Drill and cutting process

Abstract

There is a demand for drills with high rigidity and good chip evacuation while reducing chipping on the tip side. A drill according to one aspect of the present disclosure has a body extending along a rotation axis. The body has a cutting edge, a thinning groove, a discharge groove, a tip surface, a first honing surface, and a second honing surface connected to the first honing surface. The first honing surface has a first portion which is connected to the second honing surface and the width of which in tip view progressively increases toward the second honing surface. The second honing surface has a second portion which is connected to the first honing surface and the width of which in tip view progressively increases toward the first honing surface.

Description

[Technical Field]

[0001] This aspect relates to a method for manufacturing a drill and a cutting. [Background technology]

[0002] Known drills used in milling a workpiece include those described in Patent Documents 1 and 2. As in the drills described in Patent Documents 1 and 2, chamfering or honing the boundary between the flank and flute located at the tip of the drill can be effective in avoiding stress concentration that occurs during cutting and improving the chip removal performance of the drill.

[0003] Specifically, the drill described in Patent Document 1 has a curved flank, which has the great advantage of reducing the load on the drill tip during drilling. Also, Patent Document 2 discloses that the heel portion located at the tip of the drill is rounded with an R surface to further improve chip evacuation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2001 / 036134 [Patent Document 2] Publication number 03-040499 Summary of the Invention

[0005] A drill according to one embodiment of the present disclosure has a rod-shaped body extending from a tip end to a rear end along a rotation axis. The body has a cutting edge located near the tip end, a thinning groove extending from the cutting edge toward the rear end, a discharge groove located radially outward of the thinning groove and extending from the cutting edge toward the rear end, a tip end surface adjacent to the thinning groove and the discharge groove in front of the rotation axis, a first honing surface located at the intersection of the tip end surface and the thinning groove, and a second honing surface located at the intersection of the tip end surface and the discharge groove and connected to the first honing surface. The first honing surface has a first portion connected to the second honing surface and whose width in a tip view increases toward the second honing surface. The second honing surface has a second portion connected to the first honing surface and whose width in a tip view increases toward the first honing surface. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a drill according to an embodiment. [Figure 2] FIG. 2 is an enlarged view of an area A1 shown in FIG. [Figure 3] FIG. 3 is a plan view of the drill shown in FIG. 2 as viewed from a direction B1. [Figure 4] FIG. 3 is a plan view of the drill shown in FIG. 2 as viewed from a direction B2. [Figure 5] FIG. 5 is an enlarged view of an area A2 shown in FIG. [Figure 6] FIG. 5 is an enlarged view of an area A2 shown in FIG. [Figure 7] 3 is a schematic diagram showing one step of a method for manufacturing a machined product according to one embodiment. FIG. [Figure 8] 3 is a schematic diagram showing one step of a method for manufacturing a machined product according to one embodiment. FIG. [Figure 9] 3 is a schematic diagram showing one step of a method for manufacturing a machined product according to one embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, a drill according to an embodiment will be described in detail with reference to the drawings. For ease of explanation, the drawings below show only the main components constituting the embodiment in a simplified form. Therefore, the drill may include any components not shown in the drawings referred to in this specification. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions and dimensional ratios of the components.

[0008] 1, the drill 1 according to the embodiment of the present disclosure has a substantially cylindrical body 3 extending from a front end 3A to a rear end 3B along a rotation axis O1. The body 3 can perform drilling while rotating in a rotation direction O2 around the rotation axis O1.

[0009] 1, the body 3 has a cutting portion 5 located on the tip 3A side and a shank portion 7 located on the rear end 3B side of the cutting portion 5. There are no particular limitations on the shapes of the cutting portion and the shank portion, but in the drill of this embodiment, since the body is generally cylindrical, the cutting portion and the shank portion are also generally cylindrical.

[0010] The cutting portion 5 includes a portion that comes into contact with a workpiece, and this portion plays a major role in cutting the workpiece. The shank portion 7 is a portion that is gripped by a rotating spindle or the like in a machine tool, and may be designed according to the shape of the spindle.

[0011] The cutting portion 5 and the shank portion 7 may be formed of separate members or may be formed integrally. Generally, a drill 1 in which the cutting portion 5 and the shank portion 7 are formed of separate members is called a replaceable-tip type, and a drill 1 in which the cutting portion 5 and the shank portion 7 are formed integrally is called a solid type.

[0012] The outer diameter of the main body 3 in this embodiment may be set to, for example, 0.5 mm to 4 mm. Furthermore, when the length in the direction in which the rotation axis O1 extends is L and the outer diameter is D, the relationship between L and D in the main body 3 in this embodiment may be set to, for example, L = 1D to 10D. When the outer diameter of the cutting portion 5 and the outer diameter of the shank portion 7 are different, the outer diameter of the cutting portion 5 is set to the outer diameter D of the main body 3.

[0013] The cutting portion 5 has a cutting edge 9, a thinning groove 11, a discharge groove 15, a tip surface 17, and an outer peripheral surface 19. As shown in FIGS. 2 and 3, the cutting edge 9 is located on the tip 3A side of the body 3. Since the cutting edge 9 is generally called a tip edge, in the following description, the cutting edge 9 may also be referred to as a tip edge. FIG. 3 is a plan view of the drill 1 viewed from a direction perpendicular to the rotation axis O1, which may also be referred to as a side view. The thinning groove 11 and the discharge groove 15 are grooves that extend from the cutting edge 9 toward the rear end 3B. The tip surface 17 is located on the tip 3A side and faces the tip 3A. The outer peripheral surface 19 is a surface located on the outer peripheral side of the cutting portion 5.

[0014] When the cutting portion 5 has one or more cutting edges 9, the number of thinning grooves 11, discharge grooves 15, tip faces 17, and outer peripheral surfaces 19 may correspond to the number of cutting edges 9. In the example shown in Fig. 2, the number of cutting edges 9 is two, and the numbers of thinning grooves 11, discharge grooves 15, tip faces 17, and outer peripheral surfaces 19 are also two each.

[0015] As shown in FIG. 4, the cutting edge 9 has a main cutting edge 21 extending from the rotation axis O1 side toward the outer peripheral surface 19 side. The end of the main cutting edge 21 on the rotation axis O1 side is located closer to the tip 3A than the end of the main cutting edge 21 on the outer peripheral surface 19 side. The main cutting edge 21 refers to a portion of the cutting edge 9 that is located on the ridge where the tip face 17 and the discharge flute 15 intersect and has a positive rake angle. In this case, the tip face 17 functions as a clearance face, and the discharge flute 15 functions as a rake face. FIG. 4 is a plan view of the drill 1 viewed from the tip 3A side along the rotation axis O1, and may also be referred to as a front view or a tip view.

[0016] As shown in an example in Figure 4, when the main body 3 is viewed from the tip, the cutting edge 9 has a chisel edge 23 including the rotation axis O1 and a thinning edge 25 extending from the chisel edge 23 toward the outer peripheral surface 19 of the main body 3.

[0017] The thinning edge 25 refers to a portion of the cutting edge 9 that is located on the ridge where the tip face 17 and the thinning groove 11 intersect, and where the rake angle is a negative value. In the example shown in Fig. 4, the thinning edge 25 is located closer to the rotation axis O1 than the main cutting edge 21, and is connected to the main cutting edge 21. When viewed from the tip, the chisel edge 23, thinning edge 25, and main cutting edge 21 of the cutting edge 9 are aligned in this order from the rotation axis O1 toward the outer periphery.

[0018] The chisel edge 23 refers to a portion of the cutting edge 9 that is located on the ridge where the plurality of tip surfaces 17 intersect when the cutting portion 5 has a plurality of tip surfaces 17, and functions as a pseudo cutting edge. In the example shown in Figure 4, the chisel edge 23 intersects with the rotation axis O1 and is connected to the thinning edge 25.

[0019] Here, when the cutting portion 5 has a plurality of cutting edges 9, one of the plurality of cutting edges 9 is designated as a first cutting edge 9A, and the cutting edge 9 located forward of the first cutting edge 9A in the rotational direction O2 is designated as a second cutting edge 9B. In the example shown in Fig. 4, the first cutting edge 9A and the second cutting edge 9B each have a main cutting edge 21, a chisel edge 23, and a thinning edge 25. Furthermore, when viewed from the tip, the second cutting edge 9B is located forward of the first cutting edge 9A in the rotational direction O2 via the thinning groove 11 (or discharge groove 15) and the tip face 17.

[0020] When the cutting portion 5 has three or more cutting edges 9, the cutting edge 9 located forward of the first cutting edge 9A in the rotation direction O2 and closest to the first cutting edge 9A forward in the rotation direction O2 is defined as the second cutting edge 9B.

[0021] The thinning groove 11 is a groove located on the side of the tip 3A of the cutting part 5. The thinning groove 11 is provided to reduce the core thickness on the side of the tip 3A of the cutting part 5. For this reason, the surface located on the rear side in the rotation direction O2 is inclined so as to move toward the front in the rotation direction O2 as it moves toward the rear end 3B. The thinning groove 11 may be formed by grinding with a grindstone or the like. In the example shown in FIG. 4, the cutting part 5 has a plurality of thinning grooves 11 separated from each other via the tip surface 17 when viewed from the tip.

[0022] When the cutting portion 5 has a plurality of thinning grooves 11, one of the plurality of thinning grooves 11 that extends from the first cutting edge 9A toward the rear end 3B is referred to as a first thinning groove 11A. Also, one of the plurality of thinning grooves 11 that extends from the second cutting edge 9B toward the rear end 3B is referred to as a second thinning groove 11B. The second thinning groove 11B is located forward of the first thinning groove 11A in the rotational direction O2.

[0023] The thinning groove 11 may have a thinning surface 13 located on the front side in the rotational direction O2. There are no particular limitations on the shape of the thinning surface 13, but it may be flat. When the cutting portion 5 has multiple thinning grooves 11, the cutting portion 5 may have multiple thinning surfaces 13. In the example shown in FIG. 4, the first thinning groove 11A has a first thinning surface 13A, and the second thinning groove 11B has a second thinning surface 13B.

[0024] The discharge grooves 15 are generally called flutes and are located on the outer periphery side of the thinning grooves 11. The discharge grooves 15 are provided to discharge chips toward the rear end 3B. Therefore, the surface located on the rear side in the rotation direction O2 generally slopes toward the rear side in the rotation direction O2 as it approaches the rear end 3B. The discharge grooves 15 also extend to the rear end 3B side of the thinning grooves 11. The thinning grooves 11 and the discharge grooves 15 are open to each other and connected. In the example shown in FIG. 1, the discharge grooves 15 extend from the cutting edge 9 toward the rear end 3B in a twisted manner around the rotation axis O1, but they may also extend straight.

[0025] In the present disclosure, "extending in a twisted manner" means that the discharge groove 15 extends in a generally twisted manner from the cutting edge 9 toward the rear end 3B. As shown in FIG. 1, the discharge groove 15 may extend in a spiral shape. The discharge groove 15 may have a partially non-twisted portion. When the discharge groove 15 extends in a twisted manner, the twist angle of the discharge groove 15 is not limited to a specific value and may be set to, for example, approximately 10° to 35°.

[0026] 4, the cutting part 5 has a plurality of discharge grooves 15 spaced apart from each other across the tip end surface 17. In this case, of the plurality of grooves, the one extending from the first cutting edge 9A toward the rear end 3B is referred to as the first discharge groove 15A, and the one extending from the second cutting edge 9B toward the rear end 3B is referred to as the second discharge groove 15B. The second discharge groove 15B is located forward of the first discharge groove 15A in the rotational direction O2.

[0027] The tip surface 17 may have a plurality of inclined planes or may have a curved shape. The tip surface 17 may also have an opening 27 through which the coolant is discharged. In this case, the coolant passes through a flow path inside the main body 3 and is discharged from the opening 27.

[0028] 4, the thinning grooves 11 and the discharge grooves 15 are located between the plurality of tip surfaces 17. In this case, one of the plurality of tip surfaces 17 is defined as a first tip surface 17A, and the tip surface 17 located forward of the first tip surface 17A in the rotational direction O2 is defined as a second tip surface 17B.

[0029] The first tip surface 17A is adjacent to the first thinning groove 11A and the first discharge groove 15A on the front side in the rotational direction O2. Specifically, as shown in FIG. 4, when viewed from the front end, the first tip surface 17A is located forward of these grooves in the rotational direction O2 and is in contact with these grooves. The first tip surface 17A may also be connected to the second cutting edge 9B on the rear side in the rotational direction O2. The first tip surface 17A is a surface that extends from the second cutting edge 9B toward the first thinning groove 11A and the first discharge groove 15A, and therefore may also be referred to as a clearance surface for the second cutting edge 9B.

[0030] The above relationship also holds true when the first tip surface 17A, the first thinning groove 11A, the first discharge groove 15A, and the second cutting edge 9B are replaced with the second tip surface 17B, the second thinning groove 11B, the second discharge groove 15B, and the first cutting edge 9A, respectively.

[0031] The outer peripheral surface 19 is a surface area located at the outer edge of the cutting part 5. The outer peripheral surface 19 may have a margin or clearance. In the example shown in FIG. 2, the cutting part 5 has multiple outer peripheral surfaces 19 separated from each other by discharge grooves 15. When the cutting part 5 has multiple outer peripheral surfaces 19, one of the multiple outer peripheral surfaces 19 is designated as a first outer peripheral surface 19A, and the outer peripheral surface 19 located forward of the first outer peripheral surface 19A in the rotational direction O2 is designated as a second outer peripheral surface 19B.

[0032] When the first outer peripheral surface 19A is rotated around the rotation axis O1, the first outer peripheral surface 19A may overlap with the second outer peripheral surface 19B. Specifically, in the example shown in Fig. 4, the outer peripheral surfaces 19 are rotationally symmetrical by 180° about the rotation axis O1. The above relationship also holds true when the first outer peripheral surface 19A is replaced with the first cutting edge 9A, the first thinning groove 11A, the first discharge groove 15A, or the first tip surface 17A.

[0033] Cutting portion 5 has a first honing surface 29 located at the intersection of first tip surface 17A and first thinning groove 11A. Cutting portion 5 also has a second honing surface 31 located at the intersection of first tip surface 17A and first discharge groove 15A. As shown in Fig. 4, when viewed from the tip, first honing surface 29 and second honing surface 31 each extend from the side of rotation axis O1 toward the outer periphery of main body 3.

[0034] In addition, first honing surface 29 is connected to second honing surface 31. The portion where first honing surface 29 and second honing surface 31 connect is referred to as first connecting portion P1. First honing surface 29 and second honing surface 31 form a single honing surface. Second honing surface 31 may be connected to first outer peripheral surface 19A.

[0035] The first honing surface 29 has a first portion 33. The first portion 33 is a portion located on the outer periphery of the first honing surface 29, and is connected to the second honing surface 31 at a first connecting portion P1.

[0036] The width of first portion 33 increases toward second honing surface 31. Here, the width of first portion 33 refers to width W1 in a direction perpendicular to an imaginary line N passing through end point T1 of first honing surface 29 on the rotation axis O1 side and end point T2 on the outer periphery side of second honing surface 31 when viewed from the tip, as shown in FIG. 5. Width W1 of first portion 33 may be 5 μm to 30 μm. Furthermore, the amount of change in width W1 of first portion 33 may be 3 μm to 25 μm. The sizes of widths (W2 to W5, WP1, WP2) described below will also be specified using the above method.

[0037] When viewed from the tip, if the width of the outer circumferential side of the second honing surface 31 is large and the end point cannot be determined, as shown in Figure 5, the midpoint of the width of the outer circumferential side of the second honing surface 31 in the circumferential direction of the rotation axis O1 is taken as the outer circumferential end point T2 of the second honing surface 31.

[0038] Furthermore, when the width of first portion 33 increases as it approaches second honing surface 31, it does not necessarily mean that the width of first portion 33 increases continuously, and there may be a portion where the width is constant. Even when the width increases as it approaches other portions (second portion 35 to fifth portion 51) described below, in other words, in a certain direction, it does not necessarily mean that the width of each portion increases continuously, and there may be a portion where the width is constant.

[0039] The second honing surface 31 has a second portion 35. As shown in Fig. 5, the second portion 35 is a portion of the second honing surface 31 located on the side of the rotation axis O1, and is connected to the first honing surface 29 at a first connecting portion P1. The second portion 35 is connected to the first portion 33 at the first connecting portion P1.

[0040] The width of second portion 35 as viewed from the tip increases toward first honing surface 29. Width W2 of second portion 35 shown in Fig. 5 may be 3 µm to 30 µm. Furthermore, the amount of change in width W2 of second portion 35 may be 2 µm to 25 µm.

[0041] Chips generated during cutting may collide with the boundary between the flank and the thinning groove, and with the boundary between the flank and the discharge groove 15, causing chipping at these boundary portions. This is because the boundary portions have angular shapes, which tend to reduce the strength of the boundary portions. In particular, the areas near the intersections of the flank, the thinning groove, and the discharge groove tend to have protruding shapes such as pointed or convex curved shapes, making chipping collisions more likely to occur.

[0042] When such chipping occurs, the center of gravity of the drill shifts, impairing the drill's stability in moving straight ahead during cutting. This reduces the accuracy of cutting, and may force the drill to be replaced early.

[0043] One way to solve this problem is to provide a honed surface on the flank, which can prevent chipping at the boundary due to collision with the chips and extend the tool life.

[0044] However, if the honing surface is excessively large relative to the flank, the thickness of the drill body will be thinned, which may reduce the rigidity of the drill. In other words, if the honing surface is excessively large, the tool life may be shortened. In addition, in the above case, chips that collide with the honing surface may flow toward the flank instead of into the flute, which may worsen the chip discharge performance of the drill.

[0045] In the drill 1 according to this embodiment, the width of the first portion 33 on the first honing surface 29 increases as it approaches the second honing surface 31, and the width of the second portion 35 on the second honing surface 31 increases as it approaches the first honing surface 29.

[0046] The above-described configuration of the drill 1 allows the width of the honing surface to be relatively large at the intersection of the first tip face 17A, the first thinning groove 11A, and the first discharge groove 15A, thereby reducing chipping in areas prone to chip collision.

[0047] Furthermore, since excessive honing of the flank face is avoided, the thickness of the main body 3 is ensured, making it easier to maintain the rigidity of the drill 1, and at the same time, it also has excellent performance in terms of chip removal.

[0048] Therefore, the drill of this embodiment is a drill that reduces the occurrence of breakage due to collision with chips, maintains the rigidity of the body, and achieves good chip discharge properties.

[0049] When viewed from the tip, first portion 33 may extend rearward in the rotational direction O2 of the rotation axis O1 as it approaches second honing surface 31, and second portion 35 may extend rearward in the rotational direction O2 of the rotation axis O1 as it approaches first honing surface 29. In the example shown in Fig. 4, the honing surface comprising first honing surface 29 and second honing surface 31 has a convex shape that bulges rearward in the rotational direction O2 with first connecting portion P1 as its apex.

[0050] In such a case, the area near the intersection of the first tip surface 17A, the first thinning groove 11A, and the first discharge groove 15A will have a more protruding shape, so by providing the first portion 33 and the second portion 35, the occurrence of defects is reduced.

[0051] 5, the entire first honing surface 29 may be the first portion 33. In other words, the width of the first honing surface 29 increases as it approaches the second honing surface 31.

[0052] Chips generated during cutting are discharged along the thinning grooves 11 and discharge grooves 15, resulting in a twisted shape centered on the rotation axis O1, with the amount of chips generated increasing toward the outer periphery. For this reason, the load caused by chip collisions on the portion of the main body 3 located toward the outer periphery also increases in proportion to the amount of chips generated. For this reason, the width of the honing surface on the outer periphery may be greater than the width of the honing surface on the rotation axis O1 side.

[0053] Therefore, when the drill 1 has the above-described configuration, the high rigidity and good chip discharge performance of the drill 1 can be ensured, while the risk of the drill 1 breaking due to collision with chips can be reduced.

[0054] As shown in Figure 5, the second honing surface 31 may have a first region 37 and a second region 39 located more radially outward than the first region 37. The first region 37 may have a concave shape recessed forward in the rotational direction O2 when viewed from the tip. The second region 39 may extend forward in the rotational direction O2 as it approaches the radially outward side when viewed from the tip. The first region 37 may be connected to the second region 39, and in this case, the connected portion is referred to as a second connecting portion P2.

[0055] Chips generated during cutting may collide with the first region 37 as they flow from the first thinning groove 11A to the first discharge groove 15A. If the first region 37 is not concave, collisions of chips tend to concentrate near the end of the first region 37 on the rotation axis O1 side. However, if the first region 37 is concave, the risk of chip collisions can be dispersed to the outer peripheral portion of the first region 37.

[0056] Furthermore, when the second region 39 extends forward in the rotational direction O2 toward the outer periphery, the width of the first discharge groove 15A increases, which further improves chip discharge performance.

[0057] The first region 37 may have a third portion 41 whose width increases toward the outer circumferential surface 19. The third portion 41 may be connected to the second region 39 at the second connecting portion P2, or may be connected to the second portion 35. In such a case, the risk of breakage due to chip collision can be reduced while ensuring high rigidity and good chip discharge performance of the drill 1. The width W3 of the third portion 41 shown in FIG. 5 may be 5 μm to 50 μm. The amount of change in the width W3 of the third portion 41 may be 3 μm to 45 μm.

[0058] 5 , the bottom 43 refers to the portion of the first region 37 where the boundary between the first discharge groove 15A and the first region 37 is recessed furthest forward in the rotational direction O2, and the bottom 43 may be said to be located at the forward end in the rotational direction O2. Here, in the first region 37, a portion located on the outer periphery side of the bottom 43 is referred to as an outer region 45, and a region located inside the outer region 45 is referred to as an inner region 47.

[0059] 5, when viewed from the tip, outer region 45 faces the first thinning groove 11A, and therefore chips flowing from first thinning groove 11A are more likely to collide with outer region 45 than with inner region 47. Therefore, when main body 3 has the above-described configuration, a relatively wide honing is applied to outer region 45, and therefore breakage due to chip collision is less likely to occur.

[0060] The second region 39 may have a fourth portion 49 whose width increases toward the first region 37. The fourth portion 49 may be connected to the first region 37 at a second connecting portion P2. When viewed from the tip, the fourth portion 49 is a portion of the second region 39 located forward in the rotational direction O2, i.e., a protruding portion, and therefore has a high risk of chipping of the drill 1 due to collision with chips. Therefore, when the second region 39 has the above-described configuration, such risk can be reduced. The width W4 of the fourth portion 49 shown in FIG. 5 may be 10 μm to 100 μm. The amount of change in the width W4 of the fourth portion 49 may be 2 μm to 80 μm.

[0061] The second region 39 may have a fifth portion 51 whose width increases toward the outer peripheral surface 19. The fifth portion 51 may be connected to the first outer peripheral surface 19A or to the fourth portion 49. In this case, the high rigidity and good chip discharge performance of the drill 1 can be ensured while reducing the risk of breakage of the drill 1 due to collision with chips. The width W5 of the fifth portion 51 shown in FIG. 5 may be 15 μm to 150 μm. Furthermore, the amount of change in the width W5 of the fifth portion 51 may be 5 μm to 120 μm.

[0062] 5, the width WP1 of the first connecting portion P1 may be smaller than the width WP2 of the second connecting portion P2. In this case, excessive honing near the first connecting portion P1 can be reduced, and the thickness of the main body 3 near the first connecting portion P1 can be ensured. Furthermore, when viewed from the front end, the first connecting portion P1 may be located forward of the second connecting portion P2 in the rotational direction O2.

[0063] When the portion where the width of second honing surface 31 is smallest is defined as smallest portion S, first region 37 may have smallest portion S. Specifically, as shown in Fig. 5, the minimum value of width W1 of first region 37 may be width WS of smallest portion S. In such a case, since the width of second region 39 becomes relatively large, chipping due to chip collision is less likely to occur on the outer periphery of main body 3.

[0064] When the distance from the end of second honing surface 31 on the rotation axis O1 side to smallest portion S is L1 and the distance from smallest portion S to the end of second honing surface 31 on the outer periphery side is L2, L2 / L1 ≧ 5 may be satisfied. Specifically, as shown in FIG. 6 , in the direction along virtual straight line N, the relationship between the distance L1 from first connecting portion P1 to smallest portion S and the distance L2 from smallest portion S to second connecting portion P2 may be L2 / L1 ≧ 5. In such a case, the width of the honing surface from smallest portion S to the outer periphery side gradually increases, making it less likely that chips will collide with the outer periphery of main body 3.

[0065] First thinning groove 11A may have a first thinning surface 13A connected to first portion 33. Furthermore, the length of first honing surface 29 may be longer than the length of the boundary portion between first tip surface 17A and first thinning surface 13A. Specifically, as shown in FIG. 6 , when length L3 of first honing surface 29 in the direction along virtual line N is defined as length L4 of the boundary portion between first tip surface 17A and first thinning surface 13A, L3 may be greater than L4. In such a case, the risk of breakage due to chip collision in the portion located near rotation axis O1 can be reduced.

[0066] When viewed from the tip, the distance from the rotation axis O1 to the end of first honing surface 29 on the rotation axis O1 side may be smaller than one-third of the outer diameter of main body 3. Specifically, the relationship between the distance L5 from the rotation axis O1 to end point T1 on the rotation axis O1 side of first honing surface 29 shown in FIG. 4 and the outer diameter D of main body 3 may be L5 > D / 3. In such a case, it is possible to reduce the risk of breakage due to chip collision in the portion located near the rotation axis O1.

[0067] In the direction along the imaginary straight line N, the first honing surface 29 may be longer than the second honing surface 31. In such a case, the length of the second honing surface 31 becomes relatively large, and therefore the first discharge groove 15A also becomes relatively wide. As a result, chip discharge performance becomes even better. In addition, in the direction along the imaginary straight line N, the first region 37 may be longer than the second region 39, and the first portion 33 may be longer than the other portions. The third portion 41 may be longer than the second portion 35, and the fifth portion 51 may be longer than the fourth portion 49.

[0068] Specifically, in the direction along the virtual straight line N, the length of the first honing surface 29 may be 0.05D to 0.2D. The length of the second honing surface 31 may be 0.2D to 0.4D. The length of the first region 37 may be 0.2D to 0.38D. The length of the second region 39 may be 0.02D to 0.2D. The length of the first portion 33 may be 0.05D to 0.2D. The length of the second portion 35 may be 0.01D to 0.1D. The length of the third portion 41 may be 0.15D to 0.38D. The length of the fourth portion 49 may be 0.02D to 0.2D. The length of the fifth portion 51 may be 0.01D to 0.1D.

[0069] In addition to first honing surface 29 and second honing surface 31, main body 3 may have a honing surface having the same configuration as first honing surface 29 or second honing surface 31. For example, a honing surface having the same configuration as first honing surface 29 or second honing surface 31 may be provided at the boundary between second tip surface 17B and second thinning groove 11B. Honing surfaces having the same configuration as first honing surface 29 or second honing surface 31 may also be provided at the boundary between second tip surface 17B and second discharge groove 15B and the boundary between second tip surface 17B and second outer peripheral surface 19B. Furthermore, there is no particular limitation on the number of honing surfaces that drill 1 has. For example, if drill 1 has three blades, drill 1 may have three honing surfaces.

[0070] Examples of the material of the main body 3 include cemented carbide and cermet. Examples of cemented carbide compositions include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. Here, WC, TiC, and TaC are hard particles, and Co is a binder phase. Cermet is a sintered composite material in which a ceramic component is combined with a metal. Specifically, examples of cermet include titanium compounds whose main component is titanium carbide (TiC) or titanium nitride (TiN).

[0071] The surface of the main body 3 may be coated with a film using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and the composition of the film may include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), alumina (Al2O3), or the like.

[0072] <Method of manufacturing machined products> Next, a method for manufacturing a machined product according to an embodiment of the present disclosure will be described in detail using the drill 1 according to the above embodiment as an example. The following description will be given with reference to FIGS.

[0073] A method for manufacturing a machined product according to an embodiment of the present disclosure includes: (1) a step of rotating the drill 1 around a rotation axis O1; (2) bringing the cutting edge 9 of the rotating drill 1 into contact with the workpiece 100; (3) The step of separating the drill 1 from the workpiece 100.

[0074] More specifically, first, as shown in FIG. 7, the drill 1 is rotated around the rotation axis O1 and moved in a direction along the rotation axis O1 (Y1 direction), thereby bringing the drill 1 relatively closer to the workpiece 100.

[0075] Next, as shown in Fig. 8, the cutting edge 9 of the drill 1 is brought into contact with the workpiece 100 to cut the workpiece 100. Then, as shown in Fig. 9, the drill 1 is moved relatively away from the workpiece 100 by moving the drill 1 in the Y2 direction.

[0076] In the embodiment, the drill 1 is moved closer to the workpiece 100 while the workpiece 100 is fixed and rotated around the rotation axis O1. In addition, in Fig. 8, the cutting edge 9 of the rotating drill 1 is brought into contact with the workpiece 100 to cut the workpiece 100. In addition, in Fig. 9, the drill 1 is moved away from the workpiece 100 while rotating.

[0077] In the cutting process using the manufacturing method according to the embodiment of the present disclosure, the drill 1 is moved in each step to bring the drill 1 into contact with the workpiece 100 or to separate the drill 1 from the workpiece 100. Of course, the present invention is not limited to this form.

[0078] For example, in step (1), the workpiece 100 may be brought closer to the drill 1. In step (3), the workpiece 100 may be moved away from the drill 1. To continue the cutting process, the drill 1 may be kept rotating, and the step of bringing the cutting edge 9 of the drill 1 into contact with different locations on the workpiece 100 may be repeated.

[0079] Typical examples of the material of the workpiece 100 include aluminum, carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals. [Explanation of symbols]

[0080] 1. Drill 3. Main unit 3A...Tip 3B...rear end 5...Cutting part 7. Shank 9 Cutting edge 9A...1st cutting edge 9B...Second cutting edge 11 Thinning groove 11A···First thinning groove 11B Second thinning groove 13 Thinning surface 13A···First thinning surface 13B: Second thinning surface 15...Discharge groove 15A...1st discharge groove 15B...Second discharge groove 17...Tip surface 17A...1st tip surface 17B...2nd tip surface 19...outer surface 19A...First outer surface 19B...Second outer peripheral surface 21 Main cutting edge 23 Chisel blade 25···Thinning blade 27 Opening 29. First honing surface 31 Second honing surface 33...1st part 35...Second part 37...1st area 39...Second area 41...3rd part 43...bottom 45...outer area 47...inner area 49...4th part 51...5th part 100...Work material O1 Rotation axis O2 Rotation direction L: Body length L1~L5...length (spacing) D: Outer diameter of the body P1, P2... Connection T1, T2...end points N... Virtual line W1~W5: Width of each part WP1, WP2...Connection width S...Minimum part WS: Width at the smallest part Y1, Y2.....movement direction

Claims

1. a rod-shaped main body extending from a front end to a rear end along a rotation axis; The main body is A cutting edge located on the tip side; a thinning groove extending from the cutting edge toward the rear end; a discharge groove located on the outer circumferential side of the thinning groove and extending from the cutting edge toward the rear end; a tip end surface adjacent to the thinning groove and the discharge groove in front of the rotation direction of the rotary shaft; a first honing surface located at an intersection of the tip surface and the thinning groove; a second honing surface located at an intersection of the tip surface and the discharge groove and connected to the first honing surface; The first honing surface has a first portion connected to the second honing surface and having a width increasing in a tip view as approaching the second honing surface, The second honing surface is connected to the first honing surface and has a second portion whose width, as viewed from the tip, increases toward the first honing surface.

2. In the tip view, The first portion extends rearward in the rotational direction toward the second honing surface, The drill according to claim 1 , wherein the second portion extends rearward in the rotational direction toward the first honing surface.

3. The drill of claim 1 , wherein the entire first honing surface is the first portion.

4. In the tip view, The second honing surface is a first region having a concave shape recessed forward in the rotation direction; The drill according to claim 1 , further comprising: a second region located on the outer periphery side of the first region and extending forward in the rotation direction as it approaches the outer periphery side.

5. The body has an outer peripheral surface located at an outer edge, The first region is The second portion; The drill according to claim 4 , further comprising a third portion connected to the second region, the width of which increases in the tip view as it approaches the outer circumferential surface.

6. the first region further has a bottom portion located at a front end in the rotation direction, The drill of claim 5 , wherein the third portion includes the bottom portion.

7. The drill according to claim 4 , wherein the second region has a fourth portion that includes an end connected to the first region and whose width in the tip view increases toward the first region.

8. The drill according to claim 4 , wherein the second region has a fifth portion that includes the outer peripheral end and whose width, as viewed from the tip, increases toward the outer peripheral side.

9. the first region is connected to the second region; A portion where the first honing surface and the second honing surface contact each other is called a first connection portion, When a portion where the first region and the second region contact each other is defined as a second connection portion, In the tip view, The drill according to claim 4 , wherein the width of the honing surface at the first connecting portion is smaller than the width of the honing surface at the second connecting portion.

10. When the portion where the width of the second honing surface is smallest is defined as the minimum portion, The drill of claim 4 , wherein the first region comprises the minimum portion.

11. In the tip view, The distance from the end of the second honing surface on the rotation axis side to the minimum part is L1, When the distance from the minimum portion to the outer peripheral end of the second honing surface is L2, The drill according to claim 10, wherein L2 / L1≧5.

12. the thinning groove has a thinning surface connected to the first portion, The drill according to claim 1 , wherein a length of the first honing surface is longer than a length of a boundary portion between the first tip surface and the first thinning surface.

13. When viewed from the tip, The drill according to claim 1 , wherein a distance from the rotation axis to an end of the first honing surface on the rotation axis side is less than one-third of an outer diameter of the body.

14. Rotating the drill according to any one of claims 1 to 13; bringing the rotating drill into contact with a workpiece; and a step of separating the drill from the workpiece.

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