Coiling machine and coil spring manufacturing method

Abstract

To suppress spatter when cutting the wire that forms the coil spring. [Solution] A coiling machine according to one embodiment includes a spiral forming unit that forms a wire into a spiral, a laser heater that heats the wire by irradiating the wire formed into a spiral by the spiral forming unit with laser light, and a cutter that cuts the portion of the wire heated by the irradiation of the laser light. Furthermore, the input energy per unit area E [J / cm] by irradiating the portion of the wire with the laser light is calculated. 2 and the time T [s] from the irradiation of the laser light to the cutting by the cutter satisfy the relationship ET×800<4048.

Description

[Technical Field]

[0001] The present invention relates to a coiling machine used in manufacturing a coil spring and a method for manufacturing a coil spring. [Background technology]

[0002] In manufacturing a coil spring, a wire is formed into a spiral shape and then cut by a cutter at a position that will become the end of the coil spring. As a configuration of the cutter, for example, one that includes a mandrel that supports the inner peripheral surface of the wire to be formed into a spiral shape and a cutter that applies an impact to the wire supported by the mandrel to cut the wire.

[0003] Also, in order to facilitate cutting of the wire, a method has been proposed in which a part of the wire is softened by laser heating before cutting (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7066880 Summary of the Invention [Problem to be solved by the invention]

[0005] When laser heating as described above is performed before cutting, if the heated part is impacted by the cutter, a phenomenon in which molten metal particles scatter (spatter) may occur. Such spatter can cause contamination of the coil spring and the coiling machine.

[0006] Therefore, an object of the present invention is to provide a coiling machine and a method for manufacturing a coil spring that can suppress spatter during cutting. [Means for solving the problem]

[0007] The coiling machine according to one embodiment includes: Made of metal, the material used for coil springs a spiral forming unit for forming a wire into a spiral shape; and a wire formed into a spiral shape by the spiral forming unit, the wire being heated by irradiating the wire with a laser beam. and forming a heated portion in the wire, the heated portion having an irradiation area including a molten pool, a first softened area located around the irradiation area and including austenite, and a second softened area located around the first softened area and including martensite. a laser heater; The wire is formed into a spiral shape by applying an impact to the heated portion using a mandrel that supports the inner peripheral surface of the wire and a cutter that projects from the end of the mandrel and moves downward toward the outer peripheral surface of the wire. The above-mentioned Ya and a cutter for cutting the wire. heating The input energy E [J / cm2] per unit area by irradiating the part with the laser light, and the irradiation of the laser light has stopped from The cutter contacts the wire. The time T [s] until the This suppresses spattering of metal particles from the heated area when the cutter impacts the wire. .

[0008] A method for manufacturing a coil spring according to one embodiment includes the steps of: Made of metal, the material used for coil springs The wire is formed into a spiral shape hand , The wire is formed with a heated region having an irradiation region including a molten pool, a first softened region located around the irradiation region and including austenite, and a second softened region located around the first softened region and including martensite, and the wire is formed into a spiral shape using a mandrel that supports the inner circumferential surface of the wire, and a cutter that protrudes from the end of the mandrel and descends toward the outer circumferential surface of the wire, and the cutter impacts the heated region. The above-mentioned Ya Furthermore, the wire is cut. heating The input energy E [J / cm2] per unit area by irradiating the part with the laser light, and the irradiation of the laser light has stopped from The cutter contacts the wire. The time T [s] until the This suppresses spattering of metal particles from the heated area when the cutter impacts the wire. . [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a coiling machine and a method for manufacturing a coil spring that can suppress spatter during cutting. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view showing a main part of a coiling machine according to one embodiment. [Figure 2] FIG. 2 is a schematic front view of the coiling machine shown in FIG. [Figure 3] FIG. 3 is a schematic flowchart of a method for manufacturing a coil spring according to one embodiment. [Figure 4] FIG. 4 is a schematic perspective view of a coiling machine illustrating a specific example of a spiral forming step according to one embodiment. [Figure 5] FIG. 5 is a schematic perspective view of a coiling machine showing a specific example of the heating step. [Figure 6] FIG. 6 is a schematic perspective view showing a first example of a laser light irradiation mode. [Figure 7] FIG. 7 is a schematic perspective view showing a second example of the laser light irradiation mode. [Figure 8] FIG. 8 is a schematic perspective view of a coiling machine showing a specific example of the cutting step. [Figure 9] FIG. 9 is a side view showing an example of a suitable positional relationship between the mandrel, the cutter, and the heating portion. [Figure 10] FIG. 10 is a side view showing a state in which the wire has been cut by the cutter. [Figure 11] FIG. 11 is a table showing the heating conditions used in the verification of sputtering. [Figure 12] FIG. 12 is a schematic plan view of the surface of a wire irradiated with laser light having a rectangular beam profile. [Figure 13] FIG. 13 is a diagram for explaining the definition of the irradiation area shown in FIG. [Figure 14] FIG. 14 is a schematic plan view of the surface of a wire irradiated with laser light having a circular beam profile. [Figure 15] FIG. 15 is a diagram for explaining the definition of the irradiation area shown in FIG. [Figure 16] FIG. 16 is a table showing the results of an experiment conducted to confirm whether spatters occurred under each of the heating conditions shown in FIG. [Figure 17] FIG. 17 is a table showing the calculation results of the cutting parameters. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a coiling machine and a method for manufacturing a coil spring will be described with reference to the drawings.

[0012] FIG. 1 is a schematic perspective view showing a main part of a coiling machine 100 according to this embodiment. FIG. 2 is a schematic front view of the coiling machine 100 shown in FIG. 1. As shown in FIGS. 1 and 2, a conveying direction X, a vertical direction Y, a forming direction Z, and a circumferential direction Dθ are defined. The conveying direction X, the vertical direction Y, and the forming direction Z are perpendicular to one another. The conveying direction X is the direction in which a straight wire 1 is conveyed before being formed into a spiral shape. The forming direction Z is the direction in which a coil spring formed by wire 1 bent into a spiral extends (the direction in which the coil spring grows). The circumferential direction Dθ is the direction in which the wire 1 forming the coil spring is wound.

[0013] The coiling machine 100 includes a conveying unit 10, a spiral forming unit 20, a cutter 30, a laser heater 40, and a controller 50.

[0014] 1 and 2, the transport unit 10 includes a pair of drive rollers 11, a pair of driven rollers 12, and a wire guide 13. The transport unit 10 may include more drive rollers 11 and driven rollers 12.

[0015] Each drive roller 11 and each driven roller 12 face each other via the wire 1. When each drive roller 11 rotates, each driven roller 12 rotates via the wire 1. With this rotation, the wire 1 sandwiched between each drive roller 11 and each driven roller 12 is conveyed in the conveying direction X. The wire 1 is inserted into the wire guide 13. The wire guide 13 guides the wire 1 so that it moves straight in the conveying direction X, and leads the wire 1 to the spiral forming unit 20.

[0016] The spiral forming unit 20 forms the wire 1 conveyed by the conveying unit 10 into a spiral shape. In the example of FIGS. 1 and 2, the spiral forming unit 20 includes a first forming roller 21, a second forming roller 22, and a pitch tool 23.

[0017] The first forming roller 21, the second forming roller 22, and the pitch tool 23 are arranged in this order along the circumferential direction Dθ. The positions of the first forming roller 21, the second forming roller 22, and the pitch tool 23 in the forming direction Z are different from one another.

[0018] The first shaping roller 21 and the second shaping roller 22 sequentially bend the wire 1 conveyed in the conveying direction X in the vertical direction Y. The wire 1 thus sequentially bent describes an arc along the circumferential direction Dθ. The bent wire 1 is guided by the pitch tool 23 at a position shifted in the shaping direction Z from the second shaping roller 22.

[0019] The cutter 30 includes a mandrel 31 and a cutter 32. The mandrel 31 is disposed inside the first forming roller 21, the second forming roller 22, and the pitch tool 23. As shown in FIG. 2, for example, the mandrel 31 has a semicircular shape along the XY plane and extends longitudinally in the forming direction Z. Specifically, the mandrel 31 has a plane 310 parallel to the vertical direction Y and the forming direction Z, and a curved surface 311 having an arc-shaped cross section. The inner peripheral surface of the spirally formed wire 1 is supported mainly near the end of the curved surface 311 in the vertical direction Y.

[0020] The cutter 32 is disposed between the second forming roller 22 and the pitch tool 23 in the circumferential direction Dθ. The cutter 32 is formed, for example, from a block-shaped steel material. However, the shape of the cutter 32 is not limited to this example. The cutter 32 is configured to be movable along the vertical direction Y by a drive mechanism provided in the cutting device 30.

[0021] 2, the laser heater 40 irradiates a part of the spirally formed wire 1 with laser light L. By irradiating the wire 1 with this laser light L, a heated part 1V having a higher temperature than other parts is formed in the wire 1.

[0022] 1 and 2, the laser heater 40 includes a laser oscillator 41, an optical fiber 42, and a laser head 43. The laser head 43 includes, for example, a beam spot adjuster.

[0023] The laser oscillator 41 may be, for example, a semiconductor laser that generates laser light L. The optical fiber 42 transmits the laser light L generated by the laser oscillator 41 to the laser head 43. The laser head 43 adjusts the beam shape of the laser light L to a rectangle or a circle using the above-mentioned beam spot adjuster. The beam spot adjuster may be, for example, an optical element such as a beam homogenizer.

[0024] 2, the laser light L emitted from the laser head 43 is inclined at an acute angle θ with respect to the vertical direction Y. In the YZ plane, the laser light L may be parallel to the vertical direction Y or may be inclined with respect to the vertical direction Y.

[0025] The controller 50 controls the conveying unit 10, the spiral forming unit 20, the cutter 30, and the laser heater 40. For example, the controller 50 includes a CPU (Central Processing Unit). The CPU executes a computer program related to the manufacture of coil springs, thereby realizing various processes for driving the conveying unit 10, the spiral forming unit 20, the cutter 30, and the laser heater 40.

[0026] Next, a method for manufacturing a coil spring using the coiling machine 100 will be described. Fig. 3 is a schematic flowchart of the method for manufacturing a coil spring according to this embodiment. This manufacturing method includes, as main steps for manufacturing one coil spring, a spiral forming step S1, a laser heating step S2, and a cutting step S3. Although not shown in the flowchart, the method for manufacturing a coil spring according to this embodiment may also include general coil spring manufacturing steps such as quenching, tempering, setting, and shot peening.

[0027] 4 is a schematic perspective view of a coiling machine 100 illustrating a specific example of the spiral forming step S1. In the spiral forming step S1, a conveying unit 10 uses a driving roller 11 and a driven roller 12 to move the wire 1 straight in the conveying direction X and guide it to a wire guide 13. The wire 1 guided out of the wire guide 13 is bent in the vertical direction Y by a first forming roller 21 and a second forming roller 22 and formed into an arc shape. The arc-shaped wire 1 is guided by a pitch tool 23 so as to be formed into a spiral shape with a predetermined pitch. This operation gradually elongates the spiral wire 1 in the forming direction Z.

[0028] 5 is a schematic perspective view of the coiling machine 100 showing a specific example of the heating step S2. In the heating step S2, the laser heater 40 irradiates, for example, a portion of the spirally shaped wire 1 that is located near the end of the mandrel 31 in the vertical direction Y (below the cutter 32) with laser light L. The base material of the wire 1 is heated by the energy of this laser light L, and a softened heated portion 1V is formed.

[0029] When the heating step S2 is performed, the conveyance unit 10 stops conveying the wire 1. The laser heater 40 is fixedly disposed at a predetermined position, for example, and irradiates the laser beam L from this position toward a portion of the stopped wire 1. As another example, the laser heater 40 may include a movement mechanism that moves the laser head 43, and the laser beam L may be irradiated while the laser head 43 is brought close to the wire 1 by this movement mechanism.

[0030] Fig. 6 is a schematic perspective view showing a first example of an irradiation mode of the laser beam L. Fig. 7 is a schematic perspective view showing a second example of an irradiation mode of the laser beam L. The laser heater 40 irradiates the surface of the wire 1 with the laser beam L in an irradiation direction DL.

[0031] The laser light L according to the first example has a rectangular beam profile that is elongated in the width direction of the wire 1. The laser light L according to the second example has a circular beam profile. A heated area 1V is formed in the irradiation area 1a of the wire 1 irradiated with the laser light L and its surroundings. The heated area 1V may include a molten pool formed by melting the base material of the wire 1 by the energy of the laser light L. This molten pool may extend not only to the irradiation area 1a but also to its surroundings.

[0032] The shape of the beam profile of the laser light L is not limited to the first and second examples. In addition, various shapes such as a square shape or an ellipse shape can be applied to the beam profile of the laser light L.

[0033] 8 is a schematic perspective view of the coiling machine 100 showing a specific example of the cutting step S3. The cutting step S3 is performed when a predetermined time has elapsed since the irradiation of the laser light L in the heating step S2 was stopped.

[0034] Specifically, in the cutting step S3, the cutter 32 descends toward the vicinity of the portion of the wire 1 supported by the mandrel 31 (near the heated portion 1V). At this time, the cutter 32 applies an impact to the outer circumferential surface of the wire 1, thereby cutting the wire 1. The spiral wire 1 cut in this manner corresponds to the coil spring 2.

[0035] The coil spring 2 has a first terminal 61 including a first end surface 61a and a second terminal 62 including a second end surface 62a. After one coil spring 2 is manufactured, the above-described spiral forming step S1, heating step S2, and cutting step S3 are performed again to manufacture the next coil spring 2. Therefore, both the first terminal 61 and the second terminal 62 are cut by the cutter 30. A dent may remain on the first terminal 61 due to the impact applied by the cutter 32. Furthermore, a mark caused by the irradiation of the laser light L may remain on at least one of the first terminal 61 and the second terminal 62.

[0036] 9 is a side view showing an example of a suitable positional relationship between the mandrel 31, cutter 32, and heated portion 1V. In the spiral forming step S1 described above, the spirally formed wire 1 is fed between the mandrel 31 and the cutter 32. In the feeding direction of the wire 1 (circumferential direction Dθ), a clearance C is provided between the downstream end (plane 310) of the mandrel 31 and the upstream end 320 of the cutter 32. In the example of FIG. 9, the irradiation center O of the laser light L is located closer to the cutter 32 than the clearance C (downstream in the circumferential direction Dθ).

[0037] In the example of FIG. 9, the heated area 1V includes an irradiated area 1a, a first softened area 1b around the irradiated area 1a, and a second softened area 1c around the first softened area 1b. For example, the irradiated area 1a and the first softened area 1b are mainly formed of austenite. This austenite transforms into martensite after self-cooling for a certain period of time. The second softened area 1c is mainly formed of tempered martensite. Immediately after irradiation with the laser light L, a molten pool may be formed in the irradiated area 1a.

[0038] For example, the irradiation area 1a overlaps with the cutter 32 in the vertical direction Y. Most of the first softened area 1b and the second softened area 1c also overlap with the cutter 32 in the vertical direction Y, but in the example of FIG. 9, part of the second softened area 1c is located in the clearance C.

[0039] FIG. 10 is a side view showing a state in which the cutter 32 is lowered parallel to the vertical direction Y from the state shown in FIG. 9 to cut the wire 1. When the tip of the cutter 32 impacts the outer peripheral surface of the wire 1 that protrudes in the circumferential direction Dθ beyond the plane 310 of the mandrel 31, a shear force is applied to the heated portion 1V and its surroundings, causing the wire 1 to break. The cutter 32 descends, for example, up to near the axis of the wire 1. A dent B (depression) caused by the cutter 32 is formed in the cut wire 1, i.e., the coil spring 2. In the example of FIG. 10, the irradiated region 1a and the first softened region 1b overlap with the dent B, but they may also be offset from each other.

[0040] Even if a molten pool is formed in the irradiated region 1a immediately after irradiation with the laser light L, the molten pool has already solidified due to self-cooling when the wire 1 is cut by the cutter 32, or the molten pool solidifies due to heat loss caused by contact with the cutter 32. Therefore, a quench-hardened portion is formed in at least a part of the irradiated region 1a while the wire 1 is being cut.

[0041] On the other hand, the portions of the irradiation region 1a where no quench-hardened portion is formed, the first softened region 1b, and the second softened region 1c are softer than the quench-hardened portion and the base material of the wire 1. Therefore, when the cutter 32 impacts the wire 1, the portions of the irradiation region 1a where no quench-hardened portion is formed, the first softened region 1b, or the second softened region 1c in the heated portion 1V are likely to break. As shown in FIG. 9, if the irradiation center O is shifted toward the cutter 32 from the clearance C, a load can be effectively applied to the first softened region 1b or the second softened region 1c located upstream of the irradiation region 1a in the circumferential direction Dθ, and the wire 1 can be broken along these regions.

[0042] When the cutter 32 impacts the wire 1, a phenomenon (spattering) may occur in which metal particles from the heated area 1V fly off. This spattering is thought to occur when the cutter 32 comes into contact with the molten pool at the heated area 1V. Spattering can cause contamination of the coil spring 2 and the coiling machine 100. Therefore, it is necessary to set heating and cutting conditions that can suppress spattering.

[0043] The inventors have investigated heating conditions and cutting conditions that can suppress spattering. Figure 11 is a table showing three heating conditions 1, 2, and 3 used in this investigation. In this table, under heating conditions 1, 2, and 3, the irradiation area S [cm ] of the laser beam L on the heating area 1V is shown. 2 ], output P[W], irradiation time Tz[s], output density D[W / cm 2 ] and input energy per unit area E (J / cm 2 ) values ​​are shown.

[0044] The irradiation area S is the area of ​​the irradiation region 1a on the surface of the wire 1 when viewed in the irradiation direction DL. The power density D is the laser power P divided by the irradiation area S (D=P / S). The input energy E is the power density D multiplied by the irradiation time Tz (E=D×Tz).

[0045] Here, we will explain the irradiation region 1a for which the irradiation area S is to be calculated. Fig. 12 is a schematic plan view of the surface of the wire 1 irradiated with laser light L having a rectangular beam profile as shown in Fig. 6, viewed in the irradiation direction DL. In the following explanation, the direction parallel to the axis of the wire 1 is called the axial direction DA, and the direction perpendicular to the axial direction DA and the irradiation direction DL is called the width direction DW of the wire 1.

[0046] The dotted area in Fig. 12 corresponds to the irradiation area 1a of the surface of the wire 1 that is irradiated with the laser light L1. When viewed in the irradiation direction DL, this irradiation area 1a is rectangular having a width W1 in the axial direction DA and a width W2 in the width direction DW. In the example of Fig. 12, the width W1 is smaller than the width W2. However, the width W1 may be equal to or greater than the width W2.

[0047] Fig. 13 is a diagram for explaining the definition of the irradiation area 1a shown in Fig. 12. Fig. 13 shows a center line CL1 that passes through the irradiation center O of the irradiation area 1a and is parallel to the axial direction DA, and a center line CL2 that passes through the irradiation center O and is parallel to the width direction DW. On the surface of the wire 1, the laser light L1 has a power distribution PW1 along the center line CL1 and a power distribution PW2 along the center line CL2.

[0048] In the example of Figure 13, the power distribution PW1 is Gaussian, and the power distribution PW2 is top-hat. The Gaussian power distribution PW1 is mountain-shaped with the output value peaking in the center. The top-hat power distribution PW2 is trapezoidal, with the output value peaking over a wide range.

[0049] In this embodiment, the half width of the output distribution PW1 is defined as width W1, and the half width of the output distribution PW2 is defined as width W2. That is, the irradiation area 1a is an area defined by the half widths of the output distributions PW1 and PW2.

[0050] The half-width of the Gaussian power distribution PW1 corresponds to the width of the power distribution PW1 at the position where the power value is half of the peak P. Similarly, the half-width of the top-hat power distribution PW2 corresponds to the width of the power distribution PW2 at the position where the power value is half of the peak.

[0051] Fig. 14 is a schematic plan view of the surface of wire 1 irradiated with laser light L having a circular beam profile as shown in Fig. 7, viewed in irradiation direction DL. In the example of Fig. 14, irradiation area 1a is a perfect circle with a diameter Ra.

[0052] Fig. 15 is a diagram for explaining the definition of the irradiation area 1a shown in Fig. 14. For example, the laser light L has a Gaussian power distribution PW on the surface of the wire 1 on a line segment passing through the irradiation center O, such as center lines CL1 and CL2. The diameter Ra corresponds to the half-width of the power distribution PW, i.e., the width of the power distribution PW at the position where the output value is half of the peak PK.

[0053] The shape of the irradiation region 1a and the power distribution of the laser light L are not limited to those exemplified in Figures 12 to 15. For example, in the examples of Figures 12 and 14, both of the power distributions PW1 and PW2 may be top-hat types, or both of the power distributions PW1 and PW2 may be Gaussian types. Also, in the example of Figure 15, the power distribution PW may be top-hat type.

[0054] The irradiation area 1a may be defined as an area irradiated with the laser light L at an output equal to or greater than half of the peak, and its shape is not limited to a rectangle or a circle. As another example, the irradiation area 1a may be elliptical. In this case, the major and minor axes of the irradiation area 1a can be defined by the half-value width of the power distribution.

[0055] Fig. 16 is a table showing the results of an experiment to confirm whether spatter occurs under each of the heating conditions 1, 2, and 3 shown in Fig. 11. In this experiment, for each of the heating conditions 1, 2, and 3, the cooling time T [s] after heating was changed to four values: 0.3 s, 0.6 s, 0.9 s, and 1.2 s, and the wire 1 was actually cut by the cutter 30 to observe whether spatter occurs.

[0056] The cooling time T corresponds to the time from the irradiation of the laser light L to the cutting by the cutter 30, more specifically, the time from the cessation of the irradiation of the laser light L to the contact of the cutter 32 with the wire 1. During this cooling time T, the heat of the heated part 1V is mainly transferred to the surrounding area of ​​the wire 1, causing the temperature of the heated part 1V to decrease.

[0057] For heating conditions 1 and 2, no sputtering occurred regardless of whether the cooling time T was 0.3 s, 0.6 s, 0.9 s, or 1.2 s. On the other hand, for heating condition 3, sputtering occurred when the cooling time T was 0.3 s, 0.6 s, or 0.9 s, but no sputtering occurred when the cooling time T was 1.2 s.

[0058] Here, in order to quantify the conditions for generating spatter, the following cooling parameters and cutting parameters are defined. [Cooling parameter] = [Cooling time T] x [Coefficient A] [Cutting parameters] = [Input energy E] - [Cooling parameters] As a result of the inventors' investigation, it was found that by using cutting parameters calculated with coefficient A set to 800, it is possible to evaluate whether spatter occurs or not.

[0059] Figure 17 is a table showing the calculation results of the cutting parameters when coefficient A is set to 800. As shown in Figure 16, spatter occurs under heating condition 3 when the cooling time T is 0.3 s, 0.6 s, and 0.9 s. The cooling parameters are 4528, 4288, and 4048, respectively. On the other hand, under other conditions where spatter does not occur, the cooling parameters are lower.

[0060] Based on the above verification, it is clear that spattering can be suppressed by determining the heating and cutting conditions so that at least the cutting parameter is less than 4048. In other words, it is preferable to determine the input energy E and the cooling time T so that they at least satisfy the relationship ET×800<4048. It is even more preferable if the input energy E and the cooling time T satisfy the relationship ET×800<4000.

[0061] The scope of the present invention is not limited to the configurations disclosed in the above-described embodiments. The present invention can be implemented by modifying the configurations disclosed in the embodiments in various ways.

[0062] For example, when carrying out the present invention, it goes without saying that the configuration and arrangement of each element of the coiling machine 100 can be modified in various ways as needed.

[0063] The coil spring 2 manufactured by the coiling machine 100 may have a variety of shapes, and for example, the coil diameter and pitch may vary in the axial direction of the coil spring. In other words, the coil spring 2 manufactured by the coiling machine 100 may be a cylindrical coil spring, as well as a barrel-shaped coil spring, an hourglass-shaped coil spring, a tapered coil spring, an unequal pitch coil spring, a coil spring having a negative pitch portion, or any other shape. [Explanation of symbols]

[0064] 1...wire, 10...conveying unit, 20...spiral forming unit, 30...cutting machine, 31...mandrel, 32...cutter, 40...laser heating machine, 50...controller, 100...coiling machine, X...conveying direction, Y...vertical direction, Z...forming direction, 1V...heating area, 1a...irradiation area.

Claims

1. A spiral forming unit that forms a metal wire, which is a material for a coil spring, into a spiral shape; a laser heater that irradiates a laser beam onto the wire being formed into a spiral shape by the spiral forming unit to heat the wire, thereby forming a heated portion in the wire, the heated portion having an irradiation region including a molten pool, a first softened region located around the irradiation region and including austenite, and a second softened region located around the first softened region and including martensite; a cutter including a mandrel supporting the inner peripheral surface of the wire formed into a spiral shape, and a cutter projecting from an end of the mandrel and descending toward the outer peripheral surface of the wire, the cutter impacting the heated portion to cut the wire; Equipped with The input energy E [J / cm] per unit area by irradiating the heated portion of the wire with the laser light ２ ] and a time T [s] from when the irradiation of the laser light is stopped until the cutter comes into contact with the wire, E-T×800<4048 By satisfying the relationship above, spattering of metal particles at the heated portion when the cutter impacts the wire is suppressed.

2. The input energy is the power density D [W / cm ２ ] multiplied by the irradiation time Tz [s] of the laser light, The power density D is the sum of the power P [W] of the laser light and the area S [cm 2 ] of the irradiated region of the laser light on the surface of the wire. ２ ] is the value divided by The irradiation area is an area defined by a half width of the output distribution of the laser light on the surface of the wire.

2. The coiling machine according to claim 1.

3. A metal wire, which is the material for a coil spring, is formed into a spiral shape, a method for forming a heated portion in the wire, the heated portion having an irradiation region including a molten pool, a first softened region including austenite and located around the irradiation region, and a second softened region including martensite and located around the first softened region; The wire cutting method includes a mandrel that supports the inner peripheral surface of the wire formed into a spiral shape, and a cutter that protrudes from the end of the mandrel and descends toward the outer peripheral surface of the wire, and cuts the wire by applying an impact to the heated portion with the cutter. This includes: The input energy E [J / cm] per unit area by irradiating the heated portion of the wire with the laser light ２ ] and a time T [s] from when the irradiation of the laser light is stopped until the cutter comes into contact with the wire, E-T×800<4048 By satisfying the relationship above, spattering of metal particles at the heated portion is suppressed when the cutter impacts the wire.

4. The input energy is the power density D [W / cm ２ ] multiplied by the irradiation time Tz [s] of the laser light, The power density D is the sum of the power P [W] of the laser light and the area S [cm 2 ] of the irradiated region of the laser light on the surface of the wire. ２ ] is the value divided by The irradiation area is an area defined by a half width of the output distribution of the laser light on the surface of the wire. The method for manufacturing a coil spring according to claim 3.

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