Hammer drill and method for deep drilling
AssigneeFraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorsSimon Hahn, Philipp Schroer, genannt Fleutert, Volker Wittig, Marian Bunk
Life of this patent
Estimating the term…
Abstract
A hammer drill is provided including at least one cylinder, in which at least one piston is mounted such that it can be moved axially between an upper and a lower end position, wherein the cylinder has at least one lower fluid supply, which can be cyclically supplied with a drive fluid, wherein the cylinder is closed with an upper cover and a lower cover, wherein, in the lower end position, the piston is in contact with an inner side of the lower cover and a ring gap is formed between the entire casing surface of the piston and the inner wall of the cylinder. A method for deep drilling using a hammer drill of this type is also provided.
Claims18
A hammer drill comprising
- at least one housing having a cylinder bore,
- a piston mounted in said cylinder bore such that said piston can move axially between an upper end position and a lower end position,
- at least one lower fluid supply adapted to cyclically supply the cylinder bore with drive fluid,
- an upper cover and a lower cover closing
- the cylinder bore at each end, wherein
- the piston is in contact with an inner surface of the lower cover in a lower end position, and wherein
- a ring gap is formed between an outer surface of the piston and an inner wall of the cylinder bore, wherein
- said ring gap has a gap height H which is greater than
- H=2·(Ra,cylinder+Ra,piston)+3·Dparticles, wherein
- Ra,cylinder and Ra,piston denote a mean roughness values of the inner wall of the cylinder bore and the outer surface of the piston, respectively and
- Dparticle denotes a maximum particle size in the drive fluid.
A method for deep drilling using a hammer drill with at least one housing having a cylinder bore, the method comprising:
- mounting a piston inside said cylinder bore such that said piston can move axially between an upper end position and a lower end position, wherein
- a ring gap is formed between an outer surface of the piston and an inner wall of the cylinder bore, wherein
- said ring gap has a gap height H which is greater than
- H=2·(Ra,cylinder+Ra,piston)+3·Dparticle, wherein
- Ra,cylinder and Ra,piston denote a mean roughness values of the inner wall of the cylinder bore and the outer surface of the piston, respectively and
- Dparticle denotes a maximum particle size in the drive fluid;
- closing the cylinder bore with an upper cover and a lower cover at each end;
- cyclically supplying a drive fluid to the cylinder bore by at least a lower fluid supply:
- letting the piston strike against an inner surface of the lower cover in the lower end position.
Dependencies are inferred from the claim text.