3D printing equipment

Abstract

The invention belongs to the technical field of 3D printing, and particularly discloses 3D printing equipment which comprises a box body and a door body, the door body seals the box body, a printing unit used for printing elastic materials is installed in the box body, the 3D printing equipment further comprises a low-temperature temperature control unit, and the low-temperature temperature control unit comprises a compressor, a condenser, a throttling component, an evaporator, a low-pressure pipe and a high-pressure pipe; the evaporator is installed in the box body, and the compressor and the condenser are installed on the outer side of the box body. An outlet of the evaporator is connected with an air suction port of the compressor through the low-pressure pipe; an exhaust port of the compressor is connected with an inlet of the condenser through the high-pressure pipe, and an inlet of the evaporator is communicated with an outlet of the condenser through the throttling component. The printed part can be in a low-temperature state, the moving speed of the printing nozzle is increased, and therefore the printing speed is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a 3D printing device. Background Art

[0002] 3D printing is a technology that creates three-dimensional products by gradually adding material. This technology integrates cutting-edge technologies from many fields and is hailed as the core technology of the "Third Industrial Revolution." FDM 3D printing is a rapid prototyping process based on material extrusion, characterized by low energy consumption, low cost, and high forming precision. FDM stands for "Fused Deposition Modeling," also known as FFF, or "Fused Filament Fabrication." In FDM printing, objects are constructed by selectively depositing molten material layer by layer along a predetermined path.

[0003] Typically, when printing elastic materials with FDM 3D printing technology, during the process of selectively depositing molten material layer by layer, as the print head moves over the completed part to deposit the next layer, the already printed part will create a certain resistance to the movement of the print head. Since elastic materials are flexible, the printed products are also flexible. As the height of the printed part increases, the reaction force of this resistance will cause the already printed part to shake more and more obviously, resulting in increasingly significant misalignment between layers, ultimately causing a low yield rate for the printed products, or even printing failure and scrapped products.

[0004] During the above printing process, the faster the print head moves, the greater the resistance, resulting in a higher risk of printing failure. Therefore, when using FDM 3D printing technology to print elastic materials, the printing speed is very slow and the printing efficiency is extremely low. Currently, it usually takes 90-104 hours to print a pair of size 42-43 elastic shoes using this technology. Summary of the Invention

[0005] The present invention provides a 3D printing device, the purpose of which is to keep the printed part in a low-temperature state, increase the moving speed of the printing nozzle, and thus increase the printing speed.

[0006] The present invention is achieved through the following technical solution: a 3D printing device, comprising a box and a door, wherein the door encloses the box, wherein a printing unit for printing elastic material is installed in the box, and further comprising a low-temperature temperature control unit, wherein the low-temperature temperature control unit includes a compressor, a condenser, a throttling component, an evaporator, a low-pressure pipe, and a high-pressure pipe; the evaporator is installed in the box, and the compressor and the condenser are installed outside the box; The outlet of the evaporator is connected to the air intake of the compressor through the low-pressure pipe; the exhaust port of the compressor is connected to the inlet of the condenser through the high-pressure pipe, and the inlet of the evaporator and the outlet of the condenser are connected through the throttling component.

[0007] Compared with the existing technology, this solution has the following advantages and beneficial effects: During the printing process of the elastic material, the chamber remains closed. A low-temperature control unit, through the coordinated operation of components such as a compressor, condenser, and evaporator, maintains a stable temperature within the chamber, below the glass transition temperature (Tg) of the printing material. This keeps the printed area cool, increasing the movement of the print head and, consequently, the printing speed. The low temperature rapidly freezes the already printed area. The movement of the amorphous segments in the material is restricted, while the crystallization rate in the semi-crystalline regions is accelerated, transforming the material from a viscoelastic state to a rigid solid state. Deformation can be controlled to the micron level. This low deformation allows the print head to move at speeds 10-15 times faster than traditional FDM technology (without slowing down to allow the material to set), significantly shortening the printing cycle (for example, printing a pair of elastic shoe parts can be reduced from 90-104 hours to 7-11 hours), making mass 3D printing of elastic materials possible.

[0008] Elastic materials are easily deformed at room temperature due to creep, deadweight or nozzle disturbance, leading to problems such as interlayer offset and line distortion. In this solution, the low temperature environment significantly improves the rigidity of the printed parts and enhances anti-interference ability: even if it is slightly hit by the high-speed movement of the nozzle or the airflow disturbance, the structural dimensions can be kept stable. At the same time, the low temperature only freezes the deep material of the printed part. When the newly extruded molten material comes into contact with the low-temperature substrate, the contact surface is temporarily heated due to local heat conduction, ensuring that the molecular chains between layers are effectively entangled, avoiding structural collapse without sacrificing the bonding strength between layers, and solving the pain point of "difficulty in balancing speed and precision" in the printing of elastic materials.

[0009] Low temperatures can inhibit chemical reactions such as oxidation and hydrolysis in elastic materials during the printing process, reducing material performance degradation (such as yellowing and decreased mechanical strength). For semi-crystalline elastic materials, low temperatures can regulate their crystallinity distribution, resulting in more uniform mechanical properties (such as tensile strength and elastic modulus) across the printed part. Furthermore, the rigidified printed structure provides stable support for subsequent layers, enabling the direct molding of complex shapes such as suspended structures and grid-like cutouts without the need for additional support structures, reducing post-processing steps and material waste.

[0010] The low-temperature temperature control unit achieves efficient use of the internal space of the cabinet through a reasonable layout (built-in evaporator, external compressor and condenser), preventing the refrigeration components from occupying the printing work area; the piping design of low-pressure pipes, high-pressure pipes and throttling components ensures efficient refrigerant circulation.

[0011] Furthermore, a condenser tube and a plurality of heat sinks are provided in the condenser, the plurality of heat sinks are fixed inside the condenser, the condenser tube is coiled in a serpentine shape in the condenser, the plurality of heat sinks are distributed at intervals and connected to the condenser tube, and a fan is provided in the condenser.

[0012] Beneficial Effects: The condenser tube in this solution features a serpentine coil design, which prolongs the flow path of the high-temperature, high-pressure gaseous refrigerant within the condenser and increases the contact time between the refrigerant and the heat sink. Furthermore, multiple, spaced-apart heat sinks are tightly connected to the condenser tube, rapidly dissipating the heat transferred from the condenser tube over a larger surface area. This structure allows the refrigerant to efficiently release heat during its flow, ensuring full condensation from gas to liquid. This provides a stable supply of high-pressure liquid refrigerant for subsequent pressure reduction and throttling by the throttling components, thus avoiding the loss of cooling efficiency caused by incomplete condensation (such as abnormally high compressor exhaust pressure and cooling capacity reduction).

[0013] The serpentine coils allow for a long pipe layout within the limited condenser's internal space. Combined with spaced-apart heat sinks, this design meets cooling requirements without increasing the condenser's overall size. This compact design is particularly well-suited for integrating 3D printing equipment. The condenser can be installed externally (e.g., on the back, sides, or bottom) without occupying space within the print chamber, reducing the overall footprint and balancing cooling performance with miniaturization.

[0014] In this solution, a fan is provided in the condenser to dissipate heat and improve the heat dissipation efficiency of the condenser.

[0015] Furthermore, the evaporator includes an evaporation tube, which is coiled in a serpentine shape inside the evaporator, and the evaporator is laid on one or more surfaces of the inner layer of the box.

[0016] Beneficial effect: The evaporation tube is designed in a serpentine coil, which extends the flow path of the low-temperature and low-pressure refrigerant in the limited space inside the evaporator and increases the heat exchange time between the refrigerant and the air in the printing cabin (box).

[0017] Furthermore, the throttling component is a capillary tube or an expansion valve.

[0018] Beneficial Effects: The throttling components in this solution, whether fixed capillary tube throttling or dynamic expansion valve throttling, effectively separate the high-pressure side (condenser, compressor discharge) from the low-pressure side (evaporator, compressor suction) of the refrigeration system, preventing direct pressure transfer between the two sides and causing system disturbances (such as compressor overload and refrigerant backflow). This pressure isolation reduces load fluctuations on core components such as the compressor and condenser, reduces the risk of mechanical wear and fatigue aging, and extends the overall service life of the equipment.

[0019] Furthermore, the box body and the door body both include an inner layer, an interlayer and an outer layer, the inner layer and the outer layer are both metal shells or plastic shells, and the interlayer is a heat-insulating layer.

[0020] Beneficial effects: The insulation layer in the interlayer (such as polyurethane foam layer, vacuum insulation panel or glass wool) forms a thermal resistance barrier through low thermal conductivity materials, which can effectively prevent the heat from the external environment outside the box (such as room temperature, heat dissipation from equipment operation) from being transferred to the low-temperature area inside the box, while reducing the loss of cold air inside the box to the outside.

[0021] Furthermore, a sealing strip is provided on the edge contour of the inner side of the door body that contacts the box body.

[0022] Beneficial Effect: The sealing strip deforms to tightly fill the gap between the door and the chamber, forming a complete, sealed barrier. This effectively prevents ambient air (heat and moisture) from entering the chamber, while also preventing the escape of cold air inside. This design, combined with the chamber's three-layer insulation, reduces heat exchange at the gap between the chamber and the door by over 90%, preventing temperature fluctuations within the chamber caused by convection. This ensures a uniformly low temperature environment across the entire printing area, safeguarding the stability of the frozen elastic material segments.

[0023] Furthermore, an observation window is provided on the door body, and the observation window is a transparent observation window.

[0024] Benefits: The transparent observation window allows operators to directly observe the 3D printing progress of the elastic material inside the chamber (such as interlayer adhesion and printhead filament stability), equipment operation (such as print platform movement and evaporator frost), and low-temperature environmental conditions (such as abnormal fogging and material deformation due to temperature fluctuations) without opening the door. This real-time visual monitoring can promptly detect printing defects (such as stringing, edge warping, and clogging), avoid sudden temperature increases inside the chamber caused by frequent door openings, thereby reducing the risk of material scrap and preventing changes in material viscosity caused by temperature fluctuations, which can lead to reduced printing accuracy. Without an observation window, operators would need to frequently open the door to check the printing status. Each door opening allows ambient air (containing heat and moisture) to flow into the chamber, disrupting the low-temperature environment and increasing refrigeration system energy consumption. It can also cause the printed layers to soften and deform due to the increased temperature. The transparent observation window eliminates this problem through "non-contact observation," ensuring the continuous and efficient operation of the refrigeration system, reducing energy consumption, and ensuring the dimensional stability of printed parts.

[0025] Furthermore, a thermostat is installed on the box, and the thermostat includes a temperature sensor and a thermostat body. The temperature sensor is installed inside the box, and the thermostat body is installed outside the box; a relay is connected to the power supply of the compressor, and the temperature sensor and the relay are both electrically connected to the thermostat body.

[0026] Beneficial Effect: A temperature sensor monitors the chamber's temperature in real time and transmits this data to the thermostat. When the chamber's temperature rises to a set threshold due to heat release during the printing process (e.g., nozzle heating and material melting), the thermostat automatically connects the compressor via a relay, initiating the refrigeration cycle. When the temperature drops below the target value, the relay disconnects the compressor, halting cooling. This "monitor-judgment-execute" closed-loop control logic stabilizes the chamber's temperature within a specified tolerance, precisely matching the glass transition temperature of the elastic material. This prevents repeated freezing and relaxation of material segments due to temperature fluctuations, thereby ensuring the rigidity and dimensional accuracy of the printed part.

[0027] Furthermore, it also includes a defrost unit for defrosting the evaporator. The defrost unit is a direct cooling defrost module or an air cooling defrost module. The direct cooling defrost module includes a heating wire arranged near the evaporator; the air cooling defrost module includes a fan installed on one side of the evaporator.

[0028] Beneficial effects: The defrost unit in this solution solves the problem of decreased refrigeration efficiency caused by evaporator frosting, providing a key guarantee for the continuous and efficient operation of elastic material 3D printing equipment.

[0029] Furthermore, it also includes a drying and dehumidification unit, which is a rotary dehumidifier.

[0030] Benefits: The rotary dehumidifier uses a honeycomb-shaped moisture-absorbing rotor (containing materials such as activated silica gel and molecular sieves) to continuously absorb moisture from the air inside the printing chamber, maintaining a low humidity level within the chamber, keeping it consistently below 50% RH. In low-temperature printing environments, this reduced moisture content in the air fundamentally reduces the risk of frost / condensation on the evaporator, cooling fins, and printed parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 This is a structural schematic diagram of an embodiment of a 3D printing device of the present invention; Figure 2 This is a schematic structural diagram of another embodiment of a 3D printing device according to the present invention; Figure 3 This is a structural schematic diagram of a 3D printing device in one embodiment of the present invention after a fan is added to the condenser.

[0032] Markings and corresponding parts names in the accompanying drawings: Cabinet 1, door body 2, sealing strip 201, door handle 3, compressor 4, condenser 5, heat sink 501, condenser tube 502, evaporator 6, evaporator tube 601, heat dissipation fin 602, print head 7, print model 8, print platform 9, low-pressure pipe 10, high-pressure pipe 11, throttling component 12, material supply system 13, fan 14. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0034] As an embodiment of the present application, Figure 1 As shown, this embodiment provides a 3D printing device, including a box body 1 and a door body, the door body encloses the box body 1, and in this embodiment, a door handle 3 is connected to the outside of the door body.

[0035] A printing unit for printing elastic materials is installed in the box 1. The printing unit adopts the existing 3D printing technology principle. The internal components of the printing unit (such as motors, belts, bearings, lubricating oil, grease; cables; limit sensors, pressure sensors, etc.) are all made of low-temperature resistant materials.

[0036] A 3D printing device in this embodiment also includes a low-temperature temperature control unit, which includes a compressor 4, a condenser 5, a throttling component 12, an evaporator 6, a low-pressure pipe 10 and a high-pressure pipe 11; the evaporator 6 is installed in the box body 1 by screws or welding, and the compressor 4 and the condenser 5 are installed outside the box body 1. In this embodiment, an inwardly recessed space is provided in the lower right corner of the box body 1, and the space is used to install the compressor 4, so that the compressor 4 is fixed on the box body 1, which is convenient for overall movement; in this embodiment, the condenser 5 is located at the back, sides or bottom of the box body 1. When the condenser 5 is installed at the bottom of the box body 1, the inwardly recessed space set in the lower right corner of the box body 1 can be enlarged, and the condenser 5 is also installed in this space, so that the entire device occupies less space and has a more beautiful appearance.

[0037] The outlet of the evaporator 6 is connected to the air intake of the compressor 4 through a low-pressure pipe 10; the exhaust port of the compressor 4 is connected to the inlet of the condenser 5 through a high-pressure pipe 11, and the inlet of the evaporator 6 and the outlet of the condenser 5 are connected through a throttling component 12.

[0038] The compressor 4 compresses the low-temperature, low-pressure refrigerant gas into a high-temperature, high-pressure gas to drive the refrigeration cycle.

[0039] The high-pressure pipe 11 and the low-pressure pipe 10 are the "blood vessels" connecting the core components, responsible for the transportation of refrigerant on the high-pressure side and the low-pressure side respectively. The high-pressure pipe 11 is a pipeline for transporting high-pressure refrigerant (usually a copper pipe with strong pressure resistance), connecting the exhaust port of the compressor 4 and the inlet of the condenser 5. The compressor 4 compresses the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous refrigerant through mechanical work, and discharges it into the high-pressure pipe 11 through the exhaust port of the compressor 4. The high-temperature, high-pressure gaseous refrigerant is transported to the inlet of the condenser 5 through the high-pressure pipe 11 and enters the condenser 5. At this time, the condenser 5 is cooled by air convection or fan 14, dissipating the heat in the refrigerant into the outside air, and the refrigerant gradually condenses into a high-pressure liquid due to heat release.

[0040] The low-pressure pipe 10 is a pipe for transporting low-pressure refrigerant (the pressure requirement is lower than that of the high-pressure pipe 11, but it must be resistant to low temperatures). It connects the outlet of the evaporator 6 and the air intake of the compressor 4. After being throttled and reduced in pressure by the throttling component 12, the low-temperature, low-pressure gas-liquid mixed refrigerant enters the evaporator 6, where it absorbs heat from the cabinet 1 (to achieve cooling) and completely evaporates into a low-temperature, low-pressure gaseous refrigerant. This gaseous refrigerant enters the low-pressure pipe 10 through the outlet of the evaporator 6. The low-temperature, low-pressure gaseous refrigerant is transported to the air intake of the compressor 4 through the low-pressure pipe 10, where it is sucked in and compressed again by the compressor 4, entering the next round of refrigeration cycle.

[0041] In one embodiment, the printing unit is an existing 3D printing device, which includes a printing nozzle 7 (hot end), a material supply system 13 (cold end), a printing platform 9, a motion control system and an extrusion drive mechanism.

[0042] Solid filamentous elastic material (such as PU / PEBA) is squeezed into the hot end by the gears at the cold end, melted by the heating block, and extruded from the nozzle; at the same time, the motion system (such as XYZ three-axis linkage) controls the print head 7 to move according to the G-code path generated by the slicing software, depositing the molten material layer by layer on the printing platform 9. After each layer is completed, the platform moves down by a layer thickness (usually 0.1-0.3mm), and the stacking cycle continues until a printed model 8 (a three-dimensional solid) is formed.

[0043] The printing unit can also be a photocurable resin extrusion printing system, including a print head 7, a curing lamp, a material supply system 13, a printing platform 9, a motion control system, and an extrusion drive mechanism (such as a metering pump). The photocurable resin can be single-component, dual-component, or multi-component. The liquid photocurable resin material is fed into the print head 7 by a drive mechanism (such as a metering pump) and extruded from the nozzle; at the same time, the motion system (such as an XYZ three-axis linkage) controls the print head 7 to move according to the G code path generated by the slicing software. The curing lamp irradiates the extruded resin material to solidify it, and the material is deposited layer by layer on the printing platform 9. After each layer is completed, the platform moves down by a layer thickness (usually 0.1-0.3mm), and the stacking cycle continues until a three-dimensional solid is formed. After the photocurable resin is extruded and printed, if its physical and mechanical properties do not meet the requirements for use, it can be post-cured (such as heat curing, moisture curing, or light curing) to improve its physical and mechanical properties.

[0044] In one embodiment, a condenser tube 502 and a plurality of heat sinks 501 are provided in the condenser 5. The plurality of heat sinks 501 are fixed inside the condenser 5, and the condenser tube 502 is coiled in a serpentine shape inside the condenser 5. This can increase the contact area between the condenser tube 502 and the heat sink 501, thereby increasing the heat dissipation. In this embodiment, the plurality of heat sinks 501 are spaced apart and connected to the condenser tube 502. In this embodiment, the heat sink 501 is typically a thin metal sheet (such as an aluminum sheet or a copper sheet) and is fixed to the serpentine condenser tube 502 by welding, expansion joint, or snap-fitting to ensure close contact between the two (reducing thermal resistance). This connection allows the heat of the high-temperature refrigerant in the condenser tube 502 to be efficiently transferred to the heat sink 501.

[0045] In one embodiment, Figure 3 As shown, a condenser tube 502 and a plurality of heat sinks 501 are provided in the condenser 5. The plurality of heat sinks 501 are fixed inside the condenser 5. The condenser tube 502 is coiled in a serpentine shape in the condenser 5. In this embodiment, a fan 14 is provided in the condenser 5. The condenser 5 is air-cooled by the fan 14, which can quickly release heat into the air and reduce the heat exchange time.

[0046] In one embodiment, Figure 1 As shown, in this embodiment, the evaporator 6 includes an evaporation tube 601, which is coiled in a serpentine shape within the evaporator 6. The evaporator 6 is installed on one or more surfaces of the inner layer of the housing 1. The serpentine design of the evaporation tube 601 in this embodiment extends the flow path of the low-temperature, low-pressure refrigerant within the limited space within the evaporator 6, thereby increasing the heat exchange time between the refrigerant and the air within the printing chamber (housing 1).

[0047] In one embodiment, Figure 2As shown, the evaporator 6 also includes a plurality of heat dissipating fins 602 and a bracket. The plurality of heat dissipating fins 602 are connected to the evaporating tube 601 at intervals. The heat dissipating fins 602 and the evaporating tube 601 are fixed to form an evaporating assembly by welding, expansion or snapping. The evaporating assembly is fixed on the bracket, and the bracket is fixed in the box body 1.

[0048] The multiple heat dissipation fins 602 connected to the evaporation tube 601 at intervals greatly expand the heat exchange area, so that the heat in the box body 1 can be quickly transferred to the refrigerant in the evaporation tube 601 through the heat dissipation fins 602. The efficiency of the liquid refrigerant absorbing heat and evaporating in the evaporation tube 601 is significantly improved, and the temperature of the printing box body 1 can be reduced to the target value in a short time, providing an instant response low-temperature field for the low-temperature curing of the elastic material.

[0049] In one embodiment, the throttling component 12 is a capillary tube or an expansion valve, which throttles and reduces pressure to control the flow rate of the liquid refrigerant. The capillary tube is a slender copper tube or stainless steel tube with a uniform inner diameter, without any moving parts and with an extremely simple structure. It is usually coiled into a spiral shape, with both ends directly connected to the condenser 5 (high-pressure side) and the evaporator 6 (low-pressure side). Throttling is achieved by utilizing the resistance effect of the fluid flowing in the slender pipe; the expansion valve is an adjustable throttling component 12, which can dynamically adjust the flow rate according to the state of the refrigerant at the outlet of the evaporator 6.

[0050] In one embodiment, the box body 1 and the door body 2 both include an inner layer, an interlayer and an outer layer. The inner layer and the outer layer are both metal shells or plastic shells, and the interlayer is an insulation layer. Specifically, the interlayer is a polyurethane foam insulation layer that isolates the heat exchange between the inside and the outside.

[0051] In one embodiment, a sealing strip 201 is provided on the edge contour where the door body 2 contacts the box body 1. The sealing strip 201 is made of a magnetic rubber sealing ring. The sealing strip 201 can ensure the airtightness of the contact between the box body 1 and the door body 2, thereby preventing cold air from leaking out and hot air from entering.

[0052] In one embodiment, an observation window is provided on the door body 2 , and the observation window is a transparent observation window, so that the internal situation of the box body 1 can be conveniently observed through the observation window without opening the door body 2 .

[0053] In one embodiment, a lighting lamp is provided in the box body 1, which is automatically turned on when the door is opened and automatically turned off when the door is closed through a combination of a mechanical trigger device and a circuit switching switch.

[0054] Specifically: A door-controlled micro switch (or contact switch) is installed at the connection between the door body 2 and the box body 1, which is composed of a "trigger rod", "internal contacts" and "spring". The door body 2 and the box body 1 are hinged.

[0055] When the door is opened: the door body 2 rotates around the hinge, releasing the pressure on the trigger rod, and the spring inside the switch springs up, closing the contacts, conducting the circuit, and the light is energized and illuminated; When closing the door: the door body 2 squeezes the trigger rod, pushing the internal mechanical structure to disconnect the contacts, cut off the circuit, and turn off the power to the light.

[0056] In one embodiment, a thermostat (not shown in the figure) is installed on the box body 1, and the thermostat includes a temperature sensor and a thermostat body. The temperature sensor is installed inside the box body 1, and the thermostat body is installed outside the box body 1; a relay is connected to the power supply of the compressor 4, and the temperature sensor and the relay are both electrically connected to the thermostat body.

[0057] The temperature sensor is installed in the box 1 to monitor the temperature inside the box in real time (commonly used thermistors, thermocouples, etc., the accuracy varies with demand); The main body of the thermostat consists of a setting panel (where the user enters the target temperature), a comparison circuit (which compares the measured temperature with the set temperature), and a control module (which outputs instructions); Compressor 4, the power source for the refrigeration system, directly affects the temperature inside the cabinet (cooling occurs when running, and rising when stopped). The temperature sensor transmits a high-temperature signal to the thermostat, which detects the need for cooling and outputs a start signal (e.g., a relay closure), energizing compressor 4. During this time, the refrigeration system operates (the refrigerant circulates and absorbs heat), and the temperature inside cabinet 1 gradually decreases.

[0058] The temperature sensor transmits a signal indicating that the temperature has reached the specified level. The thermostat determines that cooling is no longer needed and outputs a stop signal (the relay is disconnected), shutting down compressor 4. The temperature inside cabinet 1 slowly rises due to factors such as external heat leakage until the start condition is triggered again, thus completing the cycle. This process is automated through "temperature differential triggering," eliminating the need for manual intervention and maintaining the cabinet temperature within the set range.

[0059] In this embodiment, the compressor 4 is automatically started and stopped to maintain the set temperature, and the temperature inside the printer housing 1 is controlled to be -90°C to 15°C.

[0060] In one embodiment, the temperature of the printer housing 1 is controlled at a temperature between -60°C and 0°C. In another embodiment, the temperature of the printer housing 1 is more preferably controlled at a temperature between -40°C and -10°C.

[0061] In one embodiment, a 3D printing device further includes a defrost unit for defrosting the evaporator 6. The defrost unit is a direct-cooling defrost module or an air-cooling defrost module. In this embodiment, a controller is mounted on the housing 1, and the direct-cooling defrost module or the air-cooling defrost module is electrically connected to the controller. The controller has an operation interface that integrates functions such as temperature setting, mode switching, printing, leveling, and light switching.

[0062] The direct cooling defrost module includes a heating wire arranged near the evaporator 6, a defrost sensor (such as a temperature sensor, a frost thickness sensor), and a timing module, which melts the frost regularly. The principle is: the frost on the surface of the evaporator 6 is melted by active heating; the heating wire is directly attached to or wrapped around the coil surface of the evaporator 6 (such as in the gap of the serpentine tube of the evaporator 6), or fixed on a bracket below or around the evaporator 6 to ensure that heat can be efficiently transferred to the frosted area of ​​the evaporator 6. The heating wire is connected to the controller on the box body 1 through a wire, is controlled by the defrost sensor or the timing module, and is interlocked with the compressor 4 (the compressor 4 stops working during defrosting to avoid conflict between heating and cooling); The air-cooled defrost module includes a fan mounted on one side of the evaporator 6, which forces cold air to circulate and prevent frost. The fan is typically mounted on one side of or directly in front of the evaporator 6 (e.g., at the air inlet or outlet of the evaporator 6), forming an "evaporator 6 - fan" airflow path: After cooling the air through the evaporator 6, the fan forces the air to various areas within the cabinet, then flows back to the evaporator 6 through the return air port, forming a closed-loop circulation. The fan and evaporator 6 are not mechanically connected, but airflow is connected through air duct structures on the cabinet 1 (e.g., air guides and hoods), ensuring that all air flows through the evaporator 6. The fan's motor is connected to the controller via wires and operates in conjunction with the compressor 4 and the defrost heater (if present). The fan and compressor 4 operate synchronously during cooling and can be paused during defrosting.

[0063] In one embodiment, a 3D printing device further includes a drying and dehumidifying unit for preventing frost from forming in the printing box 1. The drying and dehumidifying unit is used to control the humidity in the box 1 to be less than 50% RH. In this embodiment, the drying and dehumidifying unit is a rotary dehumidifier.

[0064] The rotary dehumidifier is a state-of-the-art technology. Its core structure comprises a honeycomb-shaped moisture-absorbing rotor (made of a ceramic fiber carrier composited with a moisture-absorbing material such as activated silica gel or molecular sieve), a treatment fan, a regeneration fan, a regeneration heater (electrically or steam-heated), a sealed partition (dividing the rotor into a treatment zone and a regeneration zone), and a control system. Its operating principle is based on a cycle of physical adsorption and thermal energy regeneration: when moist air enters the treatment zone (approximately a 270° sector of the rotor), moisture is absorbed by the moisture-absorbing material, and dry air is output. Simultaneously, the rotor rotates at a speed of 8-18 rpm, transferring the moisture-saturated portion into the regeneration zone (approximately a 90° sector). This portion is then backwashed with high-temperature regeneration air at 100-140°C, desorbing and discharging moisture, restoring the rotor's moisture absorption capacity and achieving continuous dehumidification. This maintains a low humidity level inside the printer housing 1, with the drying system capable of controlling the humidity to less than 50% RH.

[0065] In another embodiment, the drying and dehumidification unit in this embodiment is a dehumidification bag, which has an adsorption material such as a desiccant inside. The dehumidification bag is placed inside the box 1 and mainly absorbs moisture in the box 1 through the adsorption material inside the dehumidification bag to achieve the purpose of dehumidification and drying.

[0066] During the printing of elastic materials, the present invention operates in a closed structure. The temperature within the printer housing 1 is lower than the glass transition temperature of the printed material. The printed area remains at a low temperature, freezing the chain motion within the amorphous or semi-crystalline structure of the material, resulting in rigidity and low deformation. This significantly increases the speed of the print head 7. Furthermore, the drying system maintains a controlled humidity of less than 50% RH to prevent frost formation within the print chamber, significantly exceeding the printing speed of traditional FDM 3D printing, reaching speeds 10 to 15 times faster than conventional 3D printing. For example, the printing time for elastic shoes can be reduced from 90-104 hours to 7-11 hours. This significantly improves production efficiency and reduces time costs, making mass production of elastic materials possible through 3D printing.

[0067] It should be noted that the above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A 3D printing device, comprising a box and a door, wherein the door closes the box, and a printing unit for printing elastic material is installed in the box, characterized in that: It also includes a low-temperature temperature control unit, which includes a compressor, a condenser, a throttling component, an evaporator, a low-pressure pipe and a high-pressure pipe; the evaporator is installed in the box, and the compressor and the condenser are installed outside the box; The outlet of the evaporator is connected to the air intake of the compressor through the low-pressure pipe; the exhaust port of the compressor is connected to the inlet of the condenser through the high-pressure pipe, and the inlet of the evaporator and the outlet of the condenser are connected through the throttling component.

2. A 3D printing device according to claim 1, characterized in that: The condenser is provided with a condensing tube and a plurality of heat sinks, the plurality of heat sinks are fixed inside the condenser, the condensing tube is coiled in a serpentine shape inside the condenser, the plurality of heat sinks are distributed at intervals and connected to the condensing tube, and a fan is provided inside the condenser.

3. A 3D printing device according to claim 1, characterized in that: The evaporator includes an evaporation tube, which is coiled in a serpentine shape inside the evaporator. The evaporator is laid on one or more surfaces of the inner layer of the box.

4. The 3D printing device according to claim 1, characterized in that: The throttling component is a capillary tube or an expansion valve.

5. The 3D printing device according to claim 1, characterized in that: The box body and the door body both include an inner layer, an interlayer and an outer layer. The inner layer and the outer layer are both metal shells or plastic shells, and the interlayer is a heat-insulating layer.

6. The 3D printing device according to claim 1, characterized in that: A sealing strip is provided on the edge contour where the door body contacts the box body.

7. The 3D printing device according to claim 1, characterized in that: An observation window is provided on the door body, and the observation window is a transparent observation window.

8. A 3D printing device according to any one of claims 1 to 7, characterized in that: A thermostat is installed on the box body, and the thermostat includes a temperature sensor and a thermostat body. The temperature sensor is installed inside the box body, and the thermostat body is installed outside the box body; a relay is connected to the power supply of the compressor, and the temperature sensor and the relay are both electrically connected to the thermostat body.

9. A 3D printing device according to any one of claims 1 to 7, characterized in that: It also includes a defrost unit for defrosting the evaporator. The defrost unit is a direct cooling defrost module or an air cooling defrost module. The direct cooling defrost module includes a heating wire arranged near the evaporator; the air cooling defrost module includes a fan installed on one side of the evaporator.

10. A 3D printing device according to any one of claims 1 to 7, characterized in that: It also includes a drying and dehumidification unit, which is a rotary dehumidifier or a dehumidification bag.

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