JP2001212644A - Manufacturing method for aluminum articles with constant cross section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for an aluminum product with a constant cross section whose dimensional accuracy is certified in a simple and easy way. SOLUTION: The method comprises a die casting process which forms aluminum die-cast materials with a substantially constant configuration of a cross section having an odontoid process in the centrifugal or centripetal direction and a sizing process to perform sizing after aluminum die-casting materials are heated and annealed. The manufacturing method enables sizing through cold sizing, and the elongation of aluminum die-cast materials is certified when sizing is performed through the ductility generated from aluminum die-cast materials by application of annealing aluminum die-cast materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum product in which an aluminum die-cast material formed by a die-casting method is formed into a predetermined shape having a constant cross section.

[0002]

2. Description of the Related Art Aluminum-based metals composed of aluminum metals and aluminum alloys have been used in many product fields because of their excellent various properties. Further, in recent years, from the viewpoint of energy saving, it has been particularly noted as a material for reducing the weight of transportation equipment such as automobiles, railway vehicles, ships, and aircraft that consume a large amount of energy, and various industrial equipment. That is, aluminum-based metals are being used not only as various structural materials but also in various actuators. In particular, when used as various types of actuators, dimensional accuracy of products is required along with conditions such as high hardness.

[0003] Not only aluminum-based metal products,
When manufacturing a product having high dimensional accuracy in a general product, a method of performing sizing after forming a rough shape is used.

[0004] Here, as a method of forming a product having a rough shape, a die casting method capable of forming a product having a rough shape at low cost is generally used. Here, the rough product formed by the die casting method has a draft for taking out the die casting material from the mold. This draft was eliminated during sizing. In addition, since the aluminum die-cast product has a small elongation, a crack or the like is generated on a surface to be sized, so that a product having high dimensional accuracy cannot be obtained.

Here, when manufacturing an aluminum-based metal product using a conventional manufacturing method, machining is used as a method of eliminating draft. However, machining has a problem that the cost increases and the cost required for the obtained product increases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a manufacturing method for easily manufacturing an aluminum product having a fixed cross section and a dimensional accuracy guaranteed.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have repeatedly studied a method for manufacturing an aluminum product. As a result, the aluminum die-cast material obtained by the die-casting process is annealed to obtain an aluminum product. It has been found that the die-casting material becomes ductile, and that the ductility guarantees the plastic deformation of the aluminum die-casting material, so that the sizing in the cold state is easily performed.

That is, the method for producing an aluminum product having a constant cross section according to the present invention comprises: a die casting step of forming an aluminum die casting material having a substantially constant cross section having tooth-like projections in a centrifugal direction or a centripetal direction by a die casting method; And a sizing step of performing sizing after annealing by heating.

In the method for manufacturing an aluminum product having a constant cross section according to the present invention, the aluminum die-cast material produced in the die-casting step is annealed to cause the aluminum die-cast material to have ductility. Guarantees the elongation of the die cast material and enables sizing by cold sizing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for manufacturing an aluminum product having a constant cross section according to the present invention includes a die casting step of forming an aluminum die cast material, and a sizing step of performing cold sizing after annealing the aluminum die cast material. .

The aluminum product having a constant cross section manufactured by the manufacturing method of the present invention refers to an aluminum product having a constant axial cross section at an arbitrary position in the axial direction. For example, a product formed in a columnar shape, a tubular shape, or the like can be given. Specifically, products such as a vane type variable valve timing mechanism (VVT-i) housing, an internal gear or an external gear are provided. Can be given.

The die-casting step is a step of forming an aluminum die-cast material having a tooth-shaped projection in a centrifugal direction or a centripetal direction and having a substantially constant cross section by a die-casting method. Here, the aluminum die-casting material having a substantially constant cross-sectional shape means that a die-casting method is a method of forming a die-casting material using a mold, so that a draft for removing from the mold is provided. Further, the substantially constant cross-sectional shape of the aluminum die-cast material having tooth-shaped protrusions in the centrifugal direction or centripetal direction is, for example, a shape such as an external gear having teeth formed in the centrifugal direction like a gear or a spline, It refers to a shape like an internal gear having teeth protruding on the inner peripheral surface. Also,
The number of teeth of the tooth-shaped projection is not particularly limited, and may be one or more.

The formation of the aluminum die-cast material by the die-casting method can be carried out by using the same method as that used in the production of ordinary die-cast materials. That is, the die casting material is formed into a mold shape by pressing the molten alloy of the raw material alloy into the mold and then cooling and solidifying the molten metal. Further, the die casting material can be formed by using a die casting machine used for forming an ordinary aluminum die casting material.

The sizing step is a step of performing cold sizing after heating and annealing the aluminum die-cast material. In other words, the sizing step is a step of performing sizing by performing cold sizing on the aluminum die-cast material that has been subjected to annealing, when the aluminum die-cast material is annealed, the aluminum die-cast material softens and becomes ductile. It is.

Preferably, the annealing is performed by heating the aluminum die-cast material to 350 ° C. or higher. If the heating temperature of the annealing is lower than 350 ° C., the ductility of the aluminum die-casting material, which is the effect of heating, is not improved, and if it exceeds 350 ° C., the ductility is improved, and sizing is possible. In the annealing, the crystal structure is homogenized by the heat treatment, and the crystal structure is cooled while maintaining the homogenized structure.

Here, FIG. 1 shows that the ductility is improved by annealing the aluminum die-cast material. FIG. 1 shows an aluminum die-cast material (ADC1) annealed at various temperatures.
2) shows the results of measuring the elongation of the untreated aluminum die-cast material. Here, the measurement of the elongation of the aluminum die-cast material is performed according to JIS from the runner of the die-cast product.
A No. 14 test piece was cut out, and a tensile test was performed with a tensile tester using this test piece.

From FIG. 1, when the heating temperature is 300 ° C. or less, the aluminum die-cast material shows only about 1% elongation.
When the temperature reaches 00 ° C., an elongation of about 4% occurs, and the elongation becomes an amount capable of molding (3.5% or more).

The aluminum die-cast material is cold-sized after annealing. Cold sizing is a process of sizing an aluminum die-cast material at normal temperature. Since the cold sizing is performed at normal temperature, high dimensional accuracy is guaranteed for the product after sizing. Further, since the work hardening due to the sizing process occurs, the hardness of the product after sizing is kept high.

In the die casting step, it is preferable that the draft angle is within once. The aluminum die-casting material is provided with a draft for die-cutting, and if this draft exceeds once, galling, cracks, and the like will occur on the surface of the product after sizing. That is, if the draft exceeds once, the sizing amount exceeds the sizing amount guaranteed by the ductility of the aluminum die-cast material.

In the die casting step, it is preferable to perform a compression step in which the draft is not less than once, and the aluminum die cast material obtained before the sizing step is compression-formed in the axial direction so that the draft is less than once. That is, when the draft of the aluminum die-cast material formed in the die casting step is once or more, the amount of sizing by cold sizing is reduced by reducing the draft by compression molding to less than once. Here, the axial direction in which compression molding is performed is
It shows the direction in which the die and the aluminum die-cast material relatively move when the die-cast material is removed from the die when the aluminum die-cast material is formed by the die-casting method.

When the compression step is performed, the aluminum die-cast material is preferably subjected to a heat treatment and then compression-molded. That is, by performing the heat treatment before performing the compression molding, the ductility of the aluminum die-cast material is increased, and the occurrence of cracks and the like due to the compression molding can be suppressed. As this heat treatment, for example, the same treatment as the heat treatment performed for the annealing treatment can be performed.

It is preferable to perform a lubrication process before the compression stroke. Examples of the lubrication treatment include lubrication treatment such as zinc phosphate treatment, application of metal soap, and emulsion lubricant. Here, when the lubrication treatment is a bond treatment, if the bond treatment is performed before the compression molding, the lubrication treatment may not be performed at the time of sizing.

It is preferable that the sizing step is a constraining molding for constraining the surface of the aluminum die-cast material opposite to the surface to be sized. In other words, sizing of aluminum die-cast material is performed by applying stress to the sizing surface, but by constraining the sizing surface and the opposite surface, the surface constrained by the stress applied at the time of sizing deforms No longer. As a result, sizing can be performed only on the surface to be subjected to sizing. Furthermore, by making the sizing process a constrained molding, the crystal structure of the sizing portion is subject to the compressive stress from the tensile stress, and in a material with small elongation,
In particular, problems such as surface cracks do not occur.

The aluminum die cast material is preferably subjected to a lubrication treatment before cold sizing. That is, by performing lubrication before cold sizing, lubricity can be imparted to the aluminum die-cast material, and seizure with a mold and wear of a tool can be suppressed during sizing. Examples of the lubrication treatment include lubrication treatment such as zinc phosphate treatment, application of metal soap, and emulsion lubricant.

The method for producing an aluminum product according to the present invention comprises:
This is a manufacturing method in which an aluminum die-cast material is formed by a die-casting machine or the like, and the aluminum die-cast material is annealed and subjected to cold sizing.

The method for producing an aluminum product of the present invention comprises:
Since the aluminum die-casting material is formed by the die-casting method, the aluminum die-casting material can be easily formed. Furthermore, since sizing is performed by cold sizing, sizing can be performed at lower cost than sizing by machining. As a result, the manufactured aluminum product has excellent dimensional accuracy and is provided at low cost.

Further, in the method for manufacturing an aluminum product of the present invention, since the ductility required at the time of sizing is secured by performing annealing, the amount of processing in sizing can be reduced, and as a result, the aluminum die-cast material Can be reduced.

[0028]

The present invention will be described below with reference to examples.

As an example of the present invention, an aluminum product was manufactured using the manufacturing method of the present invention.

(Example 1) In Example 1, an internal gear of an aluminum alloy was manufactured.

More specifically, the internal gear 1 of this embodiment is
It is composed of an ADC 12 and includes a cylindrical main body 10 and internal teeth 12 protruding toward the inner peripheral side of the main body. FIG. 2 shows the gear 1 of the first embodiment.

Here, the ADC 12 used in the internal gear of Example 1 had an elongation at room temperature of 1%. Here, the elongation of this aluminum die-cast material was measured by cutting out a JIS No. 14 test piece from a runner
Using this test piece, a tensile test was performed by a tensile tester to perform the test.

The internal gear of Example 1 was manufactured by forming an aluminum die-cast material from an aluminum alloy raw material using a die-casting method, and then sizing the aluminum die-cast material. That is, it was manufactured by a die casting process of forming an aluminum die cast material from a molten aluminum alloy raw material using a die casting machine, and a sizing process of sizing the aluminum die cast material.

The internal gear of Example 1 was manufactured by the following procedure.

First, an aluminum die casting material was formed using a die casting machine. That is, using a die-casting machine having a die in the shape of an aluminum die-cast material, the molten aluminum alloy material is pressed into the die, and after the molten metal is solidified in the die, it is removed from the die. The material was formed. At this time, the formed aluminum die-cast material had a draft angle for die-cutting of 1 degree. FIG. 3 shows an axial sectional view of the aluminum die-cast material having the draft angle. Here, FIG. 3 is a cross-sectional view of a surface of the internal gear that passes through mutually facing teeth. In addition, the die casting machine used for forming the aluminum die casting material was performed by using a die casting machine used for forming an ordinary aluminum alloy.

The aluminum die-casting material is composed of a substantially cylindrical main body and teeth formed to protrude toward the cylindrical inner peripheral surface of the main body. Here, since the tooth portion has a draft angle, the cross section of one end surface side in the axial direction of the cylindrical main body portion is larger than that of the other end surface side.

Subsequently, compression molding was performed on the aluminum die-cast material to reduce the draft.

The aluminum die casting material was put into a mold, and compression molding was performed. For details, compression molding is performed by pressing the aluminum die-cast material in the axial direction with the inner die while holding the aluminum die-cast material in the outer die of the molding die consisting of the outer die and the inner die. To reduce draft. A diagram of this compression molding is shown in FIG.

As shown in FIG. 4, this compression molding is performed in a state where the outer peripheral surface of the cylindrical aluminum die-cast material 40 is restrained by the outer mold 51 and the inner peripheral surface of the aluminum die-cast material 40 is restrained by the inner mold 52.
This was performed by pressing the punch 55 in the axial direction. Here, the condition constrained by the outer mold 51 means that the outer mold 51 is held by the outer mold 51 that substantially matches the outer peripheral surface so that the outer peripheral surface is not deformed when compression molding is performed. Indicates a state in which The same applies to the constraint in the inner mold. The compression molding is performed at 1.47 × 10 ⁴ kN (15
0 ton) and the inner mold was pressurized.

By performing compression molding, the draft angle formed in the aluminum die-cast material was reduced to 0.5 degrees.

Thereafter, the aluminum die-cast material whose draft was reduced by compression molding was subjected to an annealing treatment. The annealing treatment was performed by heating the aluminum die-cast material to 400 ° C. The annealed aluminum die-cast material was cooled by air cooling.

Subsequently, the aluminum die-cast material subjected to the annealing treatment was subjected to cold sizing. The cold sizing was performed by performing mold forming after imparting lubricity to the aluminum die-cast material by a bonding process.

The bonding treatment is, specifically, a zinc phosphate treatment and is performed for lubrication in the subsequent cold sizing of the aluminum die-cast material. As a specific treatment method, the surface was degreased by alkali washing, and then washed with water to remove the alkali solution. Subsequently, chemical conversion treatment, water washing, and soap application were performed.

The aluminum die-cast material subjected to the bonding treatment was then put into a molding die and subjected to cold sizing. The mold was composed of an inner mold and an outer mold, and the cold sizing was performed by constraint molding in which a surface to be unsized was constrained by the outer mold. The cold sizing was performed by pressing with a pressing force of 196 kN (20 ton).

At this time, the contact surface of the outer die with the aluminum die-cast material is formed in a shape substantially matching the outer peripheral shape of the aluminum die-cast material, and the inner die can form an internal gear having a constant cross section. It was formed into a shape.

Further, at the time of pressurizing in the cold sizing, the forming surface composed of the upper die and the lower die relatively moves in a direction perpendicular to the direction in which the aluminum die casting material is pressed, so that the forming surface is sized. Was done. That is, the inner peripheral surface of the internal gear was sized by applying a relative displacement in the horizontal direction between the upper die and the lower die. The restraint forming in this cold sizing was:

Through the above steps, the internal gear of Example 1 was manufactured.

The internal gear of Example 1 has a desired dimensional accuracy because an aluminum die-cast material is formed and the aluminum die-cast material is sized. Further, the one-degree draft angle of the aluminum die-cast material was eliminated by sizing.

The surface of the internal gear of Example 1 whose dimensional accuracy was guaranteed by sizing was observed.
No damage such as cracks was observed on the surface. Furthermore, the surface of the internal gear has the wear resistance required when actually used as a gear, since the hardness is maintained.

The internal gear of the first embodiment has a sufficiently high surface hardness even if it is subjected to cold sizing, so that it has high abrasion resistance and is sized to a desired shape. ing. Further, the internal gear of the first embodiment is formed by sizing the aluminum die-cast material which can be manufactured at low cost by cold sizing, so that the cost required for manufacturing the internal gear can be reduced.

Embodiment 2 In Embodiment 2, a vane type variable valve timing mechanism (VVT) made of an aluminum alloy is used.
-I) A housing was made.

More specifically, the vane type VVT-i of the second embodiment
The housing 2 is composed of an ADC 12 and has a housing portion 20 having an inner peripheral surface serving as a seal sliding surface, a vane portion 22 formed in a convex shape on the seal sliding surface, and a U-shaped end surface at the tip end of the vane portion 22. And a seal mounting groove 24 having a cross-sectional shape of. FIG. 4 shows a sectional view of the vane type VVT-i housing.

Here, the ADC 12 used in the VVT-i housing of the second embodiment is, as described in the first embodiment,
Elongation at room temperature was 1%.

The production of the VVT-i housing of Example 2 was performed by forming an aluminum die-cast material by a die-casting method and then sizing the die-cast material. Specifically, it was manufactured by the following procedure.

First, an aluminum die casting material was formed using a die casting machine. That is, using a die-casting machine having a die in the shape of an aluminum die-cast material, the molten aluminum alloy material is pressed into the die, and after the molten metal is solidified in the die, it is removed from the die. The material was formed. At this time, the formed aluminum die-cast material had a draft angle for die-cutting of 1 degree. In addition, the die casting machine used for forming the aluminum die casting material was performed by using a die casting machine used for forming an ordinary aluminum alloy.

Subsequently, compression molding was performed on the aluminum die-cast material to reduce the draft angle. First, a heat treatment was performed on an aluminum die-cast material as a pretreatment for compression molding.
This heat treatment was performed in the same manner as the heat treatment performed in Example 1. Here, the heat treatment gives the aluminum die-cast material ductility.

After the heat treatment, the aluminum die-casting material was put into a mold and compression-molded. That is, in the compression molding, the draft was reduced by pressing the aluminum die-cast material in the axial direction with the inner die in a state where the aluminum die-cast material was held in the outer die of the molding die composed of the outer die and the inner die.

In this compression molding, the surface opposite to the molding surface, that is, the outer peripheral surface of the cylindrical housing portion was pressed by the inner die while being restrained by the outer die. Here, the state constrained by the outer mold refers to a state in which the outer peripheral face is not deformed when compression molding is performed by holding the aluminum die-cast material with the outer mold that substantially matches the outer peripheral face. Show.
The compression molding is performed at 1.47 × 10 ⁴ kN (150 to
This was performed by pressing the inner mold with the pressing force of n).

By performing the compression molding, the draft angle formed in the aluminum die-cast material was reduced to 0.5 degrees.

Thereafter, the aluminum die-cast material whose draft was reduced by compression molding was subjected to an annealing treatment. The annealing treatment was performed by heating the aluminum die-cast material to 400 ° C. The heating in this annealing treatment was performed by the same means as in the annealing treatment in Example 1.

Subsequently, the aluminum die-cast material subjected to the annealing treatment was subjected to cold sizing. The cold sizing was performed by performing mold forming after imparting lubricity to the aluminum die-cast material by a bonding process.

[0062] The bonding treatment was specifically a zinc phosphate treatment. The specific processing was performed in the same manner as the bond processing in Example 1.

The aluminum die-cast material subjected to the bonding treatment was then put into a molding die and subjected to cold sizing. The mold was composed of an inner mold and an outer mold, and the cold sizing was performed by constraint molding in which a surface to be unsized was constrained by the outer mold. The cold sizing was performed by applying a pressure of 196 kN (20 ton).

Further, at the time of pressurizing in the cold sizing, the forming die composed of the upper die and the lower die relatively moves in the direction perpendicular to the direction in which the aluminum die casting material is pressed, so that the forming surface is sized. Was done. That is, the inner peripheral surface of the VVT-i housing to be sized was sized by applying a relative displacement in the horizontal direction between the upper die and the lower die. Restraint molding in this cold sizing was performed in the same manner as compression molding.

By the above steps, the VVT-i of the second embodiment
The housing was manufactured.

The VVT-i housing of the second embodiment has a desired dimensional accuracy because an aluminum die-cast material is formed and the aluminum die-cast material is sized. In addition, the one-time draft angle of the aluminum die-cast material has been eliminated by sizing.

When the surface of the VVT-i housing of Example 2 whose dimensional accuracy was guaranteed by sizing was observed, no damage such as a crack was found on the surface. Furthermore, since the internal gear has a high hardness,
It has sufficient abrasion resistance against sliding with the apex seal, rotor, gear and cover required when actually used as a VVT-i housing.

In the VVT-i housing of the second embodiment, the sizing of the aluminum die-cast material is performed by molding, compared with the conventional sizing method by machining. As a result, the cost required for sizing is reduced.

[0069]

According to the method of manufacturing an aluminum product having a constant cross section of the present invention, sizing is performed by subjecting an aluminum die-cast material, which could not be conventionally sized by plastic working due to low ductility, to sizing by plastic working. This has the effect that the cost required for sizing can be reduced.

In the method of manufacturing an aluminum product having a constant cross section according to the present invention, sizing can be performed while maintaining the hardness of the aluminum die-cast material. For this reason, the aluminum product manufactured by the manufacturing method of the present invention is excellent in abrasion resistance because it has the high hardness of the aluminum die-cast material.

[Brief description of the drawings]

FIG. 1 AD when the heating temperature of the annealing treatment was changed
It is a figure showing elongation of C12.

FIG. 2 is a diagram illustrating an internal gear of the first embodiment.

FIG. 3 is a view showing a cross section of an aluminum die-cast material of the internal gear of the first embodiment.

FIG. 4 is a view showing a state of constraint molding in compression molding at the time of manufacturing the internal gear of Example 1.

FIG. 5 is a diagram showing a cross section of a sizing portion of a vane type VVT-i housing according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal gear type gear 10 ... Body part 12 ... Internal tooth 2 ... Vane type VVT-i housing 20 ... Housing part 22 ... Vane part 24 ... Seal mounting groove 40 ... Aluminum die-cast material 51 ... Outer mold 52 ...
Inner die 55 ... Punch

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Claims (5)

[Claims] 1. A die-casting step of forming an aluminum die-casting material having a substantially uniform cross section having tooth-shaped projections in a centrifugal direction or a centripetal direction by a die-casting method, and sizing after heating and annealing the aluminum die-casting material. And a method for manufacturing an aluminum product having a constant cross section. 2. The method for manufacturing an aluminum product having a constant cross section according to claim 1, wherein said die casting step has a draft angle of once or less. 3. The die casting process according to claim 1, wherein a draft angle is at least once, and a compression step is performed in which the aluminum die cast material obtained before the sizing step is compression-molded to reduce the draft angle to less than once. For manufacturing aluminum products with a constant cross section. 4. The method for manufacturing an aluminum product having a constant cross section according to claim 1, wherein said sizing step is a constraint forming for restraining a surface of said aluminum die-cast material opposite to a surface to be sized. 5. The method according to claim 1, wherein the aluminum die-cast material is subjected to lubrication before sizing.