JPS5921385B2 - Manufacturing method for lens parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing optical system lens parts such as camera lens barrels.

In the present invention, lens-related parts specifically include parts that hold a lens in the shape of an optical system such as a cylinder, a ring, or a disk, parts that move the lens, and parts that adjust the pit or magnification. A general term for parts used to adjust exposure.

Conventionally, this type of lens parts requires extremely strict dimensional accuracy, finished surfaces, and smooth fitting in terms of performance and appearance, so turning and milling are performed using aluminum alloy round bars, pipe machines, or forged products as raw materials. It was processed through many processes such as thread cutting.

For this reason, not only was there a loss in cutting the material, but the processing cost was also high because it involved many steps. On the other hand, the production of camera parts by die-casting has already been widely used for camera bodies, etc., but parts around the lens require precision machining and are subject to contradictory harsh conditions such as anodizing and die-casting properties. Even if commercially available aluminum alloys for die casting are used as they are,
Until now, we have not been able to produce lens parts made of aluminum alloy die-casting because we were unable to obtain a satisfactory product.

Specifically, the conditions required for lens parts are (1) that a precise machining finish can be obtained;

(2) It must have mechanical rigidity and smoothness that can withstand repeated sliding operations. (3) A good anodized surface can be obtained.

(4) Good corrosion resistance. Examples include.

In order to provide an aluminum alloy die-cast lens component that satisfies the above conditions, the present inventors have repeatedly conducted research on the selection of aluminum alloys and processing processes, and have finally completed the present invention.

That is, the present invention contains 0.5-4% manganese, 0.1-2% cobalt, 0.1-3% magnesium, and 0.2% iron by weight.
Aluminum alloy consisting of 5-1.5%, balance aluminum and unavoidable impurities or additionally 1.5% silicon
Below, a die-cast body is obtained by injecting molten aluminum alloy containing one or two types of zinc (5% or less) into a die-casting mold, removing the strain during casting, and removing the strain generated during subsequent machining. Heat treatment is performed to prevent
The present invention provides a method for manufacturing aluminum alloy die-cast lens parts by performing the minimum necessary machining, followed by anodizing treatment or blackening treatment after anodizing. When selecting an aluminum alloy for die casting, it is assumed that a die casting that meets the requirements for lens parts mentioned above can be obtained, and also that the alloy has a single molten flow as a requirement associated with die casting. 2) It has low adhesion to the die, and 3. It can minimize the occurrence of defects due to molten metal flow patterns, entrainment of oxides and gases, and absorption. In addition, it is suitable for die casting of lens parts. Moreover, the structure must be susceptible to hot cracking due to solidification shrinkage, and hot cracking resistance is the main factor in alloy selection.

In the present invention, an alloy having the above-defined components was selected as an alloy meeting these requirements. This type of aluminum alloy is described in Japanese Patent Publication No. 50-21288, with 0.1 to 2% manganese, 0.1 to 2% cobalt, the balance aluminum or less than 1% magnesium, and 1% zinc.
Aluminum alloys for die casting that produce a silver to milky white anodic oxide film containing one or more of the following: 0.4% or less of beryllium are known; It cannot necessarily be said that it is sufficient as an aluminum alloy.

Although the aluminum alloy used in the present invention has a slightly grayish anodized film, it has a rigidity that can withstand precision machining, has high mechanical strength, and is suitable for severe die-casting conditions.

Manganese, an alloy component, is the main component that contributes to strength.
If added below the lower limit, no effect will be observed, and if added above the upper limit, die castability and machinability will be poor, and there will be no increase in strength. Cobalt increases the strength of the alloy and contributes to improving die-casting properties, but if it is present too much, it will not have the effect of increasing the strength. Addition of magnesium contributes to improvement of strength and is effective in improving machinability, but excessive addition causes deterioration of die-castability. Although the addition of iron causes the anodic oxide film of the product to become somewhat gray, it is an effective additive component in the present invention because it makes it suitable for severe die-casting conditions. However, excessive addition inhibits machinability. The addition of silicon and zinc are also components that have the effect of increasing strength. The method of the present invention requires heat treatment to remove strain after die casting, and during this heat treatment, magnesium, which is an essential component, and these optional components form intermetallic compounds, precipitate, age harden, and are extremely effective in improving the strength of the product. be. However, excessive presence of both silicon and zinc increases the tendency for hot cracking, which is undesirable. In addition, the valve purity that inevitably mixes into the alloy is 0.2
% or less.

In the present invention, the molten aluminum alloy is injected into a die-casting mold under pressure. Although the die-casting method itself can be adopted as it is, it is preferable to use a vacuum die-casting method in order to reduce entrainment of oxides and gases.

During die casting, the aluminum alloy used contains high melting point metals such as manganese and cobalt as alloy components, so the temperature of the molten metal inevitably becomes high, but overheating of the molten metal causes the generation of oxides, absorption of gas, etc. As this can cause defects in die-cast castings, it is necessary to carry out sufficient temperature control, and when designing the die, the position and size of the sprue, the size of the sprue, and the molten pool must be carefully controlled to prevent oxides from getting caught up in the product body. It is necessary to pay attention to the shape and size of the gas vent.

The obtained die casting is then subjected to heat treatment for the purpose of removing distortion.

The purpose of heat treatment is to prevent distortion caused by residual casting stress in the product during subsequent precision machining, and the treatment temperature is set to a temperature range that does not cause blistering. The time the stress is relieved, typically about 120
Heat treatment is performed at a temperature of 0.5 to 250°C for about 0.5 to 48 hours. Depending on the alloy components of the aluminum alloy used during strain relief heat treatment, magnesium and optional silicon,
Furthermore, due to aging precipitation of an intermetallic compound of magnonium and zinc, mechanical strength is improved compared to the as-cast state.

Therefore, depending on the composition of the alloy, it is preferable to select heat treatment conditions suitable for strain relief and age hardening at the same time.

After heat treatment for strain relief, die castings are machined to suit the intended product, but there are no particular changes to the cutting conditions, and as precision processing is required, it is necessary to pay close attention to the chuck location and chuck method. .

In the present invention, the machining process is simplified by taking into account the design of the die so that the machining process is kept to the minimum required by die casting, and in particular, the milling process is omitted, and the machining time is significantly reduced. The usual sulfuric acid method is applied to the anodizing process.

Regarding degreasing treatment before anodizing treatment, since the object to be anodized is a die-cast casting and is a machined product, there is a concern that cutting oil may remain, so ultrasonic cleaning may be effective if necessary. be.

In some cases, it may be desirable to blacken the parts surrounding the lens to prevent diffused reflection of light, and the blackening treatment may also be performed prior to sealing after anodizing.

The dyes and pigments used are not particularly limited, and commercially available black dyes and pigments can be used. The product which has been anodized or black-dyed after anodization is subjected to a sealing treatment according to a conventional method to obtain a final product.

The product obtained by the present invention has a good machined surface, can sufficiently withstand repeated sliding operations associated with lens movement, pitting, and magnification adjustment, and is not anodized or post-anodized. The finished surface of the black dyeing treatment is also good, and it has excellent corrosion resistance and weather resistance, making it possible to mass produce products of a certain quality.

Next, examples of the present invention will be given, but the present invention is not limited thereto.

EXAMPLE A die casting test was conducted using the aluminum alloys listed in Table 1.

1) Mechanical properties ASTM standard E8-61T. Using a 270-ton die-casting machine equipped with an F1g18 die-casting tensile test piece sampling mold, the various alloy molten metals listed above were cast at a temperature of 760.
A cast tensile test piece was taken at a mold temperature of 100 to 120°C.

A portion of the test piece was subjected to tempering treatment (T5 treatment). The test results are shown in Table 2. 2) Product test Lens barrel model shown in Figures 1 and 2 (outer diameter 50 mm, length 4)
Using a 100-ton die-casting machine with an automatic hot water supply equipped with a mold for 5 mI), molten metal of the alloy listed in Table 1 was
100 castings were made for each rod at temperatures of 0-780°C and mold temperatures of 140-170°C.

The unit weight of the product is approximately 2009, the maximum wall thickness is 2.4 mm, and the minimum wall thickness is 1.711 mm. After die casting, remove the runner and overflow part, and then heat each 5 rod sample at 200℃.
The casting stress was removed by heat treatment 17 for 1 hour. Next, pre-thread cutting is performed using an automatic lathe, and then small pitch screws for fixing (parts 4 and 5 in Figure 1,
P=0.5W! 71) and multi-striped trapezoidal sliding fixtures (Fig. 1, 2)
After cutting, the product is completely degreased with trichlorethylene. The machined surface of the sliding screw is the sample ▲
Except for products No. 11 and 12, all had good finished surfaces with no peeling or chips.

The product ranked No. 11 was deformed during machining due to its low strength, and the product ranked No. 12 had noticeable chipping of the threads. Next, chemical polishing was performed at 110°C for 30 seconds using a mixed solution of phosphoric acid and mononitric acid (9:1), followed by washing with running water for 15 minutes.
Subsequently, 20% sulfuric acid aqueous solution at 20°C, current density 2A/Dm
2 for 25 minutes and then washed with water.

One part of the sample was anodized, washed with water, immersed in a 5% sodium carbonate aqueous solution for 1 minute at room temperature, neutralized, and washed with water L7, Dee.
pBlackMLW (manufactured by SANDOZ (Switzerland)) 1
09/t solution at 70° C. for 10 minutes and dyed black.

All sealing treatments are done by soaking in boiling water for 30 minutes! I did it. As a result of the above, the products of samples ▲1 to 10 had sufficient appearance and performance as lens barrels, and glossy and uniform black dyeing was achieved.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional view of the lens barrel model, and FIG. 2 shows its plan view. 1... Lens barrel body, 2... Sliding mechanism, 3
...Drilled hole, 4,5...Fixing screw.

Claims (1)

[Claims] 1 Manganese 0.5-4%, cobalt 0.1-2% by weight
%, magnesium 0.1-3%, iron 0.25-1.5%
A molten aluminum alloy consisting of the balance aluminum and unavoidable pure substances is injected under pressure into a die-casting mold to obtain a die-cast body, which is then heat-treated, machined to the necessary parts, and then anodized. A manufacturing method for aluminum alloy die-cast lens parts. 2 Manganese 0.5-4%, cobalt 0.1-2% by weight
%, magnesium 0.1-3%, iron 0.25-1.5%
A die-cast body is obtained by injecting a molten aluminum alloy containing the remainder aluminum and unavoidable impurities into a die-casting mold under pressure, followed by heat treatment, machining of necessary parts, and then anodizing and blackening treatment. A method for manufacturing aluminum alloy die-cast lens parts. 3 Manganese 0.5-4%, cobalt 0.1-2% by weight
%, magnesium 0.1-3%, iron 0.25-1.5%
A molten aluminum alloy consisting of 1.5% or less silicon, 5% or less zinc, and the balance aluminum and unavoidable impurities is injected under pressure into a die-casting mold to obtain a die-cast body, which is then heat-treated. A method for manufacturing aluminum alloy die-cast lens parts, which comprises machining the necessary parts and then anodizing them. 4 Manganese 0.5-4%, cobalt 0.1-2% by weight
%, magnesium 0.1-3%, iron 0.25-1.5%
A molten aluminum alloy consisting of 1.5% or less silicon, 5% or less zinc, and the balance aluminum and unavoidable impurities is injected under pressure into a die-casting mold to obtain a die-cast body, which is then heat-treated. A method for manufacturing aluminum alloy die-cast lens parts, which comprises machining the necessary parts, followed by anodizing and blackening.