Electrode plate cutting apparatus and electrode plate cutting method

Abstract

The present invention provides an electrode plate cutting apparatus and an electrode plate cutting method that can cut electrode plates while suppressing deterioration of the electrode plates during cutting. [Solution] The electrode plate cutting device 1 according to the disclosed technology is a device that cuts an electrode plate while rotating disc-shaped slit blades 2 and 3 around an axis. The slit blades 2 and 3 have a heat-generating part 21, a heat-transferring member 22 that receives heat from the heat-generating part, and a heat-shielding member 23 that is held by the heat-transferring member and is made of a material with lower thermal conductivity than the heat-transferring member. An annular cutting surface 24 is formed on both sides over the entire circumference of the radially outer side of the heat-generating part, where the heat-transferring member contacts the electrode plate to be cut. A non-heated part 25 is provided surrounding the heat-generating part, in which the heat-shielding member is exposed in a portion inside the outermost edge of the annular cutting surface.

Description

【Technical Field】 【0001】 The disclosed technology relates to an electrode plate cutting device and an electrode plate cutting method. 【Background Art】 【0002】 Conventionally, in the manufacturing process of batteries, electrode plates are cut. Generally, an electrode plate of a battery has a structure in which a composite layer is formed on the surface of a current collector foil. Therefore, when cutting the electrode plate, a part of the composite layer may be crushed and peeled off at the cutting position. As a countermeasure, for example, the technology described in Patent Document 1 can be cited. In the technology of this document, the electrode plate (referred to as "electrode for battery" in the document) is cut while being heated. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 11-138327 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 The above-mentioned conventional technology has a problem that the electrode plate deteriorates due to heating during cutting. This is because phenomena such as oxidation of the current collector foil, deterioration of the mechanical properties of the current collector foil, and alteration of the composite layer occur by passing through a high-temperature state. Therefore, it may also affect the power generation performance as a battery. 【0005】 An object of the disclosed technology is to provide an electrode plate cutting device and an electrode plate cutting method capable of cutting an electrode plate while suppressing deterioration of the electrode plate during cutting. 【Means for Solving the Problems】 【0006】 An electrode plate cutting apparatus in one aspect of the disclosed technology is an apparatus for cutting an electrode plate while rotating a disc-shaped slit blade around an axis, wherein the slit blade has a heat-generating part, a heat-transferring member that receives heat from the heat-generating part, and a heat-shielding member held by the heat-transferring member and made of a material with lower thermal conductivity than the heat-transferring member, and annular cutting surfaces are formed on both sides over the entire circumference radially outside the heat-generating part, in which the heat-transferring member contacts the electrode plate to be cut, and a non-heated portion is provided surrounding the heat-generating part in which the heat-shielding member is exposed in a portion inside the outermost edge of the annular cutting surface. 【0007】 In the electrode plate cutting apparatus described above, the electrode plate is cut while the heating element is heated and the heat transfer member is at a high temperature. At this time, not much heat is transferred to the heat shield member. As a result, a temperature difference is created on the surface of the slit blade due to the high temperature of the annular cut surface and the low temperature of the unheated part. During cutting, the composite layer of the electrode plate becomes hot due to the heat transfer member, so there is little peeling off of part of the composite layer during cutting. The current collector foil of the electrode plate does not come into contact with the slit blade before cutting, but may come into contact with the annular cut surface after cutting. However, the contact with the current collector foil is mainly with the unheated part of the annular cut surface. As a result, the temperature of the current collector foil does not rise much before or after cutting. Therefore, in the cutting apparatus of this embodiment, there is little deterioration of the electrode plate due to the temperature rise of the current collector foil during cutting. 【0008】 In the electrode plate cutting apparatus described above, the unheated portion may be in the shape of a continuous ring in the circumferential direction. In that case, it may further be in the shape of a wave with different radii depending on the location in the circumferential direction. Alternatively, the unheated portion may be in the shape of a discontinuous discontinuous distribution in the circumferential direction. By doing so, the unheated portion can be applied to the current collector foil more reliably, and the deterioration of the current collector foil can be suppressed. In particular, in the case of a wave-shaped or discrete portion, the deterioration of the current collector foil can be suppressed while the high-temperature annular cut surface can be applied to the composite layer, softening the composite layer. 【0009】 In the electrode plate cutting apparatus in any of the above embodiments, it is desirable that at least a portion of the annular cut surface on one side, closer to the outermost edge, be an inclined surface that approaches the annular cut surface on the opposite side as it moves radially outward, and that a portion of the unheated portion is provided on the inclined surface. In this configuration, the electrode plate after cutting comes into contact with the unheated portion on the inclined surface, which is highly effective in suppressing the temperature rise of the current collector foil. 【0010】 In an electrode plate cutting device having an inclined surface, it is desirable that the heat shielding member for the unheated portion on the inclined surface is thicker than the heat shielding member for the unheated portion on the annular cut surface on the opposite side. This configuration provides a greater effect in suppressing the temperature rise of the electrode plate that comes into contact with the unheated portion on the inclined surface after cutting. 【0011】 In an electrode plate cutting device having an inclined surface, it is also desirable that the inclined surface be provided with multiple unheated sections at different radial positions. This configuration suppresses temperature rise caused by the unheated sections, even if the position of the electrode plate on the inclined surface that it contacts after cutting changes. 【0012】 A method for cutting an electrode plate in another aspect of the disclosed technology is a method for cutting an electrode plate with a disc-shaped slit blade, the slit blade having a heat-generating part, a heat-transferring member that receives heat from the heat-generating part, and a heat-shielding member held by the heat-transferring member and made of a material with lower thermal conductivity than the heat-transferring member, the slit blade having annular cutting surfaces on both sides over the entire circumference radially outside the heat-generating part, in which the heat-transferring member contacts the electrode plate to be cut, and an unheated portion surrounding the heat-generating part where the heat-shielding member is exposed in a portion inside the outermost edge of the annular cutting surface, the method for cutting an electrode plate comprising rotating the slit blade around an axis and generating heat in the heat-generating part, while bringing the electrode plate before cutting into contact with the slit blade and bringing the unheated portion into contact with the cross-section of the electrode plate exposed by cutting. [Effects of the Invention] 【0013】 According to the disclosed technology, an electrode plate cutting apparatus and an electrode plate cutting method are provided that can cut electrode plates while suppressing deterioration of the electrode plates during cutting. [Brief explanation of the drawing] 【0014】 [Figure 1] This is a cross-sectional view showing the arrangement and structure of the slit blades in an electrode plate cutting device according to an embodiment. [Figure 2] This is a perspective view showing the slit blade in the embodiment. [Figure 3] This is a side view (part 1) showing the slit blade in the embodiment. [Figure 4] This is a side view (part 2) showing the slit blade in the embodiment. [Figure 5] This is a side view (part 3) showing the slit blade in the embodiment. [Figure 6] This is a cross-sectional view (part 1) showing the structure of an inclined slit blade. [Figure 7] This is a cross-sectional view showing a cutting device that uses an inclined slit blade. [Figure 8] This is a cross-sectional view showing an enlarged portion of Figure 6. [Figure 9] This is a cross-sectional view (part 2) showing the structure of an inclined slit blade. [Modes for carrying out the invention] 【0015】 This embodiment embodies the disclosed technology as an electrode plate cutting device and electrode plate cutting method that cuts the electrode plate of a battery using a disc-shaped slit blade that rotates around an axis. As shown in Figure 1, the cutting device 1 according to this embodiment has two slit blades 2 and 3. Slit blade 2 rotates around an axis 20. Slit blade 3 rotates around an axis 30. The electrode plate to be cut has a composite layer formed on both surfaces of a current collector foil. The composite layer contains a binder component. It does not matter whether it is for the positive electrode or the negative electrode. 【0016】 Shaft 20 and shaft 30 are parallel. The offset P between shaft 20 and shaft 30 is larger than the radius R of the slit blades 2 and 3 and smaller than twice the radius R. Both shaft 20 and shaft 30 are connected to a common rotational drive source M. The gap G between the slit blade 2 and the slit blade 3 is drawn larger in the figure, but is preferably within the range of about 0.01 times to 0.5 times the thickness of the electrode plate to be cut. The cutting device 1 is a device for cutting a strip-shaped electrode plate. When cutting the electrode plate with the cutting device 1, while rotating the slit blades 2 and 3, the electrode plate is advanced in a direction perpendicular to the plane of FIG. 1 at an intermediate position Q between shaft 20 and shaft 30. As a result, the electrode plate before cutting comes into contact with the slit blades 2 and 3, and the electrode plate is divided into two in the width direction. 【0017】 The slit blade 2 and the slit blade 3 in FIG. 1 have the same structure. The slit blade 2 will be described as a representative. The slit blade 2 shown in FIGS. 1 and 2 has a hub portion 21, a disk portion 22, and a heat insulation member 23. The hub portion 21 occupies the vicinity of the center of the slit blade 2 and is a part for attaching the slit blade 2 to the shaft 20. The disk portion 22 is a ring-shaped portion provided over the entire circumference around the hub portion 21. The outer circumference of the hub portion 21 and the inner circumference of the disk portion 22 are in close contact. The entire hub portion 21 and disk portion 22 form a disk shape. 【0018】 In the slit blade 2, flat annular surfaces of the disk portion 22 are formed on both sides over the entire outer circumference in the radial direction of the hub portion 21. This surface is called an annular cutting surface 24. The annular cutting surface 24 is the surface that contacts the electrode plate to be cut during cutting. In this embodiment, the annular cutting surface 24 is flush with the surface of the hub portion 21. The heat insulation member 23 is a member held by the disk portion 22. The heat insulation member 23 is exposed at a part of the annular cutting surface 24. The portion of the annular cutting surface 24 where the heat insulation member 23 is exposed is called a non-heating portion 25. The non-heating portion 25 is located inside the outermost edge in the annular cutting surface 24. The non-heating portion 25 is provided surrounding the hub portion 21. 【0019】 The hub portion 21 is a heat - generating portion that generates heat. The disk portion 22 is a heat - conducting member through which heat is transmitted from the hub portion 21. The heat - insulating member 23 is formed of a material having a lower thermal conductivity than the material of the disk portion 22. The cutting of the electrode plate by the cutting device 1 is performed with the hub portion 21 generating heat and the disk portion 22 being at a high temperature. At this time, the portion of the non - heating portion 25 does not heat up as much as the portion of the annular cutting surface 24 other than the non - heating portion 25. 【0020】 During cutting, the electrode plate before cutting contacts the slit blades 2 and 3. At this time, what contacts the slit blades 2 and 3 is the portion of the composite material layer of the electrode plate before cutting. Therefore, the binder component of the composite material layer softens due to the heat of the disk portion 22. The cutting of the electrode plate by the cutting device 1 is performed in a state where the composite material layer is plasticized in this way. As a result, in the cutting device 1, when cutting the electrode plate, peeled pieces of the composite material layer are less likely to occur. Also, the outermost edge portion of the annular cutting surface 24 of the slit blades 2 and 3 is a part of the disk portion 22, not the heat - insulating member 23. Therefore, the heat transfer from the disk portion 22 to the composite material layer before cutting is not hindered by the heat - insulating member 23. Also, the sharpness of the slit blades 2 and 3 is as good as in the case where there is no heat - insulating member 23. 【0021】 On the other hand, in the cutting device 1, deterioration of the current - collecting foil during cutting is also less likely to occur. This is because the temperature of the current - collecting foil does not rise as much as that of the composite material layer. In the electrode plate, the current - collecting foil is located between the composite material layers on the front and back. Therefore, the current - collecting foil of the electrode plate before cutting does not directly contact the slit blades 2 and 3. From this, originally, the current - collecting foil is less likely to heat up compared to the composite material layer. As a result, in the cutting device 1, deterioration of the current - collecting foil such as oxidation and deterioration of the mechanical properties is less. The elongation of the current - collecting foil during cutting is also less. 【0022】 In the cutting device 1, the cross-section of the electrode plate is exposed by cutting. The exposed cross-section of the electrode plate (hereinafter referred to as the "cut end face") includes the cross-section of the current collector foil. The cut end face, including the cross-section of the current collector foil within it, comes into contact with the annular cutting surface 24 of the slit blades 2 and 3. At this time, the cross-section of the current collector foil within the cut end face mainly comes into contact with the unheated portion 25 of the annular cutting surface 24. For this reason, the current collector foil does not heat up much even after cutting. As a result, the deterioration of the current collector foil after cutting is minimal in the cutting device 1. 【0023】 Furthermore, the cutting device 1 also experiences less deterioration of the asphalt layer. This is because, in addition to the minimal peeling during cutting as mentioned above, the asphalt layer is less indirectly heated from the inner side through the current collector foil. Therefore, only the portion of the asphalt layer directly heated by the disk portion 22 is affected by the thermal history during cutting. 【0024】 There are various methods for heating the hub portion 21, and any of them is acceptable. For example, a heating element may be embedded inside the hub portion 21, and Joule heating may be generated by supplying power from an external source. In this case, the rotation drive source M in Figure 1 should also have a power supply function for the heating element. Alternatively, the hub portion 21 may be heated by non-contact heating methods such as infrared irradiation or induction heating. The temperature of the disc portion 22 during cutting should preferably be such that it softens the synthetic resin used as the binder component. On the other hand, if the temperature is too high, there is a risk of excessively damaging the electrode plate being cut. If the binder resin is SBR resin, for example, the temperature should be in the range of 100 to 180°C. 【0025】 The material of the disc portion 22 in the slit blades 2 and 3 is not particularly limited as long as it can be used as a cutting tool. Particularly suitable materials include, for example, hard composite compounds of tungsten carbide and a metal (such as cobalt). This material has a proven track record in cutting and shearing processes. Its thermal conductivity is also sufficiently high, although not as high as that of copper or aluminum. Other materials such as stainless steel or tool steel can also be used. 【0026】 The heat shielding member 23 can be made of ceramics or synthetic resin. However, if synthetic resin is used, it must be heat-resistant enough to withstand high temperatures, such as the heating temperature of the aforementioned disc portion 22. 【0027】 Modified examples of slit blades 2 and 3 are described below. Figures 3 to 5 show modified examples of the shape of the unheated portion 25. Slit blades 2 and 3 in Figure 3 are the same as those shown in Figures 1 and 2. In slit blades 2 and 3 in Figure 3, the unheated portion 25 is a continuous ring shape in the circumferential direction. In the modified slit blades 2 and 3 in Figure 4, the unheated portion 25 has a discontinuous shape that is discretely distributed in the circumferential direction. In the modified slit blades 2 and 3 in Figure 5, the unheated portion 25 is a wavy ring shape with a different radius depending on the location in the circumferential direction. 【0028】 By providing a non-heated section 25 around where the current collector foil of the electrode plate is located during cutting, the deterioration of the current collector foil can be suppressed more effectively. In particular, in the discrete type shown in Figure 4 and the corrugated type shown in Figure 5, the deterioration of the current collector foil is suppressed while the high-temperature annular cut surface 24 frequently comes into contact with the asphalt layer. Therefore, the effect of heating and softening the asphalt layer is significant. 【0029】 In Figure 1, the heat shield members 23 on the right and left sides of the slit blades 2 and 3 are depicted as not being connected. However, there may be areas where the heat shield members 23 on the right and left sides are connected, albeit partially. If the unheated portion 25 is intermittent, as shown in Figure 4, the heat shield members 23 on the right and left sides may be connected in all of the unheated portions 25. In short, the heat must not be blocked by the heat shield members 23 from the portion of the disk portion 22 that is on the inner side of the heat shield members 23 to the portion that is on the outer side of the heat shield members 23. 【0030】 The inclined slit blade 4 shown in Figure 6 is a modified example of the slit blade shape itself. The biggest difference between the slit blade 4 in Figure 6 and the aforementioned slit blades 2 and 3 is that the annular cutting surface on one side is an inclined surface 26. The inclined surface 26 is a surface that approaches the annular cutting surface 24 on the opposite side as it moves radially outward from the slit blade 4. The inclined surface 26 is provided around the entire circumference of the slit blade 4. In the slit blade 4, a portion of the unheated area is provided on the inclined surface 26 (unheated area 27), and the remaining portion is provided on the annular cutting surface 24 (unheated area 25). As shown in Figure 7, the inclined slit blade 4 is used in combination with the double-planar slit blade 2, with the inclined surface 26 facing outward. 【0031】 In this embodiment, the slit blade 4 further has a difference in the thickness of the heat shield member 23 between the annular cut surface 24 side and the inclined surface 26 side. In Figure 8, the thickness of the heat shield member 23 in the unheated portion 25 on the annular cut surface 24 side is denoted as T1, and the thickness of the heat shield member 23 in the unheated portion 27 on the inclined surface 26 side is denoted as T2. The thickness of the heat shield member 23 refers to the depth from the surface of the heat shield member 23 (unheated portions 25 and 27) to the bottom of the heat shield member 23. 【0032】 The thickness T2 on the inclined surface 26 side is greater than the thickness T1 on the annular cut surface 24 side. The reason for this is that the unheated portion 27 is more important than the unheated portion 25 in suppressing the temperature rise of the electrode plate after cutting. As shown in Figure 7, the electrode plates 31 and 32 after cutting are relatively likely to come into contact with the slit blade 4 on the inclined surface 26, but not so much with the flat annular cut surface 24. 【0033】 A modified example of an inclined slitting blade will be described. The slitting blade 5 shown in Figure 9 differs from the slitting blade 4 in Figure 6 in that an unheated section 28 is added. The unheated sections 27 and 28 in the slitting blade 5 are multiple unheated sections located at different radial positions on the inclined surface 26. The reason for providing the unheated section 28 in addition to the unheated section 27 on the inclined surface 26 is its importance in suppressing the temperature rise of the electrode plate after cutting. The position where the electrode plate 31 contacts the inclined surface 26 after cutting may fluctuate to some extent while cutting is in progress. Even in such cases, the slitting blade 5 with the unheated section 28 provides a stable effect in suppressing the temperature rise of the electrode plate after cutting. 【0034】 As described in detail above, according to this embodiment, the slit blade, which is a component of the cutting device 1, is provided with a heat shielding member 23 in addition to the heating element and heat transfer member. This makes a portion of the annular cut surface an unheated area. By employing a slit blade with such a structure, when cutting the electrode plate, the composite layer of the electrode plate is heated to a certain extent, while the current collector foil of the electrode plate is not heated too much. Thus, an electrode plate cutting device and an electrode plate cutting method are realized that can cut the electrode plate while suppressing the deterioration of the electrode plate during cutting. 【0035】 These embodiments and examples are merely illustrative and do not limit the disclosed technology in any way. Therefore, the disclosed technology can naturally be improved and modified in various ways without departing from its essence. For example, variations in the shape of the unheated portion 25 shown in Figures 3 to 5 can also be applied to the unheated portions 27 and 28 of inclined slit blades. Also, regarding Figure 1, although it is written that the slit blades 2 and 3 have the same structure, it is sufficient that they are the same in that they have a heating portion, a heat transfer member, and a heat shielding member, and that an annular cut surface and an unheated portion are configured on their surface. Differences such as variations in the shape of the unheated portion 25 are acceptable. 【0036】 Regarding the inclined slit blades 4 and 5, Figures 6 and 9 show an example where the position of the boundary between the inclined surface on the outer side and the flat portion on its inner circumference coincides with the position of the boundary between the hub portion 21 and the disc portion 22. However, this is not essential. The position of the boundary between the hub portion 21 and the disc portion 22 may be closer to the inside than the position shown in Figures 6 and 9. In that case, only a small portion of the outermost edge of the outer "annular cross-section" would be the "inclined surface." Conversely, the position of the boundary between the hub portion 21 and the disc portion 22 may be closer to the outside than the position shown in Figures 6 and 9. Figure 7 shows a device configuration with an inclined slit blade 4 and a flat slit blade 2 paired together, but a configuration with two inclined slit blades 4 and 5, both with their inclined surfaces 26 facing outwards, is also possible. 【0037】 The hub portion 21 and the disk portion 22 may be a single unit. In that case, the relationship between the "heat-generating part" and the "heat-transferring member" is as follows. If the heating method of the heating part is electric heating, the area around the shafts 20 and 30 in which the heating wires are embedded is the "heat-generating part," and the part of the integrated hub portion 21 and disk portion 22 outside of the heating wires is the "heat-transferring member." Alternatively, only the heating wires may be considered the "heat-generating part," and everything else in the hub portion 21 and disk portion 22 may be considered the "heat-transferring member." If the heating method of the heating part is non-contact heating, the area of ​​the integrated hub portion 21 and disk portion 22 that receives non-contact heating around the shafts 20 and 30 is the "heat-generating part," and the part outside of that is the "heat-transferring member." [Explanation of symbols] 【0038】 1 Cutting device 23 Heat shielding member 2 Slit blades 24 Annular cut surface 3 Slit blade 25 Non-heated section 4 Slit blades 26 Inclined surface 5 Slit blade 27 Non-heated section 20 shaft 28 non-heating section 21 Hub section 30 Axle 22 Disk section

Claims

[Claim 1] An electrode plate cutting device that cuts an electrode plate while rotating a disc-shaped slit blade around an axis, wherein the slit blade is The heat-generating part, A heat transfer member from which heat is transferred from the aforementioned heat-generating part, The heat transfer member is held by the heat transfer member and has a heat shield member made of a material with a lower thermal conductivity than the material of the heat transfer member. On both sides of the heating element, annular cut surfaces are formed that contact the electrode plate to be cut, extending over the entire circumference of the radially outer side of the heating element. An electrode plate cutting device in which a non-heated portion, where the heat shielding member is exposed in a portion inward from the outermost edge of the annular cross-section, is provided surrounding the heating portion. [Claim 2] The electrode plate cutting apparatus according to claim 1, wherein the non-heating section is A device for cutting electrode plates that are ring-shaped and continuous in the circumferential direction. [Claim 3] The electrode plate cutting apparatus according to claim 2, wherein the non-heating section is A cutting device for electrode plates that are corrugated, with different radii depending on the location in the circumferential direction. [Claim 4] The electrode plate cutting apparatus according to claim 1, wherein the non-heating section is A cutting device for electrode plates that are discretely distributed in the circumferential direction and are intermittent in shape. [Claim 5] An electrode plate cutting apparatus according to any one of claims 1 to 4, At least a portion of the annular cross-section on one side, closer to the outermost edge, is an inclined surface that approaches the annular cross-section on the opposite side as it moves radially outward, A cutting device for electrode plates, wherein a portion of the non-heated portion is provided on the inclined surface. [Claim 6] An electrode plate cutting apparatus according to claim 5, An electrode plate cutting device in which the heat shielding member of the non-heated portion provided on the inclined surface is thicker than the heat shielding member of the non-heated portion provided on the annular cut surface on the opposite side. [Claim 7] An electrode plate cutting apparatus according to claim 5, An electrode plate cutting device wherein the inclined surface is provided with a plurality of non-heated portions at different radial positions. [Claim 8] A method for cutting electrode plates, which involves cutting the electrode plate with a disc-shaped slit blade, The aforementioned slit blade is The heat-generating part, A heat transfer member from which heat is transferred from the aforementioned heat-generating part, The heat transfer member is held by the heat transfer member and has a heat shield member made of a material with a lower thermal conductivity than the material of the heat transfer member. On both sides of the heating element, annular cut surfaces are formed that contact the electrode plate to be cut, extending over the entire circumference of the radially outer side of the heating element. In the aforementioned annular cross-section, a non-heated portion is provided surrounding the heating portion, where the heat-shielding member is exposed in a portion inward from the outermost edge. The slit blade is rotated around its axis, and the heating element is heated, A method for cutting an electrode plate, comprising bringing the electrode plate into contact with the slit blade before cutting, and bringing the unheated portion into contact with the cross-section of the electrode plate exposed by cutting.

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