Method for cleaning the hot end of a fused deposition modeling 3D printer

Abstract

A method for cleaning a hot end of a fused deposition modeling 3D printer. The method comprises: after printing with a first printing material at a first working temperature of the hot end, setting the hot end to a second working temperature, wherein the second working temperature is equal to or higher than the first working temperature; and at the second working temperature, extruding a cleaning material from a nozzle at the bottom of the hot end, wherein the cleaning material is in a highly elastic state at the second working temperature.

Description

Technical Field

[0001] The present disclosure relates to 3D printing technology, and more particularly to a method for cleaning the hot end of a fused deposition manufacturing (FDM) 3D printer. Background Art

[0002] With the development of 3D printing over the years, many new technologies have been introduced, such as fused deposition modeling (FDM), stereolithography (SLA), selective laser sintering (SLS), layer-by-layer manufacturing (LOM), etc. Among them, FDM has attracted much attention and is the most widely used. The principle of FDM is as follows: the hot end moves along the cross-sectional contour and filling trajectory of the part under the control of the computer. The thermoplastic printing material is sent to the hot end by the feeding mechanism, and heated and melted into a molten state (also known as a "viscous flow state") in the hot end, and then extruded and selectively coated on the workbench. After rapid cooling, a layer of thin sheet contour is formed. After a layer of cross-section is formed, the workbench drops to a certain height, and then the next layer of cladding is carried out. This cycle eventually forms a three-dimensional product part.

[0003] In the FDM-3D printing process, the printing material can only be extruded to complete the 3D printing after it changes from a solid state to a molten state. Since this transformation process is completed at the hot end, the temperature of the hot end is set to make the printing material in the molten state to achieve extrusion.

[0004] In the FDM-3D printing process involving multiple colors, after printing of one color of printing material A is completed, the hot end needs to be cleaned to replace the printing material B of a different color. There are usually two options.

[0005] The first option is to squeeze the printing material B directly into the hot end. At this time, inside the hot end, the printing material B is heated to a molten state and will be mixed to a certain extent with the remaining printing material A which is also in a molten state. This mixing process causes the printing material squeezed out from the bottom of the hot end to be not the desired color (for example, if the color of printing material A is red and the color of printing material B is yellow, the extruded material will have a section of orange), and cannot be used for subsequent FDM-3D printing, and the mixed color material needs to be squeezed into the "garbage area". This extrusion process will waste a lot of materials that could have been used for printing, and at the same time delay the printing time.

[0006] The second option is to extrude a colorless and transparent cleaning material into the hot end after printing material A is printed. At this time, inside the hot end, the cleaning material is heated to a molten state, and the remaining printing material A is finally cleaned by the flow effect. However, since the cleaning material is in a molten state, it will be mixed to a certain extent with the previously remaining printing material A that is also in a molten state, resulting in a longer time to clean the printing material A. In addition, the subsequently extruded printing material B is also heated to a molten state at the hot end, so it will be mixed to a certain extent with the remaining cleaning material. This mixing process causes the material extruded from the lower part of the hot end to be not pure printing material B. This change in material composition may have a certain degree of impact on the performance of the final printed product, especially for products with high requirements for material uniformity. Therefore, when using this cleaning material, a lot of materials that could have been used for printing will also be wasted, and the cleaning effect will not be significantly improved. Summary of the invention

[0007] It would be desirable to provide a mechanism that mitigates, alleviates or eliminates one or more of the above-mentioned problems.

[0008] According to one aspect of the present disclosure, a method for cleaning a hot end of an FDM-3D printer is provided. The method comprises: after printing with a first printing material at a first operating temperature of the hot end, setting the hot end to a second operating temperature, wherein the second operating temperature is equal to or higher than the first operating temperature; and at the second operating temperature, extruding a cleaning material from a nozzle at the bottom of the hot end, wherein the cleaning material is in a highly elastic state at the second operating temperature.

[0009] These and other aspects of the disclosure will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram showing an example structure of an extruder of a typical FDM-3D printer.

[0011] Figure 2 A schematic diagram of a method for cleaning the hot end of an FDM-3D printer according to an embodiment of the present disclosure is shown.

[0012] Figure 3 The embodiment according to the present disclosure is shown Figure 2 Flow chart of an example process for squeezing cleaning material out of the bottom of the hot end in the method of FIG.

[0013] Figure 4 The embodiment according to the present disclosure is shown Figure 2 Flow chart of another example process for squeezing cleaning material out of the bottom of the hot end in the method. DETAILED DESCRIPTION

[0014] It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts in this article, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish an element, component, region, layer or part from another region, layer or part. Therefore, the first element, component, region, layer or part discussed below may be referred to as a second element, component, region, layer or part without departing from the teaching of the present disclosure.

[0015] Spatially relative terms such as "top", "bottom", "below", "under", "lower", "below", "above", "upper", etc. may be used herein to describe the relationship of one element or feature to another element or features as illustrated in the figures for ease of description. It will be understood that these spatially relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figure is flipped, then the elements described as "below other elements or features" or "below other elements or features" or "below other elements or features" will be oriented as "above other elements or features". The device can be oriented in other ways (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly.

[0016] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "one", "one" and "the" are intended to also include plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "include" and / or "comprise" specify the existence of the features, wholes, steps, operations, elements and / or parts when used in this specification, but do not exclude the existence of one or more other features, wholes, steps, operations, elements, parts and / or their groups or add one or more other features, wholes, steps, operations, elements, parts and / or their groups. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0017] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant art and / or the context of this specification, and will not be interpreted in an idealized or overly formal sense, unless explicitly defined as such herein.

[0018] The printing materials currently used by FDM-3D printers are thermoplastic materials, such as PLA (polylactic acid), ABS (acrylonitrile-butadiene-styrene), PETG (polyethylene terephthalate-1,4-cyclohexanedimethanol ester), PA (polyamide) and other polymers. These printing materials mainly exist in three physical forms: glassy state, highly elastic state and molten state, and these physical forms are closely related to temperature. The same material can be in different physical states at different temperatures. For example, as the temperature continues to rise, it changes from a glassy state to a highly elastic state, and then to a molten state. The correspondence between the physical form of different materials and temperature is different, that is, at the same temperature, one material is in a molten state, but another material can be in a highly elastic state.

[0019] As used herein, the term "glassy state" refers to a state in which a material is in a rigid solid state and is substantially incompressible and indeformable at a certain temperature. This state is called "glassy state".

[0020] As used in this article, the term "high elastic state" means that at a certain temperature, the material will produce a certain elastic strain under the action of external stress, and after the external force is removed, part of the strain can be recovered. This state is called "high elastic state". High elastic state is also called "rubber state".

[0021] As used herein, the term "molten state" means that at a certain temperature, under the action of external stress, a large deformation will occur, and the deformation cannot be restored, and the material is in a viscous fluid state. This state is called "molten state". The molten state is also called "viscous flow state".

[0022] As used herein, the term "first operating temperature" refers to the temperature of the hot end when the first printing material is being printed, and the first printing material is in a molten state at this temperature.

[0023] As used herein, the term "second operating temperature" refers to the temperature of the hot end after printing of the first printing material is completed and during the addition of the cleaning material. The first printing material is in a molten state at this temperature, and the cleaning material is in a highly elastic state at this temperature.

[0024] As mentioned above, in the current FDM-3D printing process, when the color of the printing material needs to be switched, the conventional operation used will result in a lot of waste of materials that could have been used for printing, and at the same time delay the printing time. The reason is that both the mainstream FDM-3D printing materials (such as PLA, ABS, PETG, PA) and the currently used cleaning materials (such as polyethylene) are in a molten state at the hot end temperature of the FDM-3D printer. In a molten state, the molecular chain is easier to flow, causing the subsequent printing material or cleaning material to mix with the previous printing material, resulting in a long time to clean the previous printing material. Usually, 600mm or longer materials are required to achieve a good cleaning effect, which not only increases the material cost, but also increases the time cost.

[0025] Therefore, the art always expects to improve the cleaning efficiency of the hot end of the FDM-3D printer, shorten the cleaning time, and reduce the waste of materials.

[0026] Figure 1 FIG. 1 is a schematic diagram showing an exemplary structure of an extruder 100 of a typical FDM-3D printer. Figure 1 As shown, the extruder 100 includes a cold end 110 and a hot end 120. The hot end includes a nozzle 125 and heating components such as a thermistor 121, a heater cartridge 122, and a heater block 123. A solid printing material (not shown) is extruded into the cold end 110 by a feeding mechanism and enters the hot end 120 from the top of the hot end 120. In the hot end 120, the printing material is melted into a molten state at the working temperature provided by the heating component, and is finally extruded from a nozzle 125 at the bottom of the hot end 120.

[0027] Figure 2 FIG. 2 is a schematic diagram showing a method 200 for cleaning the hot end of an FDM-3D printer according to an embodiment of the present disclosure. Figure 2 As shown, method 200 includes step 210 and step 220. Figure 1 and 2 Method 200 is described.

[0028] At step 210, after printing with the first printing material at the first operating temperature of the hot end 120, the hot end 120 is set to a second operating temperature. In this embodiment, the second operating temperature is equal to or higher than the first operating temperature. It will be understood that at the first operating temperature, the first printing material is in a molten state for normal printing operations, and at the second operating temperature equal to or higher than the first operating temperature, the first printing material will also be in a molten state.

[0029] At step 220, at a second operating temperature, the cleaning material is extruded from the nozzle 125 at the bottom of the hot end 120. The cleaning material is in a highly elastic state at the second operating temperature.

[0030] Since the cleaning material is in a highly elastic state, rather than a molten state, at the second operating temperature of the hot end 120, when the first printing material is printed and the cleaning material is extruded from the hot end 120, the physical properties of the highly elastic state (internal molecular chain flow is difficult) enable the cleaning material to physically "scrape" the inner wall of the hot end 120 (similar to erasing with an eraser). Compared with the cleaning effect of conventional molten cleaning materials (similar to flushing with liquid), a more complete cleaning of the first printing material attached to the inner wall can be achieved, and the mixing length of the highly elastic cleaning material and the molten first printing material inside the hot end 120 will become shorter. Moreover, the cleaning material in a highly elastic state can also be deformed, which means that after the cleaning material squeezes out the first printing material, it can also be smoothly squeezed out from the bottom of the hot end without affecting the subsequent printing process. Therefore, using the technical solution according to the embodiment of the present disclosure, a good cleaning effect can be achieved using a shorter cleaning material. In the example, only 100-300mm or even shorter cleaning materials are required, thereby reducing material waste, saving printing time, and improving printing efficiency. In addition, the cleaning method according to the embodiment of the present disclosure can not only be used to clean the previous printing material remaining inside the hot end during the process of switching printing materials of multiple colors, but also can be used for daily cleaning and maintenance of the printer. In either case, the beneficial technical effect of reducing waste and improving efficiency can be achieved.

[0031] In some embodiments, the cleaning material may be one or more of polycarbonate, acrylonitrile butadiene styrene, polyamide, and polyethylene terephthalate. In some embodiments, the cleaning material may be polycarbonate.

[0032] In some embodiments, the second operating temperature may be higher than 180° C. and lower than or equal to 200° C. In some embodiments, the second operating temperature may be higher than 180° C. and lower than or equal to 220° C.

[0033] In some embodiments, the first printing material may be one or more of polylactic acid, acrylonitrile-butadiene-styrene, polyamide, and polyethylene terephthalate-1,4-cyclohexanedimethanol.

[0034] In some embodiments, the temperature of the hot end 120 may remain unchanged, that is, the first operating temperature and the second operating temperature may be the same.

[0035] In some embodiments, the first printing material may be polylactic acid, and the cleaning material may be one or more of polycarbonate, acrylonitrile-butadiene-styrene, polyamide, and polyethylene terephthalate.

[0036] In some embodiments, the first printing material may be acrylonitrile butadiene styrene and the cleaning material may be polycarbonate.

[0037] In some embodiments, the first printing material may be polyamide and the cleaning material may be polycarbonate.

[0038] In some embodiments, the first printing material may be polyethylene terephthalate-1,4-cyclohexanedimethanol, and the cleaning material may be polyphenylene sulfide.

[0039] Figure 3 The embodiment according to the present disclosure is shown Figure 2 Flow chart of an example process for squeezing cleaning material out of the bottom of the hot end (step 220) in the method 200 of FIG. Figure 3 , step 220 includes steps 310 to 330. Figure 1 and 3 Steps 310 to 330 are described in detail.

[0040] At step 310, purge material is added to the hot end 120 from the top of the hot end 120. In an example, the purge material can be fed into the cold end 110 by a feeding mechanism (not shown) used with the extruder 100, and as the feeding proceeds, passes through the cold end 110 and enters the hot end 120 from the top of the hot end 120. Alternatively, the purge material can be fed directly to the cold end 110 and then enter the hot end 120, as will be further described later.

[0041] At step 320, immediately following the addition of the cleaning material, a second printing material is added to the hot end 120 from the top of the hot end 120. The second printing material may be different from the first printing material. In practice, the second printing material is typically in the form of a filament. In an example, a feeding mechanism (not shown) may feed the filament of the second printing material into the cold end 110. As the feeding proceeds, the second printing material will pass through the cold end 110 and enter the hot end 120 from the top of the hot end 120.

[0042] At step 330, the second printing material is pressed toward the bottom of the hot end 120, so that the cleaning material is pressed from the nozzle 125. In the example, as the feeding mechanism continues to feed the second printing material into the cold end 110, the second printing material entering the hot end 120 will press the cleaning material below, and finally the cleaning material will be pressed out from the nozzle 125 at the bottom of the hot end 120.

[0043] In some embodiments, the cleaning material may be in the form of a filament or a sphere. In the embodiment in which the cleaning material is a filament, after adding a section of the cleaning material, a cutting operation needs to be performed to cut off the filaments of the cleaning material. In the embodiment in which the cleaning material is a sphere, the pellets of the cleaning material can be directly fed into the hot end 120, which is simple to load and does not require cutting. In addition, the shape of the sphere makes it difficult for the cleaning material to get stuck inside the cold end 110 or the hot end 120.

[0044] Figure 4 FIG. 2 is a flow chart showing another exemplary process of squeezing the cleaning material out of the bottom of the hot end (step 220 ) in the method 200 according to an embodiment of the present disclosure. Figure 4 , step 220 includes steps 410 to 430. Figure 1 and 4 Steps 410 to 430 are described in detail.

[0045] At step 410, cleaning material is added to the hot end 120 from the top of the hot end 120. In an example, the filaments of cleaning material can be fed into the cold end 110 by a feeding mechanism, and as the feeding proceeds, pass through the cold end 110 and enter the hot end 120 from the top of the hot end 120.

[0046] At step 420, the cleaning material is pressed toward the bottom of the hot end 120 so that the first portion of the cleaning material is squeezed out of the nozzle 125. In the example, as the feeding mechanism continues to feed the cleaning material into the cold end 110, a portion of the cleaning material will enter the hot end 120 and eventually be squeezed out of the nozzle 125 at the bottom of the hot end 120.

[0047] At step 430, a second portion of the cleaning material is pulled out from the top of the hot end 120, the second portion being different from the first portion. In an example, after a portion of the cleaning material has been extruded from the nozzle 125, the feeding mechanism can be controlled to reverse to withdraw the filaments of the cleaning material from the cold end 110. In this process, a portion of the cleaning material within the cold end 110 and the hot end 120 will separate from the cleaning material that has been extruded from the nozzle 125 and be pulled out from the top of the hot end 120 (and then the cold end 110).

[0048] By adopting this embodiment, the mixing length of the second printing material and the cleaning material can be further reduced, and the time required for cleaning the hot end can be further reduced because the amount of cleaning material is reduced and the time for extruding the cleaning material is correspondingly shortened.

[0049] In some embodiments, the cleaning material may take the form of a filament.

[0050] The various embodiments and options described above for the method of the present disclosure can be combined with each other (as long as they are not inherently contradictory to each other), and the various embodiments formed by such combination are all considered as part of the present disclosure.

[0051] The technical solution of the present disclosure is more clearly and explicitly described above with reference to some embodiments in an illustrative manner. It should be understood that these embodiments are only for illustrative purposes and are by no means intended to limit the scope of protection of the present disclosure. The scope of protection of the present disclosure is limited only by the claims.

Claims

1. A method for cleaning a hot end of a fused deposition modeling 3D printer, the method comprising: The 3D printer comprises an extruder, and the extruder comprises a cold end and the hot end; After printing with a first printing material at the first operating temperature of the hot end, setting the hot end to a second operating temperature, wherein the second operating temperature is equal to or higher than the first operating temperature; and At the second working temperature, a cleaning material is extruded from a nozzle at the bottom of the hot end, wherein the cleaning material is in a highly elastic state at the second working temperature, and the first printing material and the cleaning material are fed to the cold end by a feeding mechanism; after a portion of the cleaning material has been extruded from the nozzle, the feeding mechanism is controlled to reverse to withdraw the filaments of the cleaning material from the cold end; The cleaning material includes at least one selected from the group consisting of polycarbonate, acrylonitrile-butadiene-styrene, polyamide and polyethylene terephthalate.

2. The method of claim 1, wherein extruding the cleaning material from a nozzle at the bottom of the hot end comprises: adding the cleaning material into the hot end from the top of the hot end; Immediately after the addition of the cleaning material, a second printing material is added to the hot end from the top of the hot end; as well as The second printing material is pressed toward the bottom of the hot end so that the cleaning material is squeezed out from the nozzle under the pressure of the second printing material.

3. The method of claim 2, wherein the cleaning material is in a form selected from the group consisting of: filaments and spheres.

4. The method of claim 1, wherein extruding the cleaning material from a nozzle at the bottom of the hot end comprises: adding the cleaning material into the hot end from the top of the hot end; extruding the cleaning material toward the bottom of the hot end so that a first portion of the cleaning material is extruded from the nozzle; as well as A second portion of the cleaning material is pulled out from the top of the hot end, the second portion being different from the first portion.

5. The method of claim 4, wherein the cleaning material is in the form of a filament.

6. The method according to any one of claims 1 to 5, wherein the second operating temperature is higher than 180°C and lower than or equal to 200°C.

7. The method of any one of claims 1 to 5, wherein the cleaning material is polycarbonate.

8. The method of claim 7, wherein the second operating temperature is higher than 180°C and lower than or equal to 220°C.

9. The method according to any one of claims 1 to 5, wherein the first printing material comprises at least one selected from the group consisting of polylactic acid, acrylonitrile-butadiene-styrene, polyamide, and polyethylene terephthalate-1,4-cyclohexanedimethanol.

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