Process for producing mold casting through composite modeling of 3D printing and lost foam casting
By using a composite molding process combining 3D printed sand molds and lost foam casting, and employing sealing adhesives and vacuum fixing of the sand molds, the problems of delivery cycle and surface quality in traditional casting processes have been solved. The mold closing and locking process has been simplified, and the production efficiency and quality of castings have been improved.
Patent Information
- Application Number
- CN202511482561.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-16
- Publication Date
- 2026-02-13
AI Technical Summary
Existing stamping die casting processes are difficult to meet delivery cycle requirements, and have defects such as foam vaporization and surface quality issues. The mold clamping operation of 3D printed sand molds is cumbersome and easily damages the sand molds.
The upper and lower sand molds are 3D printed, bonded together with sealing adhesive, and fixed by vacuuming in the lost foam sand box, simplifying the mold assembly and locking process. The sand mold is fixed by the negative pressure of dry sand, avoiding mechanical operation.
It improves the production efficiency and dimensional accuracy of castings, reduces the risk of sand mold damage, saves labor and time costs, and improves the surface quality of castings.
Smart Images
Figure CN121514432A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of real shape casting technology, and particularly relates to a process for producing mold castings by combining 3D printing and lost foam casting. BACKGROUND
[0002] With the shortening of the development cycle of new vehicles by automobile manufacturers, the delivery cycle of stamping mold castings is also required to be greatly shortened. At present, the casting process of stamping molds mainly includes real shape casting and lost foam casting, and the production process is as follows: a foam model is made according to product drawings, a mold is designed, a pouring system is designed, the model is sprayed with paint and dried, sand is buried for molding, smelting and pouring are performed, the mold is cooled, the sand is removed, the castings are taken out, the castings are post-processed, and machining is performed. It is difficult to meet the delivery requirements of customers by using the real shape casting and lost foam casting processes. Moreover, because of the participation of the foam mold, black slag defects caused by foam gasification and surface quality problems caused by foam are inevitable in the process. After machining, there are problems of different degrees and areas of welding. 3D printing sand casting realizes mold-free production by "layer-by-layer accumulation of sand molds", breaks through the structure limit and shortens the production cycle. 3D printing sand mold only needs "digital modeling, slicing, printing, sand mold spraying paint, molding, locking, smelting and pouring, mold cooling, sand removal, taking out castings, casting post-processing and machining. At the same time, the 3D printed sand mold is a cavity, which avoids the defects caused by the use of foam mold in real shape casting. For general small and medium-sized parts, the 3D printed sand mold is directly molded and locked for pouring. In order to avoid sand cracking during pouring, the sand iron generally reaches 80-100mm, and the sand iron is relatively large. Moreover, in the actual production process, it is relatively cumbersome to reliably fix the molded mold after 3D printing: 1) mechanical clamping: commonly used clamps such as "arch clamps", "screw pressure plates" and "quick locks" are evenly distributed along the parting surface of the sand mold (the interval is generally 300-500mm, and the large sand mold needs to be densified), and the clamping force needs to be moderate (excessive clamping force may crack the sand mold, and insufficient clamping force may cause liquid leakage); 2) heavy weight pressing: for small sand molds, weight blocks (such as cast iron blocks) can be evenly placed on the top of the molded mold to press the parting surface by using gravity; 3) bolt fixing: bolt holes are pre-set during printing, and the bolt holes of the upper and lower molds are penetrated by bolts and nuts after molding to achieve high-strength fixing. The operation process is also easy to damage the sand mold and affect the surface quality of the castings. Therefore, it is very important to solve the above problems. SUMMARY
[0003] In view of the above, the present application aims to provide a process for producing mold castings by combining 3D printing and lost foam casting, which solves the problems in the background art.
[0004] In order to achieve the above purpose, the present application provides a process for producing mold castings by combining 3D printing and lost foam casting, which includes the following steps: Step one, according to the shape of the mold using 3D printer to print sand mold, sand mold is divided into two parts of the upper and lower mold; Step two, the upper and lower mold cavity of the sand mold is coated with paint and dried; Step three, the edge of the upper and lower mold cavity of the sand mold is bonded together to combine the two; Step four, molding in the sand box, placing a 100mm thick dry sand layer in the sand box, vibrating and scraping, moving the combined 3D printed sand mold to the sand layer with the tool, the edge of the sand mold is not less than 50mm from the inner wall of the sand box, inserting the sprue into the reserved sprue socket on the surface of the upper mold, pouring sand, vibrating every 200mm of sand thickness, vibrating the sand layer, scraping the sand layer when the top of the sprue is buried, inserting the sprue cup into the sprue, laying a layer of plastic cloth on the plastic cloth, and pouring the molten metal at 1350℃ into the sand mold cavity through the sprue to obtain the casting; Step five, before pouring, inserting the negative pressure pipeline into the negative pressure nozzle of the sand box and using the vacuum pump to extract the vacuum, then pouring the molten metal into the sand mold cavity through the sprue to obtain the casting; Step six, after pouring, releasing the negative pressure of the sand box and taking out the sand mold, removing the sand mold and dry sand by vibration and cleaning to obtain the finished casting.
[0005] Preferably, the step two uses zirconium powder alcohol-based paint to brush the paint in the mold cavity, and burns dry.
[0006] Preferably, the zirconium powder alcohol-based paint has a Baumé degree of 55.
[0007] Preferably, the step three combines the upper and lower mold parts together by sealing the box with adhesive, and the combined sand mold cavity matches the shape of the mold, and the upper mold exhaust hole is sealed with adhesive tape to prevent dry sand from entering the cavity during sand embedding.
[0008] Preferably, the step four sand box has a dry sand particle size of AFS30.
[0009] Preferably, the step five uses a vacuum pump to extract the vacuum of the sand box, and the vacuum degree is maintained at 0.03-0.05MPa.
[0010] Preferably, the step five uses a ladle or a teapot type ladle to pour the molten metal into the sand mold cavity through the sprue to obtain the casting.
[0011] Preferably, the step six removes the sand mold and dry sand, and then performs annealing, shot blasting and polishing on the casting to finally obtain the finished casting.
[0012] The beneficial effects of the present application: firstly, the 3D printer is used to print the upper mold and the lower mold of the sand mold, then the surface of the upper mold and the lower mold is sprayed with paint and dried, then the upper mold and the lower mold are bonded together to form a cavity matching mold casting shape, then the molding is carried out, after molding, vacuum casting is carried out, and finally the sand mold and dry sand are removed after cooling and removing the negative pressure, and after annealing, shot blasting, polishing, the casting is obtained. Compared with the traditional sand mold locking mode, the upper mold and the lower mold are bonded by sealing box adhesive and then fixed by dry sand negative pressure, without complex bolt fastening, clamp clamping and other operations, greatly simplifying the operation process of molding and sand mold locking, saving labor and time cost. Dry sand tightly wraps the sand mold under the action of negative pressure, which can provide support and fixation to the sand mold in all directions, compared with the traditional single-point or multi-point fixation mode, the stability of the sand mold during pouring can be better guaranteed, the displacement and deformation of the sand mold are reduced, and the size accuracy and quality of the casting are improved. The traditional locking mode may cause damage to the sand mold due to improper force during operation, and the method of the present application avoids direct mechanical operation on the sand mold, reduces the risk of sand mold damage, and improves the utilization rate of the sand mold. BRIEF DESCRIPTION OF DRAWINGS
[0013] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only illustrate the present application, and other drawings can be obtained by those skilled in the art without any creative effort.
[0014] Fig. 1 is a schematic diagram of the upper mold and the lower mold of the present application; Fig. 2 is a schematic diagram of the upper mold of the present application; Fig. 3 is a schematic diagram of the lower mold of the present application; Fig. 4 is a schematic diagram of the upper mold and the lower mold of the present application placed in the sand box.
[0015] In the figure, the following are marked: 1-sand box, 2-upper mold, 3-lower mold, 4-straight gate, 5-gate cup, 6-negative pressure nozzle, 7-straight gate socket. DETAILED DESCRIPTION
[0016] In order to make the purpose, technical solutions and advantages of the present application more clear, the following will further illustrate the present application in combination with specific embodiments.
[0017] It should be noted that the technical terms or scientific terms used in the present application should be understood as the general meaning understood by those skilled in the art to which the present application belongs, unless otherwise defined. The "first", "second" and similar words used in the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Include" or "contain" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connected" or "connected" and similar words are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to represent the relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0018] As Figs. 1 to 4 shown, the present embodiment provides a process for producing a mold casting by combining 3D printing and lost foam casting, comprising the following steps: S1, printing a sand mold according to the shape of the mold using a 3D printer, the sand mold being divided into an upper mold 2 and a lower mold 3; S2, using zirconium powder alcohol-based paint to brush the paint in the cavity of the upper mold 3 and the lower mold 4 of the sand mold after printing is completed, the zirconium powder alcohol-based paint having a Baumé degree of 55 and being ignited to dry; S3, combining the cavity edges of the upper mold 3 and the lower mold 4 of the sand mold together through box sealing adhesive, the combined sand mold cavity fitting the shape of the mold, the upper mold exhaust hole being sealed with adhesive tape to avoid dry sand entering the cavity during sand embedding; attention should be paid to avoid sand mold chipping, cracking, sand block dropping and other causes of casting defects during molding; S4, molding in the sand box 1, placing a dry sand layer with a thickness of 100 mm in the sand box 1, the dry sand having a particle size of AFS30, vibrating and scraping flat, moving the molded 3D printing sand mold to the sand layer with a tool, the sand mold edge being not less than 50 mm away from the inner wall of the sand box 1, inserting the sprue 4 into the sprue insertion port 7 reserved on the surface of the upper mold 2, embedding sand, vibrating once every 200 mm of sand embedding thickness, vibrating the sand layer, embedding to the top end of the sprue 4, scraping the sand layer flat, laying a layer of plastic cloth, inserting the sprue cup 5 on the sprue 4, laying a layer of 100 mm thick loose sand on the plastic cloth, and ending the molding; since the sand mold is poured in the lost foam sand box, the sand consumption of the thinnest part of the sand mold is 30-40 mm, which is more than half of the sand consumption when the sand mold is poured bare; S5, before pouring, insert the negative pressure pipeline into the negative pressure nozzle 6 of the sand box 1, use the vacuum pump to extract vacuum and keep the vacuum degree at 0.045 MPa, the 3D printing sand mold is no longer gasified foam, the pouring temperature can be 30-50℃ lower than that of the lost foam, so the smelting metal liquid is 1350℃, the energy efficiency is reduced, the teapot type ladle is used to pour into the sand mold cavity through the gate to pour the casting, and the oxidation slag of molten iron into the cavity is reduced; S6, after pouring is completed, release the negative pressure of the sand box 1 after cooling to normal temperature, take out the sand mold, remove the sand mold and dry sand through vibration and cleaning, and finally get the finished casting after annealing treatment, shot blasting and polishing of the casting.
[0019] By reducing the sand consumption of the sand mold, shortening the production cycle of the 3D printed sand mold, reducing the amount of printing sand and resin curing agent, and reducing the production cost, the 3D printed sand mold is buried in the lost foam sand box after molding, vacuum extraction and locking to avoid the complicated molding and locking process of the 3D printed sand mold. The combination of the two can greatly improve the production efficiency of the casting. Compared with the traditional sand mold locking method, the upper mold and the lower mold are bonded by sealing box adhesive and then fixed by dry sand negative pressure, without complex bolt fastening, clamp clamping and other operations, greatly simplifying the operation process of molding and sand mold locking, saving labor and time cost. Dry sand tightly wraps the sand mold under the action of negative pressure, which can provide support and fixation to the sand mold in all directions. Compared with the traditional single-point or multi-point fixation method, it can better ensure the stability of the sand mold during pouring, reduce the displacement and deformation of the sand mold, and improve the dimensional accuracy and quality of the casting. The traditional locking method may cause damage to the sand mold due to improper force during operation, while the method of the application avoids direct mechanical operation on the sand mold, reduces the risk of sand mold damage, and improves the utilization rate of the sand mold.
[0020] Those skilled in the art will understand that the above discussion of any embodiment is only exemplary and is not intended to limit the scope of the application to these examples; under the idea of the application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the application as described above. In order to be brief, they are not provided in detail. Any omissions, modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.
Claims
1. A process for producing a mold casting of a mold by 3D printing and lost foam casting, characterized in that, It comprises the following steps: Step one, according to the shape of the mold, the sand mold is printed by a 3D printer, and the sand mold is divided into two parts of the upper mold and the lower mold; Step two, the cavities of the upper mold and the lower mold of the printed sand mold are coated with paint and dried; Step three, the edges of the cavities of the upper mold and the lower mold of the sand mold are bonded together to combine the two molds; Step four, molding in the sand box, placing a 100mm thick dry sand layer in the sand box, vibrating and scraping, moving the combined 3D printed sand mold to the sand layer with a tool, the edge of the sand mold is not less than 50mm from the inner wall of the sand box, inserting the sprue into the reserved sprue socket on the surface of the upper mold, pouring sand, vibrating every 200mm of sand thickness, vibrating the sand layer, scraping the sand layer when the top of the sprue is buried, laying a layer of plastic cloth, inserting the sprue cup on the sprue, and laying a layer of 50-100mm thick sand on the plastic cloth, molding is completed; Step five, before pouring, insert the negative pressure pipeline into the negative pressure nozzle of the sand box and use the vacuum pump to create a vacuum, then pour the molten metal liquid at 1350℃ into the sand mold cavity through the sprue to obtain the casting; Step six, after pouring, release the negative pressure of the sand box and take out the sand mold, remove the sand mold and dry sand by vibration and cleaning to obtain the finished casting.
2. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 1, characterized in that, In step two, the zirconium powder alcohol-based paint is used to brush the paint in the cavity of the upper mold and the lower mold, and the paint is dried by burning.
3. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 2, characterized in that, The zirconium powder alcohol-based paint has a Baumé degree of 55.
4. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 1, characterized in that, In step three, the upper mold and the lower mold are combined together by sealing adhesive, and the exhaust hole of the upper mold is sealed with adhesive tape to prevent dry sand from entering the cavity during sand embedding.
5. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 1, characterized in that, In step four, the dry sand particle size of the sand box is AFS30.
6. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 1, characterized in that, In step five, the vacuum pump is used to create a vacuum in the sand box, and the vacuum degree is maintained at 0.03-0.05MPa.
7. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 6, characterized in that, In step five, the molten metal liquid is poured into the sand mold cavity through the sprue by using a ladle or a teapot type ladle to obtain the casting.
8. The process for producing a mold casting of 3D printing and lost foam composite molding according to claim 1, characterized in that, After removing the sand mold and dry sand in step six, the casting is subjected to annealing, shot blasting and polishing to obtain the finished casting.