The torsional strength of the drilling tools can be greatly increased by using the double shouldertool joint.
双台肩钻具接头可大幅度提高钻具的抗扭强度。
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The result shows that the velocity field changes with the increase of space from shoulder and stir tool and the flow of weld metal from top to bottom and stir zone to rotation zone also weakens.
The new method for machining keyway in holes and the special tool is presented, with which the keyway not only in blind holes but also in shoulder holes can be machined.