Helical drill bit for an auger of a ground excavation assembly, in particular for building excavated piles, and drilling method that uses such a bit

摘要

The helical drill bit defines a helical end section of a helical structure formed at its periphery by an auger of an excavation assembly, and it is associated or associable with a support portion of the auger. Such a support portion defines a proximal section of the helical structure, which has an extension substantially centered around a longitudinal axis (X-X). The helical drill bit is adapted to rotate about the longitudinal axis (X-X) together with the support portion so as to drill a hole in the ground. The helical end section extends around an extremity axis (Y-Y; Ψ-Ψ) that is not aligned relative to the longitudinal axis (X-X).

主权项

1. A helical drill bit for an auger of a ground excavation assembly, in particular for building excavated piles;
said excavation assembly including said auger and an external casing pipe defining an internal axial cavity such as to allow the auger to pass through it, wherein said auger and casing pipe are capable of sliding axially with respect to one another, said auger being connected to an upper drive head and said casing being connected to a lower drive head thereby allowing said auger and said casing to rotate independent from each other; said auger forming at its periphery a helical or Archimedean screw-type structure and having a support portion defining a proximal section of a helical structure, the extension of which is substantially centered around a longitudinal axis (X-X) so that the spirals of the auger wrap around said longitudinal axis (X-X); said helical drill bit defining at least one helical lower end section of said helical structure, being associated or associable with said support portion, and being arranged to rotate about said longitudinal axis (X-X) together with said support portion so as to drill a hole into a ground; said lower helical end section extending substantially centered around an axis of eccentricity (Y-Y; Ψ-Ψ) offset from said longitudinal axis (X-X) so that the spirals of the drill bit defined by said lower helical end section wrapped around said axis of eccentricity (Y-Y; Ψ-Ψ) are not aligned to the spirals of the drill bit defined by said support section wrapped around said longitudinal axis (X-X) wherein said helical drill bit further defines an intermediate section of said helical structure of the auger; said intermediate section being substantially centered around the longitudinal axis (X-X) and being located between the proximal section of the auger and the lower end section of the helical drill bit wherein the radial size of the spirals of the drill bit defined by said intermediate section, when observed in a plan view relative to the longitudinal axis (X-X), is smaller than the radial size of the helical structure defined by said auger, the transversal shape of said intermediate section remaining within the transversal shape defined by said proximal section and by said lower end section.