阅读说明：本技术 热熔挤出装置及成型设备 (Hot melt extrusion device and molding equipment ) 是由 俞红祥 黄少俯 于 2020-07-14 设计创作，主要内容包括：本发明涉及一种热熔挤出装置及成型设备,所述热熔挤出装置包括挤出单元及驱动单元,所述挤出单元用于接收外部物料并加热至熔融并挤出至工作台；所述驱动单元包括驱动部和固定部,所述固定部用于固定至外部固定位置,所述驱动部能够相对于所述固定部运动；所述驱动部连接至所述挤出单元,并能够带动所述挤出单元在挤出工位和间歇工位之间切换；所述挤出单元自所述挤出工位至所述间歇工位切换时的运动速度大于预设值,以使所述挤出单元挤出的熔融状物料发生无屈服断裂,如此,该热熔挤出装置能够改善挤出间断时熔融状物料的拉丝问题。(The invention relates to a hot-melt extrusion device and molding equipment, wherein the hot-melt extrusion device comprises an extrusion unit and a driving unit, wherein the extrusion unit is used for receiving external materials, heating the external materials to be molten and extruding the external materials to a workbench; the driving unit comprises a driving part and a fixing part, wherein the fixing part is used for fixing to an external fixing position, and the driving part can move relative to the fixing part; the driving part is connected to the extrusion unit and can drive the extrusion unit to switch between an extrusion station and an intermittent station; the movement speed of the extrusion unit when switching from the extrusion station to the intermittent station is larger than a preset value, so that the molten material extruded by the extrusion unit is subjected to non-yielding fracture, and the hot-melt extrusion device can solve the problem of wire drawing of the molten material when the extrusion is interrupted.)

1. A hot melt extrusion device, comprising an extrusion unit (100) and a drive unit (200), wherein:

the extrusion unit (100) is used for receiving external materials, heating the external materials to be molten and extruding the external materials to a workbench (500);

the drive unit (200) comprises a drive part (21) and a fixing part (22), the fixing part (22) is used for fixing to an external fixing position, and the drive part (21) can move relative to the fixing part (22);

the driving part (21) is connected to the extrusion unit (100) and can drive the extrusion unit (100) to switch between an extrusion station and an intermittent station; and

the movement speed of the extrusion unit (100) during switching from the extrusion station to the intermittent station is greater than a preset value, so that the molten material extruded by the extrusion unit (100) generates no yield fracture.

2. A hot-melt extrusion device according to claim 1, wherein said extrusion unit (100) is rotatably connected to a fixed position, and said driving portion (21) is capable of driving said extrusion unit (100) to swing around the fixed position so as to switch from said extrusion station to said intermittent station.

3. A hot-melt extrusion device according to claim 2, wherein said driving portion (21) is capable of driving said extrusion unit (100) to swing away from said work table (500) to switch from said extrusion station to said intermittent station.

4. A hot melt extrusion device according to claim 2, wherein the driving portion (21) is linearly movable relative to the fixing portion (22), the driving portion (21) being rotatably connected to the extrusion unit (100).

5. A hot melt extrusion device according to claim 4, wherein said drive unit (200) further comprises a position detection element for limiting a movement stroke of said drive portion (21).

6. A hot melt extrusion apparatus as set forth in claim 5, wherein said position detection sensing element includes first and second position sensing members corresponding to said extrusion station and said intermittent station, respectively.

7. A hot-melt extrusion device according to claim 4, wherein in said drive unit (200): the drive part (21) is configured as a piston rod of an air cylinder or a hydraulic cylinder, and the fixing part (22) is configured as a cylinder barrel of the air cylinder or the hydraulic cylinder.

8. A hot melt extrusion device according to claim 7, wherein said drive unit (200) further comprises an energy storage mechanism for increasing the speed of movement of said drive section (21).

9. A hot-melt extrusion device according to any one of claims 1 to 8, further comprising a flow blocking unit (300), wherein the flow blocking unit (300) is configured to prevent the molten material from continuously flowing out of the extrusion unit (100).

10. A hot-melt extrusion apparatus according to claim 9, wherein said extrusion unit (100) comprises a nozzle (11), an inner cavity (111) is provided in said nozzle (11), and an extrusion port (112) for communicating said inner cavity (111) to the outside is formed on said nozzle (11);

the flow blocking unit (300) comprises a flow blocking element (31) arranged in the inner cavity (111), the flow blocking element (31) divides the inner cavity (111) into a first cavity (1111) close to the extrusion opening (112) and a second cavity (1112) far away from the extrusion opening (112), and the flow blocking element (31) can change the volume ratio of the first cavity (1111) and the second cavity (1112) through displacement or deformation in the inner cavity (111).

11. A hot melt extrusion device according to claim 10, wherein the flow blocking element (31) is provided as a membrane element, the outer circumferential side of which is fixed to the inner circumferential wall of the inner chamber (111), the membrane element being elastically deformable in the inner chamber (111) to change the volume ratio of the first cavity (1111) and the second cavity (1112).

12. Hot melt extrusion device according to claim 10, wherein the flow blocking unit (300) further comprises an actuating mechanism (32), the actuating mechanism (32) comprises a fixed part (321) and a sliding part (322), the fixed part (321) is fixed relative to the extrusion unit (100), the sliding part (322) is capable of sliding relative to the fixed part (321), one end of the sliding part (322) is connected to the flow blocking part (31) to drive the flow blocking part (31) to displace or deform in the inner cavity (111).

13. A hot melt extrusion device according to claim 12, wherein the fixed member (321) is provided with a slideway (3211) for accommodating the sliding member (322) to slide telescopically, and one end of the sliding member (322) far away from the joint of the choke member (31) extends into the slideway (3211).

14. A hot-melt extrusion device according to claim 10, wherein the extrusion unit (100) further comprises a feeding mechanism (12), and the feeding mechanism (12) comprises a feeding cylinder (121) and a pushing member (122) arranged in the feeding cylinder (121) for pushing the molten material to the nozzle (11).

15. A hot-melt extrusion device according to claim 14, characterized in that the pusher (122) is provided as a feed screw.

16. A hot-melt extrusion apparatus according to claim 14, wherein the inner chamber (111) is configured as a stepped hole opened at one end of the feed cylinder (121), and a nozzle element (113) is fitted in a small-diameter portion of the stepped hole, and the nozzle element (113) and a portion of the feed cylinder (121) constitute the nozzle (11).

17. Hot melt extrusion device according to claim 16, wherein the flow stop (31) is provided as a membrane element, the outer edge of which is elastically constrained to the abrupt change in the aperture of the stepped bore.

18. A molding apparatus comprising at least one hot-melt extrusion device according to any one of claims 1 to 17.

Technical Field

The invention relates to the technical field of 3D printing, in particular to a hot-melt extrusion device and forming equipment.

Background

Compared with the traditional numerical control cutting machining technology, the 3D printing technology not only inherits a full-digital three-dimensional entity forming mode, but also can define processing information such as colors, materials and the like related to appearance and functions according to different regions of a three-dimensional digital model in a design stage, so that the 3D printing equipment can not only realize the shape molding of the three-dimensional entity at one time, but also can utilize various material attributes to obtain a multi-material mixed forming body with more advanced functions.

With the rapid reduction of the cost of polymer consumables such as PLA +, PA, TPU, acrylic resin and the like in recent years, the 3D printing technology is promoted to be applied to the industries of hearing aids, orthodontics, sports shoes and the like in batches. For example, some reports suggest that a lattice structured midsole may be manufactured using a selective sintering of SLS powder, photo-curing 3D printer, and a resilient mesh surface may be formed using an FDM 3D printer.

FDM 3D printing equipment generally comprises a heating spray head, a wire feeding mechanism and a movable workbench, wherein the wire feeding mechanism conveys wires to the heating spray head, the heating spray head heats the front ends of the wires to be melted and extrudes the wires to the workbench, the extruded melted wires form a predetermined shape on the surface of the workbench by utilizing X-Y motion of the workbench, and the workbench moves once along the Z-axis direction when printing a layer of section. In the printing process, the molten wire has better fluidity, when the printed shape needs to be cut off temporarily, the outflow of the molten wire needs to be cut off temporarily, and at the time, because the molten wire has certain viscosity and better fluidity, the molten wire is drawn due to the viscosity and is cast due to the fluidity in the cutting process.

Some existing FDM 3D printing apparatuses can alleviate the casting problem to some extent by using a wire drawing back manner or using another mechanism to temporarily close the outlet of the heating nozzle, but the wire drawing problem is caused by the material itself, and no prior art provides a solution to the problem.

Disclosure of Invention

In view of the above, it is necessary to provide a hot-melt extrusion device and a molding apparatus, which can improve the problem of stringing of molten material when the extrusion is interrupted.

A hot melt extrusion device comprises an extrusion unit and a driving unit, wherein:

the extrusion unit is used for receiving external materials, heating the external materials to be molten and extruding the external materials to the workbench;

the driving unit comprises a driving part and a fixing part, wherein the fixing part is used for fixing to an external fixing position, and the driving part can move relative to the fixing part;

the driving part is connected to the extrusion unit and can drive the extrusion unit to switch between an extrusion station and an intermittent station; and

the movement speed of the extrusion unit when switching from the extrusion station to the intermittent station is greater than a preset value, so that the molten material extruded by the extrusion unit is subjected to non-yielding fracture.

In one embodiment, the extrusion unit is rotatably connected to a fixed position, and the driving part can drive the extrusion unit to swing around the fixed position so as to switch from the extrusion station to the intermittent station.

In one embodiment, the driving part can drive the extrusion unit to swing in a direction away from the workbench so as to switch the extrusion station to the intermittent station.

In one embodiment, the driving part can move linearly relative to the fixing part, and the driving part is rotatably connected with the extrusion unit.

In one embodiment, the driving unit further includes a position detecting element for limiting a moving stroke of the driving part.

In one embodiment, the position detection detecting element includes a first position detecting member and a second position detecting member corresponding to the extrusion station and the intermittent station, respectively.

In one embodiment, the drive unit comprises: the driving portion is configured as a piston rod of the air cylinder or the hydraulic cylinder, and the fixing portion is configured as a cylinder tube of the air cylinder or the hydraulic cylinder.

In one embodiment, the drive unit further comprises an energy storage mechanism for increasing the speed of movement of the drive section.

In one embodiment, the hot melt extrusion device further comprises a flow blocking unit, and the flow blocking unit is used for preventing the molten material from continuously flowing out of the extrusion unit.

In one embodiment, the extrusion unit comprises a nozzle, an inner cavity is arranged in the nozzle, and an extrusion port for communicating the inner cavity with the outside is formed on the nozzle; the flow blocking unit comprises a flow blocking piece arranged in the inner cavity, the flow blocking piece divides the inner cavity into a first cavity close to the extrusion opening and a second cavity far away from the extrusion opening, and the flow blocking piece can change the volume ratio of the first cavity to the second cavity through displacement or deformation in the inner cavity.

In one embodiment, the obstructing member is provided as a membrane element having an outer peripheral side fixed to an inner peripheral wall of the inner chamber, the membrane element being elastically deformable in the inner chamber to change a volume ratio of the first chamber to the second chamber.

In one embodiment, the choke unit further includes an actuating mechanism, the actuating mechanism includes a fixed part and a sliding part, the fixed part is fixed relative to the extrusion unit, the sliding part can slide relative to the fixed part, and one end of the sliding part is connected to the choke part to drive the choke part to displace or deform in the inner cavity.

In one embodiment, the fixed part is provided with a slide way for accommodating the sliding part to slide in a telescopic way, and one end of the sliding part, which is far away from the joint of the choked flow part, extends into the slide way.

In one embodiment, the extrusion unit further comprises a feeding mechanism, and the feeding mechanism comprises a feeding cylinder and a pushing member arranged in the feeding cylinder and used for pushing the molten material to the nozzle.

Further, the pushing member is provided as a feed screw.

In one embodiment, the inner cavity is configured as a stepped hole formed at one end of the feeding cylinder, a nozzle element is embedded in a small-diameter part of the stepped hole, and the nozzle element and a part of the feeding cylinder form the nozzle.

In one embodiment, the flow inhibitor is provided as a membrane element, and the outer edge of the membrane element is elastically constrained to the abrupt change of the aperture of the stepped hole.

The second aspect of the invention also provides a molding device, which comprises at least one hot melt extrusion device.

In the hot melt extrusion device and the forming equipment with the same, the driving unit can drive the extrusion unit to be rapidly switched from the extrusion station to the intermittent station, when the speed is higher than the preset value, the molten material extruded by the extrusion unit is not ready to yield and deform and is directly broken, and wire drawing caused by adhesion between the molten material on the extrusion unit and the material extruded to the workbench is avoided. When the device is used, the switching speed of the extrusion unit between the two stations can be reasonably selected according to the equivalent rigidity of the melted materials, meanwhile, when the flow blocking unit is configured in the hot-melt extrusion device, the molten materials are prevented from further flowing out by the action of the flow blocking unit, the molten materials are snapped by the rapid action of the extrusion unit, and the problems of wire drawing and tape casting commonly existing in the hot-melt extrusion device can be well solved.

Drawings

FIG. 1 is a schematic diagram of the construction of one embodiment of a hot melt extrusion apparatus, wherein the extrusion unit is in an intermittent station;

FIG. 2 is an enlarged view of a portion A of the hot melt extrusion apparatus shown in FIG. 1;

FIG. 3 is a view of the hot melt extrusion apparatus shown in FIG. 1 in an extrusion station;

FIG. 4 is an enlarged view of the portion B of the hot melt extrusion apparatus shown in FIG. 3;

FIG. 5 is a schematic view of the structure of the molding apparatus;

FIG. 6 is a schematic view of an extrusion unit of the hot melt extrusion apparatus in an intermittent station;

FIG. 7 is a schematic view of an extrusion unit of the hot melt extrusion apparatus at an extrusion station;

FIG. 8 is a schematic diagram of the configuration of the extrusion unit in the hot melt extrusion apparatus switched from the extrusion station of FIG. 7 back to the intermittent station again;

FIG. 9 is a schematic view of the configuration of the extrusion unit of the hot melt extrusion apparatus at the extrusion station and printing the second layer;

FIG. 10 is a cross-sectional view of the extruded part on a table.

In the figure: 100. an extrusion unit; 11. a nozzle; 111. an inner cavity; 1111. a first cavity; 1112. a second cavity; 112. an extrusion port; 113. a nozzle element; 12. a feeding mechanism; 121. a feeding cylinder; 122. a pushing member;

200. a drive unit; 21. a drive section; 211. a hinge; 22. a fixed part;

300. a flow blocking unit; 31. a flow-impeding component; 32. an actuation mechanism; 321. a fixing member; 3211. a slideway; 322. a sliding member;

400. a supply unit; 41. a hopper; 411. a discharge port; 412. a feed inlet; 42. a delivery pipe; 43. a feeder;

500. a work table;

600. an XY driving unit;

700. and a Z-direction driving unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like are used in the indicated orientations and positional relationships based on the drawings for convenience in describing and simplifying the description, but do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

In the present invention, unless otherwise specifically stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication connection; either directly or indirectly through intervening media, either internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

Referring to fig. 1 to 4, the present invention first provides a hot melt extrusion apparatus. Comprises an extrusion unit 100 and a driving unit 200, wherein: the extrusion unit 100 is used for receiving external materials and heating the external materials to a molten state for extrusion; the driving unit 200 includes a driving part 21 and a fixing part 22, the fixing part 22 is fixed to the outside at a fixed position, and the driving part 21 is movable relative to the fixing part 22. The driving portion 21 is connected to the extrusion unit 100, and is capable of driving the extrusion unit 100 to switch between the extrusion station and the intermittent station. The speed of the extrusion unit 100 moving with the driving part 21 at the time of switching between the two stations is greater than a preset value, so that the molten material extruded by the extrusion unit 100 is subjected to non-yielding fracture.

When the extrusion unit 100 extrudes the molten material onto the working table 500, the material which is extruded from the extrusion unit 100 but does not fall onto the working table 500 is adhered to the material on the working table 500 due to the high viscosity of the molten material, and at this time, if the continuous material needs to be temporarily cut off to meet the molding requirement, the conventional method is to control the extrusion unit to continue extruding the molten material, and then drive the extrusion unit to be far away from the working table through a proper driving mechanism. However, due to the adhesion of the material, the relative distance between the extrusion unit and the working table can cause the adhered material to be elongated and thinned to form a filamentous structure, and the wire drawing effect can cause poor quality of the formed product. However, since the root cause of the stringiness phenomenon is the viscosity of the material after melting, which is an inherent property of the material, it is generally considered in the art that: wire drawing is inevitable and the quality of the formed product can be improved by appropriate post-treatment.

In the present invention, the relative movement speed between the fixing portions 22 of the driving portion 21 is fast enough, so that the molten material extruded by the extruding unit 100 is not deformed or broken in time. The process of elongation and thinning of the molten material under tension is similar to the process of plastic deformation of a metal material after the stress applied to the metal material exceeds the elastic limit of the material from the viewpoint of material mechanics. For example, when the stress of the rod-shaped material exceeds the elastic limit, the section of the material begins to be thinned, the deformation process is plastic deformation, the material cannot recover after the external force is removed, and the material is pulled apart at the later stage. This principle can be regarded as the root cause of the stringiness of the molten material. However, each material needs a certain time to deform, and when a tensile force is rapidly applied to the two ends of the rod-shaped material on the premise of satisfying the snap-off, the material cannot be snapped or deformed in time. When the theory is applied to the breaking of the molten material, the speed required for the material to break without yield can be determined according to the properties of elasticity, viscosity and the like after the material is heated to be molten, and the speed is used as the driving part 21 to drive the extrusion unit 100 to switch from the extrusion station to the intermittent station, so that the molten material can be broken when the wire drawing phenomenon is not generated. For example, the operation of the driving portion 21 may be completed within 10ms so that the molten material is subjected to non-yielding fracture.

As will be understood, the term "yield-free fracture" as used herein means that the molten material is substantially similar to a rigid fracture, without significant necking, sticking, or stringing at the fracture. Of course, there is no emphasis on the phenomenon that the molten material is not constricted or thinned at all, and for example, the material at the fracture may be thinned to some extent, but the degree of deformation is hardly noticeable as compared with the degree of deformation of the cross section during drawing.

In the prior art, when the extrusion unit is driven to switch from the extrusion station to the intermittent station, the distance driving member needs to precisely control the lifting or lowering distance of the extrusion unit, so as to ensure that the displacement of the base unit meets the layer spacing requirement of the molded product. However, in the present invention, the driving unit 200 is a force driving member, which does not require how much distance the extrusion unit 100 is driven to be precisely displaced, but only needs to control the extrusion unit 100 to be displaced at a preset speed, and the force driving member is more concerned about the speed of displacement than the distance driving member. The driving unit 200 may use a common element, such as an air cylinder, a hydraulic cylinder, etc., as an actuating element, in which case the driving portion 21 may be configured as a piston rod of the air/hydraulic cylinder, and the fixing portion 22 is configured as a cylinder barrel of the air/hydraulic cylinder. Alternatively, a quick operation of the driving unit 21 with respect to the fixed unit 22 is realized by a quick operation device driven by an electromagnet.

In one embodiment, the extruding unit 100 is rotatably connected to a fixed position, and the driving portion 21 can drive the extruding unit 100 to swing around the fixed position, so as to realize the switching from the extruding station to the intermittent station. Preferably, the driving unit 21 drives the extruding unit 100 to swing away from the worktable 500.

As described above, the extrusion unit 100 is operated by the driving unit 21 to break the molten material before it is deformed due to tension, thereby preventing the molten material from being drawn, and therefore, the oscillation direction of the extrusion unit 100 may be set to be a direction in which the molten material is pulled, and in one possible embodiment, may oscillate substantially parallel to the table 500. However, since the forming part of the product already exists on the working table 500 during the forming process, the extrusion unit 100 is swung away from the working table 500, which is equivalent to temporarily "raising" the extrusion unit 100 to avoid interference with the forming part on the working table 500 and scraping the surface of the product.

Referring to fig. 2 and 4, the driving part 21 linearly moves with respect to the fixing part 22, and the driving part 21 is rotatably connected to the extruding unit 100. In the illustrated embodiment, the driving part 21 is rotatably coupled to one end of the extruding unit 100 by a hinge 211.

The driving unit 200 may further include a position detecting element for detecting a moving stroke of the driving part 21 with respect to the fixing part 22. In some embodiments, the position detecting elements include first and second position detecting members corresponding to the extrusion station and the intermittent station of the extrusion unit 100.

When the driving unit 200 is provided as an air cylinder or a hydraulic cylinder, the position detecting element may be provided as a stroke switch or the like. The driving unit 200 may further include an energy storage mechanism for constituting a quick-acting circuit for quickly acting the driving part 21. For example, when the extrusion unit 100 is driven by a cylinder to switch the stations, a suitable fast-acting circuit may be selected to control the extension and retraction of the piston rod in the cylinder, and an energy storage mechanism may be used as a part of the fast-acting circuit to increase the extension/retraction speed of the piston rod.

With continued reference to what is shown in fig. 1-4, the extrusion unit 100 includes a nozzle 11 and a feed mechanism 12, in one embodiment: the feeding mechanism 12 includes a feeding cylinder 121 and a pushing member 122 located in the feeding cylinder 121. Referring to fig. 1, when the hot melt extrusion apparatus is used with a hopper 41 in a molding device, external materials may be supplied into an inner cavity of the hopper 41 through a feed port 412 and output to a feed cylinder 121 through a discharge port 411. The pushing member 122 pushes the material in the feeding cylinder 121 to the nozzle 11, heats the material to a molten state in the pushing process, and finally outputs the material from the nozzle 11 into a strip shape with a preset cross-sectional shape.

In the illustrated embodiment, the pusher 122 is a feed screw, such that the feed mechanism 12 is similar in overall construction to a screw extruder. The feeding mechanism 12 heats the material to be molten gradually at an end close to the nozzle 11, and in order to enable the molten material to be extruded from the nozzle 11, the end of the feeding cylinder 121 is communicated with the nozzle 11, so that the molten material can enter the nozzle 11 continuously under the pushing of the feeding screw.

In the prior art, the structural design of a hot-melt extrusion device is mainly applied to hot-melt extrusion of hard polymer wires, when the device is formed, the end part of the wire is inserted into a nozzle device capable of heating, the wire is molten along with the heating of the end part of the wire, and a wire feeding mechanism in forming equipment pushes the wire forwards so as to extrude the molten wire by utilizing the volume change in the nozzle device. When the wire is required to be disconnected temporarily, the wire is usually drawn back through the wire feeding mechanism, and the molten wire is pumped back by utilizing the piston effect formed when the wire is pulled out relative to the heating nozzle device, so that the tape casting is avoided. However, in order to keep the wire feeding process smooth, the chamber of the nozzle device into which the wire is inserted cannot be completely adhered or interfered with the wire, and thus, the piston effect has a limited effect. In particular, when the wire is replaced with an elastic material having a good elasticity, the wire is difficult to push forward or withdraw backward by the wire feeder, and the piston effect is more difficult to be formed.

When the feeding mechanism is adopted, the feeding mechanism can be well suitable for hot melt extrusion of elastic materials and hard polymer wires. Specifically, the material can be granular material, and is conveyed to the nozzle 11 through the pushing and heating of the feeding mechanism 12, and the structure does not have the problem that the material hardness is influenced when the existing wire feeding mechanism pushes the material.

In the hot-melt extrusion apparatus, in addition to the stringing due to the viscosity of the molten material, a problem to be faced is the problem of casting of the molten material. That is, when it is necessary to temporarily stop the continuous extrusion of the material and restart the extrusion from another position, the molten material continues to flow out of the nozzle 11 because the output of the material at the extrusion unit 100 is still continuous. As mentioned above, the existing technique generally uses the suction force generated by the wire feeding mechanism to suck back the flowing material, but the present invention eliminates the wire feeding mechanism, so that other forms of flow blocking unit 300 can be used to prevent the molten material from flowing out of the extruding unit 100. For example, a shut-off valve may be used to temporarily block the nozzle 11, or the pusher 122 may be driven in reverse to temporarily bring the material back in reverse.

However, the material in the feeding cylinder 121 near the discharge port 411 of the hopper 41 is still in a granular state, and only a part of the material near the nozzle 11 is heated to be molten, so that the manner of reversing the pushing member 122 to bring the material back may cause the problem that the pushing member 122 is stuck by the material in some cases, and the flow blocking manner has a certain delay, so that it is difficult to achieve sensitive flow blocking. Therefore, in a preferred embodiment, the flow-blocking unit 300 cooperates with the nozzle 11 to rapidly suck back the molten material directly inside the nozzle 11, preventing it from flowing further.

Specifically, referring to fig. 2 and 4, one end of the feed cylinder 121 is provided with a stepped hole, and the small diameter portion of the stepped hole is provided with the nozzle element 113, so that the structure of the feed cylinder 121 forms a part of the nozzle 11, that is, in the illustrated embodiment, the nozzle 11 is "integrated" with the feed mechanism 12. One end of the nozzle member 113 extends out of the stepped hole, and an inner cavity 111 of the nozzle 11 is formed between the other end and an upper end surface of the stepped hole.

The nozzle member 113 is provided with a through hole extending through its end extending outside the stepped hole to the end inside the inner chamber 111, and one end of the through hole constitutes the extrusion port 112 of the nozzle 11. The flow blocking unit 300 includes a flow blocking member 31, the flow blocking member 31 is disposed in the inner cavity 111, and divides the inner cavity 111 into a first cavity 1111 near the extrusion opening 112 and a second cavity 1112 far from the extrusion opening 112, when the flow blocking member 31 moves or deforms in the inner cavity 111, a volume ratio of the first cavity 1111 to the second cavity 1112 changes, so that the material at the extrusion opening 112 can be normally output or pumped back into the first cavity 1111.

It will be appreciated that when the resistive element 31 changes the volume ratio of the first 1111 and the second 1112 by moving in the inner chamber 111, the resistive element 31 resembles a piston head; when the flow blocking member 31 changes the volume ratio of the first chamber 1111 and the second chamber 1112 in such a manner as to deform itself, the flow blocking member 31 is similar to a membrane element in a diaphragm valve. In either way, since the flow resisting element 31 is disposed in the inner cavity 111, the volume ratio of the first cavity 1111 and the second cavity 1112 can be rapidly changed by the action thereof, so that the molten material at the extrusion opening 112 can be rapidly withdrawn. Compared with the form of the reverse pushing piece 122, the flow blocking mode can avoid the jamming of the feeding mechanism 12, and the material casting problem is well solved. In addition, when the flow blocking unit 300 can rapidly prevent further outflow of the material in the above-described manner, the aforementioned problem of wire drawing can be also assisted to be improved.

In the embodiment shown in fig. 2 and 4, the flow resisting element 31 is a membrane element, and the outer circumference side of the membrane element is fixed to the inner circumference wall of the inner cavity 111, so that the central portion of the membrane element can be largely deformed to significantly change the volume ratio of the first cavity 1111 to the second cavity 1112.

Further, as described above, the inner cavity 111 is a portion of a stepped hole formed in the feeding cylinder 121, and a step is formed at an abrupt hole diameter change position of the stepped hole, and when the choke 31 slides in the inner cavity 111, the step can limit a sliding stroke of the choke 31, and when the choke 31 is provided as a membrane element deformed in the inner cavity 111, an outer edge of the membrane element is elastically constrained at the abrupt hole diameter change position of the stepped hole.

In order to drive the displacement or deformation of the spoiler 31, the spoiler unit 300 may further include an actuating mechanism 32. In one embodiment, the actuating mechanism 32 includes a fixed part 321 and a sliding part 322, one end of the sliding part 322 is connected to the blocking part 31, and the other end is capable of moving relative to the fixed part 321, so as to move or deform the blocking part 31.

Further, a slide 3211 is formed in the fixed member 321, and one end of the sliding member 322 extends into the slide 3211, and the other end extends out of the slide 3211 and is connected to the choke 31. In this manner, the slide 3211 may guide the displacement of the slide 322. In some embodiments, in order to enable the choke 31 to respond rapidly, the slider 322 may be driven to act rapidly in a rapid driving manner similar to the driving unit 200.

Referring to fig. 5, the present invention also provides a molding apparatus including the hot melt extrusion device of any one of the foregoing embodiments. The molding apparatus may further include a supply unit 400, a work table 500, an XY driving unit 600, a Z driving unit 700, a frame and a molding controller, and the like. The supply unit 400 includes the hopper 41 connected to the extrusion unit 100, the feed pipe 42 connected to the feed port 412 of the hopper 41, and the feeder 43. The feeder 43 can be controlled by the forming controller to deliver material from the delivery pipe 42 into the hopper 41. The feeding mechanism 12, the driving unit 200, the actuating mechanism 32, etc. in the hot-melt extrusion device can be controlled by the forming controller to move according to a preset sequence and manner. The supply unit 400 may be fixedly installed at the top of the rack.

The lower surface of the table 500 is connected to an XY driving unit 600 and can be moved relative to the hot melt extrusion device by the XY driving unit 600. The XY direction referred to herein means the horizontal direction shown in fig. 5 and the direction perpendicular to the paper. The hot melt extrusion device is connected to a Z-direction driving unit 700, the Z-direction driving unit 700 may be configured as the distance driving member, and in the figure, the Z-direction driving unit 700 employs a screw nut transmission mechanism driven by a driving source, and the mechanism has high motion precision, so that the Z-direction displacement of the hot melt extrusion device can be precisely controlled.

Referring to fig. 6, in extrusion molding, the extrusion unit 100 may be first controlled to switch to an intermittent station by the driving unit 200; when the forming starts, the forming controller sends a heating instruction to the feeding mechanism 12, so that the feeding mechanism 12 heats the internal materials to a set extrusion temperature in a segmented manner, then the internal materials enter a constant temperature state, the forming controller immediately sends an action instruction to the driving unit 200, so that the driving unit drives the extrusion unit 100 to switch to an extrusion station shown in fig. 7, and sends an instruction to control the extrusion unit 100 to start extruding the materials to the workbench 500, and in the extrusion process, the XY driving unit 600 is used for driving the workbench 500 to translate. After the first extrusion path of the first layer is executed, the molding controller synchronously sends out instructions to the feeding mechanism 12, the actuating mechanism 32 and the driving unit 200, the feeding mechanism 12 is controlled to stop feeding, the sliding piece 322 drives the flow blocking piece 31 to act to suck the material at the extrusion opening 112, and meanwhile, the driving unit 200 drives one end of the extrusion unit 100 with the nozzle 11 to be quickly lifted;

in the state shown in fig. 8, the molding controller issues a positioning command to the XY driving unit 600 so that the work table 500 is rapidly moved and positioned to the start point of the second extrusion path of the first layer; the molding controller synchronously sends out instructions to the feeding mechanism 12, the actuating mechanism 32 and the driving unit 200, the driving unit 200 switches the extrusion unit 100 back to the extrusion station, the feeding mechanism 12 pushes the molten material to the nozzle 11, the actuating mechanism 32 drives the flow blocking piece 31 to reset, the extrusion port 112 extrudes the material again, and the XY driving unit 600 is matched to drive the workbench 500 to translate; after the second extrusion path of the first layer is executed, the molding controller synchronously sends out instructions to the feeding mechanism 12, the actuating mechanism 32 and the driving unit 200 again, the feeding mechanism 12 is controlled to stop feeding, the sliding piece 322 drives the flow blocking piece 31 to act to suck the material at the extrusion opening 112, and meanwhile, the driving unit 200 drives one end of the extrusion unit 100 with the nozzle 11 to rapidly lift up again. And circulating the actions until the first-layer printing is finished.

Then, referring to fig. 9, the molding controller sends a positioning command to the Z-direction driving unit 700 to control the extrusion unit 100 to move up to a height corresponding to the single-layer extrusion thickness, and then, the molding controller sends a positioning command to the XY-driving unit 600 to drive the worktable 500 to move to the extrusion starting point, and repeat the above first-layer printing operation to deposit the newly-formed extrudate on the upper-layer extrudate until the extrusion forming of all layers is completed, and the obtained three-dimensional molded body is attached to the worktable 500. Referring to fig. 10, in forming the shaped product shown in the figure, it is possible to obtain a product with a gradually changing cross section by using the difference in length of the extruded material of each layer.

It is understood that the XY driving unit 600 and the Z-direction driving unit 700 may also be controlled by the aforementioned molding controller. In some embodiments, a plurality of hot-melt extrusion devices may be disposed on the Z-direction driving unit 700, and each hot-melt extrusion device works alternately to realize combined extrusion molding of different elastic granules, and each hot-melt extrusion device works synchronously to realize concurrent extrusion molding of the same three-dimensional part. The XY-direction displacement of each hot-melt extrusion device can be set according to the maximum plane forming range of each hot-melt extrusion device, so that collision and interference between each hot-melt extrusion device and an adjacent extrusion forming part are avoided when the XY-direction driving unit 600 drives the workbench 500 to translate.

In addition, when a plurality of hot-melt extrusion devices are arranged on the Z-direction driving unit 700, each hot-melt extrusion device may use the same elastic material and form a corresponding number of molded parts at the same time, or each hot-melt extrusion device may use different materials to form molded parts having the same shape and different mechanical properties; or, different materials are alternately molded and spliced to form a single molded part, so that each part of the molded part has different mechanical properties, and the molding requirements of the functionally gradient part and the multi-material mixed component part are met.

In addition, the Z-direction driving unit 700 controls the Z-direction movement of the hot melt extrusion device, and the action performed by the extrusion unit 100 to avoid wire drawing is independently driven by the driving unit 200, so that the extrusion unit 100 can act more quickly, and meanwhile, the Z-direction driving unit 700 does not need to act when an extrusion path is switched, the extrusion unit 100 can be directly driven by the driving unit 200 to lift up, the nozzle 11 is prevented from being scratched with the surface of a product deposited and molded on the workbench 500, and the problem of repeated positioning error caused by the fact that the extrusion unit 100 is driven by the Z-direction driving unit 700 to lift up and down is also avoided.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.