Core hole drilling

from Wikipedia, the free encyclopedia

The core drill holes , or short coring be performed with rotating cylindrical hollow bodies, known as drill bits , core sample , hollow drill or core (hole) drill . When drilling in wood, one speaks of a hole saw .

A common application is in construction when drilling through masonry or concrete .

With hard materials and large diameters, core drilling has advantages over conventional drilling, since the core remains inside the drill bit and does not have to be removed, so that less wear occurs on the drilling tool and faster advance is possible.

Drilling of mineral materials

Core of a core hole drilling through concrete

Core drill bits for brick , concrete and natural stone are mostly set with diamonds in order to be able to penetrate hard rock and concrete with hard aggregates . Circular diamond trimmings are only common when cutting earthenware (tiles). Diamond drill bits with individually attached diamond segments are better suited for faster removal of the crushed material in deeper bores. The diamond trim is attached to the steel body by sintering , brazing or laser welding . Smaller, hand-held drill bits are often equipped with individual carbide teeth, or sprinkled with granules along the cutting edge.

Since with deeper bores the removed material has to be transported out of the drilling gap and, depending on the material, the resulting frictional heat has to be dissipated, the drill bit is usually flushed with water, which passes through the hollow axis of the drill to the work area and when it flows back on the outside of the drill bit the crushed particles with it.

In the case of blind holes , the drill core may have to be broken out at the end of the drilling work and removed with special, flat core pliers.

In contrast to drilling holes with a hammer drill , core hole drilling is quieter and vibration-free. The drilled hole produced is also significantly more uniform and smooth-walled. For bores with a diameter of more than 50 mm, the drill is usually guided in a drill stand, as tilting can block the drill bit, giving the device a strong angular momentum that is limited by a safety clutch, but not completely prevented.

In the construction sector, it is now common practice to create round openings for electrical and sanitary supply and disposal lines as well as supply and exhaust air pipes after pouring concrete walls and ceilings with the core hole drilling machine, instead of creating these openings by inserting placeholders in the formwork , as these can hinder the pouring and spreading of the fresh concrete.

Drilling of metallic materials

The drilling with drill core in steel is particularly useful in mobile use of magnetic drills common, since due to the smaller cutting a smaller pressing force is required surface that does not overwhelm the holding force of the magnet.

Exploratory drilling

For the investigation of the subsoil and for geological and archaeological boreholes, drill cores are taken from rock, sediment or ice ( ice drill core ) in order to obtain information about the nature of the subsoil.

Web links

Commons : Hollow Core Drill  - Collection of images, videos and audio files
  • Information brochure (PDF) from Comdrill on core drilling methods for deep drilling in geology, accessed in February 2016
  • Instructions (PDF) for carrying out core drilling in mineral materials, GDI-Herdecke; accessed in Dec. 2015

Individual evidence

  1. Tips on drilling practice from GDI Diamant Technik, Herdecke, accessed in February 2016
  2. core hole drilling. In: Baulexikon. dornbach.com, accessed on March 17, 2015 .