US-20260124787-A1 - MASONRY DRILL HEAD

US20260124787A1US 20260124787 A1US20260124787 A1US 20260124787A1US-20260124787-A1

Abstract

A masonry drill head is made from a sintered cemented carbide. The masonry drill head has an at least section-wise planar joining end for heat induced joining to a shaft, a working end for shattering masonry material under a percussive motion, at least two conveying webs each emerging from the joining end and at least two conveying grooves each extending between two of the conveying webs. A cross-sectional solid material area of the masonry drill head increases towards the joining end, such that a masonry material debris intake of at least one of the conveying grooves increases towards the working end.

Inventors

Robin BUONO
Cecilio LASCHIAZZA
Michael Magin
Luca PICCO

Assignees

CERATIZIT HARD MATERIAL SOLUTIONS S.A R.L.
CERATIZIT LUXEMBOURG S.A.R.L.

Dates

Publication Date: 20260507
Application Date: 20230914
Priority Date: 20220923

Claims (17)

1 - 15 . (canceled)
16 . A masonry drill head, comprising: an at least section-wise planar joining end for heat induced joining to a shaft; a working end for shattering masonry material under a percussive motion; at least two conveying webs each emerging from said at least section-wise planar joining end; at least two conveying grooves each extending between two of said conveying webs, wherein a cross-sectional solid material area of the masonry drill head increases towards said at least section-wise planar joining end, such that a masonry material debris intake of at least one of said conveying grooves increases towards said working end; and the masonry drill head being made from a sintered cemented carbide.
17 . The masonry drill head according to claim 16 , wherein said cross-sectional solid material area of the masonry drill head increases towards said at least section-wise planar joining end by a thickening of at least one of said conveying webs towards said at least section-wise planar joining end.
18 . The masonry drill head according to claim 16 , wherein said cross-sectional solid material area of the masonry drill head increases towards said at least section-wise planar joining end by a thickening of at least two of said conveying webs towards said at least section-wise planar joining end.
19 . The masonry drill head according to claim 16 , wherein said at least two conveying webs are two of three or four conveying webs emerging from said at least section-wise planar joining end.
20 . The masonry drill head according to claim 16 , wherein said at least two conveying webs touch an outer working circle at said at least section-wise planar joining end, wherein said cross-sectional solid material area at said at least section-wise planar joining end lies in a range from 40% to 90% of an area of the outer working circle.
21 . The masonry drill head according to claim 16 , wherein at least one of said conveying webs is twisted resulting in a twisted conveying web.
22 . The masonry drill head according to claim 21 , wherein said twisted conveying web has a twist angle in a range from 15° to 45°.
23 . The masonry drill head according to claim 16 , wherein said sintered cemented carbide has a Vickers hardness is a range from 1250 HV10 to 1700 HV10 .
24 . The masonry drill head according to claim 16 , wherein said working end has a percussion knob protruding axially outwards.
25 . The masonry drill head according to claim 16 , wherein said sintered cemented carbide has a Vickers hardness is a range from 1300 HV10 to 1500 HV10 .
26 . A masonry drill head, comprising: an at least section-wise planar joining end for heat induced joining to a shaft; a working end for shattering masonry material under a percussive motion; at least two conveying webs each emerging from said at least section-wise planar joining end; at least two conveying grooves each extending between two of said conveying webs, wherein at least one of said conveying webs is twisted more on parts of said at least section-wise planar joining end than on parts of said working end resulting in a twisted conveying web; and the masonry drill head being made from a sintered cemented carbide.
27 . The masonry drill head according to claim 26 , wherein said twisted conveying web has a twist angle which lies in a range from 15° to 45° on parts of said at least section-wise planar joining end and in a range from 0° to 15° on parts of said working end.
28 . The masonry drill head according to claim 26 , wherein said at least two conveying webs are two of three or four conveying webs emerging from said at least section-wise planar joining end.
29 . A masonry drill head, comprising: an at least section-wise planar joining end for heat induced joining to a shaft; a working end for shattering masonry material under a percussive motion; at least two conveying webs each emerging from said at least section-wise planar joining end; at least two conveying grooves each extending between two of said conveying webs, wherein a cross-sectional solid material area of the masonry drill head increases towards said at least section-wise planar joining end, such that a masonry material debris intake of at least one of said at least two conveying grooves increases towards said working end, wherein at least one of said conveying webs is twisted more on parts of said at least section-wise planar joining end than on parts of the working end resulting in a twisted conveying web; and the masonry drill head being made from a sintered cemented carbide.
30 . The masonry drill head according to claim 29 , wherein said at least two conveying webs are two of three or four conveying webs emerging from said at least section-wise planar joining end.
31 . The masonry drill head according to claim 29 , wherein the masonry drill head is welded to a steel shaft.

Description

The present invention relates to masonry drill heads according to the preambles of claims 1, 10 and 13. Masonry drill heads are designed to drill holes into masonry materials, e.g., concrete, brick stones, granite, under an axial percussive motion by which the masonry material is shattered into debris, usually shattered into a dust-like state, and an additional conveying rotatory motion by which the debris is transported out of the hole. Thus, masonry drill heads are different from metal cutting drill heads because metal cutting drill heads are designed for scraping a cutting edge into a metal surface under continuous chip formation and continuous chip transport. In other the words the primary material removal mechanisms are different. Masonry drill heads are also different from wood working drill heads, since also wood working drill heads have a different primary material removal mechanism not employing a percussive motion. The drill bit shown in EP 1 865 144 A 1 does not optimally transport masonry material debris out of a hole which results in longer drilling times and reduced lifetimes of the drill bit. The objective of the present invention is to provide a masonry drill head which transports masonry material debris better out of a hole and has at the same time both better joining properties for heat induced joining to a shaft. The objective is solved by a masonry drill head according to claim 1. The masonry drill head according to a claim 1 is made from a sintered cemented carbide and has an at least section-wise planar joining end for heat induced joining to a shaft, a working end for shattering masonry material under a percussive motion, at least two conveying webs each emerging from the joining end and at least two conveying grooves each extending between two of the conveying webs, wherein a cross-sectional solid material area of the masonry drill head increases towards the joining end, such that a masonry material debris intake of at least one of the conveying grooves increases towards the working end. Thus, the masonry material debris intake increases opposite to the increase of the cross-sectional solid material area. The masonry drill head according to claim 1 improves masonry material debris transport away from the working end while at the same time geometrically strengthening the joining end and improving a masonry material debris exit on parts of the joining end allowing for an improved joining to a shaft. The cross-sectional solid material area is formed by the sintered cemented carbide of the masonry drill head, i.e., the “air” area encompassed by the conveying grooves is not part of the cross-sectional solid material area. Examples for “heat induced joining” are welding, brazing and soldering. Preferably the joining end is free of inward and/or outward protrusions since this improves heat induced joining, especially welding, on a shaft with a shaft front side. The joining end remains at least section-wise planar when it has a circumferentially extending chamfer. Typically, the working end covers each of the conveying webs by a roof-shaped top-structure having a working edge as a ridge-line from which an inclined front leading surface and an inclined front trailing surface extend towards the joining end on both side of the working edge. “leading” and “trailing” regard to a given rotation direction of the masonry drill. The leading front surfaces and trailing front surfaces are designed and arranged for a front-side percussion contact with the masonry material. Said roof-shaped top-structure is a monolithic part of the masonry drill head. The sintered cemented carbide has a carbide skeleton structure formed by carbide grains, e.g., tungsten carbide grains, sintered together and has skeleton spaces filled with a metallic base alloy; base alloy means that from 70 weight percent to 100 weight percent with respect to the base alloy composition are formed by a metallic alloying element, e.g. cobalt, nickel or iron, or by two metallic alloying elements, e.g., cobalt+nickel, cobalt+iron, nickel+iron, or by three metallic alloying elements, e.g., cobalt+nickel+iron. Preferably, the base alloy has chromium has a minor alloying element. The carbide, the carbide grains are made from, preferably tungsten carbide, amounts preferably from 85 weight percent to 95 weight percent, more preferred from 90 weight percent to 94 weight percent, most preferred from 91 weight percent to 93 weight percent with respect to the entire sintered cemented carbide composition. Preferred embodiments of the masonry drill head according to claim 1 will be described in the following. According to a preferred embodiment the cross-sectional solid material area of the masonry drill head increases towards the joining end by a thickening of at least one of the conveying webs towards the joining end. This is advantageous since the material debris intake increases towards the working end without thereby geometrically weakening the ma