠、精度高。     

用于电弧发射光谱的数字化自动引弧电路设计

转盘电极发射光谱分析技术在油液成分检测中有重要应用,研究表明,电弧光源的稳定性对光谱分析的结果有重要影响,传统的电弧发生器多使用火花放电器作为引弧电路的核心器件,在油液成分分析中引弧的稳定性和可靠性难以保证.文章提出了一种用于电弧光源激发的数字化自动引弧电路,建立了高频引弧电路拓扑结构模型,使用双路可控硅代替火花放电器...