JP2790925B2 - Manufacturing method of aluminum valve spool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum valve spool for use in transmissions of automatic vehicles and other applications.

[0002]

2. Description of the Related Art As the hydraulic valve spool for an automatic vehicle as described above, an iron-made hydraulic spool has conventionally been used, and the iron-made valve spool has been incorporated into an aluminum casting body such as the ADC12. But,
Since the material differs between iron and aluminum of the body, the coefficients of thermal expansion are different, and as a result, there is a problem that the clearance changes between the two due to a change in temperature, and as a result, the responsiveness deteriorates. In particular, during continuous running or running in the tropics, the hydraulic pressure of the transmission increases, causing a significant deterioration in responsiveness.

Therefore, recently, a valve spool made of aluminum (including its alloy) has been used. This is because the valve spool is made of aluminum, which reduces the difference in thermal expansion coefficient from the aluminum body and keeps the clearance between them small at all times, thereby improving responsiveness and reducing the weight of the spool itself. This is because it is also possible to improve the responsiveness at the same time. However, when an anodic oxide film is formed, the film is exfoliated and powdered due to abrasion during operation, and this may be clogged in a cylinder to deteriorate responsiveness. The cause is as follows.

That is, when an anodic oxide film is formed,
As shown in FIG. 3 , at the position of the so-called pin angle (11a) of the valve spool base material (11), a state in which a missing portion (13) consisting of a portion where the coating (12) is not formed is generated. As shown in FIG. 4 , such a film lacking portion (13) is formed even when the corner is chamfered at the corner and at the obtuse corners (11 a) and (11 a) at both ends. Then, since the film portion where the missing portion (3) is present has weak adhesion between the films, the film is peeled from the lacking portion (3) as a starting point due to the frictional force during operation and becomes powdery. It has been found that such abrasion powder causes clogging and, consequently, deterioration of responsiveness.

The present invention has been made in view of such technical background, and has been made to provide an aluminum valve spool which prevents the anodic oxide film from peeling and powdering and does not cause deterioration in response. Aim.

[0006]

Means for Solving the Problems In order to achieve the above object, the inventor has repeated various experiments and studies, and as a result, has formed a corner portion of a valve spool base material into an arc shape having a radius of curvature of a certain value or more. By defining the thickness of the anodic oxide film coated thereon in a certain range, it is possible to generate the anodic oxide film without generating a missing portion, thereby preventing the generation of film abrasion powder. The present invention has been completed based on the findings described above.

That is, according to the present invention, referring to the reference numerals in the drawings , corners (1a) at both ends of a chamfered corner (3) are provided.
Aluminum spool base material (1a) formed in an arc shape with a radius of curvature of 0.05 mm or more, respectively (1)
Is anodized to form an anodic oxide film (2) having a thickness of 5 to 25 μm on the surface thereof.

[0008]

[Function] Corners (1a) at both ends of chamfered corner (3 )
(1a) a previously formed in an arc-shaped or 0.05mm respective radii of curvature, because to form an anodic oxide film having a thickness of 5~25μm on its surface (2), missing the anodized film at the corners It is produced without forming any parts, so that the film does not peel and powder due to friction during operation.

[0009]

Next, an embodiment of the present invention will be described.

FIG. 2 shows an aluminum valve spool base material (1). As the aluminum constituting the base material (1), A5052, A5056, A6061 and other alloys are generally used.

As shown in FIG . 1, a corner portion (3) of the valve spool base material (1 ) is chamfered, and further an obtuse angle is formed.
The corners (1a) and (1a) at both ends are each formed in an arc shape having a curvature radius of 0.05 mm or more. The reason for this is that by forming the corners in an arc shape of 0.05 mm or more, the anodic oxide film (2) to be formed on the corners can be uniformly formed without a lack of a film-unformed portion. This is because a proper film can be generated. Conversely, if the radius of curvature is less than 0.05 mm, a chipped portion is formed in the anodic oxide film, which causes wear powder due to exfoliation of the powder, which leads to poor response due to clogging. There is .

After the corners of the chamfered corners are formed as described above, the valve spool substrate (1) is subjected to an anodic oxidation treatment, and its surface is coated with an anodic oxide film such as a sulfuric acid film. The formation of the anodic oxide film is for imparting hardness, wear resistance and the like to the valve spool. In the present invention, the thickness of the anodic oxide film needs to be regulated to 5 to 25 μm. If the thickness is less than 5 μm, the effect of improving the hardness and wear resistance is poor, and the significance of forming an anodic oxide film is lost. on the other hand,
With a thickness exceeding 25 μm, even when the corners are formed in an arc shape having a radius of curvature of 0.05 mm or more, it is not possible to suppress the occurrence of the film lacking portion, and as a result, the abrasion powder starting from the missing portion can be prevented. This is because occurrence cannot be prevented. The type of anodic oxidation treatment and other treatment conditions are not particularly limited, and ordinary treatment conditions may be appropriately selected.

Incidentally, an aluminum valve spool base made of A6061 alloy is polished at its corners to form a circular arc having a radius of curvature of 0.1 mm, then degreased and neutralized, and then subjected to a sulfuric acid anode. Perform oxidation treatment,
A sulfuric acid film having a thickness of about 10 μm was formed. The processing conditions were as follows: sulfuric acid concentration: 14 w / v%, liquid temperature: 0 ° C., current density: 2 A /
dm2, time: 20 minutes. Next, after the low-temperature sealing treatment was performed, the state of the film at the corners was examined. As a result, no film missing portion was formed, and a film having a uniform thickness was formed.

[0014]

The present invention has been chamfered according to the above .
Anodizing treatment is performed on an aluminum valve spool base material (1) in which the corners at both ends of the corner portion are each formed into an arc shape having a radius of curvature of 0.05 mm or more, and anodized to a thickness of 5 mm.
An anodic oxide film (2) having a thickness of 25 μm is formed. Therefore, even at the corners of the chamfered corners , the anodic oxide film can be formed without generating the missing portion, and the situation in which the film is peeled and powdered from the starting portion due to friction during operation can be avoided. Therefore, it is possible to prevent deterioration of responsiveness that may be caused by this, and to provide a valve spool with excellent responsiveness and high durability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an aluminum valve spool manufactured according to the present invention.

FIG. 2 is a perspective view of a valve spool base material.

FIG. 3 is a main part of a valve spool manufactured by a conventional method .
It is sectional drawing.

FIG. 4 is another valve spur similarly manufactured by a conventional method .
It is principal part sectional drawing of a tool.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Valve spool base material 1a ... Corner part 2 ... Anodized film 3 ... Corner part

Continuation of the front page (56) References JP-A-4-219574 (JP, A) JP-A 60-139965 (JP, U) JP-A 9-17480 (JP, U) JP-B 62-14039 (JP, U.S.A.) , B1) Jikyou Hei 2-42931 (JP, Y2) Revised edition of "Electroplating Guide '88" (S63.01.20) 30 (58) Field surveyed (Int.Cl. ⁶ , DB name) F16K 11/07 F16K 3/24 C25D 11/00 302

Claims (1)

(57) [Claims] An aluminum valve spool base material (1) in which corners (1a) (1a) at both ends of a chamfered corner (3) are each formed into an arc shape having a radius of curvature of 0.05 mm or more, Anodize and apply a thickness of 5-25μ on the surface
A method for manufacturing an aluminum valve spool, comprising forming an anodized film (2) having a thickness of m.