CN115415670A

CN115415670A - Laser continuous liquid interface additive manufacturing method and device for rod piece

Info

Publication number: CN115415670A
Application number: CN202211044873.3A
Authority: CN
Inventors: 丁雪萍
Original assignee: Chongqing University of Technology
Current assignee: Chongqing University of Technology
Priority date: 2022-08-30
Filing date: 2022-08-30
Publication date: 2022-12-02

Abstract

The invention discloses a laser continuous liquid interface additive manufacturing method and a device of a rod piece, wherein the method comprises the following steps: horizontally arranging a substrate for bearing a workpiece, and enabling a wire to be vertical to the substrate from the upper part; adjusting the emergence angle of the laser excitation device to enable the emitted laser to obliquely irradiate on the wire material; starting a laser excitation device, wherein the laser power excited by the laser excitation device is P; the wire is fed downwards at a speed V1, the substrate moves at a speed V2, and the laser irradiation position is kept unchanged, so that the wire is melted on the substrate or a formed rod and the tail end of the wire to form a continuous liquid interface; the wire material is kept to be fed downwards at the speed V1, the substrate is kept to move at the speed V2, and the laser power irradiation position is kept unchanged until the rod reaches the target length. Rod manufacture is performed by laser melting a wire such that the wire forms a continuous liquid interface between the substrate or formed rod and the end of the wire.

Description

Laser continuous liquid interface additive manufacturing method and device for rod piece

Technical Field

The invention relates to the technical field of laser additive manufacturing, in particular to a method and a device for manufacturing a rod piece by using a laser additive technology.

Background

The additive manufacturing technology overcomes the large waste of raw materials in the traditional 'material removing' manufacturing, has the advantages of rapid forming, grain refinement, uniform structure and the like, and becomes the first choice of the rapid forming technology of complex structural parts.

Generally, most of rod additive manufacturing at present is additive manufacturing of rod-shaped structures based on arc fuse additive point-to-point (point by point) manufacturing, and particularly in the field of buildings, CMT arc additive manufacturing is mainly adopted, a heat source is an arc, a material form is a wire material, a welding wire transition is a short circuit transition, rod unit manufacturing is realized point-to-point, and the method is expanded to space free forming of structures such as complex frames/dot matrixes/trusses based on rod units.

However, in actual production, on one hand, the rod manufactured by adding materials to the arc fuse point by point has large internal stress and poor surface quality; on the other hand, the point-by-point manufacturing of the arc fuse is not suitable for manufacturing the rod in the space environment.

Disclosure of Invention

In view of this, the present invention provides a method and an apparatus for manufacturing a rod member by laser continuous liquid interface additive manufacturing, in which a rod member is manufactured by melting a wire material by laser to form a continuous liquid interface instead of the conventional point-by-point additive manufacturing method, so that the surface accuracy of the rod member is improved, and the method and the apparatus are more suitable for manufacturing the rod member in a space environment.

In order to solve the technical problems, the technical scheme of the invention is a laser continuous liquid interface additive manufacturing method adopting a rod piece, which comprises the following steps:

horizontally arranging a substrate for bearing the rod piece, and enabling the wire to be vertical to the substrate from the upper part; adjusting the emergence angle of the laser excitation device to enable the emitted laser to obliquely irradiate on the wire material;

starting a laser excitation device, wherein the laser power excited by the laser excitation device is P; the wire is fed downwards at a speed V1, the substrate moves at a speed V2, and the laser irradiation position is kept unchanged, so that the wire is melted between the substrate or a formed rod and the tail end of the wire to form a continuous liquid interface;

the wire material is kept to be fed downwards at the speed V1, the substrate is kept to move at the speed V2, and the laser power irradiation position is kept unchanged until the rod reaches the target length.

The principle of the invention is that the rod manufacturing is carried out by melting the wire by laser so that the wire forms a continuous liquid interface between the substrate and the end of the wire or between the formed rod and the end of the wire. The liquid interface is not broken and the wire is not tied by reasonably controlling the wire feeding speed and the substrate moving speed.

As an improvement, the included angle between the laser and the wire material is 20-60 degrees. Through setting up reasonable inclination to realize reasonable layout, thereby reduce the whole volume of device to a certain extent.

As an improvement, the wire is TC4 titanium alloy, and the diameter of the wire is 0.4-1.2 mm.

As a modification, the power P of the laser is 140-160W.

As an improvement, when the speed V1 is 4-6mm/s, the speed V2 is 0.3-0.6 mm/s; when the speed V1 is 6.5-8.5mm/s, the speed V2 is 0.7-1.2 mm/s; when the speed V1 is 9 to 11mm/s, the speed V2 is 1 to 2.25mm/s.

As a further improvement, the laser excited by the laser excitation device is a circular laser beam, and the wire is positioned in the center of the circular laser beam. So that the wire material is melted uniformly in the circumferential direction, and a continuous liquid interface is formed conveniently. Preferably, the three laser beams or the five laser beams are uniformly distributed.

The invention also provides a device for manufacturing the rod piece by the laser continuous liquid interface additive, which comprises a substrate horizontally arranged for bearing the rod piece, a wire feeding device positioned right above the substrate and used for feeding wires in a direction vertical to the substrate, and a laser excitation device used for exciting laser to melt the wires.

As another further improvement, the base plate is driven by a vertical driving mechanism to move up and down; the vertical driving mechanism comprises a lead screw, a trolley in threaded fit with the lead screw is arranged on the lead screw, and the substrate is fixed on the trolley; the trolley is characterized by further comprising a guide rod for guiding the trolley, and the lead screw is driven to rotate by the motor. The base plate is driven to move up and down through the rotation of the lead screw, the precision is high, the control is convenient, and the manufacturing of a straight rod piece is facilitated.

As an improvement, the wire feeding device comprises a winch for receiving wires, and a pair of wire feeding rollers are arranged below the winch side by side; and a wire guide pipe is vertically arranged below the wire feeding roller.

As an improvement, a straightener is arranged between the winch and the wire feeding roller. The wire is straightened before wire feeding, so that the wire feeding amount and the wire feeding direction are more accurate.

As an improvement, the wire feeding roller wheel is driven by a direct current motor, and the direct current motor is controlled by a PID controller. The wire feeding speed is automatically controlled by PID, and a continuous liquid interface is formed after the wires are melted.

As an improvement, the wire melting monitoring system further comprises a monitoring system for monitoring the melting state of the wire, wherein the monitoring system comprises a high-speed camera, a thermal infrared imager and a displacement sensor. The monitoring system is used for monitoring the melting state of the wire and the condition of the liquid interface, and feeding back the condition so as to adjust the wire feeding speed and the substrate moving speed.

As an improvement, the base plate and the wire feeding device are connected with an upper computer, and the upper computer controls the movement speed and the wire feeding speed. And the upper computer adjusts the substrate movement speed and the wire feeding speed according to the information fed back by the monitoring system, so that the formation of a continuous liquid interface is ensured.

The invention has the advantages that: compared with the existing method for manufacturing the rod piece by adding materials point by point, the method for manufacturing the rod piece by adding materials through the continuous liquid interface formed by the laser fuse wire has the advantages that the finished product has high surface precision and high strength, and is more suitable for manufacturing the rod piece in the space environment, particularly for manufacturing the straight rod piece in the space environment by adding materials.

Due to the influence of environmental factors such as gravity, temperature and the like in the space, the printing mode is different from the ground, and the forming difficulty is higher, on one hand, the device is required to be simple and light in structure as much as possible due to the fact that the device needs to be carried to the space environment, therefore, the laser (the semiconductor laser with the wavelength of 808nm is preferably selected) is adopted for material increase manufacturing of the rod piece, and the laser is small in size and light in weight, so that the material increase manufacturing device is small in size and light in weight; on the other hand, the difficulty of additive manufacturing of rod members by using laser in a space environment is the matching of the wire feeding speed and the substrate moving speed, if the wire feeding speed is too slow or the substrate moving speed is too fast, a liquid bridge between the tail end of the wire material and the formed rod member is very easy to break, and if the wire feeding speed is too fast or the substrate moving speed is too slow, a wire binding phenomenon is easy to occur (for example, for additive manufacturing of non-straight rod members such as straight rod members or spiral rod members, the wire binding phenomenon is caused by the fact that the vertical downward wire feeding speed is too fast), therefore, the wire feeding speed is generally considered to be not less than 13mm/s, and the substrate moving speed is not less than 3mm/s; on the other hand, the type and diameter of the wire will also affect the wire feed speed and the substrate movement speed. The TC4 titanium alloy is very suitable for manufacturing aerospace devices, and through a great deal of creative work, the TC4 titanium alloy is unexpectedly found to be: aiming at TC4 titanium alloy wires of 0.4-1.2mm (aiming at a certain straight rod piece or a certain truss in space), the total laser power is 140-160W (because heat is mainly radiated in a heat radiation mode in microgravity environments such as space and the like, the laser power cannot be too large, otherwise, the service life of the device is greatly influenced due to the fact that larger heat cannot be timely radiated, if the cost and the volume and the weight of the device are greatly increased by arranging a radiating fin, the total laser power cannot be too small, and if the wires are not sufficiently melted, a liquid bridge is extremely easy to break or tie, therefore, the optimal total laser power is found through creative labor aiming at the titanium alloy wires of the specific diameter, and when the wire feeding speed is 4-6mm/s, if the substrate moving speed is greater than 0.6mm/s, the melted wires form liquid drops under the action of surface tension in the microgravity environment, so that the liquid bridge formed between the tail end of the wires and a molten pool is extremely easy to break, and further the manufacturing cannot be continued, and if the substrate moving speed is less than 0.3mm/s, the wire tying appears; when the wire feeding speed is 6.5-8.5mm/s, if the substrate moving speed is more than 1.2mm/s, the melted wire forms liquid drops under the action of surface tension in a microgravity environment, so that a liquid bridge formed between the tail end of the wire and a molten pool is extremely easy to break, and further the rod piece manufacturing cannot be continued, and if the substrate moving speed is less than 0.7mm/s, wire binding occurs; when the wire feeding speed is 9-11mm/s, if the moving speed of the substrate is more than 2.25mm/s, the melted wire forms liquid drops under the action of surface tension in a microgravity environment, so that a liquid bridge formed between the tail end of the wire and a molten pool is extremely easy to break, and further the rod piece manufacturing cannot be continued, and if the moving speed of the substrate is less than 1mm/s, wire binding occurs;

when the wire feeding speed is higher than 11mm/s, the wire cannot be melted in time, and the tail end of the wire is pushed against the substrate to deform, so that stable forming cannot be realized; and when the wire feeding speed is less than 4mm/s, the tail end of the wire cannot be stably connected with the molten pool, so that a liquid bridge between the tail end of the wire and the molten pool is extremely easy to break, the tail end of the wire is melted to form liquid drops, and under the microgravity environment, the small liquid drops at the tail end of the wire are gradually changed into large liquid drops or liquid balls under the action of surface tension, so that the rod piece forming process is interrupted.

Drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Fig. 2A and 2B illustrate a rod manufactured by a conventional additive manufacturing method.

Fig. 2C shows a rod manufactured according to the present invention.

The labels in the figure are: the device comprises a substrate 1, a laser excitation device 2, a wire feeding roller 3, a winch 4, a straightener 5, a wire guiding pipe 6, a high-speed camera 7, an infrared thermal imager 8, a displacement sensor 9, a lead screw 10, a trolley 11, a formed rod 100, a continuous liquid interface 101, a laser 102 and a wire 103.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments in order to make those skilled in the art better understand the technical solutions of the present invention.

Herein, suffixes such as "module", "part", or "unit" used to denote elements are used only for facilitating the description of the present invention, and have no specific meaning in itself. Thus, "module", "component" or "unit" may be used mixedly.

Herein, the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

The terms "first," "second," and the like, herein are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As used herein, unless otherwise expressly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such that the terms "connected," or "connected," as used herein, may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in a specific case to those of ordinary skill in the art.

In the present text, the term "continuous liquid interface" means that the transition form between the end of the metal wire and the molten pool is always in a liquid bridge transition state under the action of laser, that is, the end of the wire is connected with the molten pool by means of a metal liquid bridge.

The term "liquid bridge" as used herein refers to the laser rapidly melting a metal wire into a metal melt (liquid) and the metal melt bond between the unmelted wire, i.e., the end of the wire, and a formed rod on the substrate as the substrate moves, etc. The additive manufacturing forming process is a process accompanied by physical phase change such as liquid bridge formation and solidification into a rod (solid).

As used herein, the term "wire binding" refers to the phenomenon of incomplete melt build-up due to excessive solid metal wire feed.

As shown in FIG. 1, the present invention provides a laser continuous liquid interface additive manufacturing device for a rod, which comprises a substrate 1 horizontally arranged for carrying the rod, a wire feeding device located right above the substrate 1 for feeding a wire 103 in a direction perpendicular to the substrate 1, and a laser excitation device 2 for exciting laser to melt the wire 103.

In some embodiments, the base plate 1 is driven by a vertical driving mechanism to move up and down; the vertical driving mechanism comprises a lead screw 10, a trolley 11 in threaded fit with the lead screw 10 is arranged on the lead screw 10, and the substrate 1 is fixed on the trolley 11; and the device also comprises a guide rod (not shown in the figure) for guiding the trolley 11, and the screw rod 10 is driven by a motor to rotate. Of course, other modes can be used to drive the substrate 1 to move, such as a slide rail, an oil cylinder, etc., as long as the substrate 1 can be driven to move up and down and the precise control can be realized.

In other embodiments, the substrate may also be moved in the XCY three directions in order to produce a non-straight rod, such as a spiral.

In other embodiments, the laser and the wire can be moved by the mechanical arm, and after the mechanical arm carries the laser and the wire to reach the target position, the rod manufacturing of the corresponding position can be realized by moving the substrate.

The wire feeding device specifically comprises a winch 4 for receiving wires 103, and a pair of wire feeding rollers 3 are arranged below the winch 4 in parallel; and a wire guide pipe 6 is vertically arranged below the wire feeding roller 3. In addition, in order to ensure the collimation of the wire, a straightener 5 is arranged between the winch 4 and the wire feeding roller 3. The wire feeding roller 3 clamps the wire, and the wire 103 is pulled out from the winch 4 by rotation to realize wire feeding. The wire feeding roller 3 is driven by a direct current motor which is automatically controlled by PID control, and the wire feeding speed is adjusted according to the melting condition.

The laser excitation device 2 is a ring-type laser excitation device, can excite a plurality of laser beams 102 to be uniformly distributed according to the circumference, and simultaneously melts the wires 103 from a plurality of directions so as to ensure the melting uniformity of the wires 103.

In order to monitor the melting condition of the wire, the invention is also provided with a monitoring system which comprises a high-speed camera 7, a thermal infrared imager 8 and a displacement sensor 9 and is used for monitoring parameters such as continuity, temperature and the like of a liquid interface. In addition, in order to realize automatic control, the monitoring system, the wire feeding device and the substrate 1 are all connected with an upper computer, and the wire feeding speed and the movement speed of the substrate 1 are adjusted through data monitored by the monitoring system, so that the formation of the continuous liquid interface 101 is ensured.

Based on the device, the invention also provides a laser continuous liquid interface additive manufacturing method of the rod piece, which comprises the following steps:

the method comprises the following steps that firstly, a substrate for bearing a workpiece is horizontally arranged, and a wire is perpendicular to the substrate from the upper part; adjusting the emergence angle of the laser excitation device to enable the emitted laser to obliquely irradiate on the wire material;

secondly, starting a laser excitation device, wherein the laser power excited by the laser excitation device is P; the wire is fed downward at a speed V1, the substrate is moved at a speed V2, and the laser irradiation position is maintained constant, so that the wire melts to form a continuous liquid interface between the substrate or the formed rod and the end of the wire. The molten liquid material of the wire has a surface tension that bridges between the end of the wire and the substrate or formed rod.

And thirdly, the wire is fed downwards at the speed V1, the substrate is moved at the speed V2, and the laser power irradiation position is continuously unchanged until the rod reaches the target length. If the wire feeding speed and the substrate moving speed can be controlled well, the liquid material can be ensured not to be broken, and the wire above the rod is melted into liquid after the liquid material below the rod is cooled into solid, so that the complete rod is formed.

As a specific embodiment, the wire material adopted by the invention is TC4 titanium alloy, and the diameter of the wire material is 0.4-1.2 mm; the power P of the laser is 140-160W; when the speed V1 is 4-6mm/s, the speed V2 is 0.3-0.6 mm/s; when the speed V1 is 6.5-8.5mm/s, the speed V2 is 0.7-1.2 mm/s; when the speed V1 is 9 to 11mm/s, the speed V2 is 1 to 2.25mm/s. On the premise of certain parameters such as wire material, laser power and the like, in order to ensure the formation of a continuous liquid interface, the wire feeding speed and the substrate movement speed need to be well controlled. If the substrate is moved too fast or the wire feed speed is too slow, the liquid interface may break resulting in rod manufacturing failures. If the substrate moves too slowly or the wire feeding speed is too fast, the wires are not melted timely and are pushed against the substrate or the formed layer of the workpiece, and wire binding is caused.

In some embodiments, in order to ensure the continuity of the liquid bridge, in the third step, the change of the liquid bridge is also detected by the monitoring system. Specifically, a high speed camera captures an image with the laser focus at the focal position of the high speed camera.

The image acquisition device periodically or in real time acquires images and then sends the images to the upper computer, the upper computer performs image processing on the images acquired by the image acquisition device to obtain the current state of the liquid bridge, and the upper computer corrects the wire feeding speed or the movement speed of the substrate according to the current state of the liquid bridge. For example, if the upper computer performs image processing to obtain the current thickness or width of the liquid bridge (specifically, the thickness or width value of the liquid bridge can be calculated according to the pixel value; further, the image can be preprocessed to increase the definition of the image so as to improve the accuracy of the corresponding data of the liquid bridge), and the current thickness or width of the liquid bridge obtained in the last period or the average value of the thickness or width in the last time period (which can be preset) is compared with the image, if the average value becomes smaller, the risk of the liquid bridge breaking is indicated, the current wire feeding speed and/or substrate moving speed is corrected (specifically, the current wire feeding speed and substrate moving speed are obtained through a displacement sensor, and whether the wire feeding speed and the substrate moving speed are within the preset threshold range is judged, and if the wire feeding speed and/or the substrate moving speed are not within the preset threshold range, the wire feeding speed and/or the substrate moving speed are adjusted to be within the preset threshold range) so as to ensure the continuity of the liquid bridge; accordingly, if the wire feeding speed becomes larger, which indicates that there is a risk of wire binding, the current wire feeding speed and/or the substrate moving speed is corrected (for example, the wire feeding speed is decreased or the substrate moving speed is increased so as to be within the preset range).

Of course, in other embodiments, a prediction model for determining whether the liquid bridge has a fracture risk may be obtained by training a large number of training samples (including image data of a normal liquid bridge, image data of a liquid bridge that is about to fracture, and image data of a liquid bridge that fractures), so that the captured image data may be input into the prediction model for prediction, thereby obtaining a prediction result, so that a corresponding wire feeding speed or a corresponding substrate moving speed may be adjusted according to the prediction result.

Furthermore, in order to ensure the connection between the formed rod and the substrate in the microgravity environment, the end of the wire is welded with the substrate before the first step is performed, so as to avoid the difficulty in connecting the melt at the end of the wire with the substrate due to the surface tension in the early stage of manufacturing.

In order to prove the surface progress and performance advantages of the rod manufactured by the method under the microgravity environment, a comparison test is carried out, namely a TC4 titanium alloy wire with the length of 0.8-1mm and the diameter of 0.8mm is adopted, and the straight rod is manufactured by respectively adopting resistance heating thermal deposition forming, arc stagnation deposition forming and the laser fuse additive manufacturing method, wherein in the laser fuse additive manufacturing process, the total laser power P is 150W, the wire feeding speed V1 is 7mm/s, and the substrate moving speed (namely the descending speed) V2 is 1.2mm/s. The results of the straight rod piece obtained in the three ways are shown in fig. 2A-2C, respectively.

Wherein, fig. 2A and fig. 2B are a rod manufactured by a wire material resistance heating point-by-point additive manufacturing method and a rod manufactured by an arc standing point deposition additive manufacturing method, respectively. Fig. 2C is a rod manufactured by the apparatus and method of the present invention. It can be obviously seen that the surface precision of the rod piece manufactured by the invention is greatly improved compared with the existing rod piece manufactured by point-by-point additive manufacturing. In addition, through tests, the tensile strength of the rod manufactured by the TC4 titanium alloy additive manufacturing method is more than 900MPa, which is equivalent to the strength of a forged piece.

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

Claims

1. A laser continuous liquid interface additive manufacturing method of a rod, characterized in that the additive manufacturing method is based on an additive manufacturing apparatus of a rod, the additive manufacturing apparatus comprising: the additive manufacturing method comprises the following steps of horizontally arranging a substrate for bearing a workpiece, a wire feeding device which is positioned right above the substrate and used for feeding wires in a direction vertical to the substrate, and a laser excitation device used for exciting laser to melt the wires, wherein the additive manufacturing method comprises the following steps:

horizontally arranging a substrate for bearing a workpiece, and vertically arranging a wire material to the substrate from the upper part; adjusting the emergence angle of the laser excitation device to enable the emitted laser to irradiate the wire obliquely;

the wire material is fed downwards at a speed V1, the substrate is moved at a speed V2, and the laser power irradiation position is continuously unchanged until the rod reaches the target length;

wherein the power P of the laser is 140-160W;

when the speed V1 is 4-6mm/s, the speed V2 is 0.3-0.6 mm/s;

when the speed V1 is 6.5-8.5mm/s, the speed V2 is 0.7-1.2 mm/s;

when the speed V1 is 9 to 11mm/s, the speed V2 is 1 to 2.25mm/s.

2. The method of claim 1, wherein the rod comprises: the included angle between the laser and the wire is 20-60 degrees, and/or the wire is TC4 titanium alloy with the diameter of 0.4-1.2 mm.

3. The method of claim 1, wherein the laser continuous liquid interface additive manufacturing method comprises: the laser excited by the laser excitation device is a circular laser beam, and the wire is positioned in the center of the circular laser beam.

4. The method of claim 1, wherein the laser continuous liquid interface additive manufacturing method comprises: the additive manufacturing apparatus further comprises: the monitoring system is used for monitoring the melting state of the wire material and comprises a high-speed camera, a thermal infrared imager and a displacement sensor; correspondingly, the additive manufacturing method further comprises the steps of: and the upper computer respectively adjusts the movement speed and the wire feeding speed of the substrate and the wire feeding device according to the monitoring data acquired by the monitoring system.

5. A device for manufacturing a rod piece by laser continuous liquid interface additive is characterized in that: comprises a substrate horizontally arranged for bearing a rod piece, a wire feeding device positioned right above the substrate and used for feeding wires in a direction vertical to the substrate, a laser excitation device used for exciting laser to melt the wires, and a vertical driving mechanism used for driving the substrate to move up and down, wherein,

the vertical driving mechanism comprises a lead screw, a trolley in threaded fit with the lead screw is arranged on the lead screw, and the substrate is fixed on the trolley; the trolley is characterized by further comprising a guide rod for guiding the trolley, and the lead screw is driven to rotate by the motor.

6. The laser continuous liquid interface additive manufacturing device of the rod piece according to claim 5, wherein: the wire feeding device comprises a winch for accommodating wires, and a pair of wire feeding rollers are arranged below the winch side by side; and a wire guide pipe is vertically arranged below the wire feeding roller.

7. The apparatus of claim 5, wherein: and a straightener is arranged between the winch and the wire feeding roller.

8. The laser continuous liquid interface additive manufacturing device of a rod piece according to claim 6, wherein: the wire feeding roller is driven by a direct current motor, and the direct current motor is controlled by a PID controller.

9. The laser continuous liquid interface additive manufacturing device of the rod piece according to claim 5, wherein: the wire melting monitoring system is used for monitoring the melting state of the wire, and comprises a high-speed camera, a thermal infrared imager and a displacement sensor.

10. The laser continuous liquid interface additive manufacturing device of a rod piece according to claim 9, wherein: the substrate and the wire feeding device are connected with an upper computer, and the upper computer controls the movement speed and the wire feeding speed.