JPS6049875A - Production of plateworked assembly - Google Patents

Abstract

PURPOSE:To obtain a plateworked assembly having satisfactory resistance to corrosion by using inexpensive ordinary steel plates by providing a projecting part to at least one of joint surfaces of the plate-worked members to be joined to each other and subjecting the members to spot welding at this projecting part then subjecting the members to dip painting. CONSTITUTION:Joint surfaces 20 of flanges 12b and 14b are in flat contact with each other except a projecting part 18 prior to spot welding. The part 18 is grasped and pressed by electrodes 22 and 24 of a welding machine and when electricity is conducted to said electrodes, a nugget 26 is formed and both flanges 12b, 14b are welded and bonded to each other. Gaps 28 are formed to the joint surfaces of the flanges between the respective nuggets 26 owing to deformation of the projecting parts 18 in this stage. The side sill produced in such a way is subjected to an ordinary pretreatment and is then dipped in an electrodeposition tank and is subjected to electrodeposition painting by the conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing sheet metal assemblies, such as automobiles and various home appliances, which are assembled mainly using thin steel sheets and which are coated with dip coating such as electrodeposition coating for rust prevention. be.

As is known in the art, the automobile? Sheet metal assemblies, such as sheet metal parts, are made by molding thin steel plates into the desired shape and fixing them together using spot welding, then subjecting them to the necessary pretreatment and immersing them in an electrodeposition coating bath. Then, a rust-preventive undercoat is applied. However, in the above-mentioned spot welded parts, the joint surfaces of multiple sheet metal parts are substantially in close contact with each other, so the paint coverage is not sufficient during electrodeposition coating, and the coating film required for rust prevention is not formed sufficiently. - For this reason, rust is likely to occur along the joint surface of the spot weld, which reduces product value and impairs durability. In order to solve this problem, it is necessary to use a steel plate that has been subjected to a surface treatment for rust prevention, such as a galvanized steel plate, but this is not preferable because it causes a significant increase in cost.

The present invention has been devised in view of the above, and includes providing a protrusion projecting to the opposite side of the joint surface on at least one joint surface of the sheet metal members to be joined to each other, and ? The gist of this invention is a method of manufacturing a sheet metal assembly, which is characterized by performing dipping coating after repeated welding. According to the present invention, at least one joint surface of the sheet metal members to be joined to each other is provided with a protrusion that protrudes toward the opposite side of the joint surface, that is, the side away from the mating surface, by pressing or the like, and Spot welding is performed in Step 1, followed by dip painting. As a result, an appropriate gap is formed between the contact surfaces of the opposing sheet metal members, excluding the spot welds,
During electrodeposition coating, the paint sufficiently penetrates into the gaps and forms the necessary anti-rust coating, making it possible to manufacture sheet metal assemblies with excellent durability using inexpensive ordinary steel sheets. There are advantages.

Embodiments of the method of the present invention will be described in detail below with reference to the accompanying drawings. First, in FIG. 1, reference numeral 10 generally indicates an automobile side sill manufactured by the method of the present invention. The side sill 10 connects the inner panel 12 and the outer panel 14 with flanges 12a and 14a1 provided above and below, respectively.
12b and 14b are integrally joined by spot welding 16. In this embodiment, the portion of the lower flange 14b of the outer panel 14 to be spot welded has a circular shape protruding in the direction away from the mating flange 12b, as shown by the chain line in FIG. Projections 18 are arranged in a row, and the projections 18 are used for assembling the inner panel 12 and the outer panel 14.
Spot welding is performed in the area. In Figure 2,
Before spot welding, the joint surfaces 20 of the flanges 12b and 14b are in planar contact except for the protrusion 18, but when the protrusion 18 is held between the electrodes 22 and 24 of the welding machine and pressurized and energized, , and both flanges 12 are formed with 8 holes 26.
b, 14. b are welded together, and at this time, due to the deformation of the protrusion 18, a gap 28 is formed at the flange joint surface between each navigator hole 1-26.

In the embodiment of FIG. 2, the inner and outer panels 12
．． 14 is a steel plate with a thickness of 0.8 (5 pcc), and a protrusion 18
The protrusion height is 2.5, the diameter of the protrusion 18 is] Omm
, the diameter of the tip of the welding electrode tip 22 is 1 f of 4 mm,
The gap size was about 0.3 mm at 8a, and about 0.6 mm at the middle part 28b between the 7 holes.

After subjecting the Zyde/L 10 manufactured in this way to normal pretreatment, it was immersed in an electrodeposition bath and subjected to stain painting using a conventional method. After entering the coating, a sufficient coating film was formed in all the gaps except for the 8th chip and the 26th part. After completion of an automobile having such a side sill 10, rainwater or the like may enter the gap 28 while driving.
Also, due to dew condensation, dew forms inside the side sill 10 and the gap 2
8, there is a sufficient coating film formed on the inner surface of the gap 28, so rust will not develop rapidly, and the side sill 10, which is important as a strength member.
can improve durability.

In addition, in FIG. 1, the hole 3 drilled in the inner panel 12
Reference numeral 0 designates an air vent hole for venting air from the side sill 10 during electrodeposition coating and making it easier for paint to enter.

Next, FIGS. 3 to 25 illustrate various shapes of the protrusion 18 that are advantageous when employed in carrying out the present invention.

First, Fig. 3 shows a case where the protrusion is trapezoidal embossed 18a, the plate thickness is 0.6 to 0.8 mm, and the diameter of the tip of the spot welding machine is 4 to 5 fins. , emboss],
It is appropriate that the height Ha of 8a is 3 to 10 m1, and the width Wa of the top surface is about 10 m at maximum. Next, in Fig. 4, the protrusion is a circular protrusion 18b as in Fig. 2, and the plate thickness and electrode chip are under the same conditions as those in Fig. ~10 carp, the diameter Db is about 20 at maximum. In addition, in Fig. 5, the protrusion is formed as an elliptical protrusion], 8c, and when the plate thickness and electrode tip diameter are the same as above, the height Hc is 2 to 10 cm, the short axis Dc and the long axis Dc'
It is appropriate to select a maximum of about 15 and 30, respectively.

However, as is clear from FIG. 2, the gap 28 is generated between the joint surfaces by implementing the method of the present invention because the protrusion 8 is deformed during welding and excess material is removed.
This is due to the deformation that occurs when the periphery of the material 6 is pushed out. Therefore, depending on the throwing power of the paint used, the material plate is Thickness, diameter of hollow 8t 26, spot welding 1
It is desirable to appropriately determine the shape and size of the protrusion 18 according to the pitch of the protrusions 6 and the like.

Furthermore, the application of the method of the present invention is not limited to the side sills of automobiles as exemplified in Section 2, but can also be applied to various sheet metal assemblies of automobiles that require corrosion resistance, home appliances such as washing machine housings, etc. It can be widely applied. Furthermore, when carrying out the present invention, spot welding can be carried out by providing protrusions similar to those described above alternately at each welding point, for example, on both sheet metal members to be joined by spot welding. Forming protrusions on each sheet metal member and making it F! 7-t welding may be performed.

As shown above, in the present invention, at least one joint surface of sheet metal members to be joined to each other is provided with a protrusion that protrudes to the opposite side of the joint surface, and after spot welding is performed at the protrusion. This method is characterized by dip coating, and is very advantageous because it is possible to obtain a sheet metal assembly having sufficient corrosion resistance using ordinary steel sheets at low cost.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of an automobile side sill manufactured by the method of the present invention, FIG. 2 is a partial cross-sectional view taken along the line ■-■ in FIG. 1, and FIGS. 3 to 5 are views according to the present invention FIG. 4 is a cross-sectional view showing various shapes of protrusions suitable for use in carrying out the method. 12... Inner and flannel 22, 24... Welding electrode 14... Outer flannel 28... Gap 6...
,I ヮto welding part

Claims (1)

[Claims] A sheet metal member characterized in that at least one joint surface of sheet metal members to be joined to each other is provided with a protrusion projecting to the opposite side of the joint surface, spot welding is performed on the protrusion, and then dip painting is performed. How to manufacture an assembly.