JP5093214B2 - Electrodeposition coating method for hub unit bearings - Google Patents

Description

  The present invention relates to a hub unit bearing, and more particularly to a coating film on a peripheral surface of a hub pilot outer diameter portion of the hub unit bearing.

2. Description of the Related Art In recent years, in automobile axle devices and the like, as described in Japanese Patent Application Laid-Open No. 2000-142009 (hereinafter referred to as prior art), etc., in order to reduce the number of parts and product cost, So-called third-generation hub unit bearings have been developed that integrate these with the components of the axle device. In the prior art hub unit bearing, the mounting flange of the suspension device is formed on the outer ring of the double-row angular ball bearing, one inner ring (first inner ring) is integrated with the hub, and the other inner ring (second inner ring) is further integrated. The inner ring holding cylinder formed on the hub is externally fitted and press-fitted. A female spline is formed on the shaft core of the hub, and a male spline of a drive shaft is fitted into the female spline, and a driving force is transmitted from the drive shaft to the hub (that is, a wheel).
The hub of the hub unit bearing described above is provided with a pilot outer diameter portion that is a guide for centering when the wheel is attached to the hub in a convex shape on the side where the wheel is attached. Conventionally, a black paint has been brush-painted, spray-painted and baked on the peripheral surface of the pilot outer diameter portion for the purpose of rust prevention or the like to form a paint film.

  However, in conventional brush painting and spray painting, it takes 4 to 5 days for the coating film to be completely cured, causing problems such as peeling at the handling stage until the coating film is completely cured. It was. Furthermore, since the hardness of the coating film was insufficient, there were problems that it was easily damaged and peeled off, and that it was difficult to apply the coating film uniformly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hub unit bearing having an excellent coating film on a peripheral surface of a pilot outer diameter portion of the hub unit bearing and an electrodeposition coating method for the hub unit bearing. .

In order to solve the above-mentioned problems, in the present invention, a coating film electrodeposition of a hub unit bearing having a hub integrally formed with a wheel mounting flange and a pilot outer diameter formed on a ridge on the wheel side. In the method
The hub includes an inner peripheral surface from an outer peripheral surface of the pilot outer diameter portion except for the flange portion by immersing only the pilot outer diameter portion while overflowing the coating solution into the electrodeposition tank during electrodeposition of the coating film. The electrodeposition coating method for the hub unit bearing is characterized by being formed continuously .

Thus, in the present invention, the coating film is formed on the peripheral surface of the pilot outer diameter portion of the hub of the hub unit bearing using the electrodeposition coating method. In the case of an electrodeposition coating film, the electrodeposition of the coating film is completed, and after baking and cooling, the coating is completely cured, so even if kerosene / solvent adheres, it does not peel off at all. In addition, the coating film can be formed uniformly and thinly, and baking and cooling time are short. Furthermore, a coating film having a higher hardness than that of the spray coating film, which is hard to be damaged and difficult to peel off can be obtained. Furthermore, in the present invention, the electrodeposition coating film is formed by immersing the pilot outer diameter portion while overflowing the coating solution in the electrodeposition tank, thereby removing the flange portion from the outer peripheral surface of the pilot outer diameter portion. In addition, since the electrodeposition is continuously performed, there is an effect that the influence of the undulation on the coating liquid surface and the shaking of the apparatus is reduced by keeping the overflow and the coating range constant.

It is the longitudinal cross-sectional view which showed the hub unit bearing which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a hub unit bearing 1 according to an embodiment of the present invention.
In this embodiment, the present invention is applied to a third generation hub unit bearing for a drive axle in an FF (front engine / front drive) type passenger car. In FIG. 1, a member denoted by reference numeral 3 is an outer ring of the double row angular ball bearing 5, and first and second raceway surfaces 7 and 9 having arcuate cross sections opened outward in the axial direction on the inner peripheral side thereof. Is formed. A flange 11 is formed on the outer peripheral side of the outer ring 3, and the hub unit bearing 1 is coupled to a knuckle arm (not shown) of the suspension device via the flange 11.

  A first inner ring 15 integrated with the hub 13 is disposed on the first raceway surface 7 side of the outer ring 3, and an inner side corresponding to the first raceway surface 7 of the outer ring 3 is disposed on the outer peripheral side of the first inner ring 15. A raceway surface 17 having an arcuate cross section that opens in the direction is formed. Between the raceway surface 17 of the first inner ring 15 and the first raceway surface 7, a first roller row 23 including a plurality of steel balls 19 and a cage 21 is interposed. In the figure, reference numeral 25 denotes an inner locking end, and reference numeral 27 denotes a shaft seal.

  A second inner ring 31 is disposed on the second raceway surface 9 side of the outer ring 3, and an inwardly open arcuate cross section corresponding to the second raceway surface 9 of the outer ring 3 is disposed on the outer peripheral side of the second inner ring 31. The track surface 33 is formed. Between the raceway surface 33 and the second raceway surface 9 of the second inner ring 31, a second roller row 35 including a plurality of steel balls 19 and a cage 21 is interposed.

  The second inner ring 31 is fitted and press-fitted into a second inner ring holding cylinder 37 extending inside the hub 13, and the inner locking end 39 abuts on the inner locking end 25 of the first inner ring 15. While being positioned in the axial direction, it is fixed and integrated with the hub 13 by a swing caulking 41 applied to an end of the second inner ring holding cylinder 37. In the figure, a member denoted by reference numeral 43 is an encoder that is externally fitted and fixed to the second inner ring 31, and a hub 13 that outputs to an electronic control device (not shown) together with a sensor fixed to a knuckle arm (not shown). (Ie, wheel) rotation information is generated. A wheel mounting flange 49 in which a hub bolt 47 is implanted is formed on the hub 13, and a wheel (not shown) is mounted on the wheel mounting flange 49. A female spline 51 is formed at the axial center of the hub 13.

  On the wheel side of the hub 13, a pilot outer diameter portion 42 serving as a guide for the wheel center is provided. In order to prevent rust and the like, the peripheral surface of the pilot outer diameter portion 42 is provided with, for example, black rust preventive coating (indicated by a thick solid line in FIG. 1). This rust-proof coating film is applied only to the peripheral surface of the pilot outer diameter portion 42 by an electrodeposition coating method.

  Hereinafter, the formation of the electrodeposition coating film used in the present application will be briefly described. The hub 13 is dried after degreasing and washing to remove oil and fat. After attaching a cap (not shown) to prevent the coating film from adhering to the formation portion of the female spline 51, an electrode is attached to the dried hub 13 so that only the peripheral surface portion of the pilot outer diameter portion 42 can be dissociated. The electrode is immersed in an electrodeposition tank (for example, a cup-shaped container) in which the paint is spread, and a voltage is applied between the electrode and the electrode provided in the electrodeposition tank. Electrodeposit on the circumference. In the electrodeposition apparatus used this time, in order to simplify the apparatus, the phosphorylation treatment before painting is omitted, and in order to improve the parting off of the painted part even though it is a partial painting, the paint is applied into the cup instead of simple immersion. The coating area is kept constant by circulating the air through the pump and keeping the overflow from the cup constant. As a result, the influence of undulations on the coating liquid surface and shaking of the device is reduced. As an example, when the coating film thickness was about 15 μm, the electrodeposition voltage was 200 V and the electrodeposition time was 1 minute. After electrodeposition of the coating film is completed, the electrodeposition coating film is cured by baking and cooling at a high temperature to complete the coating film. The baking treatment of the coating film may use far infrared rays in addition to the normal heat treatment. This time, when far infrared rays were used, the baking time after painting was about 3 minutes. During this time, the surface temperature of the hub 13 is 140 degrees and the internal temperature of the bearing is 100 degrees or less so that the structure of the material of the hub 13 is not affected. When far-infrared rays are used in this way, there are effects of controlling the baking temperature of the coating film and shortening the cooling time.

  The electrodeposition coating film prepared as described above can form a coating film that is thinner and more uniform than a coating film prepared by conventional brush coating or spray coating. In addition, the coating film does not peel off even when a solvent such as kerosene adheres. Furthermore, the hardness of the electrodeposition coating film is 5H to 7H, which is higher than that of the spray coating film 2H, and the risk of scratches, peeling, etc. is reduced, and the rust prevention effect can be greatly improved.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, although the color of the paint has been described as black, it is not limited to black, and any water-soluble paint that can be dissociated can be electrodeposited. Furthermore, although the cationic electrodeposition coating method using a cation (cation) paint has been described, the same effect can be obtained by an anion electrodeposition coating method using an anion (anion) paint. Further, it goes without saying that the present invention can also be applied to the outer peripheral surface of the pilot outer diameter portion of other generation hub unit bearings such as the first generation and the second generation.

(Effect of the invention)
As described above, according to the present invention, the electrodeposition coating film is used as the coating film on the outer surface of the pilot outer diameter portion of the hub unit bearing, so that the film thickness is thin, uniform, and high hardness of 5H to 7H. Thus, a hub unit bearing having an excellent rust prevention effect can be provided.
Further, in the present invention, the electrodeposition coating film includes an inner peripheral surface from an outer peripheral surface of the pilot outer diameter portion except for the flange portion by immersing the pilot outer diameter portion while overflowing the coating solution in the electrodeposition tank. Since the electrodeposition is continuously performed, the effect of undulation on the coating liquid surface and the shaking of the apparatus can be reduced by keeping the overflow and the coating range constant.

DESCRIPTION OF SYMBOLS 1 ... Hub unit bearing 3 Outer ring 5 Double row angular contact ball bearing 7 First raceway surface 9 Second raceway surface 13 Hub 15 First inner ring 17 Raceway surface 19 Steel balls 21 ... Cage 23 ... 1st roller train 31 ... 2nd inner ring 33 ... Raceway surface 35 ... 2nd roller train 37 ... 2nd inner ring holding cylinder 42 ... Pilot outer diameter 51 ... Female spline

Claims (1)

In a coating film electrodeposition method for a hub unit bearing having a hub integrally formed with a wheel mounting flange and a pilot outer diameter formed on a ridge on the wheel side,
The hub includes an inner peripheral surface from an outer peripheral surface of the pilot outer diameter portion except for the flange portion by immersing only the pilot outer diameter portion while overflowing the coating solution into the electrodeposition tank during electrodeposition of the coating film. An electrodeposition coating method for a hub unit bearing, characterized by being formed continuously with

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