基于红外辐射测温法的焊头动态高速真温测量系统研制

Development of Dynamic High-Speed True Temperature Measurement System for Welding Head Based on Infrared Radiation Thermometry

温度是用来表征物体特性的一个重要的基本参数,被广泛应用于金属加工、生产生活、航空航天等各个领域,温度测量的准确与否对每个行业都有着至关重要的影响。随着电子设备的尺寸不断微型化以及各种可穿戴智能设备的普及和发展,小型化成为了电子元件技术水平的一个重要技术指标,所以电子元器件也一直朝着小尺寸、高集成化方向发展,而其焊接温度的波动引起的产品良品率也在不断降低。因此,如何实现电子元器件焊接过程中焊头温度的实时获取,已成为众多相关企业急需研究的课题。基于晶体管式焊接电源的工作特点,从分析焊头的结构特性入手,利用焊头的红外光谱辐射特性,设计了一种激光瞄准式的光学系统,采用朗伯体法对焊头进行温度测量,从而得到焊头工作时的实时真温。整个温度测量系统由硬件系统部分和软件系统部分构成。其中,硬件系统包括光学系统的设计、 I/V转换及放大电路和上位机的高速数据采集系统。软件系统主要包括上位机系统界面的设计。上位机软件采用LabVIEW进行程序设计,主要包括AD采集卡的配置与驱动、数据滤波、零点测量、温度标定、温度计算、实时温度曲线和数据存储。在系统建立、软件调试完毕后,采用标准空腔黑体炉对测温系统进行了校准。首先,利用整体黑体法对焊头工作时的发射率进行了试验,结果表明,在氧化和非氧化状态下,其发射率与文献数据基本一致。然后利用该发射率值,计算出了焊头上小孔的空腔黑体发射率。最后,利用恒流晶体管式焊接电源进行了系统稳定性和重复性实验。分析该方法的不确定度,得出该方法的总体不确定度在3%以内。通过对测温系统的标定和配置,该系统还可以应用在其他需要高速精确测温的场景。

Temperature is an important basic parameter used to characterize the properties of objects,and is widely used in various fields such as metal processing,production life,aerospace,etc.The accuracy of temperature measurement has a crucial impact on each industry.With the continuous miniaturization of the size of electronic devices and the popularity and development of various wearable smart devices,miniaturization has become an important technical indicator of the level of technology of electronic components,so electronic components have also been developing in the direction of small size and high integration,and its welding temperature fluctuations caused by the product yield is also decreasing.Therefore,achieving real-time access to the solder head temperature during welding electronic components has become an urgent research topic for many related companies.Based on the working characteristics of transistorized welding power supply,this paper starts by analyzing the structural characteristics of the solder head,using the infrared spectral radiation characteristics of the solder head,and designs a laser-targeted optical system to measure the temperature of the solder head using the Lambertian method,to obtain the real-time true temperature of the solder head when working.The whole temperature measurement system consists of a hardware system part and a software system part.Among them,the hardware system includes the design of the optical system,I/V conversion and amplification circuit and the high-speed data acquisition system of the upper computer.The software part of the system mainly includes the design of the interface of the upper computer system.The software of the upper computer adopts LabVIEW for program design,which mainly includes the configuration and driving of AD acquisition card,data filtering,zero point measurement,temperature calibration,temperature calculation,real-time temperature curve and data storage.After the system was established and the software was debugged,the temperature measurement system was calibrated using a standard cavity blackbody furnace.First,the emissivity of the weld head during operation was tested using the integral blackbody method,and the results showed that the emissivity was in general agreement with literature data in both oxidized and non-oxidized states.Then,using this emissivity value,the cavity blackbody emissivity was calculated for the small holes in the solder head.Finally,system stability and repeatability experiments were performed using a constant-current transistorized welding power source.The uncertainty analysis of the method yielded an overall uncertainty of the method within 3%.By calibrating and configuring the temperature measurement system,the system can also be applied to other scenarios where high-speed accurate temperature measurement is required.