A 3D chip geometry driven predictive method for heat-loading performance of hob tooth in high-speed dry hobbing

High-speed dry hobbing is an emerging green technique for gear hobbing owing to its high productivity and environmental friendliness. However, severe friction occurs and heat instantaneously accumulates in the cutting region due to the adoption of high cutting speed and the lack of metalworking fluids, which causes serious hob wear. This investigation is concerned with the thermal performance and heat-loading quantitative method of hob cutter in high-speed dry hobbing. According to the multiple-edge and intermittent cutting behavior, the temporal dynamic characteristics of hob cutter are analyzed. Based on the complex 3D chip geometry produced in high-speed dry hobbing, the calculation method for heat-production (the amount of generated cutting heat) of hob tooth is proposed. Considering the coupling effects of heat conduction, heat convection, and heat radiation, the prediction model for heat-loading quantity (the bearing capacity of cutting heat) of hob tooth is developed. With the help of the developed method, the interrelation between the thermal performance of hob cutter and material removal volume, cutting conditions, coating material, respectively, are investigated. The predictive method developed in this work provides a methodology for process parameter optimization and hob cutter manufacturing of high-speed dry hobbing.     

精磨双凸面蜗杆的一对螺旋蜗杆传动的计算机设计、啮合的形成和仿真(续)

作者们基于以下研究提出了精磨蜗杆的螺旋蜗杆传动的计算机设计和分析方法。1．滚刀的理论螺线表面是用一维面生成的。2．蜗杆表面与滚刀螺线表面相比齿廓和轴向为凸面。3．蜗杆的双凸面可局部承受接触和获得给定范围的传动误差的预先设计的抛物线函数。蜗杆传动的计算机设计可以显示和避免蜗杆齿面形成奇异点和齿棱。模拟双凸面蜗杆和蜗轮齿面的啮合和接触来确定支承接触轴线不对中和传动误差的影响。开发和应用数值解的计算机程序。数值计算实例说明所提供的开发原理。     

精磨双凸面蜗杆的一对螺旋蜗杆传动的计算机设计、啮合的形成和仿真

作者们基于以下研究提出了精磨杆的螺旋蜗杆传动的计算机设计和分析方法。1．滚刀的理论螺线表面是用一维面生成的。2．蜗杆表面与滚刀螺线表面相比齿廓和轴向为凸面。3．蜗杆的双凸面可局部承受接触和获得给定范围的传动误差的预先设计的抛物线函数。蜗杆传动的计算机设计可以显示和避免蜗杆齿面形成奇异点和齿棱。模拟双凸面蜗杆和蜗轮齿面的啮合和接触来确定支接触轴线不对和传动误差的影响,开发和应用了数值的计算机程序。数值计算实例说明所提供的开发原理。     

Design and simulation of meshing of new type of worm-gear drive with localized contacts

The design and simulation of meshing of a single enveloping worm-gear drive with modified surfaces is presented. Generally worm-gear is generated by the hob which is identical, to the worm. This process guarantees the conjugation between the worm and the gear but results in a line contact at every instant which is very sensitive to misalignment. The localization of bearing contact is necessary to reduce the sensitivity of the worm-gear drive to misalignment. Practically this localization is achieved by application of an oversized worm type hob to cut the worm-gear. The oversized hob approach is very practical and effective to localize bearing contact but can not provide the conjugation between the worm and the modified worm-gear. This work proposes an analytical procedure to make the worm surface conjugate to the worm-gear which is cut by the oversized hob. The developed computer program allows the investigation of the influence of misalignment on the shift of the bearing contact and the determination of the transmission errors, the contact ratio and the principle curvatures. The developed approach has been applied for ZK type of single-enveloping worm-gear drives and the developed theory is illustrated with a numerical example.     

圆柱齿轮滚切多刃断续切削空间成形模型及应用

滚切加工作为当前圆柱齿轮制造应用最为广泛的工艺具有高效但成形过程复杂的特点。基于展成原理,由规则分布在滚刀基本蜗杆螺旋面上的一系列切削刃相继从圆柱齿坯上切除材料,最终包络形成渐开线齿面。研究其成形原理可以为提升该工艺性能提供有效指导。针对齿轮滚切工艺过程多刃切削成形特征,建立圆柱齿轮滚切的空间成形模型。基于滚刀几何结构参数的理论约束关系,建立滚刀切削刃序列的参数方程;根据滚刀和工件的几何参数以及切削参数确定滚切过程中滚刀与工件的空间位置和运动关系,并基于空间运动学方法推导求得滚刀刀刃序列形成的空间成形曲面参数模型;采用离散数值方法获得滚切过程中的切屑几何形态及切屑厚度,并根据切屑几何计算各刀刃去除材料时的瞬时主切削力。该模型可以为滚切工艺参数优化、滚刀几何设计等研究提供支撑。     

采用标准齿轮滚刀加工蜗轮的方法研究

在没有涡轮滚刀的情况下，通过研究涡轮蜗杆与圆柱齿轮的啮合条件，以及涡轮蜗杆与圆柱齿轮间模数、压力角的关系，推导出一种使用标准齿轮滚刀近似加工蜗轮的方法。然后确定用标准齿轮滚刀加工的蜗轮与蜗杆能正确啮合的调整方法，该方法在实际中有很大的利用价值。     

Parametric analysis of the end face engagement worm gear

A novel specific type of worm drive, so-called end face engagement worm gear(EFEWD), is originally presented to minimize or overcome the gear backlash. Different factors, including the three different types, contact curves, tooth profile, lubrication angle and the induced normal curvature are taken into account to investigate the meshing characteristics and create the profile of a novel specific type of worm drive through mathematical models and theoretical analysis. The tooth of the worm wheel is very specific with the sine-shaped tooth which is located at the alveolus of the worm and the tooth profile of a worm is generated by the meshing movement of the worm wheel with the sine-shaped tooth, but just the end face of the worm(with three different typical meshing types) is adapted to meshing, and therefore an extraordinary manufacturing methods is used to generate the profile of the end face engagement worm. The research results indicates that the bearing contacts of the generated conjugate hourglass worm gear set are in line contacts, with certain advantages of no-backlash, high precision and high operating efficiency over other gears and gear systems besides the end face engagement worm gear drive may improve bearing contact, reduce the level of transmission errors and lessen the sensitivity to errors of alignment. Also, the end face engagement worm can be easily made with superior meshing and lubrication performance compared with the conventional techniques. In particular, the meshing and lubrication performance of the end face engagement worm gear by using the end face to meshing can be increased over 10% and 7%, respectively. This investigate is expect to provide a new insight on the design of the future no-backlash worm drive for industry.     

以蜗杆为母面的二次包络环面蜗杆传动

本文提出以蜗杆为母面，直接利用现有普通滚刀，在第一次包络时加工出蜗轮和蜗轮同开关的工具齿轮，实际只需加工出一个齿，做成沿螺旋线布刀的装配式刀具，这是一个更为经济而现有刀具不能加工的先进新方法。这种也能实现瞬时双线接触。     

齿轮磨前滚刀的齿形研究

介绍了磨前滚刀滚切齿轮的最大根切量和磨后的渐开线长度计算，并建立了数学模型。为更加直观起见，还建立了模拟滚齿的数学模型，并在实验的基础上提出了参考标准。     

Mathematical model and tooth surfaces of recess action worm gears with double-depth teeth

In this study, the surface equations of recess action (RA) worm gears with double-depth teeth, generated by a ZN worm-type hob cutter, are proposed. Based on the generation mechanism and the theory of gearing, a mathematical model of a series of worm gears, semi RA, full RA and standard proportional tooth types, with double-depth teeth is developed as the function of design parameters of the ZN worm-type hob cutter. According to the derived tooth surface equations, computer graphs of a series of worm gears with double-depth teeth are plotted. Tooth surface variations of the generated RA worm gears due to the varying pitch line, pressure angle and tooth height of the hob cutter are also investigated.     

EC-2硬齿面切削油及应用研究

本文介绍了在用硬质合金滚刀加工淬硬齿轮时,用EC-2硬齿面切削油,可显著减少刀具磨损,防止崩刃,从而提出刀具寿命和有利于提高齿轮表面质量。     

单齿飞刀连续分度加工平面齿蜗轮方法的研究

针对单角度盘铣刀加工平面蜗轮效率低等缺点，提出了一种用单齿飞刀连续分度加工平面齿蜗轮的方法。单齿飞刀制造方便，加工过程简单，连续分度的加工效率比单齿分度高。建立了飞刀直刃运动数学模型，分析了飞刀切得的齿面与理论齿面之间的关系，提出了飞刀安装倾角的求解方法。对于高精度平面蜗轮制造，该方法具有很高的应用价值。     

用齿轮滚刀加工蜗轮的误差分析

分析了采用代用齿轮滚刀加工蜗轮时产生的径向和轴向加工误差 ,提出按理论公法线长度加工蜗轮以减小误差的方法。     

滚刀和插齿刀切削过程的模拟

针对滚刀、插齿刀齿形及凸角齿形部分设计存在的问题 ,否定了原有传统理论认为的刀具切削刃交点在齿轮相应啮合线上只有一个对应点的论点 ,提出了新的设计理论。通过对切削加工中主要运动的研究 ,利用微机实现了对加工过程的模拟     

滚刀和插齿刀切削过程的模式

针对滚刀、插齿刀齿形及凸角齿形部分设计存在的问题,否定了原有传统理论认为的刀具切削刃交点在齿轮相应啮合线上只有一个对应点的论点,提出了新的设计理论.通过对切削加工中主要运动的研究,利用微机实现了对加工过程的模拟.     

涂层滚刀加工喷焊齿轮的试验研究

本文研究了用涂层滚刀加工镍基喷焊齿轮的试验结果。结果表明涂层滚刀的耐磨性和抗粘结能力有所提高,但刀具的磨损,特别是边界犁沟形式的磨损比较严重,复会涂层滚刀的磨损相对要小些。     

椭球形滚刀若干理论问题

介绍了一种加工内齿轮的新型刀具椭球形滚刀,首先论述了球形滚刀的局限性和椭球滚刀的优越性,然后就椭球形滚刀的基本参数,螺旋面方程和滚刀的螺旋线升角以及椭球形滚刀法向齿距误差和法向圆度误差等基本理论问题进行了论述,为设计和研究椭球形滚刀提供理论依据。     

AutoCAD2004环境下蜗轮滚刀的计算机辅助设计

以Visual C++6.0为开发环境进行编程计算,完成了蜗轮滚刀的参数化设计;用AutoCAD2004绘图软件提供的AutoLisp语言完成了蜗轮滚刀工程图的自动绘制,实现了蜗轮滚刀的计算机辅助设计。     

高速干切滚齿工艺系统切削热全过程传递模型

高速干切滚齿工艺消除了切削油/液的使用,是一种绿色高效的齿轮制造工艺。切削热伴随着高速干切滚齿工艺全过程且区别于传统湿式滚切工艺,是造成干切滚刀磨损和机床热变形的重要因素,直接影响制造成本和加工精度。根据干切滚刀周期性断续传热特性,综合考虑切削热在切屑、工件、干切滚刀、冷却介质以及滚齿机床加工空间的传递规律,提出将高速干切滚齿工艺系统切削热的发生与传递全过程划分为三个阶段的研究思想,从关系模型和热传递方程两个层面建立了高速干切滚齿工艺系统切削热全过程传热模型,包括切削接触界面热传递、切削区域热传递和机床加工空间热传递三个阶段的模型,然后基于工艺仿真试验对所建模型进行了应用研究,揭示了高速干切滚齿工艺系统的切削热在工件、干切滚刀、切屑中的动态变化规律,最后通过试验验证了模型的有效性。