JPH0146244B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an annular hole cutting tool.

No. 28,416, issued by the present inventor, discloses an annular cutter having a plurality of spaced apart teeth around its tip (lower end). Each tooth is formed with a plurality of blade portions that alternate in the circumferential direction, and each blade portion is configured to produce separate chips. The radially innermost cutting edge extends radially across a shallow gullet formed in the interproximal web, and the outermost cutting edge extends the gullet upwardly between the interproximal teeth. It extends radially across a spirally extending outer helical groove. According to this, the radial depth of the spiral groove is approximately 1/2 of the thickness of the annular wall of the cutter, and the thickness of the web is approximately 1/2 of the thickness of the annular wall.
Therefore, the radial dimension of the radially inner cutting edge of each tooth is approximately 1/2 the thickness of the annular wall.
Thus, the radial depth of the helical groove is sufficient to discharge chips generated by the double-edged portions.

This prior patent also states that each tooth has three teeth instead of two.
If the three blades are to be staggered in the circumferential direction to produce book chips, the radial depth of the helical groove and the thickness of the web should be kept the same as in the two-stage blade; The wall part of the knife corresponding to the depth of the spiral groove,
This indicates that there are not a single blade, but two blades that are offset in the circumferential direction. The radially outermost cutting portion is defined by an outer gullet of relatively short axial dimension and opening into a helical groove. Nevertheless, the radial dimension of the helical groove is approximately equal to 1/2 of the wall thickness of the blade and can easily accommodate chips produced by the innermost blade. In addition, the web part of the wall still has one cutting edge whose width is approximately 1/2 the wall thickness of the cutting tool, and the chips produced by this cutting edge must be transferred radially into the helical groove. .

The blades disclosed in such prior patents perform a cutting action far superior to that of previous annular blades, but when the blades are used for drilling holes on an industrial scale, the chips may form in the inner opening (inner opening). gullet) tend not to move freely into the spiral groove. In that case, the cutting action is significantly slowed down and results in an oversized hole with a rough finish and a tapered shape. Also,
The life of the blade is also substantially reduced. The inventor is
The most practical way to solve this problem of chip flow from the annular cutter opening and the helical groove is to form the chips thin and narrow so that they can be easily directed into the helical groove as soon as they are cut. We found that it is possible to compose the following.

Typically, the chip begins to curl into a helical shape as soon as it is cut. The volume and stiffness of a helical chip are determined by its width and thickness; the wider it is, the less it will bend easily and the more volume it will have. A large volume of helical chips reduces the amount of chips that can move up the path defined by the helical groove in a given period of time. On the other hand, thin chips easily deflect when they encounter obstacles, such as the walls of a helical groove or a hole, and the depth of the helical groove required to ascend the helical groove is much smaller. Thin chips move more easily into the helical groove and have less tendency to clog the helical groove. Thin chips can also be easily deformed above their elastic limit and therefore easily broken into small pieces. In addition, the thin chips form radially compressible, spring-like helices that intertwine with other helices as they ascend within the helical groove. When these tangled spiral chips engage the wall of the hole being machined,
The resulting friction acts to resist further rotation of the chips integrally with the cutting tool, forcing them upwardly by the rear side wall of the helical groove, without clogging the helical groove. That is, if the chip width is reduced, the cross-sectional area of the spiral groove is reduced. Furthermore, if the thickness of the side wall of the blade is constant, decreasing the size of the helical groove increases the strength of the blade by increasing the thickness of the interproximal web. The thicker the web, the more rigid it is and the more precisely the holes can be formed with a better finish. Furthermore, the increased strength of the cutting tool allows thicker chips to be cut and more teeth to be used, resulting in faster cutting operations.

The main object of the present invention is to provide an annular hole cutting tool that cuts more efficiently, faster, and more accurately than ever before, provides improved finishing, and has a longer life.

Another object of the present invention is to provide a grooved annular cutter that is more resistant to breakage than conventional cutters of the same size.

In particular, the present invention provides at least three cutting edges on each tooth, each of which has a radial dimension of substantially less than one half of the wall thickness of the cutting edge.
The radial dimension of the groove can be reduced to about 1/3 of the wall thickness of the blade, yet deep enough to freely accommodate chips generated by the widest blade part;
The purpose of the present invention is to provide a grooved annular hole cutting tool.

It is also an object of the present invention to provide an annular hole cutting tool that is more efficient than conventional tools of the same size. The purpose of this is to form at least three cutting edges on each tooth of the cutter, with each cutting edge producing a separate chip, two of which are directed radially inward into the groove. This is achieved by configuring the cutting tool to be formed by the side wall portion of the blade, that is, the web portion between adjacent teeth.

The present invention is also very suitable for being formed as two parts that are axially adjacent and nested together, so that the tip of the blade where the teeth are formed can be made of a relatively expensive cutting tool such as high speed steel. It is an object of the present invention to provide an annular hole-edge cutter which can be made of a conventional material, while the cutter main body can be made of an inexpensive material such as heat-treated relatively low-alloy steel.

It is also an object of the present invention to provide an arrangement for the manufacture of annular slotted cutlery of small diameter, in which the tendency for hair cracking to occur during groove grinding or heat treatment is substantially reduced.

Another object of the present invention is to provide a structure for an annular-shaped cutter that can easily reduce the diameter of a standard-sized cutter to produce a special-sized cutter.

A further object of the invention is to provide an annular boring tool which is very suitable for cutting multiple stacked workpieces.

It is an additional object of the invention to provide an annular cutter which is very suitable for making large volume cuts without clogging grooves or openings.

An annular hole cutting tool according to an embodiment of the present invention includes an annular side wall having a plurality of cutting teeth at a lower end thereof spaced apart in the circumferential direction, and the outer peripheral surface of the side wall has a number of cutting teeth corresponding to the number of cutting teeth. A spiral groove is formed.
Each cutting tooth is provided with a plurality of cutting edges staggered circumferentially and preferably also vertically, with at least two of these cutting teeth corresponding to the thickness of the web between adjacent cutting teeth. The other blade portion is located at a cutting tooth portion corresponding to the radial depth of the helical groove. In one embodiment of the blade part according to the invention,
The total width of the two inner blades mentioned above in the radial direction is:
It is desirable that the width be greater than the overall width of the other blades, in which case the thickness of the web will be greater than the depth of the helical groove. In any case, it is desirable that the depth of the spiral groove be set to be at least as large as the width of the wider one of the inner double-edged portions. The wall thickness of the knife is also set to form a relatively narrow cutting path in order to keep the power required to feed the knife into the workpiece reasonably low.

Next, embodiments of the present invention will be described with reference to the drawings.

In the drawings, reference numeral 10 designates a ring-shaped cutting tool according to the present invention, and this cutting tool 10 includes a main body 12 and a shaft portion 14. As shown in FIG. The main body 10 is formed into an inverted top shape and has a side wall 16 and a top wall 18. 20
22 is a spiral groove extending upward around the outer periphery of the main body 12 in proximity to each of the cutting teeth 20; 24 is a spiral groove formed on the outer periphery of the main body 12; A land separating the spiral grooves 22 from each other is shown. Note that these spiral grooves and lands are formed on the side wall 16 of the cutter 10.
Although shown as being formed over the entire length of the side wall 16, in some cases, the action of the cutter 10 may be more effective if it is substantially shorter than the side wall 16. Reference numeral 26 denotes a web forming a portion of the side wall 16 between the cutting teeth 20, and a radially outward surface 28 of each web 26 forms an inner wall of the spiral groove 22. 30 and 32 are the front side wall and rear side wall of each spiral groove 22, respectively.

In the embodiment of FIGS. 1-4, each cutting tooth 20 is provided with three blades 34, 36, 38, the blades 34 being spaced forward from the blade 36 in the direction of rotation; Further, the blade portion 36 is spaced forward from the blade portion 38 in the same direction. 42 is an inward opening (gullet) whose upper end slopes radially outwardly and upwardly as indicated by 44, and at the lower end of the rear face 40 the blade portion 34 is located. Reference numeral 48 denotes a sub-opening formed in the web 26 in the vicinity of the inner opening 42, and the blade portion 36 is located at the lower end of the rear surface 46.
is located. The upper end 50 of this secondary opening 48 is curved radially outwardly and upwardly. Blade part 3
4 and 36 are radially inner surfaces 52 of the sub-opening 48;
are separated by a circumferential shoulder 51 at their lower ends. The other blade part 38 is formed at the lower end of the rear side wall 32 of the spiral groove 22, and the shoulder part 54 is formed at the lower end of the spiral groove 22.
It is spaced backward from the blade part 36 by this.

Reference numerals 56 and 58 denote two counterfeit surfaces or flank surfaces formed on the bottom surface of each cutting tooth 20. When the cutter 10 is in operation, one of the flank surfaces 56 is upward in the axial direction and inward in the radial direction. and the other flank 58 slopes axially upwardly and radially outwardly.
Further, each of these flank surfaces 56, 58 is arranged slightly upwardly from the blade portions 34, 36, 38 in the circumferential direction, for example, from 8 to 8.
It is angled at 10° to define the necessary relief for the blades 34, 36, 38. The flanks 56, 58 intersect at the apex 60, which intersects the radially outermost blade 38. Note that these flank surfaces 56 and 58 are
Although the apex 60 may be ground to intersect any of the blades 34, 36, and 38, it is preferred in most cases to intersect the outermost blade 38 as described above. As a result of inclining both flanks 56, 58, each cut portion 34, 36, 38 is inclined in the axial direction and is also offset in the vertical and circumferential directions.

One of the important features of the knife 10 according to the invention is that at the lower end of each cutting tooth 20, the web 26 is formed with two cutting sections 34, 36. In the cutter of FIGS. 1-9, the radial dimension of the web 26 is desirably greater than the radial depth of the adjacent helical groove 22. Blade part 34,
Since the blades 36 and 38 are alternated in the circumferential direction as shown, when the blade 10 is rotated and fed into the workpiece, each of the blades 34, 36, 38 produces chips separately. Furthermore, the relative dimensions of the cutter 10 are as follows:
The radial depth of the two blades 34, 36 is not substantially smaller than the wider of the two blades 34, 36, and is preferably larger. Therefore, the chips cut by the blade 34 are immediately directed into the opening 48 and into the helical groove 22 by the radial slope of the blade 34 and the upper ends 44, 50 of the openings 42, 48.
Similarly, chips generated by the blade 36 are removed from the blade 36.
6 and the curved wall 50 of the secondary opening 48 directs it immediately into the immediately adjacent helical groove 22 . The axial dimension of the sub-opening 48 is desirably larger than the axial dimension of the inner opening 42, so that chips can be quickly transferred from the blade portion 34 to the sub-opening 48 and into the spiral groove 22.
This prevents chips from clogging the inner opening 42. Due to the inclination of the blade part 34, the chips cut by the blade part 34 tend to be sent upward and outward, that is, at right angles to the radial direction of the blade part 34 and the flank surface 56, but The circumferential dimension is determined to prevent the chips generated by the blade portion 34 from curling directly within the inner opening 42.
It needs to be set sufficiently small. That is, the inner opening 4
2 is formed sufficiently small in the circumferential direction, the blade part 3
The chips cut by 4 are maintained relatively straight, and more easily extend upward and outward from the inner opening 42 into the spiral groove 22.
turned inward. The width of the inner opening 42 in the circumferential direction is preferably no greater than about 1/2 of the thickness of the web 26, and about 1/3 of the thickness of the web 26.
degree is desirable. The circumferential dimension of the inner opening 42 is then varied in an inverse relationship to the thickness of the web 26. With this arrangement, each chip produced by the blades 34, 36 is immediately directed radially outwardly and axially upwardly into the helical groove 22. Blade part 3
Similarly, the chips formed by 8 are sent upward into the spiral groove 22.

These chips are each relatively thin and tend to spiral axially rather than radially, so that they are effectively directed outwardly by the openings 42,48. The aforementioned helical chips from each of the blades 34, 36, 38 tend to intertwine with each other as they move axially upwardly and radially outwardly into the helical groove 22. When such entangled spiral chips come into contact with the wall of the hole being machined, the resulting friction immediately tends to prevent the chips from rotating integrally with the cutter 10. At this time, the rear surface 32 of the helical groove 22, which has received the chips inside, engages the entangled chips and moves them upwardly out of the helical groove 22. These spiral chips are thin;
Spiral grooves 2, especially if they are relatively thin
2 and the walls of the hole being machined. Since the rear surface 32 of each spiral groove 22 is formed in a continuous spiral shape, the upward flow of chips inside the groove is continuous and proceeds smoothly without being disturbed. Thus, shaping and dimensioning the inner opening 42 and the secondary opening 48 so that chips from the blades 34 , 36 are directed substantially immediately into the helical groove 22 also reduces the flow of chips within the helical groove 22 . Since the upward movement is unobstructed, free upward movement of the chips out of the helical groove is ensured. spiral groove 2
If pressurized cooling water is supplied to the inside of the cutter 10, the small chips inside the cutter 2 can more easily flow freely upward. In addition, since the chips are thin and inherently weak, they break easily when they escape from the hole being machined, and therefore do not wrap around the blade 10 or the arbor when they exit the hole, making it difficult for subsequent chips to escape. without interfering with Furthermore, if the inner opening 42 is formed narrow in the circumferential direction, the chips from the blade portion 34 will not have the tendency to curl as described above, and will be fed into the helical groove 22 in a more linear state. As a result, the possibility of chips getting caught in the inner opening 42 or the spiral groove 22 and causing a blockage is reduced.

If it is desired to provide a slight gap between the inner circumferential surface of the side wall 16 and the disc portion of the workpiece to be cut, the inner circumferential surface of the side wall 16 is shortened from the lower end.
For example, it may taper outwardly by about 1 degree, as shown at 62 in FIG. 3, over about 1/2 inch. In that case, this tapered part 6
The inner circumferential surface portion above 2 may be cylindrical. According to this configuration, the inner circumferential surface of the cutter 10 includes the blade portion 34,
Slightly above points 36 and 38, approximately 0.02
You will get an air gap of cm (about 0.008 inch).
The gap between the inner circumferential surface of the side wall 16 of the cutter 10 and the disk portion can also be obtained by making the cylindrical inner circumferential surface slightly eccentric with respect to the outer circumferential surface of the cutter 10. Also shown in FIG. 3, the depth of the helical groove 22 can be increased, if desired, by grinding the inner surface 28 so that it tapers inwardly up to the portion 62 at a slightly greater rate than the portions above it. , it can also be gradually deepened upward. In that case, the blade part 3
8 defines a radial gap for the freshly cut chip. In short, the spiral groove 22 as a whole can be formed so that its cross-sectional area gradually increases upward, thereby making it easier to remove chips. Further, each spiral groove 22 may be tapered so that the width in the circumferential direction is wider at the upper end than at the lower end.

By making the web portion thick and strong while keeping all the chips extremely thin, the inner opening 4 in the axial direction
The depth of 2 can be made even deeper. Deepening the inner openings 42 not only allows for an increased amount of cooling water to flow through the cutting teeth 20, but also keeps the cutting teeth 20 sharp for a longer period of time before the inner openings 42 need to be ground again. be done.

Generally, to reduce the power required to feed an annular hole cutting tool into a workpiece such as steel, the cutting path or groove formed by the tool must be relatively narrow.
For knives constructed for the purpose of forming small or medium diameter holes, e.g. up to 2.54 cm (1 inch) in steel, practical wall thicknesses are approximately
0.160 to 0.180 inch). As shown in FIGS. 1 to 4, each cutting tooth 20 has three blade portions 34,
36 and 38, and the thickness of the side wall 16 is approximately 0.46 cm.
(approximately 0.180 inch), when a thick web 26 is desired, the radial depth of the helical groove 22 is approximately
Approximately 0.20cm (approximately 0.080 inch), therefore web 2
6 can be approximately 0.25 cm (approximately 0.100 inch) thick. Also, the width of the two inner blades 34, 36 can be approximately 0.13 cm (approximately 0.050 inch), or if desired, the width of the innermost blade 34 can be approximately 0.11 cm (approximately 0.11 cm).
0.045 inch), the width of the middle blade part 36 is approximately 0.14 cm
(approximately 0.055 inch). In this way, web 2
By forming the blade 6 relatively thick and the side wall 16 relatively thin, chips from the three blade portions 34, 36, and 38 can easily enter the spiral groove 22. Preferably, the circumferential dimension of each spiral groove 22 is several times the radial depth. However, if it is not necessary to make the web 26 thicker, the dimensions of the blade are set so that the thickness of the web 26 is approximately 0.03 cm (approximately 0.010 inch) thinner than the wall thickness of the blade. That is, if the thickness of the blade side wall 16 is approximately 0.46 cm (approximately 0.180 inch), the thickness of the web 26 is approximately 0.20 cm (approximately 0.080 inch).
inch), and set the depth of the spiral groove 22 to approximately 0.25 cm (approximately 0.100 cm).
inches). In that case, the width of each blade part 34, 36 is approximately 0.10 cm (approximately 0.040 inch)
Can be set to . In any case, the depth of the spiral groove 22 is greater than the width of the double-edged portions 34, 36. If available power is limited, larger diameter knives may be formed with thinner sidewalls to reduce the horsepower required to rotate the knife. When the sidewalls are made relatively thin in this manner, the web 26 is preferably formed into a spiral groove 22.
It is thicker than the depth of the blade and gives strength to the knife.

The annular hole cutting tool shown in Figs. 5 to 8 is
It differs from the cutter of FIGS. 1 to 4 in essentially only one respect. That is, in FIGS. 5 to 8,
In the portion of each cutting tooth 20 corresponding to the depth of the spiral groove 22, two blade portions 70, 72 are provided instead of one blade portion as shown by reference numeral 38 in FIGS. 1 to 4. is forming. In this case, the width of each blade portion 70, 72 can be made approximately 1/2 of the depth of the opening. Each cutting tooth 2
The 0 flanks 56, 58 are sloped as described with respect to FIGS. 1-4, and preferably intersect at the apex 74, which intersects the outermost blade 72 at approximately the center.

In the cutlery shown in FIGS. 5 to 8, the blade part 7
2 are slightly alternated with the blade portions 70 in the circumferential direction, and these blade portions 70, 72 are configured to cut out one chip having a line of weakness at the center. As a practical matter, in a knife for drilling holes in steel, it is necessary to suppress the misalignment of the blade 72 to about 1/4 of the misalignment of the other blades, preferably about 0.02 cm (0.15 inch) or more. must not. A single deformed chip thus produced by the blades 70, 72 tends to break immediately upon encountering an obstacle. However, since this single fragile chip is immediately sent into the large spiral groove 22,
The tendency for thin chips to become stuck in the portion of the helical groove 22 between the shoulder 82 (FIG. 8) and the sidewall 76 of the hole being machined is avoided.

If the blade part 72 is shifted backward from the blade part 70 so that each of these blade parts 72, 70 cuts out separate chips, the part of the helical groove 22 where the blade part 72 is provided can be moved upward and downward. The dimension in the direction is substantially the opening 4
It is preferably formed as an aperture 84 (FIG. 9) equal to 4.50 mm. In this way, when the blade 72 is displaced by an amount sufficient to cut out separate chips, the chips thus cut out are immediately sent into the spiral groove 22 by the opening 84, thereby preventing the opening 84 from becoming clogged. do not have.

When the cutter shown in FIG. 9 is rotated and fed into a workpiece, four independent chips are produced by the blades 34, 36 and 70, 72. On the other hand, according to the cutter shown in FIGS. 5 to 8, the blade parts 34 and 36 cut out separate chips, and at the same time, the blade parts 70 and 72 cut out a single easily breakable chip as described above. arise. In either case, the chips produced by the blade 34 are directed outwardly substantially immediately into the helical groove 22, and the chips produced by the blade 36 are likewise substantially immediately directed upwardly and outwardly into the helical groove 22. Sent. Blade part 70,
The same applies to one or each chip generated by 72.
It is fed upward into the spiral groove 22.

However, substantially immediately after the chips cut by the blades 34, 46, 70 are directed into the helical groove 22, they come into frictional contact with the sidewalls 76 of the hole being machined. Since unbroken chips usually have a somewhat spiral shape, the frictional resistance generated as a result of their contact with the side wall 76 tends to prevent the spiral chips from rotating together with the cutting tool. . the result,
These chips substantially immediately engage the rear side wall portion 78 (FIG. 6) of the helical groove 22 and are forced upwardly out of the helical groove 22 without any interference in the manner previously described. In this way, in the case of the cutter shown in FIGS. 5 to 8, since the circumferential dimension of the shoulder portion 82 is set small, the chips engage with the rear side wall portion 80 of the spiral groove 22 and are captured. Never. This is desirable because it substantially reduces the tendency for chips to become trapped between the outer circumferential surface of the tool and the sidewalls of the hole being machined, especially when the chips are thin and easily deformed. In addition, since the chips are thin,
Even when flowing upward through the spiral groove 22, there is little possibility of damaging the side wall of the hole. Also, these fine chips break easily once they escape the hole, so the cutter does not wrap around the arbor and do not interfere with the free flow of subsequent chips.

In the configurations shown in FIGS. 5 to 8 and 9, two blades are formed instead of one in the portion of the cutting tooth 20 that corresponds to the depth of the spiral groove 22, making it easier to use than a standard-sized blade. Even if a cutter with a smaller outer diameter, for example about 0.020 inch, is desired, there is another advantage in that the outer circumferential surface of the standard size finished cutter only needs to be ground by about 0.010 inch. Even in this case, the depth of the spiral groove 22 is approximately 0.03 cm.
(approximately 0.010 inch) and is still large enough to accommodate the width of the chips created by the other three blades. Note that if the radial depth of the spiral groove 22 to be formed is substantially the same as the width of the widest chip, the outer diameter of the cutter shown in FIGS. 1 to 4 can be ground. , special sized blades may be formed.

A further advantage of providing at least two blades in the web portion and in the portion of the cutting tooth 20 corresponding to the depth of the helical groove 22 is that when cutting metal chips,
This lies in the fact that it has a tendency to expand by as much as 10%. In other words, in the cutters shown in FIGS. 5 to 8 and 9, the depth of the spiral groove 22 is set to be 10% or more larger than the width of the maximum blade portion, so that the spiral groove 22 is formed by the expanding chips. The tendency for binding or clogging may be further reduced. Note that the blade portions 70 and 72 of the cutlery shown in FIGS. 5 to 8 cut out a single chip, but this chip has a brittle magnetic wire running through its center and is easily broken into narrow pieces.

Another advantage of having two blades in the web portion of the knife is that thicker walls and wider helical grooves can be formed if desired. Conventionally,
The width of the web blade is approximately 0.25cm (approximately 0.100 inch)
In this case, it was difficult to move wide chips radially outward into the spiral groove. However, according to the invention, the two thin chips formed by the cutting edge of the web section can be moved very easily radially and axially into the outer helical groove and have a width of about 0.51 mm.
Cut paths larger than cm (0.200 inch) can be easily obtained on an industrial scale.

The cutters shown in FIGS. 10-15 are similar to, but slightly different from, those shown in FIGS. 1-4. In the cutter of FIGS. 1-4, the flank face 56 slopes radially inwardly and axially upwardly at an angle of approximately 20° to 25°, so that the blade portions 34, 36 also slope. It is also sloping. Below, this is
Referred to as "positive internal tilt angle". This degree of inclination angle means that the chip load on the cutting tool is approximately 0.005~
A rotation of less than 0.008 cm (0.002 to 0.003 inch) per revolution is suitable for forming holes. The resulting thin chips are very flexible and twistable. As previously mentioned, the cut chips are moved upwardly in a path perpendicular to the plane of the flank and perpendicular to the radial orientation of the blade. Thus, when the positive internal inclination angle is relatively large, chips are directed radially outwardly by the blades 34, 36 to engage the sidewalls of the hole being machined. If these chips are thin, they are easily twisted, so it is not very difficult to eject them upward through the spiral groove 22 of the cutter as described above.

On the other hand, if the chips are relatively thick, they will not bend easily when engaged with the sidewalls of the hole being machined and may clog the helical groove 22 when forming multiple holes on an industrial scale. There is also. For this reason, increasing the angle of inclination of the blade sections 34, 36 as shown in FIGS.
Relatively high feed rates, such as 0.012 cm (0.006 inch), are not preferred when the cutter is used to form large numbers of holes on an industrial scale. If the cutter is used under conditions where the chip load becomes large,
The radial inclination of the two inner cutting edges 34, 36 must be substantially less than 25°, so that chips are directed more upwardly in the vertical direction and less outwardly in the left-right direction. . For high chip loads, the radial inclination of the inner cutting edges 34, 36 preferably ranges from +10 DEG to -3 DEG.

In the cutter shown in FIG. 10, the angle of inclination a of the blade portions 34, 36 is approximately +10°, and in the cutter shown in FIGS. 14 and 15, the angle of inclination b of the blade portions 34, 36 is approximately −3°. According to this degree of inclination angle, the blade portion 34,
The chips cut out by 36 are compared to the case with an inclination angle of 25°.
This results in a tendency to travel in more vertical paths. Even when the inclination angle is relatively small, it is desirable to provide the blade portions 34, 36 with a positive radial rake angle r relative to the inner peripheral surface of the blade, as shown in FIG. 13, for example. When the radial rake angle of these blades 34, 36 is slightly positive, for example up to 10 DEG, each chip cut is radially directed slightly outward and upward. Even if the inclination angle is about -3° (Fig. 14),
A small positive radial rake angle (10°) directs the chips slightly radially outward and vertically upward, passing directly adjacent to the sloped top surfaces 44, 50 of the openings 42, 48, or contact at a very small angle, thus causing the helical groove 22 to deflect upwardly with little twisting. If the inclination angle is made smaller, the opening 42,
Any twisting or bending required by the top of 51 or the side walls of the hole being formed can be minimized. This reduces the tendency for chips to clog the helical groove 22, even if the chips are relatively thick, when the angle of inclination is in the range of +10° to -3°.

Setting the angle of inclination of the inner blades 34, 36 to be small also provides other advantages, such as: That is,
It will be appreciated that as the angle of inclination approaches zero, the blade becomes shorter and the width of the chips cut becomes narrower.
This narrower chip is easier to eject upwardly in the helical groove 22 than a wider chip, and is therefore less prone to jamming. If the chips flow freely and smoothly in the spiral groove 22, less horsepower is required to rotate the cutter than if the chips tend to clog the spiral groove 22. If the torque of the cutter is small, the side wall of the cutter can be made thinner, and the stress is reduced, so the life of the tool is extended.

Furthermore, by making the internal inclination angle relatively small,
The advantage also arises that the cutter can also form holes in stacked materials. For example, FIG. 15 shows a cutting tool in the state of making a hole in two plates P ₁ and P ₂ stacked one above the other. In this case, the leading edge of the tool is the cutting edge 34
Since the blade part 3 is formed at the inner end in the radial direction of
As soon as the inner end of the blade 4 penetrates the upper plate P ₁ , the disc part S in the knife is cut off from the plate P ₁ , and the blade part 34 can then easily enter the lower plate P ₂ . This knife can easily cut stacked materials even when the internal inclination angle increases up to 10°. This is the top 6
0 (Fig. 10) passes through the upper plate P ₁ ,
The flange portion extending outward and upward in the radial direction of the disk portion S is very thin, and even if the disk portion S is completely cut off, the moderate downward pressure acting on the blade will cause the blade to It easily enters the lower plate P ₂ and the plate P ₁
This is because it is sufficient to bend and cut the thin flange portion around the disk S cut from the disk.
Experiments have shown that an internal slope angle of about +3° gives good results both for high chip loads and for cutting stacked materials.

As mentioned above with respect to FIGS. 1 to 4, the top 6
0 forms the intersection of the two flanks 56, 58, preferably intersecting the blade 38. This blade part 38
desirably forms a positive radial rake angle (10° or less) with respect to the outer peripheral surface of the cutter. In each of the embodiments shown in FIGS. 10 to 15, the outer cutting portion 38 is provided near its outer end with a large external slope of, for example, 40° to 45° with respect to the horizontal plane, upwardly and radially outwardly. Another sloped relief surface 86 is provided. The above external inclination angle is shown in FIG.
The external inclination angle between 20° and 25° is designated by d. According to experience, the angle of inclination of the outermost part of the outer blade part 38 is, for example,
It has been confirmed that a relatively large angle, such as 40° to 45°, provides several advantages, including: That is, if this angle of inclination is set large, it not only helps to direct the chips cut by the blade 38 inward from the side wall of the hole being formed, but also helps to direct the chips cut out by the blade 38 inward from the side wall of the hole being formed, and also to reduce the internal angle e of the outer end of the blade 38, that is, the side wall 16 of the blade 38. The relatively large angle between the bottom flank and the bottom flank results in reduced tooth wear and longer tool life.

As shown in FIG.
It contacts the blade portion 38 at approximately the midpoint of the depth. The line of intersection 88 between the flanks 58, 86 is preferably located approximately one quarter of the depth of the helical groove 22 inwardly of the outer peripheral surface of the cutter. Also, as shown in FIG. 13, the blade portion 3
8 is continuous with the shoulder 54 at a relatively large radius 90. This rounded shoulder 90 is a part of the blade 36.
It is desirable to extend forward by at least approximately 0.10 cm (approximately 0.040 inch). These blade parts 36, 38
Although the shoulder 90 between them is curved to this extent, they produce two separate chips as long as the spacing between the blades 36, 38 is greater than the feed rate of the blade in the vertical direction. The inventor has discovered that the blade portions 36, 38
As long as you keep the spacing at about 0.03 cm (about 0.010 inch),
It was discovered that two chips were cut out. on the other hand,
The vertical spacing between the blades 36, 38 is determined by the length of the shoulder between them and the angle of inclination of each flank. As already mentioned, chips tend to expand as they are cut out. In addition, relatively thick chips have a larger expansion amount than thin chips. The shoulder portion 90
easily curls and expands thick chips without creating a binding effect between the hole being formed and the shoulder 54. Therefore, the curled chips generated by the blade portion 38 freely ascend the spiral groove 22.

According to the annular hole cutting cutter of the present invention, advantages such as easy removal of chips can be obtained without sacrificing the strength of the cutter. This means that each cutting tooth has at least 3
This is because the depth of the helical groove can be set to be substantially smaller than the width or thickness of the web between adjacent cutting teeth while providing four or more cutting edges. The strength of an annular cutter with grooved sidewalls is determined primarily by the thickness of the web. Therefore, if it is necessary to make the web of a particular cutter a predetermined minimum thickness, according to the present invention, the depth of the spiral groove can be made equal to or less than the thickness of the web, and the blade portion nevertheless cuts. The total wall thickness of the knife of the present invention can be smaller than that of conventional knives because it can be deep enough to accommodate the widest chips to be ejected. It is desirable to form the side wall thinly in terms of cost reduction and narrow cutting path. However, thicker webs are also acceptable. As mentioned above, since the web is formed with two cutting edges, the chips are more easily and smoothly directed into the helical groove. Therefore, the stress in the web is substantially lower with two blades than with one, and the strength properties of the blade are therefore improved even if the web thickness is less than the depth of the helical groove. do.

Another advantage of the ring-shaped cutter according to the present invention is the third one.
It becomes clear from the figure. That is, as previously discussed, the thickness of the web 26 can be substantially greater than the depth of the helical groove 22 in the vicinity of each cutting tooth 20, if desired. This forms at least two blade portions in the portion of the cutting tooth 20 corresponding to the web thickness,
The width of each of these blade portions is desirably substantially the same as the spiral groove 2.
This is based on the fact that the depth is set smaller than 2. Therefore, the inner wall 28 of the spiral groove 22 has a lower end proximate to the third point.
By tapering radially inwardly and upwardly and relatively steeply to the point indicated at 62 in the figure, the chips produced by the blade 38 define a gap in the immediate vicinity of the helical groove 22. Similarly, if the inner circumferential surface near the lower end of the cutter is tapered outward and upward in the radial direction, the thickness of the web 26 is at its minimum near the upper end of the side wall 16 of the cutter at a location indicated by 86 in FIG. Become.
Then, this portion 86 becomes a problem regarding the strength of the cutter. Therefore, in a conventional cutter in which the depth of the spiral groove near the cutting teeth of the cutter is increased to the same extent as the thickness of the web, it is difficult to form a spiral groove that gradually deepens upward and at the same time define a void around the inner peripheral surface. The total wall thickness of the cutter then needs to be substantially greater. On the other hand, with the knife of the present invention, a substantially larger void can be obtained around the inner peripheral surface of the knife without requiring a substantial increase in the total wall thickness. This larger air gap is also desirable for its ability to increase the flow of cooling water to the cutting blade.

Forming the web relatively thick and the spiral groove relatively shallow is extremely important in the production of annular cutters. In other words, assuming a constant wall thickness, if you try to grind a relatively deep spiral groove on the side wall, there is a very high possibility that fine hair cracks will occur in the web.
This will shorten the life of the knife. Deep spiral grooves are also prone to cracking during heat treatment. However, by making the helical groove relatively shallow and the web relatively thick, the web portion absorbs a substantially greater amount of heat, thereby substantially reducing the tendency for hair cracking to occur during heat treatment or grinding of the groove. . Forming the spiral groove shallowly is desirable from the viewpoint of manufacturing costs, and it can be processed or ground in a short time, and the life of the cutter will be extended depending on the shallowness.

Although not shown, most annular cutters require a central pilot pin or drill.
In practice, the cavity 88 in the shaft 14 that holds the pilot pin or pilot drill must be at least a certain size. Therefore, the inner diameter of the cutter must be at least equal to the diameter of the pilot pin or pilot drill. In the cutter of the present invention, the web can be formed to be thicker than the depth of the spiral groove, so if the pilot hole is of a constant size, the outer diameter of the cutter of the present invention can be smaller than the actual minimum outer diameter of conventional cutters.

Furthermore, since the cutter of the present invention has a thicker web part than conventional ones, the two parts, that is, the tooth part and the main body, are nested in the axial direction in the web part and are connected to each other by screwing, welding, etc. Another advantage is that it can be configured in parts. Such a nested connection can be achieved without any substantial effect on the strength of the cutter due to the thickness of the web. A two-part knife of this type has clear cost advantages, since only the teeth need to be made of expensive steel, and only the teeth need to be replaced when the teeth wear out.

A thicker web portion increases the torque and thrust it can withstand, allowing for a greater number of cutting teeth around the blade. Increasing the number of cutting teeth increases the number of cutting edges and speeds up the cutting action.

Regarding the type of cutter shown in FIGS. 5 to 8 and 9 in which each cutting tooth has four blades,
Unless special considerations are taken, it is desirable that the two inner blades have approximately the same width and the two outer blades have approximately the same width. However, this is not the case when special considerations are taken. For example, if it is desired to create a very smooth surface on the central disk portion, the innermost blade 34 should be substantially narrower than the next blade 36. In any case, these blade parts 34,
Even the widest one of the grooves 36 must not be wider than the depth of the spiral groove 22. Also, if it is desired to drill a very smooth hole in a workpiece, the outermost cutting edge 72 must be significantly narrower than the next cutting edge 70. Additionally, if it is desired to simultaneously form a smooth wall hole and a smooth side disc, the innermost blade 34 and outermost blade 72 should be narrower than the intermediate blades 36,70. In any case, if the knife is configured to drill holes in steel and has at least four blades, the width of the widest blade should be approximately 0.16 cm (approx.
0.0625 inch) or less will usually give the best results. However, if greater strength is required, the width of the blade portion may be increased to 2 to 3 times.

Similarly, the apex between the gap surfaces 56 and 58 is preferably formed to intersect with the outermost edge, but depending on the purpose, a flank may be formed to intersect with one of the other edges. May be ground. That is, for example, when a cutting tool is used for the purpose of forming a hole in two or more stacked workpieces, and the positive radial angle of inclination of the innermost cutting section 34 is 25 degrees, etc., the comparison is made. When the target is made larger, the top between the flanks 56 and 58 becomes the side wall 1 of the cutter.
6. It is configured so that it is located in the immediate vicinity of the inner circumferential surface of No. 6. If this apex, that is, the high point of the cutter, is located close to the inner peripheral surface of the cutter side wall 16, there will be little difficulty in feeding the cutter into the stacked workpieces. However, the first
As shown in FIGS. 0 to 15, when the innermost blade 34 has a small or negative angle of inclination, the flanks 56, 58 can intersect along the outermost blade 72. In that case, the knife can still be used to make holes in the stacked materials.

Note that since chips tend to expand slightly immediately after being cut, the depth of the spiral groove in the radial direction is
Preferably, surface 28 is ground to a maximum at the two connection points. By doing so, the frictional resistance between the chips cut out by the blade portion 38 and the inner wall of the spiral groove is suppressed to a minimum.

The high point of the knife can be moved to the inner blade 34 without changing the position of the top 74. In other words, since the flank 56 is inclined upward in the circumferential direction, if the shoulders 51 and 54 are made sufficiently long, the top 74 will be spaced above the blade 34 instead of below.
In that case, the cutting action is initiated by the blade 34 and the blade 34 enters the topmost workpiece before the apex 74. Therefore, if the width of the blade 34 is made very narrow, the small lip remaining on the disc being cut out will not prevent the disc from rising into the blade, and the blade will be free to move downwards. Can enter into the workpiece.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an annular hole cutting tool according to an embodiment of the present invention, Fig. 2 is an enlarged view of the main part of the part indicated by circle 2 in Fig. 1, and Fig. 3 is taken along the line 3-3 in Fig. 1. FIG. 4 is a cross-sectional view of a main part showing one cutting tooth of the same embodiment in a slightly perspective view, FIG. 5 is a perspective view showing another embodiment of the present invention, and FIG. Fig. 5 is an enlarged view of the main part of the part indicated by circle 6, Fig. 7 is a cross-sectional view showing one cutting tooth of the same embodiment in a slightly perspective view, and Fig. 8 is a machining of the cutter of the same embodiment. FIG. 9 is an enlarged bottom view of the main part shown in relation to objects, FIG. 9 is a perspective view of the main part showing still another embodiment of the present invention which is slightly modified from the embodiment shown in FIGS. FIG. 11 is a perspective view of the essential parts of a cutlery according to another embodiment of the present invention, FIG. 12 is an explanatory diagram of the essential parts of the same cutter, and FIG. 13 is an end view of the essential parts of the same cutter. FIG. 14 is a vertical sectional view of the main part of a cutter according to still another embodiment of the present invention,
FIG. 15 is a vertical sectional view of a main part showing a mode in which the cutter shown in FIG. 14 is used for drilling holes in stacked workpieces. 10...Knife, 12...Main body, 14...Shaft part,
16... Side wall, 20... Cutting tooth, 22... Spiral groove, 24... Land, 26... Web, 34,3
6, 38...blade portion, 42...inner opening, 48...
Sub-opening, 70, 72...blade portion, 86...flank surface,
88...Cross line, 90...Shoulder.

Claims (1)

Claims: 1. A generally cylindrical annular sidewall having a plurality of cutting teeth spaced circumferentially around its lower end and having means for attaching the cutter to a rotational drive member;
Further, the annular side wall has a plurality of grooves extending upward from the lower end around the outer peripheral surface thereof, and the adjacent cutting teeth are connected to each other by a circumferential web on the inner peripheral surface side of the annular side wall. are radially opposed to the grooves, and each groove has a front side wall and a rear side wall that are circumferentially spaced apart and extend substantially radially;
an inner wall extending circumferentially and defining a radially outer side of said web, each cutting tooth having a radially inner cutting edge, a radially intermediate cutting edge and at least one cutting tooth;
forming at least three radial cutting edges consisting of three outer cutting edges, the inner cutting edge and the middle cutting edge of each cutting tooth being attached to the web relative to each other, respectively, so that the cutting tool rotates; and arranged to cut a separate chip when fed into the workpiece, the inner and intermediate cutting edges cutting a total width of the chip at least equal to the thickness of the web. , each of the inner and intermediate blades having a radial dimension less than the thickness of the web, and having a radial dimension in the web extending upwardly from the inner and intermediate blades on the cutting teeth and at the upper end. forming a radially outwardly open opening means in said groove adjacent to said groove, said outer cutting edge defining, at least in part, a lower end of said circumferential rear side wall of said adjacent groove; , the radial dimension of each groove is not less than the radial dimension of the inner cutting edge and the intermediate cutting edge, and the circumferential dimension is substantially larger than the radial dimension of the cutter. is rotated and fed into the workpiece in the axial direction, the chips formed by the inner cutting edge and the intermediate cutting edge of the web portion of the annular side wall respectively pass through their corresponding openings and radially approach each other. An annular hole cutting tool characterized by being fed upward into the groove. 2. The annular hole cutting tool according to claim 1, wherein each cutting tooth is provided with three blade portions. 3 The blade portion of each cutting tooth is arranged so that the outer end in the radial direction of the inner blade portion is located forward of the inner end in the radial direction of the intermediate blade portion with respect to the rotational direction of the cutter, and the outer end in the radial direction of the intermediate blade portion 3. The annular hole-edge cutter according to claim 2, wherein the outer cutter is shifted in the circumferential direction so that it is located forward of the inner end in the radial direction of the outer cutter. 4. The annular hole cutting tool according to claim 2, wherein the thickness of the web is set to be larger than the radial depth of the groove. 5. Each of the inner and intermediate cutting portions is angled radially outwardly and axially upwardly by an angle not greater than about 10° with respect to the horizontal plane. The annular hole-marking knife according to item 1. 6. Claim 1, characterized in that each inner and intermediate cutting section is radially outwardly and axially inclined at an angle of +10° to -3° with respect to the horizontal plane. An annular hole cutter described in section. 7. The annular hole-edge cutter according to claim 6, wherein each inner cutter portion is provided with a positive rake angle with respect to the inner circumferential surface of the side wall of the cutter. 8. An annular hole-edge cutter according to claim 6, wherein each outer cutter portion is provided with a positive radial rake angle with respect to the outer peripheral surface of the side wall of the cutter. 9 Each cutting tooth is provided with a pair of flanks which are radially inclined in opposite directions relative to each other and which are axially upwardly inclined and circumferentially backwardly from each cutting edge; formed radially coextensive with at least the inner cutting edge and the intermediate cutting edge, and at the same time inclined radially outwardly and axially upwardly by an angle not greater than 10° with respect to the horizontal plane. An annular hole-edge cutter according to claim 2, characterized in that: 10 forming on each cutting tooth a pair of flanks that are radially inclined in opposite directions relative to each other, and axially upwardly and circumferentially backwardly from each cutting edge;
One of these flanks is formed to be coextensive in the radial direction with at least the inner cutting edge and the intermediate cutting edge, and at the same time axially and radially outward at an angle of +10° to -3° with respect to the horizontal plane. The annular hole-edge cutting tool according to claim 2, characterized in that the cutting tool is inclined in a direction. 11. Claims characterized in that the other flank extends rearwardly from the outer cutting edge and is inclined radially outwardly and axially upwardly by an angle not greater than 25°. The annular hole-edge cutter according to item 10. 12. An annular bore according to claim 11, characterized in that the other flank is sloped radially outwardly and axially upwardly by an angle of about 20° to 25°. Ake cutlery. 13 Each cutting tooth is provided with a third flank extending rearwardly from the outer cutting edge and radially inwardly from the outer peripheral surface of the blade side wall, the flank being set at an angle of approximately 40° to 45° with respect to the horizontal plane. 13. An annular hole cutting tool according to claim 12, characterized in that it is inclined radially outwardly and axially upwardly by an angle of .degree. 14 The radial dimension of the third flank is approximately 1/4 of the radial depth of the adjacent groove at the outer cutting edge.
14. The annular hole-edge cutter according to claim 13, wherein the cutter is set as follows. 15 Each intermediate blade portion is connected to an adjacent outer blade portion by a circumferential shoulder, and at least a portion of this shoulder portion is constituted by a curved surface terminating near the outer end of the intermediate blade portion. An annular hole-edge cutter according to claim 2, characterized in that: 16 The length of the shoulder in the circumferential direction is larger than the radial dimension of the intermediate blade, and the curved surface is approximately in contact with the portion of the shoulder located immediately after the outer end of the intermediate blade in the radial direction. 16. The annular hole cutting tool according to claim 15, characterized in that the cutting tool is defined by a radius. 17. The annular hole-edge cutter according to claim 16, wherein the other end of the curved surface is substantially in contact with the outer cutting edge. 18 Each cutting tooth has four radial cutting edges;
3. An annular hole cutting tool according to claim 2, wherein the two outermost cutting edges define the lower ends of the rear sidewalls of adjacent grooves. 19. An annular hole cutting tool according to claim 18, characterized in that the thickness of each web is at least slightly larger than the radial depth of each groove.