Patent Application
20150273576
Priority is claimed to Chinese Application No. 201410118421.4, filed Mar. 27, 2014, and the entire contents thereof are hereby incorporated by herein reference.
The present invention relates to a forming equipment for refining and casting aluminum alloy.
The embryonic form of low pressure casting can be traced back to the beginning of last century. The proposal of applying low pressure casting to manufacture aluminum alloy was firstly put forward in 1917 in France and in 1924 in Germany, but large-scale industrial production didn't follow thereafter. It was from 1945 after the World War II when aluminum alloy was manufactured with this method for commercial purposes. In 1958 an American automobile manufacturer employed plenty of aluminum alloy casts which are fabricated by means of low pressure casting to produce engine parts of compact cars. Low pressure casting was introduced into China in 1957 or so, but it was approximately from 1960 when the method was paid sincere attention marked by extensive study and importation of equipments. However, professionals in the field did not attach much importance to it, since this epoch-making method, which broke through the principles of common knowledge in the art and almost don't need any flash groove, presented technical difficulties completely different from the gravity metal casting method which had been established as a “technology”. Under this circumstance, the production of air cooling cylinder heads used in light cars in 1961 became an outset of practical using of low pressure casting in China. Thereafter, this technique developed rapidly. After overcoming multiple technical problems and thanks to such advantages as high material utilization rate, easy to automate molding etc, low pressure casting has gradually become a major casting method for light alloy casts, in particular for automobile parts. Low pressure casts have been accounting for about 50% of all aluminum alloy casts and are famous around the world for their enormous output and excellent quality. The products have been used for other parts of automobile. In particular after 1970 low pressure casting was employed extensively to manufacture wheels. And also, with requirements for improved performance and light weight of automobiles as well as such unprecedented strict requirements for sophisticated inner qualities and mechanical properties, low pressure casting was increasingly employed to manufacture cylinder heads and cylinder blocks. However, the current low pressure casting is executed in a way that the aluminum fluid refined is poured into a holding furnace of low pressure casting machine through casting ladle, and then heated radiatively in the holding furnace by a heating rod in the upper part of the holding furnace so as to keep temperature. In the hermetical holding furnace, pressure is applied onto the surface of the aluminum fluid through dry compressed air of low pressure so that the aluminum fluid rises through a lifting tube inserted in the aluminum fluid and is pressed into a mould cavity connected above the holding furnace. The aluminum fluid is slowly filled into the cavity from its lower part and solidifies after the pressure being kept for a period of time. At last the cast can be taken out when it cools to below its solid phase temperature. The drawbacks of this method include: the aluminum fluid is heated by radiative heating of the heating rod in the upper part of the furnace to keep temperature, which heating is uneven, namely the temperature in the upper portion is higher while the temperature in the lower portion is lower; the aluminum fluid refined would be oxidized by absorbing air in the process of being poured into the holding furnace, weakening the refining effect; it is compressed air at room temperature that enters the holding furnace, which adds to oxidation of the aluminum fluid in the holding furnace; in addition, the high temperature air in the furnace is discharged directly into the atmosphere after depressurization, resulting in heat loss and thus energy waste.
The object of the present invention is to provide an integrated equipment for aluminum alloy refining and low pressure casting to resolve the above-mentioned problems.
The technical solution for achieving the above object is as follows: the body frame of a low pressure casting machine is mounted with a mould, and the body frame of the low pressure casting machine is mounted with a holding furnace at its lower portion; the holding furnace is divided into two furnace chambers, that is, fluid refining chamber and pressure casting chamber, the two furnace chambers are connected at their lower portions through a passage with a gate valve and a filter; the two furnace chambers are each provided with immersing electric heaters at their lower portions, and the fluid refining chamber is provided at its bottom portion with permeable bricks at regular intervals, which bricks are connected with a compressed inert gas tank via an intake tube having an electric proportional valve B; the fluid refining chamber is provided at its middle-upper portion with a furnace gate; the two furnace chambers are connected at their upper portions through a connecting pipe with an electric valve; the pressure casting chamber is connected at its upper portion with the sprue of the mould through the lifting tube and a suction tube, and the lifting tube is provided at its lower portion with a filtering screen; the pressure casting chamber is provided at its upper portion with a pressure relief tube having an electric proportional valve A, which tube is connected with a gas tank.
After being refined in the fluid refining chamber, aluminum fluid doesn't contact air so that it will not be reoxidized, enabling manufacture of casts with fine quality. Meanwhile, immersing electric heating is employed in the holding furnace of the present invention to improve the temperature uniformity of aluminum fluid and the heating efficiency. After completing the pressure casting, the inert gas at high temperature will not be discharged directly into the atmosphere but into a gas tank so that it can be reused after being purified, improving utilization rate of resource and energy.
In the drawing, the reference numbers represent the following components respectively: 1—body frame of low pressure casting machine, 2—mould, 3—suction tube, 4—holding furnace, 4-1—fluid refining chamber, 4-2—pressure casting chamber, 5—pressure relief tube, 6—electric proportional valve A, 7—lifting tube, 8—filtering screen, 9—intake tube, 10—electric proportional valve B, 11—base of the holding furnace, 12—immersing electric heaters, 13—gate valve, 14—filter screen, 15—permeable bricks, 16—furnace gate, 17—connecting pipe, 18—electric valve.
The specific embodiment according to the present invention will be described in conjunction with the drawing.
As shown in the drawing, the body frame 1 of a low pressure casting machine of the equipment (as shown in
Aluminum fluid is injected into the fluid refining chamber 4-1 of the holding furnace 4 through the furnace gate 16 and then the furnace gate is closed tightly. By opening the gate valve 13 and the electric proportional valve B 10, the aluminum fluid in the fluid refining chamber 4-1 flows via the passage into the pressure casting chamber 4-2 under effect of the gravity and gas pressure. The gate valve 13 and the electric proportional valve B 10 are closed when the aluminum fluid in the pressure casting chamber 4-2 reaches the upper limit.
All valves should be closed at beginning of the operation. The electric valve 18 and the electric proportional valve B 10 are opened at the beginning of casting with the latter being operated according to the pressure curve of the pressure casting chamber 4-2 set by IPC (Industrial Personal Computer). Inert gas passing the permeable bricks 15 forms small bubbles to refine the aluminum fluid in the fluid refining chamber 4-1, and after finishing the refining process the gas enters the pressure casting chamber 4-2 through the connecting pipe 17. Under gas pressure, the aluminum fluid in the pressure casting chamber 4-2 enters the cavity of the mould 2 along the lifting tube 7 and the suction tube 3 so as to be molded. After the pressure in the pressure casting chamber 4-2 reaches a set holding pressure, the electric valve 18 and the electric proportional valve 10 are closed to hold the pressure. The electric proportional valve A 6 in the pressure relief tube 5 and the electric valve 18 are opened after the aluminum fluid in the mould 2 is solidified into a cast, and the electric proportional valve A 6 in the pressure relief tube 5 and the electric valve 18 are closed after the pressure in the pressure casting chamber 4-2 reaches a predetermined pressure value. Finally, the mould 2 is opened and the cast is taken out of it, completing a whole casting cycle.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201410118421.4 | Mar 2014 | CN | national |
