基于图像测量技术的双波长测温仪在线校准方法

红外测温的方法具有非接触、能够测量极高温度的特点,但其测温精度易受材料自身和环境的影响,针对静电悬浮材料实验装置中双波长测温仪温度测量存在偏差的问题,设计了一种基于图像测量技术的在线校准方法。采用CCD相机获取测温样品的图像,通过边缘提取拟合计算样品体积随温度的变化,与材料自身实际的热膨胀系数对比,修正双波长测温仪的发射率比值。通过对纯金属锆的实验,比对校准后测量的熔点温度,验证了该在线校准方法。     

选择红外测温仪主要考虑

正温度范围:每种型号的测温仪都有其特定的测温范围。所选仪器的温度范围应与具体应用的温度范围相匹配。目标尺寸:测温时,被测目标应大于测温仪的视场,否则测量有误差。建议被测目标尺寸超过测温仪视场的50%为好。光学分辨率(D:S):即测温仪探头到目标直径之比。如果测温仪远离目标,而目标又小,应选择高分辨率的测温仪。     

光纤型红外测温仪消除辐射率对测温结果影响的研究

在机械加工中测量切削温度有多种方法,其中红外辐射测温法是通过测量出物体的辐射能来计算得出物体的温度方法,这种测量方法需要知道被测量物体的辐射率。在机械加工中,很难获得工件材料和刀具材料的准确辐射率,所以在测量切削温度的过程中如何避免辐射率对测温结果的影响很重要。文中利用光纤型红外测温仪,通过比值处理In As和In Sb的辐射能的方法巧妙滤掉了辐射率的影响,并基于新型标定装置最终处理得出了红外光纤测温仪的电势-温度关系曲线。     

红外测温仪在真空炉温度测量上的应用

非接触式测温(红外测温仪)以其响应时间短、测量温度高、经久耐用等特点,已经逐渐取代传统的接触式测温(热电偶等),并成功地广泛应用于各种工业领域。真空炉内温度的测量就是成功的一例,但在红外测温仪的选型和使用中还应注意一些问题,现介绍如下。 1.峰值保持 在实际应用中,移动的被测物体往往会移出视线以外,或者在两个被测物体之间会出现低温的空间,这种情况当然会导致测温仪的读数忽上忽下。为了解决这个问题,大多数的红外测温仪设置了一个被称之为“峰值保持”的功能。这是一个简单的     

电站锅炉高温烟气对壁面红外测温的影响

电站锅炉中重要部件被高温烟气覆盖时,红外测温方法会导致测温带来偏差,文中利用源项多流法对烟气遮蔽下壁面的红外测温进行了模拟,计算了不同探测角度下进入探测器的能量以及测量的温度,分析了烟气的厚度、温度、吸收系数、散射系数以及散射相函数对壁面红外测温的影响,得出随着烟气厚度的增加,探测温度受烟气的影响会越大,随着烟气温度、吸收系数和散射系数的增加,红外探测温度会随之升高,但散射相函数对红外测温的影响较小。     

基于虚拟仪器的可视化电力设备在线红外监控系统研究

对变电站主要电力设备红外测温仪在线监测进行研究,重点研究了基于红外测温仪与视频信号结合扫描的在线监测系统。设计并构建了系统,使其能利用红外测温仪扫描电力设备并形成可视的温度分布及变化模型。本系统可以将设备的图像监控画面和可视化的红外测温信号结合起来,对设备进行远程红外测温,并将返回的温度值加以存储和分析,经网络传至控制终端,利用软件形成电力设备温度分布及变化过程模型,分析并监视变电站或设备的运行情况。     

用电子陀螺精密云台对准立火道测温区的方法

由于焦炉炉顶在高温下的变形随时间季节的变化而变化,走行在不平整的炉顶的轨道测温机器人能否替代人工进行焦炉立火道温度测量的关键是如何自动将测温仪对准测温点,在不同的立火道上方测温机器人的倾角不同,并且不同立火道的变形量也不同,使得固定在测温机器人上的测温仪很难对准测温点。为此,将测温仪固定在安装了电子陀螺仪的精密云台上,通过手动标定及自动定位2个步骤对焦炉立火道底部最佳测量区间进行温度测量。并在太钢9号焦炉上完成了对设备的调试和实验,获得了多组温度数据,对比标准温度进行分析得知,实验所测量的立火道温度合理,符合生产工艺,验证了利用陀螺仪定位的新型测温云台系统的可行性。     

远距离红外测温仪

一种远距离红外测温仪在中国深圳蛇口科健公司投产。 这种IR系列远距离红外测温仪测量距离和测量目标的比值是500,可测100m远目标的温度,测温范围:0～3000C,有最大值、最小值、瞬时值记忆     

粉末材料激光烧结成型过程温度场的测量

介绍了粉末材料的激光烧结成型技术,研制开发了测温系统对粉末材料激光烧结过程温度场进行了测量,利用红外测温仪测量粉末表面温度,热电偶测量粉末内部温度,测量结果由计算机处理.最后将温度场测量结果与数值模拟结果进行了比较,二者吻合较好.     

基于MLX90601C的红外测温仪

介绍了一种红外测温仪,该测温仪基于红外测温模块MLX90601C,具有高测量精度、液晶显示和数据存储、语音播报功能,并带有RS-232数据接口,可以将测得的数据发送到PC.分析了红外测温原理和影响红外测温精度的因素,介绍了MLX90601C的特性与结构,内部寄存器及其功能,介绍了MLX90601C内部温度数据的存储格式及读取方式.分析了SPI串口的读写操作时序.设计了单片机控制MLX90601C的SPI接口电路、语音播报电路和液晶显示电路、RS-232接口电路,编写了测温仪的软件程序.     

大型复杂框架结构焊接变形与应力控制仿真

针对大型复杂结构件有限元计算效率低下的问题,提出了分段移动温控体热源高效算法,并将该算法应用于挖掘机中框架非连续焊的分层逐项优化中,对分段移动温控体热源模型和逐点移动双椭球热源模型的计算效率进行了对比。结果表明,取对称焊与跳焊相结合的焊接方式所得到的焊接残余应力和角变形量最小,左右两侧立板处焊接残余应力峰值相较于原工艺方案,降幅率分别为38.46%和42.13%,降低效果显著;分段移动温控体热源模型与逐点移动双椭球热源模型模拟结果相比,两者得到的变形量变化趋势一致,计算精度相当,但前者计算效率显著要高。将模拟结果与测量结果进行对比,两者高度一致,验证了热源模型及优化工艺的准确性。     

General temperature rise solution for a moving plane heat source problem in surface grinding

In the present study, the general solutions for a transient state as well as for the temperature rise formed everywhere in the workpiece due to a rectangular-shaped moving plane heat source arising at the grinding zone are derived. The present analysis starts from a point heat source solution by applying the method of separation of variables to a three-dimensional heat conduction problem. Because the workpiece moving velocity is quite small, the convective term related to the workpiece velocity is first excluded from the heat conduction equation. This workpiece velocity effect will be included in the model by slightly modifying the coordinate variable in the sliding direction shown in the solution of the point heat source. Therefore, the general three-dimensional solution of the stationary temperature rise can be expressed in an integral form as a function of the product value of the unknown initial condition and the particular solution of temperature rise. The unknown initial temperature rise in the solution can be replaced by the point heat source due to frictional that multiplying the product of the Dirac delta functions defined for three directions. Using the definition of the Dirac delta function, the temperature rise solution for a point heat source can thus be obtained. This solution is further extended to obtain the moving and uniform heat sources arising in a rectangular grinding zone. A comparison among the experimental result and the theoretical results predicted by the present model and Jaeger’s model [Jaeger JC (1942) Proc Roy Soc, NSW 76:203–224.] show that the present model is quite accurate and is generally superior to Jaeger’s model; it can be applied to predict the three-dimensional temperature rise distributions in the workpiece.     

High-speed test of thermal effects for a machine-tool structure based on modal analysis

A new test method has been developed to evaluate the temperature rise of machine-tool structures. In this method, which uses short period data obtained during a warm-up run, the machine-tool structure is modelled by the finite element method (FEM) and is analysed in terms of the eigenvalues of the thermal equation. Characteristic temperature rise curves for the structure are obtained, which have variable parameters. The values of these depend upon the strength of heat sources. Then, by determining the parameters such that the characteristic temperature rise curves fit those obtained during a warm-up run, it is possible to identify the strength of the heat sources, and thus the values of temperature rise for any point in the structure. Experiments have been carried out which verify the effectiveness of the method.     

激光片光浓度场测量系统及其在风洞模拟中的应用

为在大型环境风洞中模拟大气污染物迁移扩散状况,开发出污染物浓度激光片光测量系统和污染物发放系统。基于激光片光浓度场测量系统,风洞模拟得到城市环境下点、线和面源污染物的扩散分布图案。基于风洞试验工况的边界条件,计算流体动力学(CFD)仿真得到污染物扩散分布,CFD仿真结果和激光片光浓度测量结果,两者定性一致,达到了相互印证的效果。将研究开发的激光片光浓度场测量系统和定量采样方法相结合,有望实现风洞试验中污染物浓度场的定量测试。     

Manufacturing and temperature measurements of a sodium heat pipe

A high-temperature sodium stainless steel heat pipe was fabricated and its performance has been investigated. The working fluid was sodium and it was sealed inside a straight tube container made of stainless steel. The amount of sodium occupied approximately 20% of the total volume of the heat pipe and its weight was 65.7gram. The length of a stainless steel container is 1002mm and its outside diameter is 25.4mm. Performance tests were carried out in a room air condition under a free convective environment and the measured temperatures are presented. The start-up behavior of the heat pipe from a frozen state was investigated for various heat input values between 600W and 1205W. In steady state, axial temperature distributions of a heat pipe were measured and its heat transfer rates were estimated in the range of vapor temperature from 500°C to 630°C. It is found that there are small temperature differences in the vapor core along the axial direction of a sodium heat pipe for the high operating temperatures. But for the range of low operating temperatures there are large temperature drops along the vapor core region of a sodium heat pipe, because a small vapor pressure drop makes a large temperature drop. The transition temperature was reached more rapidly in the cases of high heat input rate for the sodium heat pipe.     

Noniterative algorithm for improving the accuracy of a multicolor-light-emitting-diode-based colorimeter

We present a noniterative algorithm to reliably reconstruct the spectral reflectance from discrete reflectance values measured by using multicolor light emitting diodes (LEDs) as probing light sources. The proposed algorithm estimates the spectral reflectance by a linear combination of product functions of the detector's responsivity function and the LEDs' line-shape functions. After introducing suitable correction, the resulting spectral reflectance was found to be free from the spectral-broadening effect due to the finite bandwidth of LED. We analyzed the data for a real sample and found that spectral reflectance with enhanced resolution gives a more accurate prediction in the color measurement.     

Transfer function solving, simulating and testing of thermal dynamics characteristics of a ballscrew

Based on the theory of heat transfer, the transfer function between the thermal deformation of any point on the lead screw and the temperature of heat sources of a ballscrew under the influence of multi-changeable heat sources is solved by using the Laplace transform method. By solving the amplitude-frequency characteristics and phase-frequency characteristics of the transfer function, the steady-state response of thermal deformation of the ballscrew is obtained, and the thermal dynamics characteristics of the lead screw under the influence of multi-heat sources are further studied. Comparing with the result of finite-element simulation, the theoretical analyzing result accords with the steady-state part of the finite-element simulating result. Through tests of the steady-state response of thermal deformation, the thermal dynamics characteristics are further studied. The curves of tests by and large accord with the theoretical analyzing result, which shows that the method of transfer function is correct and valid in solving the steady-state response of thermal deformation.     

时栅角位移传感器在线自标定系统

为解决时栅角位移传感器在实际应用中的在线标定问题,提出了一种定角平移自标定方法并设计了相应的自标定系统。该方法首先把圆周封闭的自然基准转换成定角基准,在时栅内部建立了自标定基准。然后,根据傅里叶级数的性质,将定角基准平移到傅里叶变换的幅值和相位中,建立了测量值之差与误差之差的函数关系。通过对测量值之差进行傅里叶分析,重构了时栅角位移传感器的误差函数。最后,讨论了影响自标定精度的误差来源,并设计了传感器的零点纠错算法。为了检验自标定效果,利用激光干涉仪实验装置与自标定系统进行了对比试验。结果表明:定角平移自标定精度为1.9″,与理论计算的自标定误差(1.5±0.5)″的结论相符。提出的自标定方法在解决时栅自身标定基准的同时,满足了精密测量领域对时栅精度和可靠性的要求。     

电子束焊接温度场实时监测系统设计

焊接温度场是影响焊接质量和生产效率的主要因素,因此对焊接过程中的温度场分布进行监测就显得极为重要。利用普通彩色CCD构成了焊接温度场实时测量系统;基于工件热辐射随温度变化单调上升特性建立了温度场测量模型;采用最小二乘法对实测的温度数据进行分析,得到了温度场测量模型的最佳参数。试验结果表明了该监测系统的可行性。     

Transfer function solving,simulating and testing of thermal dynamics characteristics of a ballscrew

Based on the theory of heat transfer, the transfer function between the thermal deformation of any point on the lead screw and the temperature of heat sources of a ballscrew under the influence of multi-changeable heat sources is solved by using the Laplace transform method. By solving the amplitude-frequency characteristics and phase-frequency characteristics of the transfer function, the steady-state response of thermal deformation of the ballscrew is obtained, and the thermal dynamics characteristics of the lead screw under the influence of multi-heat sources are further studied. Comparing with the result of finite-element simulation, the theoretical analyzing result accords with the steady-state part of the finite-element simulating result. Through tests of the steady-state response of thermal deformation, the thermal dynamics characteristics are further studied. The curves of tests by and large accord with the theoretical analyzing result, which shows that the method of transfer function is correct and valid in solving the steady-state response of thermal deformation.