CA1207566A - Drill and indexable carbide insert therefor - Google Patents
Drill and indexable carbide insert thereforInfo
- Publication number
- CA1207566A CA1207566A CA000431130A CA431130A CA1207566A CA 1207566 A CA1207566 A CA 1207566A CA 000431130 A CA000431130 A CA 000431130A CA 431130 A CA431130 A CA 431130A CA 1207566 A CA1207566 A CA 1207566A
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- insert
- cutting
- cutting edge
- drill
- face
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Abstract
TITLE OF THE INVENTION
A DRILL AND INDEXABLE CARBIDE INSERT THEREFOR
ABSTRACT OF THE DISCLOSURE
Disclosed is a drill with a shank having a central axis of rotation and only one insert on one end of the shank. The insert has two cutting edges. The first cutting edge has a negative radial rake and the second cutting edge has negative axial and positive radial rake surface. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis. Also disclosed is a cutting insert of hard wear resistant material. The insert has top and bottom faces and a peripheral wall joining the top and bottom faces.
The insert body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face. There are first cut-ting edges formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall. One end of each of the first cutting edges termi-nates in a juncture with a second cutting edge that extends from the cutting face toward the seating face.
The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis.
A DRILL AND INDEXABLE CARBIDE INSERT THEREFOR
ABSTRACT OF THE DISCLOSURE
Disclosed is a drill with a shank having a central axis of rotation and only one insert on one end of the shank. The insert has two cutting edges. The first cutting edge has a negative radial rake and the second cutting edge has negative axial and positive radial rake surface. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis. Also disclosed is a cutting insert of hard wear resistant material. The insert has top and bottom faces and a peripheral wall joining the top and bottom faces.
The insert body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face. There are first cut-ting edges formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall. One end of each of the first cutting edges termi-nates in a juncture with a second cutting edge that extends from the cutting face toward the seating face.
The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis.
Description
~7566 BACKGROUND OF THE INVENTION
.
This invention relates to the field of metalcutting tools and, more specifically, it relates to those metal-cutting tools known as drills.
The prior art method of drilling holes has been by the use of twist drills, twist drills with brazed carbide tips or drills having indexable carbide inserts.
The use of drills having indexable carbide inserts is often preferred because of their consistent quality and overall cost effectiveness.
Notwithstanding the economical advantages of drills having indexable carbide inserts, twist drills are still used for holes under about one- half inch in diameter.
The principal reason for still using the small twist drills is that it has generally been thought to be impractical to manufacture a small drill having index-able carbide inserts.
It woul~ be desirable to have a small drill that uses indexable carbide inserts because such a tool can drill a~ higher speeds, for longer periods of time and for less cost than twist drills.
However, the obstacles to manufacturing a small drill having indexable carbide inserts are twofold.
Since such drills have a minimum of two inserts, the inserts would have to be made very small so as to both fit on the drill shank. These inserts would be costly to make as well as difficult to handle. The first obstacle then is that a drill employing small indexable
.
This invention relates to the field of metalcutting tools and, more specifically, it relates to those metal-cutting tools known as drills.
The prior art method of drilling holes has been by the use of twist drills, twist drills with brazed carbide tips or drills having indexable carbide inserts.
The use of drills having indexable carbide inserts is often preferred because of their consistent quality and overall cost effectiveness.
Notwithstanding the economical advantages of drills having indexable carbide inserts, twist drills are still used for holes under about one- half inch in diameter.
The principal reason for still using the small twist drills is that it has generally been thought to be impractical to manufacture a small drill having index-able carbide inserts.
It woul~ be desirable to have a small drill that uses indexable carbide inserts because such a tool can drill a~ higher speeds, for longer periods of time and for less cost than twist drills.
However, the obstacles to manufacturing a small drill having indexable carbide inserts are twofold.
Since such drills have a minimum of two inserts, the inserts would have to be made very small so as to both fit on the drill shank. These inserts would be costly to make as well as difficult to handle. The first obstacle then is that a drill employing small indexable
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1~7566 indexable carbide inserts simply would not be economical to manufacture. The second obstacle is that the shank would become too weak to withstand ~he anticipated cut-ting loads if two inserts were placed on the same end of the shank.
Applicant, however, has solved the problems of the prior art by utilizing a single indexable carbide insert that acts as if it were two inserts. So far as appli-cant is aware, this is the first use of a single index-able insert on a drill.
A single carbide tip has been used in a ball end mill as shown in United States Patent No. 4,132,493.
It is thus an object of this invention to manufac-ture a drill that uses indexable carbide inserts and that can drill holes under about one-half inch in diameter.
It is another object of this invention to econo~
cally manufacture a drill that uses indexable carbide inserts and that can drill holes under about one-half inch in diameter.
It is a still further object of this invention to manufacture a small drill that uses indexable carbide inserts and that can effectively replace twist drills.
BRIEF SUMMARY OF I'HE INVENTION
.
According to the invention, there is disclose~ a drill with a shank having a central axis of rotation.
There is only one inser~ on one end of the shank. The insert has two cutting edges. The first cutting edge ~'7~6G
has a negative radial rake sur~ace and the second cut-ting edge has negative axial and positive radial rake surfaces. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis.
In another embodiment of the invention, there may be more than one insert on the end of the shank.
The central axis of rotation passes through the axial rake face of the second cutting edge. The first cutting edge may have zero axial rake or positive axial rake.
Preferably, the insert is indexable.
In a preferred embodiment, the first cutting edge is substantially perpendicular to the central axis of rotation so that a hole with a substantially flat bottom is formed.
Preferably, the insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of the diamond is between 75 degrees and 85 degrees. It is also preferable for the insert to be in the shape of a square when viewed in plan.
The shank has a reduced diameter portion. The insert is held to the shank by fastening means passing through a perforation in the insert and terminating in a recess in the shank.
The second cutting edge axial rake face preferably extends outwardly with respect to the insert so as to break out of the insert.
1;Z(~7S!6~
In another embodiment, the insert ha.s at least one other cutting edge having negative axial and positive radial rake surfaces. This at least one other cutting edge cooperates with the first and second cutting edges to form a radiused hole when rotated about the central axis.
In a further embodiment, the second cutting edge may be concave.
According to the invention, there is a drill dis-closed with a shank having a central axis of rotation.Only one cutting insert is disposed on the end of the shank and the insert has first and second cutting edges and a clearance face. The first cutting edge extends inwardly and parallel to a plane containing the axis of rotation. The second cutting edge extends inwardly from the first cutting edge and when viewed from the end forms an included angle of greater than 90 degrees therewith. The first and second cutting edges are oriented along the forward portion in the rotational sense of the clearance face. The clearance face inter-sects the plane without intersecting the axis of rota-tion. The first and second cutting edges cooperate so as to rotatably cut a hole.
In another embodiment of the drill, there is at least one cutting insert disposed on the end of the shank.
The second cutting edge has a rake face and prefer-ably the axis of rotation passes through the rake face.
lZ~S~i6 The first cutting edge has a negative radial rake surface and the second cutting edge has negative a~ial and positive radial rake surfaces. The first cutting edge may have zero axial rake or positive axial rake.
The insert is most preferably indexable.
Preferably, the first cutting edge is substantially perpendicular to the axis of rotation so that a hole with a substantially flat bottom is formed.
The insert may be in the shape of a diamond when viewed in plan with the smaller of the included angles of the diamond being between 75 degrees and 85 degrees.
Alternatively, the insert may be in the shape of a square when viewed in plan.
The shank has a reduced diameter portion and the insert is disposed on the end of the reduced diameter portion of the shank. The insert is held to the shank by fastening means passing through a perforation in the insert and terminating in a recess in the shank. The drill may also have means for supplying coolant which are internal to the shank and exit the shank at the end of the reduced diameter portion.
The second cutting edge may comprise a plurality o~
cutting segments. The orientation of each of the seg-ments differs in orientation from the previous cutting segment so that when viewed from the end the included angle between the first of said segments and the first cutting edge and the included angle between each ~ZC~75~;
subse~uent cutting segment and the previous cutting seg-ment is greater than 90 degrees.
In another embodiment, the second cutting edge is substantially concave. l'he concave cutting edge and its axial rake face form a groove which narrows in depth and width away fro~ the concave cutting edge.
According to the invention, disclosed i9 a cutting insert of hard wear resistant material. The insert has top and bottom faces and a peripheral wall joining the top and bottom faces. The insert body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face.
There are first cutting edges formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall. One end of each of the first cutting edges terminates in a juncture with a second cutting edge that extends from said cutting face toward said seating face. The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis.
Each of the second cutting edges has a rake face which extends upwardly awây from the seating face so that it breaks out through the cutting face.
Preferably, the insert is indexable.
Preferably, the insert is in the shape of a diamond when viewed in plan and the smaller of the included angles o~ the diamond is between 75 degrees and ~5 756~i degrees. Preferably, also, the insert is in the shape of a square when viewed in plan.
In other embodiments, each of the second cutting edges joins with at least one other cutting edge that extends toward the seating face. Alternatively, each of the second cutting edges is concave away from the seating face.
According to the invention, disclosed is a hard wear resistant cutting insert. The insert has a top and bottom parallel to the top joined by four lateral faces.
At least one of the lateral faces is a clearance face.
The clearance face has a first cutting edge which is formed by the intersection of the top and the clearance face. The clearance face also has a second cutting edge intersecting the first cutting edge at an included angle of greater than 90 degrees when viewed perpendicularly to the clearance face. The second cutting edge is formed by the intersection of a rake face of the second cutting edge and the clearance face. The rake face is defined by a plane which intersects the clearance face, one of said lateral faces and the top. This plane is not perpendicular to either of the clearance face, lateral face or top so that a flat is formed extending away from the second cutting edge~
Preferably, the insert is indexable.
In a further embodiment, the insert is preferably in the shape of a diamond when viewed in plan with the smaller of the included angles of the diamond being lZ~7S~i between 75 degrees and 85 degrees. In another embodi-ment, the insert is in the shape of a s~uare when viewed in plan.
The second cutting edge may comprise a plurality of cutting segments The orientation of each of the seg-ments differs in orientation from the previous cutting segment so that when viewed perpendicularly to the clear-ance face the included angle between the first of the segments and the first cutting edge and the included angle between each subsequent cutting segment and the previous cutting segment is greater than 90 degrees.
Each of the segments has a rake face which differs in orientation, corresponding to the differences in orientation of each of the segments. Each of the rake faces intersects the rake faces on either side thereof.
The lines of intersection formed by the rake faces all converge to a point away from the segments.
In another embodiment, the second cutting edge has a concave portion and a corresponding concave axial rake face. The concave portion and axial rake face form a groove which narrows in depth and width away from the concave cutting portion.
BRIEF DESCRIPTION OE THE DRAWINGS
The exact nature of the present invention will become more clearly apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:
1~i7S~6 Figure 1 is a side view of the drill according to the present invention Figure 2 is an end view of the drill in Fi~ure 1.
Figure 3 is a schematic illustration of a hole made by a drill according to the invention.
Figure 4 is an enlarged view of Figure 2.
Figure 5 is a side view of another embodiment of the drill according to the invention.
Figure 6 is a perspective view of an insert accord-ing to the invention.
Figure 7 is a plan view of the insert of Figure 6.
Figure 8 is a view of Figure 7 in the direction shown by arrow VIII.
Figure 9 is a perspective view of another insert according to the invention.
Figure 10 is a plan view of the insert of Flgure 9.
Figure 11 is a view of Figure 10 in the direction of arrow XI.
Figure 12 i6 a perspective view of another insert according to the invention.
Figure 13 is a plan view of the insert of Figure 12.
Figure 14 is a view of Figure 13 in the direction of arrow XIV.
Figure 15 is a perspective view of another insert according to the invention.
Figure 16 is a plan view of the insert of Figure 15.
lZiO 7S66 Figure 17 is a view of the insert of Figure 16 in the direction of arrow XVII.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings somewhat more in detail, according to the invention there is disclosed a drill 2 as shown in Figures 1 and 2. The drill has a shank 4 having a central axis of rotation 6. The direction of rotation is shown by arrow 7. There is only one insert 8 on one end 10 of the shank. The insert has two cutting edges 12 and 14. The first cutting edge 12 has a nega-tive radial rake surface and the second cutting edge 14 has negative axial and positive radial rake surfaces.
The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis.
The operation of the drill according to the inven-tion can best be understood by referring to Figure 3.
Figure 3 schematically illustrates a hole 16 being drilled hy the drill according to the invention. The first cutting edge removes the outer portion 18 of the hole while the second cutting edge removes the inner portion 20 of the hole. The second cutting edge must be located slightly away from the axis of rotation so that there is never a point of zero velocity on the second cutting edge. Since the second cutting edge is slightly removed from the axis of rotation, a small nib 22 is left after each rotation of the drill. However, in the prac-tical application of the drill, this nib would frequently 12~7566 break off during the drilling operation so as not to be evident in the finished hole.
According to the invention, there is disclosed another embodiment of the drill. There is a shank 4 haviny a central axis of rotation 6. ~here is at least one insert ~ on one end 10 of the shank. For larger holes, the use of two or more inserts may be preferable.
The insert has two cutting edges 12 and 14~ The first cutting edge 12 has a negative radial rake surface and the second cutting edge 14 has negative axial and posi-tive radial rake surfaces. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis.
This invention has been found to be most useful for drilling holes less than one inch in diameter and especially useful for drilling holes less than one-half inch in diameter. It is contemplated within the scope of this invention that this drill may also be used for holes larger than one inch in diameter.
Preferably, the central axis of rotation 6 passes through the axial rake face 24 of the second cutting edge 14.
It is preferred that the first cutting edge has 2ero axial rake or positive axial rake.
Most preferably, the insert is indexable.
In a preferred embodimentl and as best shown in Figure 1, the first cutting edge 12 is substantially perpendicular to the central axis of rotation 6 so that a :12~756~
hole with a substantially flat bottom is formed. It had previously been thought to be impossible to drill a flat bottom hole. However, according to the invention, a flat bottom hole is easily drilled.
~ eferring now to Figure 7, the insert is preferably in the shape of a diamond when viewed in plan and the smaller of the included angles at 26 of the diamond is between 7~ degrees and 85 degrees. Normally, there will be two cutting positions on the insert at 28 and 30.
Referring now to Figures 5 and 10, there is another embodiment of the drill 2 wherein the insert ~ is in the shape of a square when viewed in plan. The advantage of using a square insert is that four cutting positions 34, 36, 38 and 40 are now possible.
It should be noted that a flat bottom hole is no longer possible when a square insert is used. The reason is that a clearance angle is needed on the outside of the insert so that the side of the insert does not rub against the wall of the hole. To obtain this clearance angle, the insert must be tilted slightly, with the result that the first cutting edge would no longer be perpendicular to the axis of rotation.
Referring back to Fiyures 1 and 2, the shank prefer-ably has a reduced diameter portion 42. The insert is disposed on the end 10 of the reduced diameter portion of the shank.
The insert is held to the shank by fastening means 44 passing through a perforation 46 in the insert. The '7S~6 fastening means terminates in a recess 94 in the shank.
The fastening means may be any of those well known in the prior art.
As can he seen most clearly in Figures 6 through 8, the second cutting edge axial rake face 24 extends out-wardly with respect to the insert so as to break out of said insert at 48.
In another embodiment of the drill, as can be seen in Figures 12 through 14, the insert 8 has at least one other cutting edge 50. This cutting edge has negative axial and positive radial rake surfaces. The at least one other cutting edge cooperates with the first and second cutting edges to form a radiused hole when rotated about the central axis.
Referring now to Figures 15 ~hrough 17, there is a further embodiment of the drill wherein the second cut-ting edge 14 is concave 52.
According to the invention, disclosed is a drill as can be seen in Figures 1 and 2, but can be best seen in Figure 4. The drill has a shank 4 and the shank has a central axis of rotation 6. The direction of rotation is shown by arro~ 7. There is only one cutting insert 8 disposed on the end 10 of the shank. As shown in Figure 4, the insert has first and second cutting edges 12 and 14, respectively, and clearance face 54. The first cut-ting edge 12 extends inwardly and parallel to a plane 56 containing the axis of rotation. The plane rotation.
The plane 56 is positioned so as to be perpendicular to lZ~ S66 the plane of the paper. The second cutting edge 14 extends inwardly from the first cutting edge and when viewed from the end forms an included angle 58 of greater than 90 degrees therewith. The first and second cutting edges are oriented along the forward portion 60 in the rotational sense of the clearance face 54. The clearance face intersects the plane 56 without intersecting the axis of rotation. The intersection of the clearance face and the plane is along a line that would be drawn from 62 to 64. The first and second cutting edges cooperate so as to rotatably cut a hole.
The operation of the drill according to the inven-tion is schematically illustrated in ~igure 3. Hole 16 is being drilled with outer portion 18 of the hole being removed by the first cutting edge and the inner portion 20 of the hole being removed by the first cutting edge.
In order for the objects of the invention to be achieved, the second cutting edge is located slightly off center so as to avoid any point of zero velocity. Because the second cutting edge is located sllghtly off center, ~ou get nib 22, which is broken off periodically during the operation of the drill.
According to the invention, there is disclosed a drill 2 as can also be seen in Figures 1 and 2. There is a shank 4 having a cental axis of rotation 6. There is at least one cutting insert 8 disposed on the end 10 of the shank. For larger holes, it may be preferable to have two or more inserts located on the end of the shank.
lZ~375~
For larger holes, it may be preferable to have two or more inserts located on the end of the shank. Referring now to Figure 4, the insert has first and second cutting edges 12 and 14, respectively, and a clearance face 54.
The first cutting edge 12 extends inwardly and para:Llel to a plane 56 containing the axis of rotation. This plane 56 is perpendicular to the plane of the paper. The second cutting edge 14 extends inwardly from the first cutting edge and when viewed from the end forms an included angle 58 of greater than 90 degrees therewith.
The first and second cutting edges are oriented along the forward portion 60 in the rotational sense of the clear-ance face 54. The clearance face intersects the plane 56 without intersecting the axis of rotation. The first and second cutting edges cooperate so as to rotatably cut a hole.
The preferred use of this invention is for holes less than about one inch in diameter, in which case one insert would preferably be used. However, drilled holes greater than about one inch in diameter are also contem-plated within the scope of the invention~ In this latter case, it may be found to be preferable to use two or more inserts.
The second cutting edge has a rake face 24 and, preferably, the axis of rotation 6 passes through the rake face.
Preferably, the first cutting edge has a negative radial rake surface and the second cutting edge has i2~7Sf~6 negative axial and positive radial rake surfaces. The first cutting edge also has a zero axial rake or positive axial rake. Preferably, the insert is indexable.
In a preferred embodiment, the first cutting edge 12 is substantially perpendicular to the axis of rotation 6 so that a hole with a substantially flat bottom is formed. In the prior art, it was thought to be impossi-ble to get a flat bottom hole; however, such a hole is found to be achievable according to the invention.
As can be seen in Figures 1 and 7, the insert 8 is in the shape of a diamond when viewed in plan and the smaller of the included angles at 26 of the diamond is between 75 degrees and 85 degrees. Normally, with such an insert shape, there would be two cutting positions located at 28 and 30.
In another embodiment, as shown in Figures 5 an 10, the insert 8 is in the shape of a square when viewed in plan. With this type of insert, it is possible to have four cutting positions with each cutting position located at the corners 34, 36, 38 and 40 of the square. Because of the clearance angles required on the outside of the insert, the insert must be tilted slightly. Accordingly, a flat bottom hole is no longer possible with a s~uare insert.
The shank has a reduced diameter portion 42. The insert is disposed on the end 10 of the reduced diameter portion of the shank.
75~6 The insert is held to the shank by fastening means 44 passing through a perforation 46 in the insert. The fastening means terminates in a recess 94 in the shank.
The drill preferably comprises means 66 for supply-ing coolant. The coolant means are internal to the shank and exit the shank at the end 10 of the reduced diameter portion.
In another embodiment, as shown in Figures 12 through 14, the second cutting edge is comprised of a plurality of cutting segments. As shown in the figures, there is one additional segment 50, but it is contem-plated within t~e scope of the invention that there may be several such segments. The orientation of each of the segments differs in orientation rom the previous cutting segment so that when viewed from the end the included angle 58 between the first of the segments and the first cutting edge and the included angle 68 hetween each sub~
sequent cutting segment and the previous cutting segment is greater than 90 degrees.
A further embodiment is now shown in ~igures 15 through 17. In this embodiment of the drill, the second cutting edge 14 is substantially concave as shown by 52.
The concave cutting edge 52 and its axial rake face 70 form a groove which narrows in depth 72 and width 74 away from the concave cutting edge 52.
According to the invention, there is a cutting insert disclosed as shown in Figures 6 through 8. The insert is comprised of a body of hard wear resistant :1~07566 material having top 76 and bottom 78 faces and a peri-pheral wall 80 joining the top and bottom faces. The hard wear resistant material is preferably cemented carbide. The body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face. First cutting edges 12 are formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall.
One end of each of the first cutting edges terminates in a jt~ncture 82 with a second cutting edge 14 that extends from the cutting face toward the seating face. The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis.
Each of the second cutting edges has a rake face 24 which extends upwardly away from the bottom face so that it breaks out through the cutting face at 48.
It is preferable that the insert is indexable.
Preferably, the insert is in the shape of a diamond when viewed in plan and the smaller of the included 20 angles at 26 of the diamond is between 75 degrees and 85 degrees. As shown in the figures, there would normally be two cutting positions located at 28 and 30.
Referring now to Figures 9 through ll, the insert may be in the shape of a square when viewed in plan.
When the insert has a square shape, there would normally be four cutting pGsitions located at each corner of the square.
~2a~ i6 In another embodiment of the insert, as shown in Figures 12 through 14, each of the second cutting edges 14 joins with at least one other cutting edge 50 that extends toward the seating face.
In a further embodiment, as shown in Figures 15 through 17, each of the second cutting edges 1~ of the insert is concave away from the seating face.
According to the invention, there is disclosed a hard wear resistant cutting insert. The hard wear resistant material is preferably cemented carbide. As best seen in Figures 6 through 8, there is a top 76 and a bottom 78 parallel to the top joined by four lateral faces 80. At least one of the lateral faces is a clear-ance face 54. The clearance face has a first cutting edge 12 which is formed by the intersection of the top 76 and the clearance face 54. There is a second cutting edge 14 intersecting at 82 the first cutting edge at an included angle 58 of greater than 90 degrees when viewed perpendicularly to the clearance face. The second cut-ting edge is formed by the intersection of a rake face 24of the second cutting edge and the clearance face. The rake face is defined by a plane which intersects the clearance face at 14, one of the lateral faces at 84 and the top at 86. This plane is not perpendicular to either of the clearance face, the one of the lateral faces or the top so that a flat is formed extending away from the second cutting edge.
Most preferably, the insert is indexable.
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lZ~3'7566 Preferably~ the insert is in the shape of a diamond when viewed in plan and the smaller of the included angles at 26 of the diamond is between 75 degrees and 85 degrees. With a diamond shape, there would normally be two cutting positions.
Preferably, also, the insert is in the shape of a square when viewed in plan, and there would normally be four cutting positions.
In another embodiment of the insert, as shown in Figures 12 through 14, the second cutting edge comprises a plurality of cu~ting segments. The orientation of each of the segments differs in orientation from the previous cutting segment so that, when viewed perpendicular to the clearance face 54, the included angle 58 between the first 14 face segments and the first cutting edge 12 and the included angle 6g between each subsequent cutting segment 50 and the previous cutting segment is greater than 90 degrees. Each of the segments has a rake face 88 and 90 which differs in orientation corresponding to the differing in orientation of each of the segments 14 and 50, respectively. Each of the rake faces intersects the rake faces on either side thereof. As shown in the figures, rake faces 88 and 90 would intersect at 92. The lines of intersection formed by the rake faces all con-verge to a point 48 away from the segments.
In a further embodiment of the insert, as shown in Figures 15 through 17, the second cutting edge 14 has a concave portion 52 and a corresponding concave axial rake 12~5~;
face 70. The concave portion and the axial rake face form a groove which narrows in depth 72 and width 74 away from the cutting force.
Modifications may be made within the scope of the appended claims.
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1~7566 indexable carbide inserts simply would not be economical to manufacture. The second obstacle is that the shank would become too weak to withstand ~he anticipated cut-ting loads if two inserts were placed on the same end of the shank.
Applicant, however, has solved the problems of the prior art by utilizing a single indexable carbide insert that acts as if it were two inserts. So far as appli-cant is aware, this is the first use of a single index-able insert on a drill.
A single carbide tip has been used in a ball end mill as shown in United States Patent No. 4,132,493.
It is thus an object of this invention to manufac-ture a drill that uses indexable carbide inserts and that can drill holes under about one-half inch in diameter.
It is another object of this invention to econo~
cally manufacture a drill that uses indexable carbide inserts and that can drill holes under about one-half inch in diameter.
It is a still further object of this invention to manufacture a small drill that uses indexable carbide inserts and that can effectively replace twist drills.
BRIEF SUMMARY OF I'HE INVENTION
.
According to the invention, there is disclose~ a drill with a shank having a central axis of rotation.
There is only one inser~ on one end of the shank. The insert has two cutting edges. The first cutting edge ~'7~6G
has a negative radial rake sur~ace and the second cut-ting edge has negative axial and positive radial rake surfaces. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis.
In another embodiment of the invention, there may be more than one insert on the end of the shank.
The central axis of rotation passes through the axial rake face of the second cutting edge. The first cutting edge may have zero axial rake or positive axial rake.
Preferably, the insert is indexable.
In a preferred embodiment, the first cutting edge is substantially perpendicular to the central axis of rotation so that a hole with a substantially flat bottom is formed.
Preferably, the insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of the diamond is between 75 degrees and 85 degrees. It is also preferable for the insert to be in the shape of a square when viewed in plan.
The shank has a reduced diameter portion. The insert is held to the shank by fastening means passing through a perforation in the insert and terminating in a recess in the shank.
The second cutting edge axial rake face preferably extends outwardly with respect to the insert so as to break out of the insert.
1;Z(~7S!6~
In another embodiment, the insert ha.s at least one other cutting edge having negative axial and positive radial rake surfaces. This at least one other cutting edge cooperates with the first and second cutting edges to form a radiused hole when rotated about the central axis.
In a further embodiment, the second cutting edge may be concave.
According to the invention, there is a drill dis-closed with a shank having a central axis of rotation.Only one cutting insert is disposed on the end of the shank and the insert has first and second cutting edges and a clearance face. The first cutting edge extends inwardly and parallel to a plane containing the axis of rotation. The second cutting edge extends inwardly from the first cutting edge and when viewed from the end forms an included angle of greater than 90 degrees therewith. The first and second cutting edges are oriented along the forward portion in the rotational sense of the clearance face. The clearance face inter-sects the plane without intersecting the axis of rota-tion. The first and second cutting edges cooperate so as to rotatably cut a hole.
In another embodiment of the drill, there is at least one cutting insert disposed on the end of the shank.
The second cutting edge has a rake face and prefer-ably the axis of rotation passes through the rake face.
lZ~S~i6 The first cutting edge has a negative radial rake surface and the second cutting edge has negative a~ial and positive radial rake surfaces. The first cutting edge may have zero axial rake or positive axial rake.
The insert is most preferably indexable.
Preferably, the first cutting edge is substantially perpendicular to the axis of rotation so that a hole with a substantially flat bottom is formed.
The insert may be in the shape of a diamond when viewed in plan with the smaller of the included angles of the diamond being between 75 degrees and 85 degrees.
Alternatively, the insert may be in the shape of a square when viewed in plan.
The shank has a reduced diameter portion and the insert is disposed on the end of the reduced diameter portion of the shank. The insert is held to the shank by fastening means passing through a perforation in the insert and terminating in a recess in the shank. The drill may also have means for supplying coolant which are internal to the shank and exit the shank at the end of the reduced diameter portion.
The second cutting edge may comprise a plurality o~
cutting segments. The orientation of each of the seg-ments differs in orientation from the previous cutting segment so that when viewed from the end the included angle between the first of said segments and the first cutting edge and the included angle between each ~ZC~75~;
subse~uent cutting segment and the previous cutting seg-ment is greater than 90 degrees.
In another embodiment, the second cutting edge is substantially concave. l'he concave cutting edge and its axial rake face form a groove which narrows in depth and width away fro~ the concave cutting edge.
According to the invention, disclosed i9 a cutting insert of hard wear resistant material. The insert has top and bottom faces and a peripheral wall joining the top and bottom faces. The insert body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face.
There are first cutting edges formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall. One end of each of the first cutting edges terminates in a juncture with a second cutting edge that extends from said cutting face toward said seating face. The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis.
Each of the second cutting edges has a rake face which extends upwardly awây from the seating face so that it breaks out through the cutting face.
Preferably, the insert is indexable.
Preferably, the insert is in the shape of a diamond when viewed in plan and the smaller of the included angles o~ the diamond is between 75 degrees and ~5 756~i degrees. Preferably, also, the insert is in the shape of a square when viewed in plan.
In other embodiments, each of the second cutting edges joins with at least one other cutting edge that extends toward the seating face. Alternatively, each of the second cutting edges is concave away from the seating face.
According to the invention, disclosed is a hard wear resistant cutting insert. The insert has a top and bottom parallel to the top joined by four lateral faces.
At least one of the lateral faces is a clearance face.
The clearance face has a first cutting edge which is formed by the intersection of the top and the clearance face. The clearance face also has a second cutting edge intersecting the first cutting edge at an included angle of greater than 90 degrees when viewed perpendicularly to the clearance face. The second cutting edge is formed by the intersection of a rake face of the second cutting edge and the clearance face. The rake face is defined by a plane which intersects the clearance face, one of said lateral faces and the top. This plane is not perpendicular to either of the clearance face, lateral face or top so that a flat is formed extending away from the second cutting edge~
Preferably, the insert is indexable.
In a further embodiment, the insert is preferably in the shape of a diamond when viewed in plan with the smaller of the included angles of the diamond being lZ~7S~i between 75 degrees and 85 degrees. In another embodi-ment, the insert is in the shape of a s~uare when viewed in plan.
The second cutting edge may comprise a plurality of cutting segments The orientation of each of the seg-ments differs in orientation from the previous cutting segment so that when viewed perpendicularly to the clear-ance face the included angle between the first of the segments and the first cutting edge and the included angle between each subsequent cutting segment and the previous cutting segment is greater than 90 degrees.
Each of the segments has a rake face which differs in orientation, corresponding to the differences in orientation of each of the segments. Each of the rake faces intersects the rake faces on either side thereof.
The lines of intersection formed by the rake faces all converge to a point away from the segments.
In another embodiment, the second cutting edge has a concave portion and a corresponding concave axial rake face. The concave portion and axial rake face form a groove which narrows in depth and width away from the concave cutting portion.
BRIEF DESCRIPTION OE THE DRAWINGS
The exact nature of the present invention will become more clearly apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:
1~i7S~6 Figure 1 is a side view of the drill according to the present invention Figure 2 is an end view of the drill in Fi~ure 1.
Figure 3 is a schematic illustration of a hole made by a drill according to the invention.
Figure 4 is an enlarged view of Figure 2.
Figure 5 is a side view of another embodiment of the drill according to the invention.
Figure 6 is a perspective view of an insert accord-ing to the invention.
Figure 7 is a plan view of the insert of Figure 6.
Figure 8 is a view of Figure 7 in the direction shown by arrow VIII.
Figure 9 is a perspective view of another insert according to the invention.
Figure 10 is a plan view of the insert of Flgure 9.
Figure 11 is a view of Figure 10 in the direction of arrow XI.
Figure 12 i6 a perspective view of another insert according to the invention.
Figure 13 is a plan view of the insert of Figure 12.
Figure 14 is a view of Figure 13 in the direction of arrow XIV.
Figure 15 is a perspective view of another insert according to the invention.
Figure 16 is a plan view of the insert of Figure 15.
lZiO 7S66 Figure 17 is a view of the insert of Figure 16 in the direction of arrow XVII.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings somewhat more in detail, according to the invention there is disclosed a drill 2 as shown in Figures 1 and 2. The drill has a shank 4 having a central axis of rotation 6. The direction of rotation is shown by arrow 7. There is only one insert 8 on one end 10 of the shank. The insert has two cutting edges 12 and 14. The first cutting edge 12 has a nega-tive radial rake surface and the second cutting edge 14 has negative axial and positive radial rake surfaces.
The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis.
The operation of the drill according to the inven-tion can best be understood by referring to Figure 3.
Figure 3 schematically illustrates a hole 16 being drilled hy the drill according to the invention. The first cutting edge removes the outer portion 18 of the hole while the second cutting edge removes the inner portion 20 of the hole. The second cutting edge must be located slightly away from the axis of rotation so that there is never a point of zero velocity on the second cutting edge. Since the second cutting edge is slightly removed from the axis of rotation, a small nib 22 is left after each rotation of the drill. However, in the prac-tical application of the drill, this nib would frequently 12~7566 break off during the drilling operation so as not to be evident in the finished hole.
According to the invention, there is disclosed another embodiment of the drill. There is a shank 4 haviny a central axis of rotation 6. ~here is at least one insert ~ on one end 10 of the shank. For larger holes, the use of two or more inserts may be preferable.
The insert has two cutting edges 12 and 14~ The first cutting edge 12 has a negative radial rake surface and the second cutting edge 14 has negative axial and posi-tive radial rake surfaces. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis.
This invention has been found to be most useful for drilling holes less than one inch in diameter and especially useful for drilling holes less than one-half inch in diameter. It is contemplated within the scope of this invention that this drill may also be used for holes larger than one inch in diameter.
Preferably, the central axis of rotation 6 passes through the axial rake face 24 of the second cutting edge 14.
It is preferred that the first cutting edge has 2ero axial rake or positive axial rake.
Most preferably, the insert is indexable.
In a preferred embodimentl and as best shown in Figure 1, the first cutting edge 12 is substantially perpendicular to the central axis of rotation 6 so that a :12~756~
hole with a substantially flat bottom is formed. It had previously been thought to be impossible to drill a flat bottom hole. However, according to the invention, a flat bottom hole is easily drilled.
~ eferring now to Figure 7, the insert is preferably in the shape of a diamond when viewed in plan and the smaller of the included angles at 26 of the diamond is between 7~ degrees and 85 degrees. Normally, there will be two cutting positions on the insert at 28 and 30.
Referring now to Figures 5 and 10, there is another embodiment of the drill 2 wherein the insert ~ is in the shape of a square when viewed in plan. The advantage of using a square insert is that four cutting positions 34, 36, 38 and 40 are now possible.
It should be noted that a flat bottom hole is no longer possible when a square insert is used. The reason is that a clearance angle is needed on the outside of the insert so that the side of the insert does not rub against the wall of the hole. To obtain this clearance angle, the insert must be tilted slightly, with the result that the first cutting edge would no longer be perpendicular to the axis of rotation.
Referring back to Fiyures 1 and 2, the shank prefer-ably has a reduced diameter portion 42. The insert is disposed on the end 10 of the reduced diameter portion of the shank.
The insert is held to the shank by fastening means 44 passing through a perforation 46 in the insert. The '7S~6 fastening means terminates in a recess 94 in the shank.
The fastening means may be any of those well known in the prior art.
As can he seen most clearly in Figures 6 through 8, the second cutting edge axial rake face 24 extends out-wardly with respect to the insert so as to break out of said insert at 48.
In another embodiment of the drill, as can be seen in Figures 12 through 14, the insert 8 has at least one other cutting edge 50. This cutting edge has negative axial and positive radial rake surfaces. The at least one other cutting edge cooperates with the first and second cutting edges to form a radiused hole when rotated about the central axis.
Referring now to Figures 15 ~hrough 17, there is a further embodiment of the drill wherein the second cut-ting edge 14 is concave 52.
According to the invention, disclosed is a drill as can be seen in Figures 1 and 2, but can be best seen in Figure 4. The drill has a shank 4 and the shank has a central axis of rotation 6. The direction of rotation is shown by arro~ 7. There is only one cutting insert 8 disposed on the end 10 of the shank. As shown in Figure 4, the insert has first and second cutting edges 12 and 14, respectively, and clearance face 54. The first cut-ting edge 12 extends inwardly and parallel to a plane 56 containing the axis of rotation. The plane rotation.
The plane 56 is positioned so as to be perpendicular to lZ~ S66 the plane of the paper. The second cutting edge 14 extends inwardly from the first cutting edge and when viewed from the end forms an included angle 58 of greater than 90 degrees therewith. The first and second cutting edges are oriented along the forward portion 60 in the rotational sense of the clearance face 54. The clearance face intersects the plane 56 without intersecting the axis of rotation. The intersection of the clearance face and the plane is along a line that would be drawn from 62 to 64. The first and second cutting edges cooperate so as to rotatably cut a hole.
The operation of the drill according to the inven-tion is schematically illustrated in ~igure 3. Hole 16 is being drilled with outer portion 18 of the hole being removed by the first cutting edge and the inner portion 20 of the hole being removed by the first cutting edge.
In order for the objects of the invention to be achieved, the second cutting edge is located slightly off center so as to avoid any point of zero velocity. Because the second cutting edge is located sllghtly off center, ~ou get nib 22, which is broken off periodically during the operation of the drill.
According to the invention, there is disclosed a drill 2 as can also be seen in Figures 1 and 2. There is a shank 4 having a cental axis of rotation 6. There is at least one cutting insert 8 disposed on the end 10 of the shank. For larger holes, it may be preferable to have two or more inserts located on the end of the shank.
lZ~375~
For larger holes, it may be preferable to have two or more inserts located on the end of the shank. Referring now to Figure 4, the insert has first and second cutting edges 12 and 14, respectively, and a clearance face 54.
The first cutting edge 12 extends inwardly and para:Llel to a plane 56 containing the axis of rotation. This plane 56 is perpendicular to the plane of the paper. The second cutting edge 14 extends inwardly from the first cutting edge and when viewed from the end forms an included angle 58 of greater than 90 degrees therewith.
The first and second cutting edges are oriented along the forward portion 60 in the rotational sense of the clear-ance face 54. The clearance face intersects the plane 56 without intersecting the axis of rotation. The first and second cutting edges cooperate so as to rotatably cut a hole.
The preferred use of this invention is for holes less than about one inch in diameter, in which case one insert would preferably be used. However, drilled holes greater than about one inch in diameter are also contem-plated within the scope of the invention~ In this latter case, it may be found to be preferable to use two or more inserts.
The second cutting edge has a rake face 24 and, preferably, the axis of rotation 6 passes through the rake face.
Preferably, the first cutting edge has a negative radial rake surface and the second cutting edge has i2~7Sf~6 negative axial and positive radial rake surfaces. The first cutting edge also has a zero axial rake or positive axial rake. Preferably, the insert is indexable.
In a preferred embodiment, the first cutting edge 12 is substantially perpendicular to the axis of rotation 6 so that a hole with a substantially flat bottom is formed. In the prior art, it was thought to be impossi-ble to get a flat bottom hole; however, such a hole is found to be achievable according to the invention.
As can be seen in Figures 1 and 7, the insert 8 is in the shape of a diamond when viewed in plan and the smaller of the included angles at 26 of the diamond is between 75 degrees and 85 degrees. Normally, with such an insert shape, there would be two cutting positions located at 28 and 30.
In another embodiment, as shown in Figures 5 an 10, the insert 8 is in the shape of a square when viewed in plan. With this type of insert, it is possible to have four cutting positions with each cutting position located at the corners 34, 36, 38 and 40 of the square. Because of the clearance angles required on the outside of the insert, the insert must be tilted slightly. Accordingly, a flat bottom hole is no longer possible with a s~uare insert.
The shank has a reduced diameter portion 42. The insert is disposed on the end 10 of the reduced diameter portion of the shank.
75~6 The insert is held to the shank by fastening means 44 passing through a perforation 46 in the insert. The fastening means terminates in a recess 94 in the shank.
The drill preferably comprises means 66 for supply-ing coolant. The coolant means are internal to the shank and exit the shank at the end 10 of the reduced diameter portion.
In another embodiment, as shown in Figures 12 through 14, the second cutting edge is comprised of a plurality of cutting segments. As shown in the figures, there is one additional segment 50, but it is contem-plated within t~e scope of the invention that there may be several such segments. The orientation of each of the segments differs in orientation rom the previous cutting segment so that when viewed from the end the included angle 58 between the first of the segments and the first cutting edge and the included angle 68 hetween each sub~
sequent cutting segment and the previous cutting segment is greater than 90 degrees.
A further embodiment is now shown in ~igures 15 through 17. In this embodiment of the drill, the second cutting edge 14 is substantially concave as shown by 52.
The concave cutting edge 52 and its axial rake face 70 form a groove which narrows in depth 72 and width 74 away from the concave cutting edge 52.
According to the invention, there is a cutting insert disclosed as shown in Figures 6 through 8. The insert is comprised of a body of hard wear resistant :1~07566 material having top 76 and bottom 78 faces and a peri-pheral wall 80 joining the top and bottom faces. The hard wear resistant material is preferably cemented carbide. The body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face. First cutting edges 12 are formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall.
One end of each of the first cutting edges terminates in a jt~ncture 82 with a second cutting edge 14 that extends from the cutting face toward the seating face. The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis.
Each of the second cutting edges has a rake face 24 which extends upwardly away from the bottom face so that it breaks out through the cutting face at 48.
It is preferable that the insert is indexable.
Preferably, the insert is in the shape of a diamond when viewed in plan and the smaller of the included 20 angles at 26 of the diamond is between 75 degrees and 85 degrees. As shown in the figures, there would normally be two cutting positions located at 28 and 30.
Referring now to Figures 9 through ll, the insert may be in the shape of a square when viewed in plan.
When the insert has a square shape, there would normally be four cutting pGsitions located at each corner of the square.
~2a~ i6 In another embodiment of the insert, as shown in Figures 12 through 14, each of the second cutting edges 14 joins with at least one other cutting edge 50 that extends toward the seating face.
In a further embodiment, as shown in Figures 15 through 17, each of the second cutting edges 1~ of the insert is concave away from the seating face.
According to the invention, there is disclosed a hard wear resistant cutting insert. The hard wear resistant material is preferably cemented carbide. As best seen in Figures 6 through 8, there is a top 76 and a bottom 78 parallel to the top joined by four lateral faces 80. At least one of the lateral faces is a clear-ance face 54. The clearance face has a first cutting edge 12 which is formed by the intersection of the top 76 and the clearance face 54. There is a second cutting edge 14 intersecting at 82 the first cutting edge at an included angle 58 of greater than 90 degrees when viewed perpendicularly to the clearance face. The second cut-ting edge is formed by the intersection of a rake face 24of the second cutting edge and the clearance face. The rake face is defined by a plane which intersects the clearance face at 14, one of the lateral faces at 84 and the top at 86. This plane is not perpendicular to either of the clearance face, the one of the lateral faces or the top so that a flat is formed extending away from the second cutting edge.
Most preferably, the insert is indexable.
-20~
lZ~3'7566 Preferably~ the insert is in the shape of a diamond when viewed in plan and the smaller of the included angles at 26 of the diamond is between 75 degrees and 85 degrees. With a diamond shape, there would normally be two cutting positions.
Preferably, also, the insert is in the shape of a square when viewed in plan, and there would normally be four cutting positions.
In another embodiment of the insert, as shown in Figures 12 through 14, the second cutting edge comprises a plurality of cu~ting segments. The orientation of each of the segments differs in orientation from the previous cutting segment so that, when viewed perpendicular to the clearance face 54, the included angle 58 between the first 14 face segments and the first cutting edge 12 and the included angle 6g between each subsequent cutting segment 50 and the previous cutting segment is greater than 90 degrees. Each of the segments has a rake face 88 and 90 which differs in orientation corresponding to the differing in orientation of each of the segments 14 and 50, respectively. Each of the rake faces intersects the rake faces on either side thereof. As shown in the figures, rake faces 88 and 90 would intersect at 92. The lines of intersection formed by the rake faces all con-verge to a point 48 away from the segments.
In a further embodiment of the insert, as shown in Figures 15 through 17, the second cutting edge 14 has a concave portion 52 and a corresponding concave axial rake 12~5~;
face 70. The concave portion and the axial rake face form a groove which narrows in depth 72 and width 74 away from the cutting force.
Modifications may be made within the scope of the appended claims.
-22~-
Claims (54)
1. A drill comprising: a shank having a central axis of rotation; only one insert on one end of said shank, said insert having two cutting edges; said first cutting edge having a negative radial rake surface and said second cutting edge having negative axial and positive radial rake surfaces;
said first and second cutting edges cooperating to form a radiused hole when rotated about said central axis with said central axis of rotation passing through the axial rake face of said second cutting edge.
said first and second cutting edges cooperating to form a radiused hole when rotated about said central axis with said central axis of rotation passing through the axial rake face of said second cutting edge.
2. A drill comprising: a shank having a central axis of rotation; at least one insert on one end of said shank, said insert having two cutting edges; said first cutting edge having a negative radial rake surface and said second cutting edge having negative axial and positive radial rake surfaces;
said first and second cutting edges cooperating to form a radiused hole when rotated about said central axis with said central axis of rotation passing through the axial rake face of said second cutting edge.
said first and second cutting edges cooperating to form a radiused hole when rotated about said central axis with said central axis of rotation passing through the axial rake face of said second cutting edge.
3. The drill of Claim 1 wherein said first cutting edge has zero axial rake.
4. The drill of Claim 1 wherein said first cutting edge has positive axial rake.
5. The drill of Claim 1 wherein said insert is index-able.
6. The drill of Claim 5 wherein said first cutting edge is substantially perpendicular to said central axis of rotation so that a hole with a substantially flat bottom is formed.
7. The drill of Claim 5 wherein said insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of said diamond is between 75 degrees and 85 degrees.
8. The drill of Claim 5 wherein said insert is in the shape of a square when viewed in plan.
9. The drill of Claim 5 wherein said shank has a reduced diameter portion, said insert being disposed on said end of said reduced diameter portion of said shank.
10. The drill of Claim 9 wherein said insert is held to said shank by fastening means passing through a perforation in said insert and terminating in a recess in said shank.
11. The drill of Claim 1 wherein said second cutting edge axial rake face extends outwardly with respect to said insert so as to break out of said insert.
12. The drill of Claims 1 or 2 wherein said insert has at least one other cutting edge having negative axial and positive radial rake surfaces, said at least one other cutting edge cooperating with said first and second cutting edges to form a radiused hole when rotated about said central axis.
13. The drill of Claims 1 or 2 wherein said second cutting edge is concave.
14. A drill comprising: a shank having a central axis of rotation; only one cutting insert disposed on the end of the shank and having first and second cutting edges and a clearance face, said first cutting edge extending inwardly and parallel to a plane containing said axis of rotation, said second cutting edge extending inwardly from said first cutting edge and, when viewed from the end, forming an included angle of greater than 90 degrees therewith, said first and second cutting edges oriented along the forward portion, in the rotational sense, of said clearance face, said clearance face intersecting said plane without inter-secting said axis of rotation, said first and second cutting edges cooperating so as to rotatably cut a hole and said second cutting edge having a rake face with said axis of rotation passing through said rake face.
15. A drill comprising: a shank having a central axis of rotation; at least one cutting insert disposed on the end of the shank and having first and second cutting edges and a clearance face, said first cutting edge extending inwardly and parallel to a plane containing said axis of rotation, said second cutting edge extending inwardly from said first cutting edge and when viewed from the end forming an included angle of greater than 90 degrees therewith, said first and second cutting edges cooperating so as to rotatably cut a hole, said second cutting edge having a rake face and said axis of rotation passing through said rake face.
16. The drill of Claim 14 wherein said second cutting edge has a rake face and said axis of rotation passes through said rake face.
17. The drill of Claim 16 wherein said first cutting edge has a negative radial rake surface and said second cutting edge has negative axial and positive radial rake surfaces.
18. The drill of Claim 17 wherein said first cutting edge has zero axial rake.
19. The drill of Claim 17 wherein said first cutting edge has positive axial rake.
20. The drill of Claim 17 wherein said insert is indexable.
21. The drill of Claim 20 wherein said first cutting edge is substantially perpendicular to said axis of rotation so that a hole with a substantially flat-bottom is formed.
22. The drill of Claim 21 wherein said insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of said diamond is between 75 degrees and 85 degrees.
23. The drill of Claim 20 wherein said insert is in the shape of a square when viewed in plan.
24. The drill of Claim 20 wherein said shank has a reduced diameter portion, said insert being disposed on said end of said reduced diameter portion of said shank.
25. The drill of Claim 24 wherein said insert is held to said shank by fastening means passing through a perfora-tion in said insert and terminating in a recess in said shank.
26. The drill of Claim 24 further comprising means for supplying coolant which are internal to said shank and exit said shank at said end of said reduced diameter portion.
27. The drill of Claim 20 wherein said second cutting edge comprises a plurality of cutting segments, the orienta-tion of each of said segments differing in orientation from the previous cutting segment so that when viewed from the end the included angle between the first of said segments and said first cutting edge and between each subsequent cutting segments and the previous cutting segment is greater than 90 degrees.
28. The drill of Claim 20 wherein said second cutting edge is substantially concave, said concave cutting edge and its axial rake face forming a groove which narrows in depth and width away from said concave cutting edge.
29. The drill of Claim 15 wherein said second cutting edge has a rake face and said axis of rotation passes through said rake face.
30. The drill of Claim 29 wherein said first cutting edge has a negative radial rake surface and said second cutting edge has negative axial and positive radial rake surfaces.
31. The drill of Claim30 wherein said first cutting edge has zero axial rake.
32. The drill of Claim30 wherein said first cutting edge has positive axial rake.
33. The drill of Claim30 wherein said insert is indexable.
34. The drill of Claim 33 wherein said first cutting edge is substantially perpendicular to said axis of rotation so that a hole with a substantially flat bottom is formed.
35. The drill of Claim 34 wherein said insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of said diamond is between 75 degrees and 85 degrees.
36. The drill of Claim 33 wherein said insert is in the shape of a square when viewed in plan.
37. The drill of Claim 33 wherein said shank has a reduced diameter portion, said insert being disposed on said end of said reduced diameter portion of said shank.
38. The drill of Claim 37 wherein said insert is held to said shank by fastening means passing through a perfora-tion in said insert and terminating in a recess in said shank.
39. The drill of Claim 37 further comprising means for supplying coolant which are internal to said shank and exit said shank at said end of said reduced diameter portion.
40. The drill of Claim 33 wherein said second cutting edge comprises a plurality of cutting segments, the orienta-tion of each of said segments differing in orientation from the previous cutting segment so that when viewed from the end the included angle between the first of said segments and said first cutting edge and between each subsequent cutting segments and the previous cutting segment is greater than 90 degrees.
41. The drill of Claim 33 wherein said second cutting edge is substantially concave, said concave cutting edge and its axial rake face forming a groove which narrows in depth and width away from said concave cutting edge.
42. A cutting insert comprising: a body of hard wear resistant material having top and bottom faces and a peripheral wall joining said top and bottom faces; said body being polygonal when viewed in plan; one of said top and bottom faces acting as a seating face and the other acting as a cutting face; first cutting edges formed on opposite sides of said cutting face at the juncture of said cutting face with said peripheral wall; one end of each of said first cutting edges terminating in a juncture with a second cutting edge that extends from said cutting face toward said seating face; said first and second cutting edges cooperating to form a radiused hole when rotated about a central axis, a rake face next to said second cutting edge with said central axis of rotation passing through said surface.
43. The cutting insert of Claim 42 wherein each of said second cutting edges has a rake face which extends upwardly away from said bottom face so that it breaks out through said top face.
44. The cutting insert of Claim 43 wherein said insert is indexable.
45. The insert of Claim 44 wherein said insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of said diamond is between 75 degrees and 85 degrees.
46. The insert of Claim 44 wherein said insert is in the shape of a square when viewed in plan.
47. The cutting insert of Claim 42 wherein each of said second cutting edges joins with at least one other cutting edge that extends toward said seating face.
48. The cutting insert of Claim 42 wherein each of said second cutting edges is concave away from said seating face.
49. A hard, wear resistant cutting insert comprising:
a top and a bottom parallel to said top joined by four lateral faces, at least one of said lateral faces being a clearance face, said clearance face having a first cutting edge which is formed by the intersection of said top and said clearance face and a second cutting edge intersecting said first cutting edge at an included angle of greater than 90 degrees, when viewed perpendicular to the clearance face, which is formed by the intersection of a rake face of said second cutting edge and said clearance face, said rake face defined by a plane which intersects said clearance face, one of said lateral faces and said top and is not perpendicular to any of them so that a flat is formed extending away from said second cutting edge, said first and second cutting edges cooperating to form a radiused hole when rotated about a central axis and said central axis of rotation passing through said second cutting edge rake face.
a top and a bottom parallel to said top joined by four lateral faces, at least one of said lateral faces being a clearance face, said clearance face having a first cutting edge which is formed by the intersection of said top and said clearance face and a second cutting edge intersecting said first cutting edge at an included angle of greater than 90 degrees, when viewed perpendicular to the clearance face, which is formed by the intersection of a rake face of said second cutting edge and said clearance face, said rake face defined by a plane which intersects said clearance face, one of said lateral faces and said top and is not perpendicular to any of them so that a flat is formed extending away from said second cutting edge, said first and second cutting edges cooperating to form a radiused hole when rotated about a central axis and said central axis of rotation passing through said second cutting edge rake face.
50. The insert of Claim 49 wherein said insert is indexable.
51. The insert of Claim 50 wherein said insert is in the shape of a diamond when viewed in plan and the smaller of the included angles of said diamond is between 75 degrees and 85 degrees.
52. The insert of Claim50 wherein said insert is in the shape of a square when viewed in plan.
53. The insert of Claim 49 wherein said second cutting edge comprises a plurality of cutting segments, the orienta-tion of each of said segments differing in orientation from the previous cutting segment so that when viewed perpendicu-lar to the clearance face, the included angle between the first of said segments and said first cutting edge and between each subsequent cutting segment and the previous cutting segment is greater than 90 degrees, each of said segments having a rake face which differs in orientation corresponding to the differing in orientation of each of said segments, each of said rake faces intersecting the rake faces on either side thereof, the lines of intersection formed by said rake faces all converging to a point away from said segments.
54. The insert of Claim 49 wherein said second cutting edge has a concave portion and a corresponding concave axial rake face, said concave portion and axial rake face forming a groove which narrows in depth and width away from said con-cave cutting portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US39560482A | 1982-07-06 | 1982-07-06 | |
| US395,604 | 1982-07-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207566A true CA1207566A (en) | 1986-07-15 |
Family
ID=23563720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000431130A Expired CA1207566A (en) | 1982-07-06 | 1983-06-24 | Drill and indexable carbide insert therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1207566A (en) |
-
1983
- 1983-06-24 CA CA000431130A patent/CA1207566A/en not_active Expired
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