JPH1158116A - Core drill and hole drilling method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hole drilling method and a core drill in which only a small amount of the fibrous material on the outer side of a part to be cut is torn off in cutting the fibrous material. SOLUTION: A marking blade 7, an outer blade 8 and an inner blade 9 are provided as a blade body H to be embedded in a blade part 6. The marking blade 7 is provided with a blade tip located on a part corresponding to an outer edge of a hole to be cut and an inclined surface which is inclined upward on the radially inner side from the blade tip, and the outer edge of the hole to be cut is marked. The fibrous material present across the inner side and the outer side of a part to be cut is divided. During the cutting by the outer blade 8 or the inner blade 9 which is achieved after the marking by the marking blade 7, no fibrous material is hooked and torn off by the outer blade 8 or the inner blade 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core drill for cutting and drilling a hole and a method for drilling a hole using the same.
More particularly, the present invention relates to a core drill suitable for cutting and drilling a hole in an object to be cut containing fibrous material and a hole drilling method using the same.

[0002]

2. Description of the Related Art A core drill is used as a cutting tool for making a hole in a wooden board, a plastic board, a metal board, a gypsum board or the like. This core drill has a cylindrical body,
It comprises a shank mounting portion provided at the upper end of the main body and an annular blade provided below the main body. A blade body such as a carbide tip is embedded in the lower end surface of the blade portion. The shank mounting portion is mounted on the shank, and the shank is mounted on the drill body. The core drill rotates through the shank by driving the drill body, and the blade body cuts the workpiece. The planar shape of the portion to be cut (hereinafter also referred to as a “cut portion”) is an annular band having a width substantially equal to the width of the blade body. By performing this cutting from the upper surface to the lower surface of the work, the cut portion and the portion surrounded by the cut portion are removed from the work, and holes are formed in the work. Conventionally, blades of various shapes have been used to increase cutting efficiency, and a core drill using two types of blades having different shapes has also been proposed (for example,
Japanese Patent Publication No. 62-24205, etc.).

By the way, when a fiber material such as a wood material or a fiber-reinforced resin is cut using the core drill, the blade body hooks the fiber material and peels it off. If the fibrous material outside the part to be cut (that is, outside the outer edge of the hole to be drilled) is peeled, traces of the peeled remain on the final product, not only impairing the appearance, but also strength, dimensional accuracy, touch, There is a problem that the quality such as wettability of the paint is deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a core drill which does not peel off the fibrous material outside the cut portion even when the fibrous material is cut, and a core drill having the same. It is an object of the invention to provide a method of drilling holes.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention has a cylindrical main body and an annular blade located below the main body. In a core drill for drilling a hole in which a plurality of blades are provided, (1) a blade edge located at a position corresponding to an outer edge of a hole to be drilled, and a radially inward direction from the blade edge. A squeezing blade that has an inclined surface that is inclined upward and that presses and squeezes the outer edge portion of the hole to be drilled from above, and (2) a main blade that cuts the inside of the outer edge portion squeezed by the squeezing blade. A core drill is provided (claim 1).

Another invention made to solve the above-mentioned problem is a hole drilling method for drilling a hole in the fibrous material by cutting the fibrous material using a core drill. A hole drilling method, comprising cutting fibrous material at an outer edge portion of a hole to be drilled by a blade body provided in a core drill, and then cutting the inside of the outer edge portion by a blade body provided in the core drill. (Claim 6).

According to these inventions, first, the fibrous material is divided at the outer edge of the hole to be drilled. Thereafter, a portion inside the fibrous material is cut off.
Therefore, peeling of the fibrous material outside the portion to be cut during cutting is suppressed. In order to sharply cut the fibrous material, the lower end surface of the cutting blade may be inclined upward from the rear in the rotation direction to the front in the rotation direction. In addition, in order to surely cut the fibrous material by the Kebiki blade before cutting by the main blade, the position of the cutting edge, which is the lower end of the Kebiki blade, may be lower than the position of the lower end of the main blade. .

In the present invention, in order to efficiently perform cutting by the main blade, the main blade includes an outer blade which mainly cuts a radially outer portion of a portion to be cut and a radially inner portion of the portion to be cut. And an inner blade for mainly cutting (claim 4). In this case, if the position of the lower end of the outer blade is lower than the position of the lower end of the inner blade,
Cutting proceeds in the order of the outer blade and the inner blade, and a hole can be formed easily and efficiently (claim 5).

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partial sectional view showing a state in which a core drill 1 according to an embodiment of the present invention is mounted on a shank 2 as viewed from the front. Note that reference numeral 3 in FIG. 1 denotes a center drill whose upper end is attached to the shank 2.

The core drill 1 includes a cylindrical main body 4, a shank mounting portion 5, and a blade 6. The shank attachment part 5 is provided integrally with the main body part 4 above the main body part 4, has a substantially cylindrical shape, and has a smaller diameter than the main body part 4. The core drill 1 is attached to the shank 2 by inserting and fixing the lower end of the shank 2 to the shank attachment portion 5. In this embodiment, the projection 10 provided on the inside of the shank mounting portion 5 is locked by the locking recess 11 provided on the shank 2 so that the protrusion 10 is provided in the axial direction (vertical direction).
The movement of the core drill 1 is prevented.
0 is brought into contact with the ball 12 provided on the shank 2, thereby preventing the relative movement of the core drill 1 and the shank 2 in the rotation direction. As the means for fixing the core drill 1 and the shank 2, various known means can be used in addition to the illustrated means.

The blade portion 6 is provided below the main body portion 4 so as to be continuous with the main body portion 4 and is annular. Outer peripheral surface 1 of blade 6
3 is configured to bulge radially outward from the outer peripheral surface 14 of the main body 4, so that the blade 6 is thicker than the main body 4. A blade body H made of a carbide tip is buried in the lower end surface 15 of the blade portion 6 with its blade tip protruding downward. In the outer peripheral surface 13 of the blade portion 6, near the front of the blade body H in the rotation direction (indicated by an arrow R in FIG. 1), a chip discharge groove 16 is provided which is inclined upward from the bottom toward the rear in the rotation direction. Have been.

The lower end surface 15 of the blade 6 is inclined upward from the outside in the radial direction to the inside in the radial direction. This can prevent interference between the grindstone and the lower end face 15 when polishing the blade body H embedded in the blade portion 6 with the grindstone.

FIG. 2 shows a view (bottom view) of the core drill 1 as viewed from the blade portion 6 side. As shown in this figure, three types of blade bodies H of a rivet blade 7, an outer blade 8 as a main blade, and an inner blade 9 as a main blade are embedded in the lower end surface 15 of the blade portion 6 of the core drill 1. ing. The arrangement of each blade H
The central angles are equally spaced at intervals of 120 °. And
The blades H are arranged such that the cutting blade 7, the outer blade 8, and the inner blade 9 are arranged in this order when viewed from the front in the rotation direction (indicated by an arrow R in FIG. 2). Each blade body H is buried obliquely with respect to the rotational direction such that the radially inner portion is located forward of the radially outer portion in the rotational direction in order to reduce cutting resistance and facilitate chip discharge. ing.

FIGS. 3 (a), 3 (b) and 3 (c) are cross-sectional views of the vicinity of the rivet blade 7, the outer blade 8 and the inner blade 9 along the radial direction. In each figure, the right side is the radial outside, and the left side is the radial inside.
As shown in FIG. 3A, the cutting edge 7 has a cutting edge 71 located on the outermost side in the radial direction and an inclined surface 72 inclined upward from the cutting edge 71 toward the inside in the radial direction. As shown in FIG. 3 (b), the outer blade 8 is
A first inclined surface 82 inclined upward from the cutting edge 81 radially outward; a second inclined surface 83 inclined upward from the cutting edge 81 radially inward;
A third inclined surface 84 that is continuous with the inclined surface 83 and that is inclined with a larger gradient than the second inclined surface 83 is provided. The position of the boundary between the second inclined surface 83 and the third inclined surface 84 is substantially at the center of the outer cutter 8 in the width direction. As shown in FIG. 3C, the inner blade 9 has a cutting edge 91, a flat surface 92 extending flat from the cutting edge 91 radially outward, and a slant upward from the cutting edge 91 radially inward. And an inclined surface 93. The position of the cutting edge 91 is substantially at the center of the inner blade 9 in the width direction.

FIG. 4 shows a cutting blade 7, an outer blade 8 and an inner blade 9.
Is a schematic diagram showing the positional relationship in the vertical direction. In this drawing, the blade bodies H are shown side by side for convenience. Also in this figure, the right side is the radial outside, and the left side is the radial inside. 4, the vertical position of the lower end of the blade H (in this embodiment, the vertical position of the lower end coincides with the vertical position of the cutting edges 71, 81, 91) is such that the kebiki blade 7 is the lowest. Then, the outer cutter 8 and the inner cutter 9 are arranged in that order. Also, the third inclined surface 84 of the outer cutter 8
The inclined surface 93 of the inner blade 9 is located lower than the inner blade 9.

FIG. 5 is a partially enlarged view of the vicinity of the cutting edge 7 when the core drill 1 is viewed from the outside in the radial direction. As is clear from this figure, the blade lower end surface 73 of the rivet blade 7 is inclined upward from the rear in the rotation direction (indicated by an arrow R in FIG. 5) to the front in the rotation direction.

Next, a method of drilling a hole in the workpiece 17 using the core drill 1 will be described. First, as described above, the shank 2 to which the core drill 1 and the center drill 3 (see FIG. 1) are attached is attached to a drill body (not shown), and the core body 1 and the center drill 3 are driven by driving the drill body. Rotate. Then, the tip of the center drill 3 is brought into contact with the center position of the hole to be drilled, and cutting is started. The cutting with the center drill 3 is not intended for the cutting itself, but for the alignment of the cutting with the core drill 1.

As the cutting with the center drill 3 progresses, the core drill 1 moves downward, and the lower end of the blade 6 comes into contact with the upper surface 18 of the workpiece 17 to start cutting with the core drill 1. At this time, as shown in FIG.
The cutting edge 71 of the lowermost cutting blade 7 first comes into contact with the workpiece 17, and the outermost part in the radial direction of the part to be cut (that is, the outer edge of the hole to be drilled) is cut.
Then, the fibrous material extending over the outside and the inside of the cut portion is divided. At this time, as described above, the kebiki blade 7
Since the blade lower end surface 73 (see FIG. 5) is inclined upward from the rear in the rotation direction to the front in the rotation direction, the fiber can be pushed off while pressing the fiber from above. Can be achieved.
In order to sharply cut the fibrous material, it is preferable that the inclination angle of the blade lower end surface 73 be 10 degrees or more and 40 degrees or less with respect to the horizontal direction.

The inclined surface 72 is simultaneously formed with the cutting edge 71.
The portion near the outer edge of the hole to be drilled is cut by
The cut swarf is discharged upward and outward through a swarf discharge groove 16a (see FIG. 2) provided immediately forward in the rotation direction of the rivet blade 7. By providing the inclined surface 72 in this way, not only the cutting edge of the outer edge portion but also the cutting in the vicinity of the outer edge portion can be performed by the cutting edge 7, and the width of the portion where the fibrous material is divided by the cutting edge is widened. be able to. Therefore, even when the drill body is misaligned during cutting by an outer blade (final blade) described later, there is no possibility that the fiber material outside the outer edge portion is peeled off.

As the cutting further proceeds, the cutting edge 81 of the outer cutter 8 is moved to the upper surface 1 of the workpiece 17 as shown in FIG.
Touch 8. Then, the first inclined surface 82 and the second inclined surface 83 of the outer cutter 8 cut the workpiece 17. The portion mainly cut by the outer cutter 8 is a portion closer to the outside in the radial direction than the center of the width of the portion to be cut (indicated by a double-headed arrow A in FIG. 6B). The cut chips are fed to a chip discharge groove 16 provided immediately in front of the outer blade 8 in the rotation direction.
b (see FIG. 2) and discharged upward and outward.

When the cutting further proceeds, the cutting edge 91 of the inner cutter 9 is moved to the upper surface 1 of the workpiece 17 as shown in FIG.
Touch 8. As described above, since the inclined surface 93 of the inner cutter 9 is located lower than the third inclined surface 84 of the outer cutter 8, the inclined surface 93 of the inner cutter 9 is radially inward from the center of the width of the portion to be cut. The closer part is mainly cut. The cut chips are discharged upward and outward through chip discharge grooves 16 c (see FIG. 2) provided immediately forward in the rotation direction of the inner blade 9.

At the time of cutting by the outer cutter 8 or the inner cutter 9, the fibrous material has already been divided by the squeeze cutter 7.
Alternatively, the inner blade 9 does not hook and peel the fibrous material outside the portion to be cut. Therefore, the traces left on the final product will damage the appearance,
There is no reduction in quality such as dimensional accuracy, touch, and wettability of the paint.

Such cutting is performed on the upper surface 1 of the workpiece 17.
By applying from 8 to the lower surface, the portion to be cut and the portion surrounded by the portion to be cut are removed from the workpiece 17, and a hole is formed in the workpiece 17.

In this embodiment, the blade body H is provided with one squeeze blade 7, one outer blade 8 and one inner blade 9, but the blade body H
Is not limited to this. For example, two rivet blades 7, two outer blades 8, and two inner blades 9 may be provided. In this case, the blade bodies H may be arranged in the order of "Keviki blade 7, outer blade 8, inner blade 9, kebiki blade 7, outer blade 8, inner blade 9" when viewed from the front in the rotation direction. , "Keviki blade 7, Kebiki blade 7, Outer blade 8, Outer blade 8, Inner blade 9, Inner blade 9" may be arranged in this order. In addition, one knives blade 7 is provided, two outer knives 8 and two inner knives 9 are provided, and the arrangement order is “Keviki knives 7, outer knives 8, inner knives 9, outer knives 8, inner knives 9”. You may comprise so that it may become. Further, instead of providing two types of blade bodies H of the outer blade 8 and the inner blade 9 as the main blade, a single type of main blade is provided,
The blade H may be constituted by the main blade and the rivet blade 7.

In this embodiment, the center drill 3 is used for positioning, but the center drill 3 may be omitted. Instead of the center drill 3, a center pin that retreats upward along with the progress of cutting may be provided, and positioning may be performed with this center pin.

[0027]

As described above, in the hole drilling method, the fibrous material is cut off at the outer edge of the hole to be drilled and then cut inside the outer edge to prevent the fibrous material from being peeled off. can do. By providing the cutting blade and the main blade as the blade body, it is possible to obtain a core drill in which even if the fibrous material is cut, the fibrous material outside the portion to be cut is hardly peeled off.

In particular, if the lower end surface of the kebiki blade is inclined upward from the rear in the rotational direction to the front in the rotational direction, the quality of the back can be sharply divided. In addition, if the lower end position of the cutting blade is lower than the lower end position of the main blade, it is possible to more surely cut the fiber by the cutting blade prior to cutting by the main blade.

Further, by forming the main blade from an outer blade and an inner blade, particularly by setting the lower end of the outer blade below the lower end of the inner blade, a core drill having high cutting efficiency can be obtained. it can.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a state in which a core drill according to an embodiment of the present invention is attached to a shank, as viewed from the front.

FIG. 2 is a bottom view of the core drill shown in FIG. 1;

FIG. 3A is a cross-sectional view of the core drill shown in FIG. 1 taken along a radial direction in the vicinity of a cutting edge, and FIG.
3 is a cross-sectional view along the radial direction near the outer cutter of the core drill shown in FIG. 1, and FIG. 3C is a cross-sectional view along the radial direction near the inner cutter of the core drill shown in FIG. 1. .

FIG. 4 is a schematic diagram showing a vertical positional relationship between a rivet blade, an outer blade, and an inner blade of the core drill shown in FIG. 1;

FIG. 5 is a partially enlarged view of the core drill shown in FIG. 1;

6 (a) is a cross-sectional view along a radial direction showing a state of cutting an object to be cut by the crevices of the core drill shown in FIG. 1, and FIG. 6 (b) is FIG. FIG. 6C is a cross-sectional view taken along a radial direction showing a state of cutting the work with the outer blade of the core drill shown in FIG. 6. FIG. 6C is a sectional view of the work with the inner blade of the core drill shown in FIG. FIG. 3 is a cross-sectional view taken along a radial direction showing a state of cutting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Core drill 2 ... Shank 3 ... Center drill 4 ... Body part 5 ... Shank mounting part 6 ... Blade part 7 ... Kebiki blade 73 ... Blade lower end surface 8. ..Outer blade 9 ・ ・ ・ Inner blade 15 ・ ・ ・ Lower end face 16, 16a, 16b, 16c ・ ・ ・ Chip discharge groove H ・ ・ ・ Blade

Claims (6)

[Claims] A core drill for drilling a hole, comprising: a cylindrical main body; and an annular blade located below the main body, wherein a plurality of blades are provided at a lower end surface of the blade. The blade body includes: (1) a cutting edge located at a position corresponding to the outer edge of the hole to be drilled, and an inclined surface inclined upward inward in the radial direction from the cutting edge; A core drill provided with a rivet blade for pressing and piercing the outer edge portion of the rim from above, and (2) a main blade for cutting the inside of the outer edge portion revitalized by the rivet blade. 2. The core drill according to claim 1, wherein a lower end surface of the cutting blade is inclined upward from a rear side in a rotational direction to a front side in a rotational direction. 3. The core drill according to claim 1, wherein a position of a cutting edge, which is a lower end of the cutting blade, is lower than a position of a lower end of the main blade. 4. The invention according to claim 1, wherein the main blade comprises an outer blade for mainly cutting a radially outer portion of the portion to be cut and an inner blade for mainly cutting a radially inner portion of the portion to be cut. 3. The core drill according to any one of 3. 5. The core drill according to claim 4, wherein a position of a lower end of the outer cutter is lower than a position of a lower end of the inner cutter. 6. A hole drilling method for drilling a hole in a fibrous material by cutting the fibrous material using a core drill, the outer edge of the hole to be drilled by a blade body provided in the core drill. A hole drilling method comprising cutting fibrous material at a portion, and then cutting the inside of the outer edge portion with a blade body provided on a core drill.