Joint structure, manufacturing method thereof, and sheathing for electric wire

Abstract

Provided are: a joining structure making it possible to join resin plates together without needing to provide a surplus resin plate section for joining, and offering excellent workability in the joining together of resin plates; a method of producing same; and a wire exterior cover using the joining structure.　A joining structure 1 comprises a joining part 10 formed by butt-welding a plate surface part 22 of a first resin plate 21 made of a first resin, and an end surface part 24 of a second resin plate 23 made of a second resin. In the joining structure, a foam resin is used for the first resin and a foam resin or a non-foam resin is used for the second resin. The joining part 10 has a welding recess 25 in a surface 22a of the plate surface part 22. In an internal corner 10a of a reverse surface 22b, there is a padding section 27 formed by melt-flowing and solidifying of at least the first resin out of the first resin and the second resin.

Description

[Technical Field]

[0001] The present invention relates to a joint structure, a method for manufacturing the same, and an outer casing for an electric wire. [Background technology]

[0002] An electric wire outer casing is used around a wire harness that is routed in a vehicle, etc., to protect the wire harness from external forces. The electric wire outer casing protects the electric wire from external forces by covering the outer periphery of the electric wire.

[0003] As an example of an electric wire sheathing that protects such a wire harness, Patent Documents 1 and 2 describe an electric wire sheathing that is attached to the outer periphery of an electric wire and that is made by folding a thermoplastic resin foam sheet to form a cylindrical housing portion.

[0004] Of these, the wire sheathing of Patent Document 1 has a plurality of wall portions that extend along the extension direction of the wire and form a storage section that stores the wire, and these multiple wall portions have an outer cover wall portion, an inner cover wall portion that overlaps and is joined to the outer cover wall portion, and side wall portions adjacent to both ends of the inner cover wall portion, and are configured so that the inner cover wall portion is supported by the side wall portions at both ends.

[0005] In addition, in the wire sheathing of Patent Document 2, the wall portion constituting the housing portion includes a first wall portion having a protrusion formed therein and a second wall portion having a hole formed therein. Here, the housing portion is configured so that at least one of the protrusion and the hole deforms and the protrusion is inserted into the hole, thereby engaging the first wall portion with the second wall portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-13107 [Patent Document 2] Japanese Patent Publication No. 2020-89041 Summary of the Invention [Problem to be solved by the invention]

[0007] In the wire sheathing described in Patent Documents 1 and 2, a cylindrical storage section is formed by overlapping and joining the surfaces of resin plates such as thermoplastic resin foam sheets, or by engaging protrusions and holes formed in the resin plates.

[0008] In this regard, if resin plates could be joined without overlapping their plate surfaces, the area of ​​the resin plates required to form a joined structure such as an electric wire outer casing could be reduced, which would be desirable in terms of reducing material costs.Furthermore, if resin plates could be joined without forming protrusions and holes in the resin plates, it would be desirable in terms of reducing the number of work steps when forming a joined structure such as an electric wire outer casing, which would improve workability.

[0009] This is not limited to the wire sheathing, but also applies to other joined structures in which a first resin made of a foamed resin is joined to a second resin made of a non-foamed resin or a foamed resin.

[0010] An object of the present invention is to provide a joint structure that allows resin plates to be joined together without providing an extra resin plate portion for joining, and that is also easy to work with when joining the resin plates, a method for manufacturing the same, and an outer casing for an electric wire that uses the joint structure. [Means for solving the problem]

[0011] The inventors discovered that a joined structure can be achieved by providing a welding recess on the surface of the first resin plate at a joint formed by welding a plate surface portion of a first resin plate made of a first resin to an end surface portion of a second resin plate made of a second resin while butting them together, and by providing a built-up portion at an inside corner of the back surface where at least the first resin of the first and second resins melts, flows, and solidifies, thereby making it possible to join resin plates with excellent workability without overlapping the plate surfaces of the resin plates, and thereby completing the present invention.

[0012] That is, the gist of the present invention is as follows. (1) A joined structure having a joint formed by welding a plate surface portion of a first resin plate made of a first resin and an end surface portion of a second resin plate made of a second resin in a butted state, wherein the first resin is a foamed resin and the second resin is a non-foamed resin or a foamed resin, and the joint has a weld recess on the surface and a built-up portion at an inside corner on the back surface, formed by at least the first resin of the first and second resins melting, flowing, and solidifying. (2) The joined structure according to (1) above, wherein the minimum thickness of the first resin in the joined portion, measured at the bottom position of the welding recess, is in the range of 0.1 mm or more and 2.0 mm or less. (3) The joined structure according to (1) or (2) above, wherein the joint has a minimum thickness of 0.1 mm or more when measured from the position of the welding recess. (4) The butt angle between the plate surface portion of the first resin plate and the end surface portion of the second resin plate is The joint structure according to any one of (1) to (3) above, wherein the angle measured on the acute angle side is in the range of 45° to 90°. (5) The bonded structure according to any one of (1) to (4) above, wherein one or both of the first resin and the second resin contain a polypropylene resin. (6) An outer casing for an electric wire to be attached to the outer periphery of an electric wire, the outer casing for an electric wire comprising the joint structure according to any one of (1) to (5) above. (7) A wire harness with an exterior body, comprising: a wire harness; and the exterior body for electric wires according to (6) above, wherein the exterior body for electric wires is attached to the outer periphery of the wire harness. (8) A method for manufacturing a joined structure, the method comprising: a positioning step of positioning and holding an end surface of a second resin plate made of a second resin in a state where the end surface of the second resin plate is abutted against the back surface of a plate surface of a first resin plate made of a first resin; a welding horn pressing step of pressing a tip of a welding horn against the front surface side of the plate surface of the first resin plate in a state where the plate surface of the first resin plate is abutted against the end surface of the second resin plate; and a joint forming step of emitting ultrasonic waves from the welding horn to weld the plate surface of the first resin plate and the end surface of the second resin plate in a state where the plate surface of the first resin plate is abutted against the end surface of the second resin plate to form a joint, wherein the first resin is a foaming resin, the second resin is a non-foaming resin or a foaming resin, and the joint has a welding recess on the surface and a buildup portion at an internal corner of the back surface, formed by melting, flowing, and solidifying at least the first resin of the first and second resins. (9) The method for manufacturing a joint structure according to (8) above, wherein the tip of the welding horn is formed in a convex projection shape. (10) The method for manufacturing a joint structure according to (8) or (9) above, wherein at least a portion of the surface of the tip of the welding horn is curved. (11) A method for manufacturing a joint structure according to any one of (8) to (10) above, wherein at least a portion of the surface of the tip of the welding horn is formed with a plurality of projections and recesses. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a joint structure that allows resin plates to be joined together without providing an extra portion of the resin plate for joining, and that is also excellent in workability when joining the resin plates, a method for manufacturing the same, and an outer casing for an electric wire that uses the joint structure. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing the main parts of a bonded structure, including the bonded portion, where FIG. 1(a) is a plan view and FIG. 1(b) is a cross-sectional view (transverse cross-sectional view) taken along line aa in FIG. 1(a). [Figure 2]Figure 2 is a schematic plan view of a welding recess in a joint that constitutes a joint structure of various embodiments, where Figure 2(a) shows a case where the bottom surface of the welding recess is formed with a striped uneven shape, Figure 2(b) shows a case where the bottom surface of the welding recess is formed with an irregular uneven shape, and Figure 2(c) shows a case where the bottom surface of the welding recess is formed with a flat surface. [Figure 3] FIG. 3 is a plan view showing the shape of a welding recess in a joint of a joint structure according to another embodiment. [Figure 4] Figure 4 is a schematic diagram showing the main parts, including the joint, of a joint structure of another embodiment, where Figure 4(a) shows a case where the surface of the buildup portion of the joint is formed into a concave shape when viewed from the inside corner, and Figure 4(b) shows a case where the surface of the buildup portion of the joint is formed into a convex shape when viewed from the inside corner. [Figure 5] FIG. 5 is a schematic perspective view showing the structure of an outer casing for an electric wire. [Figure 6] FIG. 6 is a flow diagram of a method for manufacturing a bonded structure. [Figure 7] FIG. 7 is a diagram for explaining the method for manufacturing a joint structure, and is a conceptual diagram for explaining an example of the welding horn pressing step and the joint forming step. [Figure 8] Figure 8 is a conceptual diagram showing an example of the shape of the tip of a welded horn used in a manufacturing method of a joined structure of another embodiment, where Figure 8(a) shows a case where the tip of the welded horn has an uneven surface formed by knurling, Figure 8(b) shows a case where the tip of the welded horn has a convex protrusion and the tip surface of the protrusion has an uneven surface formed by blasting, and Figure 8(c) shows a case where the tip of the welded horn has a convex protrusion and the tip of the protrusion has a convex surface formed by filleting. [Figure 9] FIG. 9 is a view of the joined structure of Example 1 of the present invention, observed at a cross section perpendicular to both the first resin plate and the second resin plate. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, a joint structure and an outer casing for an electric wire according to some embodiments of the present invention will be described below.

[0016] FIG. 1 is a schematic diagram showing the main parts of a joined structure, including the joint, where FIG. 1(a) is a plan view and FIG. 1(b) is a cross-sectional view (a-a) of FIG. 1(a). FIG. 2 is a schematic plan view of a welded recess in a joint constituting a joined structure of various embodiments, where FIG. 2(a) shows a case where the bottom surface of the welded recess is formed with a striped uneven shape, FIG. 2(b) shows a case where the bottom surface of the welded recess is formed with an irregular uneven shape, and FIG. 2(c) shows a case where the bottom surface of the welded recess is formed with a flat surface. FIG. 3 is a plan view showing the shape of the welded recess in a joint of a joined structure of another embodiment. FIG. 4 is a schematic diagram showing the main parts of a joined structure of another embodiment, including the joint, where FIG. 4(a) shows a case where the surface of the welded portion of the joint is formed with a concave shape when viewed from the inside corner, and FIG. 4(b) shows a case where the surface of the welded portion of the joint is formed with a convex shape when viewed from the inside corner.

[0017] 1. Joint structure 1, the joined structure 1 has a joint 10 formed by welding a plate surface 22 of a first resin plate 21 made of a first resin to an end surface 24 of a second resin plate 23 made of a second resin in a butt-to-end state. In this joined structure 1, the first resin is a foamed resin, and the second resin is a non-foamed resin (solid resin) or a foamed resin. The joint 10 has a welding recess 25 on the front surface 22a of the plate surface 22 of the first resin plate 21, and a buildup portion 27 formed at an internal corner 10a formed on the back surface 22b of the plate surface 22 by melting, flowing, and solidifying at least the first resin of the first and second resins.

[0018] As a result, a welding recess 25 is formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and the first resin is extruded in the depth direction of the welding recess 25, melts and flows near the end surface portion 24 of the second resin plate 23, and is welded to the end surface portion 24 of the second resin plate 23, thereby increasing the bonding area between the end surface portion 24 of the second resin plate 23 and the plate surface portion 22 of the first resin plate 21. In particular, as the second resin that constitutes the end surface portion 24 of the second resin plate 23 melts together with the first resin that constitutes the plate surface portion 22 of the first resin plate 21, a layer of a mixture of the first resin and the second resin is formed at the boundary between the first resin plate 21 and the second resin plate 23, and the first resin plate 21 and the second resin plate 23 are joined by welding. Therefore, the first resin plate 21 and the second resin plate 23 can be joined by welding without joining the plate surfaces of the first resin plate 21 and the second resin plate 23, so it is possible to join the first resin plate 21 and the second resin plate 23 without providing any extra resin plate portion, and it is possible to provide a joined structure 1 that is easy to work with when joining them.

[0019] Here, "welding" refers to plastic welding. In this embodiment, it is preferable to use ultrasonic welding as the resin welding. Resin welding refers to a technique for joining multiple resin plates made of thermoplastic resin, or multiple locations on a single resin plate, by heating them above their melting point. Ultrasonic welding refers to a technique for melting and joining multiple resin plates, or multiple locations on a single resin plate, by using ultrasonic vibrations and pressure.

[0020] (Regarding the first and second resin plates) The first resin plate 21 and the second resin plate 23 are made of a first resin and a second resin, respectively.

[0021] Here, the first resin plate 21 and the second resin plate 23 may be made of the same resin plate or different resin plates. Of these, when the first resin plate 21 and the second resin plate 23 are made of the same resin plate, the first resin plate 21 and the second resin plate 23 are formed by bending a single resin plate. In this case, the first resin plate 21 is made of a plate surface portion of a resin plate, and the second resin plate 23 is made of an end surface portion of the same resin plate. This further reduces the number of parts that make up the joined structure 1, thereby further improving workability when forming the joined structure.

[0022] Of the first and second resins constituting the first and second resin plates 21 and 23, the resin type of at least the first resin is preferably a thermoplastic resin, such as polyethylene resin, polypropylene resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyamide resin, polyphenylene sulfide resin, polystyrene resin, polyvinyl chloride resin, polyvinyl acetate resin, polytetrafluoroethylene resin, acrylic resin, etc. Here, it is preferable that one or both of the first and second resins contain polypropylene resin.

[0023] The first resin and the second resin may be made of the same resin type or different resin types. In particular, when the first resin and the second resin are made of the same resin type, the bonding strength between the first resin plate 21 and the second resin plate 23 can be further increased.

[0024] The first resin and the second resin may contain various additives that are typically added to resins depending on the intended use. The additives may include, but are not limited to, one or more of fillers, antioxidants, stabilizers, flame retardants, metal deactivators, UV absorbers, light stabilizers, plasticizers, nucleating agents, compatibilizers, clarifying agents, antistatic agents, lubricants, and the like.

[0025] Of the first and second resins, at least the first resin is made of a foamed resin. As a result, when the resin is melted, air bubbles are expelled from the resin and the resin shrinks, making it difficult for the melted resin to spread in the plate surface direction of the first resin plate 21 and the second resin plate 23. At this time, particularly in the first resin plate 21, when forming the welding recess 25 in the first resin plate 21, the first resin is easily extruded in the depth direction of the welding recess 25. As a result, the welded resin is promoted to be solidified, and excessive melt flow of the resin is suppressed, making it difficult for the resin to leak out of the joint 10.

[0026] Here, the density of the foamed resin is not particularly limited, but is, for example, 200 kg / m 3 More than 1000kg / m 3 In particular, from the viewpoint of reducing the weight of applied products having the joint structure 1, such as an exterior body for an electric wire or a wire harness with an exterior body, and enhancing the buffering effect against mechanical shock, the density of the foamed resin is 1000 kg / m 3 Preferably, it is 700 kg / m or less. 3 More preferably, it is 500 kg / m or less. 3 On the other hand, the density of the foamed resin is preferably 200 kg / m or less from the viewpoint of ensuring the mechanical strength of the foamed resin and promoting the melt flow of the foamed resin when forming the welding recess 25. 3 It is preferable that this is equal to or greater than this.

[0027] On the other hand, the second resin constituting the second resin plate 23 may be made of a non-foaming resin or the above-mentioned foaming resin. In particular, by making the second resin of a non-foaming resin, the bonding strength between the first resin plate 21 and the second resin plate 23 can be further increased.

[0028] The plate thickness dimension t1 of the first resin plate 21 and the plate thickness dimension t2 of the second resin plate 23 are not particularly limited, but for example, in order to further improve the balance between the ease of welding by forming the welding recess 25 and the mechanical strength, it is preferable that they are 0.5 mm or more and 5.0 mm or less, and it is particularly preferable that they are 1.0 mm or more and 2.0 mm or less.

[0029] (Regarding joints) The joined structure 1 has a joint 10 formed by welding a plate surface 22 of a first resin plate 21 made of a first resin to an end surface 24 of a second resin plate 23 made of a second resin in a butted state. Here, the joint 10 is formed by welding the end surface 24 of the second resin plate 23 in a butted state to the back surface (the lower surface in FIG. 1) of the plate surface 22 of the first resin plate 21, as shown in FIG.

[0030] The joint 10 has a welding recess 25 on the surface 22a of the plate surface portion 22 of the first resin plate 21. Here, the surface 22a of the plate surface portion 22 is the surface on the side that is not butted against the end surface portion 24 of the second resin plate 23. By providing the welding recess 25 in the joint 10, at least the first resin contained in the first resin plate 21 is extruded in the depth direction of the welding recess 25, melts and flows near the end surface portion 24 of the second resin plate 23, and the melted and flowed resin is welded to the end surface portion 24 of the second resin plate 23 to form a buildup portion 27, which will be described later. Note that the resin that melts and flows by forming the welding recess 25 may contain a second resin in addition to the first resin.

[0031] The bottom surface 26 of the welding recess 25 may be made of a non-foaming resin. In particular, when the first resin is extruded in the depth direction of the welding recess 25 and melted and flowed near the end surface 24 of the second resin plate 23, the first resin on the bottom surface 26 of the welding recess 25 also often melts, and therefore a non-foaming resin is often formed on the bottom surface 26 of the welding recess 25.

[0032] Here, the width dimension w of the bottom surface 26 of the welding recess 25 along the thickness direction of the second resin sheet 23 (X1 direction in FIG. 1 ) is preferably equal to or greater than the thickness dimension t2 of the second resin sheet 23. In this case, the bottom surface 26 of the welding recess 25 is preferably configured to include positions where both sides of the second resin sheet 23 are present, as viewed in the thickness direction (X1 direction) of the second resin sheet 23. Furthermore, the width dimension w of the bottom surface 26 of the welding recess 25 is preferably greater than the thickness dimension t2 of the second resin sheet 23 by a range of more than 0 mm and not more than 1.0 mm. Configuring the welding recess 25 in this manner facilitates melting and flow of the resin extruded in the depth direction of the welding recess 25 near the end surface 24 of the second resin sheet 23. On the other hand, the width dimension w of the bottom surface 26 of the welding recess 25 may be smaller than the thickness dimension t2 of the second resin sheet 23.

[0033] The surface shape of the bottom surface 26 of the welding recess 25 can be a lattice-like uneven shape, for example, as shown in Fig. 1(a). As will be described later, such a lattice-like uneven shape can be formed by pressing the tip of a welding horn, which has been knurled in a twill pattern, against the surface 22a of the plate surface portion 22 of the first resin plate 21. This makes it easier to extrude the resin in the depth direction of the welding recess 25.

[0034] The surface shape of the bottom surface 26 of the welding recess 25 is not limited to the lattice-like uneven shape shown in Fig. 1(a). For example, it may be a striped uneven shape formed using a knurled tip of a welding horn as shown in Fig. 2(a). It may also be an irregular uneven shape formed using a blasted tip of a welding horn as shown in Fig. 2(b). It may also be a flat surface as shown in Fig. 2(c).

[0035] Furthermore, the shape of the welding recess 25 is not limited to the rectangular shape shown in FIG. 1(a), but may be a circular shape as shown in FIG.

[0036] 1, the joint 10 has a buildup portion 27 formed by melting, flowing, and solidifying at least the first resin of the first and second resins at an inside corner 10a of the back surface 22b formed by the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23. This increases the joining area between the end surface portion 24 of the second resin plate 23 and the plate surface portion 22 of the first resin plate 21, allowing the first resin plate 21 and the second resin plate 23 to be joined by welding.

[0037] The shape of the welded portion 27 is not particularly limited, and may be, for example, as shown in Figure 4(a), such that the surface of the welded portion 27E of the joint 10E is concave when viewed from the inside corner 10a, or as shown in Figure 4(b), such that the surface of the welded portion 27F of the joint 10F is convex when viewed from the inside corner 10a.

[0038] The minimum thickness t3 of the joint 10, which is the minimum thickness, regardless of the measurement direction, measured from the position of the welding recess 25, is preferably 0.1 mm or more, and more preferably 0.3 mm or more. Here, the minimum thickness t3 of the joint 10 may preferably be 0.1 mm or 0.10 mm. The minimum thickness t3 of the joint 10 measured from the position of the welding recess 25 may be less than 0.1 mm. However, by setting the minimum thickness t3 to 0.1 mm or more, the thickness of the joint 10 (the total thickness of the first resin sheet 21 and the second resin sheet 23) is ensured even near the location where the welding recess 25 is formed, making it less likely that the first resin will break at the joint 10. On the other hand, the upper limit of the minimum thickness t3 of the joint 10 measured from the position of the welding recess 25 is preferably 2.0 mm, and more preferably a value approximately 0.1 mm smaller than the plate thickness (the thickness of the first resin sheet 21). Here, when the upper limit of the minimum thickness t3 is set to a value approximately 0.1 mm smaller than the plate thickness, for example, when the thickness of the first resin plate 21 is 1.5 mm, the upper limit of the minimum thickness t3 of the joint 10 can be set to 1.4 mm. Also, for example, when the thickness of the first resin plate 21 is 1.0 mm, the upper limit of the minimum thickness t3 of the joint 10 can be set to 0.9 mm. In this way, by setting the upper limit of the minimum thickness t3 of the joint 10, as measured from the position of the welding recess 25, to 2.0 mm or a value approximately 0.1 mm smaller than the plate thickness, the resin is more easily extruded when forming the welding recess 25, thereby increasing the bonding strength between the first resin plate 21 and the second resin plate 23.

[0039] Furthermore, in the joint 10, the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the bottom of the welding recess 25, is preferably 0.1 mm or more, more preferably 0.3 mm or more. Here, the preferable lower limit of the minimum thickness t4 of the first resin may be 0.1 mm or 0.10 mm. The minimum thickness t4 of the first resin at the bottom of the welding recess 25 may be less than 0.1 mm, but by making it 0.1 mm or more, fracture of the first resin at the joint 10 can be made less likely. On the other hand, by making the minimum thickness t4 of the first resin at the bottom of the welding recess 25 2.0 mm or less, more preferably 1.0 mm or less, the resin can be easily extruded when forming the welding recess 25, thereby further improving workability when joining the first resin plate 21 and the second resin plate 23. Furthermore, when forming the joined structure 1 by ultrasonic welding, which will be described later, the vibration of the ultrasonic waves U can make it easier to melt the end surface portion 24 of the second resin plate 23. The minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21 is often the thickness of the first resin plate 21 measured at the deepest position on the bottom surface 26 of the welding recess 25, but may also be the thickness of the first resin plate 21 measured at a different position.

[0040] Furthermore, in the joint 10, the butt angle between the plate surface 22 of the first resin plate 21 and the end surface 24 of the second resin plate 23 is preferably in the range of 45° to 90°, measured on the acute angle side, and more preferably in the range of 60° to 90°. By setting the butt angle between the plate surface 22 of the first resin plate 21 and the end surface 24 of the second resin plate 23 in this range, it becomes easier for the resin to melt and flow on both sides of the end surface 24 of the second resin plate 23 when the resin is extruded in the depth direction of the welding recess 25.

[0041] 2. Regarding the exterior body for electric wires The wire sheathing 30 is an sheathing for an electric wire that is attached to the outer periphery of the electric wire 4 and includes the joint structure 1.

[0042] The following detailed description will be given with reference to the drawings. Fig. 5 is a schematic perspective view showing the structure of an electric wire outer casing 30. The electric wire outer casing 30 has a wall portion 31 existing along the extending direction X2 of the electric wire 4, and has a housing portion 32 formed by being surrounded by this wall portion 31 and housing the electric wire 4. By including the above-described joint structure 1 in the electric wire outer casing 30, the electric wire outer casing 30 can be formed without providing an extra resin plate portion for joining, and workability in joining the resin plates to form the electric wire outer casing 30 is improved, so that an electric wire outer casing 30 that can adequately protect the electric wire 4 while achieving weight reduction can be obtained. Note that while Fig. 5 shows the electric wire 4 as a single cylindrical wire, the electric wire 4 may be a bundle of two or more electric wires, such as a wire harness, or may be branched as needed.

[0043] The shape of the electric wire outer casing 30 is not particularly limited, and for example, as shown in Fig. 5, the wall portions 31 may be formed by bending a single resin plate at multiple bending portions 30a to 30c. In this case, it is preferable that the wall portions 31 of the electric wire outer casing 30 are configured so as to surround the entire circumference of the electric wire 4. By forming the electric wire outer casing 30 from a single resin plate in this way, the number of joints of the resin plate is reduced, and therefore the production of the electric wire outer casing 30 can be carried out more efficiently.

[0044] 3. Wire harnesses with exterior housing The wire harness 3 with an exterior body of the present invention includes a wire harness 40 formed of electric wires 4 and the above-described electric wire exterior body 30, and the electric wire exterior body 30 is attached to the outer periphery of the wire harness 40. This allows the electric wire exterior body 30 to protect at least a part of the electric wire bundle constituting the wire harness 40 and an electric wire assembly formed of a plurality of divided electric wire bundles branching out and extending from the electric wire bundle.

[0045] 4. Manufacturing method of the bonded structure Next, a method for manufacturing the above-described joined structure 1 will be described. Fig. 6 is a flow diagram of the method for manufacturing the joined structure 1. This manufacturing method includes a positioning step ST1 in which an end surface 24 of a second resin plate 23 made of a second resin is positioned and held against a back surface 22b of a plate surface 22 of a first resin plate 21 made of a first resin, a welding horn pressing step ST2 in which a tip end 51 of a welding horn 5 is pressed against the front surface 22a of the plate surface 22 of the first resin plate 21 while the plate surface 22 of the first resin plate 21 and the end surface 24 of the second resin plate 23 are butted together, and a joint forming step ST3 in which ultrasonic waves U are oscillated from the welding horn 5 to weld the plate surface 22 of the first resin plate 21 and the end surface 24 of the second resin plate 23 while they are butted together, thereby forming a joint 10.

[0046] First, a first resin plate 21 made of a first resin and a second resin plate 23 made of a second resin are prepared. The first resin constituting the first resin plate 21 is preferably a foamed resin. By using a foamed resin as the first resin plate 21, when the tip 51 of the welding horn 5 is pressed against the first resin plate 21 in the welding horn pressing step ST2 (described later) and the first resin is melted using ultrasonic waves U in the joint forming step ST3, air bubbles escape from the first resin, causing it to shrink and be easily extruded toward the depth of the welding recess 25. This promotes solidification of the welded resin and suppresses excessive melt flow of the first resin, making it less likely for the first resin to flow out of the joint 10. On the other hand, the second resin constituting the second resin plate 23 may be either a non-foamed resin or a foamed resin.

[0047] A positioning step ST1 is performed on the first resin plate 21 and the second resin plate 23. In the positioning step ST1, the first resin plate 21 and the second resin plate 23 are positioned and held in a state where the end surface portion 24 of the second resin plate 23 made of the second resin is abutted against the back surface 22b of the plate surface portion 22 of the first resin plate 21 made of the first resin. For example, when manufacturing an electric wire outer casing 30 including the joint structure 1, by positioning the first resin plate 21 and the second resin plate 23 in the positioning step ST1, it is possible to form an accommodating portion 32 that accommodates the electric wire 4 at a desired position and size.

[0048] In the positioning process ST1, the positioning and holding of the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23 can be performed by using a means for holding them in a predetermined position, such as a dedicated positioning jig made to match the shape and dimensions of the resin plate, to fix the positional relationship between the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23 while they are in contact with each other.

[0049] 7A and 7B are diagrams illustrating a method for manufacturing a joined structure, and are conceptual diagrams illustrating an example of the welded horn pressing step and the joint forming step. After the positioning step ST1, as shown in FIG. 7A, the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23 are butted against each other, and then the welded horn pressing step ST2 is performed, in which the tip portion 51 of the welded horn 5 is pressed against the surface 22a of the plate surface portion 22 of the first resin plate 21. This allows the tip portion 51 of the welded horn 5 to be positioned relative to the plate surface portion 22 of the first resin plate 21 and the end surface 24 of the second resin plate 23.

[0050] It is preferable that the tip 51 of the welded horn 5 is formed in a convex projection shape. This makes it difficult for deformation to occur at the base of the welded horn 5, and also increases the force per unit area acting on the plate surface 22 of the first resin plate 21 when the tip 51 of the welded horn 5 is pressed against the plate surface 22 of the first resin plate 21 in the welded horn pressing step ST2. This makes it easier to extrude the first resin in the depth direction of the welded recess 25 when forming the welded recess 25 in the joint forming step ST3 described below.

[0051] 8A and 8B are conceptual diagrams showing examples of the shape of the tip of a welding horn used in manufacturing a bonded structure of another embodiment. Fig. 8(a) is a diagram showing a configuration in which the tip of the welding horn has an uneven surface formed by knurling. Fig. 8(b) is a diagram showing a configuration in which the tip of the welding horn has a convex protrusion, the tip of which has an uneven surface formed by blasting. Fig. 8(c) is a diagram showing a configuration in which the tip of the welding horn has a convex protrusion, the tip of which has a convex surface formed by filleting.

[0052] Here, as shown in FIG. 8( a), the tip 51 of the welding horn 5 may have multiple projections and depressions formed on at least a portion of its surface by knurling, such as a twill or flat grain. Also, as shown in FIG. 8( b), the tip 51G of the welding horn 5G may have convex protrusions formed thereon, or multiple projections and depressions may be formed on at least a portion of the surface of the tip 51G by blasting. By forming multiple projections and depressions on the surface of the tip 51 of the welding horn 5, 5G, the contact area with the first resin plate 21 is reduced, which allows the pressure applied to the contact portion with the first resin plate 21 to be concentrated on the convex portions. Furthermore, the vibration of the ultrasonic wave U in the joint formation step ST3, which will be described later, can also be concentrated on the convex portions, making it easier to extrude at least the first resin in the depth direction of the welding recess 25.

[0053] 8(c), at least a portion of the surface of tip 51H of welding horn 5H may be curved, and more specifically, the tip of a convex protrusion formed on tip 51H may have a chamfered convex surface formed by filleting. By forming a curved surface on tip 51 of welding horn 5 in this way, the contact area with first resin plate 21 is reduced, which makes it possible to concentrate the pressure applied to the contact area with first resin plate 21 and also to concentrate the vibrations of ultrasonic waves U in joint formation step ST3, which will be described later, making it easier to extrude at least the first resin in the depth direction of welding recess 25. Furthermore, by forming a curved surface at the tip portion 51, when the convex curved portion of the tip portion 51 is pressed along the overlapping portion between the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23, the end portion of the tip portion 51 is pressed shallowly, making it easier to obtain the required thickness of the first resin plate 21 after forming the welding recess 25 (in particular, the minimum thickness t3 of the first resin plate when measured from the position of the welding recess 25).

[0054] Next, as shown in FIG. 7( b), a joint formation step ST3 is performed in which ultrasonic waves U are emitted from the welding horn 5 to weld the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23 in a butted state, thereby forming a joint 10. The vibration of the ultrasonic waves U emitted from the welding horn 5 heats and melts at least the first resin of the first and second resins, and the molten resin is extruded by the welding horn 5. At this time, a portion of the end surface portion 24 of the second resin plate 23 may melt together with the first resin and form a mixture with the extruded first resin. The extruded resin melts and flows near the end surface 24 of the second resin plate 23 and is welded to the inside corner 10a between the back surface 22b of the plate surface portion 22 and the end surface 24 of the second resin plate 23, thereby forming the joint 10. At this time, a welding recess 25 is formed on the surface 22a of the plate surface portion 22 of the first resin plate 21 at the location where the welding horn 5 was pressed. At the same time, a build-up portion 27 is formed at an inside corner 10a formed on the rear surface 22b of the plate surface portion 22 and the end surface portion 24 of the second resin plate 23.

[0055] In this way, a joint structure 1 can be obtained in which the joint 10 has a welding recess 25 on the front surface 22a of the plate surface portion 22 of the first resin plate 21, and has a buildup portion 27 formed at the inside corner 10a of the joint 10 on the back surface 22b of the plate surface portion 22 by melting, flowing, and solidifying at least the first resin of the first and second resins.

[0056] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. [Example]

[0057] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0058] [Example 1 of the present invention] The first resin plate 21 and the second resin plate 23 each have a density of 480 kg / m 3 The foamed resin plates used were made of foamed polypropylene resin. Here, the plate thickness dimension t1 of the first resin plate 21 and the plate thickness dimension t2 of the second resin plate 23 were both 1.5 mm. The first resin plate 21 and the second resin plate 23 were made of resin plates of different colors to make it easier to check the welding state.

[0059] In the positioning step ST1, the first resin plate 21 and the second resin plate 23 were butted at a right angle against the back surface 22b of the plate surface 22 of the first resin plate 21 made of the first resin, with the end surface 24 of the second resin plate 23 made of the second resin, and these were positioned with a positioning jig in contact, and their positional relationship was maintained. That is, the butt angle between the plate surface 22 of the first resin plate 21 and the end surface 24 of the second resin plate 23 was set to 90°.

[0060] Next, in the welding horn pressing step ST2, the plate surface portion 22 of the first resin plate 21 and the end surface portion 24 of the second resin plate 23 were butted against each other, and the tip portion 51 of the welding horn 5 was pressed against the surface 22a of the plate surface portion 22 of the first resin plate 21. As shown in FIG. 8(a), the welding horn 5 used had a convex protrusion with a tip surface measuring 2.4 mm in length and 8.0 mm in width formed on the tip portion 51, and multiple protrusions and recesses formed on the tip surface of the protrusion by a twill knurling pattern with a module (m) of 0.2 as specified in JIS B 0951. The tip portion 51 of the welding horn 5 was pressed against the first resin plate 21 and the second resin plate 23 so that the short side (vertical direction) of the tip portion 51 overlapped the thickness direction of the second resin plate 23. At this time, the tip portion 51 of the welded horn 5 was set to protrude evenly from the second resin plate 23 in the thickness direction of the second resin plate 23 .

[0061] With the tip 51 of the welding horn 5 pressed against the first resin plate 21 and the second resin plate 23, ultrasonic waves U were emitted from the welding horn 5 as a joint forming step ST3. Here, the ultrasonic waves U from the welding horn 5 were emitted using a small welder (manufactured by Ultrasonic Industrial Co., Ltd., model number: P128), and ultrasonic waves with an output of 100 W and a frequency of 28 kHz were emitted for 0.9 seconds, with the welding horn 5 being pushed in to a depth of 0.75 mm, thereby welding the first resin plate 21 and the second resin plate 23 to form the joint 10, and thereby producing the joined structure 1.

[0062] The resulting joined structure 1 was observed in a cross section perpendicular to both the first resin plate and the second resin plate, as shown in FIG. 9. The results of the observation shown in FIG. 9 reveal that in the joint formation step ST3, the first resin constituting the first resin plate 21 and the second resin constituting the second resin plate 23 are heated and locally melted by the oscillation of the ultrasonic waves U, and the molten first resin is extruded by the welding horn 5 with reduced voids due to foaming. The extruded first resin melts and flows near the end surface 24 of the second resin plate 23 while forming a mixture with the molten second resin, and is welded to the inside corner 10a between the back surface 22b of the plate surface 22 and the end surface 24 of the second resin plate 23 to form a buildup portion 27.

[0063] Furthermore, the joint 10 of the resulting joint structure 1 had a welding recess 25 formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and a lattice-like uneven shape formed on the bottom surface 26 thereof. The length and width dimensions of the bottom surface 26 of the welding recess 25 were approximately the same as the dimensions of the tip portion 51 of the welding horn 5. That is, the width dimension w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 2.4 mm.

[0064] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 0.75 mm. Furthermore, the tip position of the end face portion 24 of the second resin was located at approximately the same position as the plate surface portion 22 of the first resin plate 21 before the formation of the joint 10, and the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the position of the deepest bottom surface 26 of the welding recess 25, was measured to be 0.75 mm.

[0065] The bond strength of the obtained bonded structure 1 was measured using an autograph tensile testing machine (model number: AGS-X, 10N-10kN) manufactured by Shimadzu Corporation when the bonded portion 10 was peeled off along the depth direction of the welded recess 25, and the bond strength was measured to be 147 [N].

[0066] [Example 2] The welded horn 5 had a convex protrusion at the tip 51 with a tip surface measuring 2.0 mm in length and 8.0 mm in width, and the tip surface of the protrusion had multiple irregularities formed by a twill knurling pattern with a module (m) of 0.2 as specified in JIS B 0951.A joint structure 1 was produced in the same manner as in Example 1 of the present invention.

[0067] In the joint 10 of the resulting joint structure 1, as in Example 1 of the present invention, a welding recess 25 was formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and a lattice-like uneven shape was formed on the bottom surface 26 of the welding recess 25. The length and width of the bottom surface 26 of the welding recess 25 were approximately the same as the dimensions of the tip 51 of the welding horn 5. That is, the width w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 2.0 mm.

[0068] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 0.75 mm. Furthermore, the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the deepest position on the bottom surface 26 of the welding recess 25, was measured to be 0.75 mm.

[0069] The bond strength of the resulting bonded structure 1 was measured by the same method as in Example 1 of the present invention, and the bond strength was measured to be 143 [N].

[0070] [Example 3] The welding horn 5 had a convex protrusion at the tip 51 with a tip surface measuring 1.6 mm in length and 8.0 mm in width, and the tip surface of the protrusion had multiple irregularities formed by a twill knurling pattern with a module (m) of 0.2 as specified in JIS B 0951.A joining structure 1 was produced in the same manner as in Example 1 of the present invention.

[0071] In the joint 10 of the resulting joint structure 1, as in Example 1 of the present invention, a welding recess 25 was formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and a lattice-like uneven shape was formed on the bottom surface 26 of the welding recess 25. The length and width dimensions of the bottom surface 26 of the welding recess 25 were approximately the same as the dimensions of the tip portion 51 of the welding horn 5. That is, the width dimension w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 1.6 mm.

[0072] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 0.75 mm. Furthermore, the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the deepest position on the bottom surface 26 of the welding recess 25, was measured to be 0.75 mm.

[0073] The bond strength of the resulting bonded structure 1 was measured by the same method as in Example 1 of the present invention, and the bond strength was measured to be 123 [N].

[0074] [Example 4] As shown in Figure 8(b), a welded horn 5G was used, which had a convex protrusion at the tip 51G, with a cross-sectional size of 2.0 mm in length and 8.0 mm in width, and a mountain-shaped protrusion protruding 0.5 mm from the tip, and the tip surface of the protrusion had an uneven surface formed by blasting processing.A bonded structure 1 was produced in the same manner as in Example 1 of the present invention.

[0075] In the joint 10 of the resulting joined structure 1, as in Example 1 of the present invention, a welding recess 25 was formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and the shape of the mountain-shaped convex protrusion of the welding horn 5 was directly transferred to the bottom surface 26 of the welding recess 25. The dimensions and shape of the bottom surface 26 of the welding recess 25 were also approximately the same as the dimensions and shape of the tip portion 51 of the welding horn 5. That is, the width dimension w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 2.0 mm.

[0076] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 1.00 mm. Furthermore, the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the deepest position on the bottom surface 26 of the welding recess 25, was measured to be 0.75 mm.

[0077] The bond strength of the resulting bonded structure 1 was measured by the same method as in Example 1 of the present invention, and the bond strength was measured to be 135 [N].

[0078] [Example 5] As shown in Figure 8(c), a welded horn 5H was used, which had a convex protrusion at the tip 51H, with a cross-sectional size of 2.0 mm in length and 8.0 mm in width, and a mountain-shaped protrusion at the tip, and the tip of the protrusion was filleted with a radius of 1.0 mm, giving the protrusion a convex surface with a protrusion height of 0.5 mm.A joint structure 1 was produced in the same manner as in Example 1 of the present invention.

[0079] In the joint 10 of the resulting joined structure 1, as in Example 1 of the present invention, a welding recess 25 was formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and the shape of the mountain-shaped convex protrusion of the welding horn 5 was directly transferred to the bottom surface 26 of the welding recess 25. The dimensions and shape of the bottom surface 26 of the welding recess 25 were also approximately the same as the dimensions and shape of the tip portion 51 of the welding horn 5. That is, the width dimension w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 2.0 mm.

[0080] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 0.90 mm. Furthermore, the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the deepest position on the bottom surface 26 of the welding recess 25, was measured to be 0.75 mm.

[0081] The bond strength of the resulting bonded structure 1 was measured by the same method as in Example 1 of the present invention, and the bond strength was measured to be 146 [N].

[0082] [Example 6] A joint structure 1 was produced in the same manner as in Example 1 of the present invention, except that the pressing depth of the welding horn 5 when forming the joint 10 was set to 1.45 mm.

[0083] The joint 10 of the resulting joint structure 1 had a welding recess 25 formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and a lattice-like uneven shape formed on the bottom surface 26. The length and width dimensions of the bottom surface 26 of the welding recess 25 were approximately the same as the dimensions of the tip portion 51 of the welding horn 5. That is, the width dimension w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 2.4 mm.

[0084] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 0.05 mm. Furthermore, the tip position of the end face portion 24 of the second resin was located at approximately the same position as the plate surface portion 22 of the first resin plate 21 before the formation of the joint 10, and the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the position of the deepest bottom surface 26 of the welding recess 25, was measured to be 0.05 mm.

[0085] The bond strength of the resulting bonded structure 1 was measured by the same method as in Example 1 of the present invention, and the bond strength was measured to be 70 [N].

[0086] [Example 7] The joined structure 1 was produced in the same manner as in Example 1 of the present invention, except that the plate thickness dimension t1 of the first resin plate 21 was 3.0 mm, the plate thickness dimension t2 of the second resin plate 23 was 1.5 mm, and the pressing depth of the welding horn 5 when forming the joint 10 was 0.90 mm.

[0087] The joint 10 of the resulting joint structure 1 had a welding recess 25 formed on the surface 22a of the plate surface portion 22 of the first resin plate 21, and a lattice-like uneven shape formed on the bottom surface 26. The length and width dimensions of the bottom surface 26 of the welding recess 25 were approximately the same as the dimensions of the tip portion 51 of the welding horn 5. That is, the width dimension w of the bottom surface 26 of the welding recess 25 along the plate thickness direction of the second resin plate 23 was approximately 2.4 mm.

[0088] Furthermore, in the obtained joined structure 1, the minimum thickness t3 of the joint 10, regardless of the measurement direction, measured from the position of the welding recess 25 was measured to be 2.10 mm. Furthermore, the tip position of the end face portion 24 of the second resin was located at approximately the same position as the plate surface portion 22 of the first resin plate 21 before the formation of the joint 10, and the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the position of the deepest bottom surface 26 of the welding recess 25, was measured to be 2.10 mm.

[0089] The bond strength of the resulting bonded structure 1 was measured by the same method as in Example 1 of the present invention, and the bond strength was measured to be 12 [N].

[0090] [Comparative Example 1] As Comparative Example 1, a joint structure having the structure shown in FIG. 11 of Patent Document 2 was formed. A through hole was formed in the first resin sheet 21, and a protrusion was formed at the tip of the end surface 24 of the second resin sheet 23. The protrusion had a wide head portion forming the tip and a narrow body portion connecting the abutting surface of the head and the first resin sheet 21. Next, the protrusion was inserted into the through hole in the plate surface 22 of the first resin sheet 21 from the back surface side, in this state, with the wide head portion of the protrusion folded, and then the body portion, and the end surface 24 of the second resin sheet 23 was abutted at a right angle. Then, both ends of the head were returned to their pre-bending state, and the protrusion was inserted into the through hole so that the body portion passed through the through hole, thereby forming a joint structure.

[0091] In Comparative Example 1, more resin plates were required than in the present invention example to provide a protrusion at the tip end of the end surface portion 24 of the second resin plate 23. When the bonding strength of the obtained bonded structure was measured using the same measuring method as in Present Invention Example 1, the maximum bonding strength was measured to be 93 [N].

[0092] Comparative Example 2 In Comparative Example 2, a hole was formed in the first resin plate 21, and a protrusion was formed at the tip of the end surface 24 of the second resin plate 23. Next, the protrusion of the end surface 24 of the second resin plate 23 was inserted into the hole of the plate surface 22 of the first resin plate 21 from the back surface side, and the end surface 24 of the second resin plate 23 was butted at a right angle. Thereafter, the protrusion of the end surface 24 of the second resin plate 23 protruding from the hole of the plate surface 22 of the first resin plate 21 was crimped by thermal melting, thereby fixing the end surface 24 of the second resin plate 23 and the plate surface 22 of the first resin plate 21 together.

[0093] In Comparative Example 2, more resin plates were also required than in the Example of the present invention to provide a protrusion at the tip of the end surface portion 24 of the second resin plate 23. When the bonding strength of the obtained bonded structure was measured using the same measuring method as in Example 1 of the present invention, the maximum bonding strength was measured to be 120 [N].

[0094] From the above, in the joined structures 1 of Examples 1 to 7 of the present invention, there is no need to provide a protrusion at the tip end of the end surface portion 24 of the second resin plate 23, so no extra resin plate portion is required for joining, and all of them had a joining strength exceeding 10 [N]. Furthermore, since welding is performed by emitting ultrasonic waves U from the welding horn 5, the workability in joining the first resin plate 21 and the second resin plate 23 was also excellent.

[0095] Therefore, the joined structures 1 of Examples 1 to 7 of the present invention were capable of joining resin plates together without providing any extra resin plate portions for joining, and also had excellent workability when joining the resin plates.

[0096] In particular, the bonded structures 1 of Examples 1 to 5 of the present invention had high bond strength and firmly bonded the resin plates together when the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the bottom of the welding recess 25, was in the range of 0.1 mm to 2.0 mm, since the bond strength exceeded 120 [N] in all cases. Therefore, from the perspective of particularly increasing the bond strength and enabling the resin plates to be firmly bonded together without providing an extra resin plate portion for bonding, it is considered preferable to set the minimum thickness t4 of the first resin along the thickness direction of the first resin plate 21, measured at the bottom of the welding recess 25, to be in the range of 0.1 mm to 2.0 mm.

[0097] On the other hand, in the joined structures of Comparative Examples 1 and 2, in order to join the first resin plate 21 and the second resin plate 23, it was necessary to provide a protrusion at the tip end of the end face portion 24 of the second resin plate 23, which required more resin plates. [Explanation of symbols]

[0098] 1. 1A~1F Joint structure 10, 10A~10F joint 10a Inside corner of back side of joint 21, 21A~21D 1st resin plate 22 Plate surface portion of first resin plate 22a: Plate surface portion (surface) of first resin plate 22b: Plate surface portion (rear surface) of first resin plate 23 Second resin plate 24 End surface of second resin plate 25, 25A~25F welding recess 26, 26A~26F Bottom of welding recess 27, 27E, 27F Overlay part 3. Wire harness with outer casing 30. Wire sheathing 30a~30c bending part 31 Wall 32 Storage section 4 electric wire 40 Wire harness 5, 5G, 5H Welded Horn 51, 51G, 51H Welded horn tip t1: Thickness of the first resin plate t2: Thickness of the second resin plate t3 Minimum thickness of the first resin plate measured from the welding recess position t4 Minimum thickness of the first resin when measured at the bottom of the weld recess U Ultrasonic X1: Thickness direction of second resin plate X2 Wire extension direction

Claims

1. A joined structure having a joint formed by welding a plate surface portion of a first resin plate made of a first resin and an end surface portion of a second resin plate made of a second resin in a butted state, the first resin is a foamed resin, the second resin is a non-foaming resin or a foaming resin, The joint has a welding recess on the surface and a build-up portion at an inside corner on the back surface, formed by at least the first resin of the first resin and the second resin melting, flowing, and solidifying.

2. The joint structure according to claim 1 , wherein the minimum thickness of the first resin in the joint portion is in the range of 0.1 mm to 2.0 mm when measured at the bottom of the welding recess.

3. The joint structure according to claim 1 or 2, wherein the joint has a minimum thickness of 0.1 mm or more when measured from the position of the welding recess.

4. 4. A joint structure according to claim 1, wherein the butt angle between the plate surface portion of the first resin plate and the end surface portion of the second resin plate is in the range of 45° or more and 90° or less when measured on the acute angle side.

5. The bonded structure according to claim 1 , wherein one or both of the first resin and the second resin contain a polypropylene resin.

6. An outer casing for an electric wire that is attached to the outer periphery of an electric wire, An outer casing for an electric wire, comprising the joint structure according to claim 1 .

7. A wire harness comprising: the wire sheathing according to claim 6; The wire harness with an exterior body is configured such that the wire exterior body is attached to the outer periphery of the wire harness.

8. a positioning step of positioning and holding an end surface of a second resin plate made of a second resin in a state where the end surface of the second resin plate is abutted against a rear surface of a plate surface of the first resin plate made of a first resin; a welding horn pressing step of pressing a tip end of a welding horn against a front surface side of the plate surface portion of the first resin plate in a state where the plate surface portion of the first resin plate and the end surface portion of the second resin plate are butted against each other; a joint forming step of forming a joint by welding a plate surface portion of the first resin plate and an end surface portion of the second resin plate in a butted state by oscillating ultrasonic waves from the welding horn; Including, the first resin is a foamed resin, the second resin is a non-foaming resin or a foaming resin, A method for manufacturing a joined structure, wherein the joint has a welding recess on the surface and a buildup portion at an inside corner on the back surface, the buildup portion being formed by at least the first resin of the first resin and the second resin melting, flowing, and solidifying.

9. The method for manufacturing a joint structure according to claim 8 , wherein the tip of the welding horn is formed in a convex projection shape.

10. The method for manufacturing a joint structure according to claim 8 or 9, wherein at least a portion of the surface of the tip of the welding horn is formed into a curved shape.

11. The method for manufacturing a joint structure according to claim 8 , wherein at least a portion of the surface of the tip of the welding horn is formed with a plurality of projections and recesses.

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