Jet printing method for improving edge strength of 3D printing sand mold and sand mold

Abstract

The invention relates to the technical field of 3D printing, and discloses a jet printing method for improving the edge strength of a 3D printing sand mold and the sand mold, and the method comprises the following steps: the sand mold is subjected to zoning treatment, and the sand mold is divided into a contact area and a non-contact area according to whether the surface of a mold cavity of the sand mold is in direct contact with high-temperature molten metal or not in the casting process; a first binder spraying parameter is set for the contact area, a second binder spraying parameter is set for the non-contact area, and the spraying amount of the binder in unit area corresponding to the first binder spraying parameter is larger than that of the second binder spraying parameter; and spraying a binder on a contact area of the sand paving layer according to a first binder spraying parameter through binder spraying 3D printing equipment, spraying the binder on a non-contact area of the sand paving layer according to a second binder spraying parameter, overlapping and curing layer by layer, and integrally forming to obtain the sand mold. According to the application, through the setting of partition treatment and differential sticky jetting, the sand mold meets the casting strength requirement, and meanwhile, the air permeability, collapsibility and light weight are taken into account.

Description

A jet printing method for improving the edge strength of 3D printed sand molds and the sand molds themselves. Technical Field

[0001] This application relates to the technical field of 3D printing, and in particular to a jet printing method and sand mold for improving the edge strength of 3D printed sand molds. Background Technology

[0002] In the field of machinery manufacturing, 3D printing technology has developed rapidly in recent years, especially 3D sand mold printing technology, which has been widely used in the casting industry. 3D sand mold printing technology has brought many conveniences to casting production, significantly improved production efficiency, and can quickly manufacture sand molds with complex shapes to meet the casting needs of different products.

[0003] However, existing sand mold 3D printing technology faces challenges when dealing with complex castings, which require high sand mold strength. Common methods include: firstly, increasing the amount of binder to make the sand mold more robust; however, while increasing overall mold strength enhances rigidity, it reduces permeability, severely impacting casting performance; secondly, using sand materials with better strength properties to improve overall mold strength, but these materials are often expensive, and their improvement in permeability and collapsibility is limited, still failing to meet the ideal casting requirements for sand mold performance; thirdly, post-processing of the sand mold, such as high-temperature baking, can further enhance its strength; however, high-temperature baking may cause deformation, affecting mold precision and also reducing permeability and collapsibility to some extent.

[0004] Therefore, the need for a jet printing method that can improve the edge strength of sand molds while ensuring good air permeability and collapsibility has become a technical problem that needs to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a jet printing method and a sand mold for improving the edge strength of 3D printed sand molds.

[0006] A jet printing method for improving the edge strength of 3D printed sand molds includes the following steps: (1) Sand mold functional zoning: The sand mold is divided into contact areas and non-contact areas according to whether its cavity surface is in direct contact with high-temperature molten metal during the casting process; (2) Printing parameter setting: A first adhesive jetting parameter is set for the contact area and a second adhesive jetting parameter is set for the non-contact area, wherein the amount of adhesive jetting per unit area corresponding to the first adhesive jetting parameter is greater than that of the second adhesive jetting parameter; (3) Zonal jetting molding: Based on the parameters set in step (2), adhesive is jetted on the sand layer according to the first adhesive jetting parameter for the contact area and according to the second adhesive jetting parameter for the non-contact area using an adhesive jetting 3D printing device, and the adhesive is jetted layer by layer and cured to obtain a sand mold in one piece.

[0007] By adopting the above technical solution, the sand mold is functionally divided into contact and non-contact areas that directly contact the high-temperature molten metal, allowing for targeted treatment of different regions. Next, different binder spraying parameters are set for the contact and non-contact areas, with a larger binder spraying volume per unit area in the contact area. This ensures that each area can be sprayed with binder according to appropriate parameters during subsequent printing. In the zoned spraying molding stage, binder spraying 3D printing equipment is used to spray binder onto the corresponding areas of the sand layer according to the set parameters, and then the layers are stacked and cured one by one, ultimately forming a single integrated sand mold. This method effectively improves the strength of the sand mold's contact area, meeting the requirements for contact with the high-temperature molten metal during casting, while maintaining appropriate strength in the non-contact area, ensuring good overall permeability and post-cast collapse resistance of the sand mold, thus improving casting performance.

[0008] Further, in step (1), the contact area consists of the cavity interface constituting the casting cavity and the cavity reinforcement area, wherein the cavity reinforcement area is a reinforcement area defined by extending a predetermined distance from the cavity interface to the outside of the sand mold entity.

[0009] By adopting the above technical solution, the specific composition of the contact area is clarified. The contact area is subdivided into the cavity interface that constitutes the casting cavity and the cavity reinforcement area. The cavity reinforcement area extends a certain distance from the cavity interface to the outside of the sand mold to form a reinforcement area. This can more accurately strengthen the parts of the sand mold edge that are easily affected by high-temperature molten metal, improve the strength of the sand mold edge when in contact with high-temperature molten metal, and ensure the stability of the sand mold during the casting process.

[0010] Furthermore, the cavity reinforcement area extends from the working surface of the cavity to the outside of the sand mold body by a predetermined distance of 10mm to 30mm.

[0011] By adopting the above technical solution, extending the cavity reinforcement zone from the working surface of the cavity to the outer side of the sand mold body by 10mm to 30mm allows for precise control of the thickness of the high-strength sand mold structure. Within this reasonable range, the strength of the sand mold edge can be effectively improved, enabling the sand mold to better withstand the impact and pressure of high-temperature molten metal during the casting process. Simultaneously, it ensures that the interior of the sand mold maintains a reasonable low strength, guaranteeing good permeability and post-cast collapseability, thereby improving casting performance.

[0012] Furthermore, the ratio of the amount of adhesive sprayed per unit area in the contact area to that in the non-contact area is (1.1-2):1.

[0013] By adopting the above technical solution, the ratio of the amount of binder sprayed per unit area in the contact area to that in the non-contact area is set within the range of (1.1 - 2):1. This ensures that there is sufficient binder in the contact area to improve its strength, meeting the requirements for direct contact with the high-temperature molten metal during the casting process. This also ensures that the sand mold edge has sufficient load-bearing capacity, preventing damage or deformation under the action of the high-temperature molten metal. Furthermore, it avoids the non-contact area from having poor permeability due to excessive binder, ensuring that the sand mold as a whole has good permeability. This facilitates the discharge of gas during the casting process, reduces the generation of defects such as porosity, and also ensures that the sand mold has good collapsibility after casting, facilitating the cleaning and subsequent processing of the castings, thereby improving the quality of the cast products.

[0014] Furthermore, both the adhesive sprayed in the contact area and the adhesive sprayed in the non-contact area are furan resins.

[0015] By adopting the above technical solution, furan resin has good bonding properties. As a binder sprayed in both contact and non-contact areas, furan resin can firmly bond the sand particles together, ensuring that the sand mold has a certain strength. While meeting the support strength requirements, it reduces material costs and synergistically improves the overall permeability and collapsibility of the sand mold, thereby optimizing economic benefits while improving the quality of castings. In addition, furan resin has a certain thermal stability at high temperatures. When facing high-temperature molten metal during the casting process, it can maintain good performance and is not easy to decompose or fail, which helps to maintain the structural integrity of the sand mold.

[0016] Furthermore, in step (3), grayscale printing process is used to achieve the partitioned spraying molding; the grayscale printing process adjusts the driving piezoelectric nozzle in real time according to the first adhesive spraying parameter and the second adhesive spraying parameter to control the piezoelectric nozzle to perform differentiated spraying, so that the adhesive dosage deposited on the unit printing area of ​​the contact area is continuously higher than the adhesive dosage deposited on the unit printing area of ​​the non-contact area.

[0017] By adopting the above technical solution and employing grayscale printing technology to achieve zoned spray molding, this process can adjust the driving piezoelectric nozzle in real time according to the first and second binder spraying parameters. In actual operation, by precisely controlling the spraying behavior of the piezoelectric nozzle, differentiated spraying is achieved between the contact area and the non-contact area. This differentiated spraying ensures that the binder dosage deposited per unit printing area in the contact area is consistently higher than that in the non-contact area, thereby effectively improving the strength of the contact area while maintaining the overall structural stability of the sand mold. This is particularly important for the edge parts of the sand mold that are in direct contact with the high-temperature molten metal during the casting process, significantly enhancing their resistance to thermal shock and mechanical wear, and improving the quality of castings and production efficiency.

[0018] Furthermore, the grayscale printing process is achieved by adjusting the electronic control signal driving the piezoelectric printhead, including at least one of the following methods: (a) using different voltage pulse amplitudes for the contact area and the non-contact area; (b) using different voltage pulse frequencies for the contact area and the non-contact area; (c) using different scanning path densities for the contact area and the non-contact area.

[0019] By employing the above technical solutions, the grayscale printing process can achieve differentiated spraying between contact and non-contact areas by flexibly adjusting the electronic control signals driving the piezoelectric printhead. Specifically, using different voltage pulse amplitudes, the contact area receives a larger amount of binder sprayed due to the higher amplitude, thus improving the strength of this area; using different voltage pulse frequencies, the high-frequency pulses in the contact area promote denser binder deposition, enhancing its thermal shock resistance; using different scanning path densities, the contact area achieves a more uniform binder distribution by increasing the number of scanning paths, further improving the strength and stability of the mold edge. These methods can be used individually or in combination to ensure a significant difference in binder spraying volume between the contact and non-contact areas, ultimately achieving a balance between improved mold edge strength and optimized overall performance.

[0020] Furthermore, the non-contact area of ​​the sand mold is processed into a honeycomb porous structure through data modeling. The honeycomb porous structure includes honeycomb walls and an internal cavity surrounded by the honeycomb walls.

[0021] By adopting the above technical solution, the non-contact area of ​​the sand mold is processed into a honeycomb porous structure through data modeling. This structure includes honeycomb walls and the internal cavities enclosed by them. This design can ensure that the sand mold has a certain strength as a whole, while significantly improving the permeability and collapseability of the sand mold. The internal cavities provide channels and space for gas flow and collapse. At the same time, it effectively reduces the amount of material used, thereby reducing the overall weight of the sand mold and meeting various requirements of the casting process.

[0022] This application also provides a sand mold using the jet printing method described above, including a contact area and a non-contact area. The contact area corresponds to the surface of the casting cavity and its adjacent solid reinforcement area, and the non-contact area is the main sand mold area outside the contact area. The sand strength in the contact area is higher than that in the non-contact area.

[0023] Furthermore, the non-contact area has a honeycomb porous structure, which includes honeycomb walls and an internal cavity enclosed by the honeycomb walls.

[0024] In summary, this application includes at least the following beneficial technical effects: (1) The sand mold is formed by a specific jet printing method, and the differentiated design of its contact area and non-contact area precisely matches the casting process requirements; the contact area corresponds to the surface of the casting cavity and the adjacent solid reinforcement area, and uses high-strength binder and dense jet parameters to ensure that the structure can still maintain its integrity under the direct impact of high-temperature molten metal, effectively preventing defects such as sand adhesion and deformation; (2) The non-contact area, as the main body of the sand mold, achieves lightweighting through a honeycomb porous structure. The skeleton formed by the honeycomb wall provides basic support strength and forms a gas flow channel through the internal cavity, significantly improving permeability. At the same time, the collapseability is better than that of the traditional solid structure, which facilitates the demolding and cleaning of the casting. This combination of partitioned reinforcement and porous design enables the sand mold to meet the casting strength requirements while taking into account permeability, collapseability and lightweighting, ultimately improving the surface quality and production efficiency of the casting. Detailed Implementation

[0025] The technical solutions in the embodiments of the invention are described in detail below.

[0026] Example 1 Example 1 provides a jet printing method to improve the edge strength of 3D printed sand molds, including the following steps: (1) Sand mold functional zoning: The sand mold is divided into contact areas and non-contact areas according to whether its cavity surface is in direct contact with high-temperature molten metal during the casting process; (2) Printing parameter setting: A first adhesive jetting parameter is set for the contact area and a second adhesive jetting parameter is set for the non-contact area, wherein the amount of adhesive jetting per unit area corresponding to the first adhesive jetting parameter is greater than that of the second adhesive jetting parameter; (3) Zonal jetting molding: Based on the parameters set in step (2), adhesive is jetted on the sand layer according to the first adhesive jetting parameter for the corresponding contact area and according to the second adhesive jetting parameter for the corresponding non-contact area using an adhesive jetting 3D printing device, and the adhesive is jetted on the sand layer according to the second adhesive jetting parameter, layer by layer, solidified, and integrally formed to obtain a sand mold.

[0027] Specifically, in step (1), the contact area consists of the cavity interface that constitutes the casting cavity and the cavity reinforcement area. The cavity reinforcement area is a reinforcement area defined by extending a predetermined distance from the cavity interface to the outside of the sand mold entity. The cavity reinforcement area surrounds the entire casting cavity, and the cavity reinforcement area extends a predetermined distance from the working surface of the cavity to the outside of the sand mold entity by 10mm to 30mm.

[0028] In this embodiment, the cavity reinforcement zone extends 10mm from the working surface of the cavity to the outside of the sand mold body. The presence of the cavity reinforcement zone can further enhance the strength of the sand mold edge and prevent damage to the sand mold edge during the casting process.

[0029] To achieve different strength requirements in different areas, the ratio of adhesive sprayed per unit area in the contact area to that in the non-contact area is (1.1-2):1. In this embodiment, the ratio of adhesive sprayed per unit area in the contact area to that in the non-contact area is 2:1, which ensures that there is enough adhesive in the contact area to improve strength, while avoiding the non-contact area from being affected by excessive adhesive and thus affecting air permeability.

[0030] In this embodiment, both the adhesive sprayed in the contact area and the adhesive sprayed in the non-contact area are furan resin. The good bonding properties of furan resin ensure a strong bond between sand grains, providing basic strength support for the sand mold.

[0031] In order to achieve partitioned spray molding, in step (3), this embodiment adopts grayscale printing process. This process adjusts the driving piezoelectric nozzle in real time according to the first adhesive spraying parameters and the second adhesive spraying parameters to control the piezoelectric nozzle to perform differentiated spraying, so that the adhesive dosage deposited on the unit printing area of ​​the contact area is continuously higher than the adhesive dosage deposited on the unit printing area of ​​the non-contact area.

[0032] As an optional implementation, the grayscale printing process is achieved by adjusting the electronic control signal driving the piezoelectric printhead, including at least one of the following methods: (a) using different voltage pulse amplitudes for contact areas and non-contact areas for printing; (b) using different voltage pulse frequencies for contact areas and non-contact areas for printing; (c) using different scan path densities for contact areas and non-contact areas for printing.

[0033] In practice, different voltage pulse amplitudes are used for spraying in the contact and non-contact areas. A higher voltage pulse amplitude in the contact area results in a greater amount of adhesive deposited per unit printing area, thus improving the strength of that area. Simultaneously, different voltage pulse frequencies can be used; high-frequency pulses in the contact area promote denser adhesive deposition, enhancing its thermal shock resistance. Furthermore, different scanning path densities can be used; increasing the number of scanning paths in the contact area allows for more uniform adhesive distribution, further improving the edge strength and stability of the sand mold. In this embodiment, different voltage pulse amplitudes are used for spraying in the contact and non-contact areas: 80V for the contact area and 50V for the non-contact area.

[0034] In addition, the non-contact area of ​​the sand mold is processed into a honeycomb porous structure through data modeling. This structure includes honeycomb walls and the internal cavity enclosed by them, which not only ensures that the sand mold has a certain strength, but also significantly improves permeability and collapsibility, reduces material usage, reduces the overall weight of the sand mold, and meets various requirements of the casting process.

[0035] Example 2 provides a sand mold prepared using the jet printing method for improving the edge strength of 3D printed sand molds described in Example 1. The sand mold includes a contact area and a non-contact area. The contact area is in contact with the high-temperature molten metal during casting and corresponds to the solid reinforcement area of ​​the casting cavity surface and its adjacent parts. The non-contact area is not in contact with the high-temperature molten metal during casting and corresponds to the main body area of ​​the sand mold other than the contact area. Because the amount of binder sprayed in the contact area is greater than that in the non-contact area, the sand strength in the contact area is higher than that in the non-contact area. This ensures both the strength of the contact area and the permeability of the non-contact area.

[0036] Specifically, the contact area consists of the cavity interface that constitutes the casting cavity and the cavity reinforcement area. The cavity reinforcement area extends a predetermined distance from the cavity interface to the outside of the sand mold entity. In this embodiment, the extension distance is set to 20mm. This distance can effectively enhance the edge strength of the sand mold and prevent edge damage during casting.

[0037] Furthermore, the adhesive sprayed in the contact area is ethyl silicate, which has good high-temperature resistance and can effectively resist the thermal shock and chemical corrosion of high-temperature molten metal, reduce the risk of sand sticking to the casting, and ensure the integrity and smoothness of the cavity surface; furan resin is sprayed in the non-contact area, which has a lower cost, reduces material costs while meeting the support strength requirements, and can also improve the overall air permeability and collapsibility of the sand mold.

[0038] Meanwhile, the non-contact area of ​​the sand mold is processed into a honeycomb porous structure through data modeling. This structure includes honeycomb walls and the internal cavity enclosed by them. This design not only ensures that the sand mold has a certain strength, but also significantly improves the permeability and collapse of the sand mold. The internal cavity provides channels and space for gas flow and collapse, and also reduces the amount of material used and the overall weight of the sand mold, thus meeting a variety of requirements of the casting process.

[0039] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A jet printing method for improving the edge strength of 3D printed sand molds, characterized in that, Includes the following steps: (1) Functional zoning of sand mold: The sand mold is divided into contact area and non-contact area according to whether its cavity surface is in direct contact with the high temperature molten metal during the casting process. (2) Printing parameter setting: Set a first adhesive spraying parameter for the contact area and a second adhesive spraying parameter for the non-contact area, wherein the amount of adhesive sprayed per unit area corresponding to the first adhesive spraying parameter is greater than that of the second adhesive spraying parameter; (3) Partition spraying molding: Based on the parameters set in step (2), the adhesive is sprayed on the sand layer according to the first adhesive spraying parameters on the contact area and according to the second adhesive spraying parameters on the non-contact area using the adhesive spraying 3D printing equipment. The layers are stacked and cured one by one to obtain a sand mold.

2. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: In step (1), the contact area consists of the cavity interface that constitutes the casting cavity and the cavity reinforcement area. The cavity reinforcement area is a reinforcement area defined by extending a predetermined distance from the cavity interface to the outside of the sand mold entity.

3. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: The cavity reinforcement zone extends from the working surface of the cavity to the outside of the sand mold body by a predetermined distance of 10mm to 30mm.

4. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: The ratio of the amount of adhesive sprayed per unit area in the contact area to that in the non-contact area is (1.1-2):

1.

5. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: Both the adhesive sprayed in the contact area and the adhesive sprayed in the non-contact area are furan resins.

6. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: In step (3), grayscale printing process is used to achieve the partitioned spray molding; The grayscale printing process adjusts the drive piezoelectric nozzle in real time based on the first and second adhesive spraying parameters to control the piezoelectric nozzle to perform differentiated spraying, so that the adhesive dosage deposited per unit printing area in the contact area is consistently higher than the adhesive dosage deposited per unit printing area in the non-contact area.

7. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: The grayscale printing process is achieved by adjusting the electronic control signal driving the piezoelectric printhead, including at least one of the following methods: (a) using different voltage pulse amplitudes for the contact area and the non-contact area; (b) using different voltage pulse frequencies for the contact area and the non-contact area; (c) using different scanning path densities for the contact area and the non-contact area.

8. The jet printing method for improving the edge strength of 3D printed sand molds according to claim 1, characterized in that: The non-contact area of ​​the sand mold is processed into a honeycomb porous structure through data modeling. The honeycomb porous structure includes honeycomb walls and an internal cavity surrounded by the honeycomb walls.

9. A sand mold, using the jet printing method according to any one of claims 1 to 8, characterized in that: It includes a contact area and a non-contact area. The contact area corresponds to the surface of the casting cavity and the solid reinforcement area of ​​its adjacent part. The non-contact area is the main sand mold area outside the contact area. The sand strength of the contact area is higher than that of the non-contact area.

10. A sand mold according to claim 9, characterized in that: The non-contact area has a honeycomb porous structure, which includes honeycomb walls and an internal cavity enclosed by the honeycomb walls.