JP2004154954A - Mold assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of a defective and the irregularity of quality in a mold assembly having a sprue. <P>SOLUTION: A cavity 13 is formed between a pair of molds 10 and 12 which are made approach/separate from each other, the sprue 15 one end of which is opened to a seat surface 10a formed on the outer surface of one mold 10 and the other end of which is made to communicate with the cavity is formed. and a molten metal M injected from the tip of the nozzle 22 of an injection apparatus 20 brought into contact with the seat surface is packed in the cavity 13 through the sprue. A cooling medium control device 30 controls the flow rate of a cooling medium supplied to a cooling medium hole 16 formed in the vicinity of the seat surface so that the temperature in the vicinity of the seat surface of one end of the sprue detected by a temperature sensor 31 becomes a constant prescribed temperature. Preferably, the sprue is formed by the inner surface of another sprue bush 11 fixed in one mold. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a molding die apparatus having a sprue.
[0002]
[Prior art]
As a molding die apparatus having a sprue, for example, as shown in FIG. 2, a pair of molds in which a cavity 3 and a runner 4 and a gate 4a connecting the both are formed therebetween are formed so as to be separated from each other. There are molds 1 and 2 in which a molten metal M injected from a nozzle 8 of an injection machine is filled into a cavity 3 from a sprue 5 formed in a fixed mold 1 via a runner 4 and a gate 4a. (For example, see Patent Document 1). In this prior art, the molten metal M is a magnesium alloy in a semi-molten state, and is provided in the fixed mold 1 around the sprue 5 in order to prevent a molding cycle from being lengthened due to a delay in solidification of the molten metal M in the sprue 5. The cooling medium is passed through the cooling holes 6 to speed up the solidification of the molten metal M. Further, in this prior art, the sprue 5 is formed directly on the fixed mold 1, but there is a sprue 5 formed by an inner surface of a sprue bush 7 fitted and fixed to the fixed mold 1 (for example, Patent Document 1). 2).
[0003]
[Patent Document 1]
JP 2001-30324 (Paragraph [0002], FIG. 7)
[0004]
[Patent Document 2]
JP-A-10-202350 (FIG. 2)
[0005]
[Problems to be solved by the invention]
In the molding die apparatus described in Patent Literature 1, the tip of the nozzle 8 of the injection device is brought into contact with a seating surface 1a formed on a part of the die 1 around one end of the sprue 5 to discharge the molten metal M. The cavity 8 is filled through the sprue 5, and at the tip of the nozzle 8, at least the molten metal M filled in the molds 1 and 2 is solidified, and the amount of the molten metal M injected in the next molding cycle is measured. It is in contact with the bearing surface 1a of the mold 1 until completion. Since the temperature of the mold 1 is lower than the temperature of the nozzle 8, the temperature of the nozzle 8 is lowered by this contact, and the temperature of the molten metal M in the tip of the nozzle 8 is also lowered and solidified to form the plug P.
[0006]
Since the temperature of the mold 1 changes considerably as the time elapses after the start of molding, the temperature at the tip of the nozzle 8 in contact with the temperature fluctuates greatly. When the temperature is low, the plug P formed is strongly fixed in the tip of the nozzle 8, and the pressure for pushing out the plug P at the start of the injection of the molten metal M increases. From behind, the injection amount of the molten metal M may be insufficient, resulting in defective products. Even when no defective product is generated in shape, if the pressure at the start of injection varies, the flow state of the molten metal M also varies, resulting in variation in the quality of the cast product. Conversely, if the temperature at the tip of the nozzle 8 rises and exceeds a certain limit, a complete plug P is not formed, and when the tip of the nozzle 8 is detached from the mold 1, the molten metal M in the nozzle 8 is removed. The problem of leakage occurs.
[0007]
An object of the present invention is to solve each of these problems by controlling the temperature in the mold near the bearing surface of one end of the sprue with which the tip of the nozzle comes into contact to a predetermined temperature. .
[0008]
[Means for Solving the Problems]
A molding die apparatus according to the present invention includes a pair of dies approaching and separating from each other, a cavity formed between the two dies that are closely joined together, and is formed in one of the dies. A sprue having one end opened to a seat formed on the outer surface of the same mold and the other end communicating with the cavity is provided, and the molten metal injected from the tip of the nozzle of the injection device in contact with the seat is passed through the sprue. In a molding die apparatus configured to be filled in the cavity, a cooling medium hole formed inside the mold near the seating surface, a temperature sensor for detecting a temperature near the mold seating surface, A cooling medium control device is provided for controlling the flow rate of the cooling medium supplied to the cooling medium hole such that the temperature near the seat surface detected by the sensor becomes a substantially constant predetermined temperature.
[0009]
In the molding die apparatus described in the preceding paragraph, the sprue is formed by the inner surface of a separate sprue bush fixed in the mold, the seat surface is formed at one end of the sprue bush, and the cooling medium hole is formed by the seat of the sprue bush. The temperature sensor is preferably formed inside the vicinity of the surface and detects the temperature near the seat surface of the sprue bush.
[0010]
In the molding die apparatus described in the above item 2, the cooling medium is preferably air.
[0011]
Function and Effect of the Invention
According to the present invention, a cooling medium hole formed inside the vicinity of the mold seat, a temperature sensor for detecting a temperature near the mold seat, and a temperature near the seat detected by the temperature sensor Is provided with a cooling medium control device that controls the flow rate of the cooling medium supplied to the cooling medium hole so that the temperature becomes substantially constant. Therefore, the temperature near the bearing surface of the mold detected by the temperature sensor is as described above. At a predetermined temperature, a plug having a substantially constant temperature slightly lower than the predetermined temperature is stably formed in the tip of the nozzle. Therefore, the pressure at the start of the injection of the molten metal becomes almost constant, and the injection amount of the molten metal does not become insufficient and the flow state of the molten metal does not fluctuate. Thus, the molten metal in the nozzle does not leak when the tip of the nozzle is separated from the mold.
[0012]
The sprue is formed by the inner surface of a separate sprue bush fixed in the mold, the seat surface is formed at one end of the sprue bush, the coolant hole is formed inside the sprue bush near the seat surface, and the temperature sensor is According to the molding die apparatus that detects the temperature near the seating surface of the sprue bush, the sprue bush has a smaller heat capacity than the die, and the sprue bush is fixed to the die, but the joint is formed. Has a considerable heat transfer resistance, so the temperature near the seat surface of the sprue bush is controlled by the cooling medium control device to control the flow rate of the cooling medium supplied to the cooling medium hole formed inside the seat surface of the sprue bush. As a result, the above-described predetermined temperature is maintained with a small control delay. As a result, the plug formed in the tip of the nozzle becomes more stable, so that the yield and quality of the cast product are further improved, and the possibility that the molten metal in the nozzle leaks is further reduced.
[0013]
According to the molding apparatus using air as the cooling medium, the air has a small heat capacity, so the thermal stress generated near the cooling medium hole is reduced, so that troubles such as cracks due to the thermal stress near the cooling medium hole are reduced. And it is very easy to implement.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a molding die apparatus according to the present invention will be described with reference to the embodiment shown in FIG. The molding die apparatus according to this embodiment has a pair of dies composed of a fixed die 10 and a movable die 12, and the fixed die 10 is connected to a mold clamping device (not shown) via a mounting plate 17. The movable die 12 is attached to a fixed die plate, and is attached to a movable die plate of a mold clamping device via a mounting plate 18 so as to be able to approach and separate from the fixed die 10 as shown by an arrow A.
[0015]
As shown in FIG. 1, when the fixed mold 10 and the movable mold 12 are joined to each other, a cavity 13 for molding a product is communicated between the molds 10 and 12 and the cavity 13 via a gate 14a. Runner 14 is formed. The fixed mold 10 is formed with a sprue 15 having a tapered hole shape penetrating in parallel with the moving direction A of the movable mold 12, and one end on the small diameter side has a concave spherical seat surface 10 a formed on the outer surface of the fixed mold 10. The other end, which is the large diameter side, is opened to the runner 14. The mounting board 17 has an opening 17a coaxial with the sprue 15 and having a diameter larger than that of the seat surface 10a.
[0016]
A sprue bush 11 that is substantially cylindrical and forms a part of the fixed mold 10 is fitted and fixed to the fixed mold 10, and a sprue 15 of the fixed mold 10 is formed by an inner surface of the sprue bush 11, and a seat surface 10a is formed. The sprue bush 11 is formed at one end. An air cooling hole (cooling medium hole) 16 is formed inside the sprue bush 11 near the seating surface 10 a so as to surround one end of the sprue 15.
[0017]
The injection device 20 includes a barrel 21 heated by heaters 23a and 23b and a nozzle 22 provided at the tip of the barrel 21. In the barrel 21, an injection screw (not shown) for injecting the molten metal M has an inner hole 21a. It is provided slidable with the inner surface. The tip of the nozzle 22 has a spherical shape that can abut on the seating surface 10a of the sprue bush 11. The injection device 20 retreats at the same time as the rotation of the injection screw, sends the molten metal M made of a semi-molten magnesium alloy to the distal end in the inner hole 21a, and rapidly advances the injected screw M at a predetermined timing. Is injected into the sprue 15 from the tip of the discharge hole 22a of the nozzle 22, and is filled into the cavity 13 via the runner 14 and the gate 14a.
[0018]
In the fixed mold 10 and the sprue bush 11, a thermocouple (temperature sensor) 31 whose tip is located near the seating surface 10a and detects the temperature of that portion is provided. (Medium control device) 30. The air flow control device 30 is disposed near the seat surface 10a of the sprue bush 11 via the air supply passage (cooling medium supply passage) 32 so that the temperature detected by the thermocouple 31 becomes a predetermined temperature (described later). The amount of cooling air supplied to the provided air cooling holes 16 is controlled. In this embodiment, the cooling air that has cooled near the seat surface 10a of the sprue bush 11 by passing through the air cooling hole 16 and has been warmed is discharged to the atmosphere.
[0019]
Next, the operation of the above-described embodiment will be described. In a state where the movable mold 12 is brought into contact with the fixed mold 10 and clamped, and the cavity 13 and the runner 14 are formed between the two molds 10 and 12, the injection device 20 moves forward to move the tip end of the nozzle 22. It comes into contact with the seat surface 10a of the sprue bush 11 of the fixed mold 10. Then, the injection screw in the barrel 21 of the injection device 20 rapidly advances, and the molten metal M measured and stored in the front end portion of the inner hole 21a is injected into the sprue 15 from the tip of the discharge hole 22a of the nozzle 22. Then, the cavity 13 is filled through the runner 14 and the gate 14a. Next, the injection device 20 retreats at the same time as the rotation of the injection screw, and measures the molten metal M to be injected next and sends it to the tip end in the inner hole 21a. When the measurement is completed, the operation of the injection screw is stopped. In parallel with this, when the molten metal M filled in the cavity 13, the runner 14 and the sprue 15 is solidified, the movable mold 12 is retracted by the mold clamping device to open the molds 10 and 12, and solidified in the cavity 13. The cast product is taken out together with the solidified molten metal in the runner 14 and the sprue 15. Thus, one cycle of the molding process is completed, and by repeating this, a cast product is produced. The injection device 20 is retracted when the solidification of the filled molten metal M is completed and the measurement of the molten metal M to be injected next is completed, so that the tip of the nozzle 22 is separated from the seating surface 10a of the sprue bush 11. Alternatively, the tip of the nozzle 22 may be kept in contact with the bearing surface 10a of the sprue bush 11 during the production of one lot.
[0020]
During the production of the casting, the cooling air from the air flow control device 30 is supplied to the air cooling holes 16 to cool the vicinity of the seating surface 10a of the sprue bush 11, and the air flow control device 30 The amount of cooling air supplied to the air cooling holes 16 is controlled so that the temperature near the seating surface 10a detected by 31 becomes a predetermined temperature. The barrel 21 and the nozzle 22 are heated by the heaters 23a and 23b to keep the magnesium alloy therein in the molten metal M in a semi-molten state, whereas the fixed mold 10 and the movable mold 12 including the sprue bush 11 are cooled by outside air. The temperature of the sprue bush 11 is lower than the temperature of the nozzle 22 because the molten metal M filled and solidified is solidified. As a result, the tip of the nozzle 22 is cooled by the sprue bush 11 in a state in which it is in contact with the seating surface 10a. Therefore, in the tip of the discharge hole 22a of the nozzle 22, the temperature of the molten metal M decreases, solidifies, and the plug P Is formed. The temperature at the tip of the nozzle 22 is affected by the temperature near the seating surface 10a of the sprue bush 11, and the higher the temperature near the seating surface 10a, the higher the temperature at the tip of the nozzle 22 and the plug P is substantially closed. When the temperature near the seating surface 10a is low, the temperature at the tip of the nozzle 22 is also low, and the formed plug P has a long length and is firmly fixed in the tip of the nozzle 22.
[0021]
Since the molten metal M injected from the injection device 20 is extruded by pushing out the plug P, if the plug P is firmly fixed in the tip of the nozzle 22, the pressure at the start of injection of the molten metal M increases. Some of the molten metal M leaks backward from between the injection screw and the inner hole 21a, and the injection amount of the molten metal M may be insufficient to cause defective products. Further, even when no defective product is produced in shape, if the pressure for pushing out the plug P varies, the flow state of the molten metal M also varies, so that the quality of the cast product varies. In order to prevent such a problem, in this embodiment, the plug P formed in the tip of the nozzle 22 substantially affects the injection amount of the molten metal M injected into the sprue 15 from the nozzle 22. The temperature near the seating surface 10a of the sprue bush 11 detected by the thermocouple 31 is controlled so as not to give. That is, the air flow controller 30 sets the plug P such that the temperature near the seating surface 10a detected by the temperature sensor 31 does not substantially affect the injection amount of the molten metal M injected from the nozzle 22. The flow rate of the cooling medium supplied to the cooling medium hole 16 is controlled so as to have a predetermined temperature which is formed inside the tip of the discharge hole 22a of the nozzle 22 abutting on the nozzle 10a.
[0022]
As described above, in the above-described embodiment, the plug P having a temperature that does not substantially affect the injection amount of the molten metal M to be injected next is stabilized in the distal end portion of the discharge hole 22a of the nozzle 22. Formed. Therefore, since the pressure when the injection of the molten metal M from the tip of the nozzle 22 into the sprue 15 is started becomes substantially constant, it is possible that the injection amount of the molten metal M is insufficient or the flow state of the molten metal M fluctuates. As a result, it is possible to obtain a cast product of constant and stable quality with good yield. Further, when the tip of the nozzle 22 is detached from the bearing surface 10a of the sprue bush 11, the molten metal M in the nozzle 22 does not leak.
[0023]
In the above-described embodiment, the plug P formed in the distal end portion of the nozzle 22 has a size that does not substantially affect the injection amount of the molten metal M injected into the sprue 15 from the nozzle 22. Thus, the accuracy of the injection amount of the molten metal injected from the injection device is improved, so that the quality of the obtained cast product is further improved. However, the present invention is not limited to this, and the plug P formed in the distal end of the nozzle 22 may be somewhat firmly fixed and the injection amount of the molten metal M may be slightly reduced. Even in this case, the temperature of the tip of the nozzle 22 abutting on the bearing surface 10a, which is at a constant predetermined temperature, is constant, so that the pressure of the molten metal M and the amount of injection into the sprue 15 at the start of injection are constant. Therefore, the injection amount of the molten metal M does not become insufficient, and the flow state of the molten metal M does not fluctuate, and a cast product of a constant and stable quality with a good yield can be obtained.
[0024]
In the above-described embodiment, the sprue 15 is formed by the inner surface of a separate sprue bush 11 fixed in the fixed die 10, the seat surface 10a is formed at one end of the sprue bush 11, and the air cooling hole 16 is formed by the sprue bush. The thermocouple 31 is formed inside the vicinity of the seating surface 10 a of the bush 11, and detects the temperature near the seating surface 10 a of the sprue bush 11. In this way, the heat capacity of the sprue bush 11 is smaller than that of the whole fixed mold 10, and the sprue bush 11 is fixed to the fixed mold 10, but its joint portion has considerable heat transfer resistance. Therefore, the temperature near the seating surface 10a of the sprue bush 11 is controlled by controlling the flow rate of the cooling air supplied to the air cooling hole 16 formed inside the vicinity of the seating surface 10a of the sprue bush 11 by the air flow rate control device 30, The above-mentioned predetermined temperature is maintained with a small control delay. As a result, the temperature of the tip of the nozzle 22 is stabilized, and the plug P formed at the tip of the discharge hole 22a becomes more stable, so that the yield and quality of the cast product are further improved, and the inside of the nozzle 22 is improved. The risk of the molten metal M leaking further decreases. However, the present invention is not limited to this. The sprue 15 is formed directly on the fixed die 10, the air cooling hole 16 is formed inside the fixed die 10 near the seating surface 10a, and the thermocouple 31 is formed on the seating surface 10a. The temperature may be detected by detecting the temperature of the nearby mold 10. This also makes the plug P formed at the tip of the discharge hole 22 a of the nozzle 22 more stable than before. In addition, the yield and quality of the cast product can be improved, and the possibility that the molten metal M in the nozzle 22 leaks can be reduced.
[0025]
Further, in the above-described embodiment, air is used as the cooling medium that cools the vicinity of the seating surface 10a with which the tip of the nozzle 22 is in contact, so that the air has a small heat capacity and therefore generates heat near the air cooling hole 16. Since the stress is reduced, it is possible to reduce troubles such as cracks caused by thermal stress in the vicinity thereof, and it is very easy to implement. However, the present invention is not limited to this, and it is also possible to use a gas other than air or a liquid such as water or oil as a cooling medium passing through the cooling medium hole 16.
[0026]
The temperature near the seating surface 10a of the fixed die 10 may be detected not only by a thermocouple but also by using a thermistor or another temperature sensor 31.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an entire structure of an embodiment of a molding die apparatus according to the present invention.
FIG. 2 is a cross-sectional view showing the overall structure of an example of a molding apparatus according to the related art.
[Explanation of symbols]
10, 12: mold (fixed type, movable type), 10a: seat surface, 11: sprue bush, 13: cavity, 15: sprue, 16: cooling medium hole (air cooling hole), 20: injection device, 22 ... Nozzle, 30: cooling medium control device (air flow control device), 31: temperature sensor (thermocouple), M: molten metal, P: plug.

Claims (3)

A pair of dies which are close to and separated from each other, a cavity formed between the two dies which are closely joined together, one end of which is formed in one of the dies, and one end of which is formed on the outer surface of the same die. A sprue having an opening at the formed seat surface and the other end communicating with the cavity is provided, and the molten metal injected from the tip of the nozzle of the injection device abutting on the seat surface is filled into the cavity via the sprue. In the molding die apparatus to be
A cooling medium hole formed inside the mold near the bearing surface;
A temperature sensor for detecting a temperature near the bearing surface of the mold;
A cooling medium control device for controlling a flow rate of a cooling medium supplied to the cooling medium hole such that a temperature near the seat surface detected by the temperature sensor becomes a substantially constant predetermined temperature. Molding equipment for molding. The molding die device according to claim 1,
The sprue is formed by an inner surface of a separate sprue bush fixed in the mold,
The seat surface is formed at one end of the sprue bush,
The cooling medium hole is formed inside the vicinity of the seat surface of the sprue bush,
The molding die device, wherein the temperature sensor detects a temperature near the seat surface of the sprue bush. The molding die device according to claim 1 or 2,
A molding die apparatus, wherein the cooling medium is air.

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