Method for cleaning nozzle of 3D printer, and 3D printer

Abstract

Disclosed in the present application are a method for cleaning a nozzle of a 3D printer, and a 3D printer. The 3D printer comprises a nozzle and an extruder. The method comprises: acquiring current printing filament information of a nozzle, and flow channel state information of the nozzle, wherein the flow channel state information of the nozzle at least comprises information indicating the clogging degree of the nozzle, and the current printing filament information at least comprises filament type information of a filament currently extruded from the nozzle; and executing nozzle purging on the basis of the flow channel state information of the nozzle. In the present application, a purging or cold-pull operation can be executed on the basis of flow channel state information of a nozzle, and factors such as variations in extrusion resistance are comprehensively taken into consideration, such that the nozzle is cleaned in a timely manner; and the high-elastic-state characteristic of a cleaning filament is utilized to effectively remove impurities from the nozzle.

Description

A method for cleaning the nozzle of a 3D printer and the 3D printer itself.

[0001] This application claims priority to Chinese Patent Application No. 202510358848.X, filed on March 25, 2025, entitled "A Method for Cleaning the Nozzle of a 3D Printer and a 3D Printer", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of 3D printing, and in particular to a nozzle cleaning method for a 3D printer and a 3D printer, which can effectively determine the nozzle flow channel status and clean the nozzle to ensure the normal operation and printing quality of the 3D printer. Background Technology

[0003] 3D printers build 3D models by heating and melting filaments (such as PLA / ABS filaments) to stack layers. During the 3D printing process, nozzle clogging is a significant factor affecting print quality and efficiency. Different types of printing filaments, due to differences in their physical properties (such as glass transition temperature and fluidity), can easily remain and solidify within the nozzle channels, leading to nozzle clogging.

[0004] Existing 3D printer nozzle cleaning methods are often not intelligent or efficient enough. They cannot accurately determine the degree of blockage in the nozzle flow channel, nor can they take appropriate cleaning measures. Therefore, it is necessary to study this technical problem, especially to conduct in-depth research on the flow channel status of the nozzle, in order to improve the reliability and quality of printing. Summary of the Invention

[0005] This application provides a method for cleaning the nozzle of a 3D printer and a 3D printer itself. The working system of a 3D printer generally includes the following components: a filament loaded in a hopper is connected to an extruder; the extruder feeds the filament into the nozzle and deposits the molten filament onto a worktable at an appropriate temperature; and a printed model is obtained by stacking layers. The 3D printer may also include a motion system that drives the print head, which houses the extruder and nozzle, to move. The worktable can also move relative to the print head. Through the coordinated movement between the print head and the worktable, three degrees of freedom of movement are achieved, thereby enabling the printing of a three-dimensional model.

[0006] The nozzle cleaning method for a 3D printer provided in this application includes obtaining the current printing filament information and the nozzle flow channel status information. The nozzle flow channel status information includes at least information indicating the degree of nozzle blockage, and the current printing filament information includes at least the filament type information of the current extruded filament of the nozzle.

[0007] The nozzle flushing is performed based on the nozzle flow channel status information. The nozzle flushing includes controlling the nozzle temperature at a preset flushing temperature and extruding a cleaning filament into the nozzle using an extruder. The cleaning filament has at least a high elasticity characteristic.

[0008] Obtain the current filament information and printhead flow path status information of the printhead. The printhead flow path status information includes at least information indicating the degree of printhead clogging, and the current filament information includes at least the type of filament being extruded by the printhead. Obtaining this information can provide a basis for subsequent printhead cleaning operations.

[0009] After numerous experiments, the inventors discovered that printing consumables with high elasticity can effectively adhere to impurities remaining on the inner wall of the printhead, and thus have a certain probability of removing the impurities, thereby improving the flow path of the printhead.

[0010] Furthermore, the extruder includes an extrusion motor and an extrusion wheel. The extrusion motor is connected to the extrusion wheel for transmission. The extrusion wheel is used to feed or retract filament into the printhead. The printhead flow channel status information includes information on the extrusion resistance experienced by the filament in the current printing state, and outputs abnormal information on the printhead flow channel status.

[0011] In some embodiments, the printhead flow channel status information includes outputting printhead flow channel status abnormality information based on the extrusion resistance information experienced by the current filament during printing. Specifically, this can be achieved by pre-calibrating to obtain the extrusion resistance threshold under different extrusion flow rates when the extrusion is normal. If the extrusion resistance exceeds the extrusion resistance threshold when extruding the current printing filament, printhead flow channel status abnormality information is output. The extrusion resistance can be measured or read using various methods.

[0012] In some embodiments, the extrusion motor torque range under normal extrusion conditions is obtained at different extrusion flow rates; when the extrusion motor torque exceeds the extrusion motor torque range during the extrusion of the current printing filament, printhead flow channel status abnormality information is output. In other words, if the extrusion motor torque exceeds the extrusion motor torque range during the extrusion of the current printing filament, printhead flow channel status abnormality information is output, indicating that the printhead flow channel status has deteriorated, resulting in increased extrusion resistance.

[0013] Specifically, the extrusion motor can be a servo motor, a torque motor, a brushless motor or a brushed motor with a torque sensor, or a stepper motor whose torque is indirectly estimated by current monitoring. It is understood that since the extrusion motor is connected to the extrusion wheel drive to apply the extrusion force to the printed filament, measuring the working torque of the extrusion motor can directly or indirectly reflect the extrusion resistance.

[0014] In some embodiments, image information of the nozzle extrusion fluid morphology under different extrusion flow rates when the extrusion state is normal is obtained, and an image evaluation domain is planned based on the image information of the nozzle extrusion fluid morphology. When extruding the current printed filament, image information of the nozzle ejection fluid state is obtained. If the nozzle ejection fluid state exceeds the image evaluation domain, nozzle flow channel state abnormality information is output, which indicates that the nozzle flow channel state has deteriorated, resulting in increased extrusion resistance.

[0015] In some embodiments, a printhead displacement sensor is also included. During printing, the printhead is displaced under the action of the extruded filament, and the sensor acquires the printhead displacement range under different extrusion flow rates when the extrusion is normal. If the printhead displacement exceeds the printhead displacement range when extruding the current printing filament, the sensor outputs printhead flow channel status abnormality information. For example, when the normal extrusion flow rate is 8 mm / s, the printhead displacement range is ±0.05 mm. If the actual printhead displacement reaches 0.1 mm, the printhead flow channel status is determined to be abnormal.

[0016] Further, as shown in Figure 3, the preset flushing temperature includes a first preset flushing temperature. Performing printhead flushing according to the printhead flow channel state information includes: extruding cleaning filaments into the printhead at the first preset flushing temperature, wherein the first preset flushing temperature is higher than the glass transition temperature of the current printing filaments, and the cleaning filaments are in a flow state.

[0017] It is understood that the printhead cleaning method of this application is implemented during the printing process. Obtaining the current printing filament information of the printhead can provide relevant process parameter information of the current printing filament, thereby adopting different control methods and processes to ensure the effectiveness of printhead cleaning.

[0018] In some embodiments, the current printing filament information includes at least the filament type information of the current extruded filament of the printhead. Based on the filament type of the current extruded filament, the glass transition temperature of the current extruded filament can be determined. Above the glass transition temperature, the current extruded filament will change from a solid state to a highly elastic state (also known as a viscoelastic state or rubber state). In this state, the adhesion force between the cleaning filament in a fluid state and the current extruded filament will be greater than the adhesion force between the current extruded filament and the inner wall of the printhead (usually metal). In other words, cleaning consumables can be used as organic solvents to dissolve impurities in the hot end, and then the printhead can be cleaned by rinsing.

[0019] It is understandable that the first preset rinsing temperature can be the glass transition temperature of the current extrusion filament, or it can be higher than the glass transition temperature of the current extrusion filament. Performing extrusion at a temperature higher than the glass transition temperature of the current filament can make the cleaning filament soften and flow better, making it easier to remove residual substances in the nozzle channel.

[0020] In some embodiments, the cleaning filament can be PLA or PETG material. PLA filament is in a fluid dynamic state at 190-230°C, and PETG filament is in a fluid dynamic state at 220-250°C. At these temperatures, PLA and PETG can print normally. If the current extrusion filament is TPU, the glass transition temperature of TPU filament is lower than the fluid dynamic temperature of PLA and PETG. In this case, the first preset flushing temperature is the same as that of PLA or PETG, ensuring that the cleaning filament can flow in the printhead to remove impurities. Similarly, if the current extrusion filament is PPS, the glass transition temperature of PPS filament is higher than the fluid dynamic temperature of PLA and PETG. In this case, the first preset flushing temperature needs to be the same as the glass transition temperature of PPS. At this temperature, PLA and PETG are also in a fluid dynamic state, ensuring that the cleaning filament can flow in the printhead to remove impurities.

[0021] Furthermore, in some embodiments, performing nozzle flushing based on nozzle flow channel status information may further include obtaining the cumulative flushing amount of cleaning material extruded onto the nozzle at a first preset flushing temperature within a preset flushing time, and outputting nozzle flow channel status error information if the cumulative flushing amount is lower than a minimum flushing threshold.

[0022] By controlling the extrusion motor to drive the extrusion wheel with constant torque or periodically fluctuating torque within a certain time, the current printing filament can be flushed and cleaned. If enough current printing filament cannot be extruded within the preset time, it indicates that the nozzle flow channel condition has deteriorated significantly, making it impossible to flush the filament or making flushing very difficult.

[0023] In other embodiments, the torque information or rotational speed of the extruder is obtained when the cleaning filament is extruded into the nozzle at a first preset flushing temperature. If the torque information of the extruder is greater than the preset flushing torque or the rotational speed of the extruder is lower than the preset rotational speed, the nozzle flow channel status error information is output.

[0024] Specifically, in some cases, the printhead flow path condition deteriorates so severely that it can no longer be flushed by cleaning the cleaning line or flushing is extremely difficult. In these cases, continuing to flush the printhead is meaningless and may cause further damage to the printer's performance, such as clogging of the extrusion wheel. When this happens, a printhead flow path status error message can be output and flushing can be stopped. The printhead flow path status error message can also be pushed to the user or terminal device via the display screen or server.

[0025] Furthermore, as shown in Figure 3, the process of performing nozzle flushing based on the nozzle flow channel status information also includes: calculating the cumulative flushing amount of cleaning material extruded into the nozzle at the first preset flushing temperature; and controlling the nozzle temperature to switch from the first preset flushing temperature to the second preset flushing temperature when the cumulative flushing amount is not lower than the minimum flushing threshold, and extruding the cleaning material into the nozzle at the second preset flushing temperature, wherein the cleaning material is in a flow state at the second preset flushing temperature.

[0026] In some embodiments, the nozzle cleaning method further includes, when the current printing filament is a flexible printing filament, obtaining extrusion resistance information of the current filament in the printing state.

[0027] In some embodiments, when the printing consumption exceeds the warning threshold, the extrusion resistance information of the current filament in the printing state is obtained, wherein the printing consumption is the cumulative amount of the current printing filament used since the last time the nozzle flow channel status abnormal information was output.

[0028] As mentioned earlier, with the accumulation of printing time, impurities or residual consumables will inevitably adhere to the inner wall of the printhead, leading to the deterioration of the printhead flow channel. By counting the amount of printing after the last cleaning, users can be reminded to clean the printhead in a timely manner, thereby ensuring that the printer is in good working condition.

[0029] Furthermore, as shown in Figure 2, the nozzle cleaning method for a 3D printer provided in this application further includes a cold-drawing operation after nozzle flushing. The cold-drawing operation involves controlling the nozzle temperature to switch to the high-elasticity temperature of the cleaning filament and controlling the retraction of the cleaning filament from the nozzle. Polymer materials exhibit excellent high-elasticity characteristics between the glass transition temperature and the viscous flow transition temperature, meaning they possess high elasticity and can deform. The inventors discovered that, in the high-elasticity state, cooling during the stretching and thinning process of polymer materials can increase the filament strength, thereby carrying out all the polymer material within the nozzle. Impurities in the hot end are removed by the adhesion of the polymer material to impurities on the nozzle wall. In addition, controlling the retraction of the cleaning filament from the nozzle ensures that the movement direction of the cleaning material within the nozzle is opposite to the flushing direction, thus removing impurities that are difficult to remove during flushing, thereby significantly improving the nozzle cleaning effect.

[0030] In some embodiments, when the cleaning liner is PLA or PETG, the cold-drawing operation includes controlling the nozzle temperature to switch to 75-95°C and controlling the retraction of the cleaning liner from the nozzle. The inventors discovered through experiments that when using PLA or PETG as cleaning consumables, within this temperature range, the cleaning consumables are in a highly elastic state and not easily broken, effectively carrying out all the polymer material inside the nozzle.

[0031] In some embodiments, the cleaning cable is a light-colored cable, which makes it easier to observe whether impurities inside the nozzle are brought out during flushing or re-extraction of waste materials, allowing users to judge the cleaning effect and the number of cleaning cycles.

[0032] In some embodiments, the cleaning filament is PLA or PETG. PLA or PETG exhibits excellent elasticity between the glass transition temperature and the viscous flow transition temperature, meaning the polymer material possesses high elasticity and can deform. Cooling during the stretching and thinning process increases the filament strength, thereby carrying out all the polymer material within the nozzle. Impurities in the hot end are removed by the adhesion of the polymer material to impurities on the nozzle wall.

[0033] In some embodiments, the current printing filament and the cleaning filament are the same type. In this case, the printhead flushing and / or cold-drawing operations described above can be performed directly.

[0034] In some embodiments, the device may further include a hopper, to which the printer is connected. The hopper may hold multiple or various printing filaments. The extruder is controlled to extrude cleaning filaments, including target cleaning filaments determined based on current printing filament information, into the printhead. The printhead cleaning method also includes:

[0035] If the current printing filament and the target cleaning filament are of different types, obtain the type information of at least one filament placed in the hopper. If the types of multiple filaments placed in the hopper include the type of the target cleaning filament, cut off the current printing filament and remove the current printing filament from the printhead, and feed the target cleaning filament from the hopper to the printhead to perform printhead rinsing.

[0036] It is understandable that printers or cartridges can be combined to achieve printing with different filament combinations. The workflow can involve a filament cutting device on the printer or cartridge cutting off the current printing filament and retracting it to a suitable position, such as before the junction point of the cartridge or filament converging device, before feeding the next printing filament into the printhead, thus achieving filament switching. When suitable clean filaments are stored in the cartridge and the current printing filament differs from the intended clean filament, the current printing filament can be automatically cut off and the intended clean filament fed in. Subsequently, printhead rinsing and / or cold-drawing operations as described above can be performed.

[0037] This application provides a 3D printer, which includes the nozzle cleaning method described in any of the above claims.

[0038] This application also provides a computer-readable storage medium storing computer instructions, including instructions that, when executed on a computer, cause the computer to perform the above-described nozzle cleaning method for a 3D printer.

[0039] The printhead cleaning method provided in this application can perform flushing or cold drawing operations based on the printhead flow channel status information. Taking into account factors such as changes in extrusion resistance, the printhead is cleaned in a timely manner. By utilizing the high elasticity of the cleaning filament, impurities inside the printhead can be effectively cleaned, thereby improving printing quality and ensuring service life.

[0040] Additional aspects and advantages of embodiments of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of this application. Attached Figure Description

[0041] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein:

[0042] Figure 1 is a schematic diagram of the working system of a 3D printer according to an embodiment of this application;

[0043] Figure 2 is a flowchart illustrating a method for cleaning the nozzle of a 3D printer according to an embodiment of this application.

[0044] Figure 3 is another schematic flowchart of a nozzle cleaning method according to an embodiment of this application;

[0045] Figure 4 is a schematic diagram of the printhead printing or printhead rinsing state according to the embodiments of this application;

[0046] Figure 5 is a schematic diagram of the nozzle cold-drawing operation state according to the embodiment of this application;

[0047] Figure 6 is a schematic diagram of a typical material state of a polymer printing filament according to an embodiment of this application. Detailed Implementation

[0048] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the embodiments of this application, and should not be construed as limiting the embodiments of this application.

[0049] This application provides a method for cleaning the nozzle of a 3D printer. The 3D printer includes a nozzle and an extruder. The specific steps of the nozzle cleaning method include:

[0050] Figure 1 shows a schematic diagram of the working system 100 of the 3D printer according to an embodiment of this application. The printing filament 150 loaded on the hopper 140 is connected to the extruder 160. The extruder 160 feeds the printing filament 150 into the nozzle 120 and deposits the molten printing filament 150 onto the worktable 110 at an appropriate temperature. By stacking layers one by one, a printed model is obtained. The 3D printer may also include a motion system 130, which can drive the print head loaded with the extruder 160 and the nozzle 120 to move. The worktable 110 can also move relative to the print head. Through the motion coordination between the print head and the worktable 110, the three degrees of freedom of motion in three directions are realized, thereby realizing the printing of the three-dimensional model.

[0051] The hopper 140 can store or hold printing filaments 150. The hopper 140 can be a system that stores multiple printing filaments 150 and automatically conveys and recycles them. For example, the hopper 140 can have four troughs for storing rolled printing filaments 150, and feeds the filaments 150 to the 3D printer via a feeding / unfeeding mechanism. Specifically, the hopper 140 can use a multi-channel assembly to converge the feeding and unfeeding channels of multiple printing filaments 150 into a single feed tube, which is ultimately connected to the nozzle of the 3D printer. The printing filaments 150 can also be in the form of rolled filaments stored on a tray, which can be cylindrical or disc-shaped. Alternatively, the hopper 140 can be a simple tray or a mounting bracket for printing filaments 150, or simply refer to a tray for loading printing filaments.

[0052] As shown in Figure 4, the printhead 120 may include a cooling section 1201, a connecting section 1202, and a heating section 1203. It is understood that the cooling section 1201 has a lower temperature, and the printing filament 150 is in a solid state within it. Along the conveying direction of the printing filament 150, the extruder 160 is located before the cooling section 1201, feeding the printing filament 150 into the printhead 120 through friction or other forces. The heating section 1203 can undergo temperature changes, for example, by electromagnetic heating, contact heating, or contact heat transfer. It can also be cooled by natural cooling, airflow cooling, or liquid cooling. During printing, the printing filament 150 is heated to a molten state in the heating section 1203 and extruded by the extruder 160, thus achieving printing. The connecting section 1202 connects the cooling section 1201 and the heating section 1203 and is generally made of a material with low thermal conductivity.

[0053] As shown in Figure 2, the nozzle cleaning method for a 3D printer provided in this application includes:

[0054] S1: Obtain the current printing line information and printhead flow channel status information of the printhead.

[0055] The nozzle flow channel status information includes at least information indicating the degree of nozzle blockage, and the current printing filament information includes at least the filament type information of the filament currently being extruded by the nozzle.

[0056] S2: Perform nozzle flushing based on nozzle flow channel status information.

[0057] The nozzle rinsing process includes controlling the nozzle temperature at a preset rinsing temperature and extruding cleaning filaments into the nozzle using an extruder. The cleaning filaments have at least a high elasticity characteristic.

[0058] Obtain the current filament information and printhead flow path status information of the printhead. The printhead flow path status information includes at least information indicating the degree of printhead clogging, and the current filament information includes at least the type of filament being extruded by the printhead. Obtaining this information can provide a basis for subsequent printhead cleaning operations.

[0059] To enhance the functionality of 3D printing and improve material properties, various modifiers are often added to the printing filament. Different modifiers have different applicable operating temperatures, which can lead to component carbonization during printing, causing them to adhere to the inner wall of the nozzle. Furthermore, different filaments also have different operating temperatures. Printing a low-temperature filament after a high-temperature filament, without sufficient flushing, can also result in some high-temperature filament remaining on the inner wall of the nozzle. All of these situations can deteriorate the flow path of the nozzle, potentially leading to nozzle clogging in severe cases.

[0060] After numerous experiments, the inventors discovered that printing consumables with high elasticity can effectively adhere to impurities remaining on the inner wall of the printhead, and thus have a certain probability of removing the impurities, thereby improving the flow path of the printhead.

[0061] Furthermore, the extruder includes an extrusion motor and an extrusion wheel. The extrusion motor is connected to the extrusion wheel for transmission. The extrusion wheel is used to feed or retract filament into the printhead. The printhead flow channel status information includes information on the extrusion resistance experienced by the filament in the current printing state, and outputs abnormal information on the printhead flow channel status.

[0062] In some embodiments, the printhead flow channel status information includes outputting printhead flow channel status abnormality information based on the extrusion resistance information experienced by the current filament during printing. Specifically, this can be achieved by pre-calibrating to obtain the extrusion resistance threshold under different extrusion flow rates when the extrusion is normal. If the extrusion resistance exceeds the extrusion resistance threshold when extruding the current printing filament, printhead flow channel status abnormality information is output. The extrusion resistance can be measured or read using various methods.

[0063] In some embodiments, the extrusion motor torque range under normal extrusion conditions is obtained at different extrusion flow rates. If the extrusion motor torque exceeds this range when extruding the current printable filament, printhead flow channel status abnormality information is output. In other words, if the extrusion motor torque exceeds the range when extruding the current printable filament, printhead flow channel status abnormality information is output, indicating a deterioration in the printhead flow channel condition, leading to increased extrusion resistance. For example, at a normal extrusion flow rate of 5 mm / s, the extrusion motor torque range is 2-5 N·m. If the motor torque reaches 6 N·m during actual extrusion, the printhead flow channel status is determined to be abnormal.

[0064] Specifically, the extrusion motor can be a servo motor, a torque motor, a brushless motor or a brushed motor with a torque sensor, or a stepper motor whose torque is indirectly estimated by current monitoring. It is understood that since the extrusion motor is connected to the extrusion wheel drive to apply the extrusion force to the printed filament, measuring the working torque of the extrusion motor can directly or indirectly reflect the extrusion resistance.

[0065] In some embodiments, image information of the nozzle extrusion fluid morphology under different extrusion flow rates when the extrusion state is normal is obtained, and an image evaluation domain is planned based on the image information of the nozzle extrusion fluid morphology. When extruding the current printed filament, image information of the nozzle ejection fluid state is obtained. If the nozzle ejection fluid state exceeds the image evaluation domain, nozzle flow channel state abnormality information is output, which indicates that the nozzle flow channel state has deteriorated, resulting in increased extrusion resistance.

[0066] Specifically, under normal circumstances, the extruded filament should be continuous and uniform. If the image shows that the extruded filament is broken or uneven in thickness, the nozzle flow channel is considered abnormal. By calibrating the nozzle extrusion flow channel morphology at a specific extrusion flow rate, for example based on material properties such as fluid velocity, fluid angle, and viscoelastic fluid memory recovery effect, a healthy evaluation domain for the flow channel is planned. Then, a vision sensor installed on the tool head acquires images of the fluid state ejected from the nozzle. Based on the image information corresponding to the process parameters in the evaluation domain, it is determined whether the current printed filament exceeds this evaluation domain. If it does, the hot end state is considered abnormal, indicating that the nozzle flow channel condition has deteriorated, resulting in increased extrusion resistance.

[0067] In some embodiments, a printhead displacement sensor is also included. During printing, the printhead is displaced under the action of the extruded filament, and the sensor acquires the printhead displacement range under different extrusion flow rates when the extrusion is normal. If the printhead displacement exceeds the printhead displacement range when extruding the current printing filament, the sensor outputs printhead flow channel status abnormality information. For example, when the normal extrusion flow rate is 8 mm / s, the printhead displacement range is ±0.05 mm. If the actual printhead displacement reaches 0.1 mm, the printhead flow channel status is determined to be abnormal.

[0068] Specifically, the printhead may include a cooling section, a connecting section, and a heating section. The printhead is mounted on the printhead holder. By setting an eddy current induction coil, strain gauge, or other displacement sensor, the displacement of the printhead relative to the printhead holder during the extrusion process can be sensed. This can characterize the extrusion resistance of the filament in the current printing state. In some embodiments, an eddy current induction coil is set on the other of the printhead or the printhead holder, and a metal sheet corresponding to the eddy current induction coil is set on one of the printhead or the printhead holder. In this way, the displacement of the printhead relative to the printhead holder under the extrusion resistance can be sensed.

[0069] Further, as shown in Figure 3, the preset flushing temperature includes a first preset flushing temperature, and the nozzle flushing is performed according to the nozzle flow channel state information, including:

[0070] S21: Extrude cleaning material into the nozzle at the first preset flushing temperature.

[0071] The first preset rinsing temperature is higher than the glass transition temperature of the current printing filament, and the cleaning filament is in a fluid state.

[0072] It is understood that the printhead cleaning method of this application is implemented during the printing process. Obtaining the current printing filament information of the printhead can provide relevant process parameter information of the current printing filament, thereby adopting different control methods and processes to ensure the effectiveness of printhead cleaning.

[0073] In some embodiments, the current printing filament information includes at least the filament type information of the current extruded filament of the printhead. Based on the filament type of the current extruded filament, the glass transition temperature of the current extruded filament can be determined. Above the glass transition temperature, the current extruded filament will change from a solid state to a highly elastic state (also known as a viscoelastic state or rubber state). In this state, the adhesion force between the cleaning filament in a fluid state and the current extruded filament will be greater than the adhesion force between the current extruded filament and the inner wall of the printhead (usually metal). In other words, cleaning consumables can be used as organic solvents to dissolve impurities in the hot end, and then the printhead can be cleaned by rinsing.

[0074] Figure 4 illustrates the state of the printing filament 150 within the nozzle 120 during the printing process. In the cooling section, the printing filament is in a solid state; in the heating section, it can be in a molten state, filling the heating end, and can be extruded under the action of the extruder. Figure 6 shows a typical material state diagram of the polymer printing filament. It can be understood that as the temperature gradually increases, below the glass transition temperature, the polymer printing filament is in a glassy state, exhibiting solid properties and unable to flow. Between the glass transition temperature and the fluidization transition temperature, the material exhibits a highly elastic state (also known as viscoelastic or rubbery state). In this state, the material exhibits good elasticity, possessing deformability but unable to flow like a liquid. As the temperature further increases, the material enters a fluidized state, exhibiting good fluidity. During normal printing, the printing filament will be in a fluidized state to facilitate extrusion.

[0075] Understandably, the first preset rinsing temperature can be the glass transition temperature of the current extrusion filament, or it can be higher than the glass transition temperature of the current extrusion filament. Performing extrusion at a temperature higher than the glass transition temperature of the current filament can make the cleaning filament soften and flow better, making it easier to remove residual substances in the nozzle channel.

[0076] In some embodiments, the cleaning filament can be PLA or PETG material. PLA filament is in a fluid dynamic state at 190-230°C, and PETG filament is in a fluid dynamic state at 220-250°C. At these temperatures, PLA and PETG can print normally. If the current extrusion filament is TPU, the glass transition temperature of TPU filament is lower than the fluid dynamic temperature of PLA and PETG. In this case, the first preset flushing temperature is the same as that of PLA or PETG, ensuring that the cleaning filament can flow in the printhead to remove impurities. Similarly, if the current extrusion filament is PPS, the glass transition temperature of PPS filament is higher than the fluid dynamic temperature of PLA and PETG. In this case, the first preset flushing temperature needs to be the same as the glass transition temperature of PPS. At this temperature, PLA and PETG are also in a fluid dynamic state, ensuring that the cleaning filament can flow in the printhead to remove impurities.

[0077] Furthermore, in some embodiments, performing nozzle flushing based on nozzle flow channel status information may further include obtaining the cumulative flushing amount of cleaning material extruded onto the nozzle at a first preset flushing temperature within a preset flushing time, and outputting nozzle flow channel status error information if the cumulative flushing amount is lower than a minimum flushing threshold.

[0078] Specifically, the first preset flushing time can be 1 minute, 2 minutes, or 5 minutes. The minimum flushing threshold can be used to characterize the volume of the printed filament. For example, when the printed filament has a circular cross-section and a diameter of 1.75mm, the minimum flushing threshold can be any value between 6 and 12mm, such as 6mm, 7mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, 11mm, or 12mm. For example, if the preset flushing time is 30 seconds and the minimum flushing threshold is 8mm, and the cumulative flushing volume is only 5mm within 30 seconds, then the printhead flow channel state is determined to be incorrect.

[0079] By controlling the extrusion motor to drive the extrusion wheel with constant torque or periodically fluctuating torque within a certain time, the current printing filament can be flushed and cleaned. If enough current printing filament cannot be extruded within the preset time, it indicates that the nozzle flow channel condition has deteriorated significantly, making it impossible to flush the filament or making flushing very difficult.

[0080] In other embodiments, the torque information or rotational speed of the extruder is obtained when the cleaning filament is extruded into the nozzle at a first preset flushing temperature. If the torque information of the extruder is greater than the preset flushing torque or the rotational speed of the extruder is lower than the preset rotational speed, the nozzle flow channel status error information is output.

[0081] Specifically, in some cases, the printhead flow path condition deteriorates so severely that it can no longer be flushed by cleaning the cleaning line or flushing is extremely difficult. In these cases, continuing to flush the printhead is meaningless and may cause further damage to the printer's performance, such as clogging of the extrusion wheel. When this happens, a printhead flow path status error message can be output and flushing can be stopped. The printhead flow path status error message can also be pushed to the user or terminal device via the display screen or server.

[0082] Furthermore, as shown in Figure 3, performing nozzle rinsing based on nozzle flow channel status information also includes calculating the cumulative rinsing amount of cleaning material extruded into the nozzle at the first preset rinsing temperature:

[0083] S22: When the cumulative flushing volume is not lower than the minimum flushing threshold, control the nozzle temperature to switch from the first preset flushing temperature to the second preset flushing temperature, and extrude the cleaning filament into the nozzle at the second preset flushing temperature.

[0084] At the second preset rinsing temperature, the cleaning line is in a fluid state.

[0085] It is understandable that printhead flushing can be approximated as two-stage extrusion. In some embodiments, the glass transition temperature of the current printing filament is higher than the flow dynamic temperature of the cleaning consumable, that is, the first preset flushing temperature is higher than the second preset flushing temperature. At this time, the printhead flushing performed at the first preset flushing temperature is the high-temperature flushing stage. After the high-temperature flushing length reaches the target, the printhead temperature can be reduced to the second preset flushing temperature. The second preset flushing temperature can correspond to the flow dynamic temperature of PLA / PETG. At this temperature, the second stage of PLA / PETG working temperature extrusion is performed, thereby ensuring that when the printhead flushing is performed at the second preset flushing temperature, the cleaning filament can fill the nozzle, thereby fully contacting the impurities in the printhead, which is convenient for removing impurities in the subsequent cold drawing operation and improving the cleaning effect. In some embodiments, the first preset flushing temperature can be equal to the second preset flushing temperature, that is, the two flushing stages can be combined into one flushing stage, or at the first preset flushing temperature, the cumulative flushing amount is first detected to be greater than or equal to the minimum flushing threshold. After the cumulative flushing amount reaches the standard, a certain amount of flushing is then performed, followed by subsequent cleaning steps.

[0086] In some embodiments, the nozzle cleaning method further includes, when the current printing filament is a flexible printing filament, obtaining extrusion resistance information of the current filament in the printing state.

[0087] The inventors discovered during experiments that extrusion failures are more likely to occur when printing with elastic filament. After extensive observation and summarization, they found that elastic filament is more sensitive to deterioration of the printhead flow path when extruding it using an extruder. This is because when extrusion resistance increases, the elastic filament is more prone to deformation, leading to failure in feeding the filament from the extruder into the printhead. Therefore, when printing with elastic filament, the extrusion resistance information experienced by the filament during printing can be actively monitored, allowing for timely alerts to the user or proactive printhead cleaning.

[0088] In some embodiments, when the printing consumption exceeds the warning threshold, the extrusion resistance information of the current filament in the printing state is obtained, wherein the printing consumption is the cumulative amount of the current printing filament used since the last time the nozzle flow channel status abnormal information was output.

[0089] As mentioned earlier, with the accumulation of printing time, impurities or residual consumables will inevitably adhere to the inner wall of the printhead, leading to the deterioration of the printhead flow channel. By counting the amount of printing after the last cleaning, users can be reminded to clean the printhead in a timely manner, thereby ensuring that the printer is in good working condition.

[0090] Furthermore, as shown in Figure 2, the nozzle cleaning method for a 3D printer provided in this application further includes, after performing nozzle rinsing, the nozzle cleaning method also includes:

[0091] S3: Cold drawing operation. The cold drawing operation includes controlling the nozzle temperature to switch to the high elasticity temperature of the cleaning line and controlling the retraction of the cleaning line after exiting the machine.

[0092] Polymer materials exhibit excellent elastic characteristics between their glass transition temperature and viscous flow transition temperature, meaning they possess high elasticity and can deform. The inventors discovered that in this elastic state, cooling during the stretching and thinning process of the polymer material increases the strength of the filament, thereby carrying out all the polymer material within the nozzle. Impurities in the hot end are removed by the adhesion of the polymer material to impurities on the nozzle wall. Furthermore, by controlling the retraction of the cleaning filament from the production machine, the movement of the cleaning consumable within the nozzle is opposite to the rinsing direction, thus removing impurities that are difficult to remove during rinsing, significantly improving the nozzle cleaning effect.

[0093] Figure 5 shows the state of the printed filament during the cold drawing process. During the cold drawing process, the printed filament is in a highly elastic state at the temperature of the heating section. As the extruder pulls the printed filament back, the printed filament separates from the inner wall of the nozzle and begins to thin. During the deformation and movement, it carries away impurities in the nozzle. The printed filament is further cooled in the cooling section, thus ensuring that the printed filament is not pulled off during the pull-back process. It can be seen that the end of the cooling section will have a pointed shape, which indicates that the printed filament has been completely drawn out.

[0094] In some embodiments, when the cleaning liner is PLA or PETG, the cold-drawing operation includes controlling the nozzle temperature to switch to 75-95°C and controlling the retraction of the cleaning liner from the nozzle. The inventors discovered through experiments that when using PLA or PETG as cleaning consumables, within this temperature range, the cleaning consumables are in a highly elastic state and not easily broken, effectively carrying out all the polymer material inside the nozzle.

[0095] In some embodiments, the cleaning cable is a light-colored cable, which makes it easier to observe whether impurities inside the nozzle are brought out during flushing or re-extraction of waste materials, allowing users to judge the cleaning effect and the number of cleaning cycles.

[0096] In some embodiments, the cleaning filament is PLA or PETG. PLA or PETG exhibits excellent elasticity between the glass transition temperature and the viscous flow transition temperature, meaning the polymer material possesses high elasticity and can deform. Cooling during the stretching and thinning process increases the filament strength, thereby carrying out all the polymer material within the nozzle. Impurities in the hot end are removed by the adhesion of the polymer material to impurities on the nozzle wall.

[0097] In some embodiments, the current printing filament and the cleaning filament are the same type. In this case, the printhead flushing and / or cold-drawing operations described above can be performed directly.

[0098] In some embodiments, the device may further include a hopper, to which the printer is connected. The hopper may hold multiple or various printing filaments. The extruder is controlled to extrude cleaning filaments, including target cleaning filaments determined based on current printing filament information, into the printhead. The printhead cleaning method also includes:

[0099] If the current printing filament and the target cleaning filament are of different types, obtain the type information of at least one filament placed in the hopper. If the types of multiple filaments placed in the hopper include the type of the target cleaning filament, cut off the current printing filament and remove the current printing filament from the printhead, and feed the target cleaning filament from the hopper to the printhead to perform printhead rinsing.

[0100] It is understandable that printers or cartridges can be combined to achieve printing with different filament combinations. The workflow can involve a filament cutting device on the printer or cartridge cutting off the current printing filament and retracting it to a suitable position, such as before the junction point of the cartridge or filament converging device, before feeding the next printing filament into the printhead, thus achieving filament switching. When suitable clean filaments are stored in the cartridge and the current printing filament differs from the intended clean filament, the current printing filament can be automatically cut off and the intended clean filament fed in. Subsequently, printhead rinsing and / or cold-drawing operations as described above can be performed.

[0101] This application also provides a 3D printer that performs the nozzle cleaning method described in any of the above claims.

[0102] This application also provides a computer-readable storage medium storing computer instructions, wherein the computer program instructions are stored thereon, and when the instructions are executed on a computer, the computer causes the computer to perform the nozzle cleaning method of the 3D printer described in FIG2.

[0103] The non-transitory computer-readable storage medium storing computer instructions includes, for example, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0104] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0105] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, RAM, magnetic disks, or optical disks.

[0106] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0107] In this specification, the terms "specifically," "furthermore," "particularly," "understandably," etc., refer to specific features, structures, materials, or characteristics described in connection with embodiments or examples that are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0108] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0109] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for cleaning the nozzle of a 3D printer, the 3D printer comprising a nozzle and an extruder, characterized in that, The nozzle cleaning method includes: Obtain the current printing filament information and printhead flow channel status information of the printhead. The printhead flow channel status information includes at least information indicating the degree of printhead blockage, and the current printing filament information includes at least the filament type information of the printhead currently extruding filament. The nozzle flushing is performed based on the nozzle flow channel status information. The nozzle flushing includes controlling the nozzle temperature to be at a preset flushing temperature and controlling the extruder to extrude cleaning filaments into the nozzle. The cleaning filaments have at least a high elasticity characteristic.

2. The nozzle cleaning method according to claim 1, characterized in that, The preset flushing temperature includes the first preset flushing temperature; Performing nozzle flushing based on nozzle flow channel status information includes: Cleaning filament is extruded into the printhead at a first preset flushing temperature, wherein the first preset flushing temperature is higher than the glass transition temperature of the current printing filament, and the cleaning filament is in a fluid state.

3. The nozzle cleaning method according to claim 2, characterized in that, Performing nozzle flushing based on nozzle flow channel status information also includes, Within a preset rinsing time, the cumulative rinsing amount of cleaning material extruded into the nozzle at a first preset rinsing temperature is obtained. If the cumulative rinsing amount is lower than a minimum rinsing threshold, a nozzle flow channel status error message is output, or... The torque or rotational speed of the extruder is obtained when the cleaning filament is extruded into the nozzle at the first preset flushing temperature. If the torque of the extruder is greater than the preset flushing torque or the rotational speed of the extruder is lower than the preset rotational speed, the nozzle flow channel status error information is output.

4. The nozzle cleaning method according to claim 2, characterized in that, Performing nozzle flushing based on nozzle flow channel status information also includes, The cumulative flushing amount of the cleaning filament extruded into the nozzle at the first preset flushing temperature is counted. If the cumulative flushing amount is not lower than the minimum flushing threshold, the nozzle temperature is controlled to switch from the first preset flushing temperature to the second preset flushing temperature, and the cleaning filament is extruded into the nozzle at the second preset flushing temperature. The second preset flushing temperature is lower than or equal to the first preset flushing temperature, and the cleaning filament is in a flow state at the second preset flushing temperature.

5. The nozzle cleaning method according to claim 3 or 4, characterized in that, The minimum scouring threshold is any value between 6 and 12 mm.

6. The nozzle cleaning method according to claim 1, characterized in that, The extruder includes an extrusion motor and an extrusion wheel. The extrusion motor is connected to the extrusion wheel for transmission. The extrusion wheel is used to feed or retract filament into the printhead. The printhead flow channel status information includes information on the extrusion resistance experienced by the filament in the current printing state, and outputs abnormal information on the printhead flow channel status.

7. The nozzle cleaning method according to claim 6, characterized in that, The printhead flow path status information includes information on the extrusion resistance experienced by the filament during printing, and outputs abnormal printhead flow path status information, including: Obtain the extrusion motor torque range under normal extrusion conditions at different extrusion flow rates; when the extrusion motor torque exceeds the extrusion motor torque range during the extrusion of the current printing filament, output nozzle flow channel status abnormality information; and / or, Acquire image information of the nozzle extrusion fluid morphology under normal extrusion conditions at different extrusion flow rates, and plan an image evaluation domain based on the nozzle extrusion fluid morphology image information; acquire image information of the nozzle ejection fluid state when extruding the current printing filament, and output nozzle flow channel state abnormality information when the nozzle ejection fluid state exceeds the image evaluation domain; and / or, It also includes a printhead displacement sensor. In the printing state, the printhead is displaced under the action of the extruded filament, and the printhead displacement range under different extrusion flow rates is obtained when the extrusion state is normal. If the printhead displacement exceeds the printhead displacement range when the current printing filament is extruded, the printhead flow channel status abnormality information is output.

8. The nozzle cleaning method according to claim 6, characterized in that, The method further includes: If the current printing filament is a flexible printing filament, obtain the extrusion resistance information of the current filament in the printing state, and / or, If the printing consumption exceeds the warning threshold, obtain the extrusion resistance information of the current filament in the printing state. The printing consumption is the cumulative amount of the current printing filament used since the last time the printhead flow channel status abnormal information was output.

9. The nozzle cleaning method according to claim 1, characterized in that, The cleaning cable is a light-colored cable, and / or the cleaning cable is PLA or PETG.

10. The nozzle cleaning method according to claim 1, characterized in that, Controlling the extruder to extrude cleaning filament into the printhead includes the target cleaning filament determined based on the current printing filament information; The printer is connected to a hopper, which is used to hold multiple wires; The method further includes: If the current printing filament and the target cleaning filament are of different types, obtain the type information of at least one filament placed in the hopper. If the types of multiple filaments placed in the hopper include the type of the target cleaning filament, cut off the current printing filament and remove the current printing filament from the printhead, and feed the target cleaning filament from the hopper to the printhead to perform printhead rinsing.

11. The nozzle cleaning method according to claim 1, characterized in that, Currently, the printing and cleaning cables are of the same type.

12. The nozzle cleaning method according to claim 11, characterized in that, The printhead flow channel status information includes the extrusion resistance information experienced by the current filament during printing, and outputs printhead flow channel status abnormality information. Specifically, it obtains the extrusion resistance threshold under different extrusion flow rates when the extrusion state is normal, and outputs printhead flow channel status abnormality information when the extrusion resistance is greater than the extrusion resistance threshold during the extrusion of the current printing filament.

13. The nozzle cleaning method according to claim 2 or 4, characterized in that, After the nozzle rinsing is performed, the method also includes a cold-drawing operation, which involves controlling the nozzle temperature to switch to the high-elasticity temperature of the cleaning cable and controlling the retraction of the cleaning cable after it exits the machine. Alternatively, when the cleaning line is PLA or PETG, the cold drawing operation includes controlling the nozzle temperature to switch to 75-95℃ and controlling the retraction of the cleaning line after exiting the machine.

14. A 3D printer, characterized in that, The 3D printer performs the nozzle cleaning method as described in any one of claims 1-13.

15. A computer-readable storage medium storing computer instructions, characterized in that, Includes instructions that, when executed on a computer, cause the computer to perform the nozzle cleaning method as described in any one of claims 1 to 13.

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