CN202224635U - Low-pressure casting device - Google Patents

Abstract

The utility model relates to a casting technical field discloses a device for low pressure casting. The low-pressure casting device comprises a heat preservation chamber, a mold, a pressure chamber, a liquid lifting chamber, a plug rod for controlling the closing of the material injection channel, a liquid level pressurization control system and a liquid level sensor. The utility model provides a low pressure casting device has following advantage: the production efficiency is greatly improved, and continuous production can be realized; the casting parameters are stable, and the fluctuation of the pressurizing pressure is small and the control system is simplified because the metal liquid level is kept constant during each pouring; the quality of the molten metal is stable; the process freedom is improved.

Description

A low pressure casting device

technical field

The utility model relates to the technical field of casting, in particular to a device for low-pressure casting

Background technique

Low-pressure casting refers to a casting method in which liquid metal fills the mold from bottom to top and solidifies under pressure to obtain castings under pressure. Specifically: apply about 0.0098 to 0.049MPa on the metal liquid surface of the closed crucible The air pressure (dry air or inert gas) makes the molten metal rise along the pipe (riser) placed in the molten metal and flows into the mold above the chamber, until the molten metal is completely solidified from the upper part of the mold to the gate When the pressurization is stopped, the molten metal in the riser flows back to the crucible and the casting mold can be opened to take out the casting. Because the pressure applied on the liquid metal surface is very low, it is called low-pressure casting.

The low-pressure casting device is a low-pressure casting machine. The most widely used low-pressure casting machine is a top-mounted structure. Its feature is that the heat preservation and pouring crucible boiler is placed under the mold, and a liter liquid pipe is placed in the molten metal in the crucible boiler to connect with the mold. The top-mounted low-pressure casting machine has the advantages of simple structure, easy manufacture and convenient operation.

Compared with other casting forming methods, the low-pressure casting process based on the top-mounted machine structure has the following advantages: 1) The molten metal filling is stable and the filling speed is controllable, which can effectively avoid turbulence, impact and splashing of the molten metal, and reduce Air entrainment and oxidation improve the quality of castings; 2) The fluidity of metal is good, which is conducive to the formation of thin-walled castings with clear contours and smooth surfaces; 3) The liquid solidifies under pressure, the feeding effect is good, the casting structure is compact, and the mechanical properties High; 4) The gating system of low-pressure casting is simple, generally no riser is required, and the process yield is high. Generally, the process yield of low-pressure casting parts is mostly above 90%; 5) It is easy to realize mechanization and automation.

However, the top-mounted low-pressure casting machine also has obvious disadvantages: 1) Low production efficiency, which is caused by the long pressurization process and long solidification time; All operations in the production cycle are carried out indoors, and most of the time for the heat preservation crucible is idle; the third is that when the molten metal in the crucible is used up for feeding, the entire production process must be stopped; 2) Control of pressurized pressure parameters The main reason for the low accuracy is that the metal liquid level in the crucible boiler decreases with the increase of the pouring times, and the height of the metal liquid surface from the mold is constantly changing, so the pressurized pressure needs to change with the change of the liquid level height, resulting in a The pressure fluctuation is large; the second is that the pressure feedback is slow, due to the large sealing area of the heat preservation crucible, easy leakage, large volume, slow pressure rise, etc., the timeliness of the pressurization of the molten metal filling is poor; 3) the freedom of the casting process of the parts is poor; 4) It is difficult to guarantee the stability of the quality of molten aluminum in the heat preservation crucible. Because the heat preservation crucible is sealed, refining in the furnace and removal of oxidized slag cannot be implemented, and the quality of liquid aluminum fluctuates greatly.

Utility model content

In order to solve the above problems, the utility model provides a low-pressure casting that can give full play to the advantages of low-pressure casting, avoid its shortcomings, and meet the increasingly higher requirements of the market for casting quality, mechanical properties, production efficiency, and process freedom. Casting device.

The utility model is achieved in that:

A low-pressure casting device, including a heat preservation chamber and a mould, a pressurization chamber, a liquid lifting chamber, a plug rod for controlling the closing of the injection channel, a liquid level pressurization control system, and a liquid level sensor,

The heat preservation chamber communicates with the pressurization chamber through the injection channel, the stopper rod is arranged above the injection channel opening, the pressurization chamber communicates with the lifting chamber, and the heat preservation chamber is provided with a feeding port;

A liquid level sensor and a liquid level pressurization control device are arranged above the pressurization chamber, and the liquid level sensor is electrically connected to the liquid level pressurization control device;

A mold is arranged above the liquid-lifting chamber, and the liquid-lifting chamber communicates with the mold.

The utility model can be further improved: the pressurization chamber and the bottom of the liquid raising chamber are connected by a channel, and the bottom ends of the pressurizing chamber and the liquid raising chamber are inclined, and gradually incline upward from the pressurizing chamber to the liquid raising chamber.

Optionally, the plug rod moves up and down through a hydraulic cylinder or a pneumatic cylinder.

Optionally, the liquid level sensor is a liquid level electrode.

The low-pressure casting device provided by the utility model adopts a three-chamber structure independently arranged, that is, a heat preservation chamber, a pressurization chamber, and a liquid lifting chamber respectively. A plug rod that moves up and down realizes connection and disconnection. During casting: the liquid metal level in the heat preservation chamber is higher than the pressurization/liter liquid chamber, and when the rising channel of the plug rod is opened, the metal liquid in the heat preservation chamber flows into the pressure/liter liquid chamber under the action of gravity, and when it reaches a certain height The stopper rod is closed; then gas is introduced into the liquid metal surface in the pressurized chamber, and the metal is hydraulically injected into the mold to form it; when the solidification is completed, the gas in the pressurized chamber is released, the stopper rod is opened, and the metal liquid in the heat preservation chamber is released again. Add molten metal to the pressurized chamber. It can be seen from this that the liquid metal level in the pressurized chamber of the low pressure casting device is kept at a constant value every time casting. During pouring, forming and solidification, operations such as feeding, refining, and slag removal can be performed in the heat preservation room.

The low-pressure casting device provided by the utility model has the following advantages:

1) The production efficiency is greatly improved, and continuous production can be realized: when the molten metal in the heat preservation chamber 1 is insufficient, it can be supplemented by feeding, and the supplement can be carried out at any stage, that is, during injection, filling, pressure keeping, pressure relief and start-up The supplementary feeding process can be implemented in the mold stage, realizing continuous production, and overcoming the defects of the existing technology that the entire production process needs to be stopped; the second is because the pressurization process is shortened;

2) The casting parameters are stable, because the metal liquid level remains constant during each pouring, the fluctuation of the pressurized pressure is small, the control system is simplified, the control accuracy is high, and the process parameters such as the filling speed in each cycle are more stable. Pressure feedback is also fast;

3) The quality of molten metal is stable, the heat preservation room is not sealed, the refining in the furnace and the removal of oxide slag are relatively easy to implement, and the quality fluctuation of molten aluminum is small;

4) The degree of freedom of the process is improved, and the degree of freedom of the casting process of the parts is improved.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the utility model, constitute a part of the application, and do not constitute an improper limitation of the utility model. In the accompanying drawings:

Fig. 1 is the structural representation of the low-pressure casting device that the utility model embodiment provides;

Fig. 2 is the state schematic diagram when adding molten metal in the device;

Fig. 3 is a schematic diagram of the state of injecting molten metal into the pressurization chamber and the liquid lifting chamber in the heat preservation chamber;

Fig. 4 is a schematic diagram of the state of filling in the pressurization chamber and the liquid lifting chamber;

Fig. 5 is a schematic diagram of the state of filling and casting of the lifting chamber into the mold;

Fig. 6 is a schematic diagram of the return state of the molten metal in the lifting chamber after the pressure is released.

In the figure: 1-insulation chamber, 2-feeding port, 3-liquid/pneumatic cylinder, 4-plug rod, 5-injection channel, 6-pressurization chamber, 7-liquid level sensor, 8-pressurization port, 9 -Liquid chamber, 10-mold, 11-feeding channel, 12 liquid level pressurization control system

Detailed ways

The utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The schematic embodiments and descriptions of the utility model are used to explain the utility model, but not as a limitation to the utility model.

As shown in Figure 1, the low-pressure casting device provided by this embodiment includes a heat preservation chamber 1, a pressurization chamber 6, a liquid lifting chamber 9, a mold 10, a stopper rod 4 for controlling the closing of the injection channel, and a liquid level pressurization control system 12. Liquid level sensor 7: The heat preservation chamber 1 communicates with the pressurization chamber 6 through the injection channel 5, the stopper rod 4 is set above the mouth of the injection channel 5, the pressurization chamber 6 communicates with the liquid lifting chamber 9, and the heat preservation chamber 1 There is a feeding port 2; a liquid level sensor 7, a pressurizing port 8 and a liquid level pressurization control device 12 are arranged above the pressurization chamber 6, and the liquid level sensor 7 is electrically connected with the liquid level pressurization control device 12, and the liquid level pressurization control The device inputs gas into the pressurized chamber through the pressurized port; a mold 10 is arranged above the liquid-lifting chamber 9 , and the liquid-lifting chamber 9 communicates with the mold 10 .

The working process of the low pressure casting device provided by the present embodiment is:

1) Injection: Add the smelted molten metal into the heat preservation chamber 1 through the feeding port 2 (as shown in Figure 2), the stopper rod 4 rises under the drive of the hydraulic/pneumatic cylinder 3, opens the injection channel 5, and the heat preservation chamber 2 The molten metal in the liquid flows into the pressurization chamber 6 and the lifting chamber 9 (shown in Figure 3 ) through the channel 5, and when the metal liquid level in the pressurizing chamber 6 and the lifting liquid 9 rises to the height of the liquid level sensor 7, The liquid level sensor 7 is connected due to the effect of metal conduction, and then sends out a signal, and the control system drives the hydraulic/pneumatic cylinder 3 to drive the stopper rod 4 down, closing the injection channel 5 (as shown in Figure 4), and the injection process is completed;

2) Pressurization/filling/holding/solidification stage: the liquid level pressurization control system injects dry air or inert gas on the surface of the molten metal in the pressurization chamber 6 through the pressurization port 8 to complete the filling of the molten metal , pressure-holding solidification process (shown in Figure 5);

3) Pressure relief stage: After the solidification is completed, the pressurization chamber 6 starts to exhaust and release pressure through the gas filling port 8, and the molten metal at the top of the liquid lifting chamber 9 falls back under the action of gravity until it is in contact with the metal in the pressurization chamber 6. Until the liquid level is even (as shown in Figure 6), then the mold opening, part picking, spraying, core setting (if necessary) and other actions can be performed on the working table, and one casting cycle is completed.

In addition, while the casting operation is being performed on the workbench, it can enter the material injection stage of the next casting cycle (injecting molten metal from the heat preservation chamber 1 into the pressurization chamber 6 and the liquid lifting chamber 9 to a specified height).

If the metal liquid level in the heat preservation chamber 1 is lower than the limit value (the limit value must ensure that the metal liquid level in the heat preservation chamber 1 is always higher than the metal liquid level in the pressurization chamber 6 and the liquid lifting chamber 9), it can be added by feeding Port 2 adds new molten metal to the holding chamber 4.

In order to be more conducive to the lifting and backflow of the liquid level in the lifting chamber, in this embodiment, the bottom of the pressurizing chamber and the lifting chamber can be designed to be inclined, and gradually slope upward from the pressurizing chamber to the rising chamber.

In this embodiment, the plug rod can move up and down through a hydraulic cylinder or a pneumatic cylinder. Liquid level sensor can choose liquid level electrode.

The utility model is further described below through specific examples, and compared with comparative examples.

Example 1

The low-pressure casting machine provided by the utility model is used to cast aluminum alloy cylinder head, the material of the cylinder head is ZL105 or ZL114, the casting mold is metal mold + sand core, the heat preservation chamber, the pressurization chamber and the liquid lifting chamber adopt crucible, the capacity of the crucible is 1500Kg, aluminum The liquid pouring temperature is 690°C, and the mold temperature is 200-300°C.

Injection: Open the stopper rod 4, and the aluminum alloy liquid that meets the requirements flows into the pressurization chamber 6 and the liquid lifting chamber 9 through the channel 5 between the heat preservation chamber 1 and the pressurization chamber 6. When the aluminum alloy liquid in the pressurization chamber 6 When the two poles of the liquid level sensor 7 are touched, the sensor is connected, and the hydraulic cylinder/pneumatic cylinder controls the plug rod 4 to close, and the filling process is completed;

Mold filling: A gas (dry air or inert gas) that does not react with the aluminum alloy liquid is introduced into the pressurized chamber 6, the gas supply system enters the pressurized chamber 6 from the pressurized port 8, and the molten metal passes through under pressure The liquid lifting chamber 9 is pressed into the mold of the aluminum alloy cylinder head, and the filling parameters such as the liquid level pressurization pressure and pressurization speed are stable and controllable, ensuring that the liquid level rises steadily and the exhaust is smooth during the filling stage, and the filling time is 55s about;

Holding pressure: After filling the mold, increase the holding pressure appropriately to improve the feeding capacity of the aluminum liquid, and the holding time is 3 minutes;

Pressure relief/mold removal: After the aluminum alloy cylinder head is solidified, the exhaust pressure is released, the aluminum alloy liquid in the lifting chamber 9 flows back, and the casting enters the mold removal stage. The time required for mold removal is about 2 minutes. At the same time, the plug rod 4 Open it for a new round of feeding, and the process of mold ejection and feeding will not interfere with each other and affect each other.

When the molten metal in the heat preservation chamber 1 is insufficient, it can be replenished by adding materials, and the replenishment can be carried out at any stage in the above process, that is, heat preservation can be implemented in the above stages of material injection, filling, pressure keeping, pressure relief and mold ejection The supplementary feeding process in chamber 1 realizes continuous production. And according to the state of molten aluminum, refining, slag removal and other processes are carried out in real time to improve the quality of molten aluminum.

Due to the realization of continuous production, the temperature of the aluminum liquid and the mold is stable, the quality of the castings and the pass rate are improved, the productivity reaches 10 pieces per hour, the shift output is 80 pieces, and the pass rate of the castings is over 98%.

Example 2

Adopt the low-pressure casting machine provided by the utility model to cast the aluminum alloy wheel hub, the material is ZL101, the casting mold is a metal type, the crucible capacity is 1800Kg, the aluminum liquid pouring temperature is 700°C, and the mold temperature is 200-300°C.

Operation process is described with embodiment 1.

Continuous production is realized, with a productivity of 14 pieces/hour and a shift output of 112 pieces.

Example 3

The low-pressure casting machine provided by the utility model is used to cast the aluminum alloy instrument cabin shell, the material is ZL114, the casting mold is a self-hardening resin sand mold, the crucible capacity is 1200Kg, and the aluminum liquid pouring temperature is 700°C.

Concrete operation process is described with embodiment 1.

The productivity reaches 8 pieces per hour, and the shift output is 64 pieces.

Comparative example 1

The aluminum alloy cylinder head is cast by a traditional top-mounted low-pressure casting machine.

The cylinder head material is ZL105 or ZL114, the casting mold is metal mold + sand core, the crucible capacity is 800Kg, the aluminum liquid pouring temperature is 690°C, and the mold temperature is 200-300°C.

The technological process is pressurized filling, pressure-holding solidification, and pressure-releasing mold ejection.

When the molten metal in the thermal insulation pouring crucible is used up, the supplementary feeding process is as follows: stop production, the thermal insulation crucible withdraws from the bottom of the workbench, open the crucible cover, pour the aluminum alloy liquid, remove the slag, cover the crucible cover (seal), and enter the work bottom of the table, and then proceed to normal production.

Continuous production cannot be realized, the productivity is 6 pieces per hour, the shift output is 40 pieces, and the qualified rate of castings is about 90%.

The technical solutions provided by the embodiments of the present invention have been introduced in detail above. In this paper, specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the above embodiments are only applicable to help understand the present invention. The principle of the embodiment; at the same time, for those of ordinary skill in the art, according to the embodiment of the present invention, there will be changes in the specific implementation and the scope of application. Utility model restrictions.

Claims (4)

1. A low-pressure casting device, comprising a heat preservation chamber and a mould, characterized in that: the device also includes a pressurization chamber, a liquid lifting chamber, a plug rod for controlling the closing of the injection channel, a liquid level pressurization control system, a liquid position sensor, The heat preservation chamber communicates with the pressurization chamber through the injection channel, the stopper rod is arranged above the injection channel opening, the pressurization chamber communicates with the lifting chamber, and the heat preservation chamber is provided with a feeding port; A liquid level sensor and a liquid level pressurization control device are arranged above the pressurization chamber, and the liquid level sensor is electrically connected to the liquid level pressurization control device; A mold is arranged above the liquid-lifting chamber, and the liquid-lifting chamber communicates with the mold. 2. The low-pressure casting device according to claim 1, characterized in that: the pressurization chamber and the bottom of the liquid lifting chamber are connected by a channel, and the bottom ends of the pressurizing chamber and the liquid lifting chamber are inclined, from the pressurization chamber to the liquid lifting chamber The direction gradually slopes upward. 3. The low-pressure casting device according to claim 1, wherein the plug rod moves up and down through a hydraulic cylinder or a pneumatic cylinder. 4. The low-pressure casting device according to claim 1, wherein the liquid level sensor is a liquid level electrode.

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