JPS5855374B2 - Method for forming colored coating of coil spring for vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a colored coating for identifying the load characteristics of a coil spring used in an automobile suspension system.

In the coil springs used in automobile suspension systems,
Adjacent spring wires collide with each other due to vibrations, shocks, etc. that occur during running, producing a so-called knocking sound.

In particular, in non-linear custom-made springs such as tapered coil springs and unequal pitch coil springs, the spring wires are configured so that they collide with each other in a portion of the longitudinal direction, resulting in knocking noise. is remarkable.

In order to prevent the occurrence of such knocking noise, a tube with a spring wire inserted is used, but water or electrolytic solution (such as road antifreeze) that enters the tube can be used. In some cases, breakage of the spring wire may occur due to corrosion fatigue, and even if adhesives or sealants are used to prevent moisture from entering, they may not be sufficiently effective under conditions of repeated stress. I can't wait.

Also, it requires a lot of man-hours both manually and mechanically to insert the spring wire into the tube.
Improving productivity is extremely difficult.

Furthermore, in the case of using a tube provided with slits, productivity is slightly improved, but there is a disadvantage that the adverse effects of moisture are more significant than in the former case.

Furthermore, methods such as immersion in a highly concentrated resin solution or coating with powder may be considered, but it is necessary to repeat the treatment at least several times in order to obtain a thickness that is effective in preventing the occurrence of tapping noise. Masking is required in the case of partial painting, and if there is a risk of air pollution.

On the other hand, in order to obtain a good ride comfort, the coil springs mentioned above must have uniform characteristics for each vehicle, but the springs after molding have relatively large variations in their load characteristics, so in practice In order to eliminate variations, it is necessary to conduct a load characteristic test for each product after molding, and to classify each spring according to its characteristics based on the results of the load test.

Conventionally, the tube was inserted after the coil springs were manually colored based on the results of a load test, which required man-hours for the coloring work in addition to the man-hours for inserting the tube.

The present invention has been made under the above circumstances, and its purpose is to facilitate the formation and coloring of the covering portion on the spring wire, to increase productivity, and to ensure that the covering portion is strong with the spring wire. It adheres closely to the coil spring and does not easily come off, effectively preventing knocking noise and corrosion of the spring wire, and does not adversely affect the characteristics of the coil spring body, and is easy to clean due to the coating process and load characteristics. It is an object of the present invention to provide a method for forming a colored coating part of a coil spring, which allows the coloring process for identification to be performed in one process, thereby simplifying the process and saving labor.

Hereinafter, the present invention will be explained with reference to the drawings.

The drawings schematically illustrate the process of forming a colored coating in the present invention.

In the figure, 1 is a hot-coiled coil spring body similar to a normal vehicle suspension coil spring, and 2 is a spring wire that makes up this body. A colored coating portion 3 is provided.

The colored covering portion 3 has a melting point of 250° so as to cover the entire spring wire including at least a part of the spring wire 2 that faces adjacent spring wires or these mutually opposing surfaces.
It is formed by injecting a mixture of a thermoplastic resin powder of C or less and a coloring agent together with flame from a spray gun 4, and spraying a desired amount of the mixture onto a desired position of the spring wire to fuse it.

A plurality of spray guns 4 (in the case of three in the figure) are provided facing the desired positions, and each spray gun is configured to spray a mixture containing a coloring agent of a different color.

Then, the above-mentioned coloring agent is subjected to a predetermined load test for each spring body 1 after coiling is completed, and is classified according to the actual load characteristics, and the colors are set so that the predetermined color classification is done according to this classification. There is.

For example, load test results are categorized by color, such as red for high ranking results, white for middle ranking results, and yellow for low ranking results.

Note that, before the above-mentioned colored coating part forming step, there is provided a splash body forming step such as coiling→heat treatment→shot peening→painting, etc., almost in the same way as in the conventional method.

In addition, it is desirable to preheat the spring wire 2 to a surface temperature of about 100 to 250° C. before forming the coating portion 3. For example, when the wire is heated and dried in a drying oven after painting, etc. For example, this drying step may be used as a preheating step, and in such cases, it is preferable to arrange a test and injection stage at an appropriate position on the exit side of the drying oven.

In addition, each spray gun 4 is preferably one that can inject both resin powder and flame at the same time, and the temperature of the spring wire is always below 250°C. It is better to make it happen.

Modified ethylene vinyl acetate copolymer was used as the powder material, and
Table 1 shows the test results of an example in which thermal spraying was carried out from a distance of 50 to 1000 plates at a spraying angle of ~900° (the device was manufactured by Schr.I.) and a comparative example in which a spring wire was inserted into the tube. Compare and show.

As can be seen from the table, the above Examples have soundproofing effects equivalent to those of the Comparative Examples, and are excellent in durability and antirust effects, and in particular, productivity is significantly improved.

In addition, no change in the repulsion constant was observed depending on the presence or absence of the coating in both cases.

In addition, the soundproofing effect in the table is that when a rectangular wave with an amplitude of O ~ ±25 m7'/L and a frequency of 1 kHz is input, the sound pressure level was 80 to 85 dB when there was no coating, but when it was coated. It became 0.

Durability is indicated by the number of times the normal contraction load is repeated. The rust prevention effect is based on a salt spray test, and in the comparative example it is 72 to 120.
Although rust occurred over time, in the example, no rust occurred after 240 hours or more.

Productivity is indicated by the time required to form the covering part on one main body.

G and E are the tensile strength and elongation of the coating.

Table 2 shows the measurement results of residual compressive stress before and after thermal spraying in the above examples.

As shown in the same table, the influence of thermal spraying on residual compressive stress is virtually negligible.

Note that the residual compressive stress was measured (by the 4X-ray method).

In the second embodiment, in which modified nylon was used instead of the modified ethylene vinyl acetate copolymer in the above embodiment, the thickness of the covering portion 3 was 7 m0, which was 1 m0 in the first embodiment.
The same soundproofing effect was obtained.

In addition, in the third embodiment using polyolefin powder, the same soundproofing effect as in the first embodiment can be obtained with a thickness of 4 mm in the case of polyethylene and a thickness of one plate in the case of ionomer resin. was completed.

In any of the above cases, since the resin powder is mixed with a color former and sprayed, the formation of the coating and the coloring of the splash body can be done at the same time, reducing the number of man-hours. I was able to make a big contribution.

Note that the present invention is not limited to the above-mentioned embodiments. For example, the coil spring main body 1 may be unequal in all or part of the coil inner diameter, coil outer diameter, coil pitch, strand diameter, etc. In addition, the presence or absence of the end turn portion, the cross-sectional shape of the strands, etc. can be arbitrarily set.

The covering portion 3 may be fused to the main body 1 at one end 2 and both ends in the axial direction, at the middle portion, or over the entire length, and in any of these, the fusion bonding may be continuous or spaced in the longitudinal direction of the spring wire. It may be either.

Further, the covering portion 3 may be provided on the other side or both sides of the spring wire 2 in the coil axis direction.

If necessary, they may be provided continuously in the circumferential direction of the spring wire 2. In this case, the inner and outer portions of the main body 1 may be formed thinner than the opposing portions of the adjacent spring wires. You may also do so.

Incidentally, in the case where the above-mentioned covering portion 3 is attached only to the portions of the mutually opposing surfaces of the spring wires that are likely to come into contact with each other.

The other parts are painted in the same way as regular coil blades.

However, since this area is a surface where the spring wires do not come into contact with each other, there is no possibility of peeling due to contact even with normal coating, and this is an effective way to prevent rusting.

The material forming the covering part 3 may be any thermoplastic resin powder with a melting point of 250°C or less,
In addition, the color type and amount of the color former to be mixed may be set as appropriate.

In addition, various modifications and applications are possible within the scope of the gist of the present invention.

As mentioned above, in the coil springs used in automobile suspension systems, after coiling the spring wires, a load test is carried out on each individual product to classify it according to its actual load characteristics, and then the Located at least in part or all of the mutually opposing surfaces of adjacent spring wires that may come into contact with each other, or on the entire spring wire including these mutually opposing surfaces, and having a melting point of 250°C or less A mixture of thermoplastic resin powder and a color forming agent whose color classification is selectively set in accordance with the above-mentioned load characteristic classification is sprayed together with flame from a spray gun to fuse the mixture. It is something.

Therefore, even if adjacent spring wires come into contact with each other due to vibrations, shocks, etc., the occurrence of knocking noise can be effectively prevented by the presence of the covering portion.

Since the sheathing is fused to the spring wire, the two are firmly adhered to each other to prevent moisture from penetrating, ensuring that the sheath does not come off or corrode, especially at the mutually contacting parts of the spring wire. can be prevented.

Furthermore, since powder having a melting point of 250° C. or less is used, there is no adverse effect on the dimensions, spring constant, residual stress, etc. of the coil spring body.

Furthermore, no pollution such as air pollution is caused when forming the covering portion, and no masking step is required even when partial covering is applied.

Furthermore, according to the present invention, after coiling the strands, a load test is conducted for each actual product, and colored coatings are formed in different colors according to the obtained load characteristic classification. Not only is it possible to accurately identify the load characteristics, but since a coloring agent is mixed into the resin powder, the formation of the coating and the coloring for identifying the load characteristics of the coil spring can be performed at the same time. Coupled with the ease of automation and production line production, productivity can be greatly improved.

Claims (1)

[Claims] 1 After coiling the spring wires that make up the coil spring body, conduct a load test to classify them according to their load characteristics, and then evaluate the possibility that at least the mutually opposing surfaces of adjacent spring wires will come into contact with each other. A thermoplastic resin powder with a melting point of 250°C or less is located in part or all of a certain location or the entire spring wire including these mutually opposing surfaces, and is selectively colored according to the load characteristic classification mentioned above. 1. A method for forming a colored coating part of a coil spring for a vehicle suspension system, characterized in that the mixture with the color former described in (1) is fused together with a flame from a spray gun.