A four-tungsten electrode rotary additive manufacturing apparatus and additive manufacturing method

Abstract

This invention relates to the field of tungsten inert gas (TIG) welding additive manufacturing technology, and provides a four-TIG rotary additive manufacturing apparatus and method. The apparatus includes a base, a turntable, a wire feeder, and four TIG welding torches. The turntable is rotatably mounted on the base, and the wire feeder is fixedly mounted on the base, passing through the center of the turntable. The turntable can rotate around the wire feeder. The four TIG welding torches are evenly distributed around the wire feeder on the turntable, and are symmetrically arranged with the wire feeder as the center. The tungsten electrodes of the four TIG welding torches face the welding wire fed from the wire feeder. The turntable drives the four TIG welding torches to rotate, forming a rotating arc during welding. This invention can precisely control the droplet size and promote droplet transfer with higher energy density, improving the additive manufacturing shape control effect.

Description

Technical Field

[0001] This invention relates to the field of tungsten inert gas welding additive manufacturing technology, and in particular to a four-tungsten electrode rotary additive manufacturing apparatus and additive manufacturing method. Background Technology

[0002] Arc welding additive manufacturing technology typically uses an electric arc as a heat source to melt metal wire. The movement paths of the wire feed end and the workpiece end are programmed. With the movement of the wire feed end or the position of the workpiece end, complex metal parts can be printed by flat welding without support. However, during the additive manufacturing process, local dimensional deviations are often caused by the non-uniformity of the molten droplet during the transition. Therefore, if the additive manufacturing process can be carried out by controlling the transition of the molten droplet size, the accuracy of the additive parts and the efficiency of additive manufacturing can be improved.

[0003] During flat welding, surface tension acts as a resistance to droplet transition, causing the droplets to form spherical shapes and resulting in physical adsorption, thus suspending the droplets at the solid-liquid interface. In traditional additive manufacturing equipment, the introduction of a transverse magnetic field, combined with the current flowing through the molten pool, stirs the pool, enhancing its fluidity, helping to eliminate porosity, refine grains, and ultimately improve the quality of the additively manufactured parts. However, the orientation relationship between the transverse magnetic field and the current produces an uneven component force in the horizontal direction, causing deviation during droplet transfer. When a DC positive polarity is used in conjunction with a transverse magnetic field, a droplet forms on one side after the welding wire enters the arc. The droplet acts as a liquid conductor in the arc. At this time, the current flowing through the liquid conductor points from the workpiece to the tungsten electrode, in an upward direction and slightly forward. Under the influence of the magnetic field force, according to the left-hand rule, the direction of the magnetic field force, the direction of the current, and the direction of the force are all orthogonal. At this time, the magnetic field force on the droplet points to a position slightly downward and forward. The horizontal component of the magnetic field force is significantly stronger than the vertical component. However, the horizontal component does not promote droplet transfer and will have the side effect of causing the droplet to deviate from the falling axis during transfer. Therefore, this method is not effective in controlling droplet transfer. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a four-tungsten electrode rotary additive manufacturing apparatus and method of use, which can precisely control the droplet size and promote droplet transition with higher energy density, thereby improving the additive shape control effect.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A four-tungsten electrode rotary additive manufacturing apparatus is characterized by comprising a base, a turntable, a wire feeding gun, four TIG welding guns, a circuit system, a motor, and a transmission gear set. The motor is fixed on the base, and the output shaft of the motor is connected to the turntable through the transmission gear set. The turntable is rotatably mounted on the base. The wire feeding gun is fixedly mounted on the base through the center of the turntable, and the turntable can rotate around the wire feeding gun.

[0007] Four TIG welding torches are evenly distributed around the wire feeder on the turntable, and the four TIG welding torches are symmetrically arranged with the wire feeder as the center. The tungsten electrodes of the four TIG welding torches face the welding wire fed by the wire feeder. The four TIG welding torches and the wire feeder are electrically connected to the power supply through a circuit system that passes through the base and the turntable.

[0008] Furthermore, the turntable and the base are rotatably connected via a second bearing, and the wire feed gun and the turntable are rotatably connected via a first bearing; the gear set includes a driven gear fixedly connected to the turntable and a driving gear fixedly connected to the output shaft, and the driven gear meshes with the driving gear.

[0009] Furthermore, the circuit system includes a conductive post that can rotate with the turntable. Four annular conductive rails are arranged around the outer circumference of the conductive post. Inside, there are wires that are respectively connected to one of the four annular conductive rails and connected to four TIG welding guns. The four annular conductive rails are in contact with a brush and are electrically connected to a power source through wires passing through the base.

[0010] Furthermore, the four TIG welding torches are positioned opposite each other in pairs, and the connection between the tungsten electrodes of the two TIG welding torches positioned opposite each other in each group passes through the front end of the welding wire; the four TIG welding torches are respectively tilted toward the wire feeder, and the connection between them and the turntable is detachable, and the distance between the wire feeders is adjustable.

[0011] Furthermore, the TIG welding torch includes a torch body and a tungsten electrode assembly disposed on the torch body. The tungsten electrode assembly includes a welding torch tube, a tungsten electrode clamp, a tungsten electrode, and a ceramic nozzle. The welding torch tube and the ceramic nozzle are connected by threads. The tungsten electrode clamp is installed inside the welding torch tube and is axially fixed by the ceramic nozzle. The tungsten electrode is installed inside the tungsten electrode clamp and locked by a conical surface.

[0012] Furthermore, the tip of the tungsten electrode is bent inward and faces the wire feed gun.

[0013] Furthermore, the wire feeder includes a gas protection mechanism and a cooling mechanism. The gas protection mechanism is located between the wire feed nozzle and the wire feed tube of the wire feeder, and the cooling mechanism is located between the TIG welding torch and the wire feeder.

[0014] Furthermore, the four tungsten electrodes are powered by two DC pulse power supplies. One set of two TIG welding torches, arranged opposite each other, is connected to the positive and negative terminals of one power supply, and the other set of two TIG welding torches, arranged opposite each other, is connected to the positive and negative terminals of another power supply.

[0015] Furthermore, the four tungsten electrodes are powered by a single power source, and the four TIG welding torches are all connected to the positive terminal of the same power source, while the welding wire is connected to the negative terminal of the same power source.

[0016] The additive manufacturing method of the four-tungsten electrode rotary additive manufacturing apparatus is characterized by comprising the following steps:

[0017] Adjust the positions of the wire feeder and TIG welding torch to focus on the tip of the welding wire, and plan the additive manufacturing path;

[0018] In dual-power mode, the gas, liquid, and electric switches are turned on to start the additive manufacturing process. A set of TIG welding torches, arranged opposite each other, are connected to the positive and negative terminals of one power source, while another set of TIG welding torches, arranged opposite each other, are connected to the positive and negative terminals of another power source. During the additive manufacturing process, two transverse pulsed arcs are formed. The turntable drives the four TIG welding torches to rotate around the wire feeder, forming a rotating arc during welding. The welding wire is melted as it passes through the rotating arc, and under the combined action of cutting and gravity during the rotation of the arc, it is transformed into droplets of controllable size that drip downwards.

[0019] In single-power-supply mode, the gas, hydraulic, and electrical switches are turned on to begin the additive manufacturing process. Four TIG welding torches are connected to the positive terminal, and the welding wire to the negative terminal. During additive manufacturing, four transverse pulsed arcs are formed. The turntable drives the four TIG welding torches to rotate around the wire feed torch, creating a rotating arc during welding. The welding wire is melted as it passes through the rotating arc, and simultaneously, under the combined effects of the cutting action of the rotating arc and gravity, it is shaped into controllable-sized droplets that drip downwards.

[0020] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0021] The four-tungsten electrode rotary additive manufacturing apparatus provided by this invention includes a base, a turntable, a wire feeder, and four TIG welding torches. The base is used to mount the turntable, and the wire feeder is mounted at the center of the turntable. TIG welding torches are mounted at the four positions of the wire feeder. The TIG welding torches arranged opposite each other are grouped together, tilted towards the wire feeder, and symmetrically distributed. The straight lines of the tungsten electrodes of each group of two groups of TIG welding torches intersect at the front end of the welding wire. The wire feeder is fixed on the base and is not affected by the rotation of the turntable. The turntable can drive the TIG welding torches to rotate, thereby forming a rotating arc during welding. This can overcome the adsorption effect of the welding wire on the molten droplet. By changing the lateral force on the molten droplet through the rotating arc, the droplet is selectively cut by the rotation speed during its growth, thus achieving precise control of the droplet size.

[0022] This invention uses the rotating arc generated between the tungsten electrodes of a rotating TIG welding torch as a heat source to melt the welding wire. It does not form a current loop with the workpiece and does not form a molten pool, thus avoiding the molten pool from affecting the droplet transition. Since the force of the rotating arc on the droplet is located on the horizontal plane and is evenly distributed around the droplet, it forms a transverse cutting effect. Combined with gravity, the droplet can be selected to fall at a certain moment of growth by controlling the rotation speed. The droplet transition is stable and the additive manufacturing shape control effect is good. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the four-tungsten electrode rotary additive manufacturing apparatus described in this invention;

[0024] Figure 2 This is a schematic cross-sectional view of the four-tungsten electrode rotary additive manufacturing apparatus of the present invention;

[0025] Figure 3 This is a schematic diagram of the power transmission structure of the turntable;

[0026] Figure 4 This is a schematic diagram of the circuit system structure for four TIG welding torches.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. First TIG welding torch, 2. Second TIG welding torch, 3. Wire feeder, 4. Turntable, 5. Base, 6. Third TIG welding torch, 7. Fourth TIG welding torch, 8. First bearing, 9. Second bearing, 10. Driven gear, 11. Drive gear, 12. Output shaft, 13. Motor, 14. Conductive post, 15. First annular conductive rail, 16. Second annular conductive rail, 17. Third annular conductive rail, 18. Fourth annular conductive rail, 19. First brush, 20. Second brush, 21. Third brush, 22. Fourth brush, 23. Tungsten electrode. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0030] The four-tungsten electrode rotary additive manufacturing apparatus of the present invention drives four TIG welding torches to rotate via a turntable, forming a rotating arc during welding, precisely controlling the size of the molten droplets, and promoting droplet transition with higher energy density, thereby improving the additive shape control effect.

[0031] Example 1

[0032] like Figure 1As shown, the four-tungsten electrode rotary additive manufacturing apparatus includes a base 5, a turntable 4, a wire feeder 3, and a first TIG welding torch 1, a second TIG welding torch 2, a third TIG welding torch 6, and a fourth TIG welding torch 7 distributed around the wire feeder 3. The turntable 4 is rotatably mounted on the base 5, and the wire feeder 3 is fixedly mounted on the base 5 through the center of the turntable 4. The turntable 4 can rotate around the wire feeder 3; the wire feeder is fixed on the base and is not affected by the rotation of the turntable.

[0033] The first TIG welding torch 1, the second TIG welding torch 2, the third TIG welding torch 6, and the fourth TIG welding torch 7 are evenly arranged on the turntable 4 around the wire feeder 3, and are symmetrically arranged with the wire feeder 3 as the center. The tungsten electrodes 23 of the four TIG welding torches face the welding wire fed by the wire feeder 3. The turntable 4 drives the four TIG welding torches to rotate, forming a rotating arc during welding. This rotating arc has a higher energy density due to the cross-rotation of the double arcs, thus it can melt the welding wire with a higher melting point to form a molten droplet. The rotating arc can also perform a transverse cutting effect on the molten droplet, and the size of the molten droplet can be more precisely controlled by controlling the rotation speed, so as to achieve better additive manufacturing control.

[0034] Specifically, such as Figure 2 As shown, in this embodiment of the invention, the plane where the base 5 is located is the xy plane, where the east-west direction corresponds to the y-axis direction and the north-south direction corresponds to the x-axis direction. The first TIG welding torch 1, the second TIG welding torch 2, the third TIG welding torch 6, and the fourth TIG welding torch 7 are respectively positioned in the east, west, south, and north directions of the wire feeder. The first TIG welding torch 1 and the fourth TIG welding torch 7, positioned opposite each other along the east-west direction, form one group; the second TIG welding torch 2 and the third TIG welding torch 6, positioned opposite each other along the north-south direction, form another group. They are all inclined towards the wire feeder 3, and the straight lines containing the tungsten electrodes of each group of TIG welding torches intersect at the front end of the welding wire.

[0035] The turntable 4 has a circular lower part and an external gear on its outer surface. A first annular conductive rail 15, a second annular conductive rail 16, a third annular conductive rail 17, and a fourth annular conductive rail 18 are arranged around the outer circumference of the turntable. The external gear in the middle of the turntable acts as a driven gear 10, and the upper part acts as a conductive post 14 for the first TIG welding torch 1, the second TIG welding torch 2, the third TIG welding torch 6, and the fourth TIG welding torch 7. The conductive post 14 has wires inside that connect to the first annular conductive rail 15, the second annular conductive rail 16, the third annular conductive rail 17, and the fourth annular conductive rail 18, respectively, and these wires are connected to the first TIG welding torch 1, the second TIG welding torch 2, the third TIG welding torch 6, and the fourth TIG welding torch 7 to provide power input. The first annular conductive rail 15, the second annular conductive rail 16, the third annular conductive rail 17, and the fourth annular conductive rail 18 are in contact with the first brush 19, the second brush 20, the third brush 21, and the fourth brush 22, respectively, and are electrically connected to the power supply through wires passing through the base 5. Figure 4 As shown.

[0036] The electric motor 13, which provides rotational power to the turntable 4, is fixed on the base 5. The output shaft 12 of the electric motor 13 transmits power through a meshing drive gear 11 and a driven gear 10. Figure 3 As shown. The drive gear 11 is located in the cavity inside the base 5 and is fixedly connected to the output shaft 12.

[0037] The turntable 4 and the base 5 are connected by a second bearing 9, enabling a rotatable connection between the turntable 4 and the base 5. The wire feeding gun 3 is connected to the turntable 4 by a first bearing 8, allowing the wire feeding gun 3 to be fixed relative to the base 5 but to rotate relative to the turntable 4.

[0038] The first TIG welding torch 1, the second TIG welding torch 2, the third TIG welding torch 6, and the fourth TIG welding torch 7 are all the same type of TIG welding torch, each including a torch body and a tungsten electrode assembly mounted on the torch body. The tungsten electrode assembly includes a welding torch tube, a tungsten electrode clamp, a tungsten electrode 23, and a ceramic nozzle. The welding torch tube and the ceramic nozzle are connected by threads. The tungsten electrode clamp is installed inside the welding torch tube and axially fixed by the ceramic nozzle. The tungsten electrode 23 is installed inside the tungsten electrode clamp and locked in place by a conical surface.

[0039] The tip of the tungsten electrode 23 is bent inward and faces the wire feed gun 3. The symmetrical bending of the tungsten electrodes of one set of TIG welding guns is used to guide the arc conduction and intersect with the arc of another set of TIG welding guns at the tip of the welding wire.

[0040] The wire feeder includes a gas protection mechanism and a cooling mechanism. The gas protection mechanism is located between the wire feed nozzle and the wire feed tube of the wire feeder, and the cooling mechanism is located between the TIG welding torch and the wire feeder.

[0041] In this invention, the two sets of TIG welding torches have two connection methods:

[0042] First, in the dual power supply mode, the four tungsten electrodes are powered by two DC pulse power supplies. One set of TIG welding torches is connected to one power supply, and the two TIG welding torches in each set are connected to the positive and negative terminals respectively. By controlling the phase difference of the two pulse currents, the arc can be better conducted to achieve the effect of resisting the interference of the two arcs.

[0043] Second, in the single power supply mode, the four tungsten electrodes are powered by one power supply. The four TIG welding guns are connected to the positive terminal, and the welding wire is connected to the negative terminal to resist arc interference.

[0044] In dual-power mode, the welding method of the four-tungsten electrode rotary additive manufacturing apparatus provided by the present invention includes the following steps:

[0045] Adjust the positions of the wire feeder and TIG welding torch to focus on the tip of the welding wire, and plan the additive manufacturing path;

[0046] Turn on the gas, liquid, and electric switches to start the additive manufacturing process. A set of TIG welding torches positioned opposite each other are connected to a power source. Two TIG welding torches in each set are connected to the positive and negative terminals, respectively. During the additive manufacturing process, two transverse pulsed arcs are formed. The turntable drives four TIG welding torches to rotate around the wire feeder, forming a rotating arc during welding. The welding wire is melted as it passes through the rotating arc, and under the combined action of cutting during the rotation of the arc and gravity, it is turned into droplets of controllable size that drip downwards.

[0047] In a single power supply mode, the welding method of the four-tungsten electrode rotary additive manufacturing apparatus provided by the present invention includes the following steps:

[0048] Adjust the positions of the wire feeder and TIG welding torch to focus on the tip of the welding wire, and plan the additive manufacturing path;

[0049] Turn on the gas, liquid, and electric switches to start the additive manufacturing process. Connect the four TIG welding torches to the positive terminal and the welding wire to the negative terminal. During the additive manufacturing process, four transverse pulsed arcs are formed. The turntable drives the four TIG welding torches to rotate around the wire feeder, forming a rotating arc during welding. The welding wire is melted as it passes through the rotating arc. At the same time, under the combined action of cutting during the rotation of the arc and gravity, it becomes droplets of controllable size that drip downwards.

[0050] The four-tungsten electrode rotary additive manufacturing apparatus provided by this invention can overcome the adsorption effect of welding wire on molten droplets. By changing the lateral force on the molten droplets through the rotating arc, it selectively cuts the droplets during their growth process by adjusting the rotation speed, achieving precise control over the droplet size. Specifically, the rotating arc generated between specific tungsten electrodes of the rotating welding torch serves as the heat source to melt the welding wire. It does not form a current loop with the workpiece and does not form a molten pool, thus avoiding the molten pool affecting the droplet transition. Since the force of the rotating arc on the droplet is located on the horizontal plane and is evenly distributed around the droplet, it works in conjunction with gravity. By controlling the rotation speed, the droplet can be selected to fall at a certain moment during its growth, resulting in a stable droplet transition and good additive manufacturing shape control.

[0051] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A four-tungsten electrode rotary additive manufacturing apparatus, characterized in that, Includes a base (5), a turntable (4), a wire feeder (3), four TIG welding torches, a circuit system, a motor (13), and a transmission gear set. The motor (13) is fixed on the base (5), and the output shaft (12) of the motor (13) is connected to the turntable (4) through the transmission gear set. The turntable (4) is rotatably mounted on the base (5). The wire feeder (3) passes through the center of the turntable (4) and is fixedly mounted on the base (5). The turntable (4) can rotate around the wire feeder (3). Four TIG welding torches are evenly distributed around the wire feeder (3) on the turntable (4), and the four TIG welding torches are symmetrically arranged with the wire feeder (3) as the center. The tungsten electrodes (23) of the four TIG welding torches face the welding wire fed by the wire feeder (3). The four TIG welding torches and the wire feeder (3) are electrically connected to the power supply through a circuit system that passes through the base (5) and the turntable (4). The four TIG welding torches are positioned opposite each other in pairs, and the connection between the tungsten electrodes (23) of the two TIG welding torches in each pair passes through the front end of the welding wire; the four TIG welding torches are respectively tilted toward the wire feeder (3), and the connection between them and the turntable (4) is detachable, and the distance between the wire feeders is adjustable. In dual power supply mode: the four tungsten electrodes are powered by two DC pulse power supplies. One set of two TIG welding torches, which are arranged opposite each other, are connected to the positive and negative terminals of one power supply, and the other set of two TIG welding torches, which are arranged opposite each other, are connected to the positive and negative terminals of the other power supply. In single-source mode: the four tungsten electrodes are powered by one power source, the four TIG welding torches are all connected to the positive terminal of the same power source, and the welding wire is connected to the negative terminal of the same power source.

2. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 1, characterized in that, The turntable (4) is rotatably connected to the base (5) via a second bearing (9), and the wire feed gun (3) is rotatably connected to the turntable (4) via a first bearing (8); the gear set includes a driven gear (10) fixedly connected to the turntable (4) and a driving gear (11) fixedly connected to the output shaft (12), and the driven gear (10) and the driving gear (11) mesh with each other.

3. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 1, characterized in that, The circuit system includes a conductive post (14) that can rotate with the turntable (4). Four annular conductive rails are arranged around the outer circumference of the conductive post (14). Inside, there are wires that are connected to one of the four annular conductive rails and connected to four TIG welding guns respectively. The four annular conductive rails are in contact with a brush and are electrically connected to the power supply through wires that pass through the base (5).

4. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 1, characterized in that, The TIG welding torch includes a torch body and a tungsten electrode assembly disposed on the torch body. The tungsten electrode assembly includes a welding torch tube, a tungsten electrode clamp, a tungsten electrode (23), and a ceramic nozzle. The welding torch tube and the ceramic nozzle are connected by threads.

5. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 4, characterized in that, The tungsten electrode clamp is installed inside the welding gun tube and is axially fixed by the ceramic nozzle. The tungsten electrode (23) is installed inside the tungsten electrode clamp and locked by the conical surface.

6. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 5, characterized in that, The tip of the tungsten electrode (23) is bent inward and faces the wire feed gun (3).

7. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 1, characterized in that, The wire feeding gun (3) includes a gas protection mechanism located between the wire feeding nozzle and the wire feeding tube of the wire feeding gun (3).

8. The four-tungsten electrode rotary additive manufacturing apparatus according to claim 7, characterized in that, The wire feeder (3) includes a cooling mechanism located between the TIG welding torch and the wire feeder (3).

9. The additive manufacturing method of the four-tungsten electrode rotary additive manufacturing apparatus according to any one of claims 1-8, characterized in that, Includes the following steps: Adjust the wire feeder (3) and TIG welding torch position to focus on the front end of the welding wire, and plan the additive manufacturing path; In dual power supply mode, the gas, liquid and electric switches are turned on to start the additive manufacturing process. A set of TIG welding guns are connected to the positive and negative terminals of one power supply respectively, and another set of TIG welding guns are connected to the positive and negative terminals of another power supply respectively. During the additive manufacturing process, two transverse pulse arcs are formed. The turntable (4) drives the four TIG welding guns to rotate around the wire feeder (3). During welding, a rotating arc is formed. The welding wire is melted during the rotating arc process. At the same time, under the combined action of cutting and gravity during the rotating arc process, it becomes a droplet of controllable size and drips downward. In single power supply mode, the gas, liquid and electric switches are turned on to start the additive manufacturing process. The four TIG welding guns are connected to the positive pole and the welding wire is connected to the negative pole. Four transverse pulse arcs are formed during the additive manufacturing process. The turntable (4) drives the four TIG welding guns to rotate around the wire feeder (3). A rotating arc is formed during welding. The welding wire is melted during the rotating arc process. At the same time, under the combined action of cutting and gravity during the rotation of the rotating arc, it becomes a droplet of controllable size and drips downward.

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