A matrix cascade refrigeration device for additive manufacturing of frozen sand molds and a method thereof

Abstract

The application provides a frozen sand mold additive manufacturing matrix staged refrigeration device, which comprises a support plate, a lifting guide column, an electric cylinder, an integrated gradient refrigeration device, a sand laying device, a roller, a printing nozzle, a rack, a vacuum pump, a guide rail, a forming platform and a motor. The device and method use water as a binder, set a wide-area regional refrigeration strategy before printing through a visual and arrayed temperature adjustment interface, accurately and gradiently refrigerate the water-based binder spraying area by the cooling device integrated in the upper computer control system, accurately control and adjust the position of each area during the sand mold freezing printing process, improve the sand mold forming precision and mechanical properties, and simultaneously realize that different sand mold areas have differentiated thermal physical parameters to actively regulate and control the accurate solidification process of the casting. Through the integrated design of roller compaction and negative pressure adsorption, the surface flatness and internal tightness during sand laying can be increased, the casting strength can be improved, and high-quality manufacturing can be realized.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a graded cooling device and method for a frozen sand mold additive manufacturing matrix. Background Technology

[0002] The traditional foundry industry is resource-intensive and faces challenges such as long manufacturing cycles, numerous production processes, high labor intensity, expensive finished products, and harsh working environments. The traditional foundry industry urgently needs breakthroughs and transformations in green processes to promote energy conservation, emission reduction, and green sustainable development in manufacturing. Adopting environmentally friendly cryogenic sand casting processes and equipment can significantly reduce material and energy consumption during the casting process, reduce pollutant emissions, improve casting yield, and achieve efficient, high-quality, and precise forming of castings.

[0003] 3DP (3D Printing Process) is a type of 3D printing process that uses various powder materials and binders (such as water or resin) to "print" the cross-section of a part onto a single layer of powder material through a nozzle. These layers are then stacked to create a model of the target part. The specific process is as follows: a layer of binder is sprayed from the print head under the control of a host computer. After one layer is printed, the forming platform descends by the thickness of one layer, and then powder is spread and compacted using a powder feeding roller to form a new single layer of powder. The next layer is then printed, and so on, layer by layer, to obtain the desired mold. Areas not sprayed with binder during printing are covered with dry powder, which provides support and is relatively easy to remove after printing. Parts bonded only with binder have relatively low strength, so post-processing is required to enhance their mechanical properties.

[0004] Traditional printing methods employ multi-material (ordinary silica sand, chromite sand, and zircon sand, etc.) sand-laying printing manufacturing with different thermophysical parameters to lay sand in sections and control it in an integrated manner for complex castings with large differences in wall thickness. This molding method is limited by the level of automation and the mutual mixing and contamination of sand materials, making it difficult to achieve precise control of multi-region sand laying for complex shapes. The matrix-level cooling method and device for cryogenic sand mold additive manufacturing proposed in this invention uses a single silica sand raw material with lower cost. Different matrix cooling devices impart different thermophysical parameters to different areas of the sand mold, replacing the traditional method of controlling each area with multiple materials. At the same time, the integrated design of roller compaction and negative pressure adsorption device increases the density of the sand layer and the penetration of the cold source medium. In addition, the convection and conduction of cold air in the upper layer caused by the negative pressure at the bottom increases the freezing efficiency of the mold and improves the mold performance. The control method is simpler and more effective, the control process is more environmentally friendly, the level of automation is more intelligent, the level of digital integration is higher, and the prospects for engineering applications are stronger. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a graded cooling device and method for a matrix of cryogenic sand-based additive manufacturing, which addresses the shortcomings of the prior art. This device can achieve interlayer regional cooling of the printed layer, precisely cooling the area where water-based adhesive has been sprayed, and flexibly adjusting the temperature of the relevant cooling modules in the unprinted area. In the sand layer, the density of the sand layer is increased by the integrated operation of roller compaction and negative pressure extraction at the bottom of the forming platform. At the same time, the negative pressure causes the cold air above the molding sand to convect heat downwards, increasing the cooling efficiency.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a matrix-graded refrigeration device for cryogenic sand molding additive manufacturing, characterized in that it includes a frame, a support plate, a matrix-integrated refrigeration device, a sand-laying device, a forming platform, and a printing nozzle. The support plate is fixedly installed on one side of the frame, and a lifting guide column and an electric cylinder are installed on the support plate. The matrix-integrated refrigeration device is fixedly installed at the lifting end of the electric cylinder, and the lifting of the matrix-integrated refrigeration device is achieved by pushing and pulling the electric cylinder. A guide rail is provided on the frame, and the sand-laying device is installed on the guide rail. Rollers and a printing nozzle are respectively connected to both ends of the sand-laying device for compacting the sand layer and spraying water-based adhesive. A forming platform is installed on the guide rail, and the forming platform is driven by a motor to move on the guide rail. Multiple vacuum pumps are evenly distributed around the perimeter of the frame. The vacuum pumps are sealed to the forming platform through conduits. By adjusting the parameters of the vacuum pumps, different negative pressure adsorption can be applied to different printing areas to achieve compaction of the sand layer and improve the transmission efficiency of the cold air above in the molding sand particles.

[0007] Preferably, the matrix integrated refrigeration device consists of a pressure plate and a matrix of semiconductor refrigeration chips. The semiconductor refrigeration chips are fixedly mounted on the pressure plate, which is connected to a lifting guide column and an electric cylinder. The movement of the matrix integrated refrigeration device is achieved by the telescopic movement of the electric cylinder.

[0008] Preferably, the molding platform includes a sand-supporting plate, a frame, and a bottom box. The frame is fixedly installed on the periphery of the sand-supporting plate, and the bottom box is fixedly connected to the bottom of the sand-supporting plate. The sand-supporting plate of the molding platform has multiple micro-holes arranged in a matrix. The periphery of the bottom box is sealed to a vacuum pump through a conduit. The sand-supporting plate has multiple micro-holes arranged in a matrix, and the micro-holes transmit vacuum negative pressure to adsorb molding sand. A dense mesh is provided on the sand-supporting plate. The molding platform is mounted on a frame through a lifting screw. The dense mesh on the sand-supporting plate of the molding platform is used to prevent the laid molding sand from leaking through the micro-holes at the bottom.

[0009] Preferably, the printing nozzle is connected to the right side of the sand-laying device via a lead screw to enable back-and-forth movement. A roller is installed on the left side of the sand-laying device, which moves and rolls to achieve a smooth and compact sand layer surface. Simultaneously, by working in conjunction with the negative pressure adsorption device on the forming platform, the density of the sand layer is further increased.

[0010] A method for staged cooling of a cryogenic sand mold additive manufacturing matrix includes the following steps:

[0011] S1. Select appropriate molding sand according to the type of casting, perform equal-thickness layered slicing on the geometric model of the mold, and determine the two-dimensional slicing information of each layer.

[0012] S2. Place the molding sand into the sand spreading device. At this time, the sand spreading device is on the left side of the guide rail. First, lay the bottom sand in the molding platform. Then, according to the calculated sand spreading thickness, move the sand spreading device to the right to lay a single layer of sand. At the same time as spreading the sand, turn on the vacuum pump. The sand layer is flattened by negative pressure adsorption and roller rolling, and the density of the molding sand and the flatness of the sand layer are increased to form the first sand layer.

[0013] S3. When the sand-laying device moves to the right end point along the guide rail, the sand-laying operation of a single layer of sand is completed. The sand-laying device moves to the left along the guide rail. At this time, the printing nozzle sprays water-based adhesive according to the two-dimensional slice information of this layer to perform the printing operation.

[0014] S4. After the printing nozzle sprays a layer of molding sand, the matrix integrated cooling device is lowered above the first sand layer by the electric cylinder and maintains a certain distance. The input end opens the cooling plate at the corresponding position of the matrix integrated cooling device according to the position of the printed pattern on the first sand layer and sets the cooling temperature to realize the rapid regional freezing and molding of the printed pattern.

[0015] S5. The sand-bearing plate of the forming platform descends one layer thickness by rotating the lead screw below the forming platform. Repeat S2-S4 to continue printing multiple layers until the printing operation of the preset mold is completed.

[0016] S6. Remove the frozen sand mold and transport it to the sand mold gradient cooling storage chamber for low-temperature conditioning, and clean the workbench.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This invention achieves regionalized, high-precision cooling of the printing layer by adding a matrix integrated cooling device, thereby reducing energy consumption and realizing a green and environmentally friendly casting process.

[0019] 2. The highly controllable cooling method of this invention can reduce the flow time of water when printing as a binder, thereby achieving better control over the accuracy and performance of cryogenic printing.

[0020] 3. The present invention increases the density of the sand layer and improves the casting performance by integrating roller compaction and negative pressure adsorption device. At the same time, the cold air convection caused by the negative pressure at the bottom increases the freezing efficiency of the casting mold.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 This is a schematic diagram of the molding platform in this invention.

[0024] Figure 3 This is a schematic diagram of the roller structure in this invention.

[0025] Figure 4 This is a schematic diagram of the matrix semiconductor refrigeration chip arrangement structure of the integrated refrigeration device in this invention.

[0026] Figure 5 This is a schematic diagram of the connection of the refrigeration device of the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] Detailed Implementation

[0029] Example 1

[0030] like Figure 1 and Figure 2 As shown, this embodiment provides a matrix-level refrigeration device for cryogenic sand-mold additive manufacturing, including a frame 8, a support plate 1, a matrix-integrated refrigeration device 4, a sand-laying device 5, a forming platform 11, and a printing nozzle 7. The support plate 1 is fixedly installed on one side of the frame 8. A lifting guide column 2 and an electric cylinder 3 are mounted on the support plate 1. The matrix-integrated refrigeration device 4 is fixedly installed on the lifting end of the electric cylinder 3, and the lifting of the matrix-integrated refrigeration device is achieved by pushing and pulling the electric cylinder 3. A guide rail 10 is provided on the frame 8, and the sand-laying device is installed on the guide rail 10. 5. The two ends of the sand-laying device 5 are respectively connected to rollers 6 and printing nozzles 7 for compacting the sand layer and spraying water-based adhesive. A forming platform 11 is installed on the guide rail 10. The forming platform 11 is driven by a motor 12 to move on the guide rail 10. Multiple vacuum pumps 9 are evenly distributed around the frame 8. The vacuum pumps 9 are sealed to the forming platform 11 through conduits. By adjusting the parameters of the vacuum pumps 9, different negative pressure adsorption can be applied to different printing areas to achieve compaction of the sand layer and improve the transmission efficiency of the cold air above in the molding sand particles.

[0031] In this embodiment, the matrix integrated refrigeration device 4 consists of a pressure plate and a matrix of semiconductor refrigeration chips 14. The semiconductor refrigeration chips 14 are fixedly mounted on the pressure plate. The pressure plate is connected to the lifting guide column 2 and the electric cylinder 3. The movement of the matrix integrated refrigeration device 4 is realized by the telescopic movement of the electric cylinder 3. The lifting guide column is slidably connected to the support plate 1 for guiding and limiting.

[0032] In this embodiment, the molding platform 11 includes a sand-bearing plate, a frame, and a bottom box. The frame is fixedly installed on the periphery of the sand-bearing plate, and the bottom of the sand-bearing plate is fixedly connected to the bottom box. The sand-bearing plate of the molding platform 11 has a plurality of micro-holes 13 arranged in a matrix. The periphery of the bottom box is sealed to a vacuum pump through a conduit. The sand-bearing plate has a plurality of micro-holes 13 arranged in a matrix. A dense mesh is provided on the sand-bearing plate. The molding platform 11 is mounted on the frame 8 by a lifting screw. The lifting screw is connected to a lifting motor, which drives the rotation to control the lifting of the molding platform 11.

[0033] In this embodiment, the print head 7 is connected to the right side of the sand-spreading device 5 via a lead screw to achieve back-and-forth movement. The roller 6 is fixedly installed on the left side of the sand-spreading device, and is driven to rotate by a motor. The sand-spreading device 5 moves the roller 6 and the print head 7 left and right via the guide rails 10 on both sides of the frame 8 to achieve sand spreading, compaction, and printing.

[0034] Example 2

[0035] A method for staged cooling of a cryogenic sand mold additive manufacturing matrix includes the following steps:

[0036] S1. Select appropriate molding sand according to the type of casting, perform equal-thickness layered slicing on the geometric model of the mold, and determine the two-dimensional slicing information of each layer.

[0037] S2. Place the molding sand into the sand spreading device 5. At this time, the sand spreading device 5 is on the left side of the guide rail 10. First, lay 5cm of bottom sand in the molding platform 11. Then, according to the calculated sand spreading thickness, move the sand spreading device 5 to the right to lay a single layer of sand with a sand spreading thickness of 0.3 to 0.6mm. At the same time as spreading the sand, turn on the vacuum pump 9 and adjust the adsorption flow rate to 10L / min to 40L / min. The sand layer is flattened by negative pressure adsorption and roller rolling, and the density of the molding sand and the flatness of the sand layer are increased to form the first sand layer.

[0038] S3. When the sand spreading device moves to the right end point along the guide rail 10, the printing nozzle 7 sprays water-based adhesive according to the two-dimensional slice information to print the layer pattern.

[0039] S4. After the printing nozzle 7 has sprayed a layer of molding sand, the matrix integrated cooling device 4 descends above the first sand layer and maintains a certain distance. According to the required cooling temperature of the first sand layer, the cooling plate at the corresponding position of the matrix integrated cooling device 4 is turned on and the cooling temperature is set. The cooling temperature is set to -5℃ to -40℃ to quickly freeze and form the printed pattern. It stays for 5 to 15 seconds, and then the matrix integrated cooling device rises back to the initial position.

[0040] S5. The forming platform 11 descends by one layer thickness, and S2-S4 are repeated to continue printing multiple layers until the printing operation of the preset mold is completed.

[0041] S6. Remove the frozen sand mold and transport it to the sand mold gradient cooling storage chamber for low-temperature conditioning, and clean the workbench.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A staged refrigeration device for cryogenic sand mold additive manufacturing matrix, characterized in that, The system includes a frame (8), a support plate (1), a matrix integrated cooling device (4), a sand-laying device (5), a molding platform (11), and a printing nozzle (7). The support plate (1) is fixedly installed on one side of the frame (8). A lifting guide column (2) and an electric cylinder (3) are installed on the support plate (1). The matrix integrated cooling device (4) is fixedly installed on the lifting end of the electric cylinder (3). The matrix integrated cooling device (4) consists of a pressure plate and a matrix of semiconductor cooling chips (14). A guide rail (10) is provided on the frame (8), and a sand-laying device (5) is installed on the guide rail (10). The two ends of the sand-laying device (5) are respectively connected to rollers (6) and printing nozzles (7) for compacting the sand layer and spraying water-based adhesive. A forming platform (11) is installed on the guide rail (10). The forming platform (11) is driven by a motor (12) to move on the guide rail (10). Multiple vacuum pumps (9) are evenly distributed around the frame (8). The vacuum pumps (9) are sealed to the forming platform (11) through conduits. The sand-laying device (5) lays a single layer of sand to form a sand layer. The printing nozzle (7) sprays water-based adhesive according to the two-dimensional slice information of each layer of the casting geometric model to carry out the printing operation. After the printing nozzle (7) has sprayed a layer of molding sand, the matrix integrated cooling device (4) is controlled by the electric cylinder (3) to descend above the sand layer and maintain a certain distance. According to the location of the printed pattern on the sand layer, the cooling plate of the matrix integrated cooling device (4) at the corresponding position is opened and the cooling temperature is set to realize the rapid regional freezing and molding of the printed pattern.

2. The staged refrigeration device for cryogenic sand mold additive manufacturing matrix according to claim 1, characterized in that, The semiconductor cooling chip (14) is fixedly installed on the pressure plate. The pressure plate is connected to the lifting guide column (2) and the electric cylinder (3). The movement of the matrix integrated cooling device (4) is realized by the telescopic movement of the electric cylinder (3).

3. The staged refrigeration device for cryogenic sand mold additive manufacturing matrix according to claim 1, characterized in that, The molding platform (11) includes a sand-bearing plate, a frame and a bottom box. The frame is fixedly installed on the periphery of the sand-bearing plate, and the bottom of the sand-bearing plate is fixedly connected to the bottom box. The sand-bearing plate of the molding platform (11) has multiple micro-holes (13) arranged in a matrix. The periphery of the bottom box is sealed to a vacuum pump through a conduit. The sand-bearing plate has multiple micro-holes (13) arranged in a matrix. A dense mesh is provided on the sand-bearing plate. The molding platform (11) is installed on the frame (8) through a lifting screw.

4. The staged refrigeration device for cryogenic sand mold additive manufacturing matrix according to claim 1, characterized in that, The print head (7) is connected to the right side of the sand spreading device (5) by a lead screw, and the print head (7) moves back and forth by the motor driving the lead screw to rotate.

5. The staged refrigeration device for cryogenic sand mold additive manufacturing matrix according to claim 1, characterized in that, The roller (6) is fixedly installed on the left side of the sand spreading device. The roller (6) is driven to rotate by the motor. The sand spreading device (5) drives the roller (6) and the printing nozzle (7) to move left and right through the guide rails (10) on both sides of the frame (8) to achieve sand spreading, compaction and printing.

6. A method for performing staged cooling of a frozen sand mold additive manufacturing matrix using the staged cooling apparatus for frozen sand mold additive manufacturing according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Select appropriate molding sand according to the type of casting, perform equal-thickness layered slicing on the geometric model of the mold, and determine the two-dimensional slicing information of each layer. S2. Place the molding sand into the sand spreading device (5). At this time, the sand spreading device (5) is on the left side of the guide rail (10). First, lay the bottom sand in the molding platform (11). Then, according to the calculated sand spreading thickness, move the sand spreading device (5) to the right to lay a single layer of sand. At the same time as laying the sand, turn on the vacuum pump (9) to flatten the sand layer by negative pressure adsorption and roller rolling and increase the density of the molding sand and the flatness of the sand layer to form a sand layer. S3. When the sand-laying device moves to the right end along the guide rail (10), the sand-laying operation of a single layer of sand is completed. The sand-laying device moves to the left along the guide rail. At this time, the printing nozzle (7) sprays water-based adhesive according to the two-dimensional slice information of this layer to carry out the printing operation. S4. After the printing nozzle (7) sprays a layer of molding sand, the matrix integrated cooling device (4) is controlled by the electric cylinder (3) to descend above the sand layer and maintain a certain distance. According to the location of the printed pattern on the sand layer, the corresponding cooling plate of the matrix integrated cooling device (4) is opened and the cooling temperature is set to realize the rapid regional freezing and molding of the printed pattern. S5. The sand-bearing plate of the forming platform (11) is lowered by a layer thickness by rotating the screw below the forming platform (11). Repeat S2-S4 to continue printing multiple layers until the printing operation of the preset mold is completed. S6. Remove the frozen sand mold and transport it to the sand mold gradient cooling storage chamber for low-temperature conditioning, and clean the workbench.

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