JPH0140869B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lower arm formed by applying a sealant containing asphalt pitch and atactic polypropylene (APP) as main ingredients to areas where rust is likely to occur. Generally, the undercarriage of a car is as shown in Figure 1.
A wheel 2 connected to the axle housing 1 to be rotated is supported by a knuckle 3, and the upper end of the knuckle 3 is connected to the lower end of a strap-type shock absorber 4. , is connected to the tip of a lower arm 6 fixed to a boss portion 5 on the vehicle body side via a bush 6a, via a ball joint 7 and a ball housing 8 that holds the ball joint 7. Conventionally, the ball housing 8 or bushing 6a is integrated with the lower arm 6 by electric welding, masked and painted in a prescribed manner, and the welded area is filled with a vinyl chloride sealer using a press-fitting machine. This prevents rust from forming on the welded parts. Such vinyl chloride sealers are heat-curable and have the advantage of having little change in hardness depending on the ambient temperature once hardened, but the main component of this sealer is generally powdered PVC called plastisol.
and plasticizer (mainly DOC), it has poor adhesion, and also has poor wettability, storage stability, and weather resistance, so it is constantly exposed to wheel vibration during driving, such as the welded part of the ball housing. In some places, PVC sealant easily peels off, and especially when driving in cold regions or along the coast where salt is sprinkled on the road to prevent freezing, salt damage may cause damage.
There is a problem in that rust occurs at the location where the sealer is peeled off, resulting in corrosion of the lower arm. The present inventor has devised the present invention in order to effectively solve the problems in the prior art, and the purpose is to provide a sealant with excellent adhesiveness, thermal stability, and weather resistance to a ball. To provide a lower arm formed by coating the welded part with the housing or the welded part with the bush. To achieve this purpose, the sealant according to the present invention contains 30 to 50% by weight of asphalt, 20 to 35% by weight of APP, and 15 to 40% by weight of C-9 distillate tackifier.
The gist is that normal butene, crosslinked polypropylene (EPT), an antioxidant, etc. are added to a mixture consisting of The gist is that at least the welded portion of the ball housing to the lower arm is covered. An example of the implementation of the present invention will be explained in detail below based on the accompanying drawings. FIG. 2 shows a joint structure in which the sealant according to the present invention is applied to the surface of the welded portion between the lower arm and the ball housing. That is, as shown in FIG. 3, a mounting hole 9 is formed at the tip of the lower arm 6, which has bushes 6a, 6a formed at the middle and rear ends, and the upper end is inserted into the mounting hole 9 inwardly. A small diameter hole is formed by the bulging portion 8a,
A cylindrical ball housing 8 is inserted into which the lower part 8c, which is continuous with the intermediate part and the stepped part 8b, is a thin, large-diameter hole, and the ball housing 8 extends over the entire circumference of the upper and lower ends of the mounting hole 9. 8 and the mounting hole 9 are welded together by electric welding. A layer of thermoplastic sealant 11 is formed on the surface of welded metal 10 formed by welding around the entire circumference of the upper and lower ends of the mounting hole 9. As the components of this sealant 11, the following may be considered, for example. (Sealing agent A) Asphalt pitch...40-50% by weight Atactic polypropylene (APP)
...25-35% by weight Normal butene ...5-10% by weight C-9 fraction tackifier ...15-20% by weight Antioxidant ...200ppm (Sealing agent B) Asphalt pitch ...30-40% by weight Tsuku Polypropylene (APP)
…20-30% by weight cross-linked polypropylene (EPT)
...5 to 15% by weight C-9 fraction tackifier ...30 to 40% by weight The properties of these sealants are as shown in the table below.

[Table] The reason why the sealant according to the present invention is made of the components as shown in the above examples is as follows. First of all, the reason why asphalt pitch was used as one of the ingredients was to improve water resistance and to serve as an extender for the tackifier, which will be described later. ℃), has good thermal stability and does not burn, and the reason why tackifier is added is to improve tackiness or adhesion.Also, normal butene and selectively added
The purpose of EPT is to impart elasticity, and the antioxidant is to prevent oxidation due to continuous heating. Next, the procedure for fitting the ball joint 7 into the ball housing 8 will be specifically described. First, the ball housing 8 is inserted into the mounting hole 9 of the lower arm 6 and integrated by electric welding. Next, after masking the inside of the ball housing 8,
A 30μ melanin-based baking paint is applied to the entire body. Thereafter, the welding area is filled with the molten sealant 11 described above. After that, insert the ball joint 7 into the ball housing 8 from below with the connecting pin 7a above and the ball part 7b below, and then insert the ball joint 7 into the ball housing 8 from below.
The ball seat 12 is press-fitted around the ball part 7b inserted inside, and the bottom plate 13 is further pushed in until it hits the stepped part 8b of the ball housing 8, and the thin lower part 8c of the ball housing 8 is crimped inward to close the ball joint. The int 7 is held by a ball housing 8. And pin 7 of ball joint 7 in such a state
A cap-shaped rubber seal 14 is placed over the ball housing 8, and the lower end of the seal 14 is fitted into a groove 15 formed on the outer periphery of the upper end of the ball housing 8, and the ball housing 8 is tightened and held by a circlip 16. The above is only an example of the implementation of the present invention, and the sealing agent is not limited to the welded part between the ball housing and the lower arm, but may also be filled in the welded part between the lower arm and the bushing 6a, or the entire lower arm may be melted. Alternatively, the entire lower arm may be coated with the sealing agent by dipping it into the existing sealant. As is clear from the above description, according to the present invention,
The sealant is asphalt pitch 30-50% by weight, APP 20-35% by weight, and tackifier 15%.
Normal butene in a mixture consisting of ~40% by weight,
Since it is obtained by adding EPT or antioxidants, it is less than 300cps at 200℃ and B
&R can also be a sealant that has a temperature of 100℃ or higher, so even if it is filled into the welded parts of the lower arm, the temperature near the lower arm when the vehicle is actually running is around 60℃, so the sealant is It does not melt and fall, and since it has an appropriate viscosity, peeling due to vibrations and scattering of pebbles, etc., is reduced. Furthermore, since a simple method such as pouring the sealant while applying it is sufficient, it has many advantages such as being able to easily form a coating film of the sealant of about 200 to 500 μm.

[Brief explanation of drawings]

The drawings show an example of the implementation of the present invention,
Fig. 1 is a partial sectional view showing the suspension of an automobile, Fig. 2 is a perspective view of the lower arm, Fig. 3 is a sectional view showing the joint state of the lower arm and the ball housing, and Fig. 4 is the ball housing and the ball housing. It is a partial sectional view showing a state in which the joint is fitted. In addition, in the drawing, 6 is a lower arm, 6a is a bushing, 8 is a ball housing, 10 is a welded part, and 11
is a sealant.

Claims (1)

[Claims] 1. Apply asphalt 30 to 50 on the lower arm that supports the vehicle body, at least in areas where rust is likely to occur, such as the weld between the lower arm and the ball housing or the weld between the lower arm and the bushing.
A sealant comprising 20-35% by weight of atactic polypropylene and 15-40% by weight of C-9 distillate tackifier, further adding at least one of normal butene, crosslinked polypropylene and an antioxidant. A lower arm characterized by forming a film of.