JP3718665B2 - Drill bit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drill bit in which a cemented carbide cutting edge tip is fixed to the tip of a bit body by brazing, welding, or the like, and more specifically, a drill bit having high rigidity and suitable for drilling concrete, stone, or the like. It is about.
[0002]
[Prior art]
For drilling concrete, stone, etc., a dedicated drill bit is attached to the rotary hammer drill, and the drill bit is drilled by applying both the impact force and rotational torque in the axial direction at the same time. (Drilling) is done. In order to meet the demand for higher efficiency of this kind of drilling work, as a drill bit, a cutting edge tip made of cemented carbide with excellent wear resistance is brazed or welded to the tip of the steel bit body. There are many things fixed by.
[0003]
As this type of drill bit, the applicant previously formed a plurality of cutting blade portions on a cemented carbide cutting blade tip made of a block body fixed to the tip of the bit body, and each cutting blade portion. The cutting edge and flank joining edge formed above were used as cutting edges, and the inner edges of these cutting edges were joined at the tip of the cutting edge to make the tip of the cutting edge apex without a chisel point and formed between each cutting edge. The drill bit of the structure which made the recessed part continue in the chip discharge groove | channel provided in the outer periphery of a bit main body was proposed (refer Japanese Patent Application No. 2000-377082).
[0004]
According to the drill bit of this configuration, by drilling in concrete or stone material, the cutting blade impacts the drill hole cutting surface impactively, and following the cutting, the cutting blade is bitten into the drill hole cutting surface. Drilling is performed by rotating rotary cutting, and chips generated on the drill hole cutting surface are lifted from the drill hole cutting surface along with the movement of the drill bit in the axial direction, and between the cutting blades, Since the chip is smoothly discharged to the outside of the drill hole through the chip discharge groove, the tip of the blade tip has a tip shape with no chisel point, so the rotation balance is good when drilling, and the tip of the tip of the tip is always the center of the drill hole cutting surface. In response to the above, it is possible to drill a constant-diameter hole with high accuracy.
[0005]
[Problems to be solved by the invention]
Considering the drilling action when a drill bit without a chisel point as described above is attached to a rotary hammer drill and drilling into concrete, stone, etc., cutting by an axial impact force, that is, a cutting edge In impact cutting, where the drill hole cutting surface is impacted and the drill hole cutting surface is crushed, the degree of crushing by each cutting blade is the tip of the blade tip that forms the tip shape where the inner edge of the cutting blade is concentrated. The part becomes larger.
[0006]
In addition, when the cutting edge bites into the drill hole cutting surface following the impact cutting and the rotation cutting involves rotation, the cutting amount by each cutting edge increases at the peripheral edge of the cutting edge.
[0007]
Thus, when observing the wear of each cutting blade after repeated use for drilling, the wear of each part of the cutting blade does not necessarily progress uniformly, and the outside of the cutting blade that increases the amount of cutting during rotary cutting is not necessarily obtained. The wear of the end portion is large, and when it is applied from the middle portion of the cutting blade to the tip of the cutting edge, there is no great difference in the degree of wear for each cutting blade. This is because the adjacent cutting blades approach each other from the middle part of the cutting blade to the top of the cutting edge, and each rotary blade bites into the drill hole cutting surface during rotary cutting. However, since the peripheral speed is also smaller than the outer edge of the cutting edge, it is considered that a large cutting resistance is not applied and the effective cutting of the cutting edge outer edge is not possible. .
[0008]
Therefore, the present invention eliminates uneven cutting resistance applied to each part of the cutting edge during rotary cutting on the drill hole cutting surface, and each part of the plurality of cutting edges cooperates to efficiently and smoothly rotate the cutting surface of the drill hole. Thus, an object of the present invention is to provide a drill bit that can reduce the partial wear of the cutting edge and extend the service life.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a drill bit according to the present invention has a cutting surface formed on each cutting blade portion by forming a plurality of cutting blade portions on a cutting blade tip made of a cemented carbide block body. The cutting edge is the joining edge of the flank, the inner edge of the cutting edge of one of the cutting edges forms the edge of the cutting edge, the inner edge of the cutting edge of the other cutting edge is terminated before the edge of the cutting edge, It is characterized in that a notch recess is formed in each cutting blade.
[0010]
In the drill bit according to the present invention, a plurality of cutting edge portions are formed on a cutting edge tip made of a block body made of cemented carbide, and the joining edge of the cutting surface and the flank formed on each cutting edge portion is formed as a cutting edge. The inner edges of the cutting edges of at least two cutting edges are abutted at the edge of the cutting edge, the inner edges of the cutting edges of the other cutting edges are terminated before the edge of the cutting edge, and a notch is formed in each cutting edge. It is good also as what is characterized by this.
[0011]
Here, the positions of the notch recesses are shifted by the adjacent cutting blades, all the notch recesses are formed leaving the outer edge of the cutting blades, and the notch recesses of the adjacent cutting blades are one of them. It is preferable that the portions are overlapped in the rotation direction and the length of the notch recess is changed.
[0012]
According to the drill bit configured in this way, when cutting with a cutting edge biting into the drill hole cutting surface, there is no cutting action at the notch recess, the cutting resistance is reduced, and the drill hole cutting surface is reduced. However, the remaining part of the cutting edge is appropriately cut by the other cutting blades, and each part of the plurality of cutting blades is responsible for rotating the drill hole cutting surface. Therefore, the cutting force on the drill hole can be efficiently and smoothly cut by effectively using the rotational torque, the uneven wear of the cutting edge can be reduced, and the useful life of the drill bit can be extended.
[0013]
Further, in the present invention, the inner ends of the cutting edges of at least two cutting edges, for example, of the plurality of cutting edges formed on the cutting edge tip made of a cemented carbide block body are butted at the tip of the cutting edge. With this configuration, the tip of the blade tip can be shaped like a tip without a chisel point. Since the apex of the apex is fitted in the recess at the center of the drill hole cutting surface to exhibit a guide function, the effect of preventing the drill bit from running out is enhanced, and a highly accurate constant diameter hole can be drilled.
[0014]
In addition, the depth of the notch recess is not particularly limited, but in the case of a drill bit for drilling concrete or stone, the depth of the notch recess is practically set.
It is preferable to set to 0.2 mm to 1 mm . Further, in order to form a notch recess in the cutting blade, the notch recess can be formed in a shallow groove shape with a flat bottom structure by hanging from the corresponding flank to the notch recess. In this case, the workability of the drill bit is improved and the production cost can be reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a front view of a main part in which a part of a drill bit showing an embodiment of the present invention is omitted, FIG. 2 is a bottom view of the drill bit, and FIG. 3 is a perspective view of a cutting edge chip corresponding to FIG. FIG. 4 is an explanatory diagram for explaining the positional relationship of each notch recess with respect to the drill hole cutting surface.
[0017]
In the figure, reference numeral 1 denotes a steel bit body. A shank (not shown) connected to the drive shaft of a rotary hammer drill is extended on the upper part, a chip discharge groove 2 is provided on the outer periphery of the bit body, and a bit body tip is provided. A cutting blade tip 3 made of a cemented carbide block body is fixed by brazing, welding, or the like, and three cutting blade portions 3a, 3b, 3c are circumferentially attached to the cutting blade tip 3 in the embodiment. It is shaped.
[0018]
Each cutting edge portion 3a, 3b, 3c is formed with a cutting surface 6 and a flank 7 so that the joining edges on both sides are the cutting edges 4, the inner ends of the respective cutting edges 4 are butted and the tip 8 is the chisel point. There is no pointed shape.
[0019]
In the present invention, notch recesses 5a, 5b, 5c are formed in the cutting edge 4 of each of the cutting edge portions 3a, 3b, 3c. In the embodiment, these notch recesses 5a, 5b, and 5c are formed in a shallow groove shape with a flat bottom by hanging from the corresponding flank 7 to the cutting edge 4, so that the practical notch recesses 5a and 5b are formed. , 5c is set to 0.2 mm to 1 mm. Moreover, since the bottom part of each notch recessed part 5a, 5b, 5c forms and joins the joining edge with respect to the cutting surface 6 similarly to the cutting blade 4, this joining part exhibits the function as an auxiliary cutting blade. .
[0020]
Moreover, all the notch recessed parts 5a, 5b, 5c are formed leaving the outer edge part of the cutting blade 4, and each notch recessed part 5a, 5b, 5c is a position and length in the cutting blade 4. Is changing. That is, as shown in FIGS. 2 and 3, the notch recess 5 a of the cutting edge 4 of the cutting edge 3 a is located near the outer end of the cutting edge 4 and is the shortest with the outer end of the cutting edge 4 remaining. are doing. The notch recessed part 5b of the cutting blade 4 of the cutting blade part 3b is located in the intermediate part of the cutting blade 4, and is longest. The notch recessed part 5c of the cutting edge 4 of the cutting edge part 3c is located near the inner end of the cutting edge 4, and this notch recessed part 5c itself is substantially the same length as the notch recessed part 5a. A cutout portion 5d is formed in an inclined shape from the side to the blade tip apex 8, and is substantially set to the same length as the cutout recess portion 5b.
[0021]
Further, in the embodiment, in forming each notch recess 5a, 5b, 5c, as shown in FIG. 4, the drill hole cutting surface cut by the cutting blade 4 is concentrically arranged in four ranges A1, A2. , A3, A4, and the cutting edge 4 of the cutting edge 3a is formed with a notch recess 5a having a length that leaves the range A2, and the cutting edge 4 of the cutting edge 3b has a range A2˜ A notch recess 5b having a length to leave A3 is formed, and a notch recess 5c having a length to leave the range A3 is formed on the cutting edge 4 of the cutting edge portion 3c. An inclined notch 5d reaching the blade tip vertex 8 is formed on the end side so as to leave the ranges A3 to A4.
[0022]
In the above configuration, according to the present invention, when rotating cutting is performed on the drill hole cutting surface, the cutting of the peripheral portion of the drill hole cutting surface that places the greatest cutting burden on the cutting edge 4 is performed by three cuttings. The outer end portion of the blade 4 cooperates, and the uncut portion of the drill hole cutting surface is left at the notch recesses 5a, 5b, 5c and the notch portion 5d formed in each of the cutting blades 4. Cutting of the remaining portion of the intermediate portion of the surface is performed by the cutting blade portion 3a and the cutting blade 4 of the cutting blade portion 3c in cooperation, and the remaining portion of the center portion of the drill hole cutting surface is joined at the tip 8 of the cutting edge. The two cutting blades 4 that perform the cutting work together. Thus, the remaining portion of the drill hole cutting surface generated at the notch recesses 5a, 5b, 5c and the notch 5d formed in each cutting edge 4 is appropriately cut by the subsequent other cutting edges 4. The unevenness of the cutting force applied to each cutting edge 4 is eliminated, and each part of the three cutting edges 4 can cooperate to efficiently rotate the cutting surface of the drill hole.
[0023]
【The invention's effect】
The present invention is implemented in the form as described above, and according to the present invention, the basic configuration of the drill bit is the same as that of a well-known drill bit of this kind. And can be used as is.
[0024]
Thus, in the drill bit of the present invention, a notch recess is formed in a plurality of cutting blades constituting the cutting edge, and the cutting edge is subjected to cutting (striking cutting) in which the cutting edge impacts the drill hole cutting surface. When cutting into the drill hole cutting surface and rotating cutting, each part of the cutting blade is assigned to rotate the drill hole cutting surface, so each cutting blade has no uneven cutting resistance applied to the cutting edge and effectively uses the rotational torque Thus, efficient and smooth rotary cutting can be performed, and uneven wear of the cutting edge can be reduced to extend the service life of the drill bit.
[Brief description of the drawings]
FIG. 1 is a front view of a main part in which a part of a drill bit showing an embodiment of the present invention is omitted.
FIG. 2 is a bottom view of the drill bit.
FIG. 3 is a perspective view of a cutting edge chip corresponding to FIG. 2;
FIG. 4 is an explanatory diagram for explaining a positional relationship of each notch recess with respect to a drill hole cutting surface;
[Explanation of symbols]
1 Bit body 2 Chip discharge groove 3 Cutting edge tips 3a, 3b, 3c Cutting edge part 4 Cutting edge 5a, 5b, 5c Notch recess 5d Notch part 6 Cutting surface 7 Relief surface 8 Cutting edge vertex
A1, A2, A3, A4 range

Claims (8)

A cutting blade tip made of a cemented carbide block body is formed with a plurality of cutting blade portions, and the cutting edge formed on each cutting blade portion and the joining edge of the flank surface are used as cutting blades, and any cutting blade portion The drill bit is characterized in that the inner edge of the cutting edge forms the tip of the cutting edge, the inner edge of the cutting edge of the other cutting edge is terminated before the edge of the cutting edge, and a notch is formed in each cutting edge. . A cutting edge chip made of a cemented carbide block body is formed with a plurality of cutting edge portions, and a cutting edge formed on each cutting edge portion and a joining edge of a flank face as a cutting edge, and at least two cutting edge portions The inner edge of each of the cutting edges is abutted at the edge of the cutting edge, the inner edge of the cutting edge of the other cutting edge is terminated before the edge of the cutting edge, and a notch is formed in each cutting edge. The drill bit described.   The drill bit according to claim 1 or 2, wherein the position of the notch recess is shifted between adjacent cutting edges.   The drill bit according to any one of claims 1 to 3, wherein all the notch recesses are formed leaving an outer end portion of the cutting blade.   The drill bit according to any one of claims 1 to 4, wherein notch recesses of adjacent cutting blades are partially overlapped in the rotation direction.   The drill bit according to any one of claims 1 to 5, wherein the length of the notch recess is changed between adjacent cutting edges.   The drill bit according to any one of claims 1 to 6, wherein the depth of the notch recess is set to 0.2 mm to 1 mm.   The drill bit according to any one of claims 1 to 7, wherein the notch recess is formed in a shallow groove shape having a flat bottom structure by hanging from the corresponding flank to the notch recess.

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