Patent Description:
3D printing systems are also known as three-dimensional printers, namely devices capable of implementing rapid prototyping, and the 3D printers can use bonding materials, such as special wax materials, powdered metals or plastics, to manufacture three-dimensional objects by printing layers of bonding materials. Currently, the 3D printing system comprises a 3D printer and a multi-material unit (referred to as "MMU") which can automatically switch the type or color of a wire according to printing requirements and deliver the wire to the 3D printer.

<CIT> discloses a system including a frame and a first pair of rollers coupled to a first side of the frame. The first pair of rollers is configured to support a first end of a pipe reel. The system also includes a first cradle disposed longitudinally between the first pair of rollers and a second pair of rollers coupled to a second side of the frame. The second pair of rollers is configured to support a second end of a pipe reel. The system also includes a second cradle disposed longitudinally between the second pair of rollers, a pipe guide coupled to a third side of the frame between the first and second sides, a pipe brake coupled to the frame, and a pipe re-spooler coupled to the frame.

<CIT> discloses an apparatus for supplying/discharging filaments for a 3D printer. The apparatus comprises: a filament supplying unit winding a filament having a wire shape, and supplying the wound filament; a filament output unit outputting a 3D printout by fusing and discharging the filament supplied from the filament supplying unit; and a driving unit automatically supplying the filament to the filament output unit, and automatically discharging the filament from the filament output unit to the filament supplying unit. A filament can be accurately supplied to an extruder, and a fixed filament can be easily discharged from the extruder.

Embodiments of the present invention provide a material feeding mechanism, a multi-material unit and a 3D printing system.

According to a first aspect of the present invention, provided is a material feeding mechanism, comprising: a main body; an unloading clutch assembly connected to the main body; and a driver assembly configured to drive the unloading clutch assembly to be switchable between (i) a first position relative to the main body in which the unloading clutch assembly is drivingly coupled to a reel to rotate the reel under driving of the driver assembly to wind a wire around the reel; and (ii) a second position relative to the main body in which the unloading clutch assembly is drivingly separated from the reel; wherein the material feeding mechanism further comprising a loading clutch assembly connected to the main body, wherein the driver assembly is further configured to drive the loading clutch assembly to be switchable between (i) a third position relative to the main body in which the loading clutch assembly is drivingly separated from the wire; and (ii) a fourth position relative to the main body in which the loading clutch assembly is drivingly coupled to the wire to pull the wire to be released from the reel under driving of the driver assembly.

According to a second aspect of the present invention, provided is a multi-material unit, comprising: at least one reel around which at least one wire for a 3D printer is wound respectively; and at least one material feeding mechanism, each material feeding mechanism comprising the material feeding mechanism described above, wherein the at least one material feeding mechanism is for use with respective ones of the at least one reel to feed the at least one wire to the 3D printer.

According to a third aspect of the present invention, provided is a 3D printing system, comprising: a 3D printer; at least one reel around which at least one wire for the 3D printer is wound; and at least one material feeding mechanism, each material feeding mechanism comprising: a main body; an unloading clutch assembly connected to the main body; and a driver assembly configured to drive the unloading clutch assembly to be switchable between (i) a first position relative to the main body in which the unloading clutch assembly is drivingly coupled to a corresponding reel of the at least one reel to rotate the corresponding reel under driving of the driver assembly to wind a corresponding wire of the at least one wire around the corresponding reel; and (ii) a second position relative to the main body in which the unloading clutch assembly is drivingly separated from the corresponding reel, and wherein the at least one material feeding mechanism is for use with the corresponding reel of the at least one reel to feed the at least one wire to the 3D printer, wherein each material feeding mechanism further comprises a loading clutch assembly connected to the main body, wherein the driver assembly is further configured to drive the loading clutch assembly to be switchable between (i) a third position relative to the main body in which the loading clutch assembly is drivingly separated from the corresponding wire; and (ii) a fourth position relative to the main body in which the loading clutch assembly is drivingly coupled to the corresponding wire to pull the corresponding wire to be released from the corresponding reel under driving of the driver assembly.

According to the material feeding mechanism, the multi-material unit and the 3D printing system provided by the embodiments of the present invention, the unloading clutch assembly and the driver assembly are arranged on the main body of the material feeding mechanism, such that the driver assembly can drive the unloading clutch assembly to be switched between the first position relative to the main body and the second position relative to the main body. In the first position, the unloading clutch assembly is drivingly coupled to the reel and can rotate the reel under driving of the driver assembly to wind the wire around the reel, thereby preventing the wire from being suspended or accumulated in the material feeding mechanism after unloading, and improving the reliability and tidiness of the multi-material unit. In the second position, the unloading clutch assembly is drivingly separated from the reel, and the 3D printing system can normally print a three-dimensional object.

It is to be understood that although terms such as first, second and third may be used herein to describe various elements, components, regions, layers and/or portion, these elements, components, regions, layers and/or portion should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer or portion from another. Therefore, a first element, component, region, layer or portion discussed below may be referred to as a second element, component, region, layer or portion without departing from the teaching of the present disclosure.

Spatially relative terms such as "under", "below", "lower", "beneath", "above" and "upper" may be used herein for ease of description to describe the relationship between one element or feature and another element(s) or feature(s) as illustrated in the figures. It will be understood that these spatially relative terms are intended to cover different orientations of a device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, an element described as being "below other elements or features" or "under other elements or features" or "beneath other elements or features" will be oriented to be "above other elements or features". Thus, the exemplary terms "below" and "beneath" may cover both orientations "above" and "below". Terms such as "before" or "ahead" and "after" or "then" may similarly be used, for example, to indicate the order in which light passes through elements. The device may be oriented in other ways (rotated by <NUM> degrees or in other orientations), and the spatially relative descriptors used herein are interpreted correspondingly. In addition, it will also be understood that when a layer is referred to as being "between two layers", it may be the only layer between the two layers, or there may also be one or more intermediate layers.

The terms used herein are merely for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an", and "the" are intended to include plural forms as well, unless otherwise explicitly indicted in the context. It is to be further understood that the terms "comprise" and/or "include", when used in this specification, specify the presence of described features, entireties, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, entireties, steps, operations, elements, components and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items, and the phrase "at least one of A and B" refers to only A, only B, or both A and B.

It is to be understood that when an element or a layer is referred to as being "on another element or layer", "connected to another element or layer", "coupled to another element or layer", or "adjacent to another element or layer", the element or layer may be directly on another element or layer, directly connected to another element or layer, directly coupled to another element or layer, or directly adjacent to another element or layer, or there may be an intermediate element or layer. On the contrary, when an element is referred to as being "directly on another element or layer", "directly connected to another element or layer", "directly coupled to another element or layer", or "directly adjacent to another element or layer", there is no intermediate element or layer. However, under no circumstances should "on" or "directly on" be interpreted as requiring one layer to completely cover the underlying layer.

Embodiments of the present disclosure are described herein with reference to schematic illustrations (and intermediate structures) of idealized embodiments of the present disclosure. Because of this, variations in an illustrated shape, for example as a result of manufacturing techniques and/or tolerances, should be expected. Therefore, the embodiments of the present disclosure should not be interpreted as being limited to a specific shape of a region illustrated herein, but should comprise shape deviations caused due to manufacturing, for example. Therefore, the region illustrated in a figure is schematic in nature, and the shape thereof is neither intended to illustrate the actual shape of the region of a device, nor to limit the scope of the present disclosure.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meanings as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It is to be further understood that the terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings thereof in relevant fields and/or in the context of this specification, and will not be interpreted in an ideal or too formal sense, unless thus defined explicitly herein.

In the related art, a multi-material unit may comprise a material guide tube, a reel, a loading friction wheel and a motor connected to the loading friction wheel. A wire is wound around the reel, and an end of the wire is in contact with the friction wheel. During loading, the motor drives the loading friction wheel to rotate forward, so as to deliver the wire into the material guide tube. A 3D printer uses the wire in the material guide tube to achieve printing. When the printing is finished or the wire is replaced, the motor drives the loading friction wheel to rotate reversely so as to withdraw the wire from the material guide tube into the multi-material unit.

However, the wire in the related art is suspended or accumulated in the multi-material unit after being withdrawn, the wire is likely to be entangled in other parts, affecting the normal operation of the multi-material unit, and the messy wire will cause poor tidiness of the multi-material unit.

Embodiments of the present disclosure provide a material feeding mechanism, a multi-material unit and a 3D printing system. A driver assembly and an unloading clutch assembly are provided, wherein the driver assembly can be drivingly coupled to a reel through the unloading clutch assembly, so as to drive the reel to rotate to wind back a wire around the reel, thereby preventing the wire from being suspended or accumulated.

The present disclosure is described in detail below with reference to the embodiments. It will be appreciated that in order to more clearly illustrate the structures of the embodiments of the present disclosure, only a complete structure of some of gears is shown in the drawings of the present disclosure, and that other gears are represented by a cylindrical structure, the structural details of which are not shown.

<FIG> is a schematic structural diagram of a material feeding module in a multi-material unit according to some embodiments of the present disclosure; <FIG> is a right side view of the material feeding module of <FIG>; <FIG> is a left side view of the material feeding module of <FIG>; and <FIG> is a partial schematic structural diagram of the material feeding module of <FIG> with a reel removed.

It will be appreciated that the multi-material unit may comprise at least one material feeding module and a material guide tube (not shown) shared by the at least one material feeding module. When the 3D printer needs to use a wire of a certain color or material, the material feeding module having the wire in the multi-material unit delivers the wire into the material guide tube. A printing motor in the 3D printer pulls the wire in the material guide tube and delivers it to a hot end of the 3D printer to implement a printing operation. In an example of <FIG>, the material feeding module comprises a material feeding mechanism <NUM>, a reel <NUM>, and a reel holder <NUM>. A wire is wound around the reel <NUM>, and the reel <NUM> is rotatably connected to the reel holder <NUM>. The material feeding mechanism <NUM> is connected to the reel holder <NUM>.

<FIG> is an axonometric view of the material feeding mechanism <NUM> in <FIG> at a first angle; <FIG> is a schematic structural diagram of an unloading clutch assembly in the material feeding mechanism of <FIG> in a first position; and <FIG> is a schematic structural diagram of the unloading clutch assembly in the material feeding mechanism of <FIG> in a second position. For ease of illustration, an unloading friction wheel <NUM> shown in <FIG> is hidden in <FIG> and <FIG>. Referring to <FIG>, the material feeding mechanism <NUM> comprises a main body <NUM>, an unloading clutch assembly <NUM> and a driver assembly <NUM>.

The main body <NUM> may be a supporting component of the material feeding mechanism <NUM> that may be connected to the reel holder <NUM>. The main body <NUM> may be made of a common material such as a metallic material or a plastic material.

The unloading clutch assembly <NUM> and the driver assembly <NUM> are both coupled to the main body <NUM>. The unloading clutch assembly <NUM> may be switched between a first position relative to the main body <NUM> (the position shown in <FIG>) and a second position relative to the main body <NUM> (the position shown in <FIG>) under driving of the driver assembly <NUM>.

When the unloading clutch assembly <NUM> is in the first position, the unloading clutch assembly <NUM> may be drivingly coupled to the reel <NUM>. The unloading clutch assembly <NUM> may transfer a driving force output by the driver assembly <NUM> to the reel <NUM> so that the reel <NUM> can rotate under driving of the driver assembly <NUM>, so as to wind the wire around the reel <NUM>.

When the unloading clutch assembly <NUM> is in the second position, the unloading clutch assembly <NUM> is drivingly separated from the reel <NUM>, that is, the driving force of the driver assembly <NUM> cannot be transferred to the reel <NUM>.

The driver assembly <NUM> may comprise a motor capable of outputting a rotational motion or a linear motion, a hydraulic cylinder, an air cylinder, etc. Various structures of the unloading clutch assembly <NUM> may also be possible. In some embodiments, the driver assembly <NUM> may comprise a rotary motor capable of outputting a rotational motion and a linear motor capable of outputting a linear motion, a rotating shaft of the reel <NUM> may be provided with a driven gear, and the unloading clutch assembly <NUM> may comprise a driving gear which can be meshed with the driven gear. In some embodiments, the driver assembly <NUM> may comprise a rotary motor but has no linear motor, as described in further detail below.

In an embodiment where the driver assembly <NUM> comprises a linear motor, the linear motor may be mounted on the main body <NUM>, a motor housing of the rotary motor may be coupled to an output shaft of the linear motor, and an output shaft of the rotary motor may be coaxially connected to the driving gear. The linear motor may synchronously drive the rotary motor and the driving gear to move in a linear direction, so that the driving gear is switched between the first position and the second position. When the driving gear is in the first position, the rotary motor may drive the driving gear to rotate, and the reel <NUM> is driven to rotate through the driven gear meshed with the driving gear, so as to wind the wire around the reel <NUM>. When the driving gear is in the second position, the driving gear is separated from the driven gear, and power cannot be transferred to the driven gear from the rotary motor.

It may be appreciated that when the 3D printer completes printing or wire replacement is required, the driver assembly <NUM> drives the unloading clutch assembly <NUM> to move to the first position relative to the main body <NUM>, and the unloading clutch assembly <NUM> is drivingly coupled to the reel <NUM>. The driver assembly <NUM> can drive the reel <NUM> to rotate through the unloading clutch assembly <NUM>, so as to withdraw the wire from the material guide tube and rewind the wire around the reel <NUM>, thereby preventing the wire from being suspended or accumulated. Further, the wire is prevented from being wound around other components, such that the multi-material unit can normally work with a high reliability. Moreover, the multi-material unit can also be tidier.

When the 3D printer needs to execute a printing operation, the driver assembly <NUM> may, for example, drive the unloading clutch assembly <NUM> to move to the second position relative to the main body <NUM>, so as to separate the unloading clutch assembly <NUM> from the reel <NUM>. The wire in the material guide tube may be continuously delivered to the hot end (not shown) of the 3D printer under driving of the printing motor of the 3D printer. Since the unloading clutch assembly <NUM> is drivingly separated from the reel <NUM>, the unloading clutch assembly <NUM> does not hinder the rotation of the reel <NUM>, the reel <NUM> may freely rotate relative to the reel holder <NUM> under driving of the wire, and the 3D printing system can normally print a three-dimensional object. In addition, the driver assembly <NUM> is not driven by the reel <NUM> during the printing operation, reducing unnecessary abrasion.

With continued reference to <FIG>, in this example, the reel <NUM> may comprise an intermediate body and flanges <NUM> located on two sides of the intermediate body respectively. The intermediate body may be configured to wind the wire, and the flanges <NUM> may each protrude from the intermediate body in a circumferential direction, thereby functioning to block the wire, and preventing the wire from being released from the reel <NUM>.

With continued reference to <FIG>, in some embodiments, the material feeding mechanism <NUM> may further comprise an unloading friction wheel <NUM> rotatably connected to the main body <NUM>. The unloading friction wheel <NUM> has a wheel surface for force fit connection with the flanges <NUM> of the reel <NUM>. When the unloading clutch assembly <NUM> is in the first position, the unloading clutch assembly <NUM> is drivingly coupled to the unloading friction wheel <NUM> to rotate the reel <NUM> through the unloading friction wheel <NUM>. When the unloading clutch assembly <NUM> is in the second position, the unloading clutch assembly <NUM> is drivingly separated from the unloading friction wheel <NUM> so that the unloading clutch assembly <NUM> is drivingly separated from the reel <NUM>.

The unloading friction wheel <NUM> may be of a wheel-like structure, the wheel surface of which may be provided with knurls or other structures. When the unloading clutch assembly <NUM> is in the first position, the unloading clutch assembly <NUM> may be drivingly connected to the unloading friction wheel <NUM>, and the driving force of the driver assembly <NUM> may be transferred to the unloading friction wheel <NUM> through the unloading clutch assembly <NUM> and transferred to the flanges <NUM> through the unloading friction wheel <NUM> so as to drive the reel <NUM> to rotate. Since the wheel surface of the unloading friction wheel <NUM> is provided with the knurls, a static friction force between the wheel surface and the flanges <NUM> may be increased, so that the reel <NUM> can be effectively driven to rotate. This solution is simple in structure and easy to implement. In addition, power is transferred between the reel <NUM> and the material feeding mechanism <NUM> through the surface where the wheel surface of the unloading friction wheel <NUM> is in contact with the flanges <NUM> of the reel <NUM>, without the need for complex design of the structure of the reel <NUM>, and the reel <NUM> may be conveniently taken out of the reel holder <NUM>, facilitating replacement of the reel <NUM>.

<FIG> is a schematic structural diagram of the unloading clutch assembly <NUM> in the material feeding mechanism of <FIG>; and <FIG> is an exploded schematic diagram of the unloading clutch assembly <NUM> of <FIG>. With continued reference to <FIG>, <FIG> and <FIG>, in some embodiments, the driver assembly <NUM> may comprise a driving motor <NUM> connected to the main body <NUM> and a transmission shaft <NUM> drivingly coupled to an output shaft of the driving motor <NUM>. The unloading clutch assembly <NUM> may comprise a first connecting member <NUM>, a first gear <NUM>, and a second gear <NUM>.

The first gear <NUM> is sleeved on the transmission shaft <NUM> and is in form-fit connection to the transmission shaft <NUM>. That is, the first gear <NUM> may be provided with a non-circular through hole, and the transmission shaft <NUM> may have a mating section that matches the non-circular through hole in shape. The transmission shaft <NUM> may be sleeved at the mating section so that the first gear <NUM> may remain stationary relative to the transmission shaft <NUM>. When the transmission shaft <NUM> rotates under driving of the driving motor <NUM>, the first gear <NUM> may rotate together therewith.

The first connecting member <NUM> may be located on one side of the first gear <NUM> in a rotation axis direction of the first gear <NUM>. The first connecting member <NUM> comprises a first end <NUM> sleeved on the transmission shaft <NUM> and a second end <NUM> opposite to the first end <NUM>. The first connecting member <NUM> may be machined from a common material such as metal or plastic. The first end <NUM> of the first connecting member <NUM> may be provided with a first through hole through which the transmission shaft <NUM> may pass.

The second gear <NUM> is rotatably connected to the second end <NUM> of the first connecting member <NUM>. In an example, the second end <NUM> of the first connecting member <NUM> may be provided with a second through hole, and a rotary shaft passes through the second gear <NUM> and the second through hole, so as to connect the second gear <NUM> to the first connecting member <NUM>. In another example, the second end <NUM> of the first connecting member <NUM> is integrally provided with a rotary shaft, which passes through the second gear <NUM>, so as to rotatably connect the second gear <NUM> to the first connecting member <NUM>.

The first gear <NUM> is meshed with the second gear <NUM>. From a position point of view, the first gear <NUM> and the second gear <NUM> are located at the two ends of the first connecting member <NUM> respectively, and the first connecting member <NUM> abuts against the first gear <NUM>. It may be appreciated that although the first end <NUM> of the first connecting member <NUM> is sleeved on the transmission shaft <NUM>, no direct fixation is performed therebetween. The first connecting member <NUM> may be kept relatively fixed through a pressure generated by the abutment against the first gear <NUM>, and the pressure may cause a frictional force between the first connecting member <NUM> and the first gear <NUM>, which allows the first connecting member <NUM> and the second gear <NUM> to be circumferentially pivoted around the transmission shaft <NUM> with the rotation of the transmission shaft <NUM> and the first gear <NUM>. That is, the first gear <NUM>, the second gear <NUM>, and the first connecting member <NUM> may rotate as a whole with the rotation of the transmission shaft <NUM>. In addition, when an external force is present, it may be used to overcome the frictional force between the first connecting member <NUM> and the first gear <NUM> so that the first connecting member <NUM> and the second gear <NUM> can rotate as a whole relative to the first gear <NUM>. That is, the first connecting member <NUM> and the second gear <NUM> may be circumferentially pivoted around the transmission shaft <NUM>.

To allow the first gear <NUM> to abut against the first connecting member <NUM>, the transmission shaft <NUM> may be provided with two shoulders, each of which may have a diameter greater than that of the transmission shaft <NUM>. The two shoulders may be located on two sides of the unloading clutch assembly <NUM> in an axial direction of the transmission shaft <NUM> respectively, the first connecting member <NUM> may abut against one of the shoulders, and the first gear <NUM> may abut against the other shoulder. Rational adjustment of the dimension between the two shoulders allows the first connecting member <NUM> to abut against the first gear <NUM>.

In an example, to allow the second gear <NUM> to drive the unloading friction wheel <NUM> to rotate, the unloading friction wheel <NUM> may comprise a first wheel body and a second wheel body sequentially arranged in an axial direction of the unloading friction wheel <NUM>. The first wheel body and the second wheel body may be integrally machined and formed. The first wheel body has a wheel surface provided with knurls, and the second wheel body may have a plurality of teeth arranged in a circumferential direction. The second wheel body may be configured to mesh with the second gear <NUM>.

Referring to <FIG> and <FIG>, when the 3D printer completes printing or wire replacement is required, the driving motor <NUM> drives the transmission shaft <NUM> to rotate in a first direction (the arrow direction in <FIG>), thereby driving the first connecting member <NUM>, the first gear <NUM> and the second gear <NUM> to rotate as a whole relative to the main body <NUM>, so that the second gear <NUM> can swing to a position where it can be meshed with the second wheel body of the unloading friction wheel <NUM>, that is, the unloading clutch assembly <NUM> is in the first position. Since the unloading friction wheel <NUM> is meshed with the second gear <NUM>, when the driving motor <NUM> continues to drive the transmission shaft <NUM> to rotate in the first direction, the unloading friction wheel <NUM> provides a resistance against the rotation of the second wheel body <NUM> and the first connecting member <NUM> in the circumferential direction of the transmission shaft <NUM>. This resistance can overcome the frictional force between the first connecting member <NUM> and the first gear <NUM>, so that relative rotation occurs between the first gear <NUM> and the first connecting member <NUM>. That is, the first gear <NUM> may continue to rotate with the transmission shaft <NUM>, while the first connecting member <NUM> may remain stationary relative to the main body <NUM>. Since the first gear <NUM> is meshed with the second gear <NUM>, the first gear <NUM> may rotate with the transmission shaft <NUM> to drive the second gear <NUM> to rotate relative to the first connecting member <NUM>, while the second gear <NUM> may drive the unloading friction wheel <NUM> to rotate through the second wheel body and then drive the reel <NUM> to rotate. According to the solution, the structure is simple, the unloading clutch assembly <NUM> can be moved between the first position and the second position through one driving motor <NUM>, so that the cost can be reduced. Referring to <FIG> and <FIG>, when the driving motor <NUM> drives the transmission shaft <NUM> to rotate in a second direction opposite to the first direction, the second gear <NUM> may be drivingly separated from the second wheel body, and the unloading clutch assembly <NUM> is in the second position.

In the embodiment described above, the unloading friction wheel <NUM> comprises the first wheel body configured to be drivingly coupled to the reel <NUM> and the second wheel body configured to be drivingly coupled to the unloading clutch assembly <NUM>. In another embodiments, the material feeding mechanism <NUM> may further comprise a first mating gear <NUM> coaxially connected to the unloading friction wheel <NUM>, as shown in <FIG>. For example, the main body <NUM> may be provided with a rotatable unloading rotary shaft, and the first mating gear <NUM> and the unloading friction wheel <NUM> may be both in form-fit connection to the unloading rotary shaft, so that the machining of the unloading friction wheel <NUM> can be simplified, and the cost can be reduced.

The first mating gear <NUM> is configured such that when the unloading clutch assembly <NUM> is in the first position, the first mating gear <NUM> is meshed with the second gear <NUM> of the unloading clutch assembly <NUM>. The second gear <NUM> may drive the first mating gear <NUM> to rotate and then drive the unloading friction wheel <NUM> to rotate. Moreover, when the unloading clutch assembly <NUM> is in the second position, the first mating gear <NUM> is disengaged from the second gear <NUM> of the unloading clutch assembly <NUM>.

In some embodiments, the unloading clutch assembly <NUM> further comprises a second connecting member <NUM> arranged opposite to the first connecting member <NUM> with respect to the first gear <NUM> and the second gear <NUM>.

With continued reference to <FIG> and <FIG>, the first connecting member <NUM> and the second connecting member <NUM> may be located on two sides of the first gear <NUM> and the second gear <NUM> respectively in the axial direction of the transmission shaft <NUM>. The two sides of the first gear <NUM> may abut against the first connecting member <NUM> and the second connecting member <NUM> respectively.

The second connecting member <NUM> may also be sleeved on the transmission shaft <NUM>, with particular reference to a connection mode between the first end <NUM> of the first connecting member <NUM> and the transmission shaft <NUM>.

In an example, the second end <NUM> of the first connecting member <NUM> is integrally provided with a rotary shaft, the second connecting member <NUM> is provided with a shaft hole at a corresponding position, and the rotary shaft passes through the second gear <NUM> and the shaft hole, so as to rotatably connect the second gear <NUM> between the first connecting member <NUM> and the second connecting member <NUM>. In another example, the second connecting member <NUM> is provided with a rotary shaft, the first connecting member <NUM> is provided with a shaft hole, and the rotary shaft passes through the second gear <NUM> and the shaft hole.

The unloading clutch assembly <NUM> may comprise an elastic clamp member <NUM>. The elastic clamp member <NUM> bridges the first connecting member <NUM> and the second connecting member <NUM> to provide an elastic force enabling the first connecting member <NUM> and the second connecting member <NUM> to clamp the first gear <NUM>. The elastic clamp member <NUM> may continuously provide the elastic force to improve the reliability of the unloading clutch assembly <NUM>.

Various structures of the elastic clamp member <NUM> may be possible. As an example, the elastic clamp member <NUM> may comprise a spring having one end connected to the first connecting member <NUM> and the other end connected to the second connecting member <NUM>. The spring may provide a pulling force such that the first connecting member <NUM> and the second connecting member <NUM> clamp the first gear <NUM>.

As another example, the elastic clamp member <NUM> comprises an elastic clamp member body <NUM> axially extending parallel to the transmission shaft <NUM> and two clamping jaws connected to two ends of the elastic clamp member body <NUM> respectively. For ease of description, the two clamping jaws are named a first clamping jaw <NUM> and a second clamping jaw <NUM> respectively. The first clamping jaw <NUM> abuts against an outer surface of the first connecting member <NUM> facing away from the first gear <NUM> and the second gear <NUM>, and the second clamping jaw <NUM> abuts against an outer surface of the second connecting member <NUM> facing away from the first gear <NUM> and the second gear <NUM>.

The distance between the first clamping jaw <NUM> and the second clamping jaw <NUM> may be smaller than the distance between the outer surface of the first connecting member <NUM> and the outer surface of the second connecting member <NUM>, so that when the elastic clamp member <NUM> bridges the first connecting member <NUM> and the second connecting member <NUM>, the first clamping jaw <NUM> and the second clamping jaw <NUM> may elastically deform relative to the elastic clamp member body <NUM>, and the distance therebetween becomes larger, and accordingly the elastic force for clamping the first connecting member <NUM> and the second connecting member <NUM> can be provided. In addition, the first clamping jaw <NUM>, the second clamping jaw <NUM> and the elastic clamp member body <NUM> may all be arranged against or close to the first connecting member <NUM> and the second connecting member <NUM>, so that the space volume of the unloading clutch assembly <NUM> can be reduced.

In an example, the outer surface of the first connecting member <NUM> is provided with a first groove <NUM>, and the outer surface of the second connecting member <NUM> is provided with a second groove <NUM>. The first clamping jaw <NUM> is provided with a first protrusion 1252a engaged with the first groove <NUM>, and the second clamping jaw <NUM> is provided with a second protrusion 1253a engaged with the second groove <NUM>. This can improve the contact area between the first connecting member <NUM> and the first clamping jaw <NUM>, and between the second connecting member <NUM> and the second clamping jaw <NUM>, so that the elastic clamp member <NUM> is not prone to being released from the first connecting member <NUM> and the second connecting member <NUM>, improving the reliability of the unloading clutch assembly <NUM>.

In some embodiments, the main body <NUM> may also be provided with a first position limiter <NUM> and a second position limiter <NUM>. The unloading clutch assembly <NUM> is movable between the first position limiter <NUM> and the second position limiter <NUM>. The first position limiter <NUM> and the second position limiter <NUM> may be both configured to protrude from the main body <NUM>. Taking the first position limiter <NUM> as an example, the first position limiter <NUM> may comprise a bolt, a threaded section of the bolt may be screwed into a threaded hole of the main body <NUM>, and a head portion of the bolt may be located outside the threaded hole.

The first position limiter <NUM> is positioned on a movement path of the unloading clutch assembly <NUM> relative to the main body <NUM> such that the unloading clutch assembly <NUM> is in the first position when moved to abut against the first position limiter <NUM>. Referring to <FIG> and <FIG>, the first position limiter <NUM> is arranged with respect to the second end <NUM> of the second connecting member <NUM> of the unloading clutch assembly <NUM> such that when the unloading clutch assembly <NUM> is in the first position, an upper edge of the second end <NUM> of the second connecting member <NUM> may abut against the first position limiter <NUM>. The first position limiter <NUM> may provide a resistance against the frictional force between the first connecting member <NUM> and the first gear <NUM> so that the unloading clutch assembly <NUM> may remain in the first position. By means of the first position limiter <NUM>, it is also possible to reduce a contact force between the second gear <NUM> and the first mating gear <NUM>, reduce the abrasion of the two gears, and prolong the service life of the unloading clutch assembly <NUM>.

The second position limiter <NUM> is positioned on a movement path of the unloading clutch assembly <NUM> relative to the main body <NUM> such that the unloading clutch assembly <NUM> is in the second position when moved to abut against the second position limiter <NUM>. Referring to <FIG>, the second position limiter <NUM> is arranged with respect to the second end <NUM> of the second connecting member <NUM> of the unloading clutch assembly <NUM> such that when the unloading clutch assembly <NUM> is in the second position, a lower edge of the second end <NUM> of the second connecting member <NUM> may abut against the second position limiter <NUM>. The second position limiter <NUM> may provide a resistance against the frictional force between the first connecting member <NUM> and the first gear <NUM> so that when the transmission shaft <NUM> continues to rotate in the second direction, the unloading clutch assembly <NUM> may remain in the second position, which can shorten the movement path of the unloading clutch assembly <NUM> and reduce the useless movement of the unloading clutch assembly <NUM>.

It may be appreciated that the size by which the first position limiter <NUM> and the second position limiter <NUM> protrude from the main body <NUM> is greater than a gap between the second connecting member <NUM> and the main body <NUM>, but smaller than a gap between the second gear <NUM> and the main body <NUM>. In this way, the first position limiter <NUM> and the second position limiter <NUM> can play a limiting role but do not interfere with the normal rotation of the second gear <NUM>.

The functions of the first position limiter <NUM> and the second position limiter <NUM> are described above by way of example in which the second connecting member <NUM> of the unloading clutch assembly <NUM> is located between the first connecting member <NUM> and the main body <NUM> (as shown in <FIG>). In some embodiments, the first connecting member <NUM> may be located between the second connecting member <NUM> and the main body <NUM>, and the first position limiter <NUM> and the second position limiter <NUM> may then be configured to abut against an upper edge and a lower edge of the first connecting member <NUM> respectively. The spatially relative terms "upper" and "lower" herein are used with reference to <FIG> and <FIG> and should not be construed as being limiting.

<FIG> is a schematic structural diagram of the material feeding mechanism of <FIG> with the main body <NUM> removed; <FIG> is an axonometric view of the material feeding mechanism <NUM> in <FIG> at a second angle; <FIG> is a schematic structural diagram of the material feeding mechanism of <FIG> with a wire supporting frame removed; <FIG> is a schematic structural diagram of a loading clutch assembly <NUM> in the material feeding mechanism of <FIG> in a third position; and <FIG> is a schematic structural diagram of the loading clutch assembly <NUM> in the material feeding mechanism of <FIG> in a fourth position. The arrow direction in <FIG> is the first direction.

Referring to <FIG>, according to the invention, the material feeding mechanism <NUM> further comprises a loading clutch assembly <NUM>. The loading clutch assembly <NUM> is connected to the main body <NUM>. The loading clutch assembly <NUM> may be switchable between a third position relative to the main body <NUM> (the position as shown in <FIG>) and a fourth position relative to the main body <NUM> (the position as shown in <FIG>) under driving of the driver assembly <NUM>.

When the loading clutch assembly <NUM> is in the third position, the loading clutch assembly <NUM> may be drivingly separated from a wire <NUM>, that is, the driving force of the driver assembly <NUM> cannot be transferred to the wire <NUM>.

When the loading clutch assembly <NUM> is in the fourth position, the loading clutch assembly <NUM> is drivingly coupled to the wire <NUM>, and the loading clutch assembly <NUM> may transfer the driving force output by the driver assembly <NUM> to the wire <NUM>, so as to pull the wire <NUM> to be released from the reel <NUM> under driving of the driver assembly <NUM>.

In an example, the main body <NUM> may be provided with a wire supporting frame <NUM>. The wire <NUM> is wound around the reel <NUM>, and the end of the wire <NUM> may extend out of the reel <NUM> and be located on the wire supporting frame <NUM>. To fully illustrate the structure of the material feeding mechanism <NUM>, the wire wound around the reel <NUM> is not shown in the drawings.

When the 3D printer needs to print a three-dimensional object, the driver assembly <NUM> drives the loading clutch assembly <NUM> to move to the fourth position relative to the main body <NUM>, and the loading clutch assembly <NUM> is drivingly coupled to the wire <NUM>, so that the wire <NUM> can be pulled, so as to deliver the wire <NUM> into the material guide tube.

The driver assembly <NUM> may then, for example, drive the loading clutch assembly <NUM> to move to the third position relative to the main body <NUM>, and the loading clutch assembly <NUM> is drivingly separated from the wire <NUM>. In this way, the printing motor of the 3D printer may pull the wire <NUM> in the material guide tube and implement the printing operation. The driver assembly <NUM> is not required to provide a driving force in this process, so that energy can be saved. Furthermore, since the loading clutch assembly <NUM> is drivingly separated from the wire <NUM>, it is possible to prevent the driving force of pulling the wire <NUM> by the printing motor from being transferred to the driver assembly <NUM>, thereby reducing the load of the printing motor. Moreover, the driver assembly <NUM> is not driven by the wire <NUM> during the printing operation, reducing unnecessary abrasion.

The loading clutch assembly <NUM> may be driven in various manners. For example, the driver assembly <NUM> may comprise a first motor for driving the loading clutch assembly <NUM> to move between the third position and the fourth position, and a second motor for driving the unloading clutch assembly <NUM> to move between the first position and the second position.

In another embodiments, the loading clutch assembly <NUM> and the unloading clutch assembly <NUM> may be driven by using the same driving motor <NUM>. The unloading clutch assembly <NUM> and the loading clutch assembly <NUM> are sleeved at two ends of the transmission shaft <NUM> respectively, and the output shaft of the driving motor <NUM> is drivingly coupled to a portion of the transmission shaft <NUM> between the unloading clutch assembly <NUM> and the loading clutch assembly <NUM>.

In an embodiment, the main body <NUM> may have a first wall surface <NUM> (<FIG>) and a second wall surface <NUM> (<FIG>) which are arranged opposite each other. The driving motor <NUM> may be arranged between the first wall surface <NUM> and the second wall surface <NUM>, and the transmission shaft <NUM> may penetrate through both the first wall surface <NUM> and the second wall surface <NUM>. As shown in <FIG>, the output shaft of the driving motor <NUM> may be coaxially provided with a worm <NUM>, and the portion of the transmission shaft <NUM> between the first wall surface <NUM> and the second wall surface <NUM> may be sleeved with a worm wheel <NUM>. The worm wheel <NUM> cooperates with the worm <NUM> so that the direction of a torque output by the driving motor <NUM> can be changed, simplifying the structure of the material feeding mechanism <NUM>.

Referring to <FIG>, a first end portion of the transmission shaft <NUM> extending beyond the first wall surface <NUM> may be connected to the unloading clutch assembly <NUM>. Referring to <FIG>, a second end portion of the transmission shaft <NUM> extending beyond the second wall surface <NUM> may be connected to the loading clutch assembly <NUM>. To prevent the unloading clutch assembly <NUM> and the loading clutch assembly <NUM> from displacing in the axial direction of the transmission shaft <NUM>, catches <NUM> may also be provided on the transmission shaft <NUM>. The side of the loading clutch assembly <NUM> facing away from the main body <NUM> is provided with a catch <NUM>, and the side of the unloading clutch assembly <NUM> facing away from the main body <NUM> may also be provided with a catch <NUM>.

Referring to <FIG>, in some embodiments, the material feeding mechanism <NUM> further comprises a loading friction wheel <NUM> rotatably connected to the main body <NUM>. The loading friction wheel <NUM> has a wheel surface for force fit connection with the wire <NUM>. When the loading clutch assembly <NUM> is in the third position, the loading clutch assembly <NUM> is drivingly separated from the loading friction wheel <NUM> so that the loading clutch assembly <NUM> is drivingly separated from the wire <NUM>, and when the loading clutch assembly <NUM> is in the fourth position, the loading clutch assembly <NUM> is drivingly coupled to the loading friction wheel <NUM> to pull the wire <NUM> through the loading friction wheel <NUM>.

Referring to <FIG>, the loading friction wheel <NUM> may be of a wheel-like structure, the wheel surface of which may be provided with knurls or other structures. The wheel surface of the loading friction wheel <NUM> may be configured to come into contact with the wire <NUM>, thereby driving the wire <NUM> to move in a tangential direction of the loading friction wheel <NUM>. In an example, the wire <NUM> may be located between the wheel surface of the loading friction wheel <NUM> and the wire supporting frame <NUM>, and the loading friction wheel <NUM> may drive the wire <NUM> to slide along a surface of the wire supporting frame <NUM>. In another example, the main body <NUM> may be provided with a rotatable driven friction wheel, and the wire <NUM> may be located between the wheel surface of the loading friction wheel <NUM> and a wheel surface of the driven friction wheel. When the loading friction wheel <NUM> rotates, the driven friction wheel rotates with the loading friction wheel <NUM> to pull the wire <NUM>, such that the friction force between the wire <NUM> and each of the loading friction wheel <NUM> and the driven friction wheel is rolling friction force, and the wire <NUM> is more easily pulled.

When the loading clutch assembly <NUM> is in the fourth position, the loading clutch assembly <NUM> may be drivingly coupled to the loading friction wheel <NUM>. The driving force of the driver assembly <NUM> may be transferred to the loading friction wheel <NUM> through the loading clutch assembly <NUM>, and transferred to the wire <NUM> through the loading friction wheel <NUM>, so as to drive the wire <NUM> to move. Since the wheel surface of the loading friction wheel <NUM> is provided with the knurls, the static friction force between the wheel surface and the wire <NUM> can be increased, so that the wire <NUM> can be effectively driven to move. This solution is simple in structure and easy to implement, and reduces the production cost.

There are various implementations of the loading clutch assembly <NUM>. In some embodiments, the loading clutch assembly <NUM> is structurally the same as the unloading clutch assembly <NUM>, the functions of the two assemblies differ in that when the loading clutch assembly <NUM> is in the fourth position, the loading clutch assembly <NUM> is drivingly coupled to the wire <NUM>, whereas when the unloading clutch assembly <NUM> is in the first position, the unloading clutch assembly <NUM> is drivingly coupled to the reel <NUM>. That is, the structures to which the unloading clutch assembly <NUM> and the loading clutch assembly <NUM> are drivingly coupled are different.

For example, the loading clutch assembly <NUM> may also comprise a first connecting member, a first gear, and a second gear. The first connecting member comprises a first end sleeved on the transmission shaft <NUM> and a second end opposite to the first end. The first gear is sleeved on the transmission shaft <NUM> and is in form-fit connection to the transmission shaft <NUM>. The second gear is rotatably connected to the second end of the first connecting member and is meshed with the first gear. The first connecting member abuts against the first gear so that the first connecting member and the second gear can be circumferentially pivoted around the transmission shaft <NUM> with the rotation of the transmission shaft <NUM> and the first gear.

In an example, the loading clutch assembly <NUM> further comprises a second connecting member arranged opposite to the first connecting member with respect to the first gear and the second gear.

In an example, the loading clutch assembly <NUM> further comprises an elastic clamp member for bridging the first connecting member and the second connecting member to provide an elastic force enabling the first connecting member and the second connecting member to clamp the first gear.

As an example implementation of the elastic clamp member of the loading clutch assembly <NUM>, the elastic clamp member comprises an elastic clamp member body axially extending parallel to the transmission shaft <NUM> and two clamping jaws connected to two ends of the elastic clamp member body respectively. A first clamping jaw of the two clamping jaws abuts against an outer surface of the first connecting member facing away from the first gear and the second gear, and a second clamping jaw of the two clamping jaws abuts against an outer surface of the second connecting member facing away from the first gear and the second gear.

Further, in the loading clutch assembly <NUM>, the outer surface of the first connecting member may be provided with a first groove, and the outer surface of the second connecting member may be provided with a second groove. The first clamping jaw is provided with a first protrusion engaged with the first groove, and the second clamping jaw is provided with a second protrusion engaged with the second groove.

The first connecting member, the first gear, the second gear, the elastic clamp member and the second connecting member in the loading clutch assembly <NUM> are identical in structure and function to the first connecting member <NUM>, the first gear <NUM>, the second gear <NUM>, the elastic clamp member <NUM> and the second connecting member <NUM> in the unloading clutch assembly <NUM>, and reference can be made specifically to the above description of the unloading clutch assembly <NUM>, which will not be described in detail herein again.

In some embodiments, to allow the second gear of the loading clutch assembly <NUM> to drive the loading friction wheel <NUM> to rotate, the loading friction wheel <NUM> may comprise a third wheel body and a fourth wheel body. The third wheel body and the fourth wheel body may be integrally machined and formed. The third wheel body has a wheel surface provided with knurls, and the fourth wheel body may have a plurality of teeth arranged in a circumferential direction. The fourth wheel body may be configured to mesh with the second gear <NUM>.

In other embodiments, the material feeding mechanism <NUM> may comprise a second mating gear <NUM>. The second mating gear <NUM> is coaxially connected to the loading friction wheel <NUM>, as shown in <FIG>. For example, the main body <NUM> may be provided with a rotatable loading rotary shaft, and the second mating gear <NUM> and the loading friction wheel <NUM> may be both in form-fit connection to the loading rotary shaft, so that the machining of the loading friction wheel <NUM> can be simplified, and the cost can be reduced.

The second mating gear <NUM> is configured such that when the loading clutch assembly <NUM> is in the third position, the second mating gear <NUM> is disengaged from the second gear of the loading clutch assembly <NUM>, and when the loading clutch assembly <NUM> is in the fourth position, the second mating gear <NUM> is meshed with the second gear of the loading clutch assembly <NUM>, and the second gear can drive the second mating gear <NUM> to rotate, thereby driving the loading friction wheel <NUM> to rotate.

Referring to <FIG>, when the 3D printer needs to print a three-dimensional object, the driving motor <NUM> drives the transmission shaft <NUM> to rotate in a second direction (the direction opposite to the arrow direction in <FIG>) so as to drive the first connecting member, the first gear and the second gear of the loading clutch assembly <NUM> to rotate as a whole relative to the main body <NUM>, so that the second gear can swing to a position where it can be meshed with the second mating gear <NUM>, that is, the loading clutch assembly <NUM> is in the fourth position. Since the second mating gear <NUM> is meshed with the second gear, when the driving motor <NUM> continues to drive the transmission shaft <NUM> to rotate in the second direction, the second mating gear <NUM> provides a resistance against the rotation of the second gear and the first connecting member in the circumferential direction of the transmission shaft <NUM>. The resistance can overcome a frictional force between the first connecting member and the first gear, so that relative rotation occurs between the first gear and the first connecting member. That is, the first gear may continue to rotate with the transmission shaft <NUM>, while the first connecting member may remain stationary relative to the main body <NUM>. Since the first gear is meshed with the second gear, the first gear may drive the second gear to rotate relative to the first connecting member, while the second gear may drive the second mating gear <NUM> to rotate, thereby driving the loading friction wheel <NUM> to rotate so as to pull the wire <NUM> to move in a direction from right to left in <FIG> (that is, in <FIG>, the wire <NUM> moves in the arrow direction), so as to deliver the wire <NUM> into the material guide tube. After the wire <NUM> is delivered to the material guide tube, the driving motor <NUM> may, for example, drive the transmission shaft <NUM> to rotate in the first direction (the arrow direction in <FIG>), the second gear of the loading clutch assembly <NUM> may be disengaged from the second mating gear <NUM>, and the loading clutch assembly <NUM> is in the third position (as shown in <FIG>). In this way, the printing motor of the 3D printer can continue to pull the wire in the material guide tube to implement the printing operation.

In some embodiments, the unloading clutch assembly <NUM> and the loading clutch assembly <NUM> are configured such that when the unloading clutch assembly <NUM> is in the first position, the loading clutch assembly <NUM> is in the third position, and when the unloading clutch assembly <NUM> is in the second position, the loading clutch assembly <NUM> is in the fourth position.

In an unloading operation, when the unloading clutch assembly <NUM> is in the position shown in <FIG>, the loading clutch assembly <NUM> is in the position shown in <FIG>. In a loading operation, when the unloading clutch assembly <NUM> is in the position shown in <FIG>, the loading clutch assembly <NUM> is in the position shown in <FIG>.

When the 3D printer completes printing or wire replacement is required, the driver assembly <NUM> drives the unloading clutch assembly <NUM> to be drivingly coupled to the unloading friction wheel <NUM> and drives the loading clutch assembly <NUM> to be drivingly separated from the loading friction wheel <NUM>. The unloading friction wheel <NUM> may drive the reel <NUM> to rotate reversely, thereby winding the wire around the reel <NUM>. During this process, the loading clutch assembly <NUM> is drivingly separated from the loading friction wheel <NUM>, and the loading clutch assembly <NUM> does not hinder the reverse rotation of the reel <NUM>.

When the 3D printer needs to print a three-dimensional object, the driver assembly <NUM> drives the loading clutch assembly <NUM> to be drivingly coupled to the loading friction wheel <NUM> and drives the unloading clutch assembly <NUM> to be drivingly separated from the unloading friction wheel <NUM>. The loading friction wheel <NUM> may pull the wire <NUM> into the material guide tube. In this process, the reel <NUM> rotates forward relative to the reel holder <NUM>, and the unloading clutch assembly <NUM> does not hinder the forward rotation of the reel <NUM>.

It may be appreciated that in some embodiments the driver assembly <NUM> may be implemented by arranging a first motor and a second motor to drive the loading clutch assembly <NUM> and the unloading clutch assembly <NUM> respectively, and in some embodiments it may be implemented through the driving motor <NUM> and the transmission shaft <NUM>.

In an example, the unloading clutch assembly <NUM> and the loading clutch assembly <NUM> are sleeved on the transmission shaft <NUM> such that the unloading clutch assembly <NUM> and the loading clutch assembly <NUM> can be circumferentially pivoted around the transmission shaft <NUM> with the rotation of the transmission shaft <NUM>. The unloading clutch assembly <NUM> and the loading clutch assembly <NUM> are at an angle to each other in the circumferential direction of the transmission shaft <NUM> such that when the unloading clutch assembly <NUM> is circumferentially pivoted around the transmission shaft <NUM> in the first direction to the first position, the loading clutch assembly <NUM> is pivoted in the first direction to the third position, and when the unloading clutch assembly <NUM> is circumferentially pivoted around the transmission shaft <NUM> in a second direction opposite to the first direction to the second position, the loading clutch assembly <NUM> is pivoted in the second direction to the fourth position. Therefore, one driving motor <NUM> may be provided, simplifying the structure of the material feeding mechanism <NUM>.

In some embodiments, the main body <NUM> of the material feeding mechanism <NUM> is further provided with a third position limiter <NUM> and a fourth position limiter <NUM>. The loading clutch assembly <NUM> is movable between the third position limiter <NUM> and the fourth position limiter <NUM>.

The third position limiter <NUM> and the fourth position limiter <NUM> may be both configured to protrude from the main body <NUM>, and reference for the specific implementation may be made to the structure of the first position limiter <NUM>. In an example, the first position limiter <NUM> and the second position limiter <NUM> protrude from the first wall surface <NUM> of the main body <NUM>, and the third position limiter <NUM> and the fourth position limiter <NUM> protrude from the second wall surface <NUM> of the main body <NUM>.

The third position limiter <NUM> is positioned on a movement path of the loading clutch assembly <NUM> relative to the main body <NUM> such that the loading clutch assembly <NUM> is in the third position when moved to abut against the third position limiter <NUM>. The fourth position limiter <NUM> is positioned on a movement path of the loading clutch assembly <NUM> relative to the main body <NUM> such that the loading clutch assembly <NUM> is in the fourth position when moved to abut against the fourth position limiter <NUM>. Referring to <FIG>, the third position limiter <NUM> is arranged with respect to the second end (the smaller one of the two ends of the second connecting member) of the second connecting member (the one of the two connecting members of the loading clutch assembly <NUM> that is closer to the main body <NUM>) of the loading clutch assembly <NUM> such that when the loading clutch assembly <NUM> is in the third position, a left edge of the second end of the second connecting member may abut against the third position limiter <NUM>. The fourth position limiter <NUM> is arranged opposite to the third position limiter <NUM> with respect to the second end of the second connecting member of the loading clutch assembly <NUM> such that when the loading clutch assembly <NUM> is in the fourth position, a right edge of the second end of the second connecting member may abut against the third position limiter <NUM>. The spatially relative terms "left" and "right" herein are used with reference to <FIG> and should not be construed as being limiting.

An example will be taken for description below in which the reverse rotation of the driving motor <NUM> drives the transmission shaft <NUM> to rotate in the first direction, and the forward rotation of the driving motor <NUM> drives the transmission shaft <NUM> to rotate in the second direction. Referring to <FIG> and <FIG>, when the driving motor <NUM> reversely drives the unloading clutch assembly <NUM> to be drivingly coupled to the unloading friction wheel <NUM>, the unloading clutch assembly <NUM> may abut against the first position limiter <NUM>, and the loading clutch assembly <NUM> may abut against the third position limiter <NUM>. When the driving motor <NUM> continues to reversely rotate to drive the reel <NUM> to reversely rotate, the transmission shaft <NUM> continues to rotate in the first direction, and the third position limiter <NUM> can provide a resistance against the frictional force between the first connecting member and the first gear of the loading clutch assembly <NUM>, so that the loading clutch assembly <NUM> remains in the third position. This can shorten the movement path of the loading clutch assembly <NUM> and reduce the useless movement of the loading clutch assembly <NUM>.

Referring to <FIG>, when the driving motor <NUM> rotates forward to drive the loading clutch assembly <NUM> to be drivingly coupled to the loading friction wheel <NUM>, the loading clutch assembly <NUM> may abut against the fourth position limiter <NUM>, and the unloading clutch assembly <NUM> may abut against the second position limiter <NUM>. When the driving motor <NUM> continues to rotate forward, the fourth position limiter <NUM> may provide a resistance against the frictional force between the first connecting member and the first gear of the loading clutch assembly <NUM> so that the loading clutch assembly <NUM> may remain in the fourth position and pull the wire <NUM> through the loading friction wheel <NUM>. By arranging the fourth position limiter <NUM>, a contact force between the second gear and the second mating gear <NUM> can be reduced, the abrasion of the two gears can be reduced, and the service life of the loading clutch assembly <NUM> can be prolonged. In addition, the second position limiter <NUM> may provide the resistance against the frictional force between the first connecting member <NUM> and the first gear <NUM> of the unloading clutch assembly <NUM> so that the unloading clutch assembly <NUM> may remain in the second position.

The specific limiting way of the third position limiter <NUM> and the fourth position limiter <NUM> may refer to the above description of the first position limiter <NUM> and the second position limiter <NUM> and is not described in detail herein again.

An embodiment of the present disclosure further provides a multi-material unit, comprising at least one reel <NUM> and at least one material feeding mechanism <NUM>. At least one wire <NUM> for a 3D printer is respectively wound around the at least one reel <NUM>. The at least one material feeding mechanism <NUM> is for use with respective ones of the at least one reel <NUM> to feed at least one wire <NUM> to the 3D printer.

It may be appreciated that the multi-material unit may comprise a case and at least one (one or more) material feeding module(s) arranged in the case, and that each material feeding module may be provided with one reel <NUM> and one material feeding mechanism <NUM>. That is, the material feeding mechanisms <NUM> and the reels <NUM> in the multi-material unit have a one-to-one correspondence in number, and one reel <NUM> may be wound with one type of wire <NUM> and provided with one material feeding mechanism <NUM>. In an example, each reel <NUM> may be further provided with one reel holder <NUM>. In addition, one material guide tube for guiding the wire toward the hot end of the 3D printer may penetrate the case of the multi-material unit, that is, a plurality of material feeding units may share one material guide tube.

The structure and function of the material feeding mechanism <NUM> are the same as those of the above embodiment, and are not described in detail herein again.

An embodiment of the present disclosure further provides a 3D printing system, comprising a 3D printer and a multi-material unit. The multi-material unit is configured to feed a wire <NUM> to the 3D printer. The 3D printer has a hot end and a printing motor, and the printing motor may be configured to pull the wire <NUM> in a material guide tube and deliver it to the hot end during printing. The hot end may heat and melt the wire <NUM>, and the 3D printer can build a three-dimensional object with a building material layer by layer, which is formed after the wire is molten.

As described above, the multi-material unit may comprise at least one reel <NUM> and at least one material feeding mechanism <NUM>. At least one wire <NUM> for a 3D printer is respectively wound around the at least one reel <NUM>. The at least one material feeding mechanism <NUM> is for use with respective ones <NUM> of the at least one reel <NUM> to feed at least one wire <NUM> to the 3D printer.

As described above, each material feeding mechanism <NUM> comprises a main body <NUM>, an unloading clutch assembly <NUM> connected to the main body <NUM>, and a driver assembly <NUM>. The driver assembly <NUM> is configured to drive the unloading clutch assembly <NUM> to be switchable between a first position relative to the main body <NUM> in which the unloading clutch assembly <NUM> is drivingly coupled to a corresponding reel <NUM> of the at least one reel <NUM> to rotate the corresponding reel <NUM> under driving of the driver assembly <NUM> to wind the corresponding wire <NUM> of the at least one wire <NUM> around the corresponding reel <NUM>; and a second position relative to the main body <NUM> in which the unloading clutch assembly <NUM> is drivingly separated from the corresponding reel <NUM>.

According to the invention, each material feeding mechanism <NUM> further comprises a loading clutch assembly <NUM> connected to the main body <NUM>. The driver assembly <NUM> is further configured to drive the loading clutch assembly <NUM> to be switchable between a third position relative to the main body <NUM> in which the loading clutch assembly <NUM> is drivingly separated from the corresponding wire <NUM>, and a fourth position relative to the main body <NUM> in which the loading clutch assembly <NUM> is drivingly coupled to the corresponding wire <NUM> to pull the corresponding wire <NUM> to be released from the corresponding reel <NUM> under driving of the driver assembly <NUM>.

The specific structure and function of the multi-material unit and the material feeding mechanism <NUM> may refer to the above embodiments and are not described in detail herein again.

In some embodiments, in each material feeding mechanism <NUM> of the multi-material unit of the 3D printing system, the driver assembly <NUM> may also be configured to execute the following operations.

When the material feeding mechanism <NUM> is operated for unloading, the driver assembly <NUM> drives the unloading clutch assembly <NUM> to move to the first position and drives the loading clutch assembly <NUM> to move to the third position.

The "unloading" may occur when printing is completed or wire replacement is required, which may be understood as a process in which the wire <NUM> needs to be withdrawn from the material guide tube and rewound around the reel <NUM>. During unloading, the driver assembly <NUM> drives the unloading clutch assembly <NUM> to be drivingly coupled to the unloading friction wheel <NUM>, and drives the loading clutch assembly <NUM> to be drivingly separated from the loading friction wheel <NUM>. The unloading friction wheel <NUM> may drive the reel <NUM> to rotate reversely, thereby winding the wire around the reel <NUM>. During this process, the loading clutch assembly <NUM> is drivingly separated from the loading friction wheel <NUM>, and the loading clutch assembly <NUM> does not hinder the reverse rotation of the reel <NUM>.

When the material feeding mechanism <NUM> is operated for loading, the driver assembly <NUM> drives the unloading clutch assembly <NUM> to move to the second position and drives the unloading clutch assembly <NUM> to move to the fourth position.

The "loading" may be understood as a process in which the multi-material unit delivers the wire <NUM> required for printing to the material guide tube. During loading, the driver assembly <NUM> drives the loading clutch assembly <NUM> to be drivingly coupled to the loading friction wheel <NUM>, and drives the unloading clutch assembly <NUM> to be drivingly separated from the unloading friction wheel <NUM>. The loading friction wheel <NUM> may pull the wire <NUM> into the material guide tube, and during the process of pulling the wire <NUM>, the reel <NUM> rotates forward relative to the reel holder <NUM>, and the unloading clutch assembly <NUM> does not hinder the forward rotation of the reel <NUM>.

When the material feeding mechanism <NUM> has been operated for loading to allow the 3D printer to perform printing, the driver assembly <NUM> keeps the unloading clutch assembly <NUM> in the second position, keeps the loading clutch assembly <NUM> in the fourth position, and turns off the driver assembly <NUM>.

The "printing" may be understood as a process in which the printing motor in the 3D printer pulls the wire <NUM> in the material guide tube and delivers it to the hot end of the 3D printer. During printing, the driver assembly <NUM> may drive the loading clutch assembly <NUM> to be drivingly coupled to the loading friction wheel <NUM> and drive the unloading clutch assembly <NUM> to be drivingly separated from the unloading friction wheel <NUM>, and then stop the driver assembly <NUM>, for example, a power supply of the driving motor <NUM> may be turned off. Referring to <FIG> and <FIG>, by the driving of the printing motor, the wire <NUM> may continue to move in the arrow direction in <FIG> (the direction from right to left in <FIG>), and the driving force applied to the wire <NUM> by the printing motor may simultaneously drive the loading friction wheel <NUM> to rotate in a clockwise direction in <FIG> and then drive the coaxial second mating gear <NUM> to rotate in the clockwise direction in <FIG>. The second mating gear <NUM> may apply to the second gear of the loading clutch assembly <NUM> a driving force for rotation in a counterclockwise direction relative to the transmission shaft <NUM>, thereby pushing away the second gear, so that the loading clutch assembly <NUM> is drivingly separated from the second mating gear <NUM>, and the loading clutch assembly <NUM> may be located between the third position and the fourth position. Since the driver assembly <NUM> has stopped operating, the transmission shaft <NUM> does not rotate and the unloading clutch assembly <NUM> may remain in the second position. The 3D printer can continue to execute the printing operation, and neither the loading clutch assembly <NUM> nor the unloading clutch assembly <NUM> affects the normal operation of the printing motor.

It may be appreciated that during printing, the loading clutch assembly <NUM> may be located between the third position defined by the third position limiter <NUM> and the fourth position defined by the fourth position limiter <NUM> after being pushed away. When the 3D printing system resumes unloading, the loading clutch assembly <NUM> may rotate in the first direction along with the transmission shaft <NUM> and be brought into the third position, and at this time, the unloading clutch assembly <NUM> moves from the second position to a position between the first position and the second position. When the transmission shaft <NUM> continues to rotate in the first direction, the unloading clutch assembly <NUM> may re-abut against the first position limiter <NUM>, that is, the unloading clutch assembly <NUM> is in the first position. The transmission shaft <NUM> continues to rotate in the first direction and drives the reel <NUM> to rotate reversely through the unloading clutch assembly <NUM> to wind the wire <NUM> around the reel <NUM>.

Similarly, when the 3D printing system resumes loading, the loading clutch assembly <NUM> may rotate in the second direction along with the transmission shaft <NUM> and be brought into the fourth position. At this time, the unloading clutch assembly <NUM> may be located between the first position and the second position. When the transmission shaft <NUM> continues to rotate in the second direction to pull the wire <NUM> for loading, the unloading clutch assembly <NUM> may re-abut against the second position limiter <NUM>, that is, in the second position.

In some embodiments, during the printing operation, the unloading clutch assembly <NUM> may also be located between the first position and the second position and the loading clutch assembly <NUM> may be located between the third position and the fourth position by adjusting a rotation angle of the driving motor <NUM>. The specific angle may be set according to the actual situation.

According to the multi-material unit and the 3D printing system provided by the embodiments of the present disclosure, the unloading clutch assembly <NUM> and the driver assembly are arranged on the main body <NUM> of the material feeding mechanism <NUM>, such that the driver assembly <NUM> can drive the unloading clutch assembly <NUM> to be switched between the first position relative to the main body <NUM> and the second position relative to the main body <NUM>. In the first position, the unloading clutch assembly <NUM> is drivingly coupled to the reel <NUM> and can rotate the reel <NUM> under driving of the driver assembly <NUM> to wind the wire <NUM> around the reel <NUM>, thereby preventing the wire <NUM> from being suspended or accumulated in the material feeding mechanism <NUM> after unloading, and improving the reliability and tidiness of the multi-material unit. In the second position, the unloading clutch assembly <NUM> is drivingly separated from the reel <NUM>, and the 3D printing system can normally print a three-dimensional object.

Although the present disclosure has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered illustrative and schematic, rather than limiting; and the scope of the present invention is only defined by the appended claims.

Claim 1:
A material feeding mechanism (<NUM>), comprising:
a main body (<NUM>);
an unloading clutch assembly (<NUM>) connected to the main body (<NUM>); and
a driver assembly (<NUM>) configured to drive the unloading clutch assembly (<NUM>) to be switchable between (i) a first position relative to the main body (<NUM>) in which the unloading clutch assembly (<NUM>) is drivingly coupled to a reel (<NUM>) to rotate the reel (<NUM>) under driving of the driver assembly (<NUM>) to wind a wire (<NUM>) around the reel (<NUM>); and (ii) a second position relative to the main body (<NUM>) in which the unloading clutch assembly (<NUM>) is drivingly separated from the reel (<NUM>), characterized in that
the material feeding mechanism (<NUM>) further comprises:
a loading clutch assembly (<NUM>) connected to the main body (<NUM>),
wherein the driver assembly (<NUM>) is further configured to drive the loading clutch assembly (<NUM>) to be switchable between (i) a third position relative to the main body (<NUM>) in which the loading clutch assembly (<NUM>) is drivingly separated from the wire (<NUM>); and (ii) a fourth position relative to the main body (<NUM>) in which the loading clutch assembly (<NUM>) is drivingly coupled to the wire (<NUM>) to pull the wire (<NUM>) to be released from the reel (<NUM>) under driving of the driver assembly (<NUM>).