Laminated block correctness determining method

A laminated block correctness determining method for determining whether a laminated block to be laminated is a correct laminated block when manufacturing a laminated iron core by laminating cylindrical laminated blocks, each including laminated iron core pieces, wherein orientation identification portions are respectively disposed on opposite end surfaces of each of the laminated blocks in an axial direction, the orientation identification portions being used to identify an orientation of the laminated block, the laminated block correctness determining method comprising:

• acquiring, with an imaging device, a captured image of the laminated block by capturing one end surface of the laminated block in the axial direction;
• and
• determining whether the orientation of the laminated block is correct by comparing the orientation identification portion in a registered image with the orientation identification portion in the captured image, the registered image being an image of one end surface of the correct laminated block in the axial direction registered in advance, wherein
• each of the laminated blocks includes:
• a central hole;
• cooling passages which are arranged at intervals in a circumferential direction, which open in the opposite end surfaces, and through which a cooling medium flows;
• and
• a key that protrudes from an inner surface of the central hole,
• the cooling passages include:
• a first cooling passage located in a predetermined region as the one end surface is viewed;
• and
• a second cooling passage symmetric to the first cooling passage with respect to an imaginary axis extending in a protruding direction of the key, the second cooling passage having an opening shape that is different from an opening shape of the first cooling passage,
• the orientation identification portions each include the first cooling passage and the second cooling passage, and
• the determining whether the orientation of the laminated block is correct includes determining whether the orientation of the laminated block is correct by comparing the opening shape of the cooling passage located in the predetermined region in the registered image with the opening shape of the cooling passage located in the predetermined region in the captured image.