TWI580497B - Negative pressure suction method - Google Patents

Description

Negative pressure suction casting method

The invention relates to a casting method, in particular to a negative pressure suction casting method for sucking molten steel into a mold by using a negative pressure to form a casting.

Please refer to Figure 5 for the gravity casting method of the conventional steel foundry. The main method is to melt the steel to 1450~1700 °C in a melting furnace, then place the high temperature molten steel in the iron drum d, and then pour the molten steel into the pouring. In the pre-made mold a, the molten steel is passed through the pouring pool b1, the vertical runner b2 and the flow passage b3 of the flow path system b by gravity, and flows into the cavity c through the water inlet b4. After the molten steel is cooled and solidified, it is taken out from the mold a, and after proper cleaning and processing, the required castings can be obtained.

Most of the above casting methods are used in the casting of steel files. However, based on the consideration of casting cost and casting quality, it has the following disadvantages:

1. For castings with a thickness of about 3.5 mm or less, when the molten steel is poured into the sand mold by gravity, the molten steel needs to pass through the flow path system. However, due to the blockage of air in the cavity, the flow rate of the molten steel will not be too fast, and the thinner the thickness of the meat, the slower the flow rate. The longer the flow path, the faster the molten steel will cool. Therefore, if the temperature of the molten steel is not high, the flow is low. Insufficient sex will make casting thin meat difficult, and it is not easy to cast excellent products.

2. When the melting temperature increases to 1700 ° C, even after the higher temperature, although the fluidity of the molten steel can be increased to form a thin meat casting, but after the melting temperature increases, it will not only increase The power consumption will greatly shorten the life of the refractory material of the melting furnace, and increase the frequency of replacement of the refractory material. As a result, the replacement cost of the refractory material and the capacity reduction caused by the replacement shutdown will be increased. Furthermore, when the molten steel melting temperature exceeds 1700 ° C, the refractory material in the melting furnace is melted into the molten steel, which causes an increase in oxide impurities in the molten steel, which affects the purity and mechanical properties of the steel casting.

3. During the pouring process, the molten steel needs to be filled with a flow path system including a pouring pool, a vertical sprue and a flow passage to flow into the cavity, and the molten steel in the flow path system and the molten steel in the cavity At the same time, it is cooled and solidified The molten steel remains in the flow path system and consumes more molten steel, so that the ratio of the casting to the total poured molten steel (that is, the step retention rate) cannot be effectively improved, and the retention rate cannot be effectively improved, that is, the molten steel cannot be saved, and it cannot be effective. Save energy and reduce production costs.

In view of the above, in order to provide a structure different from the conventional technology and to improve the above disadvantages, the inventors have accumulated many years of experience and continuous development and improvement, and the present invention has been produced.

An object of the present invention is to provide a negative pressure suction-injection casting method, which can solve the problem that the casting of thin meat is difficult to be formed when the temperature of the conventional molten steel is not high, so as to meet the requirements for the use of the thin meat of the casting.

An object of the present invention is to provide a negative pressure suction and pouring method, which can solve the disadvantages of excessive melting temperature of conventional molten steel, thereby reducing power consumption, reducing refractory wear and replacement frequency, improving casting purity and mechanical performance, and Can reduce production costs.

An object of the present invention is to provide a vacuum suctioning and pouring method, which can solve the problem that the excessively used molten steel stays in the flow path system and the step retention rate cannot be improved, thereby saving the cost of recycling the molten steel, and Effectively increase production.

One of the objects of the present invention is to provide a negative pressure suction and pouring method. The casting method must be cast in iron drums, eliminating the need to use iron drums and related equipment to reduce production costs.

In order to achieve the above object, the present invention provides a negative pressure sucking and pouring method for at least one casting to mold at least one casting, wherein the mold is provided with a connecting cavity and a flow path system, and the negative pressure is sucked. The pouring method comprises the steps of: a. capping a flat plate with a straw to the top of the melting furnace, the melting furnace containing molten molten steel, and the bottom end of the straw is inserted into the molten steel; b. forming on the mold Connecting the air passage of the cavity, and placing the mold on the flat plate, so that the flow path system of the mold communicates with the top end of the suction pipe; c. Covering a cover body above the mold and the flat plate, and extracting the air inside the cover body, Decreasing the air pressure in the cover body and the cavity, extracting the molten steel in the melting furnace upward through the suction pipe, and flowing the molten steel into the cavity; and d. standing for a period of time, allowing the flow path system to enter between the cavity The nozzle is solidified, and the air negative pressure state in the hood is released, so that the molten steel in the flow path system flows back into the melting furnace.

In practice, the invention further includes a step of removing the cover after the step d and separating the mold from the plate.

In practice, the mold is a sand mold, and the air passage on the mold is the sand gap of the sand mold, and the temperature of the molten steel in the melting furnace is between 1400 and 1550 °C.

In order to further understand the present invention, the specific embodiments of the present invention and the effects achieved thereby are described in detail below with reference to the drawings and drawings.

2‧‧‧melting furnace

3‧‧‧ tablet

4‧‧‧Sipper

5‧‧‧ mould

51‧‧‧ cavity

52‧‧‧Air passage

53‧‧‧Flow system

531‧‧‧ entrance

54‧‧‧ Inlet

6‧‧‧ Cover

61‧‧‧Exhaust pipe

9‧‧‧Steel

A‧‧‧ mould

b‧‧‧Flow system

B1‧‧‧Pooling pool

B2‧‧‧spindle

B3‧‧‧ flow path

B4‧‧‧ Inlet

C‧‧‧ cavity

D‧‧‧iron bucket

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded view of the components used in the preferred embodiment of the invention.

Figure 2 is a schematic cross-sectional view showing the combination of the elements used in the preferred embodiment of the present invention.

Figure 3 is a view showing the state of use of a preferred embodiment of the present invention when a negative pressure is formed.

Fig. 4 is a view showing the state of use of the molten steel countercurrent melting furnace of the preferred embodiment of the present invention.

Fig. 5 is a schematic view showing a state of use in which a molten steel is poured into a mold by a conventional sand mold casting method.

Please refer to FIGS. 1 to 4, which are preferred embodiments of the negative pressure suction casting method of the present invention, which include the following steps:

a. The flat plate 3 having the straw 4 is capped to the top of the melting furnace 2, and the molten furnace 2 contains molten molten steel 9, and the bottom end of the suction pipe 4 projects into the molten steel 9.

b. An air passage 52 communicating with the cavity 51 is formed in the mold 5, and the mold 5 is placed on the flat plate 3 so that the flow path system 53 of the mold 5 communicates with the top end of the suction pipe 4.

c. Covering the cover 6 above the mold 5 and the flat plate 3, and extracting the air in the cover 6, reducing the air pressure in the cover 6 and the cavity 51, and sucking up the inside of the melting furnace 2 via the suction pipe 4. The molten steel 9 causes the molten steel 9 to flow into the cavity 51 to form a casting. as well as

d. After standing for a period of time, the water inlet 54 between the flow path system 53 and the cavity 51 is solidified, and then the air negative pressure state in the cover 6 is released, so that the molten steel in the flow path system 53 flows back to the melting furnace 2 Inside.

Wherein, the melting furnace 2 of the step a is a coil heating melting furnace; the melting temperature of the molten steel 9 is controlled between 1400 and 1550 ° C; the suction pipe 4 passes vertically through the flat plate 3, and the bottom end opening of the suction pipe 4 extends. In the molten steel 9, the top end opening of the straw 4 is substantially flush with the top surface of the flat plate 3.

The mold 5 of the step b is a sand mold, and the air passage 52 on the mold 5 is a gap between the sand grains of the sand mold for generating a gas permeable effect; the inlet 531 of the flow path system 53 of the mold 5 is formed on the bottom surface of the mold 5, Therefore, when the mold 5 is placed on the flat plate 3, the inlet 531 is aligned with the top end of the suction pipe 4. The opening is such that the flow path system 53 of the mold 5 communicates with the top end of the suction tube 4.

In the step c, the cover body 6 is a hollow container having an open bottom surface, and the top end of the cover body 6 is connected with an air suction pipe 61, so that when the cover body 6 is covered over the mold 5 and the flat plate 3, the cover is evacuated by a vacuum pump. The air in the body 6 and the air pressure in the casing 6 can be made the same as the air pressure in the cavity 51, the flow path system 53, and the suction pipe 4 due to the gas permeability of the mold 5. Therefore, the molten steel 9 in the melting furnace 2 is extracted by the negative pressure, so that the molten steel 9 flows upward through the suction pipe 4, and flows into the cavity 51 via the flow path system 53. In practice, the cavity 51 may also be provided with several pieces to simultaneously form a plurality of castings.

In step d, after the molten steel 9 flows into the cavity 51, it is allowed to stand for a while, and the molten steel 9 in the cavity 51 has not completely solidified, and the flow path system 53 and the cavity 51 are advanced. When the nozzle 54 has solidified, the air negative pressure state in the cover body 6 is released, and the molten steel 9 which has not been solidified in the flow path system 53 is returned downwardly back into the melting furnace 2.

After the molten steel 9 is completely returned to the melting furnace 2, the cover 6 is removed, and the mold 5 is separated from the flat plate 3, the molten steel 9 in the mold 5 is continuously cooled, and the new mold 5 is repositioned on the flat plate 3. When it is up, the pouring operation can be performed again.

Therefore, the present invention has the following advantages:

1. In the invention, the molten steel is sucked into the cavity by means of suction under negative pressure, and the thickness of the casting can be reduced by less than 2.5 mm. Therefore, for products with special needs, the thinness of the casting can be caused. Meet the requirements of use.

2. The invention draws molten steel into the cavity by means of suction under negative pressure, even though the temperature of the molten steel is between 1400 and 1550 ° C, it can flow smoothly in the flow system, therefore, through the molten steel The reduction of the melting temperature not only reduces the power consumption to save energy, but also reduces the loss of refractory material and melts into the molten steel to improve the purity and mechanical properties of the casting, and can reduce the refractory material of the melting furnace. Change frequency to reduce production costs.

3. The invention can make the molten steel which has not been solidified flow back into the melting furnace after the pouring is completed, so as to provide the next pouring use, thereby effectively improving the retention rate, not only saving the cost of recycling and re-production, but also increasing the output. .

4. The invention draws molten steel into the cavity by means of suction in a negative pressure manner, can reduce the melting temperature of the molten steel, and uses a shorter flow path system, when the molten steel which has not been solidified flows back into the melting furnace, No impurities are mixed in the molten steel, so impurities can be prevented from affecting the mechanical properties of the steel casting.

5. The melting furnace of the present invention is a melting furnace for coil heating, which can directly supply the molten steel, and the suction pipe can be sucked to form a casting. Therefore, not only is the casting procedure simpler and more efficient, and there is no need to use the iron drum. And related equipment, which can reduce production costs.

In summary, according to the above disclosure, the present invention can achieve the intended purpose, and provides a negative pressure which can not only make the casting thin, reduce the production cost, increase the yield, and the process is simple, and the quality of the casting can be ensured. The method of sucking and pouring is very valuable for industrial use, and the invention patent application is filed according to law.

2‧‧‧melting furnace

3‧‧‧ tablet

4‧‧‧Sipper

5‧‧‧ mould

51‧‧‧ cavity

52‧‧‧Air passage

53‧‧‧Flow system

531‧‧‧ entrance

6‧‧‧ Cover

61‧‧‧Exhaust pipe

9‧‧‧Steel

Claims (2)

A negative pressure sucking and pouring method is for forming a plurality of castings by a plurality of casting molds, each of which is provided with a connecting cavity and a flow path system and an air passage communicating with the cavity, and each mold is a sand mold, The air passage is a gap between the sand grains of the sand mold; the negative pressure suction casting method comprises the following steps: a. Covering a flat plate with a straw to the top of a melting furnace, the melting furnace is filled with molten steel a liquid, and the bottom end of the straw extends into the molten steel; b, one of the plurality of molds is placed on the plate, so that the flow path system of the mold communicates with the top end of the straw; A cover is attached to the mold and the flat plate, and the air in the cover body is extracted to reduce the air pressure in the cover body and the cavity, and the molten steel in the melting furnace is sucked upward through the suction pipe to flow the molten steel into the mold. d, after standing for a period of time, when the molten steel in the water inlet between the flow path system and the cavity is solidified, but the molten steel in the cavity is not completely solidified, the negative air pressure state in the cover body is released. Reversing the molten steel in the flow path system back into the melting furnace, And after the molten steel in the flow path system completely flows back into the melting furnace, the cover body is removed, and the molten steel in the water inlet is solidified, but the mold in which the molten steel in the cavity is not completely solidified is separated from the flat plate and removed; e. Repeat steps b through d using the aforementioned cover until the molding of the plurality of molds described above is completed. The vacuum suction casting method according to claim 1, wherein the molten steel in the melting furnace has a temperature between 1400 and 1550 °C.