This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-250697 filed on Dec. 26, 2016, the contents of which are incorporated herein by reference.
The present invention relates to a bonded structure containing a first member and a second member bonded to each other with an adhesive or a sealing member, at least one of the first member and the second member being a metal member, and also relates to a method of manufacturing the bonded structure.
Japanese Laid-Open Patent Publication No. 2014-128986 discloses a vehicle subframe made up of a bonded structure containing aluminum and carbon-fiber-reinforced plastic (CFRP) which are bonded to each other with an adhesive. Japanese Laid-Open Patent Publication No. 2011-056583 discloses a composite material laser machining method of filling, with a filler material, a joined portion of welded joint between fiber-reinforced plastic (FRP) and metal, irradiating the filler material with a laser beam to thereby melt the filler material and performing laser welding.
Japanese Laid-Open Patent Publication Nos. 2014-128986 and 2011-056583 do not refer to corrosion of bonded portions of the metal members and the CFRP or the FRP. In a metal such as aluminum, a casting member includes larger crystal grains than those of a wrought member. When the casting member and the fiber-reinforced plastic are adhesively bonded, impurities existing along the grain boundary of the casting member serve as local cells, and causes electrolytic corrosion (grain boundary corrosion). Then, corrosion intrudes into the interface between the casting member and the adhesive via the grain boundary, and consequently the adhesive is liable to be peeled off the casting member.
The present invention has been made by considering such tasks. An object of the present invention is to provide a bonded structure and a manufacturing method of the bonded structure that can suppress electrolytic corrosion occurring near an interface between a metal member and a bonding member such as an adhesive, and suitably bond a first member and a second member together.
According to a first aspect of the present invention, there is provided a bonded structure containing a first member and a second member bonded to each other with an adhesive or a sealing member, at least one of the first member and the second member being a metal member, wherein an amorphous structure layer is formed on a surface layer of the metal member, and an outer circumferential end portion of the adhesive or the sealing member interposed between a first member side bonded surface and a second member side bonded surface is located on a surface of the amorphous structure layer.
According to the configuration, the outer circumferential end portion of a bonding member such as the adhesive or the sealing member is disposed on the amorphous structure layer that does not include a grain boundary. Consequently, it is possible to prevent intrusion of electrolytic corrosion into the interface between the surface of the metal member (the surface of the amorphous structure layer) and the outer circumferential end portion of the bonding member. Thus, it is possible to suitably bond the first member and the second member to each other.
In the first aspect of the present invention, the first member may be the metal member, the second member may be a fiber-reinforced plastic member, the metal member and the fiber-reinforced plastic member may be bonded to each other with the adhesive, the amorphous structure layer may be formed on the surface layer of the metal member, and the outer circumferential end portion of the adhesive interposed between a metal member side bonded surface and a fiber-reinforced plastic member side bonded surface may be located on the surface of the amorphous structure layer.
The interface between the metal member and the outer circumferential end portion of the adhesive is close to outdoor air. Therefore, the electrolytic corrosion readily intrudes into the interface via the grain boundary. According to the configuration, the outer circumferential end portion of the adhesive is disposed on the amorphous structure layer which does not include the grain boundary. Consequently, it is possible to prevent intrusion of the electrolytic corrosion into the interface between the surfaces of the metal members (the surface of the amorphous structure layer) and the outer circumferential end portion of the adhesive. Thus, it is possible to suitably bond the metal members and the fiber-reinforced plastic member.
In the first aspect of the present invention, the metal member may include a first closed cross-sectional structure portion, the fiber-reinforced plastic member may include a second closed cross-sectional structure portion, the metal member side bonded surface may be provided on an outer circumferential surface of the first closed cross-sectional structure portion, the fiber-reinforced plastic member side bonded surface may be provided on an inner circumferential surface of the second closed cross-sectional structure portion, and the first closed cross-sectional structure portion may be disposed inside the second closed cross-sectional structure portion, and the outer circumferential surface of the first closed cross-sectional structure portion and the inner circumferential surface of the second closed cross-sectional structure portion may face toward each other.
According to the configuration, the metal member and the fiber-reinforced plastic member jointly form a socket-and-spigot structure. Thus, it is possible to easily bond the metal member and the fiber-reinforced plastic member.
In the first aspect of the present invention, the metal member side bonded surface may include a surface layer on which the surface of the amorphous structure layer is not formed.
In the first aspect of the present invention, a cavity surrounded by the adhesive may be formed on the surface layer.
According to a second aspect of the present invention, there is provided a bonded structure containing a first member and a second member bonded to each other with an adhesive or a sealing member, at least one of the first member and the second member being a metal member, wherein an amorphous structure layer is formed on a surface layer of the metal member, and a surface of the amorphous structure layer covers a metal member side bonded surface and a metal member side non-bonded surface, the adhesive or the sealing member being applied to the metal member side bonded surface for the metal member, and neither the adhesive nor the sealing member being applied to the metal member side non-bonded surface for the metal member.
According to the configuration, the surface of the amorphous structure layer which does not include the grain boundary is formed so as to cover the metal member side bonded surface and the metal member side non-bonded surface. Thus, the electrolytic corrosion does not occur in the interface between the surface of the metal member (the surface of the amorphous structure layer) and the outer circumferential end portion of the bonding member such as the adhesive or the sealing member. Thus, it is possible to suitably bond the first member and the second member together.
In the second aspect of the present invention, the first member may be the metal member, the second member may be a fiber-reinforced plastic member, the metal member and the fiber-reinforced plastic member may be bonded to each other with the adhesive, the amorphous structure layer may be formed on the surface layer of the metal member, and the surface of the amorphous structure layer may cover a metal member side bonded surface and a metal member side non-bonded surface, the adhesive being applied to the metal member side bonded surface for the metal member, and the adhesive not being applied to the metal member side non-bonded surface for the metal member.
According to the configuration, the surface of the amorphous structure layer which does not have the grain boundary is formed so as to cover the metal member side bonded surface and the metal member side non-bonded surface. Consequently, the electrolytic corrosion does not occur in the interface between the surface of the metal member (the surface of the amorphous structure layer) and the outer circumferential end portion of the adhesive. Thus, it is possible to suitably bond the metal member and the fiber-reinforced plastic member together.
In the second aspect of the present invention, the metal member may include a first closed cross-sectional structure portion, the fiber-reinforced plastic member may include a second closed cross-sectional structure portion, the metal member side bonded surface may be provided on an outer circumferential surface of the first closed cross-sectional structure portion, the fiber-reinforced plastic member side bonded surface may be provided on an inner circumferential surface of the second closed cross-sectional structure portion, and the first closed cross-sectional structure portion may be disposed inside the second closed cross-sectional structure portion, and the outer circumferential surface of the first closed cross-sectional structure portion and the inner circumferential surface of the second closed cross-sectional structure portion may face toward each other.
According to the configuration, the metal member and the fiber-reinforced plastic member jointly form the socket-and-spigot structure. Thus, it is possible to easily bond the metal member and the fiber-reinforced plastic member together.
In the second aspect of the present invention, the metal member side bonded surface may include a surface layer on which the surface of the amorphous structure layer is not formed.
In the second aspect of the present invention, a cavity surrounded by the adhesive may be formed on the surface layer.
According to the present invention, there is provided a method of manufacturing a bonded structure that contains a metal member and a fiber-reinforced plastic member bonded to each other with an adhesive, the method including:
irradiating the metal member with laser, and thereby forming an amorphous structure layer on a surface layer of the metal member; and disposing an outer circumferential end portion of the adhesive on a surface of the amorphous structure layer when bonding the metal member and the fiber-reinforced plastic member to each other with the adhesive.
According to the configuration, the outer circumferential end portion of the adhesive is disposed on the amorphous structure layer which does not have the grain boundary. Consequently, the electrolytic corrosion does not occur in the interface between the surface of the metal member (the surface of the amorphous structure layer) and the outer circumferential end portion of the adhesive. Thus, it is possible to suitably bond the metal member and the fiber-reinforced plastic member together.
According to the present invention, it is possible to prevent intrusion of the electrolytic corrosion into the interface between the surfaces of the metal member and the outer circumferential end portion of the bonding member such as the adhesive. Thus, it is possible to suitably bond the first member and the second member such as the metal member and the fiber-reinforced plastic member to each other.
The above and other objects features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.
A bonded structure according to an embodiment of the present invention will be described with reference to
As shown in
The subframe 12 supports an unillustrated engine, the steering mechanism 14 and the suspension 16. For example, a configuration disclosed in Japanese Laid-Open Patent Publication No. 2009-096370 is applicable to a relationship between the subframe 12 and parts around the subframe 12.
As shown in
The center beam 20 supports the engine (not shown) via a support rod 24 (
As shown in
A rod opening portion 42 is formed so as to extend from the front surface portion 30 to the inclined portion 38, and allows insertion of the support rod 24 therein. Bolt holes 44 are formed in the top surface portion 34 and the bottom surface portion 36, and are used to fix a rod support bolt 46 (
A fixing hole 52 is formed in the top surface portion 34, and is used to fix part of the steering mechanism 14 (gear box). A nut member 54 (
A rib 58 is formed between the top surface portion 34 and the bottom surface portion 36, in order to enhance the strength of the center beam 20.
Structures to be bonded to the side brackets 22L, 22R by using the plurality of bolts 60 and the adhesive 130 are arranged on the front surface portion 30, the back surface portion 32, the top surface portion 34 and the bottom surface portion 36 of the center beam 20. More specifically, through-holes 62 are formed in the front surface portion 30 and the bottom surface portion 36, and allow insertion of the bolts 60 therein.
End portions 66L, 66R of the center beam 20 correspond to the above second closed cross-sectional structure portions. In the back surface portion 32 and the top surface portion 34 of each of the end portions 66L, 66R of the center beam 20, injection ports 74 for injecting the adhesive 130, and confirmation holes 76 for confirming a degree of injection or filling of the adhesive 130 are formed. Each injection port 74 is located at the center of the four confirmation holes 76 arranged therearound. The number of the injection ports 74 and the number of the confirmation holes 76 are not limited to the above, and can be optionally selected according to factors such as positions and shapes of areas in which the adhesive 130 needs to be injected. In
The side brackets 22L, 22R are fixed to a main frame (not shown) of the vehicle 10 so that the entire subframe 12 is supported on the main frame. Further, the side brackets 22L, 22R support the steering mechanism 14 and the suspension 16 as shown in
As shown in
The bonded portion 80 is a hollow member made up of a front surface portion 90, a back surface portion 92, a top surface portion 94 and a bottom surface portion 96, and basically has a rectangular cross-sectional shape. Further, the bonded portion 80 includes at the front side an inclined portion 98 that inclines downward from the top surface portion 94 toward the front surface portion 90. Hence, each of the side brackets 22L, 22R has a closed cross-sectional structure portion (first closed cross-sectional structure portion) of a closed cross section, and includes an opening portion 100 formed on the center beam 20 side.
The bonded portion 80 corresponds to the first closed cross-sectional structure portion. The cross-sectional shape of the bonded portion 80 is substantially similar to the cross-sectional shape of the center beam 20. An outer circumference of the bracket bonded portion 80 is slightly smaller than an inner circumference of the center beam 20. Hence, the end portions 66L, 66R of the center beam 20 can be externally fitted onto the bonded portions 80 of the side brackets 22L, 22R. That is, the center beam 20 and the side brackets 22L, 22R jointly form a socket-and-spigot structure in which the first closed cross-sectional structure portions of the side brackets 22L, 22R are disposed inside the second closed cross-sectional structure portions of the center beam 20, and outer circumferential surfaces of the first closed cross-sectional structure portions and inner circumferential surfaces of the second closed cross-sectional structure portions face toward each other.
As shown in
Structures to be bonded to the center beam 20 by using the bolts 60 and the adhesive 130 are arranged on the front surface portions 90, the back surface portions 92, the top surface portions 94 and the bottom surface portions 96 of the side brackets 22L, 22R. More specifically, through-holes 102 are formed in the front surface portions 90 and the bottom surface portions 96, and allow insertion of the bolts 60 therein. Recesses 110 for guiding the adhesive 130 are formed in the top surface portion 94. Although not shown, the recesses 110 are also formed in the back surface portion 92.
In this description, portions at which the center beam 20 and the side brackets 22L, 22R are bonded are defined as follows. That is, surfaces (inner surfaces) of the front surface portion 30, the back surface portion 32, the top surface portion 34, the bottom surface portion 36 and the inclined portion 38 of the center beam 20 that are bonded to the side brackets 22L, 22R are referred to as beam-side bonded surfaces 120. Outer surfaces of the front surface portions 90, the back surface portion 92, the top surface portions 94, the bottom surface portions 96, and the inclined portions 98 of the side brackets 22L, 22R are referred to as bracket-side bonded surfaces 122.
Each of the beam-side bonded surfaces 120 includes a fiber-reinforced-plastic side bonded surface to which the adhesive 130 is applied, i.e., a bonded surface 34a (
The outer circumferential surfaces of the bonded portions 80 of the side brackets 22L, 22R and the inner circumferential surfaces of the end portions 66L, 66R of the center beam 20 are adhesively bonded.
As shown in
Although not shown, as with the top surface portion 94, the amorphous structure layer 200 is also formed on the front surface portion 90, the back surface portion 92, the bottom surface portion 96 and the inclined portion 98 of the right bracket 22R. A structure of the bonded area between the bonded portion 80 of the left bracket 22L, and the end portion 66L of the center beam 20 is also the same.
The amorphous structure layer 200 plays a role of preventing electrolytic corrosion of the metal member (the top surface portion 94 in the following description). This reason will be described with reference to
When the grain boundary 140 is exposed to outside air as in the top surface portion 94′ shown in
When the amorphous structure layer 200 is formed on a surface layer including the surface of the top surface portion 94 shown in
As shown in
As shown in
Irradiating the surface of the metal member (the top surface portion 94 in the following description) with laser light forms the amorphous structure layer 200 on the surface layer. The amorphous structure layer 200 has a surface roughness more than a predetermined level. A bottomed hole layer 214 (
The bottomed hole 212 includes an opening portion 216 on the surface of the bottomed hole layer 214. A cross-sectional shape of the bottomed hole 212 in the depth direction has a reverse-tapered shape (i.e., a shape in which the bottom side is larger than the opening side) including a bulged portion 220 having a larger inner circumference than the opening portion 216, between the opening portion 216 and a bottom portion 218. Many of the bottomed holes have a reverse-tapered shape in which the inner circumference gradually expands from the opening portion 216 toward the bottom portion 218 so that the bottom portion 218 is formed as the bulged portion 220.
A hook portion 222 having an undercut shape is formed around the opening portion 216. The hook portion 222 includes a head portion 224 which extends in non-parallel to a direction E parallel to an extending surface of the metal member, i.e., is inclined with respect to the direction E. The opening portion 216 is formed at one end side of the head portion 224. The length of the head portion 224 is 100 μm or less.
The bottomed hole layer 214 plays a role of improving the bonding strength of the adhesive 130. This reason will be described with reference to
As shown in
By contrast with this, the reverse-tapered shapes of the bottomed holes 212 shown in
Before the center beam 20 and the side brackets 22L, 22R are bonded, the surfaces of the bonded portions 80 of the side brackets 22L, 22R are irradiated with a laser. Conditions such as an intensity and an irradiation time of laser are set according to the thickness and an area of the amorphous structure layer 200. After the irradiation of the laser, the bonded portions 80 are cooled. The amorphous structure layer 200 is formed on each surface of the cooled bonded portion 80. Further, the bottomed hole layer 214 is formed on the surface layer of the amorphous structure layer 200. The bonded portion 80 can be cooled by natural cooling such as air cooling, or forced cooling such as use of an arbitrary cooling device.
Next, the adhesive 130 is applied to the bonded portions of the center beam 20 and the side brackets 22L, 22R, i.e., the beam-side bonded surface 120 and the bracket-side bonded surface 122 (
Next, the bonded portions 80 of the side brackets 22L, 22R are fitted into the end portions 66L, 66R of the center beam 20. The surface of the bottomed hole layer 214 formed on the surface layer of the bracket-side bonded surface 122, and the beam-side bonded surface 120 are arranged in facing relation to each other with the adhesive 130 interposed therebetween, and the bracket-side bonded surface 122 and the beam-side bonded surface 120 are bonded together. In this case, the outer circumferential end portion 132 of the adhesive 130 is disposed on the surface of the amorphous structure layer 200 (bottomed hole layer 214).
Next, the bolts 60 are screwed and tightened into the through-holes 62 of the center beam 20 and the through-holes 102 of the side brackets 22L, 22R to thereby adjust the thickness of the adhesive 130. The adhesive 130 is injected through the injection ports 74 of the center beam 20.
A manufacturing method disclosed in Japanese Laid-Open Patent Publication No. 2014-128986 is applicable except formation of the amorphous structure layer 200.
In the present embodiment, the subframe 12 that is a bonded structure has been described. However, the present invention can be also used for another structure containing the metal members and the fiber-reinforced plastic member adhesively bonded together. The present invention can be also used for an adhesively bonded portion of another structure that does not adopt the socket-and-spigot structure. Alternatively, one of an inner member and an outer member of the socket-and-spigot structure may be a metal member.
In the present embodiment, the bonded structure (center beam 20) containing the metal members (side brackets 22L, 22R) and the fiber-reinforced plastic member (center beam 20) adhesively bonded together has been described. However, the bonded structure to which the present invention is applicable is not limited to a bonded structure containing the metal members and the fiber-reinforced plastic member that are bonded to each other by an adhesive. At least one of the first member and the second member may be the metal member. For example, the present invention is applicable to bonded structures containing metal members and a glass (ceramic) member, or metal members and a plastic member, or metal members and a rubber member, or the like. A sealing member may be used instead of an adhesive.
As the sealing member, generally used members such as acrylic, urethane, polyurethane, silicone, modified silicone, oil caulking and polysulphide members can be used.
In the subframe 12 (bonded structure) according to the present embodiment, the amorphous structure layer 200 is formed on the surface layer of the bonded portion 80 of the right bracket 22R (metal member). The outer circumferential end portion 132 of the adhesive 130 interposed between the bonded surface 202 (metal member side bonded surface) of the bonded portion 80 of the right bracket 22R, and the bonded surface 34a (fiber-reinforced plastic member side bonded surface) of the end portion 66R of the center beam 20 (fiber-reinforced plastic member) is located on the surface of the amorphous structure layer 200.
According to the configuration, as shown in
In the subframe 12 (bonded structure) according to the present embodiment, the amorphous structure layer 200 is formed on the surface layer of the bonded portion 80 of the right bracket 22R (metal member). The surface of the amorphous structure layer 200 covers the bonded surface 202 (metal member side bonded surface) to which the adhesive 130 is applied for the bonded portion 80 of the right bracket 22R, and the non-bonded surface 204 (metal member side non-bonded surface) to which the adhesive 130 is not applied for the bonded portion 80.
According to the configuration, as shown in
The bonded portion 80 of the right bracket 22R (metal member) includes the first closed cross-sectional structure portion. The end portion 66R of the center beam 20 (fiber-reinforced plastic member) includes the second closed cross-sectional structure portion. The bonded surface 202 of the bonded portion 80 of the right bracket 22R is arranged on an outer circumferential surface of the first closed cross-sectional structure portion. The bonded surface 34a of the end portion 66R of the center beam 20 is arranged on the inner circumferential surface of the second closed cross-sectional structure portion. When the bonded portion 80 of the right bracket 22R is fitted into the end portion 66R of the center beam 20, the first closed cross-sectional structure portion is disposed inside the second closed cross-sectional structure portion, and the outer circumferential surface of the first closed cross-sectional structure portion and the inner circumferential surface of the second closed cross-sectional structure portion face toward each other.
According to the configuration, the right bracket 22R and the center beam 20 jointly form the socket-and-spigot structure. Consequently, it is possible to easily bond the right bracket 22R and the center beam 20.
In a method of manufacturing the subframe 12 (bonded structure) according to the present embodiment, the bonded portion 80 of the right bracket 22R (metal member) is irradiated with laser to thereby form the amorphous structure layer 200 on the surface layer of the bonded portion 80. When the bonded portion 80 of the right bracket 22R (metal member) and the end portion 66R of the center beam 20 (fiber-reinforced plastic member) are adhesively bonded, the outer circumferential end portion 132 of the adhesive 130 is disposed on the surface of the amorphous structure layer 200.
According to the configuration, as illustrated in
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood that variations and modifications can be effected thereto by those skilled in the art without departing from the scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
2016-250697 | Dec 2016 | JP | national |