共查询到19条相似文献,搜索用时 203 毫秒
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通过数值模拟的方法计算了圆坯感应加热过程的温度分布情况,研究了线圈匝数、聚磁体、坯料表面与空气的对流换热等因素对感应加热的影响。结果表明,线圈匝数对坯料温度分布有较大的影响,为了得到相对均匀的温度分布需选择合理的线圈匝数;感应加热中采用聚磁体,可显著提高坯料端部温度,消除坯料端部温度偏低的现象;同时,计算了感应加热过程的磁场分布,解释了坯料温度分布和变化的原因,并提出控制感应加热过程坯料温度的合理措施。 相似文献
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为研究低温回火热处理炉加热的温度均匀性,搭建低温明火炉实验平台,在实验炉内采用高速烧嘴脉冲燃烧加热,获得了实测的炉膛温度分布和炉内钢板表面温度,试验结果表明在合理布置炉内烧嘴和合理的供热方式条件下,不采用循环风机也可满足炉内钢板加热温度均匀性要求。 相似文献
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基于ANSYS的锻件感应加热温度场的数值模拟研究 总被引:2,自引:0,他引:2
针对感应加热过程中工件温度难以测量的问题,应用电磁学和传热学基本理论,建立了锻铸坯料电磁场和温度场分布的数学模型,运用ANSYS软件对感应加热过程温度分布进行变参数研究,为揭示铸坯感应加热过程的规律、优化工艺参数提供理论依据。 相似文献
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针对棒线材加热炉在加热质量方面存在氧化烧损及脱碳情况方面损耗量大、加热温度均匀性差等问题,采用全平焰烧嘴、精细化供热分段等多种技术措施,达到进一步改善棒线材加热炉加热质量的目的。 相似文献
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Mold temperature is a major factor in the quality of injection molding process. A high mold temperature setting is feasible to enhance the molding quality but prolongs the cooling time. Induction heating is the method currently used to heat the mold surface without increasing the molding cycle. However, one unresolved problem of induction heating is the proximity effect resulting from two adjacent coils with different current directions. The proximity effect substantially decreases heating efficiency, which then causes non-uniform heating. This effect is difficult to avoid in a single-layer coil. The most common solution, which is to use magnetic concentrators to reduce the proximity effect, does not obtain satisfactory results. In the novel magnetic shielding induction heating method developed in this study, heating efficiency and temperature uniformity are enhanced by using ferrite materials to separate the conflicting magnetic fields caused by the repulsive proximity effect. Three typical single-layer coils are investigated in this study, including a reciprocated single-layer coil, a single-layer spiral coil, and a rectangular frame coil. Appropriate placement of ferrite materials on these induction coils successfully eliminated the proximity effect, increased the heating rate, and improved temperature uniformity. 相似文献
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Setting high mold temperatures for injection-molding plastics facilitates favorable flow conditions for filling cavities with melted materials and provides an esthetically pleasing surface as well as a high replication rate of high-quality products; however, the cooling times are typically prolonged. Electromagnetic induction heating incorporating surface heating instead of conventional volume heating for mold-heating processes is advantageous because it provides a rapid heating time and a reduced cooling time, is environmentally friendly, and saves energy; therefore, it has been adopted in various variotherm injection-molding systems. Although previous studies have discussed how induction heating is influenced by major factors, such as the number of coil turns, working frequency, and heating distance, few studies have investigated other crucial factors, such as the thickness of the heated target and the position of the induction coil. In this study, the effects of the thickness of a heated target, pitch of coil turns, heating distance, position of the induction coil, working frequency, and waiting time on the heating rate and temperature uniformity of induction heating on a mold surface by using a single-layered coil were analyzed. In addition, the Taguchi method and principal component analysis were applied to determine the optimal combination of control factors for achieving a high heating rate and low temperature deviation. Both simulation and experimental results indicated that the thickness of a heated target plays a crucial role in affecting the heating rate; specifically, a thicker workpiece slows the heating process and generates rapid heat dissipation after induction heating. Moreover, the position of the induction coil exerts the most notable effect on heating uniformity. 相似文献
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This study applied three-dimensional steady-state finite-element numerical simulations of electromagnetic fields and temperature distributions to evaluate the effects of various coil geometries, regional depositions, and magnetic shielding materials on the induction heating of a curved mold plate surface used for fabricating automotive spoilers. Conventionally, the induction heating of large mold surfaces by using a set of long inductive coils entails employing a costly, high-power induction heating device. This study proposes a multizone induction heating approach that entails dividing a target surface into several zones and then applying numerous sets of short inductive coils that require only low-power induction heating devices to the individual regional zones for heating. In this approach, the coil design is relatively simple for efficiently heating these small-area zones. The simulation results are described as follows: (1) the geometry of the inductive coils with respect to the processed workpiece demonstrated a considerable effect on the electromagnetic field distribution and the heating efficiency of the system. (2) Magnetic shielding materials facilitated eliminating the proximity effect, which produces a nonuniform heating pattern along the workpiece wall. (3) Compared with single-zone induction heating, the multiple-zone induction heating of a largely curved mold surface enhanced the heating rate and uniformity performance. 相似文献
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Natural convection is the governing phenomena in many material processing applications. The conventional method of uniform heating at the bottom wall of an enclosure may result in inadequate thermal mixing and poor temperature distribution leading energy wastage. In this work, an alternative, energy-efficient method of distributed heating of the cavity is studied and compared with the isothermal bottom wall heating case in enhancing the thermal mixing and improving the temperature distribution in the cavity. Steady laminar natural convection of various fluids of industrial importance (Pr = 0.015, 07, 10, 1000) in the range of Ra = 103–105 is studied in a differentially heated cavity and in two cases of discretely heated square cavities. Detailed analysis is carried out by visualizing the heat flow by heatlines. The thermal mixing and temperature uniformity in each case are quantified in terms of cup-mixing temperature and root-mean square deviation (RMSD), respectively. It is found that thermal management policy of distributed heating significantly influences the thermal mixing and temperature uniformity in the enclosures. In a case with multiple discrete heat sources, a remarkable uniformity in temperature across the cavity is achieved with moderate thermal mixing. 相似文献
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A moving metallic plate subject to heating and cooling boundary conditions is considered in this work. The plate is heated by an imposed heat flux, and cooled down by an array of impinging jets through convection and radiation. The objective of the present work is determination of operating conditions for controlling the temperature distribution at the end of both heating and cooling sections. The results show that the temperature distribution becomes more uniform across the heating section with an increase in the heating length. An increase in the distance from the impinging jet to the plate causes an increase in the temperature values across the cooling section, and a decrease in the diameter of the impinging jet causes a decrease in the temperature values across the cooling section. It is also shown that an increase in cooling length and the addition of another impinging jet help to reduce the temperature values and increase the uniformity of the structure across the cooling section. Optimized values of the pertinent parameters for both hardening and tempering heat treatments were investigated. 相似文献
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Hsuan-Liang Lin Shia-Chung Chen Ming-Chang Jeng Pham Son Minh Jen-An Chang Jiun-Ren Hwang 《International Communications in Heat and Mass Transfer》2012
Induction heating in injection molding has the advantages of rapid heating, reduced cycle time, and improved product quality. In this research, using both experiment and simulation, externally wrapped coil induction heating was applied to verify the heating capacity of a pair of mold plates. By applying different coil designs and mold gap, the effect of the externally wrapped coil induction heating was evaluated. Results showed that when a serial coil was used as an inductor, the heating rate reached 8.0 °C/s. From an initial mold temperature of 40 °C, after 15 s heating, the mold surface temperature reached 159.9 °C with the serial coil. The parallel coil shows a better heating uniformity but its heating rate is far lower than the serial coil. For the serial coil, the temperature distribution between the core and cavity plate are almost the same. The heating rate increases from 4.9 °C/s to 10.6 °C/s when the inductor design is changed from 5 turns to 7 turns. After 15 s heating, the temperature at point T2 increases from 40 °C to 166.7 °C and 106.1 °C with a mold gap of 1 mm, and 6 mm, respectively. 相似文献
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Shia-Chung Chen Rean-Der Chien Su-Hsia Lin Ming-Chung Lin Jen-An Chang 《International Communications in Heat and Mass Transfer》2009,36(8):806-812
Dynamic mold surface temperature control has the advantage of improving molded part qualities without significant increases in cycle time. In this study, a gas-assisted heating system combined with water cooling and different mold designs to achieve dynamic mold surface temperature control was established. The feasibility of using gas-assisted heating for mold surface temperature control during the injection molding process was then evaluated from experimental results. The effect of mold design as well as heating conditions including hot gas temperature, gas flow capacity, and heating time on the heating efficiency and the distribution uniformity of mold surface temperature were also studied. Results showed that as hot gas temperature and gas flow capacity increased, as well as increasing heating times from 2 s to 4 s, mold surface temperature increased significantly. Fan shaped gas channel design exhibits better mold surface temperature distribution uniformity than tube shaped gas channel design. During gas-assisted heating/cooling, it takes 2 s to increase mold surface temperature from 60 °C to 120 °C and 34 s for mold surface to return to 60 °C. In addition, under specified heating conditions and using the best composite mold designs, the heating rate can reach up to 30 °C/s, a rate well-suited to industrial applications. 相似文献
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强制炉气循环电炉一般用于加热铝镁合金构件等工件要求温度均匀性较高、且炉温较低,以对流传热为主的场合。这类电炉设计的主要问题是确定风机的风量、风压及合理组织炉内气流的循环。详细地进行了风量的理论计算,并实际应用。 相似文献
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A low cost high temperature test facility designed and built for the purpose of thermo-mechanical testing is described. An induction heater provides variable heating rates, simple operation and easy access for temperature and strain measurement. Specially designed high temperature specimen grips with water-cooling allow for testing over long periods of time. Contact temperature and strain measurements are utilised to provide accurate and reliable results. Detail is given on the experimental procedure including calibration of the thermocouple temperature measurement. A validation study of the thermal expansion and tensile Young’s Modulus of carbon steel 1020 at temperatures up to 850 °C proves the accuracy of the test set-up and procedure. Results are given for the stress–strain curves of aluminium alloy 7000 T4 at various temperatures to further demonstrate the capabilities of the test facility. The measured thermo-mechanical properties of these materials were used to develop high temperature constitutive models for implementation in finite element thermal–structural analysis of hypersonic structures. 相似文献