The latter has a cylindrical groove at its center, thus generating a solid core, which guides the tool as it proceeds during the drilling operation.
后者在其中心有一圆柱形沟槽，这样能生成整体芯在钻孔作业过程中引导钻头。
2
The center of this groove is also half-way from the ceiling to the floor of the Grand Gallery.
这些槽的中央也是从走廊的天花板都地面距离的一半。
3
Based on both the area formula of gear tooth and groove and their respective center multiplying formula, the force and moment expressions of both sides of side-panels could be brought out at first.