| 摘要 |
PURPOSE: To provide an expansion anchor which can be economically manufactured and has a secure continuous expansion characteristic in crack or tensile stress zones. CONSTITUTION: An expansion anchor has a coating made of a low friction material on an inner peripheral contacting surface of an expansion sleeve 7 and an outer peripheral contacting 10 surface of an extension part of a shaft 2. The coating 10 effects a smaller friction coefficient between the expansion sleeve and the expansion part 3 of the shaft 2 than the friction coefficient between the expansion sleeve 7 and an inner wall of a borehole, therefore a secure continuous expansion characteristic of the expansion anchor in a crack or tensile stress working area can be realized. Protrusions 11, 12 are formed at a front and a rear positions on the outer periphery of the expanse sleeve 7 for maintaining contact with the inner wall of the borehole, particularly in the broken zone during large displacement of the expansion anchor.
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