Cutting insert, cutting tool, and method for manufacturing cut workpiece

Abstract

A cutting insert according to one non-limiting aspect of the present disclosure has a rod shape extending along a central axis from a tip end to a rear end. The cutting insert has a body section, and a cutting section that is located further toward the tip end side than the body section. The cutting section has a tip end surface that is located on the tip end side, an upper surface that extends from the tip end surface toward the body section, and a tip end blade that is located at the intersection of the tip end surface and the upper surface. The upper surface has a pair of first breaker protrusions that each extend from the body section side toward the tip end surface, and a second breaker protrusion that is located between the pair of first breaker protrusions. The second breaker protrusion has a flat surface that slants upward toward the body section.

Description

Cutting insert, cutting tool, and method for manufacturing machined product CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2023-151945, filed on September 20, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a cutting insert and a cutting tool used in cutting a workpiece, and a method for manufacturing a machined product. Examples of cutting include turning and milling. Examples of turning include internal diameter machining, external diameter machining, grooving, and cut-off.

[0003] An example of a cutting tool used when cutting a workpiece is the cutting tool described in Japanese Patent Laid-Open No. 9-174308 (Patent Document 1). The cutting tool described in Patent Document 1 has a holder and a cutting insert (hereinafter simply referred to as "insert"). The insert described in Patent Document 1 has a pair of breaker protrusions extending from a tip cutting edge. During cutting, chips are brought into contact with the pair of breaker protrusions to deform the chips and control the speed at which the chips flow.

[0004] However, a simple design with only a pair of breaker protrusions is not very versatile for various cutting conditions and workpiece materials. For example, when cutting with a small feed rate or when cutting soft materials such as aluminum or low-carbon steel, it is difficult to control the deformation of the chips, and the breaker protrusions have limited effect on controlling the speed at which the chips flow, i.e., on braking the chips.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an insert that is highly versatile in terms of cutting conditions and types of workpiece materials.

[0006] A non-limiting one-sided cutting insert of the present disclosure has a rod shape extending along a central axis from a tip end to a rear end. The cutting insert has a body portion and a cutting portion located closer to the tip end than the body portion. The cutting portion has a tip surface located closer to the tip end, an upper surface extending from the tip surface toward the body portion, and a tip cutting edge located at the intersection of the tip surface and the upper surface. The upper surface has a pair of first breaker protrusions each extending from the body portion side toward the tip surface, and a second breaker protrusion located between the pair of first breaker protrusions. The second breaker protrusion has a flat surface that slopes upward as it approaches the body portion.

[0007] 1 is a perspective view showing an unlimited single-sided cutting insert of the present disclosure; FIG. 2 is an enlarged view of region II shown in FIG. 1; FIG. 3 is a plan view showing the upper surface of the cutting insert shown in FIG. 1 from the front; FIG. 4 is an enlarged view of region IV shown in FIG. 3; FIG. 5 is a side view of the cutting insert shown in FIG. 3 as viewed from direction V; FIG. 6 is an enlarged view of region VI shown in FIG. 5; FIG. 6 is a plan view of the cutting insert shown in FIG. 3 as viewed from direction VII; FIG. 7 is an enlarged view of the tip side of the cutting insert shown in FIG. 3; FIG. 8 is a cross-sectional view of section IX of the cutting insert shown in FIG. 8; FIG. 9 is a cross-sectional view of section X of the cutting insert shown in FIG. 8; FIG. 9 is a cross-sectional view of section XI of the cutting insert shown in FIG. 8; FIG. 10 is a cross-sectional view of section XII of the cutting insert shown in FIG. 8; FIG. 11 is a perspective view showing an unlimited single-sided cutting tool of the present disclosure; FIG. 12 is a schematic view showing one step in an unlimited method of manufacturing a single-sided machined product of the present disclosure; FIG. 13 is a schematic view showing one step in an unlimited method of manufacturing a single-sided machined product of the present disclosure; FIG. 14 is a schematic view showing one step in an unlimited method of manufacturing a single-sided machined product of the present disclosure;

[0008] <Cutting Insert> Hereinafter, a non-limiting one-sided cutting insert 1 (hereinafter also simply referred to as "insert 1") of the present disclosure will be described in detail with reference to the drawings. However, for the sake of convenience, in each of the drawings referred to below, only the main components necessary for explaining the embodiment are shown in a simplified form. Therefore, the insert 1 may include any components not shown in each of the drawings referred to. Furthermore, the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components and the dimensional ratios of each component. Note that, for ease of visual understanding, specific regions of the insert 1 are shaded in FIG. 4.

[0009] The insert 1 may have a rod shape extending along the central axis O1 from the front end 1a to the rear end 1b, as in the non-limiting example shown in Figures 1 to 12. The insert 1 may have a prismatic shape. The insert 1 may have a quadrangular prism shape. Note that the quadrangular prism shape may be roughly a quadrangular prism shape, and does not necessarily have to be a quadrangular prism shape in the strict sense.

[0010] The insert 1 may have a body portion 3 and a cutting portion 5, as shown by way of non-limiting example in FIGS.

[0011] The main body portion 3 can function as a portion that is fixed to the holder when the insert 1 is attached to the holder. The main body portion 3 may be located at the center of the insert 1 in the direction along the central axis O1.

[0012] The cutting portion 5 may be located closer to the tip 1a than the main body portion 3. The cutting portion 5 is capable of coming into contact with the workpiece, and can function as a portion that plays a major role in cutting (e.g., grooving) the workpiece.

[0013] The insert 1 may further include a cutting portion 7 located closer to the rear end 1b than the main body portion 3. In this case, the cutting portion 5 may be referred to as the first cutting portion 5, and the cutting portion 7 may be referred to as the second cutting portion 7. The second cutting portion 7 may have the same configuration as the first cutting portion 5. Therefore, the description regarding the first cutting portion 5 may be used to understand the configuration of the second cutting portion 7.

[0014] The cutting portion 5 may have a tip surface 9, an upper surface 11, and a tip cutting edge 13, as shown in a non-limiting example in FIG.

[0015] The tip surface 9 may be located on the tip 1 a side. The upper surface 11 may extend from the tip surface 9 toward the main body portion 3.

[0016] The upper surface 11 is a convenient expression and does not indicate an upward direction. For example, the upper surface 11 does not need to face upward when the insert 1 is used. This also applies to other parts that include the expressions "up" and "down." Furthermore, the positional relationship in the up-down direction may be specified by defining a direction perpendicular to the central axis O1, from the central axis O1 toward the upper surface 11 as "upward," and a direction from the upper surface 11 toward the central axis O1 as "downward."

[0017] The tip cutting edge 13 may be located at the intersection of the tip surface 9 and the top surface 11. The tip cutting edge 13 may be located over the entire intersection, or may be located over only a portion of the intersection. The tip cutting edge 13 can be used to cut a workpiece when manufacturing a machined product using the insert 1. The tip cutting edge 13 may also be generally referred to as a leading cutting edge or a main cutting edge.

[0018] The tip cutting edge 13 may have a straight line shape or a curved line shape when viewed from the tip or from above. The tip cutting edge 13 may also have a shape that combines a straight line and a curved line when viewed from the tip or from above. For example, as in a non-limiting example shown in FIG. 7, the tip cutting edge 13 may have a straight line shape when viewed from the tip. Also, as in a non-limiting example shown in FIG. 4, the tip cutting edge 13 may have a straight line shape when viewed from above.

[0019] The term "tip view" may refer to a state viewed from the side of the tip 1a. The term "top view" may refer to a state viewed from the side of the top surface 11. In other words, the term "top view" may refer to a state where the top surface 11 is viewed from the front.

[0020] Here, the top surface 11 may have a pair of first breaker protrusions 15 and one or more second breaker protrusions 17, as in the non-limiting examples shown in Figures 2 and 4. The pair of first breaker protrusions 15 may each extend from the side of the main body 3 toward the tip surface 9. The second breaker protrusion 17 may be located between the pair of first breaker protrusions 15. The second breaker protrusion 17 may have a flat surface 19. The flat surface 19 may be inclined upward as it approaches the main body 3, as in the non-limiting example shown in Figure 11. In these cases, the insert 1 has excellent versatility for various cutting conditions and types of workpiece materials.

[0021] Specifically, in cutting processes with a large feed rate or cutting hard materials such as titanium alloys or high-carbon steel, it is easy to stably deform chips at the first breaker protrusion 15. In addition, it is easy to control the speed at which chips flow at the first breaker protrusion 15.

[0022] Even when it is difficult to control chip deformation in cutting with a small feed rate or when cutting soft materials such as aluminum or low-carbon steel, the chips can come into contact with the second breaker protrusion 17 in addition to the pair of first breaker protrusions 15. This provides a high braking effect on the chips.

[0023] Furthermore, the second breaker protrusion 17 does not have a convex curved shape as a whole, but has a flat surface 19 that slopes upward as it approaches the main body 3. Therefore, the insert 1 is configured so that chips can easily come into contact with the second breaker protrusion 17. Furthermore, because the flat surface 19 is flat, chips can easily come into surface contact with the second breaker protrusion 17. This further enhances the braking effect of the second breaker protrusion 17 on chips. Therefore, the insert 1 is highly versatile in terms of cutting conditions and types of workpiece materials.

[0024] The flat surface 19 may be a flat surface. Flat does not necessarily have to be flat in the strict sense. The flat surface 19 may be generally flat, and may be slightly curved or have slight irregularities that are not noticeable when the insert 1 is viewed as a whole. For example, the flat surface 19 may have slight irregularities of about several tens of μm.

[0025] In the non-limiting example shown in FIG. 8, the outer edges of the first breaker protrusion 15, the second breaker protrusion 17, and the plane 19 are shown with thick lines to facilitate visual understanding of the extent of these portions.

[0026] 2 and 4, the second breaker protrusion 17 may be connected to the first breaker protrusion 15. In this case, it is easy to prevent chips from getting stuck between the first breaker protrusion 15 and the second breaker protrusion 17.

[0027] The upper surface 11 may have a plurality of second breaker protrusions 17. When the upper surface 11 has a plurality of second breaker protrusions 17, the number of the second breaker protrusions 17 may be 2 to 4. In a non-limiting example shown in FIG. 4 etc., an example of the second breaker protrusions 17 may show a case where there are two second breaker protrusions 17.

[0028] As a non-limiting example shown in Figure 4, when the top surface 11 is viewed from the front, the multiple second breaker protrusions 17 may be spaced apart from one another across the central axis O1. In this case, it is easy to ensure chip deformation in the direction along the tip cutting edge 13. When the chip is deformed in this way, the chip tends to harden. Therefore, chip deformation by the first breaker protrusion 15 and the second breaker protrusion 17 tends to be stable.

[0029] 4, when the upper surface 11 is viewed from the front, the plurality of second breaker protrusions 17 may be aligned in a direction along the cutting edge 13. In this case, it is easy to synchronize the timing at which the chips come into contact with each of the plurality of second breaker protrusions 17, and the chips tend to advance in a direction perpendicular to the cutting edge 13. Therefore, the chips tend to curl stably, and the chips tend to have a vortex shape rather than a helical shape.

[0030] When the upper surface 11 is viewed from the front, the width W1 of the flat surface 19 in a direction perpendicular to the central axis O1 may be the same as or different from the width W2 of the flat surface 19 in a direction along the central axis O1. For example, as shown in a non-limiting example in FIG. 4, when the upper surface 11 is viewed from the front, the width W1 of the flat surface 19 in a direction perpendicular to the central axis O1 may be larger than the width W2 of the flat surface 19 in a direction along the central axis O1. In this case, it is easier to brake the chips quickly. Therefore, the chips tend to curl more stably.

[0031] The width W1 of the plane 19 in the direction perpendicular to the central axis O1 and the width W2 of the plane 19 in the direction along the central axis O1 are not limited to a specific size. For example, the width W1 may be set to approximately 0.1 to 1 mm. The width W2 may be set to approximately 0.05 to 0.8 mm. Furthermore, the widths W1 and W2 may each be evaluated using their maximum values.

[0032] The first breaker projection 15 may be connected to the leading edge 13, as in the non-limiting examples shown in Figures 2 and 12. The second breaker projection 17 may be separated from the leading edge 13, as in the non-limiting examples shown in Figures 2 and 11. In these cases, excessive breaking of chips immediately after they are generated by the leading edge 13 is likely to be avoided.

[0033] 9 , in a cross section perpendicular to the central axis O1 and passing through the first breaker projection 15 and the second breaker projection 17, the second breaker projection 17 may be located lower than the upper end 15a of the first breaker projection 15. In this case, it is easy to prevent the second breaker projection 17 from protruding excessively. Therefore, the role of the first breaker projection 15 can be easily ensured.

[0034] The pair of first breaker protrusions 15 may be connected to each other on the side of the main body 3, as in the non-limiting examples shown in Figures 2 and 4. The first breaker protrusions 15 may also have a convex curved shape. Note that the convex curved shape may be a roughly convex curved shape, and does not necessarily have to be a convex curved shape in the strict sense.

[0035] 2 and 10, the upper surface 11 may further have a rake face 21. The rake face 21 may be located along the tip cutting edge 13. The rake face 21 may also be inclined downward as it moves away from the tip cutting edge 13. The rake face 21 can function as a portion through which chips flow during cutting.

[0036] 2 and 11, the second breaker protrusion 17 may be located on the rake face 21. In this case, chips flowing along the rake face 21 tend to advance onto the second breaker protrusion 17. This makes it easier for the chips to come into contact with the flat surface 19, allowing the flat surface 19 to stably perform its function.

[0037] 4, the second breaker protrusion 17 may be located closer to the tip face 9 than the center 15b of the first breaker protrusion 15 in the direction along the central axis O1. In this case, the chips can be brought into contact with the second breaker protrusion 17 at a relatively early timing in the flow of chips generated by the tip cutting edge 13. In other words, it is easy to avoid a situation where the timing to brake the flow of chips on the flat surface 19 is too late. Therefore, the flow of chips can be easily controlled.

[0038] As a non-limiting example shown in Figure 4, when the upper surface 11 is viewed from the front, the end of the plane 19 on the tip surface 9 side and the tip cutting edge 13 may each be linear, and the end of the plane 19 may be parallel to the tip cutting edge 13. In these cases, chips tend to advance in a direction perpendicular to the tip cutting edge 13. Therefore, chips tend to curl stably. Note that "parallel" does not necessarily mean strictly parallel, and may mean that an inclination of about ±5° is permitted.

[0039] As a non-limiting example shown in Figure 4, when the upper surface 11 is viewed from the front, the width W1 of the plane 19 in the direction perpendicular to the central axis O1 may increase toward the tip cutting edge 13. In this case, it is easier to brake the chips quickly, which makes it easier for the chips to curl more stably.

[0040] The insert 1 is not limited to a specific size. For example, the length of the insert 1 in the direction along the central axis O1 may be set to approximately 10 to 40 mm. Furthermore, the width of the insert 1 in the direction perpendicular to the central axis O1 when viewed from above may be set to approximately 2 to 12 mm. The height of the insert 1 in the direction perpendicular to the central axis O1 when viewed from the tip may be set to approximately 2 to 10 mm.

[0041] Examples of the material of the insert 1 include cemented carbide and cermet. Examples of the cemented carbide composition 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.

[0042] The cermet may be a sintered composite material in which a ceramic component is combined with a metal. An example of the cermet is a titanium compound mainly composed of titanium carbide (TiC) or titanium nitride (TiN). It goes without saying that the material of the insert 1 is not limited to the above composition.

[0043] The surface of the insert 1 may be coated with a coating using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and the composition of the coating may include, for example, titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0044] <Cutting Tool> Next, a non-limiting one-sided cutting tool 101 of the present disclosure will be described with reference to the drawings.

[0045] The cutting tool 101 may have a holder 103 and an insert 1, as in a non-limiting example shown in Fig. 13. When the cutting tool 101 has the insert 1, the insert 1 has excellent versatility for cutting conditions and types of workpiece materials, and therefore, it is possible to exhibit high cutting performance.

[0046] The holder 103 may extend from the first end 103a toward the second end 103b. The extending direction of the holder 103 may coincide with the extending direction of the central axis O1 of the insert 1. The holder 103 may also be rod-shaped extending from the first end 103a toward the second end 103b. The holder 103 may also be shaped like a prism. The holder 103 may also be shaped like a square prism.

[0047] The holder 103 may have a pocket 105. The pocket 105 may be located on the side of the first end 103a. The insert 1 can be attached to the pocket 105.

[0048] The holder 103 may have an upper jaw 107 and a lower jaw 109 located on the side of the first end 103 a and spaced apart from each other, and the upper jaw 107 and the lower jaw 109 may form a pocket 105 .

[0049] The insert 1 may be located within the pocket 105. If the holder 103 has an upper jaw 107 and a lower jaw 109, the insert 1 may be sandwiched between the upper jaw 107 and the lower jaw 109.

[0050] The insert 1 may be positioned in the pocket 105 so that at least a part of the portion used as a cutting edge protrudes outward from the side of the first end 103 a of the holder 103. For example, the insert 1 may be positioned in the pocket 105 so that the cutting edge 13 protrudes outward from the side of the first end 103 a of the holder 103.

[0051] The insert 1 may be attached to the pocket 105 by a screw 111. For example, the insert 1 may be attached to the pocket 105 by inserting the screw 111 into the screw holes of the upper jaw 107 and the lower jaw 109 and fastening the screw 111 to the screw holes.

[0052] Examples of materials for the holder 103 include steel and cast iron. When the material for the holder 103 is steel, the holder 103 has high toughness.

[0053] <Method for Manufacturing Machined Product> Next, a non-limiting method for manufacturing the machined product 201 having one surface according to the present disclosure will be described with reference to the drawings.

[0054] The machined product 201 may be produced by cutting a workpiece 203. A manufacturing method for the machined product 201 may include the following steps: (1) a step of rotating the workpiece 203; (2) a step of bringing the cutting tool 101, which is typified by the non-limiting embodiment described above, into contact with the rotating workpiece 203; and (3) a step of separating the cutting tool 101 from the workpiece 203.

[0055] Specifically, first, as in a non-limiting example shown in Fig. 14 , the workpiece 203 may be rotated around the axis O2, and the cutting tool 101 may be brought relatively close to the workpiece 203. Next, as in a non-limiting example shown in Fig. 15 , the cutting edge 13 of the cutting tool 101 may be brought into contact with the workpiece 203 to cut the workpiece 203. Then, as in a non-limiting example shown in Fig. 16 , the cutting tool 101 may be moved relatively away from the workpiece 203.

[0056] By going through the above process, the cutting tool 101 has an insert 1 that is highly versatile for cutting conditions and the material type of the workpiece 203, making it possible to obtain a machined product 201 with a highly accurate finished surface.

[0057] In the non-limiting example shown in FIGS. 14 to 16, the workpiece 203 is fixed and the cutting tool 101 is moved in each step, but the present invention is not limited to this configuration.

[0058] For example, in step (1), the workpiece 203 may be brought closer to the cutting tool 101. Also, in step (3), the workpiece 203 may be moved away from the cutting tool 101. When continuing the cutting process, the workpiece 203 may be kept rotating, and the step of bringing the cutting tool 101 into contact with different locations of the workpiece 203 may be repeated.

[0059] Examples of the material of the workpiece 203 include titanium alloys, aluminum, carbon steel (high carbon steel and low carbon steel), alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0060] The above provides examples of the non-limiting one-sided cutting insert 1, cutting tool 101, and method for manufacturing the machined product 201 of the present disclosure, but it goes without saying that the present disclosure is not limited to the above embodiments and can be any as long as it does not deviate from the gist of the present disclosure.

[0061] For example, the cutting insert 1, the cutting tool 101, and the manufacturing method of the machined product 201 may be configured as follows. [1] The cutting insert is rod-shaped extending along a central axis from a tip end to a rear end, and has a main body portion and a cutting portion located closer to the tip end than the main body portion, the cutting portion having a tip surface located closer to the tip end, an upper surface extending from the tip surface toward the main body portion, and a tip cutting edge located at an intersection of the tip surface and the upper surface, the upper surface having a pair of first breaker protrusions each extending from the main body portion side toward the tip surface, and a second breaker protrusion located between the pair of first breaker protrusions, the second breaker protrusion having a flat surface that slopes upward toward the main body portion. [2] In the cutting insert of the above item [1], the second breaker protrusion may be connected to the first breaker protrusion. [3] In the cutting insert of [1] or [2] above, the upper surface may have a plurality of the second breaker protrusions, and when the upper surface is viewed from the front, the plurality of second breaker protrusions may be spaced apart from one another via the central axis. [4] In the cutting insert of [3] above, when the upper surface is viewed from the front, the plurality of second breaker protrusions may be positioned side by side in a direction along the leading edge. [5] In the cutting insert of any one of [1] to [4] above, when the upper surface is viewed from the front, the width of the plane in a direction perpendicular to the central axis may be larger than the width of the plane in a direction along the central axis. [6] In the cutting insert of any one of [1] to [5] above, the first breaker protrusion may be connected to the leading edge, and the second breaker protrusion may be spaced apart from the leading edge. [7] In the cutting insert of any one of [1] to [6] above, the second breaker protrusion may be located lower than an upper end of the first breaker protrusion in a cross section perpendicular to the central axis and passing through the first breaker protrusion and the second breaker protrusion. [8] A cutting tool may have a holder extending from a first end to a second end and having a pocket located on the side of the first end, and the cutting insert of any one of [1] to [7] above located in the pocket.[9] A method for manufacturing a machined product can include the steps of rotating a workpiece, bringing the cutting tool described above in [8] into contact with the rotating workpiece, and removing the cutting tool from the workpiece.

[0062] DESCRIPTION OF SYMBOLS 1...Cutting insert (insert) 1a...Tip 1b...Rear end 3...Main body 5...Cutting portion (first cutting portion) 7...Cutting portion (second cutting portion) 9...Tip surface 11...Upper surface 13...Tip cutting edge 15...First breaker protrusion 15a...Upper end 15b...Center 17...Second breaker protrusion 19...Flat surface 21...Rake face 101...Cutting tool 103...Holder 103a...First end 103b...Second end 105...Pocket 107...Upper jaw 109...Lower jaw 111...Thread 201...Cutting workpiece 203...Workpiece O1...Central axis O2...Axis

Claims

1. A cutting insert having a rod shape extending along a central axis from a tip to a rear end, and having a main body portion and a cutting portion located on the tip side of the body portion, wherein the cutting portion has a tip surface located on the tip side, an upper surface extending from the tip surface toward the body portion, and a tip blade located at the intersection of the tip surface and the upper surface, wherein the upper surface has a pair of first breaker projections each extending from the body portion side toward the tip surface, and a second breaker projection located between the pair of first breaker projections, and the second breaker projection has a flat surface that is inclined upward as it approaches the body portion.

2. The cutting insert according to claim 1, wherein the second breaker protrusion is connected to the first breaker protrusion.

3. A cutting insert as described in claim 1 or 2, wherein the upper surface has a plurality of the second breaker protrusions, and when the upper surface is viewed from the front, the plurality of second breaker protrusions are spaced apart from each other via the central axis.

4. The cutting insert according to claim 3, wherein, when the upper surface is viewed from the front, the plurality of second breaker projections are positioned side by side in a direction along the tip edge.

5. A cutting insert according to any one of claims 1 to 4, wherein, when the top surface is viewed from the front, the width of the plane in a direction perpendicular to the central axis is greater than the width of the plane in a direction along the central axis.

6. A cutting insert according to any one of claims 1 to 5, wherein the first breaker projection is connected to the leading edge, and the second breaker projection is spaced from the leading edge.

7. A cutting insert according to any one of claims 1 to 6, wherein in a cross section perpendicular to the central axis and passing through the first breaker projection and the second breaker projection, the second breaker projection is located lower than an upper end of the first breaker projection.

8. A cutting tool comprising: a holder extending from a first end toward a second end and having a pocket located on the side of the first end; and a cutting insert according to any one of claims 1 to 7 located in the pocket.

9. A method for manufacturing a machined product, comprising the steps of: rotating a workpiece; bringing the cutting tool according to claim 8 into contact with the rotating workpiece; and removing the cutting tool from the workpiece.

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