CA1324013C - Masonary drill tip with strong and chamfered cutting edges - Google Patents
Masonary drill tip with strong and chamfered cutting edgesInfo
- Publication number
- CA1324013C CA1324013C CA000557950A CA557950A CA1324013C CA 1324013 C CA1324013 C CA 1324013C CA 000557950 A CA000557950 A CA 000557950A CA 557950 A CA557950 A CA 557950A CA 1324013 C CA1324013 C CA 1324013C
- Authority
- CA
- Canada
- Prior art keywords
- tip
- flank
- intersection
- cutting
- chamfer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000005520 cutting process Methods 0.000 title claims abstract description 58
- 239000004575 stone Substances 0.000 claims abstract description 4
- 230000006872 improvement Effects 0.000 claims description 5
- 239000000463 material Substances 0.000 abstract description 7
- 238000005553 drilling Methods 0.000 abstract description 4
- 239000002245 particle Substances 0.000 description 7
- 230000035515 penetration Effects 0.000 description 7
- 101150078000 arid3a gene Proteins 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B51/00—Tools for drilling machines
- B23B51/02—Twist drills
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/44—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts
- E21B10/445—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts percussion type, e.g. for masonry
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
- E21B10/58—Chisel-type inserts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B2226/00—Materials of tools or workpieces not comprising a metal
- B23B2226/75—Stone, rock or concrete
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B2251/00—Details of tools for drilling machines
- B23B2251/14—Configuration of the cutting part, i.e. the main cutting edges
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B2251/00—Details of tools for drilling machines
- B23B2251/50—Drilling tools comprising cutting inserts
Abstract
ABSTRACT OF DISCLOSURE
A cutting tip to be carried by a drill bit for rotation in a first direction and useful in drilling holes in stone and masonry materials wherein the tip is planar and has a point defined by first and second surfaces intersecting at a point and third and fourth flank edges extending generally parallel to the longitudinal axis and where the leading edge of at least one of the flank edges. determined by the direction of rotation, is chamfered.
A cutting tip to be carried by a drill bit for rotation in a first direction and useful in drilling holes in stone and masonry materials wherein the tip is planar and has a point defined by first and second surfaces intersecting at a point and third and fourth flank edges extending generally parallel to the longitudinal axis and where the leading edge of at least one of the flank edges. determined by the direction of rotation, is chamfered.
Description
~ 3240 ~ ~
BACKGROUN~ OF THE INVENTION
The present invention relates to drills and more particularly to a cutting tip which is useful in connection with a masonry drill assembly including a fluted shaft to receive t~le tip ann carry away the chips generated by rotation of the cutting tip.
lt is known in the art that pointed cutting tips are commonly utili2ed in connection with masonry drills where the cutting tip is inserted into the end of a helically fluted shaft which is utili~ed to pick up and carry away the chips generated by the rotation of the tip.
The cutting is dccomplished by means of rotation of the tip as previously described, in a selected direction of rotation, where in tlle prior art a cutting edge is established on each side of the chisel edge of the tip by the intersection of d leading face of the tip as defined by the direction of rotdtion dnd d Srontmost surface of the tip as defined by the direction of penetration, and where a flank edge pardllel to the axis of penetration of the drill is established on each side of the point by the intersection of d leading face of tl-e tip and a sidemost surface of the tip pardllel to the axis of penetration of the tip, and where the intersections of said cutting edges and said flank edges establish poin~s of the tip on each side of the chisel edge, said points being tl~e locus of the initiation of and ~he most rapid progress of the chipping and attrition which causes the wear of the cutting edges and flank edges during cutting. ' Prior art drill tips of the foregoing configuration are known and have been manufactured by the Vermont American corporation as well as many others. Prior art drills are ~nown that incorporate a chamfer of the cutting edge for the purpose of increasing resistance to gross chipping, but at the exDense of increased reSiStdnCe to penetration. ~o one skilled in tlle art the said chaInfer produces whdt is known dS d "negative rake." ~here are no prior art devices that have uti1i2ed a chamfer to produce a negative rake on a -flank edge of a masonry drill tip as provided by present invention.
One example of a prior art masonry drill bit is shown in U.S. Patent number 4,026,327 wllere a rotary percussive drill bit is illustrated. In U.S. Patent number 4,243,113 a drill bit somewhat similar to one arrangement provided by the present invention is shown but without the chamfered edges.
Other features of drill bits are shown in U.S. Patents 3,106,972 and 3,555,937 as well as British Patent 1,062,158 but non show a straicht forward masonry drill.
suMMARr OF THE INVENTlOh The preSent invention provides new useful, and - inexpensive arrangements for improving the characteristics of drill bits for stone and masonry, and particularly for increasing the wear life of a drill bit utili~ed for drilling holes in hard britt1e materials such as masonry and rock and reducing the force required to advance the drill bit.
In accordance with one feat"re of the present invention it has been found tl,at in the case of masonry drill bits and in particular~ drill bits of planar configuration having a point and flank edges where the cutting edges are advanced into the mdterial to be cut as the drill advances, drill bit failure initiateS most often at the intersectionS
of the cutting and flank edges. Normally the wear then develops a10ng tl-e leading cutting edges and the flank edges and causes a receeding of the points of intersection and a rounding of the two edges. Progression of the wear pattern progressively increases the force required for penetration until the force required is greater than the force available.
It llas been une~Dectedly found that structures withjn the scope of t~le prese~llt invention direct the ~ear at the intersections of tlle ClItting edges and the respective flank edges away from said intersections so that the result is more uniform wear over a grea~er length of edge and a geometry that prcvides qreater structual resistance to chipping aIld major fractule . I
Arrangements within the scope of the present invention further provide dril1 bits with strengthened flank edges which have been found to unexpectedly greatly increase useful drill iife.
Further it has been unexpectedly found that by chamfering the flank edges the effectiveness of the drill bit is improved in masonry and stone drilling.
In summary the present invention provides a cutting tip to be carried by a drill bit for rotation in a first direction and useful in drilling holes in for example masonry and rock mateIials where the tip is planar and has a chisel edge defined by first and second cùtting edges intersecting with tlle chisel edge and third and fourth flank edges where tlle leading edge of at least one of the flank cutting edges determined by the direction of rotation is chamfered at the leading edge.
~hile several arrangements within the scope of the preSent invention are shown in the accompanying figure it will be understood that various other arrangements also within the scope of the present invention will occur to those skilled in the art in view of the reading of the disclosure set forth hereinafter.
BRIEF DESCRIPTION OF T~E DRAWINGS
Examples in accordance with the present invention and the prior art are shown in the accompanying drawings where:
Figure I is a perspective view of an example of a drill tip in accordance with the present invention located in a drill shank;
Figure 2 is d plan view of a prior art cutting tip;
Figure 3 is an elevational view of ~he cutting tip shown in Figure 2;
Figure 4 is a view taken along a plane passing through line 4-4 of Figure 3;
Figure S is a view taken along a plane passing through lines S-S of Figure 3;
Figure 6A-6B are plan views of other prior art drill bits;
Figure 7 is a perspective view of another example of a prior art drill tip;
Figu~es 8A and ~a are plan and elevational illustrations of an example of one drill tip arrangement in accordance with the present invention;
Figures 9A-98 are plan views of other drill tip arrangment within the scope of the present invention; and Figu~-e 10 is a graphic illustrating the comparison of the characteristics of drill bits within the scope of the present invention with prior art drill bits.
¦ DETAlLEi) DESCRIPTION OF rHE DRAwlNGS
¦ Referring first to Figure 1 a perspective illustration ¦ of d cutting tip within the scope of the preSent invention ¦ located in a drill 5hank as generally well known in the art.
¦ In Figure I a tip 1 in this case a tip with;n the scope of ¦ the present invention as described hereinafter ;s 10cated in ¦ a fluted shank member 26 and can be of for example ¦ tungsten carbide.
l Flutes 27 helical1y encircle shaft 26 and are provided ¦ for the reIlloval of clliI)s generated by the cutting edges of ¦ the tip I dS the 5IIdrt 26 rotates while being thrust by a ¦ feed force F into the nateridl being drilled.
l Figures 2-6B illustrdte drill tips dS known in the ¦ prior art. Figu e 2 is plan view of an example of one prior ¦ art tip~ and Figule 3 is ar elevational view of the same tip hich is a solid defined Iy seveI- surfaces. Surfaces SA and 7A are symmetrically disposed on each side of a centerline of rotation of the tiV so that the intersection creates a l chisel edge 3 where the surfaces 5A 7A intersect at an ¦ angle less thall 180. Likewise the intersection of surface SA with surface 4 defines cutting edge S while the intersection of surface 7A with surface 4 defines cutting edge 7. In tl-e arrangement shown in Figures 2 and 3 surfaces SA and 7A extend between surfaces 4 and 6 at an angle B for example 15 to 30~ as illustrated in Figures 4 and S to define the clearances behind the cutting edges S
and 7 defined by tlle intersection of surface SA 7A and lateral surfaces 6 and 4 respectively as shown.
In the prior art arrangement il1ustrat~d in Figure I
and 2 flank surfaces IOA and llA which may be planar 3s shown in Figure 2 are provided and flank edges IO and II are provlded by the intersectlon of surfaces IOA, llA bnd surfaces 6 and 4 respectively. Surfaces lOA and IIA may be located at an ang1e C wit~ respect to surfaces 6 and 4 to provide clearance bellind the flank tips IO and II as shown.
It is obvious that the extensions of cutting edges S
and 7 terminate at their intersection with flank edges IO
and Il to create points I3 and I4. In the case of a new drill tip or dril1 tip with no wear, the cutting action is performed by the cutting edges S and 7 and the diameter of the hole is determined hy tlle distance between points I3 and I4 where flank edges IO and II merely follow points I3 and 14. The cutting tip is of a hard material for example a conglomerate of smdll hard partic1es appropriately bonded together, for example, cemellted carbide which is cùrrently ; used.
Examining the fine structure at the points I3 and I4 it will be recognized t~lat the outermost hard particle at each is bonded to t~le body of the tip over less of its surface than are the next adjacent particles and that the proportion of the particle bonded to the body of the tip is a direct function of the solid angle bounded by surfaces 7A 6, IOA
and similarly by SA, 4, llA. For example, as shown in Figure 7 particle IS of which point I4 is one corner is bonded to the body by three (3) surfaces whereas particle I6 is bonded by four (4) surfaces. Obviously particle IS at point I4 5holI1d be more easily dislodged. -~ 1 324~1 3 ¦ The partic1es 15 and I6 can represent single hard ¦ partic1es or they can represent an aggregate of partic1es.
¦ During wear ùoth sing1e partic1es and aggregates of ¦ partic1es are dis10dged. Whether it is a single partic1e or ¦ the aggregate of partic1es that is dis10dged in a spec,ific ¦ event is dependent Dn a mu1ip1icity of conditions and events ¦ inc1uding constant fo~ces, impact forces, direction of ¦ forces, inhomogeneities in the material being cut, ¦ inhomogeneities in the cutting tip material, size and ¦ hardness of the cuttings from the workpiece relative to the ¦ size and hardIless of the hard particles and to the thickness ¦ and hardness of the borlding material in the cutting tip.
¦ Whatever the preciSe combination of wear mechanisms the ¦ resultant wear initiates at points I3 and 14 and growS.
¦ Ultimately, cutting edges S and 7 are blunted and flank ¦ edges I0 and lI become tapered so that the cutting tip ¦ becomes wedge shaped when seen in the elevation view. These ¦ changes cause an increased thrust required to penetrate the ¦ workpiece unti1 furtl,er use of the drill tip is no longer l practical.
In accordance with one feature of the present invention it has been unexpectedly found that the physical strength of the cu~ting edges S and 7 at their extremities iS a 1arger l than expected proportion of the total wear mechanism and ¦ that strengtIlening the extreme portions of cutting edges S
and 7 significantly increases the useful life o- the drill.
Other prior art configuration are also known as shown in Figures 6A and 6B. In Figure 6A the 'flank surfaces are l composed of two semicirclIldr surfaces 17 and I8 having a diameter D2 equal to the diameter of the hole to be drilled as the drill is rotated in direction F so the drill bit flank edge is congruent to the surface of revolution caused by drill rotation. Chamfered surfaces 19 and 20 are angularly disposed so that their trailing edges clear the surface of revolution. Figure 6B illustrates an arrangement where semicircular flank surfaces 21, 22 are provided with diameter D2 which is the diameter of the drill bit, so the total flank surface are congruent to the surface of revolution of the bit.
Referring now to Figure 1 which shows an assembly using a drill bit within the scope of the present invention shown in enlarged view in Figures 8A, 8B a principal feature of drill tips within the scope of the present invention as shown in Figure 8A, 8B is that the flank edges lOA and llA, shown in Figure 2, and surfaces 17, and 18 shown in Figure 6A and surfaces 21, 22 shown in Figure 6 are replaced by chamfer surfaces 43, 44.
In accordance with a principal feature of the present invention, the flank surfaces lOA, llA of the example in the prior art shown in Figure 3 are modified by chamfers 43 and 44 as shown to create new edges 46, 47 and new edges 52 and 53 and a new set of cutting points 57, 58, 59, and 60 as shown in the Figures where points corresponding to the points 59, 60 were not provided by the prior art. As shown in Figure 8A, the chamfered surfaces 43 and 44 respectively form an included angle I with the plane of their adjacent flank surface 62 or 61 of from 7.5 132~ol3 degrees to 70 degrees. Preferably, the angle I is 45 degrees.
~ S~
Similarly the ~n~ angles having apexes at 57, 58, 59, 60 are larger than those having apexes at 13 or 14 of the prior art example and are bonded to the body of the cutting tip over a larger proportion of their surface than are the corresponding extreme elements at points 13 and 14 in the cutting tip shown in Figures 2 and 3. It has been found that this change in geometry results in stronger physical structures at the locations of maximum wear due to chipping in a micro or micro form.
A further strengthening consequence of the invention derives from the changed angle of attack of cutting edges 63 and 64 as opposed to that of edges 5 and 7 of Figures 2 and 3.
Arrangements also within the scope of the present invention are also shown in Figures 9A-9B. In Figure 9A a tip is provided having a lateral surfaces 70, 71 with flank edges 72, 73 which have a diameter D3 corresponding to the diameter of the drill bit. Chamfers 74, 75 at angles F and G provide the advantages of the present invention by defining cutting points 76-81 similar to the cutting point illustrated in Figures 8A, 8B. The chamfered surfaces 74 and 75 respectively form an included angle F or G with the 25 plane of their adjacent flank surface 70 or 71 of from 7.5 degrees to 70 degrees. Preferably, each of the angles F
and G is 45 degrees.
l324nl3 Figure 9B illustrates another possible arrangement within the scope of the present invention where lateral edges 92, 93 are provided along with a semicircular flank edges 82, 83 having a diameter D4 equal to the drill bit diameter and where the edges are chamfered at 84, 85 in an arc pattern with the length of the chamfer less than the length of the whole flank edge to define points 86 91.
In general the chamfer surfaces within the scope of the present invention which define the cutting tip faces and points can be symmetrical relative to the center of rotation or they can be nonsymmetrical, they can be the full length of the flanks or they can extend only for a part of the lla .~
L~
. C ~r~yt~ of the flanks as shown or they can be tilted relative , to the axis of rotation of tlle drill to produce a triangular chamfer surface. The chamfers can be 'ncorporated in a design of the cutting tip wherein the flanks are disposed to provide clearance relative to the cylindrical surface of rotation of the drill or in tl,e design of cutting tip wherein tl,e f1anks coincide with the cylindrica1 surface of rotatio" of the drill or in t~le design of cutting tip wherein tl,e flanks are a combination of clearance and coincidence relative to the surface of rotation of the drill Drill bits incorporating features of devices within the scope of the present invention were tested in comparison with cutting tips of various prior art configurations but uniformly without tl,e chamfered leading edges of the flank surfaces provided by devices within the scope of the present invention as described hereinbefore. The dril1 bits incorporating cemented carbide tips having configurations within the scope of the present invention were compared with the dril1 bits manufactured by other manufacturers providing a somewhat similar tip configuration but in no case providing the additiona1 points as described hereinbefore.
From the testing it WdS conc1uded that as the angle is increased from 7,5D improvement is noted and that the depth of the chamfer can be between 1/5 and 3/4 of the de~th of the tip preferably about l/3.
Tests were cond,lcted with three materials, namely, pressure c~st concrete with crushed aggregate, concrete with gravel aggregate anll granite at various feed forces. It waS found that drill tips in accordance with the present invention provide superior results illustrated by superior rate of decrease in penetration rate over that of comparison drills and the rdte of wear was diminished with the result that the useful life of the drill was substantially improved, all as shown in Figure lO which is an illustration of comparison of the penetration rate of a drill point referenced to the tota1 depth of drilled holes. The superiority of devices within the scope of the present invention is clearly illustrated.
while all of the reasons for the superiority of drill bits within the scope of the present invention are not fully understood it is believed that dt least a portion of the improvement arises because the cutting forces are divided dmong several points ~hich because of the configuration are stronger dS previously described. Some improvement also arises because tl-e cutting edges are oriented to direct the cutting forces into the body of the tip rather than tdngentidlly to the arc of the cutting path as is the case with prior art tips. Furti~er, by redirecting the cutting forces the strength of the cutting edges are greatly enhanced. Some improvement may also be achieved because the overall lengths of the cutting edges are increased reducing the cutting force per unit length of cutting edge.
l It wil1 be understood tl~dt the foregoing are but a few examples o~ arrangements within the scope of the present invention and other drrangements also within the scope of the present iI~ventioll will occur to those skilled in of the art upon reading tI,is disclosule set forth hereinbefore.
BACKGROUN~ OF THE INVENTION
The present invention relates to drills and more particularly to a cutting tip which is useful in connection with a masonry drill assembly including a fluted shaft to receive t~le tip ann carry away the chips generated by rotation of the cutting tip.
lt is known in the art that pointed cutting tips are commonly utili2ed in connection with masonry drills where the cutting tip is inserted into the end of a helically fluted shaft which is utili~ed to pick up and carry away the chips generated by the rotation of the tip.
The cutting is dccomplished by means of rotation of the tip as previously described, in a selected direction of rotation, where in tlle prior art a cutting edge is established on each side of the chisel edge of the tip by the intersection of d leading face of the tip as defined by the direction of rotdtion dnd d Srontmost surface of the tip as defined by the direction of penetration, and where a flank edge pardllel to the axis of penetration of the drill is established on each side of the point by the intersection of d leading face of tl-e tip and a sidemost surface of the tip pardllel to the axis of penetration of the tip, and where the intersections of said cutting edges and said flank edges establish poin~s of the tip on each side of the chisel edge, said points being tl~e locus of the initiation of and ~he most rapid progress of the chipping and attrition which causes the wear of the cutting edges and flank edges during cutting. ' Prior art drill tips of the foregoing configuration are known and have been manufactured by the Vermont American corporation as well as many others. Prior art drills are ~nown that incorporate a chamfer of the cutting edge for the purpose of increasing resistance to gross chipping, but at the exDense of increased reSiStdnCe to penetration. ~o one skilled in tlle art the said chaInfer produces whdt is known dS d "negative rake." ~here are no prior art devices that have uti1i2ed a chamfer to produce a negative rake on a -flank edge of a masonry drill tip as provided by present invention.
One example of a prior art masonry drill bit is shown in U.S. Patent number 4,026,327 wllere a rotary percussive drill bit is illustrated. In U.S. Patent number 4,243,113 a drill bit somewhat similar to one arrangement provided by the present invention is shown but without the chamfered edges.
Other features of drill bits are shown in U.S. Patents 3,106,972 and 3,555,937 as well as British Patent 1,062,158 but non show a straicht forward masonry drill.
suMMARr OF THE INVENTlOh The preSent invention provides new useful, and - inexpensive arrangements for improving the characteristics of drill bits for stone and masonry, and particularly for increasing the wear life of a drill bit utili~ed for drilling holes in hard britt1e materials such as masonry and rock and reducing the force required to advance the drill bit.
In accordance with one feat"re of the present invention it has been found tl,at in the case of masonry drill bits and in particular~ drill bits of planar configuration having a point and flank edges where the cutting edges are advanced into the mdterial to be cut as the drill advances, drill bit failure initiateS most often at the intersectionS
of the cutting and flank edges. Normally the wear then develops a10ng tl-e leading cutting edges and the flank edges and causes a receeding of the points of intersection and a rounding of the two edges. Progression of the wear pattern progressively increases the force required for penetration until the force required is greater than the force available.
It llas been une~Dectedly found that structures withjn the scope of t~le prese~llt invention direct the ~ear at the intersections of tlle ClItting edges and the respective flank edges away from said intersections so that the result is more uniform wear over a grea~er length of edge and a geometry that prcvides qreater structual resistance to chipping aIld major fractule . I
Arrangements within the scope of the present invention further provide dril1 bits with strengthened flank edges which have been found to unexpectedly greatly increase useful drill iife.
Further it has been unexpectedly found that by chamfering the flank edges the effectiveness of the drill bit is improved in masonry and stone drilling.
In summary the present invention provides a cutting tip to be carried by a drill bit for rotation in a first direction and useful in drilling holes in for example masonry and rock mateIials where the tip is planar and has a chisel edge defined by first and second cùtting edges intersecting with tlle chisel edge and third and fourth flank edges where tlle leading edge of at least one of the flank cutting edges determined by the direction of rotation is chamfered at the leading edge.
~hile several arrangements within the scope of the preSent invention are shown in the accompanying figure it will be understood that various other arrangements also within the scope of the present invention will occur to those skilled in the art in view of the reading of the disclosure set forth hereinafter.
BRIEF DESCRIPTION OF T~E DRAWINGS
Examples in accordance with the present invention and the prior art are shown in the accompanying drawings where:
Figure I is a perspective view of an example of a drill tip in accordance with the present invention located in a drill shank;
Figure 2 is d plan view of a prior art cutting tip;
Figure 3 is an elevational view of ~he cutting tip shown in Figure 2;
Figure 4 is a view taken along a plane passing through line 4-4 of Figure 3;
Figure S is a view taken along a plane passing through lines S-S of Figure 3;
Figure 6A-6B are plan views of other prior art drill bits;
Figure 7 is a perspective view of another example of a prior art drill tip;
Figu~es 8A and ~a are plan and elevational illustrations of an example of one drill tip arrangement in accordance with the present invention;
Figures 9A-98 are plan views of other drill tip arrangment within the scope of the present invention; and Figu~-e 10 is a graphic illustrating the comparison of the characteristics of drill bits within the scope of the present invention with prior art drill bits.
¦ DETAlLEi) DESCRIPTION OF rHE DRAwlNGS
¦ Referring first to Figure 1 a perspective illustration ¦ of d cutting tip within the scope of the preSent invention ¦ located in a drill 5hank as generally well known in the art.
¦ In Figure I a tip 1 in this case a tip with;n the scope of ¦ the present invention as described hereinafter ;s 10cated in ¦ a fluted shank member 26 and can be of for example ¦ tungsten carbide.
l Flutes 27 helical1y encircle shaft 26 and are provided ¦ for the reIlloval of clliI)s generated by the cutting edges of ¦ the tip I dS the 5IIdrt 26 rotates while being thrust by a ¦ feed force F into the nateridl being drilled.
l Figures 2-6B illustrdte drill tips dS known in the ¦ prior art. Figu e 2 is plan view of an example of one prior ¦ art tip~ and Figule 3 is ar elevational view of the same tip hich is a solid defined Iy seveI- surfaces. Surfaces SA and 7A are symmetrically disposed on each side of a centerline of rotation of the tiV so that the intersection creates a l chisel edge 3 where the surfaces 5A 7A intersect at an ¦ angle less thall 180. Likewise the intersection of surface SA with surface 4 defines cutting edge S while the intersection of surface 7A with surface 4 defines cutting edge 7. In tl-e arrangement shown in Figures 2 and 3 surfaces SA and 7A extend between surfaces 4 and 6 at an angle B for example 15 to 30~ as illustrated in Figures 4 and S to define the clearances behind the cutting edges S
and 7 defined by tlle intersection of surface SA 7A and lateral surfaces 6 and 4 respectively as shown.
In the prior art arrangement il1ustrat~d in Figure I
and 2 flank surfaces IOA and llA which may be planar 3s shown in Figure 2 are provided and flank edges IO and II are provlded by the intersectlon of surfaces IOA, llA bnd surfaces 6 and 4 respectively. Surfaces lOA and IIA may be located at an ang1e C wit~ respect to surfaces 6 and 4 to provide clearance bellind the flank tips IO and II as shown.
It is obvious that the extensions of cutting edges S
and 7 terminate at their intersection with flank edges IO
and Il to create points I3 and I4. In the case of a new drill tip or dril1 tip with no wear, the cutting action is performed by the cutting edges S and 7 and the diameter of the hole is determined hy tlle distance between points I3 and I4 where flank edges IO and II merely follow points I3 and 14. The cutting tip is of a hard material for example a conglomerate of smdll hard partic1es appropriately bonded together, for example, cemellted carbide which is cùrrently ; used.
Examining the fine structure at the points I3 and I4 it will be recognized t~lat the outermost hard particle at each is bonded to t~le body of the tip over less of its surface than are the next adjacent particles and that the proportion of the particle bonded to the body of the tip is a direct function of the solid angle bounded by surfaces 7A 6, IOA
and similarly by SA, 4, llA. For example, as shown in Figure 7 particle IS of which point I4 is one corner is bonded to the body by three (3) surfaces whereas particle I6 is bonded by four (4) surfaces. Obviously particle IS at point I4 5holI1d be more easily dislodged. -~ 1 324~1 3 ¦ The partic1es 15 and I6 can represent single hard ¦ partic1es or they can represent an aggregate of partic1es.
¦ During wear ùoth sing1e partic1es and aggregates of ¦ partic1es are dis10dged. Whether it is a single partic1e or ¦ the aggregate of partic1es that is dis10dged in a spec,ific ¦ event is dependent Dn a mu1ip1icity of conditions and events ¦ inc1uding constant fo~ces, impact forces, direction of ¦ forces, inhomogeneities in the material being cut, ¦ inhomogeneities in the cutting tip material, size and ¦ hardness of the cuttings from the workpiece relative to the ¦ size and hardIless of the hard particles and to the thickness ¦ and hardness of the borlding material in the cutting tip.
¦ Whatever the preciSe combination of wear mechanisms the ¦ resultant wear initiates at points I3 and 14 and growS.
¦ Ultimately, cutting edges S and 7 are blunted and flank ¦ edges I0 and lI become tapered so that the cutting tip ¦ becomes wedge shaped when seen in the elevation view. These ¦ changes cause an increased thrust required to penetrate the ¦ workpiece unti1 furtl,er use of the drill tip is no longer l practical.
In accordance with one feature of the present invention it has been unexpectedly found that the physical strength of the cu~ting edges S and 7 at their extremities iS a 1arger l than expected proportion of the total wear mechanism and ¦ that strengtIlening the extreme portions of cutting edges S
and 7 significantly increases the useful life o- the drill.
Other prior art configuration are also known as shown in Figures 6A and 6B. In Figure 6A the 'flank surfaces are l composed of two semicirclIldr surfaces 17 and I8 having a diameter D2 equal to the diameter of the hole to be drilled as the drill is rotated in direction F so the drill bit flank edge is congruent to the surface of revolution caused by drill rotation. Chamfered surfaces 19 and 20 are angularly disposed so that their trailing edges clear the surface of revolution. Figure 6B illustrates an arrangement where semicircular flank surfaces 21, 22 are provided with diameter D2 which is the diameter of the drill bit, so the total flank surface are congruent to the surface of revolution of the bit.
Referring now to Figure 1 which shows an assembly using a drill bit within the scope of the present invention shown in enlarged view in Figures 8A, 8B a principal feature of drill tips within the scope of the present invention as shown in Figure 8A, 8B is that the flank edges lOA and llA, shown in Figure 2, and surfaces 17, and 18 shown in Figure 6A and surfaces 21, 22 shown in Figure 6 are replaced by chamfer surfaces 43, 44.
In accordance with a principal feature of the present invention, the flank surfaces lOA, llA of the example in the prior art shown in Figure 3 are modified by chamfers 43 and 44 as shown to create new edges 46, 47 and new edges 52 and 53 and a new set of cutting points 57, 58, 59, and 60 as shown in the Figures where points corresponding to the points 59, 60 were not provided by the prior art. As shown in Figure 8A, the chamfered surfaces 43 and 44 respectively form an included angle I with the plane of their adjacent flank surface 62 or 61 of from 7.5 132~ol3 degrees to 70 degrees. Preferably, the angle I is 45 degrees.
~ S~
Similarly the ~n~ angles having apexes at 57, 58, 59, 60 are larger than those having apexes at 13 or 14 of the prior art example and are bonded to the body of the cutting tip over a larger proportion of their surface than are the corresponding extreme elements at points 13 and 14 in the cutting tip shown in Figures 2 and 3. It has been found that this change in geometry results in stronger physical structures at the locations of maximum wear due to chipping in a micro or micro form.
A further strengthening consequence of the invention derives from the changed angle of attack of cutting edges 63 and 64 as opposed to that of edges 5 and 7 of Figures 2 and 3.
Arrangements also within the scope of the present invention are also shown in Figures 9A-9B. In Figure 9A a tip is provided having a lateral surfaces 70, 71 with flank edges 72, 73 which have a diameter D3 corresponding to the diameter of the drill bit. Chamfers 74, 75 at angles F and G provide the advantages of the present invention by defining cutting points 76-81 similar to the cutting point illustrated in Figures 8A, 8B. The chamfered surfaces 74 and 75 respectively form an included angle F or G with the 25 plane of their adjacent flank surface 70 or 71 of from 7.5 degrees to 70 degrees. Preferably, each of the angles F
and G is 45 degrees.
l324nl3 Figure 9B illustrates another possible arrangement within the scope of the present invention where lateral edges 92, 93 are provided along with a semicircular flank edges 82, 83 having a diameter D4 equal to the drill bit diameter and where the edges are chamfered at 84, 85 in an arc pattern with the length of the chamfer less than the length of the whole flank edge to define points 86 91.
In general the chamfer surfaces within the scope of the present invention which define the cutting tip faces and points can be symmetrical relative to the center of rotation or they can be nonsymmetrical, they can be the full length of the flanks or they can extend only for a part of the lla .~
L~
. C ~r~yt~ of the flanks as shown or they can be tilted relative , to the axis of rotation of tlle drill to produce a triangular chamfer surface. The chamfers can be 'ncorporated in a design of the cutting tip wherein the flanks are disposed to provide clearance relative to the cylindrical surface of rotation of the drill or in tl,e design of cutting tip wherein tl,e f1anks coincide with the cylindrica1 surface of rotatio" of the drill or in t~le design of cutting tip wherein tl,e flanks are a combination of clearance and coincidence relative to the surface of rotation of the drill Drill bits incorporating features of devices within the scope of the present invention were tested in comparison with cutting tips of various prior art configurations but uniformly without tl,e chamfered leading edges of the flank surfaces provided by devices within the scope of the present invention as described hereinbefore. The dril1 bits incorporating cemented carbide tips having configurations within the scope of the present invention were compared with the dril1 bits manufactured by other manufacturers providing a somewhat similar tip configuration but in no case providing the additiona1 points as described hereinbefore.
From the testing it WdS conc1uded that as the angle is increased from 7,5D improvement is noted and that the depth of the chamfer can be between 1/5 and 3/4 of the de~th of the tip preferably about l/3.
Tests were cond,lcted with three materials, namely, pressure c~st concrete with crushed aggregate, concrete with gravel aggregate anll granite at various feed forces. It waS found that drill tips in accordance with the present invention provide superior results illustrated by superior rate of decrease in penetration rate over that of comparison drills and the rdte of wear was diminished with the result that the useful life of the drill was substantially improved, all as shown in Figure lO which is an illustration of comparison of the penetration rate of a drill point referenced to the tota1 depth of drilled holes. The superiority of devices within the scope of the present invention is clearly illustrated.
while all of the reasons for the superiority of drill bits within the scope of the present invention are not fully understood it is believed that dt least a portion of the improvement arises because the cutting forces are divided dmong several points ~hich because of the configuration are stronger dS previously described. Some improvement also arises because tl-e cutting edges are oriented to direct the cutting forces into the body of the tip rather than tdngentidlly to the arc of the cutting path as is the case with prior art tips. Furti~er, by redirecting the cutting forces the strength of the cutting edges are greatly enhanced. Some improvement may also be achieved because the overall lengths of the cutting edges are increased reducing the cutting force per unit length of cutting edge.
l It wil1 be understood tl~dt the foregoing are but a few examples o~ arrangements within the scope of the present invention and other drrangements also within the scope of the present iI~ventioll will occur to those skilled in of the art upon reading tI,is disclosule set forth hereinbefore.
Claims (10)
1. In a blade type cutting tip for a stone and masonry drill bit in which the cutting tip conventionally includes a chisel edge point defined by the intersection of first and second face surfaces symmetrically disposed on each side of a centerline of rotation of said tip and having two further points at the intersection of said face surfaces with respective ones of a pair of flank surfaces located respectively on opposite sides of said chisel edge point, said further points being located at the intersection of leading edges of said surfaces, the improvement comprising: a chamfer on said flank surfaces at the intersection thereof with the respective face surfaces to direct the wear away from said two further points at the intersection of said surfaces, said chamfer providing a first cutting point at the intersection of each said chamfer and each said face surface associated therewith and a second cutting point at the intersection of each said chamfer and flank surface associated therewith, said chamfers having a depth of between 1/5 and 3/4 of the depth of said tip.
2. The invention of Claim 1, wherein said chamfer defines a chamfered surface at an included angle of from 7.5 degrees to 70 degrees with the plane of the adjacent flank surface.
3. The invention of Claim 2, wherein said chamfered surface defines an included angle of 45 degrees with the plane of said flank surface.
4. The invention of Claim 1, wherein said chamfer comprises a surface extending only part of the length of said flank.
5. The invention of Claim 1, wherein said chamfer includes a triangular surface tilted relative to the axis of rotation of the drill bit.
6. The invention of Claim 1, wherein only one of said rotationally leading edges is chamfered.
7. The invention of Claim 1, wherein more than one of said rotationally leading edges is chamfered.
8. The invention of Claim 7, wherein said chamfers are unequal.
9. The invention of Claim 7, wherein said chamfers are equal.
10. The invention of Claim 1, wherein said depth of each of said chamfers is about 1/3 of the depth of said tip.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US012,428 | 1979-02-15 | ||
| US1242887A | 1987-02-09 | 1987-02-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1324013C true CA1324013C (en) | 1993-11-09 |
Family
ID=21754932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000557950A Expired - Fee Related CA1324013C (en) | 1987-02-09 | 1988-02-02 | Masonary drill tip with strong and chamfered cutting edges |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS63239007A (en) |
| CN (1) | CN1016949B (en) |
| BR (1) | BR8800464A (en) |
| CA (1) | CA1324013C (en) |
| CH (1) | CH674335A5 (en) |
| DE (1) | DE3803910A1 (en) |
| DK (1) | DK61888A (en) |
| FR (1) | FR2610553B1 (en) |
| IT (1) | IT1219838B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5918105A (en) * | 1994-12-12 | 1999-06-29 | Black & Decker Inc. | Cutting tools for drilling concrete, aggregate, masonry or the like materials |
| TW299385B (en) | 1994-12-12 | 1997-03-01 | Black & Decker Inc | Cutting tools for drilling concrete, aggregate, masonry or the like materials |
| DE19720589A1 (en) * | 1997-05-16 | 1998-11-19 | Hilti Ag | Drilling tool |
| GB0201197D0 (en) * | 2002-01-19 | 2002-03-06 | Armeg Ltd | Tile cutting attachment |
| JP6117659B2 (en) * | 2013-09-06 | 2017-04-19 | 本田技研工業株式会社 | Centrifugal pump |
| JP7380813B1 (en) * | 2022-11-29 | 2023-11-15 | 株式会社タンガロイ | drilling tool |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE698003C (en) * | 1938-06-29 | 1940-10-30 | Spiralbohrer Werkzeug Und Masc | Twist drill for tough materials |
| DE2807197A1 (en) * | 1978-02-20 | 1979-08-30 | Heller Verwaltungsges | DRILL HEAD OF A ROTARY IMPACT DRILL |
| DE8215364U1 (en) * | 1982-05-24 | 1982-10-14 | Weissenfeld, Günther, 5630 Remscheid | POINT DRILLING TOOL |
| DE3544433C2 (en) * | 1985-12-16 | 1995-12-14 | Hilti Ag | Rock drill |
-
1988
- 1988-02-02 CA CA000557950A patent/CA1324013C/en not_active Expired - Fee Related
- 1988-02-04 IT IT47603/88A patent/IT1219838B/en active
- 1988-02-05 BR BR8800464A patent/BR8800464A/en not_active IP Right Cessation
- 1988-02-08 DK DK061888A patent/DK61888A/en not_active Application Discontinuation
- 1988-02-08 FR FR8801440A patent/FR2610553B1/en not_active Expired - Fee Related
- 1988-02-08 CH CH434/88A patent/CH674335A5/de unknown
- 1988-02-09 DE DE3803910A patent/DE3803910A1/en not_active Ceased
- 1988-02-09 CN CN88101340.4A patent/CN1016949B/en not_active Expired
- 1988-02-09 JP JP63028610A patent/JPS63239007A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN1016949B (en) | 1992-06-10 |
| IT8847603A0 (en) | 1988-02-04 |
| FR2610553B1 (en) | 1993-05-07 |
| DK61888A (en) | 1988-08-10 |
| BR8800464A (en) | 1988-09-20 |
| DK61888D0 (en) | 1988-02-08 |
| JPS63239007A (en) | 1988-10-05 |
| CH674335A5 (en) | 1990-05-31 |
| DE3803910A1 (en) | 1988-08-18 |
| IT1219838B (en) | 1990-05-24 |
| FR2610553A1 (en) | 1988-08-12 |
| CN1032131A (en) | 1989-04-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |