Non-riser casting mold for aluminum alloy cylinder cover and low-pressure mold filling casting method of non-riser casting mold

Abstract

A dead head-free casting mold for an aluminum alloy cylinder cover is characterized in that the lower part of a front mold is provided with an inward front mold bulge, the lower part of a rear mold is provided with an inward rear mold bulge, the inward front mold bulge and the inward rear mold bulge are assembled to form a lower mold, and an upper mold, a left end mold, a right end mold, the front mold and the rear mold are assembled to form a mold cavity. The bottom of the lower die is provided with a main pouring gate, an inner pouring gate and a pouring gate opening which are communicated with one another; and the pouring gate opening is sequentially connected with a transition sleeve and a riser tube. The casting method sequentially comprises the steps of sand core manufacturing and placing, liquid lifting, mold filling, pressurization and pressure maintaining and pressure relief, molten aluminum starts to be subjected to mold filling and feeding from the cover cap face of the cylinder cover, and solidification and feeding of the cylinder cover body are completed through the molten aluminum in a mold cavity by means of low-pressure gas through a heat preservation furnace under the pressure effect. According to the method, an independent lower die is not needed, a special riser sand core and the feeding effect of the riser sand core are not needed, the yield of the cylinder cover can be increased to about 90%, and the casting manufacturing cost of the cylinder cover is effectively reduced.

Description

Technical Field

[0001] The present invention relates to a casting mold and a casting method thereof, and particularly to an aluminum alloy cylinder head casting mold and a low-pressure filling casting method thereof. Background Art

[0002] In recent years, with the rapid development of the domestic automobile industry, the technologies of automobile engines and their key component products have become increasingly mature, and the localization of their key components (such as cylinder heads) has been gradually achieved. In addition, with the gradual localization of cylinder heads, the current traditional 90-degree tilting gravity casting process is increasingly widely used in cylinder heads. In this process, during casting, a 90-degree tilting casting machine is used to make the molten aluminum smoothly enter the mold cavity from the mold pouring basin under the action of gravity, and through processes and methods such as filling, solidification, and cooling, the product is formed by using risers to compensate for the shrinkage of the cylinder head product body. The main feature of this 90-degree tilting gravity casting process is to use risers to compensate for the shrinkage of the product body, so that the product has no casting defects such as shrinkage porosity, and its qualified rate is relatively high, but the yield is only about 50%. Therefore, this process has serious disadvantages such as low yield and high manufacturing cost. In addition, at present, some enterprises in the industry also use the low-pressure casting process to produce cylinder heads. The basic principle of its low-pressure casting is to apply low-pressure gas to drive the molten metal in the holding furnace, so that it rises through the riser pipe and enters the mold cavity. After the filling is completed, low-pressure gas is used to make the molten metal in the mold cavity complete solidification and compensation for shrinkage through the holding furnace. The main feature of this low-pressure casting process is to produce according to the principle of the low-pressure casting process, and its product yield can reach about 90%. However, the main technical disadvantage of this process is that the molten aluminum fills the mold from the combustion chamber surface of the cylinder head, and this part of the cylinder head is always in a high-temperature state during the production process, resulting in larger grain sizes and secondary dendrite arm spacings on the combustion chamber surface of the cylinder head, thus unable to meet the high technical requirements of high-performance engines or range extenders for new energy vehicles. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above deficiencies and provide an aluminum alloy cylinder head riserless casting mold and a low-pressure filling casting method thereof, which solve the problem that the low-pressure casting feeds from the combustion chamber surface of the cylinder head and cannot guarantee the technical performance such as the secondary dendrite arm spacing of the combustion chamber surface of the cylinder head, and at the same time can solve the problem that the gravity casting has a low yield of casting products due to riser compensation for shrinkage.

[0004] The object of the present invention is achieved by the following technical solutions: A riserless casting mold for an aluminum alloy cylinder head, comprising an upper mold, a left end mold, a right end mold, a front mold, and a rear mold. The lower part of the front mold has a front mold convexity inward, and the lower part of the rear mold has a rear mold convexity inward. After mold clamping, the front mold convexity inward and the rear mold convexity inward form a lower mold. The upper mold, the left end mold, the right end mold, the front mold, and the rear mold form a mold cavity after combination. The bottom of the lower mold has a main runner, an inner runner, and a runner opening that are interconnected. The runner opening is sequentially connected to a transition sleeve and a riser tube.

[0005] A water cooling mechanism is installed on the outer side of the upper mold, and a negative pressure air extraction mechanism is installed on the outer side of the front mold.

[0006] The low-pressure filling casting method adopted by the riserless casting mold for the aluminum alloy cylinder head is as follows: First, the upper water channel core, lower water channel core, intake air channel core, small exhaust channel core, large exhaust channel core, and oil cavity core corresponding to the aluminum alloy cylinder head are respectively made according to the sand core decomposition production process. There is no need for a special riser core and no need to make a special riser core mold. Then, each of the sand cores is placed into the riserless casting mold for the aluminum alloy cylinder head, and each of the sand cores is clamped by a clamping mechanism corresponding to the left end mold, the right end mold, the front mold, the rear mold, and the upper mold. Next, after the casting mold is clamped, it is flipped 180 degrees by a flipping mechanism. Relative to the cylinder head, the combustion chamber surface of the cylinder head faces upward and the cover surface of the cylinder head faces downward. The aluminum liquid starts to fill and feed from the cover surface of the cylinder head. Then, the flipped casting mold is moved above a holding furnace by a conveying and moving mechanism to dock the holding furnace with the casting mold. Then, according to the low-pressure casting principle, low-pressure gas is used to drive the aluminum liquid in the holding furnace, so that it rises through the riser tube and enters the mold cavity of the casting mold for filling. The low-pressure gas is used through the holding furnace to complete the solidification and feeding of the aluminum liquid in this mold cavity under pressure for the cylinder head. At the same time, during the entire riser process, the negative pressure air extraction mechanism is turned on to discharge the gas generated due to the setting of each sand core, thereby avoiding air holes in the cylinder head casting. The water cooling mechanism is turned on to cool the hot spot parts of the cylinder head casting, thereby avoiding shrinkage porosity casting defects in the cylinder head casting. After pressure relief, the flipping mechanism flips the casting mold 180 degrees in the opposite direction to return to the original position, and the casting mold is opened again to take out the cylinder head casting.

[0007] The upper mold, the left end mold, the right end mold, the front mold, and the rear mold of the casting mold are respectively installed on the upper template, left template, right template, front template, and rear template of the casting system equipment.

[0008] After adopting the present invention, the interior of the casting mold is formed such that the combustion chamber corresponding to the cylinder head faces upward and the cover surface faces downward, and the molten aluminum is filled and fed from the cover surface of the cylinder head. As a result, the temperature at the combustion chamber position of the cylinder head is relatively low and the solidification is relatively fast, making the secondary dendrite arm spacing at this combustion chamber position smaller (higher density), meeting the relevant high-tech requirements. In addition, after the casting mold is closed, it forms the lower mold without a separate lower mold. This casting method for the cylinder head does not require a special riser for feeding, but relies on low-pressure gas to allow the molten aluminum in the mold cavity to complete the solidification and feeding of the cylinder head body under pressure through a holding furnace. This not only enables the yield of the cylinder head to be increased to about 90%, thus effectively reducing the casting manufacturing cost of the cylinder head, but also does not require the production of a special riser core and riser core mold, thereby greatly reducing the core manufacturing cost and eliminating the manufacturing cost of the cylinder head riser. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. is a schematic structural view of the riserless casting mold for an aluminum alloy cylinder head of the present invention.

[0010] Figure 2 FIG. is a process diagram of the casting method adopted by the present invention (the cover surface of the cylinder head faces upward, forming the cylinder head casting and removing the transition sleeve).

[0011] Figure 3 FIG. is a schematic exploded view of each core applied in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be further described below in conjunction with the drawings and the detailed description of the invention.

[0013] Referring to Figure 1 、 Figure 2 It can be seen that the riserless casting mold for an aluminum alloy cylinder head of the present invention includes an upper mold 5, a left end mold 2, a right end mold 6, a front mold 8, and a rear mold 3. The lower part of the front mold 8 has an inward front mold protrusion 28, and the lower part of the rear mold 3 has an inward rear mold protrusion 23 (corresponding to the position of the inward front mold protrusion 28). After the mold is closed, the inward front mold protrusion 28 and the inward rear mold protrusion 23 form the lower mold 11 (without a separate lower mold, that is, no special riser core mold is required and the riser core is omitted). After the upper mold 5, the left end mold 2, the right end mold 6, the front mold 8, and the rear mold 3 are combined (i.e., after the mold is closed), they form a mold cavity 1. The bottom of the lower mold 11 has a main runner 13, an inner runner 12, and a runner opening 14 (at the bottom of the casting mold) that are interconnected. The runner opening 14 is sequentially connected to a transition sleeve 9 and a riser pipe 10.

[0014] A water cooling mechanism 4 is installed on the outer side of the upper mold 5 (cooling the hot spots and combustion chamber parts of the cylinder head to avoid shrinkage porosity casting defects in the cylinder head casting, and at the same time making the combustion chamber of the cylinder head more dense), and a negative pressure air extraction mechanism 7 is installed on the outer side of the front mold 8 (discharging the gas generated due to the setting of each core to avoid porosity in the cylinder head casting).

[0015] Relative to the cylinder head, the combustion chamber surface of the cylinder head faces upward and the cover surface of the cylinder head faces downward, and the molten aluminum starts to fill the mold from the cover surface of the cylinder head. The upper mold, left end mold, right end mold, front mold, and rear mold of the casting mold (made of metal) are respectively installed on the upper template, left template, right template, front template, and rear template of the casting system equipment.

[0016] The low-pressure filling casting method adopted by the riserless casting mold for the aluminum alloy cylinder head is as follows: First, the upper water channel core 16, lower water channel core 19, intake air channel core 21, small exhaust channel core 18, large exhaust channel core 17, oil cavity core 15 (and other cores 20, as Figure 3 shown) corresponding to the aluminum alloy cylinder head are made according to the core decomposition manufacturing process. There is no need for a special riser core (that is, no need to make a special riser core mold). Then, each of the cores is placed into the riserless casting mold for the aluminum alloy cylinder head, and each of the cores is pressed by a pressing mechanism corresponding to the left end mold 2, right end mold 6, front mold 8, rear mold 3, and upper mold 5 (to prevent the position of each core from shifting during the flipping process); Next, after the casting mold is closed, it is flipped 180 degrees by the flipping mechanism. Relative to the cylinder head, the combustion chamber surface of the cylinder head faces upward and the cover surface of the cylinder head faces downward, and the molten aluminum starts to fill the mold from the cover surface of the cylinder head; Then, the flipped casting mold is moved above the holding furnace by the conveying and moving mechanism to dock the holding furnace with the casting mold. Then, according to the low-pressure casting principle, low-pressure gas is used to drive the molten aluminum in the holding furnace, so that it rises through the riser pipe 10 and enters the mold cavity of the casting mold for filling. The molten aluminum in this mold cavity is solidified and compensated under pressure (that is, pressurization and pressure holding) by using low-pressure gas through the holding furnace to complete the cylinder head; At the same time, during the entire riser process, the negative pressure air extraction mechanism is turned on to discharge the gas generated due to the setting of each core, thereby avoiding porosity in the cylinder head casting. The water cooling mechanism is turned on to cool the hot spots and combustion chamber parts of the cylinder head casting, thereby avoiding shrinkage porosity casting defects in the cylinder head casting, and at the same time making the combustion chamber of the cylinder head more dense (that is, the secondary dendrite arm spacing in this combustion chamber part reaches higher performance requirements); After pressure relief, the flipping mechanism flips the casting mold 180 degrees in the opposite direction to return to its original position, and then the casting mold is opened again to take out the cylinder head casting 22.

[0017] The main runner 13 and the inner runner 12 are located at the bottom of the lower mold of the casting mold (i.e., between the lower mold and the transition sleeve). The runner opening 14 is sequentially connected to the transition sleeve 9 and the riser 10. The riser 10 is installed on the holding furnace. Then, through the driving and pressurization of the low-pressure machine, the pressurization mechanism, and the pressurization driving device, the molten aluminum in the holding furnace sequentially passes through the riser 10, the transition sleeve 9, the runner opening 14, the main runner 13, and the inner runner 12 and smoothly enters the mold cavity 1 for filling (filling the mold cavity in a laminar flow manner to form a cylinder head casting), as Figure 2 shown (when in actual use, the riser is downward). The technological steps (and parameters) adopted are as follows: liquid lifting, filling, pressure boosting and holding pressure, and pressure relief. The molten aluminum in the mold cavity is made to complete the solidification and feeding of the cylinder head body under the action of pressure (i.e., pressure boosting and holding pressure) by using low-pressure gas to pass through the holding furnace. The temperature of the molten aluminum is 705 ± 5 °C, the liquid-lifting pressure is 20 Kpa, the holding-pressure is 22 Kpa, the filling time is 22 S, and the holding-pressure time is 300 S. After the pressure relief is completed, the flipping mechanism flips the casting mold 180 degrees in the reverse direction to return to the original position, and then the casting mold is opened again to take out the cylinder head casting therein (after forming the cylinder head casting product, the main runner 13, the inner runner 12, and the runner opening 14 of the cylinder head casting are all cut off by a sawing machine). This casting method requires the use of a holding furnace (containing molten aluminum), a low-pressure machine, a pressurization mechanism, a pressurization driving device, etc. (collectively referred to as low-pressure system equipment), and requires the use of a flipping mechanism (realizing a 180-degree flip), a conveying and moving mechanism, a casting mold (containing relevant sand cores), and a pressing mechanism, an upper template, a left template, a right template, a front template, a rear template, etc. (collectively referred to as casting system equipment).

Claims

1. The riserless casting die for aluminum alloy cylinder head, comprising an upper die, a left end die, a right end die, a front die and a rear die, is characterized in that: The lower part of the front mold has an inward front mold protrusion, and the lower part of the rear mold has an inward rear mold protrusion. After mold clamping, the inward front mold protrusion and the inward rear mold protrusion form a lower mold. The upper mold, left end mold, right end mold, front mold, and rear mold form a mold cavity after combination. The bottom of the lower mold has a main runner, an inner runner, and a runner gate that communicate with each other. The runner gate is sequentially connected to a transition sleeve and a riser tube.

2. The riserless casting mold for aluminum alloy cylinder head according to claim 1, characterized in that: A water cooling mechanism is installed on the outer side of the upper mold, and a negative pressure air extraction mechanism is installed on the outer side of the front mold.

3. The low-pressure filling casting method adopted by the riserless casting mold for aluminum alloy cylinder heads according to claim 2, characterized in that: First, the upper water channel core, lower water channel core, intake air channel core, small exhaust channel core, large exhaust channel core, and oil cavity core corresponding to the aluminum alloy cylinder head are respectively manufactured according to the sand core decomposition manufacturing process. There is no need for a special riser core or a special riser core mold. Then, each of the sand cores is placed into the riserless casting mold for the aluminum alloy cylinder head, and each of the sand cores is pressed by a pressing mechanism corresponding to the left end mold, right end mold, front mold, rear mold, and upper mold. Next, after the casting mold is clamped, it is flipped 180 degrees by a flipping mechanism. Relative to the cylinder head, the combustion chamber surface of the cylinder head faces upward and the cover surface of the cylinder head faces downward, and the molten aluminum starts to fill the mold from the cover surface of the cylinder head. Then, the flipped casting mold is moved above the holding furnace by a conveying and moving mechanism to dock the holding furnace with the casting mold. Then, according to the low-pressure casting principle, low-pressure gas is used to drive the molten aluminum in the holding furnace, so that it rises through the riser tube and enters the mold cavity of the casting mold for filling. The low-pressure gas is used through the holding furnace to make the molten aluminum in this mold cavity complete the solidification and feeding of the cylinder head under pressure. At the same time, during the entire riser process, the negative pressure air extraction mechanism is turned on to discharge the gas generated due to the setting of each sand core, thereby avoiding air holes in the cylinder head casting. The water cooling mechanism is turned on to cool the hot spots and combustion chamber parts of the cylinder head casting, thereby avoiding shrinkage porosity casting defects in the cylinder head casting and at the same time making the combustion chamber of the cylinder head have higher density. After pressure relief, the flipping mechanism flips the casting mold 180 degrees in the opposite direction to return to its original position, and the casting mold is opened again to take out the cylinder head casting.

4. The low-pressure filling casting method adopted by the riserless casting mold for aluminum alloy cylinder heads according to claim 3, characterized in that: The upper mold, left end mold, right end mold, front mold, and rear mold of the casting mold are respectively installed on the upper template, left template, right template, front template, and rear template of the casting system equipment.

5. The low-pressure filling casting method adopted by the riserless casting mold for aluminum alloy cylinder heads according to claim 3, characterized in that: The temperature of the molten aluminum is 705 ± 5 °C, the riser pressure is 20 Kpa, the holding pressure is 22 Kpa, the filling time is 22 S, and the holding time is 300 S.

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