End mill

Abstract

The purpose of the present invention is to provide an end mill capable of removing cutting marks generated by over-cutting and finishing a machined surface into a satisfactorily glossy surface, even when over-cutting occurs due to a structural cutting edge, entrainment of scattered cutting chips, and the like. The end mill is provided with a linear end cutting edge (1) at the tool tip, a pressing sliding contact surface (2) is continuously arranged on the rear side of the end cutting edge (1) in the tool rotation direction, the pressing sliding contact surface (2) is in sliding contact with a cutting surface cut by the end cutting edge (1) in a pressed state, and the pressing sliding contact surface (2) is configured in a state that the tool tip faces upwards. And an inclined plane that is inclined upward at a predetermined inclination angle (alpha) from the end cutting edge (1) side toward the rear side in the direction of rotation of the tool, and the inclination angle (alpha) is set so as to exceed 0 DEG and not more than 4 DEG with respect to a plane (S) perpendicular to the axis of rotation (C) of the tool.

Description

Technical Field

[0001] This invention relates to end mills such as radius end mills and square end mills, which have a straight bottom cutting edge at the front end of the tool. Background Technology

[0002] This type of end mill can perform planar machining based on the bottom edge, so it can be used for various machining processes such as roughing, semi-finishing, and final finishing. However, even when used for final finishing, previous end mills sometimes formed cutting marks (tool marks) on the cutting surface.

[0003] The applicant conducted research on the above-mentioned reasons and concluded that one of the reasons was overcutting caused by the structural cutting edge. Therefore, in order to suppress the formation of the structural cutting edge, the applicant proposed the end mill shown in Patent Document 1 (hereinafter referred to as "conventional example"). Here, the structural cutting edge refers to the part that functions as a cutting edge in which cutting powder (cutting chips) fuses to the cutting edge during cutting and becomes a new cutting edge.

[0004] In this conventional example, a plurality of chip discharge grooves are provided on the outer periphery of the front end of the tool body, extending from the tool tip toward the tool base end. A bottom cutting edge is integrally provided with the tool body at the intersection of the rake face of the chip discharge groove and the front rear cutting face of the tool body. At least one of the bottom cutting edges is formed with a convex edge protruding toward the front end of the tool axis. The convex edge is formed by continuously arranging a plurality of generally straight edges. The bottom cutting edge with the convex edge is set to a predetermined rake angle, thereby suppressing the formation of the structural cutting edge.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-16468 Summary of the Invention

[0006] However, as mentioned above, although the previous examples suppressed the formation of the structural cutting edge, they could not completely suppress it. Depending on the type of material being cut (e.g., a soft material with low hardness), a structural cutting edge may sometimes be generated, resulting in a cutting mark.

[0007] Furthermore, it is ineffective against cutting marks not caused by the cutting edge of the structure, such as those caused by the entrapment of flying cutting chips.

[0008] Therefore, even when using the previous example, there are cases where cutting marks remain on the machined surface, preventing a good gloss finish. In such cases, grinding is required in subsequent processes, which adds to the processing time.

[0009] Therefore, the applicant studied new countermeasures and believed that even if the formation of the structural cutting edge is not suppressed, a good glossy surface can be obtained by removing the cutting marks generated therefrom. After in-depth research, the present invention was discovered.

[0010] In other words, the purpose of this invention is to provide an end mill that can remove cutting marks caused by overcutting, even when overcutting occurs due to the structural cutting edge, the entrapment of scattered cutting chips, etc., and finish the machined surface with a good gloss.

[0011] The main points of the invention will be described with reference to the accompanying drawings.

[0012] An end mill has a straight bottom cutting edge 1 at its front end. The end mill is characterized by a continuously provided pressing and sliding contact surface 2 on the rear side of the bottom cutting edge 1 in the tool rotation direction. This pressing and sliding contact surface 2 slides in contact with the cutting surface being cut by the bottom cutting edge 1 in a pressing state. The pressing and sliding contact surface 2 is configured as an inclined plane that, when the tool front end is facing upwards, slopes upwards from the bottom cutting edge 1 towards the rear side in the tool rotation direction at a predetermined angle α. Furthermore, the angle α is set to be greater than 0° and less than 4° relative to a surface S perpendicular to the tool rotation axis C.

[0013] In addition, in the end mill described in technical solution 1, a flank face 3 is continuously provided on the rear side of the tool rotation direction of the pressing sliding contact surface 2, and the pressing sliding contact surface 2 and the edge line 4 formed at the boundary between the pressing sliding contact surface 2 and the flank face 3 are configured to slide in contact with the cutting surface in a pressing state.

[0014] Furthermore, in the end mill described in technical solution 2, the end mill is characterized in that it has a convex region 5, which includes the pressing sliding contact surface 2, the flank face 3, and the ridge line 4. The convex region 5 protrudes relative to the bottom cutting edge 1 in the direction of the tool tip, and the convex region 5 is configured such that the protrusion A relative to the bottom cutting edge 1 is greater than 0 mm and less than 0.004 mm.

[0015] In addition, in the end mill described in technical solution 1, the pressing sliding contact surface 2 has a length of more than 1% of the tool's outer diameter and is arranged from the outer peripheral base point of the bottom cutting edge 1 toward the tool's rotation axis C.

[0016] In addition, in the end mill described in technical solution 2, the pressing sliding contact surface 2 has a length of more than 1% of the tool's outer diameter and is arranged from the outer peripheral base point of the bottom cutting edge 1 toward the tool's rotation axis C.

[0017] In addition, in the end mill described in technical solution 3, the pressing sliding contact surface 2 has a length of more than 1% of the tool's outer diameter and is arranged from the outer peripheral base point of the bottom cutting edge 1 toward the tool's rotation axis C.

[0018] In addition, in any one of the end mills described in technical solutions 1 to 6, the end mill is characterized in that the end clearance angle β of the bottom cutting edge 1 is 0° or more and 1° or less.

[0019] In addition, in any one of the technical solutions 1 to 6, the end mill is characterized in that the pressing sliding contact surface 2 is formed in the shape of a strip and is set from the outer peripheral base point of the bottom cutting edge 1 to the vicinity of the tool rotation axis C.

[0020] In addition, in the end mill described in technical solution 7, the pressing sliding contact surface 2 is formed as a strip and is located from the outer peripheral base point of the bottom cutting edge 1 to the vicinity of the tool rotation axis C.

[0021] In addition, in any one of the technical solutions 1 to 6, the end mill is characterized in that the end mill is configured as a radius end mill, and the radius end mill has a corner R-edge 6 continuously formed on the outer peripheral side of the bottom cutting edge 1, and then an outer peripheral cutting edge 7 is continuously formed on the corner R-edge 6.

[0022] Furthermore, in the end mill described in technical solution 7, the end mill is characterized in that it is configured as a radius end mill, and a corner R-edge 6 is continuously formed on the outer periphery of the bottom cutting edge 1, and an outer peripheral cutting edge 7 is continuously formed on the corner R-edge 6.

[0023] Furthermore, in the end mill described in technical solution 8, the end mill is characterized in that it is configured as a radius end mill, and the radius end mill has a corner R-edge 6 continuously formed on the outer periphery of the bottom cutting edge 1, and an outer peripheral cutting edge 7 is continuously formed on the corner R-edge 6.

[0024] In addition, in the end mill described in technical solution 9, the end mill is characterized in that it is configured as a radius end mill, and the radius end mill has a corner R-edge 6 continuously formed on the outer periphery of the bottom cutting edge 1, and an outer peripheral cutting edge 7 is continuously formed on the corner R-edge 6.

[0025] By constructing it as described above, this invention can remove the cutting marks caused by over-cutting even when over-cutting occurs due to the cutting edge of the structure, the entrapment of scattered cutting chips, etc., and finish the machined surface into a good glossy surface.

[0026] Therefore, it has become a practical end mill that can eliminate the grinding process after cutting, or can shorten the processing time in the existing grinding process, reduce working hours, and increase productivity. Attached Figure Description

[0027] Figure 1 This is the top view (tool front view) of this embodiment.

[0028] Figure 2This is a front view showing the blade portion of this embodiment.

[0029] Figure 3 This is a side view showing the blade portion of this embodiment.

[0030] Figure 4 This is a reference enlarged side sectional view showing the tilt angle (α) of the pressing sliding contact surface in the convex region of this embodiment and the protrusion amount (A) of the convex region.

[0031] Figure 5 This is an explanatory diagram showing the end-edge clearance angle of the bottom edge in this embodiment.

[0032] Figure 6 This is an explanatory diagram illustrating another example of this embodiment.

[0033] Figure 7 (a) is an explanatory diagram illustrating the effects of the present invention. Figure 7 (b) is a photograph showing the surface condition of the machined surface.

[0034] Figure 8 (a) is an explanatory diagram showing the mechanism of cutting mark generation at the cutting edge of a conventional end mill. Figure 8 (b) is a photograph showing the surface condition of the machined surface.

[0035] Figure 9 This is a photograph showing the evaluation results of gloss in Experiment 2 (hardness of the material being cut: 30 HRC).

[0036] Figure 10 This is a photograph showing the evaluation results of gloss in Experiment 2 (hardness of the material being cut: 40 HRC).

[0037] Figure 11 This is a photograph showing the evaluation results of gloss in Experiment 2 (hardness of the material being cut: 50 HRC).

[0038] Figure 12 This is a photograph showing the evaluation results of gloss in Experiment 2 (hardness of the material being cut: 53 HRC).

[0039] Figure 13 This is a photograph showing the confirmation results of the surface condition based on laser microscopy in Experiment 3.

[0040] Figure 14 This is a photograph showing the evaluation results of glossiness in Experiment 4.

[0041] Label Explanation

[0042] 1: Bottom edge; 2: Pressing and sliding contact surface; 3: Back face; 4: Edge line; 5: Convex area; 6: Corner R edge; 7: Outer peripheral edge; A: Protrusion amount of the convex area; C: Tool rotation axis; S: Surface perpendicular to the tool rotation axis; α: Inclination angle of the pressing and sliding contact surface; β: End edge clearance angle of the bottom edge. Detailed Implementation

[0043] The function of the present invention is illustrated with reference to the accompanying drawings, and preferred embodiments of the present invention are described.

[0044] In this invention, the pressing sliding contact surface 2, which is continuously provided on the rear side of the tool rotation direction of the bottom edge 1, is configured as an inclined plane with an inclination angle α relative to the plane S perpendicular to the tool rotation axis C. In other words, it is configured as an inclined plane with an inclination angle α tilted upward from the bottom edge 1 side toward the rear side of the tool rotation direction when the tool tip is facing upward. It is configured to slide in contact with the cutting surface cut by the bottom edge 1 in a pressing state. Therefore, the pressing sliding contact surface 2 moves while plastically deforming the cutting surface, thereby flattening the cutting surface.

[0045] That is, in conventional end mills, when a structural cutting edge is generated, such as... Figure 8 As shown, due to the overcutting at the tip of this structure, a deeper cutting mark is left as a scratch than the cutting surface cut by the bottom edge. This scratch prevents the achievement of a glossy finish on the machined surface. However, in this invention, as... Figure 7 As shown, pressing the sliding contact surface 2 causes plastic deformation of the cutting surface cut by the bottom edge 1 while grinding it flat, thereby improving the polishing effect. Even for deep scratches caused by over-cutting due to structural edge tip, chip entrapment, etc., it can play a sufficient grinding role, remove cutting marks and finish the machined surface (cutting surface) into a good glossy surface.

[0046] Furthermore, in this invention, since the tilt angle α of the pressing sliding contact surface 2 is set to be greater than 0° and less than 4°, the cutting resistance of the pressing sliding contact surface 2 will not become too large, the tool posture during cutting is stable, and while achieving the above-mentioned effects, smooth cutting processing can also be realized.

[0047] Furthermore, in this invention, compared to the wedge angle (the angle between the rake face and the flank face) of the bottom edge in a conventional end mill without pressing the sliding contact surface 2, pressing the sliding contact surface 2 increases the angle corresponding to the wedge angle of the bottom edge 1 (the angle between the rake face 10 and the pressing sliding contact surface 2: hereinafter referred to as the "wedge angle of the bottom edge 1"), and the volume of the bottom edge tip increases, thus preventing damage to the bottom edge 1 as much as possible.

[0048]

Example

[0049] Specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0050] This embodiment applies the end mill of the present invention to a radius end mill, which has a cutting edge 8. The cutting edge 8 is composed of a bottom cutting edge 1, a corner R-cutting edge 6 continuously disposed on the outer periphery of the bottom cutting edge 1, and an outer peripheral cutting edge 7 continuously disposed with the corner R-cutting edge 6.

[0051] Specifically, this embodiment is configured such that: a pressing and sliding contact surface 2 is provided on the rear side of the bottom cutting edge 1 in the tool rotation direction. The pressing and sliding contact surface 2 is continuously provided with the bottom cutting edge 1 and slides in contact with the cutting surface (hereinafter referred to as "cutting surface of bottom cutting edge 1") cut by the bottom cutting edge 1 in a pressing state. The polishing effect brought about by the pressing and sliding contact action of the pressing and sliding contact surface 2 will remove the scratches (cutting marks) generated on the cutting surface of the bottom cutting edge 1 and obtain a glossy machined surface.

[0052] The following is a detailed description of the structure of each part of this embodiment.

[0053] This embodiment has a structure in which a blade 9 is provided at the front end of the handle (not shown) via the neck (not shown).

[0054] like Figure 1 As shown, the cutting edge 9 consists of two cutting edges 8. Each cutting edge 8 is composed of a bottom cutting edge 1 arranged in a straight line at the front end of the tool, a corner R-edge 6 continuously arranged on the outer periphery of the bottom cutting edge 1, and an outer peripheral cutting edge 7 continuously arranged with the corner R-edge 6. That is, this embodiment is a double-flute end mill with a cutting edge 9 composed of two cutting edges 8. In addition, the structure of the cutting edge 9 is not limited to the above structure. For example, it can also be composed of four or six cutting edges. Alternatively, it can be configured as a square-head end mill without the corner R-edge 6, where the cutting edge 9 is only composed of the bottom cutting edge 1 and the outer peripheral cutting edge 7.

[0055] In addition, in this embodiment, the tool outer peripheral end point of the bottom cutting edge 1 is referred to as the outer peripheral base point of the bottom cutting edge 1. For example, in a radius end mill, the boundary position between the bottom cutting edge 1 and the corner R cutting edge 6 is the outer peripheral base point of the bottom cutting edge 1, or in a square end mill, the boundary position between the bottom cutting edge 1 and the outer peripheral cutting edge 7 is the outer peripheral base point of the bottom cutting edge 1.

[0056] In addition, such as Figure 1As shown, each cutting edge 8 is formed with a rising core. Here, in this embodiment, a rising core means that each bottom edge 1 or its extension does not pass through the tool rotation axis C but is positioned in front of the tool rotation direction relative to the tool rotation axis C. Furthermore, the bottom edge 1 is not limited to the above situation; for example, it may be formed with a so-called lowered core, where the bottom edge 1 or its extension does not pass through the tool rotation axis C but is positioned behind the tool rotation axis C relative to the tool rotation axis C. Alternatively, it may be formed with the bottom edge 1 or its extension passing through the tool rotation axis C. Additionally, in the figure, the arrow labeled T indicates the tool rotation direction.

[0057] In addition, such as Figure 2 and Figure 3 As shown, each peripheral cutting edge 7 is configured as a spiral cutting edge forming a spiral shape around the tool's rotation axis C. Furthermore, the peripheral cutting edge 7 is not limited to the above structure; for example, it can also be a straight cutting edge (a straight or tapered cutting edge).

[0058] In addition, such as Figure 2 As shown, one end of each corner R-blade 6 is continuously set to the outer peripheral base point of the bottom blade 1, and the other end is continuously set to the front end of the outer peripheral blade 7, forming an approximately 1 / 4 arc shape (R shape) protruding towards the outer peripheral front end of the blade 9 (cutting blade 8).

[0059] In addition, such as Figure 1 and Figure 2 As shown, each bottom cutting edge 1 is arranged in a straight line from the continuous setting part with the corner R cutting edge 6 to the vicinity of the tool rotation axis C, and is set in a position that is parallel to each other and point-symmetrical about the tool rotation axis C.

[0060] In addition, a pressing sliding contact surface 2 is continuously provided on the rear side of each bottom cutting edge 1 in the tool rotation direction. The pressing sliding contact surface 2 slides in contact with the cutting surface of the bottom cutting edge 1 in a pressing state.

[0061] Specifically, such as Figure 4 As shown, the pressing sliding contact surface 2 is configured as an inclined surface that tilts upward at an angle α from the bottom edge 1 side toward the rear side (back edge 3 side) of the tool rotation direction when the tool tip is facing upward.

[0062] In detail, the pressing sliding contact surface 2 is formed into a strip of approximately the same width, such as... Figure 4As shown, an inclined plane with a predetermined inclination angle α relative to the surface S perpendicular to the tool's rotation axis C is provided along approximately the entire length of the bottom cutting edge 1. Regarding the inclination angle α, when the inclination angle α of the pressing sliding contact surface 2 is 0°, i.e., when the pressing sliding contact surface 2 is parallel to the surface S perpendicular to the tool's rotation axis C, no pressing action is generated, making it difficult to achieve a grinding effect. Furthermore, when the inclination angle α is greater than 4°, the cutting resistance increases, potentially leading to chipping or tool damage due to instability in the tool's posture. Therefore, the inclination angle α is set to be greater than 0° and less than 4°, preferably greater than 0.5° and less than 4°, and more preferably greater than 1° and less than 3°.

[0063] Furthermore, in this embodiment, the pressing and sliding contact surface 2 is provided over the entire area of ​​the bottom edge 1, but the length of the pressing and sliding contact surface 2 is not limited to that of this embodiment. The pressing and sliding contact surface 2 can be any structure that has a length of more than 1% of the outer diameter of the tool and is provided from the outer peripheral base point of the bottom edge 1, i.e., the boundary between the bottom edge 1 and the corner R edge 6, toward the tool rotation axis C.

[0064] In addition, the shape of the pressing sliding contact surface 2 is not limited to a strip shape, but can also be a roughly triangular shape when viewed from the front end of the tool, with the surface width gradually decreasing towards the tool's rotation axis C.

[0065] In addition, such as Figure 1 and Figure 4 As shown, the pressing sliding contact surface 2 is configured to be continuously arranged with the back cutting surface 3 located behind the tool rotation direction of the bottom cutting edge 1. The pressing sliding contact surface 2 and the edge line 4 formed at the boundary between the pressing sliding contact surface 2 and the back cutting surface 3 are in sliding contact with the cutting surface in a pressing state.

[0066] That is, the bottom cutting edge of a conventional radius end mill (hereinafter referred to as "existing product") is formed by the rake face and the flank face, but in this embodiment, a pressing and sliding contact surface 2 is provided between the bottom cutting edge 1 and the flank face 3. Therefore, the bottom cutting edge 1 is formed by the rake face 10 and the pressing and sliding contact surface 2 (the edge line formed at the boundary between the rake face 10 and the pressing and sliding contact surface 2 becomes the bottom cutting edge 1).

[0067] In addition, such as Figure 4As shown, this embodiment has a structure with a convex region 5, which includes the aforementioned pressing and sliding contact surface 2, the back face 3, and the ridge line 4. The convex region 5 protrudes further towards the tool tip than the bottom cutting edge 1. The convex region 5 is configured such that the protrusion A relative to the bottom cutting edge 1 is greater than 0 mm and less than 0.004 mm, preferably more than 0.001 mm and less than 0.003 mm. Here, the protrusion A of the convex region 5 in this embodiment is the protrusion of the outermost peripheral side (the boundary side with the corner R-edge 6) of the area that facilitates the cutting of the bottom cutting edge 1, and can be determined by direct measurement using a microscope or a shape measuring machine. In addition, when the protrusion A is small and it is difficult to perform direct measurement as described above, it can also be determined by the following formula (1) (refer to...). Figure 4 ).

[0068] The amount of protrusion A = w × tanα (1)

[0069] Here, w is the width of the pressing sliding contact surface 2, and α is the tilt angle of the pressing sliding contact surface 2.

[0070] In addition, in this embodiment, the end-edge clearance angle β of the bottom cutting edge 1 (refer to...) Figure 5 The angle is set to be smaller than that of existing products (about 3°) so that the contact area between the pressing sliding contact surface 2 and the material being cut is increased.

[0071] Specifically, in this embodiment, the end-edge clearance angle β of the bottom edge 1 is set to 0° or more and 1° or less, preferably 0° or more and 0.5° or less, and more preferably 0° or more and 0.2° or less (0° is ideal; when the end-edge clearance angle β is less than 0°, the foremost point of the tool is located near the tool rotation axis C, and the pressing and sliding contact function of the pressing and sliding contact surface 2 (convex area 5) cannot be exerted, and the machined surface becomes rough and becomes a dull machined surface).

[0072] Alternatively, the bottom edge 1 may not use the fixed end edge clearance angle β as described above, but may use a structure in which the end edge clearance angle β varies in the length direction (radial) of the bottom edge 1.

[0073] Specifically, for example, such as Figure 6 As shown, it can also be configured such that within a specified range X1 on the outer periphery of the bottom cutting edge 1, the end-cutting clearance angle β is set to 0° to 0.5°, and within a range X2 that is closer to the inner side of the specified range X1 (on the side of the tool rotation axis C), the end-cutting clearance angle β is set to the same angle (about 3°) as conventional radius end mills.

[0074] In this embodiment, the sliding contact surface 2 is pressed to plastically deform the cutting surface cut by the bottom edge 1 while grinding it flat, thereby improving the polishing effect. Even for deep scratches caused by over-cutting due to structural edge tip, chip entrapment, etc., it can play a sufficient grinding role, remove cutting marks and finish the machined surface (cutting surface) into a good glossy surface.

[0075] Therefore, it has become a practical radius end mill that can eliminate the grinding process after cutting, or can shorten the processing time in the existing grinding process, reduce working hours, and improve productivity.

[0076] In addition, in this embodiment, by providing a pressing and sliding contact surface 2 along the bottom cutting edge 1, the wedge angle of the bottom cutting edge 1 becomes larger and the volume of the front end of the bottom cutting edge 1 becomes larger, thus becoming a radius end mill that minimizes damage to the bottom cutting edge 1 and has excellent durability.

[0077] Furthermore, as shown in Experiments 2 and 3 described later, this embodiment demonstrates particularly excellent performance for relatively soft workpiece materials (Rockwell hardness below 50 HRC). Therefore, by using this embodiment in the machining of soft workpiece materials that are prone to structural cutting edges and plastic deformation, even deep scratches caused by overcutting due to structural cutting edges are effectively ground, removing cutting marks and finishing the machined surface (cutting surface) with a good gloss.

[0078] The following is an experiment (evaluation) demonstrating the effectiveness of the above-described embodiment.

[0079] <Experiment 1>

[0080] In Experiment 1, the appropriate conditions (range) of the tilt angle α of the pressing sliding contact surface 2, the end blade gap angle β of the bottom blade 1, and the protrusion amount A of the convex area 5 in this embodiment were confirmed.

[0081] Specifically, evaluation samples No. 1 to 15 as shown in Table 1 were prepared, and the gloss of the machined surface compared to existing products (conventional radius end mills without pressing the sliding contact surface 2) was evaluated when the workpiece was machined under the following machining conditions. Furthermore, the gloss level compared to existing products was confirmed visually. For the judgment, a case with excellent gloss and almost no visible cutting marks was marked as ◎, a case with gloss above that of existing products but with visible cutting marks was marked as ○, a case the same as existing products was marked as △, and a case where the machined surface was blurry and worse than existing products was marked as ×.

[0082] Table 1

[0083]

[0084] [Processing Conditions]

[0085] Tool outer diameter: Corner radius R: 1mm, handle diameter:

[0086] Material to be cut: Pre-hardened steel (30HRC)

[0087] Rotational speed: 5,250 rpm

[0088] Feed rate: 1,600 mm / min

[0089] Axial cut-in depth: 0.03mm

[0090] Radial cut-in depth: 0.15mm

[0091] Coolant: Water-soluble cutting oil

[0092] As shown in Table 1, based on the results of experiments No. 2, No. 3, No. 6, No. 7 and No. 12 to No. 15, it was confirmed that the tilt angle α of the pressing sliding contact surface 2 can exceed 0° and be less than 4°, preferably more than 0.5° and less than 4°, and more preferably more than 1° and less than 3°.

[0093] Furthermore, based on the results of experiments No.2, No.9, No.10 and No.11, it was confirmed that the end-edge clearance angle β of the bottom edge 1 can be less than 1°, and preferably less than 0.5°.

[0094] Furthermore, based on the results of experiments No.2 to No.8, it was confirmed that the protrusion A of the convex region 5 can be 0.004 mm or less, and preferably 0.001 mm or more and 0.003 mm or less.

[0095] <Experiment 2>

[0096] Experiment 2 confirmed the effectiveness of this embodiment when machining materials with different hardnesses.

[0097] Specifically, using existing products and this embodiment (both with the following processing conditions: tilt angle α of the pressing sliding contact surface 2: 2°, protrusion A of the convex area 5: 0.001mm, and end-edge clearance angle β of the bottom cutting edge 1: 0°, and the other with the same conditions), we processed various workpieces with Rockwell hardness ranging from 30HRC to 53HRC, according to the following processing conditions, and evaluated the gloss of the processed surface. Furthermore, the gloss was confirmed visually. Additionally, as... Figures 9-12As shown, a component for confirming reflection is used, which repeatedly displays multiple distinct "○" and "01" symbols. The surface with the repeated "○" and "01" symbols is covered over the machined surface of the material being cut. The visual representation of the "○" and "01" symbols (reflected images) reflected on the machined surface is confirmed and represented as "reflection". Regarding the determination, a case where the machined surface has a glossy finish and good reflection is marked as ◎; a case where the machined surface has a cloudy appearance or cutting marks but reflection exists is marked as ○; and a case where cutting marks are obvious and there is almost no reflection is marked as ×.

[0098] [Processing Conditions]

[0099] Tool outer diameter: Corner radius R: 0.2mm, handle diameter:

[0100] Materials to be cut: Pre-hardened steel, quenched steel (30HRC~53HRC)

[0101] Rotational speed: 10,500 rpm

[0102] Feed rate: 1,600 mm / min

[0103] Axial cut-in depth: 0.03mm

[0104] Radial cut-in depth: 0.15mm

[0105] Coolant: Water-soluble cutting oil

[0106] Table 2 below shows the evaluation results of Experiment 2. Additionally, Figures 9-12 The results of Experiment 2 show the comparison of the state (gloss) of the processed surfaces.

[0107] Table 2

[0108]

[0109] As shown in Table 2 and Figures 9-12 As shown, existing products produce obvious cutting marks and almost no reflection for all types of materials being cut, or although reflection exists, the machined surface appears cloudy and shows cutting marks, making it impossible to achieve gloss. In contrast, this embodiment achieves excellent gloss with good reflection under the conditions of end-edge clearance angle β: 0° and 0.5° for materials with a hardness (Rockwell hardness) of 30HRC to 50HRC.

[0110] Based on the results of Experiment 2, it was confirmed that this embodiment can effectively grind even deep scratches caused by overcutting due to structural cutting edges in the machining of soft cut materials that are prone to structural cutting edges, and can remove cutting marks and finish the machined surface (cutting surface) with a good gloss.

[0111] <Experiment 3>

[0112] In Experiment 3, the effectiveness of this embodiment in machining a workpiece that is softer than the workpiece used in Experiment 2 was confirmed.

[0113] Specifically, using existing products and this embodiment (the tilt angle α of the pressing sliding contact surface 2 is 2°, the protrusion A of the convex area 5 is 0.001mm, and the end-edge clearance angle β of the bottom edge 1 is 0°), the material to be cut is processed according to the following processing conditions, and the processed surface is observed using a laser microscope.

[0114] [Processing Conditions]

[0115] Tool outer diameter: Corner radius R: 0.2mm, handle diameter:

[0116] Material to be cut: Carbon steel S50C (Brinell hardness: approximately 150 HBW)

[0117] Rotational speed: 10,500 rpm

[0118] Feed rate: 1,600 mm / min

[0119] Axial cut-in depth: 0.03mm

[0120] Radial cut-in depth: 0.15mm

[0121] Coolant: Water-soluble cutting oil

[0122] Figure 13 The results of observing the state of the machined surface using a laser microscope in Experiment 3 are shown.

[0123] like Figure 13 As shown, existing products show multiple scratches on the machined surface, while in contrast, this embodiment shows almost no scratches on the machined surface.

[0124] Based on the results of Experiment 3, it was confirmed that this embodiment, in the processing of steel that is softer than pre-hardened steel before heat treatment, can effectively grind even deep scratches caused by over-cutting due to the structural cutting edge, and can remove cutting marks and finish the machined surface (cutting surface) with a good gloss.

[0125] <Experiment 4>

[0126] In Experiment 4, the end-edge clearance angle β of the bottom edge 1 was confirmed, including cases where it was less than 0°.

[0127] Specifically, evaluation samples (Experiments No. 28-30) were prepared with the tilt angle α of the pressing sliding contact surface 2 set to 2° and the end-edge clearance angle β set to -0.25° (comparative example), 0° (this embodiment), and 0.5° (this embodiment). The gloss of the machined surface was evaluated when the workpiece was machined under the following processing conditions. Furthermore, the gloss was confirmed visually. Figure 14 As shown, a component for confirming projection is used, in which multiple distinct "○×" symbols are repeatedly arranged. The surface with the repeated "○×" symbols is covered on the machined surface of the material being cut. The visual representation of the "○×" symbols (reflected image) projected onto the machined surface is confirmed and represented as "projection". Regarding the determination, as in Experiment 2, a case where the machined surface has a glossy finish and projection is good is marked as ◎, a case where the machined surface has a cloudy finish or cutting marks but projection is present is marked as ○, and a case where the cutting marks are obvious and projection is almost nonexistent is marked as ×.

[0128] [Processing Conditions]

[0129] Tool outer diameter: Corner radius R: 0.2mm, handle diameter:

[0130] Material to be cut: Carbon steel S50C (Brinell hardness: approximately 150 HBW)

[0131] Rotational speed: 10,500 rpm

[0132] Feed rate: 1,600 mm / min

[0133] Axial cut-in depth: 0.03mm

[0134] Radial cut-in depth: 0.15mm

[0135] Coolant: Water-soluble cutting oil

[0136] Table 3 below shows the evaluation results of Experiment 4. Additionally, Figure 14 The results of Experiment 4 show the comparison of the state (gloss) of the processed surfaces.

[0137] Table 3

[0138]

[0139] As shown in Table 3 and Figure 14 As shown, the results are as follows: in the samples with a cutting edge clearance angle β of 0° (Experiment No. 29) and 0.5° (Experiment No. 30), the machined surface has gloss and good reflection, but in the sample with a cutting edge clearance angle β of -0.25° (Experiment No. 28), the machined surface is rough, the cutting marks are obvious, and there is almost no reflection.

[0140] The reason for this result is believed to be that when the end-edge clearance angle β is less than 0°, the front end of the tool is located near the tool rotation axis C, so there is no effect of pressing the sliding contact surface 2 and the edge 4 (convex area 5) to plastically deform the cutting surface cut by the bottom edge 1 while grinding it flat.

[0141] Furthermore, the present invention is not limited to this embodiment, and the specific structure of each structural element can be appropriately designed.

Claims

1. An end mill, having a straight bottom cutting edge at the tool tip, characterized in that, A pressing and sliding contact surface is continuously provided on the rear side of the bottom edge in the tool rotation direction. The pressing and sliding contact surface slides in contact with the cutting surface cut by the bottom edge in a pressing state. The pressing and sliding contact surface is configured as an inclined plane that is inclined upward from the bottom edge side toward the rear side of the tool rotation direction with a predetermined inclination angle when the tool tip is facing upward. The inclination angle is set to be more than 0° and less than 4° relative to the plane perpendicular to the tool rotation axis.

2. The end mill according to claim 1, characterized in that, A rear cutting surface is continuously provided on the rear side of the tool rotation direction of the pressing sliding contact surface. The pressing sliding contact surface and the edge line formed at the boundary between the pressing sliding contact surface and the rear cutting surface are configured to slide in contact with the cutting surface in a pressing state.

3. The end mill according to claim 2, characterized in that, The end mill has a convex region that includes the pressing sliding contact surface, the flank face, and the ridge. The convex region protrudes relative to the bottom cutting edge in the direction of the tool tip. The convex region is configured such that the amount of protrusion relative to the bottom cutting edge is greater than 0 mm and less than 0.004 mm.

4. The end mill according to claim 1, characterized in that, The pressing and sliding contact surface has a length of more than 1% of the tool's outer diameter and is positioned from the outer peripheral base point of the bottom edge toward the tool's rotation axis.

5. The end mill according to claim 2, characterized in that, The pressing and sliding contact surface has a length of more than 1% of the tool's outer diameter and is positioned from the outer peripheral base point of the bottom edge toward the tool's rotation axis.

6. The end mill according to claim 3, characterized in that, The pressing and sliding contact surface has a length of more than 1% of the tool's outer diameter and is positioned from the outer peripheral base point of the bottom edge toward the tool's rotation axis.

7. The end mill according to any one of claims 1 to 6, characterized in that, The end-edge clearance angle of the bottom edge is greater than 0° and less than 1°.

8. The end mill according to any one of claims 1 to 6, characterized in that, The pressing and sliding contact surface is formed in the shape of a strip, which is set from the outer peripheral base point of the bottom edge to the vicinity of the tool rotation axis.

9. The end mill according to claim 7, characterized in that, The pressing and sliding contact surface is formed in the shape of a strip, which is set from the outer peripheral base point of the bottom edge to the vicinity of the tool rotation axis.

10. The end mill according to any one of claims 1 to 6, characterized in that, The end mill is configured as a radius end mill, and a corner R-edge is continuously formed on the outer periphery of the bottom cutting edge, and an outer peripheral cutting edge is continuously formed on the corner R-edge.

11. The end mill according to claim 7, characterized in that, The end mill is configured as a radius end mill, and a corner R-edge is continuously formed on the outer periphery of the bottom cutting edge, and an outer peripheral cutting edge is continuously formed on the corner R-edge.

12. The end mill according to claim 8, characterized in that, The end mill is configured as a radius end mill, and a corner R-edge is continuously formed on the outer periphery of the bottom cutting edge, and an outer peripheral cutting edge is continuously formed on the corner R-edge.

13. The end mill according to claim 9, characterized in that, The end mill is configured as a radius end mill, and a corner R-edge is continuously formed on the outer periphery of the bottom cutting edge, and an outer peripheral cutting edge is continuously formed on the corner R-edge.

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