PREPARATION METHOD FOR ALUMINUM ALLOY CAVITY CASTING FILLED WITH SPECIAL-SHAPED FOAMED ALUMINUM

Abstract

The application discloses a preparation method for an aluminum alloy cavity casting filled with special-shaped foamed aluminum. The preparation method includes: preparing special-shaped foamed aluminum in a first mold by adopting a powder metallurgy foaming method; fixing the special-shaped foamed aluminum coated with the soldering flux in a second mold after the special-shaped foamed aluminum is coated with soldering flux; and casting by using molten aluminum alloy. According to the preparation method for the aluminum alloy cavity casting filled with the special-shaped foamed aluminum, the overall strength of the casting can be improved while the wall thickness of the casting is reduced to meet the requirement that the overall quality of the casting is not increased.

Claims

1. A preparation method for an aluminum alloy cavity casting filled with special-shaped foamed aluminum, characterized in that the preparation method comprises: preparing special-shaped foamed aluminum in a first mold by adopting a powder metallurgy foaming method; fixing the special-shaped foamed aluminum coated with the soldering flux in a second mold after the special-shaped foamed aluminum is coated with soldering flux; and casting by using molten aluminum alloy.

2. The preparation method according to claim 1, characterized in that the step of preparing the special-shaped foamed aluminum in the first mold by adopting the powder metallurgy foaming method comprises: preparing foaming precursors by a powder pressing method after pure aluminum powder and titanium hydride are uniformly mixed; putting the plurality of the foaming precursors into the preheated first mold for foaming; and taking out the foamed material after heat preservation, and cooling.

3. The preparation method according to claim 1, characterized in that the isovolumetric density of the special-shaped foamed aluminum is 0.2-0.4 g/mm.sup.3, and the thickness of a surface shell is 1-2 mm.

4. The preparation method according to claim 1, characterized in that the step of coating the special-shaped foamed aluminum with the soldering flux comprises: soaking the special-shaped foamed aluminum in the soldering flux which is heated to 80-100° C. for 3-10 min, then taking out the soaked special-shaped foamed aluminum, drying, heating to 500-600° C., and conducting heat preservation; preferably, the soldering flux is a potassium fluorotitanate aqueous solution with a concentration of 5-15%.

5. The preparation method according to claim 1, characterized in that the step of fixing the special-shaped foamed aluminum coated with the soldering flux in the second mold after the special-shaped foamed aluminum is coated with soldering flux comprises: heating the second mold to 350-450° C. in advance, spraying a layer of coating on the inner surface of the second mold, then putting the special-shaped foamed aluminum coated with the soldering flux on the surface into the second mold to be fixed, and closing the mold in place.

6. The preparation method according to claim 1, characterized in that the step of casting comprises pouring the molten aluminum alloy of 660-700° C. into the second mold where the special-shaped foamed aluminum is fixed.

7. The preparation method according to claim 1, characterized in that the preparation method further comprises a step of carrying out post-treatment on the casting.

8. The preparation method according to claim 1, characterized in that an aluminum alloy wall thickness of the casting is 4-8 mm.

9. An aluminum alloy cavity casting filled with special-shaped foamed aluminum, characterized by being prepared by the preparation method according to claim 1.

10. The aluminum alloy cavity casting filled with the special-shaped foamed aluminum according to claim 9, characterized in that the aluminum alloy cavity casting is a steering knuckle component or an auxiliary frame component of a chassis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a structural schematic diagram of a steering knuckle component of a chassis filled with foamed aluminum, wherein (a) is a steering knuckle, and (b) is special-shaped foamed aluminum filled in the steering knuckle; and

[0032] FIG. 2 is a structural schematic diagram of an auxiliary frame component of a chassis filled with foamed aluminum, wherein (a) is an auxiliary frame, and (b) is special-shaped foamed aluminum filled in the auxiliary frame.

DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the invention are clearly and completely described in combination with the embodiments of the invention and the accompanying drawings of the invention, and obviously, the described embodiments are only a part of the embodiments of the invention, but not all the embodiments of the invention. Based on the embodiments of the present invention, other embodiments obtained by those of ordinary skill in the art without creative work all belong to the scope of protection of the present invention.

[0034] The invention is further described below with reference to the illustrative examples shown in the accompanying drawings. According to the following description, the advantages in various aspects of the invention are more obvious. The same reference signs in the drawings refer to the same components. The shape and the size of each component in the schematic drawings are only used for illustration, and cannot be considered to reflect the actual shape, size and absolute position.

[0035] The preparation method for the aluminum alloy cavity casting filled with the special-shaped foamed aluminum provided by the invention generally includes the following steps:

[0036] (1) preparation of special-shaped foamed aluminum: firstly, pure aluminum powder and titanium hydride are uniformly mixed, and foaming precursors are prepared by adopting a powder pressing method; then, a plurality of foaming precursors are put into a first mold which is preheated to about 700° C. for foaming, and the foamed material is taken out after heat preservation for 3-5 min; and finally, strong wind cooling or water mist cooling is conducted to obtain the special-shaped foamed aluminum.

[0037] (2) pretreatment of the special-shaped foamed aluminum: the prepared special-shaped foamed aluminum is completely soaked into a soldering flux which is heated to 80-100° C. for 3-10 min, then the soaked special-shaped foamed aluminum is taken out, and dried to form a white frost-shaped coating on the surface; and finally, the special-shaped foamed aluminum is directly heated to 500-600° C., and heat preservation is conducted for standby application.

[0038] (3) pretreatment of molten aluminum alloy, wherein the pretreatment sequentially includes the steps of melting, refining, component adjusting, refining and modifying, and slag and hydrogen measuring; and finally, the molten aluminum alloy is subjected to heat preservation at 660-700° C. for standby application.

[0039] (4) pretreatment of a second mold: a cavity of the second mold is prepared and then put into a heating furnace to be uniformly heated to 350-450° C., and dust on the surface of the cavity is completely removed by spraying through an air gun after the heated cavity is taken out; and finally, a coating is uniformly sprayed on the surface of the cavity, heating is conducted to 350-450° C., and heat preservation is performed for later use.

[0040] (5) casting molding: the prepared special-shaped foamed aluminum is put into the preheated second mold, the mold is closed in place, and the pretreated molten aluminum alloy is poured into the mold for casting.

[0041] (6) post-treatment: the casting is taken out, a sprue and a riser are cut off, and machining, shot blasting treatment and surface treatment are conducted according to product requirements.

Embodiment 1

[0042] An aluminum alloy cavity casting of a certain type of chassis, namely a steering knuckle: the boundary dimension of the casting is 550 mm×160 mm×240 mm, the used alloy is A356, the weight is 4.25 kg, and the basic wall thickness is 6 mm. As shown in FIG. 1, a steering knuckle component of the chassis includes an aluminum alloy cavity casting part (a steering knuckle as shown in a dotted frame in FIG. 1a) and a foamed aluminum part filled in the cavity casting (special-shaped foam aluminum filled in the steering knuckle as shown in FIG. 1b). The appearance size of the filled foamed aluminum is 300 mm×150 mm×150 mm, the filled foamed aluminum is made of pure aluminum, the weight of the filled foamed aluminum is 0.21 kg, and the isovolumetric density of the filled foamed aluminum is 0.2-0.4 g/cm.sup.3. A casting process: low-pressure casting.

[0043] Specific steps are as follows:

[0044] (1) preparation of special-shaped foamed aluminum: firstly, pure aluminum powder and titanium hydride (0.5-1.5 wt % of the total weight) are fully and uniformly mixed, and foamable precursors are prepared by adopting a powder pressing method; then, a first mold used for foaming is preheated to about 700° C. in a heating furnace; then, according to a shape of the special-shaped foamed aluminum, the plurality of the foamable precursors are put into the first mold according to pre-designed positions; and after heat preservation is conducted for 3-5 min, the special-shaped foamed aluminum is taken out and rapidly cooled, wherein a cooling mode is strong wind cooling or water mist cooling.

[0045] (2) pretreatment of the special-shaped foamed aluminum: the prepared special-shaped foamed aluminum is completely soaked into a soldering flux which is heated to 80-100° C. for 5 min, then the soaked special-shaped foamed aluminum is taken out, and dried to form a white frost-shaped coating on the surface; and finally, the special-shaped foamed aluminum is directly heated to 540° C., and heat preservation is conducted for standby application.

[0046] (3) pretreatment of molten aluminum alloy: molten aluminum with qualified chemical components is refined, modified and refined, the molten aluminum alloy is heated to 680° C., and heat preservation is performed for later use.

[0047] (4) pretreatment of a second mold: a cavity of the second mold is prepared and then put into a heating furnace to be uniformly heated to 380° C., and dust on the surface of the cavity is completely removed by spraying through an air gun after the heated cavity is taken out; and finally, a coating is uniformly sprayed on the surface of the cavity, heating is conducted to 380° C., and heat preservation is performed for later use.

[0048] (5) casting molding: the pretreated special-shaped foamed aluminum is put into the preheated second mold, the mold is closed in place, and the pretreated molten aluminum alloy is poured into the mold for casting.

[0049] (6) post-treatment: the casting is taken out, a sprue and a riser are cut off, and machining, shot blasting treatment and surface treatment are conducted according to product requirements.

[0050] In the casting process, the foamed aluminum is special-shaped closed-cell foamed aluminum, a matrix is industrially pure aluminum, the foamed aluminum is formed through direct foaming by a powder method, the thickness of a surface shell is 1.2 mm, and the isovolumetric density is 0.25 g/mm3.

[0051] Further, the soldering flux is a potassium fluorotitanate aqueous solution with a concentration of 12%.

Embodiment 2

[0052] An aluminum alloy cavity casting of a certain type of chassis, namely an auxiliary frame component: the boundary dimension of the casting is 410 mm×260 mm×210 mm, the used alloy is Salifont-36, the weight is 4.5 kg, and the basic wall thickness is 4.5 mm. As shown in FIG. 2, the auxiliary frame component of the chassis includes an aluminum alloy cavity casting part (an auxiliary frame as shown in a dotted frame in FIG. 2a) and a foamed aluminum part filled in the cavity casting (special-shaped foam aluminum filled in the auxiliary frame as shown in FIG. 2b); the appearance size of the filled foamed aluminum is 220 mm×330 mm×130 mm, the filled foamed aluminum is made of pure aluminum, the weight of the filled foamed aluminum is 0.41 kg, and the isovolumetric density of the filled foamed aluminum is 0.2-0.4 g/cm.sup.3. A casting process: low-pressure casting.

[0053] Specific steps are as follows:

[0054] (1) preparation of special-shaped foamed aluminum: firstly, pure aluminum powder and titanium hydride (0.5-1.5 wt % of the total weight) are fully and uniformly mixed, and foamable precursors are prepared by adopting a powder pressing method; then, a first mold used for foaming is preheated to about 700° C. in a heating furnace; then, according to a shape of the special-shaped foamed aluminum, the plurality of the foamable precursors are put into the first mold according to pre-designed positions; and after heat preservation is conducted for 3-5 min, the special-shaped foamed aluminum is taken out and rapidly cooled, wherein a cooling mode is strong wind cooling or water mist cooling.

[0055] (2) pretreatment of the special-shaped foamed aluminum: the prepared special-shaped foamed aluminum is completely soaked into a soldering flux which is heated to 80-100° C. for 8 min, then the soaked special-shaped foamed aluminum is taken out, and dried to form a white frost-shaped coating on the surface; and finally, the special-shaped foamed aluminum is directly heated to 560° C., and heat preservation is conducted for standby application.

[0056] (3) pretreatment of molten aluminum alloy: molten aluminum with qualified chemical components is refined, modified and refined, the molten aluminum alloy is heated to 660° C., and heat preservation is performed for later use.

[0057] (4) pretreatment of a second mold: a cavity of the second mold is prepared and then put into a heating furnace to be uniformly heated to 420° C., and dust on the surface of the cavity is completely removed by spraying through an air gun after the heated cavity is taken out; and finally, a coating is uniformly sprayed on the surface of the cavity, heating is conducted to 420° C., and heat preservation is performed for later use.

[0058] (5) casting molding: the pretreated special-shaped foamed aluminum is put into the preheated second mold, the mold is closed in place, and the pretreated molten aluminum alloy is poured into the mold for casting.

[0059] (6) post-treatment: the casting is taken out, a sprue and a riser are cut off, and machining, shot blasting treatment and surface treatment are conducted according to product requirements.

[0060] In the casting process, the foamed aluminum is special-shaped closed-cell foamed aluminum, a matrix is industrially pure aluminum, the foamed aluminum is formed through direct foaming by a powder method, the thickness of a surface shell is 1.5 mm, and the isovolumetric density is 0.4 g/mm3.

[0061] Further, the soldering flux is a potassium fluorotitanate aqueous solution with a concentration of 10%.

[0062] The above are only the preferred embodiments of the invention, and does not limit the patent range of the invention, and the equivalent structure transformation made by using the contents of the description and the drawing of the invention or the direct/indirect application in other related technical fields under the conception of the invention is included in the patent protection range of the invention.