CA1074985A - Machine tool cutter - Google Patents
Machine tool cutterInfo
- Publication number
- CA1074985A CA1074985A CA302,708A CA302708A CA1074985A CA 1074985 A CA1074985 A CA 1074985A CA 302708 A CA302708 A CA 302708A CA 1074985 A CA1074985 A CA 1074985A
- Authority
- CA
- Canada
- Prior art keywords
- face
- cutter
- tool
- discs
- disc
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D43/00—Broaching tools
- B23D43/02—Broaching tools for cutting by rectilinear movement
- B23D43/04—Broaching tools for cutting by rectilinear movement having inserted cutting edges
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Milling Processes (AREA)
- Milling, Broaching, Filing, Reaming, And Others (AREA)
Abstract
MACHINE TOOL CUTTER
Abstract of the Disclosure A metal cutting tool is described having an elongated tool body with an elongated tool face portion. A
plurality of recesses are formed in the tool face, each having a flat bottom face inclined inwardly and rearwardly to the longitudinal axis of the tool body. Each recess contains a rotatably indexable cylindrical cutter disc with an end face resting on the flat bottom of the recess.
Each cutter disc has a generally cylindrical edge face including a generally concave cutter portion forming an acute angle with an adjacent end face of the disc. The magnitude of this acute angle and the degree of inclination of the recess flat bottom face are such as to provide a positive rake angle of 1-25° between the cutter portion and the work cut.
Abstract of the Disclosure A metal cutting tool is described having an elongated tool body with an elongated tool face portion. A
plurality of recesses are formed in the tool face, each having a flat bottom face inclined inwardly and rearwardly to the longitudinal axis of the tool body. Each recess contains a rotatably indexable cylindrical cutter disc with an end face resting on the flat bottom of the recess.
Each cutter disc has a generally cylindrical edge face including a generally concave cutter portion forming an acute angle with an adjacent end face of the disc. The magnitude of this acute angle and the degree of inclination of the recess flat bottom face are such as to provide a positive rake angle of 1-25° between the cutter portion and the work cut.
Description
Background of the Invention 1. Field of the Invention ,_ This invention relates to a novel machine tool cutter and particularly to a broaching tool in which the cutting surfaces are at a positive rake angle to the work cut.
2. Description of the Prior Art -The typical broaching tool is in the form of an elongated body having a plurality of spaced annular ribs generally transverse to the longitudinal axis of the body.
10 A series of titanium carbide teeth are braised onto side walls of these ribs in a position perpendicular to the longitudinal body axis. Each of these teeth has a curved upper cutting edge and normally engages the work cut on the work piece at a negative rake angle.
The usual designs have placed tremendous stresses on the tool and the cutter teeth as well as on the work piece being broached. There have been various attempts in the past to develop new designs which will decrease the load on individual cutters, such as the tooth design shown in 20 U.S. Patent 3,849,852, issued November 26, 1974. That design in theory decreases the load because the individual -tooth takes a narrow deep cut rather than a wide shallow cut.
U.S. Patent 1,945,535, issued February 6, 1934, des-cribes a broaching tool having cutters with a positive rake angle and a specially designed chip relief groove.
The cutter at a positive rake angle will in theory take a cleaner cut and leave a smoother surface behind the cut by rolling the chip formed into the chip relief groove, 30 thereby reducing fracturing off of small particles and serving to reduce generation of heat in the work and in the tool.
As a tool cutter is forced through a work piece, high friction is generated between the tool face and the com-pressed material adjacent the tool face. With the high temperature and high specific pressure present, a layer of material clings to the tool face to form what is known as a built-up edge. This built-up edge is, -therefore, forced through the work by the cutter face and does the actual fracturing or cutting. The chip body shears away from this built-up edge and passes off above.
As the built-up edge becomes larger and larger, it becomes more and more unstable until fragments thereof are torn off. The built-up edge is, therefore, continually varying in size and attacking the area of fracture or shear with a varying area which causes roughness. Further-more, as the built-up edge increases in size, the chip being formed and following upwardly of the tool face is subjected to a band of increasing curvature which would remain at a substantially constant value if the built-up edge can be kept at a reduced size.
Such problems were recognized by the inventors in U.S.
Patent 2,392,481, issued January 18, 1946, but they con-tinued to work on the size and shape of the chip relief grooves much in the manner as was done by the inventor in U.S. Patent 1,945,535.
None of these prior designs was able to solve the problem of the immense pressures and built-up edge which caused the cutting edge to quickly wear and frequently break wlth the resultant rough work piece surface behind the cut.
; In Proulx et al U.S. Patent 3,946,472, issued March 30,1976, there is described a broaching tool in which the cutter teeth are in the snape of buttons or discs. This had the unique feature of being able to make use of the angular position of the discs so as to form a smoothly curving contoured surface. This represented a very significant advance in the art in being able to greatly reduce the power required per unit volume of chip removed. The result was less wear on the individual cutters, less breakage of cutters and less damage to the work piece being machined.
It is, therefore, the object of the present invention to provide an improved configuration of tool cutter which can take advantage of the benefits of U.S. Patent 3,946,472 while providing a positive ral~e angle between the cutter face and the work cut.
Summary of the Invention In accordance with the present invention there is pro-vided a novel metal cutting tool comprising an elongated tool body having an elongated tool face portion. A plurality of recesses or pockets are formed ln the tool face, each having a flat bottom face inclined inwardly and rearwardly to the longitudinal axis of the tool body. Cylindrical cutter discs are mounted in the recesses with an end face of each cutter resting on a recess flat bottom face. Each cutter disc has a ~enerally cylindrical edge face with a generally concave cutter portion forming an acute angle with an adjacent end face of the disc. The magnitude of this acute angle and the degree of inclination of the recess flat bottom face are such as to provide a positive rake angle of 1-25, preferably 5-20, between the cutting portion of the cutter disc and the work cut.
The tool face can be arcuate or it can be flat. The arcuate face typically forms an arc of at least 45 and usually at least 90. For a typical half-round broach, the arc will be in excess of 180 and it may even form a full cylindrical broach.
The angle of the cutter discs with respect to the longitudinal axis of the tool body will normally be varied within the range of about 1-15. ~n angle of about 10-15 is particul~arly preferred.
The cutter discs themselves are preferably quite small, typically having a diameter of about 0.4 to 1.0 inch. The thickness of each cutter disc is preferably in the range of about 0.15 to 0.4 inch.
The cutter discs are preferably arranged in rows transverse to the longitudinal axis of the tool bodyA These rows can be perpendicular to the longitudinal axis or they can define helical paths. The discs of each row are stag-gered laterally with respect to the discs of the next ad-jacent row whereby paths of successive cutter discs partially overlap. For the arcuate tool faces, the rows of cutter discs are preferably of increasing diameter in a rearward direction so as to produce a progressively larger hole as the broach is moved through the work piece or the work piece over the broach.
When the cutter discs are arranged in helical paths, these normally define an angle of about 5 to 95 with res-pect to the longitudinal axis of the tool body and a typical tool has a helical angle in the order of about 15 to 45.
The helical configuration has been found to be particularly advantageous in providing an exceptionally low impact load between the cutter discs and the work piece. In other words, with the helical configuration some of the discs will always :
.
, ~' be under load and this overcomes any tendency of impact as successive rows of cutter discs come into engayement with the work piece. This greatly decreases the tendency of damage to the cutting tool as well as possible breakage of the work piece being broached.
By setting the series of small cylindrical cutting discs at a small angle with respect to the longitudinal axis of the tool body, the cutting edges of these cutter discs form small arcs of a much larger circle than the diameter of the discs themselves. This, combined with the overlapping of the successive cutters due to the staggered arrangement of cutters in successive rows, results in a smooth finished surface having very shallow grooving which is easily removed by a finishing tool. This is true whether these cutter discs are being used for planing a flat surface or for broaching a round hole.
An important feature of the present invention is the shape of the indexable cutter inserts. As mentioned above, - these are preferably of a quite small diameter and are used in large numbers. For instance, a half-round helical broach for cutting a hole two inches in diameter will use 99 cutter discs each 1/2 inch in diameter.
- Each disc is of a generally annular configuration with a countersink axial hole through which a screw passes to hold the cutter disc in position in a tool face recess.
Each disc is preferably symmetrical, defining a cutting edge at both the top and bottom, but it is equally possible to have a design which is not symmetrical.
The cylindrical edge face of each disc can assume a - 30 wide variety of profiles, with a simple concave arc of a circle being the most convenient. It is, however, immaterial whether the profile is in the form of flat or curved lines, provided the angle between the cylindrical face and the adjacent encl face of a disc forms an acute angle which, together with the degree of inclination of a disc with respect to the longitudinal axis of a tool body provides a positive rake angle of 1-25 between the cutter face and the work cut.
Certain preferred embodiments of the present invention will now be illustrated by the attached drawings in which:
Figure 1 is a side elevatlon of one embodiment of a novel broaching tool;
Figure 2 is a top plan view of the broaching tool shown in Figure l;
Figure 3 is a eross seetion through row 1 of the tool of Figure l;
Figure 4 is a cross section through row 2 of the tool of Figure l;
Figure 5 is an exploded detail view of a eutting dise and soeket;
Figure 6 shows a transverse section through a eutter aeeording to the invention together with a work pieee on whieh it is funetioning; and Figures 7a to 7i show different eonfigurations of eutter dises aeeording to the invention.
The partieular broaeh illustrated in the drawings is known as a half-round broaeh. This partieular one has been illustrated sinee it is generally the most eomplex form of tool and the size, spaeings, ete. of the eutter dises apply equally to a flat broaeh as to the eonfiguration illustrated.
Looking now at the drawings, the deviee ineludes an `~
elongated tool holder body portion 20 having a bottom spline 21 extending along the len~th thereof for retaining the tool in a tool holder (not shown). The tool is held rigidly in place in the holder by the mounting screws 22.
A series of cutter discs 24 are mounted in sockets 25 in the cylindrical surface. Each of these sockets have a flat bottom face 26 which is inclined at a small angle(b) of typically about 12 to 15 to the longitudinal axis of the body portion 20 and the socket also has a semi-circular abutment wall 27 shaped to mate with the corresponding por-tion of a cutter disc. Extending into the body portion 20 through face 26 is a tapped hole 32.
One preferred form of cutting disc is shown at 24 and this has a concave cylindrical wall 29 and bevelled end faces 28. A hole 31 is formed axially through the insert with a conical countersink 30. The cutting disc is typically made from high speed steel, although any other suitable material can be used. It is held in position by means of a threaded screw 33 having a conical head portion which mates with the countersink of the cutting disc and the head of the screw includes a socket 34 for receiving a wrench.
When the cutting disc has been placed in position in the socket 25 and the screw tightened, the insert is pressed firmly against the abutment wall 27. Thus, when the broach is in operation, the forces on the cutting inserts are fully carried by the abutment walls 27 rather than by .
the screws themselves.
With this arrangement, it will be seen that only about 1/4 of the cutting edge of the cutter discs is used at one time. This means that as the portion in use becomes dulled, the screw 33 can be loosened and the cutter discs can then ' ; ~ .
be rotated sufficiently to present fresh cutting edge portions, after which the screws are again tightelled. The result is that as many as four cutting edge portions may be available on one face of a cutter disc. Furthermore, if the discs are symmetrical, they may be reversed so that another four cutting edge portions may be available on the reverse face. In this way, as many as eiaht fresh cutting edge portions may be obtainable from a single cutting disc.
In Figure 1, eight helical rows of cutting discs are shown and these are indicated as rows 1 to 8. Figure 3 shows the positioning of the cutter discs for what are designated as rows 1, 3, 5 and 7 in Figure 1 while Figure 4 is a cross section showing the position of the cutter discs for the rows designated as 2, 4, 6, and 8 in Figure 1.
Particularly from Figures 3 and 4, it becomes evident that the successive rows of cutting inserts are positioned in a circumferentially staggered manner. Thus, the axis of the cutting inserts of row 2 are positioned midway between the axis of the inserts of row 1 while the inserts of row 3 are in alignment with the inserts of row 1. The diameter typically is increased by an amount of about 0.004 inch from one row to the next following row. However, it is also possible to have two or more adjacent rows of the same diameter followed by two or more rows of increased equal diameter. It is also sometimes desirable to have the last cutting insert of one row at the same elevation as the first cutting insert of the next following row. Moreover, when the inserts are mounted on a flat broach, they may all be positioned identically on the tool body and the entire tool body can be tilted slightly to increase the cut from one row of inserts to the next.
: ' Looking now at l;`igure 6, the bevelled end face 28 of cutter disc 24 provides a clearance angle with respect to the work cut 35 of about 1-3. Because the cutter discs of this invention are of a relatively small diameter, the effect of the positive rake angle is not simply that of lifting the chip 36 away from the work cut 35 but because the surface 29 is both inclined vertically away from the cutting edge and at the same time is circular in cross section, the chip 36 tends to lift and at the same time fracture or shear so as to spread to each side of a disc in a plowing action. This is highly effective in preventing the build up of a compressed mass between the cutting edge and the work plece so that a smooth clean cut is formed.
Turning now to Figure 7, a variety of different con-figurations of the cutter discs are shown with Figure 7a representing the disc shown in Figure 5. As aan be seen from Figure 7a, the end faces 28 are bevelled at an angle c. This angle c is typically in the range of 12 - 15.
The angle d is the angle between axes of the disc and a -20 tangent to the cutting face and this is typically in the range of 35 - 45. Thus, in a typical preferred embodiment ; angle d is 39, angle c is 11, angle b is 12~ and rake angle a is 15. Such a cutter disc has a diameter of 0.5 inch, a thickness of 0.1875 inch and the edge face is an arc of radius 0.125 inch.
Figure 7b shows a generally similar symmetrical cutter disc to that of Figure 7a with the arcuate edge face 29 being replaced by a pair of inwardly inclined faces 40 meeting at the center point. Figure 7c again is a symmetrical design -having a central cylindrical edge portion 41 and inclined faces 42 providing the required positive rake angle for the - cutting edge.
~ g Figure 7d is a non-symmetrical design having a lower cylindrical edge portion 43 and an upper inclined edge 44 forming the positive rake cutting edge. While the design of Figure 7d is not reversible, it has the advantage that the abutment face 27 of the tool recess 25 can be o' cylindrical configuration rather than being machined to mate with the shapes of Figures 7a to 7c. Figure 7e, like Figure 7d, again has a lower cylindrical edge face 45 which merges into an upper concave arcuate face 46 forming the positive rake cutting face.
Figure 7f is a non-symmetrical design in which the edge face is formed primarily of an arcuate face of large diameter merging into an arcuate face of smaller diameter at the upper corners. There is no bevel on the end face.
These provide a sharper cutting edge with a steeper rake angle than, for instance, the design of Figure 7a.
Figure 7g shows a symmetrical configuration which is generally similar to Figure 7c without end bevels. The side edges have a central cylindrical portion 48 merging into upper and lower arcuate portions 50 forming the positive rake angle cutting faces. Figure 7h also represents a symmetrical design, without end bevels, in this case with the side edge of the cutter disc being divided into a pair of equal arcuate concave faces 51 joined at a central point 52.
Figure 7i is a non-symmetrical configuration generally along the lines of Figure 7e with a lower cylindrical portion 53, but without the end bevel. The cutting portion is formed in a pro~ection 54 and comprises an arcuate concave face 55.
10 A series of titanium carbide teeth are braised onto side walls of these ribs in a position perpendicular to the longitudinal body axis. Each of these teeth has a curved upper cutting edge and normally engages the work cut on the work piece at a negative rake angle.
The usual designs have placed tremendous stresses on the tool and the cutter teeth as well as on the work piece being broached. There have been various attempts in the past to develop new designs which will decrease the load on individual cutters, such as the tooth design shown in 20 U.S. Patent 3,849,852, issued November 26, 1974. That design in theory decreases the load because the individual -tooth takes a narrow deep cut rather than a wide shallow cut.
U.S. Patent 1,945,535, issued February 6, 1934, des-cribes a broaching tool having cutters with a positive rake angle and a specially designed chip relief groove.
The cutter at a positive rake angle will in theory take a cleaner cut and leave a smoother surface behind the cut by rolling the chip formed into the chip relief groove, 30 thereby reducing fracturing off of small particles and serving to reduce generation of heat in the work and in the tool.
As a tool cutter is forced through a work piece, high friction is generated between the tool face and the com-pressed material adjacent the tool face. With the high temperature and high specific pressure present, a layer of material clings to the tool face to form what is known as a built-up edge. This built-up edge is, -therefore, forced through the work by the cutter face and does the actual fracturing or cutting. The chip body shears away from this built-up edge and passes off above.
As the built-up edge becomes larger and larger, it becomes more and more unstable until fragments thereof are torn off. The built-up edge is, therefore, continually varying in size and attacking the area of fracture or shear with a varying area which causes roughness. Further-more, as the built-up edge increases in size, the chip being formed and following upwardly of the tool face is subjected to a band of increasing curvature which would remain at a substantially constant value if the built-up edge can be kept at a reduced size.
Such problems were recognized by the inventors in U.S.
Patent 2,392,481, issued January 18, 1946, but they con-tinued to work on the size and shape of the chip relief grooves much in the manner as was done by the inventor in U.S. Patent 1,945,535.
None of these prior designs was able to solve the problem of the immense pressures and built-up edge which caused the cutting edge to quickly wear and frequently break wlth the resultant rough work piece surface behind the cut.
; In Proulx et al U.S. Patent 3,946,472, issued March 30,1976, there is described a broaching tool in which the cutter teeth are in the snape of buttons or discs. This had the unique feature of being able to make use of the angular position of the discs so as to form a smoothly curving contoured surface. This represented a very significant advance in the art in being able to greatly reduce the power required per unit volume of chip removed. The result was less wear on the individual cutters, less breakage of cutters and less damage to the work piece being machined.
It is, therefore, the object of the present invention to provide an improved configuration of tool cutter which can take advantage of the benefits of U.S. Patent 3,946,472 while providing a positive ral~e angle between the cutter face and the work cut.
Summary of the Invention In accordance with the present invention there is pro-vided a novel metal cutting tool comprising an elongated tool body having an elongated tool face portion. A plurality of recesses or pockets are formed ln the tool face, each having a flat bottom face inclined inwardly and rearwardly to the longitudinal axis of the tool body. Cylindrical cutter discs are mounted in the recesses with an end face of each cutter resting on a recess flat bottom face. Each cutter disc has a ~enerally cylindrical edge face with a generally concave cutter portion forming an acute angle with an adjacent end face of the disc. The magnitude of this acute angle and the degree of inclination of the recess flat bottom face are such as to provide a positive rake angle of 1-25, preferably 5-20, between the cutting portion of the cutter disc and the work cut.
The tool face can be arcuate or it can be flat. The arcuate face typically forms an arc of at least 45 and usually at least 90. For a typical half-round broach, the arc will be in excess of 180 and it may even form a full cylindrical broach.
The angle of the cutter discs with respect to the longitudinal axis of the tool body will normally be varied within the range of about 1-15. ~n angle of about 10-15 is particul~arly preferred.
The cutter discs themselves are preferably quite small, typically having a diameter of about 0.4 to 1.0 inch. The thickness of each cutter disc is preferably in the range of about 0.15 to 0.4 inch.
The cutter discs are preferably arranged in rows transverse to the longitudinal axis of the tool bodyA These rows can be perpendicular to the longitudinal axis or they can define helical paths. The discs of each row are stag-gered laterally with respect to the discs of the next ad-jacent row whereby paths of successive cutter discs partially overlap. For the arcuate tool faces, the rows of cutter discs are preferably of increasing diameter in a rearward direction so as to produce a progressively larger hole as the broach is moved through the work piece or the work piece over the broach.
When the cutter discs are arranged in helical paths, these normally define an angle of about 5 to 95 with res-pect to the longitudinal axis of the tool body and a typical tool has a helical angle in the order of about 15 to 45.
The helical configuration has been found to be particularly advantageous in providing an exceptionally low impact load between the cutter discs and the work piece. In other words, with the helical configuration some of the discs will always :
.
, ~' be under load and this overcomes any tendency of impact as successive rows of cutter discs come into engayement with the work piece. This greatly decreases the tendency of damage to the cutting tool as well as possible breakage of the work piece being broached.
By setting the series of small cylindrical cutting discs at a small angle with respect to the longitudinal axis of the tool body, the cutting edges of these cutter discs form small arcs of a much larger circle than the diameter of the discs themselves. This, combined with the overlapping of the successive cutters due to the staggered arrangement of cutters in successive rows, results in a smooth finished surface having very shallow grooving which is easily removed by a finishing tool. This is true whether these cutter discs are being used for planing a flat surface or for broaching a round hole.
An important feature of the present invention is the shape of the indexable cutter inserts. As mentioned above, - these are preferably of a quite small diameter and are used in large numbers. For instance, a half-round helical broach for cutting a hole two inches in diameter will use 99 cutter discs each 1/2 inch in diameter.
- Each disc is of a generally annular configuration with a countersink axial hole through which a screw passes to hold the cutter disc in position in a tool face recess.
Each disc is preferably symmetrical, defining a cutting edge at both the top and bottom, but it is equally possible to have a design which is not symmetrical.
The cylindrical edge face of each disc can assume a - 30 wide variety of profiles, with a simple concave arc of a circle being the most convenient. It is, however, immaterial whether the profile is in the form of flat or curved lines, provided the angle between the cylindrical face and the adjacent encl face of a disc forms an acute angle which, together with the degree of inclination of a disc with respect to the longitudinal axis of a tool body provides a positive rake angle of 1-25 between the cutter face and the work cut.
Certain preferred embodiments of the present invention will now be illustrated by the attached drawings in which:
Figure 1 is a side elevatlon of one embodiment of a novel broaching tool;
Figure 2 is a top plan view of the broaching tool shown in Figure l;
Figure 3 is a eross seetion through row 1 of the tool of Figure l;
Figure 4 is a cross section through row 2 of the tool of Figure l;
Figure 5 is an exploded detail view of a eutting dise and soeket;
Figure 6 shows a transverse section through a eutter aeeording to the invention together with a work pieee on whieh it is funetioning; and Figures 7a to 7i show different eonfigurations of eutter dises aeeording to the invention.
The partieular broaeh illustrated in the drawings is known as a half-round broaeh. This partieular one has been illustrated sinee it is generally the most eomplex form of tool and the size, spaeings, ete. of the eutter dises apply equally to a flat broaeh as to the eonfiguration illustrated.
Looking now at the drawings, the deviee ineludes an `~
elongated tool holder body portion 20 having a bottom spline 21 extending along the len~th thereof for retaining the tool in a tool holder (not shown). The tool is held rigidly in place in the holder by the mounting screws 22.
A series of cutter discs 24 are mounted in sockets 25 in the cylindrical surface. Each of these sockets have a flat bottom face 26 which is inclined at a small angle(b) of typically about 12 to 15 to the longitudinal axis of the body portion 20 and the socket also has a semi-circular abutment wall 27 shaped to mate with the corresponding por-tion of a cutter disc. Extending into the body portion 20 through face 26 is a tapped hole 32.
One preferred form of cutting disc is shown at 24 and this has a concave cylindrical wall 29 and bevelled end faces 28. A hole 31 is formed axially through the insert with a conical countersink 30. The cutting disc is typically made from high speed steel, although any other suitable material can be used. It is held in position by means of a threaded screw 33 having a conical head portion which mates with the countersink of the cutting disc and the head of the screw includes a socket 34 for receiving a wrench.
When the cutting disc has been placed in position in the socket 25 and the screw tightened, the insert is pressed firmly against the abutment wall 27. Thus, when the broach is in operation, the forces on the cutting inserts are fully carried by the abutment walls 27 rather than by .
the screws themselves.
With this arrangement, it will be seen that only about 1/4 of the cutting edge of the cutter discs is used at one time. This means that as the portion in use becomes dulled, the screw 33 can be loosened and the cutter discs can then ' ; ~ .
be rotated sufficiently to present fresh cutting edge portions, after which the screws are again tightelled. The result is that as many as four cutting edge portions may be available on one face of a cutter disc. Furthermore, if the discs are symmetrical, they may be reversed so that another four cutting edge portions may be available on the reverse face. In this way, as many as eiaht fresh cutting edge portions may be obtainable from a single cutting disc.
In Figure 1, eight helical rows of cutting discs are shown and these are indicated as rows 1 to 8. Figure 3 shows the positioning of the cutter discs for what are designated as rows 1, 3, 5 and 7 in Figure 1 while Figure 4 is a cross section showing the position of the cutter discs for the rows designated as 2, 4, 6, and 8 in Figure 1.
Particularly from Figures 3 and 4, it becomes evident that the successive rows of cutting inserts are positioned in a circumferentially staggered manner. Thus, the axis of the cutting inserts of row 2 are positioned midway between the axis of the inserts of row 1 while the inserts of row 3 are in alignment with the inserts of row 1. The diameter typically is increased by an amount of about 0.004 inch from one row to the next following row. However, it is also possible to have two or more adjacent rows of the same diameter followed by two or more rows of increased equal diameter. It is also sometimes desirable to have the last cutting insert of one row at the same elevation as the first cutting insert of the next following row. Moreover, when the inserts are mounted on a flat broach, they may all be positioned identically on the tool body and the entire tool body can be tilted slightly to increase the cut from one row of inserts to the next.
: ' Looking now at l;`igure 6, the bevelled end face 28 of cutter disc 24 provides a clearance angle with respect to the work cut 35 of about 1-3. Because the cutter discs of this invention are of a relatively small diameter, the effect of the positive rake angle is not simply that of lifting the chip 36 away from the work cut 35 but because the surface 29 is both inclined vertically away from the cutting edge and at the same time is circular in cross section, the chip 36 tends to lift and at the same time fracture or shear so as to spread to each side of a disc in a plowing action. This is highly effective in preventing the build up of a compressed mass between the cutting edge and the work plece so that a smooth clean cut is formed.
Turning now to Figure 7, a variety of different con-figurations of the cutter discs are shown with Figure 7a representing the disc shown in Figure 5. As aan be seen from Figure 7a, the end faces 28 are bevelled at an angle c. This angle c is typically in the range of 12 - 15.
The angle d is the angle between axes of the disc and a -20 tangent to the cutting face and this is typically in the range of 35 - 45. Thus, in a typical preferred embodiment ; angle d is 39, angle c is 11, angle b is 12~ and rake angle a is 15. Such a cutter disc has a diameter of 0.5 inch, a thickness of 0.1875 inch and the edge face is an arc of radius 0.125 inch.
Figure 7b shows a generally similar symmetrical cutter disc to that of Figure 7a with the arcuate edge face 29 being replaced by a pair of inwardly inclined faces 40 meeting at the center point. Figure 7c again is a symmetrical design -having a central cylindrical edge portion 41 and inclined faces 42 providing the required positive rake angle for the - cutting edge.
~ g Figure 7d is a non-symmetrical design having a lower cylindrical edge portion 43 and an upper inclined edge 44 forming the positive rake cutting edge. While the design of Figure 7d is not reversible, it has the advantage that the abutment face 27 of the tool recess 25 can be o' cylindrical configuration rather than being machined to mate with the shapes of Figures 7a to 7c. Figure 7e, like Figure 7d, again has a lower cylindrical edge face 45 which merges into an upper concave arcuate face 46 forming the positive rake cutting face.
Figure 7f is a non-symmetrical design in which the edge face is formed primarily of an arcuate face of large diameter merging into an arcuate face of smaller diameter at the upper corners. There is no bevel on the end face.
These provide a sharper cutting edge with a steeper rake angle than, for instance, the design of Figure 7a.
Figure 7g shows a symmetrical configuration which is generally similar to Figure 7c without end bevels. The side edges have a central cylindrical portion 48 merging into upper and lower arcuate portions 50 forming the positive rake angle cutting faces. Figure 7h also represents a symmetrical design, without end bevels, in this case with the side edge of the cutter disc being divided into a pair of equal arcuate concave faces 51 joined at a central point 52.
Figure 7i is a non-symmetrical configuration generally along the lines of Figure 7e with a lower cylindrical portion 53, but without the end bevel. The cutting portion is formed in a pro~ection 54 and comprises an arcuate concave face 55.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A metal cutting tool comprising an elongated tool body having an elongated tool face portion, a plurality of recesses formed in said tool face, each said recess having a flat bottom face inclined inwardly and rearwardly to the longitudinal axis of the tool body and cylindrical cutter discs mounted in said recesses with an end face of each resting on a recess flat bottom face, each said cutter disc having an edge face with a generally concave cutter portion forming an acute angle with an adjacent end face of the disc, the magnitude of said acute angle and the degree of in-clination of said recess flat bottom face being such to provide a positive rake angle of 1°-25° between said cutter portion and the work cut.
2. A metal cutting tool according to claim l wherein each cutter disc has a diameter of 0.4 to 1.0 inch.
3. A metal cutting tool according to claim 2 wherein each cutter disc has a thickness of 0.15 to 0.4 inch.
4. A metal cutting tool according to claim 3 wherein the positive rake angle is in the range of 5°-20°.
5. A metal cutting tool according to claim 3 wherein said cutter discs are mounted on a circular tool face.
6. A metal cutting tool according to claim 4 wherein said circular tool face is a half-round tool face.
7. A metal cutting tool according to claim 4 wherein the cutter discs are mounted in spaced helical rows with the discs of each row being staggered circumferentially with respect to the recesses of the next adjacent row whereby the paths of successive discs partially overlap.
8. A metal cutting tool according to claim 3 wherein said cutter discs are mounted on a flat tool face.
9. An indexable cutter insert adapted to be mounted in a broaching tool body, said insert comprising a cylindrical member with end faces, a cylindrical edge face and a bore extending axially therethrough, said edge face including an inwardly inclined face portion forming a rake surface adjecent an end face, the junction of said end face and inclined cylindrical face portion defining the cutting edge of the cutter insert, such that when the insert is mounted on a broaching tool body while resting on an end face of said insert, the rake surface is at a positive rake angle of 1-25° relative to the work cut.
10. An indexable cutter insert according to claim 9 wherein the end face adjacent said rake surface is bevelled toward said rake surface.
11. An indexable cutter insert according to claim 9 which is symmetrical, defining cutting edges at both end faces thereof.
12. An indexable cutter insert according to claim 11 wherein the cylindrical edge face is a concave face.
13. An indexable cutter insert according to claim 9 having a diameter of about 0.4 to 1.0 inch and a height of about 0.15 to 0.4 inch.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA302,708A CA1074985A (en) | 1978-05-05 | 1978-05-05 | Machine tool cutter |
| DE19792916809 DE2916809A1 (en) | 1978-05-05 | 1979-04-26 | CHIPPING TOOL FOR METAL WORKING |
| GB7914998A GB2020213B (en) | 1978-05-05 | 1979-04-30 | Machine tool cutter |
| AU46581/79A AU530372B2 (en) | 1978-05-05 | 1979-05-01 | Machine tool cutter |
| IT22307/79A IT1115188B (en) | 1978-05-05 | 1979-05-02 | CUTTING TOOL FOR MACHINE TOOLS |
| JP5515679A JPS54147589A (en) | 1978-05-05 | 1979-05-04 | Cutting tool and cutter inserting matter |
| FR7911254A FR2424787A1 (en) | 1978-05-05 | 1979-05-04 | CUTTING TOOL FOR MACHINE TOOL |
| SE7903910A SE7903910L (en) | 1978-05-05 | 1979-05-04 | REPLACEMENT TOOL |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA302,708A CA1074985A (en) | 1978-05-05 | 1978-05-05 | Machine tool cutter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074985A true CA1074985A (en) | 1980-04-08 |
Family
ID=4111400
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA302,708A Expired CA1074985A (en) | 1978-05-05 | 1978-05-05 | Machine tool cutter |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS54147589A (en) |
| AU (1) | AU530372B2 (en) |
| CA (1) | CA1074985A (en) |
| DE (1) | DE2916809A1 (en) |
| FR (1) | FR2424787A1 (en) |
| GB (1) | GB2020213B (en) |
| IT (1) | IT1115188B (en) |
| SE (1) | SE7903910L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5586843A (en) * | 1992-03-03 | 1996-12-24 | International Minicut, Inc. | Indexable cutting insert for rotary cutting tools |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE427906B (en) * | 1979-06-08 | 1983-05-24 | Westin & Backlund Ab | VIEW TO DESIGN CUTTING AND / OR GRADING PRESSURE TOOL WITH EXCHANGABLE CUTTER EDGE |
| CA1188141A (en) * | 1983-02-14 | 1985-06-04 | Douglas Newton | Machine tool cutter |
| SE456652B (en) * | 1985-05-17 | 1988-10-24 | Sandvik Ab | TOOLS AND SHOULD BE REFERRED TO BE REPLACED |
| US4681485A (en) * | 1986-02-25 | 1987-07-21 | Gte Valeron Corporation | End mill cutting tool and indexable insert therefor |
| JPH0731930Y2 (en) * | 1988-10-18 | 1995-07-26 | 住友電気工業株式会社 | Brooch tool |
| FR2678188B1 (en) * | 1991-06-28 | 1995-11-03 | Safety | SPINDLE FOR A BROACHING MACHINE. |
| DE102004025622B4 (en) * | 2003-07-01 | 2009-09-24 | Sew-Eurodrive Gmbh & Co. Kg | Device for processing and / or producing a depression in a workpiece |
| DE102006025293C5 (en) * | 2006-05-31 | 2010-12-23 | Kennametal Inc. | Method of machining a wheel |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1945535A (en) * | 1932-01-26 | 1934-02-06 | Foote Burt Co | Broaching tool |
| US2392481A (en) * | 1941-12-26 | 1946-01-08 | Detroit Broach Company | Machine tool cutter |
| DE1954719U (en) * | 1964-05-14 | 1967-02-02 | Deutsche Edelstahlwerke Ag | INDEXABLE INSERT. |
| US3262183A (en) * | 1964-09-25 | 1966-07-26 | Cincinnati Milling Machine Co | Broaching tool |
| GB1140841A (en) * | 1965-01-24 | 1969-01-22 | Production Engineering Res Ass | Improved cutting tool |
| JPS4332069Y1 (en) * | 1966-11-29 | 1968-12-26 | ||
| GB1323072A (en) * | 1969-05-30 | 1973-07-11 | Newman F S | Machine tool cutters |
| US3946472A (en) * | 1975-01-22 | 1976-03-30 | J. P. Tool Limited | Broaching tool |
| JPS5335311A (en) * | 1976-09-13 | 1978-04-01 | Nippon Telegr & Teleph Corp <Ntt> | Mark read type facsimile device |
-
1978
- 1978-05-05 CA CA302,708A patent/CA1074985A/en not_active Expired
-
1979
- 1979-04-26 DE DE19792916809 patent/DE2916809A1/en not_active Ceased
- 1979-04-30 GB GB7914998A patent/GB2020213B/en not_active Expired
- 1979-05-01 AU AU46581/79A patent/AU530372B2/en not_active Ceased
- 1979-05-02 IT IT22307/79A patent/IT1115188B/en active
- 1979-05-04 SE SE7903910A patent/SE7903910L/en not_active Application Discontinuation
- 1979-05-04 JP JP5515679A patent/JPS54147589A/en active Pending
- 1979-05-04 FR FR7911254A patent/FR2424787A1/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5586843A (en) * | 1992-03-03 | 1996-12-24 | International Minicut, Inc. | Indexable cutting insert for rotary cutting tools |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2916809A1 (en) | 1979-11-08 |
| IT1115188B (en) | 1986-02-03 |
| SE7903910L (en) | 1979-11-06 |
| FR2424787B1 (en) | 1984-08-24 |
| JPS54147589A (en) | 1979-11-17 |
| GB2020213B (en) | 1982-08-11 |
| IT7922307A0 (en) | 1979-05-02 |
| AU4658179A (en) | 1979-11-08 |
| GB2020213A (en) | 1979-11-14 |
| FR2424787A1 (en) | 1979-11-30 |
| AU530372B2 (en) | 1983-07-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |