In-situ nylon polymerization based jetting and bonding forming apparatus and method

Abstract

A jet bonding molding apparatus and method based on in-situ polymerized nylon is disclosed, using in-situ polymerized nylon as the resin matrix and glass fiber, carbon fiber, and nano-inorganic powder as reinforcements. The molding apparatus consists of a dispensing machine and a jet bonding printing device. The dispensing machine prepares the active material of the in-situ polymerized nylon and conveys it to the jet bonding printing device. The printing unit in the jet bonding printing device performs reciprocating linear motion, simultaneously completing the steps of powder spreading, compaction, spraying of active material, and pre-curing. One reciprocating motion completes the printing of one thickness unit. Subsequently, the molding platform descends, and polymerization is completed in the curing chamber. This method is compatible with various materials, has a high powder filling rate, fast printing speed, does not require expensive laser equipment, and is suitable for mass production.

Description

Technical Field

[0001] This invention belongs to the fields of composite material manufacturing and additive manufacturing technology. Background Technology

[0002] Traditional fiber-reinforced thermoplastic resin 3D printing (such as SLS and FDM) is limited by its printing method and resin system, resulting in low printing efficiency and low product infill rate (only 30%-50%). Chinese patent CN109897177A discloses a 3D printed part with a multi-scale three-dimensional thermally conductive network and its preparation method. It prepares graphene nanosheet-doped nylon 6-based composite granules through in-situ polymerization and then uses these granules to prepare filaments for FDM printing. However, this patented technology does not effectively utilize the low viscosity of in-situ polymerized nylon or optimize the printing mode suitable for the in-situ polymerized nylon system. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention aims to provide an in-situ polymerized nylon jet bonding molding device and method, which effectively utilizes the low viscosity characteristics of in-situ polymerized nylon to achieve high-speed printing, high filling rate, and the printed composite material products have excellent mechanical properties, and significantly improves the efficiency of jet bonding printing molding.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A spray bonding molding device based on in-situ polymerized nylon, characterized in that it includes a dispensing machine, a printing unit, a motion unit, and a curing unit. The dispensing machine is used to provide in-situ polymerized nylon molten material to the printing unit. The printing unit includes a powder spreading hopper, a powder spreading nozzle, a compaction roller, a molten material nozzle, and a photocuring module, arranged sequentially on a cylindrical guide rail. The compaction roller is located behind the powder spreading nozzle and connected to it to compact the spread powder. The powder spreading hopper is connected to the powder spreading nozzle through a pipe to provide powder to the nozzle. The molten material nozzle includes multiple rows of nozzles, with a distance of 0.15 mm between each nozzle. The motion unit includes a stepper motor and a chain to control the reciprocating movement of the printing unit above the molding platform. The curing unit includes a screw jack, a molding platform, and a molding hopper to heat and cure the molded product.

[0005] Optionally, the vertical distance between the powder spreading nozzle and the forming platform is 0.05-0.15mm.

[0006] Optionally, the compaction roller applies a pressure of 0.3-1.0 N / mm to the powder layer, has a vibration frequency of 50-200 Hz, a diameter of 20-30 mm, and a surface hardness of HRC55-60.

[0007] Optionally, the diameter of the molten material nozzle is 5-20 μm.

[0008] Optionally, the in-situ polymerized nylon active material raw material includes monomers, initiators, and activators. The monomers are one or more of caprolactam, undecylactam, and dodecalactam. The initiators are one or more of sodium metal, sodium hydroxide, sodium methoxide, and sodium caprolactam. The activators are one or more of toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

[0009] Optionally, the powder can be one or more of glass fiber, carbon fiber, and nano-inorganic powder, with a particle size range of 20-80μm, a Hall flow rate of less than 30s / 50g, and a water absorption rate of less than 0.1%.

[0010] Optionally, the reaction temperature control range of the dispensing machine is 110-130℃, the temperature of the dispensing pipe is 90-110℃, and the output flow rate of the dispensing pipe is 50-200 ml / min.

[0011] Optionally, during the spray bonding molding process, the nozzle of the molten material is automatically wiped or sucked up every 10-50 layers to prevent nozzle clogging, and the reciprocating linear motion speed of the printing unit is 50-200 mm / s.

[0012] Optionally, the temperature of the photocuring module (6) is 160-180℃, the pre-cured spray droplets are sprayed, the temperature of the molding chamber (8) is 160-180℃, the lifting speed of the molding platform (14) is 5-20mm / s, the temperature of the molten material nozzle (3) is 90-110℃, the nozzle spraying pressure is 0.3-1.2MPa, and the gap between the nozzle and the powder layer is 0.05-0.15mm.

[0013] Optionally, the in-situ polymerized nylon spray bonding molding device and technology includes the following steps: a. The powder used is preheated and dried in a drying oven at 60°C for 8 hours, and then placed into the powder spreading nozzle.

[0014] b. Add the raw materials into the dispensing machine to prepare in-situ polymerized nylon active material, and then convey it to the molten material nozzle through the conveying pipe.

[0015] c. The powder spreading nozzle, compaction roller, molten material nozzle, and photocuring module form an integrated printing unit. A stepper motor drives the printing unit to reciprocate linearly on a cylindrical guide rail at a speed of 50-200 mm / s via a chain. The powder spreading nozzle first evenly spreads a thin layer of powder in the first area of ​​the forming platform. The powder material can be solid powder such as glass fiber, carbon fiber, metal, ceramic, polymer, or sand particles. The compaction roller further compacts the powder layer with a vibration frequency of 50-200 Hz. Then, guided by the slicing model, the molten material nozzle selectively sprays mixed active material onto the powder layer to bond the powder particles in specific areas. Immediately afterwards, the photocuring module heats the active material droplets to 160-180℃ for pre-curing treatment. The compaction roller pushes excess solid powder to the powder hopper, and then the printing unit returns to the initial point, completing the printing of one unit thickness. The forming platform descends by one unit thickness, and the printing unit repeats the bonding and spraying process until the product is printed.

[0016] d. After printing, the product is polished and cleaned to obtain powder-reinforced in-situ polymerized nylon product.

[0017] This invention innovatively proposes a combination of reciprocating linear printing mode and in-situ polymerized nylon system, fully utilizing the low viscosity of the in-situ polymerized nylon system and the high printing efficiency of the reciprocating linear printing mode to produce high-fill-rate products. The reciprocating printing and adaptive slicing algorithm achieve a single-layer printing time of only 15-35 seconds, improving efficiency by 20%-40% compared to traditional fiber-reinforced thermoplastic resin 3D printing. Multiple products can be printed per unit time with controllable precision. Simultaneously, the in-situ polymerized nylon system has a viscosity of approximately 50 mPa·s, allowing for rapid and thorough penetration into high-content powder beds (such as glass fiber and carbon fiber), and rapid polymerization and curing within 5-10 seconds, further improving printing efficiency. The printed products have a dense internal structure with a porosity of <1%, a fill rate exceeding 80%, and tensile strength increased by more than 50%, significantly improving green strength.

[0018] This invention fully utilizes the advantages of both printing mode and resin system, fundamentally solving the problems of low printing efficiency and difficulty in balancing high filling and high strength in traditional fiber-reinforced thermoplastic resin 3D printing. It provides a new path for manufacturing high-performance and highly complex end parts, and greatly expands the application potential of jet bonding molding technology in aerospace, electronics and other fields.

[0019] Specifically, compared with the prior art, the in-situ polymerized nylon jet bonding molding 3D printing device and 3D printing method of the present invention have the following beneficial effects: (1) High printing efficiency: In the traditional linear jetting method, the forming surface is composed of straight lines during the jetting process, and the forming time is long. This invention innovatively sets the molten material nozzle as a multi-row nozzle and uses low viscosity in-situ polymerized nylon molten material, so that both powder and molten material are sprayed in a plane and the layer is sprayed instantly, which greatly improves the forming efficiency.

[0020] (2) The liquid caprolactam active material used in this invention has an extremely low viscosity of about 50 mPa·s and excellent fluidity, making it very suitable for high-speed reciprocating printing. This further enhances the efficiency advantage of this printing mode and avoids the problem of traditional polymer binders such as acrylic resin and epoxy resin limiting printing speed due to their high viscosity and easy clogging of the nozzle.

[0021] (3) High filling rate and superior performance: Thermoplastic resins usually have high viscosity, requiring longer impregnation time, which limits the improvement of printing efficiency. In addition, high viscosity resins are prone to insufficient bonding with solid powder fillers during impregnation, affecting the performance of the product. Existing nylon 3D printing (such as SLS, FDM) has a generally low filler content because high filler content will deteriorate melt rheology and laser sintering behavior. In contrast, the initial viscosity of in-situ polymerized nylon active material droplets is only 50 mPa·s, which can quickly penetrate into the pores of highly filled (such as glass fiber, carbon fiber, nano powder) powder beds. Its polymerization reaction does not depend on melt flow, thus completely breaking through the filler content limitation of traditional processes. The high filling rate achieved by this process brings significant advantages: it can directly manufacture high-strength, high-modulus lightweight structural parts, directly obtain a dense structure close to injection molding level (porosity <1%), and the tensile strength is more than 50% higher than that of other thermoplastic resin printed products; it significantly reduces material costs and reduces nylon polymerization shrinkage; the green strength is high, and it is expected to eliminate complex post-processing steps such as melt infiltration.

[0022] (4) Great potential for functionalization: In-situ polymerized nylon functionalization research is mature. According to the working scenario of the printed parts, corresponding additives can be added to the reactor to achieve functional modification. In this process, functional additives (such as antioxidants, flame retardants, conductive agents, dyes, etc.) can be pre-dispersed uniformly in low viscosity caprolactam monomers when preparing liquid active materials, so as to realize the bulk functionalization of the material at the same time as polymerization and molding, endowing the printed parts with flame retardant, antistatic, conductive and other properties, and expanding its application in aerospace, automotive, electronics and other fields. Attached Figure Description

[0023] Figure 1 This is a flow chart of the in-situ polymerization nylon spray bonding molding process. Figure 2 This is a schematic diagram of an in-situ polymerized nylon spray bonding molding device.

[0024] Figure 3 This is a top view schematic diagram of an in-situ polymerized nylon spray bonding molding device.

[0025] Figure 4 This is a partial schematic diagram of the printing unit.

[0026] Among them, 1-outer shell, 2-feeding pipe, 3-molten material nozzle, 4-powder spreading hopper, 5-connector, 6-photocuring module, 7-compacting roller, 8-forming hopper, 9-heating plate, 10-screw jack, 11-cylindrical guide rail, 12-chain, 13-stepper motor, 14-forming platform, 15-powder hopper, 16-linear bearing, 17-feeding port, 18-chain straight plate, 19-sprocket, 20-powder spreading nozzle. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] refer to Figure 1 This is a process flow diagram of the in-situ polymerized nylon spray bonding molding apparatus and method of the present invention.

[0029] refer to Figure 2-4 The present invention relates to a spray bonding molding device based on in-situ polymerized nylon, comprising a dispensing machine, a printing unit, a motion unit, and a curing unit. The dispensing machine is used to provide in-situ polymerized nylon molten material to the printing unit. The printing unit includes a powder spreading bin 4, a powder spreading nozzle 20, a compaction roller 7, a molten material nozzle 3, and a photocuring module 6, arranged sequentially on a cylindrical guide rail 11. The compaction roller 7 is located behind the powder spreading nozzle 20 and connected to it, used to compact the spread powder. The powder spreading bin 4 is connected to the powder spreading nozzle 20 through a pipe, providing powder to the powder spreading nozzle 20. The molten material nozzle 3 includes multiple rows of nozzles, with each nozzle spaced 0.15 mm apart. The motion unit includes a stepper motor 13 and a chain 12, controlling the reciprocating movement of the printing unit above the molding platform. The curing unit includes a screw jack 10, a molding platform 14, and a molding bin 8.

[0030] The reaction temperature control range of the dispensing machine is 110-130℃, the temperature of the conveying pipe 2 is 90-110℃, the output flow rate of the conveying pipe 2 is 50-200 ml / min, and the diameter of the molten material nozzle 3 is 5-20μm.

[0031] The vertical distance between the powder spreading nozzle 20 and the forming platform 14 is 0.05-0.15mm. The pressure of the compaction roller 7 on the powder layer is 0.3-1.0N / mm, the vibration frequency is 50-200Hz, the diameter of the compaction roller 7 is 20-30mm, and the surface hardness of the roller is HRC55-60. This helps to rearrange the powder and improve the density of the layer.

[0032] The photocuring module 6 has a temperature of 160-180℃, pre-curing spray droplets, a molding chamber 8 has a temperature of 160-180℃, a molding platform 14 has a lifting speed of 5-20mm / s, a molten material nozzle 3 has a temperature of 90-110℃, a nozzle spray pressure of 0.3-1.2MPa, and a nozzle-powder layer gap of 0.05-0.15mm.

[0033] The reciprocating linear motion speed of the printing unit is 50-200 mm / s.

[0034] The in-situ polymerized nylon active material raw material includes monomers, initiators, and activators. The monomers are one or more of caprolactam, undecanolactam, and dodecalactam. The initiators are one or more of sodium metal, sodium hydroxide, sodium methoxide, and sodium caprolactam. The activators are one or more of toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

[0035] The powder can be one or more of glass fiber, carbon fiber, and nano-inorganic powder, with a particle size range of 20-80μm, a Hall flow rate of less than 30s / 50g, and a water absorption rate of less than 0.1%.

[0036] The process of using the in-situ polymerized nylon spray bonding molding method of the present invention is as follows. a. The powder used is preheated and dried in a drying oven at 60°C for 8 hours, and then placed into the powder spreading nozzle.

[0037] b. Add the raw materials into the dispensing machine to prepare in-situ polymerized nylon active material, and then convey it to the molten material nozzle 3 through the material conveying pipe 2.

[0038] c. The powder spreading nozzle 20, compaction roller 7, molten material nozzle 3, and photocuring module 6 form an integrated printing unit. Stepper motor 13 drives the printing unit to reciprocate linearly on cylindrical guide rail 11 via chain 12 at a speed of 50-200 mm / s. The powder spreading nozzle 20 first evenly spreads a thin layer of powder in the first area on the forming platform 14. The powder material can be solid powder such as glass fiber, carbon fiber, metal, ceramic, polymer, or sand particles. The compaction roller 7 further compacts the powder layer with a vibration frequency of 50-200 Hz. Then, according to the guidance of the slicing model, the molten material nozzle 3 selectively sprays mixed active material on the powder layer to bond the powder particles in specific areas. Immediately afterwards, the photocuring module 6 heats the active material droplets to 160-180℃ for pre-curing treatment. The compaction roller 7 pushes the excess solid powder to the powder hopper 15. Then the printing unit returns to the initial point, and the printing of one unit thickness is completed. The forming platform 14 descends by one unit thickness, and the printing unit repeats the bonding and spraying process until the product printing is completed.

[0039] d. After printing, the product is polished and cleaned to obtain powder-reinforced in-situ polymerized nylon product.

[0040] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Implementation Example 1 The in-situ polymerized nylon spray bonding molding method of the present invention includes the following parameters: (1) The equipment is preheated to the specified temperature: the temperature of the dispensing machine reactor is 110℃, the temperature of the conveying pipe 2 is 90℃, the temperature of the molten material nozzle 3 is 90℃, the temperature of the photocuring module 6 is 160℃, and the temperature of the molding chamber 8 is 160℃.

[0042] (2) The output flow rate of the conveying pipe 2 is 50 ml / min, the nozzle diameter of the molten material nozzle 3 is 5 μm, the spraying pressure is 0.3 MPa, the gap between the powder spreading nozzle 20 and the powder layer is 0.05 mm, the compaction roller 7 has a roller diameter of 20 mm, the pressure is 0.3 N / mm, and the vibration frequency is 50 Hz.

[0043] (4) The reciprocating linear motion speed of the printing unit is 50 mm / s, and the lifting speed of the forming platform 14 is 5 mm / s.

[0044] (5) The printed products can be used after polishing and cleaning. After testing, the tensile strength and modulus are 649.8MPa and 48.3GPa, and the flexural strength and modulus are 378.4MPa and 40.2GPa. Compared with the materials prepared by fused deposition modeling of traditional continuous fiber reinforced nylon prepreg filament, the tensile strength and flexural strength are increased by 30% and 50%, respectively.

[0045] Implementation Example 2 The in-situ polymerized nylon spray bonding molding method of the present invention includes the following parameters: (1) The equipment is preheated to the specified temperature: the temperature of the dispensing machine reactor is 120℃, the temperature of the conveying pipe 2 is 100℃, the temperature of the molten material nozzle 3 is 100℃, the temperature of the photocuring module 6 is 170℃, and the temperature of the molding chamber 8 is 170℃.

[0046] (2) The output flow rate of the conveying pipe 2 is 125 ml / min, the nozzle diameter of the molten material nozzle 3 is 12 μm, the spraying pressure is 0.7 MPa, the gap between the powder spreading nozzle 20 and the powder layer is 0.05 mm, the compaction roller 7 has a roller diameter of 25 mm, the pressure is 0.8 N / mm, and the vibration frequency is 125 Hz.

[0047] (4) The reciprocating linear motion speed of the printing unit is 130 mm / s, and the lifting speed of the forming platform 14 is 15 mm / s.

[0048] (5) The printed products can be used after polishing and cleaning. After testing, the tensile strength and modulus are 624.8MPa and 46.44GPa, and the flexural strength and modulus are 353.18MPa and 37.52GPa. Compared with the materials prepared by fused deposition modeling of traditional continuous fiber reinforced nylon prepreg filament, the tensile strength and flexural strength are increased by 25% and 40%, respectively.

[0049] Implementation Example 3 The in-situ polymerized nylon spray bonding molding method of the present invention includes the following parameters: (1) The equipment is preheated to the specified temperature: the temperature of the dispensing machine reactor is 130℃, the temperature of the conveying pipe 2 is 110℃, the temperature of the molten material nozzle 3 is 110℃, the temperature of the photocuring module 6 is 180℃, and the temperature of the molding chamber 8 is 180℃.

[0050] (2) The output flow rate of the conveying pipe 2 is 200 ml / min, the nozzle diameter of the molten material nozzle 3 is 20 μm, the spraying pressure is 1.2 MPa, the gap between the powder spreading nozzle 20 and the powder layer is 0.05 mm, the compaction roller 7 has a roller diameter of 30 mm, the pressure is 1.2 N / mm, and the vibration frequency is 200 Hz.

[0051] (4) The reciprocating linear motion speed of the printing unit is 200 mm / s, and the lifting speed of the forming platform 14 is 20 mm / s.

[0052] (5) The printed products can be used after polishing and cleaning. After testing, the tensile strength and modulus are 601.8MPa and 41.3GPa, and the flexural strength and modulus are 320.4MPa and 32.2GPa. Compared with the traditional continuous fiber reinforced nylon prepreg fused deposition printing, the tensile strength and flexural strength of the materials are increased by 20% and 30%, respectively.

Claims

1. A spray bonding molding device based on in-situ polymerized nylon, characterized in that: The system includes a dispensing machine, a printing unit, a motion unit, and a curing unit. The dispensing machine is used to provide in-situ polymerized nylon molten material to the printing unit. The printing unit includes a powder spreading hopper (4), a powder spreading nozzle (20), a compaction roller (7), a molten material nozzle (3), and a photocuring module (6), which are arranged sequentially on a cylindrical guide rail (11). The compaction roller (7) is located behind the powder spreading nozzle (20) and is connected to the powder spreading nozzle (20) to compact the spread powder. The powder spreading hopper (4) is connected to the powder spreading nozzle (20) through a pipe to provide powder to the powder spreading nozzle (20). The molten material nozzle (3) includes multiple rows of nozzles, with each nozzle spaced 0.15 mm apart. The motion unit includes a stepper motor (13) and a chain (12) to control the printing unit to move back and forth above the molding platform. The curing unit includes a screw jack (10), a molding platform (14), and a molding hopper (8) to heat and cure the molded product.

2. The spray bonding molding apparatus based on in-situ polymerized nylon according to claim 1, characterized in that, The vertical distance between the powder spray nozzle (20) and the molding platform (14) is 0.05-0.15mm.

3. The spray bonding molding apparatus based on in-situ polymerized nylon according to claim 1, characterized in that, The pressure of the compaction roller (7) on the powder layer is 0.3-1.0 N / mm, the vibration frequency is 50-200 Hz, the diameter of the compaction roller (7) is 20-30 mm, and the surface hardness of the roller is HRC55-60.

4. The spray bonding molding apparatus based on in-situ polymerized nylon according to claim 1, characterized in that, The diameter of the molten material nozzle (3) is 5-20 μm.

5. A molding method using the spray bonding molding apparatus based on in-situ polymerized nylon as described in any one of claims 1-3, characterized in that... Includes the following steps: a. Add the in-situ polymerized nylon active material to the dispensing machine for mixing to prepare the in-situ polymerized nylon active material required for spray bonding molding. At the same time, preheat the spray bonding molding device to the specified temperature: the temperature of the molten material nozzle (3) is 90-110℃, the temperature of the photocuring module (6) is 160-180℃, and the temperature of the molding chamber (8) is 160-180℃. b. The dispensing machine delivers the active material through the conveying pipe (2) to the molten material nozzle (3) at a rate of 50-200 ml / min to prepare for printing; c. The stepper motor (13) controls the printing unit to make reciprocating linear motion on the cylindrical guide rail (11) through the chain (12). The powder spraying nozzle (20) sprays a 0.05mm thick powder layer on the surface of the forming platform. The compaction roller (7) pushes the excess powder to the powder chamber (15). The molten material nozzle (3) sprays active material droplets on the designated area of ​​the powder bed according to the slicing software model. Then the photocuring module (6) preheats and cures the droplets. Then the entire printing unit returns to the initial position. The printing of one unit thickness is completed. The screw jack (10) controls the forming platform (14) to descend by one thickness unit. The fully impregnated powder and in-situ polymerized nylon active material are polymerized and cured in the forming chamber (8) at 160-180℃. The above operation process is repeated until the product printing is completed. After printing, the product is polished and cleaned to obtain powder-reinforced in-situ polymerized nylon product.

6. The spray bonding molding method based on in-situ polymerized nylon according to claim 5, characterized in that, The in-situ polymerized nylon active material raw material includes monomers, initiators, and activators. The monomers are one or more of caprolactam, undecanolactam, and dodecalactam. The initiators are one or more of sodium metal, sodium hydroxide, sodium methoxide, and sodium caprolactam. The activators are one or more of toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

7. The spray bonding molding method based on in-situ polymerized nylon according to claim 5, characterized in that, The powder can be one or more of glass fiber, carbon fiber, and nano-inorganic powder, with a particle size range of 20-80μm, a Hall flow rate of less than 30s / 50g, and a water absorption rate of less than 0.1%.

8. The spray bonding molding method based on in-situ polymerized nylon according to claim 5, characterized in that, The reaction temperature control range of the dispensing machine is 110-130℃, the temperature of the conveying pipe (2) is 90-110℃, and the output flow rate range of the conveying pipe (2) is 50-200 ml / min.

9. The spray bonding molding method based on in-situ polymerized nylon according to claim 5, characterized in that, The automatic wiping or suction of the molten material nozzle is performed every 10-50 layers to prevent nozzle clogging. The reciprocating linear motion speed of the printing unit is 50-200 mm / s.

10. The spray bonding molding method based on in-situ polymerized nylon according to claim 5, characterized in that, The temperature of the photocuring module (6) is 160-180℃, the pre-cured spray droplets are sprayed, the temperature of the molding chamber (8) is 160-180℃, the lifting speed of the molding platform (14) is 5-20mm / s, the temperature of the molten material nozzle (3) is 90-110℃, the nozzle spraying pressure is 0.3-1.2MPa, and the gap between the nozzle and the powder layer is 0.05-0.15mm.

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