JPS6281257A - Die casting device - Google Patents

Abstract

PURPOSE:To form an intricate flow in a mixing cavity and to permit thorough mixing of an additive and molten metal by limiting the sectional area of a gate communicating with a molding cavity and mixing cavity with respect to the sectional area of a gate communicating the mixing cavity and injection sleeve. CONSTITUTION:The molten metal injected from the injection sleeve 14 of a die casting machine having the mixing cavity 5 flows through the 2nd gate 7 into the mixing cavity 5. The molten metal is mixed with the additive 23 in the mixing cavity. The 1st gate 4 communicating the mixing cavity 5 and the molding cavity 3 is formed to 5/6-1/5 the sectional area of the 2nd gate 7 communicating the mixing cavity 5 and the injection sleeve 14 and therefore, the molten metal admitted into the cavity 5 from the injection sleeve 14 is pressurized again to form the intricate flow. The additive 23 and the molten metal are thoroughly mixed so that the generation of the ununiform dispersion of the additive 23 and the insufficient wetting of the additive 23 and the metal is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a die-casting device, and is particularly effective when used in a method of molding metal-based composite materials by die-casting.

[Conventional technology]

Conventionally, high-pressure solidification casting has been studied as a manufacturing method for producing metal-based composite materials, but this method requires a preheating process for additives and a process for impregnating the base metal with the additives.

Therefore, this conventional method has problems in that productivity is poor due to the provision of preforming and compounding steps for additives, and as a result, the cost of the product is also high.

On the other hand, JP-A-60-18262 discloses that a die-casting method is used, and the large stirring energy of the injected molten metal obtained in the die-casting process is used to mix the molten metal as an additive. A method is disclosed in which, in order to achieve the above method, a molded product cavity, a mixing cavity, and a gate communicating between both cavities are formed between a movable mold and a fixed mold, and a gate is formed between a movable mold and a fixed mold, and a gate is formed in a region closer to the injection sleeve than the mixing cavity. Die casting 'AM' is known which is provided with means for fixing additives.

[Problem that the invention seeks to solve]

However, according to the experimental research conducted by the present inventors, in the apparatus disclosed in the above publication, depending on the conditions for injecting the molten metal from the injection sleeve into the mold, the additive may be unevenly dispersed or the additive may be mixed. It has been found that there is a problem that insufficient wetting with the metal tends to occur, resulting in insufficient strength of the composite metal material after molding, and non-uniformity in properties such as coefficient of thermal expansion and abrasion resistance. It has become clear that this problem is particularly likely to occur when the additive is in a fibrous form, and is a particular problem when manufacturing fiber-reinforced composite metals using the above-mentioned die-casting method.

[Means for solving problems]

Therefore, in order to solve the above-mentioned problems, the present invention provides a first
The cross-sectional area of the gate is 576 to 1/ of the cross-sectional area of the second gate communicating the mixing cavity and the injection sleeve.
A die-casting device of No. 5 is adopted.

[Effect]

According to the above means, the molten metal injected from the injection sleeve flows into the mixing cavity via the second gate and is mixed with the additive in the mixing cavity. At this time, the first gate that communicates the mixing cavity with the molded product cavity has a cross-sectional area of 5/6 to 1/5 that of the second gate, so that the injection is performed within the mixing cavity. The molten metal flowing from the sleeve is repressurized and sufficient mixing of the additive and molten metal occurs to form a complex flow within this mixing cavity, eliminating uneven dispersion of the additive and mixing of the additive and the metal. No lack of wetting occurs.

〔Effect of the invention〕

Therefore, according to the present invention, since the additive material has good wettability and is uniformly dispersed in the metal, the strength is high and the coefficient of thermal expansion is low.
This has the excellent effect that a composite metal material with uniform properties such as wear resistance can be obtained.

〔Example〕

FIG. 1 shows a die-casting apparatus of the present invention, and in the figure, reference numeral 28 denotes a fixed base, which is fixed to a factory floor or the like using embedded bolts. Reference numeral 17 designates fixed platens fixed to this base 28, and although only one is shown in the figure, a pair of fixed platens are provided at opposing positions. And a pair of fixed platens 1
A dieper 18 is placed between the two, and a movable platen 21 is slidably disposed on the dieper 18.

Therefore, the movable platen 21 slides between the pair of fixed platens 17 under the driving force of a hydraulic piston (not shown).
(Illustrated by arrow).

9 is a fixed block fixed to the fixed platen 17; 10
is a fixed insert disposed within the holding groove 9a of this fixed block 9. Then, this fixed block 9 and fixed insert 1
0 forms a fixed mold 29.

20 is a die base fixed to a movable platen 21, 12
1 is a movable block fixed to this gouey base, and 1/ is a movable insert disposed within the holding groove 12a of this movable block 12. A movable mold 30 is formed by each of the above members 20.12.1/. Note that both the fixed insert 10 and the movable insert 1/ are molded from hot work tool steel (SKD61).

When the movable mold 30 is in contact with the fixed mold 29, a molded product cavity 3, a mixing cavity 5, and a first cavity 3.5 are formed between the movable insert 1/ and the fixed insert 10, and a first cavity 3. Gate 4, runner 8, and second gate 7 connecting runner 8 and mixing cavity 5 and having a smaller cross-sectional area than runner 8 are formed. Here, in the present invention, the runner 8 is understood to be a part of the injection sleeve 14 described later. Note that an overflow cavity 1 is formed in the upper part of the molded product cavity 3. Reference numeral 2 denotes an overflow gate that connects the overflow cavity 1 and the product section 3a of the product cavity 3.

FIG. 2 shows the front shape of the movable insert 1/ of this mold part 30, but as shown in the figure, in this embodiment, two molded product cavities 3
The first gate 4 opens at a position not directly facing the second gate 7.

Further, the volume V of the molded product cavity 3 is smaller than the volume ■2 of the mixing cavity, and in this example, V2=2.0VI
It becomes. Here, in this example, ■ is the sum of the three volumes of the two molded product cavities.

Further, the cross-sectional area ratio between the second gate 7 and the first gate 4 is 273 for the latter. Here, the cross-sectional area is the cross-sectional area in the direction perpendicular to the direction in which the molten metal flows. and the first
The cross-sectional area of the gate 4 is the sum of the cross-sectional areas of the two gates. Further, the mixing cavity 5 has a cylindrical shape,
After molding, the molding material in the mixing cavity mixed with additives can be easily used for extrusion molded products and the like.

As shown in FIG. 2, an extrusion pin 13 is disposed in the movable mold 30 at a position facing the overflow cavity 1, the molded product cavity 3, and the mixing cavity 5. This push-out bottle 13 is connected to the push-out plate 19.
Further, the push-out plate 19 is moved back and forth in the left-right direction in the figure (as shown by arrow U) by the push-out plunger 22. The push-out plunger 22 is driven by a hydraulic piston (not shown).

In FIG. 1, reference numeral 14 denotes an injection sleeve communicating with the runner 8, and an injection plunger 16 is slidably disposed within the injection sleeve 14. Note that the injection plunger 16 is moved in the left-right direction in the figure (as shown by arrow I) by a hydraulic piston (not shown). Reference numeral 15 denotes a hot water supply port that opens into the injection sleeve 14, and a metal in a molten state, in this example, aluminum-copper-silicon alloy (ADC12) is used from this hot water supply port 15.

Next, a die-casting method using the above-mentioned block diagram apparatus will be explained. First, the movable mold 30 is separated from the fixed mold 29 by the driving force of a hydraulic piston (not shown), and in this state, a mold release agent is applied to the surfaces of the molded product cavity 3 and the mixing cavity 5. Also, at this time, a preformed body 23 of silicon carbide whiskers as an additive is placed in the mixing cavity 5,
Next, the movable platen 21 is moved by the driving force of the hydraulic piston.
is displaced, the movable mold 30 comes into contact with the fixed mold 29, and both molds 29
．． A molded product cavity 3 and a mixing cavity 5 are formed between 30 and 30.

Here, the silicon carbide whisker preform is pressure-formed without using a binder so that it is well dispersed in the molten metal during injection of the molten metal, and the pressing force depends on the filling ratio of the additive material. Although it is different, it is easily destroyed when it collides with the injected molten metal, and is molded with enough strength to maintain its shape during normal handling such as transportation.

Note that the preformed body 23 accounts for 2 to 15 vol % of the volume of the mixing cavity 5 and the molded product cavity 3.

In this state, an aluminum alloy (ADC12) heated to 630° C. to 700° C. and molten is poured into the hot water supply port 15. Then, the injection plunger is displaced by a hydraulic piston (not shown), and the molten metal is injected toward the runner 8 through the injection sleeve 14 (as shown by arrow T). At this time, the injection speed is initially set at a relatively low speed so that the air in the molded product cavity 3 can easily escape to the overflow cavity 1 side. When the injection plunger 16 advances until just before the molten metal enters the mixing cavity 5, the injection plunger 16 advances at high speed.

The second gate 7 narrows the hot water supply flow path, and as a result, the molten metal collides with the preform 23 placed in the mixing cavity 5 at a high speed of 30 to 70 m/s. The preformed body 23 is destroyed by the energy and stirred by the molten metal. This molten metal is then injected into the molded product cavity 3 through the first gate 4. In the die casting apparatus of the present invention, the cross-sectional area of the first gate 4 is larger than the cross-sectional area of the second gate 7. 273, the injected molten metal is repressurized within the mixing cavity 5 and its flow is complicatedly disturbed. For this reason, the whiskers are mixed sufficiently uniformly, and the silicon carbide whiskers and the aluminum alloy are bonded with good wettability by this repressurization. This effect becomes larger as the cross-sectional area of the gate 4 is smaller than that of the mixing gate 7, but generally in this type of die-casting method, the temperature of the mold is set much lower than the melting point of the metal to be injected, so If the cross-sectional area ratio of the first gate 4 and the second gate 7 is too large, the injection will take a long time and the gates are likely to be clogged, so the lower limit of the ratio is preferably about 175.

Then, in this state, it is injected into the molded product cavity 3 from the gate. At this time, the air remaining in the molded product cavity 3 is forced out by the molten metal, and is pushed out together with the molten metal toward the overflow cavity 1 (as shown by arrow A).
.

In particular, in this example, since the melting volume 2 of the mixing cavity 5 is larger than the volume v1 of the molded product cavity 3,
Even when the molded product cavity 3 is completely filled with molten metal, a portion of the molten metal mixed with whiskers still remains in the mixing cavity 5. Therefore, a situation in which molten metal consisting only of aluminum alloy without being mixed with whiskers flows into the molded product cavity 3 through the first gate 4 does not occur. In other words, all of the molten metal in the molded product cavity 3 is molten metal mixed with whiskers.

The molded material solidified in the mixing cavity 5 has a whisker-containing composition that is approximately the same as that in the molded product cavity 3. Conventionally, even if this part is remelted, the additive material and the metal are often not completely wetted, and the additive material is unevenly distributed, so it has been difficult to reuse it. Therefore, in the present invention, the shape of the mixing cavity 5 is made into a cylindrical shape, so that the formed material formed in the mixing cavity 5 can be effectively used as a raw material for secondary processing such as forging and extrusion. has been done.

In addition, the volume ■2 of the mixing cavity 5 is the volume of the molded product cavity 3.
The volume is preferably 1.5 to 2.0 times the volume of ■1.The reason is that if it is less than 1.5 times, the molten metal (molten metal in the runner 8) will not be sufficiently mixed with the whiskers in the mixing cavity 5.
This is because there is a possibility that the liquid may flow into the molded product cavity 3. On the other hand, if it is set to 2.0 times, the volume of the mixing cavity 5 becomes too large and the molten metal cannot be used effectively.

After the cavities 1, 3.5 are filled with molten metal in this manner, the state is maintained at high pressure for a while to solidify the metal in the cavities 1, 3.5. After the metal solidifies, the movable platen 21 is driven by a hydraulic piston (not shown) to separate the movable mold 30 from the fixed mold 29. Next, the extrusion plate is advanced by a hydraulic piston (not shown), and the solidified metal is extruded from the cavity 1.3.5 by the extrusion pin 13. The extruded metal is gripped by a gripping device (not shown) and taken out from the mold 29, 30.

The metal taken out from the molds 29 and 30 is cut at the overflow gate 2 and the first gate 4, and only the molded material in the molded product cavity 3 is taken out.

The silicon carbide whisker-reinforced aluminum manufactured by the above method had, for example, a volume content Vf of silicon carbide whiskers as an additive material of 15% and a bending strength of 55 kg/am. A similarly manufactured one with the same cross-sectional area of the gate 7 of No. 2 weighed 50 kg/dragon, and an improvement in strength of about lθ% was achieved.

According to the invention, basically all types of fibers and fine particles can be used as additives. Therefore, other metal oxides, inorganic particles, inorganic fibers, metal fibers, glass fibers, carbon fibers, whiskers, and combinations thereof may be used in addition to silicon carbide whiskers.

In particular, in the case of fibrous additives, those having a length of about 50 to 200 μm and a diameter of about 0.1 to 10 μm are effective, and the volume content in the composite material can be suitably manufactured at a Vf of 2 to 15%. In addition, as for the metal material, a. Also, in the above embodiment, the molded product cavity 3 was composed of two, but it may be one, three or more, and in that case, the first gate 4 is , and the cross-sectional area is the sum of all of them. The same applies to the mixing cavity 5 and the second gate 7.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a die-casting apparatus used in the present invention, and FIG. 2 is a front view showing a cavity portion shown in FIG. 1. 3... Molded product cavity, 4... First gate, 5
...Mixing cavity, 7...Second gate, 14.
... Injection sleeve, 21... Preformed body.

Claims (1)

[Claims] Disposed between the injection sleeve and the molded product cavity, the additive material to be dispersed in the metal is stored, and when the molten metal is injected,
In a die casting device having a mixing cavity for mixing the molten metal and the additive material, the cross-sectional area of the first gate communicating the molded product cavity and the mixing cavity is the same as the cross-sectional area of the first gate communicating the mixing cavity and the injection sleeve. 5/6 to 5/6 of the cross-sectional area of gate 2
A die-casting device characterized by being 1/5.