Method and apparatus for dividing original sheet

Abstract

To provide a cutting method capable of accurately cutting at a high speed with a minimum thermal effect by using a laser beam.SOLUTION: The method for dividing the raw sheet 1 uses a hybrid double-core laser L. A raw material 1 in which an active material layer 2 is coated on at least one surface of a long metal foil 4 is conveyed in one direction. A double core laser L constituted of a high intensity laser Lf at the center part and a preheating laser Ly surrounding the periphery of the high intensity laser Lf and preheating the periphery of the irradiation point P with lower intensity than that of the high intensity laser Lf is irradiated in a pulse state. A perforated hole 1h is formed in a raw sheet 1 in the longitudinal direction. On the downstream side separated from the irradiating point P, the raw sheet 1 is torn up and down along the row of the hole 1h with the perforated hole 1h as a starting point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an innovative method and apparatus for dividing raw material sheets used in the production of electrode sheets for lithium secondary batteries, lithium capacitors, electric double layer capacitors, etc., which can suppress the generation of sparks at the irradiation point and minimize the thermal impact on the active material layer when dividing the raw material sheets into multiple pieces with a laser beam while the raw material sheets are in a moving state. [Background technology]

[0002] Non-aqueous electrolyte secondary batteries, typified by lithium ion secondary batteries, have the advantage of high energy density and are used in a variety of electronic devices, from small-scale electronic devices such as mobile phones and personal computers to large-scale electronic devices such as power storage devices for hybrid or electric vehicles. The electrode assembly, which is the main internal structure of a lithium-ion secondary battery, can be of a wound type, in which positive and negative electrode strips, made of metal foil coated with an active material, and a separator are overlapped and wound together, or a laminated type, in which positive and negative electrode sheets cut into rectangles from a roll of material are alternately laminated with separators. The above structure is also the same for lithium capacitors and electric double layer capacitors.

[0003] These electrode assemblies are configured to fit the size of the electronic components used. In contrast, the raw material for electrode assemblies, a substrate, is a wide metal foil such as aluminum or copper, from the viewpoint of productivity. The substrate is made by applying positive or negative electrode paste (e.g., an electrode active material such as a lithium compound or carbon that is responsible for the movement of electrons and ions during battery charging and discharging, a binder that adheres the electrode active material powder to each other and to the current collector, and a conductive additive that increases the conductivity between the active material particles and ensures a conductive path) to one or both sides of the foil in a strip-like shape across almost the entire width and in the longitudinal direction, and then curing the paste. The substrate is then left with edge sections on both sides where no active material is applied. The substrate is generally wound up on a roller. Then, depending on the application, the wide raw sheet is slit to the required width using, for example, a slitter having a pair of upper and lower disk-shaped blades (Patent Document 1).

[0004] However, when raw rolls coated with hard active materials are slit with a disc-shaped slitter blade, the blade edge gradually wears down, and sharp burrs that can cause problems tend to form on the cut end surface in the cutting direction, i.e., on the surface of the raw roll. These burrs are one of the causes of battery product failures (for example, fires due to short circuits).

[0005] As a method for solving such problems, the use of a laser beam such as a YAG laser has been proposed (Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 7-37595 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-14993 Summary of the Invention [Problem to be solved by the invention]

[0007] When a running web is cut using a laser beam, such as a YAG laser, the laser beam first irradiates the active material layer on the surface, burning off the resin that makes up the active material layer. Subsequently, the active material layer and metal foil rapidly melt, forming a liquid pool in this area. This liquid pool forms rapidly and moves in the running direction of the web as the web moves, generating intense turbulence within the pool, causing the molten metal to spatter and scatter around. This spatter of molten metal adheres to the active material layer on the surface of the web, contributing to battery failure. On the opposite side of the web's running direction, the molten portion attempts to resolidify in the wake of the laser beam, but air is blown to prevent this. This air blow causes the molten metal to splash around, also contributing to battery failure.

[0008] In addition, the active material layer burns around the irradiation point of a laser beam such as a YAG laser, resulting in a deterioration in performance. When a raw material is cut by continuously irradiating a laser beam onto a raw material that is continuously moving roller-to-roller, as in Patent Document 2, the active material layers on both sides of the cutting line are thermally affected along the entire length of the cutting line, resulting in a wide area of ​​performance degradation.

[0009] High-speed cutting of raw web is required from the viewpoint of manufacturing costs, and continuous cutting of raw web while traveling at such high speeds is required. When a wide raw web consisting of an active material layer approximately 100 microns thick on the surface and a metal foil approximately 10 microns thick laminated thereon is run at high speed by roller-to-roller, even if both sides of the laser irradiation point are supported by feed rollers on the underside of the raw web as in Patent Document 2, the raw web vibrates at the laser irradiation point and undulates up and down in the traveling direction. On the other hand, since the focal depth of the laser beam is short, if the raw web undulates up and down while traveling, it may deviate from the focal depth of the laser beam, resulting in insufficient cutting.

[0010] The present invention has been made in view of the problems of the conventional example, and has as its object to provide a cutting method and dividing device which can use a laser beam with minimal thermal influence and with the generation of spatter suppressed, and which can also cut accurately at high speed. [Means for solving the problem]

[0011] The invention method (raw roll dividing method) described in claim 1 is a method for dividing a raw roll 1 using a hybrid double-core laser L, An active material layer 2 is applied to at least one side of a long metal foil 4, and a raw web 1 is being transported in one direction. A double-core laser L is irradiated in pulses onto the raw web 1, the double-core laser L consisting of a high-intensity laser Lf at the center and a preheating laser Ly that surrounds the high-intensity laser Lf and has a lower intensity than the high-intensity laser Lf and preheats the area Py around the irradiation point Pf of the high-intensity laser Lf, to form perforated holes 1h in the longitudinal direction of the raw web 1, and then, downstream and away from the irradiation point P, the raw web 1 is torn vertically along the row of perforated holes 1h, starting from the perforated holes 1h.

[0012] The method of the invention described in claim 2 is a method for suppressing vibration of the running web 1 at the irradiation point P during laser irradiation, and in the method of dividing a web described in claim 1, The area including the irradiation point P of the raw web 1 is brought into contact with the backup roller 30 from the opposite direction of the laser beam irradiation, and the double-core laser L is irradiated onto the irradiation point P while applying tension T to the raw web 1 in the contact range Θ with the backup roller 30.

[0013] The method of the invention described in claim 3 is the method of dividing a raw sheet described in claim 1 or 2, in relation to the irradiation angle of the double-core laser L, The double-core laser L is irradiated onto the irradiation point P from a direction inclined in the running direction of the raw web 1 with respect to a tangent line H that contacts the irradiation point P.

[0014] The invention device A described in claim 4 is a device for carrying out the method described in claim 1. A raw sheet dividing device (A) that cuts a raw sheet (1) having an active material layer (2) applied to at least one surface of a long metal foil (4) in the longitudinal direction using a double-core laser (L), The raw fabric dividing device A is a raw web supply unit 10 that delivers the raw web 1; divided raw roll winding units 60s and 60t for winding up the divided raw rolls 1s and 1t; a laser beam emitting device (70) that irradiates a double-core laser beam (L) onto an irradiation point (P) of the web (1) located between the web supply unit (10) and the divided web winding units (60s, 60t); a pair of upper and lower drive rollers 20a and 20b disposed between the irradiation point P and the web supply unit 10 so as to sandwich the web 1 from above and below, and which draw out the web 1 from the web supply unit 10; a pair of upper and lower nipping rollers 40a and 40b disposed between the irradiation point P and the divided web winding sections 60s and 60t so as to sandwich from above and below the web 1 on which perforations 1h have been formed by the double-core laser L; and separating rollers 50s and 50t, one of which is disposed above the clamping rollers 40a and 40b and the other of which is disposed below the clamping rollers 40a and 40b, between the clamping rollers 40a and 40b and the divided web winding sections 60s and 60t, for tearing the web 1 delivered from the clamping rollers 40a and 40b into upper and lower parts starting from the perforated holes 1h. The laser emission device 70 is characterized in that it is configured to emit a pulsed double-core laser L, which is composed of a high-intensity laser Lf at the center and a preheating laser Ly that is lower in intensity than the high-intensity laser Lf, surrounds the periphery Py of the high-intensity laser Lf, and preheats the periphery Py of the irradiation point Pf of the high-intensity laser Lf.

[0015] The invention device A described in claim 5 is a device for carrying out the method described in claim 2 (Fig. 2). In the original fabric dividing device A described in claim 4, The backup roller 30 is disposed so that its upper portion exceeds a plane S connecting the drive rollers 20a and 20b and the clamping rollers 40a and 40b at their clamping portions. The upper part of the backup roller 30 contacts the contact area Θ including the irradiation point P of the double-core laser L from the opposite side of the laser beam irradiation to back up the raw web 1, and is characterized in that tension T is applied to the raw web 1 in the contact area Θ.

[0016] Claim 6 relates to the structure of the backup roller 30 and the arrangement of the laser emitting device 70 (FIG. 2), and in the invention device A described in claim 5, The laser beam emitting device 70 is disposed at an angle to the running direction of the web 1 with respect to a tangent line H that is in contact with the irradiation point P of the web 1, The backup roller 30 is characterized in that a recessed groove 31 is formed around the entire circumference in the contact area Θ with the raw web 1, including the irradiation point P of the double core laser L, with a width exceeding the irradiation area of ​​the double core laser L. [Effects of the Invention]

[0017] In the present invention, by using a double-core laser L, the preheating laser Ly is irradiated so as to surround the periphery Py of the irradiation point Pf of the high-intensity laser Lf, thereby heating the area (preheating area Py) in a ring shape.As a result, as will be described later, this preheating area Py acts as a buffer, making it possible to suppress the occurrence of sputtering near the irradiation point Pf of the high-intensity laser Lf.

[0018] Furthermore, by emitting pulses of the double-core laser L to the running web 1, holes 1h extending in the running direction are formed in a line like perforations in the web 1, which reduces the amount of heat input to the web 1 compared to conventional cutting methods that involve continuous laser irradiation. Therefore, in the present invention, the thermal influence on the active material layer 2 can be minimized.

[0019] The area Θ including the irradiation point P of the raw web 1 is brought into contact with the backup roller 30 from the opposite direction of the irradiation of the double-core laser L, and tension T is applied to this contact area Θ with the backup roller 30, so the raw web 1 always adheres to the surface of the backup roller 30 while traveling, and the focus of the double-core laser L never deviates from the raw web 1 even when irradiated while traveling. Therefore, all holes 1h can be formed accurately.

[0020] When the double-core laser L irradiates the raw web 1 from an oblique direction relative to the running direction, the irradiation point P extends long in the running direction of the raw web 1. Because the double-core laser L is a pulsed irradiation, the raw web 1 moves during the pulse irradiation time. Therefore, in conjunction with the running of the raw web 1, holes 1h extending in the running direction of the raw web 1 are formed in the raw web 1. These holes 1h extending in the running direction of the raw web 1 make it easier to tear the raw web 1 in the subsequent tearing process.

[0021] In the contact range Θ including the irradiation point P of the double-core laser L, a groove 31 having a width that covers the irradiation range of the double-core laser L emitted from the laser emission device 70 is formed around the entire circumference of the backup roller 30. Therefore, the double-core laser L that penetrates the hole 1h drilled in the raw web 1 passes through the groove 31 and does not come into contact with the backup roller 30, and the backup roller 30 is not damaged. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view of a web dividing device according to the present invention; [Figure 2] 2A and 2B are schematic side views of FIG. 1, in which (a) is a partially enlarged view of the state in which the double-core laser is irradiated obliquely onto the original roll, and (b) is a partially enlarged view of the state in which the double-core laser is irradiated almost perpendicularly from above onto the original roll. [Figure 3] FIG. 2 is an enlarged perspective view of the irradiation point and the torn portion of the raw fabric in the circled portion in FIG. 1. [Figure 4] FIG. 4 is an enlarged perspective view of FIG. 3. [Figure 5] 5A is an enlarged perspective view of the hole in FIG. 4, (b) is a plan view of the irradiation point at the beginning of irradiation, and (c) is a plan view when the irradiation point has moved. [Figure 6] FIG. 10 is an enlarged cross-sectional view of the irradiation point at the beginning of irradiation. [Figure 7] FIG. 10 is an enlarged cross-sectional view of the irradiation point after the original web has been moved. DETAILED DESCRIPTION OF THE INVENTION

[0023] 1, the web dividing device A of the present invention includes a web supply unit 10 that delivers the web 1, divided web take-up units 60s and 60t that take up divided webs 1s and 1t, a laser beam emitting device 70 that irradiates a double-core laser beam L onto an irradiation point P of the web 1 located between the web supply unit 10 and the divided web take-up units 60s and 60t, drive rollers 20a and 20b that are provided upstream of the irradiation point P and clamp the web 1 from above and below to drive and transport it downstream, a backup roller 30 that is provided downstream of the irradiation point P so as to come into contact with the underside of the web 1, and a web dividing unit 11 that is provided downstream of the irradiation point P and has holes 1h formed in a perforated shape by the double-core laser beam L. The apparatus is also equipped with a pair of upper and lower clamping rollers 40a and 40b that are installed so as to sandwich the web 1 from above and below and serve as the starting point for tearing and dividing the web 1, and separator rollers 50s and 50t that are located between the clamping rollers 40a and 40b and the divided web winding sections 60s and 60t, one above the clamping rollers 40a and 40b and the other below, and that tear the web 1 sent out from the clamping rollers 40a and 40b into upper and lower parts starting from the perforated holes 1h, and a smoke exhaust section 80.The apparatus also includes feed rollers 90, 91, 93, 95s, 95t, 96t, dancer rollers 92, 97s, 97t, etc., each of which is incorporated into the apparatus body (not shown).

[0024] 1 to be applied, an electrode paste is applied to at least one of the front and back surfaces of a metal foil 4 to form an active material layer 2. In the embodiment shown in the figure, an example in which the active material layer 2 is formed on the surface of the metal foil 4 is shown.

[0025] The raw roll 1 has areas on both sides of the metal foil 4 where the electrode paste that will become the active material layer 2 is not applied (these areas are called ears 4b). Although not shown, there are various other types of raw roll 1, such as those with ears 4b on only one side or those without ears 4b on both sides. An appropriate type is selected depending on the application. The metal foil 4 is, for example, a copper foil or an aluminum foil having a thickness of 10 microns·meters.

[0026] The electrode paste that becomes the active material layer 2 contains an active material, a binder, a solvent, etc. The electrode paste is applied to the metal foil 4 to a thickness of about 100 micrometers, and is then dried and solidified. The active materials contained in the electrode paste include a positive electrode active material and a negative electrode active material. Positive electrode active materials include, for example, composite oxides, metallic lithium, and sulfur, while negative electrode active materials include, for example, various carbons, alkali metals such as lithium and sodium, metal compounds, metal oxides such as SiOx, and boron-added carbon. The binder may be a resin such as a fluorine-containing resin, a thermoplastic resin, or an imide-based resin.

[0027] The web supply unit 10 is composed of a torque motor 11, a web delivery shaft 12 connected to the torque motor 11, and a web support stand (not shown) incorporated into the device body. The torque motor 11 has a large starting torque and drooping characteristics, and is a motor that can provide stable operation over the entire range of rotational speed-torque characteristics, especially at low speeds and when locked. A roller-shaped raw web 1 suspended on a raw web support stand is attached to a raw web feed shaft 12 and is drawn out under stable tension by a torque motor 11 on the feed side.

[0028] A pair of upper and lower drive rollers 20a and 20b are provided next to the raw fabric supply unit 10, and feed rollers 90, 91, and 93 are provided at intervals between the raw fabric supply unit 10 and the drive rollers 20a and 20b, and a dancer roller 92 is further provided between the adjacent feed rollers 91 and 93. The dancer roller 92 is of a known mechanism, and for example, a weight or spring is attached to the dancer roller 92 to apply a downward force, so that the dancer roller 92 rises and falls in accordance with changes in the tension applied to this part of the raw web 1, thereby maintaining a constant tension applied to this part of the raw web 1.

[0029] The drive rollers 20a and 20b rotate while sandwiching the web 1 from above and below, pull out the web 1 from the web supply section 10, and send it to the next laser irradiation area. One of the drive rollers, 20a, is equipped with a drive servo motor 21. An irradiation point P is installed downstream of this pair of drive rollers 20a and 20b. The irradiation point P will be described later.

[0030] A backup roller 30 is provided at this irradiation point P and is in contact with the underside of the web 1 (FIGS. 2 and 6). The top of the backup roller 30 is positioned slightly above the plane S connecting the upstream drive rollers 20a and 20b and the downstream upper and lower clamping rollers 40a and 40b, which clamp the web, so that it pushes the underside of the web 1 moving between the drive rollers 20a and 20b and the clamping rollers 40a and 40b upward. As a result, the upper part of the backup roller 30 comes into contact with the lower surface of the web 1 in the contact range Θ, slightly pushing the web 1 upward and applying tension T to the web 1 in the contact range Θ. During movement, the web 1 is in close contact with the upper surface of the backup roller 30 within the contact range Θ, and vibrations caused by movement are completely suppressed. As described above, downstream of the backup roller 30, a pair of upper and lower nipping rollers 40a and 40b are provided, which serve as starting points for dividing the web 1 into upper and lower parts.

[0031] In the outer peripheral surface of the backup roller 30, a recessed groove 31 having a width and depth that covers the irradiation range of the double core laser L is formed over the entire circumference in a portion including the irradiation point P of the double core laser L. Fig. 2(a) shows a state in which irradiation is performed from obliquely above with respect to a tangent line H that contacts the irradiation point P on the raw web 1. In the embodiment of Fig. 1, irradiation is performed from obliquely above on the upstream side. Of course, although not shown, irradiation may also be performed from obliquely above on the downstream side. 2(b) shows the case where irradiation is performed almost perpendicularly from above the raw web 1. In this case, the irradiation point P is set at a position that is shifted from the rotation center of the backup roller 30 and away from the groove bottom of the recessed groove 31. In either case, the width and depth of the groove 31 are formed to a size (width and depth) such that the double-core laser L passing through the hole 1h of the raw web 1 does not come into contact with the bottom of the groove 31 of the backup roller 30.

[0032] The laser emission device 70 is connected to two types of laser oscillators (not shown) and uses an optical fiber called a double-clad fiber, and is capable of emitting a pulsed short-wavelength double-core laser L. The square frame in the upper right of Fig. 2 shows the state in which a pulsed double-core laser L composed of two types of short-wavelength lasers, an inner one and an outer one, is emitted. Although one laser beam emitting device 70 is shown in FIG. 1, a plurality of laser beam emitting devices (not shown) can be installed in accordance with the number of divisions of the raw web 1.

[0033] The double-core laser L is a hybrid laser beam in which a high-intensity laser Lf is located at the center and a preheating laser Ly is provided to surround it. The diagrams within the circular frames shown in Figures 2(a) and 2(b) are schematic diagrams showing the state in which the inner ultrashort wavelength high-intensity laser Lf of the double-core laser L is emitted in pulses toward the irradiation point P, and the outer preheating laser Ly with a longer wavelength is emitted in pulses. The pulse interval of the high-intensity laser Lf and the pulse interval of the preheating laser Ly may be the same or different. Furthermore, the pulse timing may be the same or different. The hybrid double-core laser L, which is composed of the high-intensity laser Lf and the preheating laser Ly, is emitted in a pulsed form as a whole.

[0034] The ultrashort pulse laser used in the high-intensity laser Lf is selected depending on the type of metal foil 4 in terms of absorption rate, and a blue laser (blue light) is used when the metal foil 4 is copper, and LD (semiconductor laser) light is used when the metal foil 4 is aluminum. That is, blue laser (blue light) is easily absorbed by copper, and LD (semiconductor laser) light is easily absorbed by aluminum.

[0035] The infrared (IR) laser used as the preheating laser Ly emits radiation in the non-visible spectrum ranging from 1300 to 1700 nanometers, and is less intense than blue lasers or LD light. The laser emission device 70 emits a pulsed double-core laser L configured as described above.

[0036] The double-core laser L is irradiated at irradiation point P, which is a point on the groove 31 of the backup roller 30, to form a hole 1h in the raw web 1. The formation of the hole 1h will be described later. When the double-core laser L forms the hole 1h in the raw web 1, it passes through the underside of the raw web 1. Therefore, as shown in Figure 2(a) above, the double-core laser L may be positioned at an angle from the upstream side (or from the downstream side, although not shown) in the running direction of the raw web 1 with respect to a tangent H tangent to irradiation point P so that the double-core laser L that has passed through does not come into contact with the backup roller 30. Alternatively, as shown in Figure 2(b), the double-core laser L may be positioned nearly perpendicular to the raw web 1 at a position shifted from the center of rotation of the backup roller 30 so that it passes through the groove 31. The double-core laser L is then pulse-irradiated onto the moving web 1 for a certain pulse time, so that holes 1h extending in the moving direction of the web 1 are formed.

[0037] The clamping rollers 40a and 40b are rollers that start tearing the raw web 1 and are provided downstream of the irradiation point P, clamping the raw web 1, on which the perforated holes 1h are formed, from above and below.

[0038] In Fig. 1, if the front side of the web dividing device A is considered the front side, the separator rollers 50s and 50t are installed downstream of the nip rollers 40a and 40b, one in front of the other behind the nip rollers 40a and 40b. In the illustrated embodiment, the separator roller 50s located on the front side is located below the nip rollers 40a and 40b, while the separator roller 50t located on the rear side is located above the nip rollers 40a and 40b, so that a separation angle γ is formed between the upper and lower separator rollers 50s and 50t at the exit of the nip rollers 40a and 40b. (Of course, the upper and lower arrangement of the separator rollers 50s and 50t may be reversed.)

[0039] Following the separating rollers 50s and 50t, feed rollers 95s, 95t and 96t are provided on each line to feed the divided webs 1s and 1t to the next divided web winding sections 60s and 60t. On the front line, a dancer roller 97s is provided between the separation roller 50s and the feed roller 95s, and on the rear line, a dancer roller 97t is provided between the separation roller 50t and the feed roller 95t, so that a certain tension is applied to the divided raw webs 1s and 1t, which are torn apart vertically at the exit of the separation rollers 50s and 50t and wound around the divided raw web winding sections 60s and 60t.

[0040] Divided web winding units 60s and 60t are installed downstream of the feed rollers 95s and 96t, respectively, and the vertically torn webs 1s and 1t are wound around winding shafts 62s and 62t. Winding servomotors 61s and 61t are connected to the winding shafts 62s and 62t, respectively. The winding servomotors 61s and 61t rotate in synchronization with the drive servomotor 21 for the drive roller 20a.

[0041] The smoke exhaust section 80 is composed of an upper surface side smoke exhaust case 81 and a lower surface side smoke exhaust case 85. The upper-side smoke exhaust case 81 is open at the bottom and covers the periphery of the irradiation point P on the upper side of the raw web 1. Figure 4 shows half of the upper-side smoke exhaust case 81 cut from the center. A slit 82 (half of which is shown in the figure) is formed on the upper surface of the upper-side smoke exhaust case 81, allowing the double-core laser L to pass through and extending in the conveyance direction of the raw web 1. A smoke exhaust pipe 83 is provided on the side of the upper-side smoke exhaust case 81, and air is sucked through the smoke exhaust pipe 83 so that the inside of the upper-side smoke exhaust case 81 is always kept at negative pressure.

[0042] The bottom-side smoke exhaust case 85 has an open top and covers the periphery of the irradiation point P on the bottom side of the raw web 1. The width of the bottom-side smoke exhaust case 85 is narrower than the recessed groove 31 of the backup roller 30, and its height is shallower than the depth of the recessed groove 31, so that it can be inserted into the recessed groove 31. A smoke exhaust pipe 87 is provided on the side of the bottom-side smoke exhaust case 85, and air is sucked through the smoke exhaust pipe 87 so that the inside of the bottom-side smoke exhaust case 85 is always under negative pressure. The bottom surface of the lower smoke exhaust case 85 is provided with a passage window 86 through which the double-core laser L passes after passing through the hole 1h in the raw web 1. (Alternatively, the inner surface of the lower smoke exhaust case 85 may be blackened without the passage window 86 to absorb the double-core laser L.)

[0043] Next, the operation of this device A will be described. The web 1 is attached to the web feed shaft 12 as shown in Figure 1. Before operation, the pulled-out portion of the web 1 passes between the drive rollers 20a and 20b and is divided by an operator after passing over the clamping rollers 40a and 40b. One of the divided webs 1s passes under the front separating roller 50s, and the other divided web 1t passes over the rear separating roller 50t and is wound onto the downstream winding shafts 62s and 62t, respectively.

[0044] When device A is operated from this state, drive servo motor 21 operates to pull out web 1 from web supply section 10. Torque motor 11 is installed in web supply section 10, and torque motor 11 rotates in accordance with the feed speed of web 1 pulled out by drive servo motor 21. Torque motor 11 pulls out web 1 from web supply section 10 with a constant tension, regardless of the number of turns of web 1.

[0045] A dancer roller 92, located adjacent to the downstream side of the web supply section 10, moves up and down in response to subtle changes in the tension of the web 1 drawn out from the web supply section 10, thereby maintaining a constant tension T of the web 1 between the drive rollers 20a and 20b, which are connected to the drive servo motor 21, and the web supply section 10. After drawing out the web 1 from the web supply unit 10 in this way, the drive rollers 20a and 20b feed the web 1 in the direction of the next irradiation point P.

[0046] In this device A, the raw web 1 is cut by a double-core laser L while it is traveling. At the irradiation point P, a double-core laser L is emitted in pulses from the laser emission device 70. As described above, the double-core laser L has a high-intensity laser Lf at the center and a preheating laser Ly surrounding it, forming an inner and outer double irradiation surface at the irradiation point P of the raw web 1. The inside of the irradiation point P is the irradiation point Pf of the high-intensity laser, and the surrounding area is the preheating region Py by the preheating laser Ly (FIG. 5(b)). The high-intensity laser Lf and the preheating laser Ly emitted in pulses are continuously applied to the irradiation point P during the pulse time (see the diagram within the square frame in Figure 2). 6 and 7, the raw web 1 moves from right to left.

[0047] Figure 6 shows the initial state of irradiation, where the double-core laser L is irradiated onto the raw web 1, forming a keyhole Kh and a small pool of molten metal 1u, and Figure 7 is a schematic diagram of the state in which a large pool of molten metal 1u is formed on the rear side of the elongated hole 1h created by the movement of the keyhole Kh in the preheating region Py around the keyhole Kh that has moved as the raw web 1 moves. Figure 5(a) is a perspective view, and Figure 5(c) is a plan view.

[0048] In the initial state (FIG. 5(b)), the active material layer 2 and the metal foil 4 are instantly heated and melted in the preheating region Py around the irradiation point Pf of the high-intensity laser, forming a small pool of molten metal 1u at that location. At this time, the resin is burned away and the active material is altered. The high-intensity laser irradiation point Pf is heated to a higher temperature than the preheating region Py, causing the active material and metal foil 4 in that area to rapidly melt, and the molten metal rapidly expands from the center of the raw web 1 at the irradiation point Pf. The rapidly expanding portion F also contains metal vapor. The rapidly expanding portion F, which also contains the metal vapor, sprays out vertically from the center, forming a keyhole Kh that penetrates vertically through the raw fabric 1. The rapidly expanding portion F, which also contains the metal vapor in the center, expands horizontally and applies pressure to the molten metal in the surrounding preheating region Py. The movement of the rapidly expanding portion F around the keyhole Kh affects the molten metal in the basin 1u, creating a flow of molten metal within the basin 1u.

[0049] At this time, as described above, around the keyhole Kh, the molten metal rises rapidly from bottom to top in the upper half of the keyhole Kh, and in the past, this rising speed became too great, causing the molten metal to splash out of the keyhole Kh. However, in this case, on the irradiated surface side of the preheating region Py (the upper surface side of the raw sheet 1), the high-intensity laser Lf pushes open the keyhole opening around the keyhole Kh, slowing down the rising speed of the molten metal at the keyhole opening, thereby significantly suppressing the splashing of the molten metal.

[0050] The next moment, as shown by the thick arrow in Figure 5(c), the workpiece 1 moves leftward, causing the irradiation point P to move rightward, and therefore the pool 1u to move rightward as well. The remaining portion of the pool 1u remains molten for a short time after the movement, resulting in the entire pool 1u extending backward from the keyhole Kh. In other words, a large pool 1u is formed behind the keyhole Kh. The remaining portion of the pool 1u, now removed from the irradiation point P, rapidly solidifies from its rear tail 1g (left end) by absorbing heat from its surroundings. At this time, the metal vapor generated within the keyhole Kh flows under high pressure from the back side of the keyhole Kh into the keyhole Kh's path, blocking the flow of molten metal into the keyhole Kh's path. As a result, a long, narrow hole 1h remains in the keyhole Kh's path (Figure 5(a)). In other words, the rear side of the keyhole Kh is connected to the long, narrow hole 1h. In FIG. 7, the elongated hole 1h, which is the trace of movement of the keyhole Kh, is shown only by a symbol in order to show the circulation of molten metal within a large molten metal pool 1u formed on the rear side of the elongated hole 1h.

[0051] As mentioned above, the keyhole Kh moves to the right together with the molten metal pool 1u, but the molten metal pool 1u is small in front of the keyhole Kh in the direction of its movement, and large molten metal pools 1u are formed on both sides of the elongated hole 1h behind the keyhole Kh, pulled by the movement of the keyhole Kh. Within this large molten metal pool 1u, the molten metal circulates in a rectified manner.

[0052] The keyhole Kh is formed penetrating the front and back of the raw material 1, but when the keyhole Kh moves along with the molten metal pool 1u, the area where the keyhole Kh was formed (the trace of movement) solidifies as it is. Because the keyhole Kh moves as described above, a long, thin hole 1h penetrating the raw material 1 from top to bottom remains in accordance with the irradiation time of the pulsed double-core laser L. Since the raw web 1 continues to move even during times when the double-core laser L is not being irradiated, as a result, elongated holes 1h extending in the running direction of the raw web 1 are formed in a perforated pattern. Preheated heat-affected zones 2n remain around the elongated holes 1h formed in a perforated pattern, but the areas between the holes 1h are not affected by heat. Therefore, the heat-affected zones 2n are significantly smaller than in continuous cutting.

[0053] The double-core laser L may be irradiated almost perpendicularly to the irradiation point P, but if it is irradiated at an angle to the tangent H that touches the irradiation point P as described above, the irradiated surface will extend long in the running direction of the raw web 1. Moreover, since the irradiation with the double-core laser L is performed while the raw web 1 is running as described above, the raw web 1 moves even during the pulse irradiation of the double-core laser L. Therefore, the irradiation point P has a shape that extends long in the running direction of the raw web 1. Furthermore, since the irradiation with the double-core laser L is performed in pulses, the holes 1h formed in the raw web 1 are formed in a line like a perforation as described above (Figure 4).

[0054] In the range Θ including this irradiation point P, the web 1 travels in contact with the rotating backup roller 30. In the contact range Θ, the upper part of the backup roller 30 protrudes slightly above the imaginary travel surface (plane S) of the web 1, so the web 1 sticks to the backup roller 30 in the contact range Θ, completely suppressing vertical vibrations caused by travel. In other words, the irradiation point P is completely fixed. When the double-core laser L is irradiated at an angle to the irradiation point P, the focal depth of the double-core laser L becomes shallow, but if the irradiation point P is completely fixed, the irradiation point P will not move out of the focal depth range of the double-core laser L. Therefore, all holes 1h formed are accurate and uniform.

[0055] When perforations 1h are formed in the raw web 1 in this manner, combustion gases from the active material layer 2 and the metal foil 4 are generated from both the top and bottom surfaces of the raw web 1 at the irradiation point P. Because the upper and lower smoke exhaust cases 81 and 85, which cover the irradiation point P of the raw web 1, are kept at negative pressure, these combustion gases are discharged to the outside via the respective smoke exhaust pipes 83 and 87.

[0056] Once a row of perforations 1h has been formed in the web 1, that portion is sent to the next pair of clamping rollers 40a and 40b. Separating rollers 50s and 50t are provided downstream of the clamping rollers 40a and 40b. The front separating roller 50s pulls downward the divided web 1s that has been pulled out from the front side of the clamping rollers 40a and 40b, while the rear separating roller 50t pulls upward the divided web 1t that has been pulled out from the rear side of the clamping rollers 40a and 40b. At the exit of the clamping rollers 40a and 40b, the web 1 is torn vertically along the perforations 1h, starting from the perforations 1h formed in the metal foil 4. This splits the web 1. The divided webs 1s and 1t pass through dancer rollers 97s and 97t and feed rollers 95s, 95t, and 96t and are wound onto divided web winding sections 60s and 60t, respectively.

[0057] As described above, the present invention makes it possible to accurately cut the raw web 1 at high speed with minimal thermal influence using a double-core laser. [Explanation of symbols]

[0058] 1: raw material, F: rapid expansion portion, 1g: tail portion of hot water reservoir, 1h: hole, 1s-1t: divided raw material, 1u: hot water reservoir, 2: active material layer, 2n: heat-affected portion (heat-affected zone), 4: metal foil, 4b: edge portion, 10: raw material supply portion, 11: torque motor, 12: raw material feed shaft, 20a-20b: drive roller, 21: drive servo motor, 30: backup roller, 31: groove, 40a-40b: clamping roller, 5 0s·50t: Separate roller, 60s·60t: Split web winding section, 61s·61t: Winding servo motor, 62s·62t: Winding shaft, 70: Laser emission device, 80: Smoke exhaust section, 81: Upper smoke exhaust case, 82: Slit, 83: Smoke exhaust pipe, 85: Lower smoke exhaust case, 86: Passage window, 87: Smoke exhaust pipe, 90, 91, 93, 95s·95t·96t: Feed roller, 92, 97s·97t: Dancer roller A: Raw material dividing device, H: Tangent line to the irradiation point, Kh: Keyhole, L: Double-core laser, Lf: High-intensity laser, Ly: Preheating laser, P: Double-core laser irradiation point, Pf: High-intensity laser irradiation point, Py: Surroundings of the high-intensity laser irradiation point (preheating area), S: Plane, T: Tension, γ: Separation angle, Θ: (Contact) range

Claims

1. A method for dividing a raw web, comprising: applying a layer of active material 2 to at least one surface of a long metal foil 4; and irradiating a raw web 1 being transported in one direction with a pulsed double-core laser L, the pulsed laser L comprising a high-intensity laser Lf at the center and a preheating laser Ly surrounding the high-intensity laser Lf and having a lower intensity than the high-intensity laser Lf for preheating the area Py around the irradiation point Pf of the high-intensity laser Lf, to form perforated holes 1h in the longitudinal direction of the raw web 1; and then, downstream away from the irradiation point P, tearing the raw web 1 vertically along the row of perforated holes 1h, starting from the perforated holes 1h.

2. 2. The method for dividing a raw web according to claim 1, wherein an area including the irradiation point P of the raw web 1 is brought into contact with a backup roller 30 from the opposite direction of the laser beam irradiation, and a double-core laser L is irradiated onto the irradiation point P while applying tension T to the raw web 1 in the contact range Θ with the backup roller 30.

3. 3. The method for dividing a web according to claim 1, wherein the double-core laser L is irradiated onto the irradiation point P from a direction inclined toward the running direction of the web 1 with respect to a tangent H to the irradiation point P.

4. A raw sheet dividing device (A) that cuts a raw sheet (1) having an active material layer (2) applied to at least one surface of a long metal foil (4) in the longitudinal direction using a double-core laser (L), a raw web supply unit 10 that delivers the raw web 1; divided web winding units 60s and 60t for winding the divided webs 1s and 1t; a laser emission device (70) that irradiates a double-core laser (L) onto an irradiation point (P) of the web (1) located between the web supply unit (10) and the divided web winding units (60s, 60t); a pair of upper and lower drive rollers 20a and 20b disposed between the irradiation point P and the raw web supply unit 10 so as to sandwich the raw web 1 from above and below, and which draws out the raw web 1 from the raw web supply unit 10; A pair of upper and lower clamping rollers 40a and 40b are installed between the irradiation point P and the divided web winding sections 60s and 60t so as to clamp from above and below the web 1 on which perforations 1h have been formed by the double-core laser L; and separating rollers 50s and 50t, one of which is disposed above the nipping rollers 40a and 40b and the other below the nipping rollers 40a and 40b, between the nipping rollers 40a and 40b and the divided web winding sections 60s and 60t, for tearing the web 1 sent out from the nipping rollers 40a and 40b into upper and lower parts starting from the perforated holes 1h. The laser emission device 70 is a raw sheet dividing device characterized in that it is configured to emit a double-core laser L in pulses, which is composed of a high-intensity laser Lf at the center and a preheating laser Ly that is lower in intensity than the high-intensity laser Lf and surrounds the periphery Py of the high-intensity laser Lf and preheats the periphery Py of the irradiation point Pf of the high-intensity laser Lf.

5. The backup roller 30 is disposed so that its upper portion exceeds a plane S connecting the drive rollers 20a and 20b and the nipping rollers 40a and 40b at their nipping portions.

5. A raw web dividing device as described in claim 4, characterized in that the upper part of the backup roller 30 contacts the contact area Θ including the irradiation point P of the double-core laser L from the opposite side of the laser beam irradiation to back up the raw web 1, and applies tension T to the raw web 1 in the contact area Θ.

6. The laser beam emitting device 70 is disposed at an angle to the running direction of the web 1 with respect to a tangent line H that is in contact with the irradiation point P of the web 1, 6. A raw web dividing device as described in claim 5, wherein a groove 31 is formed around the entire circumference of the backup roller 30 in a contact area Θ with the raw web 1, including the irradiation point P of the double-core laser L, with a width exceeding the irradiation area of ​​the double-core laser L.

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