A sand mold 3D printer

Abstract

The present invention relates to the technical field of printers, and specifically relates to a sand mold 3D printer; it includes a machine body, and an electric slide rail is installed on the inner wall of the machine body; there are two groups of the electric slide rails; a hopper is slidably connected to the upper end of one group of the electric slide rails; a U-shaped frame is slidably connected to the upper end of the other group of the electric slide rails; through the cooperation between the rotating shaft and the sliding plate, static electricity adsorption is generated on the surface of the rotating shaft due to friction, so that the rotating shaft adsorbs extremely small particles through the static electricity adsorption force on the surface, reducing the extremely small particles falling from the lower port of the hopper. On the one hand, it reduces the amount of resin adsorbed by the extremely small particles, improves the spreading fluidity of the resin, ensures that effective connections can be formed between the ceramsite sands, and improves the strength of the sand mold. On the other hand, it reduces the number of extremely small particles lifted by the resin ejected from the print head, reduces the amount of extremely small particles adhering to the edge of the nozzle, delays the time of nozzle blockage, and improves the service life of the nozzle.

Description

Technical Field

[0001] The present invention relates to the technical field of printers, and more specifically, to a sand mold 3D printer. Background Art

[0002] The sand mold 3D printing technology uses silica sand or ceramsite sand as raw materials and resin as a binder to form layers by layer-by-layer adhesion; the principle is that silica sand or ceramsite sand is sent from a hopper in a certain amount to a sand spreading roller, and the sand spreading roller spreads a very thin layer of sand grains on the powder bed. The print head sprays a resin binder in the area to be formed according to the two-dimensional layer information obtained after slicing the 3D computer model to stick the sand grains, and finally accumulates layer by layer to form a three-dimensional sand mold entity.

[0003] Compared with silica sand, ceramsite sand has a higher regeneration rate, and the tensile strength, compactness, and air permeability of the ceramsite sand core are higher than those of the silica sand core. Moreover, there are no sand sticking and vein-like pattern defects in castings such as diesel engine cylinders cast with the ceramsite sand core, making the qualified rate of ceramsite sand castings higher than that of silica sand castings. Therefore, existing sand mold 3D printers tend to use ceramsite sand as the molding raw material.

[0004] Existing ceramsite sand needs to be premixed with a curing agent in a sand mixing system in a certain proportion before printing, so that the ceramsite sand will quickly cure and bond when it encounters a resin binder, while the area that does not encounter the resin binder remains loose; however, when the ceramsite sand is stirred in the sand mixing system, it will cause friction between the ceramsite sands and generate extremely small particles such as microparticles and fine powders. On the one hand, during printing, the specific surface area of these extremely small particles is large, so they are prone to adsorb more resin, inhibiting the expansion and flow of the resin, making it impossible to form an effective connection between the ceramsite sands and reducing the strength of the sand mold. On the other hand, the resin sprayed by the print head will cause the extremely small particles to be lifted, and the lifted extremely small particles will stick to the edge of the nozzle under the action of the resin viscosity, easily causing nozzle blockage, and requiring the staff to disassemble the machine for cleaning.

[0005] In view of this, in order to overcome the above technical problems, the present invention proposes a sand mold 3D printer to solve the above technical problems. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art, the present invention proposes a sand mold 3D printer. Through the cooperation between the rotating shaft and the sliding plate, static electricity adsorption is generated on the surface of the rotating shaft due to friction, so that the rotating shaft adsorbs extremely small particles through the static electricity adsorption force on the surface, reducing the extremely small particles falling from the lower port of the hopper. On the one hand, it reduces the amount of resin adsorbed by the extremely small particles, improves the expansion fluidity of the resin, ensures that an effective connection can be formed between the ceramsite sands, and improves the strength of the sand mold. On the other hand, it reduces the number of extremely small particles lifted by the resin sprayed by the print head, reduces the amount of extremely small particles adhering to the edge of the nozzle, delays the time of nozzle blockage, and improves the service life of the nozzle.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: A sand mold 3D printer according to the present invention includes:

[0008] A machine body, on the inner wall of which an electric slide rail is installed; there are two groups of the electric slide rails; a hopper is slidably connected to the upper end of one group of the electric slide rails; a U-shaped frame is slidably connected to the upper end of the other group of the electric slide rails; a connecting pipe is installed at the upper end of the hopper; one end of the connecting pipe away from the hopper is communicated with a feeding mechanism; a powder spreading roller is arranged on one side of the hopper; the powder spreading roller is fixedly connected to the hopper;

[0009] A printing head, a lead screw is arranged below the U-shaped frame; the lead screw is rotatably connected to the U-shaped frame; the printing head is in screw drive connection with the lead screw; the upper end of the printing head is in sliding contact with the U-shaped frame; an infusion pipe is installed on one side of the printing head; one end of the infusion pipe away from the printing head is communicated with an external infusion mechanism; a servo motor is installed on one side of the U-shaped frame; the output end of the servo motor is fixedly connected to the lead screw;

[0010] A rotating shaft, a screw is rotatably connected in the hopper; a groove is formed in the inner wall of the hopper; the rotating shaft is rotatably connected in the groove; the rotating shaft is in rotational contact with the upper end wall of the groove; the rotating shaft is located below the screw; a driving motor is fixedly installed on the inner wall of the hopper; the output end of the driving motor is fixedly connected to the screw; the screw and the rotating shaft are connected by a belt drive; there are two rotating shafts; the two rotating shafts are in gear transmission connection; an air suction port is formed in the lower end surface of the groove; a closing module is installed in the air suction port;

[0011] A powder feeding cylinder, a hydraulic push rod is fixedly connected to the bottom of the powder feeding cylinder; a piston is arranged at the upper end of the hydraulic push rod; the piston is in sliding and sealing connection with the inner wall of the powder feeding cylinder; a powder bed is placed on the upper end of the piston; a scraping plate is fixedly connected to the bottom of the groove; one end of the scraping plate away from the groove is in sliding contact with the rotating shaft; the rotating shaft is made of PU material; the scraping plate is made of PTFE material;

[0012] An air suction module, which is installed on one side of the hopper; the air suction module is used to generate suction force on the air suction port.

[0013] Preferably, an installation groove is formed at one end of the scraping plate close to the roller; a sliding plate is slidably connected in the installation groove; the sliding plate and the bottom of the installation groove are fixedly connected by a compression spring.

[0014] Preferably, the closing module includes a group partition board; a barrier groove is formed in the inner wall of the air suction port; the group partition board is slidably and sealingly connected in the barrier groove; the group partition board is fixedly connected to the bottom of the barrier groove through a connecting spring; a fiberglass rope is fixedly connected to one end of the barrier partition board away from the connecting spring; one end of the fiberglass rope away from the group partition board is connected to the air suction module.

[0015] Preferably, the air suction module includes a housing; the housing is installed at one end of the hopper away from the driving motor; the gear set includes a driving gear and a driven gear; both the driving gear and the driven gear are slidably and sealingly connected to the inner wall of the housing; an air inlet channel and an exhaust channel are formed in the inner wall of the hopper; the air inlet channel is located below the exhaust channel; one end of the exhaust channel is communicated with the air inlet channel, and the other end faces the rotating shaft; one end of the air inlet channel is communicated with the air suction port, and the other end is communicated with the housing; a stretching unit is installed in the air inlet channel; the stretching unit is used for pulling the fiberglass rope.

[0016] Preferably, the stretching unit includes a piston; the piston is slidably and sealingly connected in the air inlet channel; the piston is fixedly connected to the inner wall of the air inlet channel through a return spring; a U-shaped groove is formed in the inner wall of the air inlet channel; a non-woven fabric is fixedly connected to one end of the air inlet channel close to the air suction port; one end of the fiberglass rope away from the group partition board passes through the hopper and is fixedly connected to the piston; the fiberglass rope is slidably and sealingly connected to the hopper.

[0017] Preferably, a circular groove is formed in one end of the piston close to the air suction port; a push plate is slidably and sealingly connected in the circular groove; air holes communicated with the circular groove are formed on the surface of the push plate; the push plate is in sliding contact with the inner wall of the air inlet; a slider is fixedly connected to the inner wall of the air inlet channel.

[0018] Preferably, a spiral groove is formed in the inner wall of the circular groove; the push plate is in spiral transmission connection with the spiral groove; one end of the air holes close to the non-woven fabric has a smaller diameter.

[0019] Preferably, a rotating plate is provided at one end of the exhaust port away from the housing; the rotating plate is rotatably connected to the inner wall of the exhaust port through a torsion spring.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. Through the cooperation between the rotating shaft and the sliding plate, static electricity adsorption is generated on the surface of the rotating shaft due to friction, so that the rotating shaft adsorbs extremely small particles through the static electricity adsorption force on the surface, reducing the extremely small particles falling from the lower port of the hopper. On the one hand, it reduces the resin amount adsorbed by the extremely small particles, improves the expansion fluidity of the resin, ensures that effective connections can be formed between the ceramsite sands, improves the strength of the sand mold, and on the other hand, it reduces the number of extremely small particles raised by the resin ejected from the print head, reduces the amount of extremely small particles adhered to the edge of the nozzle, delays the time of nozzle blockage, and improves the service life of the nozzle.

[0022] 2. By providing the group partition plate, the present invention enables the group partition plate to block the communication between the air inlet and the outside, making one end of the air inlet passage communicate with the air inlet and the other end communicate with the housing. This allows the extremely small particles in the groove to enter the air inlet under negative pressure adsorption and be blocked by the non-woven fabric, converging at the port of the air inlet passage. As a result, the extremely small particles do not enter the air inlet, preventing them from flowing back into the hopper through the exhaust port. Until the driving motor stops rotating, at this time the group partition plate resets and the air inlet is opened, and the extremely small particles blocked by the non-woven fabric will fall out through the air inlet under the action of gravity, avoiding the accumulation and blockage of the air inlet by the extremely small particles and facilitating the user to collect the extremely small particles in the air inlet, effectively improving the practicality of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the drawings and embodiments.

[0024] Figure 1 is a perspective view of the present invention;

[0025] Figure 2 is a perspective view of the powder feeding cylinder used in the present invention;

[0026] Figure 3 is a perspective view of the hopper used in the present invention;

[0027] Figure 4 is Figure 3 an enlarged view of part A in

[0028] Figure 5 is Figure 3 an enlarged view of part B in

[0029] Figure 6 is Figure 5 an enlarged view of part C in

[0030] Figure 7 is a perspective view of the gear set used in the present invention;

[0031] Figure 8 is a structural schematic diagram of the gear set used in the present invention;

[0032] In the figure: 1. Machine body; 11. Electric slide rail; 12. Hopper; 121. Connecting pipe; 122. Powder spreading roller; 123. Screw; 13. U-shaped frame; 131. Print head; 132. Lead screw; 133. Servo motor; 134. Infusion pipe; 2. Rotating shaft; 21. Groove; 211. Suction port; 22. Driving motor; 23. Gear set; 231. Driving gear; 232. Driven gear; 24. Scraper; 241. Installation groove; 242. Slide plate; 243. Compression spring; 25. Group partition board; 251. Blocking groove; 252. Connecting spring; 253. Glass fiber rope; 26. Shell; 261. Air inlet channel; 262. Exhaust channel; 27. Sealing block; 271. U-shaped groove; 272. Non-woven fabric; 273. Round groove; 274. Push plate; 275. Air hole; 276. Slide block; 277. Spiral groove; 28. Rotating plate; 3. Powder feeding cylinder; 31. Hydraulic push rod; 32. Piston; 33. Powder bed. Specific implementation mode

[0033] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation modes.

[0034] As Figures 1 to 8 shown, a sand mold 3D printer according to the present invention includes:

[0035] A machine body 1, an electric slide rail 11 is installed on the inner wall of the machine body 1; two groups of the electric slide rails 11 are provided; a hopper 12 is slidably connected to the upper end of one group of the electric slide rails 11; a U-shaped frame 13 is slidably connected to the upper end of the other group of the electric slide rails 11; a connecting pipe 121 is installed at the upper end of the hopper 12; one end of the connecting pipe 121 away from the hopper 12 is communicated with a feeding mechanism; a powder spreading roller 122 is arranged on one side of the hopper 12; the powder spreading roller 122 is fixedly connected to the hopper 12;

[0036] A print head 131, a lead screw 132 is arranged below the U-shaped frame 13; the lead screw 132 is rotatably connected to the U-shaped frame 13; the print head 131 is in screw drive connection with the lead screw 132; the upper end of the print head 131 is in sliding contact with the U-shaped frame 13; an infusion pipe 134 is installed on one side of the print head 131; one end of the infusion pipe 134 away from the print head 131 is communicated with an external infusion mechanism; a servo motor 133 is installed on one side of the U-shaped frame 13; the output end of the servo motor 133 is fixedly connected to the lead screw 132;

[0037] The rotating shaft 2 is rotatably connected with a screw 123 in the hopper 12; a groove 21 is provided on the inner wall of the hopper 12; the rotating shaft 2 is rotatably connected in the groove 21; the rotating shaft 2 is in rotational contact with the upper end wall of the groove 21; the rotating shaft 2 is located below the screw 123; a driving motor 22 is fixedly installed on the inner wall of the hopper 12; the output end of the driving motor 22 is fixedly connected to the screw 123; the screw 123 and the rotating shaft 2 are connected by a belt transmission; there are two rotating shafts 2; the two rotating shafts 2 are connected by a gear set 23; an air intake port 211 is provided on the lower end surface of the groove 21; a closing module is installed in the air intake port 211;

[0038] A powder delivery cylinder 3, the cylinder bottom of which is fixedly connected with a hydraulic push rod 31; a piston 32 is provided at the upper end of the hydraulic push rod 31; the piston 32 is slidably and sealedly connected to the inner wall of the powder delivery cylinder 3; a powder bed 33 is placed at the upper end of the piston 32; a scraper 24 is fixedly connected to the bottom of the groove 21; the end of the scraper 24 away from the groove 21 is in sliding contact with the rotating shaft 2; the rotating shaft 2 is made of PU material; the scraper 24 is made of PTFE material;

[0039] An air suction module is installed on one side of the hopper 12 ; the air suction module is used to generate suction force on the air suction port 211 .

[0040] As an embodiment of the present invention, a mounting groove 241 is formed at one end of the scraper 24 close to the roller; a slide plate 242 is slidably connected in the mounting groove 241; the slide plate 242 is fixedly connected to the bottom of the mounting groove 241 by a compression spring 243;

[0041] The existing ceramsite sand needs to be mixed with the curing agent in a certain proportion in advance in the sand mixing system before printing, so that the ceramsite sand will quickly solidify and bond when encountering the resin adhesive during printing, while the area that does not encounter the resin adhesive remains loose; however, the stirring of the ceramsite sand in the sand mixing system will cause friction between the ceramsite sands and produce microparticles, micropowders and other extremely small particles. On the one hand, during printing, these extremely small particles have a large specific surface area, so they are easy to absorb more resin, inhibiting the expansion and flow of the resin, so that the ceramsite sands cannot form an effective connection, reducing the strength of the sand mold; on the other hand, the resin sprayed by the print head 131 will cause extremely small particles to be lifted up, so that the lifted extremely small particles stick to the edge of the nozzle under the action of the resin viscosity, which is easy to cause nozzle blockage, so that the staff needs to disassemble the machine for cleaning;

[0042] During operation, the user places the powder bed 33 into the powder feeding cylinder 3, such that the powder bed 33 is located above the piston 32. Then, the powder feeding cylinder 3 is pushed into the machine body 1, and the printer is started. At this time, the hydraulic push rod 31 pushes the piston 32 upward, causing the piston 32 to push the powder bed 33 to the upper port of the powder feeding cylinder 3. Subsequently, the electric slide rail 11 operates, causing the hopper 12 to move from one end of the powder feeding cylinder 3 to the other end. During the movement of the hopper 12, the external feeding mechanism continuously conveys ceramsite sand through the connecting pipe 121 into the hopper 12. At this time, the driving motor 22 operates, causing the driving motor 22 to drive the screw rod 123 to rotate, so that the screw rod 123 conveys the ceramsite sand fed into the hopper 12 to both ends of the hopper 12, making the ceramsite sand in the hopper 12 evenly discharged. The ceramsite sand conveyed by the screw rod 123 can flow downward to the rotating shaft 2, causing the ceramsite sand to contact the rotating shaft 2. Since the driving motor 22 drives the upper rotating shaft 2 to rotate through a belt, the rotating shaft 2 is in sliding contact with the scraping plate 24, generating friction between the scraping plate 24 and the rotating shaft 2, causing the surface of the rotating shaft 2 to carry positive charges. Since negative charges are generated by the mutual friction between the ceramsite sands, the extremely small particles will adhere to the surface of the rotating shaft 2 under the action of electrostatic adsorption, while the normal ceramsite sands will fall to the lower port of the hopper 12 under the action of their own gravity. Moreover, the distance between the rotating shaft 2 and the lower end surface of the groove 21 is less than the diameter of the ceramsite sand. As the rotating shaft 2 rotates downward, the rotating shaft 2 drives the extremely small particles adsorbed on its surface into the groove 21. At this time, the scraping plate 24 scrapes the extremely small particles on the surface of the rotating shaft 2, causing the scraping plate 24 to scrape off the extremely small particles. Similarly, the lower rotating shaft 2 will contact the ceramsite sand again, causing the rotating shaft 2 to perform electrostatic adsorption on the extremely small particles in the ceramsite sand. The two rotating shafts 2 are distributed on the opposite side walls of the hopper 12, enabling the two rotating shafts 2 to perform electrostatic adsorption on both sides of the ceramsite sand forming a waterfall, increasing the contact area between the rotating shaft 2 and the ceramsite sand waterfall, and improving the screening of the extremely small particles in the ceramsite sand waterfall by the rotating shaft 2. When the extremely small particles fall into the groove 21, the adsorption module operates, enabling the adsorption module to adsorb the extremely small particles in the groove 21, such that the extremely small particles can enter through the air suction port 211. The other end of the air suction port 211 is connected to a collection bag through a feeding pipe, causing the extremely small particles to flow into the collection bag through the air suction port 211 and the feeding pipe. When the ceramsite sand flows out from the lower port of the hopper 12 and falls onto the powder bed 33, the hopper 12 drives the sand spreading roller to level the ceramsite sand on the powder bed 33. When the hopper 12 reaches the other end of the powder feeding cylinder 3, the electric slide rail 11 and the servo motor 133 connected to the U-shaped frame 13 cooperate synchronously, and the printing head 131 is driven by the U-shaped frame 13 and the lead screw 132 to spray the resin binder on the area to be formed to adhere to the sand grains; finally, a three-dimensional sand mold entity is formed by layer-by-layer accumulation;The skateboard 242 is arranged such that it can be pressed against the rotating shaft 2 under the pushing force of the restoring force of the compression spring 243, enabling the skateboard 242 to always be in contact with the rotating shaft 2. On the one hand, it increases the frictional force between the skateboard 242 and the rotating shaft 2, increases the static charges on the surface of the rotating shaft 2, and improves the static adsorption effect of the rotating shaft 2. On the other hand, due to the friction between the skateboard 242 and the rotating shaft 2, the skateboard 242 is inevitably worn. However, the worn skateboard 242 can still be pressed against the rotating shaft 2 under the pushing force of the compression spring 243, thus improving the service life of the skateboard 242;

[0043] Through the cooperation between the rotating shaft 2 and the skateboard 242, static electricity adsorption is generated on the surface of the rotating shaft 2 due to friction. The rotating shaft 2 adsorbs extremely small particles through the static adsorption force on its surface, reducing the extremely small particles falling from the lower port of the hopper 12. On the one hand, it reduces the amount of resin adsorbed by the extremely small particles, improves the extensional fluidity of the resin, ensures effective connection between the ceramsite sands, and improves the strength of the sand mold. On the other hand, it reduces the number of extremely small particles raised by the resin ejected from the print head 131, reduces the amount of extremely small particles adhering to the edge of the nozzle, delays the time of nozzle blockage, and improves the service life of the nozzle.

[0044] As an embodiment of the present invention, the closing module includes a group partition 25; a blocking groove 251 is formed on the inner wall of the air suction port 211; the group partition 25 is slidably and sealingly connected in the blocking groove 251; the group partition 25 is fixedly connected to the bottom of the blocking groove 251 through a connecting spring 252; a fiberglass rope 253 is fixedly connected to the end of the blocking partition away from the connecting spring 252; the end of the fiberglass rope 253 away from the group partition 25 is connected to the air suction module.

[0045] As an embodiment of the present invention, the air suction module includes a housing 26; the housing 26 is installed at one end of the hopper 12 away from the driving motor 22; the gear set 23 includes a driving gear 231 and a driven gear 232; both the driving gear 231 and the driven gear 232 are slidably and sealingly connected to the inner wall of the housing 26; an air inlet channel 261 and an air outlet channel 262 are formed on the inner wall of the hopper 12; the air inlet channel 261 is located below the air outlet channel 262; one end of the air outlet channel 262 communicates with the housing 26, and the other end faces the rotating shaft 2; one end of the air inlet channel 261 communicates with the air suction port 211, and the other end communicates with the housing 26; a stretching unit is installed in the air inlet channel 261; the stretching unit is used to pull the fiberglass rope 253.

[0046] As an embodiment of the present invention, the stretching unit includes a sealing block 27; the sealing block 27 is slidably and sealingly connected in the air inlet passage 261; the sealing block 27 is fixedly connected to the inner wall of the air inlet passage 261 through a return spring; a U-shaped groove 271 is formed in the inner wall of the air inlet passage 261; a non-woven fabric 272 is fixedly connected to one end of the air inlet passage 261 close to the air suction port 211; the end of the glass fiber rope 253 far from the group partition plate 25 passes through the hopper 12 and is fixedly connected to the sealing block 27; the glass fiber rope 253 is slidably and sealingly connected to the hopper 12;

[0047] During operation, as the drive motor 22 drives the rotating shaft 2 to rotate, the two rotating shafts 2 are engaged and driven through the driving gear 231 and the driven gear 232. Since the driving gear 231 and the driven gear 232 are in sliding and sealing contact with the inner wall of the housing 26, the air inlet passage 261 and the exhaust passage 262 are separated by the driving gear 231 and the driven gear 232, and the driving gear 231, the driven gear 232 and the housing 26 form a Roots blower. During the process of the driving gear 231 and the driven gear 232 meshing and rotating in the housing 26, a certain amount of gas is surrounded by the driving gear 231 and the driven gear 232 and conveyed from one side of the air inlet passage 261 to one side of the exhaust passage 262. The gas converges at the port of the exhaust passage 262 and flows into the exhaust passage 262 and is sprayed towards the rotating shaft 2 through the exhaust passage 262. The gas sprayed from the exhaust passage 262 can blow the ceramsite sand waterfall flowing downward along the rotating shaft 2, so that the extremely small particles in the ceramsite sand waterfall can float towards the surface of the rotating shaft 2 under the blowing of the air flow, and the rotating shaft 2 electrostatically adsorbs the extremely small particles blown by the air flow, thereby reducing the residue of the extremely small particles in the ceramsite sand waterfall and preventing the extremely small particles from flowing out of the lower port of the hopper 12 along with the ceramsite sand waterfall. As the gas pressure near the port of the air inlet passage 261 continuously decreases, a negative pressure is generated in the air inlet passage 261, causing the negative pressure adsorption seal block 27 to slide in the air inlet passage 261. The seal block 27 can pull the group partition plate 25 towards the direction close to the air inlet passage 261 through the fiberglass rope 253, so that the blocking partition stretches and connects the spring 252 to extend out of the blocking groove 251; the group partition plate 25 blocks the air suction port 211. At this time, the seal block 27 crosses the U-shaped groove 271, so that the air inlet passage 261 is communicated with the air suction port 211 through the U-shaped groove 271, preventing the outside gas from entering through the air suction port 211. The air inlet passage 261 is only communicated with the groove 21 through the air suction port 211, so that the extremely small particles in the groove 21 are adsorbed under the negative pressure and enter the air suction port 211 to the port of the air inlet passage 261. Since there is a non-woven fabric 272 at the port of the air inlet passage 261, the non-woven fabric 272 can block the dust from entering the air inlet passage 261. Until the hopper 12 moves to the other end of the powder feeding cylinder 3, at this time the drive motor 22 stops, so that no negative pressure is generated in the air inlet passage 261. At this time, the group partition plate 25 enters the blocking groove 251 under the pulling force of the restoring force of the connecting spring 252, so that the air suction port 211 is opened to the outside. At this time, the group partition plate 25 pulls the seal block 27 to reset through the fiberglass rope 253. Because the fiberglass rope 253 is in sliding and sealing connection with the inner wall of the hopper 12, it prevents the outside gas from entering between the fiberglass rope 253 and the hopper 12. The extremely small particles accumulated due to the blocking of the non-woven fabric 272 will fall to the air suction port 211 under their own gravity and flow into the collection bag along the feeding pipe at one end of the air suction port 211;

[0048] Through the arrangement of the group partition plate 25, the group partition plate 25 can block the communication between the air suction port 211 and the outside, one end of the air inlet channel 261 is communicated with the air suction port 211, and the other end is communicated with the housing 26, so that the extremely small particles in the groove 21 can enter the air suction port 211 under negative pressure adsorption and are blocked by the non-woven fabric 272 and converge at the port of the air inlet channel 261, so that the extremely small particles will not enter the air inlet channel 261, avoiding the extremely small particles from flowing back into the hopper 12 through the exhaust channel 262; until the driving motor 22 stops rotating, at this time the group partition plate 25 resets and the air suction port 211 is opened, and the extremely small particles blocked by the non-woven fabric 272 will fall out through the air suction port 211 under the action of gravity, avoiding the extremely small particles from converging and blocking the air inlet channel 261, and also facilitating the user to collect the extremely small particles in the air suction port 211, effectively improving the practicability of the present invention.

[0049] As an embodiment of the present invention, a circular groove 273 is opened at one end of the sealing block 27 close to the air suction port 211; a push plate 274 is slidably and sealingly connected in the circular groove 273; air holes 275 communicated with the circular groove 273 are opened on the surface of the push plate 274; the push plate 274 is in sliding contact with the inner wall of the air inlet channel 261; a slider 276 is fixedly connected to the inner wall of the air inlet channel 261;

[0050] During operation, when the negative pressure adsorbs the sealing block 27 away from the non-woven fabric 272, the sealing block 27 drives the push plate 274 to slide. Until the push plate 274 moves to the slider 276, the push plate 274 is blocked by the slider 276 and continuously extends out of the circular groove 273 until the sealing block 27 crosses the U-shaped groove 271; when the connecting spring 252 pulls the group partition plate 25 to reset, the group partition plate 25 can pull the sealing block 27 close to the air suction port 211 through the glass fiber rope 253. At this time, the sealing block 27 drives the push plate 274 to first contact the non-woven fabric 272, so that the non-woven fabric 272 is shaken by the push of the push plate 274, and the extremely small particles adhered to the side of the non-woven fabric 272 close to the air suction port 211 are shaken off. At this time, the glass fiber rope 253 continues to pull the sealing block 27 to move. At this time, the push plate 274 enters the circular groove 273 under the action of the blocking force of the non-woven fabric 272, so that the push plate 274 squeezes the gas in the circular groove 273 and sprays it out through the air holes 275, so that the gas sprays towards the non-woven fabric 272 through the air holes 275, and the extremely small particles adhered to the side of the non-woven fabric 272 close to the air suction port 211 are blown off by the gas, thereby improving the cleanliness of the surface of the non-woven fabric 272 and ensuring the gas flow rate in the air inlet channel 261, effectively improving the actual application effect of the present invention.

[0051] As an embodiment of the present invention, a spiral groove 277 is opened on the inner wall of the circular groove 273; the push plate 274 is in spiral transmission connection with the spiral groove 277; one end of the air hole 275 close to the non-woven fabric 272 has a smaller diameter;

[0052] During operation, when the push plate 274 enters the circular groove 273 due to the obstruction of the non-woven fabric 272, the push plate 274 can rotate spirally along the spiral groove 277, causing the air holes 275 on the surface of the push plate 274 to rotate. As a result, the push plate 274 drives the air holes 275 to rotate and blow down the surface of the non-woven fabric 272, enabling the air flow to blow the surface of the non-woven fabric 272 in a rotating manner. This increases the area of the non-woven fabric 272's surface affected by the gas blowing. Additionally, the diameter of one end of the air hole 275 close to the non-woven fabric 272 is smaller at both ends of the air hole 275, enhancing the blowing force of the air hole 275 on the non-woven fabric 272. Consequently, the cleaning effect of the air flow on the non-woven fabric 272 is improved, effectively enhancing the practical application effect of the present invention.

[0053] As an embodiment of the present invention, a rotating plate 28 is provided at one end of the exhaust passage 262 away from the housing 26; the rotating plate 28 is rotatably connected to the inner wall of the exhaust passage 262 through a torsion spring;

[0054] During operation, in the initial state, the rotating plate 28 is located within the exhaust passage 262, blocking the exhaust passage 262 to prevent external dust from entering the housing 26 through the exhaust passage 262 and protecting the driving gear 231 and the driven gear 232 from wear. This not only extends the service life of the driving gear 231 and the driven gear 232 but also ensures the tight meshing between the driving gear 231 and the driven gear 232. When the gas in the housing 26 enters the exhaust passage 262, the gas will push the rotating plate 28 of the exhaust passage 262 to rotate away from the exhaust passage 262 against the torsion force of the torsion spring, causing the rotating plate 28 to extend out of the exhaust passage 262. At this time, the gas in the exhaust passage 262 is discharged. Since the rotating plate 28 is located within the exhaust passage 262, the diameter of one end of the exhaust passage 262 where the rotating plate 28 is installed is reduced, increasing the flow velocity of the gas ejected from the exhaust passage 262. As a result, the blowing effect of the air flow on the extremely small particles in the ceramsite sand is improved, effectively enhancing the practical application effect of the present invention.

[0055] The specific working process is as follows:

[0056] During operation, the user places the powder bed 33 into the powder feeding cylinder 3, such that the powder bed 33 is located above the piston 32. Then, the powder feeding cylinder 3 is pushed into the machine body 1, and the printer is started. At this time, the hydraulic push rod 31 pushes the piston 32 upward, causing the piston 32 to push the powder bed 33 to the upper port of the powder feeding cylinder 3. Subsequently, the electric slide rail 11 operates, causing the hopper 12 to move from one end of the powder feeding cylinder 3 to the other end. During the movement of the hopper 12, the external feeding mechanism continuously conveys ceramsite sand through the connecting pipe 121 into the hopper 12. And at this time, the drive motor 22 operates, causing the drive motor 22 to drive the screw rod 123 to rotate, such that the screw rod 123 conveys the ceramsite sand fed into the hopper 12 to both ends of the hopper 12, making the ceramsite sand in the hopper 12 discharge evenly. The ceramsite sand conveyed by the screw rod 123 can flow downward to the rotating shaft 2, causing the ceramsite sand to contact the rotating shaft 2. Since the drive motor 22 drives the upper rotating shaft 2 to rotate through a belt, the rotating shaft 2 is in sliding contact with the scraper 24, generating friction between the scraper 24 and the rotating shaft 2, making the surface of the rotating shaft 2 carry positive charges. Since negative charges are generated by the mutual friction between the ceramsite sands, the extremely small particles will adhere to the surface of the rotating shaft 2 under the action of electrostatic adsorption, while the normal ceramsite sands will fall to the lower port of the hopper 12 under the action of their own gravity. And the distance between the rotating shaft 2 and the lower end face of the groove 21 is less than the diameter of the ceramsite sand. As the rotating shaft 2 rotates downward, the rotating shaft 2 drives the extremely small particles adsorbed on its surface into the groove 21. At this time, the scraper 24 will scrape the extremely small particles on the surface of the rotating shaft 2, causing the scraper 24 to scrape off the extremely small particles. Similarly, the lower rotating shaft 2 will contact the ceramsite sand again, causing the rotating shaft 2 to perform electrostatic adsorption on the extremely small particles in the ceramsite sand. And the two rotating shafts 2 are distributed on the two opposite side walls of the hopper 12, enabling the two rotating shafts 2 to perform electrostatic adsorption on both sides of the ceramsite sand forming a waterfall, increasing the contact area between the rotating shaft 2 and the ceramsite sand waterfall, so as to improve the screening of the extremely small particles in the ceramsite sand waterfall by the rotating shaft 2. And when the extremely small particles fall into the groove 21, the adsorption module operates, enabling the adsorption module to adsorb the extremely small particles in the groove 21, such that the extremely small particles can enter through the air inlet 211. And the other end of the air inlet 211 is connected to the collection bag through a feeding pipe, causing the extremely small particles to flow into the collection bag through the air inlet 211 and the feeding pipe. When the ceramsite sand flows out from the lower port of the hopper 12 and falls onto the powder bed 33, the hopper 12 drives the sand spreading roller to level the ceramsite sand on the powder bed 33. When the hopper 12 reaches the other end of the powder feeding cylinder 3, the electric slide rail 11 and the servo motor 133 connected to the U-shaped frame 13 cooperate synchronously, and through the U-shaped frame 13 and the lead screw 132, the print head 131 sprays the resin binder on the area to be formed to stick the grits; finally, a three-dimensional sand mold entity is formed by layer-by-layer accumulation;The skateboard 242 is arranged such that it can be pressed against the rotating shaft 2 under the restoring force of the compression spring 243, enabling the skateboard 242 to always be in contact with the rotating shaft 2. On the one hand, the friction between the skateboard 242 and the rotating shaft 2 is increased to add static charges to the surface of the rotating shaft 2, improving the static adsorption effect of the rotating shaft 2. On the other hand, due to the friction between the skateboard 242 and the rotating shaft 2, the skateboard 242 is inevitably worn. However, the worn skateboard 242 can still be pressed against the rotating shaft 2 under the push of the compression spring 243, improving the service life of the skateboard 242;

[0057] Among them, as the driving motor 22 drives the rotating shaft 2 to rotate, the two rotating shafts 2 are meshed and driven through the driving gear 231 and the driven gear 232. Since the driving gear 231 and the driven gear 232 are in sliding and sealing contact with the inner wall of the housing 26, the air inlet passage 261 and the exhaust passage 262 are separated by the driving gear 231 and the driven gear 232, so that the driving gear 231, the driven gear 232 and the housing 26 form a Roots blower. During the process of the driving gear 231 and the driven gear 232 meshing and rotating in the housing 26, a certain amount of gas is surrounded by the driving gear 231 and the driven gear 232 and transported from one side of the air inlet passage 261 to one side of the exhaust passage 262, so that the gas converges at the port of the exhaust passage 262 and flows into the exhaust passage 262 and is sprayed towards the rotating shaft 2 through the exhaust passage 262. The gas sprayed from the exhaust passage 262 can blow the ceramsite sand waterfall flowing downward along the rotating shaft 2, so that the extremely small particles in the ceramsite sand waterfall can float towards the surface of the rotating shaft 2 under the blowing of the air flow, and the rotating shaft 2 electrostatically adsorbs the extremely small particles blown by the air flow, thereby reducing the residue of the extremely small particles in the ceramsite sand waterfall and preventing the extremely small particles from flowing out of the lower port of the hopper 12 along with the ceramsite sand waterfall. As the gas pressure near the port of the air inlet passage 261 continuously decreases, a negative pressure is generated in the air inlet passage 261, causing the negative pressure adsorption sealing block 27 to slide in the air inlet passage 261, so that the sealing block 27 can pull the group partition plate 25 towards the direction close to the air inlet passage 261 through the glass fiber rope 253, and the blocking partition plate stretches the connecting spring 252 and extends out of the blocking groove 251; the group partition plate 25 blocks the air suction port 211. At this time, the sealing block 27 crosses the U-shaped groove 271, so that the air inlet passage 261 is communicated with the air suction port 211 through the U-shaped groove 271, preventing the outside air from entering through the air suction port 211, and the air inlet passage 261 is only communicated with the groove 21 through the air suction port 211, so that the extremely small particles in the groove 21 are adsorbed under the negative pressure and enter the air suction port 211 to the port of the air inlet passage 261. Since there is a non-woven fabric 272 at the port of the air inlet passage 261, the non-woven fabric 272 can block the dust from entering the air inlet passage 261. Until the hopper 12 moves to the other end of the powder feeding cylinder 3, at this time the driving motor 22 stops, so that no negative pressure is generated in the air inlet passage 261. At this time, the group partition plate 25 enters the blocking groove 251 under the pulling force of the restoring force of the connecting spring 252, so that the air suction port 211 is opened to the outside. At this time, the group partition plate 25 pulls the sealing block 27 to reset through the glass fiber rope 253. Because the glass fiber rope 253 is in sliding and sealing connection with the inner wall of the hopper 12, it prevents the outside air from entering between the glass fiber rope 253 and the hopper 12, and the extremely small particles accumulated by being blocked by the non-woven fabric 272 will fall to the air suction port 211 under the action of their own gravity and flow into the collection bag along the feeding pipe at one end of the air suction port 211;When the negative pressure adsorption seal block 27 is away from the non-woven fabric 272, the seal block 27 drives the push plate 274 to slide. When the push plate 274 moves to the slider 276, the push plate 274 is blocked by the slider 276 and continuously extends out of the circular groove 273 until the seal block 27 crosses the U-shaped groove 271. When the connecting spring 252 pulls the group partition plate 25 to reset, the group partition plate 25 can pull the seal block 27 close to the air suction port 211 through the glass fiber rope 253. At this time, the seal block 27 drives the push plate 274 to contact the non-woven fabric 272 first, causing the non-woven fabric 272 to vibrate under the push of the push plate 274, so that the extremely small particles adhered to the side of the non-woven fabric 272 close to the air suction port 211 are shaken off. At this time, the glass fiber rope 253 continues to pull the seal block 27 to move. At this time, the push plate 274 enters the circular groove 273 under the blocking force of the non-woven fabric 272, so that the push plate 274 squeezes the gas in the circular groove 273 to be ejected through the air hole 275, and the gas is ejected through the air hole 275 to the non-woven fabric 272, so that the extremely small particles adhered to the side of the non-woven fabric 272 close to the air suction port 211 are separated from the non-woven fabric 272 under the blowing of the gas. When the push plate 274 enters the circular groove 273 due to the blocking of the non-woven fabric 272, the push plate 274 can rotate spirally along the spiral groove 277, so that the push plate 274 drives the air holes 275 on the surface to rotate, so that the push plate 274 drives the air holes 275 to rotate and blow down the surface of the non-woven fabric 272, so that the air flow can rotate and blow the surface of the non-woven fabric 272. In the initial state, the rotating plate 28 is located in the exhaust passage 262, so that the rotating plate 28 blocks the exhaust passage 262, preventing external dust from entering the housing 26 through the exhaust passage 262, preventing the dust from wearing the driving gear 231 and the driven gear 232, not only improving the service life of the driving gear 231 and the driven gear 232, but also ensuring the meshing tightness between the driving gear 231 and the driven gear 232. When the gas in the housing 26 enters the exhaust passage 262, the gas will push the rotating plate 28 in the exhaust passage 262 to rotate in the direction away from the exhaust passage 262 against the torsion of the torsion spring, so that the rotating plate 28 can extend out of the exhaust passage 262. At this time, the gas in the exhaust passage 262 is discharged, and because the rotating plate 28 is located in the exhaust passage 262, the diameter of the end of the exhaust passage 262 where the rotating plate 28 is installed is reduced, so that the flow velocity of the gas ejected from the exhaust passage 262 increases.;

[0058] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the attached Figure 1The orientation or positional relationship shown is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the protection scope of the present invention. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0059] The basic principles, main features, and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and all these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A sand mold 3D printer, Features: include: A machine body (1), wherein an electric slide rail (11) is installed on the inner wall of the machine body (1); the electric slide rail (11) is provided in two groups; the upper end of one group of the electric slide rails (11) is slidably connected to a hopper (12); the upper end of the other group of the electric slide rails (11) is slidably connected to a U-shaped frame (13); a connecting pipe (121) is installed on the upper end of the hopper (12); the end of the connecting pipe (121) away from the hopper (12) is connected to a feeding mechanism; a powder spreading roller (122) is provided on one side of the hopper (12); the powder spreading roller (122) is fixedly connected to the hopper (12); A print head (131), a screw rod (132) is provided below the U-shaped frame (13); the screw rod (132) is rotatably connected to the U-shaped frame (13); the print head (131) is spirally connected to the screw rod (132); the upper end of the print head (131) is in sliding contact with the U-shaped frame (13); an infusion tube (134) is installed on one side of the print head (131); the end of the infusion tube (134) away from the print head (131) is connected to an external infusion mechanism; a servo motor (133) is installed on one side of the U-shaped frame (13); the output end of the servo motor (133) is fixedly connected to the screw rod (132); A rotating shaft (2), a screw rod (123) is rotatably connected in the hopper (12); a groove (21) is provided on the inner wall of the hopper (12); the rotating shaft (2) is rotatably connected in the groove (21); the rotating shaft (2) is in rotational contact with the upper end wall of the groove (21); the rotating shaft (2) is located below the screw rod (123); a driving motor (22) is fixedly installed on the inner wall of the hopper (12); the output end of the driving motor (22) is fixedly connected to the screw rod (123); the screw rod (123) and the rotating shaft (2) are connected via a belt transmission; there are two rotating shafts (2); the two rotating shafts (2) are connected via a gear set (23); an air intake port (211) is provided on the lower end surface of the groove (21); a closing module is installed in the air intake port (211); A powder delivery cylinder (3), wherein a hydraulic push rod (31) is fixedly connected to the cylinder bottom of the powder delivery cylinder (3); a piston (32) is provided at the upper end of the hydraulic push rod (31); the piston (32) is slidably sealedly connected to the inner wall of the powder delivery cylinder (3); a powder bed (33) is placed at the upper end of the piston (32); a scraper (24) is fixedly connected to the groove bottom of the groove (21); the end of the scraper (24) away from the groove (21) is in sliding contact with the rotating shaft (2); the rotating shaft (2) is made of PU material; the scraper (24) is made of PTFE material; An air suction module is installed on one side of the hopper (12); the air suction module is used to generate suction force on the air suction port (211).

2. A sand mold 3D printer according to claim 1, Features: One end of the scraper (24) close to the roller is provided with an installation groove (241); a sliding plate (242) is slidably connected in the installation groove (241); the sliding plate (242) is fixedly connected to the bottom of the installation groove (241) through a compression spring (243).

3. A sand mold 3D printer according to claim 2, wherein: The closing module includes a group partition plate (25); a blocking groove (251) is formed in the inner wall of the air suction port (211); the group partition plate (25) is slidably and sealingly connected in the blocking groove (251); the group partition plate (25) is fixedly connected to the bottom of the blocking groove (251) through a connecting spring (252); a glass fiber rope (253) is fixedly connected to one end of the blocking partition plate away from the connecting spring (252); one end of the glass fiber rope (253) away from the group partition plate (25) is connected to the air suction module.

4. A sand mold 3D printer according to claim 3, wherein: The air suction module includes a housing (26); the housing (26) is installed at one end of the hopper (12) away from the drive motor (22); the gear set (23) includes a driving gear (231) and a driven gear (232); both the driving gear (231) and the driven gear (232) are slidably and sealingly connected to the inner wall of the housing (26); an air inlet channel (261) and an air exhaust channel (262) are formed in the inner wall of the hopper (12); the air inlet channel (261) is located below the air exhaust channel (262); one end of the air exhaust channel (262) communicates with the housing (26), and the other end faces the rotating shaft (2); one end of the air inlet channel (261) communicates with the air suction port (211), and the other end communicates with the housing (26); a stretching unit is installed in the air inlet channel (261); the stretching unit is used for pulling the glass fiber rope (253).

5. A sand mold 3D printer according to claim 4, wherein: The stretching unit includes a sealing block (27); the sealing block (27) is slidably and sealingly connected in the air inlet channel (261); a U-shaped groove (271) is formed in the inner wall of the air inlet channel (261); a non-woven fabric (272) is fixedly connected to one end of the air inlet channel (261) close to the air suction port (211); one end of the glass fiber rope (253) away from the group partition plate (25) passes through the hopper (12) and is fixedly connected to the sealing block (27); the glass fiber rope (253) is slidably and sealingly connected to the hopper (12).

6. A sand mold 3D printer according to claim 5, wherein: A circular groove (273) is formed in one end of the sealing block (27) close to the air suction port (211); a push plate (274) is slidably and sealingly connected in the circular groove (273); air holes (275) communicating with the circular groove (273) are formed on the surface of the push plate (274); the push plate (274) is in sliding contact with the inner wall of the air inlet channel (261); a sliding block (276) is fixedly connected to the inner wall of the air inlet channel (261).

7. A sand mold 3D printer according to claim 6, wherein: The inner wall of the circular groove (273) is provided with a spiral groove (277); the push plate (274) is in spiral drive connection with the spiral groove (277); one end of the air hole (275) close to the non-woven fabric (272) has a smaller diameter at both ends.

8. A sand mold 3D printer according to claim 7, characterized in that: A rotating plate (28) is provided at one end of the exhaust passage (262) away from the housing (26); the rotating plate (28) is rotatably connected to the inner wall of the exhaust passage (262) through a torsion spring.

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