Programmable additive manufacturing multi-template integrated precision sand spreader and method thereof

Abstract

The present application relates to programmable additive manufacturing multi-template integrated precision sand spreader. The device comprises a sand dropping mechanism and a sand flow tester, wherein the sand dropping mechanism is composed of a fixed plate, a cylinder, a sand blocking plate assembly, a plurality of sand boxes and a plurality of sets of cylinder and sand dropping template assembly. By adjusting the position of sand dropping template and sand blocking plate, the device realizes the sand dropping at fixed point and the laying of high flexible net format multi-material sand bed. The sand flow tester is a punch plate flow meter integrated on the sand box, which can monitor the falling amount of sand particles in real time and realize the accurate control of sand dropping amount. The programmable controller controls the stopping position of sand box, sand blocking plate and sand dropping template during work, thereby improving the sand dropping efficiency and stability. The present application is helpful for high-precision, high-efficiency and high-performance printing of multi-material sand mold, and realizes the high-quality manufacturing of complex parts. It has important significance for the further popularization and application of multi-material sand mold.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of multi-material sand print paver, in particular to a programmable multi-template integrated precise sand paver for additive manufacturing. BACKGROUND

[0002] Multi-material composite sand mold is a new process method for preparing sand mold by using two or more than two molding sand materials. The prepared sand mold has the performance of multiple materials, and has more excellent complex casting local organization and mechanical property control ability compared with single material sand mold. In recent years, multi-material composite sand mold additive manufacturing technology and equipment have gradually become a research hotspot at home and abroad.

[0003] However, multi-material composite sand mold currently still faces many difficulties that need to be broken through, and how to simultaneously pave the sand bed containing multiple molding sand materials is a key link for successful printing of multi-material sand mold. At present, multi-material sand mold printing paver mainly includes two types, but these two types of pavers still have the following shortcomings when paving multiple molding sand particles:

[0004] As shown in Figure 8 The first type of multi-material sand mold printing paver is shown in the figure, which sets multiple small partitions in the traditional sand box to obtain several small sand boxes. Different material molding sand particles are stored in different sand boxes. When paving, the air cylinder pushes the sand blocking plate, and the molding sand particles fall under the action of gravity to complete the paving of multi-material molding sand. The advantage of this type of paver is simple structure and high sand paving efficiency, but its disadvantage is that it can only pave a simple "few bars" structure form of multi-material sand bed, and the flexibility level of the paving process is not high, and it cannot pave the net format multi-material sand bed as shown in Figure 9 The figure has been unable to meet the current multi-material composite sand mold additive manufacturing preparation requirements.

[0005] The second type of multi-material sand printing sand layering device adopts a matrix type sand layering structure. Related structure design sand layering device patents include: CN114918371B, a high-flexibility multi-region sand layering method and device for multi-material sand printing, CN114850417B, a sand layering and vibration compaction device for preparing a multi-material composite sand mold, and CN116493609B, a combined sand mold additive manufacturing multi-material integrated sand layering device and method. This type of device can lay a multi-material sand bed in a grid format. However, the size of this type of sand layering device is close to the size of the entire forming platform during design, and the structure is complex but not highly stable. In addition, most of these sand layering devices use vibration to layer sand. During the sand layering process, sand layering may be insufficient, and sand may leak from non-sand layering areas. Long-term use may also cause device wear and tear, leading to changes in sand layering amount. Even if the same process parameters are used during long-term use, it is difficult to ensure that the sand layering amount remains the same. Due to the vibration characteristics of this type of sand layering device, it is difficult to install a flow tester on the device, making it difficult to accurately monitor the sand layering amount.

[0006] A more advanced multi-material sand layering device is disclosed in patent CN117798324A, a flexible dynamic adjustment multi-material precise sand layering method and device. This device can lay a relatively uniform multi-type sand material grid format powder bed. However, in addition to the problems of the second type of multi-material sand printing sand layering device described above, once the sand layering device is designed and the partition position is determined, the number of powder bed grids along the sand layering direction is also determined. If a powder bed with more powder bed grids along the sand layering direction and higher flexibility is desired, the sand layering device and the corresponding partition need to be reprocessed. At the same time, when using this sand layering device, sand needs to be loaded into the sand layering groove corresponding to the grid that needs to be sand layered. The excess sand in the other sand layering grooves needs to be cleaned, making the device less convenient to use. In addition to the above problems, there is a certain gap between the baffles of different sand layering openings, and sand cannot be layered at the gap. The laid powder bed will have a noticeable gap, and the overall powder bed flatness is poor. In summary, the CN117798324A flexible dynamic adjustment multi-material precise sand layering method and device still has some problems that need to be solved.

[0007] Therefore, it is necessary to design a sand layering device specifically for multi-material sand printing, achieve high flexibility in laying a multi-material sand bed, accurately control the sand layering amount, ensure the overall sand layering device structure is simple and can operate stably for a long time, and further optimize the multi-material sand printing process to improve the efficiency of multi-material sand mold forming. This is an important problem that needs to be solved in the current multi-material composite sand mold additive manufacturing technology. SUMMARY

[0008] To solve the above problems, the application discloses a programmable additive manufacturing multi-template integrated precise sand laying device, which comprises a plurality of sand boxes, and each sand box is equipped with an independently controllable electric cylinder and a sand laying template, and a sand blocking plate is designed to control the sand laying sequence of the sand boxes.

[0009] To achieve the above-mentioned purposes, the programmable additive manufacturing multi-template integrated precise sand laying device comprises a sand laying mechanism and sand flow testers one and two.

[0010] As a further design of the present application, the bottom of each sand box is provided with an elongated sand laying opening with the same size, the width of the sand laying opening is a mm, and the length is b mm, wherein a is 3 mm at the minimum and 10 mm at the maximum, and the size of b depends on the printing forming size and is consistent with the length of the forming table in the printing direction.

[0011] As a further design of the scheme, the lower sand mold plate one and the lower sand mold plate two are structurally identical, and a plurality of narrow slots arranged along the diagonal lines are arranged on the lower sand mold plate, the total number of the narrow slots on one plate is n, and the width of each narrow slot is amm and the length is (b / n) mm.

[0012] As a further design of the scheme, the air cylinder can drive the sand baffle to stop at any position, and the sand baffle can satisfy that the two openings are respectively and simultaneously located below the lower sand outlets one and two in the sliding stroke. In the initial position, neither of the two openings of the sand baffle is below the lower sand outlet.

[0013] As a further design of the scheme, the electric cylinder one and the electric cylinder two can drive the lower sand mold plate to stop at n positions, which correspond to the n narrow slots on the plate, so as to ensure that each narrow slot can be located directly below the lower sand outlet of the corresponding sand box; that is, when the electric cylinder one drives the lower sand mold plate one to the first position, the first narrow slot on the lower sand mold plate one is located directly below the lower sand outlet, when the electric cylinder one drives the lower sand mold plate one to the second position, the second narrow slot on the lower sand mold plate one is located directly below the lower sand outlet, and so on. The process of driving the lower sand mold plate two by the electric cylinder two is the same. In the initial position, none of the narrow slots on the lower sand mold plate is below the lower sand outlet.

[0014] As a further design of the scheme, the same sand box stores sand particles of the same material, different sand boxes store sand particles of different types or different mesh sizes, and the types of sand that can be stored include quartz sand, chromite sand, zircon sand, ceramsite sand, limestone sand, corundum sand, magnesia sand and refractory clinker sand.

[0015] As a further design of the scheme, in order to realize the simultaneous laying of more than two types of sand materials, a plurality of sand boxes can be added to the above device, and a plurality of sets of electric cylinders, connecting pieces and lower sand mold plates are correspondingly arranged. The overall device includes m sand boxes, m sets of electric cylinders, connecting pieces and lower sand mold plates. The lower sand mold plate corresponds to the sand box one by one and is located below the corresponding sand box. The sand baffle is designed with m openings, and the distance between two openings is (x-a) mm.

[0016] As a further design of the scheme, the sand flow tester is a chute type solid flow meter, and each sand box is equipped with a set of chute type solid flow meter. The centripetal force measuring piece of the chute type solid flow meter is installed on the inner surface of the side wall of the corresponding sand box, so as to realize the online statistics of the centripetal force of the sand particles in the sand dropping process to measure the particle flow in real time. The signal corresponding to the instantaneous flow is transmitted to the display instrument, the instantaneous flow is displayed and output, so as to adjust the sand dropping parameters to realize quantitative sand dropping.

[0017] The application also provides a programmable additive manufacturing multi-template integrated precise sand laying method, which comprises the following steps:

[0018] Step 1: design the sand laying scheme according to the characteristics of the casting and the sand print slicing information, design the sand bed laid in each layer as a grid pattern diagram, each cell corresponds to a type of sand particles, the sand bed grid pattern diagram is divided into several rows, the number of grids in each row should be equal to the number of narrow slots of the sand laying template when designing, and the cells in each row are numbered in turn as 1, 2, 3, …, n;

[0019] Step 2: laying the first row of sand particles: first, lay the first type of sand material, the corresponding sand box sand outlet is aligned with the starting position of the first row of grids, and the corresponding cells of all the first type of sand material are sequentially sand-filled; after laying the first type of sand material, the sand outlet of the sand box of the second type of sand material is aligned with the starting position of the second row of grids, and the laying method of the first type of sand material is repeated to lay the second type of sand material, and all the sand materials are sequentially laid until all the cells in the first row are completed. The laying of the sand material; the specific sand filling method of each grid is illustrated by taking the sand box laying the cell numbered j in the first row as an example: the cylinder pushes the sand laying template to the jth position, ensures that the jth narrow slot on the sand laying template is located below the sand outlet, the cylinder pushes the sand blocking plate to make the opening located below the sand outlet, the sand particles fall from the sand box and fall into the starting position of the cell numbered j in the first row, after sand filling, the sand blocking plate returns to the original position, and the sand laying template also returns to the original position;

[0020] Step 3: during the sand filling process of step 2, the sand flow tester monitors the sand filling amount in real time, so that when the same type of sand material is sand-filled in the subsequent grid, the cylinder adjusts the position of the sand blocking plate and the electric cylinder adjusts the time of pushing the sand laying template, so as to adjust the size of the sand falling channel and the falling time, and then accurately adjust the sand filling amount, so as to realize the accurate control of the sand filling amount;

[0021] Step 4: repeat steps 2 and 3 until the sand filling of all rows of sand particles is completed;

[0022] Step 5: after sand filling, the sand surface is flattened by other compacting devices of the sand print machine, and a flat multi-material sand bed is obtained, which is convenient for the subsequent inkjet printing process.

[0023] As a further design of the present scheme, the plurality of sand boxes, sand blocking plates and plurality of sand laying templates can be controlled by a programmable controller to accurately control the stopping positions of the plurality of sand boxes, sand blocking plates and plurality of sand laying templates during sand filling work, thereby improving the sand filling efficiency and stability.

[0024] The beneficial effects of the present application are:

[0025] (1) The present application designs a position-adjustable sand blocking plate and a sand dropping template, which can construct a narrow groove-shaped sand dropping channel at any position above the forming platform, cooperate with multiple sand boxes, realize the fixed-point sand dropping of various sand materials, and can lay the grid-shaped multi-material sand bed with arbitrary distribution of sand materials. Meanwhile, only by replacing the sand dropping template and adjusting the sand dropping time, different size sand bed cells can be laid, and the flexibility level is high.

[0026] (2) The present application also integrates a sand flow tester on the sand dropping mechanism to monitor the sand dropping amount in real time, adjusts the position of the sand blocking plate through the feedback result, controls the size of the sand dropping channel, adjusts the opening and closing time of the sand dropping template, realizes the accurate control of the sand dropping amount, and realizes the quantitative sand dropping.

[0027] (3) The size of the device of the present application does not obviously increase compared with the sand layering device used in the traditional single-material sand mold printing device, and the structure is simple compared with the existing multi-material sand layering device, but the sand layering flexibility level is improved; the sand layering device of the present application is not easy to cause equipment wear in long-term use, and effectively reduces the use cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a schematic diagram of the sand dropping mechanism device of the programmable additive manufacturing multi-template integrated precise sand layering device of the present application.

[0029] Figure 2 It is a top view of the sand dropping mechanism device of the programmable additive manufacturing multi-template integrated precise sand layering device of the present application.

[0030] Figure 3 It is a partial enlarged view of the air cylinder mounting plate of the present application.

[0031] Figure 4 It is a top view of the sand blocking plate of the present application.

[0032] Figure 5 It is a side view of the air cylinder mounting plate of the present application.

[0033] Figure 6 It is a top view of the sand dropping template of the present application.

[0034] Figure 7 It is an installation schematic diagram of the sand flow tester of the present application.

[0035] Figure 8 It is a first type of multi-material sand mold printing sand layering device in the existing equipment.

[0036] Figure 9 It is a sand layering grid pattern schematic diagram of embodiment 1 of the present application.

[0037] Figure 10 It is a top view of the sand dropping template of embodiment 1 of the present application.

[0038] Figure 11 This is a schematic diagram of the sand-laying grid pattern in Embodiment 2 of the present invention.

[0039] Figure 12 This is a top view of the sand-filled template in Embodiment 2 of the present invention.

[0040] Attached Figure Descriptions: 1-Sand Box II; 2-Fixing Plate; 3-Electric Cylinder Mounting Plate; 4-Pneumatic Cylinder Mounting Plate; 5-Sand Box I; 6-Electric Cylinder I; 7-Connecting Plate I; 8-Sand Lowering Template I; 9-Sand Lowering Template II; 10-Connecting Plate II; 11-Electric Cylinder II; 12-Sand Lowering Port II; 13-Sand Lowering Port I; 14-Pneumatic Cylinder; 15-Sand Baffle Plate Connector; 16-Sand Baffle Plate; 17-Opening 2; 18-Opening I; 19-Upper Sliding Groove; 20-Lower Sliding Groove; 21-Measuring Plate; 22-Punching Plate Flow Meter. Detailed Implementation

[0041] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0042] like Figures 1-7 As shown, this embodiment provides a programmable additive manufacturing multi-template integrated precision sand spreader. The sand feeding mechanism includes a fixed plate 2, a sand holding box 1, a sand holding box 2, a sand baffle plate, a sand feeding template 1, a sand feeding template 2, a cylinder mounting plate, an electric cylinder mounting plate, a cylinder, an electric cylinder 1, and an electric cylinder 2. The sand holding box 1 and the sand holding box 2 are of the same size and are sequentially arranged within two rectangular openings of the fixed plate. A pair of cylinder mounting plates are provided on the outer sides of the two sand holding boxes, and the cylinder mounting plates have two sliding grooves of different heights. A pair of electric cylinder mounting plates are provided on the outer sides of the cylinder mounting plates. Cylinders are fixed to the cylinder mounting plates respectively. The sand baffle plate is connected to the cylinder through a sand baffle plate connector. The surface of the sand-holding box is fitted to the bottom to prevent sand leakage. During installation, the sand-holding plate passes through the upper sliding groove of the cylinder mounting plate, and the upper sliding groove guides the sand-holding plate. The first sand-holding template is connected to a set of electric cylinders through a connecting plate, and the second sand-holding template is connected to a set of electric cylinders through a connecting plate. Both electric cylinders are mounted on the electric cylinder mounting plate. The first sand-holding template is located below the first sand-holding box, and the second sand-holding template is located below the second sand-holding box. Both the first and second sand-holding templates pass through the lower sliding groove of the cylinder mounting plate, and the lower sliding groove guides the horizontal sliding of the sand-holding templates. The first molding sand flow tester is located below the first sand-holding box, and the second molding sand flow tester is located below the second sand-holding box.

[0043] The bottom of the sand box one and the sand box two is provided with an identical size of the elongated sand outlet, the width of the sand outlet is a mm, the length is b mm, wherein a is 3 mm at least and 10 mm at most, the size of b depends on the printing forming size and is consistent with the length of the forming table in the printing direction.

[0044] The sanding template one and the sanding template two are identical in structure, the sanding template is provided with a plurality of narrow slots arranged along the diagonal line, the total number of the narrow slots on one template is n, the width of each narrow slot is a mm, and the length is (b / n) mm.

[0045] The air cylinder can drive the sand blocking plate to stay at any position, and the sand blocking plate can meet the requirement that the opening one and the opening two are respectively and not simultaneously located below the sand outlet one and the sand outlet two in the sliding stroke. In the initial position, the two openings of the sand blocking plate are not located below the sand outlet.

[0046] The electric cylinder one and the electric cylinder two can drive the sanding template to stay at n positions corresponding to the n narrow slots on the template, so as to ensure that each narrow slot can be located directly below the sand outlet of the corresponding sand box; that is, when the electric cylinder one drives the sanding template one to the first position, the first narrow slot on the sanding template one is located directly below the sand outlet, when the electric cylinder one drives the sanding template one to the second position, the second narrow slot on the sanding template one is located directly below the sand outlet, and so on. The process of driving the sanding template two by the electric cylinder two is the same. In the initial position, all the narrow slots on the sanding template are not located below the sand outlet.

[0047] The same sand box stores the same type of sand particles, different sand boxes store different types or different mesh sizes of sand particles, and the types of sand that can be stored include quartz sand, chromite sand, zircon sand, ceramsite sand, limestone sand, corundum sand, magnesia sand, and refractory clinker sand.

[0048] In order to realize the simultaneous laying of more than two types of sand materials, a plurality of sand boxes can be added to the above device, and a plurality of sets of electric cylinders, connecting pieces and sanding templates are correspondingly provided. The overall device includes m sand boxes, m sets of electric cylinders, connecting pieces and sanding templates. The sanding template corresponds to the sand box one by one and is located below the corresponding sand box. The sand blocking plate is designed with m openings, and the distance between two openings is (x-a) mm.

[0049] The sand flow tester is a chute type solid flow meter, each sand box is equipped with a set of chute type solid flow meter, the centripetal force measuring piece of which is installed on the inner surface of the corresponding sand box side wall, so as to realize online statistics of the centripetal force of the sand particles in the sand dropping process to measure the particle flow in real time, the signal corresponding to the instantaneous flow is transmitted to the display instrument, the instantaneous flow is displayed and output, so as to adjust the sand dropping parameters to realize quantitative sand dropping.

[0050] Example 1, a 4x4 grid of multi-material sand beds is laid out as shown in Figure 9 The overall sand bed size is 400mmx400mm, and each cell is 100mmx100mm. The gray cells are laid with 70 / 140 mesh silica sand mixed with 2.2‰ curing agent, and the black cells are laid with 70 / 140 mesh chromite sand mixed with 2.6‰ curing agent. The sand dropping amount of each silica sand cell is about 11g, and the sand dropping amount of each chromite sand cell is about 18g.

[0051] The bottom of the sand box one and the sand box two are both provided with an elongated sand dropping port with the same size, and the size of the sand dropping port is 5mmx400mm. The distance between the two sand dropping ports is 160mm. The sand material filled in the sand box one is 70 / 140 mesh silica sand mixed with 2.2‰ curing agent, and the sand material filled in the sand box two is 70 / 140 mesh chromite sand mixed with 2.6‰ curing agent. The sand baffle is provided with two openings with the same size, and the size of the opening is 5mmx400mm. The distance between the two openings is 155mm. The sand dropping template one and the sand dropping template two have the same structure, and are both provided with a plurality of narrow slots arranged along the diagonal lines. The top view is as shown in Figure 10 The total number of narrow slots on one template in this embodiment is 4, and the size of each narrow slot is 5mmx100mm.

[0052] According to the grid diagram of the sand bed laid in this layer, the corresponding control program is written to accurately control the stopping position of the sand box one, the sand box two, the sand baffle, the sand dropping template one and the sand dropping template two during work.

[0053] During the laying process, the whole sand laying device moves forward until the sand box one stays above the sand dropping point of the first row of cells, the electric cylinder pushes the sand dropping template one until the No.1 narrow slot is below the sand dropping port, the air cylinder pushes the sand blocking plate to slide until the opening one is aligned with the sand dropping port one and stays for a period of time, the silica sand particles fall from the sand cell one under the action of gravity and finally fall at the starting edge of the No.1 cell of the first row, and the total weight of the sand falling is about 11g. After the sand dropping of the No.1 cell is completed, the sand blocking plate and the sand dropping template one return to the initial position in turn. The electric cylinder pushes the sand dropping template one until the No.3 narrow slot is below the sand dropping port, the air cylinder pushes the sand blocking plate to slide until the opening one is aligned with the sand dropping port and stays, the silica sand particles fall into the No.3 cell of the first row, and after the sand blocking plate returns to the starting position, the sand dropping template one also returns to the starting position. After the silica sand laying of the first row is completed, the sand laying device moves forward by a distance until the sand box two stays above the sand dropping position of the first row of cells, ready to lay the chromite sand cells of the first row. The electric cylinder pushes the sand dropping template two until the No.2 narrow slot of the sand dropping template two is below the sand dropping port two, and then the air cylinder pushes the sand blocking plate until the opening two is located directly below the sand dropping port two. After the sand blocking plate stays at this position for a period of time and returns to the original position, about 18g of chromite sand falls into the No.2 cell of the first row during the opening and closing process of the sand blocking plate, and after the sand dropping is completed, the sand dropping template two also returns to the starting position. The electric cylinder pushes the sand dropping template again until the No.4 narrow slot coincides with the sand dropping port two, the air cylinder pushes the sand blocking plate to move forward until the opening two is also below the sand dropping port two, and the chromite sand falls into the No.4 cell of the first row. The sand blocking plate and the sand dropping template two return to the original position in turn, and thus the sand dropping of all the cells of the first row is completed. The sand laying box continues to move, and the sand box one stops sliding when it is located at the sand dropping point of the second row of cells. The electric cylinder pushes the sand dropping template one again, the No.2 narrow slot of the sand dropping template one coincides with the sand dropping port one, the air cylinder pushes the sand blocking plate, and the opening one also coincides with the sand dropping port one. The silica sand falls into the No.2 cell of the second row, and after a period of time, the sand blocking plate returns to the original position, and the sand dropping template one also returns to the original position. The sand dropping template one slides forward again until the No.4 narrow slot is below the sand dropping port, the sand blocking plate slides, and the opening one is also below the sand dropping port. The silica sand falls, and the sand blocking plate and the sand dropping template one return to the original position in turn, and the silica sand cells of the second row are all completed. The sand dropping mechanism adjusts the position, the sand box two is above the sand dropping position of the second row of cells, the electric cylinder pushes the sand dropping template two, the No.1 narrow slot coincides with the sand dropping port two, the air cylinder pushes the sand blocking plate until the opening two also coincides with the sand dropping port two, and the chromite sand particles fall from the sand box two and fall into the No.1 cell of the second row. After the sand dropping is completed, the sand blocking plate and the sand dropping template two return to the original position in turn. The electric cylinder pushes the sand dropping template again until the No.3 narrow slot moves to below the sand dropping port two, the air cylinder pushes the sand blocking plate until the opening two is below the sand dropping port two, and the chromite sand falls into the No.3 cell of the second row. The sand blocking plate and the sand dropping template two return to the original position in turn, and the sand dropping of all the cells of the second row is completed.The sand laying box continues to move until the sand laying box one is at the sand dropping position of the third row of cells, the sand dropping method of the first row is repeated, the silica sand is laid, the sand laying box two is adjusted to be at the sand dropping position of the third row of cells, and the chromite sand is laid. The sand laying box slides again, the above sand laying method is repeated, and the sand dropping of all cells in the fourth row is completed. During the sand dropping process, the sand flow tester continues to work, and the sand dropping amount is monitored in real time and compared with the set value of 11 g of silica sand and 18 g of chromite sand. When the sand dropping amount deviates by more than 1 g, the opening and closing time of the sand blocking plate is adjusted to ensure that the sand dropping amount of each cell is controlled within the range of (11±1) g of silica sand or (18±1) g of chromite sand.

[0054] At this point, the sand dropping is completed, the compaction device of the printer flattens and compacts the dropped sand, and a grid sand bed of two materials with a smooth surface is obtained, which facilitates subsequent inkjet printing.

[0055] In example 2, a 9x10 grid multi-material sand bed as shown in Figure 11 is laid out. The overall sand bed size is 400mmx400mm, except that the size of the cells in the fifth row is 40mmx80mm, and the size of the cells in the remaining rows is 40mmx40mm. The light gray cells are laid with 70 / 140 mesh silica sand mixed with a curing agent, the dark gray cells are laid with 50 / 100 mesh silica sand mixed with a curing agent, the black cells are laid with 70 / 140 mesh chromite sand mixed with a curing agent, and the diagonal shaded cells are laid with 70 / 140 mesh zircon sand mixed with a curing agent. In the fifth row, the sand dropping amount of the two silica sand cells is 3.6g, and the sand dropping amount of the chromite sand cell is 5.8g. In the remaining rows, the sand dropping amount of the two silica sand cells is 1.8g, the sand dropping amount of the chromite sand cell is 2.9g, and the sand dropping amount of the zircon sand cell is 3.1g.

[0056] The sand laying device for laying the multi-material sand bed includes four sand laying boxes, namely sand laying box one, sand laying box two, sand laying box three and sand laying box four. Each of the four sand laying boxes is equipped with a set of electric cylinders, connecting parts and sand dropping templates. The bottom of each of the four sand laying boxes is provided with an elongated sand dropping port of the same size, and the size of the sand dropping port is 5mmx400mm. The distance between the two sand dropping ports is 120mm. The sand laying material filled in the sand laying box one is 70 / 140 mesh silica sand mixed with 2.2‰ curing agent, the sand laying material filled in the sand laying box two is 50 / 100 mesh silica sand mixed with 2.2‰ curing agent, the sand laying material filled in the sand laying box three is 70 / 140 mesh chromite sand mixed with 2.6‰ curing agent, and the sand laying material filled in the sand laying box four is 70 / 140 mesh zircon sand mixed with 2.4‰ curing agent. The sand blocking plate is designed with four openings of the same size, and the size of each opening is 5mmx400mm. The distance between the two openings is 115mm. The four sand dropping templates have the same structure and are provided with a plurality of narrow slots arranged along the diagonal lines. The top view is as shown in Figure 12As shown, the total number of narrow slots on the template in this embodiment is 10, and the size of each narrow slot is 5 mm x 40 mm.

[0057] According to the grid diagram of the sand bed laid by the layer, a corresponding control program is written to accurately control the stop positions of the sand box 1, the sand box 2, the sand box 3, the sand box 4, the sand blocking plate, the sand lowering template 1, the sand lowering template 2, the sand lowering template 3, and the sand lowering template 4 during work.

[0058] During the laying process, the sand layerer sequentially lowers sand from the first row to the ninth row of cells, and in the laying process of each row, sand is sequentially lowered according to the type of sand particles. The laying process is specifically described by taking the laying of the third row and the fifth row as examples.

[0059] When sanding under the third row of cells, first lay 70 / 140 mesh silica sand, sand box a is moved to the third row of cells sanding point directly above, in turn lay No. 2, No. 4, No. 7 and No. 9 cells. When laying No. 2 cell, the sanding template moves No. 2 narrow slot to align with the sanding port one, the sand blocking plate moves, when the opening one aligns with the sanding port one, stop moving, after a certain time, the sand blocking plate returns to the original position, the sanding template also retreats to the original position, about 1.8g of silica sand falls into No. 2 cell, during the sanding process, the sand flow tester continues to work, real-time monitoring of the sanding amount is compared with the set value, when the sanding amount deviation exceeds 0.2g, adjust the opening and closing time of the sand blocking plate, ensure that the sanding amount of each cell is controlled within the required range. Repeat the sanding method of No. 2 cell, in turn lay No. 4, No. 7 and No. 9 cells, the difference is that when laying other cells, the corresponding No. narrow slot on the sanding template one aligns with the sanding port one. After laying 70 / 140 mesh silica sand, sand box two is moved to the third row of cells sanding point directly above, lay No. 1 and No. 10 cells of 50 / 100 mesh silica sand, the sanding template two and the sand blocking plate opening and closing mode are the same as when laying 70 / 140 mesh silica sand. Sand box three is moved to the third row of cells sanding point directly above, lay No. 5 and No. 6 cells of 70 / 140 mesh chromite sand, finally sand box four is moved to the third row of cells sanding point directly above, lay No. 3 and No. 8 cells of 70 / 140 mesh zircon sand. However, due to the different types of sand particles in the four sand boxes, the densities are different, and the fluidity is also different, during the sanding process, attention should be paid to control the opening and closing time of the sand blocking plate to adjust the sanding time, and then control the sanding amount. When laying the fifth row of sand particles, the specific sand laying scheme is consistent with the third row, in turn sanding the corresponding cells of 70 / 140 mesh silica sand, 50 / 100 mesh silica sand and 70 / 140 mesh chromite sand, but the difference is that the fifth row of cells is twice the size of the third row of cells, so the sanding amount should also be twice, the opening and closing time of the sand blocking plate needs to be strictly controlled, the sanding amount is monitored in real time online through the impact plate flow meter, the opening and closing time of the sand blocking plate is adjusted to realize accurate quantitative sanding, ensure that the sanding amount of the fifth row of cells meets the laying requirements, and does not exceed.

[0060] After all the cells are sanded, the compaction device of the printer flattens and compacts the sanding, and a surface flat mesh pattern multi-material sand bed is obtained.

[0061] The technical means disclosed in the scheme of the application is not limited to the technical means disclosed in the above-mentioned embodiments, but also includes technical solutions composed of any combination of the above technical features.

Claims

1. A programmable additive manufacturing multi-template integrated precision sand spreader, characterized in that... The system includes a sand feeding mechanism and two molding sand flow testers. The sand feeding mechanism includes a fixed plate (2), a sand holding box (5), a sand holding box (1), a sand baffle (16), a sand feeding template (8), a sand feeding template (9), a cylinder mounting plate (4), an electric cylinder mounting plate, a cylinder (14), an electric cylinder (6), and an electric cylinder (11). The sand holding box (5) and the sand holding box (1) are of the same size and are arranged in sequence in the two rectangular openings of the fixed plate (2). A pair of cylinder mounting plates (4) are provided on the outside of the two sand holding boxes. The cylinder mounting plates (4) have two sliding grooves of different heights. A pair of electric cylinder mounting plates are provided on the outside of the cylinder mounting plates (4). Cylinders (14) are fixed on the cylinder mounting plates (4). The sand baffle (16) is connected to the cylinder (14) through the sand baffle connector (15). The upper surface of the sand baffle (16) is connected to the cylinder (14). The bottom of the sand box fits together to prevent sand leakage. During installation, the sand baffle (16) passes through the upper sliding groove (19) of the cylinder mounting plate (4), and the upper sliding groove (19) serves as a guide for the sand baffle. The first sand template (8) is connected to a set of electric cylinders (6) through the first connecting plate (7), and the second sand template (9) is connected to a set of electric cylinders (11) through the second connecting plate (10). Both the first electric cylinder (6) and the second electric cylinder (11) are mounted on the electric cylinder mounting plate (3). The first sand template (8) is located below the first sand box (5), and the second sand template (9) is located below the second sand box (1). Both the first sand template (8) and the second sand template (9) pass through the lower sliding groove (20) of the cylinder mounting plate (4), and the lower sliding groove (20) serves as a guide for the horizontal sliding of the sand template. The first molding sand flow tester is located below the first sand box, and the second molding sand flow tester is located below the second sand box.

2. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 1, characterized in that, The bottom of both the first sand container (5) and the second sand container (1) has a long and narrow sand outlet of the same size. The width of the sand outlet is a mm and the length is b mm. The minimum of a is 3 mm and the maximum is 10 mm. The size of b depends on the printing size and is consistent with the length of the forming table in the printing normal direction. The sand baffle (16) has two openings of the same size, and the opening size is consistent with the size of the lower sand opening of the sand box. The width is a mm and the length is b mm. The distance between the two openings on the sand baffle (16) is related to the distance between the two lower sand openings. If the distance between the two lower sand openings is x mm, then the distance between the two openings on the sand baffle is (xa) mm.

3. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 2, characterized in that, The first sand-feeding template (8) and the second sand-feeding template (9) have the same structure. The sand-feeding template is provided with a number of narrow grooves arranged along the diagonal. The total number of narrow grooves on the sand-feeding template is n. The width of each narrow groove is a mm and the length is (b / n) mm.

4. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 3, characterized in that, The cylinder (14) can push the sand baffle (16) to stay in any position. Within the sliding stroke, the sand baffle (16) can satisfy that the sand baffle opening one and opening two are respectively and not simultaneously located below the sand outlet one and sand outlet two. In the initial position, neither of the two openings of the sand baffle (16) is below the sand outlet.

5. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 4, characterized in that, Both the electric cylinder 1 (6) and the electric cylinder 2 (11) can push the sand-feeding template to stay at n positions, which correspond one-to-one with the n narrow slots on the sand-feeding template, ensuring that each narrow slot is located directly below the sand outlet of the corresponding sand box; that is, when the electric cylinder 1 pushes the sand-feeding template to position 1, the narrow slot 1 on the sand-feeding template is located directly below the sand outlet, when the electric cylinder 1 pushes the sand-feeding template to position 2, the narrow slot 2 on the sand-feeding template is located directly below the sand outlet, and so on. The process of the electric cylinder 2 pushing the sand-feeding template is the same; at the initial position, all the narrow slots on the sand-feeding template are not below the sand outlet.

6. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 5, characterized in that, The same sand container contains molding sand particles of the same material, while different sand containers contain molding sand particles of different types or mesh sizes. The types of molding sand stored include quartz sand, chromite sand, zircon sand, ceramsite sand, limestone sand, corundum sand, magnesia sand, and refractory clinker sand.

7. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 6, characterized in that, To enable the simultaneous laying of more than two types of molding sand materials, several sand-holding boxes are added to the above-mentioned device, and several sets of electric cylinders, connectors and sand-lowering templates are set accordingly. The whole device includes m sand-holding boxes, m sets of electric cylinders, connectors and sand-lowering templates. The sand-lowering templates correspond one-to-one with the sand-holding boxes and are located below the corresponding sand-holding boxes. The sand baffle is designed with m openings, and the distance between each pair of openings is (xa) mm.

8. The programmable additive manufacturing multi-template integrated precision sand spreader according to claim 7, characterized in that, The molding sand flow tester is a punch plate flow meter (22). Each sand box is equipped with a punch plate flow meter. The measuring plate (21) of the punch plate flow meter (22) is installed on the inner surface of the corresponding side wall of the sand box to realize the force on the plate during the sand dropping process and calculate the flow rate of the molding sand particles. The signal corresponding to the instantaneous flow rate is transmitted to the display instrument to display and output the instantaneous flow rate so as to adjust the sand dropping parameters to achieve quantitative sand dropping.

9. The sand-laying method of the programmable additive manufacturing multi-template integrated precision sand-laying device according to claim 8, characterized in that, The method includes the following steps: Step 1: Design the sand laying scheme based on the casting characteristics and sand mold printing slice information. Design each layer of sand bed as a grid pattern diagram. Each cell corresponds to a type of molding sand particle. The sand bed grid pattern diagram is divided into several rows. The number of grids in each row should be equal to the number of narrow slots in the sand template. The cells in each row are numbered sequentially as 1, 2, 3, ..., n. Step 2: Laying the first row of molding sand particles: First, lay the first type of molding sand material. Align the sand inlet of the corresponding sand container with the starting position of the first row of grids. Lay sand onto all corresponding cells of the first type of molding sand material in sequence. After laying the first type of molding sand material, align the sand inlet of the sand container of the second type of molding sand material with the starting position of the second row of grids. Repeat the laying method of the first type of molding sand material to lay the second type of molding sand material. Lay all molding sand materials in sequence until all cells of the first row have been laid. The specific sand dropping method for each grid is as follows: Taking the sand container one laying the cell numbered j in the first row as an example: Electric cylinder one pushes the sand dropping template one to position j, ensuring that the jth narrow groove on the sand dropping template one is below the sand dropping inlet one. The cylinder pushes the sand baffle plate so that the opening one is below the sand dropping inlet one. The molding sand particles fall from the sand container one and land at the starting position of the cell numbered j in the first row. After the sand dropping is completed, the sand baffle plate returns to its original position, and the sand dropping template one also returns to its original position. Step 3: During the sand falling process in Step 2, the molding sand flow tester monitors the amount of sand falling in real time. When the same molding sand material falls into the subsequent grid, the cylinder finely adjusts the position of the baffle plate and the electric cylinder finely adjusts the time of pushing the sand falling template to adjust the size and falling time of the molding sand falling channel, thereby accurately adjusting the amount of sand falling and achieving precise control of the amount of sand falling. Step 4: Repeat steps 2 and 3 until all rows of molding sand particles have been removed. Step 5: After the sand is removed, the sand surface is flattened by other compaction devices of the sand mold printer to obtain a flat multi-material sand bed, which facilitates the subsequent inkjet printing process.

10. The sand-laying method according to claim 9, characterized in that, Several sand-collecting boxes, sand-baffles, and sand-dropping templates can be controlled by a programmable controller to precisely control their positions during sand dropping, thereby improving sand dropping efficiency and stability.

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