JP2016022572A - Cutting tool, and machining method and machining device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool which is excellent in abrasion resistance, and can suppress deterioration of cutting performance in accordance with abrasion of a cutting blade tip.SOLUTION: An end mill which is a cutting tool has: a cutting blade part 1; and a shank part 2, and comprises: a pair of cutting blades 3 spirally formed at an angle of a helix angle δ: and a pair of chip discharge grooves 4 spirally formed between the cutting blades 3 in the surroundings of the cutting blade part 1. In the cutting blades 3, a flank side from tips of the cutting blades is covered with abrasion resistant coating which is harder than a base material, the base material is exposed on a rake face side from the cutting blade tips, and the cutting blades 3 are set so that a tool angle and/or a tool angle of the cutting blades 3 becomes smaller by progress of abrasion on the rake face side than on the flank face side of the cutting blades 3 by a cutting work.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cutting tool such as a manual tool, a cutting tool, and a drilling tool in which wear resistance is applied to a cutting blade, and a machining method and a machining apparatus using the cutting tool.

When processing carbon fiber reinforced resin composites (hereinafter referred to as “CFRP” (Carbon Fiber Reinforced Plastic)) using cutting tools such as end mills, there are problems such as delamination, fiber fraying, and burr formation. It becomes. Such a problem is a result of advanced wear of the cutting edge of the tool because the carbon fiber contained in CFRP is very hard. As a countermeasure against such wear of the cutting edge, for example, Patent Document 1 describes that a hard coating layer is provided on a scooping surface at least on the groove surface of the other surface excluding the main clearance surface and the margin portion of the drill body. . Patent Document 2 describes a cutting tool in which a rake face of a cutting edge portion is coated with a material having higher wear resistance than the base material of the cutting edge portion. The edge of the cutting edge of the cutting edge of the cutting edge falls off due to wear due to friction with the work material, and the flank and margin base material wears due to friction with the work material, resulting in the maximum cutting edge diameter. The part is retracted in the axial direction, and the cutting edge maximum diameter part and the cutting edge tip in the vicinity of the cutting edge are held so as to be smoothly continuous, and the degradation of cutting performance due to wear of the cutting edge tip is suppressed. Yes.

JP-A-57-184616 JP 2011-104772 A

Among fiber reinforced composite materials, CFRP is lightweight and has high strength and rigidity, and is frequently used for aircraft structural materials. CFRP used for aircraft structural materials has strict requirements regarding quality. For example, there is no burr protruding on the mating surface with other members, and no delamination occurs on the processed surface of CFRP. .

FIG. 7 is an explanatory diagram when cutting is performed on a workpiece made of CFRP using a conventional cutting tool. In the cutting tool, a hard coating layer 201 such as diamond is formed on the entire cutting edge 200 to enhance wear resistance. In FIG. 7, the cross section of the direction orthogonal to the center axis | shaft of a cutting tool is shown, and the blade edge | tip 200 where cutting is performed is partially expanded and shown. As shown in FIG. 7A, the entire cutting edge 200 is uniformly covered with the hard coating layer 201 including the flank face and the rake face. Since the cutting edge 202 is also covered with the hard coating layer 201, the cutting edge 202 has a uniform hardness as a whole. The cutting edge tip 202 is worn by repeating the cutting process. However, since the whole is formed to have a uniform hardness, the wear progresses uniformly throughout the cutting edge tip. 202 becomes rounded as a whole. Due to the shape change due to such wear, the cutting performance of the cutting edge tip 202 is lowered, and burrs, uncut portions, delamination, and the like are generated.

In the techniques described in Patent Documents 1 and 2 described above, the sharp edge of the cutting edge is maintained by making the flank face easy to wear. However, since the flank face is less likely to be frictionally worn with the work material, there is a possibility that sufficient effects cannot be obtained in practical use.

The present invention has been made in view of such problems in the prior art, and an object thereof is to provide a cutting tool that has excellent wear resistance and can suppress a decrease in cutting performance due to wear of the cutting edge tip. And

The cutting tool according to the present invention is a cutting tool in which a cutting blade is formed around and provided with a cutting blade portion, and the cutting blade is covered with a wear-resistant coating whose flank side is harder than the base material from the cutting blade tip. In addition, the base material is exposed on the rake face side from the tip of the cutting edge, and the cutting edge of the cutting edge and / or the cutting edge of the cutting edge is worn more than the flank face by cutting. The blade angle is set to be small. Further, the wear resistant coating is made of a material harder than the base material. Further, the wear resistant coating is formed by heat-treating the base material surface.

The machining method according to the present invention is a cutting method for cutting a workpiece using the cutting tool described above, and the rake face side of the cutting blade of the cutting tool is a flank as the workpiece is cut. The cutting operation is performed while the rake angle of the cutting edge is reduced by the progress of wear compared to the side.

The machining apparatus according to the present invention holds the above-described cutting tool and supports a workpiece that includes at least a part of a fiber reinforced composite material, and a driving unit that rotates around the rotation center axis of the cutting tool. Support means and moving means for relatively moving the drive means and / or the support means so as to cut the cutting tool with respect to the workpiece.

According to the present invention, it has excellent wear resistance by forming a wear-resistant coating harder than the base material on the flank side of the cutting edge up to the tip of the cutting edge, and on the rake face side of the cutting edge. Since the base material is exposed, during cutting, wear on the rake face side proceeds as compared with the flank face on which the wear-resistant coating is formed. For this reason, the cutting edge has a small rake angle, a small cutting edge angle, and maintains a sharp edge. The cutting edge angle is reduced by reducing the cutting edge angle, so that cutting performance is improved and cutting resistance is reduced. And the fall of the cutting performance accompanying abrasion of a cutting-blade front end can be suppressed now, and cutting performance can be maintained over a long period of time.

It is a front view of the end mill concerning one embodiment of the present invention. It is sectional drawing of the AA arrow shown in FIG. FIG. 3 is a partially enlarged view of the cutting edge of the cutting blade portion shown in FIG. 2. It is explanatory drawing in the case of cutting with respect to the workpiece which consists of CFRP using an end mill. It is explanatory drawing regarding the machining method at the time of using the cutting tool which concerns on this invention. It is an external appearance perspective view regarding the machining apparatus using the cutting tool which concerns on this invention. It is explanatory drawing in the case of cutting with respect to the workpiece which consists of CFRP using the conventional cutting tool.

Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

FIG. 1 is a front view of an end mill which is an embodiment of a cutting tool according to the present invention. The end mill of this embodiment has a cutting edge part 1 and a shank part 2. Around the cutting blade portion 1, a pair of cutting blades 3 formed in a spiral shape with a twist angle δ and a pair of chip discharge grooves 4 formed in a spiral shape between the cutting blades 3 are provided.

FIG. 2 is a cross-sectional view taken along line AA in FIG. 1 and orthogonal to the rotation center axis O of the end mill, and FIG. 3 is a partially enlarged view of the cutting edge of the cross-sectional view shown in FIG. The cutting blade portion 1 is provided with a pair of cutting blades 3 so as to be symmetric with respect to the rotation center axis O. The cutting edge 3 is formed with a rake face 5 on the chip discharge groove 4 side, and a cutting edge second flank face 6 and a cutting edge third flank face 7 are formed on the outer peripheral side. The flank surfaces 6 and 7 are covered with a wear resistant coating 8 up to the cutting edge tip 9.

As shown in FIG. 3, the rake angle α is the rotation center axis O side along the rake face by 0.1 mm to 0.2 mm from the cutting edge tip 9 where the rake face 5 and the cutting edge second flank 6 intersect. This is an angle between a straight line formed and averaged by the point group plotted in (1) and a straight line T serving as a reference connecting the cutting edge tip 9 and the rotation center axis O. The rake angle α is set in a range of −5 ° to 45 ° when the counterclockwise rotation with respect to the reference straight line T is a positive angle. Further, the clearance angle β is plotted on the outer peripheral side along the cutting edge second flank 6 by 0.1 mm to 0.2 mm from the cutting edge tip 9 where the rake face 5 and the cutting edge flank 6 intersect. The angle between a straight line formed and averaged by a group of points and a straight line S perpendicular to the straight line T connecting the cutting edge tip 9 and the rotation center axis O. Then, the clearance angle β is set in a range of 0 ° to 45 ° when the clockwise direction is a positive angle with respect to the orthogonal straight line S.

Further, the blade edge angle γ is an angle between the rake face 5 and the second flank face 6 of the cutting edge, and indicates the degree of the sharp edge of the cutting edge tip 9 and is obtained by the following calculation formula. γ = 90− (α + β) The cutting edge angle θ is an angle between the straight line S and the bisector U of the cutting edge angle γ, and the clockwise direction with respect to the straight line S is a positive angle. The cutting edge angle θ is closely related to the shearing force at the time of cutting of the cutting edge, and the shearing force increases as the cutting edge angle θ decreases.

A third cutting edge flank 7 is formed continuously behind the cutting edge second flank 6 in the cutting direction, and the inner angle between the third cutting edge flank 7 and the second cutting edge flank 6 is 180. The angle is set smaller than °.

As the base material of the end mill, a material having characteristics such as wear resistance, heat resistance, fracture resistance, plastic deformation resistance, chemical stability, and thermal conductivity is desirable. For example, high-speed tool steel, cemented carbide, Known materials such as cermet and ceramics can be used. The wear-resistant coating 8 covered on the flank surfaces 6 and 7 is made of a material harder than the base material. For example, diamond (single crystal, sintered), hard carbon such as DLC, titanium hard Examples thereof include materials such as films (TiC, TiAlN, TiN).

The hardness of the material can be compared quantitatively, for example, by measuring the Vickers hardness (HV) of the material, and a material harder than the Vickers hardness of the base material may be selected. For example, when the base material is a cemented carbide material, sintered diamond can be used as the wear-resistant coating. When the base material is high-speed tool steel, a titanium-based hard film (TiAlN) can be used as the wear-resistant film.

The abrasion-resistant coating 8 is desirably set to a thickness that does not affect the cutting performance, and specifically, 5 μm to 50 μm is preferable. And the wear-resistant film is not formed on the rake face 5 side, and the base material is exposed.

As a method for forming the wear-resistant coating 8, the base material is processed to form the cutting edge 1 and then the entire cutting edge 3 including the rake face 5 is hardened such as diamond by a CVD (Chemical Vapor Deposition) method. Apply material coating. Thereafter, the coating formed on the rake face 5 is removed by grinding to expose the base material, so that the wear resistant coating 8 is formed only on the flank faces 6 and 7 side. In addition to this method, after the cutting edge portion 1 is formed, the rake face 5 is masked with a heat-resistant coating agent, and the entire cutting edge 3 is coated with a hard material such as diamond, and then the coating formed on the rake face 5 is applied. By removing by grinding and exposing the base material, the wear-resistant coating 8 can be formed only on the flank surfaces 6 and 7 side.

The abrasion resistant coating 8 can also be formed by heat-treating the base material surface. For example, by performing heat treatment such as induction quenching, flame quenching, and laser quenching on the surface of the base material, it is possible to change the metal structure on the surface of the base material to form a coating with increased hardness. For example, in carbon steel, the metal structure of ferrite, which is a base material, can be surface-treated by heat treatment to change to a martensite or austenite metal structure to form a coating with increased hardness.

The operation when the end mill of this embodiment is used will be described. FIG. 4 is an explanatory diagram when cutting is performed on the work material 30 made of CFRP using an end mill. In FIG. 4, the cross section of the direction orthogonal to the rotation center axis | shaft of an end mill is typically shown, and the part of the cutting blade 3 in which cutting is performed is partially expanded and shown. As shown in FIG. 4A, the end mill has a wear-resistant coating 8 harder than the base material on the flank surfaces 6 and 7 side of the cutting edge 3 up to the cutting edge tip 9. The wear resistant coating 8 is not formed on the surface 5 side, and the base material is exposed.

As the cutting material 30 made of CFRP is repeatedly subjected to cutting with an end mill, wear of the cutting edge 3 proceeds. As shown in FIG. The amount of wear on the surface 5 is larger than that on the flank surfaces 6 and 7 side coated with the wear-resistant coating 8. For this reason, wear proceeds on the rake face 5 so that the rake angle α is increased, the edge angle γ of the cutting edge 3 is reduced, and the sharp edge of the cutting edge tip 9 is held. Further, since the cutting edge angle γ is reduced, the cutting edge angle θ is also reduced, and the cutting performance is improved. Therefore, when the rake angle is increased, the cutting resistance is reduced and the sharp edge is held to improve the cutting performance, and it is possible to suppress the deterioration of the cutting performance due to the wear of the cutting edge tip 9. Further, the flank surfaces 6 and 7 can reduce the amount of wear by the wear-resistant coating 8 and improve the wear resistance of the blade edge 3, and can maintain the cutting performance for a long period of time.

Therefore, even if wear of the cutting edge tip 9 progresses, chipping of the cutting edge portion 1 and burrs and delamination of the work material are surely prevented, and the life of the cutting tool is greatly improved. Stable continuous cutting is possible, and the effect of shortening the working time and the tool cost can be obtained. In the above description, an end mill, which is a cutting tool, is given as an example of a cutting tool. However, the present invention is not limited to an end mill, and a cutting tool having a rake face and a flank face formed on a cutting tool such as a lathe tool or a drill. It can also be applied to tools and drilling tools. The cutting blade of the cutting tool can be provided with a plurality of cutting blades such as four cutting blades and six cutting blades in addition to the two cutting blades described above, and is not particularly limited. Further, the work material capable of exhibiting the above-described effects using the cutting tool of the present invention is not limited to the above-mentioned CFRP, and the work material in which the cutting tool wears with the cutting work. If so, it can be the target.

In addition to the cutting tool, the present invention can also be applied to manual tools such as scissors and knives provided with a cutting edge portion having a rake face and a flank face.

The cutting tool of the present invention is mounted on a known machining apparatus and used for cutting a composite material as a workpiece. The composite material is suitable for cutting a fiber-reinforced composite material, and particularly suitable for a composite material in which fibers are laminated in layers. As the fiber reinforced composite material, in addition to the above-mentioned carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), glass long fiber reinforced plastic (GMT), boron fiber reinforced plastic (BFRP), aramid fiber reinforced plastic (AFRP) , KFRP) and polyethylene fiber reinforced plastic (DFRP). In addition, a workpiece may contain a fiber reinforced composite material in part, and is not specifically limited.

FIG. 5 is an explanatory diagram relating to a machining method when a cutting tool such as an end mill which is an embodiment of the cutting tool according to the present invention is used. FIG. 5A shows a state immediately after the start of cutting, and the cutting edge portion 1 provided on the outer periphery of the cutting tool rotates with respect to a plate-shaped work material 30 (eg, fiber-reinforced composite material). However, it is positioned so that the outer peripheral surface abuts. Next, in FIG. 5B, the cutting tool moves on the XY plane with respect to the work material 30 while rotating around the rotation center axis, and pushes the outer peripheral surface of the cutting edge portion 1 against the work material 30. Cut by touching. Next, in FIG.5 (c), although the abrasion of the blade edge | tip of the cutting blade part 1 progresses during the cutting process of the workpiece 30, since a base material is exposed in the rake face side of a blade edge | tip, an abrasion-resistant film is formed. The wear amount is larger than the formed flank side, so the rake angle at the cutting edge tip increases with wear, the sharp edge at the cutting edge is held, and the cutting resistance is reduced, resulting in reduced cutting performance. Cutting process can be continued while suppressing

FIG. 6 is an external perspective view of a machining apparatus using a cutting tool such as an end mill which is an embodiment of a cutting tool according to the present invention. The machining apparatus 100 includes a moving means including a XYZ three-axis movable mechanism by a ball screw mechanism or a linear motor mechanism and a five-axis mechanism to which a rotation mechanism around the X and Y axes is added. The Z-axis moving mechanism 101 supports the cutting tool 104 attached to the spindle shaft 103 and moves it up and down. As the moving means, a ball screw mechanism or a linear motor mechanism is used. Further, the Z-axis moving mechanism 101 includes a drive source that rotationally drives the spindle shaft 103.

The XY axis moving mechanism 102 moves the installation table to the X axis, the Y axis, or the XY compound axis. As the moving means, a ball screw mechanism or a linear motor mechanism is used. A support tool 106 such as a vise or a restraining jig is disposed on the installation table, and a work material 105 made of a fiber-reinforced composite material or the like is placed and fixed on the support tool 106. The XY axis moving mechanism 102 is driven by a ball screw mechanism or a linear motor mechanism.

Then, cutting is performed while controlling the Z-axis moving mechanism 101 and the XY-axis moving mechanism 102 to rotationally drive the cutting tool 104 with respect to the work material 105. In addition, as the support tool 106, what has the function to pinch | interpose from the thickness direction or surface direction of the cut material 105 may be used. Further, the spindle axis may be arranged on the X axis or the Y axis.

1 ・ ・ Cutting blade part 2 ・ Shank part 3 ・ ・ Cutting edge 4 ・ ・ Chip discharge groove 5 ・ ・ Rake face 6 ・ ・ Cutting edge 2 flank 7 、 ・ Cutting edge 3 flank , 8..Abrasion resistant coating, 9 .... Cutting edge tip, 30 ... Work material, 100 ... Machining device, 101 ... Z axis moving mechanism, 102 ... XY axis moving mechanism, 103 ... Spindle Shaft, 104 ... Drill, 105 ... Workpiece, 106 ... Support tool, 200 ... Cutting edge, 201 ... Hard coating layer, 202 ... Cutting edge tip, ...... Rake angle, ... , Γ ... Edge angle, θ ... Cutting edge angle, δ ... Twist angle

Claims (5)

In a cutting tool having a cutting edge formed around it and provided with a cutting edge portion, the cutting edge is covered with a wear-resistant coating harder than the base material on the flank side from the cutting edge tip and from the cutting edge tip. The base material is exposed on the rake face side, and the cutting edge angle and / or the cutting edge angle of the cutting edge is set smaller as the rake face side of the cutting edge is more worn than the flank face by cutting. Cutting tool being used. The cutting tool according to claim 1, wherein the wear-resistant coating is made of a material harder than the base material. The cutting tool according to claim 1, wherein the wear-resistant coating is formed by heat-treating the base material surface. A cutting method for cutting a workpiece using the cutting tool according to any one of claims 1 to 3, wherein the rake face side of the cutting blade of the cutting tool is a flank as the workpiece is cut. A machining method for performing a cutting operation while reducing a rake angle of the cutting blade by causing wear as compared to the side. A driving means that holds the cutting tool according to any one of claims 1 to 3 and that is driven to rotate about a rotation center axis of the cutting tool, and supports a workpiece that includes at least a part of a fiber-reinforced composite material. A machining apparatus comprising: a support unit; and a moving unit that relatively moves the driving unit and / or the support unit so as to cut the cutting tool with respect to the workpiece.

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