JPH03258611A - Rust preventive method for hemming joint portion - Google Patents

Abstract

PURPOSE:To improve the productivity and to reduce the cost in a rust preventive method for a hemming joint portion by winding and sticking a film-like rust preventive material having a pressure sensitive adhesive layer round the end edge of a panel, and then hemming the same through the film-like rust preventive material. CONSTITUTION:The end edge 1a of the first panel 1 is wound round the end edge of the second panel 2 through a film-like rust preventive agent 3 and folded back to be joined. At the time of thus rust preventing the hemming joint portion, first of all, a rust preventive material 3 comprising a rust preventive agent layer 3a and a pressure sensitive adhesive layer 3b is wound and stuck to the end edge 1a of the first panel 1, and the end edge 3c is projected over the first panel end edge 1a. Secondly, the projecting portion 3d of the rust preventive agent 3 is folded back to cover the first panel end edge 1a. Subsequently, the second panel 2 is superimposed in such a manner as to project the first panel end edge 1a. The first panel end edge 1a is wound and folded back to perform hemming and bending, and then the rust prevented agent 3 is hardened by designated heating process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for preventing rust of hemming joints in panels such as automobile doors and trunk lids.

(Prior Art) Conventionally, automobile doors and the like are hemmed together, and the manufacturing process thereof will be explained with reference to FIG. First, as shown in Fig. 3a, both the outer spring 1 and the inner panel 2 are individually press-molded, and then a bead of anti-corrosion seeker a is applied to the outer panel 1 as shown in Fig. 3. Then, as shown in FIG. 3C, the inner panel 2 is superimposed on the outer panel 1, and hemming is performed as shown in FIG. 3D. After that, pretreatment and electrodeposition coating are applied, and as shown in Fig. 3e, the edge 1a of the outer panel 1 is coated with body sealer. Rust preventive seeker a protrudes during hemming process, and when applying body sealer b in the later process, use a hemming gun to remove the outer panel l.
Because it is moved along the edge 1a of the rust preventive seeker a, there is a risk that the protruding part of the rust preventive seeker a may get in the way and come off the edge 1a. Not only can the interior not be completely filled and a sufficient rust prevention effect cannot be obtained, but the air remaining between Rust Prevention 7-A and Body Seek 1) expands during baking painting, causing Body Seek 6 Blistering occurred on the surface, and in severe cases, there was a problem that holes should not be made in the body seam 96.

As a countermeasure against this problem, a rust prevention method for a hemming joint shown in FIGS. 4 and 5 is proposed, as disclosed in Japanese Patent Application Laid-open No. 146716/1983. In this rust prevention method, as shown in FIG. 5, a film-like rust preventive agent 4 having an irregular cross section having a bulged portion 4b at an end 4a is applied to an edge 2a of an inner panel 2 as shown in FIG. 4a. The outer panel 1 is superimposed on the inner panel 2 to which the rust preventive agent 4 is attached, and in this state, as shown in FIG. After that, the rust preventive agent 4 is hardened as shown in FIG. 4.

(Problems to be Solved by the Invention) According to the conventional example described in 1., a film-like rust preventive agent is wound and pasted on the edge of the inner panel in advance, and the end edge of the inner panel to which the rust preventive agent is pasted is rolled and folded back. By performing hemming processing, it is possible to completely fill the rust preventive agent in the hemmed joint and create a product with no voids, but it requires skill to apply the film-like rust preventive agent to the designated location, and it is difficult to apply it. The position may shift, or it may shift during the hemming process. When the film-like rust preventive agent is displaced, a gap J is created between the bulge 41) formed on the film-like rust preventive agent 4 and the edge 1a of the outer panel 1, as shown in the cross section of FIG. Even if the outer panel 1 is heated and solidified during the painting process, as shown in Figure 7, the outer panel 1
However, since the film-like rust preventive agent 4 has a bulged portion 4b in cross section, a special mold is required, and production is slow. There are problems such as poor performance and a rise in costs.

Therefore, an object of the present invention is to provide a method for preventing rust of a hemmed joint, which can sufficiently prevent the rust of a hemmed joint, improve productivity, and be inexpensive.

(Means for Solving the Problems) A method for preventing rust of a hinge joint according to the present invention which achieves the object described in item 1 is to provide a method for preventing corrosion of a joint between a first panel and a second panel by interposing a film-like rust preventive agent. In order to prevent rust at the hemming joint where the edge of the panel is rolled and folded, a film-like rust preventive agent consisting of a rust preventive layer and an adhesive layer is applied along the edge of the first panel. After rolling and pasting, the second panel is overlapped so that the edge of the first panel protrudes, and then the edge of the first panel is rolled and folded back and hemmed and bent. The rust preventive agent is hardened by baking heat in the pretreatment and electrodeposition coating steps.

(Function) A film-like rust preventive agent with an adhesive layer provided along the edge of the first panel is rolled and pasted in advance, and the second panel is stacked on top of the first panel so that the edge of the first panel protrudes. The edge of the first panel is rolled back and hemmed, and the rust preventive agent is hardened by the heat added during the electrodeposition coating process, so a constant amount of film-like rust preventive agent is always applied to the hemming joint. Since the edges of the panels are sandwiched and the edge of the panel is wrapped and pasted in advance, the hemming joint and the edge of the panel are completely rust-proofed.Furthermore, since a film-like rust preventive agent is applied to the panel in advance, it is easy to prevent rust during the hemming process. There is no risk of it shifting.

(Embodiment) An embodiment of the rust prevention method for a hemmed joint according to the present invention will be described below with reference to the drawings in the case where an inner panel and an outer panel are hemmed together.

First, as shown in Fig. 1, along the edge 1a of the outer panel l, which is the first panel press-formed in the press process, a rust preventive layer 3a made of an epoxy resin material as shown in Fig. 2 is coated with acrylic. A film-like rust preventive agent 3 having an adhesive layer 3b coated with an adhesive made of a resin material is attached so that its edge 3c protrudes from the edge 1a of the outer panel 1.

Next, as shown in Figure 1, the edge 1a of the outer panel 1 is
The protruding portion 3d of the film-like rust preventive agent 3 that is more protruding is folded back, and the end edge 1a of the outer panel 1 is wound and pasted, thereby covering the end edge 1a with the film-like rust preventive agent 3.

Next, an inner panel 2, which is a second panel, is also press-formed on the outer panel 1 to which a film-like rust preventive agent 3 is attached.
As shown in FIG. 1C, the outer panel 1 is overlapped so that the edge 1a of the outer panel 1 protrudes.

Subsequently, the outer panel 1 and the inner panel 2, which are stacked on each other with the film-like rust preventive agent 3 in between, are joined by hemming as shown in FIG. 1d. At this time, since the film-like rust preventive agent 3 is adhered to the outer panel 1 by the adhesive layer 3b, the adhesion position does not shift, and
A film-like rust preventive agent 3 is placed inside the joint between the inner panel 2 and the inner panel 2.
The edge 1a of the outer panel 1 is completely filled with
is also covered.

Next, the joint portions of the outer panel 1 and the inner panel 2 are welded together by spot welding or the like, if necessary.

Thereafter, a pretreatment is performed, and the film-like rust preventive agent 3 is cured by baking heat added in the electrodeposition coating process, for example, at 170"C for 30 minutes or more, and the inner surface of the hemming joint and the edge 1a of the outer panel 1 become preventive. In this case, the part of the film-like rust preventive agent 3 intervening in the hemming joint and the part covering the edge 1a of the outer panel 1 are continuous as shown in FIG. There is no room for gaps to form, and sufficient rust prevention measures are taken.

The film-like rust preventive agent 3 used in the above-described rust preventive method may be in the form of a flat film, and can be obtained by simply cutting a large version of the film-like rust preventive agent. Compared to rust inhibitors, it does not require special molds, has high productivity, and can be obtained at low cost. In addition to the above-mentioned epoxy resin materials, the rust preventive layer 3a of the film-like rust preventive agent 3 may be made of resin such as urethane or vinyl chloride, but it may be used to improve the strength of joints or perform spot welding. Considering this, it is desirable to use epoxy resin. The material for the adhesive layer 3b may be a rubber-based, acrylic-based, or silicone-based resin, but in consideration of oil surface fixability and durability, the above-mentioned acrylic resin is preferable.

(Effects) According to the rust prevention method for hemming joints of the present invention as described above, the edge of the panel is wrapped and pasted in advance with a film rust preventive agent having an adhesive layer, and the film rust preventive agent is Since the hemming process is applied to the edge of the panel, there is no incomplete rust protection at the edge of the panel, and the rust preventive agent is completely filled in the hemmed area, ensuring a sufficient rust preventive effect, and the film-like rust preventive agent is flat. Therefore, there are effects such as high productivity and the ability to obtain products at low cost.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the method of the present invention, FIG. 2 is a cross-sectional explanatory diagram of a film-like rust preventive agent according to the present example,
3 to 7 are explanatory diagrams of conventional examples. 1... Outer panel (first panel), 1a... Edge, 2... Inner panel (second panel), 3...
Film-like rust preventive agent, 3a... anti-binder layer, 3b... adhesive layer.

Claims (2)

[Claims] (1) In a rust prevention method for a hemming joint in which a film-like rust preventive agent is interposed and a first panel edge is rolled and folded to join the first panel edge to the second panel edge, the first panel edge is A film-like rust preventive agent consisting of a rust preventive layer and an adhesive layer is rolled and pasted along the sides, and then the second panel is overlaid so that the edge of the first panel protrudes. 1. A rust prevention method for a hemmed joint, characterized in that the end edge of the panel No. 1 is rolled and folded back to perform a hemming bending process, and then the rust preventive agent is hardened by baking heat in a pretreatment and electrodeposition coating process. (2) The rust prevention method for a hemmed joint according to claim 1, wherein the rust preventive layer is made of an epoxy resin material, and the adhesive layer is made of an acrylic resin material.