JPH0544086A - Production of aluminium made valve spool - Google Patents

Abstract

PURPOSE:To evade peeling and powdering of a coating film by preliminary removing an unstable forming part of an anodized coating film by grinding. CONSTITUTION:The easily peelable part 4 of the anodized coating film on a base material 1 of an aluminium made valve spool is preliminarily intentionally removed by mechanical grinding. As the result, the deficient part 3 is eliminated and the cause of peeling and powdering of the coating film with time due to the repetition operation of a transmission is removed.

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 used for a transmission of an automatic vehicle and others.

[0002]

2. Description of the Related Art Conventionally, a hydraulic valve spool made of iron has been used as a hydraulic valve spool for an automatic vehicle as described above, and the valve spool made of iron has been incorporated in a body made of cast aluminum such as ADC12. But,
Since the materials of iron and aluminum of the body are different from each other, the coefficients of thermal expansion are different, so that there is a problem that the clearance between the two changes due to temperature change, resulting in deterioration of responsiveness. In particular, the hydraulic pressure of the transmission rises during continuous running or in the tropics, resulting in a significant deterioration in responsiveness.

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

That is, when an anodized film is formed,
As shown in FIG. 2 and FIG. 3, especially at the corners (1a) of the valve spool base material (1), the missing part (3) formed of the unformed part of the film (2) is generated. Such a film missing portion (3) also occurs when the corner portion is chamfered as shown in FIG. Since the film portion where the missing portion (3) exists has a weak adhesion between the films, the film peels off from the missing portion (3) as a starting point and becomes powdery due to the frictional force during operation. It has been found that such abrasion powder causes clogging and eventually deteriorates responsiveness.

The present invention has been made in view of the above technical background, and it is an object of the present invention to provide an aluminum valve spool which prevents the anodic oxide film from being peeled into powder and does not deteriorate the responsiveness. To aim.

[0006]

In order to achieve the above object, the present invention relates to a portion where an anodic oxide film is liable to be peeled and powdered, that is, a corner covering portion of an aluminum valve spool base material (1). The purpose of this is to intentionally remove such easily peelable parts beforehand by mechanical polishing.

That is, according to the present invention, with reference to the reference numerals of the drawings, an aluminum valve spool substrate (1) is anodized to form an anodized film (2) on the surface thereof, and then the anode spool is formed. A gist is a method of manufacturing an aluminum valve spool, which is characterized in that an easily peeling site (4) of an oxide film (2) is mechanically polished and removed in advance.

[0008]

Function: Since the easily peelable portion of the anodic oxide film is mechanically polished and removed in advance, the easily peelable portion of the anodic oxide film does not become powdered due to friction during operation.

[0009]

Embodiments of the present invention will be described below.

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

The valve spool base material (1) is anodized to form an anodized film such as a sulfuric acid film on its surface. The anodic oxide film is formed in order to impart hardness, wear resistance and the like to the valve spool. The type of anodizing treatment and the treating conditions are not particularly limited, and ordinary treating conditions may be appropriately adopted, but it is desirable that the thickness of the anodizing film is 10 μm or more. This is because if it is less than 10 μm, the effect of improving hardness and wear resistance becomes poor, and the significance of forming an anodized film may be lost.

Thus, the anodic oxide film has a thickness of 30 to 4 in particular.
When it is formed so as to reach 0 μm, in the anodized film (2) coated on the valve spool base material (1), for example, a missing portion (a film-unformed portion) is formed in a portion covered by a corner (1a). 3) has occurred. This missing part (3)
Causes the peeling powder of the film with time due to repeated operation as a transmission, and causes deterioration of responsiveness due to clogging of the abrasion powder in the cylinder.

Therefore, in the present invention, the easy peeling site (4) including the missing portion (3) which is easily peeled off is intentionally removed beforehand by mechanical polishing as shown in FIG. The reason why the polishing is limited to the mechanical polishing is that the easily peeling site (4) can be removed very easily by the mechanical polishing. For example, using No. 4 silica sand, a shot pressure of 5 kgf / cm2
Easily peelable parts that may peel off when mounted and used by performing 10 sec / pc shot blasting at (4)
Peels off easily. As the mechanical polishing method, in addition to the above shot blasting, barrel polishing, emery paper polishing,
Examples thereof include belt polishing and grindstone polishing.

When the sliding surface is roughened by the mechanical polishing, finishing may be performed by centerless polishing with a grindstone to smooth the coating surface, if necessary.

[0015]

According to the present invention, the valve spool base material made of aluminum is subjected to anodization treatment to form an anodized film on the surface thereof according to the above description, and the easily peeled portion of the anodized film is mechanically preliminarily removed. It is to be removed by polishing. Therefore, it is possible to avoid the situation where the easily peelable part of the anodized film is peeled into powder by friction during operation, so that it is possible to prevent the deterioration of the responsiveness that may occur due to this, and to improve the responsiveness. It can be used as a valve spool with excellent durability.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential 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 cross-sectional view of a main part of a valve spool before mechanically removing an easily peelable portion.

FIG. 4 is a sectional view of an essential part of the valve spool before mechanically removing the easily peelable portion.

[Explanation of symbols]

 1 ... Valve spool base material 2 ... Anodized film 4 ... Easy peeling site

Claims (1)

[Claims] 1. A valve spool base material (1) made of aluminum is anodized to form an anodized film (2) on its surface, and then an easily peeled site (4) of the anodized film (2) is formed. A method for manufacturing an aluminum valve spool, which comprises mechanically polishing and removing in advance.