Winding body, method for manufacturing a winding body, welding electrode, and manufacturing apparatus

Abstract

To manufacture a winding body which can avoid the damage of other components or the like caused by a terminal end part of a metal wire rod by shortening a distance from a weld part to a terminal end edge as much as possible without increasing the number of manufacturing steps, thereby preventing a defective winding body from being manufactured.SOLUTION: There is provided a porous winding body (filter 10) to which at least one continued metal wire rod 20 is spirally wound in a multi-layered state. In the winding body, a terminal end part 30 (metal wire rod portion 20n) of the metal wire rod is resistance spot-welded to the other portion (metal wire rod portion 20m) of the metal wire rod, and fused at the welded point. The terminal end part 30 (metal wire rod portion 20n) has a weld-solidified part 31n which is solidified after the metal wire rod in a width direction is entirely welded.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a porous wound body in which at least one continuous metal wire is wound spirally and in multiple layers, a method for manufacturing the wound body, a welding electrode suitable for manufacturing the wound body, and a manufacturing apparatus including the welding electrode.

Background Art

[0002] A porous hollow cylindrical wound body produced by winding at least one continuous metal wire spirally and in multiple layers is used for filters that remove foreign matter exceeding a predetermined size from fluid, applications for cooling fluid, and the like. Patent Document 1 is cited as a document describing such a wound body. In the above-mentioned wound body, it is necessary to fix the end portion on the winding end side of the metal wire to an appropriate position of the wound body by welding or the like, and to cut the metal wire.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Here, it is desirable that the terminal edge (cut end) of the metal wire is as close to the welded portion as possible. If the terminal edge of the metal wire is greatly spaced from the welded portion, the following problems may occur. One example of the problem is that the portion of the metal wire from the welded portion to the terminal edge may catch on other components and damage the other components. Another example of the problem is that if the distance from the welded portion to the terminal edge is long, the welded portion is likely to peel off. If tools such as wire cutters or scissors are used to cut metal wire, the cutting blades must be applied in a direction intersecting the longitudinal direction of the metal wire. During cutting, the cutting blades are inserted between the metal wire and the winding body, so the length of the metal wire from the weld to the end edge becomes longer, and it is more prone to rising in the outer diameter direction due to the insertion of the cutting blades. Therefore, in order to avoid the above-mentioned problems, post-processing is required to shorten the length of the metal wire from the weld to the end edge, which increases the number of manufacturing steps.

[0005] Furthermore, to shorten the length of the metal wire from the weld to the end edge, it is conceivable to repeatedly bend the metal wire in a direction intersecting its longitudinal direction very close to the weld, thereby cutting the metal wire. However, this method is prone to deformation and work hardening of the cut end in the direction of bending, and does not solve the problem of damaging other parts. Moreover, it is a cumbersome cutting method. Patent Document 1 describes welding the end of a metal wire at the winding end, but it does not describe how to cut the end at the winding end. This invention has been made in view of the above circumstances, and aims to provide a winding body in which the distance from the welded part to the terminal edge is as short as possible without increasing the number of manufacturing steps. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a porous winding body in which at least one continuous metal wire is wound in a spiral and multilayer manner, characterized in that the end portion of the metal wire is resistance spot welded to another portion of the metal wire and cut at the welded portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a winding body in which the distance from the welded part to the terminal edge is as short as possible without increasing the number of manufacturing steps. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view of a filter according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing the state of the end of the filter; (a) is a cross-sectional view taken along the longitudinal direction of the metal wire, and (b) is a perspective view observed from the outer diameter side of the filter. [Figure 3] This diagram shows the area near the end of the filter using an actual photograph. [Figure 4] This diagram schematically shows the winding device, which is part of the manufacturing equipment for winding wires. [Figure 5] This diagram schematically shows the downstream side of the guide member in a winding manufacturing apparatus. [Figure 6] This is a perspective view showing an example of an electrode. [Figure 7] (a) and (b) are plan views illustrating the relationship between the electrode tip surface and the metal wire in contact with the electrode tip surface. [Figure 8] (a) and (b) are schematic diagrams showing the state of a metal wire just before it is cut. [Figure 9] (a) and (b) are schematic diagrams showing the state of a metal wire just before it is cut. [Figure 10] (a) and (b) are schematic diagrams showing the state of a metal wire just before it is cut. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below using embodiments shown in the figures. However, unless otherwise specified, the components, types, combinations, shapes, and relative arrangements described in these embodiments are merely illustrative examples and not intended to limit the scope of the invention to those described. Furthermore, the configurations shown in each embodiment can be combined as appropriate, as long as they do not contradict each other.

[0010] [Filter outline] Figure 1 is a schematic perspective view of a filter according to one embodiment of the present invention. The hollow cylindrical filter 10 according to an embodiment of the present invention is formed by winding at least one continuous metal wire 20 spirally and in multiple layers at a constant pitch with a constant inclination angle with respect to the axial direction (up and down direction in the figure). The filter 10 is an example of a porous winding body in which at least one continuous metal wire is wound spirally and in multiple layers. Here, the individual layers in which the metal wire 20 is wound in the same direction are referred to as wire layers L1, L2, L3, etc. The metal wires constituting each wire layer L1, L2, L3, etc. extend in the same direction inclined with respect to the axial direction (central axis Ax1) of the hollow cylindrical filter when viewed from the front, and the metal wires constituting each wire layer adjacent to each other in the inner and outer diameter directions extend in directions that intersect each other (they are not parallel).

[0011] In Figure 1, the direction in which the metal wire portion 20(n) (thickness not shown) constituting the outermost wire layer Ln (n is a natural number) extends (the longitudinal direction of the metal wire portion 20(n)) is indicated by the solid arrow, and the direction in which the metal wire portion 20(n-1) constituting the wire layer Ln-1 immediately inside it extends (the longitudinal direction of the metal wire portion 20(n-1)) is indicated by the dashed arrow. n is generally set to around 20 to 20,000 (approximately 10 to 10,000 round trips). In other words, the filter 10 has one wire layer (for example, wire layer L1) formed by winding a metal wire 20 spirally at a constant inclination angle with respect to the axial direction, and another wire layer (for example, wire layer L2) formed by overlapping the outer circumference of the one wire layer L1 and winding a metal wire spirally at a different inclination angle than the metal wire constituting the one wire layer L1. The metal wires constituting the one wire layer L1 and the other wire layer L2 adjacent to it are configured to be non-parallel to the axial direction and to intersect with each other. Furthermore, the inclination angle of the metal wires constituting the wire layer with respect to the axial direction may be configured to change within a single wire layer.

[0012] This filter 10 is used to remove unnecessary substances from various fluids such as liquids and gases, and also to cool the fluid passing through the filter at the same time depending on the application, such as for automobile airbag inflators. First, this filter is configured such that a flow path is formed for fluid to pass in the direction in which wire layers overlap, that is, in the radial direction of the filter (the direction in which wire layers overlap). The fluid may be passed from the inner diameter side to the outer diameter side of the filter, or may be passed from the outer diameter side to the inner diameter side. Here, the radial direction does not refer to the strictly diametrical direction (radial direction), but generally refers to the direction roughly radial with respect to the axial direction and the circumferential direction. The dimensions of the filter (the inner diameter, outer diameter, axial dimensions, etc.) are appropriately determined according to the structure and size of the device in which the filter is incorporated. Types of metal used as the material for this filter include iron, steel, mild steel, stainless steel, nickel alloys, copper alloys, titanium alloys, and aluminum alloys. The optimal type of metal is selected according to the application of the filter.

[0013] In addition, the thickness and cross-sectional shape (cross-sectional shape in the direction orthogonal to the longitudinal direction of the metal wire) of the metal wire used for the filter are appropriately determined according to the size of the filter, the substances to be removed by the filter, pressure loss, and the like. For example, the cross-sectional area of a metal wire used for an inflator filter is about 0.007 to 3.2 mm² (the wire diameter is about 0.1 to 2.0 mm when based on a metal element wire having a perfectly circular cross-sectional shape).

[0014] A metal wire rod obtained by rolling a metal element wire with a perfectly circular cross-sectional shape into a predetermined shape is used for the filter. For example, as the metal wire rod, a rectangular flat wire rolled to have a flat rectangular cross-sectional shape is used. Alternatively, as the metal wire rod, a deformed wire rolled such that its cross-sectional shape is a deformed shape including approximately W-shape, U-shape, J-shape, L-shape, X-shape, and ~-shape over the entire length in the longitudinal direction is used. Alternatively, as the metal wire rod, a deformed wire rolled such that the cross-sectional shape and outer shape are not constant over the entire longitudinal length of the metal wire rod, in other words, the cross-sectional shape and outer shape vary depending on the position in the longitudinal direction of the metal wire rod, is used. Such a deformed wire is, for example, rolled such that the cross-sectional shape changes for each longitudinal length approximately equal to the width of the metal wire rod.

[0015] In the filter 10, the metal wire rod 20 is wound so as not to be twisted. The filter 10 has a plurality of contact portions where metal wire rod portions are in contact with each other. The filter 10 may be subjected to a heat treatment (for example, a heat treatment for sintering) that joins all contact portions (or a plurality of contact portions) together. Alternatively, among the plurality of contact portions in the filter 10, a portion other than the end portion on the winding end side may be a non-joined portion where joining is not performed. If the heat treatment for sintering the entire filter 10 is not performed, the manufacturing cost of the filter 10 can be reduced, and the manufacturing time of the filter 10 can be shortened.

[0016] [State of terminal end] The filter 10 according to the present embodiment is characterized in that the winding end portion (terminal end portion 30) of the metal wire rod is melted and cut at the welded position. That is, in the filter 10, welding and melting cutting of the terminal end portion 30 are performed simultaneously.

[0017] In this example, fusing (or thermal cutting) refers to cutting the metal wire by heating all or part (the inner diameter side) of the metal wire in the thickness direction to a temperature equal to or higher than its melting point, and utilizing the tension acting on the metal wire. When the entire thickness direction of the metal wire is melted, the melted portion is cut. When part of the metal wire in the thickness direction is melted, the melted portion is cut, and at the same time, the heat-affected zone (mainly on the outer diameter side), which is adjacent to the melted portion and whose structure is changed by heating resulting in decreased strength, is cut (torn off). This example differs from cutting methods using shearing force or metal fatigue in that the metal wire is cut by applying a force in its longitudinal direction.

[0018] Figure 2 is a schematic diagram showing the state of the end portion of the filter, wherein (a) is a cross-sectional view cut along the longitudinal direction of the metal wire, and (b) is a perspective view observed from the outer diameter side of the filter. Hereinafter, in the metal wire portion 20n, the portion abutted by the welding electrode is referred to as the end portion 30. More specifically, the end portion 30 is a portion on the end edge 35 side (cut end side) relative to the indentation 33 of the welding electrode.

[0019] The end portion 30 of the metal wire 20 is resistance spot welded to an appropriate position (the joined portion 21) of another portion of the metal wire 20 (the metal wire portion 20m). In this figure, among the metal wire portion 20n constituting the outermost wire layer Ln, only the periphery of the end portion 30 in particular, and only the metal wire portion 20m belonging to the wire layer Lm located on the inner diameter side relative thereto are shown (provided that m is a natural number and m<n). The metal wire portion 20p indicated by a dotted line on the right side in the figure is a portion separated from the metal wire portion 20n after the metal wire 20 is fused. The melted portion 32p indicated by a dotted line in the figure is a portion that, in the metal wire portion 20p, is separated from the metal wire portion 20n after being melted.

[0020] A molten and solidified portion 31 (31n, 31m) is formed at the end portion 30, which is part of the metal wire portion 20n, and the overlapping metal wire portion 20m, where melting occurs during welding and subsequent solidification occurs. The metal wire portions 20n and 20m are integrated within the molten and solidified portion 31, but for convenience, the molten and solidified portions 31 located on the side of each metal wire portion 20n and 20m will be distinguished and described as molten and solidified portions 31n and 31m, respectively. The molten portion 32p is the molten portion 32 that was melted immediately before the metal wire portion 20p separated. The following describes in detail the traces remaining on the winding or filter when the metal wire is cut at the welded portion or heat-affected zone by the method according to the present invention.

[0021] <Molten and solidified portion at the terminal end> The molten and solidified portion 31n is formed when at least a portion of the metal wire portion 20n in the width direction has melted and then solidified. It is desirable that the molten and solidified portion 31n is formed only within the width direction range of the metal wire 20. That is, it is desirable that the molten and solidified portion 31n does not extend beyond the width direction edge of the metal wire portion 20n and not leak outwards (do not leak laterally).

[0022] The illustrated end portion 30 has a molten and solidified portion 31n formed after the entire widthwise direction (total width or total length in the widthwise direction) of the metal wire portion 20n has melted and solidified. This indicates that the entire widthwise direction of the metal wire 20 was covered by the welding electrode during welding, and that this resulted in the entire widthwise direction of the metal wire 20 being melted. The molten and solidified portion 31n is formed from the end edge 35 over a predetermined longitudinal length of the metal wire. By melting the entire widthwise direction of the metal wire 20, the metal wire 20 can be reliably cut. Furthermore, since the entire widthwise direction of the end portion 30 is melted and joined to the metal wire portion 20m, it becomes easier to secure the necessary joining strength.

[0023] Since the molten and solidified portion 31 is melted and then solidified, it is softer than other parts of the metal wire (except for high-carbon steel). If the metal wire 20 is cut using shear force with nippers or scissors, the area near the cut end of the metal wire will work harden. However, in this embodiment, the metal wire is melted or softened before being torn off, so the end portion 30 does not work harden. In other words, even without heat treatment or the like on the winding body, it is possible to prevent the molten and solidified portion 31 from coming into contact with other parts and damaging them. Also, unlike when the metal wire is cut with nippers or scissors, it is possible to minimize the upward movement of the cut end in a direction that intersects the longitudinal direction of the metal wire.

[0024] Since the terminal portion 30 is joined by resistance spot welding, traces of pressure applied by the electrode during welding (indentations 33) remain in the area of ​​the metal wire 20 closer to the starting end (closer to the beginning of the winding) than the molten and solidified portion 31. The indentations 33 are formed over the entire width of the metal wire portion 20n. The indentation 33 has a shape corresponding to the contact pattern of the electrode when the metal wire 30 is pressurized. As an example, the indentation 33 has a shape in which the portion that was not pressurized by the electrode and the portion that was pressurized are continuous via a gentle step. As another example, Figure 2(b) shows an example in which no step is formed between the portion that was not pressurized by the electrode and the portion that was pressurized, and the indentation 33 is recognized as a point of change in the inclination angle (or wall thickness) of the outer diameter side surface of both portions.

[0025] <Thinning of the terminal section> The thickness of the terminal portion 30 is thinner overall than the thickness t of the rest of the metal wire 20. This indicates that the metal wire was cut at the appropriate location in the molten portion 32, forming the terminal edge 35. This characteristic does not appear when the metal wire is cut using pliers or the like, that is, when the welded portion and the cut end are spaced apart in the longitudinal direction of the metal wire. The terminal portion 30 has a portion in the area where the molten and solidified portion 31n is formed in which the thickness of the metal wire 20 is thinned toward the terminal edge 35 of the metal wire 20 (a portion where the thickness gradually decreases). In particular, the portion of the molten and solidified portion 31n that is exposed to the outside has a thickness that gradually decreases toward the terminal edge 35. This indicates that the terminal portion 30 has melted or softened and been stretched toward the terminal edge 35, and that a portion of the thickness of the metal wire 20 located on the outer diameter side near the terminal portion 30 has disappeared due to melting and has not remained on the winding body side (the metal wire portion 20p has separated from the metal wire portion 20n). Figure 2(b) in particular shows an example where the thickness of the end portion 30 decreases uniformly towards the end edge 35.

[0026] Here, the molten portion of the metal wire 20n (the portion that later becomes the molten and solidified portion 31n) may aggregate due to the surface tension of the molten metal material, deforming into a spherical or other rounded shape before solidifying to form the terminal edge 35. For example, the wall thickness of the downstream portion of the terminal 30 gradually decreases towards the terminal edge, but there may be areas where the wall thickness locally increases near the terminal edge (the upstream portion of the terminal). Depending on the cutting conditions, the upstream portion of the terminal 30 may have a larger wall thickness than the downstream portion.

[0027] <Stretch marks> The terminal portion 30 has a stretch mark 37 indicating that the softened metal wire portion 20n was stretched toward the terminal edge 35 of the metal wire 20. Alternatively, the stretch mark 37 indicates that the softened metal material was cut as if torn toward the terminal edge 35. The softened portion is the part whose strength has been reduced due to heating during welding, and is the heat-affected zone. In order to give the metal wire 20 a predetermined winding shape, a predetermined tension is applied to the metal wire during winding. The stretch marks 37 indicate that the metal wire was cut by melting using the tension applied during winding. In other words, the stretch marks 37 are the result of the metal wire portion 20n, which has softened due to welding, being stretched and cut in the upstream direction (towards the supply side of the metal wire) by the tension acting on the metal wire portion 20n, and the resulting traces remaining on the metal wire portion 20n. The stretch marks 37 are distinguishable by visual inspection from the rolling marks left on other parts of the metal wire 20 because they are marks left by stretching.

[0028] <Molten and solidified area exposed> At least a portion of the molten and solidified portion 31n formed at the end portion 30 is exposed to the outside. In Figure 2(b), the exposed molten and solidified portion 31n is shown with diagonal lines. At least the portion of the molten and solidified portion 31n closer to the end edge 35 of the metal wire is exposed to the outside. The end edge 35 is the molten and solidified portion 31n. In this figure, the end edge 35 of the metal wire portion 20n is welded to the metal wire portion 20m, and the distance between the welded joint and the end edge 35 is zero. The molten and solidified portion 31n is exposed from the end edge 35 over a predetermined longitudinal length of the metal wire. The molten and solidified portion 31n formed within the widthwise range of the metal wire portion 20n is exposed to the outside. The exposed molten and solidified portion 31n constitutes the outer diameter surface of the end portion 30. This indicates that a portion of the wall thickness located on the outer diameter side of the metal wire portion 20n has been lost due to stretching and cutting. In particular, it indicates that the metal wire portion 20p has separated from the metal wire portion 20n along with the molten portion 32p, which is a part of the molten area that was melted during heating. Alternatively, it indicates that at least a portion of the heat-affected zone (non-molten area) formed on the surface of the metal wire portion 20n, near the terminal edge 35, has been torn off by welding. When the molten and solidified portion 31 is formed over the entire width of the metal wire portion 20n, the end portion 30 has a portion where the molten and solidified portion 31 is exposed over the entire width of the end portion 30. In particular, the portion of the molten and solidified portion 31 near the end edge 35 has the molten and solidified portion 31 exposed over the entire width. This indicates that the metal wire portion 20p has been torn along the longitudinal direction of the metal wire. The molten and solidified portions 31n and 31m are of a size that exhibits a bonding force capable of withstanding the tension acting on the metal wire portion 20n.

[0029] <Parts to be joined> The portion of the metal wire 20m that is joined to the terminal portion 30 is referred to as the joining target portion 21. The joining target portion 21 is explained as a concept that includes the portion that is joined to the terminal portion 30 (the portion to be joined) and the portion that overlapped with the metal wire portion 20n that becomes the terminal portion 30 and therefore had the potential to be joined to the metal wire portion 20n. The joining portion 21 has a molten and solidified portion 31m in which at least a part of the width direction w of the metal wire portion 20m has melted and solidified. In Figure 2(b), the exposed molten and solidified portion 31m is shown with diagonal lines. In this example, at least a portion of the molten and solidified portion 31m is exposed to the outside. That is, at least a portion of the molten and solidified portion 31n formed at the end portion 30 and at least a portion of the molten and solidified portion 31m formed at the joining target portion 21 are both exposed to the outside. The exposed molten and solidified portions 31n and 31m constitute the outer diameter surface of the winding body. This indicates that the metal wire portion 20p separated from the metal wire portion 20n along with a part of the molten portion 32 (molten portion 32p) that was melted during heating, exposing the molten and solidified portion 31m.

[0030] [Actual photo] Figure 3 shows a photograph of the end section of the filter. The thickness of the metal wire 20 used in this figure is 0.2 mm. The area to the right of arrow A in the figure is where the molten and solidified portion 31 is exposed. As shown in the figure, it can be seen that the characteristics shown in Figure 2(b) are also present in the actual photograph taken around the end portion 30 of the filter.

[0031] [Equipment for manufacturing windings] Figure 4 is a schematic diagram primarily showing the winding device among the manufacturing equipment for windings. Figure 5 is a schematic diagram showing the downstream side of the guide member in the winding body manufacturing apparatus. Figure 5 corresponds to the manufacturing apparatus shown in Figure 4, viewed from the left side of the diagram.

[0032] The winding body manufacturing apparatus 100 comprises at least a winding device 130 and a welding device 150.

[0033] The winding device 130 includes a spindle 131 that rotates in a certain direction at a predetermined speed, and a guide member 132 that feeds out the metal wire 20 toward the spindle 131 with a predetermined tension and guides the metal wire 20 by reciprocating along the axis Ax2 of the spindle 131 at a predetermined speed. The core rod 131 is generally cylindrical or cylindrical in shape and is typically made from a metal such as stainless steel, copper alloy, or aluminum alloy. Furthermore, a tension unit is positioned upstream of the winding device 130, and the tension unit applies a predetermined tension to the metal wire 20.

[0034] The welding device 150 joins and fixes the end of the winding of the metal wire 20 to the winding of the metal wire 20 at the appropriate location using resistance spot welding. The welding apparatus 150 includes an electrode (welding electrode) 160 that contacts the workpiece to be weld, pressurizes it, and passes a welding current I through the workpiece; a power supply 155 that supplies power to the electrode 160; and a contact electrode 157 connected to the power supply 155 and serving as a receptacle for the welding current I. The welding apparatus 150 also includes a welding head 151 that holds the electrode 160; a first driving means 153 that drives the welding head 151; and a second driving means 159 that moves the contact electrode 157 closer to or further away from the workpiece to be weld. In Figure 5, the tangent TL (of the spindle 131) is defined in the direction of the metal wire 20 extending from the guide member 132 toward the spindle 131, and the normal NL (of the spindle 131) is defined as a virtual line passing through the axis Ax2 and perpendicular to both the tangent TL and the axis Ax2. Furthermore, the X, Y, and Z axes are defined in the directions along the axis Ax2, the tangent TL, and the normal NL, respectively. Furthermore, with reference to the supply direction of the metal wire 20, the side with the guide member 132 is called the upstream side, and the side with the core rod 131 or the side already wound around the core rod 131 is called the downstream side. In this example, the welding apparatus 150 applies pressure to the electrode 160 in the direction normal NL to the core rod 131.

[0035] The first driving means 153 moves the welding head 151 holding the electrode 160 back and forth along the axis Ax2 direction (X direction) of the spindle 131, back and forth in the tangential TL direction (Y direction) of the spindle 131, and moves it closer to or further away from the spindle 131 in the Z direction in the figure. The first driving means 153 drives the electrode 160 in the XY direction to move the electrode 160 to the point where the metal wire portion 20n and the metal wire portion 20m overlap. The first driving means 153 preferably includes a servo motor or a stepping motor as a means for moving the electrode 160 in the XY direction. If the electrode 160 can be precisely positioned in at least the XY direction by the servo motor or stepping motor, an air cylinder that does not require positioning accuracy may be used as a means for reciprocating the electrode 160 in the Z direction. The first driving means 153 drives the welding head 151 along the normal direction NL to pressurize the workpiece with the electrode 160. The welding head 151 holds the electrode 160 with its central axis Ax3 aligned with the pressurizing direction P, but the welding head 151 can hold the electrode 160 with its central axis Ax3 tilted relative to the pressurizing direction P as needed. The power supply 155 supplies welding current I to the electrode 160 while appropriately controlling the magnitude of the welding current I, the current application time, the application cycle, and the waveform. Suitable and well-known components are used for the contact electrode 157 and the second driving means 159. The shape of electrode 160 will be described later.

[0036] [Method of manufacturing a filter] To manufacture the filter 10, first, one end (start end, winding start) of the metal wire 20 is secured to a suitable position on the core rod 131 that constitutes the winding device 130. With a tension of 0.01 to 20 [kgf] applied to the metal wire 20, the core rod 131 is rotated at a predetermined speed in a constant direction around its central axis Ax2, while the guide member 132 that supplies the metal wire 20 is moved back and forth at a predetermined speed along the central axis Ax2 of the core rod 131. Through this operation, the metal wire 20 is wound around the outer circumference of the core rod 131 in a spiral and multi-layered manner at a predetermined pitch, while being inclined at a predetermined angle θ with respect to the central axis Ax2. In addition, the metal wires (parts of the metal wires) constituting adjacent wire layers intersect with each other to form a mesh. Furthermore, each mesh overlaps in a regular arrangement in the radial direction, achieving the set desired filtration accuracy. For example, in the first metal wire layer that is directly wrapped around the outer circumference of the core rod 131, if each metal wire 20 is inclined clockwise by a predetermined angle θ with respect to the axial direction of the core rod 131, then the metal wires 20 constituting the second metal wire layer that is wrapped around the outer circumference of the first metal wire layer are inclined counterclockwise by a predetermined angle θ with respect to the axial direction of the core rod 131. After the metal wires 20 have been wrapped a predetermined number of times (a predetermined number of layers), the rotation of the core rod 131 is stopped, and the other end (end, winding end) of the metal wires 20 is joined and fixed to the appropriate place on the already wound metal wires 20 by resistance spot welding.

[0037] The welding apparatus 150 brings the electrode 160 and the contact electrode 157 into contact with the winding body 11. The power supply 155 applies a predetermined welding current I while the electrode 160 is pressing the metal wire portion 20n against the metal wire portion 20m with a predetermined pressure, as shown in Figure 8(a), etc. The welding current I is set to a current greater than the current sufficient to join the metal wire portions together. The metal wire portion 20n is welded to the metal wire portion 20m while the tension Tp that was applied during winding continues to be applied. The welding current I is set to a magnitude that melts the metal wire portion 20n to the extent that it can no longer withstand the tension.

[0038] The portion of the metal wire located directly below the electrode 160 is cut by the tension acting on that portion. The portion of the metal wire 20p located upstream of the electrode 160 is separated from the winding body 11 while the electrode 160 is energized. At this time, the metal wire 20p is separated from the winding body 11 such that a molten and solidified portion 31n (see Figure 2) of sufficient size to exert a bonding force capable of withstanding the tension acting on the metal wire portion 20n remains on the winding body 11 side. Since the metal wire is cut using the tension acting on the metal wire, the electrode 160, the core rod 131, and the tension unit do not move during cutting, and the electrode 160 remains fixed in place, holding down the welded portion. Furthermore, since the metal wire is cut by melting using the tension acting on the metal wire, welding and cutting can be performed simultaneously, simplifying the manufacturing process.

[0039] After the metal wire is cut, the power supply 155 stops supplying power. The electrode 160 maintains a pressurized state until the molten portion 32 of the metal wire sections 20n and 20m cools and resolidifies. After the molten portion 32 has cooled and resolidified, the electrode 160 and contact electrode 157 are separated from the winding body 11, and the winding body 11 is removed from the core 131.

[0040] For cutting metal wire, it is desirable to utilize the tension that has been continuously applied to the metal wire since the time of wrapping. However, if it is possible to cut the metal wire, since the welded area is fixed by the electrode 160, the tension applied to the metal wire located upstream of the electrode 160 may be controlled to be greater at the time of cutting than at the time of wrapping. If the tension is to be changed between the time of wrapping and the time of cutting, the tension of the metal wire is adjusted in the tension unit located upstream of the guide member 132. The above embodiment is an example in which the current is stopped after the metal wire is cut, but the metal wire portion 20p may be separated from the winding body 11 after the current to the electrode 160 is stopped and while the electrode is pressurizing the metal wire.

[0041] The angle (winding angle) of the metal wire 20 with respect to the axial direction of the core rod 131, and the spacing (pitch) between adjacent metal wires 20 in the axial direction, can be changed by appropriately adjusting the ratio of the rotational speed of the core rod 131 to the movement speed of the guide member 132. By appropriately changing the thickness of the metal wire, the winding angle, the pitch, and the number of windings, the pressure loss of the fluid passing through the filter can be controlled to an appropriate value. The inner diameter of the filter 10 is equivalent in size to the outer diameter of the core rod 131, and the outer diameter of the filter 10 is adjusted appropriately according to the thickness of the metal wire 20 and the number of turns. The windings manufactured by the above method are used as filters in their original state without undergoing sintering treatment on the entire structure. Alternatively, if necessary, the winding body removed from the core 131 may be subjected to heat treatment such as sintering to metallurgically join the contact points where adjacent metal wire portions are in contact with each other, and then used as a filter.

[0042] [Electrode shape] Figure 6 is a perspective view showing an example of an electrode. Figures 7(a) and 7(b) are plan views illustrating the relationship between the electrode tip surface and the metal wire in contact with the electrode tip surface.

[0043] The electrode 160 has an electrode tip surface 161 that can come into contact with the metal wire during welding. The electrode tip surface 161 has a shape and size that allows it to cover the entire width of the metal wire 20 over a predetermined longitudinal length of the metal wire. That is, the electrode tip surface 161 has a first length Le1 that can cover the entire width (length W) of the metal wire during welding, and a second length Le2 that covers a predetermined longitudinal length of the metal wire and is longer than the first length. However, the length Le1 of the electrode tip surface 161 is set to a length that does not come into contact with other metal wire portions that are not to be welded. The "other metal wire portions that are not to be welded" referred to here are metal wire portions that extend in the same direction as the metal wire portion 20n (terminus portion 30) that comes into contact with the electrode tip surface 161, and which constitute the outer diameter surface of the winding body 11 (are exposed on the outer diameter side) and are adjacent to the terminus portion 30 in the axial direction of the winding body 11, and do not necessarily mean that they are metal wire portions belonging to the wire layer Ln (see Figure 1).

[0044] The length Le1 of the electrode tip surface 161 is set to a length that allows the entire width of the metal wire 20 to be melted and the metal wire to be reliably cut. Therefore, the length Le1 is set to be longer than the width of the metal wire 20 w. The length Le2 of the electrode tip surface 161 is set to form a molten portion capable of melting the metal wire portion located upstream of the electrode 160, and to leave a molten portion on the winding body side necessary for fixing the end of the metal wire 20 after the upstream metal wire portion has been separated. Since the entire width of the metal wire portion 20n can be melted and joined to the metal wire portion 20m, the joint strength can be ensured. The electrode 160 shown in the figure is a rectangular parallelepiped with a roughly rectangular electrode tip surface 161, but the shape of each part of the electrode 160 is not limited to this. Also, although the figure shows an electrode with an electrode tip surface 161 perpendicular to the central axis Ax3, the central axis Ax3 and the electrode tip surface 161 do not have to be perpendicular (e.g., Figure 9(b)).

[0045] As long as the electrode 160 can separate the portion of the metal wire 20 located upstream of it, and the remaining portion of the metal wire 20 can be fixed to the winding body, the metal wire 20 may take any orientation (angle) within the electrode tip surface 161. For example, if the electrode tip surface 161 is rectangular, the metal wire 20 may be brought into contact with the electrode tip surface 161 such that the longitudinal direction of the metal wire 20 coincides with the longitudinal direction (length Le1 direction) of the electrode tip surface 161, as shown in Figure 7(a). Alternatively, as shown in Figure 7(b), the metal wire 20 may be tilted so that its longitudinal direction does not coincide with the longitudinal direction (length Le1 direction) of the electrode tip surface 161, and then brought into contact with the electrode tip surface 161. The same applies when the electrode tip surface is not rectangular. Thus, the electrode 160 only needs to be able to apply pressure to the metal wire 20 while the longitudinal direction of the metal wire 20 is generally aligned with the longitudinal direction of the electrode tip surface 161.

[0046] [Pressurization of metal wire by electrodes] Figures 8 to 10 are schematic diagrams showing the state of a metal wire immediately before it is cut. These diagrams show the state in which a molten area is formed by applying pressure to the metal wire, which is the workpiece to be welded, with electrodes and passing an electric current through the electrodes.

[0047] <Pressure applied to metal wire by electrodes 1> The electrode 160 shown in Figures 8(a) and 8(b) corresponds to the electrode in Figure 6, and is an electrode having an electrode tip surface 161 perpendicular to the central axis Ax3.

[0048] Figure 8(a) shows the welding of the metal wire portions 20n and 20m by applying pressure to the electrode 160 in the direction P along the central axis Ax3, with the central axis Ax3 and normal NL of the electrode 160 aligned. The molten portion 32 is formed evenly on the upstream side (right side in the figure) and the downstream side (left side in the figure) with the normal NL as the center. Although the molten portion 32 shown in the illustration does not reach the outer diameter surface of the metal wire portion 20n, depending on the welding conditions, including the magnitude of the welding current I, the metal wire portion 20n may be melted up to the outer diameter surface, and the molten portion 32 may come into contact with the electrode tip surface 161. Similarly, in Figures 8(b) to 10, the metal wire portion 20n may also be melted up to the outer diameter surface.

[0049] The metal wire 20 is melted and cut upstream of the molten section 32 by the tension Tp acting in its longitudinal direction. The metal wire portion 20p located upstream of the electrode 160 is then separated from the winding body 11. The tension Tn=Tp also acts on the metal wire portion 20n located downstream of the electrode 160, but because the unraveling force has a component in the Z direction and is pressurized in the Z direction by the electrode 160, it does not melt and cut downstream of the molten section 32 (to the left of the normal NL in the figure), and this portion is ultimately joined to the winding body 11 to become the terminal portion 30.

[0050] Since spot welding is performed with tension applied to the metal wire 20, when the electrode 160 starts applying pressure, the same tension Tp=Tn acts on the upstream and downstream sides of the molten portion 32. Therefore, in this example where the molten portion 32 is formed evenly on both the upstream and downstream sides of the normal NL, there is a possibility that the metal wire 20 may be cut at both the downstream and upstream sides of the molten portion 32. To prevent such a situation, in Figure 8(a), it is desirable to operate the tension unit so that the tension Tp > Tn after the electrode 160 pressurizes the metal wire portions 20n and 20m. By doing so, the downstream side of the molten portion 32 and the unmolten portion in the metal wire portion 20n are not torn off by the tension Tn acting on the metal wire portion 20n, and the metal wire portion 20p can be separated from the winding body 11.

[0051] Figure 8(b) shows the welding of metal wires 20n and 20m by applying pressure to the electrode 160 in the direction P along the central axis Ax3, with the central axis Ax3 of the electrode 160 positioned downstream of the normal NL. In this figure, the normal NL is located outside the electrode tip surface 161, but the electrode 160 may be positioned so that the normal NL is located within the plane of the electrode tip surface 161. Since the central axis Ax3 of electrode 160 is positioned downstream of the normal NL, the pressure applied to the metal wire sections 20n and 20m by electrode 160 is relatively large upstream of electrode 160 and relatively small downstream of electrode 160. This pressure changes continuously depending on the distance from the normal NL.

[0052] At the upstream end of electrode 160, sufficient pressure reduces the electrical resistance between the metal wire sections 20n and 20m, allowing the welding current I to flow efficiently. At the downstream end of electrode 160, the pressure is lower than at the upstream end, resulting in higher electrical resistance. Consequently, the welding current I flowing between the metal wire sections 20n and 20m is lower than at the upstream end. The molten area 32 formed between the metal wire sections 20n and 20m is relatively large at the upstream end and relatively small at the downstream end. Therefore, it becomes easier to cut the metal wire section 20p located at the upstream end of electrode 160, while preventing unnecessary cutting of the metal wire section 20n located at the downstream end of electrode 160, thereby ensuring the necessary joint strength between the metal wire sections 20n and 20m.

[0053] Since the metal wire 20 almost always has an oxide film formed on its surface, by utilizing the fact that the pressurizing force is relatively large in the upstream portion of the electrode 160, the oxide film of the metal wire can be destroyed in the upstream portion of the electrode 160, and the electrical resistance in that portion can be effectively reduced.

[0054] Furthermore, depending on the distance between the central axis Ax3 and the normal NL, and the pressure applied by the electrode 160 to the metal wire 20, it is possible to prevent the welding current I from flowing in the downstream portion of the electrode tip surface 161. In this case, the non-conducting portion of the electrode tip surface 161 functions as a pressurizing cooling section that cools the metal wire portions 20n and 20m while pressing them. Conversely, the conductive portion of the electrode tip surface 161 functions as a pressurizing current-conducting section that conducts current while applying pressure to the metal wire portions 20n and 20m. The pressurizing cooling section presses the metal wire portions 20n and 20m, and holds the metal wire portion 20n so that it does not separate from the metal wire portion 20m due to the tension Tn acting on the metal wire portion 20n.

[0055] <Pressurization of metal wire by electrodes 2> Figures 9(a) and (b) show an example of applying pressure to the metal wire portions 20n and 20m with the electrode tip surface 161 tilted with respect to the tangent TL.

[0056] Figure 9(a) shows an example of using an electrode 160 having an electrode tip surface 161 perpendicular to the central axis Ax3, as shown in Figure 6. In this example, the pressurizing direction P coincides with the direction of the normal NL, and the intersection of the electrode tip surface 161 and the central axis Ax3 lies on the normal NL. However, because the central axis Ax3 of electrode 160 is tilted upstream by an angle φ with respect to the normal NL, the pressure applied to the metal wire portions 20n and 20m by electrode 160 is higher upstream of electrode 160 and lower downstream. Therefore, for the same reasons as in Figure 8(b), the molten portion 32 formed between the metal wire sections 20n and 20m is relatively large on the upstream side and relatively small on the downstream side. This example achieves the same effect as in Figure 8(b). The direction of pressure P may also be aligned with the direction of the central axis Ax3.

[0057] Figure 9(b) shows an example of using an electrode 160 having an electrode tip surface 161 that is not perpendicular to the central axis Ax3. In this electrode 160, the axis Ax4 perpendicular to the electrode tip surface 161 is inclined upstream by an angle λ with respect to the central axis Ax3. In this example, the pressurizing direction P coincides with the direction of the normal NL, and the intersection of the electrode tip surface 161 and the central axis Ax3 lies on the normal NL. However, because the upstream portion of the electrode tip surface 161 protrudes toward the tip of the electrode 160, the pressure applied to the metal wire by the electrode 160 is greater upstream of the electrode 160 and smaller downstream. Therefore, for the same reasons as in Figure 8(b), the molten portion 32 formed between the metal wire sections 20n and 20m is relatively large on the upstream side and relatively small on the downstream side. This example achieves the same effect as in Figure 8(b). The direction of pressure P may also be aligned with the direction of axis Ax4.

[0058] <Pressurization of metal wire by electrodes 3> The electrode 160 shown in Figures 10(a) and (b) is equipped with a pressurized current-conducting section 163 at the upstream end that pressurizes and energizes the metal wire portions 20n and 20m, and a pressurized cooling section 165 at the downstream end that presses and cools the metal wire portions 20n and 20m.

[0059] The electrode 160 shown in Figure 10(a) is integrally constructed from a conductor. The pressurized current-carrying portion 163 protrudes further toward the tip of the electrode 160 than the pressurized cooling portion 165. A step 164 is formed between the pressurized current-carrying portion 163 and the pressurized cooling portion 165. The electrode tip surface 161 on the pressurized current-carrying portion 163 side and the electrode tip surface 161 on the pressurized cooling portion 165 side are both roughly rectangular in shape and are flat surfaces perpendicular to the central axis Ax3. This figure shows the welding process where the metal wires 20n and 20m are welded together by applying pressure to the electrode 160 in the direction P along the central axis Ax3, with the central axis Ax3 and the normal NL aligned. Because the pressurized current-carrying section 163 protrudes toward the tip of the electrode 160, even if the central axis Ax3 of the electrode 160 and the normal NL are aligned, the force with which the pressurized current-carrying section 163 presses the metal wire can be greater than the force with which the pressing and cooling section 165 presses the metal wire. Because there is a step between the pressurized current-carrying section 163 and the pressing and cooling section 165, the pressing force with which the pressurized current-carrying section 163 presses the metal wire and the pressing force with which the pressing and cooling section 165 presses the metal wire can be made to differ in stages (discontinuously). In addition, the central axis Ax5 of the pressurized current-carrying section 163 is upstream of the normal NL. Therefore, in the pressurized current-carrying section 163, sufficient pressure reduces the electrical resistance between the metal wire sections 20n and 20m, allowing the welding current I to flow efficiently. In the pressing and cooling section 165, the pressing force is significantly smaller than in the pressurized current-carrying section 163, resulting in higher electrical resistance and preventing the welding current I from flowing.

[0060] The electrode 160 forms a molten portion 32 only between the metal wire portions 20n and 20m on the pressurized current-carrying portion 163 side. The pressure cooling portion 165 cools the metal wire portions 20n and 20m while pressing them. The pressure cooling portion 165 presses the metal wire portions 20n and 20m and holds them in place by the tension Tn acting on the metal wire portion 20n so that it does not separate from the metal wire portion 20m. Therefore, it is possible to melt and cut only the portion of the metal wire 20 located upstream of the electrode 160. Since the metal wire 20 almost always has an oxide film formed on its surface, the oxide film of the metal wire can be destroyed in the pressurized and energized section 163, which is the side with the greater pressure, and the electrical resistance in that section can be effectively reduced.

[0061] The electrode 160 shown in Figure 10(b) includes an insulating member 167 positioned between the pressurized current-carrying section 163 and the pressing and cooling section 165. The tip surface of the electrode 160 is a flat surface perpendicular to the central axis. The tip surface on the pressurized current-carrying section 163 side is a conductive electrode tip surface 161, and the tip surface on the pressing and cooling section 165 side is a non-conductive pressing surface 169. The pressurized current-carrying section 163 and the pressure-cooling section 165 can be made from the same material. It is preferable that the pressure-cooling section 165 be made from a material with high thermal conductivity. Furthermore, by making the pressure-cooling section 165 itself from an insulator, the insulating member 167 can be omitted. This figure shows the welding process where the metal wires 20n and 20m are welded together by applying pressure to the electrode 160 in the direction P along the central axis Ax3, with the central axis Ax3 and the normal NL aligned. The molten portion 32 is formed only in the metal wire portions 20n and 20m on the pressurized and energized portion 163 side. The function of the pressure cooling unit 165 is the same as that of the electrode shown in Figure 10(a).

[0062] In this example, only the portion of the metal wire 20n located upstream of the electrode 160 can be cut by melting. In addition, similar to Figure 10(a), the pressurized current-carrying section 163 may be made to protrude further forward than the pressing and cooling section 165.

[0063] 〔effect〕 In this embodiment, the filter 10 is cut at the point where the end portion 30 is welded. That is, during the manufacture of the filter 10, welding and cutting of the end portion 30 are performed simultaneously. Therefore, according to this embodiment, it is possible to provide a winding body in which the distance from the weld to the end edge is as short as possible without increasing the number of manufacturing steps. By making the distance from the weld to the end edge as short as possible, especially zero, a winding body is manufactured in which the end of the metal wire does not damage other parts, and the occurrence of defective winding bodies with peeled-off welds can be prevented.

[0064] [Summary of Embodiments, Functions, and Effects of the Invention] <Wound body> <<First Embodiment>> This embodiment is a porous winding body (filter 10) in which at least one continuous metal wire 20 is wound in a spiral and multi-layered manner. In the winding body, the terminal portion 30 of the metal wire (metal wire portion 20n) is resistance spot welded to the other portion of the metal wire (metal wire portion 20m), and the welded portion is cut off. Here, the terminal portion is defined as the portion closer to the terminal edge 35 than the indentation 33 of the welding electrode. According to this embodiment, a winding body is provided in which the distance from the weld to the end edge is minimized without increasing the number of manufacturing steps. It is also possible for the end edge to be the weld. Such a wound body has external features as shown in the third to eleventh embodiments, which are traces related to the cutting of the metal wire.

[0065] <<Second Embodiment>> This embodiment is a porous winding body (filter 10) in which at least one continuous metal wire 20 is wound in a spiral and multi-layered manner. In the winding body, the terminal portion 30 of the metal wire (metal wire portion 20n) is resistance spot welded to the other portion of the metal wire (metal wire portion 20m), and is cut at the welded location, and the heat-affected zone near the welded location is torn off. Here, the terminal portion is defined as the portion closer to the terminal edge 35 than the indentation 33 of the welding electrode. According to this embodiment, a winding body is provided in which the distance from the weld to the end edge is minimized without increasing the number of manufacturing steps. It is also possible for the end edge to be the weld. Such a wound body has external features as shown in the third to eleventh embodiments, which are traces related to the cutting of the metal wire.

[0066] <<Third Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) is characterized by having a molten and solidified portion 31n formed after the entire widthwise direction of the metal wire has melted and then solidified. More specifically, the molten and solidified portion is formed over a predetermined longitudinal length from the terminal edge of the metal wire. According to this embodiment, since the entire width is melted, the metal wire can be reliably cut at that point. Furthermore, since the end portion is joined to the other part of the metal wire by melting its entire width, the joint strength can be ensured.

[0067] <<Fourth Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) is characterized in that the thickness of the metal wire gradually decreases toward the terminal edge 35 of the metal wire. The external features of the winding body according to this embodiment indicate that a portion of the thickness of the metal wire near the end, particularly on the outer diameter side, was not retained on the winding body due to melting. These external features also appear when the end is stretched in the direction of the end edge due to melting or softening. Since metal wires cannot be cut at the welded point with pliers or scissors, the features of this embodiment are not present in cutting methods that utilize shear force with pliers or scissors. In other words, if the metal wire is not cut at the spot-welded point, the entire indentation remains on the metal wire, so when the metal wire is cut with pliers or scissors, the wall thickness does not gradually decrease towards the end.

[0068] <<Fifth Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) is characterized by having an elongation mark 37 formed thereon, indicating that the softened metal wire has been stretched toward the terminal edge 35. To form a predetermined winding shape from a metal wire, a specific tension is applied to the wire during winding. The stretch marks indicate that the metal wire was cut by melting using the tension applied during winding.

[0069] <<Sixth Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) has a molten and solidified portion 31n formed when at least a part of the metal wire in the width direction has melted and then solidified, and at least a part of the molten and solidified portion is exposed to the outside. Normally, in spot welding, the molten and solidified area that is visible externally indicates a welding defect; therefore, when spot welding is performed, the molten and solidified area is generally not exposed to the outside. However, in this embodiment, since the metal wire is being cut by melting, at least a portion of the molten and solidified area is exposed to the outside.

[0070] <<Seventh Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) has a molten and solidified portion 31n formed when at least a part of the metal wire in the width direction has melted and then solidified, the terminal edge 35 of the metal wire is a molten and solidified portion, and the molten and solidified portion is exposed to the outside over a predetermined longitudinal length of the metal wire from the terminal edge. In this embodiment, since the metal wire is cut by melting, the molten and solidified portion is exposed to the outside. Because a portion of the molten portion that melts during heating is separated from the winding body, the molten and solidified portion is exposed to the outside over a predetermined longitudinal length from the end edge.

[0071] <<Eighth Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) has a molten and solidified portion 31n formed when at least a part of the width direction of the metal wire has melted and then solidified, and at least a part of the molten and solidified portion is exposed to the outside, and the portion of the molten and solidified portion that is exposed to the outside has a portion in which the thickness gradually decreases toward the terminal edge 35 of the metal wire. The external features of the winding body according to this embodiment indicate that the terminal portion is extended in the direction of the terminal edge, and that a portion of the thickness of the metal wire near the terminal portion, located on the outer diameter side, was not retained on the winding body side due to melting. These characteristics do not appear when metal wire is cut using shearing force, such as with scissors or pliers.

[0072] <<Ninth Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) and the other portion of the metal wire (metal wire portion 20m) each have a molten and solidified portion 31 (31n, 31m) formed after melting, and at least a part of the molten and solidified portion 31m formed on the other portion of the metal wire is exposed to the outside. The above-mentioned feature of the winding body according to this embodiment indicates that the upstream metal wire portion 20p separated from the metal wire portion 20n along with a part of the molten portion (molten portion 32p) that was melted during heating.

[0073] <<Tenth Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 (metal wire portion 20n) and the other portion of the metal wire (metal wire portion 20m) each have a molten and solidified portion 31 (31n, 31m) formed after melting, and at least a part of the molten and solidified portion 31n formed at the terminal portion and at least a part of the molten and solidified portion 31m formed at the other portion of the metal wire are both exposed to the outside. The above-mentioned feature of the winding body according to this embodiment indicates that the upstream metal wire portion 20p is separated from the metal wire portion 20n along with a part of the molten portion (molten portion 32p) that was melted during heating. Furthermore, in this embodiment, since the metal wire is cut by melting, the molten and solidified portion 31n is exposed to the outside.

[0074] <<Eleventh Embodiment>> In the winding body (filter 10) according to this embodiment, the terminal portion 30 has a molten and solidified portion 31n formed after the metal wire 20 has melted and solidified, and the molten and solidified portion formed within the width of the metal wire portion 20n constituting the terminal portion is exposed to the outside. The molten and solidified portion exposed to the outside constitutes the outer diameter surface of the winding body. The external characteristics of the winding body according to this embodiment indicate that a portion of the thickness of the metal wire located on the outer diameter side near the end was not retained on the winding body side due to melting. Furthermore, at least the molten and solidified portion constituting the outer diameter surface of the winding body did not leak laterally.

[0075] <Manufacturing method for windings> <<Twelfth Embodiment>> This embodiment describes a method for manufacturing a porous winding body (filter 10) in which at least one continuous metal wire 20 is wound in a spiral and multi-layered manner. This embodiment includes a winding step of winding a metal wire around a core rod 131 in a spiral and multi-layered manner while applying a predetermined tension to the metal wire, and a welding step of welding the end portion of the winding of the metal wire (metal wire portion 20n, terminal portion 30) to the already wound metal wire portion 20m by resistance spot welding. The welding process is characterized by utilizing the tension continuously applied to the metal wire to cut the supply portion of the metal wire from the already wound portion. In this embodiment, the metal wire is cut by utilizing the tension acting on the metal wire, so welding and cutting can be performed simultaneously, simplifying the manufacturing process of the winding body. The tension applied to the metal wire during the cutting process may be the same as, or different from, the tension applied to the metal wire during the winding process. According to this embodiment, it is possible to provide a winding body in which the distance from the welded part to the terminal edge is as short as possible without increasing the number of manufacturing steps.

[0076] <<Thirteenth Embodiment>> In the manufacturing method according to this embodiment, when the side on which the metal wire 20 is supplied to the core 131 is the upstream side and the side on which the metal wire is already wound around the core is the downstream side, in the welding process, the welding electrode is brought into contact with the metal wire portion such that the pressing force on the metal wire portion 20n at the upstream side of the welding electrode 160 is greater than the pressing force on the metal wire portion at the downstream side of the welding electrode (Figures 8(b) to 10). According to this embodiment, the molten area is made larger in the upstream section where the applied pressure is high, and smaller in the downstream section where the applied pressure is low. As a result, it becomes easier to cut the metal wire portion in the upstream section. Furthermore, it is possible to prevent unnecessary cutting of the metal wire portion in the downstream section.

[0077] <<The Fourteenth Embodiment>> In the manufacturing method according to this embodiment, when the extending direction of the metal wire 20 supplied toward the core 131 is the tangential TL direction, and the normal NL of the core is a virtual line passing through the axis Ax2 of the core and perpendicular to both the tangential and the axis, the welding process is characterized in that the welding electrode 160 is positioned so that its central axis Ax3 is downstream of the normal, and with the directions of the normal and the central axis aligned, the metal wire (metal wire portion 20n) is pressed in the normal direction by the welding electrode and welded the end of the winding of the metal wire to the already wound metal wire portion 20m (Figure 8(b)). According to this embodiment, since the central axis of the welding electrode is positioned downstream of the normal, the pressing force at the upstream portion of the welding electrode can be made greater than the pressing force at the downstream portion of the welding electrode. Therefore, the same effects as those of the eleventh embodiment are achieved.

[0078] <<Fifteenth Embodiment>> In the manufacturing method according to this embodiment, when the extending direction of the metal wire 20 supplied toward the core 131 is the tangential TL direction, and the normal NL of the core is a virtual line passing through the axis Ax2 of the core and perpendicular to both the tangential and axial lines, the welding process is characterized in that the normals Ax3 and Ax4 of the electrode tip surface 161 of the welding electrode 160 are tilted toward the supply side of the metal wire compared to the normal NL of the core, and the metal wire is pressed by the welding electrode to weld the end of the winding of the metal wire to the already wound metal wire portion 20m. In this embodiment, by tilting the normal to the electrode tip surface, the pressing force at the upstream portion of the welding electrode is made greater than the pressing force at the downstream portion of the welding electrode. This example also achieves the same effect as the eleventh embodiment.

[0079] <Welding electrodes> <<The sixteenth embodiment>> The welding electrode 160 according to this embodiment is a welding electrode used when manufacturing a porous winding body (filter 10) in which at least one continuous metal wire 20 is wound around a rotating core 131, and the metal wire is wound in a spiral and multi-layered manner. The welding electrode 160 is characterized by having an electrode tip surface 161 having a first length Le1 that can cover the entire width of the metal wire during welding (Figures 6 to 10). According to this embodiment, the entire width of the metal wire can be melted, ensuring reliable cutting of the metal wire. According to this embodiment, a winding body with the shortest possible distance from the weld to the end edge can be provided without increasing the number of manufacturing steps. According to this embodiment, for example, the end portion 30 of the metal wire can be joined to the other portion of the metal wire (metal wire portion 20m) by melting its entire width, thus ensuring joint strength.

[0080] <<The seventeenth embodiment>> In the welding electrode 160 according to this embodiment, the electrode tip surface 161 has a second length Le2 that can cover a predetermined length in the longitudinal direction of the metal wire 20, and on one side in the second longitudinal direction, there is a pressurizing and energizing section 163 that pressurizes two overlapping metal wire portions 20n and 20m to be welded and energizes both metal wire portions, and on the other side in the second longitudinal direction, there is a pressing and cooling section 135 that presses and cools one metal wire portion in contact with the electrode tip surface (Figures 10 and 9(b)). According to this embodiment, the metal wire can be melted in the pressurized current-enhancing section while preventing it from being melted in the pressure-cooling section.

[0081] <<Eighteenth Embodiment>> In the welding electrode 160 according to this embodiment, the pressurized current-carrying portion 163 is characterized in that it protrudes further toward the tip of the welding electrode than the pressing and cooling portion 165 (Figures 10(a) and 9(b)). According to this embodiment, by making the pressurized current-carrying section protrude further toward the tip of the welding electrode than the pressurized cooling section, the pressure and melting area of ​​the metal wire portion by the pressurized current-carrying section can be increased, while the pressure and melting area of ​​the metal wire portion by the pressurized cooling section can be decreased. As a result, it becomes easier to cut the metal wire portion on the pressurized current-carrying section side. In addition, unnecessary cutting of the metal wire portion in the pressurized cooling section can be prevented.

[0082] <<The Nineteenth Embodiment>> In the welding electrode 160 according to this embodiment, the pressing and cooling section 165 is configured so that it is not energized (Figure 10(b)). According to this embodiment, the metal wire can be welded and cut in the pressurized current-enhancing section, while the metal wire can not be cut in the pressure-cooling section.

[0083] <Manufacturing equipment for windings> <<Twentieth Embodiment>> This embodiment is a manufacturing apparatus 100 for producing a porous winding body (filter 10) by winding at least one continuous metal wire 20 in a spiral and multi-layered manner. The manufacturing apparatus includes a core rod 131 that rotates in a certain direction at a predetermined speed and around which metal wire is wound in a spiral and multi-layered manner, and a welding apparatus 150 that welds the end portion of the metal wire (metal wire portion 20n) to the already wound metal wire portion 20m by resistance spot welding. The welding apparatus is characterized by comprising a welding electrode 160 (Figure) as described in any fourteenth to seventeenth embodiment. This manufacturing apparatus achieves the effects described in the fourteenth to seventeenth embodiments. [Explanation of Symbols]

[0084] L...wire layer, w...width of metal wire, t...thickness of metal wire, Le1, Le2...length of electrode tip surface, Tn, Tp...tension, Ax1...center axis of filter, Ax2...axis of core, Ax3...center axis of electrode, Ax4...axis perpendicular to electrode tip surface, Ax5...center axis of pressurized current-carrying section, 10...filter, 20...metal wire, 20n, 20m...metal wire portion, 20p...(separated) metal wire portion, 21...joining target portion (of metal wire portion 20m), 30...end portion, 31, 31n, 31m... 32...Molten part, 32p...(separated) molten part, 33...Indentation, 35...End edge, 37...Stretch mark, 100...Manufacturing device, 130...Wrapping device, 131...Core rod, 132...Guide member, 150...Welding device, 151...Welding head, 153...First driving means, 155...Power supply, 157...Contact electrode, 159...Second driving means, 160...Electrode (welding electrode), 161...Electrode tip surface, 163...Pressurized current supply part, 164...Step, 165...Pressure cooling part, 167...Insulating member, 169...Pressure surface

Claims

1. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, A winding body characterized in that the terminal portion of the metal wire is resistance spot welded to another portion of the metal wire, and the welded portion is cut off.

2. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to the other portion of the metal wire, A winding characterized in that it is cut at the welded portion and the heat-affected zone near the welded portion is torn off.

3. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The winding body is characterized in that the terminal portion has a molten and solidified portion formed when the entire widthwise portion of the metal wire is melted and then solidified over a predetermined longitudinal length range from the terminal edge of the metal wire.

4. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The aforementioned end portion is characterized in that the thickness of the metal wire gradually decreases toward the end edge of the metal wire.

5. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and the welded portion and the heat-affected zone near the portion are cut off. The winding body is characterized in that the terminal portion has an elongation mark indicating that the softened metal wire has been stretched toward the terminal edge.

6. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The winding body is characterized in that the terminal portion has a molten and solidified portion formed after at least a portion of the metal wire in the width direction has melted and solidified, and at least a portion of the molten and solidified portion is exposed to the outside.

7. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The winding body is characterized in that the terminal portion has a molten and solidified portion formed when at least a part of the width direction of the metal wire is melted and then solidified, the terminal edge of the metal wire is the molten and solidified portion, and the molten and solidified portion is exposed to the outside over a predetermined longitudinal length of the metal wire from the terminal edge.

8. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The end portion has a molten and solidified portion formed after at least a part of the width direction of the metal wire has melted, and at least a part of the molten and solidified portion is exposed to the outside, and the portion of the molten and solidified portion that is exposed to the outside has a portion in which the thickness gradually decreases toward the end edge of the metal wire.

9. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The winding body is characterized in that the terminal portion and the other portion of the metal wire each have a molten and solidified portion formed after melting, and at least a portion of the molten and solidified portion formed on the other portion of the metal wire is exposed to the outside.

10. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The winding body is characterized in that the terminal portion and the other portion of the metal wire each have a molten and solidified portion formed after melting, and at least a portion of the molten and solidified portion formed on the terminal portion and at least a portion of the molten and solidified portion formed on the other portion of the metal wire are both exposed to the outside.

11. A porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, The end portion of the metal wire is resistance spot welded to another part of the metal wire, and is cut at the welded portion, or at the welded portion and the heat-affected zone near the welded portion. The terminal portion has a molten and solidified portion formed after the metal wire has melted, A winding body characterized in that the molten and solidified portion formed within the width of the metal wire portion constituting the terminal portion is exposed to the outside.

12. A method for manufacturing a porous winding body in which at least one continuous metal wire is wound in a spiral and multi-layered manner, A winding step in which the metal wire is wound around a core in a spiral and multi-layered manner while a predetermined tension is applied to the metal wire, The process includes a welding step of welding the end portion of the metal wire to the already wound portion of the metal wire by resistance spot welding, A method for manufacturing a winding body, characterized in that, in the welding process, the tension continuously applied to the metal wire is used to cut the supply side portion of the metal wire from the already wound portion of the metal wire.

13. When the side on which the metal wire is supplied to the core is considered the upstream side, and the side on which the metal wire is already wound around the core is considered the downstream side, The method for manufacturing a winding body according to claim 12, characterized in that, in the welding step, the welding electrode is brought into contact with the metal wire portion such that the pressing force on the metal wire portion at the upstream side of the welding electrode is greater than the pressing force on the metal wire portion at the downstream side of the welding electrode.

14. When the direction in which the metal wire supplied toward the spindle extends is defined as the tangential direction, and a virtual line passing through the axis of the spindle and perpendicular to both the tangential and the axis is defined as the normal to the spindle, The method for manufacturing a winding body according to claim 13, characterized in that, in the welding step, the welding electrode is positioned so that its central axis is downstream of the normal, and with the direction of the normal and the central axis aligned, the metal wire is pressed in the direction of the normal by the welding electrode and welded the end portion of the winding of the metal wire to the already wound portion of the metal wire.

15. When the direction in which the metal wire supplied toward the spindle extends is defined as the tangential direction, and a virtual line passing through the axis of the spindle and perpendicular to both the tangential and the axis is defined as the normal to the spindle, The method for manufacturing a winding body according to claim 13, characterized in that, in the welding step, the normal of the electrode tip surface of the welding electrode is tilted toward the supply side of the metal wire than the normal of the core, and the metal wire is pressed by the welding electrode and welded the end portion of the winding of the metal wire to the already wound portion of the metal wire.

16. A welding electrode used in manufacturing a porous winding body in which at least one continuous metal wire is wound around a rotating core, the metal wire being wound in a spiral and multi-layered manner, A welding electrode characterized by having an electrode tip surface having a first length that can cover the entire width of the metal wire during welding.

17. The electrode tip surface has a second length that can cover a predetermined length in the longitudinal direction of the metal wire, The welding electrode according to claim 16, characterized in that one side in the second longitudinal direction is provided with a pressurizing and energizing section that pressurizes two overlapping metal wire sections to be welded while energizing both metal wire sections, and the other side in the second longitudinal direction is provided with a pressing and cooling section that presses and cools the metal wire section in contact with the electrode tip surface.

18. The welding electrode according to claim 17, characterized in that the pressurized current-carrying portion protrudes further toward the tip of the welding electrode than the pressing and cooling portion.

19. The welding electrode according to claim 17, characterized in that the pressing cooling section is configured so as not to be energized.

20. A manufacturing apparatus for producing a porous winding body by winding at least one continuous metal wire in a spiral and multi-layered manner, A core that rotates in a certain direction at a predetermined speed, and around which the metal wire is wound in a spiral and multi-layered manner, The welding apparatus includes a welding device for welding the end portion of the metal wire to the already wound portion of the metal wire by resistance spot welding, The welding apparatus is a manufacturing apparatus characterized by comprising a welding electrode as described in any one of claims 16 to 19.

Images