Drill, and method for manufacturing cut workpiece

Abstract

A drill according to one non-limiting aspect of the present disclosure comprises a rod-shaped main body that extends along an axis of rotation from a tip end toward a rear end. The main body has an outer circumferential surface that is positioned so as to be sandwiched between a first discharge groove and a second discharge groove, and that extends from a flank toward the rear end. The outer circumferential surface has a front margin surface extending along the first discharge groove, a rear margin surface extending along the second discharge groove, and a clearance surface positioned so as to be sandwiched between the front margin surface and the rear margin surface. A ridge line of the rear margin surface and the flank extends toward the rear end with increasing distance forwards in the direction of rotation. The ridge line includes a ridge line end portion positioned forward in the direction of rotation, and has a convex curved portion protruding forward in the direction of rotation.

Description

Drill and cutting process CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2023-120633, filed on July 25, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to methods of manufacturing drills and cuttings.

[0003] A drill (hole-making tool) described in Japanese Patent Laid-Open No. 7-040117 (Patent Document 1) is known as a drill used for performing milling on a workpiece. The drill described in Patent Document 1 has a first margin and a second margin. By having multiple margins in this way, the straightness stability of the drill is improved.

[0004] In the second margin disclosed in Patent Document 1, the end portion of the tip portion located at the front in the direction of rotation is located closer to the rear end of the drill than the end portion located at the rear in the direction of rotation. The above-described configuration of the second margin allows the tip portion to function as a wiper edge.

[0005] A relatively large cutting load is likely to be applied to the tip end of the second margin in Patent Document 1. Therefore, there is a demand for further improvement in the durability of the second margin.

[0006] A non-limiting one-sided drill according to the present disclosure has a rod-shaped body extending from a tip end to a rear end along a rotation axis, the body having a first cutting edge located on the tip end side, a second cutting edge located on the tip end side and rearward of the first cutting edge in the rotation direction of the rotation axis, a flank extending from the first cutting edge rearward in the rotation direction, a first discharge groove extending from the first cutting edge toward the rear end, a second discharge groove extending from the second cutting edge toward the rear end, and an outer circumferential surface located between the first discharge groove and the second discharge groove and extending from the flank toward the rear end.

[0007] The outer peripheral surface has a front margin surface extending along the first discharge groove, a rear margin surface extending along the second discharge groove, and a clearance surface located between the front margin surface and the rear margin surface. The ridgelines of the rear margin surface and the relief surface extend toward the rear end as they move forward in the rotation direction. The ridgelines include an end portion of the ridgeline located forward in the rotation direction and have a convex curved portion that protrudes forward in the rotation direction.

[0008] 1 is a perspective view showing an unlimited single-sided drill of the present disclosure; FIG. 2 is an enlarged view of region II shown in FIG. 1; FIG. 3 is an enlarged view of region III shown in FIG. 2; FIG. 4 is a side view of the drill shown in FIG. 1; FIG. 5 is an enlarged view of region V shown in FIG. 6; FIG. 6 is a cross-sectional view of cross-section VII of the drill shown in FIG. 4; FIG. 7 is an enlarged view of region VIII shown in FIG. 7; FIG. 8 is a perspective view showing an unlimited single-sided drill of the present disclosure, and corresponds to FIG. 3; FIG. 9 is a side view of the drill shown in FIG. 9, and corresponds to FIG. 6; FIG. 10 is a cross-sectional view of an unlimited single-sided drill of the present disclosure, and corresponds to FIG. 8; FIG. 11 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure; FIG. 12 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure; FIG. 13 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure;

[0009] <Drill> A non-limiting example of a drill 1 according to the present disclosure will be described in detail below with reference to the drawings. However, for the sake of convenience, the drawings below show only the main components necessary for explaining the embodiment in a simplified form. Therefore, the drill 1 may include optional components not shown in the drawings. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components or the dimensional ratios of the components.

[0010] In a non-limiting aspect, a solid drill may be shown as an example of the drill 1. However, the drill 1 is not limited to a solid drill, and may be, for example, a replaceable tip drill.

[0011] The drill 1 may have a main body 3, as shown in a non-limiting example in FIGS. 1 to 8 . The main body 3 may be rod-shaped and extend along a rotation axis O1 from a tip end 3a to a rear end 3b. The main body 3 is rotatable around the rotation axis O1. Note that the arrow Y1 in FIG. 1 and other figures may indicate the rotation direction of the rotation axis O1, or may indicate the rotation direction of the main body 3 around the rotation axis O1.

[0012] The main body 3 may have a shank portion 5 and a cutting portion 7. The shank portion 5 can function as a portion that is gripped by a rotating spindle of a machine tool. The shank portion 5 may be designed according to the shape of the spindle in the machine tool.

[0013] The cutting portion 7 may be located on the tip 3a side relative to the shank portion 5. The cutting portion 7 is capable of coming into contact with the workpiece, and can function as a portion that plays a major role in cutting (e.g., drilling) the workpiece.

[0014] The main body 3 is not limited to a specific size. For example, if the outer diameter of the cutting portion 7 is D, the maximum value of D may be set to approximately 2 to 50 mm. Furthermore, if the length of the cutting portion 7 in the direction along the rotation axis O1 is L, L may be set to approximately L=1.5D to 12D.

[0015] 2 , the main body 3 may have a first cutting edge 9, a second cutting edge 11, a flank 13, a first discharge groove 15, a second discharge groove 17, and an outer peripheral surface 19. These parts may be located in the cutting portion 7.

[0016] The first cutting edge 9 may be located on the side of the tip 3a. The first cutting edge 9 can function as a part that cuts the workpiece in the cutting process. The first cutting edge 9 can also be called a main cutting edge.

[0017] The second cutting edge 11 may be located on the side of the tip 3a, rearward of the first cutting edge 9 in the rotation direction Y1 of the rotation axis O1. The second cutting edge 11 may function as a part that cuts the workpiece in cutting processing. The second cutting edge 11 may also be called a main cutting edge. The second cutting edge 11 may have the same configuration as the first cutting edge 9.

[0018] There may be only one each of the first cutting edge 9 and the second cutting edge 11, or there may be multiple each of the first cutting edge 9 and the second cutting edge 11. When there are multiple each of the first cutting edge 9 and the second cutting edge 11, the first cutting edge 9 and the second cutting edge 11 may be positioned alternately in the direction along the rotation direction Y1.

[0019] When there are a plurality of first cutting edges 9 and a plurality of second cutting edges 11, the number of each of the first cutting edges 9 and the second cutting edges 11 may be 2 to 4. Furthermore, the number of second cutting edges 11 may be the same as the number of first cutting edges 9. For example, as in a non-limiting example shown in Figure 2, when there is one first cutting edge 9, there may also be one second cutting edge 11.

[0020] The first cutting edge 9 and the second cutting edge 11 may be positioned to be rotationally symmetrical at 180° with respect to the rotation axis O1. In this case, the drill 1 has high linearity when cutting a workpiece.

[0021] The flank 13 may extend rearward in the rotational direction Y1 from the first cutting edge 9. The flank 13 can function as a portion that avoids contact with the workpiece and reduces cutting resistance. The flank 13 may be connected to the first cutting edge 9.

[0022] The flank 13 may have a second flank 21 and a third flank 23. The second flank 21 may be located along the first cutting edge 9. The second flank 21 may also be connected to the first cutting edge 9. The second flank 21 may be flat.

[0023] The third flank 23 may be located along the second flank 21 at the rear in the rotational direction Y1. Alternatively, the third flank 23 may be connected to the second flank 21. The third flank 23 may be inclined with respect to the second flank 21. The third flank 23 may be flat.

[0024] The first discharge grooves 15 may extend from the first cutting edge 9 toward the rear end 3b. The first discharge grooves 15 may function as a portion for discharging chips generated by the first cutting edge 9 to the outside. The first discharge grooves 15 may extend parallel to the rotation axis O1, or may extend in a spiral shape around the rotation axis O1. The number of first discharge grooves 15 may be the same as the number of first cutting edges 9.

[0025] The first discharge groove 15 may be connected to the first cutting edge 9. In this case, the bite into the workpiece is strong. Also, a cutting face connecting the first discharge groove 15 and the first cutting edge 9 may be located between them. In this case, the discharge direction of chips generated by the first cutting edge 9 is likely to be stable. From the viewpoint of smoothly discharging chips to the outside, the first discharge groove 15 may have a concave curved shape in a cross section perpendicular to the rotation axis O1.

[0026] The second discharge grooves 17 may extend from the second cutting edge 11 toward the rear end 3b. The second discharge grooves 17 may function as a portion for discharging chips generated by the second cutting edge 11 to the outside. The second discharge grooves 17 may extend parallel to the rotation axis O1, or may extend in a spiral shape around the rotation axis O1. The number of second discharge grooves 17 may be the same as the number of second cutting edges 11.

[0027] For the same reasons as those described for the first discharge groove 15, the second discharge groove 17 may be connected to the second cutting edge 11. Also, a cutting face connecting the second discharge groove 17 and the second cutting edge 11 may be located between them. In a cross section perpendicular to the rotation axis O1, the second discharge groove 17 may have a concave curved shape.

[0028] The depths of the first discharge groove 15 and the second discharge groove 17 are not limited to specific values. For example, the depth of the first discharge groove 15 may be set to 1.5 to 10% of the outer diameter of the main body 3 (cutting portion 7), and the depth of the second discharge groove 17 may be set to 15 to 40%. The depth of the first discharge groove 15 may be the value obtained by subtracting the distance between the bottom of the first discharge groove 15 and the rotation axis O1 in a cross section perpendicular to the rotation axis O1 from the radius of the main body 3 (cutting portion 7). The bottom of the first discharge groove 15 may be the portion of the first discharge groove 15 closest to the rotation axis O1. The depth of the second discharge groove 17 may be defined in the same way as the depth of the first discharge groove 15.

[0029] The outer peripheral surface 19 may be located between the first discharge groove 15 and the second discharge groove 17. The outer peripheral surface 19 may extend from the clearance surface 13 toward the rear end 3b. The outer peripheral surface 19 may be connected to the first discharge groove 15 and the second discharge groove 17. The outer peripheral surface 19 may be connected to the clearance surface 13.

[0030] The outer peripheral surface 19 may have a leading margin surface 25 , a trailing margin surface 27 and a clearance surface 29 .

[0031] The front margin surface 25 may extend along the first discharge groove 15. Furthermore, the rear margin surface 27 may extend along the second discharge groove 17. The front margin surface 25 and the rear margin surface 27 can function as portions that come into sliding contact with the inner wall surface of a drilled hole in a workpiece, thereby stabilizing the operability of the drill 1. When the outer peripheral surface 19 has the front margin surface 25 and the rear margin surface 27, the straight-line stability of the drill 1 is high. Note that, in a cross section perpendicular to the rotation axis O1, the front margin surface 25 and the rear margin surface 27 may be arc-shaped portions that correspond to the outer periphery of the main body 3.

[0032] The clearance surface 29 may be located between the front margin surface 25 and the rear margin surface 27. The clearance surface 29 can function as a portion that reduces friction with the workpiece during cutting. The clearance surface 29 may be recessed with respect to the front margin surface 25 and the rear margin surface 27. The clearance surface 29 may be connected to the front margin surface 25 and the rear margin surface 27.

[0033] Here, the ridge line 31 of the rear margin surface 27 and the flank surface 13 may extend toward the rear end 3b as it moves forward in the rotation direction Y1, as in a non-limiting example shown in Figure 6. This configuration may be evaluated in a side view. The side view may refer to a state seen from a direction perpendicular to the rotation axis O1. When the ridge line 31 extends toward the rear end 3b as it moves forward in the rotation direction Y1, the ridge line 31 can function as a wiper edge.

[0034] The ridgeline 31 may have a convex curved portion 33. The convex curved portion 33 may include an end 31a of the ridgeline 31 located forward in the rotational direction Y1. The convex curved portion 33 may also protrude forward in the rotational direction Y1. A relatively large cutting load is likely to be applied to the end 31a of the ridgeline 31 located forward in the rotational direction Y1 and its surroundings. When the ridgeline 31 has the above-mentioned convex curved portion 33, the durability of the ridgeline 31 against cutting loads is high. Therefore, the drill 1 has high durability.

[0035] The ridge line 31 may further include a straight portion 35, as shown in a non-limiting example in FIG. 6 . The straight portion 35 may extend rearward in the rotational direction Y1 from the convex curved portion 33. In this case, it is easy to prevent the ridge line 31 from rubbing against the workpiece more than necessary. This reduces cutting resistance, suppresses wear of the ridge line 31, and tends to improve the life of the drill 1.

[0036] The straight portion 35 may be connected to the convex curved portion 33. The straight portion 35 may also include the end 31b of the ridge line 31 located rearward in the rotational direction Y1. The end 31a located forward in the rotational direction Y1 may be located closer to the rear end 3b than the end 31b located rearward in the rotational direction Y1. The end 31a may be referred to as the first end 31a, and the end 31b may be referred to as the second end 31b.

[0037] The width W35 of the straight portion 35 along the rotational direction Y1 may be the same as or different from the width W33 of the convex curved portion 33 along the rotational direction Y1. For example, as shown in a non-limiting example in FIG. 6 , the width W35 of the straight portion 35 may be greater than the width W33 of the convex curved portion 33. In this case, when the drill 1 bites into the workpiece during drilling, the convex curved portion 33 and the straight portion 35 are less likely to come into contact with the workpiece at once, and the contact area with the workpiece gradually expands from the boundary between the convex curved portion 33 and the straight portion 35, resulting in a gradual increase in cutting resistance. Note that the width W35 of the straight portion 35 and the width W33 of the convex curved portion 33 are not limited to specific values.

[0038] 3, the outer peripheral surface 19 may further have a chamfered region 37. The chamfered region 37 may be sandwiched between the second discharge groove 17 and the rear margin surface 27. In this case, stress concentration between the rear margin surface 27 and the second discharge groove 17 can be alleviated, and the risk of sudden breakage can be reduced.

[0039] The chamfered region 37 may be connected to the second discharge groove 17 and the rear margin surface 27. As a non-limiting example shown in Figure 8, the chamfered region 37 may have a linear shape in a cross section perpendicular to the rotation axis O1. The chamfered region 37 may be inclined with respect to the rear margin surface 27.

[0040] The clearance surface 29 may have a rear region 39, as shown in a non-limiting example in Figure 8. The rear region 39 may be connected to the rear margin surface 27. In a cross section perpendicular to the rotation axis O1, the rear region 39 may have a concave curved shape. In these cases, fine chips generated during cutting can be discharged to the outside via the concave curved rear region 39. This makes it difficult for chips to get caught in the rear margin surface 27, and therefore the main body 3 is less likely to be damaged.

[0041] In a cross section perpendicular to the rotation axis O1, the angle θ1 between the rear region 39 and the rear margin surface 27 may be the same as or different from the angle θ2 between the chamfered region 37 and the rear margin surface 27. For example, as in a non-limiting example shown in Figure 8, the angle θ1 may be smaller than the angle θ2 in a cross section perpendicular to the rotation axis O1. In this case, a large space can be secured for the rear region 39 located forward of the rear margin surface 27 in the rotation direction Y1, making it easier for many chips to flow into the rear region 39.

[0042] In addition, when the rear region 39 has a concave curved shape in a cross section perpendicular to the rotation axis O1, a tangent line can be set at the boundary with the rear margin surface 27, and the angle θ1 formed by the rear region 39 and the rear margin surface 27 can be determined by the angle at which this tangent line intersects with the rear margin surface 27.

[0043] 8, in a cross section perpendicular to the rotation axis O1, the angle θ1 between the rear region 39 and the rear margin surface 27 and the angle θ2 between the chamfered region 37 and the rear margin surface 27 may each be an obtuse angle. In this case, the rigidity of the drill 1 can be increased, and the drilling process can be stabilized.

[0044] The angles θ1 and θ2 are not limited to specific values. For example, the angle θ1 may be set to 60 to 145°. The angle θ2 may be set to 80 to 155°. The angle θ1 may be referred to as the first angle θ1, and the angle θ2 may be referred to as the second angle θ2.

[0045] In a cross section perpendicular to the rotation axis O1, the width W37 of the chamfered region 37 in the direction along the rotation direction Y1 may be the same as or different from the width W27 of the rear margin surface 27 in the direction along the rotation direction Y1. For example, as shown in a non-limiting example in Figure 8, in a cross section perpendicular to the rotation axis O1, the width W37 of the chamfered region 37 may be smaller than the width W27 of the rear margin surface 27. In this case, the rear margin surface 27 and the second discharge groove 17 are close to each other, so that the rear margin surface 27 can stably function as a margin.

[0046] The width W37 of the chamfered region 37 and the width W27 of the rear margin surface 27 are not limited to specific values. For example, in a cross section perpendicular to the rotation axis O1, the width W37 of the chamfered region 37 may be set to 1 to 10% of the total length of the outer periphery of the main body 3 (cutting portion 7), and the width W27 of the rear margin surface 27 may be set to 3 to 10%.

[0047] 7 , in a cross section perpendicular to the rotation axis O1, the width W27 of the rear margin surface 27 may be larger than the width W25 of the front margin surface 25 in the direction along the rotation direction Y1. Also, in a cross section perpendicular to the rotation axis O1, the width W29 of the clearance surface 29 in the direction along the rotation direction Y1 may be larger than the width W25 of the front margin surface 25 and the width W27 of the rear margin surface 27.

[0048] The width W25 of the front margin surface 25 and the width W29 of the clearance surface 29 are not limited to specific values. For example, in a cross section perpendicular to the rotation axis O1, the width W25 of the front margin surface 25 may be set to 3 to 8% of the total length of the outer periphery of the main body 3 (cutting portion 7), and the width W29 of the clearance surface 29 may be set to 10 to 25%.

[0049] As shown in a non-limiting example in FIG. 3 , the flank 13 may have a convexly curved region 41 extending from the convex curved portion 33 toward the rotation axis O1. In this case, the strength of the rear margin surface 27 can be increased, and the rear margin surface 27 is more likely to be protected. The region 41 may extend forward in the rotation direction Y1 as it moves away from the convex curved portion 33. The width of the region 41 in the direction along the rotation axis O1 may decrease as it moves closer to the rotation axis O1. The region 41 may be connected to the convex curved portion 33. The region 41 may be connected to the third flank 23. The region 41 may be separated from the second flank 21.

[0050] Examples of the material of the main body 3 include cemented carbide and cermet. Examples of the composition of the cemented carbide include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. Here, WC, TiC, and TaC may be hard particles, and Co may be a binder phase.

[0051] The cermet may be a sintered composite material in which a ceramic component is combined with a metal. Specifically, the cermet may be a titanium compound mainly composed of titanium carbide (TiC) or titanium nitride (TiN). However, the above materials are only examples and are not limiting, and the main body 3 is not limited to these materials.

[0052] The surface of the main body 3 may be coated with a coating using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and the coating composition may include, for example, titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0053] Next, a non-limiting example of another aspect of the drill 1A of the present disclosure will be described with reference to the drawings. Below, differences between the drill 1A and the drill 1 will be mainly described, and detailed descriptions of the same configurations as the drill 1 may be omitted. Therefore, the description of the drill 1 may be used to understand the configuration of the drill 1A. This also applies to the drill 1B described below.

[0054] 9 and 10 , the entire ridge line 31 may be the convex curved portion 33. In other words, the convex curved portion 33 may further include the end portion 31b of the ridge line 31 located rearward in the rotational direction Y1. In this case, the durability of the ridge line 31 against cutting loads is further improved.

[0055] Next, a non-limiting yet another one-sided drill 1B according to the present disclosure will be described with reference to the drawings.

[0056] In the drill 1B, as shown in a non-limiting example in FIG. 11 , the outer peripheral surface 19 may further include a chamfered region 37 sandwiched between the second discharge flute 17 and the rear margin surface 27. The chamfered region 37 may have a concave curved shape in a cross section perpendicular to the rotation axis O1. In these cases, chips are more likely to be discharged to the outside. Therefore, drilling is less likely to be performed with chips adhering to the chamfered region 37, and the machined surface is less likely to be damaged by the chips.

[0057] For the same reasons as those described for the drill 1, in the drill 1B, the clearance surface 29 may have a rear region 39 connected to the rear margin surface 27. Furthermore, in a cross section perpendicular to the rotation axis O1, the rear region 39 may have a concave curved shape.

[0058] In a cross section perpendicular to the rotation axis O1, the radius of curvature of the concavely curved chamfered region 37 may be the same as or different from the radius of curvature of the concavely curved rear region 39. For example, as shown in a non-limiting example in Figure 11, in a cross section perpendicular to the rotation axis O1, the radius of curvature of the concavely curved chamfered region 37 may be larger than the radius of curvature of the concavely curved rear region 39. In this case, the rigidity of the rear margin surface 27 can be increased.

[0059] The radius of curvature of the chamfered region 37 in a cross section perpendicular to the rotation axis O1 may be larger than the radius of curvature of the convex curved portion 33 at the ridge line 31 (see FIGS. 6, 10, and 11). If the radius of curvature of the chamfered region 37 is relatively large, drilling is less likely to be performed with chips adhering to the chamfered region 37. On the other hand, if the radius of curvature of the convex curved portion 33 is relatively small, chips are less likely to become caught in the convex curved portion 33. This makes it less likely that the drill 1B will break and that the inner wall surface of the drilled hole will not be damaged.

[0060] The respective radii of curvature of the chamfered region 37, the rear region 39, and the convex curved portion 33 are not limited to specific values. For example, the radius of curvature of the chamfered region 37 may be set to 3 to 20 mm. The radius of curvature of the rear region 39 may be set to 0.4 to 3 mm. The radius of curvature of the convex curved portion 33 may be set to 0.2 to 2 mm.

[0061] For the same reasons as those described for the drill 1, the drill 1B may have the following configuration: In other words, in the drill 1B, in a cross section perpendicular to the rotation axis O1, the width W37 of the chamfered region 37 in the direction along the rotation direction Y1 may be smaller than the width W27 of the rear margin surface 27 in the direction along the rotation direction Y1.

[0062] In addition, in the drill 1B, the angle θ1 formed between the rear region 39 and the rear margin surface 27 may be smaller than the angle θ2 formed between the chamfered region 37 and the rear margin surface 27 in a cross section perpendicular to the rotation axis O1.

[0063] In the drill 1B, in a cross section perpendicular to the rotation axis O1, the angle θ1 formed between the rear region 39 and the rear margin surface 27, and the angle θ2 formed between the chamfered region 37 and the rear margin surface 27 may each be an obtuse angle.

[0064] In addition, when the chamfered region 37 has a concave curved shape in a cross section perpendicular to the rotation axis O1, a tangent line can be set at the boundary with the rear margin surface 27, and the angle θ2 formed by the chamfered region 37 and the rear margin surface 27 can be determined by the angle at which this tangent line intersects with the rear margin surface 27.

[0065] <Method for Manufacturing Machined Product> Next, a non-limiting method for manufacturing the machined product 101 on one side according to the present disclosure will be described with reference to the drawings, taking as an example a case where the drill 1 described above is used.

[0066] The machined product 101 may be produced by cutting a workpiece 103. A method for producing the machined product 101 may include the following steps (1) to (4).

[0067] (1) A step of placing the drill 1 above the workpiece 103 (see FIG. 12 ). (2) A step of rotating the drill 1 in the direction of the arrow Y1 around the rotation axis O1 to bring the drill 1 closer to the workpiece 103 (see FIG. 12 ).

[0068] In steps (1) and (2), for example, the workpiece 103 may be fixed on a table of a machine tool to which the drill 1 is attached, and the drill 1 may be brought closer to the workpiece 103 while rotating. In step (2), the workpiece 103 and the drill 1 may be brought closer to each other, for example, the workpiece 103 may be brought closer to the drill 1.

[0069] (3) A process of bringing the rotating drill 1 closer to the workpiece 103, thereby bringing the rotating drill 1 into contact with the workpiece 103 and forming a machined hole 105 in the workpiece 103 (see Figure 13).

[0070] In step (3), cutting may be performed so that at least a portion of the cutting portion 7 of the main body 3 is located inside the machined hole 105. Also, in step (3), the shank portion 5 of the main body 3 may be set to be located outside the machined hole 105. From the viewpoint of obtaining a good finished surface, a portion of the rear end 3b side of the cutting portion 7 may be set to be located outside the machined hole 105. This portion can be made to function as a margin region for chip evacuation, and excellent chip evacuation can be achieved via this region.

[0071] (4) Step of separating the drill 1 from the workpiece 103 (see FIG. 14). In step (4), the workpiece 103 and the drill 1 may be separated relatively. For example, the workpiece 103 may be separated from the drill 1.

[0072] By going through the above steps, it is possible to obtain a machined product 101 having a highly accurate machined hole 105. Specifically, when the drill 1 is used in the manufacturing method of the machined product 101, the drill 1 has high durability and therefore can exhibit excellent workability. As a result, it is possible to obtain a machined product 101 having a highly accurate machined hole 105.

[0073] In addition, when cutting the workpiece 103 multiple times, for example, when forming multiple machining holes 105 in one workpiece 103, the process of contacting the drill 1 with different locations on the workpiece 103 while keeping the drill 1 rotating may be repeated.

[0074] Examples of the material of the workpiece 103 include aluminum, carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0075] 12 to 14, the drill 1 is used, but the present invention is not limited to this. For example, instead of the drill 1, a drill 1A or a drill 1B may be used.

[0076] The above describes examples of the non-limiting one-sided drills 1, 1A, 1B and the manufacturing method of the machined product 101 of the present disclosure, but it goes without saying that the present disclosure is not limited to the above-described embodiments and can be any method as long as it does not deviate from the gist of the present disclosure.

[0077] For example, the drills 1, 1A, and 1B and the manufacturing method of the machined product 101 may have the following configuration: [1] The drill has a rod-shaped main body extending from a front end to a rear end along a rotation axis, the main body including a first cutting edge located on the front end side, a second cutting edge located on the front end side and rearward of the first cutting edge in the rotation direction of the rotation axis, a flank extending from the first cutting edge rearward in the rotation direction, a first discharge groove extending from the first cutting edge toward the rear end, a second discharge groove extending from the second cutting edge toward the rear end, and a groove located between the first discharge groove and the second discharge groove and extending from the flank to the rear end.

[0013] [2] The drill according to [1] above has an outer peripheral surface extending toward the first groove, the outer peripheral surface having a front margin surface extending along the first discharge groove, a rear margin surface extending along the second discharge groove, and a clearance surface located between the front margin surface and the rear margin surface, and the ridgelines of the rear margin surface and the flank surface extend toward the rear end as they move forward in the rotation direction, and the ridgelines include an end portion of the ridgeline located forward in the rotation direction and have a convex curved portion protruding forward in the rotation direction. [2] In the drill according to [1] above, the entire ridgeline may be the convex curved portion. [3] In the drill according to [1] above, the ridgeline may further have a straight portion extending from the convex curved portion toward the rear in the rotation direction. [4] In the drill according to [3] above, the width of the straight portion in the rotation direction may be greater than the width of the convex curved portion in the rotation direction. [5] In the drill of any one of [1] to [4] above, the outer peripheral surface may further have a chamfered region sandwiched between the second discharge flute and the rear margin surface, and the chamfered region may have a concave curved shape in a cross section perpendicular to the rotation axis. [6] In the drill of [5] above, the clearance surface may have a rear region connected to the rear margin surface, and the rear region may have a concave curved shape in a cross section perpendicular to the rotation axis. [7] In the drill of [6] above, the angle formed by the rear region and the rear margin surface may be smaller than the angle formed by the chamfered region and the rear margin surface in a cross section perpendicular to the rotation axis.[8] In the drill of [6] or [7] above, in a cross section perpendicular to the rotation axis, the angle between the rear region and the rear margin surface, and the angle between the chamfered region and the rear margin surface may each be an obtuse angle. [9] In any one of the drills of [6] to [8] above, in a cross section perpendicular to the rotation axis, the radius of curvature of the concavely curved chamfered region may be greater than the radius of curvature of the concavely curved rear region.

[10] In any one of the drills of [5] to [9] above, in a cross section perpendicular to the rotation axis, the width of the chamfered region in the direction along the rotation direction may be smaller than the width of the rear margin surface in the direction along the rotation direction.

[11] In any one of the drills of [5] to

[10] above, the radius of curvature of the chamfered region in the cross section perpendicular to the rotation axis may be greater than the radius of curvature of the convexly curved portion of the ridgeline.

[12] A method for manufacturing a machined product can include the steps of rotating any one of the drills [1] to

[11] above, bringing the rotating drill into contact with a workpiece, and removing the drill from the workpiece.

[0078] DESCRIPTION OF SYMBOLS 1... Drill 1A... Drill 1B... Drill 3... Body 3a... Tip 3b... Rear end 5... Shank portion 7... Cutting portion 9... First cutting edge 11... Second cutting edge 13... Flank face 15... First discharge groove 17... Second discharge groove 19... Outer surface 21... Second flank face 23... Third flank face 25... Front margin surface 27... Rear margin surface 29... Clearance surface 31... Ridge line 31a... End (first end) 31b... End (second end) 33... Convex curved portion 35... Straight portion 37... Chamfered region 39... Rear region 41... Region 101... Cutting workpiece 103... Workpiece 105... Machined hole O1... Rotation axis Y1... Rotation direction

Claims

a first cutting blade located on the front end side of the cutting tool, a second cutting blade located on the front end side of the cutting tool and rearward in the direction of rotation of the rotating shaft relative to the first cutting blade, a clearance surface extending rearward in the direction of rotation from the first cutting blade, a first discharge groove extending from the first cutting blade toward the rear end, a second discharge groove extending from the second cutting blade toward the rear end, and an outer circumferential surface located between the first discharge groove and the second discharge groove and extending from the clearance surface toward the rear end, the outer circumferential surface having a front margin surface extending along the first discharge groove, a rear margin surface extending along the second discharge groove, and a clearance surface located between the front margin surface and the rear margin surface, the ridges of the rear margin surface and the clearance surface extending forward in the direction of rotation toward the rear end, The drill, wherein the ridge line includes an end portion of the ridge line that is located forward in the direction of rotation and has a convex curved portion that protrudes forward in the direction of rotation.

2. The drill according to claim 1, wherein the entire ridge line is the convex curved portion.

3. The drill according to claim 1, wherein said ridge line further has a straight portion extending rearward in the direction of rotation from said convex curved portion.

4. The drill according to claim 3, wherein the width of said straight portion in the direction along the rotation direction is greater than the width of said convex curved portion in the direction along the rotation direction.

5. A drill as described in any one of claims 1 to 4, wherein the outer peripheral surface further has a chamfered region sandwiched between the second discharge groove and the rear margin surface, and in a cross section perpendicular to the rotation axis, the chamfered region has a concave curved shape.

6. The drill according to claim 5, wherein the clearance surface has a rear region connected to the rear margin surface, and in a cross section perpendicular to the rotation axis, the rear region has a concave curved shape.

7. The drill according to claim 6, wherein in a cross section perpendicular to said axis of rotation, an angle between said rear region and said rear margin surface is smaller than an angle between said chamfer region and said rear margin surface.

8. A drill according to claim 6 or 7, wherein in a cross section perpendicular to the rotation axis, the angle between the rear region and the rear margin surface, and the angle between the chamfered region and the rear margin surface, are each obtuse angles.

9. The drill according to any one of claims 6 to 8, wherein in a cross section perpendicular to the rotation axis, the radius of curvature of the chamfered region, which is concavely curved, is greater than the radius of curvature of the rear region, which is concavely curved.

10. A drill according to any one of claims 5 to 9, wherein in a cross section perpendicular to the rotation axis, the width of the chamfered region in the direction along the rotation direction is smaller than the width of the rear margin surface in the direction along the rotation direction.

11. The drill according to any one of claims 5 to 10, wherein the radius of curvature of the chamfered region in a cross section perpendicular to the rotation axis is larger than the radius of curvature of the convex curved portion of the ridge line.

12. A method for manufacturing a machined product, comprising the steps of: rotating a drill according to any one of claims 1 to 11; bringing the rotating drill into contact with a workpiece; and removing the drill from the workpiece.

Images