A 3D printing device and method based on photosensitive resin concrete curb

Abstract

The application relates to a 3D printing device and method based on a photosensitive resin concrete curb, and belongs to the field of building 3D printing. The device comprises a discharge port, a smoothing device coaxially arranged outside the discharge port, and the smoothing device and the discharge port can freely rotate. The bottom of the smoothing device is provided with an inverted U-shaped forming inner channel, the top and the side wall of the forming inner channel are transparent walls, and ultraviolet lamps are arranged in the top and the side wall of the forming inner channel, which are used for irradiating photosensitive resin concrete mixture constrained and shaped by the forming inner channel, so that the photosensitive resin concrete mixture completes preliminary shaping of the shape through a photo-crosslinking reaction before obvious gravity collapse or lateral bulging deformation occurs. The application combines follow-up constraint forming and ultraviolet / near-ultraviolet curing, aims to realize mold-free forming, reduce the collapse deformation tendency and surface step-shaped defects of the mixture after extrusion, and further prepare a composite curb with certain surface flatness and durability.

Description

Technical Field

[0001] This invention relates to a 3D printing device and method for photosensitive resin concrete curbstone, which is particularly suitable for moldless rapid prototyping of high-durability municipal curbstone, and belongs to the field of architectural 3D printing technology. Background Technology

[0002] Curbstones, commonly used boundary stones in municipal roads and traffic engineering, primarily serve functions such as guiding traffic, protecting road edges, and assisting drainage. Current curbstone manufacturing processes typically employ precast cement-based concrete assembly or on-site formwork casting. These processes are highly dependent on molds, leading to problems such as high mold turnover costs, insufficient construction flexibility, and long maintenance cycles when dealing with irregular road sections, localized repairs, or small-batch custom components. Furthermore, in cold regions or road environments with frequent use of de-icing agents, traditional cement-based curbstones are susceptible to chloride erosion and freeze-thaw cycles, resulting in surface peeling, powdering, cracking, and edge damage, affecting component service life and road boundary integrity. Therefore, how to rapidly manufacture curbstone components with high early strength, good surface quality, and good salt-freezing resistance under mold-free or minimal mold conditions is one of the problems that needs to be solved in the field of municipal road component manufacturing.

[0003] Resin-based concrete possesses advantages such as rapid curing, high early strength, relatively low water absorption, and good resistance to chemical attack, making it a promising candidate for manufacturing high-durability road components. However, traditional resin-based concrete components typically rely on fixed molds for casting or prefabrication, which is insufficient to meet the flexible manufacturing needs of complex linear curbs, irregularly shaped components, or rapid on-site repairs. Introducing extrusion-based 3D printing technology into the resin-based concrete component manufacturing process is expected to reduce mold dependence and increase the freedom of component geometry design. However, resin-based composite mixtures still face challenges in printability, molding stability, and interlayer quality control during extrusion, stacking, and curing.

[0004] Existing extrusion-based 3D printing for construction typically requires materials to have sufficient flowability during the pumping and nozzle extrusion stages, while also needing to quickly establish shape retention after leaving the nozzle to withstand their own weight and the pressure of the upper layers. For cement-based or conventional resin-based 3D printing materials, achieving these rheological requirements is challenging: excessively thin materials are prone to collapse, spreading, and lateral bulging; excessively thick materials can lead to increased pumping resistance, discontinuous discharge, or insufficient interlayer bonding. Furthermore, the boundaries of the stacked material strips often create interlayer steps, ripples, or grooves on the sides of the component. For components like curb stones that are constantly exposed to rainwater, dirt, de-icing agents, and freeze-thaw cycles, side grooves and interlayer defects can easily become pathways for moisture and chloride salt retention and infiltration, increasing the risk of frost heave and interlayer damage.

[0005] To improve the surface morphology of 3D printed components, existing technologies employ structures such as scrapers, rollers, smoothing baffles, or forming baffles to level or limit the extruded material strip. However, most of these structures perform external contact trimming of the deposited material strip after extrusion, and their action tends to manifest as localized scraping, pushing, or concentrated shearing. When the freshly extruded fluidized material has not yet established sufficient structural strength, external smoothing may cause lateral displacement, bulging, cross-sectional dimension fluctuations, or disturbance of the underlying structure. Especially when printing along continuous curves or complex paths, fixed smoothing baffles or actively adjustable smoothing mechanisms may also face problems such as path adaptability, equipment interference, and insufficient forming continuity. Therefore, existing technologies still need to further achieve synergy between extrusion, constrained shaping, surface smoothing, and rapid shaping.

[0006] On the other hand, ultraviolet or near-ultraviolet light curing technology has advantages such as fast curing speed and high molding precision, and has been used in the additive manufacturing of some photosensitive resin materials. However, in resin concrete systems with high aggregate content, conventional natural sand, stone powder, or other opaque aggregates can block the curing light, causing the light to be mainly concentrated on the surface layer of the material, making it difficult for the deeper resin to fully receive effective light and complete the cross-linking reaction. For components such as curbs with large cross-sectional dimensions and high service performance requirements, relying solely on surface light curing is insufficient to ensure overall curing uniformity and early load-bearing capacity. Therefore, how to increase the effective depth of curing light in aggregate-containing resin concrete and coordinate it with subsequent deep curing mechanisms is another key issue that needs to be addressed when applying light curing technology to the 3D printing of large-volume resin-based road components.

[0007] In summary, while existing technologies involve extrusion 3D printing, photosensitive resin curing, and post-printing smoothing, they still struggle to simultaneously meet the comprehensive requirements of high-performance curbstone components for mold-free forming, surface smoothness, stacking stability, deep curing uniformity, early strength, and salt-frost resistance. Therefore, it is necessary to propose a collaborative forming scheme for materials, equipment, and processes for photosensitive resin concrete curbstones, which can balance constrained smoothing, rapid preliminary shaping, deep assisted curing, and solid waste resource utilization during continuous printing. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a 3D printing device and method for photosensitive resin concrete curb stones, which combines motion-constrained molding with ultraviolet / near-ultraviolet curing. The aim is to improve the hardware structure and adjust the composite material system to achieve mold-free molding while reducing the tendency of the mixture to collapse and deform after extrusion and the surface step defects, thereby producing composite curb stones with certain surface smoothness and durability.

[0009] The technical solution of the present invention is as follows: A 3D printing device based on photosensitive resin concrete curbstone includes a discharge port, and a smoothing device is coaxially arranged outside the discharge port; the smoothing device and the discharge port can rotate freely. The smoothing device has an inverted U-shaped molding inner channel at its bottom (the whole is rectangular but open at the bottom). The bottom of the discharge port is located inside the molding inner channel (the bottom of the discharge port is located at the upper feeding end of the molding inner channel, or extends a certain distance into the upper part of the molding inner channel). This allows the fluidized photosensitive resin concrete to enter the molding inner channel first for top and lateral constraint. The top and side walls of the molding inner channel are transparent. Ultraviolet lamps are installed inside the top and side walls of the molding inner channel to irradiate the photosensitive resin concrete mixture constrained and shaped by the molding inner channel. This allows the photosensitive resin concrete mixture to complete the initial shaping of its form through photocrosslinking reaction before significant gravity collapse or lateral bulging deformation occurs.

[0010] The fluidized photosensitive resin concrete extruded from the outlet first enters the molding inner channel, where it is constrained by the top surface and laterally, thus completing the transition from a circular discharge section to a rectangular molding section. Subsequently, the material is simultaneously smoothed within the molding inner channel and irradiated by top and lateral curing light sources, finally exiting from the lower outlet of the molding inner channel and stacked into shape.

[0011] Preferably, the photosensitive resin concrete mixture comprises, by weight, 15-25 parts photosensitive resin, 0.2-1.0 parts photoinitiator, 0.1-0.8 parts thermal latent initiator, and 75-85 parts high-transmittance glass fragments. Depending on the material rheology, gradation density, and cost control requirements, one or more of the following may be selectively added: opaque auxiliary aggregates, inorganic fillers, thickeners, coupling agents, defoamers, or rheology modifiers.

[0012] This invention uses high-transmittance glass fragments as the main light-transmitting aggregate to replace all or part of conventional opaque natural sand and gravel aggregates. The light-transmitting aggregates create staggered light transmission channels within the composite material, guiding ultraviolet light into the component and helping to extend the depth of photocuring technology. Simultaneously, photoinitiators and thermally latent initiators are compounded within the resin matrix. The localized chemical heat released by the surface photocuring reaction activates the thermally latent initiators in deeper, un-illuminated areas, thus forming a synergistic mechanism of surface photocuring and deep thermally assisted curing. To ensure cross-linking quality, the system controls the spatial geometry of the single-layer molding thickness to ensure it does not exceed the effective light penetration depth, and coordinates the printhead spatial movement speed, extrusion rate, and ultraviolet radiation power based on material characteristics.

[0013] Preferably, the photosensitive resin is a modified acrylate photosensitive resin; the photoinitiator is TPO, 1173, 184 or a combination thereof; and the thermal latent initiator is BPO, dicumyl peroxide, azo thermal latent initiator or a combination thereof.

[0014] Preferably, the glass fragments are obtained by washing, crushing, and screening high-transmittance waste glass fragments, including coarse-grained and fine-grained transparent glass particles. The coarse-grained transparent glass particles have a particle size of 1-3 mm and are used to form a particle skeleton within the resin matrix and improve the volume stability of the component. The fine-grained transparent glass particles have a particle size of 0.1-0.5 mm and are used to fill the gaps between the coarse-grained particles and improve the aggregate packing density. Through the gradation combination of coarse and fine-grained transparent glass particles, while ensuring the mechanical skeleton support of the component, the multi-path transmission capability of cured light within the composite material is improved, thereby helping to improve the deep curing effect of large-volume photosensitive resin concrete components.

[0015] The light transmittance of the glass fragments in the 365-405nm wavelength range is not less than 30%, more preferably not less than 50%, and even more preferably not less than 70%. This transmittance does not require the glass fragments to form a continuous straight light path, but rather refers to the ability of the glass particles to guide the cured light source into the photosensitive resin concrete through transmission, refraction, scattering, and multiple inter-particle transfer interactions, thereby mitigating the blocking effect of traditional opaque natural sand and gravel aggregates on ultraviolet light.

[0016] During construction, high-transmittance waste glass fragments are interspersed inside the extruded component, forming a multi-path light transmission network composed of transmission, refraction, scattering, and multiple inter-particle transmission. When the top ultraviolet lamp group (8) and the side ultraviolet lamp group (6) transmit ultraviolet light, the ultraviolet beam is refracted and transmitted deep into the resin concrete through the light transmission microchannel, thereby effectively alleviating the physical blocking limitation of ultraviolet light by conventional macro aggregates; at the same time, in conjunction with the thermal latent initiator compounded in the resin matrix, the chemical heat energy released by the surface photocrosslinking reaction is used to stimulate deep thermal curing, ultimately achieving the synergistic molding of surface light-induced shaping and deep thermal-assisted curing of large-volume curbstone components.

[0017] Preferably, it also includes a feed inlet, a support, a hopper, and a screw extrusion device, with the discharge outlet connected to the screw extrusion device and the discharge outlet being cylindrical.

[0018] Preferably, the smoothing device includes a fixed frame, which is fixed to the discharge port. A rotating frame is rotatably mounted on the fixed frame. The rotating frame is located around the discharge port and is rectangular. Two vertical legs are symmetrically arranged at the bottom of the rotating frame. The part of the bottom of the rotating frame between the two legs forms an inverted U-shaped forming inner channel with the two legs.

[0019] Preferably, the height and width of the internal channel are the same as the height and width of the target cross section of the single-layer strip during 3D printing.

[0020] Furthermore, a low-friction rotating frame can be provided between the smoothing device and the discharge port to bear the vertical load of the smoothing device and reduce the resistance when it rotates around the discharge port axis; the low-friction rotating frame structure can be an annular sliding support, a ball bearing, a thrust bearing, a low-friction bushing or a combination thereof.

[0021] Preferably, to reduce rotational resistance, the rotating frame and the fixed frame are connected by a bearing, preferably a ball bearing.

[0022] The smoothing device in this invention does not perform post-processing smoothing with an external scraper or roller after the printing material has been freely stacked and formed a stable layer. Therefore, this invention avoids the problem of traditional external scrapers applying local shearing, pushing, or tearing actions to the already deposited weak printing layer, thereby disrupting its original stress balance.

[0023] A working method of the above-mentioned 3D printing device based on photosensitive resin concrete curbstone adopts a path planning logic of partitioned printing of the outer closed shell and the inner filling core material of the curbstone component. First, the system reads the curbstone model and performs layered path planning, dividing the single-layer working area into the outer closed shell and the inner filling core material. During printing, the printing head composed of the discharge port and the smoothing device preferentially travels along the outer contour path of the outer closed shell, adopting a mode of simultaneous extrusion, bidirectional smoothing, and ultraviolet irradiation to construct a closed retaining wall with a flat outer facade. In this invention, smoothing and curing are carried out simultaneously. The outer side of the forming inner channel is provided with a top ultraviolet lamp group (8) and a side ultraviolet lamp group (6). While the material is constrained and smoothed by the top and side in the channel, it is irradiated by the curing light source and undergoes a preliminary photocrosslinking reaction. This synchronous curing process can quickly improve the shape retention ability of the surface and near-surface layers of the material before and after leaving the channel, thereby reducing the risk of material rebound, collapse, lateral bulging, or interlayer misalignment after the channel is removed.

[0024] For the lower layer of printing material, this invention employs a method of extruding, smoothing, and curing layer by layer. The lower layer has undergone preliminary photo-setting before bearing the material of the previous layer, possessing a certain early shape retention and load-bearing capacity. The current layer, within the forming channel, is subject to relatively uniform top and lateral distributed constraints, primarily acting to shape the cross-section of the newly extruded material, and does not cause significant lateral displacement of the lower layer like a single-sided scraper. Therefore, the smoothing device of this invention not only does not significantly disrupt the stability of the printed layer, but also improves interlayer contact quality and stacking stability by limiting lateral bulging of the current layer, increasing cross-sectional regularity, and reducing interlayer grooves.

[0025] Subsequently, the print head moves to the inside of the enclosed retaining wall to perform the printing of the internal filling core material. During the internal filling stage, the lateral smoothing requirements are reduced or the lateral curing light source power is reduced / turned off according to the equipment structure and filling path requirements. The internal filling is mainly completed by relying on the already formed outer enclosed shell, the lower preliminary curing structure, and the top curing light source. The system relies on the pre-cured lower structure as a support surface and works in a vertical cycle. When the curbstone is printed as a whole and detached from the equipment, the printing is completed. The internal areas with insufficient light continue to undergo heat-assisted curing or dark curing crosslinking reaction under the action of a thermal latent initiator, so that the curbstone component gradually reaches the design required load-bearing strength.

[0026] In preferred embodiments, the outer enclosure and the inner core material are made of the same or essentially the same photosensitive resin concrete mixture, both including a continuous photosensitive resin phase, high-transmittance waste glass fragments as light-transmitting aggregate, a photoinitiator, and a thermally latent initiator. The main difference between the outer enclosure and the inner core material lies not in their material composition, but in their printing path, forming constraint method, and photocuring method. Specifically: the enclosure area is the outer surface and main service exposed surface of the curbstone; therefore, printing prioritizes the path along the outer contour, employing a method of simultaneous extrusion, top and side smoothing, and top and side photocuring to achieve good surface smoothness, boundary regularity, and early shape retention in the outer shell area. The inner core area primarily serves as the internal filling and overall load-bearing component; therefore, after the outer enclosure has been initially formed, filling printing can be performed inside the enclosure. At this stage, the requirements for side smoothing or side lighting can be reduced as needed, relying mainly on the formed shell boundary, the lower pre-cured structure, and the top curing light source to complete the internal filling forming.

[0027] In addition, the outer enclosure and the inner filling core material can be slightly adjusted within the same basic material system. For example, the gradation of the light-transmitting aggregate, the resin content, or the amount of rheology modifier can be adjusted to meet the requirements of the outer shell surface quality and the inner core filling efficiency, respectively.

[0028] Preferably, during printing, the screw extrusion device continuously extrudes the photosensitive resin concrete mixture in a fluidized state from the discharge port and feeds it into the forming inner channel inside the smoothing device. During the printing process, the system controls the material hopper pushing speed, extrusion time, print head moving speed, and single-layer printing height to match the output per unit length with the target cross-sectional dimensions of the forming inner channel. In other words, the height and width of the forming inner channel define the target cross-section of the single-layer strip. After the extruded fluidized material enters the channel, it will undergo restricted spreading, compression, and leveling under the constraints of the top and side limiting walls, thus being pressed into the shape defined by the rectangular forming inner channel.

[0029] When the discharge rate matches the target cross-section of the channel, the fluidized material mainly undergoes restricted spreading and surface leveling after entering the molding inner channel, rather than resulting in a large amount of excess material being forcibly squeezed laterally. Therefore, the constraint effect of the channel on the mixture material will not manifest as violent disturbance, but rather stably compress the mixture material into a rectangular cross-section defined by the molding inner channel.

[0030] From a material state perspective, the photosensitive resin concrete mixture is in a shear state during extrusion and entry into the channel, exhibiting certain fluid plasticity and shear thinning characteristics. It can undergo controllable plastic flow under applied extrusion pressure and channel constraint. After leaving the molding channel, the shearing effect weakens, and the material maintains its basic shape by relying on its own yield stress, particle skeleton support, and the thixotropic recovery ability of the resin system. In other words, this material is neither a completely free-flowing low-viscosity liquid nor a brittle solid that has been forcibly scraped after hardening, but rather exists in a fluid plastic state suitable for "extrusion-constrained shaping-rapid setting".

[0031] When a turn or change of direction occurs, the fluidized photosensitive resin concrete mixture generates asymmetric lateral extrusion force and tangential drag force within the forming inner channel. This asymmetric force creates a deflection torque around the discharge port axis, thereby driving the smoothing device to passively rotate relative to the discharge port. Specifically: When the printing path is straight, the fluidized photosensitive resin concrete mixture experiences symmetrical forces within the molding inner channel, and the smoothing device maintains stability in its current direction. When the printing path turns or changes direction, if an angle appears between the length direction of the molding inner channel and the printing direction, the continuously extruded fluidized photosensitive resin concrete will preferentially squeeze one side of the molding inner channel wall, creating a greater lateral extrusion force and tangential drag on that side. The asymmetrical forces will generate a deflection torque on the smoothing device around the outlet axis. When this deflection torque is greater than the resistance torque at the rotational fit between the smoothing device and the outlet, the smoothing device will passively rotate, gradually aligning the direction of the molding inner channel with the new printing direction.

[0032] In this invention, a smoothing device coaxially mounted below the discharge port utilizes its internal molding channel to simultaneously apply top surface limiting and leveling and lateral physical smoothing to the freshly extruded fluidized photosensitive resin concrete mixture. At the same time, the curing beam emitted by the ultraviolet lamp integrated on its periphery irradiates the mixture constrained and shaped within the molding channel through the transparent channel wall, which has the ability to transmit light in the effective ultraviolet or near-ultraviolet curing wavelength range. This allows the mixture to complete the initial shaping of its form through a photocrosslinking reaction before significant gravity collapse or lateral bulging deformation occurs.

[0033] In summary, the smoothing of this invention occurs within the forming inner channel immediately after material extrusion, rather than through post-extrusion scraping of the deposited layer; the forming inner channel provides distributed constraint on the top and sides, rather than localized concentrated shearing; the output, printing speed, and single-layer height are matched with the channel cross-sectional dimensions, avoiding excessive material being forcibly squeezed out; the photosensitive resin concrete mixture has fluid plastic characteristics suitable for extrusion shaping; and the top and side curing light sources enable the material to simultaneously and initially solidify under constrained shaping conditions. These factors work together to improve the surface morphology of the printed layer while reducing the risk of disturbance to the stable state of the printed layer.

[0034] For any details not covered in this invention, please refer to the prior art.

[0035] The beneficial effects of this invention are as follows: 1. This invention achieves restricted shaping, surface smoothing, and simultaneous preliminary curing of fluidized photosensitive resin concrete mixtures within a channel through the combination of a passively rotating smoothing device, a transparent molding inner channel, and top and side curing light sources. Unlike traditional methods that use external scrapers or rollers for post-deposit trimming, this invention allows the mixture to enter the molding inner channel immediately after being extruded from the outlet. Under top and side distributed constraints, it completes cross-sectional transformation and surface smoothing, and is then irradiated by the curing light source in a restricted state. This reduces the risk of surface steps, lateral bulges, and interlayer misalignment caused by collapse, spreading, or external scraping after free stacking of materials, improving the flatness and cross-sectional regularity of the curbstone component's facade.

[0036] 2. The smoothing device of this invention can passively rotate in response to changes in the printing path. When the printing path turns or changes direction, the asymmetric lateral extrusion force and tangential drag force generated by the fluidized mixture within the rectangular forming inner channel create a deflection torque, causing the rectangular forming inner channel of the smoothing device to align with the printing direction. This structure helps improve the continuous forming effect on curved sections, corner sections, or irregularly shaped curb paths, and reduces the problems of local interference, insufficient side fit, or discontinuous forming that may occur with fixed smoothing structures on complex paths.

[0037] 3. This invention uses high-transmittance waste glass fragments as translucent aggregate. Its function is not merely to replace natural sand and gravel aggregates, but also to simultaneously undertake the functions of solid waste resource utilization, particle skeleton support, and multi-path transmission of cured light. Coarse-grained translucent glass particles can form a particle skeleton within the resin matrix, improving the volume stability and compressive load-bearing capacity of the component; fine-grained translucent glass particles can fill the gaps between coarse-grained particles, increasing the aggregate packing density. Simultaneously, the translucent aggregate can increase the effective depth of cured light within the composite material through transmission, refraction, scattering, and multiple inter-particle transmission, thereby alleviating the light-blocking problem caused by conventional opaque sand and gravel aggregates.

[0038] 4. This invention combines a continuous phase of photosensitive resin, a photoinitiator, a thermally latent initiator, and high-transmittance waste glass fragments as light-transmitting aggregate to form a dual photothermal curing mechanism that integrates surface photocuring and deep thermally assisted curing. Top and side curing light sources enable rapid photocrosslinking reactions in the restricted-shape surface and near-surface materials, establishing initial shape retention. For deeper areas with insufficient curing light, the thermally latent initiator can release heat during surface photocrosslinking or initiate further crosslinking during subsequent dark curing. These effects help improve the problem of insufficient internal curing in large-volume photosensitive resin concrete components, enhancing early strength, internal curing uniformity, and overall load-bearing stability.

[0039] 5. This invention employs a path planning method that separates the outer enclosed shell area and the inner filling area for printing, ensuring both the appearance quality of the curbstone and the efficiency of the internal filling. The outer enclosed shell area is preferentially formed using a method of side extrusion, side top and side smoothing, and side top and side light curing, which helps improve the flatness of the component's exterior surface, the regularity of the boundaries, and the density of the exposed surfaces during service. The inner filling area can be filled after the outer enclosed shell has been initially formed, mainly relying on the already formed shell boundary, the lower preliminary cured structure, and the top curing light source to complete the internal solid formation. This partitioned printing method helps to coordinate appearance quality, forming efficiency, and overall load-bearing capacity.

[0040] 6. The photosensitive resin concrete curbstone prepared by this invention exhibits good early-stage molding stability and durability potential. The confined smoothing within the channel reduces interlayer grooves and surface defects, lowering the risk of moisture, dirt, and de-icing agents remaining in the grooves on the component surface. The resin cross-linking network and the high-density, translucent aggregate system contribute to improved component density. The dual photothermal curing mechanism helps improve insufficient deep curing. These multiple effects collectively enhance the curbstone's ability to maintain structural integrity in a salt-freezing environment and help shorten on-site waiting time during municipal curbstone laying, repair, or replacement.

[0041] In summary, this invention addresses the molding requirements of high-performance photosensitive resin concrete curb stones by collaboratively designing a passively rotating transparent molding inner channel, a restricted smoothing and simultaneous curing within the channel, high-transmittance waste glass fragments as light-transmitting aggregate, a photothermal dual-curing material system, and a partitioned printing process for the outer closed shell area and the inner filling area. This simultaneously improves issues such as surface step effect, smoothing disturbance risk, insufficient deep curing, solid waste resource utilization, and salt freeze durability. Attached Figure Description

[0042] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0043] Figure 1 This is a schematic diagram of the overall structure of the 3D printing device for photosensitive resin concrete curbstone according to the present invention. Figure 2 This is a schematic diagram of the smoothing device of the present invention; Among them, 1-feed inlet, 2-support, 3-hopper, 4-discharge outlet, 5-smoothing device, 6-side UV lamp assembly, 7-forming inner channel, 8-top UV lamp assembly. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. However, this is not the only description; all aspects not described in detail herein are based on conventional techniques in the art.

[0045] Example 1 A 3D printing device based on photosensitive resin concrete curbstone, such as Figure 1 As shown, it includes a discharge port 4, and a smoothing device 5 is coaxially mounted on the outside of the discharge port 4; the smoothing device 5 and the discharge port 4 can rotate freely, as shown... Figure 2 As shown; The smoothing device 5 has an inverted U-shaped molding inner channel 7 at its bottom (the whole is rectangular but open at the bottom). The bottom of the discharge port 4 is located inside the molding inner channel (the bottom of the discharge port is located at the upper feeding end of the molding inner channel, or extends a certain distance into the upper part of the molding inner channel). This allows the fluidized photosensitive resin concrete to enter the molding inner channel first for top and lateral constraint. The top and side walls of the molding inner channel are transparent. Ultraviolet lamps are installed inside the top and side walls of the molding inner channel to irradiate the photosensitive resin concrete mixture constrained and shaped by the molding inner channel. This allows the photosensitive resin concrete mixture to complete the initial shaping of its form through photocrosslinking reaction before significant gravity collapse or lateral bulging deformation occurs.

[0046] The fluidized photosensitive resin concrete extruded from outlet 4 first enters the molding inner channel 7, where it is constrained by the top surface and laterally, thus completing the transition from a circular discharge section to a rectangular molding section. Subsequently, the material is simultaneously smoothed within the molding inner channel and irradiated by top and lateral curing light sources, and finally discharged from the lower outlet of the molding inner channel and stacked into shape.

[0047] Example 2 A 3D printing device for photosensitive resin concrete curbstone, as described in Example 1, differs in that the photosensitive resin concrete mixture, by weight, comprises: 15-25 parts photosensitive resin, 0.2-1.0 parts photoinitiator, 0.1-0.8 parts thermal latent initiator, and 75-85 parts high-transmittance glass fragments. Depending on the material rheology, gradation density, and cost control requirements, one or more of the following can be selectively added: opaque auxiliary aggregate, inorganic filler, thickener, coupling agent, defoamer, or rheology modifier. The opaque auxiliary aggregate is an optional component, used to adjust particle size distribution, reduce costs, or improve volume stability. Its mass percentage in the photosensitive resin concrete mixture can be 0%-25%, preferably 0%-10%. The opaque auxiliary aggregate can be selected from natural quartz sand, manufactured sand, ordinary river sand, stone powder, calcium carbonate powder, mineral powder, silica fume, or combinations thereof.

[0048] This invention uses high-transmittance glass fragments as the main light-transmitting aggregate to replace all or part of conventional opaque natural sand and gravel aggregates. The light-transmitting aggregates create staggered light transmission channels within the composite material, guiding ultraviolet light into the component and helping to extend the depth of photocuring technology. Simultaneously, photoinitiators and thermally latent initiators are compounded within the resin matrix. The localized chemical heat released by the surface photocuring reaction activates the thermally latent initiators in deeper, un-illuminated areas, thus forming a synergistic mechanism of surface photocuring and deep thermally assisted curing. To ensure cross-linking quality, the system controls the spatial geometry of the single-layer molding thickness to ensure it does not exceed the effective light penetration depth, and coordinates the printhead spatial movement speed, extrusion rate, and ultraviolet radiation power based on material characteristics.

[0049] The photosensitive resin is a modified acrylate photosensitive resin; the photoinitiator is TPO, 1173, 184 or a combination thereof; the thermal latent initiator is BPO, dicumyl peroxide, azo thermal latent initiator or a combination thereof.

[0050] Glass fragments are obtained by washing, crushing, and screening high-transmittance waste glass fragments. They include coarse-grained and fine-grained transparent glass particles. The coarse-grained particles, with a diameter of 1-3 mm, form a particle skeleton within the resin matrix and improve the volumetric stability of the component. The fine-grained particles, with a diameter of 0.1-0.5 mm, fill the gaps between the coarse-grained particles and improve the aggregate packing density. This gradation combination of coarse and fine-grained transparent glass particles ensures the structural support of the component while enhancing the multi-path transmission capability of cured light within the composite material, thereby contributing to improved deep curing effects in large-volume photosensitive resin concrete components.

[0051] The glass fragments are obtained by washing, crushing, and screening high-transmittance waste glass fragments, and include coarse-grained and fine-grained transparent glass particles. The mass ratio of the coarse-grained to the fine-grained transparent glass particles is 6:4 to 8:2, preferably 7:3.

[0052] The coarse-grained transparent glass particles have a particle size of 1–3 mm and are used to form a particle skeleton in the resin matrix, improve the volume stability of the component, and form a longer curing light transmission path; the fine-grained transparent glass particles have a particle size of 0.1–0.5 mm and are used to fill the gaps between the coarse-grained particles, improve the aggregate packing density, and improve the surface regularity of the extruded strip.

[0053] When the proportion of coarse-grained transparent glass particles is too high, the filling effect of fine-grained particles on the gaps in the skeleton is insufficient, which may cause local pores and surface unevenness. When the proportion of fine-grained transparent glass particles is too high, the total specific surface area of ​​the particles and the resin encapsulation requirement increase, which may increase the viscosity of the mixture and the extrusion resistance, and weaken the skeletal support effect of the coarse-grained particles. Therefore, through the above-mentioned gradation combination of coarse and fine particles, the aggregate packing density is improved while ensuring the skeletal support and volume stability of the component, and the extrusion molding performance of the photosensitive resin concrete mixture and the multi-path transmission capability of the cured light are also taken into account.

[0054] The transmittance of glass fragments in the 365-405nm wavelength range is not less than 70%. The transmittance does not require the glass fragments to form a continuous straight light path, but rather that the glass particles can guide the cured light source into the photosensitive resin concrete through transmission, refraction, scattering, and multiple inter-particle transfer interactions, thereby alleviating the blocking effect of traditional opaque natural sand and gravel aggregates on ultraviolet light.

[0055] During construction, high-transmittance waste glass fragments are interspersed inside the extruded component, forming a multi-path light transmission network composed of transmission, refraction, scattering, and multiple inter-particle transmission. When the top ultraviolet lamp group (8) and the side ultraviolet lamp group (6) transmit ultraviolet light, the ultraviolet beam is refracted and transmitted deep into the resin concrete through the light transmission microchannel, thereby effectively alleviating the physical blocking limitation of ultraviolet light by conventional macro aggregates; at the same time, in conjunction with the thermal latent initiator compounded in the resin matrix, the chemical heat energy released by the surface photocrosslinking reaction is used to stimulate deep thermal curing, ultimately achieving the synergistic molding of surface light-induced shaping and deep thermal-assisted curing of large-volume curbstone components.

[0056] Example 3 A 3D printing device based on photosensitive resin concrete curbstone, as described in Example 2, except that it also includes a feed inlet 1, a support 2, a hopper 3, and a screw extrusion device (not shown), and a discharge outlet 4 connected to the screw extrusion device, and the discharge outlet 4 is cylindrical.

[0057] like Figure 2 The smoothing device 5 includes a fixed frame, which is fixed to the discharge port 4. A rotating frame is rotatably mounted on the fixed frame 4. The rotating frame is located around the discharge port and is rectangular. Two vertical legs are symmetrically arranged at the bottom of the rotating frame. The part of the bottom of the rotating frame between the two legs forms an inverted U-shaped forming inner channel 7 with the two legs.

[0058] A top ultraviolet lamp group 8 and a side ultraviolet lamp group 6 are respectively installed at the top of the inner channel and inside the two legs; The height and width of the inner channel 7 are the same as the height and width of the target cross section of the single-layer strip during 3D printing.

[0059] To reduce rotational resistance, the rotating frame and the fixed frame are connected by a bearing, preferably a ball bearing.

[0060] Example 4 A working method for a 3D printing device based on photosensitive resin concrete curbstone employs a path planning logic that divides the curbstone component into an outer closed shell and an inner filling core material for partitioned printing. First, the system reads the curbstone model and performs layered path planning, dividing the single-layer working area into an outer closed shell and an inner filling core material. During printing, the print head, consisting of the discharge port and a smoothing device, preferentially travels along the outer contour path of the outer closed shell, employing a mode of simultaneous extrusion, bidirectional smoothing, and ultraviolet irradiation to construct a closed retaining wall with a smooth outer surface. Smoothing and curing occur simultaneously in this invention. A top ultraviolet lamp group 8 and a side ultraviolet lamp group 6 are installed on the outer side of the forming inner channel. While the material is being constrained and smoothed by the top and sides within the channel, it is simultaneously irradiated by the curing light source and undergoes a preliminary photocrosslinking reaction. This simultaneous curing process can rapidly improve the shape retention ability of the surface and near-surface layers of the material before and after it leaves the channel, thereby reducing the risk of material rebound, collapse, lateral bulging, or interlayer misalignment after the channel is removed.

[0061] For the lower layer of printing material, this invention employs a method of extruding, smoothing, and curing layer by layer. The lower layer has undergone preliminary photo-setting before bearing the material of the previous layer, possessing a certain early shape retention and load-bearing capacity. The current layer, within the forming channel, is subject to relatively uniform top and lateral distributed constraints, primarily acting to shape the cross-section of the newly extruded material, and does not cause significant lateral displacement of the lower layer like a single-sided scraper. Therefore, the smoothing device of this invention not only does not significantly disrupt the stability of the printed layer, but also improves interlayer contact quality and stacking stability by limiting lateral bulging of the current layer, increasing cross-sectional regularity, and reducing interlayer grooves.

[0062] Subsequently, the print head moves to the inside of the enclosed retaining wall to perform the printing of the internal filling core material. During the internal filling stage, the lateral smoothing requirements are reduced or the lateral curing light source power is reduced / turned off according to the equipment structure and filling path requirements. The internal filling is mainly completed by relying on the already formed outer enclosed shell, the lower preliminary curing structure, and the top curing light source. The system relies on the pre-cured lower structure as a support surface and works in a vertical cycle. When the curbstone is printed as a whole and detached from the equipment, the printing is completed. The internal areas with insufficient light continue to undergo heat-assisted curing or dark curing crosslinking reaction under the action of a thermal latent initiator, so that the curbstone component gradually reaches the design required load-bearing strength.

[0063] In preferred embodiments, the outer enclosure and the inner core material are made of the same or essentially the same photosensitive resin concrete mixture, both including a continuous photosensitive resin phase, high-transmittance waste glass fragments as light-transmitting aggregate, a photoinitiator, and a thermally latent initiator. The main difference between the outer enclosure and the inner core material lies not in their material composition, but in their printing path, forming constraint method, and photocuring method. Specifically: the enclosure area is the outer surface and main service exposed surface of the curbstone; therefore, printing prioritizes the path along the outer contour, employing a method of simultaneous extrusion, top and side smoothing, and top and side photocuring to achieve good surface smoothness, boundary regularity, and early shape retention in the outer shell area. The inner core area primarily serves as the internal filling and overall load-bearing component; therefore, after the outer enclosure has been initially formed, filling printing can be performed inside the enclosure. At this stage, the requirements for side smoothing or side lighting can be reduced as needed, relying mainly on the formed shell boundary, the lower pre-cured structure, and the top curing light source to complete the internal filling forming.

[0064] In addition, the outer enclosure and the inner filling core material can be slightly adjusted within the same basic material system. For example, the gradation of the light-transmitting aggregate, the resin content, or the amount of rheology modifier can be adjusted to meet the requirements of the outer shell surface quality and the inner core filling efficiency, respectively.

[0065] Example 5 A method for operating a 3D printing device based on photosensitive resin concrete curbstone, as described in Example 4, differs in that during printing, the screw extrusion device continuously extrudes the photosensitive resin concrete mixture in a fluidized state from the discharge port and feeds it into the forming inner channel inside the smoothing device. During the printing process, the system controls the material hopper pushing speed, extrusion time, print head moving speed, and single-layer printing height to match the output per unit length with the target cross-sectional dimensions of the forming inner channel. In other words, the height and width of the forming inner channel define the target cross-section of the single-layer strip. After the extruded fluidized material enters the channel, it undergoes restricted spreading, compression, and leveling under the constraints of the top and side limiting walls, thereby being compressed into the shape defined by the rectangular forming inner channel.

[0066] When the discharge rate matches the target cross-section of the channel, the fluidized material mainly undergoes restricted spreading and surface leveling after entering the molding inner channel, rather than resulting in a large amount of excess material being forcibly squeezed laterally. Therefore, the constraint effect of the channel on the mixture material will not manifest as violent disturbance, but rather stably compress the mixture material into a rectangular cross-section defined by the molding inner channel.

[0067] From a material state perspective, the photosensitive resin concrete mixture is in a shear state during extrusion and entry into the channel, exhibiting certain fluid plasticity and shear thinning characteristics. It can undergo controllable plastic flow under applied extrusion pressure and channel constraint. After leaving the molding channel, the shearing effect weakens, and the material maintains its basic shape by relying on its own yield stress, particle skeleton support, and the thixotropic recovery ability of the resin system. In other words, this material is neither a completely free-flowing low-viscosity liquid nor a brittle solid that has been forcibly scraped after hardening, but rather exists in a fluid plastic state suitable for "extrusion-constrained shaping-rapid setting".

[0068] When a turn or change of direction occurs, the fluidized photosensitive resin concrete mixture generates asymmetric lateral extrusion force and tangential drag force within the forming inner channel. This asymmetric force creates a deflection torque around the discharge port axis, thereby driving the smoothing device to passively rotate relative to the discharge port. Specifically: When the printing path is straight, the fluidized photosensitive resin concrete mixture experiences symmetrical forces within the molding inner channel, and the smoothing device maintains stability in its current direction. When the printing path turns or changes direction, if an angle appears between the length direction of the molding inner channel and the printing direction, the continuously extruded fluidized photosensitive resin concrete will preferentially squeeze one side of the molding inner channel wall, creating a greater lateral extrusion force and tangential drag on that side. The asymmetrical forces will generate a deflection torque on the smoothing device around the outlet axis. When this deflection torque is greater than the resistance torque at the rotational fit between the smoothing device and the outlet, the smoothing device will passively rotate, gradually aligning the direction of the molding inner channel with the new printing direction.

[0069] In this invention, a smoothing device coaxially mounted below the discharge port utilizes its internal molding channel to simultaneously apply top surface limiting and leveling and lateral physical smoothing to the freshly extruded fluidized photosensitive resin concrete mixture. At the same time, the curing beam emitted by the ultraviolet lamp integrated on its periphery irradiates the mixture constrained and shaped within the molding channel through the transparent channel wall, which has the ability to transmit light in the effective ultraviolet or near-ultraviolet curing wavelength range. This allows the mixture to complete the initial shaping of its form through a photocrosslinking reaction before significant gravity collapse or lateral bulging deformation occurs.

[0070] In summary, the smoothing of this invention occurs within the forming inner channel immediately after material extrusion, rather than through post-extrusion scraping of the deposited layer; the forming inner channel provides distributed constraint on the top and sides, rather than localized concentrated shearing; the output, printing speed, and single-layer height are matched with the channel cross-sectional dimensions, avoiding excessive material being forcibly squeezed out; the photosensitive resin concrete mixture has fluid plastic characteristics suitable for extrusion shaping; and the top and side curing light sources enable the material to simultaneously and initially solidify under constrained shaping conditions. These factors work together to improve the surface morphology of the printed layer while reducing the risk of disturbance to the stable state of the printed layer.

[0071] Example 6 A method for operating a 3D printing device based on photosensitive resin concrete curbstone, as described in Example 5, except that the photosensitive resin concrete mixture includes, by weight, 18 parts photosensitive resin, 0.4 parts TPO, 0.2 parts BPO, and 78 parts high-transmittance quartz glass fragments as light-transmitting aggregate. The 3D printing device of the present invention is used for printing; Printing is performed at a layer thickness of 20mm and a shell printing speed of 40mm / s. The fluidized photosensitive resin concrete mixture is physically leveled by top and side constraints within the molding channel. Simultaneously, curing light is transmitted into the component through a multi-path light transmission network formed by the translucent aggregate, enabling the mixture to quickly complete its initial shaping. When turning, the smoothing device passively rotates under the deflection torque generated by the constrained flow of material, causing the molding channel to tend to conform to the printing direction, thereby improving the continuity of surface flatness at the turning points.

[0072] Comparative Example 1 A method for operating a 3D printing device based on photosensitive resin concrete curbstone. The formula of the photosensitive resin concrete mixture is the same as that in Example 6. The difference is that the smoothing device is removed, and only the discharge port is retained for direct extrusion.

[0073] Print and cure layer by layer at a thickness of 20mm and a speed of 40mm / s.

[0074] Comparative Example 2 A method for operating a 3D printing device for curb stones, which uses conventional resin concrete, that is, without adding high light transmittance waste glass fragments as light-transmitting aggregate, and completely replacing them with opaque conventional natural quartz sand aggregate, and without adding thermal latent initiators.

[0075] Install and use the complete molding apparatus of the present invention (including a smoothing device and a circumferential ultraviolet lamp assembly). Printing is performed at a layer thickness of 20mm and a speed of 40mm / s. The material is physically leveled on three sides within the forming channel, and is simultaneously irradiated by top and side ultraviolet lamps through the transparent channel wall of the smoothing device.

[0076] To verify the synergistic effect of the follow-up smoothing device and the light-transmitting aggregate photothermal dual curing system in this invention, comparative tests were conducted on different control variable embodiments with the same printing layer thickness, printing speed, curing light source power and curing conditions. The test results are shown in Table 1.

[0077] Table 1 Comparison of curbstone performance in different control variable embodiments

[0078] The test results of the controlled variables in Table 1 show that: (1) Comparative Example 1 shows that, in the absence of a follow-up smoothing device, the photothermal dual curing system relying solely on the material is difficult to effectively improve the interlayer step effect generated by 3D printing stacked extrusion. The wavy grooves formed on the side of the component are prone to become stress concentration areas and moisture enrichment areas under salt freeze-thaw cycle erosion, thereby increasing the risk of cracking and peeling of the component along the interlayer interface.

[0079] (2) Comparative Example 2 shows that, in the absence of high-transmittance waste glass shavings and thermal latent initiators, although the follow-up smoothing device can improve the surface smoothness of the component, conventional opaque sand and gravel aggregates will limit the effective propagation depth of curing light inside the material, causing the photocrosslinking reaction to be mainly concentrated on the surface of the component, and the deep internal area is prone to insufficient curing, resulting in low overall early compressive strength of the component, which is difficult to meet the needs of rapid molding and early handling of municipal curb stones.

[0080] (3) Example 6 shows that the complete solution of the present invention combines a follow-up constraint smoothing molding structure with a photothermal dual-curing material system based on high-transmittance waste glass shavings and translucent aggregate. The restricted smoothing effect of the rectangular molding internal channels improves the apparent geometric defects of the component, while the multi-path light conduction network formed by the translucent aggregate and the deep thermal-assisted curing effect of the thermally latent initiator improve the internal curing uniformity of the large-volume resin concrete component. The synergistic effect of the two enables the component to obtain high early strength and maintain good structural integrity after salt freeze-thaw cycles, indicating that the solution of the present invention has the application potential for moldless rapid molding of municipal curb stones.

[0081] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A 3D printing device based on photosensitive resin concrete curbstone, characterized in that, The device includes a discharge port, and a smoothing device is coaxially arranged outside the discharge port; the smoothing device and the discharge port can rotate freely. The smoothing device has an inverted U-shaped molding inner channel at its bottom, with the bottom of the discharge port located inside the molding inner channel. The top and side walls of the molding inner channel are transparent, and ultraviolet lamps are installed inside the top and side walls of the molding inner channel to irradiate the photosensitive resin concrete mixture constrained and shaped by the molding inner channel. This allows the photosensitive resin concrete mixture to complete its initial shape through a photocrosslinking reaction before it collapses under gravity or bulges laterally.

2. The 3D printing device for photosensitive resin concrete curbstone according to claim 1, characterized in that, The photosensitive resin concrete mixture comprises, by weight, 15-25 parts of photosensitive resin, 0.2-1.0 parts of photoinitiator, 0.1-0.8 parts of thermal latent initiator, and 75-85 parts of glass fragments.

3. The 3D printing device for photosensitive resin concrete curbstone according to claim 2, characterized in that, The photosensitive resin is a modified acrylate photosensitive resin; the photoinitiator is TPO, 1173, 184 or a combination thereof; the thermal latent initiator is BPO, dicumyl peroxide, azo thermal latent initiator or a combination thereof.

4. The 3D printing device for photosensitive resin concrete curbstone according to claim 3, characterized in that, The glass fragments are obtained by washing, crushing and screening high-transmittance waste glass fragments, including coarse-grained transparent glass particles and fine-grained transparent glass particles. The particle size of the coarse-grained transparent glass particles is 1-3 mm, and the particle size of the fine-grained transparent glass particles is 0.1-0.5 mm. The transmittance of the glass fragments in the 365-405nm wavelength range is not less than 30%.

5. The 3D printing device for photosensitive resin concrete curbstone according to claim 4, characterized in that, It also includes a feed inlet, a support, a hopper, and a screw extrusion device. The discharge outlet is connected to the screw extrusion device and is cylindrical.

6. The 3D printing device for photosensitive resin concrete curbstone according to claim 4, characterized in that, The smoothing device includes a fixed frame, which is fixed to the discharge port. A rotating frame is rotatably mounted on the fixed frame. The rotating frame is located around the discharge port and is rectangular. Two vertical legs are symmetrically arranged at the bottom of the rotating frame. The part of the bottom of the rotating frame between the two legs forms an inverted U-shaped forming inner channel with the two legs.

7. The 3D printing device for photosensitive resin concrete curbstone according to claim 6, characterized in that, The height and width of the internal channel are the same as the height and width of the target cross section of the single-layer strip during 3D printing.

8. The 3D printing device for photosensitive resin concrete curbstone according to claim 6, characterized in that, To reduce rotational resistance, the rotating frame and the fixed frame are connected by a bearing, preferably a ball bearing.

9. A method for operating the 3D printing device based on photosensitive resin concrete curbstone as described in any one of claims 1-8, characterized in that, The system employs a path planning logic that divides the outer closed shell and the inner filling core material of the curbstone component into zones. First, the system reads the curbstone model and performs layered path planning, dividing the single-layer operation area into the outer closed shell and the inner filling core material. During printing, the print head, which consists of the discharge port and the smoothing device, prioritizes the movement along the outer contour path of the outer closed shell, using a mode of simultaneous extrusion, bidirectional smoothing, and ultraviolet light irradiation to construct a closed retaining wall with a smooth exterior. Subsequently, the print head moves to the inside of the closed retaining wall to perform the printing operation of the internal filling core material. After the entire curbstone is printed and detached from the equipment, the printing is completed. The internal areas with insufficient light continue to undergo heat-assisted curing or dark curing crosslinking reaction under the action of a heat-latent initiator, so that the curbstone component gradually reaches the load-bearing strength required by the design.

10. The working method of the 3D printing device based on photosensitive resin concrete curbstone according to claim 9, characterized in that, During printing, the screw extrusion device continuously extrudes the photosensitive resin concrete mixture in a fluid state from the discharge port and feeds it into the forming inner channel inside the smoothing device. During the printing process, the system controls the material hopper pushing speed, extrusion time, print head moving speed and single-layer printing height to match the output per unit length with the target cross-sectional size of the forming inner channel. When a turn or change of direction occurs, the fluidized photosensitive resin concrete mixture generates asymmetric lateral extrusion force and tangential drag force within the forming inner channel. This asymmetric force creates a deflection torque around the discharge port axis, thereby driving the smoothing device to passively rotate relative to the discharge port. Specifically: When the printing path is straight, the fluidized photosensitive resin concrete mixture experiences symmetrical forces within the molding inner channel, and the smoothing device maintains stability in its current direction. When the printing path turns or changes direction, if an angle appears between the length direction of the molding inner channel and the printing direction, the continuously extruded fluidized photosensitive resin concrete will preferentially squeeze one side of the molding inner channel wall, creating a greater lateral extrusion force and tangential drag on that side. The asymmetrical forces will generate a deflection torque on the smoothing device around the outlet axis. When this deflection torque is greater than the resistance torque at the rotational fit between the smoothing device and the outlet, the smoothing device will passively rotate, gradually aligning the direction of the molding inner channel with the new printing direction.

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