Cutting insert, indexable rotary cutting tool with replaceable cutting edge and its tool body

Abstract

Provided is a cutting blade, the structure of which can improve the mounting accuracy of mounting a cutting tool to a tool body and can increase the number of cutting edges in a state of being loaded on the tool body. The cutting blade includes: an upper surface having a shape with a long side direction and a short side direction; a lower surface located on the side opposite to the upper surface; a peripheral side surface formed to connect the upper surface and the lower surface; cutting edges respectively formed on the intersecting ridge lines of the upper surface and the peripheral side surface and on the intersecting ridge lines of the lower surface and the peripheral side surface, and the ridge lines extending in the long side direction are in a curved shape; and a screw through-hole penetrating from the upper surface to the lower surface. In the peripheral side surface, the end surfaces located in the long side direction of the upper surface and the lower surface are inclined with respect to the upper surface or the lower surface and are parallel to each other. In the peripheral side surface, a reference surface located on the side opposite to the cutting edge is a flat surface perpendicular to the upper surface or the lower surface.

Description

Technical Field

[0001] The present invention relates to a cutting blade, a replaceable-edge rotary cutting tool, and a tool body thereof. Background Art

[0002] When performing five-axis machining on a workpiece with a complex shape, a die, or other cutting materials, in order to achieve high-efficiency machining in the finish machining process and ensure a good machined surface, a cutting blade with a curved cutting edge and a replaceable-edge rotary cutting tool detachably mounted with the cutting blade are used. The cutting blade used in the finish machining process or the like has a high precision requirement for the cutting edge profile and the like (for example, refer to Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-189855 Summary of the Invention

[0006] Technical Problem to be Solved

[0007] However, as described above, the existing cutting blade is orthomorphic to ensure sharpness, and as a result, the mounting accuracy of the cutting tool on the tool body is poor. In addition, there are the following problems: If the sizes of the screws used when mounting the cutting tool to the tool body are the same and the number of corners in a cutting blade is increased (for example, it is set in a style with two corners on one side), the width of the blade will become larger, so it is difficult to increase the number of cutting edges in the state of being loaded on the tool body.

[0008] Therefore, an object of the present invention is to provide a cutting blade, a replaceable-edge rotary cutting tool, and a tool body thereof, the structure of which can improve the mounting accuracy of the cutting tool to the tool body and can increase the number of cutting edges in the state of being loaded on the tool body.

[0009] Technical Solution for Solving the Problem

[0010] One aspect of the present invention is a cutting blade, comprising:

[0011] An upper surface having a long side direction and a short side direction;

[0012] A lower surface located on the opposite side of the upper surface and having a long side direction and a short side direction;

[0013] A peripheral side surface formed to connect the upper surface and the lower surface;

[0014] Cutting edges are respectively formed on the intersecting ridges of the upper surface and the peripheral side surface, and the intersecting ridges of the lower surface and the peripheral side surface, and the ridges extending in the long side direction are in a curved shape; and

[0015] Screw through-holes penetrate from the upper surface to the lower surface.

[0016] Among them, in the peripheral side surface, the end surfaces in the long side direction of the upper surface and the lower surface are inclined with respect to the upper surface or the lower surface and are parallel to each other.

[0017] In the peripheral side surface, the reference surface on the side opposite to the cutting edge is a flat surface perpendicular to the upper surface or the lower surface.

[0018] According to the above aspect, in the peripheral side surface, the reference surface on the side opposite to the cutting edge is a flat surface perpendicular to the upper surface or the lower surface. Therefore, compared with the existing blade shape, more stable installation can be achieved. In addition, by making the end surfaces in the long side direction of the upper surface and the lower surface parallel to each other and inclined with respect to the upper surface and the lower surface, the clamping stiffness of the blade during cutting can be improved more compared with the existing blade shape. Moreover, by adopting a style with cutting edges on both surfaces (the upper surface and the lower surface), the number of corners in a cutting blade can be increased without increasing the width of the blade. Therefore, the number of cutting edges can be increased in the state of being loaded on the tool body.

[0019] In the cutting blade as described above, when observed from a direction perpendicular to the upper surface or the lower surface, the curved cutting edge and the intersection area in the long side direction of the upper surface or the lower surface can be connected by a bending portion.

[0020] The bending portion in the cutting blade as described above can be in an arc shape.

[0021] In the cutting blade as described above, the radius of curvature of the bending portion can be smaller than the radius of curvature of the cutting edge.

[0022] In the cutting blade as described above, the upper surface and the lower surface can be in an axisymmetric shape centered on the symmetric center axis perpendicular to the reference surface, and the positions can be offset from each other in the long side direction at the same angle as the inclination angle of the end surface.

[0023] In the cutting blade as described above, the shape of the flank of the cutting edge can be such that the clearance angle gradually changes from a positive angle to a negative angle in the long side direction.

[0024] In the cutting blade as described above, the upper surface can be formed into the following shape: the height of the upper surface along the axis perpendicular to the long side direction and the short side direction first decreases as it approaches the cutting edge, and then gradually increases as it approaches the cutting edge.

[0025] The cutting blade according to the above aspect can be formed into the following shape: the height of the cutting edge in the axial direction is higher than the flat portion around the screw through-hole in the upper surface.

[0026] Another aspect of the present invention is a tool body of a cutting tool, which detachably mounts the cutting blade as described above, and the tool body includes:

[0027] A mounting surface, and the flat portion around the screw through-hole in the upper surface or the lower surface of the cutting blade is mounted as the mounting surface; and

[0028] A restraining surface, which is perpendicular to the mounting surface and abuts against the reference surface on the cutting blade.

[0029] Another aspect of the present invention is a replaceable-edge rotary cutting tool, which includes the tool body as described above. Description of the Drawings

[0030] Figure 1A is a view showing an example of a replaceable-edge rotary cutting tool detachably mounted with a cutting blade.

[0031] Figure 1B is Figure 1A a view showing an enlarged part of the replaceable-edge rotary cutting tool shown.

[0032] Figure 2A is a perspective view showing an example of a replaceable-edge rotary cutting tool detachably mounted with a cutting blade as viewed from the tip side.

[0033] Figure 2B is Figure 2A a view showing an enlarged part of the replaceable-edge rotary cutting tool shown.

[0034] Figure 3A is a view showing an example of a replaceable-edge rotary cutting tool detachably mounted with a cutting blade as viewed from the side.

[0035] Figure 3B is a longitudinal sectional view showing Figure 3A a part of the replaceable-edge rotary cutting tool shown.

[0036] Figure 4 is a view (bottom view) showing an example of a replaceable-edge rotary cutting tool detachably mounted with a cutting blade as viewed from the front end side.

[0037] Figure 5 is a perspective view showing an example of a cutting blade.

[0038] Figure 6It is a view of the cutting blade observed from the upper surface (top view).

[0039] Figure 7 It is a view of the peripheral side surface provided with the cutting edge of the cutting blade observed along the short side direction of the upper surface (or lower surface).

[0040] Figure 8 It is a view of the surface called the end face in the peripheral side surface provided with the cutting edge of the cutting blade observed along the long side direction of the upper surface (or lower surface).

[0041] Figure 9A It is along Figure 6 A sectional view of the cutting blade along the IXA - IXA line in

[0042] Figure 9B It is along Figure 6 A sectional view of the cutting blade along the IXB - IXB line in

[0043] Figure 9C It is along Figure 6 A sectional view of the cutting blade along the IXC - IXC line in

[0044] Figure 10A It is along Figure 6 A sectional view of the cutting blade along the XA - XA line in

[0045] Figure 10B It is a view that magnifies and shows the part of the cutting edge of the cutting blade shown in Figure 10A

[0046] Figure 11 It is a view that magnifies and shows the difference in the positions of the cutting edge on the upper surface and the cutting edge on the lower surface of the cutting blade.

[0047] Explanation of reference numerals

[0048] 1: Cutting blade;

[0049] 10: Upper surface;

[0050] 10F: Flat part of the upper surface;

[0051] 15: Front cutting part;

[0052] 20: Lower surface;

[0053] 20F: Flat part of the lower surface;

[0054] 25: Front cutting part;

[0055] 30: Peripheral side surface;

[0056] 31: One end face (end face) in the long side direction;

[0057] ​32: The other end face (end face) in the long side direction;

[0058] 33: Reference plane;

[0059] 34: Rear flank;

[0060] 40: Crossing area;

[0061] 51, 52: Cutting edges with a curved shape;

[0062] 60: Screw through-hole;

[0063] 70: Corner part (bent part);

[0064] 100: Indexable rotary cutting tool;

[0065] 100C: Tool rotation axis;

[0066] 110: Tool body;

[0067] 112: Mounting surface;

[0068] 113: Restraint surface of the tool body that contacts the reference plane of the cutting insert;

[0069] 120: Screw;

[0070] LD: Long side direction;

[0071] SD: Short side direction;

[0072] w: Inclined ridge line connecting the corner between the upper surface and the end face 31 and the corner between the lower surface and the end face 31;

[0073] X: Central axis (axis perpendicular to the long side direction and the short side direction);

[0074] Y: Symmetry central axis;

[0075] α: Rear angle;

[0076] β: Inclination angle of the end face. Detailed implementation mode

[0077] Hereinafter, a preferred implementation mode of the cutting insert of the present invention will be described in detail with reference to the accompanying drawings. First, the outline of the cutting insert 1 for cutting a workpiece (not shown) will be described, and then the characteristic parts of the cutting insert 1 of the present invention will be described (refer to Figure 1A etc.).

[0078] <Summary of the indexable rotary cutting tool>

[0079] The replaceable-edge rotary cutting tool 100 is a tool used for five-axis machining of cutting materials (workpieces) such as parts and molds with particularly complex shapes, in order to achieve high-efficiency machining in the finish machining process and ensure a good machined surface. In the present embodiment, the replaceable-edge rotary cutting tool 100 is used, and a cutting blade 1 is detachably mounted thereon. The cutting edges 51 and 52 of the cutting blade 1 are curved (refer to Figures 1A - 4 ). With the cutting blade 1 mounted on the mounting surface 112 provided at the front end of the tool body 110, the replaceable-edge rotary cutting tool 100 rotates about the tool rotation axis 100C to cut the workpiece (refer to Figure 4 etc.).

[0080] <Summary of the cutting blade>

[0081] The cutting blade 1 of the present embodiment has: an upper surface 10 as the first end surface, which faces upward along the central axis X Figure 5 above; a lower surface 20 as the second end surface, which faces downward opposite to the upper surface; a peripheral side surface 30, which is formed to connect the upper surface 10 and the lower surface 20; cutting edges 51 and 52; a screw through-hole 60, which penetrates from the upper surface 10 to the lower surface 20; and a corner portion (bending portion) 70 etc. (refer to Figure 5 etc.).

[0082] The upper surface 10 and the lower surface 20 are substantially rectangular surfaces having a long side portion and a short side portion. The long side portion extends along the long side direction (denoted by the symbol LD in the figure), and the short side portion extends along the short side direction (denoted by the symbol SD in the figure). The lower surface 20 is configured to include a flat portion 20F, which becomes the mounting surface or the restraining surface in contact with the mounting surface 112 of the tool body 110 when the cutting blade 1 is mounted on the replaceable-edge rotary cutting tool 100. In addition, the upper surface 10 is configured to include a flat portion 10F, which becomes the mounting surface or the restraining surface in contact with the mounting surface of the tool body 110 when the cutting blade 1 is reversely mounted on the replaceable-edge rotary cutting tool 100.

[0083] The cutting edge 51 is formed on the intersecting ridge line of the upper surface 10 and the peripheral side surface 30 such that the ridge line extending along the long side direction is curved. The cutting edge 52 is formed on the intersecting ridge line of the lower surface 20 and the peripheral side surface 30 such that the ridge line extending along the long side direction is curved (refer to Figure 5 , Figure 8 etc.). In the present embodiment, these cutting edges 51 and 52 are formed in an arc shape (refer to Figure 6 etc.). It should be noted that the cutting edges 51 and 52 formed in such a curved shape or arc shape do not include the corner portion 70, and the configurations of these cutting edges 51 and 52 are different from that of the corner portion 70.

[0084] In the upper surface 10 and the lower surface 20, portions connecting the cutting edges 51 and 52 are formed with rake portions 15 and 25 (refer to Figure 10A etc.). In the cutting insert 1 of the present embodiment, the shape of the rake portion 15 on the upper surface 10 is formed such that the height along the axis perpendicular to the long side direction LD and the short side direction SD (i.e., the central axis X) first slightly decreases as it approaches the cutting edge 51, and then gradually increases as it approaches the cutting edge 51, and near the cutting edge 51, it is higher than the flat portion (in other words, the flat portion that becomes the mounting surface or the restraining surface in contact with the mounting surface of the tool body 110) 10F around the screw through hole in the upper surface 10 (refer to Figure 10B ). The rake portion 25 on the lower surface 20 is also formed in the same shape (refer to Figure 10A etc.). By forming the portions connecting the cutting edges 51 and 52 in the upper surface 10 and the lower surface 20 in such a shape, the rake angle of the cutting insert 1 can be increased in the positive direction, and thus, the cutting resistance can be reduced and the sharpness can be improved.

[0085] The corner portions 70 are formed between the cutting edges 51 and 52 and the intersection regions in the long side direction LD on the upper surface 10 or the lower surface 20 (in other words, the edge portions between the upper surface 10 or the lower surface 20 and the end faces 31 and 32), connecting them (refer to Figure 5 etc.). When observed from a direction perpendicular to the upper surface 10 or the lower surface 20, these corner portions 70 are in an R shape (arc shape) (refer to Figure 6 etc.). The radius of curvature of the R-shaped corner portions 70 is smaller than the radius of curvature of the cutting edges 51 and 52.

[0086] In the peripheral side surface 30, the two end faces (in other words, the two side surfaces connecting the short side portions of the upper surface 10 and the lower surface 20, one end face is denoted by the symbol 31 and the other end face is denoted by the symbol 32) located in the long side direction LD are inclined with respect to the upper surface or the lower surface and are parallel to each other (refer to Figure 5 etc.), and when the cutting insert 1 is observed in the short side direction SD, the cutting insert 1 is substantially rhomboid (diamond) (refer to Figure 7 ). In the cutting insert 1 of the present embodiment, these two end faces 31 and 32 are inclined with a negative angle β with respect to the upper surface 10 or the lower surface 20. The negative angle β here means that in the indexable rotary cutting tool 100, for example, when the lower surface 20 is mounted toward the mounting surface 112 with a screw 120, the end face (in this example, the angle between the end face 32 facing the base end side and the lower surface 20) on the base end side (opposite to the front end. Figure 3B etc., the upper side in the above) of the indexable rotary cutting tool 100 becomes an acute angle (refer to Figure 3B , Figure 7The inclination angle β is, for example, 11 degrees. Usually, the upper surface 10 and the lower surface 20 are roughly rectangular cutting blades, which are easy to move relative to the tool body 110 due to the cutting resistance generated during the processing. In the present embodiment, the following dovetail structure is formed: by setting an inclination on the two end faces 31 and 32 as described above, the base end side of the blade-replaceable rotary cutting tool 100 is combined with the wedge effect to enhance the constraint with the tool body 110 and suppress the warping of the blade. Such a dovetail structure makes it difficult for the cutting blade 1 to move during the processing, thereby enabling further high-precision processing. In addition, on the front end side of the blade-replaceable rotary cutting tool 100, the inclined end face 31 (32) forms a positive back angle.

[0087] The surface of the peripheral side surface 30 located on the opposite side to the cutting edges 51 and 52 is configured as a reference surface 33 (see Figure 8 , Figure 10A etc.). In this embodiment, the reference surface 33 is made perpendicular to the upper surface 10 and the lower surface 20 which are the constraint surfaces as described above. According to the cutting insert 1 of this embodiment, the deviation is reduced when it is installed on the tool body 110. In further detail, for example, even if there is a difference in the installation height of the cutting insert 1 due to manufacturing errors that may be caused by the shape or smooth surface of the upper surface 10 or the lower surface 20, as long as the reference surface 33 is perpendicular, the position of the cutting edges 51 and 52 (the distance from the constraint surface 113 of the tool body 110 connected to the reference surface 33 to the cutting edges 51 and 52) is always constant regardless of the installation height, and it can be expected that the deviation is very small (refer to Figure 4 etc.). Therefore, for example, when the cutting insert 1 is reversed, reinstalled to the cutter body 110 and the cutting edges 51, 52 are interchanged, the deviation of the distance between the cutting edges 51, 52 and the side surface (constraint surface) is reduced, and higher precision processing can be performed. It should be noted that the reference surface 33 composed of a flat surface is described here, but this is only a preferred example. As described above, as long as it can function as a reference surface, it does not matter even if, for example, a groove is formed in a portion and the reference surface 33 is not flat as a whole.

[0088] The portion of the peripheral side surface 30 connecting the cutting edge 51 on the upper surface 10 side and the cutting edge 52 on the lower surface 20 side functions as a flank surface (indicated by reference numeral 34) of the cutting edges 51 and 52 (see Figure 5 The shape of the flank surface 34 in the cutting insert 1 of the present embodiment is such that the flank angle α gradually changes along the longitudinal direction LD (see Figure 6 , Figures 9A - 9C)。That is, in the cutting blade 1 of the present embodiment, the upper surface 10 and the lower surface 20 are axially symmetric shapes centered on a symmetric center axis (denoted by the symbol Y) that is perpendicular to the reference plane 33 and passes through the center of the reference plane 33. By reversing 180° around the symmetric center axis Y, the cutting edge 51 on the upper surface 10 side and the cutting edge 52 on the lower surface 20 side can be interchanged. Furthermore, the positions of the upper surface 10 and the lower surface 20 are offset from each other in the longitudinal direction LD at the same angle as the inclination angle β of the end faces 31, 32 ( Figure 7 , Figure 11 ). The shape of the flank face 34 formed by the surface connecting the upper surface 10 and the lower surface 20 in such a positional relationship is such that the clearance angle α gradually changes from a positive angle to a negative angle in the longitudinal direction LD (see Figures 9A - 9C ). In addition, the clearance angle α of the flank face 34 is zero at the middle in the longitudinal direction LD (see Figure 9B ). The flank face 34 of the cutting blade 1 of the present embodiment can be, for example, the surface formed by the locus passed by the arc-shaped cutting edge 51 of the upper surface 10 during the process of translating the arc-shaped cutting edge 51 of the upper surface 10 parallel to the arc-shaped cutting edge 52 (position) of the lower surface 20. In other words, the flank face 34 can be constituted by a curved surface obtained by extending the curve of the arc-shaped cutting edge 51 of the upper surface 10 in the direction of the arc-shaped cutting edge 52 of the lower surface 20.

[0089] As described above, since the structure of the cutting blade 1 of the present embodiment has cutting edges 51, 52 on both the upper surface 10 and the lower surface 20, it is possible to ensure a plurality of cutting edge numbers without increasing the blade width (the width in the short side direction SD according to the above embodiment, in other words, the distance between the cutting edges 51, 52 and the reference plane 33). Thus, if the blade width can be suppressed while ensuring the cutting edge number, the number of blades mounted on the tool body 110 of the indexable rotary cutting tool 100 can be increased, and the number of cutting edges in the tool can be increased.

[0090] In addition, as described above, the cutting blade 1 of the present embodiment is of a two-corner type, but has a flat surface on the side opposite to the cutting edges 51, 52 and the short side direction SD. Since this flat surface effectively functions as the reference plane 33 both when manufacturing the blade and when mounting the blade on the tool body, unprecedented high-precision machining can be achieved.

[0091] In addition, the cutting blade 1 of the present embodiment as described above or the indexable rotary cutting tool 100 on which the cutting blade can be mounted can solve the following problems in the existing structure:

[0092] 1. It can solve the problems of poor accuracy and economy in the existing structure due to the inclination of the reference plane and only one corner of the cutting edge. That is, if the side surface on the side opposite to the cutting edge is a flat surface and is inclined at a positive angle, it is difficult to use it as the "reference plane" for accurately mounting the cutting edge (and the flank face) with a curved shape. In addition, when the inclined surface is used as the reference plane, the machining accuracy is likely to be reduced. Moreover, since only one cutting edge can be used, the economy may decline.

[0093] 2. It can solve the problems in the existing structure due to the inclination of the reference plane and although there are 4 corners on the cutting edge but all are square shapes, resulting in that the tool body cannot carry many inserts and poor economy (machining efficiency). For example, in a 4-corner type positive rake insert with a cutting edge of an arc shape, the side surface on the side opposite to the cutting edge is not a flat surface. And it does not have a short side direction, and since it is square, the width of the insert is large and it cannot be applied to a end mill with a small diameter size.

[0094] It should be noted that the above embodiments are an example of the preferred implementation of the present invention, but are not limited thereto, and various deformations can be made without departing from the gist of the present invention.

[0095] Industrial Applicability

[0096] The present invention is preferably applied to cutting inserts and indexable rotary cutting tools.

Claims

1. A cutting insert, characterized in that, Comprising: An upper surface, which is in a shape having a long side direction and a short side direction; A lower surface, which is located on the opposite side of the upper surface and is in a shape having a long side direction and a short side direction; A peripheral side surface, which is formed to connect the upper surface and the lower surface; Cutting edges, which are respectively formed on the intersecting ridge lines of the upper surface and the peripheral side surface, and the intersecting ridge lines of the lower surface and the peripheral side surface, and the ridge lines extending in the long side direction are in a curved shape; And Screw through holes, which penetrate from the upper surface to the lower surface, Wherein, in the peripheral side surface, the end surfaces in the long side direction of the upper surface and the lower surface are inclined relative to the upper surface or the lower surface and are parallel to each other, In the peripheral side surface, the reference surface located on the side opposite to the cutting edge is a flat surface perpendicular to the upper surface and the lower surface; Wherein, the shape of the flank face of the cutting edge is such that its clearance angle gradually changes from a positive angle to a negative angle along the long side direction, The shape formed by the upper surface is such that the height of the upper surface along the axis perpendicular to the long side direction and the short side direction first decreases as it approaches the cutting edge, and then gradually increases as it approaches the cutting edge. The shape formed by the cutting blade is such that the height of the cutting edge along the axis is higher than the flat portion around the screw through hole in the upper surface.

2. The cutting blade according to claim 1, characterized in that, When observed from a direction perpendicular to the upper surface or the lower surface, the curved cutting edge and the intersecting region in the long side direction of the upper surface or the lower surface are connected by a curved portion.

3. The cutting insert according to claim 2, characterized in that, The curved portion is in an arc shape.

4. The cutting insert according to claim 3, characterized in that, The radius of curvature of the curved portion is smaller than the radius of curvature of the cutting edge.

5. The cutting insert according to any one of claims 1 to 4, characterized in that, The upper surface and the lower surface are axisymmetric shapes centered on the symmetry central axis perpendicular to the reference surface, and are offset from each other in the long side direction at an angle equal to the inclination angle of the end surface.

6. A tool body of a cutting tool, detachably mounted with the cutting blade according to any one of claims 1 to 5, wherein the tool body is characterized by comprising: A mounting surface, which mounts the flat portion around the screw through hole in the upper surface or the lower surface of the cutting blade as a mounting surface; and A restraining surface, which is perpendicular to the mounting surface and abuts against the reference surface of the cutting blade.

7. A cutting tool with replaceable cutting edges, characterized in that, Comprising the tool body according to claim 6.

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