A square battery sealing rotary welding method and system

Abstract

The present invention relates to the field of battery manufacturing technology, and discloses a square battery sealing rotary welding method and system. The square battery sealing rotary welding method disclosed by the present invention controls the welding head to perform an R-angle welding after completing the welding of a straight edge during the battery rotation process, and controls the defocus amount during the R-angle welding to be consistent with the defocus amount during the straight edge welding, thereby ensuring the welding reliability of the R-angle position, and solving the problem of R-angle position cold welding or poor sealing caused by sudden change of defocus amount and unstable R-angle molten pool during R-angle welding in the prior art; in addition, during the straight edge welding process, the welding of the lead-in section and the lead-out section each performs a single welding on the R-angle position, so that the R-angle position can be welded multiple times, further preventing the R-angle position from being cold welded.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular to a square battery sealing rotary welding method and system. Background Art

[0002] In the manufacturing process of prismatic batteries, the sealing welding of the shell and cover is a critical step in the battery production process. The quality of the weld determines the battery's sealing performance and safety. One of the commonly used welding methods for prismatic batteries is shell cover side seam welding, which refers to the weld performed at the connection between the shell cover and the shell. The welding path consists of four straight edges and four rounded corners on the shell cover side seam. During welding, the four straight edges on the shell cover side seam are welded separately using a laser. After welding each straight edge, the battery needs to be rotated 90 degrees to weld the next straight edge. During laser welding of the four straight edges, the laser advances and lags 2-5mm to the outside of the rounded corner to ensure the rounded corner is wrapped. When welding the rounded corner, the defocus is in a sudden state compared to the defocus when welding the straight edges. The defocus fluctuates greatly, resulting in unstable molten pool formation at the rounded corner, which in turn leads to frequent problems such as cold welds or poor sealing at the rounded corner. This results in a low welding yield of battery products, resulting in a large number of battery scrap and economic losses. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a square battery sealing rotary welding method and system, which can solve the problem of sudden change in defocusing amount and unstable R corner molten pool when welding R corner in the existing technology, resulting in R corner position cold welding or poor sealing.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] On one hand, the present invention provides a square battery sealing rotary welding method for sealing and welding a battery shell and a cover plate, and the square battery sealing rotary welding method comprises: step 1, obtaining a straight edge welding path corresponding to a current straight edge, and controlling a welding head to move along the straight edge welding path to weld the current straight edge; step 2, selecting an R angle between the current straight edge and the next straight edge as a target R angle, obtaining an R angle welding path corresponding to the target R angle, controlling the battery to rotate and controlling the welding head to move along the R angle welding path to weld the target R angle during the battery rotation process, and the defocus amount during the target R angle welding is the same as the defocus amount during the straight edge welding. The amount of focus remains consistent; repeat steps one and two until the welding of four straight edges is completed; the straight edge welding path includes a straight edge welding section, a lead-in section and a lead-out section, the straight edge welding section starts at the R-angle turning point of one end of the current straight edge and ends at the R-angle turning point of the other end of the current straight edge, the lead-in section ends at the starting point of the straight edge welding section and extends a first set distance from the starting point of the straight edge welding section in a direction away from the straight edge welding section as the starting point of the lead-in section, and the lead-out section starts at the end point of the straight edge welding section and extends a second set distance from the end point of the straight edge welding section in a direction away from the straight edge welding section as the end point of the lead-out section.

[0006] Preferably, the controlling the welding head to move along the straight edge welding path to weld the current straight edge includes: controlling the welding head to accelerate to a first speed in the introduction section, controlling the welding head to emit laser and controlling the laser power to increase linearly from the first power to the set power; controlling the welding head to weld along the straight edge welding section at a first speed and a set power; controlling the welding head to decelerate to zero in the lead-out section, controlling the laser power of the welding head to decrease linearly from the set power to the first power and controlling the welding head to stop emitting light.

[0007] Preferably, the length of the lead-in section is 3-6 mm; and / or the length of the lead-out section is 3-6 mm.

[0008] Preferably, the first speed is 100-300 mm / s.

[0009] Preferably, step 2 further includes: selecting the R angle between the current straight edge and the next straight edge as the target R angle, and obtaining the R angle welding path corresponding to the target R angle; controlling the battery to rotate and controlling the welding head to move above one end of the target R angle during the battery rotation; controlling the welding head to emit laser and controlling the laser power to increase to a second power; controlling the battery to continue rotating, and at the same time controlling the welding head to move along the R angle welding path at the second power to weld the target R angle until the welding head moves above the other end of the target R angle, controlling the welding head to stop emitting light, and automatically matching the welding height during the target R angle welding to keep the defocus amount consistent with the defocus amount during straight edge welding.

[0010] Preferably, the battery's rotational angular velocity ω is in the range of 250-480° / s.

[0011] Preferably, the second power is 40-80% of the set power.

[0012] Preferably, before step one, the method further includes controlling a feeding and retrieving robot to clamp the battery and deliver it to a positioning cavity of a welding station; controlling a cylinder to clamp the battery; and obtaining a signal indicating that the battery has entered the positioning cavity.

[0013] On the other hand, the present invention provides a square battery sealing rotary welding system, which can use the above-mentioned square battery sealing rotary welding method to seal and weld the battery shell and the cover plate. The square battery sealing rotary welding system includes: a welding head for emitting laser; an X-axis for driving the welding head to move along the X-axis direction; a Y-axis for driving the welding head to move along the Y-axis direction; a Z-axis for driving the welding head to move along the Z-axis direction; an R-axis for driving the battery to rotate; and a control module for controlling the welding head, X-axis, Y-axis, Z-axis, and R-axis.

[0014] Preferably, the square battery sealing rotary welding system also includes a feeding and retrieving robot, a cylinder and an in-place detection module. The feeding and retrieving robot clamps the battery and delivers the battery to the welding station positioning cavity. The cylinder is used to clamp the battery. The in-place detection module is used to output an in-place signal when the battery enters the positioning cavity. The control module is used to control the feeding and retrieving robot and the cylinder and to obtain the in-place signal.

[0015] The beneficial technical effect of the present invention is that: the above-mentioned square battery sealing rotary welding method and system, after completing the welding of a straight edge, controls the welding head to perform an R-corner welding during the rotation of the battery, and controls the defocus amount during the R-corner welding to be consistent with the defocus amount during the straight edge welding, thereby ensuring the welding reliability of the R-corner position, and solving the problem of R-corner position cold welding or poor sealing caused by sudden change of defocus amount and unstable R-corner molten pool when welding the R corner in the prior art; in addition, during the straight edge welding process, the welding of the lead-in section and the lead-out section each performs one welding on the R-corner position, so that the R-corner position can be welded multiple times, further preventing the R-corner position from being cold welded. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of a process for rotating welding a square battery seal according to an embodiment of the present invention;

[0017] Figure 2 Schematic diagram of a straight edge welding process in one embodiment of the present invention;

[0018] Figure 3 Schematic diagram of speed variation during straight edge welding in one embodiment of the present invention;

[0019] Figure 4 Schematic diagram of power variation during straight edge welding in one embodiment of the present invention;

[0020] Figure 5a A schematic diagram of a state during R fillet welding in one embodiment of the present invention;

[0021] Figure 5b Schematic diagram of state 2 during R fillet welding in one embodiment of the present invention;

[0022] Figure 5c Schematic diagram of state 3 during R fillet welding in one embodiment of the present invention;

[0023] Figure 5d Schematic diagram of state 4 during R fillet welding in one embodiment of the present invention;

[0024] Figure 6 Schematic diagram of power variation during R-fillet welding in one embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the process of a square battery sealing rotary welding method in another embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to more clearly understand the objectives, technical solutions and advantages of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0027] The present invention provides a square battery sealing rotary welding method and a square battery sealing rotary welding system, wherein the square battery sealing rotary welding method realizes the sealing welding of the battery shell and the cover plate through the square battery sealing rotary welding system. The square battery sealing rotary welding system includes a welding head, an X-axis, a Y-axis, a Z-axis, an R-axis, and a control module. The welding head is used to emit laser light, the X-axis is used to drive the welding head to move along the X-axis direction, the Y-axis is used to drive the welding head to move along the Y-axis direction, the Z-axis is used to drive the welding head to move along the Z-axis direction, and the R-axis is used to drive the battery to rotate. The control module is used to control the welding head, the X-axis, the Y-axis, the Z-axis, and the R-axis.

[0028] like Figure 1 As shown, in one embodiment of the present invention, the square battery sealing rotation welding method includes steps S10 to S30:

[0029] S10, obtaining a straight edge welding path corresponding to the current straight edge, and controlling the welding head to move along the straight edge welding path to weld the current straight edge.

[0030] The welding path is the weld at the connection between the housing and the cover plate. It includes a straight edge welding path and an R-shaped fillet welding path. The welding paths can be pre-stored in the memory of the control module (a PLC controller in this embodiment) and retrieved by accessing data from the control module's memory. When welding a straight edge, the corresponding straight edge welding path can be retrieved by accessing data from the control module's memory.

[0031] like Figure 2 As shown, the straight edge welding path corresponding to the current straight edge obtained includes a straight edge welding section S1, an introduction section S0, and an outgoing section S2. The straight edge welding section S1 starts at the R angle turning point of one end of the current straight edge (the tangent point of the R angle of one end of the straight edge and the straight edge) X2 and ends at the R angle turning point of the other end of the current straight edge (the tangent point of the R angle of the other end of the straight edge and the straight edge) X3. The introduction section S0 ends at the starting point X2 of the straight edge welding section S1 and extends from the starting point X2 of the straight edge welding section S1 in a direction away from the straight edge welding section S1 by a first set distance (at X1) as the starting point of the introduction section S0. The outgoing section S2 starts at the end point X3 of the straight edge welding section S1 and extends from the end point X3 of the straight edge welding section S1 in a direction away from the straight edge welding section S1 by a second set distance (at X4) as the end point of the outgoing section S2. The length D1 of the lead-in section S0 is 3-6 mm, for example, 5 mm; the length D2 of the lead-out section S2 is 3-6 mm, for example, 5 mm.

[0032] Controlling the welding head to move along the straight edge welding path to weld the current straight edge can be achieved through steps S11 to S13:

[0033] S11, controlling the welding head to accelerate to a first speed in the introduction section, controlling the welding head to emit laser and controlling the laser power to increase linearly from the first power to the set power.

[0034] This step is mainly used for the welding of the introduction section S0: the control module first controls the Z axis to drive the welding head 100 to descend, and at the same time controls the X axis to drive the welding head 100 to move to the welding starting point (i.e., X1); then controls the X axis to start acceleration, and at the same time, controls the welding head 100 to start emitting laser 101, and the laser power increases linearly from the first power P1 to the set power P2, and P1 can be any value from 0 to P2; when the X axis drives the welding head 100 to move to X2, the X axis acceleration is completed, the welding speed is V1 (i.e., the first speed), the range of V1 is 100-300 mm / s, and the laser power reaches the set power P2.

[0035] S12, controlling the welding head to weld along the straight edge welding section at a first speed and a set power.

[0036] After the welding of the lead-in section S0 is completed, the welding of the straight edge welding section S1 is started: the control module controls the welding head 100 to maintain the set power P2 and welding speed V1, and welds from X2 to X3.

[0037] S13, controlling the welding head to decelerate to zero in the lead-out section, controlling the laser power of the welding head to linearly decrease from the set power to the first power, and controlling the welding head to stop emitting light.

[0038] When the welding head 100 moves to position X3, the welding of the lead-out section S2 begins: the control module controls the X-axis to start decelerating and controls the welding head 100 to start reducing power. When the welding head 100 moves to position X4, the welding speed is decelerated to zero, and the laser power of the welding head 100 is linearly reduced from the set power P2 to the first power P1. Finally, the welding head 100 is turned off and the welding head 100 stops emitting light. At this point, the current straight edge welding is completed. The speed change and power change process of the straight edge welding process are as follows: Figure 3 、 Figure 4 shown.

[0039] S20. Select the R angle between the current straight edge and the next straight edge as the target R angle, obtain the R angle welding path corresponding to the target R angle, control the rotation of the battery and control the welding head to move along the R angle welding path to weld the target R angle during the rotation of the battery, and keep the defocus amount during the target R angle welding consistent with the defocus amount during the straight edge welding.

[0040] After completing the welding of a current straight edge, the R angle welding between the current straight edge and the next straight edge can be performed without resetting the welding head 100. The R angle welding between the current straight edge and the next straight edge can be achieved through steps S21 to S24:

[0041] S21. Select the R angle between the current straight edge and the next straight edge as the target R angle, and obtain the R angle welding path corresponding to the target R angle.

[0042] After the target R angle is determined, the R angle welding path corresponding to the target R angle is obtained by retrieving data from the memory of the control module.

[0043] S22, controlling the battery to rotate and controlling the welding head to move above one end of the target R angle during the battery rotation process.

[0044] When the straight edge welding is completed, the welding head 100 moves to the relative position Y1 with the battery, as shown in FIG. Figure 5a As shown. Figure 5bThe four axes of X, Y, Z, and R are linked, wherein the R axis drives the battery to rotate around its center point, and its rotation angular velocity ω ranges from 250 to 480° / s; the X, Y, and Z axes drive the welding head 100 to move. When the welding head 100 moves to above one end of the target R angle (at Y2), the welding height of the welding head 100 is consistent with the welding height during straight edge welding.

[0045] S23, controlling the welding head to emit laser and controlling the laser power to increase to a second power.

[0046] When the welding head 100 moves to position Y2, the control module controls the welding head 100 to start emitting the laser 101 and controls the laser power to be quickly increased to the second power P3.

[0047] S24, controlling the battery to continue rotating, and at the same time controlling the welding head to move along the R-angle welding path at a second power to weld the target R-angle, until the welding head moves above the other end of the target R-angle, controlling the welding head to stop emitting light, and automatically matching the welding height when welding the target R-angle, so that the defocus amount is consistent with the defocus amount during straight edge welding.

[0048] like Figure 5b ,like Figure 5c As shown, when the welding head 100 moves to position Y2, the welding of the target R angle begins: the control module controls the R axis to continue to drive the battery to rotate at an angular velocity ω, and at the same time controls the welding head 100 to weld the target R angle along the R angle welding path (Y2-Y3) at a second power P3, until the welding head 100 moves to above the other end of the target R angle (position Y3), and then controls the welding head 100 to stop emitting light. In particular, when welding the target R angle, the welding height (the distance between the welding head and the battery) is automatically matched by controlling the four axes of X, Y, Z, and R to keep the defocus amount consistent with the defocus amount during straight edge welding; the second power P3 is obtained through a power gradient verification test, and the second power P3 is 40-80% of the set power P2.

[0049] like Figure 5d As shown, after the welding head 100 stops emitting light, it continues to control the R axis to drive the battery to rotate until the battery rotates 90°. At the same time, it continues to control the X axis, Y axis, and Z axis to drive the welding head 100 to move to Y4, and the target R corner welding is completed.

[0050] Assuming that the total rotation time of the welding head and battery relative motion is T, T2~T3 is the time period of light emission, T2 accounts for 30%~50% of the total time T, and T3 accounts for 60%~80% of the total time T, the power change of the target R fillet welding process is as follows: Figure 6 shown.

[0051] S30, repeat steps S10-S20 until the four straight edges are welded.

[0052] When the welding of the fourth straight edge is completed, the entire welding process is completed. The welding of the R angle between the fourth straight edge and the first straight edge is completed by the lead-in section welding part in the welding process of the first straight edge and the lead-out section welding part in the welding process of the fourth straight edge. There is no need to use step S20 to rotate the R angle between the fourth straight edge and the first straight edge.

[0053] The rotary welding method for sealing a rectangular battery in an embodiment of the present invention controls the welding head to perform an R-corner weld after welding one straight edge during battery rotation. The defocus during the R-corner weld is controlled to be consistent with the defocus during straight-edge welding, thereby ensuring the welding reliability of the R-corner position. This solves the problem of sudden defocus changes and unstable R-corner molten pools during R-corner welding in the prior art, which can cause R-corner weld defects or poor sealing. In addition, during the straight-edge welding process, the lead-in and lead-out sections each perform a single weld on the R-corner position, allowing the R-corner position to be welded multiple times, further preventing R-corner weld defects.

[0054] In some preferred embodiments of the present invention, the square battery sealing rotary welding system includes a welding head, an X-axis, a Y-axis, a Z-axis, an R-axis, a control module, a feeding and retrieving robot, a cylinder and an in-place detection module, the welding head is used to emit laser, the X-axis is used to drive the welding head to move along the X-axis direction, the Y-axis is used to drive the welding head to move along the Y-axis direction, the Z-axis is used to drive the welding head to move along the Z-axis direction, the R-axis is used to drive the battery to rotate, the control module is used to control the welding head, X-axis, Y-axis, Z-axis and R-axis; the feeding and retrieving robot clamps the battery and sends the battery to the welding station positioning cavity, the cylinder is used to clamp the battery, the in-place detection module is used to output an in-place signal when the battery enters the positioning cavity, the control module is used to control the feeding and retrieving robot and the cylinder and to obtain the in-place signal. Figure 7 As shown, based on the above-mentioned square battery sealing rotary welding system, a square battery sealing rotary welding method provided in another embodiment of the present invention includes steps S01 to S30, wherein steps S10 to S30 in this embodiment are the same as those in the embodiment of the present invention. Figure 1 Steps S10 to S30 in the illustrated embodiment are the same and will not be described again here.

[0055] The square battery sealing rotation welding method in this embodiment is similar to Figure 1 The difference of the square battery sealing rotary welding method in the embodiment shown is that it also includes steps S01 to S03 before step S10:

[0056] S01. Control the feeding and retrieving robot to pick up the battery and deliver it to the welding station positioning cavity. The control module controls the feeding and retrieving robot to pick up the battery and deliver it to the welding station positioning cavity and maintain the position.

[0057] S02. Control the cylinder to clamp the battery. After the battery is placed in the positioning cavity of the welding station, the control module controls the cylinder to clamp the battery.

[0058] S03. Obtaining a signal indicating that the battery has entered the positioning cavity. The welding station positioning cavity is provided with a position detection module. When a battery is placed in the welding station positioning cavity, the position detection module outputs a position signal to the control module. After the control module obtains the position signal, welding can be performed.

[0059] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Those skilled in the art may make various equivalent changes and improvements based on the above embodiment. Any equivalent changes or modifications made within the scope of the claims shall fall within the scope of protection of the present invention.

Claims

1. A square battery sealing rotary welding method for sealing and welding the battery shell and the cover plate, characterized in that: The square battery sealing rotary welding method comprises: S10, obtaining a straight edge welding path corresponding to the current straight edge, and controlling the welding head to move along the straight edge welding path to weld the current straight edge; S20, selecting the R angle between the current straight edge and the next straight edge as the target R angle, obtaining an R angle welding path corresponding to the target R angle, controlling the battery to rotate and controlling the welding head to move along the R angle welding path during the battery rotation to weld the target R angle, and maintaining the defocus amount during the target R angle welding consistent with the defocus amount during the straight edge welding; Repeat steps S10-S20 until the four straight edges are welded; The straight edge welding path includes a straight edge welding section, a lead-in section, and a lead-out section. The straight edge welding section starts at the R-angle turning point at one end of the current straight edge and ends at the R-angle turning point at the other end of the current straight edge. The lead-in section ends at the starting point of the straight edge welding section and extends from the starting point of the straight edge welding section in a direction away from the straight edge welding section by a first set distance as the starting point of the lead-in section. The lead-out section starts at the end point of the straight edge welding section and extends from the end point of the straight edge welding section in a direction away from the straight edge welding section by a second set distance as the end point of the lead-out section. The controlling the welding head to move along the straight edge welding path to weld the current straight edge includes: S11, controlling the welding head to accelerate to a first speed in the introduction section, controlling the welding head to emit laser light, and controlling the laser power to linearly increase from the first power to the set power; S12, controlling the welding head to weld along the straight edge welding section at a first speed and a set power; S13, controlling the welding head to decelerate to zero in the lead-out section, controlling the laser power of the welding head to linearly decrease from the set power to the first power, and controlling the welding head to stop emitting light; The step S20 further includes: S21, selecting the R angle between the current straight edge and the next straight edge as the target R angle, and obtaining the R angle welding path corresponding to the target R angle; S22, controlling the battery to rotate and controlling the welding head to move above one end of the target R angle during the battery rotation; S23, controlling the welding head to emit laser and controlling the laser power to increase to a second power; S24, controlling the battery to continue rotating, and at the same time controlling the welding head to move along the R-angle welding path at a second power to weld the target R-angle, until the welding head moves above the other end of the target R-angle, controlling the welding head to stop emitting light, and automatically matching the welding height when welding the target R-angle, so that the defocus amount is consistent with the defocus amount during straight edge welding.

2. The square battery sealing rotary welding method according to claim 1, characterized in that: The length of the lead-in section is 3-6 mm; and / or the length of the lead-out section is 3-6 mm.

3. The square battery sealing rotary welding method according to claim 1, characterized in that: The first speed is 100-300 mm / s.

4. The square battery sealing rotary welding method according to claim 1, characterized in that: The battery rotates at an angular velocity ω ranging from 250 to 480° / s.

5. The square battery sealing rotary welding method according to claim 1, characterized in that: The second power is 40-80% of the set power.

6. The square battery sealing rotary welding method according to any one of claims 1 to 5, characterized in that: Before step S10, the following steps are also included: S01, control the feeding and retrieving robot to pick up the battery and send it to the positioning cavity of the welding station; S02, controlling the cylinder to clamp the battery; S03: Acquire a signal indicating that the battery has entered the positioning cavity.

7. A square battery sealing rotary welding system, characterized in that: The battery shell and the cover plate can be sealed and welded using the square battery sealing rotary welding method according to any one of claims 1 to 6. The square battery sealing rotary welding system comprises: Welding head, used for emitting laser; X-axis, used to drive the welding head to move along the X-axis direction; Y-axis, used to drive the welding head to move along the Y-axis direction; A Z-axis, used to drive the welding head to move along the Z-axis direction; R-axis, used to drive the battery to rotate; The control module is used to control the welding head, X-axis, Y-axis, Z-axis and R-axis.

8. The square battery sealing rotary welding system according to claim 7, characterized in that: The square battery sealing rotary welding system also includes a feeding and retrieving robot, a cylinder and an in-place detection module. The feeding and retrieving robot clamps the battery and delivers the battery to the welding station positioning cavity. The cylinder is used to clamp the battery. The in-place detection module is used to output an in-place signal when the battery enters the positioning cavity. The control module is used to control the feeding and retrieving robot and the cylinder and to obtain the in-place signal.

Images