A welding method

Abstract

The invention discloses a welding method, belonging to the field of welding technology. The welding method includes adjusting the distance between the suction port of a negative pressure suction device and a first welding position; a molten pool is formed at the first welding position during welding, the molten pool has a keyhole opening from which plasma escapes, the keyhole opening has a first cross-sectional size, and the suction port of the negative pressure suction device sucks the plasma generated by welding; when the temperature sensor senses that the temperature of the plasma reaches a first preset temperature, the suction port is adjusted for the first time, and the keyhole opening has a second cross-sectional size; the m+1 cross-sectional size of the keyhole opening is obtained by an image acquisition device, and when the m+1 cross-sectional size is equal to or greater than the preset cross-sectional size of the keyhole opening, the suction port of the negative pressure suction device stops adjusting; after the first welding position is welded, the laser beam moves to the nth welding position. In this way, the problem that the porosity defects caused by laser deep fusion welding affect the quality of weld formation is solved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a welding method. Background Art

[0002] As a high-quality and efficient welding method, laser welding has the advantages of intelligence, high energy density, and high speed. It is one of the most widely used material processing technologies in the world. It is known as the green manufacturing technology of the 21st century and has become the main connection process technology for the battery module shell of new energy vehicles, the aluminum alloy body of high-speed rail vehicles, and the skin of the C919 large aircraft. However, the plasma plume in laser deep melting welding will destroy the stability of the molten pool and keyhole, affecting the formation of the weld and even failing to form a continuous weld.

[0003] There is an inherent physical phenomenon in laser deep penetration welding: a group of hot luminous bodies appears above the molten pool, usually called plasma plume. However, plume is closely related to the welding process, seriously hindering the transmission of laser energy, and causing interruptions in the incident laser energy, resulting in violent fluctuations in the welding molten pool, which is prone to form a large amount of spatter and welding defects such as pores and collapse. On the one hand, the formed plasma plume and the laser produce inverse bremsstrahlung absorption, resulting in the shielding of the laser energy by the plasma plume; on the other hand, the irregular fluctuation state of the plasma plume causes the sample to absorb laser energy unstably, which is easy to cause fluctuations in the keyhole and molten pool during welding, thereby causing welding defects and seriously affecting the service performance of the welded structure. Therefore, eliminating or controlling the dynamic behavior of the plasma plume in laser deep penetration welding has become a difficult problem that must be overcome in the research of high-power fiber laser deep penetration welding. Summary of the invention

[0004] In order to solve the problem that the porosity defects caused by laser deep penetration welding affect the quality of weld formation, the present invention provides a welding method, comprising the following steps:

[0005] Adjust the distance between the suction port of the negative pressure suction device and the first welding position within a preset distance range;

[0006] The laser beam is directed at the first welding position in a protective gas atmosphere;

[0007] A molten pool is formed at the first welding position;

[0008] A keyhole opening for plasma escape is formed within the range of the molten pool, the intersection of the keyhole opening and the surface of the molten pool forms a first cross-sectional dimension, and a plasma suction channel is formed between the suction port of the negative pressure suction device and the keyhole opening;

[0009] When the temperature sensor on the negative pressure suction device senses that the temperature of the plasma reaches a first preset temperature, the suction port of the negative pressure suction device is adjusted for the first time, and the first cross-sectional dimension is transformed into a second cross-sectional dimension;

[0010] The suction port of the negative pressure suction device is adjusted for the mth time, and the m+1th cross-sectional dimension of the keyhole is acquired by the image acquisition device, and the m+1th cross-sectional dimension is equal to or greater than the second cross-sectional dimension;

[0011] When the m+1th cross-sectional size is equal to or greater than the preset cross-sectional size, the suction port of the negative pressure suction device stops adjusting;

[0012] After the first welding position is welded, the laser beam moves to the nth welding position, wherein m and n are natural numbers, m>1, n>1.

[0013] According to an embodiment of the present invention, the image acquisition device obtains the width, length, radius, diameter, circumference or area of ​​the cross-sectional dimensions of the keyhole.

[0014] According to an embodiment of the present invention, in the m+1th adjustment, where m>1 and m is a natural number, the adjustment is a continuous adjustment or an intermittent adjustment; the intermittent adjustment includes setting the difference in the change of the cross-sectional size of the air inlet each time the air inlet is adjusted according to the time frequency, or setting the difference in the change of the cross-sectional size of the air inlet each time the air inlet is adjusted and / or the frequency of adjusting the cross-sectional size of the air inlet according to the difference between the cross-sectional size of the keyhole and the preset cross-sectional size.

[0015] According to one embodiment of the present invention, when the temperature sensor senses that the temperature of the plasma is equal to or greater than the minimum value of the first preset temperature, the suction port of the negative pressure suction device performs the first adjustment, and when the temperature sensor senses that the temperature of the plasma is greater than the maximum value of the first preset temperature, the suction port of the negative pressure suction device stops adjusting.

[0016] According to one embodiment of the present invention, when the temperature sensor senses that the temperature of the plasma drops from the first preset temperature to a minimum value less than the first preset temperature, the air intake port of the negative pressure suction device is adjusted for the m+sth time, and the cross-sectional size of the air intake port after the m+sth adjustment is smaller than the cross-sectional size of the air intake port after the mth adjustment, wherein m and s are natural numbers, m>1, s>1.

[0017] According to one embodiment of the present invention, when the temperature sensor senses that the temperature of the plasma in the first area reaches the first preset temperature, and / or when the temperature sensor senses that the temperature of the plasma in the second area reaches the second preset temperature, the suction port of the negative pressure suction device performs the first adjustment.

[0018] According to an embodiment of the present invention, the second preset temperature is less than or equal to the first preset temperature.

[0019] According to an embodiment of the present invention, when the m+1th cross-sectional dimension is smaller than the preset cross-sectional dimension of the keyhole opening, the suction pressure of the negative pressure suction device is increased, the negative pressure suction device has a first negative pressure, and the time when the laser beam is located at the first welding position is not less than the preset time, wherein m is a natural number, and m>1.

[0020] According to one embodiment of the present invention, during the welding process, when the laser power of the laser beam attenuates, the suction pressure of the negative pressure suction device is increased, the negative pressure suction device has a second negative pressure, and the suction port of the negative pressure suction device is adjusted for the m+xth time, and the m+1th cross-sectional dimension is deformed to the m+xth cross-sectional dimension, and the m+xth cross-sectional dimension is larger than the m+1th cross-sectional dimension, wherein m and x are natural numbers, m>1, x>1.

[0021] According to one embodiment of the present invention, when the thickness of the nth welding position is greater than the thickness of the first welding position, the suction port of the negative pressure suction device is adjusted for the m+zth time, and the m+1th cross-sectional dimension is deformed to the m+zth cross-sectional dimension, and the m+zth cross-sectional dimension is equal to or greater than the m+1th cross-sectional dimension, wherein n, m and z are natural numbers, m>1, n>1, z>1.

[0022] In order to solve the problem that the porosity defects caused by laser deep penetration welding affect the quality of weld formation, the present invention has the following advantages:

[0023] 1. The present invention uses a negative pressure suction device to suck plasma to change the dynamic distribution characteristics of the plasma outside the keyhole, thereby changing the motion path and dynamic distribution of the traditional plasma elimination, and then changing the vertical upward or oblique movement mode of the plasma plume to a circular movement along the keyhole in the molten pool, which will weaken or eliminate the shielding effect of the plasma plume concentration at the keyhole mouth on the scattering and reflection of the laser energy; and the plasma plume at the keyhole mouth will be sucked outward along the circumference of the keyhole mouth by the negative pressure airflow, thereby expanding the cross-sectional size of the keyhole mouth and increasing the absorption of the incident laser energy. The present invention adjusts the plasma plume motion state, the molten pool and the keyhole according to the negative pressure airflow field, thereby realizing the control of the weld formation in laser deep melting welding, thereby improving the quality of the weld formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A welding method flow chart of an embodiment is shown. DETAILED DESCRIPTION

[0025] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0026] As used herein, the term "including" and its variants are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "based at least in part on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like is based on the orientation or position relationship shown in the accompanying drawings. These terms are mainly for better describing the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation. In addition, in addition to being used to indicate an orientation or position relationship, some of the above terms may also be used to indicate other meanings, such as the term "upper" may also be used to indicate a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances. In addition, the terms "install", "set", "provided with", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0027] This embodiment discloses a welding method, such as Figure 1 As shown, the welding method includes the following steps:

[0028] Adjust the distance between the suction port of the negative pressure suction device and the first welding position within a preset distance range;

[0029] The laser beam is directed at the first welding position in a protective gas atmosphere;

[0030] A molten pool is formed at the first welding position;

[0031] A keyhole opening for plasma escape is formed within the range of the molten pool, the intersection of the keyhole opening and the surface of the molten pool forms a first cross-sectional dimension, and a plasma suction channel is formed between the suction port of the negative pressure suction device and the keyhole opening;

[0032] When the temperature sensor on the negative pressure suction device senses that the temperature of the plasma reaches a first preset temperature, the suction port of the negative pressure suction device is adjusted for the first time, and the first cross-sectional dimension is transformed into a second cross-sectional dimension;

[0033] The suction port of the negative pressure suction device is adjusted for the mth time, and the m+1th cross-sectional dimension of the keyhole is acquired by the image acquisition device, and the m+1th cross-sectional dimension is equal to or greater than the second cross-sectional dimension;

[0034] When the m+1th cross-sectional dimension is equal to or greater than the preset cross-sectional dimension, the air inlet of the negative pressure air inhalation device stops adjusting;

[0035] After the first welding position is welded, the laser beam moves to the nth welding position, wherein m and n are natural numbers, m>1, n>1.

[0036] In this embodiment, during the welding process, the plasma is sucked by adaptively adjusting the cross-sectional size of the suction port of the negative pressure suction device. The portion where the keyhole mouth and the surface of the molten pool intersect forms a first cross-sectional size, which is the cross-sectional size of the horizontal surface of the keyhole mouth. The method of forming a plasma suction channel between the suction port of the negative pressure suction device and the keyhole mouth can effectively control the behavior of the plasma plume. The plasma is sucked by the negative pressure suction device to change the dynamic distribution characteristics of the plasma outside the keyhole, thereby changing the motion path and dynamic distribution of the traditional plasma elimination, and then changing the vertical upward or oblique movement mode of the plasma plume to the circumferential movement along the keyhole in the molten pool, which will weaken or eliminate the shielding effect of the plasma plume gathering at the keyhole mouth on the scattering and reflection of the laser energy; and the plasma plume at the keyhole mouth will be sucked outward along the circumference of the keyhole mouth by the negative pressure airflow, thereby expanding the cross-sectional size of the keyhole mouth, and at the same time, after the plasma plume is sucked, the absorption of the incident laser energy at the welding position is increased. This embodiment adjusts the feather movement state, molten pool and keyhole according to the negative pressure air flow field, thereby realizing the control of weld formation in laser deep melting welding, thereby improving the quality of weld formation. When the temperature sensor on the negative pressure suction device senses that the plasma temperature reaches the first preset temperature, it is predicted that the plasma flow rate escaping from the keyhole may be large, and the large plasma flow rate will affect the absorption of the incident laser energy and thus affect the welding work. By adjusting the suction port inlet of the negative pressure suction device, specifically by increasing the cross-sectional size of the horizontal surface of the suction port of the negative pressure suction device for sucking plasma, the cross-sectional size of the plasma suction channel is increased, that is, the suction port space for sucking and incorporating plasma is increased. By changing the direction of plasma escape under the negative pressure environment state, the plasma escaping from one side is timely escaped toward the suction port of the negative pressure suction device. The way of increasing plasma escape can reduce the generation of pores in the molten pool, and the way of timely sucking plasma can avoid the plasma gathering affecting the welding work. At the same time, the cross-sectional size of the keyhole is increased to provide a channel for the escape of bubbles, which is conducive to the overflow of bubbles and further reduces the generation of pores in the molten pool. By acquiring the cross-sectional dimensions of the keyhole through image acquisition, the cross-sectional dimensions of the keyhole can be more accurately adjusted, and the adjustment of the suction port of the negative pressure suction device and the cross-sectional dimensions of the keyhole can be coordinated to allow the plasma to escape and be quickly sucked out. When the cross-sectional dimensions of the keyhole reach the preset cross-sectional dimensions, the suction port of the negative pressure suction device is no longer adjusted. After the first welding position is welded, the laser beam moves to the next welding position to perform welding work at the next position. In this embodiment, when the plasma temperature reaches the first preset temperature by sensing, the suction port of the negative pressure suction device performs the adjustment method, and the suction port has the function of adaptive temperature adjustment, so that the plasma can be sucked out in time.

[0037] In some embodiments, in the mth adjustment, where m>1 and m is a natural number, the change in the cross-sectional size of the horizontal surface of the air inlet is consistent or inconsistent in each adjustment. When inconsistent, the change in the cross-sectional size of the horizontal surface of the air inlet is an increase or decrease.

[0038] In some instances, the cross-sectional shape of the keyhole is consistent or inconsistent with the cross-sectional shape of the horizontal surface of the air inlet. When the plasma is sucked under negative pressure, the plasma escapes toward the air inlet, and the change in the overflow direction of the plasma may change the cross-sectional shape of the keyhole to be consistent with or similar to the cross-sectional structure of the horizontal surface of the air inlet.

[0039] In some embodiments, the cross-sectional dimensions of the air inlet of the negative pressure air suction device are consistent or inconsistent according to the materials at different welding positions. For example, the cross-sectional dimensions of the air inlet at the welding position of stainless steel material are equal to or greater than the cross-sectional dimensions of the air inlet at the welding position of high-reflective material (aluminum alloy, magnesium alloy, etc.). Due to the different properties of the materials at the welding positions, the amount and morphological volume of the plasma generated during welding are different. Therefore, it is necessary to adjust the cross-sectional dimensions of the air inlet, that is, to adjust the cross-sectional dimensions of the horizontal surface of the air inlet.

[0040] In some embodiments, when the thickness of the welding positions is different, the preset spacing ranges between the suction ports of the negative pressure suction device and the welding positions of different thicknesses are different.

[0041] In some embodiments, the preset spacing ranges from 0 to 50 mm, preferably from 10 mm to 40 mm.

[0042] In some embodiments, when the laser beam passes through the air intake port and hits the welding position, the laser beam is coaxial with the air intake port. After the air intake port is adjusted for the first time, the axis position of the air intake port is inconsistent with the axis position of the laser beam.

[0043] According to an embodiment of the present invention, the image acquisition device obtains the width, length, radius, diameter, circumference or area of ​​the cross-sectional dimensions of the keyhole.

[0044] In this embodiment, at least the above-mentioned cross-sectional dimensions are provided so that keyhole openings with different cross-sectional shapes can be obtained. For example, when the cross-sectional shape of the keyhole opening is circular, the cross-sectional dimension of the keyhole opening may be one or more of the radius, diameter, circumference and area. When the cross-sectional shape of the keyhole opening is rectangular, the area is preferably used as the cross-sectional dimension of the keyhole opening.

[0045] In some embodiments, the cross-sectional shape of the horizontal surface of the suction port of the negative pressure suction device is annular, and the annular shape includes but is not limited to a circular ring, a rectangular ring, and the like.

[0046] According to an embodiment of the present invention, in the mth adjustment, where m>1 and m is a natural number, the adjustment is a continuous adjustment or an intermittent adjustment; the intermittent adjustment includes setting the difference in the change of the cross-sectional size of the air inlet each time the air inlet is adjusted according to a time frequency, or setting the difference in the change of the cross-sectional size of the air inlet each time the air inlet is adjusted and / or the frequency of adjusting the cross-sectional size of the air inlet according to the difference between the cross-sectional size of the keyhole opening and the preset cross-sectional size.

[0047] In this embodiment, a method for adjusting the air inlet of a negative pressure air suction device is provided, which facilitates precise control of the cross-sectional size of the keyhole opening.

[0048] According to one embodiment of the present invention, when the temperature sensor senses that the temperature of the plasma is equal to or greater than the minimum value of the first preset temperature, the suction port of the negative pressure suction device performs the first adjustment, and when the temperature sensor senses that the temperature of the plasma is greater than the maximum value of the first preset temperature, the suction port of the negative pressure suction device stops adjusting.

[0049] In this embodiment, the air inlet of the negative pressure air suction device needs to be adjusted in the process of plasma temperature change. The adjustment of the air inlet is performed in the process of temperature change when the plasma temperature changes from low temperature to high temperature. The air inlet starts to adjust when the plasma temperature is equal to or greater than the minimum value of the first preset temperature. When the plasma temperature is greater than the maximum value of the first preset temperature, the air inlet is no longer adjusted, that is, the air inlet of this embodiment is not adjustable infinitely. When the first preset temperature is set in this embodiment, the temperature of the case where the temperature sensor on the negative pressure air suction device directly senses that the temperature of the plasma exceeds the first preset temperature and is maximized during welding is included in the first preset temperature. And the first preset temperature is obtained by matching with the cross-sectional size of the keyhole. When the cross-sectional size of the keyhole reaches the preset cross-sectional size, even if the temperature sensor senses that the plasma temperature rises again, the air inlet is no longer adjusted.

[0050] According to one embodiment of the present invention, when the temperature sensor senses that the temperature of the plasma drops from the first preset temperature to a minimum value less than the first preset temperature, the air intake port of the negative pressure suction device performs the m+sth adjustment, and the cross-sectional size of the air intake port after the m+sth adjustment is smaller than the cross-sectional size of the air intake port after the m+1th adjustment, wherein m and s are natural numbers, m>1, s>1.

[0051] In this embodiment, the temperature sensor senses that the temperature of the plasma drops from within the first preset temperature to less than the first preset temperature when the welding position changes, such as the process of the laser beam moving from the first welding position to the second welding position, and also occurs when the laser energy of the laser beam is reduced.

[0052] According to one embodiment of the present invention, when the temperature sensor senses that the temperature of the plasma in the first area reaches the first preset temperature, and / or when the temperature sensor senses that the temperature of the plasma in the second area reaches the second preset temperature, the suction port of the negative pressure suction device performs the first adjustment.

[0053] In the present embodiment, since welding is performed in a protective gas atmosphere, the device for supplying the protective gas is maintained on one side of the welding position, so that when the protective gas is supplied, the flow direction of the protective gas changes the direction of the plasma escape flow, and the plasma flow direction is inclined to the horizontal plane. Then, the area on the inclined side of the plasma close to the air inlet of the negative pressure suction device is the first area, and the area on the inclined side of the plasma away from the air inlet of the negative pressure suction device is the second area. The first area close to the direction of the plasma flow is short in distance due to the plasma temperature transfer, so the preset temperature ranges of the two different areas are inconsistent. Therefore, when the temperature sensor senses that the plasma temperatures of the two areas reach the preset temperature range separately or simultaneously, the air inlet is adjusted for the first time.

[0054] Preferably, when the temperature sensor senses that the plasma temperature of the first region reaches within the first preset temperature, the air intake port is adjusted for the first time. Since the second region is far from the direction of the plasma flow side, the temperature sensor may not be sensitive to the plasma temperature of the second region, resulting in the air intake port being unable to make the first adjustment in time, so it is preferred to use whether the temperature sensor senses that the plasma temperature of the first region reaches within the first preset temperature as a condition for the first adjustment of the air intake port.

[0055] In some embodiments, the air intake port can be adjusted in the first area and / or the second area, that is, only the first area is adjusted, or only the second area is adjusted, or both the first area and the second area need to be adjusted, so that the air intake port can be adaptively adjusted according to the direction of plasma flow.

[0056] According to an embodiment of the present invention, the second preset temperature is less than or equal to the first preset temperature.

[0057] In this embodiment, since the second region is away from one side of the plasma flow, the second preset temperature is set to be less than or equal to the first preset temperature, so that the air intake port of the second region is adjusted to match the air intake port of the first region.

[0058] In some embodiments, the first preset temperature and the second preset temperature are 3000°C-6000°C.

[0059] According to one embodiment of the present invention, when the m+1th cross-sectional dimension is smaller than the preset cross-sectional dimension of the keyhole opening, the suction pressure of the negative pressure suction device is increased, the negative pressure suction device has a first negative pressure, and the time when the laser beam is located at the first welding position is not less than the preset time.

[0060] In this embodiment, by adjusting the air intake port and increasing the suction pressure and welding time, the welding scheme further achieves the advantages of increasing plasma escape to reduce the generation of pores in the molten pool, and timely suctioning plasma to avoid plasma aggregation affecting the welding work.

[0061] In some embodiments, the cross-sectional length of the horizontal surface of the molten pool is 0.2 mm-1 mm, the preset cross-sectional dimension is that the keyhole length is less than 0.5 mm, and the preset time is not less than 0.1 seconds.

[0062] According to one embodiment of the present invention, during the welding process, when the laser power of the laser beam attenuates, the suction pressure of the negative pressure suction device is increased, and the suction port of the negative pressure suction device is adjusted for the m+xth time, and the m+1th cross-sectional dimension is deformed to the m+xth cross-sectional dimension, and the m+xth cross-sectional dimension is larger than the m+1th cross-sectional dimension, wherein m and x are natural numbers, m>1, x>1.

[0063] In this embodiment, due to the inherent properties of the laser, the laser power will decay with the increase of continuous use time, which will cause the keyhole to be intermittently closed during the welding process. In order to keep the keyhole open at all times, it is necessary to properly adjust the negative pressure flow and the suction port in real time to regulate the plasma suction and the circumferential flow of the keyhole in the molten pool.

[0064] According to one embodiment of the present invention, when the thickness of the nth welding position is greater than the thickness of the first welding position, the suction port of the negative pressure suction device is adjusted for the m+zth time, and the m+1th cross-sectional dimension is deformed to the m+zth cross-sectional dimension, and the m+zth cross-sectional dimension is equal to or greater than the m+1th cross-sectional dimension, wherein n, m and z are natural numbers, m>1, n>1, z>1.

[0065] In this embodiment, during the welding process when the thickness at the welding position becomes thicker, due to the different thicknesses, the welding power is also different, and the generated plasma morphology is different. It is necessary to adjust the suction port of the negative pressure suction device in real time to adapt to this change and achieve a better suction effect on the plasma. Due to the change in the thickness of the welding position, the cross-sectional size of the keyhole mouth may change after adjusting the suction port.

[0066] Since the porosity defects and weld formation quality problems of laser deep penetration welding are mainly caused by the shielding of the laser by the plume plasma, the present invention expands the keyhole opening by sucking the plasma plume at the keyhole opening to provide a channel for the bubble to escape. By adjusting the suction port of the negative pressure suction device, the dynamic characteristics of the plasma can be significantly improved, and the keyhole opening and the molten pool flow along the annular direction can be regulated to further expand the keyhole opening, which is conducive to the overflow of bubbles.

[0067] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made thereto in form and detail without departing from the scope of the present disclosure.

Claims

1. A welding method, characterized in that: The steps include: Adjust the distance between the suction port of the negative pressure suction device and the first welding position within a preset distance range; The laser beam is directed at the first welding position in a protective gas atmosphere; A molten pool is formed at the first welding position; A keyhole opening for plasma escape is formed within the range of the molten pool, the intersection of the keyhole opening and the surface of the molten pool forms a first cross-sectional dimension, and a plasma suction channel is formed between the suction port of the negative pressure suction device and the keyhole opening; When the temperature sensor on the negative pressure suction device senses that the temperature of the plasma is equal to or greater than the minimum value of the first preset temperature, the suction port of the negative pressure suction device performs a first adjustment; when the temperature sensor senses that the temperature of the plasma is greater than the maximum value of the first preset temperature, the suction port of the negative pressure suction device stops adjusting, and the first cross-sectional size is deformed into a second cross-sectional size; The suction port of the negative pressure suction device is adjusted for the mth time, and the m+1th cross-sectional dimension of the keyhole is acquired by the image acquisition device, and the m+1th cross-sectional dimension is equal to or greater than the second cross-sectional dimension; When the m+1th cross-sectional size is equal to or greater than the preset cross-sectional size, the suction port of the negative pressure suction device stops adjusting; After the first welding position is welded, the laser beam moves to the nth welding position, wherein m and n are natural numbers, m>1, n>1; The adjustment of the air intake port is to adjust the cross-sectional size of the horizontal surface of the air intake port.

2. A welding method according to claim 1, characterized in that: The image acquisition device obtains the width, length, radius, diameter, circumference or area of ​​the cross-sectional dimensions of the keyhole.

3. A welding method according to claim 1, characterized in that: In the mth adjustment, where m>1 and m is a natural number, the adjustment is a continuous adjustment or an intermittent adjustment; the intermittent adjustment includes setting the difference in the change of the cross-sectional size of the air inlet each time the air inlet is adjusted according to the time frequency, or setting the difference in the change of the cross-sectional size of the air inlet each time the air inlet is adjusted and the frequency of adjusting the cross-sectional size of the air inlet according to the difference between the cross-sectional size of the keyhole and the preset cross-sectional size.

4. A welding method according to claim 1, characterized in that: When the temperature sensor senses that the temperature of the plasma drops from the first preset temperature to a minimum value less than the first preset temperature, the air intake port of the negative pressure suction device is adjusted for the m+sth time, and the cross-sectional size of the air intake port after the m+sth adjustment is smaller than the cross-sectional size of the air intake port after the mth adjustment, wherein m and s are natural numbers, m>1, s>1.

5. A welding method according to claim 1, characterized in that: When the temperature sensor senses that the temperature of the plasma in the first region reaches within the first preset temperature, and / or when the temperature sensor senses that the temperature of the plasma in the second region reaches within the second preset temperature, the suction port of the negative pressure suction device performs the first adjustment; Among them, the area of ​​the inclined side of the plasma close to the suction port of the negative pressure suction device is the first area, and the area of ​​the inclined side of the plasma away from the suction port of the negative pressure suction device is the second area.

6. A welding method according to claim 5, characterized in that: The second preset temperature is less than or equal to the first preset temperature.

7. A welding method according to claim 1, characterized in that: When the m+1th cross-sectional dimension is smaller than the preset cross-sectional dimension of the keyhole opening, the suction pressure of the negative pressure suction device is increased, the negative pressure suction device has a first negative pressure, and the time when the laser beam is located at the first welding position is not less than the preset time, wherein m is a natural number, and m>1.

8. A welding method according to claim 1, characterized in that: During the welding process, when the laser power of the laser beam attenuates, the suction pressure of the negative pressure suction device is increased, the negative pressure suction device has a second negative pressure, and the suction port of the negative pressure suction device is adjusted for the m+xth time, and the m+1th cross-sectional dimension is deformed to the m+xth cross-sectional dimension, and the m+xth cross-sectional dimension is larger than the m+1th cross-sectional dimension, wherein m and x are natural numbers, m>1, x>1.

9. A welding method according to claim 1, characterized in that: When the thickness of the nth welding position is greater than the thickness of the first welding position, the suction port of the negative pressure suction device is adjusted for the m+zth time, and the m+1th cross-sectional dimension is deformed to the m+zth cross-sectional dimension, and the m+zth cross-sectional dimension is equal to or greater than the m+1th cross-sectional dimension, wherein n, m and z are natural numbers, m>1, n>1, z>1.

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