Cutting methods

Abstract

A cutting processing method in which a tool in which a corner part is formed by a flank surface and a rake surface is displaced toward a prescribed processing direction relative to an article being processed while being brought into contact with the surface of the article being processed, as a result of which the surface of the article being processed is cut to form a processed surface, the method comprising a groove formation procedure in which a plurality of grooves each extending along a direction intersecting the processing direction are formed at intervals in the processing direction in a region of the surface of the article being processed that is on the downstream side in the processing direction.

Description

Technical Field

[0001] The present invention relates to a cutting method for cutting the surface of a workpiece to form a machined surface.

Background Art

[0002] When cutting a workpiece, when the tool is brought into contact with the workpiece and displaced, the machining resistance associated with this displacement causes problems such as tool wear and partial defects. This problem becomes more prominent for difficult-to-cut materials that are difficult to machine.

[0003] Therefore, various techniques for reducing the machining resistance during cutting have been proposed. For example, there is a technique of irradiating a laser in advance in the region where the tool contacts the workpiece, thereby heating and reducing the strength of the region where the tool contacts immediately before contact (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since this technique reduces the strength of the workpiece by heating with a laser, it is necessary to perform machining immediately after heating so that the region irradiated with the laser remains sufficiently heated and contacts the tool. There is a problem that the degree of freedom as a machining method is not necessarily high.

[0006] The present invention has been made to solve such problems, and its object is to provide a technique for reducing machining resistance while increasing the degree of freedom as a machining method. [Means for solving the problem]

[0007] The first phase for solving the above problem is a cutting method for forming a machined surface by cutting the surface of a workpiece by displacing a tool, which has a corner formed by a flank face and a rake face, in a predetermined machining direction relative to the workpiece while in contact with the workpiece surface, and comprising a groove forming procedure for forming a plurality of grooves extending in a direction intersecting the machining direction, at intervals in the machining direction, in a region of the surface of the workpiece that is downstream in the machining direction. Furthermore, this phase may also be as shown in the second phase below. In the second phase, in the groove forming procedure, assuming a "shear surface" from the surface of the workpiece to the tip of the corner in a cross-sectional view intersecting the direction in which the corner extends, the grooves are formed at intervals wider than the length L of this "shear surface".

[0008] In the cutting method described above, multiple grooves are formed at intervals along directions intersecting the cutting direction on the surface of the workpiece, in the region downstream of the cutting direction by the tool.

[0009] In the process of cutting a workpiece to form a machined surface, a "shear surface" is formed from the surface of the cutting layer to the tip of the corner, in a cross-sectional view that intersects with the direction in which the corner of the tool extends, as the boundary between the cutting layer that is cut at the corner in contact with the workpiece and the chips cut from there.

[0010] This "shear surface" is inclined downstream in the machining direction, starting from the tip of the corner, and the machining resistance when cutting chips from the workpiece layer changes depending on the length of this shear surface. In this regard, as shown in the above-mentioned curve, if a groove is formed on the downstream side in the machining direction, the closer the corner approaches the groove, the shorter the inclination and formation of the shear surface becomes due to the groove, thus reducing the machining resistance, especially near the groove.

[0011] However, if the number of grooves is increased and the spacing between them becomes too narrow, the area between the grooves will be pushed by the corners and tilt downstream. This can hinder the displacement of the corners, potentially leading to an increase in machining resistance.

[0012] The applicant, focusing on the relationship between the spacing of such grooves and machining resistance, has devised a method to reduce machining resistance and has found that the groove spacing shown on the curved surface is suitable for reducing machining resistance. Therefore, the machining method used to cut the curved surface can effectively reduce machining resistance.

[0013] Here, the reduction in machining resistance is brought about by the structural characteristic of grooves formed at predetermined intervals, and unlike the reduction in strength due to heating, which is a characteristic that changes easily over time, it is not necessarily required to perform machining immediately after forming the grooves, thus offering a high degree of flexibility in the machining method. In this way, the cutting method for the above-mentioned surface can reduce machining resistance while increasing the degree of flexibility in the machining method. [Brief explanation of the drawing]

[0014] [Figure 1] Side cross-sectional view of a key part showing the process of the cutting method in this disclosure. [Figure 2] Flowchart illustrating the procedure for the cutting method described herein. [Figure 3] Enlarged side cross-sectional view of a key part showing the process of the cutting method in this disclosure. [Modes for carrying out the invention]

[0015] The following describes a machining method for forming a machined surface by cutting the surface of a workpiece, with reference to the drawings.

[0016] (1) Procedure for cutting process As shown in Figure 1, the cutting method of this embodiment involves bringing a tool 10, which has a corner 15 formed by a flank 11 and a rake face 13, into contact with the surface of the workpiece 20 and displacing it relative to the workpiece 20 in a predetermined cutting direction (see arrow in the same figure), thereby cutting the surface of the workpiece 20 and forming a machined surface 21. The tool 10 has a rake angle of 0 to 20°.

[0017] In this cutting method, as shown in Figure 2, a displacement procedure is first performed (s110). Here, the tool 10 is brought into contact with the surface of the workpiece 20, and then displacement in the machining direction relative to the workpiece 20 is initiated. In this embodiment, after the tool 10 is displaced until it contacts the surface of the workpiece 20, the workpiece 20 is displaced relative to the tool 10. According to this displacement, the surface of the workpiece 20 is cut to form a machined surface 21.

[0018] The workpiece 20 is configured to be displaceable in the machining direction relative to the tool 10 by a displacement mechanism (not shown). In this embodiment, the displacement speed is configured to be selectable from a range of 50 to 300 m / min.

[0019] Next, the groove formation procedure is carried out (s120). Here, a laser (more specifically, a pulsed laser) is repeatedly irradiated onto the region 23 on the surface of the workpiece 20 that is downstream in the processing direction (the region where the corner portion 15 will be located) through a slit 110 that extends in a direction intersecting the processing direction (the direction from back to front in the plane of the paper in Figure 1; the same applies hereafter), thereby forming multiple groove portions 30 extending in this direction, spaced apart in the processing direction. Each groove portion 30 is formed as a single groove extending over a certain length in a direction intersecting the processing direction.

[0020] Here, a groove portion 30 with a depth of 20 to 40 μm and a width of 20 to 200 μm is formed. As a specific example, depending on the materials of the tool 10 and the workpiece 20, a laser with a pulse width of 7 μs, an output of 2.0 to 3.0 W, a wavelength of 355 nm, and a frequency of 15 kHz is irradiated perpendicularly to the surface of the workpiece 20.

[0021] The laser is irradiated by an irradiation unit 100. This irradiation unit 100 includes an oscillator that outputs a pulsed laser, a vibration regulator that adjusts the order of the laser's frequency, an attenuator (ATT) that adjusts the output of the laser, a beam expander (EXP) for adjusting the diameter of the laser, etc. The laser passing through these is configured to be output via an optical lens and the slit 110 described above, and the laser is irradiated with its optical axis directed in a predetermined direction.

[0022] The laser is irradiated at a period (for example, 0.04 to 2 ms) determined according to the displacement speed by the displacement procedure and the interval at which the groove portion 30 is to be formed.

[0023] Also, the groove portions 30 are formed at intervals P (>L) wider than the length L of the shear cross-section 29. This shear cross-section 29 is formed as the boundary between a cutting target layer 25 that will be cut at the corner 15 in contact with the workpiece 20 and chips 27 cut at the corner 15 in that state, and is a surface extending from the surface of the cutting target layer 25 to the tip of the corner 15 in a cross-sectional view intersecting the direction in which the corner 15 extends. As a specific example, the groove portions 30 are formed at an interval of 0.2 to 1.5 mm.

[0024] Furthermore, the length L of the shear surface 29 is defined by the following formula, as shown in Figure 3, based on the thickness d of the cutting layer 25, the shear angle φ between the machined surface 21 and the shear surface 29, the rake angle α between the rake face 13 of the corner 15 and a plane perpendicular to the machined surface 21, and the average rake surface friction coefficient μ (=F / N) defined by the frictional force F and the perpendicular force N acting on the rake face 13. Here, the average rake surface friction coefficient μ is a value of 0.25 or less, determined based on the friction coefficient (0.25~0.4) of the materials of the workpiece 20 and the tool 10, and the machining conditions determined by the cutting speed (the relative displacement speed of the tool 10 with respect to the workpiece 20) and the degree of smoothness of the surface of the tool 10. In this embodiment, the machining conditions are adjusted so that the average rake face friction coefficient μ is 0.1, based on the friction coefficients of 0.25 to 0.4 of the iron used as the workpiece 20 and the cemented carbide used as the material for the tool 10.

[0025]

number

[0026] (2) Variant Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited in any way to the above embodiments and can take various forms as long as they fall within the technical scope of the present invention.

[0027] For example, in the above embodiment, the displacement procedure is illustrated in which the workpiece 20 is displaced relative to the tool 10. However, the displacement procedure may also involve displacing the tool 10 relative to the workpiece 20.

[0028] Furthermore, in the above embodiment, an example was given in which the groove formation procedure is performed sequentially at the same timing as the displacement procedure. However, the groove formation procedure can be performed before the displacement procedure, and does not necessarily have to be performed at the same time.

[0029] Furthermore, in the above embodiment, an example was given in which each groove 30 is formed as a single groove extending in a direction intersecting the machining direction. However, each groove 30 may be a configuration in which multiple holes or grooves are arranged in a line over a certain length in a direction intersecting the machining direction. In this case, in the groove formation procedure, the groove 30 is formed by continuously or intermittently irradiating with a laser while displacing the laser irradiation area along the direction intersecting the machining direction.

[0030] Furthermore, although the above embodiment illustrates a tool 10 with a single rake angle, a tool with a two-stage rake angle shape may also be used as the tool 10.

[0031] Furthermore, in the above embodiment, an example was shown in which, in the groove forming procedure, a laser is irradiated onto the surface of the workpiece 20 through the slit 110 to form grooves extending in a direction intersecting the processing direction. However, instead of the slit 110, a lens that can linearly spread the laser along a direction intersecting the processing direction may be used.

[0032] Furthermore, in the above embodiment, an example was shown in which, in the groove forming procedure, a groove extending in a direction intersecting the processing direction is formed by irradiating the surface of the workpiece 20 through the slit 110 with a laser. However, in the groove forming procedure, a groove extending in a direction intersecting the processing direction may also be formed by repeatedly scanning the surface of the workpiece 20 with a laser along a direction intersecting the processing direction (the front-back direction of the paper in Figure 1; the same applies hereinafter). In this case, it is preferable to provide a displacement mechanism that allows the irradiation unit 100 to be displaced in two directions intersecting the optical axis of the laser.

[0033] (3) Effects In the cutting method of the above embodiment, a plurality of grooves 30 extending in directions intersecting the cutting direction are formed at intervals in the region 23 on the surface of the workpiece 20 that is downstream of the cutting direction by the tool 10.

[0034] In the process of cutting the workpiece 20 to form the machined surface 21, a shear surface 29 is formed from the surface of the cutting layer 25 to the tip of the corner 15, in a cross-sectional view intersecting the direction in which the corner 15 extends on the tool 10, as the boundary between the cutting layer 25 that is cut at the corner 15 in contact with the workpiece 20 and the chips cut from there.

[0035] The shear surface 29 is inclined downstream in the machining direction, starting from the tip of the corner 15. However, there is a concern that the longer this surface becomes, the greater the machining resistance when cutting chips 27 from the workpiece layer 25. In this regard, as in the above embodiment, if a groove 30 is formed on the downstream side in the machining direction, the closer the corner 15 gets to the groove 30, the shorter the inclination and formation of the shear surface 29 becomes due to the groove 30, thus reducing machining resistance, especially near the groove 30.

[0036] However, if the number of grooves 30 is increased and the spacing between them becomes too narrow, the area between the grooves 30 will be pushed by the corners 15 and tilt downstream. This could hinder the displacement of the corners 15, potentially leading to an increase in machining resistance.

[0037] The applicant, focusing on the relationship between the spacing of the grooves 30 and the machining resistance, has devised a method to reduce machining resistance and has found that a spacing wider than the length L of the shear surface 29 is suitable for reducing machining resistance. Therefore, the above cutting method can effectively reduce machining resistance.

[0038] Here, the reduction in machining resistance is brought about by the structural feature of grooves 30 formed at predetermined intervals, and unlike the reduction in strength due to heating, which is a feature that changes easily over time, it is not necessarily required to perform machining immediately after forming the grooves 30, thus offering a high degree of flexibility in the machining method. In this way, the above cutting method can reduce machining resistance while increasing the degree of flexibility in the machining method. [Explanation of symbols]

[0039] 10...Tool, 11...Flap face, 13...Rake face, 15...Corner, 20...Workpiece, 21...Machined surface, 23...Area, 25...Cutting layer, 29...Cross section, 30...Groove, 100...Irradiation area, 110...Slit.

Claims

1. A cutting method for forming a machined surface by cutting the surface of a workpiece by displacing a tool, which has a corner formed by a flank and a rake face, in a predetermined machining direction relative to the workpiece while in contact with the surface of the workpiece, The process includes a groove forming procedure in which, on the surface of the workpiece, in a region downstream of the processing direction, a plurality of grooves extending in a direction intersecting the processing direction are formed at intervals in the processing direction, wherein the grooves are formed in the region downstream of the processing direction. In the groove forming procedure described above, assuming a "shear surface" extending from the surface of the cutting layer to the tip of the corner, in a cross-sectional view intersecting the direction in which the corner extends, the grooves are formed at intervals P (>L) wider than the length L of this "shear surface". The length L of the shear surface is defined by the following formula, which is based on the thickness d of the workpiece layer, the shear angle φ between the machined surface and the shear surface, the rake angle α between the rake face of the corner and a plane perpendicular to the machined surface, and the average rake surface friction coefficient μ, which is smaller than the friction coefficient of the workpiece and the tool material. The average friction coefficient μ of the rake face is a value of 0.25 or less, determined based on the friction coefficient of the tool material and the machining conditions. Cutting method. [Number 0001]

2. In the groove forming procedure, the groove is formed by continuously or intermittently irradiating the laser while displacing the laser irradiation area along a direction intersecting the processing direction. The cutting method according to claim 1.

3. In the groove forming procedure, the groove is formed by irradiation with a pulsed laser. The cutting method according to claim 2.

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