JPS62146716A - Method for preventing rust on hemming joint part for vehicle - Google Patents

Abstract

PURPOSE:To completely fill a rust preventive and improve corrosion resistance by winding a film type rust preventive having a swelled-out part on its end part, around the end edge of a one side panel, embedding the edge part of an opposite side panel which is laminated over said one side panel into said swelled-out part, and carrying out a hemming bending machining. CONSTITUTION:A film type rust preventive 13 is wound around the end edge of an inner panel 1, and an outer panel 2 is laminated over the inner panel 1. Then, a hemming curving machining is carried out in such a way that the edge part 2a of the outer panel 2 is embedded into the swelled-out part 13a of the rust preventive 13. After that, the rust preventive 13 is cured by heating for baking in coating pretreatment and electrodeposition coating processes. Thereby, the rust preventive can be completely filled in a hemming joint part eliminating voids, preventing a pretreatment liquid from remaining and improving corrosion resistance.

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, hoods, and trunk lids.

[Prior art]

An example of a conventional structure of this type of hemming joint is shown in FIG. 3. This example is a joint of the edge of a door in an automobile, and in the figure, 1 is an inner panel, 2 is an outer panel, and these are joined by hemming. 3 is a sealer agent,
It is interposed at the hemming joint of the inner panel 1 and the outer panel 2 from the viewpoint of strength, rust prevention, etc. 4
is a painted seal, and the edge part 2 of the outer panel 2
It is applied to prevent rust from a.

Figures 4a-e show an example of the manufacturing process for parts such as doors having such a hemming joint structure.
As shown in FIG. 4a, after press-molding both the inner panel l and the outer panel 2 individually to a certain extent, as shown in FIG.
A sealing agent 3 is applied in a bead shape to the outer panel 2, and then the inner panel 1 is superposed on the outer panel 2 as shown in FIG. 4C, and hemming processing is performed as shown in FIG. 4D. (Refer to Japanese Utility Model Application Publication No. 52-6310) After that, pretreatment and electrodeposition coating are performed, and after applying a seal 4 to the edge portion 2a of the outer panel 2, intermediate and top coatings are applied to form a product.

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There are many problems with the joint structure (as listed below).

First, regarding sealer 3, this is applied to the panel mating surfaces to provide bonding strength and to fill in the panel mating surfaces where conventional pre-treatment and electrodeposition treatment are insufficient, thereby sealing the panel hemming joints. This is to improve corrosion resistance.

Therefore, in order to achieve this purpose, it is desirable that the hemming joint is completely filled with the sealant 3 as shown in FIG. 5.1) If the hemming joint is completely charged, If the applied amount is increased, the peeler 3 will protrude during the hemming process, and wiping it off will require a large number of man-hours.

However, by controlling the sealer application position and application amount,
Although it is possible to control the amount of protrusion to a certain extent, it is difficult to control the amount of protrusion around the entire hemming joint of doors etc. that have complex shapes.
It is impossible to completely manage it.

ii) Even if it took a lot of man-hours to wipe off the released sealer 3a as shown in Figure 6, the sealer 3 would still swell and protrude during the curing stage during electrodeposition baking, requiring even more man-hours to remove it. It takes.

For these two reasons, the amount of sealant 3 is currently reduced, which poses a problem in that the inside of the hemming joint cannot be completely filled.

Next, regarding the paint seal 4, as mentioned above, this is necessary to ensure corrosion resistance of the void that inevitably remains inside the hemming joint, and also to ensure the corrosion resistance of the gap that inevitably remains inside the hemming joint, as well as the edge portion 2a (7) of the outer panel 2.
) It is applied for the purpose of improving corrosion resistance, but
□ i) Since the entire circumference of the hemming joint of a door or the like having a complex shape is coated within a short takt time, there is a possibility that the coating may miss the mark.

ii) Even if the area is completely sealed, the amount of water permeation through the sealing material is very small, but it is not O, so the corrosion resistance of the voids inside the hemming joint will deteriorate over long periods of use. This becomes a problem.

iii) Regarding the voids inside the hemming joint, in addition to the problem of corrosion resistance during use, there is also the problem of pretreatment liquid resistance (
In other words, the pretreatment liquid remains in the voids, which blows out during electrodeposition baking and adversely affects the corrosion resistance of the general surface.)
From this point of view, it is necessary to seal the material before processing.

In addition, regarding the hemming joint of the door hinge salt, there are cases where the hinge becomes an obstacle and it is not possible to apply the paint seal 4. From this point of view, there is an extremely high need for sealing in the car body process, but it has already been done. If the line configuration is set as shown in FIG. 4, it is not easy to do so because it involves a large line change.

There were some problems.

The present invention has been developed in view of these conventional problems, and aims to completely fill the hemijig joints of panels with a rust preventive agent to eliminate voids and prevent the pretreatment liquid from remaining, thereby improving the corrosion resistance of the product. To provide a rust prevention method for a hemming joint for an automobile, which improves performance, eliminates the possibility of sealing off the edge of a panel, and enables easy sealing even in areas difficult to seal with paint.

[Means for solving the above problems] In order to achieve the above object, the present invention provides a method in which a film-like rust preventive agent having an irregular cross section with a bulge at the end is wound around the edge of one side panel. Next, a mating panel is superimposed on one panel to which this rust preventive has been pasted, and in this state, the edge of the mating panel is embedded in the bulge of the rust preventive and hemmed and bent. After processing, the rust preventive agent is hardened by baking heat in the pretreatment/electrodeposition coating process.・ [Effect] Since the film-like rust preventive agent has a bulge, the edge of the mating panel is embedded in the bulge during hemming process, and the rust prevention is further enhanced by baking heat during the electrodeposition coating process. When the rust preventive agent hardens, the -C part of the rust preventive agent protects and rust-proofs the hemming joint and the edge of the mating panel through the bulge. Since the general portion interposed between the two and the bulging portion in which the edge portion of the mating panel is embedded are integrally continuous, there is no room for a gap to occur.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1a, the present invention first involves winding and pasting a film-like rust preventive agent 13 made of epoxy resin as a basic material to the edge of an inner panel 1, which is a one-sided panel press-formed in a press process. Then, an outer panel 2, which is a mating panel, which is also press-molded, is superposed on the inner panel 1 to which the rust preventive agent 13 is applied.

As shown in detail in FIG. 2, the film-like rust preventive agent 13 has an irregular cross section with a rectangular bulge 13a at the end. The thickness of t
, Inner panel (one side panel) 1 which is the panel to be pasted
When the plate thickness of is 81, T>t+s.

The conditions are met.

In addition, in FIG. 1a, s2 is the thickness of the outer panel 2.

Next, as shown in FIG. 1, hemming and bending is performed so that the edge portion 2a of the outer panel 2 is embedded in the bulge portion 13a of the rust preventive agent 13.

Thereafter, as shown in FIG. 1C, the rust preventive agent 13 is hardened by baking heat in the pre-painting treatment/electrodeposition coating process.

Note that the total width of the film-like rust preventive agent 13 is set as follows.

L=6. +12 AH=a + b + '-2--(t +s,),
', t, S+ are 12 (length of bulge 13a)
-Optional However, a is the length of the lower joint between the inner panel 1 and the outer panel 2, and b is the length of the upper joint.

Next, the effect will be explained.

Since the bulging part 13a is provided at the end of the film-like rust preventive agent 13, the edge part 2a of the outer panel 2 is completely embedded in the bulging part 13a during the hemming process, and furthermore, it is prevented from being baked in the electrodeposition coating process. The rust preventive agent 13 is cured by heating, and the general part is damaged by the inner surface of the hemming joint and the bulge part 13a.
As a result, the edge portions 2a of the outer panel 2 are protected and rust-proofed. In this case, the rust preventive 13 is applied to the general part interposed within the hemming joint and the bulged part 13a embedded in the edge part 2a.
Since they are connected in one piece, there is no room for the formation of voids as in the conventional case, and the pretreatment liquid is prevented from remaining, and the above-mentioned protection and rust prevention of the hemming joint and panel edge portion 2a is completely performed. This improves the corrosion resistance of the product. Furthermore, since the seal is formed without manual intervention during the hemming process, there is no possibility that the seal will miss the panel edge portion 2a, and the seal can be formed using the bulging portion 13a of the film-like rust preventive agent 13. Therefore, it is now possible to easily seal areas that were previously difficult to seal, such as hemming joints behind door hinges.

〔effect〕

As described above, according to the present invention, it is possible to completely fill the hemming joint with the rust preventive agent, eliminate voids, prevent the pretreatment liquid from remaining, and improve the corrosion resistance performance of the product. In addition, it is possible to eliminate the possibility of incorrect sealing on panel edge portions, and to easily seal areas that are difficult to seal.

[Brief explanation of drawings]

FIGS. 1a to 1C are explanatory diagrams showing the steps of the method of the present invention, respectively;
FIG. 2 is a cross-sectional explanatory diagram of the film-like rust preventive agent according to the present invention,
Figure 3 is a sectional view showing the conventional hemming joint structure;
Figures a to e are explanatory cross-sectional views showing the steps of a conventional hemming joint rust prevention method, and Figs. 5 and 6 are explanatory cross-sectional views, respectively, to explain the problems of the conventional method. 1... Inner panel (one side panel), 2...
...Outer panel (opposite panel), 2a...
... Eno (2j)? (bn (C) (d) (e) n 3

Claims (1)

[Claims] A film-like rust preventive agent with an irregular cross section with a bulge at the end is wound and pasted on the edge of one side panel, and then the other side panel is superimposed on the one side panel to which this rust preventive agent is pasted, and in this state. Hemming and bending is performed so that the edge of the opposing panel is embedded in the bulge of the rust preventive agent, and then,
A rust-preventing method for hemming joints for automobiles, in which the rust preventive agent is hardened by baking heat in a pretreatment/electrodeposition coating process.