JPH04183882A - Rust preventive structure in mating part of steel plate of vehicle body - Google Patents

Abstract

PURPOSE:To improve weldability and workability and to provide the rust preventive structure advantageous in terms of cost by crimping a rust preventive sheet formed by sticking an adhesive to a metal of a specific thickness having the natural electrode potential lower than the natural electrode potential of the steel plate of a vehicle body between the joint surfaces of the mating part of the steel plates. CONSTITUTION:A roof reinforce 2 which reinforces a bent roof panel 1 forming a sun roof aperture 9 of, for example, the vehicle body, from an interior 10 side is spot welded to this roof panel in the above-mentioned aperture 9. The rust preventive sheet 3 is formed of metallic foil 4 of <=500mum thickness of the metal (Zn, Al, etc.) having the natural electrode potential lower than the natural electrode potential of the steel constituting the roof panel 1 and the reinforce 2 and the adhesive 5 (epoxy resin, etc.) of <=2mum thickness stuck to one surface of this metallic foil 4. This rust preventive sheet 3 is crimped to the spot weld zone between the front end of the roof panel 1 and the front end of the reinforce 2 and the spot welding is executed under prescribed conditions. The rust preventive structure having excellent rust preventive performance is imparted to the mating part of the steel plates of the vehicle body in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a rust-preventing structure for protecting from corrosion a joint of two steel plates for a vehicle body joined by bringing them into surface contact.

(Prior Art) An automobile body is assembled by joining a plurality of press-formed panels by spot welding or the like, and then transported to a painting process. In the electrodeposition process of the painting process, the car body is completely immersed in an electrodeposition bath to form an electrodeposition coating over the entire car body, including the bag structure, but the panels are joined face-to-face by spot welding, etc. It is extremely difficult to form a chemical conversion film or an electrodeposited film on the so-called ``joint parts of steel plates'' in a short period of time. In particular, it is impossible to form an electrodeposited coating near the spot welding points.

As shown in FIG. 11, a so-called anti-corrosion steel plate has been conventionally employed in which a galvanized layer 7 is formed on both or one side of the car body steel plates 1.2 to protect the mating portions from corrosion. However, the rust-proof steel plate is not only expensive, but also has a large surface roughness and irregular surface irregularities, which has a problem of adversely affecting the image clarity of the top coat. Furthermore, in areas where road de-icing agents are sprayed, in areas with severe corrosive environments such as coastal areas, or in joints of steel plates where moisture easily penetrates and is difficult to remove, the use of anti-rust steel plates is still not sufficient. .

Therefore, in order to further improve the rust prevention ability, as shown in FIG.
There is also known a rust-proof structure in which the mating portions are sandwiched and welded (see Japanese Patent Laid-Open No. 153,787/1987, etc.).

(Problem to be solved by the invention) However, when plate-shaped zinc etc. with a thickness on the order of mm is used, although the rust prevention ability is improved, weldability (continuous dots) is extremely reduced. There were drawbacks. Also,
The work involved in attaching the joints of the steel plates is extremely complicated, and the cost is significantly higher than when rust-proof steel plates are used.

The present invention has been made in view of the problems of the prior art, and it is an object of the present invention to provide a rust-proof structure that improves weldability and workability and is advantageous in terms of cost.

(Means for Solving the Problems) In order to achieve the above object, the rust-preventing structure at the joining part of car body steel plates of the present invention is a car body steel plate in which a rust-preventing sheet is sandwiched between the joining surfaces of two steel plates to be joined. The rust-preventing structure at the mating part is characterized in that the rust-preventing sheet has a metal with a thickness of 500 μm or less, which has a lower natural electrode potential than the car body steel plate, and an adhesive stuck to this metal. It is said that

This adhesive is preferably a synthetic resin having a thickness of 2 μm or less, or a synthetic resin mixed with metal powder and/or graphite and having a thickness of 2 μm or more.

Further, there is provided a rust-preventing structure at the joint portion of car body steel plates in which a rust-preventing sheet is sandwiched between the joining surfaces of two steel plates to be joined, the rust-preventing sheet being made of a resin blended with metal powder and/or graphite. The above object can also be achieved by a rust-preventing structure in the mating part of car body steel plates, which is characterized by having a film and a metal with a thickness of 300 μm or less, which is stuck to at least one side of the resin film and has a lower natural electrode potential than the car body steel plates. can be achieved.

At this time, it is preferable to apply an adhesive to at least one side of the anti-rust sheet, and the adhesive is made of a synthetic resin with a thickness of 2 μm or less, or a synthetic resin mixed with metal powder and/or graphite. is preferably 2 It rn or more.

(Function) In the present invention configured as described above, the anti-corrosion sheet is formed into a thin plate shape, and a conductive or thin film adhesive is provided, so that it is easy to attach the sheet to the mating portion of the steel plates. When carrying out this process, the anticorrosion sheet can freely expand and contract to suit the shape of the mating part, and can be easily attached to the appropriate position, greatly improving work efficiency. Furthermore, because the adhesive conducts electricity, it has excellent continuous dot performance.

(Example) 'Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view of a sunroof opening showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a rust-preventing sheet according to the same embodiment.

114 of the sunroof opening of the vehicle body, as shown in FIG.
The structure consists of a roof panel 1 that is bent to form an opening 9, and a roof reinforcement 2 for reinforcing the roof panel 1 from the indoor side 10.
are joined by spot welding (in the figure, the electrode tip 11 is indicated by a two-dot chain line). The rust-proof structure of this example is
When spot welding the tip of the sunroof opening 9 of this roof panel 1 and the tip of the reinforcement 2,
A rust prevention sheet 3 is provided between the welding surfaces (spot margins).

As shown in FIG. 2, the rust prevention sheet 3 according to this embodiment is
A metal foil 4 with a thickness of 500 μm or less is made of a metal whose natural electrode potential is lower than that of steel constituting the roof panel 1 and the reinforcement 2, and an adhesive 5 with a thickness of 2 μm or less is adhered to one side of the metal foil 4. Examples of metals that have a lower natural electrode potential than steel and are preferable for use in the metal foil 4 of this embodiment include zinc, aluminum, zinc-aluminum alloy, and zinc-nickel alloy. On the other hand, when the adhesive 5 attached to the metal foil 4 is made of an insulator such as an epoxy resin, the thickness is preferably 2 μm or less. Further, the adhesive 5 may be made of a copolymer of ethylene and vinyl acetate or butyl rubber, and graphite or zinc powder may be added thereto to impart electrical conductivity. In this case, even if the thickness is 2 μm or more, weldability is not affected.

Such a rust preventive sheet 1-3 is formed into a band shape corresponding to the width of the spot surface, and the spot surface of one steel plate (roof reinforcement 2 in the case of the sunroof opening shown in FIG. 1) is formed with adhesive 5. Paste it on. Then, this steel plate 2 and the other steel plate (roof panel 1) are assembled so that both spot surfaces are in contact with each other, and spot welding is performed under predetermined welding conditions.

At this time, since the anti-rust sheet 3 of this embodiment is a thin plate, even if the shape of the part to be pasted is complex, it will expand and contract appropriately, will not break during work, and will improve workability. good. Therefore, it becomes possible to accurately adhere the adhesive to the mating portion. Furthermore, since the anticorrosive sheet of this example is in the form of a thin plate, there is no problem with weldability (continuous dot performance).

Note that the rust prevention sheet 3 according to the present invention can be modified in various ways without being limited to the above-mentioned embodiments.
3 to 5 are cross-sectional views showing other embodiments of the anticorrosion sheet according to the present invention.

First, the anticorrosion sheet 3 shown in FIG. 3 is made by forming the same metal foil 4 as in the first embodiment described above to a thickness of 300 μm or less, and pasting a resin film 6 on this metal foil 4. be. This resin film 6 is based on a synthetic resin such as polyester, nylon, polyethylene, SBH, etc., and has conductivity added to it.5. To achieve this, zinc powder, aluminum powder, or graphite is blended.

Further, the rust prevention sheet 3 shown in FIG. 4 is obtained by pasting the metal foil 4 of the second example on both sides of the resin film 6 of the second example described above, and the rust prevention sheet 3 shown in FIG. In this example, an adhesive 5 is further adhered to the anticorrosion sheet 3 shown in FIG. The adhesive 5 in this case can be the same as the adhesive in the first embodiment, and if it is made of an insulator such as epoxy resin, the thickness should be 2 μm or less, and
When forming a thick film of 2 μm or more, it is necessary to add graphite or zinc powder to a base such as a copolymer of ethylene and vinyl acetate or butyl rubber to impart conductivity.

Even in the case of this configuration, similar to the first embodiment described above, effects such as workability of adhesion to the mating portion, spot weldability (continuous dot performance), cost reduction, etc. can be obtained.

The rust prevention structure of the joint portion of the steel plates of the present invention is not limited to the sunroof panel opening 9 such as a double series, but can also be applied to the vehicle body or parts such as members attached to the vehicle body. It is possible to apply.

For example, front fender drip part and hood ridge, front pillar upper and lower, door inner and weatherstrip retainer, sill and pillar, pillar and pillar reinforcement, front fender and radio core support upper, hood inner and hood hinge reinforcement, hood Inner and hood striker reinforcement, hood outer and hood inner, door inner and door lock reinforcement, rear fender and wheel house inch, front floor holder, rear floor holder,
Rear floor rear and floor side, rear 10 = preferred for use in the joints of steel plates such as fender and floor side, rear fender and rear waist, rear floor rear panel, rear fender and rear panel.

Next, the present invention will be explained in further detail, but the present invention is not limited thereto, and various modifications can be made without exceeding the gist of the present invention.

(1) Test piece production Example 1 As shown in Figures 6 and 7, the plate thickness is 0.8 mm and the size is 7 mm.
A cold rolled steel plate 20 of 0mm x 150mm was bent at 30' so that a cold rolled steel plate 21 with a thickness of 0.8mm and a width of 50mm was 60mm, and between the two steel plates 20 and 21, Thickness 1.5 made of epoxy resin
As shown in the figure, spot welding 22 was performed at two locations with a 30 μm thick zinc foil (corrosion prevention sheet 3) having a μm thick adhesive sandwiched therebetween.

This test piece was conveyed to the degreasing step, chemical conversion treatment step, electrodeposition coating step, and drying step of the painting process, and an electrodeposition coating film was formed on the surface of the steel plate. Furthermore, the three sides shown in the figure of the joint of both steel plates are sealed with a vinyl chloride resin sealant 23, so that when performing a salt spray test, water will only enter the joint of both steel plates from side A. I made it.

Example 2 The zinc foil in Example 1 was replaced with an aluminum foil with a thickness of 50 μm, and the adhesive was a 70/30 mixture of ethylene-acetic acid copolymer and graphite, except that the adhesive had a thickness of 5 μm. , was produced in the same manner as in Example 1.

Example 3 The same procedure was carried out except that the zinc foil in Example 1 was a 40 μm thick zinc-aluminum alloy foil, and the adhesive was a 20 μm thick adhesive made of a 30/70 mixture of butyl rubber and zinc powder. It was produced in the same manner as in Example 1.

Example 4 12 Same as Example 1 except that the zinc foil in Example 1 was a 500 μm thick zinc-nickel alloy foil and the adhesive was an epoxy resin adhesive with a thickness of 1 μm. Created.

Example 5 The zinc-nickel alloy foil of Example 4 was bound to a rust-proof sheet with 20 μm thick zinc foil attached to both sides of a 20 μm thick resin film made by mixing polyester resin with zinc powder at a ratio of 40/60. It was produced in the same manner as in Example 4 except for the above.

Example 6 The rust preventive sheet of Example 5 was used except that 30 μm thick aluminum foil was attached to both sides of a 20 μm thick resin film made of a 20/80 mixture of nylon resin and aluminum powder. , was produced in the same manner as in Example 5.

Example 7 The anticorrosive sheet of Example 5 was prepared by pasting 40 μm thick zinc-aluminum alloy foil on both sides of a 30 μm thick resin film made of a 30/70 mixture of polyethylene resin and zinc powder. It was produced in the same manner as in Example 5 except for the following.

Example 8 Zinc-nickel alloy foils with thicknesses of 100 μm and 150 μm were pasted on both sides of a 30 μm thick resin film made by mixing the anticorrosive sheet of Example 5 with SBR resin and graphite in a ratio of 80/20. Example 5 except that
It was made in the same way.

Example 9 A 50 μm thick zinc-nickel alloy foil and a zinc-aluminum alloy foil were placed on both sides of a 20 μm thick resin film made by mixing the rust prevention sheet of Example 5 with polyester resin and zinc powder in a ratio of 30/70. It was produced in the same manner as in Example 5, except that these were each pasted.

Comparative Example 1 The material of both steel plates 20 and 21 of Example 1 was G1-90,
Except these steel plates were directly aligned and spot welded.
It was produced in the same manner as in Example 1. In addition, the material of both steel plates is 5C.
PSEG-30, EG-60SGA-30SGA-60
A test piece was prepared and the corrosion resistance was evaluated in the same manner.

Comparative Example 2 A sheet was produced in the same manner as in Example 1, except that the anticorrosive sheet in Example 1 was replaced with a zinc plate with a thickness of 1 mm.

(2) Evaluation of corrosion resistance and continuous dot performance Salt water was sprayed on each test piece thus obtained for 4 hours, dried for 2 hours, and then moistened for 2 hours. Such corrosion cycles were performed 250 times, and the maximum plate thickness reduction of both steel plates was measured. This result□・
is shown in Figure 9.

In addition, the plate thickness gap is 0, the electrode pressure direction is perpendicular to the plane, the pressure force is 200 kgf, and the electrode tip has a diameter of 5°5 m.
Continuous welding was performed under the welding conditions of mφ CF type and direct welding using a constant current timer, and the continuous dot performance was compared by measuring the nugget diameter. The results are shown in FIG.

(3) Results Regarding corrosion resistance, the corrosion resistance of cold-rolled steel sheets is 250 μm, and the corrosion resistance of so-called rust-proof steel sheets is 200 to 50 μm, whereas Examples 1 to 9 have a corrosion resistance of 10 to 20 μm, and Comparative Example 2 (1 mm zinc sheet ) is understood to have rust prevention performance equivalent to that of

Regarding weldability, all of Examples 1 to 9 had continuous 2
000 dots is possible, whereas Comparative Example 1 has 10 dots.
00 RBIs, in Comparative Example 2 it was less than 200 RBIs,
It can be seen how practical Examples 1-9 are.

(Effects of the Invention) As described in 41 below, the rust-preventing structure of the joint portion of car body steel plates of the present invention has superior rust-preventing performance than so-called rust-preventive steel plates, is advantageous in terms of cost, and has improved workability and Weldability is also significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a sunroof opening showing an embodiment of the present invention, Fig. 2 is a cross-sectional view of a rust-preventing sheet according to the same embodiment, and Figs. 6-8 are plan views and sectional views showing test pieces according to specific examples of the present invention, and FIGS. 9-10 are graphs and graphs showing the results of the same examples. Figures 11 and 12 are cross-sectional views showing conventional rust prevention structures. 1... Roof panel (steel plate), 2... Roof reinforcement (steel plate), 3... Rust prevention sheet, 4... Metal foil, 5... Adhesive,
6...Resin film. Patent applicant: Nissan Motor Co., Ltd. Japan Pariki Rising Co., Ltd. Agent Patent attorney 8 1) Mikio (1 other person)

Claims (5)

[Claims] (1) A rust-preventing structure at a joint portion of car body steel plates in which a rust-preventing sheet is sandwiched between the joining surfaces of two steel plates to be joined, wherein the rust-preventing sheet has a lower natural electrode potential than the car body steel plates. A rust-preventing structure for a mating portion of car body steel plates, comprising a metal having a thickness of 500 μm or less and an adhesive bonded to the metal. (2) A rust-preventing structure at the joining part of car body steel plates in which a rust-preventing sheet is sandwiched between the joining surfaces of two steel plates to be joined, the rust-preventing sheet containing metal powder and/or graphite. A rust-preventing structure for a mating portion of a car body steel plate, comprising a resin film and a metal having a thickness of 300 μm or less and having a lower natural electrode potential than the car body steel plate and attached to at least one side of the resin film. (3) The rust-preventing structure for a mating portion of vehicle body steel plates according to claim 2, wherein an adhesive is adhered to at least one side of the rust-preventing sheet. (4) The anti-corrosion structure for a mating portion of car body steel plates according to claim 1 or 3, wherein the adhesive is made of a synthetic resin having a thickness of 2 μm or less. (5) The rust-preventing structure for a mating portion of car body steel plates according to claim 1 or 3, wherein the adhesive is a synthetic resin mixed with metal powder and/or graphite and has a thickness of 2 μm or more.