DRILL AND METHOD FOR PRODUCE A MACHINE-MACHINED PRODUCT

Abstract

In a non-limiting aspect of the present disclosure / invention, a drill bit has a rod-shaped body extending along an axis of rotation from a front end to a rear end. The body has an outer circumferential surface located between a first flute and a second flute, extending from a clearance face to the rear end. The outer circumferential surface has a front chamfer extending along the first flute, a rear chamfer extending along the second flute, and a web surface located between the front chamfer and rear chamfer surfaces. A ridge line between the rear chamfer and the clearance face extends toward the rear end, as it rotates toward a front face.The ridge line has a convex-curved section, which has an end part of the ridge line that is located on a front side in the direction of rotation and projects towards a front side in the direction of rotation.

Description

TECHNICAL AREA

[0001] The present disclosure / invention relates to a drill bit and a method for producing a machined product. BACKGROUND

[0002] For example, a drill (drilling tool) described in Japanese Patent Application No. 7-040117 (Patent Document 1) is known as a drill used to perform a milling operation on a workpiece. The drill described in Patent Document 1 has a first chamfer and a second chamfer. The straightness stability of the drill is improved by incorporating a plurality of chamfers.

[0003] In the front end portion of the second chamfer in patent document 1, an end portion located on a front side in a rotational direction is closer to a rear end of the drill than an end portion located on a rear side in the rotational direction. With the above configuration of the second chamfer, the front end portion acts as a flat cutting edge.

[0004] The leading edge of the second chamfer in patent document 1 is relatively susceptible to high cutting forces. Therefore, further improvement of the second chamfer's durability is required. BRIEF EXPLANATION

[0005] In a non-limiting aspect of the present disclosure / invention, a drill bit has a rod-shaped body extending along an axis of rotation from a front end to a rear end. The body has a first cutting edge, a second cutting edge, a clearance face, a first chip groove, a second chip groove, and an outer circumferential surface. The first cutting edge is located on one side of the front end. The second cutting edge is located on one side of the front end and on a rear side in a direction of rotation along the axis of rotation with respect to the first cutting edge. The clearance face extends from the first cutting edge in the direction of rotation to a rear side. The first chip groove extends from the first cutting edge to the rear end. The second chip groove extends from the second cutting edge to the rear end.The outer circumferential surface is located between the first clamping groove and the second clamping groove and extends from the free surface to the rear end.

[0006] The outer circumferential surface has a front chamfer extending along the first span groove, a rear chamfer extending along the second span groove, and a web surface located between the front and rear chamfer surfaces. A ridge line between the rear chamfer surface and the free surface extends towards the rear end, as it rotates towards a front face. The ridge line has a convexly curved section with a terminal portion that is located on a front face and projects forward in the direction of rotation. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view showing a drill bit in a non-restrictive aspect of the present disclosure / invention. Fig. 2 is an enlarged view of one in Fig. 1 shown area II, Fig. 3 is an enlarged view of one in Fig. 2 shown area III, Fig. 4 is a side view of the in Fig. 1 of the drills shown, Fig. 5 is an enlarged view of one in Fig. 4 shown area V, Fig. 6 is an enlarged view of one in Fig. 5 shown area VI, Fig. 7 is a cross-sectional view along line VII-VII in which in Fig. 4 drills shown, Fig. 8 is an enlarged view of one in Fig. 7 shown area VIII, Fig. Figure 9 is a perspective view showing a drill bit in a non-restrictive aspect of the present disclosure / invention and Fig. 3 corresponds to Fig. 10 is a side view showing the Fig. The 9 drills shown are shown and with Fig. 6 corresponds, Fig. Figure 11 is a cross-sectional view showing a drill bit in a non-limiting aspect of the present disclosure / invention and with Fig. 8 corresponds , Fig. Figure 12 is a schematic diagram illustrating one of the steps in a process for producing a machined product in a non-limiting aspect of the present disclosure / invention. Fig. Figure 13 is a schematic diagram illustrating one of the steps in the process for producing the machined product in a non-limiting aspect of the present disclosure / invention, and Fig. Figure 14 is a schematic diagram showing one of the steps in the process for producing the machined product in the non-limiting aspect of the present disclosure / invention. EXECUTION FORMS <bohrer>

[0007] A drill bit 1 in a non-limiting aspect of the present disclosure / invention is described in detail below with reference to the drawings. For the sake of simplicity, each of the following drawings shows, in simplified form, only the main elements necessary to describe embodiments. The drill bit 1 may therefore have any structural elements not shown in the referenced drawings. The dimensions of the elements in each of the drawings do not accurately represent the dimensions of the actual structural elements or the dimensional ratios of these elements.

[0008] The non-restrictive aspect can provide a solid drill as an example for drill 1. However, drill 1 is not limited to solid drills, but could also be, for example, an indexable insert drill.

[0009] The drill 1 can bore a body 3 as in the non-restrictive aspect, as in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. Figure 8 shows that the body 3 can have a rod shape extending along an axis of rotation O1 from a front end 3a to a rear end 3b. The body 3 is rotatable about the axis of rotation O1. An arrow Y1 in Fig. 1 etc. can indicate a direction of rotation of the axis of rotation O1 or can indicate a direction of rotation of the body 3 around the axis of rotation O1.

[0010] The body 3 can have a shank part 5 and a cutting part 7. The shank part 5 can serve as a part that is held by a rotating spindle of a machine tool. The shank part 5 can be designed according to the shape of the spindle in the machine tool.

[0011] The cutting element 7 can be located on one side of the front end 3a with respect to the shaft part 5. The cutting element 7 can serve as a part that can contact a workpiece and plays an important role in a machining operation (for example, a drilling operation) of the workpiece.

[0012] The body 3 need not have specific dimensions. For example, if an outer diameter of the cutting part 7 is designated D, a maximum value of D can be set to approximately 2 to 50 mm. If a length of the cutting part 7 in a direction along the axis of rotation O1 is designated L, L can be set to approximately L = 1.5D to L = 12D.

[0013] The body 3 can have a first cutting edge 9, a second cutting edge 11, a clearance surface 13, a first chip groove 15, a second chip groove 17 and an outer circumferential surface 19, as shown in the Fig. 2. The non-restrictive aspect shown. These parts may be located in cutting part 7.

[0014] The first cutting edge 9 can be located on one side of the front end 3a. The first cutting edge 9 can serve as a part that cuts the workpiece in the machining process. The first cutting edge 9 can be referred to as a main cutting edge.

[0015] The second cutting edge 11 can be located on one side of the front end 3a and on the back side in the rotational direction Y1 of the rotational axis O1 with respect to the first cutting edge 9. The second cutting edge 11 can serve as a component that cuts the workpiece during the machining process. The second cutting edge 11 can also be referred to as a main cutting edge. The second cutting edge 11 can have the same configuration as the first cutting edge 9.

[0016] The number of first cutting edges (9) and second cutting edges (11) can each be one or more. If the number of first cutting edges (9) and second cutting edges (11) is a plurality, they can be arranged alternately in one direction along the direction of rotation Y1.

[0017] If the number of the first cutting edge (9) and the number of the second cutting edge (11) are multiples, their number can be between 2 and 4. The number of the second cutting edge (11) can be the same as the number of the first cutting edge (9). For example, if the number of the first cutting edge (9) is one, the number of the second cutting edge (11) can also be one, as in the Fig. 2. The non-restrictive aspect shown.

[0018] The first cutting edge 9 and the second cutting edge 11 can be arranged such that they have 180° rotational symmetry with respect to the axis of rotation O1. This results in high straightness of the drill 1 during the machining process of the workpiece.

[0019] The clearance surface 13 can extend from the first cutting edge 9 to a back side in the rotational direction Y1. The clearance surface 13 can serve as a component that reduces cutting resistance by preventing contact with the workpiece. The clearance surface 13 can be connected to the first cutting edge 9.

[0020] The free area 13 can have a second free area 21 and a third free area 23. The second free area 21 can be arranged along the first cutting edge 9. The second free area 21 can be connected to the first cutting edge 9. The second free area 21 can be flat.

[0021] The third free surface 23 can be arranged along the back side of the second free surface 21 in the direction of rotation Y1. The third free surface 23 can be connected to the second free surface 21. The third free surface 23 can be inclined relative to the second free surface 21. The third free surface 23 can be flat.

[0022] The first chip groove 15 can extend from the first cutting edge 9 to the rear end 3b. The first chip groove 15 can serve as a component that removes chips produced by the first cutting edge 9 to the outside. The first chip groove 15 can extend parallel to the axis of rotation O1 or can extend spirally around the axis of rotation O1. The number of first chip grooves 15 can be the same as the number of first cutting edges 9.

[0023] The first chip groove 15 can be connected to the first cutting edge 9. This leads to improved penetration into the workpiece. A rake face connecting the first chip groove 15 and the first cutting edge 9 can be located between them. In this case, the chip evacuation direction of the chips produced by the first cutting edge 9 tends to be stable. From the perspective of smooth chip evacuation to the outside, the first chip groove 15 can have a concave-curved shape in a cross-section orthogonal to the axis of rotation O1.

[0024] The second chip groove 17 can extend from the second cutting edge 11 to the rear end 3b. The second chip groove 17 can serve as a component that removes chips produced by the second cutting edge 11 to the outside. The second chip groove 17 can extend parallel to the axis of rotation O1 or can extend spirally around the axis of rotation O1. The number of second chip grooves 17 can be the same as the number of second cutting edges 11.

[0025] For the same reason as with the first chip groove 15, the second chip groove 17 can be connected to the second cutting edge 11. A rake face connecting the second chip groove 17 and the second cutting edge 11 can be located between them. The second chip groove 17 can have a concave-curved shape in a cross-section orthogonal to the axis of rotation O1.

[0026] The depth of each of the first flute 15 and the second flute 17 need not have a specific value. For example, the depth of the first flute 15 can be set to 1.5% to 10%, and the depth of the second flute 17 can be set to 15% to 40% of an outer diameter of the body 3 (cutting part 7). In a cross-section orthogonal to the axis of rotation O1, the depth of the first flute 15 can be a value obtained by subtracting a distance between the bottom of the first flute 15 and the axis of rotation O1 from a radius of the body 3 (cutting part 7). The bottom of the first flute 15 can be the part closest to the axis of rotation O1 within the first flute 15. The depth of the second flute 17 can be defined in the same way as the depth of the first flute 15.

[0027] The outer circumferential surface 19 can be located between the first clamping groove 15 and the second clamping groove 17. The outer circumferential surface 19 can extend from the free surface 13 to the rear end 3b. The outer circumferential surface 19 can be connected to the first clamping groove 15 and the second clamping groove 17. The outer circumferential surface 19 can be connected to the free surface 13.

[0028] The outer circumferential surface 19 can have a front chamfered surface 25, a rear chamfered surface 27 and a web surface 29.

[0029] The front chamfer surface 25 can extend along the first chip groove 15. The rear chamfer surface 27 can extend along the second chip groove 17. The front chamfer surface 25 and the rear chamfer surface 27 can serve as a component that stabilizes the functionality of the drill 1 by means of sliding contact with an inner wall surface of a machined hole in a workpiece. If the outer circumferential surface 19 has the front chamfer surface 25 and the rear chamfer surface 27, the drill 1 has high straightness. In cross-section orthogonal to the axis of rotation O1, the front chamfer surface 25 and the rear chamfer surface 27 can form a component with a circular arc shape corresponding to the outer circumference of the body 3.

[0030] The web surface 29 can be positioned between the front chamfer surface 25 and the rear chamfer surface 27. The web surface 29 can serve as a component that reduces friction against a workpiece during a machining operation. The web surface 29 can be recessed relative to the front chamfer surface 25 and the rear chamfer surface 27. The web surface 29 can be connected to the front chamfer surface 25 and the rear chamfer surface 27.

[0031] A ridge line 31 between the rear chamfer surface 27 and the free surface 13 can extend towards the rear end 3b as it moves in the rotation direction Y1 towards a front face, as in the non-restrictive aspect in Fig. Figure 6 shows this configuration. This configuration can be evaluated in a side view. The side view can be a state as seen from a direction orthogonal to the axis of rotation O1. If the ridge line 31 extends towards the rear end 3b, as it moves towards a front in the direction of rotation Y1, the ridge line 31 can serve as a flat cutting edge.

[0032] The ridge line 31 can have a convex-curved section 33. The convex-curved section 33 can have an end part 31a of the ridge line 31, which is located on a front side in the direction of rotation Y1. The convex-curved section 33 can project towards a front side in the direction of rotation Y1. The end part 31a of the ridge line 31, which is located on the front side in the direction of rotation Y1, and the area surrounding the end part 31a are susceptible to relatively high cutting loads. If the ridge line 31 has the convex-curved section 33, the ridge line 31 has high resistance to the cutting loads. Therefore, the drill 1 has high resistance.

[0033] The ridge line 31 may also have a straight section 35, as in the non-restrictive aspect in Fig. Figure 6 shows that the straight section 35 can extend from the convex-curved section 33 in the rotational direction Y1 towards a back side. In this case, it is easy to avoid a situation where the comb line 31 excessively scrapes along a workpiece. Therefore, it is possible to reduce the cutting resistance. Consequently, wear of the comb line 31 can be reduced, and the service life of the drill 1 tends to be improved.

[0034] The straight section 35 can be connected to the convex-curved section 33. The straight section 35 can have an end part 31b of the crest line 31, which is located on a back side in the direction of rotation Y1. The end part 31a, which is located on the front side in the direction of rotation Y1, can be located closer to the rear end 3b than the end part 31b, which is located on the back side in the direction of rotation Y1. The end part 31a can be referred to as a first end part 31a, and the end part 31b can be referred to as a second end part 31b.

[0035] The width W35 of the straight section 35 in a direction along the rotation direction Y1 can be equal to or different from the width W33 of the convex-curved section 33 in the direction along the rotation direction Y1. For example, the width W35 of the straight section 35 can be greater than the width W33 of the convex-curved section 33, as in the Fig. 6 shown, non-restrictive aspect. In this case, it is less likely that the convex-curved section 33 and the straight section 35 will simultaneously come into contact with the workpiece when the drill 1 penetrates a workpiece during a drilling operation, and a contact area with the workpiece gradually expands from a boundary between the convex-curved section 33 and the straight section 35, resulting in a gradual increase in cutting resistance. The width W35 of the straight section 35 and the width W33 of the convex-curved section 33 need not have a specific value.

[0036] The outer circumferential surface 19 can furthermore have a chamfered area 37, as shown in Fig. 3 shown, non-restrictive aspect. The chamfered area 37 can be located between the second clamping groove 17 and the rear chamfer surface 27. In this case, it is possible to reduce stress concentration between the rear chamfer surface 27 and the second clamping groove 17, and it is easy to mitigate the risk of sudden fracture.

[0037] The chamfered area 37 can be connected to the second clamping groove 17 and the rear chamfered surface 27. The chamfered area 37 can have a straight shape in a cross-section orthogonal to the axis of rotation O1, as in the non-restrictive aspect in Fig. 8 shown. The chamfered area 37 can be inclined with respect to the rear chamfered surface 27.

[0038] The web surface 29 can have a rear area 39, as in the non-restrictive aspect in Fig. Figure 8 shows that the rear region 39 can be connected to the rear chamfer surface 27. The rear region 39 can have a concave-curved shape in cross-section orthogonal to the axis of rotation O1. In these cases, fine chips generated during machining can be carried outwards through the concave-curved rear region 39. Consequently, chips are less likely to become trapped in the rear chamfer surface 27, and the body 3 is less susceptible to damage.

[0039] In cross-section orthogonal to the axis of rotation O1, an angle θ1 formed by the rear section 39 and the rear chamfered surface 27 can be equal to or different from an angle θ2 formed by the chamfered section 37 and the rear chamfered surface 27. For example, in cross-section orthogonal to the axis of rotation O1, the angle θ1 can be smaller than the angle θ2, as in the non-restrictive aspect in Fig. 8 shown. In this case, it is possible to maintain a large space of the rear area 39, which is located in the rotation direction Y1 on a front side with respect to the rear chamfer surface 27, and it is easy to direct a large amount of chips to the rear area 39.

[0040] If the rear region 39 has a concave-curved shape in cross-section orthogonal to the axis of rotation O1, a tangent can be defined at a boundary with the rear chamfer surface 27 and the angle θ1 formed by means of the rear region 39 and the rear chamfer surface 27 can be determined by means of an angle at which the tangent and the rear chamfer surface 27 intersect.

[0041] As in the Fig. In the non-restrictive aspect shown in Figure 8, the angle θ1, formed by the rear section 39 and the rear chamfered surface 27, and the angle θ2, formed by the beveled section 37 and the rear chamfered surface 27, can each be an obtuse angle in cross-section orthogonal to the axis of rotation O1. In this case, it is possible to improve the stiffness of the drill 1 and to stabilize the drilling process.

[0042] Angles θ1 and θ2 do not need to have specific values. For example, angle θ1 can be set to 60–145°, and angle θ2 to 80–155°. Angle θ1 can be referred to as the first angle θ1, and angle θ2 can be referred to as the second angle θ2.

[0043] In cross-section orthogonal to the axis of rotation O1, the width W37 of the chamfered region 37 in a direction along the direction of rotation Y1 can be equal to or different from the width W27 of the rear chamfered surface 27 in the direction along the direction of rotation Y1. For example, in cross-section orthogonal to the axis of rotation O1, the width W37 of the chamfered region 37 can be smaller than the width W27 of the rear chamfered surface 27, as in the non-restrictive aspect in Fig. 8 shown. In this case, it is possible to serve stably as a chamfer on the rear chamfer surface 27, since the rear chamfer surface 27 and the second clamping groove 17 are located close to each other.

[0044] The width W37 of the chamfered area 37 and the width W27 of the rear chamfered surface 27 need not have a specific value. For example, in the cross-section orthogonal to the axis of rotation O1, the width W37 of the chamfered area 37 can be set to 1 to 10% and the width W27 of the rear chamfered surface 27 can be set to 3 to 10%, with respect to a total length of the outer circumference of the body 3 (cutting part 7).

[0045] As in Fig. In the non-restrictive aspect shown in Figure 7, the width W27 of the rear chamfer surface 27 can be greater than the width W25 of the front chamfer surface 25 in the direction along the rotation direction Y1 in the cross-section orthogonal to the rotation axis O1. Similarly, in the cross-section orthogonal to the rotation axis O1, the width W29 of the web surface 29 in the direction along the rotation direction Y1 can be greater than both the width W25 of the front chamfer surface 25 and the width W27 of the rear chamfer surface 27.

[0046] The width W25 of the front chamfer surface 25 and the width W29 of the web surface 29 need not have a specific value. For example, in the cross-section orthogonal to the axis of rotation O1, the width W25 of the front chamfer surface 25 can be set to 3 to 8% and the width W29 of the web surface 29 can be set to 10 to 25%, with respect to the total length of the outer circumference of the body 3 (cutting part 7).

[0047] The free area 13 can have a region 41 extending from the convex-curved section 33 towards the axis of rotation O1 and having a convex-curved surface shape, as in the non-restrictive aspect in Fig. Figure 3 shows that in this case, it is possible to improve the strength of the rear chamfer surface 27, and the rear chamfer surface 27 is thus protected. The region 41 can extend in the rotation direction Y1 towards a front face as it moves away from the convexly curved section 33. The width of the region 41 in a direction along the rotation axis O1 can decrease as it approaches the rotation axis O1. The region 41 can be connected to the convexly curved section 33. The region 41 can be connected to the third free surface 23. The region 41 can be located away from the second free surface 21.

[0048] Examples of materials in 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 can be hard particles, and Co can be a binder phase.

[0049] Cermet can be a sintered composite material made by incorporating metal into a ceramic component. Specific examples of cermet may include titanium compounds, primarily composed of titanium carbide (TiC) or titanium nitride (TiN). However, the above materials are not limiting examples, and there is no intention to restrict the material of Body 3 to these materials.

[0050] A surface of body 3 can be coated with a layer using a chemical vapor deposition (CVD) or a physical vapor deposition (PVD) process. Examples of coating layer compositions include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and aluminum oxide (Al₂O₃).

[0051] Next, with reference to the drawings, a drill 1A is described in a further non-limiting aspect of the present disclosure / invention. The following mainly describes differences between drill 1A and drill 1, and a detailed description of a configuration identical to that of drill 1 can be omitted. Therefore, reference can be made to the description of drill 1 for an explanation of the configuration of drill 1A. This also applies to drill 1B, which is described later.

[0052] As in a non-restrictive aspect that is in the Fig. 9 and Fig. As shown in Figure 10, the entire ridge line 31 can be the convex-curved section 33 in the drill bit 1A. In other words, the convex-curved section 33 can further include the end part 31b of the ridge line 31, which is located on a back side in the rotational direction Y1. In this case, the ridge line 31 has a further improved resistance to cutting forces.

[0053] Subsequently, with reference to the drawings, a drill bit 1B is described in a further non-limiting aspect of the present disclosure / invention.

[0054] As regards the drill bit 1B, the outer circumferential surface 19 may further have a chamfered area 37 located between the second chip groove 17 and the rear chamfered surface 27, as shown in a non-restrictive aspect in Fig. Figure 11 shows that the chamfered area 37 can have a concave-curved shape in cross-section orthogonal to the axis of rotation O1. In these cases, chips are easily carried outwards. Therefore, it is less likely that the drilling operation will be carried out in a condition where chips adhere to the chamfered area 37, and a machined surface is less susceptible to damage by the chips.

[0055] For the same reason as with drill 1, the web surface 29 can have the rear region 39, which is connected to the rear chamfer surface 27 in drill 1B. The rear region 39 can have a concave-curved shape in cross-section orthogonal to the axis of rotation O1.

[0056] In cross-section orthogonal to the axis of rotation O1, the radius of curvature of the chamfered region 37, which has the concave-curved shape, can be the same as or different from the radius of curvature of the rear region 39, which also has the concave-curved shape. For example, in cross-section orthogonal to the axis of rotation O1, as in the figure shown in Fig. As shown in Figure 11, the non-restrictive aspect is that the radius of curvature of the chamfered area 37, which has the concave-curved shape, may be larger than the radius of curvature of the rear area 39, which also has the concave-curved shape. In this case, it is possible to improve the stiffness of the rear chamfered surface 27.

[0057] In cross-section orthogonal to the axis of rotation O1, the radius of curvature of the chamfered region 37 can be larger than a radius of curvature of the convex-curved section 33 on the crest line 31 (see Fig. 6, Fig. 10 and Fig. 11) If the radius of curvature of the chamfered area 37 is relatively large, it is less likely that the drilling operation will be carried out in a condition where chips will adhere to the chamfered area 37. If the radius of curvature of the convex-curved section 33 is relatively small, it is less likely that chips will become trapped in the convex-curved section 33. Accordingly, the drill 1B is less prone to breakage, and the inner wall surface of a machined hole is less susceptible to damage.

[0058] The radius of curvature of each of the chamfered region 37, the rear region 39, and the convex-curved section 33 need not have a specific value. For example, the radius of curvature of the chamfered region 37 can be set to 3 to 20 mm. The radius of curvature of the rear region 39 can be set to 0.4 to 3 mm. The radius of curvature of the convex-curved section 33 can be set to 0.2 to 2 mm.

[0059] For the same reason as drill bit 1, drill bit 1B can have the following configuration.

[0060] This means that in the drill bit 1B, in the cross-section orthogonal to the axis of rotation O1, the width W37 of the chamfered area 37 in a direction along the direction of rotation Y1 can be smaller than the width W27 of the rear chamfered surface 27 in the direction along the direction of rotation Y1.

[0061] Furthermore, in the drill 1B, in the cross-section orthogonal to the axis of rotation O1, an angle θ1, which is formed by means of the rear region 39 and the rear chamfer surface 27, can be smaller than an angle θ2, which is formed by means of the chamfered region 37 and the rear chamfer surface 27.

[0062] In the drill 1B, the angle θ1, which is formed by means of the rear area 39 and the rear chamfer surface 27, and the angle θ2, which is formed by means of the chamfered area 37 and the rear chamfer surface 27, can each be an obtuse angle in the cross-section orthogonal to the axis of rotation O1.

[0063] If the chamfered area 37 has a concave-curved shape in cross-section orthogonal to the axis of rotation O1, a tangent can be defined at a boundary with the rear chamfer surface 27, and the angle θ2 formed by means of the chamfered area 37 and the rear chamfer surface 27 can be determined by means of an angle at which the tangent and the rear chamfer surface 27 intersect. <Verfahren zum Herstellen eines maschinell-bearbeiteten Produkts>

[0064] A method for producing a machined product 101 in a non-limiting aspect of the present disclosure / invention is described below with reference to the drawings by way of the example of the use of the drill 1.

[0065] The machined product 101 can be produced by machining a workpiece 103. The method for producing the machined product 101 can comprise the following steps (1) to (4). (1) Positioning the drill bit 1 over the workpiece 103 (see Fig. 12). (2) Rotating the drill 1 about the axis of rotation O1 in a direction of an arrow Y1 and bringing the drill 1 close to the workpiece 103 (see Fig. 12).

[0066] In steps (1) and (2), for example, the workpiece 103 can be fixed to a table of a machine tool to which the drill 1 is attached, and the rotating drill 1 can be brought close to the workpiece 103. In step (2), the workpiece 103 and the drill 1 can be brought close to each other. For example, the workpiece 103 can be brought close to the drill 1. (3) Forming a machined hole 105 in the workpiece 103 by bringing the drill 1 even closer to the workpiece 103 so that the rotating drill 1 can come into contact with the workpiece 103 (see Fig. 13).

[0067] In step (3), the machining can be performed such that at least part of the cutting section 7 in the body 3 is located within the machined hole 105. In step (3), it can be specified that the shank section 5 in the body 3 is located outside the machined hole 105. From the perspective of achieving good surface quality, the setting can be such that a portion on one side of the rear end 3b in the cutting section 7 is located outside the machined hole 105. This portion can serve as a chamfer area for chip evacuation, thus providing excellent chip removal performance through this area. (4) Moving the drill bit 1 away from the workpiece 103 (see Fig. 14).

[0068] In step (4) the workpiece 103 and the drill 1 can be separated from each other. For example, the workpiece 103 can be moved away from the drill 1.

[0069] The machined product 101, which has the high-precision machined hole 105, can be obtained by performing the steps above. In particular, when the drill 1 is used in the process for manufacturing the machined product 101, it is possible to achieve excellent machinability, as the drill 1 has high durability. Consequently, it is possible to obtain the machined product 101, which has the high-precision machined hole 105.

[0070] In cases where the machining of the workpiece 103 is carried out a plurality of times and, for example, a plurality of machined holes 105 are formed in the single workpiece 103, the step of bringing the drill 1 into contact with different sections of the workpiece 103 can be repeated while the drill 1 is rotating.

[0071] Examples of materials for workpiece 103 include aluminium, carbon steel, alloy steel, stainless steel, cast iron and non-ferrous metals.

[0072] Although the drill bit 1 in the Fig. 12, Fig. 13 to Fig. Since the non-restrictive aspect shown in Figure 14 is used, there is no intention to limit the design to this embodiment. For example, drill bit 1A or drill bit 1B can be used instead of drill bit 1.

[0073] The drills 1, 1A and 1B and the method for producing the machined product 101 in the non-limiting aspects of the present disclosure / invention have been described by way of examples; however, there is no intention to limit oneself to the embodiments described above. It is obvious that any embodiments can be produced without departing from the essentials of the present disclosure / invention.

[0074] For example, the drills 1, 1A and 1B and the method for producing the machined product 101 can have the following configurations. [1] A drill bit has a body that is rod-shaped and extends along an axis of rotation from a front end to a rear end hi. The body has a first cutting edge, a second cutting edge, a clearance face, a first chip groove, a second chip groove, and an outer circumferential surface. The first cutting edge is located on one side of the front end. The second cutting edge is located on one side of the front end and on a rear side in a direction of rotation along the axis of rotation with respect to the first cutting edge. The clearance face extends from the first cutting edge in the direction of rotation to a rear side. The first chip groove extends from the first cutting edge to the rear end. The second chip groove extends from the second cutting edge to the rear end. The outer circumferential surface is located between the first chip groove and the second chip groove and extends from the clearance face to the rear end.The outer circumferential surface has a front chamfer extending along the first span groove, a rear chamfer extending along the second span groove, and a web surface located between the front and rear chamfer surfaces. A ridge line between the rear chamfer surface and the free surface extends towards the rear end, as it rotates towards a front face. The ridge line has a convexly curved section with a terminal portion that is located at a front face and projects forward towards a front face in the direction of rotation. [2] In the drill according to [1], an entire ridge line can be the convex-curved section. [3] In the drill according to [1] the ridge line may also have a straight section extending from the convex-curved section in the direction of rotation to a rear side. [4] In the drill according to [3], the width of the straight section in a direction along the direction of rotation can be greater than the width of the convex-curved section in the direction along the direction of rotation. [5] In the drill according to any one of [1] to [4], the outer circumferential surface may further have a chamfered region located between the second flute and the rear chamfered surface. The chamfered region may have a concave-curved shape in a cross-section orthogonal to the axis of rotation. [6] In the drill according to [5], the web surface can have a rear region which is connected to the rear chamfer surface. The rear region can have a concave-curved shape in a cross-section orthogonal to the axis of rotation. [7] In the drill according to [6], in a cross-section orthogonal to the axis of rotation, an angle formed by means of the rear area and the rear chamfer surface can be smaller than an angle formed by means of the chamfered area and the rear chamfer surface. [8] In the drill according to [6] or [7], in a cross-section orthogonal to the axis of rotation, an angle formed by means of the rear area and the rear chamfer surface and an angle formed by means of the beveled area and the rear chamfer surface can each be an obtuse angle. [9] In the drill according to any of [6] to [8], in a cross-section orthogonal to the axis of rotation, the radius of curvature of the chamfered area having a concave-curved shape may be larger than the radius of curvature of the rear area having a concave-curved shape.

[10] In the drill according to any one of [5] to [9], in a cross-section orthogonal to the axis of rotation, the width of the chamfered area in a direction along the direction of rotation may be smaller than the width of the rear chamfered surface in the direction along the direction of rotation.

[11] In the drill according to any one of [5] to

[10] , in a cross-section orthogonal to the axis of rotation, the radius of curvature of the chamfered area may be greater than the radius of curvature of the convex curved section at the crest line.

[12] A method for producing a machined product may include: rotating the drill according to any of [1] to

[11] , bringing the rotating drill into contact with a workpiece and moving the drill away from the workpiece. Description of reference symbols 1 drill bit 1A drill 1B drill bit 3 bodies 3a front end 3b rear end 5 shaft section 7 Cutting part 9 first cutting edge 11 second cutting edge 13 open space 15 first span groove 17 second span 19 External perimeter area 21 second open space 23 third open space 25 front chamfered surface 27 rear chamfer surface 29 pier area 31 Ridge line 31a End part (first end part) 31b End part (second end part) 33 convex-curved section 35 straight section 37 beveled area 39 rear area 41 area 101 machine-made product 103 workpiece 105 machined holes O1 Rotation axis Y1 Rotation direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 7-040117

[0002] < / bohrer>

Claims

[1] A drill bit which has: a body that has a rod shape and extends along an axis of rotation from a front end to a rear end, wherein the body exhibits a first cutting edge located on one side of the front end, a second cutting edge located on one side of the front end and on a rear side in a direction of rotation of the axis of rotation with respect to the first cutting edge, a free area extending from the first cutting edge in the direction of rotation towards a back side, a first groove extending from the first cutting edge to the rear end, a second flute extending from the second cutting edge to the rear end, and an outer circumferential surface located between the first span groove and the second span groove, extending from the free surface to the rear end, where the outer circumferential surface has a front chamfered surface extending along the first span groove, a rear chamfered surface extending along the second span groove, and a web surface located between the front chamfer surface and the rear chamfer surface, wherein a ridge line between the rear chamfered surface and the free surface extends towards the rear end, as it moves towards a front in the direction of rotation, and wherein the ridge line has a convex-curved section which has an end part of the ridge line which is located on a front side in the direction of rotation and projects towards a front side in the direction of rotation. [2] The drill according to claim 1, wherein the entire ridge line is the convex-curved section. [3] The drill according to claim 1, wherein the ridge line further comprises a straight section extending from the convex-curved section to a rear side in the direction of rotation. [4] The drill according to claim 3, wherein a width of the straight section in a direction along the direction of rotation is greater than a width of the convex curved section in the direction along the direction of rotation. [5] The drill according to any one of claims 1 to 4, wherein the outer circumferential surface furthermore has a chamfered area located between the second clamping groove and the rear chamfered surface, and The beveled area has a concave-curved shape in a cross-section orthogonal to the axis of rotation. [6] The drill according to claim 5, wherein the web surface has a rear area that is connected to the rear chamfered surface, and The rear area has a concave-curved shape in cross-section, orthogonal to the axis of rotation. [7] The drill according to claim 6, wherein in a cross-section orthogonal to the axis of rotation an angle formed by means of the rear region and the rear chamfer surface is smaller than an angle formed by means of the chamfered region and the rear chamfer surface. [8] The drill according to claim 6 or 7, wherein in a cross-section orthogonal to the axis of rotation an angle formed by means of the rear region and the rear chamfer surface and an angle formed by means of the beveled region and the rear chamfer surface are each obtuse angles. [9] The drill according to any one of claims 6 to 8, wherein in a cross-section orthogonal to the axis of rotation a radius of curvature of the chamfered area having a concave-curved shape is greater than a radius of curvature of the rear area having a concave-curved shape. [10] The drill according to any one of claims 5 to 9, wherein in a cross-section orthogonal to the axis of rotation a width of the chamfered area in a direction along the direction of rotation is smaller than a width of the rear chamfered surface in the direction along the direction of rotation. [11] The drill according to any one of claims 5 to 10, wherein in a cross-section orthogonal to the axis of rotation a radius of curvature of the chamfered area is greater than a radius of curvature of the convex curved section at the crest line. [12] A method for producing a machine-made product comprising: Rotating the drill bit according to any one of claims 1 to 11, Bringing the rotating drill into contact with a workpiece and Moving the drill away from the workpiece.

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