WO2022142355A1

WO2022142355A1 - Laser welding method for polyhedral structure

Info

Publication number: WO2022142355A1
Application number: PCT/CN2021/111976
Authority: WO
Inventors: 王林; 周伟华; 周俊杰; 钟小兰
Original assignee: 广东利元亨智能装备股份有限公司
Priority date: 2020-12-30
Filing date: 2021-08-11
Publication date: 2022-07-07
Also published as: CN112828463A

Abstract

A laser welding method for a polyhedral structure. A joint of any two connected connecting surfaces to be welded of the polyhedral structure forms a seam to be welded, a plurality of sections of seams to be welded are connected to form a welded seam track, and a connecting area of two connected sections of seams to be welded is a transition welding area. The laser welding method comprises: rotating a polyhedral structure around a rotation axis when welding is conducted to a starting point of a transition welding area, and in addition, a welding head conducting corresponding follow-up movement relative to the rotation of the polyhedral structure, wherein the follow-up movement is that the welding head moves along with a movement track of the transition welding area; and the polyhedral structure stopping rotating when the welding head conducts follow-up movement to the end of the transition welding area and a seam to be welded is directly located at a horizontal position or a vertical position. In a moving process of the welding head, a laser of the welding head is continuously output. According to the laser welding method for a polyhedral structure, continuous laser-emitting welding can be achieved, and therefore the welding efficiency is improved, and the quality of a welded seam is improved.

Description

Laser welding method of polyhedral structure

technical field

The invention relates to the technical field of laser welding, in particular to a laser welding method of a polyhedron structure.

Background technique

At present, the laser welding of the polyhedral structure usually requires the polyhedron to be turned over several times, and the laser welding needs to be interrupted during the turning process. During the process, the aluminum shell battery needs to be turned over at least three times, and the laser welding operation needs to be interrupted at least three times. This kind of laser welding method makes the whole welding time longer, so the welding efficiency is lower; at the same time, because the welding head needs to turn on and off the output of the laser more frequently, a sudden change of thermal influence will be generated at the welding position, which will affect the quality of the welding seam.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a laser welding method of a polyhedron structure, so as to improve the welding efficiency and improve the quality of the welding seam.

Embodiments of the present invention provide a laser welding method for a polyhedron structure. The joint of any two adjacent to-be-welded connection surfaces of the polyhedral structure constitutes a to-be-welded gap, and multiple sections of the to-be-welded gap are connected to form a weld track, and the connection area of the two connected sections of the to-be-welded gap is transition welding. area. The laser welding method includes:

When welding to the starting point of the transition welding area, the polyhedral structure rotates around the axis of rotation, and the welding head makes a corresponding follow-up relative to the rotation of the polyhedral structure, and the follow-up is that the welding head follows the transition move according to the motion trajectory of the welding area;

When the welding head moves to the end point of the transition welding area, the to-be-welded seam to be welded is just in a horizontal position or a vertical position, and the polyhedral structure stops rotating;

Wherein, during the movement of the welding head, the laser of the welding head is continuously output.

In some embodiments of the present invention, the movement of the welding head in the transition welding region is performed in a point-by-point moving approximation, and the starting point (X _1i , Z of the i-th segment during the point-by-point moving approach) The motion trajectory between _1i , A _1i ) and the end point (X _2i , Z _2i , A _2i ) is a straight line segment, and the length of the straight line segment is:

The length of the motion trajectory of the welding head in the transition welding region is:

where i and n are both natural numbers not less than 1, and n is not less than i.

In some embodiments of the present invention, the distance between the welding head and the polyhedral structure remains constant.

In some embodiments of the present invention, the moving speed of the welding head is a constant speed.

In some embodiments of the present invention, the laser output direction of the welding head is always vertically downward.

In some embodiments of the present invention, during the process of the welding head following from the starting point of the transition welding region to the end point of the transition welding region, the laser output direction of the welding head is always perpendicular to the position where the welding point is located. section.

In some embodiments of the present invention, the movement of the welding head following the movement trajectory of the transition welding region is a compound movement, and the compound movement is the lifting movement of the welding head and the horizontal movement of the welding head synthesis of the two.

In some embodiments of the present invention, the polyhedral structure includes a first object to be welded and a second object to be welded, and the connection surfaces to be welded of the first object to be welded and the second object to be welded are connected It becomes the to-be-welded gap, and the to-be-welded gap extends along a straight line, a broken line or a curved line.

In some embodiments of the present invention, the first object to be welded is a casing body of a battery, and the second object to be welded is a top cover of the battery, the casing body of the battery and the top cover of the battery Each has four sides and two end faces. The side is the connection surface to be welded. The side of the battery case body and the side of the top cover of the battery are spliced to form a to-be-welded gap. The to-be-welded gap is processed by laser. Welds are formed after welding.

In some embodiments of the present invention, the laser welding method for welding the casing body of the battery and the top cover of the battery into one body includes:

splicing the shell body of the battery and the top cover of the battery into a target object to be welded, and the target object to be welded has a transition welding area A, a transition welding area B, a transition welding area C, and a transition welding area D, The transition welding area A connects the first gap to be welded and the second gap to be welded, the transition welding area B connects the first gap to be welded and the fourth gap to be welded, and the transition welding area C connects the first gap to be welded. Four gaps to be welded and a third gap to be welded, the transition welding area D connects the third gap to be welded and the second gap to be welded;

The welding head welds the first gap to be welded in a horizontal direction, and moves to the starting point of the transition welding area A on the first gap to be welded;

When the target object to be welded rotates counterclockwise, the welding head lifts up and moves to the left, and the relative movement between the welding head and the target object to be welded makes the welding head reach the position at the second position. At the end point of the transition welding area A on the to-be-welded gap, the second to-be-welded gap just rotates to a horizontal position and the to-be-welded target object stops rotating, so that the welding head completes the transitional welding area A. welding;

The second gap to be welded remains horizontal, and the welding head moves from the end point of the transition welding area A on the second gap to be welded to the transition welding area D located on the second gap to be welded , so as to complete the welding of the second gap to be welded along the horizontal direction;

The target object to be welded continues to rotate counterclockwise, while the welding head moves downward and to the left, and the relative movement between the welding head and the target object to be welded causes the welding head to move to the position at the position of the welding head. At the end point of the transition welding area D on the third gap to be welded, the third gap to be welded just rotates to a horizontal position and the target object to be welded stops rotating, so that the welding head completes the transition to the transition. Welding of welding area D;

The third gap to be welded is kept in a horizontal state, and the welding head is moved from the end point of the transition welding area D on the third gap to be welded to the transition welding located on the third gap to be welded the starting point of the area C, so as to complete the welding of the third gap to be welded along the horizontal direction;

The above steps are repeated to complete the welding of the transition welding region C, the fourth gap to be welded and the transition welding region B, thereby realizing continuous laser welding of the entire target object to be welded.

The technical solutions provided by the embodiments of the present invention have at least the following beneficial effects: the above-mentioned laser welding method can perform continuous laser light-emitting welding, and the welding efficiency is higher than that of the traditional welding method; in addition, the laser output is maintained continuously without causing The sudden change of welding seam temperature caused by turning off the laser output halfway avoids affecting the welding quality.

Description of drawings

Fig. 1 is the schematic diagram of the laser welding method of the existing polyhedron structure;

2 is a schematic diagram of a laser welding method for a polyhedral structure provided in an embodiment of the present invention;

3(a) to 3(d) are schematic diagrams of a series of steps of the laser welding method of the polyhedral structure provided in the embodiment of the present invention;

Fig. 4 is the state under a certain step of the laser welding method of the polyhedron structure provided in the embodiment of the present invention;

FIG. 5 is a schematic diagram of a representation form of a weld in an embodiment of the present invention;

FIG. 6 is a schematic diagram of the state of the laser head and the polyhedron structure for welding the transition welding region in the embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention. The technical solutions between the various embodiments of the present invention can be combined with each other, but should be based on the realization by those of ordinary skill in the art.

In the description of the present invention, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. are based on those shown in the accompanying drawings The orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the term "connection" should be understood in a broad sense, for example, it may be a fixed connection and a movable connection, and it may also be a detachable connection and a non-detachable connection. , or integrally connected; it may be a mechanical connection, an electrical connection or a mutual communication. And "fixed connection" includes detachable connection, non-detachable connection and integral connection.

In the present invention, terms like "first" or "second" are only used for descriptive purposes, and should not be construed as indicating or implying their relative importance or implying the number of indicated technical features.

In order to introduce the technical solutions of the embodiments of the present invention more clearly, the present application first describes the existing laser welding method of the polyhedral structure. Take the welding process of the aluminum shell battery shell and the side of the positive and negative cover plates as an example. At present, lasers are usually used in the industry to perform discontinuous light-emitting thermal fusion welding on the gap between the shell and the positive and negative cover plates. The specific steps are shown in Figure 1. (The surface to which the hatched line is attached in Figure 1 is the welding surface where the welding has been completed):

(1) Place the battery horizontally to weld the first gap: the laser welding head outputs the laser (the solid arrow on the far left facing downward indicates that the welding head descends and turns on the laser output) and moves to the right (the direction indicated by the dashed arrow is Welding direction, that is, from the position of the corner B' to the position of the corner A') for welding. After the welding is completed, turn off the laser output, lift the laser welding head to a safe height (the solid arrow pointing upward indicates that the welding head is rising), and rotate the battery 90 degrees counterclockwise.

(2). After the battery is rotated 90 degrees counterclockwise, the second stage of gap welding is performed: the welding head descends and outputs the laser (the solid arrow pointing downward indicates that the welding head descends and the laser output is turned on), follow the laser welding direction indicated by the dotted arrow ( That is, from the position of the corner A' to the position of the corner D'), move the welding head to the end of the short side, so as to complete the welding of the second section of the gap. After the second section of gap welding is completed, the laser output is turned off, and the laser welding head is raised to a safe height (the solid arrow toward the top indicates that the welding head is raised).

(3). The battery is rotated 90 degrees counterclockwise again, so that the battery is in a position turned 180 degrees, and the third stage of gap welding is carried out: after the welding head waits for the battery to be turned in place, drop to the specified height again and turn on the laser output (the downward facing Solid arrows indicate that the welding head descends and turns on the laser output). Move the welding head according to the laser welding direction indicated by the dotted arrow (that is, from the position of the corner D' to the position of the corner C'), so as to complete the welding of the third section of the gap. After the third section of gap welding is completed, the laser output is turned off, and the laser welding head is raised to a safe height (the solid arrow toward the top indicates that the welding head is raised).

(4). The battery is rotated 90 degrees counterclockwise again, so that the battery is in a position where the battery is turned 270 degrees, and the fourth stage of gap welding is performed: after the welding head waits for the battery to be turned in place, it drops to the specified height again and turns on the laser output (the downward facing Solid arrows indicate that the welding head descends and turns on the laser output). Move the welding head according to the laser welding direction indicated by the dotted arrow (that is, from the position of the corner C' to the position of the corner B'), so as to complete the welding of the fourth section of the gap. After welding is complete, turn off the laser output again.

It is not difficult to see that, according to the existing welding method shown in Figure 1, welding a battery requires welding of four gaps, at least three times of flipping, and at least three interruptions of the laser output, which results in the laser welding process not continuously emitting light. In order to avoid the collision caused by the flip of the battery, the welding head must be raised first and then dropped. The control axis of the welding head must be repeatedly accelerated and decelerated (the dotted line in the vertical direction as shown in Figure 1 indicates lifting or falling), which leads to longer welding time and lower welding efficiency. Furthermore, since the laser output needs to be turned off when the welding head is raised, and turned on again when the welding head is dropped, the thermal influence of the welding position has a sudden change, which affects the quality of the welding seam, thereby reducing the product yield.

The following text describes the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings. It should be pointed out that although the laser welding of batteries is taken as an example, it is not limited that the technical solutions of the present application are only applied to the laser welding of batteries, and other polyhedral structures can also adopt the laser welding method in the embodiments of the present invention.

Some embodiments of the present invention provide a method of laser welding of polyhedral structures. Polyhedral structures have multiple sides, where "plurality" means "at least two". The joint of any two adjacent to-be-welded connection surfaces of the polyhedral structure constitutes a to-be-welded gap, and multiple segments of to-be-welded gaps are connected to form a weld track. The laser welding method includes:

When welding to the starting point of the transition welding area, the polyhedral structure rotates around the axis of rotation, and at the same time, the welding head makes a corresponding follow-up movement relative to the rotation of the polyhedral structure, and the follow-up is that the welding head follows the movement track of the transition welding area;

When the welding head moves to the end point of the transition welding area, the to-be-welded gap to be welded is just in the horizontal or vertical position, and the polyhedral structure stops rotating;

Among them, during the movement of the welding head, the laser of the welding head is continuously output.

With reference to FIG. 2 , the above-mentioned laser welding method is described by way of example. It should be pointed out that the circles completely filled with black and the circles filled with black shadows in the drawings of the present specification are only used to distinguish the transition welding area A and the transition welding area D, and do not represent other meanings. As shown in Figure 2, the polyhedral structure includes four gaps to be welded: the first gap to be welded, the second gap to be welded, the third gap to be welded, and the fourth gap to be welded, and the four gaps to be welded also form four transition welding area. The four transition welding regions are embodied as four corners: corner A, corner B, corner C and corner D. The first gap to be welded is between corner A and corner B, the fourth gap to be welded is between corner B and corner C, the third gap to be welded is between corner C and corner D, and the gap between corner D and corner A is The second gap to be welded.

For example, one embodiment of the laser welding method may be: moving the welding head to the starting point of the corner A on the first gap to be welded;

When the polyhedral structure rotates in the counterclockwise direction, the welding head moves following the movement track of the corner A, and the laser output direction of the welding head remains unchanged downward. The motion trajectory of the corner A is a circular motion, the center of the circle where the circle is located is the rotation center of the counterclockwise rotation of the polyhedron structure, and the radius is the distance from the rotation center to the corner A.

Although the welding head follows the movement trajectory of the corner A, the corner A moves counterclockwise in the circle, and the laser output direction of the welding head remains unchanged downward, so that there is still relative motion between the welding head and the corner A. (See Figure 2). This relative movement causes the welding head to pass through the corner A from the first gap to be welded to the second gap to be welded.

When the welding head moves to the end point of the corner A, the second to-be-welded gap to be welded is in a horizontal position, and the polyhedral structure stops rotating. During the movement of the welding head, the laser of the welding head is continuously output.

It can be understood that the embodiments of the present invention can also adopt the following technical solutions: the laser output direction of the welding head remains unchanged in a horizontal direction (for example, the direction from front to back remains unchanged), when the welding head moves to the end point of the corner A , the second to-be-welded slot to be welded is just in a vertical position, and the polyhedral structure stops rotating. Then the welding head ascends or descends to weld the second to-be-welded gap extending in the vertical direction. During the whole welding process, the laser output direction of the welding head remains a fixed horizontal direction.

In other words, when the laser output direction of the welding head is the vertical direction, when the to-be-welded gap to be welded is in a horizontal position, the polyhedral structure stops rotating, and then the welding head starts to weld the to-be-welded gap; When the direction is horizontal, when the to-be-welded seam to be welded is in a vertical position, the polyhedral structure stops rotating, and then the welding head starts to weld the to-be-welded seam. It should be pointed out that "the gap to be welded is in a vertical position" and "the gap to be welded is in a horizontal position" means that the joint surface to be welded where the gap to be welded is located or the cut plane of the gap to be welded is in a vertical position or a horizontal position.

Through the above laser welding method, continuous laser light-emitting welding can be performed, and the welding efficiency is higher than the traditional welding method; in addition, the laser output is maintained continuously, which will not cause sudden changes in the temperature of the welding seam caused by turning off the laser output in the middle, so as to avoid affecting the welding. quality.

Further, in some specific embodiments, the movement of the welding head is performed in a point-by-point moving approximation manner, so that the welding head moves following the movement trajectory of the corner. The method of point-by-point moving approximation can realize curved motion trajectories such as circular motion. The motion trajectory between the starting point (X _1i , Z _1i , A _1i ) and the end point (X _2i , Z _2i , A _2i ) of the i-th segment in the point-by-point moving approximation process is a straight line segment, and the length of the straight line segment is for:

where i and n are both natural numbers not less than 1, and n is not less than i. The X-axis, Z-axis and A-axis are perpendicular to each other, the polyhedral structure can rotate around the A-axis, and the welding head can move in the X-axis and Z-axis directions. In the case where the welding seam extends along the broken line or along the curve, that is, there is a change in the coordinates of the motion trajectory of the welding head in the A-axis direction, at this time, A _1i ≠A _2i .

Using the method of point-by-point moving approximation, assuming that the two points are segmented into infinitely small distances, the three axes including the X-axis, Z-axis and A-axis can be controlled to move and weld according to the above trajectory, so that multiple Infinitely small straight line segments fit curve segment trajectories.

In some specific embodiments, the distance between the welding head and the polyhedral structure is kept constant, which can make the penetration depth of the welding seam more uniform.

In some specific embodiments, the moving speed of the welding head is uniform, which also makes the penetration depth of the welding seam more uniform, thereby improving the welding quality.

In some specific embodiments, please refer to FIG. 2 , the laser output direction of the welding head is always vertically downward. The downward laser output direction facilitates the arrangement of the welding head, making the structure of the entire laser welding device more compact.

In some specific embodiments, please refer to FIG. 6 , in the process that the welding head follows from the starting point of the transition welding area to the end point of the transition welding area, the laser output direction of the welding head is always perpendicular to the tangent plane where the welding point is located, so that the welding is formed. The penetration depth of the weld in the front, rear, left and right directions is as uniform as possible. In Figure 6, the transition welding area A and the transition welding area D are represented by bold solid lines, and other parts are distinguished by dashed lines; the solder joints are represented by black dots, and the horizontal dashed line represents the tangent plane where the solder joints are located. The downward solid arrow indicates that the laser output direction of the welding head is vertically downward.

As shown in FIG. 6 , during the welding process, the welding spot relatively moves from the starting point of the transition welding area to the end point of the transition welding area. The cutting plane where the solder joint is located is always a horizontal plane, and the laser output direction of the welding head is always perpendicular to the cutting plane where the solder joint is located.

Further, in the above-mentioned specific embodiment, please refer to FIG. 2 and FIG. 4 , the movement of the welding head following the movement trajectory of the corner is a compound movement, and the compound movement is the lifting movement of the welding head in the up-down direction and the movement of the welding head. Move the composition of the two horizontally.

In some specific embodiments, the polyhedral structure includes a joint between the to-be-welded connection surfaces of the first to-be-welded object and the second to-be-welded object to be a to-be-welded gap, and the to-be-welded gap extends along a straight line, a broken line or a curved line, wherein A polyline is formed by turning and splicing at least two adjacent straight lines. FIG. 5 shows the situation where the laser welded seam 30 extends along a curve. By means of the welding seam 30 extending along the curve, both the first object to be welded 10 and the second object to be welded 20 are welded into one body.

Further, in some specific embodiments, please refer to FIG. 2, FIG. 3(a), FIG. 3(b), FIG. 3(c), FIG. 3(d) and FIG. 4, the first object to be welded is a battery The shell body, the second object to be welded is the top cover of the battery, the shell body of the battery and the top cover of the battery have four side surfaces and two end surfaces, the side surfaces are the connection surfaces to be welded, and the shell body of the battery has four sides and two end surfaces. The side surface is spliced with the side surface of the top cover of the battery to form a to-be-welded gap, and the to-be-welded gap is laser welded to form a welded seam.

Further, in some specific embodiments, the laser welding method for welding the casing body of the battery and the top cover of the battery into one body includes:

The shell body of the battery and the top cover of the battery are spliced into the target object to be welded. The target object to be welded has a transition welding area A, a transition welding area B, a transition welding area C, and a transition welding area D. The transition welding area A is connected The first gap to be welded and the second gap to be welded, the transition welding area B connects the first gap to be welded and the fourth gap to be welded, the transition welding area C connects the fourth gap to be welded and the third gap to be welded, and the transition welding area D Connect the third gap to be welded and the second gap to be welded;

As shown in Figure 3(a), the welding head welds the first gap to be welded along the horizontal direction (for example, the horizontal direction from left to right), and moves to the starting point of the transition welding area A on the first gap to be welded;

As shown in Figure 3(b), while the target object to be welded rotates counterclockwise, the welding head lifts up and moves to the left, and the relative movement between the welding head and the target object to be welded makes the welding head reach the second gap to be welded. The end point of the transition welding area A on the above, the second to-be-welded gap just rotates to the horizontal position and the to-be-welded target object stops rotating, so that the welding head completes the welding of the transition welding area A;

As shown in Figure 3(c), the second gap to be welded remains horizontal, and the welding head moves from the end point of the transition welding area A located on the second gap to be welded to the end of the transition welding area D located on the second gap to be welded starting point, so as to complete the welding of the second gap to be welded along the horizontal direction;

As shown in Figure 3(d), the target object to be welded continues to rotate counterclockwise, while the welding head moves down and to the left, and the relative movement between the welding head and the target object to be welded makes the welding head move to the third position to be welded. At the end point of the transition welding area D on the welding gap, the third to-be-welded gap just rotates to a horizontal position and the target object to be welded stops rotating, so that the welding head completes the welding of the transitional welding area D;

The third gap to be welded remains horizontal, and the welding head moves from the end point of the transition welding region D on the third gap to be welded to the starting point of the transition welding region C on the third gap to be welded (not shown in the figure). ), thereby completing the welding of the third gap to be welded along the horizontal direction;

The foregoing steps are repeated to complete the welding of the transition welding region C, the fourth gap to be welded, and the transition welding region B, thereby realizing continuous laser welding of the entire target object to be welded.

After all the transition welding areas and all the gaps to be welded are welded, the welding seams are connected end to end to form a closed loop.

It can be understood that the laser welding method can also adopt the welding method of clockwise rotating polyhedron structure, and the direction of welding a certain gap to be welded in a horizontal state can be from left to right, from right to left, from front to back, Back to front or other horizontal directions.

In some specific embodiments, the laser output direction of the welding head is a horizontal direction. In some cases, the laser output direction of the welding head can also be the front-rear direction or the left-right direction. Correspondingly, the to-be-welded gap of the polyhedral structure should also be substantially perpendicular to the laser output direction.

Further, in the above specific embodiment, the movement of the welding head following the movement trajectory of the corner is a compound movement, and the compound movement is the movement of the welding head in the first horizontal direction and the movement of the welding head in the second horizontal direction. The combination of the two moves, wherein the first horizontal direction is perpendicular to the second horizontal direction, for example, the first horizontal direction is the left-right direction, and the second horizontal direction is the front-rear direction.

Taking the laser welding of aluminum shell batteries as an example, using the laser welding method in the embodiment of the present invention has the following beneficial effects:

(1). The gap between the shell and the cover plate of the aluminum shell battery can be continuously welded with light, and the welding efficiency is higher; in the process of welding the four sides of the gap, the laser output will not be turned off, and the welding head remains between the battery and the battery. The distance is highly constant;

(2). When the gap is continuously emitting light for welding, the laser output will continue to be maintained, and it will not cause sudden changes in the temperature of the weld caused by turning off the laser output in the middle, so as to avoid affecting the quality of the weld;

(3) Using the battery gap continuous inversion welding method in the embodiment of the present invention, the qualified rate of battery welding is improved and the quality of the produced battery is improved.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, The scope of the invention is defined by the claims and their equivalents.

Claims

The laser welding method of a polyhedral structure, the joint of any two adjacent joint surfaces to be welded of the polyhedral structure constitutes a gap to be welded, a plurality of sections of the gap to be welded are connected to form a welding seam trajectory, and the two connected sections are to be welded The connection area of the gap is a transition welding area, and it is characterized in that, the laser welding method includes:

When welding to the starting point of the transition welding area, the polyhedral structure rotates around the axis of rotation, and the welding head makes a corresponding follow-up relative to the rotation of the polyhedral structure, and the follow-up is that the welding head follows the transition move according to the motion trajectory of the welding area;

When the welding head moves to the end point of the transition welding area, the to-be-welded seam to be welded is just in a horizontal position or a vertical position, and the polyhedral structure stops rotating;

Wherein, during the movement of the welding head, the laser of the welding head is continuously output.
The laser welding method for a polyhedral structure according to claim 1, wherein the movement of the welding head in the transition welding region is performed in a point-by-point movement approximation, and the first step in the point-by-point movement approximation is performed. The motion trajectory between the starting point (X 1i , Z 1i , A 1i ) and the end point (X 2i , Z 2i , A 2i ) of segment i is a straight line segment, and the length of the straight line segment is:

The length of the motion trajectory of the welding head in the transition welding region is:
where i and n are both natural numbers not less than 1, and n is not less than i.
The laser welding method of the polyhedral structure according to claim 1, wherein the distance between the welding head and the polyhedral structure is kept constant.
The laser welding method of the polyhedral structure according to claim 1, wherein the moving speed of the welding head is a uniform speed.
The laser welding method of the polyhedral structure according to claim 1, wherein the laser output direction of the welding head is always vertically downward.
The method for laser welding of a polyhedral structure according to claim 5, wherein the laser welding head of the welding head follows the process from the starting point of the transition welding area to the end point of the transition welding area. The output direction is always perpendicular to the cut plane where the solder joint is located.
The laser welding method of the polyhedral structure according to claim 6, wherein the movement of the welding head following the movement trajectory of the transition welding region is a compound movement, and the compound movement is the lifting and lowering of the welding head The combination of movement and horizontal movement of the welding head.
The laser welding method for a polyhedral structure according to any one of claims 1 to 7, wherein the polyhedral structure comprises a first object to be welded and a second object to be welded, the first object to be welded and all the objects to be welded The connection between the to-be-welded connection surfaces of the second to-be-welded objects becomes a to-be-welded gap, and the to-be-welded gap extends along a straight line, a broken line or a curved line.
The method for laser welding of a polyhedral structure according to claim 8, wherein the first object to be welded is a casing body of a battery, the second object to be welded is a top cover of the battery, and the shell of the battery Both the body and the top cover of the battery have four side surfaces and two end surfaces, the side surfaces are the connection surfaces to be welded, and the side surfaces of the battery case body and the top cover of the battery are spliced to form the side surfaces to be welded. The gap to be welded is laser welded to form a welded seam.
The laser welding method of the polyhedral structure according to claim 9, wherein the laser welding method for welding the casing body of the battery and the top cover of the battery into one body comprises:

splicing the shell body of the battery and the top cover of the battery into a target object to be welded, and the target object to be welded has a transition welding area A, a transition welding area B, a transition welding area C, and a transition welding area D, The transition welding area A connects the first gap to be welded and the second gap to be welded, the transition welding area B connects the first gap to be welded and the fourth gap to be welded, and the transition welding area C connects the first gap to be welded. Four to-be-welded gaps and a third to-be-welded gap, and the transition welding area D connects the third to-be-welded gap and the second to-be-welded gap;

The welding head welds the first gap to be welded along the horizontal direction, and moves to the starting point of the transition welding area A on the first gap to be welded;

While the target object to be welded rotates counterclockwise, the welding head lifts up and moves to the left, and the relative movement between the welding head and the target object to be welded makes the welding head reach the fourth position. At the end point of the transition welding area A on the to-be-welded gap, the fourth to-be-welded gap just rotates to a horizontal position and the to-be-welded target object stops rotating, so that the welding head completes the transitional welding area A. welding;

The fourth gap to be welded remains horizontal, and the welding head moves from the end point of the transition welding area A on the fourth gap to be welded to the transition welding area D located on the fourth gap to be welded , so as to complete the welding of the fourth gap to be welded along the horizontal direction;

The target object to be welded continues to rotate counterclockwise, while the welding head moves downward and to the left, and the relative movement between the welding head and the target object to be welded causes the welding head to move to the position at the position of the welding head. At the end point of the transition welding area D on the third gap to be welded, the third gap to be welded just rotates to a horizontal position and the target object to be welded stops rotating, so that the welding head completes the transition to the transition Welding of welding area D;

The third gap to be welded is kept in a horizontal state, and the welding head is moved from the end point of the transition welding area D on the third gap to be welded to the transition welding located on the third gap to be welded the starting point of the region C, so as to complete the welding of the third gap to be welded along the horizontal direction;

The foregoing steps are repeated to complete the welding of the transition welding region C, the second gap to be welded, and the transition welding region B, thereby realizing continuous laser welding of the entire target object to be welded.