JPH0225699B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a die-casting method and a die-casting device, and is effective for use in die-casting made of aluminum alloy, for example. Die-cast products produced by the method and apparatus of the invention can be used for distributor housings and the like.

[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 into the injection 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.

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 mold. 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 7 is a graph showing the results of an experiment conducted by the present inventors.As is clear from this graph, when the application of chip lubricant is stopped, the release force increases with increasing number of times, and die casting After repeating the process five times, it was finally confirmed that the solidified product could no longer be removed from the mold space.

As described above, the chip lubricant has a large effect on the mold release force, but when the present inventors conducted various studies on the mold release force effect of this chip lubricant, they 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. 8, 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. 7 and 8 were both carried out using a die casting method that did not involve spraying a mold release agent. The application of the tip lubricant was carried out by blowing the tip lubricant together with high pressure air into the injection plunger.

Based on the above study results, the present inventors previously filed an application for a method of die casting using the mold release force of a chip lubricant without spraying a special mold release agent. (Patent Application No. 58-159382) However, in the previous application by the present inventors, the main focus was simply on eliminating the mold release agent, so the chip lubricant was used to achieve the mold release effect. It did not stipulate specific measures to be taken to achieve this. That is, the tip lubricant is sprayed onto the injection sleeve from an injection port opened in the injection sleeve as in the past.

[Purpose of the invention]

The present invention is based on the development process described above, and aims to further advance the invention described in the earlier application by the present inventors, and to make the mold release force reducing effect of the chip lubricant most effective. do. Specifically, the purpose is to ensure that the lubricant serves as a chip lubricant to ensure good lubrication of the injection sleeve, and also to be well guided into the mold space to exhibit the effect of reducing mold release force.

[Structure of the invention]

In order to achieve the above object, in the die casting method of the first aspect of the present invention, the timing for spraying the lubricant is specified to be the optimum timing. That is, in the first invention, after the movable mold is brought into contact with the fixed mold to form a mold space, the lubricant is injected from the nozzle toward a portion closer to the injection sleeve than the mold space.

In the die-casting method of the second aspect of the present invention, in order to achieve the above object, positional conditions for injecting the lubricant are specified. That is, in the second invention, the lubricant is injected from a position connecting the injection sleeve and the mold space.

The die-casting device of the third aspect of the present invention aims to provide a die-casting device that can achieve the above method, especially the method of the second aspect, by opening a chip lubricant injection nozzle in a region connecting the injection plunger and the mold space. , and the nozzle blows out in the direction toward the injection sleeve.

[Effect]

According to the present invention, the tip lubricant not only lubricates the injection sleeve, but also is supplied to the mold space side by the molten metal injected by the injection plunger. That is, it is carried into the mold space prior to the molten metal while receiving heat from the molten metal. In this way, since the lubricant is carried by the molten metal, it receives the heat of the molten metal and is atomized well.
In other words, the lubricant is supplied to the mold space in a state where the lubricant reaches a high temperature and evaporates into a mist. Therefore, even if the lubricant is supplied to the mold space and adheres to the mold surface, the mold space will not be cooled by the lubricant.

In particular, according to the first method of the present invention, since the lubricant is supplied after the mold space is formed, a portion of the lubricant that is atomized during injection is directly supplied to the mold space. Even in this case, the lubricant supplied prior to the injection of the molten metal is affected by the ambient temperature and atomizes well, so that the mold space is not cooled.

Furthermore, in the second and third aspects of the present invention, since the lubricant is supplied to a position connecting the injection sleeve and the mold space, the atomized lubricant is surely directed toward the injection sleeve when the lubricant is injected. At the same time, the lubricant is also reliably supplied into the mold space by the molten metal from the injection plunger.

〔Effect of the invention〕

According to the present invention, since the lubricant that has been evaporated and atomized by the heat of the molten metal is supplied into the mold space, cooling of the mold space can be effectively prevented, and oil wrinkles etc. will occur on the product. can be prevented. Further, in the first aspect of the present invention, since the lubricant is supplied after the mold space is closed, the lubricant does not flow out wastefully, and the lubricant can be used efficiently. In particular, in the above-mentioned effect of reducing mold release force due to lubricant atomization, by efficiently utilizing the lubricant in this way, it becomes possible to control the supply amount of the lubricant to an optimum value.

Moreover, according to the second invention and the third invention, the inside of the injection sleeve can be reliably lubricated using the jetting force of the lubricant. At the same time, lubricant is always retained between the injection sleeve and the mold space.
When the molten metal is injected, the molten metal is reliably supplied to the mold space side.

〔Example〕

FIG. 1 shows an example of a die casting apparatus according to 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 receiving 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.

A spray nozzle 13 for spraying chip lubricant is opened in the runner portion 20 connecting the mold space 8 and the injection sleeve 1. 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 tip lubricant 14 in the lubricant tank 17 is pumped up to the 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. Further, this nozzle 13 extends through the movable mold 7 and is connected to a piston 22 housed in a cylinder 23 through a coupling ring 21. As the piston 22 slides, the nozzle 13 also slides back and forth.

FIG. 2 is a detailed view of the tip of the nozzle 13.
As can be seen from this figure, a tapered valve seat part 7a is formed at a position facing the runner part 20 of the movable mold 7, and the tapered tip of the nozzle 13 is attached to this valve seat part 7a. 13a comes into contact with and separates from the opening end 16a of the passage 16.
is opened and closed. This open end 16a opens toward the forming injection sleeve 1.

In addition, as shown in FIG. 1, the nozzle 13
A branch pipe 13a is formed in the middle, and high pressure air is sent into the passage 16 from this branch pipe 13a.

Chip lubricants include oil-based ones and water-soluble ones, and in this example, an oil-based chip lubricant is used which has a large effect of reducing mold release force.

Next, an example of a die casting method using the above device will be explained. First, with the movable mold 7 separated from the fixed mold 6, the valve 13 is advanced toward the fixed mold 6, and the tip 13a of the valve 13 is separated from the valve seat 7a. Then, the pump 15 is operated and the lubricant tank 17 is
Pump up the tip lubricant 14 inside. The pumped-up tip lubricant 14 is caught in the high-pressure air sent from the branch pipe 13a, passes through the passage 16, and is injected into the injection sleeve 1 from the open end 16a. At this time, the amount of lubricant applied to both sides is approximately 2.5cc.

When the injection of the tip lubricant 14 is completed, the valve 13 retreats, and the tip 13a abuts the valve seat 7a, closing the open end 16a. Next, the movable platen 4 is driven to bring the movable mold 7 into contact with the fixed mold 6, thereby forming a mold space 8. In this example, this step takes about 2.7 seconds. Thereafter, molten metal is supplied into the injection sleeve 1 from the injection port 1b using a carry-in device (not shown). This hot water supply time is about 5 seconds in this example.

Next, the injection plunger 11 is advanced at a relatively low speed (0.2 m/sec) until the molten metal fills the mold space 8, and after the molten metal reaches the mold space 8. The injection plunger is advanced at a relatively high speed (1.3 m/sec).
The molten metal in the mold space is maintained at a high pressure of about 1260 kg/cm ² by the pressure of the injection plunger.

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 at the time of spraying, and as a result, the tip lubricant is preliminarily applied to the fixed mold 6. It is thought that the molten metal adheres to the inner surface of the movable mold 7 and then comes into contact with the fixed mold 6 and the movable mold 7. Alternatively, it is considered that the mist of the chip lubricant is blown into the mold space 8 by the 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. This cycle is shown in FIG.

In the above example, the tip lubricant 14 was injected into the injection sleeve 1 with the movable mold 7 and the fixed mold 6 open, but as shown in FIG. After the mold space 8 is formed by bringing the mold 6 into contact with the mold 6, the chip lubricant 14 may be injected.

Incidentally, FIG. 5 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.

As explained above, by using the method of the present invention, the mold release force reducing effect of the chip lubricant can be brought out most effectively, and even though the mold release agent spraying is abolished, the movable mold can be effectively fixed to the mold. The solidified product can be pulled apart further and the solidified product can be extruded from the movable mold.

In particular, by eliminating the release agent spraying step, the cycle time of the die casting method can be shortened, and more die casting steps 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 surface of the molds 6 and 7 is 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.

Further, by using the die-casting apparatus of the present invention, the method of the present invention can be easily carried out.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention, FIG. 2 is a partial detailed view of the device shown in FIG. 1, and FIGS.
The figure shows the cycle time of an embodiment of the method of the present invention, Figure 5 is a sectional view showing an example of a solidified product, Figure 6 is a diagram showing the cycle time of the conventional die casting method, and Figure 7 is the mold release force. FIG. 8 is a diagram showing the relationship between mold release force and time after application of the chip lubricant. DESCRIPTION OF SYMBOLS 1... Injection sleeve, 6... Fixed mold, 7... Movable mold, 8... Mold space, 9... Extrusion pin, 11
...Injection sleeve, 13...Nozzle.

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 that communicates with the mold space and guides molten metal into the mold space, and A first step of bringing the movable mold into contact with the fixed mold to form a mold space using an extrusion pin that pushes out the solidified product, and a second step of supplying lubricant to a portion closer to the injection sleeve than the mold space. a third step of supplying the molten metal into the injection sleeve; a fourth step of injecting the molten metal in the injection sleeve into the mold space with an injection plunger; and 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. 2. a fixed mold, a movable mold that comes into contact with the fixed mold to form a mold space, an injection sleeve that communicates with the mold space and guides the molten metal into the mold space, and an extrusion pin that pushes out the solidified product from the mold space; a first step of injecting lubricant from the mold space to a region on the injection sleeve side from the nozzle using a lubricant supply nozzle that opens at a position connecting the injection sleeve and the mold space; two steps of bringing the metal into contact with the fixed mold to form a mold space; a third step of supplying the molten metal into the injection sleeve; and a fourth step of injecting the molten metal in the injection sleeve into the mold space side with an injection plunger. 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 third step. Perform the sixth step in chronological order,
and a die casting method in which the first step and the second step are performed before the third step. 3. A fixed mold, a movable mold that comes into contact with the fixed mold to form a mold space, an injection sleeve that communicates with the mold space and guides molten metal into the mold space, and a movable mold that is slidable within the injection sleeve. an injection plunger disposed to push molten metal into the mold space; and a lubricant nozzle opening at a position connecting the injection plunger and the mold space to spray chip lubricant toward the injection sleeve. die casting equipment. 4. The die casting apparatus according to claim 3, wherein the nozzle has a valve structure that opens a lubricant passage when the chip lubricant is injected, and closes the lubricant passage after the chip lubricant is injected.