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1. 发明授权

US4355281A Eddy current surface flaw detection employing signal correlation 失效
标题翻译：使用信号相关的涡流表面探伤
公开(公告)号：US4355281A
公开(公告)日：1982-10-19
申请号：US66387
申请日：1979-08-14
申请人： James M. Toth , Tyler W. Judd
发明人： James M. Toth , Tyler W. Judd
IPC分类号： G01N27/90 , G01N27/72 , G01N27/82 , G01R33/12
CPC分类号： G01N27/9046 , G01N27/904
摘要： An eddy current flaw detection system for inspecting a workpiece for surface flaws is described. The system has a search unit for mounting a pair of eddy current search coils in close proximity to a workpiece at locations which are longitudinally spaced with respect to the workpiece. The system is disclosed in the environment of a workpiece support and transport mechanism which causes a workpiece to rotate and move axially with respect to the search unit.Coil energizing and detection circuitry is provided having a pair of eddy current channels. Each channel energizes a connected one of the search coils to induce eddy currents within a workpiece at slightly different energization frequencies. Each channel has an output for producing signals indicating the presence and severity of detected flaws. The coil energization at different frequencies results in each coil responding to self induced eddy currents rather than currents induced by the other of the two coils.Processing circuitry is provided having a pair of inputs each connected to a respective eddy current channel output. The processing circuitry algebraically multiplies concurrently received eddy current channel output signals to produce a resultant signal. The disclosed signal correlation circuitry will not process a signal from a single coil. Accordingly, the axial separation of the search coils establishes a minimum length of surface flaw which will be detected. The value of the resultant signal indicates the severity of the detected surface flaw.
摘要翻译：描述了用于检查工件表面缺陷的涡流探伤系统。该系统具有搜索单元，用于在相对于工件纵向间隔开的位置处将一对涡流搜索线圈安装在工件附近。该系统在工件支撑和运输机构的环境中被公开，其使工件相对于搜索单元旋转并且轴向移动。提供具有一对涡流通道的线圈通电和检测电路。每个通道激励连接的一个搜索线圈，以在稍微不同的通电频率下在工件内感应涡流。每个通道具有用于产生指示检测到的缺陷的存在和严重性的信号的输出。不同频率的线圈通电导致每个线圈响应于自感应涡流，而不是由两个线圈中的另一个引起的电流。提供具有一对输入的处理电路，每个输入连接到相应的涡流通道输出。处理电路代数地乘以并行接收的涡流通道输出信号以产生合成信号。所公开的信号相关电路将不处理来自单个线圈的信号。因此，搜索线圈的轴向分离建立将被检测到的表面缺陷的最小长度。所得信号的值表示检测到的表面缺陷的严重性。

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