JPH0316211B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applied to injection sleeves for various castings, plunger end faces, mold cavities, and other molten metal contact surfaces to improve the flow of the molten metal and to keep the molten metal warm. This invention relates to a method of applying soot to a molten metal contact surface in order to improve mold releasability.

[Conventional technology]

Die casting, squeeze casting, molten metal molding, etc.
In various types of casting and forging, if the molten metal comes into direct contact with the molten metal contact surfaces such as the mold cavity, the inner surface of the injection sleeve, and the end face of the plunger, the product may not easily be released from the mold or the plunger tip may not move smoothly. Therefore, prior to casting, a release agent is applied to these molten metal contact surfaces.

Conventionally, this type of mold release agent has been used, for example, water-soluble Hitazol (trademark), but since this type of mold release agent is water-soluble, the temperature of the surface to which it is applied is 100 - 100℃. Not only is there a problem that the cycle time is limited to a low temperature of about 250℃, and the coating amount varies depending on the temperature of the coating surface, making the conditions unstable, but if you try to shorten the cycle time, water cooling is required, which limits the shortening. There was a problem that the cycle time was extended. In addition, since the main component of the mold release agent is water-solubilized crystalline graphite, it has high thermal conductivity and poor heat retention, and the molten metal cools easily, which may result in poor water circulation. When the concentration was increased to improve heat retention, there was a problem that the spray nozzle was easily clogged and the conditions were unstable.

Therefore, the present applicant has proposed an injection method using a molding machine, which is disclosed in Japanese Patent Application Laid-Open No. 61-99551. In this method, lubricant or mold release agent is applied to the contact surface of the molten metal, soot is applied with a burner on top of it, and after the molten metal is supplied, mold clamping and injection are performed.As a result, only the mold release agent is used. Compared to the previous case, the heat retention is improved, and the time it takes for the molten metal to solidify is longer, which improves the flow of the hot water, which not only improves the quality of the product, but also significantly reduces the amount of gas generated. It had the effect of doing so.

[Problem that the invention seeks to solve]

However, in this conventional injection method of a molding machine, which involves applying soot to the molten metal contact surface, it is not always possible to expect satisfactory results in terms of the adhesion of soot to the molten metal contact surface, and it is difficult to achieve results in one shot. Since soot must be applied every cycle, there are problems in that productivity decreases and labor becomes a burden.

[Means for solving problems]

In order to solve these problems, in the present invention, after applying a mold release agent or lubricant to the molten metal contact surface, combustion gas is injected from an injection nozzle to the molten metal contact surface to generate soot. A high voltage charge was applied to the molten metal contact surface and the molten metal contact surface to cause this soot to adhere to the molten metal contact surface.

[Effect]

When the injection nozzle is opposed to the molten metal contact surface such as the inner surface of the mold cavity or the injection sleeve and the combustion gas is injected, soot is generated.
When a high voltage charge of 30,000 volts is applied, an attractive force is generated and the soot is very well adsorbed to the molten metal contact surface, and the soot does not fall off even after several shot cycles.

〔Example〕

1 to 6 are diagrams shown to explain the method of applying soot to a molten metal contact surface according to the present invention, in which FIG. 1 is a schematic configuration diagram of a soot coating device, and FIG. 2 is a diagram of an injection burner. The left half and right half of the plan view and Fig. 3 are the AA sectional view and BB sectional view of Fig. 2, respectively.
Figure 4 is a cross-sectional view of CC and DD in Figure 3, Figure 5 is a view taken in the direction of arrow E in Figure 2, and Figure 6 is a vertical cross-sectional view of a vertical injection type die casting machine equipped with a soot coating device. It is. In FIG. 6, a fixed mold 2 is attached to the upper surface of a fixed platen 1 fixed on a floor foundation via a bolster 3, and a fixed platen 1 and an upper fixed platen (not shown) are connected to each other. A movable plate (not shown) on which a movable mold 5 is mounted is supported on the tie rod 4 connected at the corner so as to be movable up and down. Then, the fixed mold 2 and the movable mold 5 are clamped by lowering the movable platen by a mold clamping cylinder, and the fixed mold 2 is clamped by the mold clamping.
A cavity is formed by the concave portion 2a of the movable mold 5 and the convex portion 5a of the movable mold 5. On the other hand, on the bottom of the pit below the floor, an injection cylinder 6 is pivotally supported via a bracket 7 so as to be able to stand upright and tilt freely, and the piston rod 8, which advances and retreats using hydraulic pressure, has a plunger tip 9a as a head. Plungers 9 are concentrically connected by a coupling ring 10. Reference numeral 11 denotes a block formed in a cylindrical shape so as to surround the plunger 9 and the coupling 10, and a pair of cylinders 11a and an injection cylinder 6 formed in this block.
A removable cylinder 13 is formed by a ram 12 which is installed on the upper surface and slidably fits into the cylinder 11a, and the block 11 is raised by supplying oil above the ram 12. has been done. A cylindrical injection sleeve 14, which is shown enlarged in FIG.
are slidably fitted. and block 1
1 rises, the injection cylinder 14 also rises to the position indicated by the chain line in FIG. 6, engages with the hole in the bolster 3, and is joined to the fixed mold 2. 15 is a sprue provided between this joint end and the cavity.

Reference numeral 16 denotes a tilting cylinder pivotally mounted on the base side, and the working end of the piston rod 17 is pivotally mounted on the injection cylinder 6, and when the block 11 is lowered, the piston rod 17 is moved from the state shown in the figure by hydraulic pressure. By advancing the injection cylinder 6
The block 11, injection sleeve 14, etc. are configured to be tilted together to the position shown by the chain line in FIG. At this tilted position, soot application and molten metal injection, which will be described below, are performed. Reference numeral 18 is a stopper that restricts the injection cylinder and the like in an upright position.

The soot coating device will now be explained. The gas burner, generally designated by the reference numeral 20 in FIG.
It is equipped with a gas pipe 21 formed in a double structure by an outer pipe a and an outer pipe 21b, and a hydrocarbon gas such as acetylene gas is introduced to a connection port 21c of the inner pipe 21 via a hose (not shown). It's dark. This gas is a gas that generates soot as carbon with an amorphous structure called amorphous carbon by incomplete combustion at a low temperature of about 350℃, and includes methane gas, alcohol gas, propane gas, butane gas, etc. But that's fine. Furthermore, air is introduced to the connection port 21d of the outer tube 21b via a hose (not shown). At the tip of the gas pipe 21, there is formed a double-structured mixing chamber 22 that communicates with both pipes 21a and 21b. A plurality of injection nozzles 23, including a plurality of injection nozzles 23 in three stages and one in the center, are arranged in parallel at approximately equal intervals and project radially in communication with the mixing chamber 22. The gas burner 20 configured in this manner is supported by a support device (not shown), and is configured to be inserted or not inserted into the inner hole of the injection sleeve 14 tilted to the position shown in chain lines in FIG. Then, when the air is mixed and the gas injected from the injection nozzle 23 is ignited and inserted into the injection sleeve 14, the above-mentioned soot is generated and the mold release agent or lubricant of the injection sleeve 14 is applied in advance. Adheres to the inner surface.

Further, a high voltage generator 24 is connected to the gas pipe 21 of the gas burner 20 with a lead wire 25, and the ignited gas burner 20 is connected to the injection sleeve 1.
When inserted into the injection sleeve 14 and generating soot, a high voltage charge is applied to the soot and the inner surface of the injection sleeve 14, so that the soot is attracted to the inner surface of the injection sleeve 14 to increase the adhesion force of the soot. Constructed to ensure uniform adhesion. The voltage is 500 to 3000V, preferably 10000 to 20000V and several mA. In Figure 1, the soot is charged and becomes positive.
The injection sleeve 14 is shown being grounded through other parts to become a negative voltage.

Furthermore, after the soot is applied, molten metal 26 is supplied into the tilted injection sleeve 14 by a pouring device (not shown).

A method of applying soot to the molten metal contact surface in the die casting machine configured as described above will be explained. A mold release agent or lubricant is applied in advance to surfaces that come into contact with the molten metal, such as the injection sleeve, the end face of the plunger, and the mold cavity. After the mold is clamped, the block 11 is lowered to remove the injection sleeve 14 from the bolster 3, and then the tilting cylinder 16 tilts the injection cylinder 6 and the like to the position indicated by the chain line in FIG. When the injection nozzle 23 of the gas burner 20 is ignited and inserted into the inner hole of the injection sleeve 14, combustion gas is injected from the injection nozzle 23, and this combustion gas flows into the mixing chamber 22.
Since air is mixed in the flame, the appropriate speed is imparted to the flame depending on the mixing ratio. Soot is generated by the combustion of the gas, and this soot adheres to the inner surface of the injection sleeve 14, which serves as the molten metal contact surface that the injection nozzle 13 faces, and to the end surface of the plunger tip 9a. The gas burner 20 is moved up and down at an appropriate speed so that soot adheres uniformly.

When applying such soot, a high voltage charge from the high voltage generator 24 is applied to the soot and the inner surface of the injection sleeve 14 and the end surface of the plunger tip 9a, so the soot is attracted to these application surfaces and is firmly attached. and adheres evenly.

After applying the soot in this manner, the gas burner 20 is removed and the molten metal 26 is supplied into the injection sleeve 14. After the injection cylinder 6 and the like are erected by the tilting cylinder 16, the detachable cylinder 1 is
3, the block 11 is raised and joined to the fixed mold 2 of the injection sleeve 14. When the piston rod 8 of the injection cylinder 6 is raised hydraulically, the plunger tip 9a rises within the injection sleeve 14, so that the molten metal 26 is injected into the cavity through the sprue 15. After injection, the mold is opened after the molten metal 26 solidifies and the product is removed.

Thus, with this soot application method,
When soot is generated, a high voltage charge is applied to the soot and the coated surface, which greatly increases the adhesion of soot and maintains heat retention for a long time. Also, less gas is generated.

In addition, in the present invention, when applying soot to the inner surface of the injection sleeve using a burner device, the soot is applied while rotating the burner device around the axis of the burner device and moving it in the axial direction. It is also possible to apply soot evenly over the entire surface of the inner surface of the injection sleeve, etc.

Furthermore, in the present invention, if desired, the magnitude of the electric charge applied between the soot and molten metal contact surface is varied depending on the vertical or lateral positions of the injection sleeve and the mold cavity. It is also possible to vary the degree of application of the soot and the thickness of the soot as appropriate. In addition, when applying soot while moving the burner device, a timer may be used, or the movement position of the burner device may be detected using a pulse or limit switch.
Based on the electrical command and using a voltage variable device, the magnitude of the electric charge applied between the contact surfaces of the soot and the molten metal is changed over time, and the thickness of the soot coating is appropriately changed depending on the location. You can also do it like this.

Note that if ceramic is thermally sprayed on the inner surface of the injection sleeve 14, the electrical resistance will increase, making it difficult for current to flow, slowing down the dissipation of electricity, and prolonging the charging time.
Combined with the impregnated state in which the soot enters the bolus, the adhesion of the soot increases, making it more effective. That is, it can be called a sprayless mold or a sprayless sleeve, and soot can be sprayed once every few shot cycles.

Further, in this embodiment, the injection sleeve and plunger tip of a vertical die-casting machine are used as examples of the molten metal contact surface to which soot is applied, but a horizontal die-casting machine, squeeze casting machine, molten metal making machine, etc. may also be used. The molten metal contact surface may be any surface that comes into contact with the molten metal, such as a mold cavity.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, as a method for applying soot to a molten metal contact surface, after applying a mold release agent or a lubricant to the molten metal contact surface, combustion gas is injected from an injection nozzle to the molten metal contact surface. By using a method of spraying soot to generate soot, and applying a high voltage charge to the contact surface of the soot and molten metal to cause the soot to adhere to the contact surface of the molten metal, compared to the case of using only a conventional mold release agent, Not only does it have the effect of high heat retention and less gas generation, but the adhesion of the soot increases significantly as it is charged and adsorbed to the coated surface, and the adhesion is maintained for a long time. The number of soot applications is reduced, increasing productivity and reducing labor.

[Brief explanation of the drawing]

1 to 6 are diagrams shown to explain the method of applying soot to a molten metal contact surface according to the present invention, in which FIG. 1 is a schematic explanatory diagram of a soot coating device, and FIG. 2 is a schematic illustration of a soot coating device, and FIG. The left half and right half of the plan view and Fig. 3 are the AA sectional view and BB sectional view of Fig. 2, respectively.
The left half and right half of Figure 4 are respectively the same as those of Figure 3.
A CC sectional view and a DD sectional view, FIG. 5 is a view along arrow E in FIG. 3, and FIG. 6 is a longitudinal sectional view of a vertical clamping vertical injection type die casting machine equipped with a soot coating device. 2...Fixed mold, 9a...Plunger tip,
14...Injection sleeve, 20...Gas burner, 2
3... Injection nozzle, 24... High voltage generator, 2
5... Lead wire, 26... Molten metal.

Claims (1)

[Claims] 1. After applying a mold release agent or lubricant to the molten metal contact surface, combustion gas is injected from an injection nozzle to the molten metal contact surface to generate soot, and a high voltage charge is applied to the soot and the molten metal contact surface. A method for applying soot to a molten metal contact surface, which is characterized by adhering soot from a lever to the molten metal contact surface.