JPH0253164B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a cylindrical side wall having a plurality of cutting teeth circumferentially spaced around a lower end, and The present invention relates to an annular drilling knife including a knife body with a plurality of grooves extending upwardly around the circumference of the knife body.

[Conventional technology]

Such an annular drilling knife with an inner and outer back-off surface (the lower surface of the knife to create a gap between the surface to be cut and the knife) and a top between them is
No. 51-27511. However, with such an annular drilling tool, a wide cutting piece is cut, and if this cutting piece is larger than the depth of the groove, it will be caught between the cutting tool and the inner wall of the hole to be formed, making it difficult to pull it out along the groove. It's not easy.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION The object of the invention is to provide an annular drilling tool of the type mentioned at the outset, which is easy to cut, since the cutting pieces are thin and do not clog the grooves.

[Means for solving problems]

The cutter body 12 includes a cylindrical side wall 16, and a plurality of cutting teeth 18 spaced apart in the circumferential direction at the lower end thereof.
20, the cutting teeth being separated from the lower end by a plurality of grooves 22 extending upwardly around the outer periphery of the side wall and a gullet 42 inside the grooves 22 at the lower end of the side wall 16; Each of the cutting teeth has a cutting edge against the rear side of the groove and gullet and also has radially inner and outer back-off surfaces 56, 58 on the bottom surface of the cutting tooth. the inner and outer back-off surfaces intersect to form at least one circumferential apex 60, the apex having an annular drilling across said cutting edge with its front end touching the rear side of the groove 22; In cutlery,
The top 60 of one adjacent tooth 18 is the other tooth 20
The width of the cutting piece cut by all of the plurality of cutting edges and gullets 42, which are arranged radially offset from the top 60 of the groove 22 and are formed in contact with the rear side surface of the groove 22, is the width of the cutting piece cut by the groove 22. 22 radial depth.

[Action and effect]

A groove is cut into the cylindrical side wall 16 of the cutter body 12 to form a land 24, and a gullet 4 is formed adjacent to the land 24.
2, a plurality of cutting teeth 18, 20 spaced apart in the circumferential direction are formed at different levels on the lower ends thereof, and the back-off surfaces 56, 58 are formed into two surfaces inclined outwardly and inwardly in the radial direction. Then, the intersection portion becomes the top portion 60 in the circumferential direction.

By shifting this apex 60 in the radial direction with respect to the adjacent tooth, the cutting edge is divided, and since the actual cutting portion of the two adjacent teeth is different in the radial direction, the grooves described above guide the cutting edge.・The width of the cutting pieces to be ejected becomes smaller, the cutting edge reliably grips the workpiece to ensure reliable cutting, and the amount of workpiece cut by each tooth at one time is reduced. , the amount of cutting chips guided at one time through one groove is also reduced.

In this way, an extremely effective annular drilling knife,
It can be obtained with a relatively simple structure and therefore easy processing.

〔Example〕

Other features and advantages of the invention will be described in detail below with reference to the accompanying drawings, which illustrate preferred embodiments of the invention.

An annular drilling knife according to the invention is for drilling holes in metal and is generally designated by the reference numeral 10 in FIG. The cutter includes a main body 12 and a shank 14. The cutter body 12 has an inverted cup shape and the length of its side wall 16 exceeds the thickness of the workpiece into which the hole is to be cut. A plurality of cutting teeth spaced apart in the circumferential direction are formed on the lower end peripheral edge of the side wall 16. In the illustrated embodiment, the cutting teeth are divided into two groups, a first group of 18 and a second group of 20. The cutting teeth 18, 20 have one tooth 2 at the circumference.
0 is placed between every other tooth 18 adjacent to each other. A helical groove 22 extends upwardly around the outer periphery of the cutter adjacent each tooth. The continuous groove 22 forms a land 24 on the outer periphery of the cutter.
separated by At the leading edge of each land 24,
A narrow edge 25 is formed. The portion of the annular side wall 16 of the cutter located between successive teeth 18, 20 includes a web 26. The radially outer surface 28 of each web 26 defines the radially inner wall of each groove 22. The depth of the grooves 22 may be approximately equal to, slightly greater or less than, the thickness of the web 26. Each groove includes a circumferential front sidewall 30 and a rearward sidewall 32.

In the illustrated knife, each tooth 18, 20 is formed with three cutting edges 34, 36, 38. Cutting edge 38
As will be described later, there are two locations 38a and 38b. The cutting edge 34 is spaced forward in the direction of rotation from a cutting edge 36, which in turn is spaced forward from a cutting edge 38. The cutting edge 34 is formed on the rear surface 4 of the inner gullet 42 formed in the web 26.
Located at the lower end of 0. The upper end of the galette 42 is 4
4, slopes upwardly and outwardly radially. The cutting edge 36 similarly cuts the rear surface 46 of a second gullet 48 formed in the web 26 directly adjacent the gullet 42.
located at the lower end of The upper end of the second gullet 48 is
It curves radially outward and upwardly at 50 above the first gullet 42. The cutting edges 34, 36 are separated by a circumferentially extending shoulder 51 at the lower end of the radially inner surface 52 of the second gullet 48. A cutting edge 38 is located at the lower end of the rearward sidewall 32 of the groove 22 and is spaced rearwardly from the cutting edge 36 by a shoulder 54 at the lower end of the groove 22 .

There are two back-off surfaces 56, 5 on the bottom of each tooth.
form 8. When the knife is in operation (first
(FIG.) The radially inner back-off surface 56 slopes axially upwardly and radially inwardly, and the radially outer back-off surface 58 slopes axially upwardly and radially outwardly. Furthermore, each of the back-off surfaces is
It is inclined upwardly in the circumferential direction from each cutting edge at a slight angle, for example 8 to 10 degrees, to provide the necessary play in the cutting edges during rotation of the tool. The two back-off surfaces 56, 58 intersect at a downwardly extending apex 60 that intersects the radially outermost cutting edge 38 and connects the cutting edge 38 with the radially outer edge 38a. It is divided into an inner edge portion 38b (see FIG. 3). The radial slope of the back-off surface 58 ranges from approximately 5 to 35 degrees with respect to the horizontal, with approximately 10 degrees being optimal. The inner back-off surface 56 is at an angle of -3 to +25 degrees, preferably about
Inclined radially to the horizontal by 15°.
Because the back-off surfaces 56, 58 are radially and circumferentially sloped, the cutting edges 34, 36, 3
8 is not only stepped in the circumferential direction as shown in FIGS. 4 and 6, but also
As shown in the figure, when viewed from the front of the tooth, there are also vertical differences in level.

In the case of the cutlery explained above, the cutting edges 34, 3
Since the cutting piece cut by the groove 6 is narrower than the depth of the groove 22, it can be sufficiently accommodated in the groove. However, when the cutting edge 38 cuts a chip over its entire width, the chip tends to expand immediately after being cut and stick between the shoulder 54 and the wall of the hole being cut. . It is an object of the invention to avoid this sticking effect by cutting with each outer cutting edge 38 a cutting piece having a width narrower than the width of the cutting edge 38.

The top 60 of the cutting tooth 18 is the same as the top 6 of the cutting tooth 20.
It can be seen that it is located radially inside of 0. The back-off surface 58 of each tooth 18 is raised perpendicularly over its entire radial length relative to the back-off surface 58 of each tooth 20 so that the top 60 of each successive tooth of the cutter are stepped in the radial direction. This in itself results in the apex 60 of each tooth 18 being located radially inward with respect to the apex 60 of each tooth 20. In accordance with the invention, the back-off surface 56 of each tooth 20 is likewise raised upwardly relative to the back-off surface 56 of each tooth 18 over its entire radial length. Back-off surface 5 of tooth 20
6 displaces the apex 60 radially outwardly from the apex 60 of the tooth 18 by an additional percentage.

The percentage of vertical relief of the back-off surface is not critical, but in any case it must exceed the theoretical chip load on each tooth. For example, a 6-tooth blade per revolution
For a 0.305 mm (0.012 inch) advance, the theoretical chip load on each tooth is 0.051 mm (0.002 inch). Thus, if the theoretical chip load on each tooth is 0.051 mm (0.002 inch), the back-off surfaces 56, 58 will be 0.051 mm (0.051 mm), as described above.
Must be vertically raised a distance greater than mm (0.002 inch). As a practical matter,
A cutting chip load of 0.051 mm (0.002 inch) is the normal minimum cutting chip load when operating the cutting tool, and when operating the above type of annular cutting tool, the normal maximum cutting load is approximately 0.127 mm (0.005 inch). Then, the protrusion of the back-off surfaces 56 and 58 in the vertical direction is
Must be within the range of 0.076 mm (0.003 inch) to 0.308 mm (0.012 inch). However, in the case of large and heavy knives, the feed rate is 0.127mm.
(0.005 inch), the relief is on the order of 0.508 mm (0.020 inch). Actually, the surface is approximately 0.178mm
(0.007 inch) to 0.254 mm (0.010 inch), preferably about 0.229 mm (0.009 inch). The maximum amount of embossing is related to the radial inclination angle of the back-off surface and the width of the outer cutting edge so that when raised, the apex 60 intersects the outer cutting edge 38 rather than the intermediate cutting edge 36. It remains as it is.

It is highly desirable to have the inner and outer back-off surfaces raised such that the crests of the continuous teeth are approximately equally spaced radially from the radial centerline of the groove. When the top is positioned as described above, the outer cutting edges of the successive teeth cut chips of approximately equal width, each being only slightly wider than one-half the depth of the groove. As a result, all cutting chips are in groove 2
The maximum play is within 2.

As previously mentioned, the cutting operation produced by the cutting tool is best understood in the continuous view of FIG. These figures show an annular cutter of said type with six teeth. Teeth designated 1, 3, and 5 (shown on the left in FIG. 7) correspond to the teeth 18 that vertically emboss the back-off surface 58, and teeth designated 2, 4, and 6 in FIG. This corresponds to the teeth 20 which vertically emboss the radially inner back-off surface 56. The successive views of FIG. 7, progressing downward, illustrate the action of successive teeth of the cutter as they rotate successively at a rate equal to the pitch between successive teeth.

FIG. 7a shows the knife in a position where the cutting edge 36 has just begun to penetrate the top of the workpiece and cuts a narrow chip 62 from the top of the workpiece. In this position, the upwardly raised cutting edge 38 of the first tooth has not yet engaged the workpiece, and the lowest point of the cutting edge 34 is about to engage the workpiece. When the blade rotates by one tooth profile pitch and advances in the axial direction from the position shown in Figure 7a, the cutting edge 38 of the second tooth
cuts the workpiece to form a cutting piece 64. The cutting edges 34, 36 of the second tooth are vertically raised by a distance that exceeds the theoretical chip load caused by the axial feed rate, so that the cutting edges 34, 36
is actually spaced above the groove previously formed by the corresponding edge 36 of the first tooth.

When the blade rotates by the next pitch and advances in the axial direction (Fig. c), the cutting edge 36 of the third tooth does not stand out in the vertical direction, and the cutting edge 34 of the third tooth cuts the cutting piece indicated by 66. Because of the cutting, the cutting piece 62 produced by the cutting edge 36 is relatively thick. Cutting edge 38 of third tooth
The radially inner portion of starts cutting and forms a cutting piece 68. When the cutting tool rotates another pitch (figure d), the radially outer part of the cutting edge 38 cuts a wider and deeper groove than the one previously cut by the edge 38 of the second tooth, so that the cutting The piece 64 is wider and thicker than the cutting piece formed by the inner part of the cutting edge 38 of the previous tooth. The edges 34, 36 of the fourth tooth are vertically raised by a distance that exceeds the load of the cutting chip, so that they are in contact with the groove formed by the corresponding cutting edge of the third tooth. Spaced above the bottom.
Figure e illustrates the cutting action of the fifth tooth after additionally increasing the rotation and feed. Cutting edges 34, 36
Although cutting pieces 62 and 66 of sufficient width are cut, only the inner part of the cutting edge 38 in the radial direction works, and the cutting piece 68 cut by this is cut by the inner part of the cutting edge of the third tooth. Wider than one piece.

The width of the chips 62, 66 corresponds to the cutting edges 36, 34, respectively, and expands somewhat immediately after the chips are formed, but as soon as the chips 66 are formed,
Because the upper surface 44 of the first gullet 42 extends radially outwardly into the adjacent groove 22, even though the cutting piece is relatively narrow, it does not stick inside the cutter. Similarly, once the cutting chips 62 are formed, they are oriented radially outward;
The upper surface 50 of the second gullet 46 closes the adjacent groove 22.
Go inside. Thus, the narrow chips formed by the cutting edges 34, 36 are directed into the adjacent grooves 22 immediately after being formed, and the radial depth of the grooves 22 is substantially less than the width of the chips 62, 66. Because of its large size, the chips generally flow freely upwardly within the groove without stagnation.

As can be seen from FIGS. 7e-j, after all cutting edges have entered the workpiece, each of the cutting edges 38a and 38b forms a chip that is narrower than the entire width of the cutting edge 38. do. Thus, the radially outer portion of the edge 38 of each alternating tooth cuts the cutting piece 64;
The radially inner portion of each cutting edge of the intermediate tooth is a cutting piece 68.
to cut. Thus, since the width of each cutting piece 64, 68 is less than the radial depth of the groove 22, it moves freely within the groove.

After all the teeth have entered the workpiece, the back-off surfaces 56, 58 are alternately raised vertically as described above at a rate that exceeds the theoretical chip load.
All chip thicknesses are relatively thick, with a substantial maximum thickness exceeding the theoretical chip load. If the cutting chips are relatively thick, they will not twist tightly, but rather will remain generally straight, so that they will easily flow upwardly into the grooves of the blade without becoming entangled with other cutting chips. Additionally, all of the back-off surfaces 58 are inclined relative to the horizontal by a relatively small angle, preferably about 10 degrees, so that the chips cut primarily by the edges 38a are in the groove. It does not point radially inward against the radially inner surface, but rather directly upwardly within the groove. This emphasizes that all of the chips formed by the cutting edges flow freely upwards within the groove.

As noted in the preamble, when the cutting chips are obstructed from flowing upwardly in the flute away from the cutting edge, the torque and thrust required to drive the blade is reduced in the radial direction. Similarly, the cutting edge gradually dulls, increasing the life of the knife. Additionally, the surface finish obtained by the present invention is substantially superior to that obtained with prior art blades because the cutting edges remain sharp and the cutting chips do not stick to the walls of the hole being cut.

According to the invention, the cutting edges 34, 3 with only alternating teeth
6 performs cutting work. The cutting edges 34, 36 of the teeth 20 (i.e. the teeth designated by numbers 2, 4 and 6 in the embodiment up to FIG. 7) do not perform any cutting;
The cutting edges 34, 36 of the teeth may be completely omitted.
This can be easily accomplished by grinding each tooth 20 completely along its width, as shown by the radial dashed lines 70 in FIGS. 2 and 4. In this case, only the teeth 18 have inner cutting edges 34, 3.
6 will be provided. When tooth 20 is formed with only a single outer cutting edge 38, the circumferential extension of each tooth is relatively short and each tooth 20 cuts only a single narrow cut so that adjacent grooves 22 are , is substantially narrower in the circumferential direction than the groove adjacent the tooth 18 which is required to accommodate three narrow cutting chips. Thus, if only a single cutting edge is formed on the tooth 20, a large number of teeth can be formed on a blade of a given diameter. Having a higher number of teeth not only makes the cutter more powerful, but also allows it to cut more quickly at the same surface speed. Furthermore, since only a portion of the cutting edge of each tooth is actually involved in the cutting operation, the remaining portion is provided with cooling that flows downward through the passage in the blade handle so that the heat generated can be easily dissipated. It can be easily filled with the agent.

The cutters shown in FIGS. 8 to 14 are generally of a type very similar to that described in Japanese Patent Publication No. 51-27511. This type of knife has the advantage that each tooth forms only two cutting edges instead of three, and the inner cutting edge 35 extends over the entire thickness of the web 26.
It is different from the knife mentioned above. For the reasons explained below,
The width of the inner cutting edge 35 corresponds to the thickness of the web 26, which is about 1/2 or slightly more than the thickness of the cutter wall. The inner cutting edge 35 is
Since it extends over the entire width of the cutter, only a single gullet 42 needs to be provided between successive teeth.

As in the previous embodiment, the outer back-off surface 58 of tooth 18 is vertically raised and the inner back-off surface 56 of tooth 20 is similarly raised. Thus,
The crests 60 of the successive teeth are radially staggered in the same manner as in the previous embodiment. however,
In the embodiment shown in FIGS. 8-14, the inner cutting edge 35 extends through the entire thickness of the web 26, and the inner back-off surface 56 of the tooth 18 has a
As shown in Figures 12 and 13, it stands out. The back-off surfaces are raised upwardly only through a portion of their width, ie the radially nearest portion. This allows the inner cutting edge 35 of the tooth 18 to
The radially inner part 35a and the radially outer part 3
5b. As shown in FIGS. 9 and 13, the back-off surface 56 of the tooth 18 is raised over the entire circumferential direction as described above, and the surface 56 is divided into two portions 56a and 56b. The intersecting line between them is indicated by 61.

At cutting edge 35, intersecting line 61 is preferably spaced radially inwardly from shoulder 54 by a distance of 1/4 to 1/2 the thickness of the web. As will be explained below, this allows the inner cutting edges to form chips of desired dimensions. Inside back of tooth 20
Since the off-surface 56 is raised, the surface 56b of the tooth 18 should be reduced to a greater proportion, preferably 2 to 3 times the relief of the back-off surface 56 of the tooth 20, in order to obtain the desired cutting action. It is essential to make it stand out twice as much. For example, if the back-off surface 56 of the tooth 20 is approximately 0.254 mm (0.010 inch) protruding, the back-off surface 56b of the tooth 18 is approximately 0.508 mm (0.020 inch) protruding at the inner circumference of the cutter. ) to 0.762mm
(0.030 inch).

The cutting operations of the cutting tools shown in FIGS. 8 to 13 can be best understood from the continuous view of FIG. 14. The back-off surfaces 56, 58 of the continuous teeth are embossed in the same manner as in the previous embodiment, so that
Next, by means of the outer cutting teeth of the continuous teeth, numbers 64 and 6 are shown in FIG. 14 similar to the corresponding cutting pieces shown in FIG.
Cutting pieces shown at 8 are formed. However, each of the inner cutting edges of the successive teeth cuts a chip of width less than the width of cutting edge 35. Since the back-off surface 56b of each tooth 18 is raised as shown in FIGS. 12 and 13, the cutting edge 35 of each tooth 18 is
The radially innermost portion of each tooth 20 cuts a cutting piece designated by the number 63b in FIG. 14, and the radially innermost portion of the cutting edge 35 of each tooth 20 forms a cutting piece 63a. . Cutting pieces 63a and 63b
The width varies depending on the radial position of the intersecting line 61. Since the radially innermost cutting piece 63a has to travel a longer distance in the radial direction to reach the cutter groove 22, the cutting piece 63a
It is desirable that the width of the cutting piece 3a is smaller than the cutting piece 63b. Thus, as shown in FIG. 14, the intersection line 61 is spaced apart from the shoulder 54 by a distance corresponding to approximately one third of the thickness of the web 26, and the cutting strip 63a is substantially wider than the cutting strip 63b. narrow.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an annular drilling cutter according to the present invention, FIG. 2 is a partial perspective view of the cutter, and FIG. 3 is a
A partial view of the blade seen from the front of one of the teeth of the blade,
Fig. 4 is a bottom view of the tooth shown in Fig. 3, and Fig. 5 is a bottom view of the tooth shown in Fig. 3.
FIG. 6 is a partial view of the tooth following FIG. 3, FIG. 6 is a bottom view of the tooth shown in FIG. 5, and FIG. 7 is a partial view of the tooth shown in FIG.
A continuous diagram showing the order of entering the workpiece, Figure 8, is
Perspective views of different types of cutlery of the present invention, Nos. 9, 10, 11,
12 and 13 are drawings of the different type cutlery corresponding to FIGS. 2 to 6, respectively, and FIG.
FIG. 14 is a continuous view showing two successive teeth of the cutter entering the workpiece in FIGS. 1 to 13; FIG. DESCRIPTION OF SYMBOLS 10... Blade, 12... Blade body, 16... Blade side wall, 18, 20... Cutting tooth, 22... Groove, 26... Web, 30, 32... Groove side wall, 34, 36, 38...
Cutting edge, 42... Galette, 56, 58... Back
Off surface, 60...top, 62, 66, 68...cutting pieces.

Claims (1)

[Claims] 1. The cutter body 12 consists of a cylindrical side wall 16, and a plurality of cutting teeth 1 are provided at the lower end of the side wall 16 at intervals in the circumferential direction.
8, 20, the cutting teeth being separated by a plurality of grooves 22 extending from the lower end upwardly around the outer periphery of the side wall and a gullet 42 inside the grooves 22 at the lower end of the side wall 16. , each of said cutting teeth has a cutting edge abutting the rear side of said groove and gullet, and also has radially inner and outer back-off surfaces 56, 5 on the bottom surface of said cutting teeth.
8, the inner and outer back-off surfaces intersect to form at least one circumferential apex 60, the apex having its front end in contact with the rear side surface of the groove 22. In an annular drilling cutter that crosses the edge, the top 60 of one adjacent tooth 18 touches the other tooth 2.
The width of the cutting piece cut by all of the plurality of cutting edges and gullets 42, which are arranged radially offset from the top 60 of the groove 22 and are formed in contact with the rear side surface of the groove 22, is An annular drilling knife characterized in that the depth in the radial direction is less than the depth of the groove 22.