JPH09155520A - Metal forming method using metallic mold and metal forming mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a forming condition and to improve the quality of a formed product by suitably generating a solid plug. SOLUTION: On the other peripheral surface of a sprue bush 12 abutted on a nozzle 17 in a forming machine and formed as a sprue of molten metal, a sprue heater 13 for heating the sprue bush 12 is arranged. A thermocouple 15 is embedded in the sprue bush 12, and the temp. of the sprue bush 12 is controlled so that the solid plug generates in the inner part of the nozzle 17 and a pressure loss for pushing out the solid plug is smaller than 100kg/cm<3> based on the temp. measured by the thermocouple 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal forming method and a metal forming die using a die, and in particular, a nozzle of a forming machine is brought into contact with a sprue bush serving as a gate of the die. Concerning suppression of temperature drop due to.

[0002]

2. Description of the Related Art Conventionally, in the molding of metal using a mold, the temperature of the entire mold is kept at a constant temperature below the solidification temperature of the metal to be molded, as is known in the die casting method and the thixomolding method. There is. For example, in the molding of zinc alloy, magnesium alloy, aluminum alloy, 150
The mold temperature is maintained at about 300 ° C.

The mold is composed of a fixed mold and a movable mold, and a sprue bush forming a sprue is attached to the fixed mold. During molding, the nozzle tip of the molding machine contacts the sprue bushing, and the molten metal in the nozzle is injected under pressure into the mold through the sprue bushing and solidified in the mold. The nozzle is at the melting temperature of the metal, but the heat of the nozzle escapes to the sprue bush by contacting with the sprue bush that is kept below the solidification temperature of the forming metal, and as a result,
The temperature at the tip of the nozzle is below the solidification temperature of the forming metal.

When the temperature at the tip of the nozzle falls below the solidification temperature of the forming metal, a solid plug 51, in which the metal is solidified, is formed inside the nozzle tip, as shown in FIG. When the molten metal is injected into the mold from the nozzle in this state, the pressure loss at the time of injection increases, and the solid plug itself is pushed out into the mold. As a result, the molding conditions become unstable and the quality of the molded product deteriorates.

Therefore, in order to suppress the formation of the solid plug 51, a method of raising the temperature of the mold or the temperature of the nozzle is adopted.

[0006]

However, in the method of raising the temperature of the mold to a high temperature, when the molded product is taken out of the mold, the strength of the metal, which is the molded product, is weak. There is a problem that the molded product may be deformed. On the other hand, the method of raising the temperature of the nozzle has a problem that the molten metal may be ejected from the nozzle because it is difficult to form a solid plug.
That is, the solid plug causes unstable molding conditions and deteriorates the quality of the molded product. However, if it is not generated at all, the molten metal will be ejected from the nozzle. Generation of plugs is necessary.

[0007] Therefore, it is an object of the present invention to provide a metal forming method and a metal forming die for stabilizing the forming conditions and improving the quality of the formed product by suitably forming a solid plug. .

[0008]

To achieve the above object, a metal forming method of the present invention uses a mold having a fixed side and a movable side, and a sprue bush serving as a spout of the mold has a nozzle of a forming machine. In the metal forming method of injecting molten metal from the nozzle through the sprue bush under pressure into the mold, a solid plug in which the metal for forming is solidified is generated at the tip of the nozzle, and The pressure loss of the molding machine when pushing out the solid plug from the nozzle is 100 kg.
It is characterized in that molten metal is injected under pressure into the mold while heating the sprue bush so as to be smaller than / cm ² .

Further, using a mold having a fixed side and a movable side, a nozzle of a molding machine is brought into contact with a sprue bush serving as a sprue of the mold, and molten metal is passed from the nozzle through the sprue bush to the mold. In the metal forming method in which pressure is injected into the inside of the sprue bush, a member having a lower thermal conductivity than that of the material forming the mold is provided at a contact portion of the sprue bush with the nozzle, and a metal for forming is formed at a tip of the nozzle. Solidified solid plug is generated, and the molten metal is heated in the mold while heating the nozzle so that the pressure loss of the molding machine when the solid plug is extruded from the nozzle is less than 100 kg / cm ^2. It may be characterized in that it is injected under pressure.

The metal forming die of the present invention comprises a fixed side and a movable side, and the fixed side is provided with a sprue bush which serves as a sprue for molten metal when a nozzle of a forming machine abuts on the fixed side. In the mold, the sprue bush is provided with temperature drop suppressing means for suppressing a temperature drop of the nozzle due to the nozzle coming into contact with the sprue bush.

The temperature drop suppressing means has a heat conductivity higher than that of a heater for heating the sprue bush, or a material of the mold, which is provided at a contact portion of the sprue bush with the nozzle. Lower members can be used.

When a heater is used as the temperature drop suppressing means, the sprue bush is provided with a thermocouple for measuring the temperature of the sprue bush, and the sprue bush is preliminarily set based on the measurement result of the thermocouple. The heater may be driven so as to reach a set temperature, and further, the preset temperature is a solid plug in which the metal for molding is solidified at the tip of the nozzle,
Further, the temperature may be such that the pressure loss of the molding machine when the solid plug is pushed out from the nozzle is smaller than 100 kg / cm ² . On the other hand, when a member having a low thermal conductivity is used as the temperature drop suppressing means, the member may be a ceramic material.

In the metal forming die of the present invention constructed as described above, the nozzle of the forming machine is brought into contact with the sprue bush serving as a sprue, and the molten metal is injected from the nozzle through the sprue bush into the die. . At this time, a solid plug in which the metal to be molded is solidified at the tip of the nozzle is generated inside the nozzle, and this solid plug is also extruded into the mold together with the molten metal. Here, when the nozzle comes into contact with the sprue bushing and the tip of the nozzle is excessively cooled, a large solid plug is generated, resulting in a large pressure loss when injecting the molten resin into the mold and deterioration of the quality of the molded product. However, since the sprue bush is provided with the temperature drop suppressing means for suppressing the temperature drop of the nozzle, the solid plug is preferably generated. Such suppression of the temperature drop of the nozzle can be achieved by heating the sprue bush to a predetermined temperature or providing a member having a low thermal conductivity at the contact portion between the sprue bush and the nozzle.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of a metal forming die of the present invention, and FIG. 2 is an enlarged sectional view of the metal forming die shown in FIG. 1 near a sprue bush.

This mold is a mold used for metal injection molding, and is roughly divided into a movable side 1 and a fixed side 2, as shown in FIG. On the movable side 1, a movable side mold plate 3 is attached to a movable side mounting plate 6 fixed to a movable plate (not shown) of a molding machine via a spacer block 5 and a receiving plate 4. The movable side mold plate 3 has a core 9 forming a male mold.
Is installed. Further, an ejector plate 7 is provided between the movable side mounting plate 6 and the receiving plate 4 so as to be movable with respect to the movable side mounting plate 6 in parallel with the moving direction of the movable plate. The ejector plate 7 is provided with ejector pins 8 and the like for ejecting a molded product attached to the core 9 when the mold is opened.

On the fixed side 2, a fixed side mold plate 11 is attached to a fixed side mounting plate 10 fixed to a fixed plate (not shown) of the molding machine. The fixed-side mold plate 11 has a concave portion 11a serving as a female mold at a portion facing the core 9 on the movable side 1.
By moving the movable plate of the molding machine forward and closing the mold, a molding cavity is formed between the core 9 and the recess 11a. Fixed side mounting plate 10 and fixed side template 11
Through holes are formed in the center of the sprue bushing 12, and the sprue bushes 12 that penetrate the through holes and form the sprue are mounted. The sprue bush 12 is formed with a sprue 12a for introducing the molten metal injected from the molding machine into the mold. One end of the sprue 12a is in contact with the nozzle 17 of the molding machine, and the other end is in communication with the material pool 3a formed on the movable-side mold plate 3. This material pool 3a is a runner 3 formed on the movable side mold plate 3.
It communicates with the cavity via b.

Here, the structure near the sprue bush 12 will be described with reference to FIG. Sprue bush 12
A sprue heater 13 is disposed on the outer peripheral surface of the sprue heater 13 between the sprue heater 13 and the fixed side template 11. This sprue heater 13
The sprue bush 12 includes a spacer 14 fixed to the movable side end of the through hole of the fixed side template 11 and a locate ring 16 fixed to the fixed plate side end surface of the fixed side mounting plate 10.
It is sandwiched between and and is fixed to the fixed-side template 11. Also,
A thermocouple 15 for measuring the temperature of the sprue bush 12 is embedded in the sprue bush 12. The sprue heater 13 and the thermocouple 15 are each connected to an external temperature control device (not shown), and based on the measurement result of the thermocouple 15, the sprue heater 12 is adjusted to a predetermined temperature. 13 is controlled. It should be noted that the temperature of the entire mold is set and controlled to a predetermined temperature as in the conventional case.

On the other hand, a thermocouple 19 and a nozzle heater 18 are also provided at the tip of the nozzle 17 of the molding machine, and the temperature of the tip of the nozzle 17 reaches a predetermined temperature based on the measurement result of the thermocouple 19. Thus, the nozzle heater 18 is controlled.

In order to carry out injection molding of a metal material based on the above construction, molten metal is injected from the nozzle 17 with the mold clamped. At this time, the tip of the nozzle 17 is sprue bush 12. Nozzle 17 because it is joined
The state of the metal in the inside is as shown in FIG.
That is, a solid plug 51 in which the metal for molding is solidified is generated at the most distal end portion, and from there, it becomes a solid-liquid coexistence region 52 in which the solid phase and the liquid phase are gradually mixed. Solid-liquid coexistence region 5
In 2, the solid fraction decreases toward the rear end of the nozzle,
Eventually, the liquid region 53 becomes almost liquid. The length L of the solid plug 51 becomes longer as the temperature of the sprue bushing 12 is lower and the tip of the nozzle 17 is cooled.

When injection is performed in this state, the solid plug 51 is formed at the tip of the nozzle 17 as described above. Therefore, depending on the length L of the solid plug 51, the solid plug 51 may be pushed out from the nozzle. Great pressure is required. That is, the pressure loss increases. On the other hand, if the temperature of the nozzle 17 becomes unnecessarily high and the solid plug 51 is not generated at all, there is a risk that molten metal will be ejected from the nozzle 17. Therefore, the present inventor seeks the length L of the solid plug 51 within a range that does not affect the molding conditions.
The relationship between the length L and the pressure loss was investigated by experiments. Table 1 shows the results.

[0022]

[Table 1] It is known that if the pressure loss is about 100 kg / cm ² , the molding conditions are hardly affected.
It was found that the length L of the solid plug 51 at that time was 5 mm. If the length L of the solid plug 51 is 5 mm or less, the solid plug 51 extruded from the nozzle 17 is accommodated in the material pool 3a of the movable side mold plate 3, so that the molten metal injected from the nozzle 17 is It does not hinder the filling of the cavity through the runner 3b. On the other hand, as described above, the sprue bushing 12 should not be heated to a temperature at which the solid plug 51 is not generated because a problem occurs even if the solid plug 51 is not generated at all.

Therefore, in order to eliminate the adverse effects of the solid stopper 51 while forming the solid stopper 51,
It is only necessary to heat the sprue bushing 13 so that the pressure for pushing out the solid plug 51 becomes less than 100 kg / cm ² within the range where is generated. Since the metal in the liquid-solid coexistence region 52 has a thixotropic flow, no problem occurs even if it enters the mold during injection.

As is clear from the above description, the injection pressure in the initial stage of the injection process, that is, the pressure for pushing out the solid plug 51 from the nozzle 17 is more than 100 kg / cm ² within the range where the solid plug 51 is produced. To be smaller
If the temperature of the sprue bush 12 is adjusted by the sprue heater 13, the molding conditions will be stable and the quality of the molded product can be improved. The temperature of the sprue bushing 12 can be easily set if such a temperature is obtained in advance by experiments or the like. Furthermore, the injection pressure may be measured for each injection, and if the initial injection pressure is likely to exceed the above pressure, correction may be performed to raise the set temperature.

Further, since the temperature of the sprue bushing 12 is not adjusted but the temperature of the entire mold is adjusted,
Temperature control is easy. Moreover, since it is not necessary to raise the temperature of the entire mold or the temperature of the nozzle 17 as in the conventional case, there is no problem that the molded product is deformed when ejected by the ejector pin 8. However, there is no danger that the molten metal will be ejected from the nozzle 17.

FIG. 3 is a sectional view of a second embodiment of the metal molding die of the present invention, and FIG. 4 is an enlarged cross-sectional view of the metal molding die shown in FIG. 3 in the vicinity of the sprue bush.

In this embodiment, as a means for suppressing the temperature drop of the nozzle 37 during injection molding, instead of controlling the temperature of the sprue bush 32 by a heater, a metal is attached to the contact portion of the sprue bush 32 with the nozzle 37. A contact bush 33 made of a ceramic material having a lower thermal conductivity than the material forming the mold is provided.

The other structures and the temperature control of the entire mold are the same as those in the first embodiment, and therefore the description thereof will be omitted. The temperature of the nozzle 37 is also measured by the thermocouple 39 as in the first embodiment, and the length of the solid plug is controlled to a predetermined length. The temperature at which the length of the solid plug reaches a predetermined length is the range in which the solid plug is produced, and the initial injection pressure during injection is 100 kg / cm.
^The temperature is less than ² .

Table 2 shows the thermal conductivity of various materials.

[0030]

[Table 2] From Table 2, it is understood that zirconia or silicon nitride may be used as the material of the contact bush 33.

As described above, by providing the contact bush 33 having a lower thermal conductivity than the mold material at the contact portion with the nozzle 37, the nozzle 37 is brought into contact with the mold during metal injection molding. The temperature drop of 37 is suppressed. As a result, the length of the solid plug in the nozzle 37 is maintained at an appropriate length, so that the molding conditions can be stabilized and the quality of the molded product can be improved. Further, since it is not necessary to set the temperature of the entire die or the temperature of the nozzle 37 to a temperature higher than necessary, there is no deformation at the time of protruding the molded product or ejection of the molten resin from the nozzle 37. Further, since the temperature control of the sprue bushing 32 is not necessary, the temperature control is the first in that respect.
It is easier than the embodiment.

In this embodiment, an example in which ceramic is used as the material of the contact bush 33 has been shown, but the material is not limited to ceramic as long as the thermal conductivity is lower than that of the mold material.
However, considering that it is a mold used for metal injection molding, it can be said that a ceramic having excellent heat resistance is preferable as a material used for the contact bush 33.

[0033]

As described above, according to the present invention, the temperature of the nozzle is reduced by heating the sprue bush to a predetermined temperature or providing a member having a low thermal conductivity at the contact portion of the sprue bush with the nozzle. By suppressing, the solid plug in the nozzle is preferably generated, so that the molding conditions can be stabilized and the quality of the molded product can be improved. Moreover,
Since it is not necessary to raise the temperature of the entire mold as in the past, it is possible to prevent deformation of the molded product when the molded product is protruding,
Furthermore, since it is not necessary to raise the temperature of the nozzle, it is possible to prevent the risk of the molten metal spouting from the nozzle.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a metal molding die of the present invention.

FIG. 2 is an enlarged cross-sectional view in the vicinity of the sprue bush of the metal molding die shown in FIG.

FIG. 3 is a sectional view of a second embodiment of the metal molding die of the present invention.

FIG. 4 is an enlarged cross-sectional view near the sprue bush of the metal molding die shown in FIG.

FIG. 5 is a cross-sectional view showing a state of metal at a nozzle tip portion.

[Explanation of symbols]

 1 movable side 2 fixed side 3 movable side mold plate 3a material pool 3b runner 4 receiving plate 5 spacer block 6 movable side mounting plate 7 ejector plate 8 ejector pin 9 core 10 fixed side mounting plate 11 fixed side mold plate 11a recess 12, 32 Sprue bush 12a Sprue 13 Sprue heater 14 Spacer 15,19,39 Thermocouple 16 Locate ring 17,37 Nozzle 18 Nozzle heater 33 Contact bush

Claims (8)

[Claims] 1. A sprue bush (1) serving as a sprue for the mold, which uses a mold having a fixed side (2) and a movable side (1).
In the metal forming method, in which a nozzle (17) of a forming machine is brought into contact with 2) and molten metal is injected under pressure from the nozzle (17) through the sprue bush (12) into the mold, the nozzle (17) A solid plug (51) in which the metal for molding is solidified is generated at the tip of the, and the pressure loss of the molding machine when the solid plug (51) is pushed out from the nozzle (17) is less than 100 kg / cm ^2. A metal forming method, wherein molten metal is injected under pressure into the mold while heating the sprue bush (12) as described above. 2. A mold having a fixed side and a movable side is used,
A nozzle (37) of a molding machine is brought into contact with a sprue bush (32) serving as a gate of the mold, and molten metal is injected under pressure from the nozzle (37) through the sprue bush (32) into the mold. In the metal forming method, a member (33) having a lower thermal conductivity than that of the material forming the mold is provided at a contact portion of the sprue bush (32) with the nozzle (37), and the nozzle (37) is A solid plug having a metal for molding solidified is generated at the tip, and the pressure loss of the molding machine when the solid plug is extruded from the nozzle (37) is smaller than 100 kg / cm ^2. ) Is heated and molten metal is pressure-injected into the said metal mold | die, The metal forming method characterized by the above-mentioned. 3. A stationary side (2) and a movable side (1), wherein said stationary side (2) has a nozzle (17, 3) of a molding machine.
In a metal forming die provided with a sprue bush (12, 32) which is brought into contact with (7) and serves as a sprue for molten metal, the nozzle (1) is attached to the sprue bush (12, 32).
7, 37) is provided with temperature drop suppressing means (13, 33) for suppressing a temperature drop of the nozzle (17, 37) due to contact of the sprue bush (12, 32). Metal molds. 4. The metal forming die according to claim 3, wherein the temperature drop suppressing means is a heater (13) for heating the sprue bush (12). 5. The sprue bush (12) is provided with a thermocouple (15) for measuring the temperature of the sprue bush (12), and based on the measurement result of the thermocouple (15), the sprue The metal forming die according to claim 4, wherein the heater (13) is driven so that the bush (12) has a preset temperature. 6. The solid plug (5) formed by solidifying a molding metal at the tip of the nozzle (17) at the preset temperature.
1) is generated, and the pressure loss of the molding machine when the solid plug (51) is pushed out from the nozzle (17) is 10
The metal forming mold according to claim 5, wherein the temperature is such that the temperature is lower than 0 kg / cm ² . 7. The member having a lower thermal conductivity than a material forming the mold, which is provided in a contact portion of the sprue bush (32) with the nozzle (37), the temperature drop suppressing means. 33) The metal mold for molding according to claim 3. 8. The metal forming mold according to claim 7, wherein the member (33) having a low thermal conductivity is a ceramic material.