JPH03100136A - Aluminum alloy material for die - Google Patents

Abstract

PURPOSE:To improve the wear resistance and toughness in the die for plastic molding by an aluminum alloy obtd. by compacting constituted of alloy elements having specified compositional ratios. CONSTITUTION:The material is formed from an aluminum alloy obtd. by compacting a componental compsn. contg., by weight, 6 to 14% Si, 5 to 10% Cu and the balance Al with inevitable impurities and in which the average size of Si grains is regulated to 0.3 to 10mum. In this way, the wear resistance, heat resistance and toughness can be improved without deteriorating the advantages of the aluminum alloy such as machinability, lightness in weight, corrosion resistance, thermal conductivity, surface treatability (anodic oxidation treatability) and weldability, so that the service life of a molding die for plastics, rubber, metallic powder, ceramic powder, etc., can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a material for molds used when molding parts with complex shapes, and particularly for powder injection of plastics, rubber, metals, or ceramics. This invention relates to aluminum alloy materials used as molds.

[Prior art] Plastic injection molds and blow molding molds are
Steel materials are generally used.

However, aluminum alloys are used for molds that do not require mass production.

Molds made of aluminum alloys are inferior in wear resistance, softening resistance, high-temperature strength, and toughness compared to steel materials, and therefore have a short mold life, but have been preferred because they have the following advantages.

■ Due to good machinability, molding speed is fast (and mold making time is short. Also, tool life during machining is long).

■ Due to its low specific gravity, handling such as making molds and installing it is easy.

■ Good corrosion resistance makes maintenance management easy during downtime.

■ Due to its high thermal conductivity, it has a high cooling capacity as a mold and can shorten the molding cycle.

The type of aluminum alloy requires strength, so JIS
For alloys, Al-Zn-Mg- such as 7075.7079
Cu alloys have been used.

As mentioned above, aluminum alloy molds use an aluminum alloy that has excellent strength and wear resistance, but the mold life is short compared to steel materials. For example, a steel material mold can be stamped with more than 100,000 shots, but an aluminum alloy mold can be stamped with 3,000 to 5,000 shots.
It is about 100%. For this reason, aluminum alloy molds have only been used as simple molds with short lifespans. In addition, the mold life of steel materials and aluminum alloys is approximately 30 years.
There was a difference of twice as much, and it was not possible to take advantage of the superiority of aluminum alloy molds.

It is desired that an aluminum alloy with a lifespan of 1/10 or more than that of steel be developed, and the present inventors have developed an aluminum alloy that contains 15 to 40% Si and 10% or less Cu by powder metallurgy. proposed an aluminum alloy material in which the average diameter of Si particles is 10 μm or less (Japanese Patent Application No. 53-56288).

[Question 8 to be solved by the invention] As mentioned above, the mold made of aluminum alloy is
Because it has a shorter lifespan than steel materials, it was used as a simple mold. However, improvements in aluminum alloys have extended the lifespan of aluminum alloys, and due to their good machinability, they have come to be used in molds with complex shapes. For example, in order to reduce the weight of a plastic molded body such as the switch box shown in Figure 1, the bolt holes provided at the four corners are replaced by an upright cylinder that is independent from the one integrated into the side wall of the box, making the wall thinner. We are trying to

For this purpose, the lower mold (male mold) of the mold has thin ribs that stand upright in a cantilevered manner, as shown in FIG.

When a plastic melt is injected into such a mold, the thin ribs are subjected to bending loads, and the roots of the ribs may break.

Therefore, the purpose of the present invention is to improve the previously proposed ``aluminum alloy material containing 15 to 40% Si and 10% or less Cu, and making the average diameter of Si particles 10 μm or less using a powder metallurgy method.'' An object of the present invention is to provide an aluminum alloy mold material that does not cause such thin wall portions to break.

[Means for solving the problem] In order to solve the above problems, we have improved the strength, wear resistance, toughness, and machinability of the aluminum alloy by variously changing its composition, melting conditions, heat treatment conditions, metal structure, etc. As a result of studying the effects on (surface roughness), etc., we found that it is effective to contain at least Si and Cu as alloy components in A1 alloy formed by powder compaction, and to maintain the Si particle size within a specific range. , completed the invention.

That is, the first invention contains 6 to 14% Si and Cu in weight%.
0.5 to 10%, and the balance is Al and unavoidable impurities, and the average diameter of Si particles is 0.5% to 10%.
It is an aluminum alloy material characterized by having a thickness of 3 to 10μ.

The second invention is Si 6 to 14%, CuO 15% by weight.
~10%, Mg0.3~6%, and the balance is Al and unavoidable impurities, the aluminum alloy is obtained by powder compaction, and the average particle size of Si particles is 0.3 ~ It is an aluminum alloy material characterized by having a thickness of 10μ. The third invention is Si6 in weight%
~14%, Cu 0.5~10%, and further F
eAluminum obtained by powder compaction with a composition containing 0.3 to 6% of one or more metals selected from the group consisting of SMn and Ni, singly or in total, and the balance consisting of Al and inevitable impurities. alloy, and the average diameter of Si and intermetallic compound particles is 0.3 to 10
It is an aluminum alloy material characterized by μ■.

Furthermore, the fourth invention has a weight percentage of 6 to 14% Sl, Cu
0.5 to 10%, Mg 0.3 to 6%, and further contains one or more metals selected from the group consisting of Fe, Mn, and Ni, singly or in total, 0.4 to 6%. An aluminum alloy obtained by powder compaction with a composition consisting of the remainder Al and unavoidable impurities, and
The average diameter of Si and intermetallic compound particles is 0.3 to 10 μ■
It is an aluminum alloy material characterized by:

Next, the reasons for limiting the composition of the aluminum alloy of the present invention will be described.

Si is dispersed as Si particles in the A1 base, and increases wear resistance as the content increases, lowers the coefficient of thermal expansion to suppress distortion due to heat generated during machining, and increases the modulus of elasticity to improve resistance during injection molding. Suppresses mold deformation due to molten resin pressure.

If the Si content is less than 6%, the wear resistance will be insufficient, and it will not be possible to obtain a wear resistance superior to that of the conventional aluminum alloy 7075 for molds. If it exceeds 14%, the toughness decreases, and in molds with thin ribs, the ribs are likely to break. Therefore, the Si content is preferably 6 to 14%.

Cu imparts age hardenability to the alloy and improves wear resistance due to improved hardness. If the Cu content is less than 0.5%, the effect will not be sufficient, and if it exceeds 10%, the effect will be saturated and the corrosion resistance will deteriorate significantly, so it was set at 0.5 to 10%.

Mg coexists with Cu to improve hardness and wear resistance through age hardening. If the Mg content is less than 0.3%, the effect will not be sufficient, and if the Mg content is 6%, the effect will be saturated.
It was set at 3-B%.

Each component of FeSMn and Ni increases the heat resistance of the alloy. That is, the temperature during use of the mold (e.g. 100-150℃
), it suppresses the decrease in hardness (softening) and also increases the strength at room temperature to high temperature. It also has the effect of lowering the coefficient of thermal expansion and increasing the modulus of elasticity. If the content of these components is less than 0.3% individually or in total, the effect will not be sufficient, and if the content exceeds 6%, the material will become brittle and easily chipped during mold processing or use.

In addition, the average diameter of particles of Si and intermetallic compounds is 0.3
If it is less than 10 μm, wear resistance will be insufficient, and if it exceeds 10 μm, chipping or wear of the cutting tool will easily occur, and the surface to be machined will have a rough surface roughness, making it impossible to obtain a mirror finish.

Although there are various methods for producing the aluminum alloy of the present invention, it is generally produced by the following method. That is, after melting the aluminum alloy having the above-mentioned composition, the molten metal is rapidly solidified. Usually, it is cooled at a cooling rate of 100° C./second or more. Specifically, the atomization method and the splat cooling method are applied. The powder thus obtained is (a) pre-compressed - sealed in a container - heated vacuum degassing - extruded, (b) pre-compressed -
Container filling - heating vacuum degassing - hot press, (C) precompression - container filling - heating vacuum degassing - hot press - container removal - extrusion, (d) precompression - heating - extrusion, (e) precompression - container filling - heating It is solidified and molded through processes such as vacuum degassing and HIP (high temperature isostatic pressure compression). in particular (
In method a), aluminum alloy powder is pre-compressed to about 60-90% of its true density by CIP or mold compression, then sealed in a predetermined container and heated to 300-550°C while being evacuated and degassed. conduct.

If the heating temperature during degassing is less than 300° C., degassing will be insufficient and the final product will swell or have pores.

When the temperature exceeds 550°C, the s5 particles grow and become coarse. The pre-compressed product (billet) that has been degassed in this way is
Heat to a temperature of ~520"C and extrude.

Method (b) uses hot pressing (upsetting and compression at high temperatures) to produce an aluminum alloy material instead of extrusion, method (C) is the method in which the container is cut and removed after hot pressing, and extrusion is performed in method (d). is in air, vacuum or N after precompression.
2. The aluminum alloy material is heated in a gas such as Ar to degas it and then extruded, and (e) the aluminum alloy material is obtained by HIP treatment instead of extrusion or hot pressing.

In addition, in either method, it is also possible to omit preliminary compression and directly enclose the powder in a container.

When the mold size is large and large-sized materials are required,
After solidifying and forming by any of the above steps, especially (b) hot pressing or HIP, the material is expanded by forging or rolling to obtain a large-sized material.

The alloy material manufactured in this way has properties such as superior wear resistance, strength, hardness, and heat resistance, low coefficient of thermal expansion, and high modulus of elasticity compared to conventional aluminum alloy materials for molds. It is ideal as a material for In addition, the thermal conductivity is almost the same as that of 7075 alloy, so the tool life for machining will hardly be shortened. Electric discharge machining is also possible.

Furthermore, alumite treatment is also possible. This treatment is performed to further increase wear resistance, and hard alumite is usually used. In addition, if the design of the mold is changed, or if deep engraving is performed by mistake, it is also possible to build up the material by welding. Although TIG and MIG are possible welding methods, it is preferable to use electron beam welding or plasma arc welding, which can reduce the welding area. B A 4043, B A 4045 as filler rods
, BA 4145, BA 4047, BA 40
03, BA 4004, BA 4005, BA
4NO4 etc. are used. In addition, when welding, increase the degassing temperature or lengthen the degassing time during solidification and molding of the powder, and reduce the amount of hydrogen in the material by 0.5cc/10.
0gA 1 or less, preferably 0.3cc/100gA
It is better to set it to 1 or less. At this time, the degassing temperature is 490-5
The temperature is preferably 50°C.

[Example] The present invention will be explained in more detail with reference to Examples below.

Example 1 Alloys No. 1 to No. 30 shown in Table 1 were melted and rapidly solidified powder was created by air atomization.

The obtained powder was classified to have a particle size of 297 μm or less, and then preliminarily compressed to 70 to 75% of the true density by mold compression (CIP), inserted into an Al container, and vacuum degassed while being heated. The heating temperature was 500°C. The billet thus obtained was heated to 400"C and extruded at an extrusion ratio of 14,
A rod with an outer diameter of 401 m was obtained. These No. 1 to No. 30
Extrusion rod at 500℃ x 2hr → water cooling at -175℃ x 8h
A heat treatment of r was performed.

The alloy No. 31.82 in Table 1 has an outer diameter of 150I after melting.
An ingot was prepared and extruded under the same conditions as above. No
The extruded rod of Jl was subjected to the same heat treatment as above, and the extruded rod of No. 32 was heated at 470°C for 2 hours → water cooled → 115°C
Heat treatment (T73 treatment) was performed under the conditions of 7 hours→175° C.×8 hours.

Regarding the above materials, the particle size in the microstructure (Si
particles, Al-5i-Fe-based compound particles, AlAl-8i
- average diameter of all particles such as compound particles, Al-Ni compound particles, etc.), hardness at room temperature (Rockwell scale), hardness at room temperature after heating to 150°C (Rockwell scale), tensile strength at room temperature, Tensile strength at 150°C after being held at 150°C for 100 hours, specific wear amount in Okoshi type abrasion test (dry type, load 2.1kg, friction distance 8001%, mating material 5500), surface roughness after puff polishing (R □8) and when injection molding was performed using a mold, the number of shots until wear occurred or the number of shots until thin rib breakage occurred was measured.

Mold wear occurs because the molten resin is injected at high speed, and this passage section is worn out. When the passage width increases by approximately 2 μI, the flow of the resin deteriorates, so this was measured and used to determine the life span.

The results are shown in Table 2. Invention alloy No.

1 to No. 18, the specific wear amount is small, especially 707
5 (N o, 32). Moreover, the surface roughness is as small as that of 7075, and the surface finish is good. Further, among Nos. 1 to 18, Nos. 1 and 2 do not contain Mg, and Nos. contain Mg.

A comparison of No. 3, No. 4, and No. 4 shows that the hardness tends to increase with the addition of Mg, and also with Fe and Mn.

No including Ni, 5 to No, 18 is No, 1 to N
It can be seen that the hardness after heating and the tensile strength at 150° C. are high from No. 0 and 4.

Comparative alloy No. 19.20 had a large specific wear amount due to a small amount of Si, and the mold life was reached at eoo, 1000 shots. In No. 21.23, the rib of the mold broke at 2500.1100 shots due to the large amount of Sl. N
No. 22 had low Cu and Mg content, low hardness and tensile strength, large specific wear amount, and reached the end of its life after 1500 shots of wear. No, 24 is CU amount No, 25 is M
Although the amount of g was increased, the high strength could not be achieved and the ribs broke. No. 26-30 are
Fes Mn, Ni amount is too large individually or in total,
Chips were likely to occur during cutting of the mold, and the ribs of the mold were broken. In No. 11, the size of the ceramic particles was large and the surface roughness during cutting was large, making it unsuitable as a mold material. NoJ2 is a conventionally used molten cast material of 7075, but it does not have sufficient wear resistance.

Table 1 Table 1 Continued Table 2 ts2 Table [Effects of the Invention] (1) As explained above, the aluminum alloy material of the present invention has the machinability, light weight, and
Corrosion resistance, thermal conductivity, surface treatment (anodized),
It has improved wear resistance, heat resistance and toughness without sacrificing advantages such as weldability, making it suitable for molds for molding plastics, rubber, metal powders, ceramic powders, etc., and significantly improving their service life. be able to.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a part molded by the mold of the present invention, and FIG. 2 is a mold (male mold) for molding the molded product shown in FIG.

Claims (4)

[Claims] (1) An aluminum alloy obtained by powder compaction containing 6 to 14% of Si and 0.5 to 10% of Cu by weight, with the balance consisting of Al and unavoidable impurities,
An aluminum alloy material for plastic molds having excellent wear resistance and toughness, characterized in that the average diameter of Si particles is 0.3 to 10 μm. (2) Si 6 to 14%, Cu 0.5 to 10% by weight,
An aluminum alloy obtained by powder compaction with a component composition containing 0.3 to 6% Mg, the balance consisting of Al and unavoidable impurities, and the average diameter of Si particles is 0.3
An aluminum alloy material for plastic molds with excellent wear resistance and toughness, characterized by a thickness of ~10 μm. (3) Contains 6 to 14% of Si and 0.5 to 10% of Cu by weight, and further contains one or more metals selected from the group consisting of Fe, Mn, and Ni, both singly and in total.
．． An aluminum alloy obtained by powder compaction with a composition containing 3 to 6% and the balance consisting of Al and unavoidable impurities, and the average diameter of Si and intermetallic compound particles is 0.3 to 10μ. An aluminum alloy material for plastic molds with excellent wear resistance, heat resistance, and toughness. (4) Si 6 to 14%, Cu 0.5 to 10% by weight,
Contains 0.3-6% Mg, and further contains Fe, Mn and N
An aluminum alloy obtained by powder compaction containing 0.3 to 8% of one or more metals selected from the group consisting of i, singly and in total, with the balance consisting of Al and inevitable impurities. An aluminum alloy material for a plastic mold having excellent wear resistance, heat resistance and toughness, characterized in that the average diameter of Si and intermetallic compound particles is 0.3 to 10 μm.