阅读说明：本技术 四轴成型系统及其电磁感应加热装置和打印支架的方法 (Four-axis forming system, electromagnetic induction heating device thereof and method for printing support ) 是由 赵清华 吴斯倞 冯汉卿 汪贺龙 赵庆洪 刘青 于 2020-12-01 设计创作，主要内容包括：本发明涉及高分子聚合物支架制备技术领域,尤其涉及一种用于3D打印制造高分子聚合物支架的四轴成型系统及其电磁感应加热装置和打印支架的方法,本发明公开了一种用于高分子聚合物的支架四轴成型系统及其电磁感应加热装置和打印支架的方法,包括电磁感应加热线圈,所述高频加热线圈为将线圈线缆以涡旋线方式缠绕弯曲而成的管槽式单层线圈,用于加热四轴成型系统的电磁加热棒。本发明通过非封闭式的高频交流电流加热装置对电磁加热棒进行加热,采用非接触式和非封闭式线圈加热。这一加热方式加热快,稳定性好,可以对很细的旋转轴选定区域进行加热而不会接触到沉积在旋转轴上的高分子材料。(The invention relates to the technical field of high polymer support preparation, in particular to a four-axis forming system for manufacturing a high polymer support through 3D printing, an electromagnetic induction heating device of the four-axis forming system and a method for printing the support. The electromagnetic heating rod is heated by a non-closed high-frequency alternating current heating device, and non-contact and non-closed coils are adopted for heating. The heating mode has the advantages of fast heating and good stability, and can heat a selected area of a thin rotating shaft without contacting with a high molecular material deposited on the rotating shaft.)

1. The electromagnetic induction heating device is characterized by comprising a high-frequency heating coil, wherein the high-frequency heating coil is a pipe groove type single-layer coil formed by winding and bending a coil cable in a vortex line mode and is used for heating an electromagnetic heating rod of a four-axis forming system.

2. The electromagnetic induction heating apparatus for a four-axis molding system as claimed in claim 1, wherein the coil wire of the high-frequency heating coil is bent by a single wire or a plurality of wires.

3. The electromagnetic induction heating device suitable for the four-axis forming system as claimed in claim 1 or 2, wherein the arc surface of the tube slot type single-layer coil is formed by arranging a plurality of arc lines in parallel, and the center of each arc line is located on the diameter of the tube slot;

or the cambered surface of the pipe-groove type single-layer coil is formed by arranging a plurality of cables parallel to the axial direction.

4. The electromagnetic induction heating apparatus for a four-axis forming system as claimed in claim 3, wherein the pitch between the adjacent arcs is 1 to 20 mm.

5. The electromagnetic induction heating apparatus suitable for the four-axis forming system as claimed in any one of claims 1 to 4, wherein the high-frequency heating coil has a tube groove diameter of 5 to 500 mm;

and/or the wire diameter of the cable is 0.1-20 mm;

and/or the high-frequency heating coil is an electromagnetic induction coil;

and/or the electromagnetic heating rod is a metal rod or a rod with a metal coating.

6. The electromagnetic induction heating apparatus for the four-axis molding system according to any one of claims 1 to 5, further comprising a high-frequency current control unit connected to the high-frequency heating coil, the high-frequency current control unit being connected to a power source, the high-frequency control unit being configured to control a power output of the high-frequency current control unit by adjusting a voltage and a current of the power source.

7. The electromagnetic induction heating device of the high-temperature heating device suitable for the four-axis forming system is characterized by further comprising a thermocouple temperature control system, wherein the thermocouple temperature control system comprises a solid-state relay, a temperature controller and a thermocouple which are sequentially connected, the thermocouple is used for enabling the thermocouple to be in contact with the electromagnetic heating rod through a fixture, and the solid-state relay is connected with a power supply and the high-frequency heating control unit;

and/or the infrared temperature control system comprises a solid-state relay, a temperature controller and an infrared thermometer which are sequentially connected, the infrared thermometer is used for detecting the temperature of the electromagnetic heating rod and focusing on the electromagnetic heating rod, and the solid-state relay is connected with the power supply and the high-frequency heating control unit.

8. The apparatus of claim 7, further comprising an electrical slip ring connected between the temperature controller and the thermocouple.

9. A four-axis molding system, comprising:

(i) a base;

(ii) a three-axis X-Y-Z positioning system coupled to the base, the X-Y-Z positioning system for defining X, Y, Z directions, respectively;

(iii) a dispensing system mounted on said X-Y-Z positioning system, said dispensing system being moved by said X-Y-Z positioning system, said dispensing system including an extrusion head;

(iv) the fourth shaft system is connected with the base and comprises a rotating rod and an electromagnetic heating rod, the rotating rod is arranged below the extrusion head and connected with the base, the electromagnetic heating rod is connected with the rotating rod, and the rotating rod can rotate around the central axis of the rotating rod in a forward direction or a reverse direction; the middle axis of the rotating rod is parallel to the Y axis; and

(v) the electromagnetic induction heating apparatus for a four-axis forming system as claimed in any one of claims 1 to 8, wherein the electromagnetic heating rod of said fourth axis system is fitted inside the heating coil (vi) and the computer control system is used to precisely control the X-Y-Z positioning system according to a set program to control the movement of the extrusion head of the dispensing system in direction X, Y, Z and to control the rotation of the rotary rod of the fourth axis system around its central axis.

10. A method of printing a stent, performed by the four-axis molding system of claim 9, comprising the steps of:

1) an electromagnetic heating rod or a specific mould which can be heated by high frequency according to the processing of the bracket to be prepared;

2) a program for designing a deposition pattern of the polymer fibers using a computer;

3) fixing the electromagnetic heating rod or the specific die which can be heated by high frequency at the position of a rotating rod of a fourth shaft system of the four-shaft forming system, so that the electromagnetic heating rod or the specific die can rotate forwards or backwards along with the rotating rod of the fourth shaft system under the control of a computer control system;

4) controlling the X-Y-Z positioning system and the fourth shaft system through the computer control system according to the program designed in the step 2), so that the distribution system accurately extrudes additive materials, and the additive materials are deposited on an electromagnetic heating rod which can be rotated on the fourth shaft and heated by high frequency or a specific mould, thereby preparing a sample with a specific size and structure;

5) removing the sample prepared in the step 4) from an electromagnetic heating rod or a special mold which can be heated by high frequency.

Technical Field

The invention relates to the technical field of high-molecular polymer support preparation, in particular to a four-axis forming system for manufacturing a polymer support through 3D printing, an electromagnetic induction heating device of the four-axis forming system and a method for printing the support.

Background

In the preparation of polymer stents by 3D printing, it is sometimes necessary to heat and control the temperature of rotating metal objects, such as metal rods and tubes. For example, the in vivo degradable scaffold disclosed in chinese patent application No. 201410086319.0 is printed and prepared in a 3D four-axis printing and molding system, wherein the fourth axis is a rotary heating shaft, the melt-extruded polymer material is extruded through a nozzle and deposited on the rotary heating shaft, and the heating shaft needs to maintain a certain temperature so that the melt-extruded material can be firmly adhered to the rotary shaft.

The heating shaft needs to be maintained at a certain temperature so that the melt-extruded material can be firmly adhered to the rotating shaft. At present, a common heating mode is to penetrate a resistance wire into a rotating shaft to realize the heating and temperature control functions. However, when the rotating shaft is thin, the resistance wire is difficult to penetrate, and at the moment, the rotating shaft needs to be heated in a heat conduction mode, namely the rotating shaft is prepared into two sections with different diameters, and the resistance wire penetrates into the thick section to be heated and conducts heat to the thin section. The temperature conduction of the thin section is slower and the phenomenon of uneven temperature distribution exists, namely, the farther away from the thick section of the heating section, the lower the temperature. Therefore, the melt-extruded material has the problem of uneven heating during the deposition of the thin sections, resulting in different adhesion of the material or different degrees of crystallization, thereby affecting the quality of the formed polymer product.

Heating furnace radiation is feasible for simply heating the rotating shaft by other heat radiation methods, such as infrared radiation, but is not applicable when considering the deposition of the polymer material on the rotating shaft, because the heat radiation heats the polymer material deposited on the rotating shaft first and then is conducted to the rotating shaft. The rotating shaft plays a role in heat conduction and temperature reduction for the fused and deposited high polymer material.

Another method for heating the metal rotating shaft is to sleeve a high-frequency alternating current coil on the rotating shaft, and to generate heat by alternating magnetic poles in the metal rod through an alternating magnetic field generated by alternating current. However, this method of sleeving the coil around the metal rod may not allow the molten material to be directly deposited on the metal rod due to the presence of the coil.

Chinese patent application publication No. CN102045906A discloses a technical solution for locally heating and annealing a casting by semi-open high-frequency heating, but the coil in this solution cannot stably heat a metal bar, mainly because it is composed of an arc-shaped conductive part, the heating effect is easily uneven, the heating effect is slow, and the specification selection has a large limitation.

Disclosure of Invention

The invention aims to solve the technical problem that the heating shaft is heated unevenly in the prior art, so that the melting and polymerization effects of high polymer materials are influenced, and provides an electromagnetic induction heating device which can quickly and stably heat a metal rotating shaft and is suitable for a four-axis forming system and the four-axis forming system comprising the electromagnetic induction heating device, so that the temperature control is more accurate, and the temperature distribution is more uniform. The problem of traditional resistance wire heating rotatory metal object heating inequality, the intensification slowly with heated object temperature gradient great is solved and the problem that can't appoint regional heating and accuse temperature to D4 axle printing system's rotatory metal axle has been solved, makes 3D print the in-process polymer raw materials of preparation polymer support and is heated more evenly, is favorable to the temperature of accurate control heating shaft to the process of the polymerization preparation of control polymer support.

It is another object of the present invention to provide a method of printing a stent by enhancing the heating function of a 3D four-axis molding system. Is especially suitable for long polymer stents with small diameters.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

in one aspect, the present invention provides an electromagnetic induction heating device suitable for a four-axis forming system, including a heating coil, wherein the high-frequency heating coil is a pipe-groove type single-layer coil formed by winding and bending a whole cable in a spiral line manner, and is used for heating an electromagnetic heating rod of the four-axis forming system.

Furthermore, the arc surface of the pipe groove type single-layer coil is formed by parallel arrangement of a plurality of arcs, and the circle center of each arc is located on the diameter of the pipe groove and belongs to transverse arrangement;

or the cambered surface of the pipe-groove type single-layer coil is formed by arranging a plurality of cables parallel to the axial direction and belongs to longitudinal arrangement.

Further, the distance between adjacent arcs is 1-20 mm, preferably 2-10 mm.

Further, the diameter of the tube groove of the high-frequency heating coil is 5-500 mm, and preferably 20-30 mm.

Further, the filament diameter of the whole thread is 0.1-20 mm, preferably 1-5 mm.

Further, the high-frequency heating coil is an electromagnetic induction coil.

Further, the high-frequency heating coil device further comprises a high-frequency current control unit connected with the high-frequency heating coil, wherein the high-frequency current control unit is connected with a power supply and controls the output power of the high-frequency current control unit by adjusting the voltage and the current of the power supply.

The thermocouple temperature control system comprises a solid-state relay, a temperature controller and a thermocouple which are connected in sequence, the thermocouple is used for being fixed on the electromagnetic heating rod through a clamp, and the solid-state relay is connected with the power supply and the high-frequency current control unit.

The electromagnetic heating device further comprises an infrared temperature control system, wherein the infrared temperature control system comprises a solid-state relay, a temperature controller and an infrared thermometer which are sequentially connected, the infrared thermometer is used for focusing on the electromagnetic heating rod, and the solid-state relay is connected with the power supply and the high-frequency current control unit.

Further, the thermocouple temperature control system also comprises an electric slip ring connected between the temperature controller and the thermocouple.

In another aspect, there is provided a four-axis molding system, including:

(i) a base;

(ii) a three-axis X-Y-Z positioning system coupled to the base, the X-Y-Z positioning system for defining X, Y, Z directions, respectively;

(iii) a dispensing system mounted on said X-Y-Z positioning system, said dispensing system being moved by said X-Y-Z positioning system, said dispensing system including an extrusion head;

(iv) the fourth shaft system is connected with the base and comprises a rotating rod and an electromagnetic heating rod, the rotating rod is arranged below the extrusion head and connected with the base, the electromagnetic heating rod is connected with the rotating rod, and the rotating rod can rotate around the central axis of the rotating rod in a forward direction or a reverse direction; the middle axis of the rotating rod is parallel to the Y axis; and

(v) the electromagnetic induction heating device is suitable for the four-axis forming system, and an electromagnetic heating rod of the fourth axis system is assembled on a central axis of a heating coil;

(vi) a computer control system for precisely controlling the X-Y-Z positioning system according to a set program so as to control the movement of the extrusion head of the distribution system in the direction X, Y, Z, and controlling the rotation of the rotating rod of the fourth shaft system around the central axis thereof;

in still another aspect, there is provided a method for preparing an elongated stent by the four-axis molding system, comprising the steps of:

1) processing a magnetic-attraction electromagnetic heating rod or a specific mould according to a bracket to be prepared;

2) a program for designing a deposition pattern of the polymer fibers using a computer;

3) fixing the magnetic-attraction electromagnetic heating rod to the position of a rotating rod of a fourth shaft system of the four-shaft forming system, so that the magnetic-attraction electromagnetic heating rod can rotate forwards or backwards along with the rotating rod of the fourth shaft system under the control of a computer control system; adding the extrudable material into a distribution system of a four-shaft forming system;

4) controlling the X-Y-Z positioning system and the fourth shaft system through the computer control system according to the program designed in the step 2), so that the distribution system accurately extrudes fibers, and the fibers are deposited on a rotatable magnetic-attraction electromagnetic heating rod on the fourth shaft or a specific mold, so as to prepare a sample with a specific size and structure;

5) removing the sample prepared in the step 4) from the magnetic attraction electromagnetic heating rod or the special mold.

After adopting such design, the invention has at least the following advantages:

the invention heats the electromagnetic heating rod or the specific mould by manufacturing a non-closed high-frequency electromagnetic heating device. Non-contact and non-closed coil heating is used. The heating mode has the advantages of fast heating and good stability, and can heat the designated area of the metal rotating shaft which can be electromagnetically heated without directly heating the non-metal material deposited on the rotating shaft. The problems that a traditional resistance wire heats a rotary metal object to be heated unevenly, the temperature rise is slow, and the temperature gradient of the heated object is large are solved, and the problems that the designated area of the rotary metal shaft of the D4 shaft printing system cannot be heated and the temperature can not be controlled are solved.

Drawings

The foregoing is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and the detailed description.

Fig. 1 is a schematic structural view of an embodiment of a heating coil of an electromagnetic induction heating apparatus suitable for a four-axis molding system of the present invention;

FIG. 2 is a schematic structural view showing one example of the direction of current flow of a heating coil of an electromagnetic induction heating apparatus for a four-axis forming system according to the present invention;

FIG. 3 is a schematic configuration diagram of an embodiment of fitting of a thermocouple and a high-frequency heating coil of an electromagnetic induction heating apparatus suitable for a four-axis molding system according to the present invention;

fig. 4 is a schematic structural view of another embodiment of the fitting of the thermocouple and the high-frequency heating coil of the electromagnetic induction heating apparatus suitable for the four-axis molding system of the present invention;

FIG. 5 is a schematic configuration diagram of an embodiment of the present invention in which an infrared thermometer and a high-frequency heating coil are fitted to an electromagnetic induction heating apparatus for a four-axis molding system;

FIG. 6 is a schematic assembly view of one embodiment of an electromagnetic induction heating apparatus suitable for use in a four-axis forming system of the present invention;

FIG. 7 is a schematic assembly view of another embodiment of an electromagnetic induction heating apparatus suitable for use in a four-axis forming system of the present invention;

FIG. 8 is a schematic assembly view of yet another embodiment of an electromagnetic induction heating apparatus suitable for use in a four-axis forming system of the present invention;

FIG. 9 is a schematic assembly view of yet another embodiment of an electromagnetic induction heating apparatus suitable for use in a four-axis molding system of the present invention;

fig. 10 is a graph showing the heating effect of the high-frequency heating coil of different specifications according to the present invention with time (solid line: metal bar temperature; dotted line: coil itself temperature).

In the figure, the components are labeled as follows:

1-heating coil, 11 is arc line of heating coil, 12 is broken end of heating coil, 2-electromagnetic heating rod, 3-thermocouple, 31 clamp, 4-infrared thermometer, 5-high frequency current control unit, 6-direct current power supply, 7 '-solid state relay, 8' -temperature controller, 9-electric slip ring.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

An embodiment of an electromagnetic induction heating apparatus suitable for a four-axis forming system according to the present invention includes, as shown in fig. 1 to 4, a high-frequency heating coil 1 which is a single-layer coil of a pipe-channel type in which a coil cable is wound and bent in a spiral line manner, and an electromagnetic heating rod 2 for heating the four-axis forming system.

The heating coil is a pipe groove type coil, can be in a similar semicircular pipe shape, forms a semi-open type high-frequency heating coil, or is similar to a metal material which is provided with an opening in the axial direction and is suitable for all high-frequency heating. Compared with a heating mode of heat conduction, the heating mode is not influenced by the heat conductivity of the material. The heating efficiency is higher for magnetic attraction (large magnetic permeability) materials, and the temperature distribution of the heated section is more uniform.

The electromagnetic heating rod can be a metal rod or a rod with a metal coating, and the rod with the metal coating can be a ceramic rod, a polymer rod and the like, and the surface of the rod is coated with the metal coating.

Further, the arc surface of the pipe-slot type single-layer coil is formed by arranging a plurality of arcs in parallel, as shown in fig. 1, the circle centers of the arcs are located on the diameter of the pipe slot and belong to transverse arrangement. The uniform arrangement helps uniform heating.

As an alternative scheme, the cambered surface of the pipe-groove type single-layer coil is formed by arranging a plurality of cables parallel to the axial direction and belongs to longitudinal arrangement. The uniform arrangement helps uniform heating.

The invention can be used independently without a temperature control system, and comprises a heating coil, a high-frequency current control unit and a power supply when used independently; wherein the heating control unit is connected with the power supply, and controls power output by setting fixed voltage and current, thereby meeting the requirement of temperature control. The high-frequency heating coil is formed by winding and bending in a spiral line mode along the axial direction, and the current directions in the coils on two sides of a center line of the middle point of the shaft are the same; the cross section of the coil is arc-shaped, preferably major arc, the electromagnetic heating rod extends along the axial direction of the coil, and in any cross section of the electromagnetic heating rod and the coil, the electromagnetic heating rod is in a sector formed by the arc and the corresponding center of the circle of the coil, preferably located between the arc and the chord.

The heating coil is designed with non-closed openings, the coil distribution is uniform/non-uniform integrally, the temperature is controlled in a balanced manner, the heating length is extended, and the heating coil is heated in a non-contact manner. The tube-slot design of the coil refers to an opening design formed like a semicircular tube form, and the length and the diameter can be customized according to needs. In summary, the high-frequency heating apparatus has uniform temperature control performance and non-contact heating performance. Has the heating length extension performance.

Further, the coil cable of the high-frequency heating coil 1 is formed by bending a single or a plurality of cables.

Further, the electromagnetic heating rod is an electromagnetic heating rod or a rod with a metal coating.

Further, a high-frequency current control unit 5 connected to the high-frequency heating coil 1 may be further included, the high-frequency current control unit 5 being connected to a power source 6, the high-frequency control unit 5 controlling the power output of the high-frequency current control unit 5 by adjusting the voltage and current of the power source.

Further, a thermocouple temperature control system can be further included, the thermocouple temperature control system comprises a solid state relay 7, a temperature controller 8 and a thermocouple 3 which are connected in sequence, the thermocouple 3 is used for enabling the thermocouple 3 to be in contact with the electromagnetic heating rod 2 through a fixture 31, and the solid state relay 7 is connected with a power supply 6 and the high-frequency current control unit 5. The thermocouple temperature control system may further comprise an electrical slip ring 9 connected between the temperature controller 8 and the thermocouple 3. The thermocouple temperature control system can quickly heat and well control the temperature.

Further, the electromagnetic heating device further comprises an infrared temperature control system, wherein the infrared temperature control system comprises a solid-state relay 7 ', a temperature controller 8 ' and an infrared thermometer 4 which are sequentially connected, the infrared thermometer 4 is used for focusing on the electromagnetic heating rod 2, and the solid-state relay 7 ' is connected with the power supply 6 and the high-frequency current control unit 5. The infrared thermometer detects the temperature of the electromagnetic heating rod, and is favorable for controlling the temperature.

The surface temperature of the electromagnetic heating rod is collected through a thermocouple temperature control system and an infrared temperature control system, and the temperature is controlled. The temperature control is realized by a temperature controller, a thermocouple/infrared thermometer and a solid-state relay, the temperature controller is connected with alternating current, but outputs direct current to control the solid-state relay, and the direct current control alternating current solid-state relay can be connected with the on-off of a live wire of a direct current power supply to realize temperature control; the direct current solid-state relay is controlled through direct current, the on-off of the positive pole or the negative pole of the direct current power supply can be controlled, and temperature control is achieved.

Preferably, the heating coil may be an open semi-cylindrical electromagnetic induction coil, the diameter range of the coil is not limited, and the diameter of the pipe groove may be 5-500 mm, preferably 20-30 mm, preferably 25 mm. The diameter of the coil wire can be 0.1-20 mm, preferably 1-5 mm, and more preferably 2 mm.

Preferably, the high-frequency heating coil pitch may be 2 to 10 mm.

Preferably, the high-frequency heating coil is wound in a spiral manner (which may be a circular surface or other vortex-like form), and is bent and deformed as a whole.

Preferably, the temperature control range is ± 5 ℃.

Preferably, the temperature adjustment range is normal temperature to 300 ℃.

Preferably, the temperature rise rate is not less than 3 ℃/S.

Further, the coil wire of the high-frequency heating coil 1 is bent in the axial direction to form a plurality of parallel arcs 11, preferably evenly distributed arcs, to ensure even heating.

Further, the high-frequency heating coil 1 is an electromagnetic induction coil.

In another aspect, there is provided a four-axis molding system, including:

(i) a base;

(ii) a three-axis X-Y-Z positioning system coupled to the base, the X-Y-Z positioning system for defining X, Y, Z directions, respectively;

(iii) a dispensing system mounted on an X-Y-Z positioning system, said dispensing system being moved by said X-Y-Z positioning system, said dispensing system comprising an extrusion head;

(iv) the fourth shaft system is connected with the base and comprises a rotating rod which is arranged below the extrusion head and connected with the base and an electromagnetic heating rod which is connected with the rotating rod, wherein the rotating rod is a rod rotating rod which can rotate around the middle shaft of the rotating rod in a forward direction or a reverse direction, and the middle shaft of the rod rotating rod is parallel to the Y shaft; and

(v) the electromagnetic induction heating device is suitable for the four-axis forming system, and an electromagnetic heating rod of the fourth axis system is assembled on a central axis of a heating coil;

(vi) a computer control system for precisely controlling the X-Y-Z positioning system according to a set program so as to control the movement of the extrusion head of the distribution system in the direction X, Y, Z, and controlling the rotation of the rotating rod of the fourth shaft system around the central axis thereof;

in still another aspect, there is provided a method for preparing an elongated stent by the four-axis molding system, comprising the steps of:

1) processing a magnetic-attraction electromagnetic heating rod or a specific mould according to a bracket to be prepared;

2) a program for designing a deposition pattern of the polymer fibers using a computer;

3) fixing the magnetic-attraction electromagnetic heating rod to the position of a rotating rod of a fourth shaft system of the four-shaft forming system, so that the magnetic-attraction electromagnetic heating rod can rotate forwards or backwards along with the rotating rod of the fourth shaft system under the control of a computer control system; adding the extrudable material into a distribution system of a four-shaft forming system;

4) controlling the X-Y-Z positioning system and the fourth shaft system through the computer control system according to the program designed in the step 2), so that the distribution system accurately extrudes fibers, and the fibers are deposited on a rotatable magnetic-attraction electromagnetic heating rod on the fourth shaft or a specific mold, so as to prepare a sample with a specific size and structure;

5) removing the sample prepared in the step 4) from the magnetic attraction electromagnetic heating rod or the special mold.

Preferably, the shape of the die in step 1) is a smooth-surfaced cylinder (polymer filaments are directly deposited on the cylindrical surface), a cylinder with grooves on the surface (polymer filaments are deposited in the grooves, and the cross section of the grooves can be conical, circular, planar or other shapes); preferably, the mold is prepared by 3D printing technology or conventional technology such as cnc machining.

Preferably, the die is fixed in step 3) by using a clamp, or by sleeving the hollow die on a rotating rod of a fourth shaft system.

Preferably, the fixing in step 3) is to replace the rotating rod of the fourth shaft system with the die to receive the polymer, fix the polymer on the fourth shaft system, and enable the polymer to rotate forwards or backwards under the control of the computer control system.

The electromagnetic heating rod is heated through high-frequency induction heating, and only the coil area is heated, so that the magnetic electromagnetic heating rod is fast in temperature rise and fast in temperature reduction, the influence on the area outside the coil is small, the temperature attenuation is fast, the heating range of the electromagnetic heating rod is 50-300 ℃, and the extrusion molding of most thermoplastic polymers is met; the temperature uniformity reaches +/-3 ℃ within 50-150 ℃, and the temperature uniformity reaches +/-5 ℃ within 150-300 ℃; the temperature of the coil is not more than 60 ℃, and the coil only heats the electromagnetic heating rod and has no influence on the polymer support.

The density and the diameter of the coil directly influence the uniformity of temperature and the heating speed, and the coils with different specifications and sizes can be designed according to different areas so as to meet different requirements.

The length of the coil can be very long, and the coil can uniformly heat a slender electromagnetic heating rod, so that a thinner and longer support can be manufactured, and the function of the four-axis rapid forming system is expanded.

In order to verify the heating effect of the high-frequency heating coils with different specification parameters, the present invention performed heating analysis on the high-frequency heating coils with different specification parameters (table 1) in which the metal rod was located substantially at the geometric center of the coil during the test (solid line: metal rod temperature; dotted line: coil itself temperature), and the results are shown in fig. 10.

TABLE 1 Experimental parameters of high-frequency heating coils of different specifications

Numbering	Diameter (mm) D	Diameter of wire (mm) d	Number of turns n	Spacing (mm)	Total length (mm)	Diameter of heating rod (mm)	Voltage (V)	Current (A)
									Ⅰ	20	2.6	12	20	132	3	30	7.1
Ⅱ	20	1.8	12	20	132	3	30	7
									Ⅲ	40	1.8	12	20	132	3	30	4.4
Ⅳ	40	1.8	24	10	132	3	30	2.5
									Ⅴ	20	1	12	20	132	3	30	7.1
Ⅵ	20	1	24	10	132	3	30	4.3

As can be seen from table 1 and fig. 10:

i and II are compared and explained: the metal rod with the thick wire diameter is heated quickly, and the self-heating is low;

II and III, comparison and explanation: a small diameter heating metal bar speed block; self-heating is large;

III and IV are compared and explained: the turn density is low, and the metal rod heating speed is high; self-heating is large;

v and VI show by comparison: the turn density is low, and the metal rod heating speed is high; self-heating is large;

fifthly, according to the theory. II should be faster than V in temperature rise speed because II wire diameter is thick, but V itself heating temperature is too high, affecting the metal bar (lower picture video)

Sixthly, the I, the II and the V are different in filament diameter but same in output power, and the filament diameter does not influence the output power;

seventhly, the diameters, the wire diameters and the number of turns of the wire diameter III and the wire diameter VI are different, but the output power is the same, and the diameters and the number of turns are in inverse proportion because the wire diameter does not influence the output power.

Comparative example 1 heating coil comparison

The corresponding coil was prepared for the open type high frequency coil disclosed in publication No. CN102045906A entitled "heating method of high frequency heating coil and workpiece", and then its heating effect on the metal bar was tested by experiment, and the test was sequentially performed according to the order of the coil schemes disclosed in the drawings in the publication, and the results are shown in table 2:

table 2 prior art coil solution heating effect test

Numbering	Diameter of	Height	Voltage of	Electric current	Heating effect
						Ⅰ	60	60	19.3	7.6	The temperature of the metal bar is basically unchanged, and the heating effect is basically not generated
Ⅱ	60	60	15.1	7.3	The middle part of the metal bar has no heating effect, and the edge temperature is slowly increased
						Ⅲ	60	60	15.4	7.3	The temperature of the metal bar is basically unchanged, and no obvious heating effect is generated
Ⅳ	60	60	13.2	7.3	The temperature of the metal bar is basically unchanged, and no obvious heating effect is generated
						Ⅴ	60	60	19.3	7.4	The middle part of the metal bar has small temperature fluctuation and no obvious heating effect
Ⅵ	60	60	19.3	7.2	Has a certain heating effect, but the temperature is lower and unstable

As shown in table 2, the semi-open coil solution provided according to the prior art cannot achieve the desired fast and stable heating effect, and cannot be used for printing of the elongated stent.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the present invention in any way, and it will be apparent to those skilled in the art that the above description of the present invention can be applied to various modifications, equivalent variations or modifications without departing from the spirit and scope of the present invention.