The self-drilling bolt is a hollow rod with coarse thread which is a design similar to the drill rod. The bar, being hollow inside, allows passage of water / flushing air during drilling; as well as, injecting grout or resin. This bar carries at its end a bit or cutting tool with several holes sweeping, which is lost in the perforation process.
The bar to the being threaded along its length allows the coupling successive bars using connectors or couplets.
The self—piercing bolt consists of a hollow rod with thick thread whose design is similar to that of a drilling rod. The rod, which is hollow, allows water/purge air to circulate during drilling; it also allows cement grout or resin injections. This rod has a bit or cutting tool with various mapping drills, which is lost in the drilling process.
The rod, which is twined across its length, allows rods to be successively coupled through the use of connectors or couplets.
The design of the self-drilling bolt considered a cold rolling to form a standard thread profile (R25, R32, R38 and R51 and T76). As accessory, a plate and nut are used.
In mining, tunneling and specializing civil engineering are used as reinforcement bolts.
A self-drilling bolt is comprised of:
- A hexagonal nut.
- A support plate.
- Extension couplings, consisting of several sections of bolt.
- Hollow bar.
- Sacrificial rod.
Applications and uses
They are typically employed in extremely poor rock and soil susceptible to collapse as an alternative casing drilling.
Among the applications include: micropiles, soil nailing, slope stabilization, consolidation, marchiavanti, etc.
Advantages
- High quality for a limited life.
- Major length of anchoring installed.
