Device for preparing 3D printing vertical orientation steel fiber reinforced cement-based composite material

Abstract

The invention discloses a device for preparing a 3D printing vertical orientation steel fiber reinforced cement-based composite material, the device comprises a storage bin, the storage bin is fixed on a moving arm frame of a 3D printer, the top surface of the storage bin is fixedly connected with a supporting disc through a connecting cylinder, and the top surface of the supporting disc is fixedly connected with a conveying pipe in a penetrating manner; the device further comprises an auxiliary running mechanism and an auxiliary discharging mechanism, the auxiliary running mechanism is arranged on the top face of the supporting disc and the top face of the storage bin, and the auxiliary running mechanism can dropwise add lubricating oil in a first cylinder to the meshing position of a first driving gear and a first driven gear through a dropper; and the auxiliary discharging mechanism can stir the cement-based mixture in the storage bin, so that the fluidity of the cement-based mixture is improved, the cement-based mixture is smoother in the subsequent extrusion process, and the blockage and irregularity phenomena in the printing process are reduced.

Description

Technical Field

[0001] The present invention relates to the field of 3D printing building materials, and in particular to a device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials. Background Art

[0002] 3D printing technology, also known as additive manufacturing technology, is a new type of rapid construction technology with the characteristics of high automation, high efficiency and low material cost. This technology is not only widely used in industrial design, medical, aerospace, manufacturing and other fields, but also brings new challenges and opportunities to the construction industry.

[0003] Domestic and foreign researchers generally use polyvinyl alcohol fiber, polyethylene fiber, glass fiber, steel fiber and other fibers to study 3D printed fiber-reinforced cement-based composites. In the existing architectural 3D printing technology, for 3D printed steel fiber reinforced cement-based composites, the steel fibers can only be distributed along the printing path, and cannot be distributed in the vertical direction perpendicular to the specimen plane. Therefore, when the 3D printed specimen is subjected to horizontal force, the steel fibers cannot fully play their due role.

[0004] In addition, in the Chinese patent with the patent publication number CN113547607A, a device for preparing 3D printed oriented steel fiber reinforced cement-based composite materials is disclosed, including a motor, a linkage gear set, a primary steel fiber orientation unit, a secondary steel fiber orientation unit, a feed hopper and an auxiliary vibrator; the linkage gear set includes a driving gear and a driven gear; the primary steel fiber orientation unit includes a steel fiber hopper, a propulsion stirring blade, a rotating vertical shaft, a propeller blade and a vertical rod; the feed hopper includes a storage bin, an extrusion tube and an extrusion port; the secondary steel fiber orientation unit is a cylindrical permanent magnet. This device realizes the directional distribution of steel fibers in the 3D printed steel fiber reinforced cement-based composite material along the printing direction, and the steel fibers are more evenly distributed, giving full play to the reinforcing effect of steel fibers, improving the smoothness of material extrusion during 3D printing of composite materials, the compactness of printed materials, and the protrusion of fibers on the surface of printed specimens. Technical problems such as, improve the structural mechanical properties of composite materials.

[0005] However, the following defects still exist in the specific use of the comparative documents: 1. As mentioned in the comparative document, the motor speed is controlled according to the working conditions by the numerical control unit, thereby controlling the speed of the driving gear and the driven gear. The driving gear and the driven gear in the comparative document are in an exposed environment. At this time, the gears are easily contaminated by external media such as dust and debris in the environment, and these impurities will accelerate the wear of the gears, thereby affecting the accuracy and performance of the gears, and will also have an adverse effect on the lubrication of the gear meshing surface, increase friction and wear, which will cause the tooth gap to gradually increase, resulting in unstable gear meshing, vibration and noise, and even equipment failure in severe cases, which will have an adverse effect on high-precision work such as 3D printing.

[0006] 2. The comparative document mentioned that the cement-based composite material mixture is continuously transported to the storage silo through the feed pipe by a pumping device, and the upper surface of the cement-based composite material mixture is located at 2 / 3 of the height of the storage silo. This will cause 1 / 3 of the space in the storage silo to be vacant, which will cause the propulsion blades to be unable to fully stir and propel the materials, resulting in reduced discharge efficiency. When there is less cement-based composite material mixture in the storage silo, the fluidity of the material will be affected when the propeller blades are used for discharge, resulting in problems such as poor transportation or blockage. Since the storage silo is not completely filled, the pumping device also needs to be started and stopped more frequently, which will affect the transportation efficiency and increase equipment wear.

[0007] Based on the above problems, the present invention proposes a device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials, which realizes the oriented distribution of steel fibers inside the 3D printed steel fiber reinforced cement-based composite materials in the vertical direction perpendicular to the plane of the specimen, fully exerts the reinforcing effect of the steel fibers, and under the condition of the same steel fiber dosage, compared with ordinary 3D printed oriented steel fiber reinforced cement-based composite materials, the direction of the steel fibers can be basically consistent with the vertical direction perpendicular to the plane of the specimen, and the distribution of the steel fibers is more reasonable. Summary of the invention

[0008] In view of this, the technical problem to be solved by the present invention is to propose a device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials to solve the problems that the existing 3D printed steel fiber reinforced cement-based composite materials can only realize the distribution of steel fibers along the printing path, but cannot realize the distribution of steel fibers along the vertical direction perpendicular to the specimen plane, and because the gears are in an exposed environment, they are easily contaminated by external media such as dust and debris in the environment, and 1 / 3 of the space in the storage bin is vacant.

[0009] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials, comprising: a storage bin, the storage bin is fixed on the mobile arm of the 3D printer, the top surface of the storage bin is fixedly connected to a support plate through a connecting cylinder, the top surface of the support plate is penetrated and fixedly connected to a feed pipe, the top surface of the support plate is rotatably connected to a driving gear 1, the outer surface of the driving gear 1 is meshed with a driven gear 1, and the driven gear 1 is rotatably connected to the top surface of the driving gear 1, and the top surface of the driving gear 1 is fixedly connected to Motor 1, the bottom surface of the driven gear 1 is fixedly connected with a first rotating shaft, and the first rotating shaft penetrates and is rotatably connected to the inside of the supporting disk, the outer surface of the bottom end of the storage bin is fixedly connected with motor 2, the bottom end of the motor 2 is fixedly connected with driving gear 2, the outer surface of the driving gear 2 is meshed with driven gear 2, the bottom end of the storage bin is provided with a discharge port, the outer surface of the discharge port is connected with an injection device, and also includes an auxiliary operation mechanism and an auxiliary discharge mechanism, the auxiliary operation mechanism is arranged on the top surface of the supporting disk, and the auxiliary operation mechanism is arranged on the top surface of the storage bin; The auxiliary operating mechanism is used to protect the driving gear 1 and the driven gear 1 and lubricate the driving gear 1 and the driven gear 1; The auxiliary discharging mechanism is used to stir the cement-based composite material in the top 1 / 3 area of ​​the storage bin.

[0010] As an improvement, the auxiliary operating mechanism includes an outer shell, which is fixedly connected to the top surface of the support plate and protects the driving gear 1, the driven gear 1 and the motor 1. The top surface of the inner wall of the outer shell is fixedly connected to a sliding groove body, the interior of the sliding groove body is slidably connected to a slide plate, and a spring is fixedly connected between the bottom surface of the slide plate and the bottom surface of the inner wall of the sliding groove body.

[0011] As an improvement, the top surface of the support plate is rotatably connected to a connecting column, and a belt is transmission-connected between the connecting column and the first rotating shaft, the top surface of the connecting column is fixedly connected to a rotating column, and an arc groove is provided on the outer surface of the rotating column.

[0012] As an improvement, the inner wall of the outer shell is fixedly connected to a first cylinder, and the first cylinder is located above the rotating column, the interior of the first cylinder is slidably connected to a piston plate, the bottom surface of the piston plate is fixedly connected to a first sliding column, the first sliding column penetrates and is slidably connected to the bottom surface of the first cylinder, a protrusion is provided on the outer surface of the bottom end of the first sliding column, and the protrusion slides in an arc groove opened by the rotating column.

[0013] As an improvement, the top surface of the piston plate is fixedly connected to a second sliding column, and the second sliding column is slidably connected to the top surface of the first cylinder, the top end of the second sliding column is fixedly connected to an auxiliary rod, the auxiliary rod is slidably connected to the inside of the sliding groove body, and the auxiliary rod is located above the slide plate, and the outer surface of the first cylinder is fixedly connected to a dropper.

[0014] As an improvement, the auxiliary discharging mechanism includes a gear ring, which is fixedly connected to the top surface of the storage bin, and the top surface of the gear ring is rotatably connected to a first rotating disk, and the bottom surface of the first rotating disk is eccentrically rotatably connected to an auxiliary gear, and the auxiliary gear is meshed with the inner ring of the gear ring, and the bottom surface of the auxiliary gear is fixedly connected to a stirring rod.

[0015] As an improvement, the top surface of the first rotating disk is rotatably connected to a ratchet, the bottom surface of the first rotating shaft is fixedly connected to a pawl, and the pawl is meshed with the ratchet, the bottom surface of the pawl is fixedly connected to a second rotating shaft, and the second rotating shaft passes through and is fixedly connected to the interior of the first rotating disk, the bottom surface of the second rotating shaft is fixedly connected to a primary propeller blade, and the bottom surface of the primary propeller blade is fixedly connected to a secondary propeller blade.

[0016] As an improvement, the top surface of the support plate is rotatably connected with an auxiliary cylinder, the ratchet and the auxiliary cylinder are transmission-connected with a belt, the top surface of the auxiliary cylinder is slidably connected with a slide body at an eccentric part, the top surface of the support plate is fixedly connected with an L-shaped cylinder, and a piston rod is provided on a side of the slide body close to the L-shaped cylinder, and the piston rod is slidably connected to the inside of the L-shaped cylinder.

[0017] As an improvement, the device further comprises a pumping device, and the storage bin is connected to the pumping device via a feed pipe.

[0018] As an improvement, the device also includes a numerical control unit, which is electrically connected to motor one, motor two, the incident device, the movable arm and the pumping device, respectively, to control the start and stop and rotation speed of motor one and motor two, the start and stop of the incident device, the moving speed and moving path of the movable arm and the pumping speed of the pumping device.

[0019] Compared with the prior art, the present invention provides a device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials, which has the following beneficial effects: 1. By moving the piston plate up and down inside the first cylinder, the lubricating oil in the first cylinder can be dripped onto the meshing point of the driving gear 1 and the driven gear 1 through a dropper. Since the gears in the comparative document are in an exposed environment, they are easily contaminated by external media such as dust and debris in the environment. By dripping lubricating oil, it is possible to effectively prevent the external media from sticking to the gears again, keep the gears clean, thereby ensuring the accuracy and reliability of the gear transmission. The lubricating oil can also reduce the friction and wear between the gears and extend the service life of the gears.

[0020] 2. By moving the auxiliary rod up and down, and a brush head is provided at the bottom end of the auxiliary rod, the lubricating oil dripped on the meshing place of the driving gear 1 and the driven gear 1 can be smeared up and down by the brush head. By smearing up and down by the brush head, it can be ensured that the lubricating oil is more evenly distributed on the meshing surface of the driving gear 1 and the driven gear 1, reducing local wear or overheating caused by uneven lubrication. While applying the lubricating oil, the brush head can also remove tiny particles or impurities attached to the surface of the driving gear 1 and the driven gear 1, thereby achieving a cleaning effect, thereby preventing these particles or impurities from affecting the meshing effect and life of the gears.

[0021] 3. The rotation of the first rotating disk can drive the stirring rod to eccentrically stir the cement-based mixture at the upper 1 / 3 of the inner part of the storage bin. The stirring can increase the fluidity of the cement-based mixture, making it smoother in the subsequent extrusion process and reducing blockages and irregularities in the printing process. The stirring action of the eccentric stirring shaft can more effectively discharge bubbles and voids in the material, thereby improving the density of the material and the quality of the printed specimen.

[0022] 4. The device can use the steel fiber launcher to shoot the steel fiber into the discharge port, change the direction of the discharge port and the injection device through the motor drive, and control the incident direction of the steel fiber to always be consistent with the printing forward direction, thereby realizing the vertical orientation of the steel fiber in the plane, ensuring that the steel fiber can be oriented in the vertical direction inside the 3D printed steel fiber reinforced cement-based composite material.

[0023] 5. The device is provided with a graded propulsion stirring blade. After the cement-based composite material enters the storage bin, it is first stirred and compacted by the primary shaft and the primary propeller blade, pushed into the extrusion tube, and then compacted for the second time by the secondary shaft and the secondary propeller blade, and finally pushed into the discharge port, so that the particles in the printed material and the particles and the steel fibers are closer, and the density of the extruded material is improved. Compared with ordinary 3D printed directional steel fiber reinforced cement-based composite materials, the 3D printed directional steel fiber reinforced cement-based composite materials prepared by this device have a 40~80% increase in bending toughness and a 40~60% increase in shear strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a three-dimensional side view of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the storage bin of the present invention; Figure 3 This is a schematic diagram of the internal structure of the housing of the present invention; Figure 4 This is a schematic diagram of the internal structure of the first cylinder of the present invention; Figure 5 This is a schematic diagram of the connection relationship structure of the slide plate of the present invention; Figure 6 This is a schematic diagram of the gear ring connection structure of the present invention; Figure 7 This is a schematic diagram of the ratchet connection structure of the present invention; Figure 8 This is a schematic diagram of the connection relationship structure of the chute body of the present invention; Fig. 9 This is a schematic diagram of a 3D printed vertically oriented steel fiber reinforced cement-based composite material mentioned in an embodiment of the present invention; Fig.10 This is a schematic diagram of the 3D printed random steel fiber reinforced cement-based composite material mentioned in an embodiment of the present invention.

[0025] In the figure: 1. Storage bin; 11. Driving gear 1; 12. Driven gear 1; 13. Motor 1; 14. First rotating shaft; 15. Feed pipe; 16. Motor 2; 17. Driving gear 2; 18. Driven gear 2; 19. Discharge port; 110. Support plate; 2. Auxiliary operating mechanism; 21. Housing; 22. Sliding trough; 23. Slide plate; 24. Spring; 25. Connecting column; 26. Rotating column; 27. First cylinder; 28. Piston plate; 29. ​​First sliding column; 210. Second sliding column; 211. Dropper; 212. Auxiliary rod; 3. Auxiliary discharging mechanism; 31. Gear ring; 32. First rotating disk; 33. Auxiliary gear; 34. Stirring rod; 35. Ratchet; 36. Ratchet; 37. Second rotating shaft; 38. First-stage propeller blade; 39. Second-stage propeller blade; 310. Auxiliary cylinder; 311. Slide chute body; 312. L-shaped cylinder. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The present invention is further described in detail below based on the accompanying drawings and embodiments.

[0028] Embodiment 1 Please refer to Figure 1 and Figures 3 to 5 As shown: In order to solve the problems mentioned in the technical solution, the embodiment of the present application provides a device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials, including: a storage bin 1, the storage bin 1 is fixed on the mobile arm of the 3D printer, the top surface of the storage bin 1 is fixedly connected to a support plate 110 through a connecting cylinder, the top surface of the support plate 110 is penetrated and fixedly connected to a feed pipe 15, the top surface of the support plate 110 is rotatably connected to a driving gear 11, the outer surface of the driving gear 11 is meshed with a driven gear 12, and the driven gear 12 is rotatably connected to the top surface of the driving gear 11, and the top surface of the driving gear 11 is fixedly connected to Motor 13, the bottom surface of driven gear 12 is fixedly connected with the first rotating shaft 14, and the first rotating shaft 14 penetrates and is rotatably connected to the inside of the support plate 110, the outer surface of the bottom end of the storage bin 1 is fixedly connected with motor 2 16, the bottom end of motor 2 16 is fixedly connected with driving gear 2 17, the outer surface of driving gear 2 17 is meshed with driven gear 2 18, the bottom end of the storage bin 1 is provided with a discharge port 19, the outer surface of the discharge port 19 is connected with an injection device, and also includes an auxiliary operation mechanism 2 and an auxiliary discharge mechanism 3, the auxiliary operation mechanism 2 is arranged on the top surface of the support plate 110, and the auxiliary operation mechanism 2 is arranged on the top surface of the storage bin 1; The auxiliary operating mechanism 2 is used to protect the driving gear 11 and the driven gear 12 and lubricate the driving gear 11 and the driven gear 12; The auxiliary operation mechanism 2 includes a housing 21, which is fixedly connected to the top surface of the support plate 110 and protects the driving gear 11, the driven gear 12 and the motor 13. The top surface of the inner wall of the housing 21 is fixedly connected to a sliding groove 22, and a slide plate 23 is slidably connected inside the sliding groove 22, and a spring 24 is fixedly connected between the bottom surface of the slide plate 23 and the bottom surface of the inner wall of the sliding groove 22. The top surface of the support plate 110 is rotatably connected to a connecting column 25, and a belt is connected between the connecting column 25 and the first rotating shaft 14. The top surface of the connecting column 25 is fixedly connected to a rotating column 26, and an arc groove is formed on the outer surface of the rotating column 26. The inner wall of the housing 21 is fixedly connected with a first cylinder 27, and the first cylinder 27 is located above the rotating column 26. The interior of the first cylinder 27 is slidably connected with a piston plate 28, and the bottom surface of the piston plate 28 is fixedly connected with a first sliding column 29. The first sliding column 29 penetrates and is slidably connected to the bottom surface of the first cylinder 27. A convex block is provided on the outer surface of the bottom end of the first sliding column 29, and the convex block slides in the arc groove provided in the rotating column 26. The top surface of the piston plate 28 is fixedly connected with a second sliding column 210, and the second sliding column 210 penetrates and is slidably connected to the top surface of the first cylinder 27. The top end of the second sliding column 210 is fixedly connected with an auxiliary rod 212, which is slidably connected to the inside of the sliding groove body 22 and is located above the slide plate 23. The outer surface of the first cylinder 27 is fixedly connected with a dropper 211. The device also includes a pumping device, and the storage bin 1 is connected to the pumping device through a feed pipe 15; The device also includes a numerical control unit, which is electrically connected to the motor 1 13, the motor 2 16, the injection device, the movable arm and the pumping device, respectively, to control the start and stop and rotation speed of the motor 1 13 and the motor 2 16, the start and stop of the injection device, the moving speed and moving path of the movable arm and the pumping speed of the pumping device; Wherein: the storage bin 1 is fixedly connected to the mobile arm of the 3D printer (not shown in the figure), an injection device is fixed on the outer surface of the discharge port 19 for injecting steel fibers, 3 to 6 holes are opened in parallel in the middle of the discharge port 19, the injection port of the injection device is aligned with the hole of the discharge port 19, a belt is connected between the connecting column 25 and the first rotating shaft 14, an arc groove is opened on the outer surface of the rotating column 26, a protrusion is provided on the outer surface of the bottom end of the first sliding column 29, and the protrusion slides in the arc groove opened by the rotating column 26, the first cylinder 27 remains in a sealed state, the first cylinder 27 can be externally connected to an automatic lubricating oil replenishing device, the dropper 211 is provided with a one-way valve, and the bottom end of the auxiliary rod 212 is provided with a brush head.

[0029] Compared with the comparative document, through the implementation of this embodiment, not only the outer shell 21 protects the exposed driving gear 11 and the driven gear 12 to prevent them from being contaminated by external media such as dust and debris in the environment, but also the piston plate 28 moves up and down to drip lubricating oil on the meshing point of the driving gear 11 and the driven gear 12, which can effectively prevent the external media from sticking to the gears again and keep the gears clean, thereby ensuring the accuracy and reliability of the gear transmission.

[0030] For further examples, please refer to Figure 2 and Figures 6 to 8 As shown: The auxiliary discharging mechanism 3 is used to stir the cement-based composite material in the top 1 / 3 area of ​​the storage bin 1; The auxiliary discharging mechanism 3 includes a gear ring 31, which is fixedly connected to the top surface of the storage bin 1, and the top surface of the gear ring 31 is rotatably connected to a first rotating disk 32, and the bottom surface of the first rotating disk 32 is rotatably connected to an auxiliary gear 33 at an eccentric position, and the auxiliary gear 33 is meshed with the inner ring of the gear ring 31, and the bottom surface of the auxiliary gear 33 is fixedly connected to a stirring rod 34; A ratchet 36 is rotatably connected to the top surface of the first rotating disk 32, a pawl 35 is fixedly connected to the bottom surface of the first rotating shaft 14, and the pawl 35 is meshed with the ratchet 36, a second rotating shaft 37 is fixedly connected to the bottom surface of the pawl 35, and the second rotating shaft 37 penetrates and is fixedly connected to the inside of the first rotating disk 32, a primary propeller blade 38 is fixedly connected to the bottom surface of the second rotating shaft 37, and a secondary propeller blade 39 is fixedly connected to the bottom surface of the primary propeller blade 38; The top surface of the support plate 110 is rotatably connected with an auxiliary cylinder 310, a belt is connected between the ratchet 36 and the auxiliary cylinder 310, a chute body 311 is slidably connected to the eccentric part of the top surface of the auxiliary cylinder 310, an L-shaped cylinder 312 is fixedly connected to the top surface of the support plate 110, and a piston rod is provided on a side of the chute body 311 close to the L-shaped cylinder 312, and the piston rod is slidably connected to the inside of the L-shaped cylinder 312; Wherein: the stirring rod 34 is located in the upper 1 / 3 area of ​​the storage bin 1, the pawl 35 is driven by the motor 13 to rotate forward and reversely, when the pawl 35 rotates forward, it cannot drive the ratchet 36 to rotate, when the pawl 35 rotates reversely, it drives the ratchet 36 to rotate, and the L-shaped cylinder 312 can be connected to an external water reducing agent adding device.

[0031] Compared with the comparative document, through the implementation of this embodiment, the rotation of the pawl 35 can drive the stirring rod 34 to eccentrically stir the cement-based composite material mixture in the upper 1 / 3 area of ​​the storage bin 1. Through stirring, the fluidity of the cement-based mixture can be increased, making it smoother in the subsequent extrusion process, reducing blockages and irregularities in the printing process, and more effectively expelling bubbles and voids in the material, thereby improving the density of the material and the quality of the printed specimens.

[0032] Embodiment 2 In this embodiment, the 3D printing device used is the device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials of the present invention: the central axis of the first-stage propeller blade 38 is collinear with the central axis of the second-stage propeller blade 39. The discharge port has a diameter of 30 mm, and there are 4 steel fiber holes with a diameter of 2 mm in the middle. The steel fiber is 25 mm long, 0.4 mm in diameter, and has a density of 7.8 g / mm 3 The water-cement ratio of the cement-based composite mixture is 0.41.

[0033] The preparation process is: (1) Pour the dry and wet materials into the mixing pot of the pumping device according to the weighed ratio and close the pumping valve to fully stir the dry and wet materials for 90 seconds. Weigh the required steel fibers according to the weighed ratio and place them into the injection device; (2) Set the rotational speed of Motor 1 to 150 r / min, the printing speed to 8 mm / s, the printing path to a "square" shape, and the pumping speed of the pumping device to 0.5 L / min through the numerical control unit; the numerical control unit automatically controls the start and stop of Motor 2 and the incident device according to the printing forward direction, and the rotational speed of Motor 2 is set to 60 r / min.

[0034] (3) Start the device for 3D printing; a total of 12 3D printed vertically oriented steel fiber reinforced cementitious composite specimens are printed, with every 3 specimens divided into 1 group, for a total of 4 groups.

[0035] After printing is completed, the printed specimens need to be left standing for 24 - 36 h before being moved. During the standing process, they need to be covered with a plastic film to prevent surface cracks caused by excessive moisture evaporation or too low temperature. Then, they are cured in a standard curing room for 28 days. After curing is completed, three-point bending tests and shear tests are respectively carried out on the 4 groups of specimens, and the test results are recorded.

[0036] Comparative Example 1 In this comparative example, the 3D printing device used is a conventional 3D printing device. The steel fiber has a length of 25 mm, a diameter of 0.4 mm, and a density of 7.8 g / mm 3 , the water-binder ratio of the cementitious composite mixture is 0.41, and the diameter of the extrusion outlet is 30 mm.

[0037] (1) Weigh and pour the dry and wet materials into the mixing pot according to the ratio and stir well for 60 s, then weigh and put the required steel fibers into the mixing pot according to the ratio and stir well with the cementitious composite mixture for 30 s; (2) Pour the stirred steel fiber reinforced cementitious composite into a conventional pumping device and connect it to the conventional 3D printing device used in this comparative example through a feeding pipe; (3) Set the motor rotational speed of the conventional 3D printing device to 150 r / min, the printing speed to 8 mm / s, the printing path to a "square" shape, and the pumping speed of the conventional pumping device used in this comparative example to 0.5 L / min; (4) Start the conventional 3D printing device for 3D printing. A total of 12 3D printed randomly oriented steel fiber reinforced cementitious composite specimens are printed, with every 3 specimens divided into 1 group, for a total of 4 groups.

[0038] After printing is completed, the printed specimens need to be left standing for 24 - 36 h before being moved. During the standing process, they need to be covered with a plastic film to prevent surface cracks caused by excessive moisture evaporation or too low temperature. Then, they are cured in a standard curing room for 28 days. After curing is completed, three-point bending tests and shear tests are respectively carried out on the 4 groups of specimens, and the test results are recorded.

[0039] The experimental results in Example 2 are compared with the experimental results in Comparative Example 1. The results show that, compared with the 3D printed random steel fiber reinforced cement-based composite material printed by a conventional 3D printing device, the 3D printed oriented steel fiber reinforced cement-based composite material printed by the device of the present invention has an average increase in bending toughness of 75% and an average increase in shear strength of 50%. As can be seen from the schematic diagram, the orientation of the steel fibers in the test piece printed by the device of the present invention ( Fig. 9 ) is significantly better than the specimens printed by conventional 3D printing devices ( Fig.10 ).

[0040] Everything in the above example works like this: In the initial state: the dry and wet materials are weighed according to the ratio and poured into the stirring pot of the pumping device, and the pumping valve is closed to fully stir the dry and wet materials for 90 seconds, the required steel fibers are weighed according to the ratio and put into the injection device, and the cover of the injection device is closed; the speed of the motor 13 is set to 150r / min, the printing speed is set to 8mm / s, the printing path is set to a "mouth" shape, and the pumping speed of the pumping device is set to 0.5L / min through the numerical control unit; the numerical control unit automatically controls the start and stop of the motor 2 16 and the injection device according to the printing direction, and the speed of the motor 2 16 is set to 60r / min.

[0041] The following is the working process of the auxiliary operating mechanism 2 protecting the driving gear 11 and the driven gear 12 and lubricating the driving gear 11 and the driven gear 12: When in use, the motor 13 is controlled by the numerical control unit, and then the motor 13 drives the active gear 11 to rotate, and the active gear 11 rotates to drive the driven gear 12 to rotate. Since the gears in the comparative document are in an exposed state, they are easily contaminated by external media such as dust and debris in the environment. In the present invention, the rotation of the driven gear 12 will drive the first rotating shaft 14 fixedly connected thereto to rotate, and a belt is connected between the first rotating shaft 14 and the connecting column 25, that is, the rotation of the first rotating shaft 14 drives the connecting column 25 to rotate, and the rotation of the connecting column 25 drives the rotating column 26 fixedly connected thereto to rotate. Since the outer surface of the rotating column 26 is provided with an arc groove, the outer surface of the bottom end of the first sliding column 29 is provided with a protrusion, and the protrusion slides in the arc groove provided by the rotating column 26, that is, the rotating column 2 6 rotates to drive the first slide post 29 to move up and down. Since the first slide post 29 is slidably connected to the inside of the first cylinder 27, and the top of the first slide post 29 is fixedly connected with the piston plate 28, that is, the piston plate 28 moves up and down inside the first cylinder 27, and the first cylinder 27 remains sealed. The first cylinder 27 can be externally connected with an automatic lubricating oil replenishing device, and the dropper 211 is provided with a one-way valve, and then the lubricating oil in the first cylinder 27 is dripped to the meshing part of the driving gear 11 and the driven gear 12 through the dropper 211 through the up and down movement of the piston plate 28. By dripping the lubricating oil, it can effectively prevent the external medium from sticking to the gear again, keep the gear clean, thereby ensuring the accuracy and reliability of the gear transmission, and the lubricating oil can also reduce the friction and wear between the gears, and extend the service life of the gears; At the same time, as the piston plate 28 moves up and down inside the first cylinder 27, the second sliding column 210 fixedly connected to the top of the piston plate 28 moves up and down, thereby driving the auxiliary rod 212 to move up and down together. Since the auxiliary rod 212 is slidably connected to the inside of the sliding groove body 22, and the auxiliary rod 212 can slide stably through the sliding groove body 22 to avoid deviation, since a brush head is provided at the bottom end of the auxiliary rod 212, that is, when the auxiliary rod 212 moves up and down, the brush head will apply the meshing part of the active gear 11 and the driven gear 12 up and down, and the up and down application of the brush head can ensure that the lubricating oil is more evenly distributed on the meshing surface of the active gear 11 and the driven gear 12, reducing local wear or overheating caused by uneven lubrication, and the brush head can also remove tiny particles or impurities attached to the surface of the active gear 11 and the driven gear 12 while applying the lubricating oil, thereby achieving a cleaning effect, thereby preventing these particles or impurities from affecting the meshing effect and life of the gears.

[0042] Please refer to the above working process Figure 1 and Figures 3 to 5 .

[0043] The following is the working process of the auxiliary discharging mechanism 3 stirring the cement-based composite material in the top 1 / 3 area of ​​the storage bin 1: During use, since the upper surface of the stirred cement-based composite material mixture is transported to 2 / 3 of the height of the storage bin 1 in the comparative document, there is still 1 / 3 of a gap in the storage bin 1 at this time, which makes it impossible for the propulsion blade to fully stir and propel the material, resulting in reduced discharge efficiency. However, in the present invention, when the device is running, the cement-based composite material mixture fills the entire storage bin 1, and the discharge port 19 is kept in continuous discharge. The storage bin 1 is continuously fed through the feed pipe 15. At this time, the numerical control unit controls the motor 13 to rotate forward, and then the motor 13 controls the first rotating shaft 14 to rotate. The rotation of the first rotating shaft 14 drives the pawl 35 fixedly connected thereto to rotate. Since the pawl 35 cannot drive the ratchet 36 to rotate when it rotates forward, the pawl 35 drives the ratchet 36 to rotate when it reverses, and it is in forward rotation at this time, that is, it cannot drive the ratchet 36 to rotate. Then the pawl 35 rotates to drive the second rotating shaft 37 fixedly connected thereto to rotate. The rotation of the driving shaft 37 drives the first rotating disk 32 fixedly connected thereto to rotate. Since the auxiliary gear 33 is rotatably connected to the eccentric portion of the first rotating disk 32 and meshes with the inner ring of the gear ring 31 fixedly connected to the top surface of the storage bin 1, the rotation of the first rotating disk 32 drives the auxiliary gear 33 to rotate, and drives the stirring rod 34 to perform eccentric stirring movement on the top of the storage bin 1. The fluidity of the cement-based mixture can be increased by stirring, making it smoother in the subsequent extrusion process, reducing blockages and irregularities in the printing process, and the stirring action of the eccentric stirring shaft can more effectively discharge bubbles and gaps in the material, thereby improving the density of the material and the quality of the printed specimen. Subsequently, the stirred cement-based mixture is continuously discharged through the rotation of the primary propeller blades 38 and the secondary propeller blades 39; During the 3D printing interval, since there is still cement-based mixture in the storage bin 1, the cement-based mixture will initially set or harden in the storage bin 1, thereby affecting its fluidity. When 3D printing is used again, the CNC unit controls the motor 13 to rotate counterclockwise. At this time, the pawl 35 can drive the ratchet 36 to rotate. Since a belt is connected between the ratchet 36 and the auxiliary cylinder 310, the rotation of the ratchet 36 drives the auxiliary cylinder 310 to rotate together, and the top surface of the auxiliary cylinder 310 is slidably connected with a slide trough body 311 at an eccentric position, and the slide trough body 311 is provided with a piston rod at one end close to the L-shaped cylinder 312 and is slidably connected to the inside of the L-shaped cylinder 312, that is, the rotation of the auxiliary cylinder 310 drives the piston The rod reciprocates inside the L-shaped cylinder 312, and the L-shaped cylinder 312 can be externally connected to an automatic water reducing agent replenishing device, that is, the water reducing agent can be added to the initial setting or hardening cement-based mixture through the rotation of the auxiliary cylinder 310, and eccentric stirring is performed through the stirring rod 34, and then discharged through the first-level propeller blade 38 and the second-level propeller blade 39. The eccentric stirring through the stirring rod 34 can better mix the water reducing agent with the initial setting or hardening cement-based mixture, ensuring that the water reducing agent can fully play its role. With the assistance of eccentric stirring, the water reducing agent can more effectively reduce the viscosity of the cement-based mixture, significantly enhance its fluidity, and thus improve the extrusion effect during 3D printing.

[0044] Please refer to the above working process Figure 2 and Figures 6 to 8 .

[0045] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials, comprising: A material storage bin (1), the material storage bin (1) being fixed on a movable arm of a 3D printer, the top surface of the material storage bin (1) being fixedly connected to a support disk (110) via a connecting cylinder, the top surface of the support disk (110) being penetrated and fixedly connected to a material delivery pipe (15), the top surface of the support disk (110) being rotatably connected to a driving gear (11), the outer surface of the driving gear (11) being meshed with a driven gear (12), and the driven gear (12) being rotatably connected to the top surface of the driving gear (11), the top surface of the driving gear (11) being fixedly connected to a motor (13), the bottom surface of the driven gear (12) being fixedly connected to a first rotating shaft (14), and the The first rotating shaft (14) passes through and is rotatably connected to the inside of the supporting plate (110); the outer surface of the bottom end of the storage bin (1) is fixedly connected to a second motor (16); the bottom end of the second motor (16) is fixedly connected to a second driving gear (17); the outer surface of the second driving gear (17) is meshed with a second driven gear (18); the bottom end of the storage bin (1) is provided with a discharge port (19); the outer surface of the discharge port (19) is connected to an injection device; the storage bin (1) is characterized in that it also includes an auxiliary operating mechanism (2) and an auxiliary discharging mechanism (3); the auxiliary operating mechanism (2) is arranged on the top surface of the supporting plate (110); and the auxiliary operating mechanism (2) is arranged on the top surface of the storage bin (1); The auxiliary operating mechanism (2) is used to protect the driving gear 1 (11) and the driven gear 1 (12) and to lubricate the driving gear 1 (11) and the driven gear 1 (12); The auxiliary discharging mechanism (3) is used to stir the cement-based composite material in the top 1 / 3 area of ​​the storage bin (1).

2. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 1, characterized in that: The auxiliary operation mechanism (2) comprises a housing (21), the housing (21) is fixedly connected to the top surface of the support plate (110), and protects a driving gear (11), a driven gear (12) and a motor (13) therein; a sliding groove (22) is fixedly connected to the top surface of the inner wall of the housing (21); a slide plate (23) is slidably connected inside the sliding groove (22), and a spring (24) is fixedly connected between the bottom surface of the slide plate (23) and the bottom surface of the inner wall of the sliding groove (22).

3. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 2, characterized in that: The top surface of the support plate (110) is rotatably connected to a connecting column (25), and a belt is transmission-connected between the connecting column (25) and the first rotating shaft (14). The top surface of the connecting column (25) is fixedly connected to a rotating column (26), and an arc-shaped groove is provided on the outer surface of the rotating column (26).

4. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 3, characterized in that: The inner wall of the shell (21) is fixedly connected with a first cylinder (27), and the first cylinder (27) is located above the rotating column (26). The interior of the first cylinder (27) is slidably connected with a piston plate (28), and the bottom surface of the piston plate (28) is fixedly connected with a first sliding column (29). The first sliding column (29) penetrates and is slidably connected to the bottom surface of the first cylinder (27). A protrusion is provided on the outer surface of the bottom end of the first sliding column (29), and the protrusion slides in an arc groove opened by the rotating column (26).

5. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 4, characterized in that: The top surface of the piston plate (28) is fixedly connected to a second sliding column (210), and the second sliding column (210) penetrates and is slidably connected to the top surface of the first cylinder (27); the top end of the second sliding column (210) is fixedly connected to an auxiliary rod (212), and the auxiliary rod (212) is slidably connected to the inside of the sliding groove body (22), and the auxiliary rod (212) is located above the slide plate (23); the outer surface of the first cylinder (27) is fixedly connected to a dropper (211).

6. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 1, characterized in that: The auxiliary discharging mechanism (3) comprises a gear ring (31), the gear ring (31) is fixedly connected to the top surface of the storage bin (1), the top surface of the gear ring (31) is rotatably connected to a first rotating disk (32), the bottom surface of the first rotating disk (32) is rotatably connected to an auxiliary gear (33) at an eccentric position, and the auxiliary gear (33) is meshed with the inner ring of the gear ring (31), and the bottom surface of the auxiliary gear (33) is fixedly connected to a stirring rod (34).

7. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 6, characterized in that: The top surface of the first rotating disk (32) is rotatably connected to a ratchet (36); the bottom surface of the first rotating shaft (14) is fixedly connected to a pawl (35), and the pawl (35) is meshed with the ratchet (36); the bottom surface of the pawl (35) is fixedly connected to a second rotating shaft (37), and the second rotating shaft (37) passes through and is fixedly connected to the inside of the first rotating disk (32); the bottom surface of the second rotating shaft (37) is fixedly connected to a primary propeller blade (38), and the bottom surface of the primary propeller blade (38) is fixedly connected to a secondary propeller blade (39).

8. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 7, characterized in that: The top surface of the support disk (110) is rotatably connected with an auxiliary cylinder (310), a belt is transmission-connected between the ratchet (36) and the auxiliary cylinder (310), a slide groove body (311) is slidably connected at an eccentric position of the top surface of the auxiliary cylinder (310), an L-shaped cylinder (312) is fixedly connected to the top surface of the support disk (110), and a piston rod is provided on a side of the slide groove body (311) close to the L-shaped cylinder (312), and the piston rod is slidably connected to the inside of the L-shaped cylinder (312).

9. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 1, characterized in that: The device also comprises a pumping device, and the storage bin (1) is connected to the pumping device via a material delivery pipe (15).

10. The device for preparing 3D printed vertically oriented steel fiber reinforced cement-based composite materials according to claim 1, characterized in that: The device also includes a numerical control unit, which is electrically connected to the motor one (13), the motor two (16), the injection device, the movable arm and the pumping device, respectively, to control the start and stop and rotation speed of the motor one (13) and the motor two (16), the start and stop of the injection device, the moving speed and moving path of the movable arm and the pumping speed of the pumping device.

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