A method for smoothing the angle of welding torch for main shield corrugated plate of enclosure system

Abstract

The present invention relates to a method for smoothing the angle of a welding gun for the main shielding corrugated plate of an enclosure system, and belongs to the field of welding control technology. The technical solution is: a straight transition section C1-1 and a straight transition section C1-2 are set at the two ends of the straight section C1 at the bottom of the corrugated plate, close to the bottom corrugated section C2 and C6, and the welding gun angle R in the trajectory of the straight transition section C1-1, the bottom corrugated section C2, the middle corrugated section C3, the top corrugated section C4, the middle corrugated section C5, the bottom corrugated section C6, and the straight transition section C1-2 is smoothed, and the remaining trajectory parts are not smoothed. The positive effects of the present invention: the operation process is simple, and the mechanical jitter of the welding gun rotation mechanism caused by the sudden change of the welding gun angular velocity can be solved by only setting parameters such as the smoothing level, the length of the transition section, and the sampling time interval, thereby improving the quality of welding operations and the product qualification rate, and increasing the service life of the equipment mechanical structure.

Description

Technical Field

[0001] The present invention relates to a method for smoothing the angle of a welding torch for a main shield corrugated plate of an enclosure system, in particular to a method for smoothing the angle of a welding torch for a main shield corrugated plate of a Mark III film-type cargo enclosure system, and belongs to the technical field of welding control. Background Art

[0002] LNG transport vessels and LNG bunkering vessels are one of the primary methods of transporting natural gas. The MARK III membrane cargo containment system is a key component of the membrane-type LNG carrier's cargo tanks. It consists primarily of a primary shield, a secondary shield, and a thermal insulation layer. The primary shield is constructed from 1.2mm thick stainless steel corrugated sheets welded together. Due to the complex structure of the corrugated sheets, the welding mechanism must strictly follow the corrugated sheet's trajectory to meet welding process requirements, making welding control particularly important.

[0003] Mark Ⅲ membrane type cargo containment system main shield corrugated plate Figure 1 As shown, the corrugated plate consists of the bottom straight segment C1, the bottom corrugated segment C2, the middle corrugated segment C3, the top corrugated segment C4, the middle corrugated segment C5, and the bottom corrugated segment C6. During welding, the welding gun's motion trajectory is a combination of movement in the X and Y directions, and the welding gun angle R is adjusted by the welding gun rotation mechanism. The welding gun's motion trajectory consists of the bottom straight segment C1, the bottom corrugated segment C2, the middle corrugated segment C3, the top corrugated segment C4, the middle corrugated segment C5, and the bottom corrugated segment C6.

[0004] During welding, when the corrugated plate transitions between the straight line segment C1 and the bottom corrugated segment C2, between C6 and the straight line segment C1, and between corrugated segments of different radii, the welding speed will change suddenly due to the difference in welding speed and the sudden change in weld angle. The theoretical value of the welding gun angle R and the angular velocity curve are shown in the figure. Figure 2 、 Figure 3 shown.

[0005] This shows that the theoretical speed of change of the welding gun angle R is a step change at different sections of the corrugated plate. This sudden change in speed can cause mechanical vibration in the welding gun rotation mechanism, affecting welding quality and even shortening the service life of the mechanical structure. Therefore, the change curve of the welding gun angle R needs to be smoothed to ensure stable welding gun angle adjustment and reliable and stable welding quality.

[0006] A search of prior art literature and patents revealed that Chinese invention patent application number CN201910238209.4 proposes a corner transition path and determination method. The composite path formed by the transition path and the straight segment path has continuous tangents and curvature at the junction point. This ensures that when the end effector traverses the composite path at a constant speed, the speed and acceleration remain continuous throughout the entire process, which helps reduce vibration and wear and increase the robot's service life. Chinese invention patent application number CN201810716469.3 proposes a method, apparatus, and storage medium for local smooth transitions between trajectories. This method performs a local smooth transition between the first and second straight trajectories and generates a transition curve, enabling the control system to smoothly control the end effector without sudden changes in feed direction, resulting in a smoother motion process. However, this invention patent only smoothes the inflection points when the travel trajectory is straight. This addresses the problem of sudden changes in the motor shaft speed involved in travel control and does not address the mechanical jitter caused by sudden changes in the welding gun angle during corrugated sheet welding. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for smoothing the welding gun angle of the main shielding corrugated plate of the enclosure system. By setting a welding gun angle R smoothing algorithm, the mechanical jitter of the welding gun rotation mechanism caused by the sudden change of the welding gun angle R is eliminated, the welding operation quality and product qualification rate are improved, the service life of the mechanical structure of the equipment is increased, and the above-mentioned technical problems existing in the existing technology are solved.

[0008] The technical solution of the present invention is:

[0009] A method for smoothing the welding torch angle of the main shield corrugated plate of an enclosure system is disclosed. The welding torch motion trajectory consists of a bottom straight segment C1, a bottom corrugated segment C2, a middle corrugated segment C3, a top corrugated segment C4, a middle corrugated segment C5, and a bottom corrugated segment C6 of the corrugated plate. During welding, the welding torch motion trajectory is a synthesis of motions in the X and Y directions, and the welding torch angle R is adjusted by a welding torch rotation mechanism. The method is unique in that a straight transition segment C1-1 and a straight transition segment C1-2 are set at both ends of the bottom straight segment C1 of the corrugated plate near the bottom corrugated segments C2 and C6, and the welding torch angle R in the trajectory of the straight transition segment C1-1, the bottom corrugated segment C2, the middle corrugated segment C3, the top corrugated segment C4, the middle corrugated segment C5, the bottom corrugated segment C6, and the straight transition segment C1-2 is smoothed, while the remaining trajectory portions are not smoothed.

[0010] The smoothing process adopts the following method:

[0011] The theoretical value of the welding gun angle R is sampled at a fixed time interval ΔT, and is set as 、 、 … For any three consecutive sampling points 、 、 ( ) is formed by the broken line segment, take and The midpoint of and The midpoint of the two midpoints, and then take the midpoint ,by Replace the original , complete the smoothing process of the welding gun angle Ri once; and so on, set j as the smoothing level, iterate the welding gun angle Ri j times, that is, perform j smoothing processes on the welding gun angle Ri, and after j iterations, the welding gun angle Ri Calculated according to formula (1): (1) Among them is the number of location sampling points, .

[0012] The time interval ΔT is 10ms-50ms, and the smoothing level j ranges from 10-50.

[0013] An angle Δθ is set between the vertical direction of the tangent of the welding gun movement trajectory and the central axis of the welding gun, and Δθ is 0-10°.

[0014] The length of the straight transition section C1-1 is 0-5 mm, and the length of the straight transition section C1-2 is 0-5 mm.

[0015] The maximum value of the welding gun angle R is ±60°, and when it exceeds ±60°, it remains unchanged.

[0016] The positive effects of the present invention are as follows: the operation process is simple, and the mechanical jitter of the welding gun rotation mechanism caused by the sudden change of the welding gun angular velocity can be solved by only setting parameters such as the smoothing level, the transition section length, and the sampling time interval, thereby improving the welding operation quality and the product qualification rate, and increasing the service life of the equipment mechanical structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the primary shield corrugated sheet of the Mark III membrane-type cargo containment system;

[0018] Figure 2 is the theoretical value (°)-time (s) curve of welding gun angle R;

[0019] Figure 3 is the theoretical angular velocity (° / s)-time (s) curve of the welding gun angle R;

[0020] Figure 4 This is the motion trajectory of the welding torch for the main shield corrugated plate of the enclosure system according to an embodiment of the present invention;

[0021] Figure 5 is the welding gun angle Ri effect after j iterations in the embodiment of the present invention;

[0022] Figure 6 1 is a comparison of the welding gun angle R value (°)-time (s) curves of the first embodiment of the present invention without smoothing and when j=20;

[0023] Figure 7 1 is a comparison of the angular velocity (° / s)-time (s) curves of the welding gun angle R without smoothing and when j=20 in Example 1 of the present invention;

[0024] Figure 8 This is a diagram showing the welding effect of the corrugated plate when the smoothing process is not performed in the first embodiment of the present invention;

[0025] Figure 9 This is a diagram showing the welding effect of a corrugated plate when the smoothness level j=20 in the first embodiment of the present invention;

[0026] Figure 10 This is a comparison of the welding gun angle R value (°)-time (s) curves of the unsmoothed embodiment 2 of the present invention and when j=35;

[0027] Figure 11 1 is a comparison of the angular velocity (° / s)-time (s) curves of the welding gun angle R when the smoothing process is not performed and when j=35 in the second embodiment of the present invention;

[0028] Figure 12 This is a diagram showing the welding effect of the corrugated plate when the smoothing process is not performed in the second embodiment of the present invention;

[0029] Figure 13 This is a diagram showing the welding effect of a corrugated plate when the smoothness level j=35 according to the second embodiment of the present invention;

[0030] In the figure: X: parallel to the bottom surface of the corrugated plate along the weld direction; Y: parallel to the bottom surface of the corrugated plate and perpendicular to the weld direction; R: welding gun angle, which is the angle between the center axis of the welding gun and the Y direction; C1: bottom straight segment; C2, C6: bottom corrugated segment; C3, C5: middle corrugated segment; C4: top corrugated segment; C1-1, C1-2: straight transition segment; Δθ: angle between the center axis of the welding gun and the perpendicular direction of the tangent of the welding gun motion trajectory; j: smoothing level; ΔT: time interval; T: sampling time. DETAILED DESCRIPTION

[0031] The present invention will be further described below through embodiments with reference to the accompanying drawings.

[0032] In an embodiment, a method for smoothing the angle of a welding torch for a main shield corrugated plate of an enclosure system is provided. The motion trajectory of the welding torch is composed of a bottom straight segment C1 of the corrugated plate, a bottom corrugated segment C2, a middle corrugated segment C3, a top corrugated segment C4, a middle corrugated segment C5, and a bottom corrugated segment C6. During welding, the motion trajectory of the welding torch is synthesized by motion in the X direction and the Y direction. The welding torch angle R is adjusted by a welding torch rotation mechanism. The welding torch angle R is defined as a positive angle when tilted in the negative X direction with the gun tip as the center, and a negative angle otherwise.

[0033] The welding gun movement trajectory is as follows Figure 4 As shown, straight transition segments C1-1 and C1-2 are set at the two ends of the straight segment C1 at the bottom of the corrugated plate near the bottom corrugated segments C2 and C6, and the welding gun angle R in the trajectory of the straight transition segment C1-1, bottom corrugated segment C2, middle corrugated segment C3, top corrugated segment C4, middle corrugated segment C5, bottom corrugated segment C6, and straight transition segment C1-2 is smoothed, and the remaining trajectory parts are not smoothed.

[0034] The smoothing process uses the following method:

[0035] The theoretical value of the welding gun angle R is sampled at a fixed time interval ΔT, and is set as 、 、 … , for any three consecutive sampling points 、 、 ( ) is formed by the broken line segment, take and The midpoint of and The midpoint of the two midpoints, and then take the midpoint ,by Replace the original , completing the smoothing process of the welding gun angle Ri.

[0036] Similarly, set j as the smoothing level, iterate the welding gun angle Ri j times, that is, perform j smoothing processes on the welding gun angle Ri, and after j iterations, the welding gun angle Calculated according to formula (1):

[0037] (1)

[0038] in is the number of location sampling points, After j iterations, the welding gun angle Ri effect is as follows: Figure 5 shown.

[0039] The time interval ΔT is 10ms-50ms, and the smoothing level j ranges from 10-50.

[0040] An included angle Δθ is set between the vertical direction of the tangent of the welding gun movement trajectory and the central axis of the welding gun, and Δθ is 0-10° to meet the welding process requirements.

[0041] The straight transition section C1-1 is 0-5 mm, and the straight transition section C1-2 is 0-5 mm.

[0042] Set the maximum value of the welding gun angle R to ±60°. When it exceeds ±60°, keep it unchanged to avoid interference between the welding mechanism and the surface of the corrugated plate workpiece when the welding gun rotates, which will affect the welding effect. Example 1:

[0043] The sampling time interval ΔT is 20ms, the smoothing level j is 20, the angle Δθ between the center axis of the welding gun and the perpendicular direction of the tangent of the welding gun motion trajectory is 3°, the length of the straight transition section C1-1 is 2.5mm, the length of the straight transition section C1-2 is 2.5mm, and the maximum value of the welding gun angle R is 60°. For the straight transition section C1-1, the bottom corrugated section C2, the middle corrugated section C3, the top corrugated section C4, the middle corrugated section C5, the bottom corrugated section C6, and the straight transition section C1-2, 20 iterations of smoothing are performed according to formula (1), and the welding gun angle R data is calculated as follows: Figure 6 、 7 shown.

[0044] from Figure 6 、 Figure 7 、 Figure 8 and Figure 9 It can be seen that after the welding gun angle R is smoothed, the welding gun angle transition in each stage is smooth, the welding process is stable, the weld is well formed, and it meets the use requirements. Example 2:

[0045] The sampling time interval ΔT is 30ms, the smoothing level j is 35, the angle Δθ between the center axis of the welding gun and the perpendicular direction of the tangent of the welding gun motion trajectory is 3°, the length of the C1-1 segment is 1.5mm, the length of the C1-2 segment is 1.5mm, and the maximum value of the welding gun angle R is 60°. For the straight transition segment C1-1, the bottom corrugated segment C2, the middle corrugated segment C3, the top corrugated segment C4, the middle corrugated segment C5, the bottom corrugated segment C6, and the straight transition segment C1-2, 35 iterations of smoothing are performed according to formula (1), and the welding gun angle R data is calculated as follows: Figure 10 、 11 shown.

[0046] from Figure 10 、 Figure 11 、 Figure 12 、 Figure 13It can be seen that after the welding gun angle R is smoothed, the welding gun angle transition in each stage is smooth, the welding process is stable, the weld is well formed, and it meets the use requirements.

Claims

1. A method for smoothing the welding torch angle of a main shield corrugated plate of an enclosure system. The torch motion trajectory is composed of the bottom straight section C1, the bottom corrugated section C2, the middle corrugated section C3, the top corrugated section C4, the middle corrugated section C5, and the bottom corrugated section C6 of the corrugated plate. During welding, the torch motion trajectory is a combination of motion in the X and Y directions. The torch angle R is adjusted by a torch rotation mechanism. The method is characterized by: Set straight transition sections C1-1 and C1-2 at the ends of the straight section C1 at the bottom of the corrugated plate, near the bottom corrugated sections C2 and C6. Smooth the welding gun angle R in the trajectory of the straight transition section C1-1, bottom corrugated section C2, middle corrugated section C3, top corrugated section C4, middle corrugated section C5, bottom corrugated section C6, and straight transition section C1-2. The rest of the trajectory is not smoothed. The smoothing process adopts the following method: The theoretical value of the welding gun angle R is sampled at a fixed time interval ΔT, and is set as 、 、 … For any three consecutive sampling points 、 、 ( ) is formed by the broken line segment, take and The midpoint of and The midpoint of the two midpoints, and then take the midpoint ,by Replace the original , complete the smoothing process of the welding gun angle Ri; Similarly, set j as the smoothing level, iterate the welding gun angle Ri j times, that is, perform j smoothing processes on the welding gun angle Ri, and after j iterations, the welding gun angle Calculated according to formula (1): （1）； in is the number of location sampling points, .

2. A method for smoothing the welding torch angle of a main shield corrugated plate of an enclosure system according to claim 1, characterized in that: The time interval ΔT is 10ms-50ms, and the smoothing level j ranges from 10-50.

3. The method for smoothing the welding torch angle of the main shield corrugated plate of the enclosure system according to claim 1, characterized in that: An angle Δθ is set between the vertical direction of the tangent of the welding gun movement trajectory and the central axis of the welding gun, and Δθ is 0-10°.

4. The method for smoothing the welding torch angle of the main shield corrugated plate of the enclosure system according to claim 1, characterized in that: The length of the straight transition section C1-1 is 0-5 mm, and the length of the straight transition section C1-2 is 0-5 mm.

5. The method for smoothing the welding torch angle of the main shield corrugated plate of the enclosure system according to claim 1, characterized in that: The maximum value of the welding gun angle R is ±60°, and when it exceeds ±60°, it remains unchanged.

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