KR100596473B1 - Core drill bit and cutting tip with taper in inner diameter - Google Patents

Abstract

The present invention relates to a core drill bit and a cutting tip used for drilling a workpiece into a relatively large diameter hole. The core drill bit and the cutting tip are used to cut a cutting load at the time of drilling a workpiece, And it is an object of the present invention to provide a core drill bit and a cutting tip that can smoothly remove a work material core when a drilling operation is completed. In order to achieve this object, the cutting tip of the core drill bit is thicker than the thickness of the end of the front side end of the cutting tip connected to the shank. In order to achieve the above object, a core drill bit includes a shank and the above-mentioned cutting tip, wherein an outer diameter of the front side of the cutting tip is equal to or larger than an outer diameter of a side connected to the shank, Is smaller than the inner diameter of the side connected to the shank.

Core drill, taper, diamond tool, abrasive grain, cutting path, initial cutting force

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core drill bit having a tapered inner diameter and a cutting tip,

FIG. 1A is a perspective view of a conventional core drill bit. FIG.

FIG. 1B is a longitudinal sectional view showing a state where the workpiece is drilled by using the conventional core drill bit shown in FIG. 1A; FIG.

FIG. 2A is a partially cutaway perspective view of a cutting tip of a core drill bit according to Embodiment 1 of the present invention; FIG.

FIG. 2B is a vertical cross-sectional view showing a state in which a drilled material is drilled using the core drill bit according to the first embodiment of the present invention shown in FIG. 2A. FIG.

3 is a view showing the progress of wear of a cutting tip according to the continuous use of a core drill bit according to Embodiment 1 of the present invention.

Figs. 4A and 4B are a partially cutaway perspective view and a longitudinal section of a cutting tip of a core drill bit according to a second embodiment of the present invention. Fig.

5A and 5B are a partially cutaway perspective view and a longitudinal sectional view of a cutting tip of a core drill bit according to a third embodiment of the present invention.

6 is a perspective view showing a detachable cutting tip and a ring-shaped cutting tip according to the shape of a cutting tip in a core drill bit according to the present invention;

Description of the Related Art

50: Workpiece

60: workpiece core

100, 200, 300: core drill bit

110, 210, 310: cutting tip

110a, 210a, 310a: front

110b, 210b1, 210b2, 210b3, 310b:

110c, 210c, 310c: outer surface

110d, 210d 310d: shank connection

120, 220, 330: shank

311: concave groove

The present invention relates to a core drill bit used for drilling a hole having a relatively large diameter in a workpiece and a cutting tip joined or formed thereon. More particularly, the present invention relates to a core drill bit used for drilling a workpiece core, Core drill bit and a cutting tip joined thereto or formed thereon.

FIG. 1A shows a conventional core drill bit 10, and FIG. 1B shows a longitudinal section of a state in which the workpiece 50 is drilled using such a conventional core drill bit. 1A and 1B, a conventional core drill bit 10 includes a cutting tip 11 for cutting a workpiece 50 and a core tip 10 for supporting the core tip and a core drill bit 10 And a shank 12 for mounting on the drill.

The front surface 11a of the cutting tip 11 of the core drill bit 10 and the front surface 11a of the core drill bit 10 at the initial stage of the work The cutting perforation operation is started by first contacting. Next, the core drill bit 10 is moved in the axial direction (longitudinal direction) simultaneously with the rotation, so that the core drill bit 10 is formed with the front face 11a of the cutting tip 11, The inner side surface 11b and the outer side surface 11c of the portion adjacent to the side surface 11c and particularly the front surface 11a come into contact with the workpiece 50 and participate in the cutting operation. Particularly, in order to cool the frictional heat generated between the workpiece 50 and the cutting tip 11 during the cutting operation of the hard material such as the stone, the reinforced concrete, the asphalt and the metal material, the cooling water is cut with the workpiece 50 and the workpiece core 60 It is common to work with a wet method of feeding between the tips 11. When the cutting operation is completed, a hole corresponding to the outer diameter of the cutting tip 11 is formed in the workpiece 50. At this time, a cylindrical workpiece core 60 having an outer diameter corresponding to the inner diameter of the cutting tip 11 remains at the inner diameter portion of the core drill bit 10, and after the workpiece core 60 is removed, do.

The thickness of the cutting tip is generally greater than the thickness of the shank so that a space is formed between the shank and the portion already cut in the workpiece 50 and the workpiece core 60 during cutting. A cutting chip is smoothly discharged between these spaces, and no friction is generated between the shank and the portion already cut in the workpiece 50 and the workpiece core 60, so that the cutting load at the time of cutting (cutting) is reduced. However, in the conventional conventional core drill bit 10, the inner diameter of the cutting tip 11 is formed to be a certain size along the longitudinal direction so that the portion already cut in the workpiece 50 and the workpiece core 60 during cutting, There is almost no space between the outer side surface 11c and the inner side surface 11b of the tip 11 so that the cutting chips can not easily be discharged therebetween and the contact area with the workpiece increases with the wear of the cutting tip Thereby increasing the cutting load. Moreover, the cooling water supplied between the workpiece 50 and the workpiece core 60 and the cutting tip 11 is not smoothly supplied and discharged therebetween, so that the cooling efficiency can not be improved. Further, in the conventional core drill bit 10, when the cutting is completed and the workpiece core 60 is removed, the workpiece core 60 and the inner side surface 11b of the cutting tip 11 are almost in contact with each other, So that the workpiece core 60 is not easily removed. Normally, the operation time is delayed because it is removed by using a driver or a hammer.

It is an object of the present invention to solve the problems of the prior art as described above, and it is an object of the present invention to reduce the cutting area by reducing the contact area of the inner surface during drilling of the workpiece, to secure the discharge passage of the chip, And to provide a core drill bit and a cutting tip with a prolonged life.

It is still another object of the present invention to provide a core drill bit and a cutting tip capable of smoothly removing a work material core when a drilling operation of a workpiece is completed, thereby shortening a continuous drilling operation time.

In order to achieve the above-described object, a cutting tip of a core drill bit according to the present invention has a thickness of a front side end portion of a cutting tip that is thicker than a thickness of an end portion connected to a shank.

The inner surface of the cutting tip may be linearly formed or formed in a stepped shape. In addition, concave grooves may be formed in front of these cutting tips along the rotational direction of the core drill bit.

The cutting tip of another aspect of the present invention includes a plurality of cutting tips described above, the ends of the cutting tips connected to the shank are ring-shaped connected to each other, and the outer diameter of the front side of the cutting tip is The inner diameter of the front side of the cutting tip is smaller than the inner diameter of the side connected to the shank.

In another aspect of the present invention, a core drill bit includes a shank and the above-mentioned cutting tip, wherein an outer diameter of the front side of the cutting tip is greater than or equal to an outer diameter of a side connected to the shank, Is smaller than the inner diameter of the side connected to the shank.

The shank and the cutting tip may be separately manufactured and joined. Alternatively, the cutting tip may be formed by attaching diamond abrasive grains to a part of the shank.

Hereinafter, the core drill bit and the cutting tip of the present invention will be described in detail with reference to the drawings.

(Example 1)

FIG. 2A is a perspective view showing a state in which a part of a cutting tip 110 of a core drill bit 100 according to the first embodiment of the present invention is cut, and FIG. 2B is a perspective view showing a state where a workpiece 50 ) Are perforated in the longitudinal direction. The outer diameter of the cutting tip 110 of the core drill bit 100 of the present embodiment is constant along the axial direction of the core drill bit 100. The inner diameter of the cutting tip 110 is, As shown, it can be seen that a taper is formed not constant along the axial direction. That is, the inner diameter at the front surface 110a of the cutting tip 110, which is initially in contact with the workpiece 50 during the drilling operation, is the opposite side of the front surface of the cutting tip 110, The taper is formed so as to be smaller than the inner diameter of the shank connecting portion 110d. This is because when the cutting tip 110 alone is viewed individually, the thickness of the end portion of the cutting tip 110 on the front surface 110a side is designed to be thicker than the thickness of the end portion on the shank connecting portion 110d side. At this time, the inner diameter of the cutting tip 110 at the front surface 110a and the inner diameter at the shank connecting portion 110d are preferably 2 mm to 2.4 mm.

When drilling the workpiece 50 with the core drill bit 100 of the present embodiment designed as described above, the front surface 110a of the cutting tip 110 first contacts the surface of the workpiece 50 at the beginning of the work, / RTI > Next, the core drill bit 100 moves in the axial direction (longitudinal direction) at the same time as the core drill bit 100 is rotated, so that the cutting tip 110 of the core drill bit 100 is brought into contact with the front face 110a, The front inner side portion 110ab that meets the outer side surface 110b and the front side outer portion 110ac that meets the outer side surface 110c participate most in the cutting operation. The outer surface 110c of the cutting tip 110 also contacts with the inner diameter side of the hole of the already cut workpiece 50 to some extent in the cutting operation. However, since the inner diameter at the front surface 110a of the cutting tip 110 is smaller than the inner diameter at the shank connecting portion 110d of the cutting tip 110, the front inner surface 110ab adjacent to the front surface 110a of the cutting tip 110, A space is formed between the inner side surface 110b and the portion of the work material core 60. [ Therefore, the inner side surface 110b of the cutting tip 110 and the workpiece core 60 are not in contact with each other, so that the inner side surface 110b is not involved in the cutting operation. (Accordingly, the cutting tip 110 mainly wears in the front surface 110a, the front inner side portion 110ab, and the front side outer portion 110ac, which will be described below again with reference to Fig. 3).

As described above, since the cutting chips generated due to the cutting are smoothly discharged between the inner side surface 110b and the space formed between the portion of the workpiece core 60 already cut and the friction is not generated therebetween, do. Particularly, when cooling water is supplied between the workpiece 50 and the cutting tip 110 at the time of cutting the workpiece 50 such as a hard material such as stone, reinforced concrete, asphalt or metal, And acts as an exhaust passage to improve the cooling efficiency. Further, after the drilling operation is completed, the workpiece core 60 comes into contact with the front inner side portion 110ab of the cutting tip 110, and a space (not shown) is formed between the workpiece core 60 and the inner side surface 110b of the cutting tip 110 . Therefore, after the drilling operation is completed, it is easy to remove the workpiece core 60 from the core drill bit 100 by using the space. In FIG. 2B, a space formed between the workpiece core 60 and the inner surface 110b of the cutting tip 110 is well shown. (However, it is described below that the workpiece core 60 is not shown in parallel to Fig. 1B).

FIG. 3 shows the progress of wear of the cutting tip 110 due to continuous use of the core drill bit 100. FIG. 3 shows that the portion drawn in the circle III in FIG. 2A, which is partially cut away from the cutting tip 110 portion of the core drill bit 100, is changed by wear. 3 (a) shows a cutting tip 110 of a core drill bit 100 of a new product which has not yet been drilled, FIG. 3 (b) shows a case where a drilling operation is performed several times, The drilling operation is performed several times so that the upper portion of the cutting tip 110 is worn by about half. As mentioned above, during the drilling operation of the workpiece 50, the front portion 110a, the front inner portion 110ab, and the front outer portion 110ac of the cutting tip 110 mainly participate in the cutting operation. 3, as the height of the cutting tip 110 decreases, a large amount of abrasion occurs in the front inner side portion 110ab and the front side outer portion 110ac. As a result, the cutting tip 110 is abraded, (110) has a rounded front surface, and its height is lowered.

As described above, when the cutting tip 110 of the core drill bit 100 is worn, the outer diameter of the cutting tip 110 keeps the initial value, but the inner diameter of the cutting tip 110 gradually increases. However, since the inner diameter at the front face 110a of the core drill bit 100 is still smaller than the inner diameter at the shank connection portion 110d even when the wear of the cutting tip 110 progresses, Friction is not generated between the cutting tip 110 and the workpiece core 60 so that the cutting load is reduced and the supply and discharge passage of the cooling water is secured and the cooling efficiency is improved.

Further, during the cutting operation of the hard material, as the core drill bit 100 advances in the thickness direction of the workpiece 50, the front face 110a, the front inner side portion 110ab and the front side outer side 110ac of the cutting tip 110 Wear occurs somewhat. Accordingly, there is no change in the inner diameter of the perforation hole of the workpiece 50 to be cut during the cutting (drilling) operation. However, in accordance with the wear of the front inner side portion 110ab, The inner diameter of the workpiece core 110 increases, and the outer diameter of the workpiece core 60 gradually increases. FIG. 2B shows such a cutting behavior (although the workpiece core 60 is slightly exaggerated), as shown in FIG. 2B, the outer diameter of the workpiece core 60 gradually increases as the drilling operation progresses. That is, the final outer diameter (outer diameter at the front surface 110a side of the cutting tip) is larger than the initial outer diameter of the workpiece core 60 (the outer diameter at the shank connection portion 110d side of the cutting tip). Therefore, after the drilling operation is completed, the workpiece core 60 is in contact with the front inner side portion 110ab of the cutting tip 110 and between the workpiece core 60 and the inner side surface 110b of the cutting tip 110 The space to be formed is formed larger on the side of the shank connection portion 110d, so that the workpiece core 60 can be more easily removed.

In the core drill bit 100 of the present embodiment, the cutting tip 110 has an outer diameter uniformly formed along the axial direction of the core drill bit 100, but the outer diameter of the cutting tip 110 at the front surface 110a, And may be designed to have a taper larger than the outer diameter at the connecting portion 110d. In this case, a space is formed between the outer surface 110c of the cutting tip 110 and the inner diameter portion of the hole formed in the workpiece 60 during the drilling process of the workpiece 60 so that they are not in contact with each other, The cutting load is reduced and the supplying and discharging passage of the cooling water is ensured and the cooling efficiency is improved. As a result, the workpiece core 60 is prevented from being damaged, Removal is facilitated. In the core drill bit in the following embodiments, the cutting tip is shown and described as having an outer diameter uniformly formed along the axial direction of the core drill bit, but the present invention is not limited thereto.

(Example 2)

The cutting tip 110 of the core drill bit 100 of the above-described first embodiment has a shape in which the inner side surface 110b is linearly tapered, but the core drill bit of the present invention is not limited thereto. 4A and 4B show a core drill bit 200 according to the present embodiment in which the inner surfaces 210b1, 210b2 and 210b3 of the cutting tip 210 are formed in a stepped shape. Fig. 4A is a perspective view showing a state in which a part of the cutting tip 210 of the core drill bit 200 is cut, and Fig. 4B is a longitudinal sectional view of such a core drill bit. The basic operation of this embodiment is similar to the above-described embodiment, but has the following differences.

That is, since the inner surfaces 210b1, 210b2, and 210b3 of the cutting tip 200 are formed in a stepped shape, the core drill bit 200 of the present embodiment is formed in such a manner that, during the drilling operation of the workpiece 50, Only the inner side surface 210b1 contacts with the workpiece core 60 and the remaining inner side surfaces 210b2 and 210b3 form a certain space with respect to the workpiece core 60. [ Therefore, when drilling the workpiece 50 with the core drill bit 100 of the first embodiment, the inner surface 110b of the cutting tip 100 is hardly in contact with the workpiece core 60, The core drill bit 200 of the present embodiment is less likely to be cut than the core drill bit 100 of the first embodiment because the inner side surface 210b1 of the core drill bit 200 maintains contact with the workpiece core 60. [ The load is increased. However, in the core drill bit 200 of the present embodiment, the contact area between the inner surface of the cutting tip and the workpiece core 60 is reduced as compared with the conventional core drill bit, so the cutting load is reduced as compared with the core drill bit . On the other hand, the core drill bit 200 of the present embodiment has a greater distance between the inner side surface and the workpiece core 60 than the core drill bit 100 of the first embodiment, So that cutting and cooling efficiency can be improved.

(Example 3)

The core drill bit 300 of the present embodiment shown in Figs. 5A and 5B has a concave groove 311 formed in the front face 310a of the cutting tip 310 along the circumferential direction of the core drill bit 300 The same as Example 1 except for the following. Therefore, the operation is also the same as that of the first embodiment except for the following points.

That is, since the recessed groove 311 is formed along the circumferential direction in the cutting tip of the core drill bit 300 of this embodiment, the discharge of the cutting chip and the supply and discharge of the cooling water are smoothly performed along the concave groove 311 It becomes. The area of the front surface 310a of the cutting tip 310 is reduced due to the formation of the concave groove 311 so that the area of friction with the workpiece 50 decreases at the beginning of the drilling of the workpiece 50, The initial cutting force is improved. 5A and 5B, the cross-section of the concave groove 311 of this embodiment is shown as a V shape, but the shape thereof is not limited to this, and may be U or W shape. Other operations and effects of the concave groove 311 are described in Korean Patent Application No. 10-2004-0025962 filed on April 21, 2004 under the name of "diamond tool with concave groove" .

The core drill bit and the cutting tip according to the present invention have been described only in terms of the shape and the action thereof, and the core drill bit and the manufacturing method thereof are not mentioned, And can be produced by a commonly used material and method. That is, the cutting tip of the core drill bit of the present invention can be made of carbon tool steel, cemented carbide, diamond or the like depending on the use place, that is, the kind of the workpiece, and the manufacturing method can be appropriately selected accordingly.

For example, diamond core drill bits commonly used for cutting hard materials such as stone, reinforced concrete, asphalt, and metal materials include artificial and natural diamonds, cubic boron nitride (cBN), silicone carbide ) And alumina is generally attached to a shank made of a metal material such as stainless steel or carbon steel. At this time, the method of joining the grindstone made of diamond abrasive to the shank can be roughly classified into a sintering tip welding method (hereinafter referred to as sintering method), electroplating method, and a brazing method. In the sintering method, the binder metal and the abrasive grains are preliminarily mixed, pressed and sintered, and then the sintering tip is bonded to the shank using an adhesive, silver solder fusion, laser welding, or resistance welding. In the electrodeposition method, the abrasive grains are attached to the shanks using a binder such as nickel by wet electroplating. In the fusion welding method, a liquid paste in which a binder metal and a binder are mixed is applied to a shank, and then the abrasive grains are dispersed. .

Generally, the sintering method is a method in which a sintering tip is separately prepared as a cutting tip and is bonded to a shank, or a fusing method or an electrodeposition method is a method of directly forming abrasive grains on a shank to form a cutting tip.

However, by applying the sintering method, only the cutting tip having the same shape as the sintering tip can be separately manufactured by the fusion welding or electrodeposition method, and then the core drilling bit can be manufactured by joining the cutting tip to the shank by laser welding, resistance welding, silver solder fusion or the like. Reference may be made to Korean Patent Application No. 10-2004-0015192, filed March 5, 2004, entitled " Diamond Tool with Tip and Method of Manufacturing the Same ". Also in the sintering method, as in the simultaneous pressure sintering method, there is a method in which a shank is placed on a mold, a powder mixed with a metal binder and a diamond abrasive is filled in a mold, and the metal binder and abrasive grains are pressed and sintered together with a shank to produce a diamond tool .

Therefore, in the case of manufacturing the core drill bit of the present invention using diamond, the cutting tip and the shank may be separately manufactured and joined together, or the diamond tip may be directly attached to the shank to form the cutting tip.

When the cutting tip is separately manufactured by the sintering method, the fusing method, or the electrodeposition method and attached to the shank, the cutting tip is divided into the separation type cutting tip and the ring type cutting tip depending on the shape thereof. 6 is a detachable cutting tip having a plurality of cutting tips 610a attached to a shank 620b. Since the size of the cutting tip is small, it is easy to manufacture individual tips. On the other hand, in order to achieve the above- 620b may be somewhat difficult. The cutting tips of FIGS. 2A, 4A, and 5A according to the first to third embodiments described above are ring-shaped cutting tips in which the lower ends of the plurality of cutting tips shown in FIG. 6 are all connected to form a ring. The cutting tips 110, 210, and 310 shown in the above-described embodiments are larger in size than the cutting tips 610a shown in FIG. 6A. However, since the shape of the cutting tips 110, 210, and 310 has the structure of the present invention described above, ). Therefore, it is preferable that the separable cutting tip 610a shown in Fig. 6 is used for the large-diameter core drill bit, and the ring-shaped cutting tips 110, 210 and 310 shown in Figs. 2A, 4A, It is preferable to be used for a drill bit. A detailed description of the shape of the cutting tip of these core drill bit is also given in Korean Patent Application No. 10-2004-0015192 filed on March 5, 2004, entitled " You may refer to the

As described above, the core drill bit of the present invention may be manufactured by using not only diamond but also carbon tool steel or cemented carbide.

The core drill bit manufactured in accordance with the above-described structure of the present invention is advantageous in that cutting chips generated due to cutting are smoothly discharged between the inner surface of the cutting tip and the space between the workpiece core portion already cut, So that the cutting load is reduced during drilling. Particularly, when drilling a hard material such as a stone or a metal material, the space between the workpiece core and the inner surface of the cutting tip acts as a supply and discharge passage for the cooling water, thereby improving the cooling efficiency. Such an improvement in cutting performance leads to a longer service life of the tool. Moreover, after the drilling operation is completed, it is quick to remove the workpiece core from the core drill bit, thereby shortening the time required for the next drilling operation.

Claims (10)

As a cutting tip of a core drill bit, The thickness of the front side end portion of the cutting tip is thicker than the thickness of the end portion connected to the shank, Wherein a cut groove is formed in a front surface of the cutting tip along a rotational direction of the core drill bit. The cutting tip according to claim 1, wherein the inner surface of the cutting tip is linearly formed. The cutting tip according to claim 1, wherein the inner surface of the cutting tip is formed in a stepped shape. delete A cutting tool comprising a plurality of cutting tips according to any one of claims 1 to 3, The ends of the cutting tips connected to the shanks are ring-shaped connected to each other, Wherein the outer diameter of the front side of the cutting tip is greater than or equal to the outer diameter of the side connected to the shank and the inner diameter of the front side of the cutting tip is smaller than the inner diameter of the side connected to the shank. delete As a core drill bit, The shank, A cutting tool, comprising a cutting tip according to any one of claims 1 to 3, Wherein the outer diameter of the front side of the cutting tip is greater than or equal to the outer diameter of the side connected to the shank and the inner diameter of the front side of the cutting tip is smaller than the inner diameter of the side connected to the shank. delete The core drill bit according to claim 7, wherein the shank and the cutting tip are separately manufactured and joined. The core drill bit according to claim 7, wherein the cutting tip is formed by attaching diamond abrasive grains to a part of the shank.

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