JPH04218640A - Die stock - Google Patents

Abstract

PURPOSE:To obtain inexpensive die stock light in weight and having good heat conductivity by subjecting an Al alloy having a specified compsn. constituted of Mg, Mn, Be, Ti, B and Al to water cooling continuous casting. CONSTITUTION:An Al alloy contg. 2.0 to 7.0% Mg, 0.1 to 1.0% Mn, 0.001 to 0.01% Be, 0.003 to 0.15% Ti and 0.001 to 0.2xTi, furthermore contg., at need, 0 to 2.0% Si, 0 to 1.0% Fe, 0 to 5.0% Zn, 0 to 1.0% Ni and 0 to 1.0% Cr and the balance substantial Al, with impurities is cast by a water cooling continuous casting method. After that, this casting is preferably subjected to heat treatment of holding it at 400 to 550 deg.C for >=4 hr and thereafter executing cooling at a cooling rate slower than 200 deg.C/H and is furthermore machined according to necessary. In this way, the die stock of high quality occupied with fine crystalline grains having <=1mm grain size can be obtd. without executing rolling and forging.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new mold material for resin molding, press molding, etc. made of aluminum alloy. Specifically, the present invention aims to take advantage of the characteristics of aluminum alloys, such as light weight and good thermal conductivity, which have recently been in increasing demand, and to obtain large, complex-shaped, integrated molded products at low cost. It relates to mold materials for resin molding, press molding, etc.

0002

[Prior Art] Traditionally, as mold materials, steel, cast steel, etc. have been used for mass production, and zinc alloy casting materials, aluminum alloy casting materials, etc. have been used for prototyping. Due to the trend of increasing demand for aluminum alloys, rolled or forged aluminum alloy materials (hereinafter referred to as wrought materials) are becoming popular for use in small to medium-sized production. Among these, aluminum alloy casting materials are susceptible to internal defects such as pinholes, which impair the appearance and gloss of the molded product and extremely shorten the life of the mold, so improvements are desired.

On the other hand, among aluminum alloy casting materials, the aluminum-magnesium type has a wide solidification temperature range, so it has difficulties in castability and weldability, but it has excellent strength without heat treatment and has excellent machinability, polishability, and surface treatment properties. Because of its excellent properties, attempts are being made to improve castability, weldability, etc. by making it finer. For example, an aluminum-manganese-magnesium alloy containing beryllium, titanium, and boron for casting is disclosed in JP-A-57-207152.
There is also one published by Special Publication No. 62-45303. However, good molds cannot be manufactured using the casting alloy described in this publication as a raw material.

0004

[Problems to be Solved by the Invention] Mold materials made of aluminum alloy wrought materials are currently in widespread use, but they have drawbacks such as lack of large cross-sectional sizes and high costs. By the way, if the castability of the above aluminum-magnesium alloy casting materials is improved and internal defects are eliminated, and the structure (crystal grains) is controlled to make weldability and etching properties appropriate, these aluminum alloys can be easily expanded. It is expected that this material can be used as a mold material by improving its elasticity.

[0005] Therefore, using this alloy as a mold material, it is necessary for small to medium volume production to: - have no internal defects, have low residual stress, and have appropriate mechanical properties, machinability, and polishability. We investigated alloy components, casting methods, heat treatment methods, etc. that would satisfy the following requirements: Weldability and etching properties were appropriate.

[0006]

[Means for Solving the Problems] From the above points of view, the present inventors have conducted extensive studies on refinement treatment, water-cooled continuous casting method, and heat treatment of aluminum-magnesium alloys.
The present invention was achieved by discovering that sufficient properties as a mold material can be obtained without rolling or forging. That is, the present invention contains magnesium 2.0 to 7.0% and manganese 0.1 to 7.0%.
1.0%, beryllium 0.001-0.01%, titanium 0.003-0.15%, and boron ranging from a minimum of 0.001% to 20% with respect to titanium, with the remainder being substantially A mold material characterized by being made by casting an aluminum alloy consisting of impurities and aluminum by a water-cooled continuous casting method, and 2.0 to 7.0% magnesium.
, manganese 0.1~1.0%, beryllium 0.001~
0.01%, titanium 0.003-0.15%, minimum 0.01%.
Boron ranging from 0.001% to 20% relative to titanium, copper 0-2.0%, silicon 0-2.0%, iron 0-1.0%, zinc 0-5.0%, nickel 0-1 .0% and chromium 0~
The gist of the present invention is a mold material characterized in that it is made by casting an aluminum alloy containing 1.0% aluminum with the remainder consisting essentially of impurities and aluminum by a water-cooled continuous casting method.

The present invention will be explained in detail below. The mold material of the present invention is composed of an ingot made by the water-cooled continuous casting method described below. Among the aluminum alloys in the ingot, magnesium has mechanical properties and machinability and polishability that are essential for mold manufacturing. It contributes to improvement, but its content is 2.0
-7.0%, preferably 3.0-6.0%. If the amount of magnesium is less than this, the mechanical strength, machinability, and polishability will be poor, and if the amount of magnesium is more than this, the castability will be reduced and internal defects will be more likely to occur.

Manganese has good castability, mechanical properties, machinability,
Contributes to improving polishability, etc. Manganese content is 0.1~
It can be selected from a range of 1.0%, but preferably from a range of 0.2 to 0.6%. Beryllium has the effect of preventing magnesium from oxidizing and cleaning the molten metal when melting this alloy, helping to prevent internal defects and improve castability by refining the structure, and also improves weldability. Its content may be in the range of 0.001 to 0.01%, preferably 0.002 to 0.04%.

In addition, titanium and boron are added in a specific proportion to the aluminum alloy of the present invention for the purpose of refining the structure, eliminating internal defects and uniformly refining the structure, improving mechanical properties, machinability, and polishability. In addition to the properties, it improves the weldability necessary for overlaying and the etching property for creating patterns on the surface of the molded product. The titanium content varies depending on the solidification rate during continuous casting, but is 0.003 to 0.15%, preferably 0.003 to 0.15%.
It is necessary that the content be in the range of 0.005 to 0.10%, and if the content is too low, internal defects will occur, and the structure will not be sufficiently refined, resulting in poor mechanical properties, machinability, polishability, weldability, and etching. Deterioration of sex, etc. Furthermore, if the titanium content is too high, TiB2 will significantly settle in the molten metal due to its relationship with boron, which tends to cause problems in casting operations. Boron is present in a range from a minimum of 0.001 to 20% with respect to titanium. Boron ensures the effect of refining the crystals of titanium, but if it is contained in an amount greater than 20% relative to titanium, this effect is rather diminished. In addition, in order to prevent settling of TiB2 and ensure the refining effect, a certain proportion of titanium is added in the furnace, and the remaining amount is added with a wire of aluminum-titanium-boron mother alloy of a certain proportion between the furnace and the mold. It is preferable to add.

The essential components to be contained in the aluminum alloy of the present invention have been described above, but the alloy of the present invention may further contain other specific components within a range that does not impair its functions. That is, 0 to 2.0% copper and 0% silicon.
~2.0%, iron 0-1.0%, zinc 0-5.0%,
Nickel can be contained in the range of 0 to 1.0% either singly or in an appropriate combination of two or more. These metal components do not exhibit any special additional functions as shown in Examples 4 to 11 below, but as long as they are within the above range, they can sufficiently exhibit the effects of the present invention.

[0011] In addition, this alloy contains hydrogen gas and tends to generate inclusions such as aluminum and magnesium oxides, so in addition to adjusting these components, molten metal cleaning treatment such as degassing and removal of inclusions is necessary. In addition to inserting chlorine-based flux or gas into the furnace, degassing and removal of inclusions are performed using a ceramic filter between the furnace and the mold, and the process moves to a water-cooled continuous casting method.

The conventional sand casting method is a batch (discontinuous) casting method, in which solidification proceeds from the periphery and the solidification rate is slow, making it easy to create defects inside the ingot. In order to eliminate these problems, unidirectional solidification is desirable, and as an industrial method, water-cooled continuous casting is applicable, so we investigated the relationship between the above components, refinement treatment, and molten metal cleaning treatment for this casting method. We were able to obtain a defect-free ingot.

That is, in the water-cooled continuous casting method, the above-mentioned molten aluminum alloy is injected from the furnace through the launder into the distribution plate in an overflow method, and the height of the molten metal in the mold is adjusted to a constant level by using a float or the like. Meanwhile, the molten metal is injected at a constant flow rate through a pipe attached to a distribution board into a mold that has a base metal at the bottom and is also equipped with a screen to prevent inclusions. The injected molten metal contacts the wall of the mold, which is forcibly cooled by cooling water, and forms a thin solidified shell from the contact area toward the inside of the molten metal, and is continuously drawn downward by the lowering of the bottom metal. This method completely solidifies the molten metal by injecting cooling water directly into the solidified shell, making it easy to obtain a large cross-sectional size, and also making it possible to produce multiple ingots at the same time.

[0014] The above alloy components, refinement treatment, molten metal cleaning treatment, and casting method eliminate internal defects such as pinholes and inclusions, but in this casting method, the temperature of the ingot skin and center part is different, Due to the difference in the amount of solidification shrinkage, the larger the cross-sectional size of the ingot, the more stress remains, and if left as it is, it will cause deformation during mold cutting. To remove this stress, 4
4 hours or more, preferably 6 hours at a temperature of 00 to 500 °C
A heat treatment is performed by soaking for ~10 hours and then gradually cooling at a rate of 200°C/H, preferably slower than 50°C/H. If the soaking temperature is lower than 400°C and for less than 4 hours, stress relief will not be sufficient, and if the cooling rate is fast, residual stress will occur due to heat treatment, which is disadvantageous.

[0015] The heat treatment of these ingots also helps to homogenize the cast structure, improving mechanical properties, machinability, and polishability. The ingot produced as described above is then cut to the required size and subjected to face milling to obtain a mold material. The mold material manufactured by heat treatment has no internal defects, has a small crystal grain size, and has appropriate mechanical properties, so it has the machinability, polishability, and
It satisfies weldability, etching properties, etc.

[0016] Furthermore, the present mold material has excellent corrosion resistance and surface treatment properties, and also has features such as no need for rust preventive oil for the mold and easy surface hardening treatment such as hard alumite.

[0017]

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Examples 1 to 3 Cross-sectional size (single piece) 150 mm x 300 mm, casting temperature 720°C, descending speed 45 mm/min, cooling water amount 20 m
Continuous casting was performed over a length of 150 mm at 3/H to obtain mold materials shown in Table 1 below, with and without heat treatment. In addition, a comparison was made with conventional aluminum alloy wrought materials and aluminum alloy cast materials listed in Table 1. Table 2 below shows the results of comparisons regarding items (1) to (8) below. (1) The internal defect is 10mm x 10m at the center of the cross section.
m was examined under a microscope at 10 times magnification, and the number of defects larger than 0.1 mm was counted. Defects were observed in the cast material (especially AC7A), but were not observed in the mold material of the present invention and the wrought material. (2) The crystal grain size was measured using the same speculum plane as in (1) with 10 times magnification. The mold material of the present invention had much finer grains than the casting material. (3) Mechanical properties were measured using JIS No. 4 tensile test pieces,
The tensile properties were measured according to SZ2241, and the hardness of the chuck portion after this tensile test was measured according to JISZ2243. The mold material of the present invention was superior to casting materials and was better than wrought material A5083. (4) Cutting performance is 30mm diameter, 2-flute eredomiru,
Rotation speed 3500 rpm, cutting depth 35 mm x 30 mm,
Evaluation was made from the shape of chips and surface roughness of the surface cut at a feed rate of 1000 m/min. The mold material of the present invention had the second best performance after wrought material A7075. (5) Polishability was measured by processing a cut surface of 50 mm x 50 mm to 15 μm with an end mill, finishing with #400 and #600 paper, lapping with chromium oxide and diamond paste, and comparing the surface conditions. This mold material was superior to cast material and second only to wrought material A7075. (6) Weldability was measured by groove processing a 200 mm part of a plate-shaped sample, using a filler rod A5356WY-1.6 mmφ, and
IG welding machine (conditions: current 300A, voltage 30V, welding speed 350mm/min, argon feed rate 25 liters/min)
Garment welding was performed at , and the welded part was observed using X-ray transmission. Casting materials 7A, 4C and A70
In No. 75, the structure was coarse and blowholes were observed in the welded part, whereas in No. 75, the mold material of the present invention and the wrought material (A
5083), no defects were observed in the welds. (7
) Etching properties were compared by photo-etching to compare the degree of protrusion of 0.3 mm x 0.3 mm lattice ribs at 3 mm intervals on a 100 mm x 100 mm plate.
However, while the cast material did not have sufficient shape, the mold material of the present invention was similar to a wrought material and could be used. (8) Residual stress is 300mm width x 700mm length x 1
00mm thick, 30mm x 30mm in the center of the longitudinal and lateral directions
A 70 mm groove was dug and the amount of deformation on the opposite side was measured, and it was confirmed that the mold material of the present invention had minimal deformation. Examples 4 to 11 Each alloy shown in Table 3 below was subjected to water-cooled continuous casting under the conditions shown in Table 4 below, and heated and cooled under each heat treatment condition shown in Table 3 to obtain a mold material. After cutting and polishing this material, Table 5 is shown below.
When the mold material of the present invention was evaluated using the injection molding method under the following conditions, it was found that the mold material of the present invention has better quality and durability than an aluminum alloy casting material, and is a material close to a wrought aluminum alloy material. The comparison results are shown in Table 6 below.

[0018]

Effect of the invention: The mold material according to the present invention fully exhibits the advantages of aluminum alloy such as light weight and good thermal conductivity, and is a large and inexpensive material, so it is suitable for resin molding and press molds and jigs. It can be used widely. Among these, it is suitable for large-sized molds with relatively low molding pressure, molds for resin foaming, casting, hollow molds, and rim molding, which are expected to grow significantly in the future.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

[0024]

[Table 6]

Claims (6)

[Claims] Claim 1: Magnesium 2.0-7.0%, manganese 0.1-1.0%, beryllium 0.001-0.0
1%, titanium 0.003-0.15%, and a minimum of 0.0
A mold material characterized in that it is made by casting an aluminum alloy containing boron in a range of 0.01% to 20% based on titanium, with the remainder consisting essentially of impurities and aluminum, using a water-cooled continuous casting method. Claim 2: Magnesium 2.0-7.0%, manganese 0.1-1.0%, beryllium 0.001-0.0
1%, titanium 0.003-0.15%, minimum 0.001
Boron ranging from % to 20% with respect to titanium, copper 0-2
．． 0%, silicon 0-2.0%, iron 0-1.0%, zinc 0-2.0%
5.0%, nickel 0-1.0% and chromium 0-1.0
%, with the remainder essentially consisting of impurities and aluminum, which is cast by a water-cooled continuous casting method. 3. A mold material obtained by casting the aluminum alloy according to claim 1 or 2 by a water-cooled continuous casting method and then subjecting it to heat treatment. 4. After casting the aluminum alloy according to claim 1 or 2 by a water-cooled continuous casting method,
A mold material characterized by being heat-treated by holding it at 50°C for 4 hours or more and then cooling it at a cooling rate slower than 200°C/H. 5. A mold material obtained by casting the aluminum alloy according to claim 1 or 2 by a water-cooled continuous casting method, and characterized in that the aluminum alloy is occupied by granular crystals with a crystal grain size of 1 mm or less. . 6. A mold, characterized in that it is formed by cutting a mold material obtained by casting the aluminum alloy according to claim 1 or 2 by a water-cooled continuous casting method.