Laser quenching method

Abstract

To prevent deformation from occurring in a quenched part of a push-cutting blade due to laser quenching.SOLUTION: A laser quenching method according to the invention performs laser quenching on a push-cutting blade 3 formed by roughening for roughening a blade edge and finishing for finishing the roughly formed blade edge. The method includes: irradiating, with a laser beam from above, a blade edge of a roughly formed blade 32 whose blade edge is roughly formed by roughening, so as to perform laser quenching thereon; and then, performing finishing work for finishing the blade edge to form the push-cutting blade 3.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a laser hardening method suitable for hardening a cutting blade of a flexible die having a cutting blade formed on a magnetic material, a die-cut roll having a cutting blade formed directly on the roll surface, and the like. [Background technology]

[0002] 2. Description of the Related Art A laser hardening method is known in which a workpiece is irradiated with laser light to locally heat it and harden it by self-cooling (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-63551 A Summary of the Invention [Problem to be solved by the invention]

[0004] The laser hardening method has the advantage that heat can be concentrated locally, so the effect of the heat on the workpiece is small and deformation of the workpiece is unlikely to occur.

[0005] However, when the workpiece is a thin part, for example when laser hardening the sharp tip of a cutting blade of a flexible die or die-cut roll, there is little room for the heat generated by the irradiation of the laser light to escape, so self-cooling cannot be performed efficiently, and deformation is likely to occur at the tip of the blade.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to prevent deformation from occurring in the hardened portion of the cutting blade. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention is configured as follows.

[0008] (1) A laser hardening method according to the present invention is a laser hardening method for performing laser hardening by irradiating a cutting edge of a cutting blade, the cutting edge of which is formed by cutting, with a laser beam, The cutting process includes a rough process for roughly forming a cutting edge, and a finish process for finishing the roughly formed cutting edge. The cutting edge roughly formed by the rough process is laser hardened by irradiating the laser light, and the laser-hardened cutting edge is finished by the finish process.

[0009] According to the laser hardening method of the present invention, the cutting edge of the cutting blade formed by cutting is irradiated with laser light before finishing to sharpen the cutting edge, i.e., before the cutting edge is roughly formed by rough processing. The roughly formed cutting edge has a wider cutting edge than the cutting edge that is sharpened by finishing. This allows the heat generated by the irradiation of the laser light to be efficiently cooled by itself, and prevents the tip of the cutting edge irradiated with the laser light from being deformed.

[0010] (2) In a preferred embodiment of the present invention, a cutting tool is attached to a spindle of a machine tool to perform the cutting process, and a laser head is attached to the spindle of the machine tool to perform the laser hardening.

[0011] According to this embodiment, since the cutting tool is attached to the spindle of the machine tool to perform cutting, and the laser head is attached to the spindle to perform laser hardening, cutting and laser hardening can be performed on the same machine tool. This makes it possible to manufacture the cutting blade more efficiently than when cutting is performed on the machine tool and laser hardening is performed on a laser hardening device separate from the machine tool.

[0012] (3) In another embodiment of the present invention, the tip of the cutting edge roughly machined by the rough machining has a flat surface of a very small width, and the tip of the cutting edge finished by the finish machining has the flat surface eliminated and is sharp.

[0013] According to this embodiment, the cutting edge after rough machining, which is hardened by irradiating a laser beam, has a very small flat surface at the tip, and therefore can efficiently self-cool the heat generated by the irradiation of the laser beam, compared to a cutting edge after finish machining, which has no flat surface and has a sharp tip. This makes it possible to prevent the tip of the cutting edge irradiated with the laser beam from being deformed.

[0014] (4) In yet another embodiment of the present invention, the laser hardening involves irradiating the tip of the cutting edge, which protrudes upward and is roughly formed by the rough machining, from above with the laser light to harden the tip of the cutting blade.

[0015] According to this embodiment, the tip of the cutting edge that protrudes upward is irradiated with laser light from above, so that a surface-hardened layer can be formed on the tip of the cutting edge of the cutting blade.

[0016] (5) In one embodiment of the present invention, the cutting blade is provided on a flexible die.

[0017] According to this embodiment, the cutting blade is provided on a flexible die which is mounted so as to be wrapped around a magnetic cylinder.

[0018] Since the surface hardened layer formed by laser hardening can be formed only on the tip of the cutting blade, when the flexible die is bent and wrapped around the magnet cylinder, the tip of the cutting blade will not be damaged by bending stress. Effect of the Invention

[0019] Thus, according to the present invention, the laser light is irradiated onto the cutting edge of the cutting blade, which is roughly formed by rough machining. Therefore, compared to irradiating a cutting edge that has been sharpened, the heat generated by the irradiation of the laser light can be cooled down more efficiently, and deformation of the tip of the cutting edge can be prevented. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic perspective view showing a state in which a flexible die is attached to a magnet cylinder. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the cutting blade taken along line AA in FIG. [Diagram 3] FIG. 3 is a schematic front view of an NC machine tool that performs laser hardening. [Figure 4] FIG. 4 is a schematic front view of an NC machine tool that performs cutting processing. [Diagram 5] FIG. 5 is a schematic plan view of a workpiece to be machined by an NC machine tool. [Figure 6] FIG. 6 is an enlarged cross-sectional view of the protrusion taken along line BB in FIG. [Figure 7] FIG. 7 is a cross-sectional view of a protrusion to explain cutting processing of a workpiece, where (a) is a cross-sectional view of the protrusion before rough processing, (b) is a cross-sectional view of the rough processing blade after rough processing, and (c) is a cross-sectional view of the cutting blade after finish processing. [Figure 8] FIG. 8 is a schematic cross-sectional view illustrating irradiation of laser light onto the rough-cutting blade after rough-cutting. [Figure 9] Figure 9 is a schematic cross-sectional view for explaining deformation caused by irradiation of laser light onto the cutting blade after finishing processing, where Figure 9(a) is a schematic cross-sectional view showing the irradiation of laser light onto the cutting blade, and Figure 9(b) is a schematic cross-sectional view showing the deformation after irradiation of laser light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0022] The laser hardening method of this embodiment involves irradiating the cutting edge of the cutting blade with a laser beam to perform laser hardening. This laser hardening increases the hardness of the cutting edge of the cutting blade, reduces wear, and extends the life of the cutting blade.

[0023] In this embodiment, the present invention will be described by applying it to a cutting blade provided on a flexible die used for punching or half-cutting a sheet to be processed, such as a label, along a predetermined cutting line.

[0024] FIG. 1 is a schematic perspective view showing a state in which a flexible die 1 is attached to a magnet cylinder 4 so as to be wound around the magnet cylinder 4, and FIG. 2 is an enlarged cross-sectional view of a cutting blade 3 taken along line AA in FIG.

[0025] The flexible die 1 has a plurality of cutting blades 3 formed on one side of a flexible base 2 made of a ferromagnetic material such as carbon steel, along cutting lines, which in this example are rectangular ring-shaped cutting lines.

[0026] This flexible die 1 is attached by wrapping it around a magnet cylinder 4, as shown in Figure 1, and the sheet to be processed, such as a label, is passed between the magnet cylinder 4 around which the flexible die 1 is wrapped and an anvil roll (receiving cylinder) (not shown), and punching and half-cutting are performed along the cutting line.

[0027] The cutting blade 3 of the flexible die 1 is manufactured as follows. First, a rectangular cross-section protrusion is formed along the cutting line on one side of a flexible base made of a thin carbon steel plate or the like by etching. Then, the protrusion is cut by an NC machine tool described later, and the laser hardening of this embodiment is performed to manufacture the flexible base.

[0028] That is, the cutting blade 3 of the flexible die 1 is manufactured by using a flexible base as a workpiece, on one side of which a rectangular cross-sectional protrusion is formed by etching, and then performing cutting processing on this workpiece using an NC machine tool and laser hardening.

[0029] The cutting process involves head machining, in which the upper surface of the rectangular cross-section protrusion is cut to the desired height, rough machining, in which a tapered end mill is used to roughly machine the cutting edge, and finishing machining, in which a tapered end mill with a larger taper angle than the rough machining process is used to finish the cutting edge.

[0030] FIG. 3 is a schematic front view of an NC machine tool used to manufacture the cutting blade 3 of the flexible die 1 described above.

[0031] This NC machine tool 5 is a vertical machining center, and when performing laser hardening, a laser head 7 is attached to the spindle 6. When performing cutting, a holder 9 that holds a cutting tool 8 such as a tapered end mill is attached to the spindle 6 as shown in FIG.

[0032] In this way, by attaching the laser head 7 or cutting tool 8 to the spindle 6 of the NC machine tool 5, it is possible to perform laser hardening or cutting. This eliminates the need to move the workpiece 11 between the laser hardening device and the machine tool to perform laser hardening and cutting, as is done in the case of performing hardening with a laser hardening device and then cutting with a machine tool separate from the laser hardening device, thereby improving work efficiency.

[0033] The NC machine tool 5 is equipped with a contact-type height gauge 10 for measuring the height of the top surface of the workpiece 11 to be machined, i.e., a flexible base having protrusions formed on one side by etching, a table 12 on which a vice 14 for holding the workpiece 11 is attached, and a tool length measuring device 13 for contacting the tip of a cutting tool 8 attached to the spindle 6 to measure the tool length.

[0034] This NC machine tool 5 performs machining by moving a spindle 6 and a table 12 in three axial directions, namely, X-, Y-, and Z-axes, which are perpendicular to each other.

[0035] 5 is a schematic plan view of the workpiece 11 machined by the NC machine tool 5. As described above, this workpiece 11 is the flexible base 2 with the protrusions 31 formed on one side by etching. This workpiece 11 is cut and laser hardened by the NC machine tool 5 to form the flexible die 1 equipped with the cutting blade 3 shown in FIGS. 1 and 2.

[0036] This workpiece 11 is formed by forming a plurality of rectangular cross-section protrusions 31 in the shape of a rectangular ring along cutting lines by etching on one side of a flexible base 2 made of a thin carbon steel plate having a thickness of, for example, 0.440 mm.

[0037] In this example, a total of 12 protrusions 31 extending in a rectangular ring shape along the cutting line are formed in two rows in the horizontal direction (left and right direction in FIG. 5) and six columns in the vertical direction (up and down direction in FIG. 5).

[0038] Fig. 6 is an enlarged cross-sectional view of the protrusion 31 taken along line BB in Fig. 5. As shown in Fig. 6, the cross-sectional shape of the protrusion 31 formed on one side of the flexible base 2 is rectangular. The upper surface of this rectangular cross-sectional protrusion 31 is head-machined by cutting to a desired height using a radius end mill as a cutting tool 8 by an NC machine tool 5.

[0039] Thereafter, rough machining and finishing, which are processes for forming a cutting edge, are performed by the NC machine tool 5 to machine the cutting edge into a desired shape.

[0040] In the laser hardening method of this embodiment, rough machining is performed, followed by laser hardening, and then finish machining.

[0041] FIG. 7 is a schematic cross-sectional view showing how the cross-sectional shape of the ridges 31, whose upper surfaces have been cut to a desired height, changes as a result of rough machining and finishing.

[0042] Figure 1(a) shows the protrusion 31 whose upper surface has been cut to the desired height by head machining, i.e., the protrusion 31 before rough machining, Figure 1(b) shows the rough machining blade 32, which is the blade after rough machining, and Figure 1(c) shows the cutting blade 3 after finish machining.

[0043] In the rough machining, a tapered end mill is used to cut one side surface of the protrusion 31 having a rectangular cross section as shown in FIG. 7(a), and then the other side surface is cut.

[0044] By this rough machining, as shown in Figure 7(b), a rough machining blade 32 is formed having a flat cutting edge surface 32a of a very small width W, first inclined side surfaces 32b, 32b continuing on both sides of the flat cutting edge surface 32a, base flat surfaces 32c, 32c respectively continuing on each of the first inclined side surfaces 32b, 32b, and base side surfaces 32d, 32d respectively continuing on each of the base flat surfaces 32c, 32c.

[0045] In the rough processing of this embodiment, the cutting edge flat surface 32a is processed so that the minute width W is, for example, about 0.03 mm. This cutting edge flat surface 32a disappears by finish processing as described later, and the cutting edge tip 3a of the cutting blade 3 after finish processing shown in FIG. 7(c) becomes sharp.

[0046] In this manner, in the finish machining, the blade tip flat surface 32a of the minute width W at the tip of the rough machining blade 32 is eliminated to form a sharp blade tip 3a. For this reason, in the rough machining, the blade height H2 after the rough machining shown in Fig. 7(b) is processed so as to be about 0.02 mm higher than the blade height H1 of the cutting blade 3 after the finish machining shown in Fig. 7(c).

[0047] In this embodiment, in the finish machining, the cutting edge height H1 is machined to 0.400 mm, and in the rough machining, the cutting edge height H2 is machined to 0.420 mm.

[0048] The minute width W of the cutting edge tip 32a of the rough cutting edge 32 is preferably 0.01 mm or more so that the cutting edge tip is not deformed by laser hardening, and is preferably 0.05 mm or less so that the cutting edge tip can be sharpened by finish processing.

[0049] The workpiece 11 after rough machining, on which the rough machining blade 32 is formed, is subjected to laser hardening as described later.

[0050] For the rough cutting blade 32 shown in FIG. 7(b) after laser hardening, a taper end mill having a larger taper angle than that for rough cutting is used to cut one side and then the other side.

[0051] As a result of this finishing process, as shown in Figure 7 (c), the flat cutting edge surface 32a disappears, and a sharp cutting edge tip 3a and second inclined side surfaces 3b, 3b connected to both sides of it are formed, and the first inclined side surfaces 32b, 32b, base flat surfaces 32c, 32c, and base side surfaces 32d, 32d similar to those of the rough cutting blade 32 remain to form the cutting blade 3.

[0052] Next, laser hardening of the rough cutting edge 32 after rough cutting shown in FIG. 7(b) will be described.

[0053] After the rough machining is completed, the laser head 7 shown in FIG. 3 is attached in place of the taper end mill, which is the cutting tool 8 attached to the spindle 6 of the NC machine tool 5.

[0054] The laser head 7 collects the laser light transmitted from the laser oscillator and irradiates it onto the roughly machined flexible base 2 serving as the workpiece 11. In this embodiment, a YAG laser oscillator is used as the laser oscillator.

[0055] An example of the setting conditions for laser hardening in this embodiment is shown in Table 1 below.

[0056] [Table 1] As shown in Table 1, the output of the laser oscillator is 0.18 J, the repetition frequency is 20 Hz, the pulse width is 1 ms, the laser spot diameter is φ0.45 mm, and the feed speed of the table 12 is 200 mm / min.

[0057] As shown typically in FIG. 8, the laser light L is irradiated onto the flexible base 2 on which the rough cutting blade 32 is formed, toward the tip of the cutting edge of the rough cutting blade 32 protruding upward from the upper laser head 7.

[0058] In the cutting blade 3 after finishing shown in Figure 7(c) above, the cutting edge tip 3a is sharp, whereas in the rough cutting blade 32 after rough cutting shown in Figure 7(b), the cutting edge tip has a flat cutting edge surface 32a with a minute width W of approximately 0.03 mm.

[0059] In the laser hardening method of this embodiment, laser light is irradiated onto the rough cutting blade 32, which has a cutting edge flat surface 32a with a minute width W formed at the tip of the cutting edge, so that the heat generated by the irradiation of the laser light can be efficiently cooled by itself, and deformation of the cutting edge can be prevented.

[0060] In contrast, as shown in Fig. 9(a), when laser hardening is performed on the cutting blade 3 after finishing after the cutting process, the cutting blade 3 has a sharp cutting edge 3a. As a result, there is little room for the heat generated by the irradiation of the laser light L to escape, and self-cooling cannot be performed efficiently, resulting in deformation of the cutting edge, as shown in Fig. 9(b). Note that the deformation is exaggerated in Fig. 9(b) to make it easier to understand.

[0061] After the laser hardening according to this embodiment was performed, the hardness of the cutter blade 3 manufactured by performing finish processing was measured.

[0062] At a position 0.03 mm from the tip of the cutting edge, the measured Vickers hardness was about 700 HV, which is equivalent to about 60 in HRC (Rockwell) equivalent.

[0063] At a position 0.1 mm from the tip of the cutting edge, the measured Vickers hardness was about 450 HV, which is equivalent to about 45 in HRC (Rockwell) terms.

[0064] As shown above, it can be seen that a surface-hardened layer is formed by laser hardening up to approximately 0.03 mm from the tip of the cutting edge.

[0065] In the laser hardening method of this embodiment, the laser light L is irradiated from above onto the tip of the cutting edge of the rough cutting blade 32, so that a surface-hardened layer is formed at the tip of the cutting edge of the rough cutting blade 32, and the base of the rough cutting blade 32 and the flexible base 2 are not hardened.

[0066] Therefore, when the flexible base 2 on which the cutting blade 3 is formed is bent and attached by wrapping it around the magnetic cylinder 4 as shown in Figure 1 above, the surface hardened layer at the tip of the cutting blade 3 is not damaged and the cutting blade can be attached without any problems.

[0067] In the above embodiment, the present invention is described as being applied to a flexible die 1 in which a cutting blade 3 is formed on a flexible base 2, but the present invention is not limited to flexible dies and can be similarly applied to a die-cut roll in which a cutting blade is formed directly on the surface of the roll.

[0068] In laser hardening of the cutting blade of a die-cut roll, hardening can be performed deeply, not just at the tip of the cutting blade as in the case of a flexible die. [Explanation of symbols]

[0069] 1 Flexible Die 2 Flexible Base 3 Push-cutting blade 5 NC machine tools 7 Laser Head 8 cutting tools 11 Work 31 protrusion

Claims

1. A laser hardening method for performing laser hardening by irradiating a cutting edge of a cutting blade whose cutting edge is formed by cutting, comprising the steps of: The cutting process includes a roughing process for roughly forming a cutting edge and a finishing process for finishing the roughly formed cutting edge, The cutting edge roughly formed by the rough processing is laser-hardened by irradiating the laser light, and the laser-hardened cutting edge is finished by the finish processing. Laser hardening method.

2. a cutting tool is attached to a spindle of a machine tool to perform the cutting process; and a laser head is attached to the spindle of the machine tool to perform the laser hardening. The laser hardening method according to claim 1.

3. The tip of the cutting edge roughly machined by the rough machining has a flat surface of a minute width, The tip of the cutting edge finished by the finishing process is sharpened by removing the flat surface. The laser hardening method according to claim 1.

4. In the laser hardening, the tip of the cutting edge that protrudes upward and is roughly formed by the rough processing is irradiated with the laser light from above to harden the tip of the cutting edge. The laser hardening method according to claim 1.

5. The cutting blade is a cutting blade provided on a flexible die.

5. The laser hardening method according to claim 1.

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