Hole-opening tool, blank for hole-opening tool, and method for manufacturing blank for hole-opening tool

Abstract

A drilling tool provided with a core material and an outer material located around the core material, in which an integrated hole is formed in the outer material, the integrated hole having, when viewed in the longitudinal direction from the tip side, an insertion region through which the core material is inserted; and an oil hole region communicating with the insertion region, in which an oil hole is defined by the outer periphery of the core material inserted through the insertion region and the edge of the oil hole region of the outer material.

Description

Technical Field

[0001] The present invention relates to a hole-opening tool, a blank for a hole-opening tool, and a method for manufacturing a blank for a hole-opening tool. Background Art

[0002] Patent Documents 1 and 2 disclose a hole-opening tool having an opening portion with an oil hole at the tip. Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-104253 Patent Document 2: Japanese Unexamined Patent Application Publication No. 2011-20254 Summary of the Invention Problems to be Solved by the Invention

[0004] Since the opening portion of the oil hole is located at the tip of the hole-opening tool, it is difficult to accurately form the oil hole in terms of shape and position. Specifically, it is difficult to dispose the opening portion of the oil hole at a specified position at the tip of the hole-opening tool when the hole-opening tool is completed, and it is difficult to form the oil hole without bending or undulating before reaching the opening portion.

[0005] An object of several embodiments of the present invention is to accurately dispose the opening portion of the oil hole at a specified position and suppress the bending or undulating of the oil hole before reaching the opening portion. Technical Means for Solving the Problems

[0006] One aspect of the present invention is a hole-opening tool including a core material and an outer material disposed around the core material. An integral hole is formed in the outer material. When viewed from the tip side in the longitudinal direction, the integral hole has: an insertion region through which the core material is inserted; and an oil hole region communicating with the insertion region. An oil hole is defined by the outer periphery of the core material inserted into the insertion region and the edge of the oil hole region of the outer material.

[0007] One aspect of the present invention is a blank for a hole-opening tool including a core material and an outer material disposed around the core material. An integral hole is formed in the outer material. When viewed from the tip side in the longitudinal direction, the integral hole has: an insertion region through which the core material is inserted; and an oil hole region communicating with the insertion region. An oil hole is defined by the outer periphery of the core material inserted into the insertion region and the edge of the oil hole region of the outer material.

[0008] One aspect of the present invention is a method for manufacturing a blank for a hole-opening tool, including the following steps: a step of forming a core material; a step of forming an outer material, in which an integral hole is formed, and when viewed in the longitudinal direction from the tip side, the integral hole has an insertion region for inserting the core material and an oil hole region communicating with the insertion region; and a step of inserting the core material into the insertion region and dividing and forming an oil hole by the outer periphery of the core material inserted into the insertion region and the edge of the oil hole region of the outer material.

[0009] Regarding other features of the present invention, they will be clarified by the description in the following specification and drawings. Advantages of the Invention

[0010] According to several embodiments of the present invention, the opening portion of the oil hole can be accurately arranged at a specified position, and the bending or undulation of the oil hole before reaching the opening portion can be suppressed. Description of the Drawings

[0011] Figure 1 It is a side view of the hole-opening tool 10 of the present embodiment. Figure 2 It is a view obtained by observing the hole-opening tool 10 of the present embodiment in the longitudinal direction from the tip DE side. Figure 3 It is Figure 1 a cross-sectional view taken along line A-A' in Figure 4 It is Figure 1 a view after separating the core material 21 and the outer material 22 in the cross-sectional view taken along line A-A' in Figure 4 A is a view of the outer material 22. Figure 4 B is a view of the core material 21. Figure 5 It is a cross-sectional view taken along line A-A' of the hole-opening tool 10A of the first modified example. Figure 6 It is an explanatory view of the hole-opening tool 10B of the second modified example. Figure 6 A is a cross-sectional view taken along line A-A' of the hole-opening tool 10B. Figure 6 B is an enlarged view of the vicinity of the oil hole 14. Figure 7 It is an explanatory view of the oil hole 14 of the blank 20 of the present embodiment. Figure 8 It is an explanatory view of the marking portion 24 of the blank 20 of the present embodiment. Figure 8 A is a view showing an outline of the marking portion 24. Figure 8 B is a side view of the blank 20 of the present embodiment. Figure 9 It is a flowchart of the manufacturing process of the blank 20 of the present embodiment. Figure 10 It is an explanatory view of the mold 30 of the external material 22 used in the manufacturing process of the blank 20 of the present embodiment. Figure 11 It is an explanatory view of the pin 33 for the integral hole of the mold 30. Figure 11 A is a perspective view of the pin 33 for the integral hole. Figure 11 B is a view obtained by observing the pin 33 for the integral hole from the tip side. Figure 12 It is a view showing the case where the core material 21 is inserted into the insertion region 25 of the integral hole 27. Figure 12 A is a view showing the state before the core material 21 is inserted into the insertion region 25 of the integral hole 27. Figure 12 B is a view showing the state during the process of inserting the core material 21 into the insertion region 25 of the integral hole 27. Figure 12 C is a view showing the state after the core material 21 is inserted into the insertion region 25 of the integral hole 27. Figure 13 Among them, Figure 13 A is an explanatory view of the mold 30X used in the manufacturing process of the blank 20X of the comparative example. Figure 13 B is a view obtained by observing an example of the blank 20X formed by the mold 30X from the tip side. Figure 14 It is an explanatory view of the pin 33X for the hole of the mold 30X. Figure 14 A is a perspective view of the pin 33X for the hole. Figure 14 B is a view obtained by observing the pin 33X for the hole from the tip side. Detailed Embodiment

[0012] According to the description in this specification and the drawings, at least the following matters become clear.

[0013] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, parts, etc. shown in the respective drawings are denoted by the same reference numerals, and repeated explanations will be appropriately omitted.

[0014] ===This Embodiment=== Figure 1 It is a side view of the hole-opening tool 10 of the present embodiment. Figure 2 It is a view obtained by observing the hole-opening tool 10 of the present embodiment along the length direction from the tip DE side.

[0015] <Definition of Directions and Terms, etc.> First, with reference to Figure 1 and Figure 2 the directions and terms, etc. in the hole-opening tool 10 will be defined.

[0016] The boring tool 10 cuts the material to be cut by rotating around the rotation axis C, thereby forming a machined hole. As Figure 1 shown, the direction along the rotation axis C is defined as the "length direction".

[0017] In addition, as Figure 2 shown, when observing the boring tool 10 from the tip DE side, the direction R of rotation around the rotation axis C is defined as the "rotation direction".

[0018] The tip DE of the boring tool 10 is the end on the side that processes the material to be cut (workpiece) among the two ends in the length direction of the boring tool 10. As Figure 2 shown, the tip DE is located at the center 18 of the boring tool 10 and on the rotation axis C.

[0019] In addition, regarding the definitions of the above directions and terms, etc., unless otherwise specified, they are common in other embodiments of this specification. For example, the directions and terms, etc. in the above boring tool 10 are the same in the blank 20 for the boring tool 10 described later.

[0020] <Outline of the boring tool 10> Next, referring back to Figure 1 and Figure 2 , and newly referring to Figures 3 - 4 B, the outline of the boring tool 10 in this embodiment will be described.

[0021] Figure 3 is Figure 1 a cross-sectional view taken along the line A - A' in Figure 4 is Figure 1 a view showing the separation of the core material 21 and the outer material 22 in the cross-sectional view taken along the line A - A' in Figure 4 A is a view of the outer material 22, Figure 4 B is a view of the core material 21.

[0022] The boring tool 10 can form a hole by cutting the material to be cut with the cutting edge by rotating around the rotation axis C. The boring tool 10 in this embodiment is a drill bit. However, the boring tool 10 can also be a boring tool other than a drill bit, such as a tap or a thread milling cutter. The boring tool 10 can be installed on a machine tool or the like via a support member (not shown) and perform machining of the material to be cut by rotating around the rotation axis C.

[0023] Figure 2 For example, the diameter of the tip DE side of the boring tool 10 shown in

[0024] this embodiment, that is, the drill diameter of the boring tool 10, is in the range of φ1.0 mm to φ3.0 mm. However, the drill diameter of the boring tool 10 can also be in a range other than φ1.0 mm to φ3.0 mm.As shown Figure 2 As shown, the boring tool 10 of the present embodiment is composed of two components, a core material 21 and an outer material 22. However, the boring tool 10 may also have components other than the core material 21 and the outer material 22.

[0025] The core material 21 is the component on the center 18 side among the two components constituting the boring tool 10. As shown Figure 4 in FIG. B, the core material 21 is formed such that the outer shape of the cross section is substantially circular. In addition, the outer diameter of the core material 21 is formed to be equal to or smaller than the hole diameter of the outer material 22. Thereby, the core material 21 can be inserted into the insertion region 25 (described later) of the integral hole 27 formed in the outer material 22.

[0026] As shown Figure 4 in FIG. B, the core material 21 is a solid material (a component with its interior filled). However, the core material 21 may also be a hollow material (a component with a cavity inside). For example, in the boring tool 10A of the first modification shown later Figure 5 in FIG., the core material 21A is a hollow material, and a cavity (oil hole 19) is formed inside the core material 21A.

[0027] In addition, the core material 21 may be formed into a shape other than a substantially circular outer shape of the cross section. The core material 21 may be formed into a shape such as an ellipse, a quadrilateral, a polygon, etc. In this case, the core material 21 only needs to be a shape that can be inserted into the insertion region 25 (described later) of the integral hole 27 formed in the outer material 22 and can be joined to the outer material 22.

[0028] The outer material 22 is a component located around the core material 21, and as shown Figure 4 in FIG. A, it is formed such that the outer shape of the cross section is substantially circular. In addition, the outer periphery 17 of the outer material 22 is also the outer periphery 17 of the boring tool 10 (and the blank 20 described later). In the boring tool 10 of the present embodiment, as described later, the core material 21 is inserted into a part (i.e., the insertion region 25) of the integral hole 27 formed in the outer material 22, and the core material 21 is joined to the outer material 22.

[0029] As shown Figure 3 and Figure 4 in FIG. A, an integral hole 27 is formed in the outer material 22. The integral hole 27 has an insertion region 25 and an oil hole region 26. The insertion region 25 is the region in the integral hole 27 for inserting the core material 21. In addition, the oil hole region 26 is the region in the integral hole 27 that communicates with the insertion region 25.

[0030] As shown Figure 4 in FIG. A, the oil hole region 26 is located on the outer periphery 17 side with respect to the insertion region 25 and communicates with the insertion region 25. As shown Figure 3As shown, when the core material 21 is inserted into the insertion region 25, an oil hole 14 (described later) is formed by dividing the outer periphery of the core material 21 at the connection portion between the insertion region 25 and the oil hole region 26 and the edge of the oil hole region 26.

[0031] In the hole-opening tool 10 of the present embodiment, by having the oil hole region 26 communicating with the insertion region 25, when the core material 21 is inserted into the insertion region 25, breakage of the core material 21 or the outer material 22 can be suppressed. Suppose that when the core material 21 is inserted into a hole that does not have the oil hole region 26 (i.e., a hole with only the insertion region 25), if the gap between the core material 21 (specifically, the outer periphery of the core material 21) and the outer material 22 (specifically, the edge of the insertion region 25) is small, a high load will act on the core material 21 or the outer material 22, and breakage may sometimes occur.

[0032] The outer material 22 of the present embodiment has room for deformation such that when the core material 21 is inserted into the insertion region 25, it expands toward the outer periphery 17 through the oil hole region 26 and the insertion region 25 can be enlarged. Therefore, even if the gap between the core material 21 and the outer material 22 is small, the oil hole region 26 can function as a gap for absorbing the shortage of the gap and suppress the occurrence of breakage of the core material 21 or the outer material 22.

[0033] In the hole-opening tool 10 of the present embodiment, the core material 21 and the outer material 22 are each formed of a cemented carbide composed of a material containing tungsten carbide (WC) and cobalt (Co).

[0034] However, the core material 21 and the outer material 22 may also be formed of materials other than cemented carbide. Here, the core material 21 and the outer material 22 are formed by extrusion molding as described later. Therefore, the materials of the core material 21 and the outer material 22 only need to be materials that can be formed by extrusion molding.

[0035] In addition, the core material 21 and the outer material 22 are not limited to one type of material and may be formed of different materials. In the hole-opening tool 10 of the present embodiment, the cemented carbide used can form the core material 21 with a material having excellent defect resistance and form the outer material 22 with a material having excellent wear resistance.

[0036] In addition, the core material 21 and the outer material 22 are not limited to the cemented carbide as one type of material and may be formed of different materials. For example, the core material 21 may be formed of cemented carbide while the outer material 22 is formed of a material other than cemented carbide, or the core material 21 may be formed of a material other than cemented carbide while the outer material 22 is formed of cemented carbide.

[0037] In the hole-opening tool 10 formed by joining the core material 21 and the outer material 22, as Figure 1 and Figure 2As shown, a discharge groove 11, a cutting edge 12, a flank 13, and an oil hole 14 are formed.

[0038] The discharge groove 11 is a groove for discharging chips from the machining surface during machining of the material to be cut. In the boring tool 10 of the present embodiment, as Figure 1 and Figure 2 shown, two discharge grooves 11 are formed. The two discharge grooves 11 are each formed in a spiral shape along the rotation axis C on the outer periphery 17. However, the boring tool 10 may be formed with three or more discharge grooves 11, or may be formed with only one discharge groove 11.

[0039] As Figure 1 shown, the lead of the discharge groove 11 formed in a spiral shape is set to L1. Here, the "lead" refers to the distance traveled in the length direction when a certain part of the spiral rotates one week in the rotation direction R. In the boring tool 10 of the present embodiment, the discharge groove 11 is formed such that the lead L1 is constant.

[0040] The boring tool 10 of the present embodiment is a so-called two-flute drill bit having two cutting edges 12. However, in the boring tool 10, three or more cutting edges 12 may be formed, or only one cutting edge 12 may be formed.

[0041] The oil hole 14 is a hole for allowing cutting oil to flow toward the tip DE side of the boring tool 10. The chips generated by machining flow through the discharge groove 11 together with the cutting oil flowing out of the oil hole 14 and are discharged smoothly. The oil hole 14 may also be one or three or more corresponding to the number of cutting edges 12.

[0042] In the present embodiment, the two oil holes 14 are each formed in a spiral shape along the length direction as Figure 1 shown. In addition, the discharge groove 11 of the boring tool 10 is formed in a spiral shape along each of the two oil holes 14.

[0043] In the present embodiment, the oil hole 14 has a tapered portion 15 when viewed in the length direction from the tip DE side of the boring tool 10. The tapered portion 15 is formed to become narrower (become pointed) as it goes from the outer periphery 17 side to the center 18 side.

[0044] However, the oil hole 14 may also be a shape other than a shape in which the width narrows toward the center 18 (becomes pointed), for example, it may be a substantially circular shape. In the following description, the oil hole 14 having a shape other than a substantially circular shape including a shape in which the width narrows toward the center 18 (becomes pointed) may sometimes be referred to as an "non-circular shape" oil hole 14.

[0045] In addition, in the boring tool 10 of the present embodiment, the two oil holes 14 are asFigure 2 When viewed in the longitudinal direction from the top DE side as shown, it is located at a position rotationally symmetric with respect to the center 18 of the boring tool 10. Thus, cutting oil can be uniformly supplied to the machining surface. However, when within the range where a reduction in the tip strength of the cutting edge 12 can be tolerated, the two oil holes 14 may not be located at positions rotationally symmetric with respect to the center 18 of the boring tool 10.

[0046] <Oil hole 14> The opening of the oil hole 14 is located at the tip DE of the boring tool 10. Since the smaller the drill diameter, the narrower the tip DE of the boring tool 10, it is sometimes difficult to accurately position the opening of the oil hole 14 at a specified position, and it is difficult to suppress the bending or undulation of the oil hole 14 before reaching the opening. In the case of a non-circular oil hole 14 such as the oil hole 14 of the boring tool 10 in the present embodiment, not only the position of the opening but also the shape is difficult to accurately form.

[0047] Therefore, in the boring tool 10 of the present embodiment, by forming an integral hole 27 larger than the oil hole 14 (i.e., an integral hole 27 having an insertion region 25 and an oil hole region 26) in the outer material 22, first, it is possible to easily ensure the accuracy of the shape and position of the integral hole 27. And by inserting the core material 21 into a part of the integral hole 27 where the shape and position accuracy is ensured (i.e., the insertion region 25), the oil hole 14 is divided and formed. Specifically, the oil hole 14 is divided and formed by the outer periphery of the core material 21 inserted into the insertion region 25 and the edge of the oil hole region 26 of the outer material 22. Thus, in the boring tool 10 of the present embodiment, the opening of the oil hole 14 can be accurately positioned at a specified position, and the bending or undulation of the oil hole 14 before reaching the opening can be suppressed. Furthermore, the oil hole 14 can be formed to accurately follow the lead L1 of the discharge groove 11.

[0048] <Variant example> Figure 5 It is a cross-sectional view taken along the A - A' line of the boring tool 10A of the first variant example.

[0049] The above-mentioned boring tool 10 of the present embodiment only has the oil hole 14 formed by dividing the outer periphery of the core material 21 inserted into the insertion region 25 and the edge of the oil hole region 26 of the outer material 22. However, the way of the oil hole is not limited to Figures 1 - 4 the case of the boring tool 10 shown in B. In Figure 5 the boring tool 10A of the first variant example shown, in addition to the oil hole 14, another oil hole 19 is formed in the core material 21A. Thus, the supply amount of cutting oil to the machining surface can be increased.

[0050] Figure 6It is an explanatory view of the hole-opening tool 10B of the second modified example. In addition, Figure 6 A is a cross-sectional view taken along the line A-A' of the hole-opening tool 10B, Figure 6 B is an enlarged view of the vicinity of the oil hole 14.

[0051] In Figure 6 A and Figure 6 B, in the hole-opening tool 10B of the second modified example, the oil hole 14 formed in the outer material 22B further has a widened portion 16. The widened portion 16 is a portion that is located closer to the center 18 side than the tapered portion 15 and whose width expands as it goes toward the center 18 side when viewed from the tip DE side along the length direction as shown in Figure 6 A. By forming the widened portion 16 in the oil hole 14 formed in the outer material 22B, even in the region on the center 18 side where the width of the oil hole 14 becomes narrow, the supply amount and pressure of the cutting oil can be increased.

[0052] <Blank 20 of the hole-opening tool 10> Hereinafter, the blank 20 of the hole-opening tool 10 in the state before the discharge groove 11 and the cutting edge 12 are formed will be described.

[0053] Figure 7 It is an explanatory view of the oil hole 14 of the blank 20 of the present embodiment. Figure 8 It is an explanatory view of the marking portion 24 of the blank 20 of the present embodiment. In addition, Figure 8 A is a view showing an outline of the marking portion 24, Figure 8 B is a side view of the blank 20 of the present embodiment.

[0054] Regarding the above-mentioned Figures 1 - 6 hole-opening tool shown in B, first, the blank 20 described below is manufactured, and then the discharge groove 11 along the lead (described later) of the oil hole 14 and the cutting edge 12 at the tip are formed.

[0055] As Figure 7 shown, the lead of the helically formed oil hole 14 is set to L2. In the blank 20 of the present embodiment, the lead L1 (refer to Figure 1 ) of the discharge groove 11 during the manufacture of the hole-opening tool 10 is formed to be equal to the lead L2 of the oil hole 14 (L1 = L2).

[0056] As Figure 8 A shown, on the outer periphery of the blank 20 of the present embodiment, a marking portion 24 is formed. The marking portion 24 is a portion that functions as an indication line when the discharge groove 11 is formed. The marking portion 24 is formed in a spiral shape on the outer periphery of the blank 20. In the blank 20 of the present embodiment, as Figure 8As shown in FIG. B, an outer peripheral groove 23 having the same twist angle as the marking portion 24 is formed at a portion other than the marking portion 24 on the outer periphery 17 of the blank 20. Therefore, the marking portion 24 can be visually recognized as a portion where these outer peripheral grooves 23 are not formed. However, the marking portion 24 is not limited to Figure 8 the manner shown in FIG. B, and may be, for example, a colored portion.

[0057] As Figure 8 shown in FIG. A, the lead of the helically formed marking portion 24 is set to L3. In the blank 20 of the present embodiment, the lead L3 of the marking portion 24 is formed to be equal to the lead L2 of the oil hole 14 (refer to Figure 5 ). Thus, it is possible to easily make the lead L1 of the discharge groove 11 formed helically along the marking portion 24 equal to the lead L2 of the oil hole 14 (L1 = L2). That is, the opening accuracy of the oil hole 14 can be formed well on the flank 13 at the tip DE of the boring tool 10. In addition, the leads L1 of the discharge groove 11, L2 of the oil hole 14, and L3 of the marking portion 24 are formed to be equal to each other.

[0058] <Outline of the manufacturing process of the blank 20> Figure 9 is a flowchart of the manufacturing process of the blank 20 of the present embodiment.

[0059] In the manufacturing process of the blank 20 of the present embodiment, first, the formation of the core material 21 (S001) and the formation of the outer material 22 (S002) are performed separately. When forming the core material 21, specifically, powders of the materials of the core material 21 (here tungsten carbide (WC) and cobalt (Co)) are mixed and extrusion molded using a mold (not shown). Thus, the core material 21 is formed into Figure 4 the shape shown in FIG. B (the outer shape of the cross section is a substantially circular shape), and then sintered.

[0060] In addition, when forming the outer material 22, specifically, in the same manner as the formation of the core material 21, powders of the materials of the outer material 22 (here tungsten carbide (WC) and cobalt (Co)) are mixed and extrusion molded using the mold 30 shown in Figure 10 . Thus, the outer material 22 is formed into Figure 4 the shape shown in FIG. A (the outer shape of the cross section is a substantially circular shape). In addition, the outer material 22 is formed with an insertion common region 25 and an oil hole region 26 by extrusion molding using the mold 30.

[0061] Figure 10 is an explanatory view of the mold 30 of the outer material 22 used in the manufacturing process of the blank 20 of the present embodiment. As Figure 10As shown, the mold 30 has an extrusion part 31 and a pin 33 for integral holes. Figure 11 It is an explanatory view of the pin 33 for integral holes of the mold 30. In addition, Figure 11 A is a perspective view of the pin 33 for integral holes, Figure 11 B is a view obtained by observing the pin 33 for integral holes from the tip side.

[0062] The extrusion part 31 is a component through which the powder 36, which is the material of the outer material 22, passes. The cross-section of the extrusion part 31 is formed in a substantially circular shape, and by extruding the powder 36 from the Figure 10 left side to the right side in the extrusion part 31, the outer shape of the cross-section of the outer material 22 can be formed in a substantially circular shape.

[0063] A groove forming part 32 is formed on the inner surface of the extrusion part 31. The groove forming part 32 is a part for forming the outer peripheral groove 23 and the marking part 24 on the outer periphery 17 of the outer material 22 (blank 20). Here, the groove of the groove forming part 32 is formed as a spiral groove having the same twist angle as the outer peripheral groove 23.

[0064] In the manufacturing process of the blank 20 of the present embodiment, the powder 36 is extruded from the Figure 10 left side to the right side while rotating in the extrusion part 31. Thereby, while the outer material 22 is being extrusion-molded, the outer peripheral groove 23 can be formed on the outer periphery 17 of the outer material 22 (blank 20). In addition, although not shown in Figure 10 , the groove forming part 32 is not formed at the part corresponding to the marking part 24, and thereby, the marking part 24 can be formed.

[0065] The pin 33 for integral holes is a component for forming the integral hole 27 of the outer material 22 during the extrusion molding of the outer material 22. The pin 33 for integral holes is formed in a pin shape (rod shape) and is disposed inside the extrusion part 31. In addition, the pin 33 for integral holes is disposed along the extrusion direction of the powder 36 (i.e., the length direction of the blank 20). Thereby, when the powder 36 is extruded while rotating in the extrusion part 31, the integral hole 27 is formed in the part where the pin 33 for integral holes passes through.

[0066] As Figures 10 - 11 shown in B, the pin 33 for integral holes has an insertion pin 34 and an oil hole pin 35. The insertion pin 34 is a component for forming the insertion common area 25. The oil hole pin 35 is a component for forming the oil hole area 26. In the present embodiment, the insertion pin 34 and the oil hole pin 35 are connected. Here, "connection" can be either a manner in which the insertion pin 34 and the oil hole pin 35 are formed integrally, or a manner in which the insertion pin 34 and the oil hole pin 35 are separate and locally connected.

[0067] In the present embodiment, by using the integrated hole pin 33 formed by connecting the general-purpose insertion pin 34 and the oil hole pin 35, the rigidity of the integrated hole pin 33 can be ensured during extrusion, and the integrated hole 27 can be formed with good accuracy in terms of shape and position.

[0068] As Figure 11 shown in A, the general-purpose insertion pin 34 is formed to extend parallel to the length direction of the hole-opening tool 10 to be manufactured (i.e., the length direction of the blank 20 to be manufactured). The oil hole pin 35 is formed to be spirally wound around the outer periphery of the general-purpose insertion pin 34. Thus, the integrated hole 27 is formed such that, along the rotation axis C, the oil hole region 26 is spirally wound around the insertion region 25.

[0069] The outer material 22 extruded and formed using the mold 30 is sintered through subsequent processes. Here, in the manufacturing process of the blank 20 in the present embodiment, unlike the core material 21, the outer material 22 is not completely sintered and is in a semi-sintered state.

[0070] Next, as shown in Figure 12 A to Figure 12 C described later, the core material 21 is inserted through the insertion region 25 ( Figure 9 S003) of the integrated hole 27. Thus, the oil hole 14 is formed by dividing through the outer periphery of the core material 21 inserted through the insertion region 25 and the edge of the oil hole region 26 of the outer material 22.

[0071] Figure 12 FIG. is a view showing the situation where the core material 21 is inserted through the insertion region 25 of the integrated hole 27. In addition, Figure 12 FIG. A is a view showing the state before the core material 21 is inserted through the insertion region 25 of the integrated hole 27. Figure 12 FIG. B is a view showing the state during the process of inserting the core material 21 through the insertion region 25 of the integrated hole 27. Figure 12 FIG. C is a view showing the state after the core material 21 is inserted through the insertion region 25 of the integrated hole 27.

[0072] In the present embodiment, when the core material 21 is inserted through the insertion region 25, the oil hole region 26 communicating with the insertion region 25 expands toward the outer periphery 17, and the insertion region 25 can be enlarged. Therefore, even if the gap between the core material 21 and the outer material 22 is small, it is possible to suppress the situation where a high load acts on the core material 21 or the outer material 22, suppress cracking, and achieve the optimal bonding between the core material 21 and the outer material 22 in subsequent processes.

[0073] Finally, the core material 21 and the outer material 22 are bonded (S004 in Figure 9 the above).

[0074] As described above, the outer material 22 is in a semi-sintered state in the process after extrusion molding. On the other hand, the core material 21 is completely sintered. Thus, in the present embodiment, the completely sintered core material 21 is inserted through the semi-sintered outer material 22. In this process, by further sintering the entirety of the core material 21 and the outer material 22, the outer material 22 also becomes completely sintered. Thereby, the core material 21 and the outer material 22 are joined together.

[0075] Here, usually, components shrink due to sintering. Therefore, when sintering the entirety of the core material 21 and the outer material 22, both the core material 21 and the outer material 22 shrink. However, the core material 21 has already been completely sintered, while the outer material 22 is completely sintered from the semi-sintered state. Thus, the outer material 22 shrinks more significantly than the core material 21. That is to say, the degrees of shrinkage of the outer material 22 and the core material 21 are different. In this process, since the outer material 22 shrinks from the outside in the direction of clamping the core material 21, the core material 21 and the outer material 22 can be joined more firmly.

[0076] In addition, the materials of the core material 21 and the outer material 22 of the blank 20 in the present embodiment contain cobalt (Co). Thus, when sintered in this process, Co is locally melted, and the core material 21 and the outer material 22 are more easily joined.

[0077] Furthermore, in the process of S001, the core material 21 may also be in a semi-sintered state. The semi-sintered core material 21 can be inserted through the semi-sintered outer material 22, and in this process, the entirety of the core material 21 and the outer material 22 is completely sintered. However, as described above, when completely sintered from the semi-sintered state, the components shrink more significantly. Therefore, compared with the case of the present embodiment where the core material 21 has already been completely sintered, the accuracy of the shape and position of the oil hole 14 may sometimes decrease. Therefore, it is preferable that, as in the present embodiment, the completely sintered core material 21 is inserted through the semi-sintered outer material 22, and in this process, only the outer material 22 is completely sintered.

[0078] <Manufacturing process of the blank 20X of the comparative example> Figure 13 A is an explanatory view of the mold 30X used in the manufacturing process of the blank 20X of the comparative example. Figure 13 B is a view obtained by observing an example of the blank 20X formed using the mold 30X from the tip side. Figure 14 is an explanatory view of the hole pin 33X of the mold 30X. In addition, Figure 14 A is a perspective view of the hole pin 33X, Figure 14 B is a view obtained by observing the hole pin 33X from the tip side.

[0079] In the present embodiment, the two components, i.e., the core material 21 and the outer material 22, are formed separately, and the blank 20 is manufactured by joining the core material 21 and the outer material 22 in a subsequent process. However, in the blank 20X of the comparative example, an oil hole 14 is directly formed in one component corresponding to the core material 21 and the outer material 22.

[0080] The mold 30X used in the manufacturing process of the blank 20X of the comparative example has an extrusion part 31 and a pin for hole 33X. The extrusion part 31 is the same as the extrusion part 31 of the mold 30 in the present embodiment. Different from the mold 30 in the present embodiment, the pin for hole 33X does not have an insertion common pin 34 and only has an oil hole pin 35.

[0081] As described above, the oil hole pin 35 is formed very thin and is not connected to the insertion common pin 34, so its rigidity is low. Therefore, sometimes as Figure 13 shown in A, when the powder 36 passes through the pin for hole 33, the position of the oil hole pin 35 may shift. Thus, in the blank 20X after extrusion molding, sometimes as Figure 13 shown in B, the position of the oil hole 14 may shift. In this comparative example, when the powder 36 is extruded while rotating in the extrusion part 31, the position shift of the oil hole pin 35 with low rigidity is more likely to occur. Therefore, in the manufacturing process of the blank 20X of the comparative example, it is difficult to accurately form the opening of the oil hole 14 in terms of shape and position.

[0082] In contrast, in the present embodiment, by using the integrated pin for hole 33 formed by connecting the insertion common pin 34 and the oil hole pin 35, the integrated hole 27 can be accurately formed in terms of shape and position. That is, the opening of the oil hole 14 can be accurately formed in terms of shape and position.

[0083] ===Summary=== According to the present specification, the hole-opening tool 10 in the following manner is provided.

[0084] (Mode 1) Mode 1 includes a core material 21 and an outer material 22 located around the core material 21. An integrated hole 27 is formed in the outer material 22. When viewed in the longitudinal direction from the top DE side, the integrated hole 27 has: an insertion common region 25 for inserting the core material 21; and an oil hole region 26 communicating with the insertion common region 25. The oil hole 14 is formed by dividing the outer periphery of the core material 21 inserted into the insertion common region 25 and the edge of the oil hole region 26 of the outer material 22.

[0085] According to the above mode, the opening of the oil hole 14 can be accurately arranged at a specified position, and the situation where the oil hole 14 bends or undulates before reaching the opening can be suppressed.

[0086] (Mode 2) In Mode 2, the core material 21 and the outer material 22 are formed of different materials.

[0087] According to the above mode, the degree of freedom in selecting the materials used in the boring tool 10 can be increased.

[0088] (Mode 3) In Mode 3, the oil hole 14 is formed in a spiral shape along the length direction.

[0089] According to the above mode, the oil hole 14 can be formed along the shape of the discharge groove 11 formed in a spiral shape.

[0090] (Mode 4) In Mode 4, the oil hole 14 has a tapered portion 15 whose width becomes narrower as it goes from the outer periphery 17 side to the center 18 side when viewed along the length direction from the tip DE side.

[0091] According to the above mode, when viewed along the length direction from the tip DE side of the boring tool 10, the oil hole 14 can be efficiently arranged corresponding to the radial arrangement of the discharge groove 11 and the cutting edge 12 from the center 18.

[0092] (Mode 5) In Mode 5, the oil hole 14 has a widened portion 16 that is located on the center 18 side of the tapered portion 15 and whose width becomes wider as it goes to the center 18 side when viewed along the length direction from the tip DE side.

[0093] According to the above mode, even in the region on the center 18 side where the width of the oil hole 14 becomes narrower, the supply amount and pressure of the cutting oil can be increased.

[0094] (Mode 6) In Mode 6, a plurality of oil holes 14 are formed, and the plurality of oil holes 14 are located at positions rotationally symmetric with respect to the center 18 when viewed along the length direction from the tip DE side.

[0095] According to the above mode, the cutting oil can be uniformly supplied to the machining surface.

[0096] (Mode 7) In Mode 7, another oil hole 19 is formed in the core material 21.

[0097] According to the above mode, the supply amount of the cutting oil to the machining surface can be increased.

[0098] According to this specification, a blank 20 for the boring tool 10 in the following mode is provided.

[0099] (Mode 8) Mode 8 includes a core material 21 and an outer material 22 surrounding the core material 21. An integral hole 27 is formed in the outer material 22. When viewed in the longitudinal direction from the tip DE side, the integral hole 27 has an insertion region 25 for inserting the core material 21 and an oil hole region 26 communicating with the insertion region 25. An oil hole 14 is formed by dividing the outer periphery of the core material 21 inserted into the insertion region 25 and the edge of the oil hole region 26 of the outer material 22.

[0100] According to the above mode, the opening accuracy of the oil hole 14 can be well arranged at a specified position, and the bending or undulation of the oil hole 14 before reaching the opening can be suppressed.

[0101] According to this specification, a method for manufacturing a blank 20 for a hole-opening tool 10 of the following mode is provided.

[0102] (Mode 9) Mode 9 includes the following processes: a process of forming the core material 21; a process of forming the outer material 22, in which an integral hole 27 is formed in the outer material 22. When viewed in the longitudinal direction from the tip DE side, the integral hole 27 has an insertion region 25 for inserting the core material 21 and an oil hole region 26 communicating with the insertion region 25; and a process of inserting the core material 21 into the insertion region 25, and forming an oil hole 14 by dividing the outer periphery of the core material 21 inserted into the insertion region 25 and the edge of the oil hole region 26 of the outer material 22.

[0103] According to the above mode, the opening of the oil hole 14 can be well arranged at a specified position, and the situation of the oil hole bending or undulating before reaching the opening can be suppressed.

[0104] (Mode 10) In Mode 10, in the process of forming the outer material 22, the outer material 22 is formed by extrusion molding using a mold 30. The mold 30 has an insertion pin 34 for forming the insertion region 25 and an oil hole pin 35 for forming the oil hole region 26, and the insertion pin 34 is connected to the oil hole pin 35.

[0105] According to the above mode, the rigidity of the oil hole pin 35 can be improved.

[0106] (Mode 11) The insertion pin 34 is formed to extend parallel to the longitudinal direction of the hole-opening tool 10, and the oil hole pin 35 is formed to be spirally wound around the outer periphery of the insertion pin 34.

[0107] According to the above mode, the oil hole 14 of the hole-opening tool 10 can be formed in a spiral shape along the longitudinal direction.

[0108] === Others === The above-described embodiments are for facilitating the understanding of the present invention and are not for a limiting interpretation of the present invention. Additionally, it goes without saying that the present invention can be changed and improved without departing from its gist, and the present invention includes its equivalent solutions. Description of Reference Numerals

[0109] 10, 10A, 10B Drilling Tools 11 Discharge Groove 12 Cutting Edge 13 Rear Cutting Face 14, 19 Oil Holes 15 Tapered Portion 16 Widening Portion 17 Outer Periphery 18 Center 20, 20X Blanks 21, 21A Core Materials 22, 22B Outer Materials 23 Outer Peripheral Groove 24 Marking Portion 25 Insertion-Use Area 26 Oil Hole-Use Area 27 Integral Hole 30, 30X Molds 31 Extrusion Portion 32 Groove Forming Portion 33 Integral Hole Pin 33X Hole Pin 34 Insertion Pin 35 Oil Hole Pin 36 Powder

Claims

1. An opening tool, comprising a core material and an outer material disposed around the core material, wherein an integral hole is formed in the outer material, and when viewed in the longitudinal direction from the tip side, the integral hole has: an insertion region for inserting the core material therethrough; and an oil hole region communicating with the insertion region, wherein an oil hole is defined by the outer periphery of the core material inserted into the insertion region and the edge of the oil hole region of the outer material.

2. The hole-opening tool according to claim 1, wherein, The core material and the outer material are made of different materials.

3. The hole-opening tool according to claim 1, wherein, The oil hole is formed in a spiral shape along the longitudinal direction.

4. The hole-opening tool according to claim 1, wherein, The oil hole has a tapered portion whose width narrows as it goes from the outer peripheral side toward the center side when viewed in the longitudinal direction from the tip side.

5. The hole-opening tool according to claim 4, wherein, The oil hole has a widened portion that is located closer to the center side than the tapered portion and whose width widens as it goes toward the center side when viewed in the longitudinal direction from the tip side.

6. The hole-opening tool according to claim 1, wherein, A plurality of the oil holes are formed. When viewed in the longitudinal direction from the tip side, the plurality of oil holes are located at rotationally symmetric positions with respect to the center.

7. The hole-opening tool according to claim 1, wherein, Another oil hole is formed in the core material.

8. A blank for an opening tool, comprising a core material and an outer material disposed around the core material, wherein an integral hole is formed in the outer material, and when viewed in the longitudinal direction from the tip side, the integral hole has: an insertion region for inserting the core material therethrough; and an oil hole region communicating with the insertion region, wherein an oil hole is defined by the outer periphery of the core material inserted into the insertion region and the edge of the oil hole region of the outer material.

9. A method for manufacturing a blank for an opening tool, comprising the following steps: a step of forming a core material; a step of forming an outer material, in which an integral hole is formed in the outer material, and when viewed in the longitudinal direction from the tip side, the integral hole has an insertion region for inserting the core material therethrough and an oil hole region communicating with the insertion region; and a step of inserting the core material into the insertion region, and defining an oil hole by the outer periphery of the core material inserted into the insertion region and the edge of the oil hole region of the outer material.

10. The manufacturing method of the blank for the hole-opening tool according to claim 9, wherein, In the step of forming the outer material, the outer material is formed by extrusion molding using a mold, the mold has an insertion pin for forming the insertion region and an oil hole pin for forming the oil hole region, and the insertion pin is connected to the oil hole pin.

11. According to the method for manufacturing a blank for an opening tool as claimed in claim 10, wherein the insertion pin is formed to extend parallel to the longitudinal direction of the opening tool, and the oil hole pin is formed to be wound spirally around the outer periphery of the insertion pin.

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