JPH0763836B2 - Aluminum alloy casing manufacturing method and bearing insert for casing manufacturing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a transmission casing of an automobile, for example,
The present invention relates to a method for manufacturing an aluminum alloy casing having a through hole into which an outer race of a ball bearing or a roller bearing is to be press-fitted, and a bearing insert used for casting the casing.

(Prior Art) A transmission casing of an automobile equipped with a relatively high-power diesel engine, such as a truck and a tractor, which has large transmission torque and large torque fluctuation, is conventionally made of cast iron.

(Problems to be Solved by the Invention) In a normal transmission casing, a pair of ball bearings that respectively support a drive pinion that serves as an input shaft and a main shaft that serves as an output shaft are arranged on the same axis line. A pair of ball bearings that support both ends of a counter shaft that is arranged parallel to the shaft are arranged on an axis parallel to the axis. The four ball bearings are supported by press-fitting the respective outer races into through holes formed in the casing wall.

Recently, in a large vehicle such as a truck, it has been considered to reduce the weight by making a cast iron transmission casing from an aluminum alloy in order to improve power performance and fuel efficiency, but the transmission torque is large and the torque fluctuation is large. Since the outer race of the ball bearing rotates around with the rotation of the drive pinion, the main shaft, the counter shaft, etc., the bearing press-fitting hole on the casing wall is prematurely worn, resulting in rattling of the outer race. Occurred.

Therefore, in order to prevent early wear of the bearing press-fitting holes, an aluminum alloy is used as a matrix, and high hardness fine particles such as silicon carbide and alumina for improving wear resistance are dispersed in the matrix metal. After inserting an insert made of a material into a predetermined portion of a casing casting mold, that is, a portion where a bearing press-fitting hole is to be formed, it is attempted to encircle the insert with a molten aluminum alloy for casting that forms the casing body, It was confirmed that this method can remarkably improve the wear resistance of the bearing press-fitting hole and improve the mechanical strength of the casing wall surface at the outer peripheral portion of the press-fitting hole. However, since the insert made of the composite material using the aluminum alloy as a matrix metal has a scaffolding oxide film formed on the surface during its production, when cast with the molten aluminum alloy forming the casing body, it is sufficient. It was confirmed that stable bond strength could not be obtained, and there were many variations in quality.

According to the present invention, a sufficient bonding strength is stable between an insert made of an aluminum alloy composite material, that is, a bearing insert that is cast around a casing portion where the bearing press-fitting hole is to be formed, and an aluminum alloy forming the casing body. It is an object of the present invention to provide a method of manufacturing an aluminum alloy casing secured by the above method, and a bearing insert used in carrying out the method.

(Means for Solving the Problems) The present invention was devised to achieve the above-mentioned object, and aluminum containing 10 to 13% by weight of silicon is provided in a portion of a casing casting mold where a bearing press-fitting hole is to be formed. Silicon alloy, consisting of aluminum alloy composite material in which particles of alumina, etc. are dispersed in the alloy, and after inserting an annular insert having a thin portion formed on the outer peripheral edge thereof, the molten aluminum alloy for casting in the mold A method of manufacturing an aluminum alloy casing, characterized in that the insert is integrally cast by melt-bonding a thin portion of the outer peripheral edge of the insert and a molten metal, and an aluminum alloy containing 10 to 13% by weight of silicon. Characterized in that a thin portion is provided on the outer peripheral edge of an annular body made of an aluminum alloy composite material in which particles of silicon carbide, alumina, etc. are dispersed. It is an gist bearing unit inserts used in the practice of the method.

(Operation) According to the present invention, the bearing insert for forming the bearing press-fitting hole of the aluminum alloy casing is made of a composite material in which particles of silicon carbide, alumina, etc. are dispersed in the aluminum alloy. Wear resistance of the bearing press fit hole is improved. In addition, the melting point of the insert using an aluminum alloy containing 10 to 13% by weight of silicon as the matrix metal of the insert is lowered (about 590
C.) and the shape of the insert is a ring-shaped body that forms a bearing press-fitting hole and surrounds the outer periphery of the hole, and a thin portion that easily melts is formed on the outer peripheral edge of the insert to form the insert and the casing body. The aluminum alloy will be melt-bonded at least at the outer peripheral edge portion of the insert.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings. First, FIG. 1 shows a transmission casing for an automobile as an example of a casing cast by the method of the present invention. In the figure, reference numeral 10 is a casing main body, and 12 is a cover that is provided to cover the upper opening of the casing main body 10, and generally forms a lower case of a gear shifter. In the casing body 10, a first bearing press-fitting hole 14 for press-fitting an outer race of a ball bearing that pivotally supports a drive pinion that serves as an input shaft, and an output side end portion of a main shaft that serves as an output shaft are pivotally supported. A second bearing press-fitting hole 16 for press-fitting the outer race of the ball bearing is provided, and both press-fitting holes 14 and 16 are arranged on the same axis.
Further, the casing body 10 is provided with third and fourth bearing press-fitting holes 18 and 20 for press-fitting the outer races of a pair of ball bearings that support both ends of the counter shaft. It is arranged on the counter shaft axis parallel to the main shaft axis.

The bearing press-fitting holes 14, 16, 18 and 20 are respectively formed in the central portions of the bearing inserts 14 ', 16', 18 'and 20', and each insert is inside the casing body 10 as described in detail below. It is cast around and is integrally connected.

In the illustrated embodiment, adjacent bearing press fit holes 14 and 18
, 16 and 20 are close to each other, so that the respective inserts 14 'and 18' and 16 'and 20' form a spectacle-shaped continuous annular body, and the insert 14 'is shown in FIG. And 18 '
The connected annular body of is shown. Each insert 14 ', 16',
18 'and 20' are aluminum alloys for casting containing 10 to 13% by weight of silicon such as JIS AC8A as a matrix metal, and 3 to 12% by weight of silicon carbide and alumina powder are dispersed in the matrix metal. Made of particle-dispersed composite material. The reason why the mixing amount of the powder of silicon carbide, alumina, etc. is 3 to 12% (weight ratio) is that the wear resistance is insufficient if it is less than 3%, and that if the amount exceeds 12%, the mixed powder becomes even. This is because dispersion is difficult, segregation is likely to occur, and tensile strength is deteriorated. Also, by adopting a casting aluminum alloy containing 10 to 13% by weight of silicon as the matrix metal, the insert 14 'to
The melting point of 20 'is as low as about 590 ° C. Further, as shown in the sectional view of FIG. 3, thin-walled portions 22 each having a small heat capacity are formed on the outer peripheral edges of the inserts 14 'to 20'. (Note that, in the drawing, a cross-sectional view of the insert 18 'is representatively shown.) When casting the casing body 10, the mold is 380
Preheated to 〜420 ℃, the bearing insert 14 ', 16', 1
8'and 20 'are preheated to 300 to 350 ° C and placed in a predetermined position in the mold. On the other hand, a normal casting aluminum alloy such as JIS AC4C melt is prepared, and the melt temperature is 700-730 ℃.
Is injected into the mold.

The bearing inserts 14 ', 16', 18 'and 20' are made of silicone.
It is made of an aluminum alloy containing 10 to 13% by weight and has a melting point that is sufficiently lower than that of the molten metal, and a thin portion 22 with a small heat capacity is formed on the outer peripheral edge of each insert. Even if the aluminum oxide film is formed, the molten metal and the insert are melted and metallurgically bonded at least around the thin portion 22. As a result, the bearing inserts 14 ', 16', 18 'and 20' are
Casing body 10 with sufficient bond strength and stability
It will be cast around.

The rough casting material of the casing body 10 manufactured as described above is machined in the bearing press-fitting holes 14, 16, 18 and 20, and other necessary parts, and then the ball bearings described above are inserted in the bearing press-fitting holes. The outer race of the ring is press-fitted. Each bearing press-fit hole 14, 16, 18 and 20 is made of a composite material in which an appropriate amount of particles of high hardness such as silicon carbide and alumina are dispersed in a matrix of aluminum alloy, so it has excellent wear resistance. , Tribe pinion,
It has sufficient durability even if the outer race of the ball bearing rotates around as the main shaft, counter shaft, etc. rotate.

Although the transmission casing is illustrated as an example in the above embodiment, the method and bearing insert of the present invention are
It can be widely applied to various casings that need to press-fit and support outer races such as ball bearings, and JIS AC4C is exemplified as an aluminum alloy that forms the casing body.
Various aluminum alloys for sand molds or die castings, and aluminum alloys for die casting can be adopted depending on the properties. Further, in the above embodiment, since the bearing press-fitting holes which are adjacent to each other are close to each other, the bearing portion insert has a continuous annular body like a spectacle type. Annular inserts are used.

(Effects of the Invention) As described in detail above, the method for manufacturing an aluminum alloy casing according to the present invention is characterized in that silicon is applied to the portion where the bearing press-fitting hole of the casing casting mold is to be formed.
Silicon carbide in an aluminum alloy containing ~ 13% by weight, consisting of aluminum alloy composite material in which particles of alumina and the like are dispersed, and after inserting an annular insert having a thin wall portion formed in the outer peripheral edge thereof, into the above mold A casting of an aluminum alloy for casting is characterized by injecting a molten metal of the outer peripheral edge of the insert and melt-bonding the molten metal with the insert to enclose the insert integrally, and the bearing insert used for carrying out the method is silicon. In an aluminum alloy containing 10 to 13% by weight of silicon carbide, a thin wall portion is provided on the outer peripheral edge of an annular body made of an aluminum alloy composite material in which particles such as silicon carbide and alumina are dispersed. The aluminum alloy casing cast by the above-mentioned manufacturing method using the bearing insert is barely compared to the aluminum alloy cast casing. Has excellent remarkably wear resistance grayed press-fit hole, thus it is possible to improve the durability of the casing.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an automobile transmission casing manufactured by the method of the present invention, FIG. 2 is a front view showing a bearing insert for forming the bearing press-fitting holes 14 and 18 of FIG. 1, and FIG. The drawing is a sectional view taken along the line III-III in FIG. 10 …… Casing body; 14,16,18 and 20 …… Bearing press fit hole; 14 ′, 16 ′, 18 ′ and 20 ′ …… Bearing insert; 22 …… Thin section.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nagasaki Nobuhiro 16 at 2214 Kanaya, Kanaya-cho, Hara-gun, Shizuoka Prefecture (56) References JP-A-58-112649 (JP, A) JP-A-62-89564 (JP, A)

Claims (2)

[Claims] 1. An aluminum alloy composite material in which particles of silicon carbide, alumina, etc. are dispersed in an aluminum alloy containing 10 to 13% by weight of silicon in a portion where a bearing press-fitting hole of a casing casting mold is to be formed. , After inserting an annular insert having a thin wall portion formed on its outer peripheral edge, inject a molten aluminum alloy for casting into the mold to melt-bond the thin wall portion of the outer peripheral edge of the insert and the molten metal, and integrate the insert For producing an aluminum alloy casing characterized in that the aluminum alloy casing is cast 2. A thin-walled portion is provided on the outer peripheral edge of an annular body made of an aluminum alloy composite material in which particles of silicon carbide, alumina, etc. are dispersed in an aluminum alloy containing 10 to 13% by weight of silicon. Bearing insert for aluminum alloy casing manufacturing