WO2024119457A1

WO2024119457A1 - Crystallization control apparatus and method for producing 3d printing filament

Info

Publication number: WO2024119457A1
Application number: PCT/CN2022/137744
Authority: WO
Inventors: 苗振兴; 戈弋; 罗小帆
Original assignee: 苏州聚复科技股份有限公司
Priority date: 2022-12-08
Filing date: 2022-12-08
Publication date: 2024-06-13
Also published as: CN116348275A; CN116348275B

Abstract

A crystallization control apparatus and method for producing 3D printing filament, 3D printing filament, and a spool. The crystallization control apparatus makes it so that during production, when 3D printing filament is wound back and forth within filament grooves of two spools, the speed of the filament increases each time the filament encounters a groove, ensuring that each section of the 3D printing filament is stretched and thus maintains tension. Mainly, controlling the groove depth of each filament groove of the two spools makes it so that filament located in the middle of two adjacent positions of the two spools only has slight stretching tension, thereby ensuring the tension of the 3D printing filament between a first spool (121) and a second spool (122), and avoiding to the greatest extent possible the stretching of the filament, thereby ensuring dimensional uniformity in the diameter of the filament.

Description

Crystallization control device and method for producing 3D printing wire

Technical Field

The present application relates to the technical field of 3D printing, and in particular to a crystallization control device and method for producing 3D printing wire, 3D printing wire, and a winding wheel.

Background technique

In recent years, the gradually emerging 3D printing, also known as additive manufacturing, is an advanced manufacturing method based on the principle of layer-by-layer material accumulation that has emerged and developed rapidly in the past 30 years. One of the multiple technical routes of 3D printing is material extrusion 3D printing. Due to the advantages of low equipment cost, wide material selection and good molded part performance, this 3D printing method has been widely used in recent years. The material extrusion 3D printing process is based on the extrusion, layer-by-layer accumulation and solidification (such as glass transition, crystallization, solvent volatilization, etc.) of materials in a flowing state (such as molten state, solution, etc.) under pressure, and thus constructs a 3D object. A process that is widely used in material extrusion 3D printing is called fused deposition modeling (FDM) or fused filament fabrication (FFF). Its basic principle is: the thermoplastic polymer wire is transmitted to a high-temperature hot end by gears to melt the polymer. The hot end moves along the cross-sectional contour and filling trajectory of the part under the control of a computer motion control system, and the molten material is extruded at the same time. The material solidifies rapidly and partially fuses with the surrounding material. This process is repeated layer by layer to construct a three-dimensional object.

Material extrusion 3D printing mostly uses continuous wire as its raw material form. The average diameter of the wire is usually about 1.75mm-2.85mm, and it is necessary to ensure good dimensional uniformity. At present, the most common type of material used in 3D printing wire is polylactic acid (PLA). PLA wire for 3D printing is generally prepared by an extrusion process, that is, the thermoplastic polymer is extruded through a screw extruder, cooled and shaped in a water tank, and then rolled up. For polymer materials with a slow crystallization rate such as PLA, since it is quickly cooled after extrusion and there is not enough time for crystallization, the prepared wire is usually in an amorphous state or has only a very low degree of crystallinity. Low crystallinity will lead to poor heat resistance of the wire, and it is more likely to soften prematurely at the cold end of the print head, resulting in poor extrusion and even blocking of the print head. At present, most of the 3D printing PLA wires on the market belong to this category.

Patent CN106715100B discloses a method for preparing high-crystallinity 3D printing PLA filaments. The method achieves high crystallinity of the filaments by post-processing (annealing) the filaments. However, after production practice, it was found that this method requires additional post-processing steps, which increases the complexity of the production process and leads to a low yield rate.

Patent applications CN109483844A and CN209454120U disclose a device and method for controlling crystallinity, which achieves "online crystallization" of polymer extrusion products (without post-processing steps) by increasing the residence time of the wire in the water bath through a roller group, i.e., multi-stage temperature control. However, after production practice, it was found that this method is relatively complicated to operate in actual use and cannot effectively control the dimensional accuracy of the extruded product.

Summary of the invention

In view of the shortcomings of the related technologies mentioned above, the purpose of the present application is to provide a crystallization control device and method for producing 3D printing wires, 3D printing wires, and a winding wheel, which are used to solve technical problems such as the complicated operation of the existing preparation of 3D printing wires and the inability to effectively control the dimensional accuracy of the extruded products.

To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application provides a crystallization control device for producing 3D printing wires, comprising: a temperature control tank, comprising a tank body for containing a fluid, and used to control the temperature of the fluid to control the 3D printing wire passing through the tank body to reach a crystallization temperature; a tension control mechanism, arranged in the temperature control tank, comprising a first winding wheel arranged at the proximal end of the tank body and a second winding wheel arranged at the distal end of the tank body, and used for the 3D printing wire to be wound back and forth between the first winding wheel and the second winding wheel to increase the residence time and residence length of the 3D printing wire in the tank body; wherein a plurality of wire grooves are arranged on the first winding wheel or/and the second winding wheel, and the groove depths of all or part of the plurality of wire grooves are sequentially increased, so as to control the tension of the 3D printing wire passing through the tank body by configuring the winding direction of the 3D printing wire on the first winding wheel and the second winding wheel or/and by configuring the relative rotation speed of the first winding wheel and the second winding wheel.

The second aspect of the present application provides a crystallization control method for producing 3D printing wires, the crystallization control method comprising the following steps: melting a crystalline polymer and extruding a molded wire; passing the extruded 3D printing wire through a first temperature control tank to cool and shape; winding the shaped 3D printing wire on a tension control mechanism located in the second temperature control tank so that the 3D printing wire is retained in the temperature control tank for a preset time under a preset tension to obtain a crystallized polymer material wire; pulling the 3D printing wire out of the tension control mechanism, and winding and storing it after cooling; wherein the tension control mechanism comprises a first winding wheel arranged at the proximal end of the temperature control tank and a second winding wheel arranged at the distal end of the temperature control tank, a plurality of wire grooves are arranged on the first winding wheel or/and the second winding wheel, and the groove depths of all or part of the plurality of wire grooves are sequentially increased, so as to control the tension of the 3D printing wire passing through the temperature control tank by configuring the winding direction of the 3D printing wire on the first winding wheel and the second winding wheel or/and by configuring the relative rotation speed of the first winding wheel and the second winding wheel.

A third aspect of the present application provides a winding wheel for being installed in pairs on a crystallization control device for producing 3D printing wires, the winding wheel comprising a wheel body and a plurality of wire grooves formed on the wheel body for winding the wires, the groove depths of all or part of the plurality of wire grooves increasing sequentially, so as to control the tension of the 3D printing wire passing through the crystallization control device by configuring the winding direction of the 3D printing wire in the pair of winding wheels or/and by configuring the relative rotation speed of the pair of winding wheels.

In summary, the crystallization control device and method and winding wheel for producing 3D printing wire provided by the present application enable the 3D printing wire in the tension control mechanism to be reciprocated in the wire grooves of the two winding wheels, and the linear speed of each wire groove passed through is a little faster than that of the previous wire groove, thereby allowing the 3D printing wire to be stretched in each section to maintain tension. The present application mainly controls the groove depth of each wire groove in the two winding wheels, so that the wire between the two adjacent positions between the two winding wheels has only a slight tensile tension, which not only ensures the tension of the 3D printing wire between the first winding wheel and the second winding wheel, but also avoids the wire stretching to the maximum extent, thereby ensuring the uniformity of the wire diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

The specific features of the present application are shown in the attached claims. The features and advantages of the invention involved in the present application can be better understood by referring to the exemplary embodiments and drawings described in detail below. The drawings are briefly described as follows:

FIG. 1 is a schematic flow chart showing a crystallization control method according to an embodiment of the present application.

FIG. 2 is a schematic structural diagram of a crystallization control device according to an embodiment of the present application.

FIG. 3 is a schematic structural diagram of another embodiment of the crystallization control device of the present application.

FIG. 4 is a schematic structural diagram of a tension control mechanism of the present application in one embodiment.

FIG5 is a schematic diagram of the A-A section in FIG2 .

FIG. 6 is a schematic structural diagram of a winding wheel according to an embodiment of the present application.

FIG7 is a schematic diagram of the cross section taken along line B-B in FIG6 .

FIG8 is a schematic structural diagram of a winding wheel in another embodiment of the present application.

FIG. 9 is a schematic diagram showing a wire web formed between the first winding wheel and the second winding wheel in the present application.

FIG. 10 is a schematic structural diagram of a winding wheel in another embodiment of the present application.

FIG. 11 is a schematic structural diagram of a winding wheel in another embodiment of the present application.

Detailed ways

The following is an explanation of the implementation of the present application by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification.

In the following description, reference is made to the accompanying drawings, which describe several embodiments of the present application. It should be understood that other embodiments may also be used, and that mechanical composition, structure, electrical and operational changes may be made without departing from the spirit and scope of the present disclosure. The following detailed description should not be considered restrictive, and the scope of the embodiments of the present application is limited only by the claims of the published patents. The terms used herein are only for describing specific embodiments and are not intended to limit the present application. Spatially related terms, such as "upper", "lower", "left", "right", "below", "below", "lower", "above", "upper", etc., may be used in the text to facilitate the description of the relationship between an element or feature shown in the figure and another element or feature.

Furthermore, as used in this article, the singular forms "one", "an" and "the" are intended to include plural forms as well, unless there is an indication to the contrary in the context. It should be further understood that the terms "comprising" and "including" indicate the presence of the described features, steps, operations, elements, components, projects, kinds, and/or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and/or groups. The terms "or" and "and/or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and/or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

The present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. The technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

As described in the background technology, the extrusion process commonly used in the field of polymer processing and manufacturing cannot well control the crystallinity of crystalline polymers, which results in that the crystallinity of the final extruded product of crystalline polymers is usually uncontrollable, resulting in unstable or unsatisfactory performance of the product. That is, the traditional process cannot directly obtain high-crystallinity 3D printing PLA wire after processing and molding. For example, the method disclosed in the above patent document CN106715100B stores the wire on a large roll, heats the large roll for crystallization, and then divides the large roll into small roll products. It has been found through production practice that this method increases the post-processing time and the winding time, and there is a certain wire loss, which affects the production efficiency. In addition, the schemes of the above patent documents CN109483844A and CN209454120U are adopted. It has been found through production practice that the length of the wire intended to increase the residence time in the hot water tank is limited, and the production speed of the wire is slow in order to ensure the residence time of the wire; moreover, the resistance to the rotation of each wheel needs to be overcome by pulling the wire, which will cause the wire to be overstretched, thereby affecting the uniformity of the wire size. The above solution can meet the performance requirements at a relatively low production speed, but cannot be effectively used when the speed is further increased, which is not conducive to improving production efficiency and reducing production costs.

To this end, the present application provides a crystallization control device for producing 3D printing wires and a crystallization control method for producing 3D printing wires, which are used to allow the 3D printing wires to directly obtain high crystallinity during the extrusion process, that is, to allow the crystallization to be completed synchronously during the wire production process without the need for any post-processing steps, and to ensure good dimensional uniformity of the wires while ensuring the production efficiency. The crystallization control method of the present application is suitable for semi-crystalline 3D printing wires including polylactic acid (PLA).

In this application, the term "non-crystalline" or "crystalline" can generally be measured by the level of crystallinity. When the crystallinity is high, the attraction between polymer molecules is easy to interact, so the strength is high, but the transparency is poor; on the contrary, the strength is low and the transparency is good, and the volume change is not large when melting, and it is not easy to shrink.

In the present application, the term "wire" generally refers to a material having a small cross-sectional diameter and a long length. For example, the cross-section of the wire may be circular, square or oval.

In this application, the term "comprising" generally means including the features explicitly stated, but not excluding other elements.

In this application, the term "about" generally refers to a variation within a range of 0.5%-10% above or below a specified value, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10% above or below a specified value.

"Polylactic acid" sometimes abbreviated as "PLA" is a high molecular weight polymer synthesized by polymerization of lactide, which is a cyclic dimer of lactic acid or 2-hydroxypropionic acid. Lactic acid is a chiral molecule with two optical isomers, l-lactic acid and d-lactic acid. Usually, l-lactic acid and d-lactic acid are both present in PLA. The composition ratio of l-lactic acid and d-lactic acid is the key factor determining the crystallization behavior of PLA (including crystallinity and crystallization kinetics). Most commercially available PLAs have a predominant l-lactic acid content. When the d-lactic acid content increases, the crystallinity, melting temperature, and crystallization rate will decrease accordingly. When the d-lactic acid content exceeds 15%, the crystallization ability of PLA becomes very weak. Suitable for PLA described in this application, the l-lactic acid content ranges preferably between 85% and 100%. Examples of such PLA materials include 2500HP, 4032D, 2003D, 4043D, and 7001D supplied by Nature Works LLC.

The process of polymer melt cooling and crystallization is roughly as follows: plastic particles are extruded to form polymer melt, and the microstructure is composed of irregularly entangled polymer chains. During the cooling process of the polymer melt at the outlet die, some polymer chains remain in a disordered state, forming an amorphous area; while some polymer chains are regularly arranged, forming a crystalline area. The proportion of the crystalline area is the crystallinity of the polymer material.

The crystallization of polymer materials mainly includes two steps: (1) nucleation, that is, polymer chains or other components form crystal nuclei under certain conditions; (2) crystal growth, that is, polymer chains are arranged regularly around the crystal nuclei to form crystals. For a specific material, its nucleation and crystal growth will be temperature-dependent, that is, there are temperatures T' and T" (where T'<T"), which correspond to the temperature with the fastest nucleation rate and the temperature with the fastest crystal growth, respectively. Some polymer materials can only form crystal nuclei but cannot grow into crystals during the cooling process of the melt. This is because when the melt temperature gradually cools from high temperature, it first reaches near T" (the temperature with the fastest crystal growth). At this time, the molecular chains are active and easy to grow crystals, but there are no crystal nuclei in the melt for the crystals to attach and grow, so no crystallization area is formed in the melt; when the temperature further drops to near T', a large number of crystal nuclei begin to form in the melt, but the temperature at this time and in the subsequent period is too low, making it difficult for the molecular chains to move and unable to arrange regularly around the crystal nuclei to grow crystals. When the cooled material is heated again and the temperature reaches near T", the polymer chains begin to grow crystals from the crystal nuclei. This crystallization behavior is usually called cold crystallization, and polymer materials with cold crystallization behavior can also be called cold crystallized polymers. Common cold crystallized polymers include: polylactic acid, polydimethyl terephthalate, some polyamides, etc.

The cold crystallization behavior can usually be characterized by differential scanning calorimetry (DSC). The characterization method is:

1. Weigh an appropriate amount of sample (usually several milligrams to tens of milligrams) according to the requirements of the specific DSC instrument;

2. Place the sample into the DSC instrument and measure using the following temperature program:

a. Single heating: The sample is heated at a constant heating rate (10-20C/min) to a certain temperature, T _h , which is higher than the highest melting point T _m of the material _and can completely melt all the crystal regions of the material to form a melt;

b. Cooling: Cool the sample at a constant cooling rate (10-20C/min) to a certain temperature T _l , which _is lower than the glass transition temperature T _g of the material and can completely transform the material into a non-fluid solid state;

c. Secondary heating: The sample is heated again at a constant heating rate (10-20C/min) to a certain temperature T _h ', which is higher than the highest melting point T _m of the material _and can completely melt all the crystal regions of the material to form a melt. T _h ' and T _h can be the same or different;

d. Record the heat flow of the first heating, cooling, and second heating processes.

Among them, T _h , T _l and T _h ' can be flexibly selected according to the characteristics of different materials. If the material shows a crystallization peak with a non-zero area (usually an exothermic peak with a lower temperature than the melting peak) during the secondary heating process, it can be judged that the material has cold crystallization behavior. The temperature corresponding to the crystallization peak during the secondary heating process is the cold crystallization temperature T _cold .

For another part of polymer materials, T’>T”, or the two are close, then the nucleation of the material melt during the cooling process occurs before the crystal growth, or nucleation and crystal growth occur simultaneously. This type of polymer usually does not show a cold crystallization peak when tested using the same DSC method as described above, that is, there is no obvious crystallization peak during the secondary heating process. Its crystallization peak usually only appears during the cooling process. The temperature corresponding to the crystallization peak during the cooling process can usually be considered as the crystallization temperature of the material, or Tc.

Most PLA filaments used in FDM/FFF type 3D printing are prepared by melt extrusion process. During the melt extrusion process, fully dried PLA pellets are put into a screw polymer extruder (single screw or twin screw) with a cylindrical die along with other formulation components for continuous extrusion. The extruded material is then cooled, pulled by a tractor to obtain the desired physical size, and finally collected. This process may also use equipment such as melt pumps/gear pumps (to ensure stable output) and laser diameter gauges (real-time measurement of the physical size of the wire).

Please refer to FIG. 1 , which is a schematic flow chart of a crystallization control method of the present application in one embodiment. As shown in the figure, the crystallization control method for producing 3D printing wire of the present application includes the following steps:

Step S10: Melting the crystalline polymer and extruding it into a wire; in an embodiment, the crystalline polymer is melted and extruded into a wire by an extruder for producing 3D printing wires. The crystalline polymer includes polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polypropylene (PP), polyamide (PA), polybutylene terephthalate (PBT), polyoxymethylene (POM), polyvinyl chloride (PVC), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF), polycaprolactone (PCL), polylactic acid (PLA), and one or more copolymers of any of the above polymers; wherein the crystalline polymer also includes one or more of the following components: colorant, pigment, filler, fiber, plasticizer, nucleating agent, heat/UV stabilizer, processing aid, impact modifier;

In the embodiments, the process disclosed in the present application is applicable to most polymer extrusion equipment. Specifically, the extrusion equipment such as the extruder can be selected by the operator according to the actual situation. Common extrusion equipment includes: single screw extruder, twin screw extruder, multi-screw extruder, plunger extruder, blade plasticizing extruder, etc. At the same time, the operator can also select additional equipment according to actual needs, such as melt metering pump, etc.

Step S11: passing the extruded 3D printing wire through a first temperature control tank to cool down and shape; in an embodiment, the temperature control range of the first temperature control tank is between 50°C and 60°C, for example, the first temperature control tank is filled with water with a temperature range of 50°C to 60°C to cool down the high-temperature wire just out of the extruder, so as to melt shape the wire and quickly nucleate it, thereby achieving shaping of the wire.

Step S12: Winding the shaped 3D printing wire on the tension control mechanism located in the second temperature control tank so that the 3D printing wire is retained in the temperature control tank for a preset time under a preset tension to obtain a crystallized polymer material wire.

Please refer to FIG. 2 , which is a schematic structural diagram of a crystallization control device of the present application in one embodiment. As shown in the figure, the crystallization control device 1 includes a second temperature control tank 11 and a tension control mechanism 12 .

The second temperature-controlled tank 11 includes a tank body 110 for containing a fluid, and is used to control the temperature of the 3D printing wire in the tank body 110 by controlling the temperature of the fluid. In an embodiment, the second temperature-controlled tank 11 is installed on a frame 10 and maintained at a certain height above the ground to facilitate operators to perform production operations or maintenance on the second temperature-controlled tank 11.

In one embodiment, the temperature control range of the second temperature control tank 11 is between 80°C and 100°C. For example, the second temperature control tank 11 is filled with water with a preset temperature range of approximately 80°C-100°C. In a preferred embodiment, the temperature of the water contained in the second temperature control tank 11 is approximately between 85°C and 95°C, for example, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C. In a more preferred embodiment, the temperature of the water contained in the second temperature control tank 11 is approximately 90°C, which is used to enhance the linking activity of the polymer in the wire and promote the growth of the crystal zone.

In some embodiments, for example, when the preset temperature in the tank body 110 of the second temperature-controlled tank 11 is higher, such as exceeding 100°C, for example, when producing a certain type of wire, when the preset temperature in the tank body 110 of the second temperature-controlled tank 11 is required to reach between 150°C and 300°C, the tank body 110 of the second temperature-controlled tank 11 may be filled with oil that meets this preset temperature, or a molten low-temperature alloy liquid that meets the above preset temperature (such as a solder alloy melt, etc.), or a high-temperature salt molten liquid that meets the above preset temperature (such as a salt solution), or an airflow that meets the above preset temperature, or steam or mist that meets the above preset temperature.

In other embodiments, for example, in certain production processes, it is necessary to pre-treat the wire shaped in the second temperature-controlled tank 11 at the same time, such as coating certain materials on the surface of the wire or performing micro-pore etching on the surface of the wire. The fluid contained in the tank body 110 of the second temperature-controlled tank 11 can also be a liquid or vapor including a wire coating agent, or a liquid or vapor including a surface etchant. Of course, the fluid can also include a wire coating agent and a liquid or vapor including a surface etchant.

In the above embodiment, in order to monitor the temperature in the second temperature-controlled tank 11 in real time, a temperature sensor 15 for sensing the temperature of the fluid is provided in the tank body 110 thereof. In one embodiment, the temperature sensor 15 is provided on one side of the second temperature-controlled tank 11, for example, near the overflow port on the distal side or the proximal side, such as in the overflow tank 111 shown in FIG. 2 , but is not limited thereto. In actual implementation, the temperature sensor 15 can be provided at any position where the temperature of the fluid in the tank body 110 of the second temperature-controlled tank 11 can be detected.

In an embodiment, a fluid pipeline 14 is provided on one or both sides of the tank body 110 of the second temperature-controlled tank 11, for inputting the fluid of a preset temperature into the internal space of the tank body 110. In an embodiment as shown in FIG2 , the pipeline is provided on one side of the tank body 110 of the second temperature-controlled tank 11 and extends along its long side, and the pipeline includes an inlet 140 for connecting to an external input pipeline and a plurality of outlets (not shown) located inside the tank body 110.

In some other embodiments, for example, in certain production processes, it is necessary to pre-process the wire material shaped in the second temperature-controlled tank 11 at the same time, and the tank body 110 of the second temperature-controlled tank 11 is provided with a combination of one or more devices including infrared radiation, microwave radiation, and alternating magnetic field for radiating the internal space of the tank body 110.

In one embodiment, the second temperature-controlled groove 11 is an elongated groove, for example, an elongated groove with a length of 3-6m. In a preferred embodiment, the second temperature-controlled groove 11 is an elongated groove with a length of 4m. In order to clearly illustrate the positional relationship between the various devices, components, structures, or mechanisms in the embodiments of the present application, the end of the second temperature-controlled groove 11 adjacent to the above-mentioned first temperature-controlled groove is the proximal end, and the end of the second temperature-controlled groove 11 away from the above-mentioned first temperature-controlled groove is the distal end. It should be understood that the above-mentioned proximal end or distal end may also be referred to as the proximal side or the distal side.

In one embodiment, an overflow groove 111 is respectively provided on the proximal side and the distal side of the second temperature control groove 11 for allowing the fluid such as water in the groove body 110 to overflow, and a notch 1110 for allowing the 3D printing wire to pass through is provided on the side wall shared by the overflow groove 111 and the groove body 110, and the notch 1110 is provided corresponding to the guide wheel.

Please refer to FIG3, which is a schematic diagram of the structure of another embodiment of the crystallization control device of the present application. As shown in the figure, in the embodiment shown in FIG3, the notch of the tank body 110 of the second temperature-controlled tank 11 is provided with a cover that can be opened and closed, and the cover 16 is used to cover the notch of the tank body 110 during production, so as to prevent the liquid such as water in the tank body 110 from overflowing, and also to facilitate the stability of the water temperature in the tank body 110. In this embodiment, the cover 16 is provided on one side of the tank body 110 through a plurality of hinge components 17, and one or more handles are provided on the cover 16 to facilitate the operator to operate the cover 16.

It was found in the experiment that the residence time of the melt in each polymer material crystallinity control device is an important factor affecting the crystallinity. The specific residence time can be selected and adjusted by factors such as the crystallization speed of the material and the crystallinity requirements of the final product, the extrusion speed, the length of each polymer material crystallinity control device, the material/implementation scheme of the polymer material crystallinity control device, etc. Therefore, one of the purposes of the crystallization control device of the present application is to increase the storage space of the 3D printing wire to increase the residence time of the 3D printing wire in the second temperature control tank.

Please refer to FIG. 4, which is a schematic diagram of the structure of the tension control mechanism of the present application in one embodiment. As shown in the figure, in this embodiment, the tension control mechanism 12 includes: a first winding wheel 121 and a second winding wheel 122, wherein the first winding wheel 121 is arranged at the proximal end of the second temperature control tank 11, and is adjacent to the overflow tank 111 on the proximal side of the second temperature control tank 11. The second winding wheel 122 is arranged at the distal end of the second temperature control tank 11, and is adjacent to the overflow tank 111 on the distal side of the second temperature control tank 11. The second winding wheel 122 maintains a certain distance from the first winding wheel 121, so that the wire passing through the second temperature control tank 11 is wound back and forth between the first winding wheel 121 and the second winding wheel 122, so as to provide a longer storage space for the 3D printing wire, so as to meet the residence time of the 3D printing wire in the tank body 110 and achieve high crystallinity of the wire.

As shown in FIG9 , a first winding wheel 121 and a second winding wheel 122 are respectively arranged at both ends of the second temperature-controlled tank 11 of the water tank, and the spacing between the first winding wheel 121 and the second winding wheel 122 is l. The 3D printing wire passing through the second temperature-controlled tank 11 sequentially goes from the first circle of the distal second winding wheel 122 to the first circle of the proximal second winding wheel 122, and then returns to the second circle of the distal second winding wheel 122, and then the second circle of the proximal second winding wheel 122, and so on, forming an upper and lower wire mesh between the first winding wheel 121 and the second winding wheel 122. Even if the 3D printing wire runs at a certain speed (for example, a speed of 100 m/min) under the traction of the traction machine, the length of the 3D printing wire in the second temperature-controlled tank 11 is long enough to meet the residence time of the 3D printing wire in the tank body 110 and achieve high crystallinity of the wire, as shown in the test examples and Table 1 described later.

In this embodiment, the crystallization control device for producing 3D printing wires of the present application further includes a first drive motor (not shown) for driving the first winding wheel 121 and a second drive motor (not shown) for driving the second winding wheel 122. In this embodiment, both the first drive motor and the second drive motor are servo motors, which are used to perform the work of preset speeds through control instructions input by the operator. Specifically, the first drive motor and the second drive motor realize the rotation of the wheels at a specific speed through

mechanical structures

1211 and 1222 such as transmission rods and bevel gears.

In order to prevent adjacent wires in the lower wire mesh formed between the first winding wheel 121 and the second winding wheel 122 from contacting or sticking to each other, the bottom of the tank body 110 of the second temperature-controlled tank 11 is provided with a plurality of grooves 111 extending from the proximal end to the distal end. Please refer to Figure 5, which is a schematic diagram of the A-A section in Figure 2. As shown in the figure, each groove of the plurality of grooves 111 is used for allowing a wire to pass through, so that the plurality of grooves 111 can be wound at intervals around adjacent 3D printing wires in the bottom wire mesh/lower wire mesh formed between the first winding wheel 121 and the second winding wheel 122.

As mentioned above, after the 3D printing wire passes through the first temperature control tank for cooling and shaping, it needs to enter the second temperature control tank 11 and stay for a certain period of time to achieve high crystallinity of the wire. Therefore, it is necessary to introduce the wire from the first temperature control tank into the second temperature control tank 11. In an embodiment, the proximal end of the tank body 110 of the second temperature control tank 11 is provided with a first proximal guide wheel 1212 for introducing or leading the 3D printing wire into or out of the first winding wheel 121; and the distal end of the tank body 110 is provided with a second proximal guide wheel 1222 for introducing or leading the 3D printing wire into or out of the second winding wheel 122. In one embodiment, the

guide wheel

1212 or 1222 is installed on one end of a movable swing arm, and the other end of the swing arm is set on a rotating shaft. The swing arm provides a certain degree of freedom of movement to adapt to the high-speed running wire.

In order to make the two winding wheels of the tension control mechanism completely immersed in the liquid of the second temperature control tank 11, or in another embodiment, to make a part (such as the upper part) of the two winding wheels of the tension control mechanism exposed or immersed in the liquid of the second temperature control tank 11 (for example, to make the lower wire net of the upper and lower wire nets wound on the first winding wheel 121 and the second winding wheel 122 immersed in the liquid of the second temperature control tank 11, and the upper wire net exposed from the liquid surface of the second temperature control tank 11), it is necessary to adjust the height of the two winding wheels of the tension control mechanism in the tank body 110 of the second temperature control tank 11. In the embodiment, the first adjustment mechanism 1213 for adjusting the setting height of the first winding wheel 121 is provided at the proximal end of the tank body 110 of the second temperature control tank 11; and the second adjustment mechanism 1223 for adjusting the setting height of the second winding wheel 122 is provided at the distal end of the tank body 110. Specifically, the first adjustment mechanism 1213 and the second adjustment mechanism 1223 are, for example, a combination of a slider and a slide rail, which are fixed after being adjusted to a certain height to achieve height adjustment of the winding wheels.

In the following embodiments, the first winding wheel 121 and the second winding wheel 122 are immersed in the fluid contained in the tank body 110 as an example for description.

Due to the limitation of the internal space of the tank body 110 of the second temperature-controlled tank 11, the wires wound back and forth between the first winding wheel 121 and the second winding wheel 122 form two upper and lower wire nets, and the distance between adjacent wires in the wire net is small. If the wire net or the wires have no tension, the wires in the water will bend and shake with the water flow, and adjacent wires will contact or stick together during the shaking process, thereby affecting the forming size of the wires. However, since the newly formed wires are still softened to a certain extent after being heated by the second temperature-controlled tank 11, if the wires are tensioned or a slightly larger tension is applied, the wires will be stretched thinner, which will also affect the forming size of the wires. For this reason, in the present application, the tension of each section of the wires in the upper and lower wire nets formed by the wires wound back and forth between the first winding wheel 121 and the second winding wheel 122 is reasonably set, that is, it is ensured that the tension of each section of the wires is controllable and uniform, thereby achieving better dimensional accuracy and uniformity.

Please refer to FIG. 6 and FIG. 7 . FIG. 6 is a schematic diagram of the structure of a winding wheel of the present application in one embodiment. FIG. 7 is a schematic diagram of the BB cross-section in FIG. 6 . For the convenience of explanation, FIG. 6 and FIG. 7 take the first winding wheel 121 as an example. In this embodiment, the first winding wheel 121 has a plurality of wire grooves, for example, n+1 wire grooves. The groove depths of the plurality of wire grooves increase according to a preset ratio, so that the diameters of two adjacent wire grooves differ by a fixed ratio or a preset value. For example, in one embodiment, the fixed preset value is a fixed length, for example, the length is e. As shown in FIG. 7 , the diameter of the deepest wire groove (the wire groove with the smallest diameter) is r ₁ , and the diameter of the shallowest wire groove (the wire groove with the largest diameter) is r ₂ . Then the relationship between the number of wire grooves n+1 and the fixed length e is expressed as: r ₂ -r ₁ =n·e. In some embodiments, the diameter r ₁ of the deepest wire groove is designed to be within the diameter r 2 of the shallowest wire groove. ₂ , for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%. In a preferred embodiment, the diameter _r1 of the deepest wire groove is designed to be approximately 90% of the diameter _r2 of the shallowest wire groove.

In another embodiment, the depth of the grooves on the first winding wheel 121 or the second winding wheel 122 is deepened in sequence, but it may not follow a fixed value. For example, the depth variation of a certain groove or several grooves may be adjusted accordingly according to actual needs. For example, in a certain embodiment, since the softening degree of the 3D printing wire when it is first wound in the first groove of the winding wheel is greater than the softening degree of the 3D printing wire when it is in the last groove of the winding wheel (that is, the wire gradually hardens), therefore, in order to ensure the tension of the wire in each section, the depth of the last groove on the first winding wheel 121 or the second winding wheel 122 may be made greater than the depth of the last groove on the first winding wheel 121 or the second winding wheel 122. The depth variation range may be different from that of other wire grooves. For example, the depth variation of the last wire groove is smaller. Please refer to Figure 8, which is a schematic diagram of the structure of the winding wheel of the present application in another embodiment. As shown in the figure, 9 wire grooves are arranged on the winding wheel. Taking the radius variation of the 9 wire grooves in the winding wheel as an example, from right to left with a fixed value of 0.4mm, the radius of the first winding wheel is 50mm, followed by 50.4mm, 50.8mm, 51.2mm, 51.6mm, 52mm, 52.4mm, and 52.8mm respectively. However, the radius of the last wire groove with the shallowest groove is 53mm, that is, the depth variation of the last wire groove is smaller.

As can be seen from the above, the groove depth of each wire groove on the first winding wheel 121 or the second winding wheel 122 is different. Under the fixed angular velocity of the winding wheel, the linear speed of the wire grooves at different positions of the same winding wheel is different. Then, by configuring the winding direction of the 3D printing wire in the first winding wheel 121 and the second winding wheel 122 or by configuring the relative rotation speed of the first winding wheel 121 and the second winding wheel 122, or by configuring the winding direction of the 3D printing wire in the first winding wheel 121 and the second winding wheel 122 and configuring the relative rotation speed of the first winding wheel 121 and the second winding wheel 122, the tension of the 3D printing wire passing through the second temperature control tank 11 is controlled. For example, in a specific embodiment, by reasonably setting the speed ratio of the first winding wheel 121 and the second winding wheel 122, it can be achieved that when the wire passes through each groove of the two winding wheels in turn, the linear speed gradually increases. The difference in line speed between the front and rear provides the pulling force for each section of the wire in the upper and lower wire nets, thus ensuring that the tension of each section of the wire is controllable and uniform, thus achieving better dimensional accuracy and uniformity.

As shown in FIG6 and FIG7 , the first winding wheel 121 has 12 wire grooves for winding 3D printing wires therein. The depths of the 12 wire grooves increase from the right side to the left side of FIG6 and FIG7 , that is, the diameters or radii of the 12 wire grooves decrease from right to left. When the first winding wheel 121 is driven to rotate, the linear speed of the first wire slot on the far right is less than the linear speed of the second wire slot on the right, the linear speed of the second wire slot on the right is less than the linear speed of the third wire slot on the right, and so on, the linear speed of the eleventh wire slot on the right is less than the linear speed of the twelfth wire slot on the right. In other words, when these 12 wire slots are all wound with 3D printing wires and the first winding wheel 121 is driven to rotate, the speed of the 3D printing wire located in each wire slot is from the first circle on the right to the left, and the linear speed of the 12 wire slots of the first winding wheel 121 is an accelerated phenomenon. Therefore, when the 3D printing wire is wound between the first winding wheel 121 and the second winding wheel 122, the wire wound in the 12 wire slots of the first winding wheel 121 is an accelerated process, see the description of Figure 9 below.

It should be understood that when the second winding wheel 122 also adopts the same wire groove design as the first winding wheel 121, and the deepest wire groove of the first winding wheel 121 and the deepest wire groove of the second winding are located on the same side of the groove body 110, the speed of each section of the wire in the upper and lower wire nets formed by the wire wound back and forth between the first winding wheel 121 and the second winding wheel 122 is greater than that of the previous section of the wire, that is, the tension of each section of the wire in the upper and lower wire nets formed by the wire wound back and forth between the first winding wheel 121 and the second winding wheel 122 is greater than the tension of the previous section of the wire.

In one embodiment, the rotational speeds of the first winding wheel 121 and the second winding wheel 122 can also be bound by setting the rotational speed ratio or the rotational speed difference between the first drive motor and the second drive motor. Specifically, the rotational speeds of the first winding wheel 121 and the second winding wheel 122 can be set by input items or selection items provided by a display interface of a control device, such as a touch screen.

In one embodiment, the 3D printing wire is first wound around the deepest wire groove (i.e., the wire groove with the smallest diameter) of the second winding wheel 122, and then wound around the deepest wire groove of the first winding wheel 121, and then wound back and forth between the second winding wheel 122 and the first winding wheel 121 in the order of the wire grooves from deep to shallow, and is led out through the shallowest wire groove (i.e., the wire groove with the largest diameter) of the first winding wheel 121. In this embodiment, the rotation speed of the first winding wheel 121 is set to be greater than the rotation speed of the second winding wheel 122.

In another embodiment, the speed difference of the wire in each section is flexibly adjusted in combination with the state of the wire during the forming process, and the rotational speeds of the first winding wheel 121 and the second winding wheel 122 can be kept equal by setting the first drive motor and the second drive motor. That is, based on the above-mentioned winding method, the rotational speed of the first winding wheel 121 can also be set equal to the rotational speed of the second winding wheel 122.

Please refer to FIG. 9 , which is a schematic diagram of a wire mesh formed between the first winding wheel and the second winding wheel in the present application. As shown in the figure, assuming that the linear speed of the wire groove at the maximum diameter position of the first winding wheel 121 located at the proximal end of the second temperature-controlled tank 11 is v _a , the linear speed of the wire groove at the maximum diameter position of the second winding wheel 122 located at the distal end of the second temperature-controlled tank 11 is v _b , and the traction speed of the 3D printing wire (for example, the traction speed is the speed provided by the traction machine) is v. In the embodiment, the speed ratios ka and k _b of the first winding wheel 121 and the second winding wheel 122 are set by a _program , and respectively represent:

and

Since the first winding wheel 121 and the second winding wheel 122 are both moving as a whole, the angular velocities of the corresponding positions of all the wire grooves in the first winding wheel 121 or the second winding wheel 122 are the same, and the linear velocity of the corresponding wire groove position is proportional to the diameter or radius of the winding wheel. Therefore, the linear velocity of each groove position in the first winding wheel 121 can be calculated, starting from the wire groove position with the largest diameter to the wire groove position with the smallest diameter, which are _va , _va ·(1-e), ..., _va ·(1-n·e).

Correspondingly, the linear velocity of each groove position in the second winding wheel 122 can also be obtained, starting from the groove position with the largest diameter to the groove position with the smallest diameter: v _b , v _b ·(1-e), ..., v _b ·(1-n·e).

In a specific implementation, after obtaining the traction speed of the traction machine, according to the set values of the speed ratios _ka and _kb of the first winding wheel 121 and the second winding wheel 122, the line speeds on the plurality of line slots in the first winding wheel 121 and the second winding wheel 122 are as follows:

The plurality of grooves in the first winding wheel 121 start from the groove with the largest diameter to the groove with the smallest diameter, and the linear speeds of the grooves are sequentially expressed as: v· _ka , v· _ka ·(1-e), ..., v· _ka ·(1-n·e).

The plurality of grooves in the second winding wheel 122 start from the groove with the largest diameter to the groove with the smallest diameter, and the linear speeds of the grooves are sequentially expressed as: v·k _b , v·k _b ·(1-e), ..., v·k _b ·(1-n·e).

By setting the speed parameter values of the first winding wheel 121 and the second winding wheel 122, for example, by setting and controlling the speed of the first winding wheel 121 to be greater than the speed of the second winding wheel 122, assuming that the traction speed of the traction machine is v, the following is achieved:

v≥v· _ka≥v · _kb≥v ·ka·(1-e)≥v· _kb _· (1-e)≥…≥v· _ka ·(1-n·e)≥v· _kb ·(1-n·e).

It can be seen that when the 3D printing wire between the first winding wheel 121 and the second winding wheel 122 is reciprocatingly wound in the wire grooves of the two winding wheels, the linear speed of the 3D printing wire when passing through each wire groove is slightly faster than that of the previous wire groove, so that the 3D printing wire is stretched in each section to maintain tension.

It can be seen from the above relationship that the smaller the difference e is set, the closer the _ka and _kb are set to 1, and the larger the number of wire slots n is set, the closer the line speeds of two adjacent positions are. In this way, it can be ensured that the wire between the two adjacent positions between the first winding wheel 121 and the second winding wheel 122 has only a slight tensile tension, which ensures the tension of the 3D printing wire between the first winding wheel 121 and the second winding wheel 122, and avoids the wire stretching to the maximum extent, thereby ensuring the uniformity of the wire diameter.

Step S13: pulling the 3D printing wire out of the tension control mechanism, and winding and storing it after cooling treatment; in one embodiment, a third temperature control tank is further provided near the far end of the second temperature control tank 11. In the embodiment, the temperature control range of the second temperature control tank 11 is between 15°C and 30°C, for example, the second temperature control tank 11 is filled with water with a preset temperature range of about 15°C-30°C, for example, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C; in a more preferred embodiment, the temperature of the water contained in the third temperature control tank is about 20°C, which is used to cool down/cool the 3D printing wire passing through the third temperature control tank, and then the 3D printing wire is wound up by a winding machine arranged in the production line, which is then convenient for packaging, storage or transportation.

To further illustrate the principles and beneficial effects of this application, this application provides the following test examples:

By setting the first winding wheel 121 and the second winding wheel 122 on both sides of the proximal and distal ends of the second temperature control tank 11, and allowing the 3D printing wire passing through the second temperature control tank 11 to be repeatedly wound between the first winding wheel 121 and the second winding wheel 122 according to a preset sequence, the 3D printing wire can stay for a long time. The wire pulling speed is set to 100m/min, and after comparative testing of the test model, the wire residence time shown in Table 1 below can be obtained:

Table 1:

测试模型Testing the Model	圈数Number of turns	长度(m)Length(m)	牵引速度(m/min)Traction speed (m/min)	停留时间(min)Residence time (min)
直接通过Directly through	//	3.53.5	100100	0.0350.035
绕圈后通过After circling, pass	33	23.123.1	100100	0.2310.231
绕圈后通过After circling, pass	99	69.369.3	100100	0.6930.693

绕圈后通过After circling, pass	1515	102.3102.3	100100	1.0231.023
绕圈后通过After circling, pass	……	……	……	……

It can be seen from Table 1 that when the wire grooves of the first winding wheel 121 and the second winding wheel 122 are designed to be 9-circle grooves, for example, using the winding wheel shown in FIG. 8 above, the 3D printing wire can be retained in the preset temperature environment of the second temperature control bath 11 for 0.693 min. According to the 3D printing wire, the requirement of high crystallinity can be met by retaining it at this ambient temperature for 30 s. This test result shows that the design of the present application is sufficient for the wire to be crystallized online during the processing and forming process.

It should be understood that the crystallization speed of PLA wires of different formulations is different, and the residence time required for full crystallization usually varies from 30s to 2min. Therefore, under the inspiration of the inventive concept of this application, in other embodiments, the second temperature control tank can also be extended and the spacing between the first winding wheel and the second winding wheel can be increased, or the number of wire grooves on the first winding wheel and the second winding wheel can be appropriately increased or decreased, which can meet the retention time of the 3D printing wire in the second temperature control tank.

In the above-mentioned test example in which the wire grooves of the first winding wheel and the second winding wheel are designed to be 9 grooves as shown in Figure 8, the wire pulling speed is set to 100m/min, and the diameter difference between every two adjacent wire grooves in the first winding wheel and the second winding wheel is designed to be 0.8mm, wherein the diameter of the deepest wire groove is 100mm, and the diameter of the shallowest wire groove is 106mm. The number of turns of the wire grooves in the first winding wheel and the second winding wheel is designed to be 9 turns, and the speed ratios of the first winding wheel and the second winding wheel are set to 0.990 and 0.995 respectively. Then, according to actual tests, the line speeds at each position are: 100, 99.5, 99.3, 99.1, 98.6, 98.3, 97.9, 97.6, ..., 93.9, 93.4 respectively. From this test result, it can be seen that the speed of the 3D printing wire from the entrance to the exit is increased by about 7%. Considering that the wire is gradually stretched over a distance of 69.3m, the 3D printing wire can maintain relatively good dimensional stability and meet the design requirements of the process.

In another embodiment, for example, the preset temperature in the second temperature control tank is set between 15°C and 30°C. Based on the inspiration of the above method steps S10-S13, and in view of the process characteristics of the crystallization control device and method of the present application that allow the 3D printing wire to stay in the temperature control tank for a long time and have low stretching, sufficient cooling of the wire that requires low-temperature processing can be achieved, thereby effectively improving the processing quality and efficiency of such wire.

In another embodiment, for example, if the 3D printing wire wound between the first winding wheel and the second winding wheel needs to be kept in a slightly relaxed state in the second temperature control tank to release a part of the wire tensile deformation, the line speed of the latter position can be set to be slightly lower than the line speed of the previous position, for example, the 3D printing wire is first wound around the shallowest wire groove of the second winding wheel, and then wound around the shallowest wire groove of the first winding wheel, and then wound back and forth between the second winding wheel and the first winding wheel according to the order of the wire grooves from shallow to deep, and led out through the deepest wire groove of the first winding wheel. In this embodiment, the rotation speed of the first winding wheel is set to be less than or equal to the rotation speed of the second winding wheel, so that a state in which the 3D printing wire is slightly relaxed is formed, thereby releasing a part of the wire tensile deformation.

Based on the inventive concept of the present application, in some embodiments, the wheel body of the winding wheel can also be divided into two or more sections. Taking the division of the wheel body of the winding wheel into two as an example, the groove depth of the wire groove in the first section decreases in sequence according to a preset ratio or a preset value, and the groove depth of the wire groove in the second section increases in sequence according to a preset ratio or a preset value. Please refer to FIG. 10, which is a schematic structural diagram of a winding wheel in another embodiment of the present application. As shown in the figure, the left and right sections of the winding wheel have 6 wire grooves respectively, that is, there are 12 wire grooves from left to right, wherein the groove depths of the first to sixth grooves from left to right decrease in sequence, presenting a diameter _r1 ＜ _r2 as shown in FIG. 10; presenting a diameter _r2 ＜ _r3 as shown in FIG. 10 (the diameter in FIG. 10 is also shifted to _r2 ＝ _r3 ); the groove depths of the seventh to twelfth grooves increase in sequence, presenting a diameter _r3 ＞ _r24 as shown in FIG. ; The pair of winding wheels are arranged in the same direction at the proximal and distal ends of the temperature control tank (for example, the second temperature control tank), and the 3D printing wire passing through the temperature control tank is repeatedly wound on the pair of winding wheels and rotated. For example, the 3D printing wire first enters from the leftmost 1st wire slot, at which time the line speed is the slowest, and the speed gradually rises between the pair of winding wheels to the 6th wire slot, and then gradually transitions from the 7th wire slot to the gradually deepening 12th wire slot in the middle and later stages of the process. In this way, the wire in the latter stage is slowed down in each stage and has slight relaxation. Of course, in other embodiments, the groove depth of the 7th to 12th wire slots of the winding wheel in Figure 10 can also be kept unchanged, so that the speed of the wire in the latter stage can be kept balanced without stretching or relaxation.

As another variation example under the concept of the present application, please refer to FIG. 11 , which is a schematic structural diagram of a winding wheel of the present application in yet another embodiment. As shown in the figure, the left section and the right section of the winding wheel respectively have 6 wire grooves, that is, there are 12 wire grooves from left to right, wherein the groove depths of the first groove to the sixth groove from left to right increase successively, presenting a diameter r ₁ >r ₂ as shown in FIG. 11 ; the groove depths of the seventh groove to the twelfth groove decrease successively, presenting a diameter r ₁ <r ₂ as shown in FIG. 11 . The pair of winding wheels are arranged in the same direction at the proximal and distal ends of the temperature control tank (for example, the second temperature control tank), and the 3D printing wire passing through the temperature control tank is repeatedly wound on the pair of winding wheels and rotated. For example, the 3D printing wire first enters from the leftmost 1st wire slot, at which time the wire speed is the fastest, and the speed gradually decreases between the pair of winding wheels to the 6th wire slot, and then gradually transitions from the 7th wire slot to the gradually shallower 12th wire slot in the middle and later stages of the process. In this way, the wire in the later stage can be accelerated in each stage, and then the wire can be slightly tightened.

The present application further provides a 3D printing wire, which is prepared by the crystallization control method described in Figures 1 to 9 and the crystallization control device, and the 3D printing wire is a semi-crystalline 3D printing wire including polylactic acid (PLA). In an embodiment, in addition to PLA, the wire may also contain other ingredients, for example, including but not limited to: colorants, pigments, fillers, fibers, plasticizers, nucleating agents, heat/UV stabilizers, processing aids, impact modifiers and other additives. The average diameter of the 3D printing wire is usually 1.75 mm or 2.85 mm.

In some embodiments, the average diameter of the 3D printing wire is 1.55 mm-1.95 mm (for example, it can be 1.55 mm, 1.56mm, 1.57mm, 1.58mm, 1.59mm, 1.60mm, 1.61mm, 1.62mm, 1.63mm, 1.64mm, 1.65mm, 1.66mm, 1.67mm, 1.68mm, 1.69mm, 1.70mm, 1.71mm, 1.72mm, 1.73mm, 1.74mm, 1.75mm, 1.76mm, 1.77mm, 1.78mm, 1.79mm, 1.80mm, 1.81mm, 1.82mm, 1.83mm, 1.84mm, 1.85mm, 1.86mm, 1.87mm, 1.88mm, 1.89mm, 1.90mm, 1.91mm, 1.92mm, 1.93mm, 1.94mm, or 1.95mm).

In other embodiments, the average diameter of the 3D printing wire is 2.65mm-3.15mm (for example, it can be 2.65mm, 2.66mm, 2.67mm, 2.68mm, 2.69mm, 2.70mm, 2.71mm, 2.72mm, 2.73mm, 2.74mm, 2.75mm, 2.76mm, 2.77mm, 2.78mm, 2.79mm, 2.80mm, 2.81mm, 2.82mm, 2.83mm, 2.84mm, 2.85mm, 2.86mm, 2.87mm m, 2.88mm, 2.89mm, 2.90mm, 2.91mm, 2.92mm, 2.93mm, 2.94mm, 2.95mm, 2.96mm, 2.97mm, 2.98mm, 2.99mm, 3.00mm, 3.01mm, 3.02mm, 3.03mm, 3.04mm, 3.05mm, 3.06mm, 3.07mm, 3.08mm, 3.09mm, 3.10mm, 3.11mm, 3.12mm, 3.13mm, 3.14mm, or 3.15mm).

The present application also provides a winding wheel for being installed in pairs on a crystallization control device for producing 3D printing wires. The winding wheel includes a wheel body and a plurality of wire grooves formed on the wheel body for winding the wires.

As shown in Figures 2 to 9 above, the groove depths of all or part of the plurality of grooves are sequentially increased so that the tension of the 3D printing wire passing through the crystallization control device can be controlled by configuring the winding direction of the 3D printing wire on the paired winding wheels or/and by configuring the relative rotation speed of the paired winding wheels.

In one embodiment, the depths of all or part of the plurality of wire grooves are sequentially increased according to a preset ratio or preset value, such as the various embodiments shown in FIG. 6 to FIG. 8 .

In one embodiment, the winding wheel has n+1 grooves, wherein the diameters of every two adjacent grooves differ by a length e, the diameter of the deepest groove is r ₁ , and the diameter of the shallowest groove is r ₂ , then r ₂ -r ₁ =n·e, and the ratio of r ₁ to r ₂ ranges from 80% to 99%. Please refer to FIG. 6 and FIG. 7. In this embodiment, the winding wheel 121 has a plurality of wire grooves, for example, n+1 wire grooves. The groove depths of the plurality of wire grooves increase according to a preset ratio, so that the diameters of two adjacent wire grooves differ by a fixed ratio or a preset value. For example, in one embodiment, the fixed preset value is a fixed length, for example, the length is e. As shown in FIG. 7, the diameter of the deepest wire groove (the wire groove with the smallest diameter) is _r1 , and the diameter of the shallowest wire groove (the wire groove with the largest diameter) is _r2 . Then, the relationship between the number of wire grooves n+1 and the fixed length e is expressed as: _r2 - _r1 =n·e. In some embodiments, the diameter _r1 of the deepest wire groove is designed to be within the diameter r2 of the shallowest wire groove. ₂ , for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%. In a preferred embodiment, the diameter _r1 of the deepest wire groove is designed to be approximately 90% of the diameter _r2 of the shallowest wire groove.

In summary, the crystallization control device and method for producing 3D printing wires, and the winding wheels provided by the present application enable the 3D printing wires in the tension control mechanism to be reciprocated in the wire grooves of the two winding wheels, and the linear speed of each wire groove passed through is a little faster than that of the previous wire groove, thereby allowing the 3D printing wires to be stretched in each section to maintain tension. The present application mainly controls the groove depth of each wire groove in the two winding wheels, so that the wire between the two adjacent positions between the two winding wheels has only a slight tensile tension, which not only ensures the tension of the 3D printing wire between the first winding wheel and the second winding wheel, but also avoids the wire stretching to the maximum extent, thereby ensuring the uniformity of the wire diameter.

The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

A crystallization control device for producing 3D printing wire, characterized by comprising:

A temperature-controlled tank, comprising a tank body for containing a fluid, and used to control the temperature of the fluid so that the 3D printing wire in the tank body reaches a crystallization temperature;

A tension control mechanism is disposed in the temperature control tank, comprising a first winding wheel disposed at the proximal end of the tank body and a second winding wheel disposed at the distal end of the tank body, for allowing the 3D printing wire to be wound back and forth between the first winding wheel and the second winding wheel to increase the residence time and residence length of the 3D printing wire in the tank body;

Wherein, a plurality of wire grooves are arranged on the first winding wheel or/and the second winding wheel, and the groove depths of all or part of the plurality of wire grooves are sequentially increased, so as to control the tension of the 3D printing wire passing through the groove body by configuring the winding direction of the 3D printing wire on the first winding wheel and the second winding wheel or/and by configuring the relative rotation speed of the first winding wheel and the second winding wheel.
According to claim 1, the crystallization control device for producing 3D printing wire is characterized in that the fluid contained in the tank includes: water at a preset temperature, oil at a preset temperature, molten low-temperature alloy liquid at a preset temperature, high-temperature salt molten liquid at a preset temperature, air flow at a preset temperature, or steam at a preset temperature.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that the preset temperature of the fluid contained in the tank body is between 80°C and 100°C, or between 150°C and 300°C; or the preset temperature of the fluid contained in the tank body is between 15°C and 30°C.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that the fluid contained in the tank body is a liquid or steam including a wire coating agent and/or a surface etchant.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that the tank body is provided with one or more devices selected from the group consisting of infrared radiation, microwave radiation, and alternating magnetic field for radiating the internal space of the tank body.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that a pipeline for inputting the fluid into the internal space of the trough body is provided on one side or both sides of the trough body.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that a temperature sensor for sensing the temperature of the fluid is provided in the tank body.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that a plurality of grooves extending from the proximal end to the distal end are provided at the bottom of the trough body, which are used to space adjacent 3D printing wires in the bottom wire mesh formed between the first winding wheel and the second winding wheel.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that the notch of the groove body is provided with a cover body that can be opened and closed.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that a first proximal guide wheel for introducing the 3D printing wire into or out of the first winding wheel is provided at the proximal end of the trough body; and a second proximal guide wheel for introducing the 3D printing wire into or out of the second winding wheel is provided at the distal end of the trough body.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that a first adjustment mechanism for adjusting the installation height of the first winding wheel is provided at the proximal end of the trough body; and a second adjustment mechanism for adjusting the installation height of the second winding wheel is provided at the distal end of the trough body.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that the first winding wheel and the second winding wheel are immersed in the fluid contained in the tank.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that it also includes a first drive motor for driving the first winding wheel to rotate, and a second drive motor for driving the second winding wheel to rotate.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that the deepest wire groove of the first winding wheel and the deepest wire groove of the second winding wheel are located on the same side of the groove body.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that the groove depths of the multiple grooves on the first winding wheel or the second winding wheel increase sequentially according to a preset ratio or preset value.
The crystallization control device for producing 3D printing wire according to claim 1 is characterized in that the groove depth of some of the multiple grooves on the first winding wheel or the second winding wheel increases sequentially according to a preset ratio or preset value.
The crystallization control device for producing 3D printing wire according to claim 15 or 16 is characterized in that the first winding wheel or the second winding wheel has n+1 wire grooves, wherein the diameters of every two adjacent grooves differ by a length e, the diameter of the deepest wire groove is r 1 , and the diameter of the shallowest wire groove is r 2 , then r 2 -r 1 =n·e, and the ratio of r 1 to r 2 ranges from 80% to 99%.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that the 3D printing wire is first wound around the deepest wire groove of the second winding wheel, and then wound around the deepest wire groove of the first winding wheel, and then wound back and forth between the second winding wheel and the first winding wheel according to the order of the wire grooves from deep to shallow, and led out through the shallowest wire groove of the first winding wheel.
The crystallization control device for producing 3D printing wire according to claim 18, characterized in that the rotation speed of the first winding wheel is greater than or equal to the rotation speed of the second winding wheel.
According to the crystallization control device for producing 3D printing wires according to claim 1, it is characterized in that the 3D printing wire is first wound around the shallowest wire groove of the second winding wheel, and then wound around the shallowest wire groove of the first winding wheel, and then reciprocatedly wound between the second winding wheel and the first winding wheel according to the order of the wire grooves from shallow to deep, and led out through the deepest wire groove of the first winding wheel.
The crystallization control device for producing 3D printing wire according to claim 20 is characterized in that the rotation speed of the first winding wheel is less than or equal to the rotation speed of the second winding wheel.
A crystallization control method for producing 3D printing wire, characterized in that the crystallization control method comprises the following steps:

The crystalline polymer is melted and extruded into wire;

The extruded 3D printing wire passes through the first temperature control tank to cool down and shape;

Winding the shaped 3D printing wire on the tension control mechanism located in the second temperature control tank so that the 3D printing wire is retained in the temperature control tank for a preset time under a preset tension to obtain a crystallized polymer material wire;

The 3D printing wire is pulled out from the tension control mechanism, and is rolled up and stored after cooling;

Wherein, the tension control mechanism includes a first winding wheel arranged at the proximal end of the temperature control tank and a second winding wheel arranged at the distal end of the temperature control tank, and a plurality of wire grooves are arranged on the first winding wheel and/or the second winding wheel, and the groove depths of all or part of the plurality of wire grooves increase sequentially, so as to control the tension of the 3D printing wire passing through the temperature control tank by configuring the winding direction of the 3D printing wire on the first winding wheel and the second winding wheel or/and by configuring the relative rotation speed of the first winding wheel and the second winding wheel.
The crystallization control method for producing 3D printing wire according to claim 22 is characterized in that the temperature control range of the first temperature control tank is between 50°C and 60°C; the temperature control range of the second temperature control tank is between 80°C and 100°C; the temperature control range of the cooling treatment is between 15°C and 30°C.
According to the crystallization control method for producing 3D printing wires according to claim 22, it is characterized in that the first winding wheel and the second winding wheel of the tension control mechanism are immersed in the fluid contained in the second temperature control tank.
The crystallization control method for producing 3D printing wire according to claim 22 is characterized in that the deepest wire groove of the first winding wheel and the deepest wire groove of the second winding wheel are located on the same side of the second temperature control tank.
The crystallization control method for producing 3D printing wire according to claim 22 is characterized in that the groove depths of the multiple grooves on the first winding wheel or the second winding wheel increase sequentially according to a preset ratio or preset value.
The crystallization control method for producing 3D printing wire according to claim 22 is characterized in that the groove depth of some of the multiple grooves on the first winding wheel or the second winding wheel increases sequentially according to a preset ratio or preset value.
The crystallization control method for producing 3D printing wire according to claim 26 or 27 is characterized in that the first winding wheel or the second winding wheel has n+1 wire grooves, wherein the diameters of every two adjacent grooves differ by a length e, the diameter of the deepest wire groove is r 1 , and the diameter of the shallowest wire groove is r 2 , then r 2 -r 1 =n·e, and the ratio of r 1 to r 2 ranges from 80% to 99%.
According to the crystallization control method for producing 3D printing wires according to claim 22, it is characterized in that the step of winding the shaped 3D printing wire on the tension control mechanism located in the second temperature control tank includes: allowing the 3D printing wire to first be wound around the shallowest wire groove of the second winding wheel, and then be wound around the shallowest wire groove of the first winding wheel, and then be wound back and forth between the second winding wheel and the first winding wheel according to the order of the wire grooves from shallow to deep, and be led out through the deepest wire groove of the first winding wheel.
The crystallization control method for producing 3D printing wire according to claim 29 is characterized in that it also includes the step of controlling the rotation speed of the first winding wheel to be greater than or equal to the rotation speed of the second winding wheel.
According to the crystallization control method for producing 3D printing wires according to claim 22, it is characterized in that the step of winding the shaped 3D printing wire on the tension control mechanism located in the second temperature control tank includes: allowing the 3D printing wire to first be wound around the shallowest wire groove of the second winding wheel, and then be wound around the shallowest wire groove of the first winding wheel, and then be wound back and forth between the second winding wheel and the first winding wheel according to the order of the wire grooves from shallow to deep, and be led out through the deepest wire groove of the first winding wheel.
The crystallization control method for producing 3D printing wire according to claim 31 is characterized in that it also includes a step of controlling the rotation speed of the first winding wheel to be less than or equal to the rotation speed of the second winding wheel.
A 3D printing wire prepared according to any one of the crystallization control methods described in claims 22-32.
A winding wheel, used to be installed in pairs on a crystallization control device for producing 3D printing wires, characterized in that the winding wheel includes a wheel body and a plurality of wire grooves formed on the wheel body for winding wires, and the groove depths of all or part of the plurality of wire grooves increase sequentially, so that the tension of the 3D printing wire passing through the crystallization control device can be controlled by configuring the winding direction of the 3D printing wire in the pair of winding wheels or/and by configuring the relative rotation speed of the pair of winding wheels.
The winding wheel according to claim 34 is characterized in that the groove depths of all or part of the multiple grooves increase sequentially according to a preset ratio or preset value.
The winding wheel according to claim 34 or 35 is characterized in that the winding wheel has n+1 wire grooves, wherein the diameters of every two adjacent grooves differ by a length e, the diameter of the deepest wire groove is r 1 , the diameter of the shallowest wire groove is r 2 , then r 2 -r 1 =n·e, and the ratio of r 1 to r 2 ranges from 80% to 99%.