JPH03280Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a molding sand pumping control device that pumps molding sand to a mold making machine.

(Prior art) Conventionally, in order to feed molding sand to a mold making machine, the molding sand is stored in a pressure feeding tank, air is supplied into the pressure feeding tank by a pressure air system, and pressurized air is supplied to the molding machine. Accordingly, the molding sand is forced to be fed to the sand tank of the molding machine through the sand feeding passage (see, for example, Japanese Utility Model Application No. 58-47350). and,
A level sensor is installed in the pressure feeding tank, and an opening/closing valve is installed in the sand feeding passage, and when the level sensor detects that the amount of molding sand remaining in the pressure feeding tank has decreased, the opening/closing valve is activated. Close operation.

However, when detecting the remaining amount of molding sand using the level sensor, there is a problem in that the remaining amount cannot be accurately detected. In other words, the level sensor is, for example, provided with a contact sensor that comes into contact with the foundry sand at a predetermined height at the bottom of the pressure-feeding tank, and is activated to detect a predetermined residual amount state when the foundry sand is no longer in contact with this contact sensor. Alternatively, a device is used that uses optical means to detect when the foundry sand has fallen below a predetermined level. However, the foundry sand is not always in a constant fluid state, and if it remains along the wall of the pressure-feeding tank, it may be because the molding sand has finished feeding at the pressure-feeding port at the bottom of the tank. Furthermore, the level sensor may not be able to detect the level sensor due to molding sand adhering to the wall surface. At this time, the molding sand in the sand feeding passage is pumped, and when it decreases below a certain level, the molding sand in the sand feeding passage is rapidly transported to the molding machine side by pressurized air in the pressure feeding tank. Sand is blown out from the sand tank or dust collection duct of the molding machine to which this air impact pressure acts, causing dust to be generated in the surrounding area.

In addition, if the detection level by the level sensor is set to a high level and the detection timing is set early in order to avoid the above phenomenon, the volume of the pressure tank cannot be used effectively and a large amount of molding sand remains in the sand feeding passage. In this case, it may become difficult to pump the molding sand when replenishing the pumping tank with molding sand and starting pumping the molding sand again.

(Purpose of the invention) In view of the above-mentioned circumstances, the present invention prevents air shock pressure from acting on the sand tank of the molding machine by accurately determining when the feeding of molding sand from the pressure tank has finished. An object of the present invention is to provide a molding sand pumping control device that suppresses the generation of dust and prevents a large amount of sand from remaining in a sand feeding passage.

(Structure of the invention) The pressure-feeding control device of the present invention is provided with a pressure detector that detects the internal pressure of the pressure-feeding tank, and upon receiving a signal from the pressure detector, the feeding of molding sand from the pressure-feeding tank to the sand feeding passage is completed. Detects the decrease in internal pressure caused by this, and closes the opening/closing valve of the sand feeding passage, and after a predetermined delay, the auxiliary air supply unit supplies auxiliary air to the sand feeding passage downstream of the opening/closing valve. The invention is characterized by comprising a control means for stopping the operation.

(Effects of the invention) According to the invention, the internal pressure of the pressure-feeding tank is detected by a pressure detector, the feeding of molding sand from the pressure-feeding tank to the sand feeding passage is completed, and the air shock pressure is applied to the molding machine. By determining that the internal pressure of the pressure-feeding tank decreases as a phenomenon before it acts on the sand tank, and using this to detect the feeding status of foundry sand in the pressure-feeding tank, it is possible to Regardless of the state in which the foundry sand is attached, it is possible to accurately detect the state in which the supply of molding sand from the pressure tank to the sand supply passage is completed.

In addition, when the pressure drop state of the pressure feeding tank is detected, that is, the end of feeding is detected, the opening/closing valve of the sand feeding passage is closed to prevent the pressurized air in the pressure feeding tank from being transmitted to the sand feeding passage side, thereby causing an air shock. In addition to preventing the generation of dust due to pressure, the auxiliary air supply unit stops supplying auxiliary air after a predetermined time delay. It is possible to prevent a large amount of molding sand from remaining in this sand feeding passage by feeding the molding sand directly, and to ensure good feeding by preventing it from becoming an obstacle when the molding sand is pumped again. It is something.

(Example) Hereinafter, an example of the present invention will be described along with the drawings. FIG. 1 is an overall configuration diagram.

The molding sand S is fed to a pressure tank 1 through a gate valve 3 at its upper part.
4 is opened and closed. A sand feeding passage 2 having one end open at the bottom of the pressure feeding tank 1 is provided.
The downstream end of the plurality of first to third molding machines 3 to 5
There are connection openings to the respective sand tanks 6 to 8.

A pressurized air system 10 that introduces pressurized air is connected to the pressurized tank 1 . In this pressurized air system 10, pressurized air from a pressure source 11 is
The first
It is introduced into the upper part of the pressure-feeding tank 1 through the introduction passage 14 . The supply/exhaust valve 13 is operated by pilot pressure, and when the first pressurizing valve 12 is turned on and pressurized air is being supplied, the supply/exhaust valve 13 introduces pressurized air into the pressurized tank 1. When the 1 pressurizing valve 12 is turned off, it operates to exhaust the pressure in the pressurizing tank 1.

Further, the pressurized air from the pressure source 11 is
It is introduced from the bottom of the pressure tank 1 via the pressure valve 15 and the second introduction passage 16 . The pressurized air introduced from the bottom through the second introduction passage 16 is for increasing the fluidity of the foundry sand S accommodated in the pressure feeding tank 1, thereby causing the floating foundry sand S to along with pressurized air, the sand feed passage 2
It is sent under pressure.

The sand feeding passage 2 branches into branch passages 2a to 2c for each of the molding machines 3 to 5, and each branch passage 2a to 2
c, respectively, first to third opening/closing valves 17 to 1;
9 is interposed to open and close the feeding of the molding sand S. The on-off valves 17 to 19 are constituted by pinch valves that are opened and closed by turning pressurized air on and off. 1 solenoid valve 21 is interposed and configured to drive the opening and closing operations of the opening and closing valves 17 to 19. This opening/closing valve 17~
An auxiliary air supply unit 23 for supplying auxiliary air is connected to the sand feeding passage 2a on the downstream side of the sand feeding passage 2a. The auxiliary air supply unit 23 includes a first supply section 24 that supplies a first auxiliary air that is installed directly downstream of the on-off valves 17 to 19, and a second auxiliary air that is installed slightly downstream of the first supply section 24. and a second supply section 25 that supplies both supply sections 24 and 2.
Auxiliary air is supplied from 5 to each air pipe 2.
It is driven by the operation of second and third solenoid valves 28 and 29 interposed in solenoid valves 6 and 27. In the figure, only the sand feeding passage 2a for the first molding machine 3 is shown in detail, but the sand feeding passage 2b, for the second and third molding machines 4, 5 is shown in detail. 2c is similarly configured.

On the other hand, in the pressure feeding tank 1, there is a pressure detector 30 for detecting the internal pressure of the tank in order to detect the remaining amount of foundry sand S in the pressure feeding tank 1 from changes in the internal pressure.
is provided. Further, level sensors 31 are installed in the sand tanks 6 to 8 of each of the molding machines 3 to 5, respectively.

The tank internal pressure detection signal from the pressure detector 30 and the signal from the level sensor 31 are outputted to the control means 33, which sends the first and second pressurizing valves 12, 15, the first to third solenoid valves 21, Control signals are output to 28 and 29, respectively.

The control by the control means 33 will be explained based on the time chart of FIG. 2. Based on the operation of the first molding machine 3, the remaining amount of molding sand S in the sand tank 6 decreases, and when the level sensor 31 turns on at point A, the molding sand S is pumped into the sand tank 6 and into the tank 1.
A control signal is output from the control means 33 to each part so as to feed the water from the control means 33 to each part. First, each opening/closing valve 17 to 19
The pressurized air system 10 is operated in a closed state, and the
Pressurized air is introduced into the pressure feeding tank 1 from the first introduction passage 14 via the supply/exhaust valve 13 which is in the air supply position with the first pressure valve 12 in the open state,
The second pressurizing valve 15 is also opened and the second introduction passage 16 is opened.
Pressurized air is introduced into the bottom of the pressure-feeding tank 1 from the tank 1 to prepare for pressure-feeding.

Then, when a predetermined time t lags from point A at which the level sensor 31 is turned on, the first solenoid valve 21 opens the first on-off valve 17.
is turned on, and the third solenoid valve 29 is turned on to supply the second auxiliary air from the second supply section 25, and the molding sand S in the pressure feeding tank 1 is transferred to the first molding together with the pressurized air. Pressure feeding to the sand tank 6 of the machine 3 is started. Through the above-described operation, the foundry sand S is transferred to the sand tank 6 of the first molding machine 3.
is fed under pressure, and the level sensor 31 is turned off in a state in which a predetermined amount of foundry sand S is supplied.

Next, as described above, while the molding sand S is being pumped from the pressure tank 1, the remaining amount of molding sand S in the pressure tank 1 decreases, and the amount of sand S from the pressure tank 1 to the sand feeding passage 2 decreases. When the pressure-feeding of the foundry sand S is completed, the pressure-feeding tank 1 is transferred from the pressure-feeding air system 10
The amount of air flowing into the sand feeding passage 2 increases relative to the pressurized air introduced therein, and the internal pressure of the pressure feeding tank 1 changes to decrease based on the fluctuation of the difference between the two. When this pressure fluctuation is detected and judged from the signal of the pressure detector 30, that is, when the detected pressure of the pressure detector 30 exceeds the set value at point B and the pressure drops, the first solenoid valve 21 is turned off. At the same time, the first on-off valve 17 is closed, and the first and second pressurizing valves 12 and 1 of the pressurized air system 10 are closed.
5 is closed, the introduction of pressurized air into the pressurized tank 1 is stopped, and the pressurized air in the pressurized tank 1 is exhausted by the supply/exhaust valve 13 which is in the exhaust position.

Then, from the closing operation of the first on-off valve 17, the second on-off valve ₁₇ is opened for a predetermined time t1 set by a timer.
The solenoid valve 28 is turned on, and the first auxiliary air is supplied from the first supply section 24. Furthermore, when the predetermined time _t2 set by the timer has elapsed, the third solenoid valve 29 is turned off to stop the supply of the second auxiliary air from the second supply section 25 that has been in the supply state. be. Furthermore, when the supply of the second auxiliary air from the second supply section 25 is stopped, the first to third on-off valves 17 to 19 are opened because the internal pressure of the pressure tank 1 is greatly reduced. be.

In the above state, the gate valve 34 at the top of the pressure tank 1 is opened and the molding sand S is pumped into the tank 1.
It is meant to be replenished internally. Note that the above operation is the first
Although only the pressure feeding of the molding sand S to the molding machine 3 has been shown, the pressure feeding control of the molding sand S to the other molding machines 4 and 5 is also performed in the same manner as described above.

As a result of the above operation, when the foundry sand S in the pressure feeding tank 1 is no longer fed to the sand feeding passage 2, this is detected from the internal pressure drop, and the foundry sand S in the sand feeding passage 2 is transferred to the sand feeding passage 2. By closing the on-off valves 17 to 19 before rapidly feeding the sand with pressurized air, it is possible to prevent sand from blowing out in the sand tanks 6 to 8. Furthermore, after the on-off valves 17 to 19 are closed, auxiliary air is supplied downstream of the on-off valves 17 to 19 for a predetermined period of time to reduce the amount of foundry sand S remaining in the sand feeding passage 2. Good feeding can be obtained during the next pumping.

In addition, in the above operation, the on-off valves 17 to 1
9 is closed, the time for continuing to supply auxiliary air is set to the time required for the molding sand S in this passage to be fed to the sand tank, depending on the length of the sand feeding passage 2, etc. It is something to do.

Further, the structures of the pressurized air system 10 and the auxiliary air supply unit 23 are not limited to those of the above embodiments, and can be modified as appropriate. Furthermore, the structures of the on-off valves 17 to 19 that open and close the sand feeding passage 2 and their opening and closing operation structures are not limited to those of the above embodiments.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a molding sand pumping control device according to an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the control means. S... Foundry sand, 1... Pressure feeding tank, 2... Sand feeding passage, 3-5... Molding machine, 6-8... Sand tank, 10... Pressure feeding air system, 17-19... Opening/closing valve , 21, 28, 29... Solenoid valve, 23... Auxiliary air supply unit, 24... First supply section, 25... Second supply section, 30... Pressure detector, 33... Control means.

Claims (1)

[Scope of utility model registration request] A pressure-feeding tank containing foundry sand and connected to a pressure-feeding air system, a molding machine equipped with a sand tank, a sand feed passage communicating with the pressure-feeding tank and the sand tank, and opening and closing of the sand feed passage. an on-off valve, an auxiliary air supply unit that supplies auxiliary air to the sand feeding passage on the downstream side of the on-off valve, a pressure detector that detects the internal pressure of the pressure tank, and a pressure sensor that receives a signal from the pressure sensor and performs pressure feeding. Control that determines and detects a decrease in internal pressure accompanying the completion of feeding of molding sand from the tank to the sand feeding passage, closes the opening/closing valve, and stops the supply of auxiliary air by the auxiliary air supply unit after a predetermined time delay. 1. A pressure feeding control device for molding sand, comprising: means.