JPH0318980B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a die-casting method, and is effective for use in die-casting made of aluminum alloy, for example, and is not particularly limited in use, but the present invention relates to a die-casting method. Die-cast products can be used for distributor housings, etc.

[Process of establishment of the present invention]

The conventional die-casting method is performed according to the procedure shown in FIG. That is, with the movable mold open from the fixed mold, apply a chip lubricant to the inside of the radiant sleeve, then spray a mold release agent onto both the fixed mold and the movable mold, and then bring the movable mold into contact with the fixed mold. Next, the injection sleeve is filled with molten metal, the molten metal is injected into the mold space by an injection plunger, and after the molten metal solidifies in the mold space, the movable mold is separated from the fixed mold to release the solidified product. This was done in the process of taking it out.

That is, in the conventional die-casting method, it is a given that a release agent is sprayed onto the surface of the mold so that the solidified product can be smoothly removed from the surface of the mold. However, as the shape of the product becomes more complex and the shape of the mold becomes more complex, the number of locations and amount of spraying of this mold release agent increases, and as a result, the time required for spraying the mold release agent increases. It will end up being put away. The increased time required for spraying the mold release agent not only reduces the number of die casts per unit time and lowers productivity, but also has a significant impact on the quality of die cast products, as explained below. will give.

In other words, the conventional spraying of mold release agent uses multiple nozzles to simultaneously spray the mold release agent onto the mold surface, so if there is even one spot that requires long spraying, the time required to spray the mold release agent can be reduced. becomes the total mold release agent spraying time. Therefore, in areas where there is no need to spray mold release agent for a long time, the mold release agent may be sprayed excessively, resulting in a drop in mold surface temperature and more mold release agent adhering than necessary. Become. In addition, excessively lowering the mold surface temperature locally in this way leads to a decrease in productivity and quality of the die-cast product.

As such, spraying a mold release agent itself causes a deterioration in the quality of die-cast products, but in the conventional die-casting method, this mold release agent is always used to take out the solidified product from the mold. The spraying was taken for granted.

For example, Japanese Patent Application Laid-Open No. 48-55122, Jikkosho
49-11298, some die-casting machines only describe a chip lubricant and do not specifically disclose a mold release agent, but all of the die-casting machines described in these publications are based on the premise that release agents are not particularly disclosed. The molding agent is sprayed onto the mold surface.
Based on this premise, an attempt was made to improve the lubricity of the chip lubricant.

Note that in the conventional die casting method shown in Fig. 1, the mold release agent is supplied with the mold open, but in the conventional technology, the mold release agent is supplied with the mold closed. It was also known that For example, in the die casting method described in U.S. Pat. No. 1049178, U.S. Pat. No. 3,645,319, and U.S. Pat. Ta.

However, no matter which die casting method is used, die casting is always performed on the assumption that a release agent is sprayed as a matter of course, as described above.

In such a process, the present inventors have noticed that the chip lubricant has a large effect on the mold release force when extruding the solidified product from the movable die. This tip lubricant is mainly used to facilitate sliding between the injection sleeve and the injection plunger within the injection sleeve, but this tip lubricant is used between the fixed mold and the solidified product and between the movable mold and the injection plunger. The present inventors have focused on the fact that it also has the effect of relaxing the bonding force with the solidified product.

Figure 2 is a graph showing the results of an experiment conducted by the present inventors.As is clear from this figure, when the application of chip lubricant is stopped, the mold release force increases as the number of times increases, resulting in die casting. After repeating the process five times, it was finally confirmed that the solidified product did not come out of the mold space.

As described above, the chip lubricant has a large effect on the mold release force, but the inventors conducted various studies on the mold release force effect of this chip lubricant, and found that After that, it was recognized that the time it takes for the movable mold to come into contact with the fixed mold has a great influence on the above-mentioned mold release force effect.

The results of experiments conducted by the inventors regarding this matter are shown in FIG. In FIG. 3, the horizontal axis shows the time from application of the tip lubricant to the supply of molten metal into the injection sleeve, and the vertical axis shows the force required to separate the movable mold from the fixed mold. As is clear from this figure, there is a tendency that the shorter the above-mentioned time is, the smaller the mold release force is, and the mold release force becomes larger as time passes.

The experiments shown in FIGS. 2 and 3 were both carried out using a die casting method that did not involve spraying a mold release agent. The tip lubricant is applied by blowing the tip lubricant together with high pressure air into the injection plunger.

The results of the study conducted by the present inventors regarding the experimental results shown in FIG. 3 above are shown below. As shown in FIG. 4, in order to spray the chip lubricant into the injection sleeve 1 together with high-pressure air, and because the inside of the injection sleeve 1 has been sufficiently heated by filling the molten metal in the previous process,
This is thought to be because the tip lubricant in the injection sleeve 1 flows out from the open end 1a of the fixed mold 6.

[Purpose of the invention]

The present invention was devised based on the results of experiments conducted by the present inventors, and focuses on the effect of chip lubricant on reducing mold release force, and eliminates the need for spraying mold release agent, which was conventionally required. The purpose is to enable the die-casting method to be smoothly and continuously achieved while abolishing it.

[Structure of the invention]

In order to achieve the above object, in the present invention, the movable die is brought into contact with the fixed die as early as possible after the tip lubricant is applied.

In other words, in the conventional die casting method, after spraying chip lubricant, a mold release agent was further sprayed onto the movable mold and the fixed mold, and then the movable mold was brought into contact with the fixed mold, but in the method of the present invention, the conventional die casting method The new model adopts a structure that eliminates the mold release agent spraying process. Therefore, according to the present invention, the time required for spraying the mold release agent is shortened. The mold release agent spraying time varies depending on the size of the mold space, but the average time is 10
It takes about seconds, and the time after application of the separation agent is shortened.

〔Example〕

FIG. 5 shows an example of a die-casting apparatus used in the method of the present invention.

2 in the figure is a fixed base, which is fixed to the factory floor with embedded bolts (not shown) or the like. Reference numeral 3 denotes fixed platens fixed to this fixed base, and although only one is shown in the figure, a pair of fixed platens are provided at opposing positions. A movable platen 4 is disposed between the pair of fixed platens and reciprocates along the tie bar 5 by the driving force of a hydraulic piston (not shown).

6 is a fixed mold fixed to the fixed platen 3; 7 is a movable mold fixed to the movable platen 4;
A mold space 8 is formed between the molds 6 and 7 by the contact between the molds 6 and the movable mold 7. A push-out pin 9 is slidably disposed within the mold space 7 and is used to push out the solidified product solidified within the mold space 8 from the mold space 8. Reference numeral 10 denotes a push-out plate that drives the push-out pin 9, and it reciprocates in response to the driving force of a hydraulic piston (not shown).

An injection sleeve 1 is disposed in the fixed mold 6, and an injection plunger 1 is disposed inside the injection sleeve 1.
1 is fitted. And injection plunger 11
is reciprocated by the driving force of a hydraulic piston (not shown). Reference numeral 1b denotes an injection port opened on the upper surface of the injection sleeve, through which molten aluminum alloy is injected into the injection sleeve 1. Reference numeral 12 denotes a carrying device for carrying this molten metal.

A spray nozzle 13 for spraying chip lubricant is opened in the injection port 1b. High-pressure air of 4 to 5 kg/cm ² is supplied to this blow nozzle 13, and the chip lubricant is engulfed in this high-pressure air. That is, the chip lubricant 14 in the lubricant tank 13 is pumped up to the air passage 16 by the pump 15, where it is engulfed by high-pressure air and sprayed into the injection sleeve 1 from the spray nozzle 13. Note that there are two types of chip lubricants: oil-based and water-soluble.In this example, we used an oil-based chip lubricant that has a large effect of reducing mold release force, such as a mixed vegetable oil of oleic acid and linolenic acid. are doing.

Next, an example of a die casting method using the above device will be explained. First, tip lubricant is supplied into the injection sleeve 1 with the movable mold 7 separated from the fixed mold 6 as shown in FIG. At this time, the amount of lubricant supplied is
It is about 1.5cc to 2.5cc. Next, the movable platen 4 is driven, the movable mold 7 is brought into contact with the fixed mold 6, and a mold space 8 is formed. In this example, since this process is performed in about 2.7 seconds, the lubricant inside the injection sleeve 1 will not be scattered unnecessarily. After that, loading device 1
2, the molten metal is supplied into the injection sleeve 1. At this time, the lubricant in the injection sleeve 1 comes into contact with the molten metal, and about half of the lubricant evaporates due to the heat of the molten metal. Note that this hot water supply time is approximately 5 seconds in this example.

Next, the injection plunger 11 is advanced at a relatively low speed (0.2 m/sec) until the mold space 8 is filled with the molten metal, as shown in FIG. Prevent getting caught in the molten metal. As shown in Figure 7, after the molten metal reaches the mold space 8, it moves at a relatively high speed (1.3m/
sec) to advance the injection plunger. and,
The pressure of the injection plunger maintains the molten metal in the mold space at a high pressure of approximately 1260 kg/cm ² .

At this time, according to the inventors' considerations, before the molten metal advances, the atomized tip lubricant flows into the mold space 8 due to the energy during spraying, and as a result, the tip lubricant is preliminarily distributed between the fixed mold 6 and the mold space 8. The molten metal adheres to the inner surface of the movable mold 7, and then the molten metal is transferred to the fixed mold 6 and the movable mold 7.
It is considered to be in contact with Alternatively, it is considered that mist and liquid chip lubricant are blown into the mold space 8 by energy during injection of the molten metal.

After the tip lubricant 14 and the molten metal are injected in this manner, this state is maintained for a while to solidify the molten metal within the mold space 8. According to this example, the time from injection to solidification is approximately 0.5 seconds. Next, the movable platen 4 is moved to separate the movable mold 7 from the fixed mold 6, and the extrusion plate 10 is also moved to push the solidified product away from the movable mold 7 using the extrusion pins 9. According to this example, it takes about 3.2 seconds to displace the movable mold, and about 9.6 seconds to move the push-out pin 9. In this way, one cycle of the die casting method of this example is completed (as shown in FIG. 8).

Note that FIG. 9 shows an example of the solidified product, and the solidified product of this example is used as a housing for an automobile distributor. Further, in the solidified product of this example, the wall thickness t of the main portion is relatively thin (about 1.5 mm). According to the experimental study by the inventors, this wall thickness t
It was confirmed that the mold release force at the time of opening the mold is affected, and that the thinner the wall thickness t, the smaller the mold release force is required. Therefore, when the wall thickness t of the solidified product is small, the amount of tip lubricant used is small, and on the other hand, when the wall thickness t is thick, it is necessary to use a large amount of tip lubricant.

In addition, in the above example, the chip lubricant is injected into the injection port 1b.
Although it is injected into the injection sleeve 1, it may alternatively be applied onto the injection plunger 11.
Further, in the above example, the tip lubricant was blown into the injection sleeve 1 together with high-pressure air, but the liquid tip lubricant may simply be dripped into the injection sleeve 1 by gravity.

〔Effect of the invention〕

As explained above, in the method of the present invention, after applying the chip lubricant, the movable mold is brought into contact with the fixed mold immediately without spraying the mold release agent, so that a mold space is formed after the chip lubricant is applied. The time it takes to do so can be significantly reduced. Therefore, the mold release force reduction effect of the chip lubricant can be brought out most effectively, and even though mold release agent spraying has been abolished, the movable mold can be easily separated from the fixed mold, and the solidified product can be moved. It can be extruded from a mold.

In particular, by eliminating the mold release agent spraying process, the cycle time of the die casting method can be shortened.
A large number of die casting processes can be performed per unit time. In addition, it is possible to prevent hot water wrinkles and hot water spots in the solidified product due to spraying of the mold release agent.

The effect of preventing hot water wrinkles and hot water stains will be explained next. In the case where a mold release agent is applied to the movable mold 7 and the fixed mold 6, the surfaces of the molds 6 and 7 are cooled by the mold release agent, and as a result, when the molten metal comes into contact with the molds 6 and 7, a solidified layer is formed on the surface. It is thought that the formation of a coagulated layer causes hot water wrinkles to appear on the surface of the coagulated product. Furthermore, when the mold release agent comes into contact with high-temperature molten metal, the mold release agent thermally decomposes, becomes gaseous, and gets caught up in the molten metal, causing blowholes to occur in the molten metal. Furthermore, the gas of the thermally decomposed mold release agent obstructs the flow of the molten metal, resulting in a decrease in the fluidity of the molten metal within the mold space, and a molten metal boundary is generated at the portion where the molten metal collides within the mold space 8. it is conceivable that.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the cycle time of the conventional die casting method, Figure 2 is an explanatory diagram showing the relationship between mold release force and chip lubricant, and Figure 3 is a diagram showing the relationship between mold release force and chip lubricant application. Explanatory diagram showing the relationship between
The figure is a cross-sectional view showing the chip lubricant application state, FIG. 5 is a cross-sectional view showing an example of the die casting apparatus used in the method of the present invention, FIGS. The figure is an explanatory diagram showing the die casting cycle time of this example, and FIG. 9 is a sectional view showing an example of a solidified product. DESCRIPTION OF SYMBOLS 1... Injection sleeve, 6... Fixed mold, 7... Movable mold, 8... Mold space, 9... Extrusion pin, 11
...Injection sleeve.

Claims (1)

[Claims] 1. A fixed mold, a movable mold that comes into contact with the fixed mold to form a mold space, an injection sleeve whose one end is open in the mold space and which guides molten metal into the mold space, and the mold space. a first step of supplying chip lubricant from a molten metal inlet formed in the injection sleeve using an extrusion pin that pushes out a solidified product; and immediately after the first step, bringing the movable mold into contact with the fixed mold. a second step of forming a mold space through the injection sleeve to prevent the chip lubricant supplied to the injection sleeve from leaking out of the mold space; a third step of supplying the molten metal into the injection sleeve from the molten metal inlet; a fourth step of injecting the molten metal in the injection sleeve into the mold space side with an injection plunger and transporting the lubricant and the molten metal to the mold space side so that the lubricant reaches the mold space side before the molten metal; A die-casting method in which a fifth step of solidifying the molten metal in the mold space, and a sixth step of separating the movable mold from the fixed mold and pushing out the solidified product in the mold space from the mold space are carried out in chronological order. 2. The die-casting method according to claim 1, wherein the first step is carried out by spraying a chip lubricant together with high-pressure air into the injection sleeve. 3. The first step is performed by dropping a chip lubricant into the sleeve.
Die casting method described in section.