【摘要】 中密度纤维板（medium density fiberboard,MDF）在生产过程中常出现鼓泡缺陷，影响其性能。为了实现MDF缺陷的精准检测，研究提出利用超声波相位差法检测中密度纤维板内部鼓泡缺陷的方法，选取6种不同厚度的中密度纤维板，模拟内部鼓泡缺陷，结合示波器与功率放大器分析超声波在板材无缺陷区与缺陷区的相位特性。结果表明：超声波穿过MDF无缺陷区域时，相位在-180°～180°之间周期性变化；而在鼓泡缺陷区域处，频率低于230 kHz时，相位在-180°和180°之间变化；频率超过230 kHz后，相位范围急剧缩小至-50°～50°。因此，230 kHz及以上的频段适用于检测MDF内部的鼓泡缺陷。超声波相位与鼓泡缺陷的存在位置与厚度呈线性相关，相关系数达到0.9以上，鼓泡距离表面越远或鼓泡层厚度越大，超声波相位越高。研究为中密度纤维板生产线提供可定位缺陷深度的无损检测方案，对实现纤维板质量在线自动化与智能化检测具有重要意义。更多还原

【Abstract】 Blister, a common defect that frequently appears during the production of medium density fiberboard(MDF), compromises its performance. To accurately detecting these internal defects, this study proposes an ultrasonic phase-difference method specifically tailored for MDF. Six MDF panels of various thicknesses were fabricated. Artificial blisters were constructed in order to systematically investigate the ultrasonic phase characteristics in both defect-free and blister-simulation regions using an oscilloscope and a power amplifier. When ultrasonic waves traverse defect-free MDF, the phase exhibits a periodic variation between-180° and +180°. In contrast, when the wave interacts with a blister, the phase remains within the same range only if the excitation frequency is below 230 kHz, while when it is above 230 kHz, the phase range collapses abruptly to between-50° and +50°. Consequently, frequencies of 230 kHz and higher are recommended for reliable blister detection. A strong linear correlation(Pearson’s r≈0.9) was formed between the measured phase and the geometrical attributes of the blister: its depth from the surface and its thickness. Specifically, the phase increases monotonically with increasing both defect depth and thickness. The proposed method offers a non-destructive, depth-resolving inspection solution that can be integrated into industrial MDF production lines, thereby offering significant value for the realization of online, automated, and intelligent quality monitoring of fiberboard production.更多还原