基于电磁-热-结构耦合的船用曲轴红套工艺仿真

船用曲轴的红套工艺过程多采用感应加热方式对曲拐进行加热.针对加热过程电磁-热-结构多场耦合问题的复杂性,以某型号船用曲轴为参考对象,对加热过程进行数值模拟分析.在研究曲轴材料随温度变化的非线性物理特性基础上,在电磁场-温度场-应力场的顺序耦合过程中,加入温度场对电磁场的双向耦合分析,分析温度场对电磁场的反馈作用;归纳感应加热过程的电磁场、温度场及应力场的分布规律;对比研究曲拐加热时矩形加热器的相对位置、加热时间对曲拐的温度场分布的影响,确定曲拐加热后满足红套孔椭圆度要求的电流密度、电流频率、矩形加热器相对位置及加热时间等设计参数,为科学制定红套工艺提供有效参考.     

船用曲轴红套过程中线圈的结构改进及位置影响研究

针对曲轴感应加热后温度分布不均匀及形变不规则的问题,提出将电磁感应加热时的矩形线圈改为弧形线圈的方法。首先应用感应加热理论,建立了电磁场与温度场的数学模型;其次使用电磁-热-结构流程的顺序耦合法,对特定型号的船用曲轴进行电磁感应加热仿真,并与已有加热方式的仿真结果进行对比分析,同时考虑弧形线圈位置对曲柄内各场分布的影响;最后得到改进后曲柄孔周围温度差为12. 15℃,孔椭圆度为0. 29 mm,线圈与孔同心且半径为1 000mm时场分布最均匀的结论。通过对比改进加热线圈前后曲柄孔周围温度场与结构场的分布,证实电磁感应加热过程中曲柄孔周围变形不均的问题得到改善。     

半组合式曲轴感应加热过程的数值模拟

从麦克斯韦方程组和导热微分方程出发,导出了感应加热工件的电磁场、温度场分布基本方程;并以电磁场和温度场有限元分析为基础,建立了有限元分析模型.利用通用有限元软件ANSYS对大型半组合式船用曲轴红套感应加热过程进行仿真分析,得到了工件温度分布图,并通过实验进行了验证,为其红套工艺的制定提供了参考和依据.     

大型船用曲轴红套过程中的变形分析

红套是大型半组合式船用曲轴装配的工艺,其质量的好坏直接决定了后续精加工的精度。属于极端制造的范畴,难以用常规的实物物理方法对曲轴工艺过程进行研究。运用ANSYS软件有限元模拟仿真对曲臂热变形及应力进行了研究。应用了温度-结构耦合场分析进行建模,对红套接触性能进行了研究。并用实验验证了该套建模仿真方法的正确性和可行性。本论文对红套过程的研究,可以作为实际操作的理论依据,缩短曲轴生产周期,提高产品质量和生产效率。     

PC微机在曲轴热处理自动控制中的应用

一、工艺流程及PC控制原理曲轴是柴油机的一个重要零件。我厂的曲轴热处理工艺过程是通过中频感应器,通以8000Hz、600V电压、120A中频电流,使曲轴感应加热,然后喷水冷却。工艺员必须制订出最佳工艺参数,如加热功率、淬火液喷流量等参数。该曲轴热处理有三档加热、三档冷却     

感应加热线圈参数对被试件温度场的影响分析

针对感应线圈参数对感应加热温度场的影响问题,以ANSYS软件为工具,采用磁热耦合分析的方法,对不同参数水平条件下的电磁感应加热过程进行了有限元计算。运用仿真结果对比分析的方法,研究了感应线圈形状、与加热面间的距离、线圈铜管宽度以及铜管间距对感应加热温度场的影响规律。并以平板被试件为对象,设计了平板感应加热测温试验,对仿真结果进行了试验验证。研究结果表明,感应加热温度场高温区域的形状与线圈形状相似;线圈与加热面之间距离越小,加热温度幅值越大,但对温度分布基本无影响;铜管越细或铜管间距越小,加热最高温度越高,且高温区域向平板边缘移动。     

氮化镓MOCVD感应加热装置的优化设计

为了设计一款成本低、效率高的中频感应加热器样机,利用ANSYS软件对感应加热立式氮化镓MOCVD反应室建立2D模型。首先分别通过改变加热线圈与石墨基座下表面距离及线圈之间的间距,研究分析其改变对石墨盘表面温度均匀性分布的影响,热-电耦合分析结果表明减小线圈和石墨之间的垂直距离及线圈之间的距离可以提高加热效率,并根据仿真结果对感应加热器的结构进行优化设计,确定加热效果较好的加热器结构。结合仿真与分析结果,制作出一台感应加热器样机。实验验证可知,石墨盘表面温度浮动在0.2%,温度分布均匀性较好,符合工艺的要求,满足生产条件。     

风力发电机组主轴承加热设备的开发

对风电机组主轴承的加热方式及感应加热原理进行分析,结合实际需要加热轴承的结构特点和参数,采用线圈谐振加热方式开发了一套120 kW的智能化感应加热设备,详细介绍了该设备的电源功率、系统结构、控制系统等方面内容。240/900轴承的实际运行数据表明,该设备加热一套轴承仅需15 min,效率高且控温精准。     

微波密封器件无腐蚀感应钎焊工艺研究

通过对铝合金微波器件接头进行局部镀镍铜,选用双面有铜层的聚四氟覆铜板,实现了微波器件接头和聚四氟材料封盖的可钎焊性。采用优化的漏印网板添加焊膏,有效地控制了焊膏预置量,保证了钎焊缝的一致性。通过优化设计感应加热线圈,解决了矩形接头的感应加热温度场均匀一致性问题;通过对微波器件感应钎焊的工艺过程研究,获得了稳定的工艺参数。利用感应加热的快速、局部的优点,实现了微波密封器件局部快速钎焊。     

热疲劳试验用电磁感应线圈热效率分析

高频感应加热广泛应用在热疲劳试验中,感应线圈是感应加热装置的核心部件。线圈壁厚过薄会使线圈效率降低,壁厚过厚则使线圈发热严重,损坏线圈。对热疲劳试样的感应加热过程进行了数值模拟,发现:增大线圈壁厚能够提高试样加热的最高温度,线圈壁厚过厚时,线圈之间的邻近效应使得试样表面焦耳热分布带变窄,不能均匀透热加热区域。线圈壁厚在(0.3~0.5)mm时,线圈热效率较低,线圈壁厚为1.5mm时,线圈热效率最高,线圈壁厚超过2.5mm时,线圈热效率反而下降。该研究对于电磁感应加热线圈的设计具有一定的指导意义。     

Design and optimization of coil structure based on the uniformity of core temperature field

Coil structure size parameters during electromagnetic induction heating affect the temperature field and heating rate of a carbon fiber-reinforced polymer (CFRP) shell. In this study, a finite element analysis model is established on the basis of a single-screw coil structure, and the influence of coil diameter, length, turns, and position relationship on the temperature field distribution and heating rate of the CFRP shell is studied. According to image entropy theory, the influence of coil structure size parameters on the uniformity of a temperature field distribution is analyzed. Furthermore, the accuracy of the coil structure size parameters with respect to temperature field variation is verified with a CFRP induction heating experiment. This study provides theoretical support and a verification method for the selection, design, and optimization of the coil structure size parameters of CFRP shells during induction heating.

     

Non-linear optimization of a new robotic induction process for local heat treatment using thermal finite element analysis

Performing high-quality repair on aging hydro power equipment is a challenging issue for utilities. Weld repair deteriorates the mechanical properties of the base metal in and around the heat-affected zone. For martensitic stainless steel runners, there is no way to perform post-weld heat treatment (PWHT) on site to restore those properties without dismantling, a very expensive job for such large components, typical of power utilities. To perform in situ high-quality repairs on such components, a new robotic heat treatment process is developed. Heat is generated and controlled using a flat spiral coil mounted on a compact, portable robot and moved over the area needing heat treatment. Unlike conventional induction heating, which requires a customized coil, this new approach combines a universal coil and a flexible robot to heat a broad range of complex shapes. One critical aspect is to set heating and path parameters in order to generate a target spatial and temporal temperature field. This paper proposes a numerical method combining thermal finite element analysis and a non-linear optimization algorithm to set these parameters. The temperature resulting from the electromagnetic field induced by the coil is modeled using an average heat input source to improve computation speed. Good agreement is obtained between numerical and experimental results for PWHT under laboratory conditions.     

Three-dimensional numerical modeling of an induction heated injection molding tool with flow visualization

Using elevated mold temperature is known to have a positive influence of final injection molded parts. Induction heating is a method that allow obtaining a rapid thermal cycle, so the overall molding cycle time is not increased. In the present research work, an integrated multi-turn induction heating coil has been developed and assembled into an injection molding tool provided with a glass window, so the effect of induction heating can directly be captured by a high speed camera. In addition, thermocouples and pressure sensors are also installed, and together with the high speed videos, comparison of the induction heating and filling of the cavity is compared and validated with simulations. Two polymer materials ABS and HVPC were utilized during the injection molding experiments carried out in this work. A nonlinear electromagnetic model was employed to establish an effective linear magnetic permeability. The three-dimensional transient thermal field of the mold cavity was then calculated and compared with the experiments. This thermal field was transferred to an injection molding flow solver to compare simulations and experimental results from the high speed video, both with and without the effect of induction heating. A rapid thermal cycle was proved to be feasible in a mold with an integrated induction coil. Furthermore, it was shown that the process can be modeled with good accuracy, both in terms of the thermal field and of the flow pattern.     

An induction heating diamond anvil cell for high pressure and temperature micro-Raman spectroscopic measurements

A new external heating configuration is presented for high-temperature diamond anvil cell instruments. The supporting rockers are thermally excited by induction from an externally mounted copper coil passing a 30 kHz alternating current. The inductive heating configuration therefore avoids the use of breakable wires, yet is capable of cell temperatures of 1100 K or higher. The diamond anvil cell has no resistive heaters, but uses a single-turn induction coil for elevating the temperature. The induction coil is placed near the diamonds and directly heats the tungsten carbide rockers that support the diamond. The temperature in the cell is determined from a temperature-power curve calibrated by the ratio between the intensities of the Stokes and anti-Stokes Raman lines of silicon. The high-pressure transformation of quartz to coesite is successfully observed by micro-Raman spectroscopy using this apparatus. The induction heating diamond anvil cell is thus a useful alternative to resistively heated diamond anvil cells.     

Coil design optimization for an induction evaporation process: Simulation and experiment

For the purpose of utilizing induction heating in the evaporation process, the effects of induction coil design and droplet size on induction heating efficiency are investigated. Electro-magnetic simulations with various induction coil designs were conducted to predict the electro-magnetic field distribution. The induction coils were fabricated in order to verify the simulation results under atmospheric evaporation test conditions. The electro-magnetic simulation results indicated that the magnetic field became widened around the Zn droplet when the size of the Zn droplet increased. This in turn attributed to the increase in induction heating energy efficiency. The energy efficiency of the induction coil with 4-windings was the highest among the 3-, 4-, and 5-windings induction coils. Energy efficiency tendencies derived by the atmospheric evaporation tests corresponded well to the simulation results, and maximum energy efficiency was measured to be 42% under the atmospheric evaporation tests.     

Development of roll-to-roll hot embossing system with induction heater for micro fabrication

In this paper, a hot embossing heating roll with induction heater inside the roll is proposed. The induction heating coil is installed inside a roll that is used as a heating roll of a roll-to-roll (R2R) hot embossing apparatus. Using an inside installed heating coil gives the roll-to-roll hot embossing system a more even temperature distribution on the surface of the heating roll compared to that of previous systems, which used an electric wire for heating. This internal induction heating roll can keep the working environment much cleaner because there is no oil leakage compared to the oiled heating roll. This paper describes the principles and provides an analysis of this proposed system; some evaluation has also been performed for the system. A real R2R hot embossing heating roll system was fabricated and some experiments on micro-pattering have been performed. After that, evaluation has been performed on the results.     

曲轴抛光常见质量问题及其对策

针对曲轴抛光后曲轴轴颈油孔下凹问题、曲柄销轴颈刹车印问题、圆角粗糙度超差问题、止推面粗糙度超差问题,通过分析抛光臂、抛光瓦与曲轴的受力和运动关系,找出质量问题根本原因,并针对性设计不同结构的抛光瓦解决相应质量问题。为同类产品的相似技术问题提供一套有效分析路径和改进措施。     

Eliminating weldlines of an injection-molded part with the aid of high-frequency induction heating

High-frequency induction is an efficient way to heat mold surface by non-contact electromagnetic induction. It has been recently applied to injection molding because of its capability to heat and cool mold surface rapidly. This study applies high-frequency induction heating to eliminate weldlines in an injection-molded plastic part. To eliminate or reduce weldlines, the mold temperature at the corresponding weld locations should be maintained higher than the glass transition temperature of the resin material. Through 3 s of induction heating, the maximum temperature of 143 °C is obtained on the mold surface around the elliptic coil, while the temperature of the mold plate is lower than 60 °C. An injection molding experiment is then performed with the aid of induction heating, and the effect of induction heating conditions on the surface appearance of the weldline is investigated. The weldline on the heated region is almost eliminated, from which we can obtain the good surface appearance of the part.     

Analysis of the induction heating for moving inductor coil

Induction heating is a process that is accompanied with magnetic and thermal situation. This paper presents a simulation of a magneto-thermal coupled problem of an induction heating process for moving inductor coil. In the magnetic and thermal analyses, temperature-dependent magnetic and thermal material properties were considered. As the inductor coil moves in the process, solution domains corresponding to inductor changes into those of the air, and the solution domains of air change into those of the inductor. For these reasons, modeling of induction heating process is very difficult with general purpose commercial programs. In this paper, induction heating process for moving coil was simulated with the concept of traveling the position of the heating planes. Finite element program was developed and finite element results were compared with the experimental results.