JPH0289580A - Manufacture of car body panel - Google Patents

Abstract

PURPOSE:To simplify the manufacture of a panel by sticking a masking tape which can be brought to thermal shrinkage to a thermal welding scheduled part of a car body panel, and thereafter, painting the panel and drying it, shrinking a masking seal, aligning the other material therewith and welding it to an exposed part of the car body panel. CONSTITUTION:In a press process, a flange part 2 is formed in the end part of three sides of an outer panel 1. Subsequently, a masking seal 4 of a vinyl chloride compound, etc., is stuck to a welding scheduled part 3. The outer panel 1 is brought to electrodeposition, dried in a high temperature atmosphere, brought to baking processing, and a thermal shrinkage processing is executed to the masking seal 4. The panel 1 is combined with an inner panel 5 and the welding scheduled part 3 exposed from the seal 4 due to thermal shrinkage and a welding scheduled part of the panel 5 are welded to each other by a high current from an electrode, and an assembly of a door panel is ended. In such a way, an unpainted panel ground can be exposed easily from the masking seal and the manufacture can be simplified.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a vehicle body panel in which a vehicle body panel and a mating material are welded together. The present invention relates to an improvement in a method of manufacturing a vehicle body panel, in which the vehicle body panel is painted and then the vehicle body panel and a mating material are welded.

(Prior art) On the production line for body panels for automobiles, etc., there are pressing operations in which steel plates are pressed into a predetermined panel shape, painting operations in which the pressed panels are electrocoated, and the painted panels are attached to mating materials. A process is known in which welding operations for joining using welding are performed in this order.

Particularly in the production line of automobile panels, it is necessary to form a coating film with a thickness of 10 μm or more on the panel in order to improve the rust prevention performance of the automobile panel. However, in general, if a coating film with a thickness of 3 μm or more is formed on the part of the panel to be welded, it becomes difficult to properly weld the part of the panel to be welded to the mating material during welding work, so the welding schedule of the panel will be delayed. It is necessary to eliminate painting on the parts.

Conventionally, as a technique for eliminating the electrodeposition coating on the area to be welded, a method is to apply wax to the area to be welded before applying the electrodeposition coating, and to remove this wax using a prescribed solvent after the electrodeposition coating. is known (Japanese Unexamined Patent Publication No. 58-367
No. 78).

(Problems to be Solved by the Invention) However, depending on the above-mentioned conventional technology, there is a problem in that each process of wax application and removal is troublesome, resulting in complicated processes and high manufacturing costs. In particular, the process of removing wax from vehicle panels requires the use of certain organic solvents (
Care must be taken to dissolve all of the wax using, for example, thinner, and wiping after this dissolution also requires time.

The vehicle body panel of the present invention was made to solve the above problems, and when welding the panel to a mating material after painting, it facilitates welding and simplifies the manufacturing process. Another object of the present invention is to provide a method for manufacturing a vehicle body panel that can reduce manufacturing costs.

(Means for Solving the Problems) In the method of manufacturing a car body panel of the present invention, before painting the car body panel, a heat-shrinkable masking seal is attached to the welding area of the car body panel. When the coating film is dried or after drying, the masking seal is heat-shrinked to expose a part of the area to be welded that was covered by the masking seal. This method is characterized in that the exposed welding portion and the welding portion of the panel mating material are joined by welding.

(Function) According to the above configuration, the masking sticker is applied to the area to be welded before painting the vehicle body panel, and the area to be welded is completely masked before painting, thereby improving rust prevention performance. Even in cases where the thickness of the coating film is increased in order to prevent the welding from occurring, it is possible to avoid forming the coating film on the portion of the vehicle body panel to be welded, making it possible to weld the vehicle body panel and the mating material.

In addition, this masking seal is made of a heat-shrinkable material, and when the paint is dried after painting the car body panel, or after the paint has dried, the masking seal is shrunk by heat. This makes it possible to expose the unpainted panel material from the seal by simply applying wax to the area to be welded, which eliminates the need to melt the wax or
Since troublesome work such as wiping is not required, it is possible to simplify the manufacturing process and reduce manufacturing costs.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of each process when the present invention is applied to a door panel. That is, in the method of this embodiment, the flange portions 2 are first formed at the ends (three sides) of the outer panel 1 in a pressing process (see FIG. 1(a)).
). Next, in the seal pasting process, masking stickers 4 made of vinyl chloride or polyester material (for example, SUMITUBE S (trade name)) are pasted onto the plurality of welding areas 3 of the flange portion 2 (see Fig. 1). (b)). Next, the outer panel 1 is transported to an electrodeposition coating process, and a rust-preventing coating film with a thickness of about 10 μm is formed on the entire surface of the outer panel 1 (FIG. 1(C)). Next, the outer panel 1 is placed in a high-temperature atmosphere in a drying process, whereby the coating film is dried and baked, and at the same time, the masking seal 4 attached to the welding area 3 is heat-shrinked (step Figure 1 (d)). After this, the outer panel 1 is combined with the inner panel 5 in a welding process, and the welding area 3 exposed from the seal 4 due to heat shrinkage and the welding area 3 of the inner panel 5 are welded together by high current from the electrode, and the door panel is assembled. Assembly is completed (FIG. 1(e)).

In the above-mentioned seal pasting process, the masking seal 4 is folded in two as shown in FIG. 2, and then placed over the upper edge of the welding portion 3 of the flange portion 2.

Adhesive is applied to a part 4a inside the edge of the seal 4 and a part 4b inside the folding edge, which are indicated by diagonal lines in FIG. . Applying adhesive only to part of sticker 4 is
This is because the parts to which the adhesive is not applied tend to shrink easily. Further, the shrinkage rate of the masking seal 4 is preferably 50% or more, that is, it is desirable that the masking seal 4 can shrink to 1/4 or less in area. If the shrinkage rate is 50% or more, the second
The masking seal 4 shown in the figure will contract to the area surrounded by the dotted line in FIG. By using the seal 4 having such a large shrinkage rate, it becomes possible to expose from the seal 4 an unpainted panel base of a size necessary for welding. The width of the masking seal 4 is, for example, about 20mm, and the length is a value corresponding to the height of the flange portion 2.

In the drying process, the outer panel 1 is carried into an MR drying oven and left in an atmosphere at, for example, 180° C. for about 20 minutes. As a result, the coating film applied to the surface of the outer panel 1 is dried and baked, and at the same time, the masking seal 4 is sufficiently shrunk.

In this way, according to this embodiment, it is possible to shrink the seal 4 using the heat for drying the panel coating film in the drying process without providing a separate process for heat shrinking the seal 4. This makes it possible to simplify the manufacturing process.

In the above welding process, as shown in FIG. 3, the main body 1a of the outer panel 1 and the flange portion 2 bent inward
The end of the inner panel 5 is inserted and caulked between the main body 1a, the flange portion 2 and the inner panel 5.
Spot welding is performed by sandwiching the overlapped ends of the two electrodes 6 from both sides with two electrodes 6. Further, the shrunken seal 4 may be collected in a drying oven during the drying process, or may be left in the area to be welded.
It is also possible to perform caulking and welding in this state. Incidentally, as shown in FIG. 1(e), a plurality of welding areas as described above are provided on three sides of the outer panel 1, and the above-mentioned process is performed for each of them.

In addition, when the inner panel 5 is also subjected to electrodeposition coating, welding can be carried out smoothly by applying the same treatment as the outer panel 1 to the welding area.

Note that the method of the present invention is applicable not only to the production of the above-mentioned door panels but also to various other panels.

In the above example, the masking seal is heat-shrinked using the heat for drying the paint film in the drying process, but the heat-shrinking of the masking seal does not necessarily have to be done in the drying process. It is also possible to provide another step before or after the step.

Next, an example investigated by the present inventor will be described which is different from the embodiment of the present invention but can achieve the same purpose as the present invention.

First, a first study example will be explained using FIG. 4. t
jji m Before painting, holes are drilled in the parts of the main body 11a of the outer panel 11, the flange part 12, and the inner panel 15 to be welded. The holes are formed in such a way that a part of the hole edge of one of the adjacent panels comes into contact with the painted surface of the other panel. When the outwardly projecting hole edge portion is pressurized by the electrode 16, the coating film adhering to that edge portion is removed. In addition, when the hole edge portion that is in contact with the painted surface of the adjacent panel is pressed by the electrode 1B and stretched flat, it damages the painted surface of the adjacent panel and causes the paint film to peel off. As a result, when the area to be welded is pressurized by the Hyakura 1!16 and the hole edge portion becomes a flat plate state, the two electrodes are brought into a substantially conductive state and welding becomes possible. Further, by making holes in each panel as described above, positioning between the panels can be ensured.

Next, a second study example will be explained using FIG. 5. When performing electrodeposition coating, the main body 21a of the outer panel 21
As shown in FIG. 5, a sheet 27 made of a conductor 7 mixed with a magnetic material and a magnetic material is pasted on each of the flange portion 22 and the inner panel 25 to be welded. The portion is held between both electrodes 2B and pressurized.

In response to this pressure, the sheet 27 damages the coating film at the welding area of each panel and causes it to peel off. As a result, the picture electrodes 26 become electrically conductive and welding becomes possible. Further, by mixing the sheet 27 with a magnetic material, it becomes easy to hold the sheet 27 on the panel.

Note that these study examples are applicable not only to the process of welding an outer panel and an inner panel, but also to various other processes in which welding processing is required for painted members.

(Effects of the Invention) As explained above, according to the method of manufacturing a car body panel of the present invention, since the panel is painted after pasting the masking seal to the area to be welded, a coating film is formed at the area to be welded. In addition, since the masking seal is heat-shrinkable, the unpainted panel material can be easily exposed from the masking sheet, simplifying manufacturing and reducing manufacturing costs. It is possible to achieve this.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining each process of a method for manufacturing a vehicle body panel according to an embodiment of the present invention, FIG. 2 is a perspective view showing an enlarged masking seal shown in FIG. 1, and FIG. FIG. 4 is a partial sectional view of a panel for explaining a welding process, and FIGS. 4 and 5 are schematic views for explaining a study example that can achieve the same object as the present invention. 1, 11.21... Outer panel 2, 12.22... Flange portion 3... Welding planned area 4... Masking seal 5, 15.25... Inner panel 6. 18.26
...Electrode Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 (e)

Claims (1)

[Claims] After pasting a heat-shrinkable masking seal on the welding area of the car body panel, the car body panel is painted, the painted car body panel is dried, and during or after this drying, the masking seal is shrunk. and then aligning a mating material with the vehicle body panel, and welding the portion of the welding portion where the vehicle body panel is exposed due to contraction of the masking seal to the welding portion of the mating material. manufacturing method.