JPH0218266B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for externally joining vehicles and the like.

Conventionally, in order to ensure the strength of the joint B of the outer panel A of a vehicle, etc., in addition to spot welding C, structural adhesive D was applied to the joint B of the outer panel A, as shown in Figure 11A. A bonding method has been used in which the structural adhesive D is fully cured in an electrodeposition drying oven to disperse stress applied to the bonded portion B. However, in this bonding method in which the structural adhesive D is permanently cured in an electrodeposition drying oven, as shown in Figure 11B, the structural adhesive D flows out due to the degreasing and washing in the chemical conversion treatment step before the main curing. A recess E is formed on the end face of the structural adhesive D, and as shown in FIG. Air bubbles F are generated in the structural adhesive D. Therefore, after forming the electrodeposited coating G in the electrodeposition process and fully curing the structural adhesive D in a drying oven, sealer J is filled in the joint recesses H between the outer panels A. The adhesive D cannot be filled into the recess E, and an air layer K is formed as shown in 11th D, and as a result, the structural adhesive D
There was a drawback that the air bubbles F and the air layer K between the adhesive D and the sealer J expanded, and pinholes M were generated on the top coat L.

The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and it is necessary to improve the curing characteristics of structural adhesives (Fig. 2) and the strain limit of body outer panels (Fig. 1) in the car body process.
Based on this, the structural adhesive applied to the joint between the outer panels is pre-cured (semi-cured) by being heated by an infrared heater from above and below the joint, preventing the structural adhesive from leaking out due to the influence of the car body process. The purpose is to provide a method for joining outer panels that can improve the specified joint strength and the appearance quality of the joint by ensuring the original adhesive strength of this CURE adhesive in a drying oven without causing deterioration. be.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figure 1 shows the body outer plate (steel plate thickness:
0.6 to 1.0 mm) indicates the strain generation area, the vertical axis is temperature (°C), the horizontal axis is the hold time (min), and the upper part of the curved axis (τ) is the strain generation area. In addition, Figure 2 shows the epoxy one-component curing type (for example, the product name Sumitomo 3M,
JA-7433) This shows the curing characteristic curve of a structural adhesive.As a result of experiments, this structural adhesive has a semi-curing area curve C1 and a curing area curve depending on the temperature (℃) and keeping time (min) as shown in the figure. C2 is obtained, and the structural adhesive can be brought into a semi-cured state between curves C1 and C2.
The range that includes the point, that is, the temperature is approximately 120℃ and approximately
By keeping it for 12 minutes, distortion of the outer panel can be prevented and the structural adhesive can be left in a semi-cured state, and the outer panel can be processed through the following steps.

That is, a structural adhesive 4 is applied to the joint 3 of one of the unit panels 1 and 2 constituting the body outer panel as shown in FIG. 4. The amount of coating is approximately 2 to 3 mm in height t and approximately 5 to 8 mm in width h.
mm, and is applied along the longitudinal direction of the joint 3 at a distance W of approximately 10 to 12 mm from the edge of the joint (structural adhesive application step). Next, the other unit panel 1 is superimposed on the joint 3 of the unit panel 2, and the joint 3 is spot welded 5 at predetermined intervals along its longitudinal direction (FIG. 5, spot welding process).
Note that this spot welding process is performed in units of subassemblies that are optimal for assembling the body.

Next, unit panels 1 and 2 of each assembly
The structural adhesive 4 is semi-cured in a pre-curing (semi-curing) step. There are two types of semi-curing methods in this pre-curing process: a horizontal method and an inclined method. In the horizontal method, as shown in FIG. 6, the unit panels 1 and 2 are supported horizontally, and the structural adhesive 4 is semi-cured by heating with an infrared heater 6 from the upper and lower surfaces of the joint 3. In this case, as shown in FIGS. 1 and 2, the heating conditions using the infrared heater are as follows: the heating temperature is 120° C. and the holding time is 12 minutes, so that the structural adhesive 4 is semi-cured. In addition, in the tilt method, unit panels 1 and 2 are tilted at a tilt angle θ of 10 as shown in Figure 7.
Support it at ~15° and apply structural adhesive 4 to the joint 3 at a heating temperature of 120°C and a holding time of 12 minutes in the same way as in the horizontal method.
is semi-cured. When the semi-cured structural adhesive is applied horizontally, it slightly protrudes toward the joint recess 7 as shown in FIG. 8A, but the end surface 4a is finished extremely smoothly. In addition, when the slope method is used, the seam recess 7 is
It flows to create a smooth surface 4b. The unit panels 1 and 2 of each subassembly bonded by pre-curing the structural adhesive 4 in this manner are assembled in a body assembly process. The body assembled in the body assembly process is sent to the degreasing and chemical forming process, where the joints 3 are first cleaned and degreased with a caustic soda aqueous solution (53±2°C) at a shower pressure of 2 kg/cm ² . Next, the body is washed with room temperature water at a shower pressure of 2 kg/cm ² . Next, the body was immersed in a titanium/alkaline aqueous solution to condition the surface of the body, and after washing again with room temperature water at a shower pressure of 2 kg/ ^cm2 , the body was immersed in a zinc phosphate aqueous solution (53±2℃). It is immersed and chemically treated. After this chemical conversion treatment, the body is washed with water again and then sent to an electrodeposition and drying process. In this electrodeposition coating, the body is immersed in an electrodeposition coating solution, and electricity is applied for a certain period of time to deposit an electrodeposition coating film 8. After that, it is baked and dried in a drying oven. In this drying oven, the object to be coated is heated at a temperature of 170°C for a holding time of 20 minutes to dry the electrodeposited coating 8, and the structural adhesive 4 is cured at the point ◇ as shown in Fig. 2.
The end surfaces 4a and 4b of the adhesive 4 are finished very smoothly without outflow of the adhesive 4 or air bubbles in the adhesive 4. The body dried in this drying process is sent to a sealer application and painting process. In this sealing process, the joint recess 7 of the joint 3 is filled with the sealer 9. Therefore, in the conventional method of curing the structural adhesive 4 in a drying oven without pre-curing, the recess E is formed on the end surface. However, by pre-curing the structural adhesive 4 at the initial stage as in this example, it is possible to prevent the occurrence of the recess E, and also to ensure that the filling of the sealer 9 in the sealing process is not carried out in close contact with the end surfaces 4a and 4b of the adhesive 4. This can be done satisfactorily without creating an air layer. After filling this sealer 9, the top coating film 1 is applied in the top coating process.
0 is applied and then placed in a drying oven again at a temperature of 130°~
It is dried at 140℃ and kept for 25 to 30 minutes.
No air bubbles F were generated in the structural adhesive 4,
Further, a sealer 9 is applied to the end surfaces 4a and 4b of the adhesive 4.
Since the coating is sufficiently spread and filled and there is no air layer K, a beautiful finish can be achieved without the occurrence of pinholes M in the topcoat film 10 of the three joint parts. Adhesive strength can be imparted.

In the above embodiments, an epoxy-based structural adhesive was used as an example, but the above-mentioned semi-curing and full-curing can also be applied to bonding using a urethane-based structural adhesive. Further, in the above embodiments, the heating temperature and holding time during semi-curing can be appropriately determined from FIG. 2.

As described above, the present invention includes a structural adhesive application step of applying a predetermined amount of structural adhesive to the joint portions of unit panels to be joined to each other, and a process of overlapping the mutual unit panels at the joint portions and joining them together. a spot welding process of spot welding parts to form a subassembly unit panel, and heating the subassembly unit panel horizontally or at a predetermined inclination angle with an infrared heater from the upper and lower surfaces of the joint part. a precuring process for semi-curing the structural adhesive at the joint; a body assembly process for assembling the assembly unit panel into a body; and a degreasing/chemical conversion process for degreasing, surface conditioning, and chemical conversion treatment of the body;
An electrodeposition step in which the body is immersed in an electrodeposition paint solution and electricity is applied for a certain period of time to deposit an electrodeposition coating film on the body, and the body is heated to dry the electrodeposition coating film, and half of the joint portion is The process consists of a drying process in which the cured structural adhesive is fully cured, and a topcoating process in which sealer is filled into the joint recesses of the joint and a top coat is applied. By semi-curing the applied structural adhesive using an infrared heater, it is possible to create a smooth finish without creating any recesses on the edge of the structural adhesive. can be easily filled, and can prevent the formation of air layers caused by recesses that occur in the structural adhesive.
It is possible to improve the appearance quality of the outer panel joint by eliminating factors that degrade the quality of the outer panel joint, and it is also possible to ensure a predetermined adhesive strength at the outer panel joint.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the strain generation area of the body outer plate due to local heating, Fig. 2 is a curing characteristic curve of a structural adhesive, Fig. 3 is a process diagram of an embodiment of the method of the present invention, and Fig. 4 is An explanatory diagram explaining the application of structural adhesive, Fig. 5 is an explanatory diagram of the spot welding process, Fig. 6 is an explanatory diagram of the horizontal method of the precure process, Fig. 7 is an explanatory diagram of the inclined method, and Fig. 8 A and B are cross-sectional views showing the semi-cured state of the structural adhesive at the outer panel joints in the precure process, Figure 9 is a cross-sectional view of the outer panel joints in the electrodeposition and drying process, and Figure 10 is the topcoat painting process. FIGS. 11A, 11B, 11B, 11C, 11D, and 11C are sectional views of the outer panel joint in a conventional example. 1, 2... Panel, 3... Joint, 4... Structural adhesive, 5... Spot welding, 6... Infrared heater, 7... Seam recess, 8... Electrodeposition coating, 9...
...Sealer, 10...Top coat film.

Claims (1)

[Claims] 1. A structural adhesive application step in which a predetermined amount of structural adhesive is applied to the joints of unit panels to be joined to each other, and the mutual unit panels are overlapped at the joints and the joints are spot welded to form a sub. A spot welding process for forming the assembly unit panel, and structural bonding of the joint by holding the subassembly unit panel horizontally or at a predetermined inclination angle and heating the joint with an infrared heater from the upper and lower surfaces of the joint. a pre-cure process for semi-curing the agent; a body assembly process for assembling the assembly unit panel into the body; a degreasing/chemical conversion process for degreasing, surface conditioning, and chemical conversion treatment of the body; and immersing the body in an electrodeposition coating liquid. An electrodeposition process in which an electric current is applied for a certain period of time to deposit an electrodeposition coating film on the body, and a drying process in which the body is heated to dry the electrodeposition coating film and the semi-cured structural adhesive at the joint part is fully cured. A method for joining exterior panels of vehicles, etc., which comprises a step of filling a sealer into a joint concave portion of the joint and a topcoating step of applying a topcoat.