JP3184372B2 - Low pressure casting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved low pressure casting method.

[0002]

2. Description of the Related Art For example, when mass-producing a cylinder head for an automobile engine, a low-pressure casting method is widely used. In this low-pressure casting method, in a state in which a molten metal made of a light alloy such as an aluminum alloy is heated and held in a sealed container, the surface of the molten metal is pressed by an inert gas or air at a relatively low pressure to push up the molten metal, and this pushing up is performed. In this method, the molten metal is filled into the cavity of the casting mold via stalk to perform casting.

In this case, it is desirable to pressurize the surface of the molten metal rapidly in order to prevent the temperature of the molten metal from lowering until the molten metal rises in the stalk and reaches the gate of the mold. It is desirable to press the molten metal surface with an appropriate pressure determined by the shape of the cast product, etc. from the start of filling to the filling, and furthermore, after the molten metal is filled into the cavity, the molten metal is placed in a good state It is desirable to pressurize the molten metal surface with a high pressure in order to coagulate at the temperature.

For this reason, conventionally, a pressurizing pattern indicating a pressure change state with respect to time is set in advance, and variable control of the pressure for pressurizing the molten metal surface is performed based on the pressurizing pattern. In this case, for example,
As disclosed in Japanese Patent Publication No. 51, the mold temperature and the melt temperature at the time of starting the pressurized filling of the melt into the cavity of the casting mold are detected, and then the correspondence between the mold temperature and the melt temperature is detected. Then, an optimal molten metal pressurizing pattern and a mold cooling pattern are selected from a plurality of molten metal pressurizing patterns and mold cooling patterns which are set in advance, and the molten metal is pressurized based on the selected molten metal pressurizing pattern. Is filled in the cavity and held under pressure, and the flow rate of the cooling water is variably controlled based on the selected mold cooling pattern and supplied to the mold to improve the quality of the casting.

[0005]

However, in the conventional low-pressure casting method described above, the gas pressure is determined based on the mold temperature and the temperature of the molten metal at the time of starting the pressurized filling of the molten metal into the cavity of the casting mold. Because you set a retention period for,
If the temperature of the mold or the temperature of the molten metal changes during the filling of the molten metal into the cavity, the casting conditions deviate from the optimum conditions, and there is a problem that the quality of the cast product deteriorates.

[0006] In view of the above-mentioned circumstances, an object of the present invention is to provide a low-pressure casting method capable of stably stabilizing the quality of a casting by enabling to always set optimum casting conditions. .

[0007]

SUMMARY OF THE INVENTION A low-pressure casting apparatus according to the present invention increases a gas pressure after filling a molten metal into a cavity of a casting mold, and increases the gas pressure after the filling. In the low-pressure casting method of performing casting while holding the gas pressure for a predetermined period, the mold temperature and the molten metal temperature in the initial period of the holding period of the gas pressure are detected, and according to the detected mold temperature and the molten metal temperature, The length of the holding period is set.

In the low-pressure casting apparatus according to the present invention, after filling the molten metal into the cavity of the casting mold, the gas pressure is increased, and the increased gas pressure is set to a predetermined value. In the low-pressure casting method of performing casting while holding for a period, the mold temperature and the molten metal temperature at the beginning of the holding period of the gas pressure are detected, and the end of the holding period is determined according to the detected mold temperature and molten metal temperature. It is characterized in that a time from a time point to a mold opening time point is set.

[0009]

According to the present invention, based on the mold temperature and the molten metal temperature at the beginning of the holding period after the gas pressure rises, the length of the holding period or the end of the holding period to the mold opening time Since the time until the mold is set, even if the mold temperature or the molten metal temperature changes during the filling of the molten metal, it is possible to always set the optimal casting conditions without being affected by it, Quality can be stabilized.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment in which the present invention is applied to a low-pressure casting apparatus for casting a pair of cylinder heads of a six-cylinder engine will be described.

FIG. 1 is a sectional view schematically showing a configuration of a left portion (for one cylinder head) from a center line of a mold set in a casting machine.

In FIG. 1, a casting mold 1 includes a lower mold 2.
And an upper mold 3 disposed above the lower mold 2 and a core assembly 4 made of an all sand mold disposed between the lower mold 2 and the upper mold 3. 2, an upper mold 3 and a core assembly 4, a nest 5 provided in the lower mold 2 to form a combustion chamber of a cylinder head, and a casting vertically provided in the upper mold 3 to form a plug hole. A cavity 7 having a shape corresponding to the cylinder head is defined by the punch pin 6. Passages 8 and 9 for introducing a cooling fluid are formed inside the insert 5 and the plug hole forming cast pin 6. Reference numeral 10 denotes a regulating member that regulates the distance between the lower mold 2 and the upper mold 3 when the mold is closed. The regulating member is suspended around the outer edge of the lower surface of the upper mold 3 so as to extend outside the core assembly 4. Covering.

The core assembly 4 is shown in FIGS. 2 and 3 as an outer frame composed of a lower frame 11 and four sand molds assembled on the lower frame 11 to form four side walls of the cavity 7 respectively. Frames 12, 13, 14, 15, outer frame 14, and lower frame 1
1 and an exhaust port forming sand core 16 having a shape as shown in FIG. 4 and an intake port forming sand core integrally provided on an outer frame 15 facing the outer frame 14. The child 17 and the lower frame 11 and the outer frame 12, as shown in FIG.
13 supported at both ends 18a, 18b
And a water core forming sand core 18 and an oil jacket forming sand core 19. Therefore, the side wall and the lower wall of the cavity 7 except for the nest 5 are all formed by a sand mold.

The above-mentioned water core forming sand core 18
A gas release passage 18c is formed at the end 18b of the gasket, and a gas generated from the core can be sucked by connecting the gas suction nozzle 20 to the passage 18c from outside during casting.

The core assembly 4 is set on the lower mold 2 with all the sand cores assembled in advance.

On the lower frame 11 which forms the lower part of the lower wall part and the side wall part of the cavity 7, there is formed a gate 22 communicating the gate 21 formed in the lower mold 2 with the cavity 7. The lower die 2 is mounted on a molten metal distributing device 24 called a distributor having a molten metal supply passage 23. Then, similarly to the casting machine using the conventional low-pressure casting mold, the surface of the molten metal stored in the closed holding furnace is pressurized with low-pressure air, so that the molten metal passes through the stalk and enters the distributor 24. Enter, and further 2
It is configured to fill cavity 7 through 1 and 22.

As is apparent from the above description, the low-pressure casting apparatus used in the present embodiment has the lower frame 11 and the outer frames 12 to 15 for holding the sand cores 16 to 19 in the mold 1 thereof.
Is formed by a sand mold that is broken and removed together with the sand cores 16 to 19 after product casting, so that the cleaning operation of the mold 1 after casting is simplified, and Automation becomes easier and the casting cycle time can be shortened.

Further, in this low-pressure casting apparatus, the core assembly 4 is set on the lower die 2 in a state where the sand cores 16 to 19 are assembled in advance, so that the casting process is further automated. It becomes easy and the casting cycle time can be shortened.

Further, in this low-pressure casting apparatus, the lower frame 11 and the outer frame 12 in which the side walls of the cavity 7 are formed of sand molds.
Since it is formed by the above-mentioned structure, there is no need to provide a sliding die, the configuration of the casting mold 1 is simplified, and the production becomes easy.

Further, in this low-pressure casting apparatus, the lower wall of the cavity 7 is formed by a lower frame 11 made of a sand mold.
Since the gate 22 is formed in the lower frame 11, the gate 2
The solidification speed of the molten metal in 2 becomes slower than that of the product part, whereby the quality of the cast product can be improved.

Next, a description will be given of a method of controlling the pressurized cooling of the molten metal when casting is performed using the low-pressure casting apparatus described above.

Pressurization of the molten metal by pressurized air is performed based on a molten metal pressurization pattern as shown in FIG. In FIG. 6, a preload period is between time points t0 and t1. After the supply of pressurized air is started, until the molten metal reaches the gate 22 of the mold 1, the pressure is rapidly increased in order to prevent the temperature of the molten metal from dropping. To rise. Between the time points t1 and t2, a pressure holding period for maintaining a constant pressure so that the molten metal is smoothly filled between the sand cores, between the time points t2 and t3, the molten metal filling period, and between the time points t3 and t4. During the period, a pressure increasing period in which the pressure is increased to apply a high pressure to the molten metal surface, and between the time points t4 and t5, a pressure maintaining period (a pressurizing period) in which a high pressure is maintained to solidify the molten metal in a favorable state; An evacuation period (cooling period) is between the time points t5 and t6. The mold clamping is performed at the time point t0, and the time point t0
At 6, the mold is opened.

A plurality of molten metal pressurization patterns from the molten metal filling start time t2 to the pressurization start time t4 in FIG. 6 are prepared according to the molten metal temperature and the mold temperature at the molten metal filling start time t2. Then, a high pressure P ₀ by a constant pressure α is set as the target pressure value between pressurization period against inner pressure P in the step-up start time point t3.

As shown in FIG. 7, the upper mold 3 is provided with a filling detection sensor 25 having a molten metal contact portion 25a for detecting the completion of filling the molten metal into the cavity 7. The boosting start time t3 is corrected based on the detection by the filling detection sensor 25. That is, when the filling detection sensor 25 detects the filling of the molten metal at the time t3 'before the pressure rising start time t3 on the solid line A indicating the preset molten metal pressurizing pattern in FIG. Along with the furnace pressure P at a time t3 'when the target pressure P ₀ (P ₀ = P + α) is reached, which is higher than the furnace pressure P at the time t3' by a constant pressure α. Like that.

On the other hand, when the amount of molten metal charged into the cavity 7 is small, and the molten metal is
Is not in contact with the molten metal contact portion 25a, the filling of the molten metal is continued along the dashed-dotted line C as it is, the pressure rise is started from the time t3 "along the dashed-dotted line C, and the furnace pressure P at the time t3" Target pressure P ₀ (P
₀ = P + α), the furnace pressure is maintained and pressurized at time t4 ″.

Further, a plurality of mold cooling patterns by controlling the flow rate of the cooling water as shown in FIG. 9 are prepared according to the molten metal temperature and the mold temperature at the molten metal filling start time t2. Based on a program selection map as shown in Table 1 below, which shows the optimal combination of the molten metal pressurization pattern and the mold cooling pattern according to the molten metal temperature and the mold temperature at t2, the furnace pressure P and the cooling water The flow rate is controlled.

[0027]

[Table 1]

The map shown in Table 1 shows, for example, that when the mold temperature is 360 ° C. and the melt temperature is 730 ° C. at the molten metal filling start time t2, each of the plurality of molten metal pressurizing patterns and the mold cooling patterns is selected. This indicates that the molten metal pressing pattern of # 1 and the mold cooling pattern of # 2 are selected. When the die temperature is 400 ° C. and the molten metal temperature is 730 ° C., the molten metal pressing pattern of # 1 and # 3 indicates that the mold cooling pattern 3 is selected. Then, when the mold 1 is cooled with the adopted cooling pattern, the actual measured value of the mold temperature at that time is compared with the adopted mold cooling pattern, and based on the comparison, the mold temperature is determined. The flow rate of the cooling water is feedback controlled so as to approach the mold cooling pattern.

Next, the pressurizing period during casting (time t4)
~ T5) length (pressurization time) and evacuation period (time t5
To t6) (cooling time) is set based on the map shown in Table 2. The combination of the pressurization time and the cooling time in the map of Table 2 is based on the pressurization start time t4 (or t4
4 ′, t4 ″) is set in accordance with the molten metal temperature and the mold temperature at the time when 10 seconds have elapsed.

Also, casting is performed only when the temperature at the start of casting falls within the temperature range shown in Table 3 below. If the temperature deviates from the above temperature range, casting is stopped.

[0031]

[Table 2]

[0032]

[Table 3]

As described above, in the present embodiment, the time at which the pressure is increased is corrected based on the detection of the completion of the filling of the molten metal by the filling detection sensor 25, so that the molten metal pressurizing control can be performed efficiently.

In this embodiment, the length of the pressurizing period (time t4 to t5) (the pressurizing time) and the length of the evacuation period (time t5 to t6) (the cooling time) during casting are shown in Table 2. The combination of the pressurization time and the cooling time in the map of Table 2 is determined based on the map shown in Table 2.
Since it is set according to the molten metal temperature and the mold temperature at the time when 4 to 10 seconds have elapsed, the pressurizing time between the times t4 and t5 and the cooling time between the times t5 and t6 after the pressurization is completed are optimally set. Therefore, the quality of the cast product can be stabilized.

FIGS. 10 and 11 are a front view and a side view, respectively, of a casting apparatus Q provided with the low-pressure casting mold 1 described above.

The casting apparatus Q includes a casting machine 30 and a core setter 3 for supplying the core assembly 4 to the casting machine 30.
1 and an extractor 3 for removing the cast product W (before removing the core assembly 4) from the casting machine 30.
2 are provided. Further, the casting machine 30 has a molten metal holding furnace 33 and a stalk 34 for supplying the molten metal 26 in the molten metal holding furnace 33 to the distributor 24. The lower mold 2 is fixed to the lower platen 35, and the upper mold 3 is fixed to the upper platen 36. 37
Is an ejector plate.

Next, a description will be given of a casting facility provided with a large number of the casting devices Q. This casting facility has a two-story structure, in which a number of casting devices Q are arranged in a line on the upper floor, and on the lower floor, a core assembly 4 and a casting Means for transporting the product W are provided.

On the upper floor, as shown in a schematic layout in FIG. 12 (plan view), 14 casting apparatuses Q1 to Q14
Are arranged in two rows, and two casting lines L1, L2
Is formed. In FIG. 12, the hatched parts indicate elevators, and E1 to E14 transfer a pallet (not shown) on which the core assembly 4 is mounted from the lower floor to the upper floor, and This elevator transfers core pallets from the upper floor to the lower floor. F1 to F8 are:
This is an elevator for transferring a pallet (not shown) on which a casting product W is placed from an upper floor to a lower floor, and transferring an empty casting product pallet from a lower floor to an upper floor. Elevators E1 to E
7 and F1 to F4 are associated with the casting line L1, and the elevators E8 to E14 and F5 to F8 are associated with the casting line L2.

Core assembly lines G1 and G2, which will be described later, are provided at the minus ends (right ends in the drawing) of the respective casting lines L1 and L2. H1 and H2 transfer the pallets on which the core assemblies 4 assembled on the core assembly lines G1 and G2 are mounted from the upper floor to the lower floor, and transfer the empty core pallets from the lower floor to the upper floor. It is an elevator that passes and moves further upward.

On the other hand, on the lower floor, two parallel conveyor lines K1 and K2 are arranged as shown in a schematic layout in FIG. 13 (plan view). One conveyor line K1 is connected to the elevators E1 to E of the casting line L1.
7, and the other conveyor line K2 is connected to the elevators E8 to E1 of the casting line L2.
4 is extended along the line formed. At one end (right end in the figure) of each of the conveyor lines K1 and K2, cast product post-processing lines J1 and J2 for removing the core assembly 4 from the cast product W and cutting gates and the like are provided. ing. Then, the stockers S1 and S2 for retaining the empty cast product pallets are elevators H1 and H2.
2 are provided adjacent to each other.

FIG. 14 is a front view showing one casting line L1 and conveyor line K1. MA indicates a lower floor surface, and MB indicates an upper floor surface. Conveyor lines K1 indicate upper and lower two conveyor lines K1a and K1.
b, and a lower conveyor line K1a that moves to the left in the figure is a diagram in which a pallet on which the core assembly 4 assembled on the core assembly line G1 is placed is positioned up to the positions of the elevators E1 to E7. And the empty cast product pallets are transported to the left of the elevators F1 to F4.
Is a conveyor line for transporting to the position of. The upper conveyor line K1b, which moves rightward in the figure, has a pallet on which a casting product W is mounted and which is transferred from an upper floor to a lower floor by elevators F1 to F4.
1 is a conveyor line that transports an empty core pallet to the position of the elevator H1, which is transported from the upper floor to the lower floor by the elevators E1 to E7. Since the other conveyor line K2 has the same configuration as the conveyor line K1, the description is omitted.

FIG. 15 is a plan view showing the layout of the core assembly lines G1 and G2 arranged on the lower floor. In the drawing, P1 and P2 are core transport conveyor lines having a two-story structure. The elevators R1 and R2 shown at the right end of the figure are core return elevators for lowering empty core pallets from the ends of the upper members of the conveyor lines P1 and P2 onto the starting ends of the lower members. It is.

The core return elevators R1, R2 are:
The elevators H1 and H2 have almost the same height, the upper ends of the elevators H1 and R1 are connected by the upper member of the conveyor line P1, and the lower ends of the elevators H1 and R1 are the lower members of the conveyor line P1. Are linked. Then, the empty core pallet transferred above the floor surface MB of the upper floor by the elevator H1 is transferred to the upper end position of the elevator R1 by the upper member of the conveyor line P1, and then transferred downward by the elevator R1. , On the lower member of the conveyor line P1. Elevators H2 and R
2 and the upper and lower members of the conveyor line P2 are the same as above.

The core assembly 4 assembled on the core assembly lines G1 and G2 is placed on a core pallet and transferred on the lower member of the conveyor line P1 to the left in FIG. Is received along with the model data. Then, the core assembly 4 discharged from the core stocker 40 by the request signals from the casting devices Q1 to Q14 is
After being bonded by the bonding machine 41, the elevators H1, H2
Transported to the lower floor by elevators H1 and H2, and transferred onto lower members of the conveyor lines K1 and K2 (K1a in the conveyor line K1).

Here, assuming that the casting apparatus which has issued the retrieval request signal is, for example, Q5 of the casting line L1, the core assembly 4 is first moved leftward in the figure to the position of the elevator E5 by the lower conveyor line K1a. The caster 30 is conveyed, then transferred to the upper floor by the elevator E5, then set in the mold 1 of the casting machine 30 by the core setter 31 of the casting device Q5, and casting is performed in the above-described manner.

On the other hand, the empty core pallet
5 to the lower floor, and the upper conveyor line K1
b transports to the right of the figure to the position of the elevator H1, is further transported by the elevator H1 above the upper floor surface MB, and is then transported by the upper member of the conveyor line P1 to the upper end position of the elevator R1, and then It is transferred downward by the elevator R1 and transferred onto the lower member of the conveyor line P1, and the core assembly line G
Returned to 1.

The product W cast by the casting machine 30 of the casting apparatus Q5 is taken out of the mold 1 by the extractor 32, transferred to the lower floor by the elevator F3, and moved rightward in the figure by the upper conveyor line K1b. The core assembly 4 is conveyed and subjected to post-processing such as removal of the core assembly 4 and gate cutting at the post-processing line J1.

As is clear from the above description, in this casting facility, the casting apparatuses Q1 to Q14 are arranged on the upper floor, and the conveyor lines K1 and K2 as the means for transporting the core assembly 4 and the cast product W are provided. Since it has a two-story structure disposed on the lower floor, the space factor is extremely good, and a large number of casting devices Q1 to Q14 can be disposed in a limited space, and the configuration around the casting machine 30 Can be simplified, and the maintainability is improved.

Further, casting devices Q1 to Q14 are arranged on the upper floor, and conveyor lines K1 and K2, which are means for conveying the core assembly 4 and the cast product W, are arranged on the lower floor. Since the lines K1, K2 are constituted by the lower core assembly carry-in line and the upper cast product carry-out line, these casting devices Q1 to Q14
Of core assembly 4 and casting apparatus Q1-Q
The unloading of the cast product W from 14 can be performed very efficiently.

Next, an example of a control routine executed by the central control controller in the casting facility will be described with reference to the flowcharts shown in FIG. In addition, in order to simplify the description, the case of the casting apparatus Q5 of the casting line L1 is taken as an example. Also, in the following flowchart,
S represents a step.

FIG. 16 is a flow chart showing a core exit routine when the core assembly 4 (unbonded) is ejected from the core stocker 40 of the core assembly line G1.

First, in step S1, a work completion command b (described later) of the casting machine is received, and in step S2, the type is read out from the delivery command signal.
At S3, the core assembly 4 of the model is taken out of the core stocker 40, and is placed on the lower member of the core transport conveyor line P1 at S4 to transport the core assembly 4 to the position of the bonding machine 41. The adhesive is injected in S5 and the core assembly 4
Glue. Then, the core assembly 4 already bonded in S6
Is transported to the lower floor on the elevator H1, the core type is detected in S7, the destination is specified in S8, the work is placed on the conveyor line K1a in S9, a work completion command is issued in S10, and the core is discharged. Complete the routine.

FIG. 17 shows that the core assembly 4 is connected to a casting device Q5.
9 is a flowchart showing a core loading routine for loading the core.

First, in step S11, a work completion command a is received.
At 12, the core assembly 4 flowing on the conveyor line K1a
Is stored in the rank memory. Then, the limit switch set on the conveyor line K1a in S13 as to whether or not the desired core assembly 4 has arrived at the position of the core transfer elevator E5 attached to the casting apparatus Q5 that has issued the retrieval command signal. If the answer is YES, a knock pin (not shown) is projected to stop the core assembly 4 at the position of the elevator E5 in S14, and is transferred to the elevator E5 in S15. Is transferred to the upper floor to complete the core loading routine.

FIG. 18 shows that the core assembly 4 is connected to a casting device Q5.
9 is a flowchart showing a core setting routine to be set in the casting machine 30 of FIG.

First, in S21, the type of the core assembly 4 that has arrived is confirmed. Then, it is determined whether or not the types match in S22. If YES, the core assembly 4 is held by the core setter 31 in S23, and if NO,
In step S31, the vehicle is returned on the elevator E5,
At 32, a work completion command is issued. Next, it is determined whether Koasetta 31 by holding the core assemblies 4 is completed in S24, if YES, the measured mold temperature T _A and YuAtsushi T _B at S25, at S26, mold temperature T _A and hot water temperature T _B
Is within the range shown in Table 3 above.

If the decision result in the step S26 is YES, a step S2 is executed.
7, the core assembly 4 is placed on the mold 1, and S28
Then, the position of the core assembly 4 is detected by the photoelectric tube. Then, in S29, it is determined whether or not the core assembly 4 blocks light. If NO, a core setting completion signal is issued in S30. If YES, an alarm is issued in S34 and S35 is issued. To stop work.

FIGS. 19 to 21 are flowcharts showing a molten metal pressurizing control routine during casting.

[0059] First, it is determined whether a set of core assemblies 4 in S41 in FIG. 19 has been completed, by measuring the mold temperature T _A and YuAtsushi T _B at S42, at S43, mold temperature T _A and water temperature T _B determines whether is in the range shown in table 3.
Then, if the decision result in the step S43 is YES, the process proceeds to a step S44 to start the casting.

Next, in S45, a molten metal pressurizing pattern and a mold cooling pattern (see FIG. 9) are selected from the map shown in Table 1, and preloading is started in S46, and feedback is performed in S47 so as to reach the target preload. Perform control. In the next S48, it is determined whether or not the preload has been completed.
The process proceeds to S51, where it is determined whether or not the mold 1 is fully closed. If YES, filling of the molten metal is started in S52, and S
At 53, feedback control is performed so as to reach the target filling pressure.

In the next S54, it is determined whether or not the filling detection sensor 25 has detected the filling of the molten metal.
At S55, the pressure P at this time is measured, and at S5
At 6 the boosting is started. Then, in S57, a value obtained by adding a constant pressure value α to the pressure P when the filling detection sensor 25 detects the filling of the molten metal is set as the target pressurized value P ₀ , and in S58, the pressure P is set to the target pressurized value P _0. performs feedback control so that, if it is determined that the pressure P is equal to or greater than the target boost value P ₀ in S59, to maintain the pressure P at that time in S60, the process proceeds to S71 in FIG. 21.

On the other hand, when the determination in S51 is NO, S
At 61, the preload is maintained, and at S62, a timer is set.
Return to When the set time of the timer has elapsed, the pressure is reduced in S64, an alarm is issued in S65, and the operation is stopped in S66.

Next, in S71 of FIG. 21, it is determined whether or not 10 seconds have elapsed. If YES, the mold temperature T _A is determined in S72.
And YuAtsushi T _B is measured, at S73, from the map shown in Table 2, sets the pressing time and cooling time. And S
When it is determined in 74 and S75 that the pressurizing time and the cooling time have been completed, the mold 1 is opened in S76, a work completion command b is issued in S77, and the molten metal pressure control routine ends.

FIG. 22 is a flowchart showing a mold closing operation routine. This routine is shown in FIGS.
1, while being related to the routine shown in FIG.

First, in S81, it is determined from S44 in FIG. 19 whether or not casting has been started.
Then, the closing operation of the mold 1 is started. Then, in S83, the mold 1
It is determined whether or not is completely closed. If YES, S84
To set the mold fully closed flag. On the other hand, if the determination in S83 is NO, the timer is set in S85, and it is determined in S86 whether or not the set time of this timer has elapsed. During NO, the process returns to S83. Proceed to S87 and issue an alarm.

FIG. 23 is a flowchart showing a control routine for controlling the mold temperature T _A and the hot water temperature T _B during casting. This routine is also executed in parallel while maintaining the relationship with the routines shown in FIGS. Here, S
At 91, it is determined from S44 in FIG. 19 whether or not casting has been started. If YES, feedback control is performed at S92 so as to reach the target temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of a casting mold provided in a low-pressure casting apparatus applied to a low-pressure casting method according to the present invention.

FIG. 2 is a perspective view of the core assembly.

FIG. 3 is an exploded perspective view of the core assembly.

FIG. 4 is a rear view of the exhaust port forming sand core (FIG. 4).
A), plan view (FIG. 4B), front view (FIG. 4C), and bottom view (FIG. 4D)

5 is a rear view (FIG. 5A), a plan view (FIG. 5B), a front view (FIG. 5C), and a bottom view (FIG. 5D) of the water core forming sand core.

FIG. 6 is a diagram showing a molten metal pressurization pattern;

FIG. 7 is a sectional view showing a state in which a filling detection sensor is attached to a mold.

FIG. 8 is a diagram for explaining a boosting start time correction operation for the pressing pattern in FIG. 6;

FIG. 9 is a diagram showing a mold cooling pattern.

FIG. 10 is a front view of a low-pressure casting apparatus applied to the embodiment of the present invention.

FIG. 11 is a front view of the same.

FIG. 12 is a plan view of an upper floor portion of a casting facility.

FIG. 13 is a plan view of a lower floor portion of a casting facility.

FIG. 14 is a side view of a casting facility.

FIG. 15 is a plan view of a core assembly line of a casting facility.

FIG. 16 is a flowchart of a core delivery routine;

FIG. 17 is a flowchart of a core loading routine.

FIG. 18 is a flowchart of a core setting routine.

FIG. 19 is a first half of a flowchart of a molten metal pressure control routine.

FIG. 20 is a flowchart middle part of a molten metal pressure control routine.

FIG. 21 is a second half of a flowchart of a molten metal pressure control routine.

FIG. 22 is a flowchart of a mold closing operation routine.

FIG. 23 is a flowchart of a temperature control routine for a molten metal and a mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casting die 2 Lower die 3 Upper die 4 Core assembly 5 Nesting 6 Casting pin 7 Cavity 8,9 Cooling fluid passage 10 Restriction member 11 Lower frame of core assembly 12-15 Outside core assembly Frame 16 Sand core for forming an exhaust port 17 Sand core for forming an intake port 18 Sand core for forming a water jacket 19 Sand core for forming an oil jacket 21, 22 Gate 25 Filling detection sensor 26 Molten metal 30 Casting machine 31 Core setter 32 Extra Kuta 33 Melt holding furnace Q, QI to Q14 Casting equipment E1 to E14, F1 to F8, H1, H2 Elevator G1, G2 Core assembly line J1, J2 Casting product post-processing line K1, K2 Conveyor line L1, L2 Casting line W Casting products

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-70368 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 18/08

Claims (2)

(57) [Claims] 1. The surface of a molten metal stored in an airtight container,
By gas pressure, pressurize based on a preset pressurization pattern, fill the cavity defined in the mold with the molten metal, and after filling with the molten metal, increase the gas pressure,
In the low-pressure casting method of performing casting while holding the gas pressure after the rise for a predetermined period, a mold temperature and a melt temperature in an initial stage of the holding period of the gas pressure are detected, and the detected mold temperature and the melt temperature are detected. A low pressure casting method, wherein the length of the holding period is set accordingly. 2. The method according to claim 1, wherein the surface of the molten metal stored in the closed container is
By gas pressure, pressurize based on a preset pressurization pattern, fill the cavity defined in the mold with the molten metal, and after filling with the molten metal, increase the gas pressure,
In the low-pressure casting method of performing casting while holding the gas pressure after the rise for a predetermined period, a mold temperature and a melt temperature in an initial stage of the holding period of the gas pressure are detected, and the detected mold temperature and the melt temperature are detected. A low-pressure casting method comprising setting a time from the end of the holding period to the point of time when the mold is opened.