JP2002254154A - Low pressure casting method and low pressure casting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low pressure casting method and a low pressure casting device capable of contriving enhancement in work efficiency by appropriately setting the molten metal pouring time and solidifying time, and obtaining improvement in the quality of a casting. SOLUTION: A stoke 33, a metal mold 40 formed with a continuous cavity 45 on the upper face of the stoke 33 through a gate 46, a molten metal feeding device 15 for filling a molten metal 60 and holding a filling pressure in the cavity 45 through the stoke 33 and a thermoelectric thermometer 49 for measuring the temperature of a temperature measuring point a, set at the gate 46, are provided, and at the time point where the thermoelectric thermo-meter 49 detects the previously set temperature at the time point where the solidification of the molten metal 60 filled in the cavity 45 proceeds to the gate 46, the filling pressure is released, and at the time point where the thermoelectric thermometer detects the previously set temperature of mold opening, the mold opening is performed to take out the casting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a low-pressure casting method and a low-pressure casting apparatus.

[0002]

2. Description of the Related Art For example, for casting of aluminum alloy or the like,
Low-pressure casting is widely used because it can be mass-produced, has a reasonable solidification process, has good dimensional accuracy, and has relatively low equipment costs.

The outline of the low pressure casting method will be described with reference to a conceptual diagram of a low pressure casting apparatus 100 shown in FIG.

[0004] The low-pressure casting apparatus 100 includes a molten metal warming furnace 101.
The crucible 102 held in the crucible 102, a crucible lid 103 for sealing the crucible 102, a stalk 104 passing through the crucible lid 103, and having a lower end extending into the crucible 102, and a crucible 104 installed above the stalk 104. In addition, the molten metal holding crucible 102 is provided with a molten metal supply port and a compressed air inlet pipe (not shown).

[0005] In casting, a predetermined amount of molten metal 120 is poured into the molten metal holding crucible 102 sealed by the crucible lid 103 from the molten metal supply port, and the molten metal supply port is closed with a lid or the like to prepare.

Next, a gas body having a relatively smaller pressure than the compressed air inlet pipe, for example, compressed air is supplied to the molten metal surface 120a.
Is pressurized, and the molten metal 120 is stoke 1
04 through the cavity 106 of the mold 105
Pour the water inside. Molten metal 1 filled in cavity 106
20 begins to solidify from the upper end of the cavity 106, gradually descends, and the gate 106a finally solidifies. Gate 1
The pressing force in the molten metal holding crucible 102 is maintained by the gas body until the solidification is completed up to the portion 06a, and the pressurization is released when the solidification is completed up to the gate 106a. Further, after the temperature of the casting decreases to a temperature at which deformation and galling does not occur even when the mold is opened and the mold 105 is released by solidification, the mold is released from the mold 105 and the casting is carried out as a casting.

[0007] From the start of pouring into the cavity 106 due to the pressurization of the molten metal surface 120a, the molten metal 120 is discharged from the gate 106a.
The time until the solidification until the filling pressure is released is the time of hot water supply, and the temperature of the casting is further reduced to a temperature at which the solidified casting does not deform or seize when the mold 105 is opened and released. The time to fall is called the coagulation time.

[0008] The setting of the pouring time and the solidification time is as follows.
Based on the time experimentally confirmed in advance, it is set artificially for each casting based on the experience and feeling of the casting operator.

[0009] On the other hand, the molten metal 120 stored in the molten metal holding crucible 102 is subjected to each of (a) and (b) of FIG.
As shown in (b) and (c), the molten metal 120 decreases every time it is cast, and the molten metal surface 120a gradually decreases. A pressure for applying a pressure corresponding to the difference h of the surface 120a for each casting, that is, a filling pressure is controlled.

[0010] For example, as shown in FIG. 9, a pressurizing value for each casting based on a calculated value is stored in a personal computer 107 or the like as shown in FIG.
The on / off valve 109 is controlled by the
There is a method in which the pressure gas supplied from 0 is automatically adjusted and pressurized.

[0011]

SUMMARY OF THE INVENTION The above low pressure casting apparatus 10
According to No. 0, the casting of the mold 105 in the cavity 106 is gradually performed, and the molten metal 120 that has flowed in first is pushed by the molten metal 120 that has been pushed up later and flows to the tip. Solidification suppresses the occurrence of shrinkage cavities and blowholes, so that a dense casting with high density can be obtained.

However, from the start of pouring into the cavity 106 due to the pressurization of the molten metal surface 120a, the molten metal 120
Hot water supply time until solidification up to 6a and release of filling pressure,
The setting of the solidification time until the temperature of the casting decreases to a temperature at which no deformation or galling occurs even when the solidified casting opens the mold 105 and releases the mold, based on the time experimentally confirmed in advance, Since each casting is set artificially based on the experience and feeling of the casting operator, the setting of the hot water supply time and the solidification time has individual differences among the casting operators. Further, in actual casting, there is a difference in solidification rate for each casting cycle.

The setting of the pouring time is not appropriate,
If the filling pressure is released in a state where the portion 06a is not completely coagulated, a sufficient hot water feeding effect cannot be obtained, and a nest is generated at the gate 106a. If the pouring time is set long in order to avoid the occurrence of nests, there is a concern that a longer time than the time required for true coagulation is set and the work efficiency is reduced. Also, if an unnecessarily long time is set, the molten metal 120
The heat of the mold 105 received from the mold may be radiated, and the temperature of the mold necessary for casting a good product may change, thereby affecting the quality of the cast product.

On the other hand, if the setting of the solidification time is not appropriate and the temperature for releasing the mold is too high, the cast product may be seized or deformed, and if the temperature for releasing the mold is too low, the release may be difficult. I am concerned.

Accordingly, an object of the present invention, which has been made in view of the above points, is to improve the working efficiency by appropriately setting the pouring time and the solidification time without human intervention, and to improve the quality of a cast product. An object of the present invention is to provide a low-pressure casting method and a low-pressure casting device.

[0016]

According to a first aspect of the present invention, there is provided a low-pressure casting method according to the first aspect of the present invention, wherein a stalk extending vertically and a continuous cavity formed at the upper end of the stalk via a sprue. Having a molten metal supply device that fills the cavity with the molten metal from the molten metal holding crucible via the stalk and holds the filling pressure,
The cavity is filled with the molten metal via the stalk by the molten metal supply device, and while maintaining the filling pressure, the filling pressure is released at the time of solidification of the gate, and after the solidification time has elapsed, the mold is opened to take out the cast product. In the low-pressure casting method, when the temperature at the temperature measurement point set in the sprue reaches the temperature at which solidification of the molten metal filled in the cavity proceeds to the sprue, the filling pressure is released. Is performed.

According to the first aspect of the present invention, the temperature at the temperature measurement point set in the gate is determined by the temperature at the temperature measurement point when the molten metal filled in the cavity starts solidifying from the upper end and proceeds to the gate. It becomes possible to release the filling pressure by the molten metal supply device when the temperature reaches a set temperature that has been experimentally confirmed in advance. As a result, the pouring time is released when the sprue portion has solidified, and an appropriate pouring time is set without excess or deficiency without human intervention, so that a proper pouring effect is obtained. In this case, the occurrence of nests can be avoided, and the mold temperature required for casting a good product can be maintained to ensure the quality of the cast product and improve the working efficiency.

The invention of the low pressure casting method according to claim 2 is
A stalk extending vertically, a mold having a cavity formed at the upper end of the stalk via a sprue, and filling the cavity with the molten metal from the molten metal holding crucible via the stalk and the filling pressure. And the molten metal supply device fills the cavity through the stalk with the molten metal and holds the filling pressure, releases the filling pressure at the time of solidification of the sprue portion, and solidifies the molten metal. In the low-pressure casting method in which the mold is opened and the cast product is taken out after a lapse of time, the mold opening is performed when the temperature at the temperature measurement point set in the gate reaches a preset mold opening time. It is characterized by.

According to the second aspect of the present invention, the temperature at the temperature measuring point set in the gate is a temperature at which the solidification proceeds and the casting does not deform or seize even when the mold is released. The temperature at the temperature measurement point at the time when the temperature has dropped to is checked experimentally in advance, and when the temperature reaches the set temperature, the mold can be opened. The temperature at the time of molding is appropriately set, so that galling and deformation occurring in the cast product can be avoided, and the mold is easily released, the quality of the cast product can be ensured, and the working efficiency is improved.

According to a third aspect of the present invention, in the low pressure casting method according to the first or second aspect, the temperature measuring point is:
It is characterized in that it is set in the cavity instead of in the gate.

According to the third aspect of the present invention, even when the temperature measurement point cannot be set in the gate due to the shape of the casting, the temperature set point can be easily set.

The invention of the low pressure casting apparatus according to claim 4 is as follows.
A stalk extending vertically, a mold having a cavity formed at the upper end of the stalk via a sprue, and filling the cavity with the molten metal from the molten metal holding crucible via the stalk and the filling pressure. And the molten metal supply device fills the cavity through the stalk with the molten metal and holds the filling pressure, releases the filling pressure at the time of solidification of the sprue portion, and solidifies the molten metal. In the low-pressure casting apparatus for removing the casting by opening the mold after a lapse of time, the apparatus further includes temperature measuring means for measuring the temperature of the temperature measuring point set in the gate, and the temperature measuring means is set in advance. The filling pressure is released when the temperature at the temperature measurement point when the solidification of the molten metal filled in the cavity progresses to the gate is detected.

According to the fourth aspect of the present invention, the temperature measuring means for measuring the temperature at the temperature measuring point in the sprue performs an experiment on the temperature at the temperature measuring point when the solidification of the molten metal filled in the cavity has progressed to the sprue. The filling pressure can be released at the time when the set temperature is detected by confirming the temperature, and the pouring time is released at the time when the gate portion is solidified. As in the above case, the quality of the cast product can be ensured and the operation efficiency can be improved.

According to a fifth aspect of the present invention, there is provided a low-pressure casting apparatus.
A stalk extending vertically, a mold having a cavity formed at the upper end of the stalk via a sprue, and filling the cavity with the molten metal from the molten metal holding crucible via the stalk and the filling pressure. And the molten metal supply device fills the cavity through the stalk with the molten metal and holds the filling pressure, releases the filling pressure at the time of solidification of the sprue portion, and solidifies the molten metal. In the low-pressure casting apparatus for removing the casting by opening the mold after a lapse of time, the apparatus further includes temperature measuring means for measuring the temperature of the temperature measuring point set in the gate, and the temperature measuring means is set in advance. The mold is opened when the temperature at the temperature measurement point at the time of opening the mold is detected.

According to the fifth aspect of the present invention, the temperature measuring means for measuring the temperature at the temperature measuring point in the gate is characterized in that the solidification proceeds and the casting becomes deformed or galling even if the mold is released. The temperature at the temperature measurement point when the temperature drops to a temperature that does not occur is experimentally confirmed in advance, and when the set temperature is detected, the mold can be opened, and the appropriate coagulation time can be set independently of humans As a result, the quality of the cast product can be ensured and the work efficiency can be improved as in the second aspect of the invention.

According to a sixth aspect of the present invention, in the low pressure casting apparatus of the fourth or fifth aspect, the temperature measuring point of the temperature measuring means is set in a cavity instead of in a gate.

According to the sixth aspect of the present invention, even when the temperature measuring point of the temperature measuring means cannot be set in the gate due to the shape of the casting, the temperature set point can be easily set.

According to a seventh aspect of the present invention, in the low pressure casting apparatus according to any one of the fourth to sixth aspects, the temperature measuring means is provided on a die casting pin, and is provided near a tip of the die casting pin. It is a thermoelectric thermometer in which the temperature measurement points are set.

According to the seventh aspect of the present invention, by providing the thermoelectric thermometer on the cast pin, the temperature measuring means can be formed without complicating the structure of the mold.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a low-pressure casting method and a low-pressure casting apparatus according to the present invention will be described below with reference to FIGS.

FIG. 1 is a conceptual diagram of a low-pressure casting apparatus 1 provided with a holding furnace 10 and a casting machine 30, FIG. 2 is a schematic view of a main part of the low-pressure casting apparatus 1, and FIG. 2 is an enlarged view of a part A, and FIG. 4 is an enlarged view of a part B of FIG.

The holding furnace 10 has a melt holding crucible 12 which is supported by the melt holding furnace 11 and holds the melt 60. The melt feeder 15 is suspended by a support frame 13 provided above the melt holding crucible 12. Supported.

As shown in FIGS. 2 and 3, the molten metal supply device 15 has a base 16 suspended from and supported by a support frame 13, the upper end of which is supported in a closed state, and the lower part of which is stored in a crucible 12 holding the molten metal. A bottomed cylindrical pressure pot 17 immersed in a molten metal 60 of an alloy is provided.

At the bottom of the pressurizing pot 17, a suction port 17a communicating with the inside of the molten metal holding crucible 12 is formed. At the side of the pressure pot 17, the base end of a hot water supply pipe 19 whose leading end communicates with the stalk 33 of the casting machine 30 via the base 16 is inserted, and a discharge port 19a formed in the hot water supply pipe 19 is added. It is open in the pressure pot 17. The suction port 17a and the discharge port 19a are opened and closed by a suction port valve 18 and a discharge port valve 20 provided in the pressurizing pot 17, respectively.

Further, a vacuum pump 22 for reducing the pressure in the pressurizing pot 17 through a suction and air supply pipe 21 and a pressurizing pot 17 through the suction and air supply pipe 21 are connected to the melt supply device 15.
A pressurized pump 23 for pressurizing by sending a pressurized gas body, in this embodiment, compressed air therein, and the like. I have.

The pressing pot 17 is provided inside the pressing pot 17.
A level sensor (not shown) for detecting the liquid level of the melt 60 in the melt 7 is provided. The operation of each of the suction port-side valve element 18, the discharge port-side valve element 20, the vacuum pump 22 and the pressurizing pump 23 is controlled by a control unit (not shown).

On the other hand, the casting machine 30 has a cylindrical stalk 33 having an upper end attached to a base 31 via a stalk plate 32 and extending in a vertical direction. The leading end of the hot water supply pipe 19 is connected.

A mold 40 is provided above the stalk 33. As shown in FIGS. 4 and 5, the mold 40 in the present embodiment includes a lower mold 41 fastened to the stalk plate 32 by bolts and the like, and a mold operating mechanism 50 (see FIG. 1) such as a hydraulic cylinder. An upper mold 42 that is vertically movable so as to be capable of moving toward and away from the lower mold 41, and a pair of horizontal molds 43 that are provided on the die base 34 of the base 31 and that can move in the horizontal direction and move toward and away from each other by a mold operating mechanism 50; The cavity 45 is formed by each cavity side 41a, 42a, 43a, 44a of the lower mold 41, the upper mold 42, and the horizontal molds 43, 44.

The lower die 41 extends vertically to communicate the stalk 33 side with the cavity 45 side, and has a relatively small opening area in the middle portion, and gradually increases as the opening area moves upward and downward. Are formed.

On the other hand, the upper mold 42 penetrates vertically as shown in an enlarged view of the main part of the mold 40 in FIG. 5, and has an upper large-diameter portion 47b and a lower small-diameter portion 47c through a step 47a. Is formed.

The molding pin 48 is provided with a molding pin mounting hole 47.
Large diameter portion 4 via a step portion 48a that can be locked to the step portion 47a of
7b and a relatively large-diameter base portion 48b and a small-diameter portion 47c
The shaft portion 48c is inserted into the cast pin mounting hole 47 from above, and the step portion 48a contacts the step portion 47a of the cast pin insertion hole 47 so that the shaft portion 48c is The tip 48d has a length that penetrates through the cavity 45 and reaches the upper part of the gate 46 of the lower die 42, and is held at a predetermined mounting position by being fitted into the cast pin mounting hole 47.

A temperature measuring means, for example, a thermocouple 49 with a thermocouple, in which a temperature measuring point a is set corresponding to the vicinity of the tip of the cast pin 48, is installed in the cast pin 48. By mounting in the cast pin mounting hole 47, the temperature at the upper position in the gate 46 can be measured.
Further, the thermoelectric thermometer 49 can be provided without complicating the configuration of the mold 40 by providing the thermoelectric thermometer 49 inside the cast pin 48.

The temperature at the temperature measuring point a is Stoke 33
Since the melt surface 60a of the melt 60 in the inside rises and rises as it approaches the temperature measurement point a, the temperature of the temperature measurement point a on the melt surface 60a at a predetermined position is experimentally obtained in advance, so that the temperature in the stalk 33 is increased. The position of the molten metal surface 60a,
For example, the molten metal surface 60 raised to a constant molten metal surface position L described later.
The position of a can be detected. That is, the thermoelectric thermometer 49 functions as a molten metal surface position sensor, and the thermoelectric thermometer 4
9 is sent to a control unit provided in the molten metal supply device 15 as a molten metal surface detection signal.

Since the temperature at the temperature measuring point a reaches the highest value due to the heat of the molten metal 60 poured into the cavity 45, the molten metal 60 gradually drops from the upper end as the solidification starts. The temperature of the temperature measurement point a at the time when the solidification has progressed to the gate 46 is experimentally confirmed and set in advance, and when the set temperature is detected, the thermoelectric thermometer 49 outputs a pouring time release signal as a signal. Send to control unit. Further, the temperature at the temperature measurement point a continues to drop as the solidification proceeds, and the temperature at the time when the solidified and cast product drops to a temperature at which deformation and galling does not occur even when the mold 40 is released. Is experimentally confirmed and set in advance, and when this temperature is detected, an electric signal is sent from the thermoelectric thermometer 49 to the control unit as a coagulation time release signal.

The base 16 of the holding furnace 10 and the casting machine 30
The outer periphery of the hot water supply pipe 19 disposed between the stalks 33 is heated and kept warm by covering the outer periphery thereof with the heater 51 for the hot water supply pipe, and the stalk 33 is also heated and kept warm with the outer periphery covered by the heater 52 for stalk. This hot water pipe heater 5
The 1 and Stoke heaters 52 can also be formed by integral heaters.

Next, the casting method using the low-pressure casting apparatus 1 configured as described above will be described with reference to the flow chart of the filling operation shown in FIG. 6, the filling operation and the repetitive filling operation shown in FIG. 7, and the casting cycle shown in FIG. This will be described with reference to the drawings.

The molten metal 60 in the cavity 45 of the mold 40
Prior to the pouring of the molten metal, filling is performed until the molten metal surface 60a reaches a predetermined height position of the stalk 33 of the casting machine 30, for example, a fixed metal surface position L set at an upper end or a position near the upper end of the stalk 33.

The hot water filling operation will be described with reference to a hot water filling operation flowchart shown in FIG.

The molten metal 60 in which the aluminum alloy is melted is poured into the molten metal holding crucible 12 of the holding furnace 10 in advance, and the molten metal 60 is stored and prepared in a predetermined amount.

In response to an instruction from the control section, the discharge port side valve element 20
Thereby, the discharge port 19a opened at the base end of the hot water supply pipe 19 is closed (Step S1). Subsequently, the suction port 17a at the bottom of the pressurized pot 17 closed by the suction port side valve body 18 is opened to communicate the inside of the molten metal holding crucible 12 and the pressurized pot 17 (step S2).

Next, the inside of the pressurizing pot 17 is depressurized by the vacuum pump 22 through the suction / air supply pipe 21 and the suction port 17 a
The molten metal 60 in the molten metal holding crucible 12 from the pressure pot 17
(Step 3). Pressurized pot 1
When the level sensor detects that the molten metal 60 has been sucked up to the vicinity of the upper end of 7, the pressure in the pressurizing pot 17 by the vacuum pump 22 is stopped, and the suction port 17 a is closed by the suction side valve element 18. (Step S4).

Next, compressed air is supplied into the pressurizing pot 17 from the suction and air supply pipe 21 by the pressurizing pump 23 to pressurize the molten metal surface in the pressurizing pot 17 and closed by the discharge port side valve element 20. The opened discharge port 19a is opened (step S
5) The molten metal 60 in the pressure pot 17 is pushed up through the hot water supply pipe 19 to a constant molten metal surface position L set at the upper end or a position near the upper end of the stalk 33 (step S6). The pressure at which the molten metal 60 is pushed up to the constant molten metal surface position L at this time is defined as the constant molten metal surface pressure.

When the molten metal 60 is pushed up to the constant molten metal surface position L, the molten metal surface 60a in the stalk 33 is gradually moved to the temperature measurement point a of the thermoelectric thermometer 49 provided on the casting pin 48 as the molten metal 60 is pushed up. Approaching, the temperature at the temperature measurement point a rises as shown in the explanatory diagram of the casting cycle in FIG.
The thermoelectric thermometer 4 indicates that the temperature has reached the temperature A at which the molten metal surface 60a is located at the constant molten metal surface position L obtained experimentally in advance.
9 to be detected.

The thermoelectric thermometer 49 calculates the constant molten metal surface position L.
When the molten metal surface 60a which has been pushed up is detected (Step S7), the molten metal surface detection signal is sent from the thermoelectric thermometer 49 to the control unit, and the pressurizing in the pressurizing pot 17 by the pressurizing pump 23 is stopped. At the same time, the discharge port 19a is closed by the discharge port side valve body 20 to prevent the backflow of the molten metal 60 from the stalk 33 and maintain the constant molten metal surface pressure to maintain the molten metal surface 60a at the constant molten metal surface position L ( Step S
8).

Subsequent to the filling operation from step 1 to step 8, a filling operation for filling the cavity 45 of the mold 40 with the molten metal 60 is started.

Next, the filling operation will be described with reference to a flowchart of the filling operation and the repetitive filling operation shown in FIG. 7 and an explanatory view of the casting cycle shown in FIG.

The discharge port 19a is closed by the discharge port side valve element 20 and the molten metal surface 60a from the stalk 33 is held at the constant molten metal surface position L (step S11), and is closed by the suction port side valve element 18. The suction port 17a is opened to release the constant molten metal surface pressure in the pressure pot 17 (step S12).

Next, the inside of the pressurizing pot 17 is depressurized by the vacuum pump 22 through the suction and air supply pipe 21, and
The molten metal 60 for one casting of the cavity 45 is sucked into the pressure pot 17 from a (step S13). Pressurized pot 1
When the molten metal 60 for one casting is sucked into 7, the vacuum pump 2
2, the suction port 17a is closed by the suction port side valve element 18 (step S14). The amount of molten metal for one casting which is sucked and supplied to the pressurizing pot 17 is experimentally determined in advance, and the level sensor provided in the pressurizing pot 17 detects the suction up to a certain position to secure a certain amount. I do.

Subsequently, compressed air is supplied from the suction / air supply pipe 21 into the pressurizing pot 17 by the pressurizing pump 23 to pressurize the molten metal surface, and the discharge port 19 a closed by the discharge port side valve element 20. Is opened (step S15). The molten metal 60 is pressure-fed into the stalk 33 from the opened discharge port 19a through the hot water supply pipe 19 to push up the molten metal surface 60a to fill the cavity 45 and maintain the filling pressure (step S16). Due to the heat of the molten metal 60 filled in the cavity 45, the temperature of the temperature measuring point a set on the casting pin 48 starts to rise as shown in FIG.
The temperature detected by the thermoelectric thermometer 49 increases.

After the temperature of the temperature measuring point a reaches the highest point, for example, 600 ° C., due to the heat of the molten metal, the molten metal 60 filled in the cavity 45 starts to solidify from the upper end, and the temperature is measured as the solidification progresses. The temperature at point a begins to drop.

When the solidification has progressed to the gate 46, and the thermoelectric thermometer 49 detects a temperature, for example, 530 ° C., which has dropped to the temperature at the time when the solidification has progressed to the preset temperature measurement point a (step S17). Then, an electric signal is sent from the thermoelectric thermometer 49 as a pouring time release signal, the pressurization in the pressurizing pot 17 by the pressurizing pump 23 is stopped to release the filling pressure, and at the same time, the discharge port 19a is set to the discharge port side valve. It is closed by the body 20 to prevent the backflow of the molten metal 60 from the stalk 33 and to maintain a constant molten metal surface pressure, thereby making the molten metal surface 60 a
Is held at the constant molten metal surface position L (step S18).

Further, the solidification in the cavity 45 progresses, and the temperature at the temperature measuring point a continues to drop, so that the solidified casting does not deform or seize even if the mold 40 is released. When the thermoelectric thermometer 49 detects a temperature, for example, 490 ° C., the thermoelectric thermometer 49 sends an electric signal to the control unit as a coagulation time release signal, and the mold operating mechanism 50 or the like causes the mold 4 to move.
0 is opened, the casting solidified in the cavity 45 is taken out, and one casting cycle ends (step S19). Thereafter, the mold 40 is closed and the next molten metal filling standby state is set.

The subsequent repetitive filling operation is performed by the discharge side valve body 20.
The discharge port 19a is closed by the
In a state where the pressure 0a is held at the constant molten metal surface position L, the suction port 17a is opened by the suction port side valve element 18 to release the constant molten metal surface pressure in the pressurizing pot 17, and the mold 4
Opening 0, the mold 40 is closed via the step S19 for taking out the solidified casting in the cavity 45, and the steps from step S11 to step S19 are set to the next molten metal filling standby state.

According to the low-pressure casting method and the low-pressure casting apparatus 1, the temperature of the temperature measuring point a at the time when the molten metal 60 filled in the cavity 45 starts to solidify from the upper end and proceeds to the gate 46 is experimentally confirmed in advance. When the temperature of the temperature measuring point a reaches the temperature at which the gate 46 has solidified, the thermoelectric thermometer 49 sends a signal as a pouring time release signal to the control unit to release the maintenance of the filling pressure. Tate 4
The pouring time can be released when the part 6 has solidified. As a result, an appropriate pouring time is set without excess or deficiency without any human intervention, an appropriate pouring effect is obtained, the occurrence of nests at the spout 46 can be avoided, and it is necessary to cast a good product. The mold temperature is maintained at a high level, the quality of the cast product can be ensured, and the working efficiency is improved.

Similarly, the temperature at the temperature measurement point a at the time when the solidification proceeds and solidifies to form a casting falls to a temperature at which deformation and galling does not occur even when the mold 40 is released. It is confirmed experimentally in advance and set, and when the set temperature is reached, the thermoelectric thermometer 49 issues an electric signal to the control unit as a coagulation time release signal to open the mold, so that the mold is opened without human intervention. The solidification time is set, the temperature at the time of mold release is set appropriately, and galling and deformation occurring in the cast product can be avoided, the mold release is easy, the quality of the cast product can be ensured and the work efficiency is improved I do.

Further, the backflow from the stalk 33 is prevented so that the molten metal surface 60 a in the stalk 33 is located immediately below the cavity 45.
Is maintained at the constant molten metal surface position L, and the molten metal supply device 15
Surface 60a in Stoke 33 by molten metal 60
Is pushed up to fill the cavity 45 and casting is performed, so that the distance from the constant molten metal surface position L to the cavity 45 in each casting cycle is constant, and the molten metal surface in the stalk 33 by the molten metal supply device 15 in each casting cycle. The filling pressure for filling the cavity 45 by pushing up 60a becomes constant, so that it is not necessary to increase the filling pressure for each casting as in the conventional low-pressure casting, and the operation control of the low-pressure casting apparatus 1 can be simplified. Further, due to the constant molten metal surface position L, the distance from the molten metal surface 60a to the cavity 45 is close, the moving distance of the molten metal 60 from the constant molten metal surface position L to the cavity 45 is short, and the temperature drop of the molten metal 60 during filling is suppressed. The fluidity of the molten metal at the time of filling is good, and the flowability of the molten metal is excellent, the moving time of the molten metal 60 at the time of filling is short, and the time of exposure to the air in the stalk 33 is short. The deterioration of the quality of the cast product due to the entanglement is avoided.

The present invention is not limited to the above embodiment, but can be variously modified without departing from the gist of the present invention. For example, when the tip 48d of the cast pin 48 does not reach the gate 46 due to the shape of the casting, the temperature measurement point a of the thermoelectric thermometer 49 can be set in the cavity 45. The thermometer 49 can be arranged near the gate 46 of the lower die 41 without being arranged on the cast pin 48.

Further, depending on the shape and thickness of the casting, the mold 4
0, a cooling water passage is formed, and a cavity 45 is formed by the cooling water.
It is also possible to control the rate of solidification in the interior. Further, a wire net formed in the lower mold 41 can be provided with a wire net that removes oxides and impurities generated in the melting process of the molten metal and mixed in the molten metal and suppresses rising disturbance of the molten metal. . In addition to casting of aluminum alloy, casting of high melting point alloy such as copper and iron is also possible.

[0069]

According to the low-pressure casting method and the low-pressure casting apparatus described above, the temperature of the temperature measuring point set in the gate of the mold or the cavity is changed so that the molten metal previously filled in the cavity starts to solidify from the upper end. The temperature at the temperature measurement point at the time of proceeding to the gate is experimentally confirmed and set, and when the set temperature is reached, the filling pressure can be released, and the part of the gate becomes true. At the time of solidification, the pouring time is released, an appropriate pouring time is set, an appropriate pouring effect is obtained, the occurrence of nests at the gate is avoided, and a good product is cast. As a result, the quality of the cast product can be ensured and the working efficiency can be improved.

Further, the temperature at the temperature measuring point set in the gate or the cavity is set at the time when the temperature of the casting, which has been solidified to a point, does not cause deformation or galling even when the mold is released. The temperature of the temperature measurement is confirmed experimentally in advance and set, and when it reaches this temperature, it becomes possible to open the mold. Is properly set, thereby avoiding galling and deformation occurring in the cast product, and the mold release is facilitated, the quality of the cast product can be ensured, and the working efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a low-pressure casting apparatus showing an outline of an embodiment of a low-pressure casting method and a low-pressure casting apparatus according to the present invention.

FIG. 2 is a schematic view of a main part of the low-pressure casting apparatus.

3 is an enlarged view of a part A of FIG. 2 showing a main part of the molten metal holding furnace.

FIG. 4 is an enlarged view of a portion B of FIG. 2 showing a main part of the casting machine.

FIG. 5 is a sectional view showing a main part of the mold.

FIG. 6 is also a flowchart of a hot water filling operation.

FIG. 7 is a flowchart showing a filling operation and a repeated filling operation.

FIG. 8 is an explanatory view of a casting cycle.

FIG. 9 is a conceptual diagram of a conventional low pressure casting apparatus.

FIG. 10 is an explanatory view showing a decrease in molten metal level of a conventional low-pressure casting apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Low pressure casting apparatus 10 Holding furnace 12 Melt holding crucible 15 Melt supply device 17 Pressurization pot 19 Hot water supply pipe 24 Pressurization pot decompression pressurization means 30 Casting machine 33 Stoke 40 Mold 41a, 42a, 43a, 44a Cavity side 45 Cavity 46 Gate 47 Casting pin mounting hole 48 Casting pin 49 Thermoelectric thermometer (temperature measuring means) 60 Melt 60a Melt surface a Temperature measurement point L Constant melt surface position

Claims (7)

[Claims] 1. A mold having a stalk extending in the vertical direction, a mold having a continuous cavity formed at the upper end of the stalk via a sprue, and filling the molten metal into the cavity from the molten metal holding crucible via the stalk. And a molten metal supply device for holding the filling pressure, filling the molten metal into the cavity via the stalk by the molten metal supply device and holding the filling pressure, and increasing the filling pressure at the time of solidification of the sprue portion. In the low-pressure casting method of releasing the mold and opening the mold after the elapse of the solidification time to remove the cast product, the temperature at the temperature measurement point set in the gate is set by the solidification of the molten metal filled in the cavity set in advance. A low-pressure casting method, wherein the filling pressure is released when the temperature at which the process has proceeded to is reached. 2. A mold having a stalk extending in the vertical direction, a mold having a continuous cavity formed at the upper end of the stalk via a sprue, and filling the molten metal into the cavity from the molten metal holding crucible via the stalk. And a molten metal supply device for holding the filling pressure, filling the molten metal into the cavity via the stalk by the molten metal supply device and holding the filling pressure, and increasing the filling pressure at the time of solidification of the sprue portion. In the low-pressure casting method of releasing, and opening the mold after the elapse of the solidification time, and taking out the cast product, the temperature at the temperature measurement point set in the gate is set to the temperature at the preset mold opening time, A low pressure casting method characterized by performing mold opening. 3. The low pressure casting method according to claim 1, wherein the temperature measurement point is set in a cavity instead of in a gate. 4. A mold having a vertically extending stalk, a mold having a continuous cavity formed at the upper end of the stalk via a sprue, and filling the molten metal into the cavity from the molten metal holding crucible via the stalk. And a molten metal supply device for holding the filling pressure, filling the molten metal into the cavity via the stalk by the molten metal supply device and holding the filling pressure, and increasing the filling pressure at the time of solidification of the sprue portion. A low-pressure casting apparatus which releases the mold and opens the mold after the elapse of the solidification time to take out a cast product, further comprising a temperature measuring means for measuring the temperature of a temperature measuring point set in the gate, wherein the temperature measuring means is provided. Releasing the filling pressure at the time when the temperature of the temperature measuring point at the time when the solidification of the molten metal filled in the preset cavity has progressed to the gate is detected. Casting apparatus. 5. A stalk extending in a vertical direction, a mold having a cavity formed at the upper end of the stalk via a sprue, and filling the molten metal into the cavity from the molten metal holding crucible via the stalk. And a molten metal supply device for holding the filling pressure, filling the molten metal into the cavity via the stalk by the molten metal supply device and holding the filling pressure, and increasing the filling pressure at the time of solidification of the sprue portion. A low-pressure casting apparatus which releases the mold and opens the mold after the elapse of the solidification time to take out a cast product, further comprising a temperature measuring means for measuring the temperature of a temperature measuring point set in the gate, wherein the temperature measuring means is provided. A low-pressure casting apparatus wherein the mold is opened when a temperature at a temperature measurement point at a preset mold opening time is detected. 6. The low-pressure casting apparatus according to claim 4, wherein the temperature measuring point of the temperature measuring means is set in a cavity instead of the gate. 7. The thermometer according to claim 4, wherein said temperature measuring means is a thermoelectric thermometer provided on a die casting pin, wherein said temperature measuring point is set near a tip of said die casting pin. 7. The low-pressure casting apparatus according to any one of claims 6 to 6.