Plasma as a heat source under high pressure fuse welding device and method

Abstract

The present invention discloses a fuse welding device and method using a plasma as a heat source under high pressure. In the device, a laser welding head is arranged above the workpiece to be welded to emit a laser beam; a reflecting mirror is fixedly arranged on the laser welding head with adjustable position and angle to reflect the laser beam; a target is fixedly arranged on the laser welding head with adjustable position and angle. The target receives the laser beam from the reflecting mirror in a high-pressure environment greater than 1 MPa to form a plasma jet in the normal direction of the target; a push-pull wire feeding mechanism is fixedly arranged on the laser welding head with adjustable position and angle. A wire feeding conduit is clamped by the push-pull wire feeding mechanism. A welding wire is threaded through the wire feeding conduit and extends out at the end close to the workpiece so that the plasma jet heats the end of the welding wire to form a molten droplet. When the size of the molten droplet is greater than a predetermined size, the push-pull wire feeding mechanism pushes the welding wire so that the molten droplet at the end contacts the molten pool on the workpiece, and then pulls back to make the end of the welding wire located at the heating position of the plasma jet.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding, and particularly relates to a fuse welding device and method with plasma as the heat source under high pressure. Background Art

[0002] Laser deep penetration welding has the advantages of a high weld depth-to-width ratio, a small heat-affected zone, and a high welding speed, so it is widely used. Under normal pressure environment, when the laser energy density is higher than a certain critical value, strong evaporation occurs on the material surface. Under the action of the evaporation recoil pressure, the molten pool liquid surface sinks downward, forming a narrow small hole deep into the molten pool, thus forming a narrow and deep weld.

[0003] As is well known, the environmental pressure will affect the evaporation behavior of materials. Therefore, the recoil pressure and welding penetration depth during the laser welding process are also closely related to the environmental pressure. The laser beam can be transmitted over a long distance through an optical fiber, and there are no various hidden dangers brought by underwater live working. Therefore, it has a good development prospect in the field of underwater welding. However, when the environmental pressure is as high as 15 MPa, the penetration depth obtained when the laser beam acts on the metal surface is extremely small, and welding cannot be achieved. The reason is that after the plasma beam above the molten pool is formed under high pressure environment, it is first compressed under the action of the environmental pressure, resulting in a decrease in volume. Under the condition that the number of particles in the plasma remains unchanged, the decrease in the plasma volume leads to an increase in particle density and an enhancement of inverse bremsstrahlung absorption. Therefore, the energy absorbed by the plasma increases, which further promotes the further enhancement of the plasma. Eventually, a highly dense and highly bright plasma is formed, making most of the laser energy absorbed and shielded by the plasma, and the obtained weld penetration depth is very small.

[0004] The information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention proposes a fuse welding device and method with plasma as the heat source under high pressure. In view of the fact that the penetration depth of the material directly irradiated by the laser under high pressure environment is very shallow and the plasma temperature is very high, the present invention uses the highly dense and highly bright light-induced plasma under high pressure environment as the heat source to heat the welding wire to achieve laser wire filling welding, which has good feasibility. This method cleverly realizes the transformation of the "harmful" highly dense and highly bright light-induced plasma under high pressure environment into "beneficial", and finds a new solution to the problem of laser welding under high pressure environment.

[0006] The object of the present invention is achieved through the following technical solutions. A fuse welding device with plasma as the heat source under high pressure includes:

[0007] A laser welding head, which is arranged above the workpiece to be welded to emit a laser beam;

[0008] A mirror, which is fixedly mounted on the laser welding head in an adjustable position and angle to reflect the laser beam;

[0009] A target material, which is fixedly mounted on the laser welding head in an adjustable position and angle. The target material receives the laser beam from the mirror under an environment greater than 1 MPa to form a plasma jet in the normal direction of the target material;

[0010] A push-pull wire feeding mechanism, which is fixedly mounted on the laser welding head in an adjustable position and angle;

[0011] A wire feeding conduit, which is clamped by the push-pull wire feeding mechanism. A welding wire is threaded through the wire feeding conduit and extends at the end close to the workpiece so that the plasma jet heats the end of the welding wire to form a molten droplet. When the size of the molten droplet is greater than a predetermined size, the push-pull wire feeding mechanism pushes the welding wire so that the molten droplet at the end contacts the molten pool on the workpiece, and then pulls back to make the end of the welding wire located at the heating position of the plasma jet.

[0012] In the fuse welding device with plasma under high pressure as the heat source, the target material and the workpiece are made of the same material.

[0013] In the fuse welding device with plasma under high pressure as the heat source, the pressure value of the high-pressure environment is related to the material of the target material. When the target material is magnesium alloy, aluminum alloy or zirconium alloy, the pressure value is not less than 1.0 MPa. When the target material is steel or titanium alloy, the pressure value is not less than 1.2 MPa. When the target material is molybdenum alloy, the pressure value is not less than 1.5 MPa.

[0014] In the fuse welding device with plasma under high pressure as the heat source, the laser beam is fiber laser, Nd:YAG laser or CO 2 laser.

[0015] In the fuse welding device with plasma under high pressure as the heat source, the predetermined size is twice the diameter of the welding wire.

[0016] In the fuse welding device with plasma under high pressure as the heat source, the molten droplets enter the molten pool in the form of short-circuit transfer.

[0017] In the fuse welding device with plasma under high pressure as the heat source, the laser beam forms a plasma jet in the normal direction of the target material.

[0018] In the fuse welding device with plasma under high pressure as the heat source, the push-pull wire feeding mechanism, the mirror and the target material are respectively fixed on the laser welding head through a wire feeding mechanism connecting rod, a mirror connecting rod and a target material connecting rod to adjust their positions and angles.

[0019] In the fuse welding device using high-pressure plasma as a heat source, the wire feeding mechanism connecting rod, the reflector connecting rod and the target material connecting rod are all hinge connecting rod mechanisms.

[0020] The welding method of the fuse welding device using plasma as a heat source under high pressure comprises:

[0021] In the first step, the laser welding head emits a laser beam, which is first incident on the surface of the reflector and then incident on the surface of the target at a certain angle, forming a plasma jet ejected along the normal direction of the target in a high-pressure environment;

[0022] In the second step, the push-pull wire feeding mechanism uniformly feeds the welding wire forward at a first speed, so that the end of the welding wire is heated by the plasma jet to form a molten droplet, and the size of the molten droplet at the end gradually increases as the welding wire is fed;

[0023] In the third step, when the molten droplet at the end reaches a predetermined size, the push-pull wire feeding mechanism uniformly feeds the welding wire forward at a second speed, so that the molten droplet at the end contacts the molten pool, and the molten droplet enters the molten pool in a short-circuit transition form;

[0024] In the fourth step, the push-pull wire feeding mechanism draws the welding wire backward at a third speed so that the end of the welding wire is located at a heating position of the plasma jet;

[0025] The fifth step is to repeat the operations of the second step to the fourth step at a certain frequency, and finally weld a whole weld on the workpiece over and over again.

[0026] Compared with the prior art, the present invention has the following advantages: the fuse welding device with plasma as heat source under high pressure in the present invention aims at the problem that the density and brightness of laser welding plasma are significantly enhanced under high pressure environment, a large amount of energy is absorbed and shielded, resulting in a significant reduction in the depth of penetration, and it is difficult to effectively achieve metal connection. It is proposed to use high-density and high-brightness photoinduced plasma as a heat source under high pressure environment to melt the welding wire for laser wire filling welding, and promote the transition of molten droplets to the molten pool with the help of plasma jet force, which can be used for the connection and repair of metal structures under high pressure environment. This method utilizes the characteristics of high density and high temperature of plasma under high pressure environment, uses high-density and high-brightness photoinduced plasma under high pressure environment as a heat source to heat the welding wire to achieve laser wire filling welding, and realizes the spraying of high-density and high-brightness plasma jet toward the molten pool through reflection, promotes the stable transition of melting point to the molten pool, thereby cleverly realizing the "harmful change of high-density and high-brightness photoinduced plasma under high pressure environment" to be beneficial, and finds a new solution to the problem of laser welding under high pressure environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Upon reading the detailed description in the following preferred specific embodiments, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The accompanying drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.

[0028] In the drawings:

[0029] Figure 1 is a schematic structural diagram of a fuse welding device with a plasma as the heat source under high pressure according to an embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of the surfacing application scenario of a fuse welding device with a plasma as the heat source under high pressure according to an embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of the butt welding application scenario of a fuse welding device with a plasma as the heat source under high pressure according to another embodiment of the present invention;

[0032] Figure 4 is a schematic diagram of a highly dense and highly bright photoinduced plasma jet generated after a laser is incident on the surface of a pure titanium TA1 target under an ambient pressure of 1.2 MPa by a fuse welding device with a plasma as the heat source under high pressure according to another embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of a highly dense and highly bright photoinduced plasma jet generated after a laser is incident on the surface of a pure zirconium target under an ambient pressure of 1.0 MPa by a fuse welding device with a plasma as the heat source under high pressure according to another embodiment of the present invention;

[0034] Figure 6 is a schematic diagram of a highly dense and highly bright photoinduced plasma jet generated after a laser is incident on the surface of a magnesium alloy target under an ambient pressure of 1.0 MPa by a fuse welding device with a plasma as the heat source under high pressure according to another embodiment of the present invention;

[0035] Figure 7 is a schematic diagram of the process of a highly dense and highly bright photoinduced plasma jet generated after a laser is incident on the surface of a stainless steel target under an ambient pressure of 1.2 MPa by a fuse welding device with a plasma as the heat source under high pressure heating a welding wire and forming a molten droplet.

[0036] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments. Specific Embodiments

[0037] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying Figures 1 to 7 drawings. Although specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0038] It should be noted that in the description of the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. The specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in the functions of components as the criterion for distinction. As mentioned throughout the specification and claims, the term "comprising" or "including" is an open-ended term and should be interpreted as "including but not limited to". The subsequent description in the specification is the preferred embodiment for implementing the present invention, but the description is for the purpose of the general principles of the specification and is not used to limit the scope of the present invention. The protection scope of the present invention shall be determined by the scope defined by the appended claims.

[0039] For the convenience of understanding the embodiments of the present invention, the following will further explain with specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation to the embodiments of the present invention.

[0040] For better understanding, as Figures 1 to 7 shown, a fuse welding device with a plasma as a heat source under high pressure includes

[0041] a laser welding head 2, which is arranged above the workpiece 9 to be welded to emit a laser beam 1;

[0042] a mirror 8, which is fixedly arranged on the laser welding head 2 with adjustable position and angle to reflect the laser beam 1;

[0043] a target 14, which is fixedly arranged on the laser welding head 2 with adjustable position and angle, and the target 14 receives the laser beam 1 from the mirror 8 in an environment of greater than 1 MPa to form a plasma jet 12 in the normal direction of the target 14;

[0044] a push-pull wire feeding mechanism 5, which is fixedly arranged on the laser welding head 2 with adjustable position and angle,

[0045] A wire feeding conduit 7 is clamped by the push-pull wire feeding mechanism 5. A welding wire 3 is threaded through the wire feeding conduit 7 and extends at the end close to the workpiece 9 such that the plasma jet 12 heats the end of the welding wire 3 to form a molten droplet 10. When the size of the molten droplet 10 is greater than a predetermined size, the push-pull wire feeding mechanism 5 pushes the welding wire 3 such that the molten droplet 10 at the end contacts the molten pool 11 on the workpiece 9, and then pulls back to position the end of the welding wire 3 at the heating position of the plasma jet 12.

[0046] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the target 14 and the workpiece 9 are made of the same material.

[0047] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the pressure value of the high-pressure environment is related to the material of the target 14. When the target 14 is made of magnesium alloy, aluminum alloy or zirconium alloy, the pressure value is not less than 1.0 MPa. When the target 14 is made of steel or titanium alloy, the pressure value is not less than 1.2 MPa. When the target 14 is made of molybdenum alloy, the pressure value is not less than 1.5 MPa.

[0048] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the laser beam 1 is a fiber laser, Nd:YAG laser or CO 2 laser.

[0049] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the predetermined size is twice the diameter of the welding wire 3.

[0050] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the molten droplet 10 enters the molten pool 11 in a short-circuit transfer form.

[0051] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the laser beam 1 forms a plasma jet 12 in the normal direction of the target 14.

[0052] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the push-pull wire feeding mechanism 5, the mirror 8 and the target 14 are respectively fixed to the laser welding head 2 through a wire feeding mechanism connecting rod 4, a mirror connecting rod 6 and a target connecting rod 15 to adjust their positions and angles.

[0053] In a preferred embodiment of the fuse welding device with plasma under high pressure as the heat source, the wire feeding mechanism connecting rod 4, the mirror connecting rod 6 and the target connecting rod 15 are all hinge connecting rod mechanisms.

[0054] In one embodiment, the temperature of the plasma is not less than 1800K.

[0055] In one embodiment, the second speed is greater than the first speed.

[0056] In one embodiment, the third speed is greater than the second speed.

[0057] In one embodiment, a fuse welding device with plasma as the heat source under high pressure includes a laser welding head 2, a push-pull wire feeding mechanism 5, a mirror 8, a target 14, and a wire feeding conduit 7; wherein the push-pull wire feeding mechanism 5, the mirror 8, and the target 14 are respectively fixed on the laser welding head 2 through a wire feeding mechanism connecting rod 4, a mirror connecting rod 6, and a target connecting rod 15, and their positions and angles can be adjusted through a hinge connecting rod mechanism; wherein the material of the target 14 is the same as that of the workpiece 9. The lower limit of the ambient pressure varies depending on the material. For magnesium alloys, aluminum alloys, and zirconium alloys, P ≥ 1.0 MPa; for steel and titanium alloys, P ≥ 1.2 MPa; for molybdenum alloys, P ≥ 1.5 MPa; the push-pull wire feeding mechanism 5 can achieve the forward feeding and backward retraction of the welding wire 3.

[0058] In one embodiment, the position and inclination angle of the mirror 8 are adjustable, and the reflectivity of the incident light reaches more than 99%; the incident laser beam 1 can be fiber laser, Nd:YAG laser or CO 2 laser; the position and inclination angle of the target 14 are adjustable, and the material of the target 14 is the same as that of the workpiece 9 to be welded.

[0059] In one embodiment, the height and inclination angle of the wire feeding conduit 7 are adjustable; the laser beam 1 first irradiates the surface of the mirror 8, and the reflected light irradiates the surface of the target 14 at a certain angle, forming a highly dense and highly bright plasma jet 12 spraying along the normal direction of the target 14 in a high-pressure environment. The highly dense and highly bright plasma jet 12 sprays towards the molten pool 11, which helps the stable transition of the melting point to the molten pool 11; the push-pull wire feeding mechanism 5 slowly and uniformly feeds the welding wire 3 forward, so that the end of the welding wire 3 is fully heated by the plasma, and as the welding wire 3 is fed, the size of the molten droplet 10 at the end of the welding wire 3 gradually increases; when the diameter of the molten droplet 10 at the end of the welding wire 3 increases to about 2 times the diameter of the welding wire 3, the push-pull wire feeding mechanism 5 quickly and uniformly feeds the welding wire 3 forward, so that the molten droplet 10 at the end of the welding wire 3 contacts the molten pool 11, and the molten droplet 10 enters the molten pool 11 in the form of short-circuit transfer; the push-pull wire feeding mechanism 5 quickly retracts the welding wire 3 backward, so that the end of the welding wire 3 is in the position heated by the plasma; a series of operations of slowly feeding the wire forward to grow the molten droplet 10, quickly feeding the wire forward to achieve short-circuit transfer of the molten droplet 1O, and retracting the welding wire 3 are repeated at a certain frequency, and so on in a cycle, and finally a whole weld seam 13 is welded on the workpiece 9.

[0060] The welding method of the fuse welding device with plasma as the heat source under high pressure includes,

[0061] In the first step, the laser welding head 2 emits a laser beam 1. The laser beam 1 first impinges on the surface of the mirror 8 and then impinges on the surface of the target 14 at a certain angle, forming a plasma jet 12 that jets along the normal direction of the target 14 in a high-pressure environment;

[0062] In the second step, the push-pull wire feeding mechanism 5 feeds the welding wire 3 forward at a first constant speed, so that the end of the welding wire 3 is heated by the plasma jet 12 to form a molten droplet 10, and the size of the molten droplet 10 at the end gradually increases as the welding wire 3 is fed;

[0063] In the third step, when the molten droplet 10 at the end reaches a predetermined size, the push-pull wire feeding mechanism 5 feeds the welding wire 3 forward at a second constant speed, so that the molten droplet 10 at the end contacts the molten pool 11, and the molten droplet 10 enters the molten pool 11 in a short-circuit transfer form;

[0064] In the fourth step, the push-pull wire feeding mechanism 5 withdraws the welding wire 3 backward at a third speed, so that the end of the welding wire 3 is located at the heating position of the plasma jet 12;

[0065] In the fifth step, the operations in the second step to the fourth step are repeated at a certain frequency, and this cycle continues until the entire weld seam 13 is welded on the workpiece 9.

[0066] In one embodiment, the laser beam 1 first impinges on the surface of the mirror 8, and the reflected light impinges on the surface of the target 14 at a certain angle, forming a highly dense and highly bright plasma jet 12 that jets along the normal direction of the target 14 in a high-pressure environment;

[0067] b) The push-pull wire feeding mechanism 5 feeds the welding wire 3 forward slowly and uniformly, so that the end of the welding wire 3 is fully heated by the plasma, and the size of the molten droplet 10 at the end of the welding wire 3 gradually increases as the welding wire 3 is fed;

[0068] c) When the molten droplet 10 at the end of the welding wire 3 reaches a certain size, the push-pull wire feeding mechanism 5 feeds the welding wire 3 forward quickly and uniformly, so that the molten droplet 10 at the end of the welding wire 3 contacts the molten pool 11, and the molten droplet 10 enters the molten pool 11 in a short-circuit transfer form;

[0069] d) The push-pull wire feeding mechanism 5 quickly withdraws the welding wire 3 backward, so that the end of the welding wire 3 is in the position heated by the plasma;

[0070] e) The operations in b) to d) are repeated at a certain frequency, and this cycle continues until the entire weld seam 13 is welded on the workpiece 9.

[0071] In one embodiment, for the surfacing welding on the pure titanium TA1 surface, the target 14 is pure titanium TA1, the IPG YLS-6000 fiber laser, the pure titanium TA1 welding wire 3 with a diameter of 2.4 mm, the power is 3000 W, the welding speed is 1.8 m / min, the spot diameter on the surface of the target 14 is 0.5 - 1.0 mm, the shielding gas is Ar gas, and the ambient pressure is 1.2 MPa. Figure 4 The highly dense and highly bright photoinduced plasma jet 12 generated after the laser is incident on the surface of the pure titanium TA1 target 14 under the ambient pressure of 1.2 MPa is given, and it is compared with the photoinduced plasma under one standard atmosphere.

[0072] In one embodiment, for the surfacing welding on the pure zirconium surface, the target 14 is pure zirconium, the IPG YLS-6000 fiber laser, the pure zirconium welding wire 3 with a diameter of 2.4 mm, the power is 3000 W, the welding speed is 1.8 m / min, the spot diameter on the surface of the target 14 is 0.5 - 1.0 mm, the shielding gas is Ar gas, and the ambient pressure is 1.0 MPa. Figure 5 The highly dense and highly bright photoinduced plasma jet 12 generated after the laser is incident on the surface of the pure zirconium target 14 under the ambient pressure of 1.0 MPa is given, and it is compared with the photoinduced plasma under one standard atmosphere.

[0073] In one embodiment, for the surfacing welding on the magnesium alloy surface, the target 14 is magnesium alloy, the IPG YLS-6000 fiber laser, the magnesium alloy welding wire 3 with a diameter of 2.4 mm, the power is 2000 W, the welding speed is 1.8 m / min, the spot diameter on the surface of the target 14 is 0.5 - 1.0 mm, the shielding gas is Ar gas, and the ambient pressure is 1.0 MPa. Figure 6 The highly dense and highly bright photoinduced plasma jet 12 generated after the laser is incident on the surface of the magnesium alloy target 14 under the ambient pressure of 1.0 MPa is given, and it is compared with the photoinduced plasma under one standard atmosphere.

[0074] In one embodiment, for the surfacing welding on the stainless steel surface, the target 14 is stainless steel, the IPG YLS-6000 fiber laser, the stainless steel welding wire 3 with a diameter of 2.4 mm, the power is 3000 W, the welding speed is 1.8 m / min, the wire feeding speed is 1.8 m / min, the spot diameter on the surface of the target 14 is about 0.5 - 1.0 mm, the shielding gas is Ar gas, and the ambient pressure is 1.2 MPa. Figure 7The process of the highly dense and bright laser-induced plasma jet 12 generated after the laser irradiates the surface of the stainless steel target 14 heating the welding wire 3 and forming molten droplets 10 under the environmental pressure of 1.2 MPa is presented. From the above examples, it can be seen that the present invention aims at the problem that in a high-pressure environment, the density and brightness of the laser welding plasma are significantly enhanced, a large amount of energy is absorbed and shielded, resulting in a significant reduction in the penetration depth and making it difficult to effectively achieve metal connection. It is proposed to use the highly dense and bright laser-induced plasma in a high-pressure environment as a heat source to melt the welding wire 3 for laser wire filling welding, and with the help of the acting force of the plasma jet 12 to promote the transition of the molten droplets 10 to the molten pool 11, which can be used for the connection and repair of metal structures in a high-pressure environment.

[0075] Although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields. The specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A fuse welding device with plasma as the heat source under high pressure, characterized in that, it includes, a laser welding head, which is arranged above the workpiece to be welded to emit a laser beam; a reflector, which is fixedly arranged on the laser welding head with adjustable position and angle to reflect the laser beam; a target, which is fixedly arranged on the laser welding head with adjustable position and angle. The target receives the laser beam from the reflector in an environment with a pressure greater than 1 MPa to form a plasma jet in the normal direction of the target; a push-pull wire feeding mechanism, which is fixedly arranged on the laser welding head with adjustable position and angle; a wire feeding conduit, which is clamped by the push-pull wire feeding mechanism. The welding wire passes through the wire feeding conduit and the end of the welding wire extends out so that the plasma jet heats the end of the welding wire to form a molten droplet. The end is close to the workpiece. When the size of the molten droplet is greater than a predetermined size, the push-pull wire feeding mechanism pushes the welding wire so that the molten droplet at the end contacts the molten pool on the workpiece, and then pulls back so that the end of the welding wire is located at the heating position of the plasma jet, and the force of the plasma jet is used to promote the transition of the molten droplet to the molten pool. The temperature of the plasma is not less than 1800K. The materials of the target and the workpiece are the same. The pressure value of the high-pressure environment is related to the material of the target. When the target is magnesium alloy, aluminum alloy or zirconium alloy, the pressure value is greater than 1.0 MPa. When the target is steel or titanium alloy, the pressure value is not less than 1.2 MPa. When the target is molybdenum alloy, the pressure value is not less than 1.5 MPa. The reflectivity of the reflector to the incident light reaches more than 99%. The material of the target is the same as that of the workpiece to be welded.

2. The fuse welding device with plasma as the heat source under high pressure according to claim 1, characterized in that, The laser beam is a fiber laser, Nd:YAG laser or CO 2 laser.

3. The fuse welding device with plasma as the heat source under high pressure according to claim 1, characterized in that, the predetermined size is twice the diameter of the welding wire.

4. The fuse welding device with plasma as the heat source under high pressure according to claim 1, characterized in that, the molten droplet enters the molten pool in a short-circuit transfer form.

5. The fuse welding device with plasma as the heat source under high pressure according to claim 1, characterized in that, the laser beam forms a plasma jet in the normal direction of the target.

6. The fuse welding device with plasma as the heat source under high pressure according to claim 1, characterized in that, the push-pull wire feeding mechanism, the reflector and the target are respectively fixed on the laser welding head through a wire feeding mechanism connecting rod, a reflector connecting rod and a target connecting rod to adjust their positions and angles.

7. The fuse welding device with plasma as the heat source under high pressure according to claim 6, characterized in that, the wire feeding mechanism connecting rod, the reflector connecting rod and the target connecting rod are all hinge connecting rod mechanisms.

8. The welding method of the fuse welding device with plasma as the heat source under high pressure according to any one of claims 1-7, characterized in that, it includes, the first step, the laser welding head emits a laser beam. The laser beam first enters the surface of the reflector and then enters the surface of the target at a certain angle to form a plasma jet spraying along the normal direction of the target in a high-pressure environment; In the second step, the wire push-pull feeding mechanism feeds the welding wire forward at a first constant speed, so that the end of the welding wire is heated by the plasma jet to form a molten droplet, and the size of the molten droplet at the end gradually increases as the welding wire is fed; In the third step, when the molten droplet at the end reaches a predetermined size, the wire push-pull feeding mechanism feeds the welding wire forward at a second constant speed, so that the molten droplet at the end contacts the molten pool, and the molten droplet enters the molten pool in the form of short-circuit transfer; In the fourth step, the wire push-pull feeding mechanism withdraws the welding wire backward at a third speed, so that the end of the welding wire is located at the heating position of the plasma jet; In the fifth step, the operations of the second step to the fourth step are repeated at a certain frequency, and finally a complete weld seam is welded on the workpiece in a cycle.

Images