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为新型航空热交换器而研制的小口径薄壁铝合金管.其口径都在10mm以下,壁厚<0.5mm。因而必须严格保证其外形尺寸精度和力学性能。尤其是为了保证小管的耐蚀性,内外表面质量的要求则更显苛刻。在管材生产的各个工艺环节.甚至在包装过程中.如果稍有疏忽.就会由于表面擦伤而产生废品.因而就需对所有产品进行最终的表面探伤。目前.管材的无损表面检测.比较流行也比较先进的有超声波检测和涡流检测方法。与超声探伤相比.涡流探伤探头结为简单,对于小口径管材的检测速度快、效率高。本文所研制的管材.最小直径为(?)3.2mm。目前还没有与之有关的检测方法及标准.因而.本文将讨论利用涡流探伤法检测小管材制品表面质量的检测标准。1 管材的涡流探伤涡流检测是将选定频率和功率的交变信号输入到探头的激励线圈.使之在被检测材料中感应出涡流。此涡流也产生一个与激励线圈电磁场相反的交变磁场.使探头中测量线圈的阻抗和电压发生变化。由于下同材料的电导率、磁导率、厚度、涂层厚度和缺陷等不同.因而探头中测量线圈的阻抗变比也不相同。检测线圈中的阻抗变比是个矢量.可通过平面图形的方式表示出来.称为阻抗图。文献[4]中详细
For the new aviation heat exchanger and the development of small-caliber thin-walled aluminum alloy pipe. Its caliber are below 10mm, wall thickness <0.5mm. Therefore, we must strictly ensure its dimensional accuracy and mechanical properties. Especially in order to ensure the corrosion resistance of the small tube, the quality requirements of the internal and external surfaces are even more demanding. In every process of pipe production, even in the packaging process, if it is neglected a little, it will produce scrap due to scratches on the surface, so the final surface inspection of all the products is required. At present, the pipe nondestructive surface testing more popular and more advanced ultrasonic testing and eddy current testing methods. Compared with ultrasonic testing, eddy current testing probe knot is simple, small diameter pipe for the detection speed, high efficiency. Pipe developed in this article. The minimum diameter (?) 3.2mm. There is no relevant testing methods and standards.Therefore, this article will discuss the use of eddy current testing of small pipe products surface quality testing standards. Eddy current inspection of a pipe Eddy current testing is to enter the alternating signal of the selected frequency and power into the excitation coil of the probe so as to induce eddy currents in the detected material. This eddy current also generates an alternating magnetic field that is opposite to that of the excitation coil, changing the impedance and voltage of the measuring coil in the probe. Due to the conductivity, permeability, thickness, coating thickness and defects of the same material, the impedance of the measuring coil in the probe is not the same. The impedance in the detection coil is a vector, which can be expressed in the form of a flat graph, called the impedance diagram. Document [4] in detail