Punch a hole in the middle of the paper cover where the hole of the spool is. Now your hole should run through the paper, spool, and cardboard without any obstructions.

在纸片棉线轴洞的位置打个洞，这个洞贯穿了纸片、棉线轴和硬纸板，洞内没有其他遮挡物。

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System actually lifts, turns and transports rolls, coil, or spool materials such as paper, film, or foil with the push of a button.

系统实际上电梯，转身和运输辊，线圈，或如纸张，薄膜阀芯材料或金属箔与一个按一下按钮。

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According to the poor linearity of pressure characteristic in a type of electric water valve, the optimization and calculation process of the spool structure was given in this paper.

针对某型号电动水阀压力特性线性度差的问题，对阀芯结构进行优化设计，给出了阀芯的设计和计算过程。

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