JP2011240446A - Drill bit and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill bit where a drilling service life is improved and the drilling accuracy of a drilling hole is improved, and to provide a method for manufacturing the same.SOLUTION: In the method for manufacturing the drill bit including a columned or cylindrical metal body, the tip of the metal body is immersed in a liquid brazing material and pulled out (31), diamond abrasive grains are made to adhere to the applied brazing material (33), and the outer circumferential side face and the tip face of the brazing material to which the diamond grains adhere are pressed to dies to be shaped, and thereafter sintered to manufacture a drilling blade (35, 36, 38). In a shaping process, the outer circumferential side face of the drilling blade is shaped by rotating the metal body while pressing the outer circumferential side face of the brazing material to the curved concave die, and the tip face of the drilling blade is nearly evenly shaped by pressing the tip face of the brazing material to the planar die.

Description

  The present invention relates to a drill bit using diamond used for drilling concrete, hard tile, and the like, and a method for manufacturing the drill bit.

  Conventionally, drill bits using diamond used for drilling concrete, mortar, tile, etc., have a core shape used for drilling large diameter holes and a non-core shape used for drilling small diameter holes. The perforating blade is formed of a sintered body of diamond abrasive grains and metal powder. The volume content of the diamond abrasive contained in the drilling blade is often set to a content of about 5 to 15 Vol% in order to maintain the holding power of the diamond abrasive and the strength of the drilling blade. Usually, when the diamond content is low, the sharpness is inferior, and it is difficult to drill only by rotating the bit to drill into concrete etc. Therefore, the vibration drill that gives vibration action in addition to the rotation action, and the hammer drill that gives impact action It was often used by attaching to a dedicated electric tool. In that case, it was accompanied by noise caused by vibration and impact.

  On the other hand, according to Patent Document 1, a single slit is provided at the tip of the metal body of the drill bit, and a diamond abrasive grain is fixed by melting a brazing alloy (brazing material) on the outer peripheral surface and the tip surface of the metal body. A drill bit adapted to be welded is disclosed. This drill bit can be easily operated by simply mounting it on a normal drill without using cooling water or other machining fluids when drilling holes in hard and brittle materials such as concrete and stone. can do.

JP 2000-108117 A

  FIG. 10 is a view showing the shape of the drilling blade 103 in the conventional drill bit 101. The drilling blade 103 is mainly composed of a brazing material 104 and diamond abrasive grains 105. First, the brazing material 104 is applied by immersing the tip of the columnar or cylindrical body 102 in a liquid brazing material. The tip portion of the body 102 after application of the brazing filler metal 104 often has a dripped drop-like shape that can be formed when it is dipped and pulled up. Thereafter, the diamond abrasive grains 105 are adhered to the drop-shaped brazing material 104 by a method such as sprinkling. As shown in FIG. 10, the shape after the adhesion is a shape in which diamond abrasive grains 105 are scattered on the outer peripheral surface of the dripped brazing filler metal. For convenience of explanation, FIG. 10 shows that the diamond abrasive grains 105 are sparsely attached, but in practice, as many diamond abrasive grains 105 as possible are attached to the brazing material. Then, after sufficiently brazing the brazing material 104, the diamond abrasive grains 105 are fixed to the body 102 by the brazing material 104 by heating at a high temperature in a vacuum atmosphere or a reducing gas atmosphere furnace (welding step).

  As described above, in the conventional drill bit 101, the shape of the drilling blade 103 formed at the tip of the body 102 is often in the form of a drop, and the protrusion protruding like the portion of the arrow 108a on the outer peripheral side surface of the tip. In some cases, the convex portion protruding near the center of the tip surface (lower surface), such as the portion indicated by the arrow 108b or the portion indicated by the arrow 108b, may largely protrude outward from the brazing material after welding.

  In the conventional drill bit described above, when the drilling blade 103 having convex portions on the outer peripheral side surface and the front end surface is used, stress is concentrated on the convex portions during drilling. Therefore, the part of the arrows 108a and 108b is missing. “To be chipped” means, for example, that the diamond abrasive grains 105 fall off or the brazing material 104 is lost. Thus, when the convex part is formed in the front end surface or the outer peripheral side surface of the drilling blade 103, chipping due to stress concentration occurs at the time of drilling work, and the drilling life of the drill bit is shortened. Moreover, since the convex part which has the outer peripheral side surface and end surface of the drilling blade 103 causes the accuracy of the drilling diameter to deteriorate, it has been desired to manufacture a drill bit so that the convex part is not generated as much as possible.

  The present invention has been made in view of the above background, and an object thereof is to realize a drill bit that can improve the drilling life and a method of manufacturing the drill bit.

  Another object of the present invention is to realize a drill bit capable of improving the drilling accuracy of a hole and a method for manufacturing the same.

  Still another object of the present invention is to realize a drill bit in which diamond abrasive grains are arranged so as to improve drilling efficiency (drilling performance) and a manufacturing method thereof.

  The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.

  According to one aspect of the present invention, in a drill bit manufacturing method for forming a drilling blade by fixing diamond abrasive grains to a tip of a columnar or cylindrical metal body with a brazing material, the tip of the metal body is liquid. Immerse it in a brazing filler metal and draw it out, attach diamond abrasive grains to the applied brazing filler metal, and press the outer peripheral side and tip of the brazing filler metal with diamond abrasive grains against the mold to shape it into a cylindrical or cylindrical shape. did. After shaping the drilling blade, the drilling blade is sintered.

   According to another feature of the present invention, the outer peripheral side surface of the brazing material is shaped into a substantially cylindrical shape by rotating the metal body while pressing the outer peripheral side surface of the drilling blade against the curved concave mold. Furthermore, the outer peripheral side surface of the drilling blade is pressed against a flat mold, and the tip surface of the brazing material is shaped substantially flat.

  According to still another aspect of the present invention, the shaping diamond abrasive grains having an average grain size that is 1/2 to 1 times the average grain diameter of the diamond abrasive grains are applied to the surface on which the planar mold brazing material is pressed. A front end surface of the brazing material is shaped using a surface provided with a large number of diamond grains for shaping.

  According to still another feature of the present invention, the metal body is cylindrical, the drilling blade is provided in an opening of the cylindrical metal body, and the inner peripheral portion of the drilling blade is provided with a cylindrical convex portion in the center. The inner peripheral part of the drilling blade is shaped by pressing against the convex part of the mold.

  According to the first aspect of the present invention, the diamond abrasive grains are adhered to the liquid brazing material, and the outer peripheral side surface and the tip surface of the brazing material to which the diamond abrasive grains are adhered are pressed against the mold and then sintered, so that the drilling blade It is possible to shape the shape of the brazing material having no convex portions on the outer peripheral side surface and the front end surface thereof, eliminate the convex portions that have been chipped due to concentration of stress during drilling, and realize a drill bit with few chips during cutting.

  According to the invention of claim 2, since the drilling blade is shaped into a cylindrical shape or a columnar shape, the drilling blade having a shape having no convex portions on the outer peripheral side surface and the front end surface is formed in both the drill bits of the non-core type and the core type. be able to.

  According to the invention of claim 3, since the outer peripheral side surface of the brazing material is shaped by rotating the metal body while pressing the outer peripheral side surface of the drilling blade against the curved concave mold, the shape has a high cylindricity and a high core circularity. It can be shaped, and a shape with few protrusions protruding on the outer peripheral side surface of the drilling blade can be realized. Further, since the applied diamond abrasive grains are brought into contact with the body surface by the pressing force, it is possible to realize a drill bit in which the protruding heights of the diamond abrasive grains are uniform.

  According to invention of Claim 4, the outer peripheral side surface of a piercing | blade blade can be pressed on a planar type | mold, the front end surface of a brazing material can be shaped, and it can be set as the shape with few convex parts which protrude on the front end surface of a perforation blade. it can. Moreover, since the entire diamond abrasive grains on the tip surface of the drilling blade come into contact with the work material such as concrete evenly during drilling work, it has the effect of suppressing uneven wear of the diamond abrasive grains and extending the drilling life. .

  According to the invention of claim 5, since the front end surface of the brazing material is shaped using the surface provided with the shaping diamond abrasive grains, when the front end surface of the brazing material is pressed and shaped, Since the flat surfaces are aligned outward, the diamond abrasive grains can be slightly rotated, the corners of the diamond abrasive grains can be directed outward to form a sharp cutting edge, and the sharpness can be improved.

  According to the invention of claim 6, the inner peripheral part of the drilling blade is shaped by pressing the inner peripheral part of the drilling blade against the convex part of the mold having a cylindrical convex part at the center. The inner peripheral surface can be shaped into a good shape.

  According to the seventh aspect of the present invention, since the drill bit manufactured by the method according to any one of the first to sixth aspects can be realized, it is possible to provide a drill bit having good durability and good piercing properties.

  According to the invention of claim 8, the metal body is rotated while pressing the outer peripheral side surface of the drilling blade against the curved concave mold, and the outer peripheral side surface of the brazing material is shaped. It is possible to provide a drill bit that can be shaped and has a drilling blade shape with few projections protruding on the outer peripheral side surface of the drilling blade.

  According to invention of Claim 9, it can be set as the shape with few convex parts which protrude on the front end surface of a drilling blade, and can provide the drill bit which has favorable drilling performance.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

FIG. 1 is a flowchart showing a manufacturing procedure of a drill bit according to an embodiment of the present invention. It is a figure which shows the method to make the diamond abrasive grain adhere to the drilling blade 3 which concerns on the Example of this invention. It is the schematic explaining the process shape | molded, pressing the outer peripheral side surface of the punching blade 3 which concerns on the Example of this invention against the curved concave shape type | mold 21. FIG. It is the schematic explaining the process of shaping, pressing the front end surface of the punching blade 3 which concerns on the Example of this invention against the planar type | mold 31. FIG. It is the schematic explaining the process of shaping, pressing the front end surface of the punching blade 3 which concerns on the Example of this invention against the planar type | mold 41. FIG. It is a front view of the core-shaped drill bit 51 which concerns on the 2nd Example of this invention. It is sectional drawing of the core-shaped drill bit 51 which concerns on the 2nd Example of this invention. It is the schematic explaining the process of shaping while pressing the internal peripheral surface of the punching blade 3 which concerns on the 3rd Example of this invention to the type | mold 81 which has a cylindrical convex part in the center. 1 is a front view of a drill bit 1 according to an embodiment of the present invention. It is sectional drawing of the drilling blade 103 part of the drill bit 101 by a prior art.

  Embodiments of the present invention will be described below with reference to the drawings. In the present specification, description will be made assuming that the vertical direction of a single drill bit is the direction shown in FIG.

  First, the overall configuration of the non-core type drill bit 1 according to the present embodiment will be described with reference to FIG. The members constituting the drill bit 1 are a metal body 2 constituting a cylindrical base portion, a mounting portion 10 formed on the rear end side, and a disc shape formed between the body 2 and the mounting portion 10. And a perforating blade 3 provided at the tip of the body 2. The mounting portion 10 is a so-called hexagonal shaft having a hexagonal cross section for mounting to a power tool as a driving source. For example, the drill bit 1 is used as a hexagonal mounting port of a driving tool such as an electric drill, impact driver, hammer drill, or the like. Can be installed. The distance between opposite sides symmetrical to the hexagonal central axis is, for example, 6.35 mm, and the axial length (vertical length) is about 30 mm. Further, a recess 11 that is continuous in the circumferential direction is formed in the vicinity of the center of the mounting portion 10 in the axial direction (vertical direction) so that a ball of a so-called one-touch mounting mechanism such as an impact driver can be fitted. The diameter of the finest detail of the hollow part 11 is 5 mm, for example.

  The brim 12 serves to reduce dust generated during drilling work from directly scattering to a power tool such as an impact tool or an operator (not shown) and to the diameter of the body 2 and the mounting part 10. Have a large diameter. The diameter of the body 2 is determined by the size of the hole in the work material. For example, drill bits 1 of various sizes are provided from a diameter of about 5 mm to a large-diameter body 2 having a diameter of 40 mm or more. In the drilling operation, it is preferable to rotate the drill bit 1 at a low speed, for example, about 1,000 to 3,000 revolutions per minute.

  The perforating blade 3 has, for example, a single layer structure in which abrasive grains are arranged and welded in a single layer. A spiral projection 13 is formed on the side surface of the body 2. The helical protrusion 13 is preferably configured integrally with the body 2. The direction of the helix is the rotation direction that draws cutting powder to the rear end side (upper side) with respect to the rotation direction in the same manner as a normal drill blade. The method of manufacturing the protrusion 13 is manufactured by cutting out the protrusion 13 from the cylindrical body 2 having a thickness larger than a predetermined thickness so as to leave a portion of the protrusion 13. It should be noted that the outer diameter of the protrusion 13 is preferably slightly smaller than the outer diameter (cutting diameter) of the drilling blade 3.

  Next, the manufacturing procedure of the drill bit 1 will be described with reference to the flowchart of FIG. In manufacturing the drill bit 1, first, the mounting portion 10 of the drill bit 1 and the body 2 are machined using a known processing method (step 31). The attachment portion 10 and the body 2 of the drill bit 1 are made of, for example, an iron-based alloy, and are formed into a shape in which the drilling blade 3 is not attached in the drill bit 1 shown in FIG. 9 by machining. Next, a base coat for protection such as rust prevention treatment is applied to the entire machined material (step 32).

  Next, after the applied base paint is sufficiently dried, the tip (lower end) of the body 2 of the drill bit 1 is dipped in a liquid brazing material (brazing material paste) placed in a container such as a beaker and then pulled up. (Step 33). As the brazing material, commercially available brazing materials such as so-called “silver brazing”, “copper brazing”, and “nickel brazing” can be used. The brazing material 4 can be easily attached to the body 2 by immersing the brazing material in the tip portion of the body 2 and pulling up the body 2. By attaching the brazing material 4 in this manner, a predetermined amount of the brazing material 4 can be applied to the front end portion of the metal body 2 without being left uncoated.

  Next, the drill bit 1 is turned upside down and inverted to sprinkle the diamond abrasive grains from above, thereby attaching the diamond abrasive grains to the surface of the brazing material applied to the tip (lower end) of the body 2 (step 34). ). The time from the end of step 33 until the diamond abrasive grains are attached in step 34 is, for example, about 30 to 60 seconds. FIG. 2 is a diagram showing a method of attaching diamond abrasive grains. Here, the body 2 is turned upside down and turned upside down, and is dropped as indicated by an arrow 20 so as to sprinkle a large number of diamond abrasive grains 5 from above, thereby attaching the diamond abrasive grains 5 to the brazing material 4. At this time, it is important that the diamond abrasive grains 5 are evenly adhered to the brazing material 4 by tilting or rotating the body 2 not in an upright state but at an angle. In this sprinkling step, it is sufficient to simply drop the diamond abrasive grains 5 by gravity, but in addition, the diamond abrasive grains 5 may be attached to the diamond abrasive grains 5 at a predetermined speed. You may adhere by the method.

  Next, after sprinkling the diamond abrasive grains 5, the process proceeds to the first shaping step. In this state, the body 2 is laid sideways, and the body 2 is rotated while pressing the outer peripheral side surface of the punching blade 3 against the curved concave mold 21 (step 35). FIG. 3 is a schematic diagram illustrating a process of shaping the outer peripheral side surface of the punching blade 3 while pressing it against the curved concave mold 21. The upper surface of the mold 21 is formed into a curved surface having a predetermined curvature in the direction perpendicular to the axial direction. Therefore, the sides 21a and 21c perpendicular to the axial direction of the upper surface are curved, and the sides 21b and 21d parallel to the axial direction of the upper surface are straight lines. Using such a mold 21, the body 2 is rotated while being moved in the direction of the arrow 23 or in the direction opposite to the arrow 23 while pressing the body 2 in the direction of the arrow 22 with a predetermined force. The number of rotations may be one or more. Thus, by shaping the punching blade 3 by pressing and rotating the curved concave mold 21, the outer peripheral side surface of the dripping-shaped drilling blade 3 can be shaped into a substantially cylindrical shape. It can be shaped into a shape with a high degree of cylindricity and core. As a result, it is possible to eliminate the large convex portion as seen on the outer peripheral side surface of the drilling blade in the conventional example, and to greatly suppress the chipping caused by stress concentration on a part of the drilling blade 3. it can.

  In addition, the applied diamond abrasive grains 5 come into contact with the surface of the body 2 by the pressing force in the direction of the arrow 22, and the protruding height of the diamond abrasive grains 5 is made uniform, so that the entire diamond abrasive grains 5 are perforated during the drilling operation. Contact evenly with work materials such as concrete. As a result, uneven wear of the diamond abrasive grains 5 can be suppressed, the drilling life of the drilling blade 3 can be greatly extended, and the drilling diameter accuracy can be maintained for a long time.

  Next, it progresses to a 2nd shaping process, and the front end surface (lower end surface) of the perforation blade 3 is shaped (step 36). FIG. 4 is a schematic diagram illustrating a process of shaping the tip surface of the punching blade 3 according to the present invention while pressing it against the flat mold 31. After shaping the outer peripheral side surface of the drilling blade 3 as shown in FIG. 3, the blade tip surface of the drilling blade 3 is shaped using a flat die 31. The planar die 31 is a flat plate made of, for example, an iron-based alloy or an aluminum-based alloy, and the upper surface 31a and the lower surface 31b are flat. Using such a mold 31, the body 2 is pressed against the planar mold 31 in the direction of the arrow 24 to shape the tip surface of the drilling blade 3 so as to be substantially flat. Thereby, it becomes a shape without the convex part (for example, 108a of FIG. 10, 108b) conventionally seen by the front end surface of the perforation blade 3, and the chip | tip of the diamond abrasive grain 5 by the big stress added to a convex part can be suppressed significantly. In addition, when the drill bit is pressed against a work material such as concrete during drilling, the entire diamond abrasive grains 5 on the tip surface of the drill blade 3 are in contact with the work material evenly to improve the cutting efficiency. To do. Furthermore, uneven wear of the diamond abrasive grains 5 can be suppressed, and an effect of extending the drilling life can be obtained.

  Next, the shaped drilling blade 3 is dried in the atmosphere for a predetermined time, for example, about several tens of minutes to several hours (step 37). Thereafter, the drill bit 1 is completed by sintering in a reducing atmosphere using a high temperature furnace filled with hydrogen (step 38). In addition, although the temperature and sintering time at the time of sintering vary depending on the material of the brazing material 4, for example, when using the nickel-based brazing material 4, it is preferable to sinter in an oven at about 1000 ° C. for 30 minutes or more. By sintering, the solvent component of the brazing material 4 evaporates and then melts, whereby the diamond abrasive grains 5 are firmly fixed to the body 2 and the diamond abrasive grains 5 are largely exposed to the outside from the surface of the brazing material 4. It becomes like this.

  Next, a second embodiment will be described with reference to FIG. In the first embodiment, the shape of the drilling blade is adjusted by using the first shaping process for shaping the side surface of the drilling blade 3 and the second shaping process for shaping the tip surface of the drilling blade 3. . However, when this method is used, the contact surfaces 5a of the diamond abrasive grains 5 that are in contact with the upper surface 31a of the mold 31 in FIG. 4 are aligned substantially in parallel, so that the planar portion of the diamond abrasive grains 5 is located on the lower side. Align. For this reason, it turned out that there exists a tendency for a sharpness to be a little inferior compared with the conventional perforation blade which arrange | positioned the diamond abrasive grain 5 at random. Therefore, in the second embodiment, the improved planar die 41 is used instead of the planar die 31 used in step 36 for shaping.

  FIG. 5 is a diagram illustrating a state in which the tip surface of the drilling blade 3 is shaped using the planar die 41 according to the second embodiment. The planar die 41 has innumerable diamond abrasive grains 42 fixed on the upper surface thereof by adhesion or the like in advance. The diamond abrasive grains 42 are not attached to the perforating blade 3 side, but are provided to adjust the direction of the diamond abrasive grains 5 on the perforating blade 3 side. It is preferable to fix it so as not to leave. Further, in order to achieve the purpose of adjusting the direction of the diamond abrasive grains 5 on the perforating blade 3 side, the diamond abrasive grains 42 are 1/2 to the average particle diameter of the diamond abrasive grains 5 attached to the perforating blade 3. The average particle size is preferably 1 time.

  Usually, most of the crystal structure of the industrial diamond abrasive grains 42 is a polyhedron. If one of the surfaces (42a) is bonded so as to be in contact with the upper surface of the flat mold 41, the protrusion (42b) is often located on the opposite side. That is, as shown in FIG. 5, the protrusions 42b of the diamond abrasive grains 42b are arranged so as to face upward. When the perforating blade 3 is pressed against the diamond abrasive grains 42 as indicated by the arrow 25, the projections 42b of the diamond abrasive grains 42 enter the gaps between the opposing diamond abrasive grains 5, and the applied diamond abrasive grains 5 You can turn it slightly to turn the sharp corners outward. Thus, by positively adjusting the direction of the sharp corners of the diamond abrasive grains 5, a drill bit with good sharpness can be realized.

  In addition, it became clear by experiment of inventors that the average particle diameter of the diamond abrasive grain 42 fixed to the planar type | mold 41 has a big influence on the sharpness of the drilling blade 3 of the drill bit 1. FIG. That is, when the average particle diameter of the diamond abrasive grains 42 is less than ½ times the average particle diameter of the applied diamond abrasive grains 5, the diamond abrasive grains are pressed when the tip surface of the drilling blade 3 is pressed against the flat mold 41. The tip angle of the grains 42 cannot sufficiently enter the gaps between the diamond abrasive grains 5, and an ideal rotational force cannot be applied to the diamond abrasive grains 5. Further, when the average grain size of the diamond abrasive grains 42 exceeds 1 times that of the applied diamond abrasive grains 5, the diamond abrasive grains 5 greatly bite into the gaps between the diamond abrasive grains 5, and the diamond abrasive grains 5 are pushed sideways, and the diamond abrasive grains 5 are unevenly distributed. Will occur. Therefore, the diamond abrasive grains 42 are preferably about 1/2 to 1 times the average particle diameter of the diamond abrasive grains 5 attached to the perforating blade 3.

  The drill bit described above is a so-called non-core type drill bit as shown in FIG. 9, but the present invention can be similarly applied to a so-called core type drill bit. FIG. 6 is a front view of the core-type drill bit 51. The members constituting the drill bit 51 are a cylindrical metal body 52, an attachment portion 60 connected to the rear end side of the body 52, and an outside of the body 52 formed between the body 52 and the attachment portion 60. It is constituted by a disc-shaped brim portion 62 having a diameter larger than the diameter and a perforating blade 53 provided at the opening tip of the body 52. A recess 61 is formed near the center of the mounting portion 60 in the axial direction (vertical direction).

  The diameter of the body 52 is larger than that of the mounting portion 60, and a hollow is formed inside the body 52 to form a substantially cylindrical shape. On the side surface of the body 52, a spiral projection 63 is formed. The helical protrusion 63 is preferably configured integrally with the body 52. The direction of the helix may be a rotation direction that draws cutting powder to the rear end side with respect to the rotation direction in the same manner as a normal drill blade. A cutout 52a may be formed in the axial direction in the opening on the front end side (lower end side) of the body 52 in order to improve the removal of cutting powder and the removal of the drill bit 1. In the drill bit 51, the drilling blade 53 can be divided and formed by being provided on a part of the circumference of the drilling blade 53, and fine dust generated from the drilled work material is effectively formed by the notch 52a. It is discharged and the perforation efficiency can be improved.

  A core discharge hole 65 is formed on the side of the body 52. The core discharge hole 65 is formed to discharge the core accumulated in the body 52 to the outside, and is a horizontal hole that penetrates the internal space and the outside. The core discharge hole 65 may be disposed on the inner rear end side (upper side) of the internal space of the body 52. The shape of the core discharge hole 65 is relatively arbitrary, and preferably has a certain size so that the core accumulated in the internal space can be effectively discharged to the outside. In this embodiment, when viewed from the front (as viewed in FIG. 6), the core discharge hole 65 has an oval shape in which a semicircle is connected to the upper and lower sides of the rectangle. Further, the width of the core discharge hole is ensured to be about the same as or slightly larger than the inner diameter of the drilling blade 53 because the core accumulated in the internal space during cutting has a diameter slightly smaller than the inner diameter of the drilling blade 53. It is preferable.

  FIG. 7 is a sectional view of the drill bit 51. The body 52 has a cylindrical shape, and the body 52 and the protrusion 63 are integrally formed. The protrusion 63 continuously extends in a spiral shape from the vicinity of the lower end to the vicinity of the flange 62 along the outer periphery of the body 52. In the manufacturing method, a cylindrical body 52 having a uniform thickness is prepared, and first, a continuous groove 64 is formed by cutting. The ratio of the axial width w1 of the spiral protrusion 63 and the axial width w2 of the groove 64 is 7: 2 in this embodiment. However, the sizes of these widths w1 and w2 are arbitrary. In particular, the axial width w2 of the groove 64 is determined by considering the amount and size of cutting powder particles generated from the object to be cut. What is necessary is just to determine the depth of 64 radial directions.

  In FIG. 7, the drilling blade 53 is continuously formed from the inner peripheral surface 53c near the lower end of the cylindrical body 52 to the distal end surface 53b and the outer peripheral surface 53a. Among these, the molding method of the outer peripheral surface 53a of the punching blade 53 can be shaped in the same manner as the shaping method described in FIG. Moreover, the shaping | molding method of the front end surface 53b of the perforation blade 53 can be shaped similarly to the shaping method demonstrated in FIG. 4 or FIG. However, in the shaping procedure according to the first embodiment, the tip surface 53b and the outer circumferential surface 53a of the drilling blade 53 can be shaped, but the shape of the inner circumferential surface 53c cannot be shaped. In the drilling operation, the cylindrical core passes inside the inner peripheral surface 53c. Therefore, if a large protrusion of the diamond abrasive grains 5 occurs on the inner peripheral surface 53c, stress is applied to the convex portion during drilling. May concentrate and the drilling blade 53 may be chipped. Therefore, in the third embodiment, the inner peripheral surface 53c of the drilling blade 53 is shaped using a die 81 having a cylindrical convex portion at the center as shown in FIG.

  FIG. 8 is a schematic diagram for explaining a process of shaping the inner peripheral surface 53c of the drilling blade 3 according to the third embodiment of the present invention while pressing the inner peripheral surface 53c against a die 81 having a cylindrical convex portion in the center (this diagram). Note that the vertical and horizontal dimensions are not drawn exactly.) The mold 81 is formed with a cylindrical recess 82 extending downward from the upper surface, and an annular bottom surface 83 is formed. A cylindrical convex portion 84 protruding upward is formed on the inner peripheral side of the annular bottom surface 83. The convex portion 84 is formed with a flat circular upper surface 84a and a cylindrical side surface 84b for connecting the upper surface 84a and the annular bottom surface 83. The cylindrical convex portion 84 is formed so that its diameter decreases from the bottom to the top, and the relationship of d1> d2 is satisfied when viewed in cross section as shown in FIG. Thus, by forming the side surface 84b in a tapered shape, the inner peripheral surface 53c of the drilling blade 53 can be easily shaped. At this time, on the outer peripheral surface 53 a of the punching blade 53, the punching blade 53 does not contact the die 81 as indicated by the arrow 85. Therefore, using the mold 81 can prevent the shape of the outer peripheral surface 53a from being affected. On the other hand, the tip surface 53b of the punching blade 53 is in good contact with the annular bottom surface 83 of the die 81, so that the tip surface 53b can be shaped simultaneously with the shaping of the inner peripheral surface 53c. The shaping work using the mold 81 can be performed in place of step 36 in the flowchart shown in FIG. Alternatively, a shaping operation using the mold 81 may be added between steps 35 and 36.

  As described above, since the drilling blade 53 of the core-type drill bit 51 can be formed well by performing the shaping work using the inner peripheral surface shaping die 81, the number of protrusions of the drilling blade 53 is small. It becomes a shape, and the chipping of the diamond abrasive grains 55 due to a large stress applied locally can be greatly suppressed. Further, uneven wear of the diamond abrasive grains 55 can be suppressed, and an effect of extending the drilling life can be obtained.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the second embodiment, as shown in FIG. 5, diamond abrasive grains 42 are bonded and fixed to the upper surface of the flat mold 41, but instead of using the diamond abrasive grains 42, Concavities and convexities equivalent to the diamond abrasive grains 42 may be formed by machining or the like. In this case, since the irregularities are cut by the diamond abrasive grains 5 at the time of drill bit shaping, the life of the mold is reduced, but the overall manufacturing cost can be suppressed by not using the diamond abrasive grains. In addition, diamond abrasive grains may be bonded and fixed to the curved concave mold 21 shown in FIG. 3 of the first embodiment in the same manner as in FIG. 5, and in this way, a sharp angle is also formed on the side surface of the drill bit. Can be directed outward, and a drill bit with good sharpness can be realized. In the above-described embodiment, the drill bit has an outer peripheral surface formed parallel to the axial direction. However, the drill bit has a tapered shape in which the vicinity of the tip of the drill bit is slightly enlarged toward the rear end, and is indicated by an arrow 85 in FIG. The gap may be eliminated.

DESCRIPTION OF SYMBOLS 1 Drill bit 2 Body 3 Drilling blade 4 Brazing material 5 Diamond abrasive grain 5a Contact surface 8a (Diamond abrasive grain contact surface 8a Convex part 10 Attaching part 11 Recessed part 12 Collar part 13 Protrusion 21 (Curve concave shape) type | mold 21a-21d ( Side 31 (planar) mold 31a (planar mold) upper surface 31b (planar mold) lower surface 41 (planar) mold 42 Diamond abrasive grain 51 Drill bit 52 Body 53 Perforated blade 53c Inner peripheral surface 55 Diamond abrasive grains 60 Mounting portion 61 Recessed portion 62 Hook portion 63 Protrusion 64 Groove 65 Core discharge hole 81 Mold 83 Bottom surface 84 Convex portion 84a (Convex portion) Top surface 84b (Convex portion) Side surface 101 Drill Bit 102 Body 103 Drilling blade 104 Brazing material 105 Diamond abrasive

Claims (9)

In the manufacturing method of a drill bit for forming a drilling blade by fixing diamond abrasive grains to a tip of a cylindrical or cylindrical metal body with a brazing material,
Dipping the tip of the metal body into a liquid brazing material and pulling it out,
The diamond abrasive grains are adhered to the applied brazing material,
The drill bit is manufactured by pressing the outer peripheral side surface and the front end surface of the brazing material to which the diamond abrasive grains have been attached to a mold and then sintering, and then sintering the drill bit.   The drill bit manufacturing method according to claim 1, wherein the drilling blade is shaped into a cylindrical shape or a columnar shape.   The method for manufacturing a drill bit according to claim 2, wherein the outer peripheral side surface of the brazing material is shaped by rotating the metal body while pressing the outer peripheral side surface of the drilling blade against a curved concave mold.   The method for manufacturing a drill bit according to claim 3, wherein the outer peripheral side surface of the drilling blade is pressed against a flat mold to shape the tip surface of the brazing material. On the surface against which the brazing material of the planar mold is pressed, there is provided a diamond diamond for shaping having an average particle diameter that is 1/2 to 1 times the average particle diameter of the diamond abrasive grain,
The drill bit manufacturing method according to claim 4, wherein a front end surface of the brazing material is shaped using a surface provided with the shaping diamond abrasive grains. The metal body is cylindrical;
The perforating blade is provided in an opening of the cylindrical metal body;
6. The inner peripheral part of the drilling blade is shaped by pressing the inner peripheral part of the drilling blade against a convex part of a mold having a cylindrical convex part at the center. The manufacturing method of the drill bit as described in a term. A drill bit for forming a drilling blade by fixing diamond abrasive grains to a tip of a cylindrical or cylindrical metal body with a brazing material,
Dipping the tip of the metal body into a liquid brazing material and pulling it out,
The diamond abrasive grains are adhered to the applied brazing material,
A drill bit in which the perforating blade is manufactured by pressing an outer peripheral side surface and a front end surface of the brazing material to which the diamond abrasive grains are adhered to a mold and then sintering.   The drill bit according to claim 7, wherein the outer peripheral side surface of the brazing material is shaped by rotating the metal body while pressing the outer peripheral side surface of the drilling blade against a curved concave mold.   The drill bit according to claim 8, wherein the outer peripheral side surface of the drilling blade is pressed against a flat mold to shape the front end surface of the brazing material.

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