CN113844030A

CN113844030A - Method for 3D printer and 3D printer device

Info

Publication number: CN113844030A
Application number: CN202111282631.3A
Authority: CN
Inventors: 商俊蓓
Original assignee: Shenzhen Tuozhu Technology Co Ltd
Current assignee: Shenzhen Tuozhu Technology Co Ltd
Priority date: 2021-11-01
Filing date: 2021-11-01
Publication date: 2021-12-28

Abstract

A method for a 3D printer. This 3D printer includes: a printhead defining a strand channel for passage of a strand, the strand channel comprising a first end and a second end opposite the first end at which the strand is to be melted, the strand channel being provided with a seam resulting from engagement of different components of the printhead; an extruder configured to feed strands into the strand passage via a first end and extrude strands via a second end; and a strand cutter disposed between the extruder and the print head. The method comprises the following steps: causing the strand cutter to cut the strand into a first strand segment outside the strand passageway and a second strand segment at least partially within the strand passageway; causing the extruder to feed a first strand segment into the strand passageway via a first end of the strand passageway such that a second strand segment is pushed by the first strand segment toward a second end of the strand passageway to a position beyond the seam; and causing the extruder to withdraw the first strand section out of the strand passageway.

Description

Method for 3D printer and 3D printer device

Technical Field

The present disclosure relates to the field of 3D printing technology, and in particular, to a method for a 3D printer, and to a 3D printer, a computer-readable storage medium, and a computer program product.

Background

The 3D printer, also known as a three-dimensional printer or a stereo printer, is a process equipment for rapid prototyping, and is usually realized by printing a material by using a digital technology. 3D printers are often used to manufacture models or parts in the fields of mold manufacturing, industrial design, and the like. In recent years, 3D printing technology has had a promising application in jewelry, footwear, industrial design, construction, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, geographic information systems, civil engineering, firearms, and other fields.

As a three-dimensional printing method known in the art, Fused Deposition Modeling (FDM) is a method of constructing a three-dimensional object by layer-by-layer printing using a material such as powdered metal or plastic based on a digital model, in which a three-dimensional printer is used to supply a modeling material in the form of a filament to a print head, where the modeling material is heated to a molten state by electrical heating. The print head prints the three-dimensional object layer by layer according to a path of movement of the print head relative to the substrate as generated by a controller of the three-dimensional printer.

In the process of reloading, the 3D printer firstly needs to withdraw part of the wires in the molten state, and since the temperature difference exists at each part of the printing head and the gap exists at the combination of each part, the part of the wires in the molten state may block the gap, so that the wire channel is blocked, and finally, the subsequent reloading operation cannot be continued.

Disclosure of Invention

The present disclosure provides a method for a 3D printer, as well as a 3D printer device, a computer readable storage medium, and a computer program product.

According to one aspect of the present disclosure, a method for a 3D printer is provided.

The 3D printer includes: a printhead defining a strand channel for passage of a strand, the strand channel comprising a first end and a second end opposite the first end at which the strand is to be melted, the strand channel being provided with a seam resulting from engagement of different components of the printhead; an extruder configured to feed strands into the strand passage via a first end and extrude strands via a second end; and a strand cutter disposed between the extruder and the print head. The method comprises the following steps: causing the strand cutter to cut the strand into a first strand segment outside the strand passageway and a second strand segment at least partially within the strand passageway; causing the extruder to feed a first strand segment into the strand passageway via a first end of the strand passageway such that a second strand segment is pushed by the first strand segment toward a second end of the strand passageway to a position beyond the seam; and causing the extruder to withdraw the first strand section out of the strand passageway.

According to another aspect of the present disclosure, there is also provided a 3D printer including: a printhead defining a strand channel for passage of a strand, the strand channel comprising a first end and a second end opposite the first end at which the strand is to be melted, the strand channel being provided with a seam resulting from engagement of different components of the printhead; an extruder configured to feed strands into the strand passage via a first end and extrude strands via a second end; a strand cutter disposed between the extruder and the print head and configured to cut the strand; and a processor configured to execute the instructions to implement the method as above.

According to yet another aspect of the present disclosure, there is also provided a non-transitory computer readable storage medium having instructions stored thereon, wherein the instructions, when executed by a processor of a 3D printer as described above, implement the method as described above.

According to yet another aspect of the present disclosure, there is also provided a computer program product comprising instructions, wherein the instructions, when executed by a processor of a 3D printer as described above, implement the method as described above.

According to the embodiment of the disclosure, when the 3D printer executes the material changing, the material cutting operation is firstly carried out, the cut line material is divided into a first line material section outside the line material channel and a second line material section at least partially positioned in the line material channel, the second line material section is pushed to a position exceeding a joint by the second end of the line material section of the first line material section towards the line material channel, and finally the first line material section is pulled back out of the line material channel. By the mode, the phenomenon that the wire materials block the wire material channel is avoided, and smooth material changing is further realized.

It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present disclosure, nor do they limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

In the drawings, like reference numerals refer to the same or similar parts or elements throughout the several views unless otherwise specified. The figures are not necessarily to scale. It is appreciated that these drawings depict only some embodiments in accordance with the disclosure and are not to be considered limiting of its scope.

Fig. 1 shows a schematic structural diagram of a 3D printer according to an exemplary embodiment of the present disclosure;

FIG. 2 shows a flow diagram of a method for a 3D printer according to an example embodiment of the present disclosure;

fig. 3 shows a flow diagram of one example process of severing a wire in the method of fig. 2, according to an example embodiment of the present disclosure;

fig. 4a shows a schematic diagram of a method for a 3D printer according to an exemplary embodiment of the present disclosure;

FIG. 4b shows a schematic diagram of a method for a 3D printer according to an example embodiment of the present disclosure;

fig. 4c shows a schematic diagram of a method for a 3D printer according to an exemplary embodiment of the present disclosure;

fig. 4D shows a schematic diagram of a method for a 3D printer according to an example embodiment of the present disclosure;

fig. 5 shows a flow diagram of another example process of severing a wire in the method of fig. 2, according to an example embodiment of the present disclosure;

fig. 6 shows a flow chart of a method for a 3D printer according to another exemplary embodiment of the present disclosure;

fig. 7 shows a flowchart of a method for a 3D printer according to another exemplary embodiment of the present disclosure; and

fig. 8 shows a flowchart of a method for a 3D printer according to another exemplary embodiment of the present disclosure;

Detailed Description

Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings, in which various details of the embodiments of the disclosure are included to assist understanding, and which are to be considered as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the present disclosure. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.

In the present disclosure, unless otherwise specified, the use of the terms "first", "second", etc. to describe various elements is not intended to limit the positional relationship, the timing relationship, or the importance relationship of the elements, and such terms are used only to distinguish one element from another. In some examples, a first element and a second element may refer to the same example of the element, and in some cases, based on the context, they may also refer to different examples.

The terminology used in the description of the various described examples in this disclosure is for the purpose of describing particular examples only and is not intended to be limiting. Unless the context clearly indicates otherwise, if the number of elements is not specifically limited, the elements may be one or more. Furthermore, the term "and/or" as used in this disclosure is intended to encompass any and all possible combinations of the listed items.

In practice, the 3D printer needs to return the thread stock currently in use before the change of the stock can be made. In the related art, the old thread material is first pumped back and then cut, so as to reduce the waste of the thread material. And then waiting for loading of a new thread material, and after the new thread material is loaded, pushing the old thread material which is cut off before and remains in the thread material channel to the nozzle through the new thread material, so as to realize the material changing step of 3D printing. The inventors found that this brings about the following problems: since the strand passage includes gaps caused by the joining of various components, when the old strand is withdrawn, a part of the old strand is in a molten state, and the strand in the molten state is cooled to become solid during a waiting time for loading of a new strand, so that the joint is blocked, the strand passage is blocked, and the subsequent strand changing step is influenced.

In view of this, the disclosed embodiments provide a 3D printer 100 and a method for a 3D printer that may alleviate, alleviate or even eliminate the above-mentioned problems.

Fig. 1 shows a schematic structural diagram of a 3D printer 100 according to one embodiment of the present disclosure. The 3D printer 100 will be described in detail with reference to fig. 1.

As shown in fig. 1, the 3D printer 100 includes: a processor (not shown in the figures), an extruder 102, a strand cutter 103, a print head 107, and a print deck 109.

The extruder 102 may be provided with an extrusion train that may be driven, for example, by a motor (not shown) controlled by a processor to perform a feed or return operation. In the feeding operation, the strand 101 is fed by the extruder 102 toward the print head 107, and in the discharging operation, the strand 101 is drawn back from the print head 107 by the extruder 102.

The printhead 107 defines a strand channel 105 for passage of the strand 101. The strand channel 105 includes a first end 104 and a second end 108 opposite the first end 104. The second end 108 is provided with a heater so that the strands 101 will be melted at the second end 108. The thread channel 105 is also provided with a seam 106 resulting from the joining of the different components of the print head 107.

The strand cutter 103 is arranged between the extruder 102 and the print head 107. In the present embodiment, for convenience of description, the direction from the second end 108 to the first end 104 is defined as the Z-axis direction. The strand cutter 103 may be driven by, for example, a motor (not shown) controlled by a controller to move in a plane perpendicular to the Z-axis direction, thereby cutting the strand 101.

The printing platform 109 is disposed at the bottom of the 3D printer 100, and is used for supporting an object to be printed, and an upper surface of the printing platform is a printing plane. The printing platform 109 may include a refill area (not shown). The space above the printing platform 109 includes a printing space for printing an object to be printed and a material replacement space for replacing a wire. In this embodiment, the combination of the print head 107 and the extruder 102 can move in the printing space and the refueling space.

Although the extruder 102 is shown in fig. 1 as being disposed above the print head 107, other embodiments are possible. For example, in a remote feed embodiment, the extruder 102 may be located remotely from the print head 107. It will also be understood that the seam 106 in fig. 1 is schematic, and in practice the seam 106 may have different dimensions and locations than illustrated.

A processor (not shown) is configured to perform operations when executing instructions, the operations comprising: causing the strand cutter 103 to cut the strand 101 into a first strand segment outside the strand passageway 105 and a second strand segment at least partially within the strand passageway 105; causing the extruder 102 to feed a first strand segment into the strand passageway 105 via the first end 104 of the strand passageway 105 such that a second strand segment is pushed by the first strand segment toward the second end 108 of the strand passageway 105 to a position beyond the seam 106; and causing the extruder 102 to draw the first strand back out of the strand passageway 105.

Fig. 2 shows a flowchart of a method 200 for the 3D printer 100 according to an example embodiment of the present disclosure. The method 200 may include the following steps.

In step 201, the strand cutter 103 is caused to cut the strand 101 into a first strand segment outside the strand passageway 105 and a second strand segment at least partially within the strand passageway 105.

Referring to fig. 4a and 4b, fig. 4a shows the operation 41 of the strand cutter 103 performing horizontal right-hand cutting such that the strand cutter 103 cuts the strand 101 while the position of the strand 101 at the bottom end of the strand passage 105 exceeds the position of the seam 106 in the direction opposite to the Z-axis direction. Fig. 4b shows the strand cutter 103 cutting the strand 101 into two strand pieces.

In step 202, the extruder 102 is caused to feed a first strand segment into the strand passageway 105 via the first end 104 of the strand passageway 105 such that a second strand segment is pushed by the first strand segment toward the second end 108 of the strand passageway 105 to a position beyond the seam 106.

Referring to fig. 4c, fig. 4c shows the wire cutter 103 performing operation 43 such that the wire cutter 103 is horizontally retracted leftward. At this point the strand 101 has been cut by the cutter 103 into a first strand segment 110 and a second strand segment 111. The extruder 102 is then powered by a motor to feed the first strand segment 110 in a direction opposite the Z-axis, i.e., to carry the operation 44 downward.

Referring to the schematic view of fig. 4d, fig. 4d shows the first strand segment 110 pushing the second strand segment 111 in a direction opposite the Z-axis to a position beyond the seam 106 after the extruder 102 performs operation 44. At this point, the second strand segment 111, which may be in a molten state, does not block the seam 106 and eventually exits the strand passageway 105 after a new strand is loaded. In this way, clogging of the seam 106 and thus of the thread passage 105 is avoided.

In step 203, the extruder is caused to withdraw the first strand segment out of the strand passageway.

With continued reference to fig. 4d, fig. 4d shows that after pushing the second strand 111 away from the position of the seam 106 in the opposite direction along the Z-axis, the extruder 102 controls the first strand 110 to be withdrawn in the Z-axis direction, i.e., performs operation 45 to transport upward until the first strand 110 is completely withdrawn. After pushing the second strand 111 away from the seam 106, the operation 45 may be performed quickly to withdraw the first strand 110 along the Z-axis, preventing the first strand 110 from being heated to a molten state. In this way, the old material is withdrawn, and the 3D printer can load new line material.

Fig. 3 shows a flowchart of one example process 201a of cutting the wire in step 201 in method 200, according to an example embodiment of the present disclosure. The process 201a may include the following steps.

In step 301, the strand cutter 103 is moved from the initial position to the working position to cut the strand.

Referring to fig. 4a, the strand cutter 103 performs a horizontal right-hand cutting operation 41, resulting in a horizontal displacement to the right, i.e., the strand cutter 103 starts to move from the initial position to the working position.

In step 302, the extruder 102 is caused to draw back the strand 101 in a direction away from the second end 108 of the strand passageway 105 while maintaining the strand cutter 103 in the working position to ensure that the strand 101 is severed into the first strand segment 110 and the second strand segment 111.

Referring to fig. 4b, the strand cutter 103 is held in the working position. To ensure that the strand 101 is cut by the strand cutter 103, the extruder 102 performs operation 42 to draw back the strand 101 in a direction opposite to the Z-axis direction so that a strand segment located above the strand cutter 103 is completely separated from a strand segment located below the strand cutter 103. Referring to fig. 4c, the strand segment located above the strand cutter 103 is a first strand segment 110, and the strand segment located below the strand cutter 103 is a second strand segment 111.

In step 303, the strand cutter is returned from the working position to the initial position.

With continued reference to fig. 4c, fig. 4c shows the strand cutter 103 performing operation 43 such that the strand cutter 103 is retracted horizontally to the left, i.e., from the working position back to the initial position, as shown in fig. 4 d.

Fig. 5 shows a flowchart of another example process 201b of cutting a wire in step 201 in method 200, according to an example embodiment of the present disclosure. The process 201b may include the following steps:

in step 501, the strand cutter 103 is moved back and forth a predetermined number of times between the initial position and the working position for cutting the strand 101 to ensure that the strand 101 is cut into the first strand segment 110 and the second strand segment 111.

In step 502, the strand cutter 103 is returned from the working position to the initial position.

In some cases, the strand cutter 103 may not be able to cut the strand 101 at once, resulting in the first strand segment 110 and the second strand segment 111. In order to ensure that the string 101 is cut into two string pieces, it is also possible to perform multiple cuts by reciprocating the string cutter 103 multiple times to and from the initial position and the working position. Then, the strand cutter 103 returns to the initial position.

Fig. 6 shows a flowchart of a method 600 for the 3D printer 100 according to another exemplary embodiment of the present disclosure. The method 600 may include the steps of:

in step 601, the strand cutter 103 is caused to cut the strand 101 into a first strand segment 110 outside the strand passageway 105 and a second strand segment 111 at least partially inside the strand passageway 105.

In step 602, the print head 107 and the print deck 109 are translated relative to each other such that the print head 107 is positioned over the refill zone.

In step 603, the extruder 102 is caused to feed the first strand segment 110 into the strand passageway 105 via the first end 104 of the strand passageway 105 such that the second strand segment 111 is pushed by the first strand segment 110 toward the second end 108 of the strand passageway 105 to a position beyond the seam 106.

In step 604, extruder 102 is caused to withdraw first strand segment 110 back out of feed channel 105.

According to some embodiments, in order to reduce the pollution of the thread, a material changing area different from the printing area needs to be set on the printing platform 109, so that the 3D printer 100 performs the function of 3D printing in the printing area and performs the operation of material returning and material changing in the material changing area.

In such an embodiment, step 602 may be performed prior to causing the extruder 102 to feed the first strand segment 110 into the strand passageway 105 via the first end 104 of the strand passageway 105 to cause the print head 107 and the print platform 109 to translate relative to each other such that the print head 107 is positioned over the refill zone, prior to performing step 603.

In one embodiment, the 3D printer 100 may be powered by a motor to control the movement of the print head 107, move the print head 107 from the print area to above the refill area, and perform the material return and refill operations.

In one embodiment, the 3D printer 100 may be powered by a motor to control the movement of the printing platform 109, move the refueling zone of the printing platform 109 to the position below the print head 107, and perform the material returning and refueling operations.

In one embodiment, the 3D printer 100 may be powered by a motor while controlling the movement of the print deck 109 and the print head 107 such that the print head 107 is positioned over the refueling zone to perform the material returning and refueling operations.

According to some embodiments, as shown in fig. 4a, the lower end of the strand 101 (in the molten state) is already at the location of the seam 106, and during the positioning of the print head 107 over the refill area, the lower end of the strand 101 in the molten state may be cooled to solidify, thereby plugging the seam 106. To avoid this possibility, step 602 may be performed before step 601.

According to some embodiments, the sequence of steps at this point is: first translating the print head 107 and the print deck 109 relative to each other so that the print head 107 is positioned above the refill zone; then the thread material cutter 103 cuts the thread material 101 into a first thread material segment 110 and a second thread material segment 111; the extruder 102 is then caused to feed the first strand segment 110 into the strand passageway 105 such that the second strand segment 111 is pushed by the first strand segment 110 toward the second end 108 of the strand passageway 105 to a position beyond the seam 106; and causing the extruder 102 to draw the first strand section 110 back out of the feed channel 105.

Fig. 7 shows a flowchart of a method 700 for the 3D printer 100 according to another example embodiment of the present disclosure. The method 700 may include the steps of:

in step 701, the strand cutter 103 is caused to cut the strand 101 into a first strand segment 110 outside the strand passageway 105 and a second strand segment 111 at least partially within the strand passageway 105.

In step 702, the print head 107 and the print deck 109 are translated relative to each other such that the print head 107 is positioned over the refill zone.

In step 703, the extruder 102 is caused to feed the first strand segment 110 into the strand passageway 105 via the first end 104 of the strand passageway 105 such that the second strand segment 111 is pushed by the first strand segment 110 toward the second end 108 of the strand passageway 105 to a position beyond the seam 106.

In step 704, the extruder 102 is caused to withdraw the first strand section 110 back out of the strand passageway 105.

In step 705, extruder 102 is caused to feed replacement strand into strand passageway 105 via first end 104 of strand passageway 105 such that second strand segment 111 is pushed out of strand passageway 105 by the replacement strand via second end 108 of strand passageway 105.

Through steps 701 to 704, the 3D printer has completed the operation of returning the material, but the second strand section 111 is still located in the strand passage 105. A reloading operation may then be performed, step 705, causing the extruder 102 to feed replacement strand into the strand passageway 105 such that the second strand segment 111 is pushed out of the strand passageway 105 by the replacement strand.

In one embodiment, it is observed whether the color of the strand discharged from the print head 107 is single and stable, and if the color of the strand discharged is single and stable, the 3D printer 100 completes the operation of replacing the strand.

Fig. 8 shows a flowchart of a method 800 for a 3D printer according to another example embodiment of the present disclosure. The method 800 may include the steps of:

in step 801, the extruder 102 is caused to withdraw the strand 101 a predetermined length in a direction away from the second end 108 of the strand passageway 105.

According to some embodiments, to perform a refuel operation, the 3D printer 100 first needs to terminate the printing operation. In order to reduce the waste of the strand 101 that has not been melted, the strand 101 is first drawn back by the extruder 102 for a predetermined length, i.e., step 801 is performed, with a long portion of the strand 101 being located in the strand passage 105.

In one embodiment, the extruder withdraws a predetermined length, depending on how much of the length of strand has not become molten.

In one embodiment, the extruder is withdrawn a predetermined length, depending on the value set by the user of the 3D printer before performing the refueling operation.

Then, steps 802 to 806 are performed. Steps 802 to 806 may be the same as steps 701 to 705 described above with respect to fig. 7 and are not described again for the sake of brevity.

There is also provided, in accordance with an embodiment of the present disclosure, a non-transitory computer-readable storage medium having instructions stored thereon, wherein the instructions, when executed by a processor, implement the steps of any of the methods as in any of the embodiments of the present disclosure.

There is also provided, in accordance with an embodiment of the present disclosure, a computer program product including instructions, wherein the instructions, when executed by a processor, implement the steps of the method as in any one of the embodiments of the present disclosure.

It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present disclosure may be performed in parallel, sequentially or in different orders, and are not limited herein as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved.

It will be understood that in this specification, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, indicate an orientation or positional relationship or dimension based on that shown in the drawings, which terms are used for convenience of description only and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be considered limiting to the scope of the disclosure.

Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to a number of indicated technical features. Thus, features defined as "first", "second", "third" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.

In the present disclosure, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integral; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise the first and second features being in direct contact, or may comprise the first and second features being in contact, not directly, but via another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

This description provides many different embodiments or examples that can be used to implement the present disclosure. It should be understood that these various embodiments or examples are purely exemplary and are not intended to limit the scope of the disclosure in any way. Those skilled in the art can conceive of various changes or substitutions based on the disclosure of the specification of the present disclosure, which are intended to be included within the scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope defined by the appended claims.

Claims

1. A method for a 3D printer, wherein the 3D printer comprises: a printhead defining a strand channel for passage of a strand, the strand channel comprising a first end and a second end opposite the first end at which the strand is to be melted, the strand channel being provided with a seam resulting from joining of different components of the printhead; an extruder configured to feed the strand into the strand channel via the first end and extrude the strand via the second end; and a strand cutter disposed between the extruder and the printhead, the method comprising:

causing the strand cutter to cut the strand into a first strand segment outside of the strand passageway and a second strand segment at least partially within the strand passageway;

causing the extruder to feed the first strand segment into the strand passageway via the first end of the strand passageway such that the second strand segment is pushed by the first strand segment toward the second end of the strand passageway to a location beyond the seam; and

causing the extruder to draw the first strand segment back out of the strand passageway.

2. The method of claim 1, wherein causing the strand cutter to sever the strand into a first strand segment and a second strand segment comprises:

moving the strand cutter from an initial position to a working position to sever the strand;

while maintaining the strand cutter in the working position, causing the extruder to draw back the strand in a direction away from the second end of the strand passageway to ensure that the strand is severed into the first strand segment and the second strand segment; and

returning the strand cutter from the working position to the initial position.

3. The method of claim 1, wherein causing the strand cutter to sever the strand into a first strand segment and a second strand segment comprises:

moving the strand cutter back and forth a predetermined number of times between an initial position and a working position for cutting the strand to ensure that the strand is cut into the first strand segment and the second strand segment; and

returning the strand cutter from the working position to the initial position.

4. The method of claim 1, wherein the 3D printer further comprises a printing platform comprising a feed change area for switching strands, and wherein the printhead and the printing platform are arranged to be translatable relative to each other, the method further comprising:

translating the print head and the printing platform relative to each other such that the print head is positioned above the refill zone prior to the extruder feeding the first strand segment into the strand passage via the first end of the strand passage.

5. The method of claim 1, wherein the 3D printer further comprises a printing platform comprising a feed change area for switching strands, and wherein the printhead and the printing platform are arranged to be translatable relative to each other, the method further comprising:

after causing the strand cutter to cut the strand into the first strand segment and the second strand segment, and before causing the extruder to feed the first strand segment into the strand passageway via the first end of the strand passageway, translating the print head and the printing platform relative to each other such that the print head is positioned above the reload area.

6. The method of claim 4 or 5, further comprising:

after causing the extruder to withdraw the first strand segment back out of the strand passageway, causing the extruder to feed a replacement strand into the strand passageway via the first end of the strand passageway such that the second strand segment is pushed out of the strand passageway by the replacement strand via the second end of the strand passageway.

7. The method of any of claims 1 to 5, further comprising:

causing the extruder to withdraw the strand a predetermined length in a direction away from the second end of the strand passageway before causing the strand cutter to sever the strand into a first strand segment and a second strand segment.

8. A 3D printer, comprising:

a printhead defining a strand channel for passage of a strand, the strand channel comprising a first end and a second end opposite the first end at which the strand is to be melted, the strand channel being provided with a seam resulting from joining of different components of the printhead;

an extruder configured to feed the strand into the strand channel via the first end and extrude the strand via the second end;

a strand cutter disposed between the extruder and the print head; and

a processor configured to execute instructions to implement the method of any one of claims 1-7.

9. A non-transitory computer readable storage medium having instructions stored thereon, wherein the instructions, when executed by the processor of the 3D printer of claim 8, implement the method of any one of claims 1-7.

10. A computer program product comprising instructions, wherein the instructions, when executed by a processor of a 3D printer according to claim 8, implement the method according to any one of claims 1-7.