| 摘要 |
PURPOSE:To improve the utilization rate of a core block, and also, to execute an ideal depth setting work by exposing a depth end line on both end sides of the core block. CONSTITUTION:A second core block 22 is shifted against a first core block 21 and joined integrally so that a depth end line E is exposed on only one end side of the first core block 21. Accordingly, the utilization rate of the core block can be improved. On the other hand, a depth end line of the other end side of the first core block 21 can be exposed by cutting and removing an undesired part of the second core block 22. In such a way, a visual observation of the depth end line from one direction can be executed, and at the time of setting the depth, the same work as in the past can be executed, and no trouble occurs.
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