Boring or penetrating the earth – Bit or bit element – With helical-conveying portion
Reexamination Certificate
1999-11-24
2001-04-10
Tsay, Frank (Department: 3672)
Boring or penetrating the earth
Bit or bit element
With helical-conveying portion
C175S416000, C408S230000
Reexamination Certificate
active
06213232
ABSTRACT:
The invention relates to a drilling tool, in particular a rock drill according to the preamble of claim
1
.
PRIOR ART
Drilling tools and, in particular, rock drills consist generally of, a drilling head fitted with a carbide cutting plate, of a helical shank with a spiral conveying helix for drilling dust or drillings and of a clamping shank for inserting the drilling tool into a drive machine.
The spiral conveying helix of a rock drill is produced generally by cutting away chips, if appropriate also without cutting (for example, by rolling rollers), in order to introduce the conveying helix grooves into the generally cylindrical initial material. In this case, where rock drills are concerned, the main function of the conveying helix is to convey the material released by the carbide cutter, that is to say the drilling dust or else drillings, out of the drillhole. Cylindrical initial materials of this kind are available in a wide variety of dimensions, so that a narrow graduation of drilling diameters can be produced.
The known drilling tools are fundamentally based on the fact that the helical shank has a cylindrical initial cross section, since the introduction of one or more conveying helix grooves gives rise to continuous ridges of the conveying helix groove which lie on an outer cylindrical surface. This is intended to ensure that drilling proceeds quietly or with little vibration, with the conveying helix being guided accurately along the conveying helix ridges.
OBJECT OF THE INVENTION
The object on which the invention is based is to provide a drilling tool and, in particular, a rock drill, which has improved handling properties, as compared with conventional drilling tools, along with a drilling capacity which is at least equal to that of these drilling tools.
SOLUTION FOR ACHIEVING THE OBJECT AND ADVANTAGES OF THE INVENTION
Proceeding from a rock drill of the type initially designated, this object is achieved, according to the invention, by means of the defining features of claim
1
.
Advantageous developments and improvements of the drilling tool specified in the main claim are possible by virtue of the features listed in the subclaims.
The invention is based on the knowledge that an increased drilling capacity can be achieved by reducing the frictional losses and increasing the conveying capacity, in that the cross section of the initial material for the conveying helix is not circular, but is replaced by a preferably symmetric polygonal profile. When a conveying helix is cut into such a polygonal profile, the remaining ridges are composed of surface portions which are lined up with one another and which, in turn, form additional pockets for transporting the drilling dust. Markedly reduced wall friction is thereby established, since the ridge of the conveying helix does not have any surface contact, but at most linear contact. Furthermore, due to the alternately successive longitudinal edges of the surface portions on the ridges of the conveying helix, a kind of scraper effect is established, which likewise leads to a positive drilling result. Moreover, an improved conveying capacity for the drilling dust is established, since the longitudinal edges on the ridges act as an additional conveying edge or pushing edge which also pushes the drilling dust into the deeper grooves, so that jamming in the region of the ridges is avoided. The flattening of the surface portions on the ridges also increases the conveying volume during the drilling operation.
In a particularly advantageous version of the invention, the clamping shank is also designed as a polygonal profile in the manner of a polygonal course, that is to say the complete drilling tool consists of the same polygonal profile, in which conveying helix grooves are introduced by cutting away chips. Particularly when received into a commercially available three-jaw chuck of a percussion drilling machine or the like, the polygonal clamping shank brings about a positive takeup, so that spinning of the drilling tool, particularly also in the case of jaw chucks having a relatively low clamping force, for example due to wear or the like, is virtually ruled out.
A multiplicity of drill sizes can therefore be produced in various dimensions by means of commercially available polygonal profile bars merely by the introduction of conveying helix grooves, the clamping shank affording the advantage of positive takeup in the multijaw chuck. For this purpose, the polygonal profile bar must have, at least in the region of the clamping shank, clamping surfaces arranged so as to be offset by 120°.
In a particular refinement of the invention, the clamping shank may also have a cylindrical cross section, in order to adapt the clamping shank to the drill receptacle, for example in hammer drilling machines. For this purpose, extruded blanks are preferably used, which are provided in the region of the conveying helix as a polygonal profile and in the region of the clamping shank with a cylindrical profile. The clamping shank can then be adapted to the respective conditions for use, for example in hammer drilling machines, whilst the helical shank having the conveying helix described is produced by cutting away chips.
In a particular design, such an embodiment may be produced as an extruded blank or forged blank, so as to allow for any desired diameter variants and cross-sectional forms in the initial shapes with a polygonal profile in the region of the helical shank and with a, for example, cylindrical profile in the region of the clamping shank.
The helical shank and clamping shank may, however, also be connected to one another in their respective shapes by means of a suitable welding method (for example friction welding method, resistance welding method and the like).
REFERENCES:
patent: 2773672 (1956-12-01), Holmes et al.
patent: 4749051 (1988-06-01), Larsson
patent: 5096344 (1992-03-01), Fischer
patent: 331 438 (1958-09-01), None
patent: 887 631 (1953-08-01), None
patent: 2 045 896 (1972-03-01), None
patent: 43 06 981 (1994-09-01), None
patent: 0 361 189 (1990-04-01), None
patent: 628665 (1927-10-01), None
patent: 2035158 (1980-06-01), None
Hawera Probst GmbH
Morgan & Lewis & Bockius, LLP
Tsay Frank
LandOfFree
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