Patent Description:
Patent Document <NUM> discloses a joint structure in which a first metal material and a dissimilar material that is difficult to be welded to the first metal material overlap each other, and a filler material (welding wire) is arc-welded through a through-portion of the dissimilar material.

A part of the melted filler material forms a flange so as to cover an upper outer periphery of the through-portion of the dissimilar material. Accordingly, the dissimilar material and the first metal material are fixed to each other by a compressive fixing force between the flange and the first metal material due to solidification shrinkage of the filler material onto the first metal material. The document <CIT> discloses an arc-spot welding method for joining different materials, the document <CIT> discloses a joint structure and the document <CIT> discloses a junction structure.

However, according to the invention of Patent Document <NUM>, moisture may enter from outside through a gap between overlapped surfaces of the first metal material and a second metal material. Electrolytic corrosion may thus occur in an area where the first metal material and the second metal material overlap each other due to the entry of the moisture, and joint strength between the materials may decrease.

In view of the foregoing, it is an object of the present invention to reduce occurrence of electrolytic corrosion in an area where a metal material and a dissimilar material overlap each other.

An aspect of the present disclosure is directed to a joint structure including a first member made of a metal material, a second member made of a material that is difficult to be welded to the first member, and a third member made of a filler material and welded to the first member, the first member, the second member, and the third member being joined together, and provides a solution as in the following.

That is, in a first aspect of the present disclosure, the second member includes a through-portion penetrating toward the first member;.

According to the first aspect, at least one of the overlapped surfaces of the first member and the second member includes the recess. The recess is formed into a space separate from the through-portion and is recessed so as to surround the entire periphery of the through-portion of the second member. The recess is formed in a space separate from the welded part, which is a welding site where the first member and the third member are welded together. The recess is recessed so as to surround the entire periphery of the welded part. The recess communicates with the injection hole. The recess is provided with the sealing material injected from the injection hole.

Since the gap between the overlapped surfaces of the first member and the second member is closed with the sealing material in this manner, it is possible to keep moisture from entering from the outside into an area where the first member and the second member overlap each other.

This makes it possible to reduce occurrence of electrolytic corrosion in the area where the first member and the second member overlap each other at the welded part, which is a welding site where the first member and the third member are welded together, and to secure joining strength.

A second aspect is an embodiment of the first aspect. In the second aspect,
the injection hole includes a plurality of injection holes, the injection holes being disposed along the recess.

According to the second aspect, the plurality of injection holes are disposed along the recess. This allows the sealing material to spread all around and throughout the recess and improve sealing properties. Further, simultaneously injecting the sealing material from the plurality of the injection holes makes it possible to perform the injection of the sealing material in a short time.

A third aspect is an embodiment of the first or second aspect. In the third aspect,
the recess has a width larger than a diameter of the injection hole.

In the third aspect, the width of the recess is larger than the diameter of the injection hole. Consequently, the sealing material injected from the injection hole spreads transversely inside the recess. This allows the sealing material to be installed over an increased area inside the recess, which improves sealing properties.

A fourth aspect is an embodiment of any one of the first to third aspects. In the fourth aspect,
the recess is formed in the first member having a smaller plate thickness than the second member, the recess being obtained by plastically deforming the first member into a three-dimensional shape.

This configuration increases the strength of the first member having a smaller plate thickness than the second member.

A fifth aspect of the present disclosure is directed to a joining method for joining together a first member made of a metal material, a second member made of a material that is difficult to be welded to the first member, and a third member made of a filler material and welded to the first member. The second member includes a through-portion penetrating toward the first member;.

In the fifth aspect, after the third member is welded to the first member through the through-portion, the sealing material is injected into the recess from the injection hole. The recess is formed into a space separate from the through-portion and is formed into a space separate from the welded part, which is a welding site where the first member and the third member are welded together. The recess is recessed so as to surround the entire peripheries of the welded part and the through-portion.

The sealing material injected after the second member is compressed and fixed by solidification and contraction of the third member on the first member prevents the sealing material from being deformed, or part of the sealing material from evaporating and generating gas, due to heat during welding. This allows the sealing material to spread all around and throughout the recess and improve sealing properties.

This makes it possible to reduce occurrence of electrolytic corrosion in the area where the first member and the second member overlap each other around the welded part, which is a welding site where the first member and the third member are welded together, and to secure joining strength.

A sixth aspect is an embodiment of the fifth aspect. In the sixth aspect,
the recess is formed in the first member having a smaller plate thickness than the second member, the recess being obtained by plastically deforming the first member into a three-dimensional shape.

According to the aspects of the present disclosure, it is possible to reduce occurrence of electrolytic corrosion in an area where a metal material and a dissimilar material overlap each other.

Note that the following description of preferred embodiments is merely an example in nature, and is not intended to limit the scope, applications, or use of the present invention.

<FIG> shows a j oint structure for joining together a first member <NUM> made of a metal material, a second member <NUM> made of a material that is difficult to be welded to the first member <NUM>, and a third member <NUM> made of a filler material.

The first member <NUM> is a plate-shaped member made of the metal material.

The second member <NUM> is a plate-shaped member made of the material that is difficult to be welded to the first member <NUM>. The second member <NUM> is arranged to overlap with an upper side of the first member <NUM>. The second member <NUM> has a circular through-portion <NUM> penetrating toward the first member <NUM>.

In the present embodiment, the through-portion <NUM> is described as a circular through-hole, but may be an elliptical or elongated through-hole.

The second member <NUM> has a recess <NUM>. The recess <NUM> is formed in the overlapped surface of the second member <NUM> with the first member <NUM>. The recess <NUM> is formed into a space separate from the through-portion <NUM> and is recessed so as to surround the entire periphery of the through-portion <NUM>. The recess <NUM> is formed into a space separate from a welded part that is a welding site where the first member <NUM> and the third member <NUM> are welded together. The recess <NUM> is recessed so as to surround the entire periphery of the welded part. The first member <NUM> is arranged so as to close a lower opening of the recess <NUM>.

The second member <NUM> has an injection hole <NUM>. The injection hole <NUM> communicates with the recess <NUM>. A plurality of the injection holes <NUM> (four injection holes in an example shown in <FIG>) are disposed along the recess <NUM>.

The recess <NUM> is provided with a sealing material <NUM>. The sealing material <NUM> is, for example, a resin material or an adhesive, and is injected into the recess <NUM> from the injection holes <NUM> using a dispenser <NUM>. After being injected into the recess <NUM>, the sealing material <NUM> is cured and closes a gap between overlapped surfaces of the first member <NUM> and the second member <NUM>.

In an example shown in <FIG>, the recess <NUM> is formed in a rectangular frame shape in a plan view. The injection holes <NUM> are formed in the middle positions of respective four sides of the recess <NUM>. The diameter of the injection hole <NUM> is substantially equal to a width of the recess <NUM>. However, the number, positions, and sizes of the injection holes <NUM> may be set freely.

The third member <NUM> is made of a filler material that is a metal material of the same type as the metal material for the first member <NUM>. The metal materials of the same type as used herein are metals that can be welded to each other, and are not only metal materials of an identical quality but also metal materials satisfactorily weldable to each other, such as ferrous metal materials or nonferrous metal materials. In other words, the metal materials of the same type are materials of the same type that are compatible with each other in welding.

Specifically, examples of a combination of the first member <NUM> and the third member <NUM> for welding include the following. For example, combinations of ferrous metal materials include mild steel and mild steel, stainless steel and stainless steel, mild steel and high-tensile steel, high-tensile steel and high-tensile steel, etc. Examples of combinations of nonferrous metal materials include aluminum and aluminum, aluminum and aluminum alloy, aluminum alloy and aluminum alloy, etc..

The second member <NUM> as a dissimilar material is a material of different quality from the quality of the first member <NUM> and the third member <NUM> as metal materials of the same type, and is difficult to be welded to the first member <NUM> and the third member <NUM>.

The first member <NUM> and the third member <NUM> as metal materials of the same type are ferrous metal materials, the second member <NUM> as a dissimilar material is a nonferrous metal material such as a copper material or an aluminum material. For example, resin materials such as carbon fiber reinforced plastics (CFRP), polyethylene terephthalate (PET), and engineering plastics are also included as dissimilar materials from the metal materials.

In the following description, a mild steel material is used as the first member <NUM>; an aluminum material is used as the second member <NUM>; and a mild steel material is used as the third member <NUM> that is a filler material.

An arc welding machine <NUM> includes a nozzle <NUM> and a tip <NUM>. The nozzle <NUM> supplies a shielding gas or the like to a welding site of a welding target. The tip <NUM> supplies a welding current to the third member <NUM>.

The arc welding machine <NUM> supplies a welding current while feeding the third member <NUM> into the through-portion <NUM> of the second member <NUM>, thereby generating an arc <NUM> between the third member <NUM> and the first member <NUM>. The third member <NUM> melted by the arc welding is melt-bonded to the first member <NUM> and is laminated in the through-portion <NUM>. Then, the melted third member <NUM> fills the through-portion <NUM> up, flows out to an upper peripheral edge of the through-portion <NUM>, and spreads in a flange shape.

In a process in which the melted third member <NUM> becomes a bead, the third member <NUM> is provided with a flange <NUM> that presses the peripheral edge of the through-portion <NUM> of the second member <NUM>. The flange <NUM> projects radially outward from the through-portion <NUM> on a surface (an upper surface in <FIG>) of the second member <NUM> facing opposite to the first member <NUM>.

Thereafter, the third member <NUM> is solidified and contracted on the first member <NUM>, whereby the second member <NUM>, which is a dissimilar material, is compressed and fixed between the flange <NUM> and the first member <NUM>.

Next, using the dispenser <NUM>, the sealing material <NUM> is injected into the recess <NUM> from the plurality of the injection holes <NUM>. In one preferred embodiment, the sealing material <NUM> is injected in such an amount that the sealing material <NUM> fills an inside of the recess <NUM> and then overflows into the injection holes <NUM>. This allows the sealing material <NUM> to spread all around and throughout the recess <NUM>. Further, simultaneously injecting the sealing material from the plurality of the injection holes <NUM> makes it possible to perform the injection of the sealing material <NUM> in a short time.

Thereafter, the sealing material <NUM> is cured inside the recess <NUM> and hence closes the gap between the overlapped surfaces of the first member <NUM> and the second member <NUM>.

When the sealing material <NUM> is charged into the recess <NUM>, some of the plurality of the injection holes <NUM> may be used as air vent holes depending on viscosity of the sealing material <NUM>. In a process of injecting the sealing material <NUM> into the recess <NUM>, air remaining inside the recess <NUM> is discharged from some of the injection holes <NUM> functioning as air vent holes. This allows the recess <NUM> to be efficiently filled with the sealing material <NUM>.

In one preferred embodiment, in addition to the injection hole <NUM> for injecting the sealing material <NUM>, an injection hole <NUM> for discharging air remaining inside the recess <NUM> is provided.

In a case where the sealing material <NUM> is injected into the recess <NUM> from the plurality of the injection holes <NUM>, an air vent hole (not shown) may be provided in addition to the injection holes <NUM> to efficiently discharge air remaining inside the recess <NUM> in the process of injecting the sealing material <NUM> into the recess <NUM>. This allows the recess <NUM> to be filled with the sealing material <NUM> while the air remaining inside the recess <NUM> is efficiently discharged. This makes it possible to shorten time taken to fill the recess <NUM> with the sealing material <NUM>.

Some of the plurality of injection holes <NUM> for injecting the sealing material <NUM>, more specifically, at least some of the plurality of the injection holes <NUM> located in between the plurality of injection holes <NUM>, may be used as holes for discharging air inside the recess <NUM>. According to this configuration, when the sealing material <NUM> is charged from a plurality of the injection holes <NUM> at the same time, the air inside the recess <NUM> can be efficiently discharged from the injection holes <NUM> not injecting the sealing material <NUM> and located between the plurality of injection holes <NUM>.

As described above, according to the joint structure of the present embodiment, the recess <NUM> is formed into a space separate from the welded part, which is a welding site where the first member <NUM> and the third member <NUM> are welded together. The sealing material <NUM> is injected into a vertical injection path for the sealing material <NUM> and a lateral communication path. The vertical injection path is formed in the first member <NUM> as a part of the recess <NUM>. The lateral communication path is recessed so as to surround the entire periphery of the through-portion <NUM>. The gap between the overlapped surfaces of the first member <NUM> and the second member <NUM> is closed with the sealing material <NUM>. It is therefore possible to keep moisture from entering from the outside into an area where the first member <NUM> and the second member <NUM> overlap each other.

This makes it possible to reduce occurrence of electrolytic corrosion in the area where the first member <NUM> and the second member <NUM> overlap each other around the welded part, which is a welding site where the first member and the third member are welded together, and to secure joining strength.

In addition, since the sealing material <NUM> is injected after the second member <NUM> is compressed and fixed by solidification and contraction of the third member <NUM> on the first member <NUM>, the sealing material <NUM> is not deformed, nor part of the sealing material <NUM> evaporates or generates gas, due to heat during welding. This allows the sealing material <NUM> to spread all around and throughout the recess <NUM> and improve sealing properties.

In the following description, the same reference characters designate the same components as those of the first embodiment, and the description is focused only on differences between this embodiment and the first embodiment.

As shown in <FIG>, a second member <NUM> has a recess <NUM>. The recess <NUM> is formed in the overlapped surface of the second member <NUM> with the first member <NUM>. The recess <NUM> is formed into a space separate from the through-portion <NUM> and is recessed so as to surround the entire periphery of the through-portion <NUM>. The recess <NUM> is formed into a space separate from a welded part that is a welding site where the first member <NUM> and the third member <NUM> are welded together. The recess <NUM> is recessed so as to surround the entire periphery of the welded part. The first member <NUM> is arranged so as to close a lower opening of the recess <NUM>.

The second member <NUM> has an injection hole <NUM>. The injection hole <NUM> communicates with the recess <NUM>. A plurality of the injection holes <NUM> (eight injection holes in an example shown in <FIG>) are disposed along the recess <NUM>. The injection holes <NUM> are formed into a space separate from the welded part, which is a welding site where the first member <NUM> and the third member <NUM> are welded together.

The recess <NUM> is provided with a sealing material <NUM>. The sealing material <NUM> is injected into the recess <NUM> from the injection holes <NUM> using a dispenser <NUM>. After being injected into the recess <NUM>, the sealing material <NUM> is cured and closes a gap between overlapped surfaces of the first member <NUM> and the second member <NUM>.

In an example shown in <FIG>, the recess <NUM> is formed in a rectangular frame shape in a plan view. Two injection holes <NUM> are formed in each of four sides of the recess <NUM>. That is, eight injection holes <NUM> are formed along the recess <NUM>. The width of the recess <NUM> is larger than the diameter of the injection hole <NUM>. However, the number, positions, and sizes of the injection holes <NUM> may be set freely.

As shown in <FIG>, when the sealing material <NUM> is injected into the recess <NUM> from the plurality of the injection holes <NUM> using the dispenser <NUM>, the sealing material <NUM> spreads circumferentially and transversely inside the recess <NUM>. Thereafter, the sealing material <NUM> is cured inside the recess <NUM> and hence closes the gap between the overlapped surfaces of the first member <NUM> and the second member <NUM>.

This allows the sealing material <NUM> to be installed over an increased area inside the recess <NUM>, which improves sealing properties.

As shown in <FIG>, a first member <NUM> has a recess <NUM>. The recess <NUM> is formed in the overlapped surface of the first member <NUM> with a second member <NUM>. The recess <NUM> is formed by press-forming the first member <NUM> having a smaller plate thickness than the second member <NUM> to be plastically deformed into a three-dimensional shape. The recess <NUM> is recessed downward in a stepped shape. The recess <NUM> is formed into a space separate from the through-portion <NUM> and is recessed so as to surround the entire periphery of the through-portion <NUM>.

The second member <NUM> is disposed so as to close an upper opening of the recess <NUM>. The second member <NUM> has an injection hole <NUM>. The injection hole <NUM> communicates with the recess <NUM>. A plurality of the injection holes <NUM> are disposed along the recess <NUM>. The width of the recess <NUM> is larger than the diameter of the injection hole <NUM>. However, the number, positions, and sizes of the injection holes <NUM> may be set freely.

When the sealing material <NUM> is injected into the recess <NUM> from the plurality of the injection holes <NUM> using a dispenser <NUM>, the sealing material <NUM> spreads circumferentially and transversely inside the recess <NUM>. Thereafter, the sealing material <NUM> is cured inside the recess <NUM> and hence closes the gap between the overlapped surfaces of the first member <NUM> and the second member <NUM>.

The strength of the first member <NUM>, which has a smaller plate thickness than the second member <NUM>, is increased by the recess <NUM> formed in the stepped shape in the first member <NUM>.

The recess <NUM> is formed into a space separate from a welded part that is a welding site where the first member <NUM> and the third member <NUM> are welded together. The sealing material <NUM> is injected into a vertical injection path for the sealing material <NUM> and a lateral communication path. The vertical injection path is formed in the first member <NUM> as a part of the recess <NUM>. The lateral communication path is recessed so as to surround the entire periphery of the through-portion <NUM>. The sealing material <NUM> closes the gap between the overlapped surfaces of the first member <NUM> and the second member <NUM>, thereby improving sealing properties. This enables the joint structure to keep moisture from entering from the outside into an area where the first member <NUM> and the second member <NUM> overlap each other. It is therefore possible to reduce occurrence of electrolytic corrosion in the area where the first member <NUM> and the second member <NUM> overlap on each other and to secure joining strength.

As shown in <FIG>, a first member <NUM> has a recess <NUM>. The recess <NUM> is formed in the overlapped surface of the first member <NUM> with a second member <NUM>. The recess <NUM> is formed by press-forming the first member <NUM> having a smaller plate thickness than the second member <NUM> to be plastically deformed into a three-dimensional shape. The recess <NUM> is recessed downward in a stepped shape. The recess <NUM> is formed into a space separate from the through-portion <NUM> and is recessed so as to surround the entire periphery of the through-portion <NUM>. The second member <NUM> is disposed so as to close an upper opening of the recess <NUM>.

The first member <NUM> has an injection hole <NUM>. The injection hole <NUM> is formed into a space separate from a welded part that is a welding site where the first member <NUM> and a third member <NUM> are welded together. The injection hole <NUM> communicates with the recess <NUM>. A plurality of the injection holes <NUM> are disposed along the recess <NUM>. The width of the recess <NUM> is larger than the diameter of the injection hole <NUM>. However, the number, positions, and sizes of the injection holes <NUM> may be set freely.

The embodiments described above may be modified as follows.

In the present embodiments, arc welding is performed on the recess <NUM> in the first member <NUM>. However, for example, so-called laser filler welding may be performed in which laser welding is performed using a filler wire as a filler material.

In the present embodiments, the recess <NUM> is formed in the first member <NUM> or the second member <NUM>, but the recess <NUM> may be formed in each of the first member <NUM> and the second member <NUM>.

To discharge air remaining inside the recess <NUM> in the process of injecting the sealing material <NUM> into the recess <NUM> from the injection holes <NUM>, an air vent hole (not shown) may be provided in addition to the injection holes <NUM>, or some of the plurality of injection holes <NUM> may be used to function as an air vent hole. However, these forms are not construed to limit the scope of the present invention.

For example, the recess <NUM> is formed into a space separate from the through-portion <NUM>. The recess <NUM> is formed into a space separate from the welded part, which is a welding site where the first member <NUM> and the third member <NUM> are welded together. The recess <NUM> is recessed so as to surround the entire peripheries of the welded part and the through-portion <NUM>. A part of the recess <NUM> communicating all around the outer periphery of the through-portion <NUM> may communicate with, and be open to, a side face on the outer periphery of the overlapped surfaces of the first member <NUM> and the second member <NUM>, and this opening may serve as an air vent hole for discharging the air from the recess <NUM>.

Claim 1:
A joint structure including a first member (<NUM>) made of a metal material, a second member (<NUM>) made of a material that is difficult to be welded to the first member (<NUM>), and a third member (<NUM>) made of a filler material and welded to the first member (<NUM>),
wherein the first member (<NUM>) and the third member (<NUM>) are ferrous metal materials and the second member (<NUM>) is a nonferrous metal material or a resin material;
the first member (<NUM>), the second member (<NUM>), and the third member (<NUM>) being joined together,
the second member (<NUM>) including a through-portion (<NUM>) penetrating toward the first member (<NUM>),
the third member (<NUM>) being welded to the first member (<NUM>) through the through-portion (<NUM>),
at least one of overlapped surfaces of the first member (<NUM>) and the second member (<NUM>) including a recess (<NUM>) formed into a space separate from the through-portion (<NUM>), the recess (<NUM>) being recessed so as to surround an entire periphery of the through-portion (<NUM>),
the recess (<NUM>) being formed into a space separate from a welded part that is a welding site where the first member (<NUM>) and the third member (<NUM>) are welded together, the recess (<NUM>) being recessed so as to surround an entire periphery of the welded part,
characterized in that at least one of the first member (<NUM>) or the second member (<NUM>) including an injection hole (<NUM>) communicating with the recess (<NUM>), and
the recess (<NUM>) being provided with a sealing material (<NUM>) injected from the injection hole (<NUM>), the sealing material (<NUM>) closing a gap between the overlapped surfaces of the first member (<NUM>) and the second member (<NUM>).