Manufacturing method for cutting tools and cut workpieces

Abstract

There is a need for a cutting tool that has a configuration in which chips can be easily removed during insert replacement work. A cutting tool based on one aspect of the present disclosure has: a holder that has a pocket; an insert that is attached to the holder; and a fixing screw that fixes the insert to the holder. The fixing screw has a shaft and a head. The head has a hexalobular hole and a slit that extends from one lobe of the hexalobular hole to the outer edge of the head.

Description

[[Technical Field]]

[0001] The present disclosure relates to a cutting tool and a method for manufacturing a cut workpiece. Examples of the cutting tool include rotary tools and turning tools. Examples of rotary tools include milling cutters. Milling cutters can be used for milling processes such as face milling and end milling. Examples of turning tools include external diameter machining tools, internal diameter machining tools, grooving tools, and cut-off tools. [[Background Art]]

[0002] In a cutting tool having a configuration in which an insert is attached to a holder by a fixing screw, insert replacement work is performed when the insert is worn. In such insert replacement work, it is necessary to remove chips that have entered the screwdriver hole provided in the head of the fixing screw. As a process for removing such chips, the insert replacement method described in Patent Document 1 is known. In Patent Document 1, chips are removed by blowing air into the above-described screwdriver hole. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2021-154434 [[Summary of the Invention]]

[0004] A cutting tool according to one aspect of the present disclosure includes a holder having a pocket, an insert attached to the holder, and a fixing screw that fixes the insert to the holder. The fixing screw has a shaft portion and a head portion, and the head portion has a hexalobular hole and a slit extending from a corner of the hexalobular hole to an outer edge of the head portion. [[Brief Description of the Drawings]]

[0005] [Figure 1]This is a perspective view showing a cutting tool according to an embodiment of the present disclosure. [Figure 2] This is an enlarged view of region II shown in Figure 1. [Figure 3] Figure 2 shows a cross-sectional view of the cutting tool taken along the line III-III. [Figure 4] Figure 1 is a perspective view of an insert in a cutting tool. [Figure 5] Figure 1 is a perspective view of the fixing screw in the cutting tool shown. [Figure 6] Figure 5 is a plan view of the fixing screw. [Figure 7] Figure 5 is a plan view of the first modified example of the fixing screw shown. [Figure 8] Figure 6 shows a cross-sectional view of the fixing screw taken along the line VIII-VIII. [Figure 9] This is a cross-sectional view corresponding to Figure 8 in a second modified example of the fixing screw shown in Figure 5. [Figure 10] Figure 6 is a cross-sectional view of the fixing screw taken along the line XX. [Figure 11] This is a cross-sectional view corresponding to Figure 10 in a third modified example of the fixing screw shown in Figure 5. [Figure 12] This is a schematic diagram showing one step in the manufacturing method of a machined workpiece according to an embodiment. [Figure 13] This is a schematic diagram showing one step in the manufacturing method of a machined workpiece according to an embodiment. [Figure 14] This is a schematic diagram showing one step in the manufacturing method of a machined workpiece according to an embodiment. [Modes for carrying out the invention]

[0006] The shape of the screw hole for fixing screws in cutting tools is generally a hexalobular hole (a hole shaped like a hexagonal star). Therefore, chips tend to accumulate at the six corners of the hexalobular hole, and even blowing air may not be sufficient to remove them. For this reason, there is a need for cutting tools with a design that facilitates chip removal during insert replacement.

[0007] The cutting tool 1 and the method for manufacturing the cut workpiece according to the embodiments of this disclosure will be described in detail below with reference to the drawings. However, for the sake of convenience of explanation, the drawings referenced below show only the components necessary for describing the embodiments in a simplified manner. Therefore, the cutting tool 1 according to the embodiments of this disclosure may include any components not shown in the drawings referenced. Furthermore, the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component.

[0008] <Cutting tools> As shown in Figure 1, an example of a cutting tool 1 according to this disclosure is a rotary tool used for milling. In addition to rotary tools, other examples of cutting tools 1 include tools used for turning operations such as outer diameter machining, inner diameter machining, and grooving.

[0009] The cutting tool 1 may include a holder 3, an insert 5, and a fixing screw 7. The holder 3 is columnar in shape, extending from a first end 3a to a second end 3b along the rotation axis O1. In Figure 1 and other figures, the direction of rotation around the rotation axis O1 is indicated by Y1. If the cutting tool 1 is a tool used for turning as described above, the rotation axis O1 may be replaced with the central axis.

[0010] The cutting tool 1 may have pockets 9 located on the side of the first end 3a. There may be only one pocket 9, or there may be multiple pockets 9, as shown in the example in Figure 1. As shown in the example in Figure 1, the multiple pockets 9 may each open to the outer circumferential surface of the holder 3 and to the end face on the side of the first end 3a. When the cutting tool 1 is viewed from the front from the side of the first end 3a, the multiple pockets 9 may be arranged at equal intervals or at unequal intervals.

[0011] Pocket 9 is a space for positioning the insert 5 and the fixing screw 7. Pocket 9 may also be used as a space for chips generated during the cutting process to produce the workpiece to flow.

[0012] As the holder 3, steel, cast iron and the like can be used. For example, from the viewpoint of enhancing the toughness of the holder 3, steel may be used among these materials.

[0013] The insert 5 is located in the pocket 9 and attached to the holder 3. The insert 5 according to an example shown in Fig. 4 has a polygonal plate shape and includes an upper surface 11, a lower surface 13, a side surface 15, and a through hole 17.

[0014] The upper surface 11 of the insert 5 has a polygonal shape, and when the insert 1 is attached to the holder 3 as in the example shown in Fig. 1, the upper surface 11 may be positioned relatively forward in the rotation direction Y1 of the insert 5. As in the example shown in Fig. 4, the upper surface 11 may have a 180° rotationally symmetric shape centered on the center of the upper surface 11. The center of the upper surface 11 can be specified, for example, by the intersection of diagonal lines of the upper surface 11. The lower surface 13 may be positioned on the opposite side of the upper surface 11, and when the insert 1 is attached to the holder 3 as in the example shown in Fig. 1, the lower surface 13 may be positioned relatively rearward in the rotation direction Y1 of the insert 5.

[0015] The side surface 15 of the insert 5 may be positioned between the upper surface 11 and the lower surface 13. The side surface 15 may be connected to the upper surface 11 and the lower surface 13 respectively. In the example shown in Fig. 4, since the upper surface 11 has a polygonal shape, the side surface 15 includes a flat surface region positioned along the sides of the upper surface 11 and a convex surface region positioned along the corners of the upper surface 11.

[0016] The insert 5 according to the example shown in Fig. 4 has a generally square plate shape, and the upper surface 11 and the lower surface 13 are each quadrilateral. When the upper surface 11 and the lower surface 13 have the above configuration, the side surface 15 includes four flat surface regions and four convex surface regions. The shape of the insert 5 is not limited to the above configuration. For example, the upper surface 11 is not limited to a quadrilateral, and may be generally triangular, generally pentagonal, generally hexagonal, or the like, for example.

[0017] The through hole 17 in the insert 5 extends from the upper surface 11 to the lower surface 13 and opens at the center of the upper surface 11 and the center of the lower surface 13 respectively. The through hole 17 is a portion for inserting (passing through) the fixing screw 7. The insert 5 is fixed to the holder 3 by fixing the fixing screw 7 inserted into the through hole 17 to the pocket 9.

[0018] The through hole 17 includes a central portion 17a, a first conical portion 17b, and a second conical portion 17c. The central portion 17a is located at the center in the thickness direction of the insert 5 (the direction from the upper surface 11 toward the lower surface 13) and has a constant inner diameter. The first conical portion 17b is located from the central portion 17a toward the upper surface 11, and forms a truncated cone shape whose inner diameter increases as the distance from the central portion 17a increases. The second conical portion 17c is located from the central portion 17a toward the lower surface 13, and forms a truncated cone shape whose inner diameter increases as the distance from the central portion 17a increases.

[0019] As in the example shown in FIGS. 2 and 3, the pocket 9 in the holder 3 includes a restraining seating surface 19 against which the lower surface 13 of the insert 5 abuts, and a restraining side surface 21 against which the side surface 15 of the insert 5 abuts. For example, the restraining seating surface 19 may have a square shape corresponding to the lower surface 13, and the restraining side surface 21 may be constituted by two flat surface regions corresponding to two flat surface regions on the side surface 15. Further, as in the example shown in FIG. 3, the restraining seating surface 19 may be provided with a screw hole 23 to which the fixing screw 7 is screwed and fixed. The screw hole 23 includes the central axis of the through hole 17 in the insert 5 and extends in the direction along the central axis.

[0020] As in the example shown in FIG. 4, the insert 5 has an upper cutting edge 25 located at the intersection of the upper surface 11 and the side surface 15. The upper cutting edge 25 may be located over the entire intersection of the upper surface 11 and the side surface 15, or may be located only on a part of the intersection. Further, in addition to the upper cutting edge 25, the insert 5 may have a lower cutting edge 27 located at the intersection of the lower surface 13 and the side surface 15. The lower cutting edge 27 may be located over the entire intersection of the lower surface 13 and the side surface 15, or may be located only on a part of the intersection.

[0021] In a single cutting operation, either the upper cutting edge 25 or the lower cutting edge 27 is used. For example, when the lower surface 13 of the insert 5 is in contact with the restraining seat surface 19 (see Figure 3) of the pocket 9, the upper cutting edge 25 is used for cutting. If the upper cutting edge 25 wears beyond a predetermined amount, the insert 5 may be removed from the pocket 9, inverted (front and back), and then reinserted into the pocket 9. In this case, the upper surface 11 of the insert 5 will be in contact with the restraining seat surface 19 of the pocket 9, and the lower cutting edge 27 can be used for cutting.

[0022] The fixing screw 7 is a component for fixing the insert 5 to the holder 3. The fixing screw 7 is inserted into the through hole 17 of the insert 5 and is screwed into the screw hole 23 (see Figure 3) formed in the restraining seat surface 19 of the pocket 9 in the holder 3.

[0023] <Fixing screws> As shown in the example in Figure 5, the fixing screw 7 has a head 29 and a shaft 31. The shaft 31 is a rod-shaped part located at the tip of the fixing screw 7, and a screw groove 33 is formed on its outer circumference. The head 29 is the part located at the rear end of the fixing screw 7 and has a larger outer diameter than the shaft 31. The head 29 can be, for example, a countersunk head or a round head. The surface of the head 29 that is on the shaft 31 side and contacts the insert 5 is the seating surface 43. That is, the insert 5 is sandwiched between the seating surface 43 of the fixing screw 7 and the restraining seating surface 19 of the pocket 9 (see Figure 3).

[0024] A screw groove 33 is formed at least on the tip side of the shaft portion 31. The insert 5 is sandwiched between the head 29 of the fixing screw 7 and the restraining seat surface 19 of the pocket 9, and the screw groove 33 of the fixing screw 7 is screwed into the screw groove (not shown) of the screw hole 23, thereby fixing the insert 5 to the holder 3 (see Figure 3).

[0025] A hole for a screwdriver is formed on the rear end face of the head 29. Specifically, a hexalobular hole 35 (a hexagonal star-shaped hole) is formed as the hole for a screwdriver. By inserting a hexalobular-shaped tool into this hexalobular hole 35 and rotating the tool, the fixing screw 7 can be attached and detached.

[0026] As shown in the example in Figure 5, the head 29 of the fixing screw 7 has a hexalobular hole 35, as well as a slit 37 extending from a corner of the hexalobular hole 35 to the outer edge of the head 29. The corners of the hexalobular hole 35 are the protruding corners of a star shape, and in the case of a hexagonal star shape, there are six corners. The slit 37 may extend from multiple corners of the hexalobular hole 35, or, as shown in the example in Figure 5, it may extend from one of the corners of the hexalobular hole 35.

[0027] When cutting is performed using cutting tool 1, some of the chips generated during cutting may enter the hexalobular hole 35. Therefore, when attaching or detaching the fixing screw 7 using a hexalobular-shaped tool, it is necessary to remove any chips that have entered the hexalobular hole 35 beforehand. However, compared to common hex sockets (hexagonal sockets) used for screwdrivers, it is more difficult to remove chips that have entered the hexalobular hole 35.

[0028] However, if the head 29 of the fixing screw 7 has the slit 37 described above, the chips that have entered the hexalobular hole 35 can be discharged to the outside through this slit 37. Therefore, even when the head 29 of the fixing screw 7 has the hexalobular hole 35, the chips that have entered the hexalobular hole 35 can be reliably removed.

[0029] When the slits 37 extend from multiple corners of the hexalobular hole 35, chips that have entered the hexalobular hole 35 can be efficiently removed. Also, when the slits 37 extend from one of the corners of the hexalobular hole 35, the reduction in strength of the head 29 of the fixing screw 7 caused by the formation of the slits 37 can be easily suppressed.

[0030] As shown in one example in Figure 6, the slit 37 may have a bottom surface 39 and a pair of inner wall surfaces 41, or, as shown in one example in Figures 10 and 11, the slit 37 may further have a concave curved surface 37e connecting the bottom surface 39 and the pair of inner wall surfaces 41.

[0031] When the rear end face of the head 29 of the fixing screw 7 is viewed from the front, the width W of the slit 37 may be constant from the part connected to the hexalobular hole 35 to the outer edge of the head 29, as in the example shown in Figure 6, or the slit 37 may have a portion 37a where the width W increases as it moves away from the hexalobular hole 35, as in the example shown in Figure 7. When the slit 37 has a portion 37a where the width W increases as it moves away from the hexalobular hole 35, chips are less likely to clog the slit 37. Therefore, the chip discharge performance is improved.

[0032] The portion 37a where the width W increases, as described above, may be located only in a part of the slit 37, as shown in Figure 6, or it may be located throughout the entire slit 37, that is, from the end connected to the hexalobular hole 35 in the slit 37 to the end located on the outer edge of the head 29. For example, as shown in Figure 7, the portion 37a where the width W increases may be located away from the end 37d connected to the hexalobular hole 35 in the slit 37.

[0033] In this case, the thickness of the head 29 near the hexalobular hole 35 is easily ensured. As a result, the hexalobular hole 35 is less likely to deform, and the fixing screw 7 can be stably attached and detached using a hexalobular-shaped tool. Also, if the portion 37a, which widens in width W as it moves away from the hexalobular hole 35, reaches the outer edge of the head 29, the chip exit in the slit 37 becomes wider, making it easier to discharge the chips inside the slit 37 to the outside of the slit 37.

[0034] The width W of the slit 37 in the above description refers to the width W of the slit 37 in a direction perpendicular to the direction in which the slit 37 extends, when the rear end face of the head 29 of the fixing screw 7 is viewed from the front. If the slit 37 has a pair of inner wall surfaces 41, the width W of the slit 37 may be evaluated by the distance between these pair of inner wall surfaces 41.

[0035] As shown in the example in Figure 8, the slit 37 may have a portion 37b where the depth D becomes shallower as it moves away from the hexalobular hole 35. Here, a virtual plane S is set that is perpendicular to the central axis O2 of the fixing screw 7 and is in contact with the rear end face of the head 29 of the fixing screw 7. The length from this virtual plane S to the bottom (bottom surface 39) of the fixing screw 7 in the direction along the central axis O2 of the fixing screw 7 is defined as the depth D of the slit 37.

[0036] This configuration improves the removal of chips from the outside. This is because the slit 37 has a portion 37b where the depth D is shallower, making it easier for the chips to move upward.

[0037] The portion 37b where the depth D is shallower may be located only in a part of the slit 37, or it may be located throughout the entire slit 37, that is, from the end of the slit 37 connected to the hexalobular hole 35 to the end located on the outer edge of the head 29. In this case, for example, as shown in the example in Figure 8, the portion 37b where the depth D is shallower may be located away from the end 37d of the slit 37 connected to the hexalobular hole 35.

[0038] In this case, the flow of chips from the hexalobular hole 35 to the slit 37 is smooth. Therefore, the slit 37 is less likely to become clogged with chips. When the portion 37b where the depth D becomes shallower reaches the outer edge of the head 29, the chips can be directed upward at the chip exit in the slit 37. Therefore, the flow of chips into the slit 37 is made even smoother, making it easier to discharge the chips inside the slit 37 to the outside of the slit 37.

[0039] Furthermore, as shown in the example in Figure 9, the depth D of the slit 37 may be constant, that is, the bottom (bottom surface 39) of the fixing screw 7 may be located on the same plane as the bottom surface 39 of the hexalobular hole 35.

[0040] When the slit 37 has a bottom surface 39 and a pair of inner wall surfaces 41, the pair of inner wall surfaces 41 may have a constant spacing H as they move away from the bottom surface 39, as shown in the example in Figure 10, or they may have portions where the spacing H widens as they move away from the bottom surface 39. That is, as shown in the example in Figure 11, the width of the slit 37 is not constant in the direction along the central axis O2 of the fixing screw 7, and there may be portions 37c where the width of the slit 37 increases as it approaches the virtual plane S described above.

[0041] In this case, the flow of chips from the slit 37 to the upper surface of the head 29 is smooth. Therefore, the slit 37 is less likely to become clogged with chips. When the portion 37c of the slit 37 where the width is increased reaches the upper surface of the head 29, the chip exit in the slit 37 becomes wider, making it easier to discharge the chips inside the slit 37 to the outside of the slit 37.

[0042] The seating surface 43 on the head 29 may be a plane perpendicular to the central axis O2 of the fixing screw 7, or it may be a tapered shape that moves away from the central axis O2 of the fixing screw 7 as it moves away from the shaft portion 31, as in the example shown in Figure 5. The slit 37 may open on such a seating surface 43 (see Figures 8 and 9).

[0043] In the example shown in Figure 3, the through hole 17 of the insert 5 has a central portion 17a, a first conical portion (frustoconical portion) 17b, and a second conical portion (frustoconical portion) 17c. The seating surface 43 of the head 29 is in contact with the first conical portion 17b. In this case, the chips that pass through the slit 37 come into contact with the first conical portion 17b. At this time, since the first conical portion 17b has a frustoconical shape in which the inner diameter increases as it moves away from the central portion 17a, the chips tend to move upward along the first conical portion 17b. That is, the chips are easily discharged to the outside, so that chips that have entered the hexalobular hole 35 can be stably removed.

[0044] The size of the insert 5 is not particularly limited. For example, the maximum width of the top surface 11 may be set to approximately 3 to 20 mm. Also, the height from the top surface 11 to the bottom surface 13 may be set to approximately 5 to 20 mm.

[0045] Examples of materials for insert 5 include cemented carbide or cermet. Examples of cemented carbide compositions include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. Here, WC, TiC, and TaC are hard particles, and Co is the binding phase.

[0046] Furthermore, cermets are sintered composite materials formed by combining a metal with a ceramic component. An example of a cermet is a titanium compound primarily composed of titanium carbide (TiC) or titanium nitride (TiN). However, it goes without saying that the material of insert 5 is not limited to the above compositions.

[0047] The surface of insert 5 may be coated with a film using chemical vapor deposition (CVD) or physical vapor deposition (PVD). Examples of film compositions include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0048] <Method for manufacturing machined parts> Next, a method for manufacturing a one-sided machined workpiece, not limited to the present disclosure, will be described with reference to Figures 12 to 14. Figures 12 to 14 show a method for manufacturing a machined workpiece when machining is performed using the cutting tool 1 described above. In Figures 12 to 14, the rotation axis O1 of the cutting tool 1 is shown by a dashed line. The machined workpiece 103 is produced by machining the workpiece 101.

[0049] A method for manufacturing a machined workpiece may include the following steps: (1) A step of rotating the cutting tool 1 as represented by the above embodiment, (2) The step of bringing the rotating cutting tool 1 into contact with the workpiece 101, (3) A step of separating the cutting tool 1 from the workpiece 101, It may be provided.

[0050] Specifically, first, as shown in Figure 12, the cutting tool 1 may be brought relatively closer to the workpiece 101 while rotating it in the Y1 direction around the rotation axis O1. Next, as shown in Figure 13, the cutting edge of the cutting tool 1 may be brought into contact with the workpiece 101 to cut the workpiece 101. Then, as shown in Figure 14, the cutting tool 1 may be moved relatively further away from the workpiece 101.

[0051] The workpiece 101 may be fixed while the cutting tool 1 is brought close to it. Alternatively, as shown in the example in Figures 12 to 14, the workpiece 101 may be fixed while the cutting tool 1 is rotated around the rotation axis O1. Alternatively, as shown in the example in Figure 14, the workpiece 101 may be fixed while the cutting tool 1 is moved away from it. In the example shown in Figures 12 to 14, the workpiece 101 is fixed while the cutting tool 1 is moved in each step, but of course, the configuration is not limited to these examples.

[0052] For example, in step (1), the workpiece 101 may be brought closer to the cutting tool 1. Alternatively, in step (3), the workpiece 101 may be moved away from the cutting tool 1. To continue the cutting process, the cutting tool 1 can be kept rotating, and the process of bringing the cutting edge of the insert 5 into contact with different parts of the workpiece 101 can be repeated.

[0053] Typical examples of materials for the workpiece 101 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0054] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. [Explanation of Symbols]

[0055] 1 cutting tools 3 holders 5 Inserts (Cutting Inserts) 7 Fixing screws 9 pockets 11 Top side 13 Bottom side 15 Side view 17 Through hole 17a central part 17b First conical section (frustum of a cone) 17c Second conical section (frustum-shaped section) 29 Head 31 Shaft 35 Hexalobular holes 37 Slits 39 Bottom 41 Interior wall surface 43 Seat 101 Work material 103 Cutting workpiece

Claims

1. A holder with a pocket, The insert attached to the holder, The insert has a fixing screw for fixing it to the holder, The aforementioned fixing screw has a shaft portion and a head portion, The aforementioned head is Hexalobular hole and A cutting tool having a slit extending from the corner of the hexalobular hole to the outer edge of the head.

2. The cutting tool according to claim 1, wherein the slit has a portion that widens as it moves away from the hexalobular hole.

3. The cutting tool according to claim 1, wherein the slit has a portion that becomes shallower as it moves away from the hexalobular hole.

4. The slit has a bottom surface and a pair of inner wall surfaces connected to the bottom surface, The cutting tool according to claim 1, wherein the pair of inner wall surfaces have portions where the spacing between them increases as they move away from the bottom surface.

5. The head has a seating surface that contacts the insert, The seating surface has a tapered shape that moves away from the central axis of the fixing screw as it moves away from the shaft portion, The cutting tool according to claim 1, wherein the slit is open in the seating surface.

6. The insert has a top surface, a bottom surface, a side surface, and through holes opening in the top and bottom surfaces through which the fixing screws are inserted. The cutting tool according to claim 5, wherein the through hole has a central portion located in the center in the direction from the upper surface to the lower surface and having a constant inner diameter, and a frustoconical portion located from the central portion toward the upper surface and having an inner diameter that increases as it moves away from the central portion.

7. A step of rotating a cutting tool according to any one of claims 1 to 6, A step of bringing the rotating cutting tool into contact with the workpiece, A method for manufacturing a machined workpiece, comprising the step of separating the cutting tool from the workpiece.

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