JPH0339439A - Aluminum alloy material for mirror-like finishing and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the Al alloy material having suitably high mirror like finishing properties by preparing an Al alloy in which the size of intermetallic compounds is regulated to specified value by the use of an Al metal having specified purity. CONSTITUTION:At the time of directly casting an Al alloy metal having <=99.9% purity (preferably about 99.8 to 99.9%) into a round bar (of about 20 to 130mm) by using a continuous casting apparatus or the like and subjecting it to homogenizing treatment to manufacture an Al alloy material, it is poured so that the cooling rate at the time of casting is regulated to >=5 deg.C/sec. In this way, the Al alloy material having high mirror-like finishing properties of <=8mu size of intermetallic compounds can be obtd., which is suitable, e.g. to a polygon mirror used for a laser printer.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is ideal for applications that require high smoothness (low roughness) and reflectance in mirror finishing, such as polygon mirrors used in laser printers. This invention relates to an aluminum alloy material and its manufacturing method.

(Prior Art) Conventionally, an alloy made of high-purity aluminum metal has been used as a polygon mirror material used in laser printers. As for the aluminum purity, a base metal having an aluminum purity of 99.9% or more or 99.99% or more is used.

This is because when cutting the above-mentioned aluminum alloy material into a mirror surface with a lathe etc., the coarse intermetallic compounds present in the aluminum alloy have an adverse effect on obtaining high smoothness (low roughness). This is because it also adversely affects the reflectance.

Therefore, conventionally, polygon mirror materials have been made of high-purity base metals, with added amounts of Mg and Si that do not generate intermetallic compounds.
Aβ-Mg series or Al2-M with improved machinability by adding
A g-3i alloy is used.

Polygonal shapes such as round rods and hexagonal rods are used as raw materials, but the manufacturing method is first to manufacture ingots by the DC method or an improved gas pressure casting method, and then extrusion or extrusion assisted pulling. Punching is performed, that is, wrought material is used as the material.

(Problem to be solved by the invention) AA-Mg system or An using the above-mentioned conventional high-purity metal
An aluminum alloy material for mirror finishing obtained from a wrought material of -Mg-Si alloy may not be able to meet the recent demands for high reflectance. That is, Aβ-Mg
or An-Mg-Si alloy intermetallic compound (Aβ-
(Fe or Al2-Fe-5L-based intermetallic compounds) may have an adverse effect on the finished cut surface. That is, 9
Maximum 10μm for materials using 9.9% bare metal, 99.99%
Materials using bare metal contain intermetallic compounds with a maximum diameter of about 5 μm, which can adhere to the tip of the cutting tool or damage the tip of the cutting tool, causing scratches and a reduction in surface roughness.

Further, the cost of aluminum ingots of 99.81% or more is higher because the refining method is different from that of general aluminum ingots (AI 299.7%). Especially 99.99%
The unit price of the above high-purity metals is more than twice that of general metals. Naturally, materials using such high-purity metals are expensive products.

The present invention has been made for the purpose of providing an aluminum alloy material that does not require the use of high-purity aluminum metal and has high mirror workability suitable for polygon mirrors, etc., and a method for manufacturing the same.

(Means for Solving the Problems) The present inventors have found that by reducing the size of intermetallic compounds in aluminum alloy materials for mirror finishing to a predetermined amount or less without using high-purity aluminum ingots, the finished surface roughness can be improved. Focusing on the possibility of improving reflectance, various studies were conducted.

The cooling rate of casting is determined by the amount of cooling water and the casting speed, but for normal ingots, if the cooling rate is too fast, the temperature difference between the outer periphery and the center of the ingot will become large, causing cracks in the ingot. On the other hand, cast rods have a small casting size and a small temperature difference, so the cooling rate can be increased and the growth of intermetallic compounds during solidification is suppressed, resulting in a structure consisting of intermetallic compounds smaller than that of the ingot. The present invention was completed based on this finding.

That is, the present invention provides (1) an aluminum alloy material for mirror finishing, which is manufactured using an aluminum base metal with a purity of 99.9% or less and has an intermetallic compound size of 8 μm or less, and (2) For mirror finishing, which is characterized by casting at a cooling rate of 5°C/sec or higher during casting when producing aluminum alloy material by casting an alloy using aluminum base metal with a purity of 99.9% or less. The present invention provides a method for manufacturing an aluminum alloy material.

The aluminum base metal used in the present invention is 99.8% to 9%
An aluminum purity of 9.9% is preferred.

Further, the size of the intermetallic compound present in the alloy material of the present invention is 8 μm or less. This is because if the intermetallic compound exceeds 8 μm, the required smoothness (low roughness) cannot be obtained.

In the present invention, the additive elements added to the aluminum base metal include F e 0.
005-0.09%, Si 0.005-0.70%
, Mg 0.5-5.0%, Mn 0.001-0
．． 0.002% is preferable, and in addition to this, Cr etc. can be added.

Next, the method for manufacturing the aluminum alloy material of the present invention will be described. An aluminum alloy ingot is directly cast into a round bar using a continuous casting machine or the like. The diameter of this round bar is preferably in the range of 20 to 130 mm. This is because within this range, even if the ingot is rapidly cooled, the temperature difference between the outer periphery and the center of the ingot will not increase and no cracks will occur.

The cooling rate during casting shall be 5° C./second or more. This is because if the speed is less than 5° C./sec, a sufficiently small intermetallic compound cannot be obtained.

A homogenization treatment is performed using the above casting method to obtain an aluminum alloy material for mirror finishing.

(Example) The present invention will be explained in detail below based on examples.

Predetermined amounts of Mg and Mn were added to the base metals shown in Table 1, and the size of intermetallic compounds, occurrence of scratches during mirror cutting, and reflectance of six types of alloys were investigated. All materials have an outer diameter of 60
It was made into a round bar of mm.

For cast rods, we use continuous casting equipment to directly cast the rods with an outer diameter of 63 m.
It was cast into a round bar of m. The cooling rate in this case is 8℃/sec (
After casting, a homogenization treatment was performed at 530°C for 6 hours, after which it was machined to an outer diameter of 60mm and used for testing.

On the other hand, the extruded rod was first cast into an ingot with an outer diameter of 345 mm.
The cooling rate in this case was 2.0°C/sec (120°C/min). After homogenizing this ingot at 530°C for 6 hours, a round bar with an outer diameter of 60 mm was extruded and tested. provided.

As is clear from the results shown in Table 1, when the alloy material according to the present invention has the same purity of β, the frequency of occurrence of scratches on the cut surface is lower than that of the comparative example, and the reflectance of the cut surface is also lower than that of the comparative example. Excellent. Moreover, even if the Aβ purity is lowered, the above performance is good.

Example 2 Six types of β-Mg-Si alloys shown in Table 2 were prepared in the same manner as in Example 1, and the size of intermetallic compounds, occurrence of scratches during mirror cutting, and reflectance were investigated. did. The material was a round bar with an outer diameter of 45 mm.

For cast rods, we use continuous casting equipment to directly cast the rods with an outer diameter of 48 m.
It was cast into a round bar of m. The cooling rate in this case was 10° C./sec (600° C./min). After casting, a homogenization treatment was performed at 540° C. for 8 hours, and then it was externally machined to an outer diameter of 45 mm and used for testing.

On the other hand, extruded specimens are first cast into an ingot with an outer diameter of 220 mm.
The cooling rate in this case was 2.6°C/sec (156°C/min). After homogenizing this ingot at 540°C for 8 hours, a round bar with an outer diameter of 45 mm was extruded and tested. provided.

As is clear from the results shown in Table 2, the alloy material according to the present invention has a lower frequency of cut surface scratches compared to the comparative example when Al1 has the same purity, and also has a lower cut surface reflectance than the comparative example. Excellent. Further, even if the Aε purity is lowered, the above performance is good.

(Effects of the Invention) As explained above, the aluminum alloy material for mirror finishing of the present invention has few defects during cutting and has excellent reflectance of the cut surface. In addition, instead of using high-purity metal of over 99.9% in the past, we now use metal of 99.9% or less to generate smaller intermetallic compounds, resulting in superior quality aluminum for mirror finishing. It can be made of an alloy material, and the cost can be significantly reduced.

The aluminum alloy material for mirror finishing of the present invention is suitable for polygon mirror materials for laser printers and the like.

Claims (2)

[Claims] (1) An aluminum alloy material for mirror finishing, which is manufactured using an aluminum base metal with a purity of 99.9% or less, and has an intermetallic compound size of 8 μm or less. (2) When manufacturing an aluminum alloy material by casting an alloy using an aluminum base metal with a purity of 99.9% or less, the cooling rate during casting is 5°C/second or more. A method for producing aluminum alloy material for mirror finishing.