Guiding pads and drill bits having guiding pads

Abstract

Provided are a guide pad having sufficient strength and a drill bit having the guide pad. The guide pad 300 has a first face 301, a second face 302 which is a flat face located opposite the first face 301, and a third face connecting the first face 301 and the second face 302. When viewed along a rotation center axis AX, the first face 301 is in a circular arc shape, a point at which an imaginary line VL passing through a center of the circular arc of the first face 301 and perpendicular to the second face 302 intersects the second face 302 is taken as a first point P1, and a point at which a center axis CX of a through hole 310 intersects the second face 302 is taken as a second point P2, the first point P1 is located closer to the third face than the second point P2.

Description

Technical Field

[0001] This invention relates to a guide pad and a drill bit having a guide pad. Background Technology

[0002] Drill bits are known as tools for forming small-diameter deep holes. A drill bit has a cutting edge at the front end of its slender body. Typically, only one cutting edge is provided, or multiple cutting edges are provided at asymmetrical positions around the axis of rotation. Furthermore, as described in Patent Document 1 below, a guide pad is provided at the front end of the drill bit body. In such a structure, the cutting edge is subjected to a directional force, and the guide pad can withstand this force while machining. During machining, the guide pad abuts against the inner surface of the hole in the material being cut, and the guide pad can suppress deformation of the body caused by the aforementioned force, thus enabling high-precision deep hole machining.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6849136

[0006] Technical issues

[0007] Because the drill bit body is slender, ensuring strength during manufacturing becomes a challenge. This is especially true in chip-changing drill bits, where in addition to the recess for mounting the guide pad, a recess for mounting the chip needs to be formed on the body, making it even more difficult to ensure the body's strength. As a countermeasure to ensure body strength, one could consider making the guide pad as thin as possible, and correspondingly increasing the wall thickness of the body.

[0008] However, if the guide pad is too thin, its strength will be reduced, potentially leading to breakage during machining. On the other hand, if the guide pad is thickened to ensure sufficient strength, the overall strength of the main body will be insufficient. As stated above, in the future, it will be difficult to achieve the machining of smaller diameter holes using drill bits using only the conventional structure.

[0009] The purpose of this invention is to provide a guide pad with sufficient strength and a drill bit having the guide pad. Summary of the Invention

[0010] One embodiment of the present invention is a guide pad for a drill bit, having a first surface, a second surface that is flat and located opposite the first surface, and a third surface connecting the first and second surfaces. A through hole for inserting a fastening component for fastening is formed, extending from the first surface to the second surface. When viewed along a predetermined direction, the first surface is arc-shaped. Taking the point where an imaginary line passing through the center of the arc of the first surface and perpendicular to the second surface intersects the second surface as a first point, and the point where the central axis of the through hole intersects the second surface as a second point, the first point is located closer to the third surface than the second point.

[0011] During the manufacturing process, the portion of the guide pad that is held between the fastening components and the main body, namely the portion between the inner wall surface of the through hole and the third surface, is subjected to significant stress.

[0012] In the guide pad with the above structure, viewed from the third surface, the second point corresponding to the position of the through hole is located further away than the first point. Therefore, it is possible to ensure that the distance between the inner surface of the through hole and the third surface is longer than in conventional structures. That is, the part under stress becomes a thick wall, sufficiently ensuring its strength. In this way, when the guide pad has the structure described above, the strength of the guide pad during processing can be sufficiently ensured without increasing the thickness of the guide pad.

[0013] As a preferred method, when viewed along a predetermined direction, the central axis of the through hole can also be tilted relative to the second surface, so that the closer to the outer periphery, the further away from the third surface.

[0014] As a more preferred embodiment, a fourth surface may be located opposite the third surface, with a portion of the fourth surface near the through hole protruding toward the opposite side of the through hole.

[0015] One embodiment of the drill bit of the present invention is a drill bit with a guide pad, the guide pad having: a first surface, which is an outer peripheral surface; a second surface, which is a flat surface located opposite the first surface and supported from the inside by the body of the drill bit; and a third surface, which is a surface extending along the rotational central axis of the body from the surface connecting the first surface and the second surface, abutting against a portion of the body, and having a through hole formed for inserting a fastening component and fastening it to the body, extending from the first surface to the second surface. When viewed along the rotational central axis of the body, the first surface is arc-shaped. Taking the point where an imaginary line passing through the center of the arc of the first surface and perpendicular to the second surface intersects the second surface as a first point, and the point where the central axis of the through hole intersects the second surface as a second point, the first point is located closer to the third surface than the second point.

[0016] As described above, this drill bit structure ensures sufficient strength of the guide pad during machining without increasing its thickness. Since it eliminates the need to create deep recesses in the main body for mounting the guide pad, the main body strength is not compromised.

[0017] As a more preferred approach, the main body may have a reinforcing wall that covers the front surface of the guide pad from the front end.

[0018] As a more preferred embodiment, a groove for guiding fluid to the front end is formed on the outer periphery of the main body, and the groove may also be formed to extend along the shape of the guide pad.

[0019] As a more preferred embodiment, the guide pad also has a fourth surface located opposite the third surface, and the groove can also be formed to extend along the fourth surface.

[0020] As a more preferred approach, the portion near the through hole in the fourth face protrudes toward the opposite side of the through hole, and the groove can also be formed as a portion that bends and extends along the fourth face.

[0021] According to the present invention, a guide pad with sufficient strength and a drill bit having the guide pad are provided. Attached Figure Description

[0022] Figure 1 This is a perspective view showing the overall structure of the drill bit according to this embodiment.

[0023] Figure 2 This is a perspective view showing the overall structure of the drill bit according to this embodiment.

[0024] Figure 3 This is a diagram depicting the drill bit of this embodiment as viewed from the front end along its rotational axis.

[0025] Figure 4 yes Figure 1 An enlarged schematic diagram of a portion thereof.

[0026] Figure 5 This is a schematic diagram of the guide pad structure in this embodiment.

[0027] Figure 6 yes Figure 5 A schematic diagram of the cross section along line VI-VI.

[0028] Explanation of main component symbols

[0029] Drill bit 10

[0030] Main body 100

[0031] Guide pad 300

[0032] Page 301 (First Page)

[0033] Page 2, 302

[0034] Page 303

[0035] Through hole 310

[0036] Rotation center axis AX Detailed Implementation

[0037] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding, the same reference numerals will be used as much as possible to denote the same constituent elements in the drawings, and repeated descriptions will be omitted.

[0038] The structure of the drill bit 10 in this embodiment will be described. Figure 1 and Figure 2 This is a perspective view showing the overall structure of drill bit 10. Figure 3 yes Figure 1 The diagram depicts the drill bit 10 as viewed from the front end side along its rotational axis AX. Figure 4 yes Figure 1 An enlarged schematic diagram of a portion thereof, specifically an enlarged schematic diagram of the front end portion of drill bit 10.

[0039] like Figure 1 As shown, the drill bit 10 includes a body 100, a cutting blade 200, and a guide pad 300.

[0040] The main body 100 is a component that constitutes the general whole of the drill bit 10 and is made of steel. The main body 100 has a holding part 120 and a cutting part 110. The holding part 120 is a part along the longitudinal direction of the main body 100 and is held by a machine tool (not shown).

[0041] For ease of explanation, the main body 100 has one end side of the gripped portion 120, which will also be referred to as the "base end side" below. In addition, the opposite side of the base end side will also be referred to as the "front end side" below.

[0042] The cutting portion 110 is the part of the main body 100 closer to the front end than the gripped portion 120, and is used for cutting the material being cut. The cutting portion 110 is formed to extend linearly from the gripped portion 120 towards the front end. Figure 3 As shown, the cutting section 110 is slightly cylindrical, and a discharge groove 111 is formed on its side. The discharge groove 111 is a groove that guides and discharges coolant during the machining process, and is formed to extend from the front end side to the base end side. The coolant is a fluid supplied from the machine tool side during the machining process for purposes such as discharging chips, cooling tools and cut materials, lubrication, and rust prevention.

[0043] The cutting insert 200 is the portion with a cutting edge 210, and is formed of a superhard material. For example... Figure 2 As shown, the cutting insert 200 is fastened by screw 11 to a position near the end of the front end side of the inner surface of the discharge groove 111. The cutting edge 210 of the cutting insert 200 protrudes further from the front end of the cutting section 110 towards the front end side. When machining the workpiece, the main body 100 rotates about the rotation center axis AX. Its rotation direction is... Figure 3The direction indicated by the middle arrow. When the main body 100 rotates, the material being cut is cut by contacting the cutting edge 210, thereby forming a deep hole in the material being cut. In the drill bit 10 of this embodiment, as described above, the cutting edge 210 portion is a replaceable independent component, constituting a so-called "chip-replaceable" tool.

[0044] In this embodiment, the main body 100 of the drill bit 10 is a so-called "single flute-shaped" tool, forming only one discharge groove 111. Correspondingly, only one cutting blade 200 is provided.

[0045] The guide pad 300 is a component that suppresses deformation of the main body 100 by abutting against the inner surface of the hole during machining. The hole formed in the workpiece by the drill bit 10 is also referred to as the "machined hole". By setting the guide pad 300, machining can be performed while ensuring the straightness and roundness of the machined hole.

[0046] In this embodiment, where the cutting edge 210 is only located at one point in the circumferential direction, a deflection force will be applied to the cutting edge 210 during machining. Therefore, by providing a guide pad 300 at a location capable of withstanding this force, deformation of the main body 100 during machining can be suppressed, and as described above, the straightness and roundness of the machined hole can be ensured.

[0047] like Figure 4 As shown, a guide pad 300 is mounted on the outer circumferential surface of the cutting part 110 near the end of the cutting part 110 at its front end. In this embodiment, two guide pads 300 are provided, arranged circumferentially. Each guide pad 300 is fastened to the cutting part 110 by a screw 12, which serves as a fastening component. Furthermore, the number of guide pads 300 mounted on the cutting part 110 can be one or more.

[0048] like Figure 4 As shown, in the cutting section 110, a discharge port 112 and a groove 113 are formed near the portion where the guide pad 300 is installed.

[0049] The outlet 112 is a hole used to supply coolant during machining. A flow path (not shown) for guiding coolant is formed inside the main body 100. One end of this flow path opens at the base end of the held portion 120. The outlet 112 is an opening formed at the other end of this flow path. During machining, coolant is supplied from the machine tool to the flow path. The coolant is discharged from the outlet 112 through the flow path and then flows into the tank 113.

[0050] The groove 113 is formed along the outer peripheral surface of the cutting section 110 to guide the coolant discharged from the outlet 112 to the cutting edge 210 at the front end. During machining, the coolant flows to the cutting edge 210 through the space between the inner surface of the groove 113 and the inner surface of the machining hole. Then, the coolant, together with the chips generated during machining, is discharged outside the machining hole through the discharge groove 111.

[0051] The specific structure of the guide pad 300 is explained. Figure 5 This is a schematic diagram of the guide pad 300 as viewed from the outer periphery. Figure 6 yes Figure 5 A schematic cross-sectional view along line VI-VI. This cross-section is the surface containing the central axis CX of the through hole 310, which will be described later. Figure 5 In the middle, the lower side is the front end side, and the upper side is the base end side.

[0052] exist Figure 5 In this context, the surface marked "301" is the outer peripheral surface when mounted on the main body 100, that is, the surface opposite to and abutting the inner surface of the machined hole. Hereinafter, this surface will also be referred to as "first surface 301". Figure 6 As shown, when the guide pad 300 mounted on the main body 100 is viewed along the rotation center axis AX (i.e., viewed along a predetermined direction), the first surface 301 is an arc-shaped surface. The central axis CT of the first surface 301, which is an arc-shaped surface, is referenced. Figure 6 The arc is an axis extending longitudinally along the body 100, roughly coinciding with the rotation center axis AX. Furthermore, the curvature of this arc is approximately equal to the curvature of the inner surface of the machined hole.

[0053] exist Figure 6 In the diagram, the surface marked "302" is located opposite the first surface 301, that is, the surface inside the first surface 301, and is supported from the inside by the cutting part 110. Hereinafter, this surface will also be referred to as "second surface 302". Second surface 302 is a flat surface.

[0054] exist Figure 5 In the diagram, the face marked "303" is one of the faces connecting the first face 301 and the second face 302. Figure 5 The face extending along the rotation center axis AX on the right side. Hereinafter, this face will also be referred to as "third face 303".

[0055] exist Figure 5 In the diagram, the face marked "304" is located opposite the third face 303. Hereinafter, this face will also be referred to as "fourth face 304". Figure 5As shown, the third surface 303 is generally flat, while the fourth surface 304 is a portion of it (the part marked "304A") that protrudes. Hereinafter, this portion will also be referred to as "protrusion 304A". Protrusion 304A is the portion of the fourth surface 304 near the through hole 310, which will be described later, and protrudes toward the opposite side of the through hole 310.

[0056] exist Figure 5 In the diagram, the surface marked "305" is one of the surfaces connecting the first surface 301 and the second surface 302, and it is the frontmost surface of the guide pad 300. Hereinafter, this surface will also be referred to as "front surface 305".

[0057] exist Figure 5 In the diagram, the surface marked "306" is one of the surfaces connecting the first surface 301 and the second surface 302, and it is the most base-side surface in the guide pad 300. Hereinafter, this surface will also be referred to as "base-side surface 306".

[0058] A through hole 310 is formed in the guide pad 300. The through hole 310 is formed for inserting the screw 12 and fastening it to the cutting part 110, and is formed to penetrate the guide pad 300 from the first surface 301 to the second surface 302.

[0059] Although the through hole 310 is roughly circular, its inner diameter varies when viewed as a whole. For example... Figure 6 As shown, a tapered portion 311 is formed on the inner surface of the through hole 310. The inner diameter from the tapered portion 311 to the first surface 301 side is larger than the inner diameter from the tapered portion 311 to the second surface 302 side. The tapered portion 311 may also be a portion where the inner diameter of the through hole 310 gradually decreases from the outer peripheral side to the inner peripheral side (body 100 side). The tapered portion 311 is the portion where force from the screw 12 is applied when fastening the guide pad 300.

[0060] exist Figure 6 In the diagram, the symbol "CX" indicates the central axis of the through hole 310. This central axis will also be referred to as "central axis CX" below. In a cross-section perpendicular to the central axis CX, the center of the circle representing the through hole 310 coincides with the central axis CX. Furthermore, even if the cross-sectional shape of the through hole 310 is not strictly circular, when it is fastened by inserting a screw 12 into the through hole 31, the axis coinciding with the central axis of the screw 12 can also be defined as the "central axis CX of the through hole 310".

[0061] like Figure 6 As shown, when viewed along the rotational center axis AX, the center axis CX in this embodiment is inclined relative to the second surface 302, causing it to tend towards the outer periphery (in Figure 6 The further away from the third side (303) the middle side (the upper side) is.

[0062] When the screw 12 is inserted into the through hole 310 and tightened by the screw 12, the guide pad 300 is subjected to an directional force. Figure 5 The force on the right and upper sides of the through hole 310 is applied to the cutting part 110. In other words, the inner surface of the through hole 310 is formed so that the aforementioned force is applied during fastening.

[0063] Although not shown in the diagram, the cutting portion 110 is provided with a first positioning portion that abuts against the third surface 303 during tightening and a second positioning portion that abuts against the base end surface 306 during tightening. When tightened by the screw 12, since the guide pad 300 is subjected to the force described above, the third surface 303 of the guide pad 300 abuts against the first positioning portion, and the base end surface 306 of the guide pad 300 abuts against the second positioning portion. As a result, the guide pad 300 is positioned by these two surfaces and installed in the correct position.

[0064] With the fastened state completed, a portion of the third surface 303 (especially, Figure 6 The portion between the chamfered portion (marked as 303A) and the tapered portion 311 is sandwiched between the screw 12 and the cutting portion 110, and this portion is subjected to greater stress.

[0065] However, since the body 100 of the drill bit 10 used for deep hole machining is slender, ensuring strength during machining becomes a problem. In particular, in this embodiment of a chip-replaceable drill bit, in addition to the recess for mounting the guide pad 300, a recess for mounting the cutting insert 200 also needs to be formed on the body 100, making it even more difficult to ensure the strength of the body 100. As a countermeasure to ensure the strength of the body 100, for example, it is possible to make the guide pad 300 as thin as possible, and correspondingly increase the wall thickness on the body 100 side.

[0066] However, if the guide pad 300 is too thin, its strength will decrease. Therefore, the portion of the guide pad 300 subjected to the stress caused by fastening as described above, or its vicinity, may break during processing. On the other hand, if the guide pad 300 is thickened to adequately ensure its strength, the resulting recess in the body 100 will have a deep strain, still resulting in insufficient strength of the body 100.

[0067] Therefore, in the guide pad 300 of this embodiment, by focusing on the position of the through hole 310, the strength of the guide pad 300 during processing can be fully ensured without increasing the thickness of the guide pad 300.

[0068] Regarding the effort put in, please continue to refer to... Figure 6 The following explanation is provided. The imaginary line VL shown in the figure is an imaginary line drawn through the center of the arc of the first surface 301 (i.e., the central axis CT) and perpendicular to the second surface 302. Figure 6 In the cross-section, the point where the imaginary line VL intersects with the second surface 302 is hereinafter referred to as "the first point P1". Additionally, in Figure 6 In the cross section, the point where the central axis CX of the through hole 310 intersects with the second surface 302 is also referred to as "the second point P2" below.

[0069] As described above, in this embodiment, the first point P1 is located closer to the third surface 303 than the second point P2. In other words, from the perspective of the third surface 303, the second point P2, corresponding to the position of the through hole 310, is located farther than the first point P1.

[0070] In the conventional structure, since the guide pad 300 is symmetrical about the same width across the through hole 310, it is defined as the position of the first point P1 and the position of the second point P2 as described above. Figure 6 The cross-sections shown are consistent with each other. In this embodiment, as described above, viewed from the third surface 303, the second point P2 is located further away than the first point P1. As a result, the distance L from the tapered portion 311 to the portion marked with numeral 303A in the third surface 303 is longer in this embodiment than in conventional structures. That is, in the guide pad 300, the wall thickness of the portion subjected to greater stress due to fastening is thicker than before. This sufficiently ensures the strength of this portion.

[0071] In this embodiment, instead of increasing the thickness of the guide pad 300, efforts are made to ensure the strength of the guide pad 300 during processing by focusing on the position of the through hole 310, etc.

[0072] Furthermore, in this embodiment, as described above, the central axis CX of the through hole 310 is inclined relative to the second surface 302. Therefore, compared to a structure where the central axis CX extends parallel to the imaginary line VL from the position of the second point P2, a longer distance L is ensured, which in turn further improves the strength of the guide pad 300.

[0073] As referenced above Figure 5 In this embodiment, the portion (protrusion 304A) near the through hole 310 in the fourth surface 304 protrudes towards the side opposite to the through hole 310. This ensures sufficient protection. Figure 5 Compared to the wall thickness of the left side portion of the through hole 310, this design prevents the portion from becoming too thin and breaking.

[0074] Explain the efforts made in other parts. For example... Figure 4As shown, a reinforcing wall 114 is formed near the end of the cutting section 110 on the front end side. The reinforcing wall 114 is a wall that protrudes outward from the peripheral side at a position adjacent to the guide pad 300. The reinforcing wall 114 covers the front end face 305 of the guide pad 300 from the front end side. By providing such a reinforcing wall 114, the strength of the front end side portion of the cutting section 110 is ensured.

[0075] As referenced above Figure 4 The outer peripheral surface of the cutting portion 110 is formed with a groove 113 for guiding coolant toward the front end. As shown in the figure, the groove 113 is formed to extend along the outline of the guide pad 300, specifically along the fourth surface 304 of the guide pad 300. The groove 113 is formed to extend in a curved manner along the shape of the fourth surface 304 that protrudes in a portion (protrusion 304A). By positioning the groove 113 in such a way and having such a shape, the reduction in rigidity of the body 100 is minimized with the formation of the groove 113.

[0076] The present embodiment has been described above with reference to specific embodiments. However, this disclosure is not limited to these specific embodiments. Even if those skilled in the art make appropriate design changes to these specific embodiments, as long as they possess the features of this disclosure, they are included within the scope of this disclosure. The elements, their configurations, conditions, shapes, etc., included in the above-described specific embodiments are not limited to those illustrated and can be appropriately modified. Regarding the elements included in the above-described specific embodiments, the combination can be appropriately changed as long as no technical contradiction arises.

Claims

1. A guide pad, used for drill bits, characterized in that, have: First impression; The second surface, which is flat and located opposite the first surface; The third surface connects the first surface and the second surface. The fourth surface located opposite the third surface; The through hole for inserting and fastening components is formed to extend from the first surface to the second surface. In a cross-sectional view along the central axis from the third surface to the fourth surface and passing through the through hole, the first surface is arc-shaped. When the point where the imaginary line passing through the center of the arc of the first surface and perpendicular to the second surface intersects the second surface is taken as the first point, and the point where the central axis of the through hole intersects the second surface is taken as the second point, the first point is located closer to the third surface than the second point. In a cross-sectional view along the direction from the third surface to the fourth surface and passing through the central axis of the through hole, the central axis of the through hole is inclined relative to the second surface, so that the closer it is to the first surface, the further away it is from the third surface.

2. The guide pad according to claim 1, characterized in that, The portion near the through hole in the fourth surface protrudes toward the opposite side of the through hole.

3. A drill bit having a guide pad, characterized in that, The guide pad has: The first surface is the outer peripheral surface when the guide pad is installed on the body of the drill bit; The second surface is a flat surface located opposite the first surface, and is supported from the inside by the body of the drill bit; The third surface is a surface that extends along the rotational axis of the main body, connecting the first surface and the second surface, and abuts against a portion of the main body. A through hole for inserting and fastening fasteners into the body is formed to extend from the first surface to the second surface. When viewed along the rotation center axis of the main body, the first surface is arc-shaped. When the point where the imaginary line passing through the center of the arc of the first surface and perpendicular to the second surface intersects the second surface is taken as the first point, and the point where the center axis of the through hole intersects the second surface is taken as the second point, the first point is located closer to the third surface than the second point. When viewed along the rotational axis of the drill bit, the central axis of the through hole is inclined relative to the second surface, thus the closer it is to the first surface, the further it is from the third surface.

4. The drill bit according to claim 3, characterized in that, The main body is provided with a reinforcing wall that covers the front end surface of the guide pad from the front end side.

5. The drill bit according to claim 3 or 4, characterized in that, A groove for guiding fluid toward the front end is formed on the outer periphery of the main body, the groove being formed to extend along the shape of the guide pad.

6. The drill bit according to claim 5, characterized in that, The guide pad also has a fourth surface located opposite the third surface, and the groove is formed to extend along the fourth surface.

7. The drill bit according to claim 6, characterized in that, The portion near the through hole in the fourth surface protrudes toward the opposite side of the through hole, and the groove is formed as a portion extending in a curved manner along the fourth surface.

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