JP2008207284A - Boring tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems wherein a tool is damaged in processing as a result of a superhard abrasive grain being torn off from the central vicinity of a tip part, and a part of a workpiece contacting with an inner hole can not be processed since the inner hole exists in the center of a rotary shaft, when grinding chips of a ceramic sintered body being the workpiece stagnate in the center of the tip part, in a conventional boring tool. <P>SOLUTION: A columnar rotary body 12 is formed by fixing abrasive grains to the tip part 18, and has: an inner hole 24 opening on a tip surface of the tip part on the inside of the columnar rotary body; and a recessed part extending up to an outer peripheral edge part in one direction by including the rotational center of the tip surface by looking at the tip surface in a plan view in the tip surface of the columnar rotary body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drilling tool, and more particularly to a drilling tool for drilling a hole in a ceramic sintered body.

  Drilling a hard and brittle material such as a ceramic sintered body is performed by rotating a drilling tool with superhard abrasive grains fixed to the tip of a columnar base around the longitudinal axis of rotation of the base. In this state, the drilling tool is pushed straight against the work piece. Conventionally, a drilling tool that has been used publicly is provided with a cross-shaped groove at the tip of the base, with the four ends of the cross-shaped groove extending to the periphery of the tip, It has a structure in which super hard abrasive grains such as diamond are fixed to the entire tip. In this way, the drilling tool that performs machining while moving straight to the workpiece has an inner hole for projecting the grinding fluid to the tip in order to improve machining efficiency.

  For example, in Patent Document 1, as shown in FIGS. 4A to 4C, two concave portions 56 are provided in the tip portion 54, an inner hole 66 is provided in the concave portion 56, and abrasive grains 58 are provided in the tip portion 54. A drilling tool 50 is fixed. The grinding fluid is ejected from the inner hole 66 through the through hole 64. 4A is a plan view of the tip 54 in plan view, FIG. 4B is a cross-sectional view of the section passing through the rotation axis and CC ′ line of the drilling tool of FIG. 4A, and FIG. It is sectional drawing of the cross section which passes along the rotating shaft and DD 'line of the tool for a drilling of a).

  Patent Document 2 describes a drilling tool (not shown) in which an inner hole for projecting a grinding liquid is provided at the center of the tip (center of the rotation axis of the base).

Catalog Mito Kogyo Co., Ltd. ZERO-M DRILL JP 2004-358765 A

  In the drilling tool of Non-Patent Document 1, grinding scraps of a ceramic sintered body, which is a workpiece, stagnate in the center of the tip portion, and super hard abrasive grains peeled off from the vicinity of the center of the tip portion. There was a problem that would be damaged.

  The drilling tool of Patent Document 2 has a problem in that a part of the workpiece that is in contact with the inner hole cannot be processed because the inner hole is at the rotation center of the rotating shaft.

  In view of the above, the present invention is a columnar rotating body in which abrasive grains are fixed to a tip end portion, and an inner hole opened in the tip end surface of the tip end portion inside the columnar rotating body, and the tip end of the columnar rotating body. The surface has a recess that extends to the outer peripheral edge in one direction including the center of rotation of the tip surface when the tip surface is viewed in plan.

  Furthermore, the maximum depth of the recess with respect to the tip surface is 0.1 mm or more.

  Furthermore, the inner hole is open to the inner surface of the recess.

  Furthermore, the concave portion has a concave curved inner surface.

  Furthermore, a notch groove along the side surface of the columnar rotating body is formed continuously with the recess.

  A columnar rotator with abrasive grains fixed at the tip, the inner surface of the columnar rotator opening in the tip surface of the tip and the tip surface of the columnar rotator in plan view In addition, by having a recess extending to the outer peripheral edge in one direction including the center of rotation of the tip surface, the processing scraps of the drilled workpiece are collected in the recess, and the collected processing scraps are collected from the inner hole. It can be efficiently moved in one direction in the recess from the rotation center side of the tip surface to the outer peripheral edge side together with the sprayed grinding liquid, and discharged to the side surface of the columnar rotating body. As a result, since the friction between the scraps and the abrasive grains at the tip is suppressed, it is possible to provide a drilling tool that makes it difficult for the abrasive grains on the tip surface to peel off from the columnar rotating body even when drilling for a long time. .

  Furthermore, by using a drilling tool in which the maximum depth of the recess with respect to the tip surface is 0.1 mm or more, the processing waste is particularly efficiently collected and discharged in the recess. For this reason, since the friction between the scraps and the abrasive grains on the front end surface is further suppressed, a drilling tool that makes it difficult for the abrasive grains on the front end surface to peel off from the columnar rotating body even if drilling is performed for a longer time. be able to.

  Further, by making the inner hole a drilling tool that is opened in the inner surface of the recess, the machining waste collected in the recess is immediately fluidized by the grinding fluid ejected from the inner hole, and processing is performed in a shorter time. Since the scraps are discharged, it is possible to provide a drilling tool that makes it difficult for the abrasive grains on the tip surface to peel off from the columnar rotating body even when drilling for a longer time.

  Furthermore, since the recess is a drilling tool having at least an inner surface forming a concave curved surface, the processing waste collected in the concave portion can be quickly moved along the concave curved surface to the outer peripheral edge side. From this, it is possible to make a drilling tool having a structure in which the abrasive grains are particularly difficult to peel off.

  Furthermore, by using a drilling tool in which a notch groove is formed along the side surface of the columnar rotating body in succession to the concave portion, the resistance when the machining waste is discharged together with the grinding liquid is reduced, so that the machining waste is reduced. It becomes easy to be discharged quickly. As a result, it is possible to provide a drilling tool in which the abrasive grains do not easily peel off even when drilling is performed for a long time.

  The best mode for carrying out the present invention will be described.

  FIG. 1A is a plan view showing the tip surface of the tip of the drilling tool of the present invention, and FIG. 1B passes through the axis of rotation of the drilling tool of FIG. Sectional drawing which shows a perpendicular | vertical cross section, (c) is sectional drawing which passes along the rotating shaft of the drilling tool of (a), and shows a cross section perpendicular | vertical to a BB 'line.

  FIG. 2A is a plan view of the tip surface of the tip portion showing another embodiment of the drilling tool of the present invention, and FIG. 2B is a side view of the tip portion of the drilling tool of FIG. It is the top view seen from the side.

The drilling tool 10 of the present invention is
A columnar rotating body 12 in which abrasive grains 18 are fixed to a tip end portion 14, an inner hole 26 opened in the tip end surface of the tip end portion 14 inside the columnar rotating body 12, and the tip end surface of the columnar rotating body 12. And a recess 16 extending to the outer peripheral edge V in one direction including the center of rotation of the tip surface in plan view. As a result, the machining scraps of the drilled workpiece are collected in the recess 16, and the collected machining scraps together with the grinding liquid ejected from the inner hole 26 from the rotation center S ₁ side of the front end surface to the outer peripheral edge V side, It can be efficiently moved in one direction within the recess 16 and discharged to the side surface 28 of the columnar rotating body 12. As a result, since the friction between the machining waste and the abrasive grains 18 of the tip end portion 14 is suppressed, the drilling tool 10 is difficult to peel off the abrasive grains 18 on the tip end face from the columnar rotating body 12 even if drilling is performed for a long time. It can be.

  In addition, even if it has the recessed part extended to the outer-periphery edge part V of several directions including the rotation center, if the recessed part is deviating toward the specific direction as a whole, it can be considered that it is one direction. And does not depart from the scope of the present invention.

The recess does not include the rotational center S ₁ or a recess that does not extend to the outer peripheral edge portion V, even provided separately distal end surface, do not depart from the scope of the present invention.

  The material of the columnar rotating body 12 is preferably tool steel. The through hole 24 formed in the columnar rotating body 12 is a flow path for supplying the grinding fluid to the inner hole 26.

  As the material of the abrasive grains 18, either diamond or CBN (cubic boron nitride) is selected. The abrasive grains 18 are fixed to the tip end portion 14 of the columnar rotating body 12 together with a binder such as Ni by electrodeposition.

  In the drilling tool 10, the maximum depth H of the recess 16 with respect to the distal end surface of the distal end portion 14 of the columnar rotating body 12 is preferably 0.1 mm or more. As a result, the processing waste is particularly efficiently collected and discharged in the recess 16. For this reason, since the friction between the processing scrap and the abrasive grains 18 on the distal end surface of the distal end portion 14 is further suppressed, the abrasive grains 18 on the distal end surface of the distal end portion 14 remain in the columnar rotating body even when drilling is performed for a longer time. 12 can be used as a drilling tool that is difficult to peel off.

When the distal end surface of the distal end portion 14 in plan view, when the distance between the end of the recess 16 and the rotation center _{S 1} and L, L / _{D 1} is preferably 0.1 to 0.3. Thus, the outer peripheral edge portion V direction from the vicinity of the center of rotation S _1, since the processing waste in the recess 16 tends to be moved, that the abrasive grains 18 are worn by swarf is further suppressed. If L / D ₁ is 0.1 or more, abrasive grains near the rotation center S ₁ are difficult to peel off from the columnar rotating body 12, and if L / D ₁ is 0.3 or less, the abrasive grains are near the rotation center S ₁ . Since it becomes difficult for the processing waste to stay, it is possible to reduce that the abrasive grains 12 are peeled off from the columnar rotating body 12.

  As shown in FIGS. 1 and 2, it is preferable that the inner hole 26 opens on the inner surface of the recess 16.

  As a result, the machining waste collected in the recess 16 is immediately fluidized by the grinding fluid ejected from the inner hole 26, and the machining waste is discharged in a shorter time. It is possible to make a drilling tool in which the abrasive grains 18 are difficult to peel off from the columnar rotating body 12. If the inner hole 26 is open to the recess 16, the time until the machining waste fluidizes in the recess 16 can be shortened, so that the machining waste can be discharged in a short time.

3 (a), 3 (b) and 3 (c) are views showing still another embodiment of the present invention, and FIG. 3 (a) is a columnar shape before the abrasive grains are fixed to the columnar rotating body of FIG. The top view which shows the front-end | tip of a rotary body, (b) is sectional drawing which shows the cross section of a columnar rotary body which passes along the rotation axis of the columnar rotary body of (a), and is perpendicular | vertical to an AA 'line, (c) is (a). It is sectional drawing which shows the columnar rotary body cross section which passes along the rotating shaft of this columnar rotary body, and is perpendicular | vertical to CC 'line. FIG. 3 (b), the (c), the recess 16 is preferably at least its inner surface a drilling tool which forms a concave curved surface R _1.

Thus, it is possible to move quickly processing refuse collected in the recess 16 to along the concave curved surface R ₁ outer periphery V side, for drilling the most peeling hard to structure abrasives 18 from columnar rotary body 12 The tool 10 can be used.

When forming the concave surface R ₁ to the inner surface of the concave portion 16, it becomes concave facing surface forming the abrasive grains 18 at the tip surface.

Since the boundary between the front end surface and the recess 16 is a part to which a large mechanical stress is applied in the drilling process, the stress applied to this part is reduced by the drilling tool in which the abrasive grains are difficult to peel off. desirable in order to, for this purpose, as shown in FIG. 3 (b), (c) , the inner surface of the recess 16 is preferably a boundary between the inner surface of the distal end surface and the recess 16 has a convex curved surface R ₂ .

Accordingly, since it is suppressed that stress at the boundary between the inner surface of the front end surface and the recess during processing is concentrated, abrasive 18 that is fixed to the concave curved surface R ₂ is a hard drilling tool 10 peeling be able to.

  In addition, it is preferable that the recessed part 16 occupies 3 to 20% of the outer periphery part V of a front end surface. As a result, not only can a sufficiently large amount of processing waste be collected in the recess 16, but also processing waste can be quickly discharged, so that the abrasive grains 18 are difficult to peel off even if drilling is performed for a long time. The tool 10 can be used. If the recessed part 16 is 3% or more of the outer peripheral edge part V of a front end surface, it will be hard to retain a process waste in the recessed part 16, and peeling of the abrasive grain 18 by carrying out drilling for a long time will be reduced. If the concave portion 16 is within 20% of the outer peripheral edge portion V of the front end surface, stress does not concentrate on the abrasive grains other than the concave portion 16, so that the abrasive grains 18 formed by drilling for a long time are not affected. Peeling is reduced.

The recess 16 occupies 3-20% proportion of the outer peripheral edge portion V of the front end surface passes through the rotation center S ₁ as shown in FIG. 2 (a), a both ends of the outer peripheral edge portion V corresponding to the recesses 16 Two straight lines are drawn and an angle α (°) formed by these two straight lines is obtained, and (α / 360 °) × 100 means 3 to 20%. Note that one of the ends of the outer peripheral edge portion V corresponding to the recess 16, if there is a notched groove 22 to be described later, a straight line drawn to the rotation center S ₁ from the point of intersection and the groove 22 and the recess 16 notch To find this ratio.

  The drilling tool 10 is formed by forming a notch groove 22 along the side surface 28 of the columnar rotating body 12 continuously with the recess 16, so that the resistance when the machining waste is discharged together with the grinding liquid is small. Therefore, it becomes easy to discharge the processing waste quickly. As a result, it is possible to obtain a drilling tool 10 in which the abrasive grains 18 are difficult to peel off even when drilling is performed for a long time.

  The notch groove 22 is preferably present at a position biased with respect to the recess 16. Specifically, as shown in FIG. 2, it means a state in which at least a part of the notch groove 22 is overlapped with an end where the recess 16 intersects the outer peripheral edge V. By forming the notch groove 22 in such a biased position, the machining waste can be discharged particularly quickly.

A drilling tool was produced as follows. Table 1 shows the production conditions and results other than those shown below.

  The columnar rotating body 12 was made of tool steel. The size was an outer diameter of 5 mm and a length of 70 mm.

  As the abrasive grains 18, diamond abrasive grains having a grain size of # 120 defined in JIS B4130 (1982) are electrodeposited on the front end surface of the columnar rotating body and the side surface in a range from the front end surface side to 5.5 mm. Fixed. The method of electrodeposition is to put # 120 diamond abrasive grains in a Ni plating solution and immerse the tip 14 of the columnar rotating body 12 in this plating solution, and simultaneously apply Ni plating to the columnar rotating body 12, The diamond abrasive grains were fixed as abrasive grains 18 in the Ni plating formed on the columnar rotating body 12.

  As a workpiece, an alumina sintered body having a thickness of 12 mm and a purity of 99.5% was used.

  As the drilling machine, a grinding center (hereinafter referred to as GC) was used.

  As the processing conditions, the workpiece was drilled by making the longitudinal direction of the drilling tool 10 perpendicular to the workpiece. The number of rotations of the drilling tool 10 was 5000 rotations per minute, and the feed rate of the drilling tool 10 was 30 mm / min. The depth of the hole to be processed was set to 10 mm, and the number of holes processed one hole before the drilling tool 10 was damaged was determined as the number of holes that can be processed. During drilling, a grinding fluid (water added with a rust inhibitor and a surfactant) was ejected from the inner hole 26 at a pressure of 3-5 MPa.

  When drilling was performed using the drilling tool 10 (sample No. 1-15) of the present invention, the number of holes that could be processed was 1612-2200, and a large number of holes could be drilled. In particular, sample no. 9-15 was particularly excellent because the number of holes that could be processed was 1907-2200.

  Samples with a maximum depth H of 0.1 mm or more (eg, Nos. 9 and 11) have 1423 and 1641 holes that can be processed, respectively, and samples with a maximum depth H of less than 0.1 mm (No. 1, In 2), the number of holes that can be processed was 1172 and 1165, respectively.

  Sample No. with an inner hole opening in the inner surface of the recess. Sample No. 8 has 1199 holes that can be processed and the inner hole is not opened on the inner surface of the recess. 3 had 1047 holes that could be processed.

  Sample No. in which the inner surface of the recess forms a concave curved surface. Sample No. 13 has a number of holes that can be processed 1647 and has no concave curved surface. 6 had 1169 holes that could be processed.

  Sample No. with notched grooves Sample No. 13 has a number of holes that can be processed 1647 and has no notch. 7 had 1192 holes that could be processed.

  Next, as a comparative example, a drilling tool outside the scope of the present invention was produced in the same manner as in the example except for the following and evaluated in the same manner as in the example.

  Sample No. Reference numeral 16 denotes a drilling tool shown in FIG. Sample No. Reference numeral 17 denotes a drilling tool shown in FIG. 5. The depth of the recess 56 is 0.3 mm, and the width is 1.5 mm. Sample No. 18 is a sample No. 18; 10 was used as a drilling tool without an inner hole.

  Sample No. which is a comparative example. 16, 17, and 18 have 1300 holes, 1347 holes, and 20 holes, respectively, and it can be seen that the number of holes that can be processed is smaller than when the drilling tool of the present invention is used. .

  On the other hand, the drilling tool of the present invention has a special material No. 1, 2, 9, 11 to 0.1 mm or more is preferable. 3 and 6 are preferably located on the inner surface of the concave portion. 6 and 13 indicate that a curved surface is preferable.

(A) is a top view which shows the front end surface of the front-end | tip part of the drilling tool of this invention, (b) passes along the rotating shaft of the drilling tool of (a), and is perpendicular | vertical to an AA 'line. Sectional drawing which shows a cross section, (c) is sectional drawing which shows the cross section which passes along the rotating shaft of the drilling tool of (a), and is perpendicular | vertical to the BB 'line | wire. (A) is a top view of the front end surface of the front-end | tip part which shows other embodiment of the drilling tool of this invention, (b) is the front-end | tip part of the drilling tool of (a) from the side surface side of a columnar rotary body. FIG. (A) is a top view which shows the front-end | tip of the columnar rotary body before fixing an abrasive grain to the drilling tool 10 of FIG. 1, (b) passes along the rotating shaft of the drilling tool 10 of (a), and A- Sectional drawing which shows the cross section of a columnar rotary body perpendicular | vertical to A 'line, (c) is sectional drawing which shows the columnar rotary body cross section which passes along the rotating shaft of the drilling tool of (a) and is perpendicular to CC' line. is there. (A) is a top view which shows the front-end | tip part of the conventional drilling tool, (b) is sectional drawing of the cross section which passes along the rotating shaft and CC 'line of the drilling tool of (a), (c) is It is sectional drawing of the cross section which passes along the rotating shaft and DD 'line of the tool for drilling of (a). (A) is a top view which shows the front-end | tip part of the other conventional drilling tool, (b) is sectional drawing of the cross section which passes along the rotating shaft and EE 'line of the drilling tool of (a), (c) ) Is a cross-sectional view of a section through the axis of rotation and the FF ′ line of the drilling tool of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 50: Drilling tool 12, 52: Columnar rotary body 14, 54: Tip part 16, 56: Recessed part 18, 58: Abrasive grain 22, 62: Notch groove 24, 64: Through hole 26, 66: Inside Hole 28: Side surface R ₁ : Concave surface R ₂ : Convex surface S ₁ : Center of rotation V: Outer peripheral edge

Claims (5)

A columnar rotator with abrasive grains fixed at the tip, the inner surface of the columnar rotator opening in the tip surface of the tip and the tip surface of the columnar rotator in plan view And the drilling tool which has the recessed part extended to the outer-periphery edge part of one direction including the rotation center of a front end surface. The drilling tool according to claim 1, wherein the maximum depth of the recess with respect to the tip surface is 0.1 mm or more. 3. The drilling tool according to claim 1, wherein the inner hole is open to an inner surface of the recess. The drilling tool according to any one of claims 1 to 3, wherein an inner surface of the concave portion forms a concave curved surface. The drilling tool according to any one of claims 1 to 4, wherein a notch groove is formed along a side surface of the columnar rotating body continuously with the recess.

Images