圆柱齿轮滚齿加工三向Dexel模型仿真与验证

针对基于实体建模技术的滚齿加工仿真问题,开发一种圆柱齿轮滚齿加工三向Dexel模型仿真方法。研究圆柱齿轮滚齿加工的运动学模型。根据滚刀和齿轮毛坯的几何参数创建三角形网格模型,并转换为引擎内的Dexel模型。同时,借助Delaunay三角剖分和Alpha形状重构进行高效的CWE计算和未变形切屑几何仿真。采用斜角切削模型来计算每个时间步上所有啮合节点的力分布。使用利勃海尔LC500滚齿机对所提仿真方法进行了验证,并结合旋转测力计和卡尔曼滤波器来补偿结构动力学,从而进行准确的切削力测量。结果表明：所提方法能够准确预测出沿滚刀刃口离散节点的三维力分布,预测误差（均方根和标准差）在4%~12%之间,且当切削条件变化时,仍然可以准确预测轴向和横向的切削力,有助于进一步提高滚齿加工仿真的效率与精度。     

An experimental method for studies of intermittent cutting at small cutting depths

Most devices for metal cutting experiments are designed to simulate continuous cutting at relatively large cutting depths. However, there is also a need for techniques to study the more complex situations prevailing in other important cutting operations like milling, sawing, hobbing, shaper cutting and grinding. These operations are characterized as being intermittent and having a relatively small and varying cutting depth per edge. In order to supply an experimental set-up for basic studies of chip formation and cutting forces under these conditions a new method for single stroke, single edge metal cutting has been developed.

The experiments are performed in a modified Charpy pendulum which offers force measurement and accurate selection of cutting speed and feed in the ranges typical of many intermittent cutting operations. The equipment is also provided with an excellent quick-stop mechanism to aid in chip formation studies.

The test method is described in detail and examples of metallographical and scanning electron microscopical studies of quick-stopped samples as well as registrations of specific thrust and cutting forces are presented.     

高速干式滚齿加工及其关键技术

介绍了干式滚齿的产生和现状;归纳了干切削理论及其研究内容;重点从机床、刀具和工艺3个方面对高速干式滚齿加工的关键技术及其解决方案进行了分析和探索.研究表明:干态高速滚齿的顺利进行,需要在切削理论上的全面突破,以及刀具、机床和工艺技术的综合改进.     

High speed temperature measurement in gear hobbing: Part I—design,concept and physical operation mode of the infrared-camera

Gear hobbing is the major technology to manufacture external gears. The motions of the tool and workpiece are dynamically linked. Therefore it is difficult to apply external measurement devices in the process. Especially the temperature, which is a vital factor to determine the load on the cutting edge, cannot be measured as easy as in other processes (for example turning). Suitable infrared-cameras are not commercially available, because these do not meet the demands for temporal and geometrical resolutions. Furthermore, commercial equipment has to be calibrated for each individual temperature (above 350 °C). This forced the Institute of Manufacturing Technology and Quality Management to develop an own measuring device. This camera is able to measure the temperature of the cutting surface within the gear hobbing process. Despite focusing the usage of the camera on hobbing in this paper, it can also be used to monitor further highly dynamical machining processes with discontinuous cutting conditions. This paper is divided into two parts. The first part describes the set-up, the concept and the physical and optical basics of the IR-camera. In the second part, the experimental realisation and the results of trials during an analogy test of the hobbing process are presented.     

Development of a new rapid characterization method of hob's wear resistance in gear manufacturing—Application to the evaluation of various cutting edge preparations in high speed dry gear hobbing

Gear hobbing remains a cutting technology mainly dedicated to large-scale productions of gears for the automotive industry. The improvements in hobbing tool design are problematic due to the very long duration of wear tests and due to the application of special machine tools only available in production plants. In order to overcome these limitations and to accelerate the efficiency of the investigations, a new rapid testing method called “flute hobbing” has been developed on a standard five-axes milling machine widely present in research laboratories. This testing method has been associated with a software providing the geometry of each chip in hobbing. The correlation of the chip geometry with the wear of each tooth enables to discriminate the critical teeth of a hob in order to focus the development in this area of the cutting zone. This new methodology has been used to investigate the influence of the cutting edge preparation on the wear resistance of gear hobs made of PM-HSS in the context of dry high speed manufacturing. The application of the AFM technology to generate defined edge preparation has shown its efficiency to improve the tool wear resistance and has confirmed previous results.     

Exploratory investigation of chip formation and surface integrity in ultra-high-speed gear hobbing

Gear hobbing is widely employed to manufacture automotive gears, where the productivity depends on the cutting speed. Currently, gear hobbing is performed at ～300 m/min using high-speed steel hob cutters. In this study, ultra-high-speed gear hobbing was attempted using a large-diameter cemented carbide hob cutter on a gear grinder. This enabled a cutting speed up to 2450 m/min. Many interesting phenomena were acquired in this speed range. Chips were severely oxidized, whereas the gear surface was not affected. Compressive residual stress was generated at the gear surfaces with low surface roughness and high hardness, while the wear of hob cutter was insignificant.     

滚齿机挂轮快速计算研究

针对在滚齿机上滚切圆拄齿轮的滚切原理及调整计算，建立了滚切圆柱齿轮传动比计算模型，并实现了用计算机进行辅助计算选择滚齿机的挂轮，将分齿挂轮和差动挂轮联合在一起计算。本程序自动识别齿轮类型、选择相应的调整计算公式来计算分齿挂轮和差动挂轮的传动比并选择出最高精度的挂轮，方便实用。     

An improved process simulation system for ball-end milling of sculptured surfaces

A simulation system is developed in this paper, which deals with the geometry and mechanics of machining with ball-end milling cutters. The geometry of the workpiece, the cutter, and the cutter/workpiece engagement is modeled using a geometric simulation system. This module uses a commercial solid modeler (ACIS) as a geometric engine and automatically extracts the critical geometric information required for the physical simulation system. To calculate the instantaneous cutting forces, a new mechanistic force model is developed. This force model takes into account the variations of the cutting coefficients along the cutting edge, and considers the variations of the rake angle and the chip flow direction on the rake face. The calibration of the developed model is performed for half-immersion ball-end milling operation. The applicability of the developed system is verified experimentally for various up-hill angles. It is shown that as the up-hill angle increases, the ball-nose tip engagement decreases which in turn significantly affects the magnitude of the resultant forces. Also, lower cutting forces and powers are experienced if cutting with the vicinity of the tool tip is avoided.     

Chip geometry and cutting forces in gear power skiving

This paper describes a new virtual model for predicting the uncut chip geometry and cutting forces in power skiving, which is a high-speed, versatile gear cutting process. The developed kinematic model is applied in a dexel-based solid modeling engine to extract three-dimensional uncut chip geometry, from which the two-dimensional cross section is obtained via Delaunay triangulation. Cutting velocities along discretized cutter edges are calculated and used to determine the effective rake and oblique angles. Then, force predictions are made using the oblique cutting model and validated using measurements from power skiving trials performed on a DMG MORI NT5400DCG mill-turn machine.     

汽车齿轮车削和滚齿复合机床研究

根据汽车行业对高精度齿轮的需求,通过自主创新的途径,重点攻克了车削和滚齿复合机床总体结构、机床数控系统、高速干式滚切工艺系统温度场控制、硬质合金高速干切滚刀等关键技术难题,研发一种汽车齿轮高精度高速车削和滚齿复合机床。机床采用基于运动控制卡的开放式数控系统,采用3种方法减少滚齿加工机床热误差变形,采用三合一组合齿轮加工刀具。将齿轮加工的全部工艺集成在一台机床内,能通过一次装夹完成车削、滚齿和去毛刺加工。由于节省了上下料时间,生产效益得到了很大的提高,实现了齿轮滚切高效、高精度、节能环保加工。     

滚齿机床振动对齿轮几何精度的影响

滚齿机床切削加工过程中,刀刃成排轮流从切入到切出,切削力由小逐渐变大,再逐渐变小,在工件和刀具之间产生周期性的激振力,使刀刃和工件加工表面产生相对位移,对加工齿轮的几何精度产生影响。研究机床结构振动与被加工齿轮精度的关系,建立滚刀和工件加工表面产生的相对位移对齿轮几何精度影响的理论模型,定量推导出了由此相对位移产生的齿廓误差;通过大量实验,对滚刀和工件加工表面产生相对位移对应的齿轮齿廓误差进行在线精密测量;使用此齿廓误差减法运算新方法,对两组实验数据进行对比分析。结果表明:提出的运算新方法能够准确地处理数据,实验数据很好地验证了建立的理论模型的正确性,误差小于2%。     

Prognosis of the local tool wear in gear finish hobbing

Gear finish hobbing is a method for soft finishing of external cylindrical power transmission gears. The application of this process is required when the process chain of gear production is to be set up completely free of coolant. Since this finishing technology is relatively new, there is some practical experience, but no fundamental knowledge regarding economical process design. One challenge in process design is that unbalanced tool wear typically leads to geometrical deviations of the machined gear profile. The aim of the investigations described in this paper is to develop a wear model which is capable to predict the local tool wear of gear finish hobbing tools. This model is based on analogy cutting trials and geometrical analyses of the chip geometries in gear finish hobbing. The results of the model are validated by fly-cutting trials with different local loads on the tool. The validation shows that an optimization of the local tool wear development can be achieved by means of the prediction model. Therefore, an optimization of the technological process parameters can be carried out based on this model to reach an efficient process design.     

基于自适应控制技术的铣削参数优化

采用BP神经网络算法应用于铣齿功率建模能较准确地预测铣齿功率大小,进而运用STATISTICA的正交设计优化试验数据对滚齿机进行再制造,通过在主轴箱加设传感器实现了机床振动稳定性的的在线监控,分析各个切削状态下主轴箱振动同铣削功率的关系,进行优化切削参数,实现了数控系统与在线监控技术的自适应闭环监控.完成了4m大型滚齿机向高速铣齿机床SKX-4000的智能化再制造.结果表明,采用的控制策略能适应强力铣削的工况变化,稳定地控制加工过程,达到保护机床、刀具和提高加工效率的目的.     

Modeling of process forces with consideration of tool wear for machining of sintered steel alloy for application to valve seat in a combustion engine

The reliable and precise machining of cylinder head components in the combustion engine represents a crucial and complicated step in the production process. In industrial manufacturing processes, disturbances are inevitable and provide a measure of uncertainty in each production step. Increasingly, the influence of such uncertainties is being evaluated using simulation models. To determine the performance quality of the model, a suitable cutting material and the edge geometry must be identified. In this paper, experimental investigation of polycrystalline cubic boron nitride grades for machining valve seats made of powder metallurgy steel in a combustion engine is presented. Then, a mechanistic approach is used to establish a prediction model of the process forces based on the experimentally determined data set.     

单轴传动滚切式双边剪薄钢板剪后“错牙”及“飞边”的原因分析与对策

针对单轴传动滚切式双边剪生产过程中出现的薄钢板经双边剪剪后出现“错牙”及“飞边”的问题,从多个方面入手对薄钢板出现“错牙”及“飞边”的原因进行了分析对比,提出了相应的解决方案,对今后滚切式双边剪的设计、制造及安装调试有借鉴和参考价值。     

圆柱齿轮展成拉齿工艺研究

针对圆柱齿轮传统滚齿、铣齿加工效率偏低的问题,提出了展成拉齿加工的工艺方案,介绍了工艺方案的专用刀具、展成切削原理及其加工效率的计算方法,从理论上分析了该工艺的优越性;例举了双齿条分度机构改装方案,客观论证了圆柱齿轮展成拉齿加工工艺的可行性和可靠性.     

Real-time estimation of cutting forces via physics-inspired data-driven model

A method is presented to estimate the cutting forces in real time within machine tools for any spindle speed, force profile, tool type, and cutting conditions. Before cutting, a metrology suite and instrumented tool holder are used to induce magnetic forces during spindle rotation, while on-machine vibrations, magnetic forces, and error motions are measured for various combinations of speeds and forces. A physics-inspired data-driven model then relates the measured accelerations to the magnetic forces, such that during cutting, on-machine measured vibrations are used in the model to estimate the cutting forces in real time.     

Modelling and simulation of micro-milling cutting forces

The paper presents a new approach for predicting micro-milling cutting forces using the finite element method (FEM). The trajectory of the tool and the uncut chip thickness for different micro-milling parameters (cutting tool radius, feed rate, spindle angular velocity and number of flutes) are determined and used for predicting the cutting forces in micro-milling. The run-out effect is also taken into account. An orthogonal FE model is developed. A number of FE analyses (FEA) are performed at different uncut chip thicknesses (0–20 μm) and velocities (104.7–4723 mm/s) for AISI 4340 steel. Based on the FE results, the relationship between the cutting forces, uncut chip thickness and cutting velocity has been described by a non-linear equation proposed by the authors. The suggested equation describes the ploughing and shearing dominant cutting forces. The micro-milling cutting forces have been determined by using the predicted forces from the orthogonal cutting FE model and the calculated uncut chip thickness. Different feed rates and spindle angular velocities have been investigated and compared with experimentally obtained results. The predicted and the measured forces are in very good agreement.     

Prediction of micro-milling forces with finite element method

This paper presents the prediction of micro-milling forces using cutting force coefficients evaluated from the finite element (FE) simulations. First an FE model of orthogonal micro-cutting with a round cutting edge is developed for Brass 260. The simulated cutting forces are compared against the experimental results obtained from turning tests. The cutting force coefficients are identified from a series of FE simulations at a range of cutting edge radii and chip loads. The identified cutting force coefficients are used to simulate micro-milling forces considering the tool trajectory, run-out and the dynamometer dynamics. The same process is also simulated with a slip-line field based model. FE and slip-line field based simulation results are compared against the experimentally measured turning and micro-milling forces.     

Improved modelling of cutting force coefficients in peripheral milling

Titanium is one of the most widely used metals in the aircraft and turbine manufacturing industries. Accurate prediction of cutting forces is important in controlling the dimensional accuracy of thin walled aerospace components. In this paper, a general three-dimensional mechanistic model for peripheral milling processes is presented. The effects of chip thickness, rake angle and cutting geometry on chip flow, rake face friction and pressure, and cutting forces are analyzed. A set of closed form expressions with experimentally estimated cutting force factors are presented for the prediction of cutting forces. The model is verified experimentally in the peripheral milling of a titanium alloy. For a given set of cutting conditions and tool geometry, the model predicts the cutting forces accurately for the chip thickness and rake angle ranges tested.