Joining structure, joining method, exterior body for wire harness, and wire harness

Abstract

Provided are a joining structure, a joining method, an exterior body for a wire harness, and a wire harness capable of firmly joining members having different physical properties while reducing the thickness of a joint part.　The joining structure 10 joins a first member 1 made of a first resin and a second member 2 made of a second resin, wherein: the second resin has physical properties having a higher foaming ratio than the first resin; and a recessed joint part 3 is provided which reaches at least the inside of the first member 1 from the outer surface side of the second member in a state in which the first member 1 and the second member 2 are superimposed. Furthermore, a method for manufacturing the joining structure 10 comprises the steps of: superimposing a first member 1 made of a first resin and a second member 2 made of a second resin having physical properties having a higher foaming ratio than the first resin; and joining the first member 1 and the second member 2 by forming the recessed joint part 3 by pressing and hot-melting the second member 2 until the recessed joint part 3 reaches at least the inside of the first member 1 from the outer surface side of the second member 2.

Description

Technical Field

[0001] The present invention relates to a joining structure, a joining method, an outer member for a wire harness, and a wire harness.

Background Art

[0002] A protector (outer member) for a wire harness is used for purposes such as protecting a wire harness, regulating a route, and fixing. Various shapes and materials of protectors for wire harnesses are used according to their applications and the like.

[0003] Currently, attention has been focused on a foamed outer member formed from a foamed sheet. Such a foamed outer member has advantages of being lightweight and can be manufactured by cutting a desired form from a single foamed sheet.

[0004] Such a foamed outer member has various usage forms and may be used in combination with other components in addition to being used alone. In particular, when used in combination with various components made of different materials, the foamed outer member is used by fixing the components to each other by joining.

[0005] As a method of joining resin materials, there is a method of providing a fitting mechanism in the resin materials and fitting them. For example, Patent Document 1 discloses a joining method in which a boss portion with a protruding tip is provided on one member, a through hole into which the boss portion can be inserted is provided on the other member, and the two members are joined by inserting the boss portion into the through hole. Such a method of providing a fitting mechanism in resin materials can also be applied when attaching a component made of a non-foamed member to the above-described foamed outer member.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, as described above, the fixing structure of the resin part disclosed in Patent Document 1 requires the processing of forming one member and the other member in advance, and there is a problem that the joint part of both members becomes large. In addition, when joining two members having different physical properties, it is conceivable to use an adhesive or a double-sided tape, etc., but depending on the structure and material of the member, the joint strength may become weak, and the joint part may come off.

[0008] In view of the above circumstances, the present invention has been made, and an object thereof is to provide a joining structure, a joining method, an exterior body for a wire harness, and a wire harness that can firmly join members having different physical properties while reducing the thickness of the joint part.

Means for Solving the Problems

[0009] The inventors of the present invention have conducted intensive studies to solve the above-described problems. As a result, the inventors of the present invention have found that, for a joining structure that joins a first member made of a first resin and a second member made of a second resin, the second resin has a physical property with a higher expansion ratio than the first resin, and in a state where the first member and the second member are overlapped, by having a concave joint part that reaches at least the inside of the first member from the outer surface side of the second member, a joining structure in which two types of members (the first member, the second member) having different physical properties are firmly joined can be obtained. In addition, the inventors of the present invention have found that by including a step of overlapping a first member made of a first resin and a second member made of a second resin having a physical property with a higher expansion ratio than the first resin, and a step of pressing and heat-melting the second member until it reaches at least the inside of the first member to form a concave joint part, the above-described joining structure can be easily manufactured, and the present invention has been completed. Specifically, the present invention provides the following.

[0010] (1) A first member made of a first resin, A second member made of a second resin, and a joining structure for joining wherein the second resin has physical properties with a higher expansion ratio than the first resin, a joining structure characterized in that the first member and the second member, in a superposed state, have a concave joining portion that reaches at least inside the first member from the outer surface side of the second member. (2) The second resin is a foamed resin, The joining structure according to (1) above, wherein the first resin is a non-foamed resin. (3) The joining structure according to (1) or (2) above, wherein the second resin is made of a material having a lower melting point than the first resin. (4) The joining structure according to (1), (2) or (3) above, wherein the second resin is made of a material having a lower density than the first resin. (5) The joining structure according to any one of (1) to (4) above, wherein the joining surface of the first member and the second member has a thermally melted portion that expands annularly outward. (6) The joining structure according to (5) above, wherein the thermally melted portion has an annular width dimension of 0.5 mm or more. (7) An outer covering for a wire harness using the joining structure according to any one of (1) to (6) above. (8) A wire harness, and the outer covering for a wire harness according to (7) above, and comprising An outer covering wire harness characterized in that the outer covering for a wire harness surrounds the wire harness from the outside or attaches to a part of the outer periphery to protect it. (9) A step of superposing a first member made of a first resin and a second member made of a second resin having physical properties with a higher expansion ratio than the first resin, and A joining method including a step of joining the first member and the second member by pressing and thermally melting the second member until it reaches at least inside the first member from the outer surface side of the second member to form a concave joining portion. (10) The pressing and heat melting of the second member is performed by ultrasonic vibration and pressing force in the ultrasonic welding method, and the joining method according to (9) above. (11) The ultrasonic welding method is performed by abutting the protrusion of a welding horn having a protrusion at the tip against the outer surface of the second member, and the joining method according to (10) above.

Effect of the Invention

[0011] According to the present invention, while achieving a reduction in the thickness of the joint portion, it is possible to firmly join members having different physical properties.

Brief Description of the Drawings

[0012]

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Figure 8

Best Mode for Carrying Out the Invention

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0014] 1. Joining Structure Hereinafter, the joining structure of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic perspective view of the joining structure of this embodiment.

[0015] The joining structure 10 of this embodiment is a joining structure for joining a first member 1 made of a first resin and a second member 2 made of a second resin, and the second resin has a physical property with a higher foaming ratio than the first resin. This joining structure 10 has a concave joining portion 3 that reaches at least the inside of the first member 1 from the outer surface side of the second member 2 in a state where the first member 1 and the second member 2 are overlapped.

[0016] Here, the "foaming ratio" indicates the degree of foaming in the first member and the second member. More specifically, this foaming ratio is represented by a value obtained by dividing the density of the member before foaming by the apparent density of the member after foaming.

[0017] In this way, the joining structure 10 has a concave joining portion 3 that reaches at least the inside of the first member 1 having a lower foaming ratio from the outer surface side of the second member 2 having a higher foaming ratio, so that the joining structure with the first member and the second member interchanged (that is, a joining structure having a concave joining portion that reaches at least the inside of the second member from the outer surface side of the first member) has a joining strength that is about twice that of the joining structure. Moreover, such a concave joining portion 3 does not need to form a complicated structure such as a fitting structure for joining, so that the thickness of the joining portion can be reduced.

[0018] FIG. 2 is a schematic cross-sectional view including the concave joining portion 3 of the joining structure 10 of this embodiment. FIG. 3 is a schematic plan view of the joining surface 5 of the first member 1 with respect to the second member when the first member 1 and the second member 2 constituting the joining structure 10 of this embodiment are separated at the joining interface position 4.

[0019] As described above, for the first resin and the second resin, it is sufficient that the second resin has a physical property of a higher expansion ratio than the first resin, and the specific resin composition, structure, etc. are not limited. Further, the first resin may be a non-foamed resin typified by a resin having an expansion ratio of 1 time.

[0020] Examples of the first resin and the second resin include thermoplastic resins 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, and acrylic resin.

[0021] In one embodiment, as an example regarding the combination of the first member 1 and the second member 2, there is a case where the first resin constituting the first member 1 is a non-foamed resin and the second resin constituting the second member 2 is a foamed resin. Further, as another example regarding the combination of the first member 1 and the second member 2, there is a case where the first resin constituting the first member 1 is a foamed resin and the second resin constituting the second member 2 is a foamed resin having a higher expansion ratio than the first resin.

[0022] In addition to resins having an expansion ratio of 1 time, non-foamed resins can include those in which no bubbles or voids are uniformly or non-uniformly dispersed in the resin when observed with an optical microscope (e.g., 10 times).

[0023] The density of the second resin, which is a foamed resin, is not particularly limited. For example, it is preferably 0.3 g / cm 3 or more and 0.9 g / cm 3 or less, more preferably 0.3 g / cm 3 or more and 0.6 g / cm 3 or less, and even more preferably 0.35 g / cm 3 or more and 0.55 g / cm 3 or less.

[0024] The number density of the bubbles of the second resin, which is a foamed resin, is not particularly limited, but the lower limit thereof is, for example, 800 bubbles / mm 3 or more, preferably 1000 bubbles / mm 3 or more. On the other hand, the upper limit of the number density of the bubbles of the second resin is, for example, 10 10 bubbles / mm 3 or less, preferably, from the viewpoint of obtaining excellent mechanical strength.

[0025] On the other hand, when the first resin is a non-foamed resin, the density of the first resin is not particularly limited, but is preferably 0.85 g / cm 3 or more and 0.95 g / cm 3 or less, more preferably 0.90 g / cm 3 or more and 0.91 g / cm 3 or less.

[0026] Furthermore, in one embodiment, the first resin and the second resin constituting the first member 1 and the second member 2 may be configured such that the second resin has a lower melting point than the first resin.

[0027] Also, in one embodiment, the first resin and the second resin constituting the first member 1 and the second member 2 may be configured such that the second resin has a lower density than the first resin.

[0028] The joining of the first member 1 and the second member 2 is not particularly limited with respect to the parts, shapes, or portions to be joined.

[0029] In FIGS. 1 to 3 described above, the first member 1 and the second member 2 are exemplified as being sheet-like for the sake of convenience of explanation, but are not limited to this example. For example, the first member and the second member may each be a block-like mass or may have a complex shape. Also, the thickness of the second member 2 in the vicinity of the joining portion is not particularly limited as long as the protrusion of the welding horn described later can penetrate and reach the inside of the first member.

[0030] As the concave joint portion 3 shown in FIGS. 1 to 3, an example is given of one having a circular shape in a plan view. Here, the shape of the concave joint portion 3 when viewed in plan is not particularly limited, and it may be any shape such as a rectangle or an ellipse. Among them, the shape of the concave joint portion 3 is preferably circular from the viewpoint of enhancing the mechanical strength of the portion where the first member 1 and the second member 2 of the joint structure 10 are joined. Also, the longitudinal sectional shape of the concave joint portion 3 (the shape in FIG. 2) is not particularly limited.

[0031] The size and length of the diameter of the concave joint portion 3 and the number of concave joint portions 3 provided are not particularly limited, and may be appropriately adjusted in consideration of the required mechanical strength and aesthetics.

[0032] The first member 1 and the second member 2 of the joint structure 10 shown in FIGS. 1 and 2 are separated at the joint interface position 4, and the joint surface 5 of the separated first member 1 with the second member 2 is shown in FIG. 3. Here, as shown in FIG. 3, the joint surface 5 preferably has a heat-melted portion 6 that extends annularly outward from the concave joint portion 3.

[0033] Having such a heat-melted portion 6 means that in the state where the first member 1 and the second member 2 are joined, the second resin forming the second member 2 and the first resin forming the first member 1 are melted and flowing into the joint interface position 4 of the first member 1 and the second member 2. And the heat-melted portion 6 formed in this way makes the first member 1 and the second member 2 have higher joint strength.

[0034] The size of the heat melting portion 6 is not particularly limited. However, generally, the larger the heat melting portion 6 is, the higher the bonding strength between the first member 1 and the second member 2 becomes. Therefore, the size of the heat melting portion 6 is preferably such that, for example, the annular width dimension of the heat melting portion 6 is 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 1.5 mm or more. In particular, when the annular width dimension of the heat melting portion 6 is 1.5 mm or more, the first member 1 and the second member 2 are bonded with a higher bonding strength. On the other hand, the annular width dimension of the heat melting portion 6 may be 0.5 mm or less.

[0035] Note that, as will be described later, the concave joint portion 3 is not limited to having a perfect circular shape in plan view. Also, the heat melting portion 6 is not limited to having a perfect circular ring shape in plan view. Here, when the heat melting portion 6 does not have a perfect circular ring shape in plan view, the annular width dimension of the heat melting portion 6 can be obtained by measuring the area surrounded by the outer contour line of the heat melting portion 6, calculating the diameter of a perfect circle having the same area, and then obtaining the width dimension from the difference between the diameter of this perfect circle and the diameter of the concave joint portion 3.

[0036] The bonding structure 10 described above can be used for various plastic parts and products. For example, it can be used in automobiles, motorcycles, bicycles, daily necessities, household appliances, personal computers, cameras, toys, various exterior bodies, various containers, etc. In particular, the bonding structure 10 can be used, for example, for the exterior body of a wire harness for in-vehicle use in automobiles. That is, such a wire harness with an exterior body includes a wire harness and an exterior body for a wire harness using the bonding structure 10 described above. Here, the exterior body for a wire harness, as an example, can surround all or part of the wire harness from the outside, or protect it by attaching to a part of the outer periphery, or regulate the extending direction of the wire harness.

[0037] 2. Manufacturing method of the bonding structure Hereinafter, the bonding structure of the present embodiment will be described with reference to the drawings. FIG. 4 is a schematic diagram for explaining the manufacturing method of the bonding structure of the present embodiment.

[0038] The manufacturing method of the joining structure according to this embodiment includes a step of overlapping a first member 1A made of a first resin and a second member 2A made of a second resin having physical properties with a higher foaming ratio than the first resin (Figs. 4(a) to (b)), and a step of joining the first member 1 and the second member 2 by pressing and thermally melting the second member 2A from the outer surface side of the second member 2A until reaching at least the inside of the first member 1A to form a concave joining portion 3 (Figs. 4(c) to (e)).

[0039] The method of pressing and thermal melting is not particularly limited as long as it is a method of pressing while melting the first member 1A and the second member 2A by applying heat. For example, the pressing and thermal melting of the second member 2A can also be performed by applying a pressing force using a soldering iron, a hot plate, or the like. Further, the pressing and thermal melting of the second member 2A is preferably performed by ultrasonic vibration by an ultrasonic welding method and a pressing force. Specifically, this ultrasonic welding method is preferably performed by abutting the protrusion of a welding horn H having a protrusion at the tip against the outer surface of the second member 2A.

[0040] In this way, by pressing and thermally melting the second member 2A from the outer surface side of the second member 2A made of a second resin having physical properties with a higher foaming ratio than the first member 1A until reaching at least the inside of the first member 1A to form the concave joining portion 3, the second resin constituting the second member 2A and the first resin constituting the first member 1A are melted and flow in the direction of the joining interface of these members. At this time, it is preferable that the welding horn H is pushed into the position of the first member 1A beyond the joining interface position 4, whereby at least the first resin constituting the first member 1A flows into the joining interface position 4 of the first member 1 and the second member 2 while being mixed with the second resin constituting the second member 2A. By such flow of the first resin and the second resin, a strong joining is achieved here.

[0041] By using the manufacturing method of such a joining structure 10, without forming a fitting structure with a complex shape and without using an adhesive or a double-sided tape, etc., a joining structure 10 in which the first member 1A and the second member 2A are firmly joined can be obtained. Moreover, since such a joining structure 10 does not need to form a complex structure such as a fitting structure for joining, the thickness of the joined part can be reduced.

[0042] Note that the present invention is not limited to the above-described embodiments, and can be freely changed without departing from the gist of the present invention.

[0043] [Examples] (Example 1) A plate-like member (thickness 1.5 mm) of non-foamed polypropylene resin (density 0.91 g / cm 3 ) as the first member and a plate-like member (thickness 1.5 mm) of foamed polypropylene resin (density 0.48 g / cm 3 ) as the second member were laminated, and using an ultrasonic welding apparatus (manufactured by Ultrasonic Industry Co., Ltd., small welder) having a welding horn with a tip portion of the shape shown in FIG. 5, from the outer surface side of the second member, until reaching inside the first member beyond the joining interface position, the second member was pressed and heat-melted to form a concave joining portion having a shape corresponding to the tip of the welding horn, and the first member and the second member were welded to obtain a joining structure sample.

[0044] (Comparative Example 1) A plate-like member (thickness 1.5 mm) of foamed polypropylene resin (density 0.48 g / cm 3 ) was used as the first member, and a plate-like member (thickness 1.5 mm) of non-foamed polypropylene resin (density 0.91 g / cm 3 ) was used as the second member. In the same manner as in Example 1, the first member and the second member were welded to obtain a joining structure sample.

[0045] (Comparative Example 2) A plate-like member (thickness 1.5 mm) of foamed polypropylene resin (density 0.48 g / cm 3 ) was used as the first member, and a plate-like member (thickness 1.5 mm) of foamed polypropylene resin (density 0.48 g / cm3 ) A bonding structure sample was obtained by welding the first member and the second member in the same manner as in Example 1, except that plate-like members (thickness: 1.5 mm) were used respectively.

[0046] (Reference Example 1) As the first member, a plate-like member (thickness: 1.5 mm) of non-foamed polypropylene resin (density: 0.91 g / cm 3 ) and as the second member, a plate-like member (thickness: 1.5 mm) of non-foamed polypropylene resin (density: 0.91 g / cm 3 ) A bonding structure sample was obtained by welding the first member and the second member in the same manner as in Example 1, except that plate-like members (thickness: 1.5 mm) were used respectively.

[0047] Five bonding structure samples of Example 1, Comparative Examples 1 to 2, and Reference Example 1 were manufactured respectively. The bonding strength between the first member and the second member was measured by measuring the maximum load when peeling the joint portion perpendicularly to the joint surface with a tensile testing machine. FIG. 6 is a distribution diagram of the bonding strength in the bonding structure samples of Example 1, Comparative Examples 1 to 2, and Reference Example 1. From this result, it was found that the bonding structure sample of Example 1 in which the second resin has a higher foaming ratio and is more easily heat-melted than the first resin has a higher bonding strength than the bonding structure sample of Comparative Example 1 in which the first resin has physical properties with a higher foaming ratio than the second resin, and the bonding structure sample of Comparative Example 2 in which the second resin and the first resin are composed of the same foamed resin.

[0048] For the bonded structure samples of Example 1 and Comparative Example 2, the longitudinal section including the concave bonding portion and the bonding surface of the first member when separated at the bonding interface position were observed with an optical microscope. Fig. 7(a) is an optical micrograph of the longitudinal section including the concave bonding portion of the bonded structure sample of Example 1, and Fig. 7(b) is an optical micrograph of the bonding surface of the first member when the first member and the second member constituting the bonded structure sample of Example 1 were separated at the bonding interface position. Also, Fig. 8(a) is an optical micrograph of the longitudinal section including the concave bonding portion of the bonded structure sample of Comparative Example 2, and Fig. 8(b) is an optical micrograph of the bonding surface of the first member when the first member and the second member constituting the bonded structure sample of Comparative Example 2 were separated at the bonding interface position. From the comparison between Fig. 7(b) and Fig. 8(b), it was found that the bonded structure sample of Example 1 in which the second resin has a physical property of a higher foaming ratio than the first resin has a larger heat-melted portion formed than the bonded structure sample of Comparative Example 2 in which the second resin and the first resin are composed of the same foamed resin.

Explanation of symbols

[0049] 10 Bonded structure 1, 1A First member 2, 2A Second member 3 Concave bonding portion 4 Bonding interface position 5 Bonding surface 6 Heat-melted portion

Claims

1. A joining structure for joining a first member made of a first resin and a second member made of a second resin, wherein the second resin has a physical property of a higher foaming ratio than the first resin, the first member and the second member have a concave joining portion that reaches at least inside the first member from the outer surface side of the second member in a superposed state, and the joining surface between the first member and the second member has a thermally melted portion that expands annularly outward, characterized in that it is a joining structure.

2. The joining structure according to claim 1, wherein the second resin is a foamed resin and the first resin is a non-foamed resin.

3. The joining structure according to claim 1 or 2, wherein the second resin is made of a material having a lower melting point than the first resin.

4. The joining structure according to claim 1, 2 or 3, wherein the second resin is made of a material having a lower density than the first resin.

5. The joining structure according to claim 1, wherein the dimension of the annular width of the thermally melted portion is 0.5 mm or more.

6. A joining structure for joining a first member made of a first resin and a second member made of a second resin, wherein the second resin has a physical property of a higher foaming ratio than the first resin, a wire harness exterior body using a joining structure having a concave joining portion that reaches at least inside the first member from the outer surface side of the second member in a superposed state of the first member and the second member.

7. A wire harness and the wire harness exterior body according to claim 6, wherein the wire harness exterior body surrounds the wire harness from the outside or attaches to a part of the outer periphery to protect it, characterized in that it is a wire harness with an exterior body.

8. A step of superposing a first member made of a first resin and a second member made of a second resin having a physical property of a higher foaming ratio than the first resin, and a step of joining the first member and the second member by pressing and thermally melting the second member until it reaches at least inside the first member from the outer surface side of the second member to form a concave joining portion, wherein the pressing and thermal melting of the second member is performed by ultrasonic vibration and pressing force by an ultrasonic welding method, which is a joining method.

9. The joining method according to claim 8, wherein the ultrasonic welding method is performed by abutting the protrusion of a welding horn having a protrusion at the tip against the outer surface of the second member. ​ ​ ​ ​ ​

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