JP3964876B2 - Drill bit - Google Patents

Description

  The present invention relates to a drill bit, and more particularly to a drill bit that can be attached to a vibration drill device and drilled in stone or concrete.

Conventionally, when drilling holes in stone or concrete, a drill bit made of cemented carbide or the like is attached to a vibration drill device, and rotation and axial vibration (striking) are applied to the drill bit. It is carried out.
As this type of drill bit, a plurality of cutting edge portions are provided in the circumferential direction, and the ridge line of the rake face and the flank face formed on each cutting edge portion is used as a cutting edge, and the inner diameter end of each cutting edge is a bit. Some are configured to be joined at the center of the tip (see Patent Document 1).
Japanese Patent Application Laid-Open No. 2002-178328.

  However, in the drill bit having the above configuration, the flank face behind the cutting edge is formed of a single surface having the same inclination angle from the inner diameter end portion to the outer diameter end. When the object is brought into impact contact with an object to be cut such as concrete, the outer diameter end which is a free end is likely to be lost. On the other hand, if the inclination angle in the axial direction of the flank is reduced so that the cutting edge does not break at the outer diameter end, the crushing ability to be crushed when it comes into contact with an object to be cut is reduced. As a result, the drilling performance is reduced. In addition, as described above, if the flank is configured with a surface having a small inclination angle, the flank protrudes from the cutting edge to the tip side at the joint with the rake face at the rear in the rotation direction. It is necessary to form a joint surface, and the construction of the drill bit is complicated for negative technical reasons.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a drill bit that does not deteriorate the drilling performance and does not lose the outer diameter end of the cutting edge.

The object of the present invention is solved by a drill bit according to claim 1. That is, in the drill bit according to the present invention, a plurality of cutting blade portions are arranged in the circumferential direction, and a joining edge line of a rake face and a flank surface formed on each cutting blade portion is used as a cutting blade. In the drill bit having a tip part joined at the center part in the bottom view of the bit tip, the one end on the inner diameter side,
At least one of the cutting blades has a first flank at the outer peripheral end, and a second flank having a different inclination angle from the first flank at the inner peripheral side ,
The first flank has a flank side flank near the cutting edge and a basal side flank formed on the base side of the flank side flank;
An inclination angle in the axial direction of the cutting edge side flank is configured to be smaller than an inclination angle in the axial direction of the proximal end flank.

  When the drill bit is configured as described above, it is possible to increase the rigidity of the outer diameter end portion of the cutting edge, and it is possible to prevent the outer diameter end portion from being damaged. Also, the second flank located on the inner diameter side is provided with an axial inclination angle in consideration of drilling efficiency (an inclination angle focusing on the drilling efficiency only; generally an inclination angle larger than the outer diameter side). Thus, efficient drilling can be performed. And since the inclination angle of the second flank can be configured to be large, the joint portion with the rake face adjacent to the rear in the rotational direction can be set at a position retracted in the axial direction from the cutting edge. The structure which does not need to form the joint surface for preventing the protrusion to the front end side like the past can be implement | achieved.

  As described above, according to the drill bit according to the present invention, it is possible to achieve two contradictory technical problems of eliminating the cutting edge portion defect and maintaining high drilling efficiency, and to satisfy the negative demands. Can be avoided.

  In the drill bit, when the inclination angle in the axial direction of the second flank is larger than the inclination angles in the axial direction of the cutting edge side flank and the proximal end flank, the drilling efficiency is improved. It is possible to realize a preferable drill bit which is high and is less likely to be broken at the outer diameter end portion.

  Further, in the drill bit, when one end located on the inner diameter side of each cutting edge is joined at the center of the tip of the bit, the rotation center can be easily positioned at the time of drilling and is stably rotated around the rotation center. This is a preferred drill bit.

Further, in the drill bit, the cutting edge part has a plurality of main cutting edge parts and a plurality of auxiliary cutting edge parts,
When the first flank and the second flank are formed on the main cutting edge, in addition to cutting or crushing by the main cutting edge, cutting or crushing by the sub cutting edge is performed. Therefore, a more efficient drill bit can be realized.

  In the drill bit, the secondary cutting edge portion is provided between the primary cutting edge portions adjacent to each other in the rotation direction, and the secondary cutting edge portion is circumferential with respect to the primary cutting edge portion located on both sides. If they are arranged at unequal intervals in the direction, holes with higher roundness can be drilled by vibration drilling.

  Further, in the drill bit, when the sub cutting edge portion is provided at a position retracted toward the base end side in the axial direction with respect to the main cutting edge portion, Since stones and the like can be further crushed by the auxiliary cutting edge portion, a drill bit with higher drilling efficiency is obtained.

Further, in the drill bit, the inner diameter end of the cutting edge of the auxiliary cutting edge portion is located at a position spaced from the center in the bottom view of the tip of the bit toward the outer periphery,
A line formed by connecting the inner diameter end of the cutting edge of the sub cutting edge portion and the center of the bit tip in the bottom view, and a rake face of the main cutting edge portion located adjacent to the rear side in the rotation direction The joint surface of which the boundary is defined by each line of the line connecting the valley line composed of the bond line and the inner diameter end of the cutting edge of the sub-cutting edge portion which is one end of the ridge line and the outer diameter end of the valley line, A configuration that is provided at a portion between two main cutting edge portions adjacent in the rotation direction and at an inner diameter side of a sub cutting edge portion disposed between the two main cutting edge portions. With this drill bit, the angle of the rake face of the main cutting edge can be made larger than the angle of the flank face, and a drill bit with high cutting and crushing ability can be realized.

  In the drill bit, if the material of the drill bit is a cemented carbide, it is preferable in terms of drilling performance and excellent in durability.

  Hereinafter, embodiments of a drill bit according to the present invention will be specifically described with reference to the drawings.

  1 is a bottom view showing a configuration of a main part (tip portion) of a drill bit according to an embodiment of the invention, FIG. 2 is a side view from the direction of arrows II-II in FIG. 1, and FIG. 3 is III in FIG. 4 is a side view from the direction of arrow IV-IV in FIG. 1, FIG. 5 is a side view from the direction of arrow V-V in FIG. 1, and FIG. It is a perspective view which shows the structure of the principal part of the drill bit shown in FIG.

  As shown in FIGS. 1 and 6, the tip portion 10 of the drill bit A according to this embodiment has a plurality of (three in this embodiment) cutting blade portions 1 arranged substantially radially in the circumferential direction. . Each of these cutting blade portions 1 has a rake face 2 formed on the front side in the rotation direction R during the drilling operation, and a flank 3 formed adjacent to the rake face 2 in the rear side in the rotation direction. And have. The rake face 2 and the flank face 3 are joined to form a ridge line 4 that forms a ridgeline. The joint ridge line 4 is located at the tip in the axial direction at each radial position of the drill bit A, and constitutes a cutting edge of the drill bit A.

  One end located on the inner diameter side of the three joining ridgelines 4 is joined at a center O1 in the bottom view of the drill bit A, and this center O1 becomes a rotation center in drilling work. However, if necessary, one end located on the inner diameter side of the three joining ridgelines 4 may be joined at the center of the bottom surface of the drill bit A via a so-called “chisel edge”.

  As shown in FIGS. 1 to 6, a first flank 3 </ b> A and an inner peripheral side (outer end) of the flank 3 of each of the three cutting blades 1 are arranged on the outer peripheral end (outer diameter end). A second flank 3B is provided on the inner diameter side. The first flank 3A and the second flank 3B are connected in a radial direction by a connecting surface 3C formed of a curved surface. However, the connecting surface 3C does not have to be a curved surface.

The first flank 3A has a cutting edge side flank 3a close to the cutting edge (joint ridgeline 4) and a proximal side flank 3b formed on the proximal side of the cutting edge side flank 3a.
In the case of this drill bit A, as shown in FIG. 7, the inclination angle α1 of the cutting edge side flank 3a in the axial direction is smaller than the inclination angle α2 of the base end flank 3b in the axial direction. It is configured.
In this embodiment, the inclination angle α3 (see FIG. 7) of the second flank 3B in the axial direction is the inclination of the blade edge flank 3a and the base end flank 3b in the axial direction. It is configured to be larger than the angles α1 and α2. However, the present invention is not limited to the above configuration, and the inclination angle α3 of the second flank 3B in the axial direction is configured to be at least larger than the inclination angle α1 of the cutting edge side flank 3a in the axial direction. Just do it. Accordingly, the inclination angle α3 of the second flank 3B in the axial direction may be equal to or smaller than each inclination angle α2 of the proximal end flank 3b in the axial direction. You can also.
Specifically, in the case of this drill bit for concrete (including stones and the like), the inclination angle α1 is about 23 degrees, the inclination angle α2 is about 45 degrees, and the inclination angle α3 is It is set to about 50 degrees. However, this inclination angle is appropriately set depending on the application, use conditions, material, and the like of the drill bit A.
As shown in FIGS. 1, 6, or 2 to 5, the second flank 3 </ b> B of the cutting edge portion 1 positioned forward in the rotational direction R and the rear thereof corresponding to the joining ridge line 4. The joint valley stripes 5 are formed radially from the rotation center O1 by the rake face 2 of the cutting edge portion 1 located adjacent to the cutting edge portion 1. Then, in the bottom view, the joint valley lines 5 and the joint lines 4 are alternately arranged radially in the rotation direction.
Further, in the proximal end portion from the second flank 3B to the connection surface 3C, the first flank 3A, the connection surface 3C, and the second flank 3B in the rotational direction are arranged. A rear adjustment surface 7 is formed so that the rear wall surface 6 is a surface that is continuous in the radial direction at the connection portion formed at the proximal end of the distal end portion 10 of the drill bit A.
Similarly, a front adjustment surface 9 is formed to connect the rake face 2 formed at an arbitrary angle of the cutting edge portion 1 and a front wall surface 8 in the rotational direction extending toward the rear end of the drill bit A. ing.

  In the case of this embodiment, the tip portion 10 of the drill bit A has the form of an integral block body. In the case of this embodiment, the tip portion 10 is made of cemented carbide. It is configured. However, it is needless to say that the tip 10 of the drill bit A can be made of a material other than cemented carbide.

  Further, although not shown, a discharge groove is formed around the proximal end (downward in FIGS. 2 to 5) of the distal end portion 10 of the drill bit A, and further, the proximal end toward the drill device side. The shaft portion of the drill bit in which the mounting portion (shank portion) is formed is fixed integrally.

And the drill bit A concerning the present Example comprised as mentioned above can show the following effects in a drilling operation.
That is, as described above, the inclination angle α1 of the cutting edge side flank 3a of the drill bit A in the axial direction is smaller than the inclination angle α2 of the base end flank 3b in the axial direction, that is, the Since the inclination angle α1 in the axial direction of the cutting edge side flank 3a is configured to be more obtuse than the inclination angle α2 in the axial direction of the base end flank 3b, an impact force acts in the drilling operation. However, it is difficult for the outer edge of the cutting edge to be lost.
In addition, since the inclination angle α3 of the second flank 3B and the inclination angle α2 of the base-side flank 3b of the first flank 3A are large, it is difficult for the cutting edge to be damaged. Nevertheless, the present drill bit A can exhibit high drilling performance.
Furthermore, since the inclination angle α3 of the second flank 3B can be increased, the junction valley 5 formed between the rake face 2 and the rear rake face 2 in the rotation direction R of the flank 3 is one. It is possible to configure the tip 10 with a simple line, and a joining surface that is necessary for a negative reason such as a conventional drill bit is not necessary. Therefore, the tip 10 is simpler than the conventional one. It can be.
In addition, the tip portion 10 of the drill bit A according to the present embodiment has a configuration in which relatively many surfaces are complicatedly combined as described above, but the tip portion 10 is formed in the form of an integral block body. Therefore, it becomes possible to manufacture with high production efficiency by casting or forging.

Next, another (second) embodiment of the present invention will be described with reference to FIGS. In the drawings, the same or corresponding components as those in the first embodiment are denoted by reference numerals obtained by adding 100 to the reference numerals in the first embodiment.
The drill bit A2 according to the second embodiment has a distal end portion 110 configured as follows. That means
In the second embodiment, a plurality (three in this second embodiment) of main cutting edge portions 101A are arranged in a radial direction in the rotation direction R, and between the adjacent main cutting edge portions 101A, 101A. Sub-cutting edge portions 101B are respectively formed. In this embodiment, a cutting edge portion is formed by the main cutting edge portion 101A and the auxiliary cutting edge portion 101B.
The auxiliary cutting edge portion 101B is provided at a position retracted from the distal end (center O1 in this embodiment) to the proximal end side as compared with the main cutting edge portion 101A. Therefore, the cutting edge (joint ridgeline 124) of the sub-cutting edge part 101B is disposed at a position retracted in the axial direction from the cutting edge (joint ridgeline 104) of the main cutting edge part 101A.
In this embodiment, the plural (three) main cutting edge portions 101A are provided at unequal intervals in the circumferential direction. The auxiliary cutting edge portions 101B are provided at equal intervals (120 degree intervals) in the circumferential direction.
Further, the auxiliary cutting edge portions 101B are arranged at unequal intervals with respect to the front and rear main cutting edge portions 101A adjacent in the rotation direction R. That is, each of the sub cutting edge portions 101B is adjacent to the space (arrangement angle) between the sub cutting edge portion 101B and the main cutting edge portion 101A adjacent to the front in the rotation direction R and the rear in the rotation direction R. It arrange | positions so that the space | interval (arrangement angle) between 101 A of main cutting blades may differ. However, instead of this embodiment, although not shown, the main cutting edge portions 101A are provided at equal intervals (120 degree intervals) in the circumferential direction, and are provided at unequal intervals in the circumferential direction of the auxiliary cutting edge portion 101B. In addition, the auxiliary cutting edge portion 101B may be arranged at unequal intervals with respect to the front and rear main cutting edge portions 101A adjacent in the rotation direction R. Alternatively, the main cutting edge portions 101A are provided at regular intervals (120 degree intervals) in the circumferential direction, and are provided at equal intervals (120 degree intervals) in the circumferential direction of the auxiliary cutting edge portions 101B. 101B may be arranged at unequal intervals with respect to the front and rear main cutting edge portions 101A adjacent in the rotation direction R.
The inner diameter end 124e of the cutting edge (joint ridgeline 124) of the sub-cutting edge portion 101B is located at a position away from the center O1 toward the outer periphery (outer diameter direction) in the bottom view of the bit tip.
And it is a site | part between the scoop surface 102 of the said main cutting edge part 101A, and the 2nd flank 103B of the main cutting edge part 101A located ahead in the rotation direction R, and the said sub cutting edge part 101B A joining surface 120 is formed at a portion on the inner diameter side of the cutting edge (joining ridgeline 124). In other words, the joining surface 120 includes a line 120a formed by connecting the inner diameter end of the cutting edge (joining ridgeline 124) of the sub cutting edge portion 101B and the center O1 in the bottom view of the tip of the bit, and the rotation direction. A trough consisting of a joining line 120b with the rake face 102 of the main cutting edge 101A located adjacent to the rear side, and a cutting edge (joining ridgeline 124) of the auxiliary cutting edge 101B serving as one end of the ridgeline 120a. The boundary is prescribed | regulated by each line of the line 120c which connects the inner-diameter end of this, and the outer-diameter end of a valley line (joining line 120b).

Thus, in this embodiment, the rake angle of the rake face 102 is sharper than the flank angle of the second flank face 103B of the main cutting edge 101A in an attempt to improve the cutting efficiency. Configured to be.
Further, as clearly shown in FIGS. 12 and 13, the cutting edge (joint ridge line 124) of the auxiliary cutting edge portion 101 </ b> B is bent toward the proximal side in the outer radial direction in the middle of the radial direction, Thus, the inclination angle toward the base end side of the cutting blade (joint ridge line 124) is a sharper angle at the portion 124A on the outer diameter side. In other words, the cutting edge (joint ridgeline 124) is configured so as to obtain a large crushing ability with an obtuse angle, specifically close to horizontal, at the inner diameter side portion 124B.

  Further, the main cutting edge portion 101A has basically the same configuration as the configuration of the cutting edge portion 1 (see FIG. 1) of the first embodiment. That is, the main cutting edge portion 101A has a rake face 102 formed on the front side in the rotation direction R in the drilling operation, and a flank 103 formed adjacent to the rake face 102 in the rear side in the rotation direction. And have. The rake face 102 and the flank face 103 are joined to form a joining ridgeline 104 that forms a ridgeline. The joining ridgeline 104 is located at the tip in the axial direction at each radial position of the drill bit A2, and constitutes a cutting edge of the main cutting edge portion 101A of the drill bit A2.

  One end located on the inner diameter side of the three joining ridge lines 104 is joined at a center O1 in the bottom view of the drill bit A, and this center O1 becomes a rotation center in drilling work.

  As shown in FIG. 8 to FIG. 14, the first flank 103 </ b> A at the outer peripheral end (outer diameter end) of each of the three flank surfaces 103 of the three main cutting edge portions 101 </ b> A and the inner peripheral side thereof A second flank 103B is provided on the (inner diameter side). The first flank 103A and the second flank 103B are connected in the radial direction by a connecting surface 103C made of a curved surface. However, the connection surface 103C is not necessarily a curved surface.

The first flank 103A includes a cutting edge side flank 103a close to the cutting edge (joint ridgeline 104) of the main cutting edge 101A, and a proximal flank formed on the proximal side of the cutting edge flank 103a. 103b.
In the case of the main cutting edge portion 101A of the drill bit A2, as shown in FIG. 14, as in the case of the cutting edge portion 1 shown in FIG. 7, the cutting edge side flank 103a is inclined in the axial direction. The angle α1 is configured to be smaller than the inclination angle α2 in the axial direction of the base end side flank 103b.
Further, in this embodiment, the inclination angle α3 (see FIG. 14) of the second flank 103B in the axial direction is the inclination of each of the blade edge flank 103a and the base end flank 103b in the axial direction. It is configured to be larger than the angles α1 and α2. However, the present invention is not limited to the above configuration, and the inclination angle α3 in the axial direction of the second flank 103B is configured to be at least larger than the inclination angle α1 in the axial direction of the cutting edge side flank 103a. Just do it. Therefore, the inclination angle α3 of the second flank 103B in the axial direction may be equal to or smaller than each inclination angle α2 of the base end flank 103b in the axial direction. You can also.
By the way, it is preferable that the inclination angle is basically the same as that in the first embodiment. However, this inclination angle is appropriately set depending on the application, use conditions, material, and the like of the drill bit A.

  Also in this embodiment, the tip portion 110 of the drill bit A2 has the form of an integral block body, and this tip portion 110 is made of cemented carbide in the case of this embodiment. It is constituted by. However, it is needless to say that the tip 110 of the drill bit A2 can be made of a material other than cemented carbide.

  Further, although not shown, a discharge groove is formed around the distal end portion (downward in FIGS. 8 and 10) of the distal end portion 110 of the drill bit A2, and further to the drill device side at the proximal end portion. The shaft portion of the drill bit in which the mounting portion (shank portion) is formed is fixed integrally.

  And, the drill bit A2 according to the present embodiment configured as described above has the same operational effects as the configuration of the first embodiment in the drilling operation, and the configuration unique to the second embodiment, Furthermore, the following effects can be achieved. That is, by providing the joint surface 120 at the position as described above, the rake angle of the rake face 102 is made sharper than the flank angle of the second flank face 103B of the main cutting edge 101A. The so-called drill bit bites well and high cutting efficiency can be obtained. In addition, since the auxiliary cutting edge portion 101B is provided as described above, it is possible to efficiently crush the work to be crushed by the main cutting edge portion 101A and to discharge it from the discharge groove to the outside of the drilling hole. It becomes.

  The present invention can be used for a drill bit that can be attached to a vibration drill device and drilled in stone or cement.

It is a bottom view which shows the structure of the principal part of the drill bit concerning one Example of this invention. It is a side view from the II-II arrow direction of FIG. It is a side view from the III-III arrow direction of FIG. It is a side view from the IV-IV arrow direction of FIG. It is a side view from the VV arrow direction of FIG. It is a perspective view which shows the structure of the principal part of the drill bit shown in FIGS. FIG. 7 is a view for illustrating the inclination angle of each flank face of the drill bit shown in FIGS. 1 to 6, and (a) is a side view as seen from the flank face orthogonal to the joining ridge line in the same view as FIG. 2; (A) is a partially enlarged view showing the inclination angles α1 and α2 of the flank as viewed from the direction of arrow VIIb-VIIb and viewed from the direction of the arrow Z (the direction of the joining ridge), and (c) is the VIIc- It is the elements on larger scale showing the inclination-angle (alpha) 3 of the flank which was cross-sectioned by VIIc arrow and seen from the Z direction. It is a perspective view which shows the structure of the principal part of the drill bit concerning another Example (Example 2). It is a bottom view which shows the structure of the principal part of the drill bit shown in FIG. It is a side view from the XX arrow direction of FIG. It is a side view from the XI-XI arrow direction of FIG. It is a side view from the XII-XII arrow direction of FIG. It is a side view from the XIII-XIII arrow direction of FIG. It is a figure for expressing the inclination angle of each flank of a drill bit shown in Drawing 8-Drawing 13, (a) is the same figure as Drawing 10, and is a side view seen from the flank side orthogonal to a joint ridgeline, (b) Is a partial enlarged view showing the inclination angles α1 and α2 of the flank as viewed from the direction of the arrow IXVb-IXVb in (a) and viewed from the direction of the Z arrow (the direction of the joining ridge), and (c) is the IXVc- It is the elements on larger scale showing the inclination-angle (alpha) 3 of the flank which was cross-sectioned by IXVc arrow and seen from the Z direction.

Explanation of symbols

A ... Drill bit
1 ... Cutting edge
2 ... Rake face
3 ... Flank
3A ... First flank
3B ... Second flank
3a ... Blade side flank
3b ... Base end flank
4 ... Joining ridgeline
α1 ... Inclination angle of the flank face
α2 ... Inclination angle of proximal flank

Claims (8)

A plurality of cutting blades are arranged in the circumferential direction, and the ridge line between the rake face and the flank formed on each cutting blade is used as a cutting blade, and one end on the inner diameter side of each cutting blade is viewed from the bottom of the bit tip. In a drill bit having a tip joined at the center in
At least one of the cutting blades has a first flank at the outer peripheral end, and a second flank having a different inclination angle from the first flank at the inner peripheral side ,
The first flank has a flank side flank near the cutting edge and a basal side flank formed on the base side of the flank side flank;
The drill bit, wherein an inclination angle in the axial direction of the cutting edge side flank is smaller than an inclination angle in the axial direction of the proximal end flank. The second flank is composed of a single plane having the same inclination angle in all portions, and the inclination angle in the axial direction of the second flank is such that the cutting edge side flank and the base end flank The drill bit according to claim 1, wherein the drill bit has a larger inclination angle in the axial direction of the surface.   The drill bit according to claim 1 or 2, wherein one end located on the inner diameter side of each cutting edge is joined at the center in the bottom view of the tip of the bit. The cutting blade portion has a plurality of main cutting blade portions and a plurality of sub cutting blade portions,
The drill bit according to claim 1, wherein the first flank and the second flank are formed on the main cutting edge.   The secondary cutting edge portions are provided between the primary cutting edge portions adjacent in the rotation direction, and the secondary cutting edge portions are arranged at unequal intervals in the circumferential direction with respect to the primary cutting edge portions located on both sides. The drill bit according to claim 4, wherein the drill bit is provided.   The drill according to claim 4 or 5, wherein the cutting edge of the auxiliary cutting edge portion is provided at a position retracted toward the base end side in the axial direction with respect to the cutting edge of the main cutting edge portion. bit. The inner diameter end of the cutting edge of the sub cutting edge portion is located at a position spaced from the center to the outer periphery in the bottom view of the tip of the bit,
A line formed by connecting the inner diameter end of the cutting edge of the sub cutting edge portion and the center of the bit tip in the bottom view, and a rake face of the main cutting edge portion located adjacent to the rear side in the rotation direction The joint surface of which the boundary is defined by each line of the line connecting the valley line composed of the bond line and the inner diameter end of the cutting edge of the sub-cutting edge portion which is one end of the ridge line and the outer diameter end of the valley line, It is a portion between two main cutting edge portions adjacent in the rotation direction, and is provided at a portion on the inner diameter side of the sub cutting edge portion disposed between these two main cutting edge portions. The drill bit according to claim 5.   The drill bit according to claim 1 or 4, wherein a material of the drill bit is cemented carbide.

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