A swing welding method for suppressing the wave deformation of thin plate welding

Abstract

The present invention provides a swing welding method for suppressing the wave deformation of thin plate welding. The implementation steps include positioning and clamping two thin-walled plate parts, using the welding center line as the swing center line of the swing welding trajectory, setting the swing width W of the swing welding, the edge welding current and the center welding current of the swing welding, and making the welding current in the welding process change according to the change of the distance between the end of the welding torch electrode and the swing center line of the swing welding, and the welding current is lower when the welding torch electrode is closer to the swing center line, so as to achieve precise control of the heat input in the area near the welding center line, thereby reducing the accumulation of thermal stress in the relevant area and suppressing the wave deformation after welding in the relevant area.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and more particularly, to a swing welding method for suppressing wavy deformation in thin plate welding. Background Art

[0002] In the practical application of welding technology, thin plate welding has always been a key and complex technical field, and the problem of wavy deformation therein has been a major challenge that has long troubled the development of the industry.

[0003] During the welding process, when the weld expands due to heat, the relatively low-temperature thin plate area around it will restrict the expansion of the weld. This interaction between thermal expansion and restraint generates uneven stresses inside the plate. As welding continues, these stresses accumulate and redistribute. When the stress exceeds the critical value that the plate can withstand, the plate will become unstable and exhibit wavy deformation. Due to the relatively thin thickness of thin plate materials, their flexural rigidity is low, and their ability to resist deformation is relatively weak. Therefore, the possibility and degree of wavy deformation are greater than those of medium and thick plates.

[0004] Existing swing welding technologies can, to a certain extent, reduce the degree of wavy deformation of the plate near the welding center line of the plate by dispersing the heat input near the welding center line of the plate in space. However, it is still difficult to completely suppress the wavy deformation of thin plates, resulting in the size and shape of the welded workpiece not meeting the standards. To this end, it is often necessary to control the wavy deformation by reducing the weld length and multi-segment welding, which is often not feasible in cases where there are requirements for connection strength or where welding sealing is required. In a large number of application scenarios, there is an urgent need for a welding method with stronger adaptability and better effect of suppressing wavy deformation to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems and provide a swing welding method for suppressing wavy deformation in thin plate welding, so as to effectively reduce the wavy deformation generated during thin-wall welding and improve the quality of thin-wall welding.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A swing welding method for suppressing wavy deformation in thin plate welding includes the following steps:

[0008] Step S10: Position and clamp two thin-wall plate parts, and determine the welding center line between the two plate parts;

[0009] Step S20: Use the welding center line as the swing center line of the swing welding track;

[0010] Step S30: Set the swing width W, swing frequency, edge welding current I1, and center welding current I2 of the weaving welding. The edge welding current I1 is the welding current when the end of the welding torch electrode swings to the maximum distance from the center line of the weaving welding, and the center welding current I2 is the welding current when the end of the welding torch electrode swings to the center line of the weaving welding, and I1 > I2;

[0011] Step S40: Perform the swing welding of the thin-wall plate, and make the welding current Ix during the welding process change according to the change in the distance s between the position of the end of the welding torch electrode and the center line of the weaving welding. The smaller the distance s between the end of the welding torch electrode and the center line of the weaving welding, the smaller the welding current Ix. The change range of Ix is I2 ≤ Ix ≤ I1.

[0012] During the welding process, the plate closer to the welding center line receives more heat input, resulting in a larger temperature change gradient during heating and cooling after welding, and thus greater thermal stress, leading to a greater tendency of wavy deformation. Weaving welding disperses the heat input near the welding center line of the plate in space. Combining with the heat input method of non-constant current, more precise control of the heat input in the area near the welding center line can be achieved. On the other hand, compared with the method of dispersing welding heat by constant current weaving welding, the above method of dispersing heat input by non-constant current weaving welding can achieve the same effect of controlling plate deformation with a smaller swing width, which has a positive effect on reducing the weld width, improving the welding appearance, and increasing the welding speed.

[0013] Preferably, in step S40, the welding current Ix during the welding process changes according to the change in the distance s between the position of the end of the welding torch electrode and the center line of the weaving welding. The relationship between the welding current Ix and the distance s between the end of the welding torch electrode and the center line of the weaving welding can be selected as a linear proportional relationship or a trigonometric function relationship according to the welding characteristics of the plate;

[0014] When Ix and s are in a linear proportional relationship, Ix and s satisfy the following quantitative relationship:

[0015]

[0016] When Ix and s are in a trigonometric function relationship, Ix and s satisfy the following quantitative relationship:

[0017]

[0018] Where W is the swing width, I1 is the edge welding current, and I2 is the center welding current.

[0019] Preferably, the swing trajectory of the welding torch electrode can be one of a zigzag shape, a crescent shape, a perfect circle shape, or a trigonometric function curve shape.

[0020] Preferably, the thickness of the thin plate to be welded is less than or equal to 3 mm.

[0021] Preferably, when the end of the welding torch electrode swings to the center line of the swing welding during the swing welding process, the angle between the welding torch and the welded plate is 90°. When the end of the electrode swings to the side with the maximum distance from the center line of the swing welding, the angle range of the interior angle of the triangle formed by the welding torch and the welded plate is set to 55°-85°. When welding to the other side with the maximum distance from the center line of the swing welding, the angle range of the exterior angle of the triangle formed by the welding torch and the welded plate is set to 95°-125°.

[0022] Preferably, the set range of the swing welding edge current I1 is 10-200A, the set range of the swing welding center current I2 is 20%-90% of the welding current I1, and the set range of the welding speed is less than or equal to 150 cm / min.

[0023] Preferably, a swing welding system for suppressing the wave deformation of thin plate welding using the above swing welding method for suppressing the wave deformation of thin plate welding includes a robot, a welding torch, a welding power source, and a PLC controller. The execution end of the robot is fixedly connected to the welding torch, enabling the welding torch to achieve multi-degree-of-freedom movement driven by the robot. The electrode of the welding torch outputs the welding current supplied by the welding power source. The robot, the welding power source, and the PLC controller are electrically connected. During the welding process, the robot calculates the distance s between the end of the welding torch electrode and the welding center line in real time based on its own real-time position information and attitude information, and sends it to the PLC controller in real time. The PLC controller calculates the welding current value Ix to be output at the current moment according to the preset quantitative relationship between the distance s and the welding current value Ix, and sends it to the welding power source. The welding power source adjusts the magnitude of the output welding current in real time according to the welding current value Ix received from the PLC controller in real time, realizing the swing welding process of suppressing the wave deformation of the thin plate.

[0024] Preferably, the welding power source has the function of receiving input variables in real time and controlling the magnitude of the welding current accordingly. The input variables received can be in the form of analog or digital quantities.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention provides a swing welding method for suppressing the wave deformation of thin plate welding. By determining the welding center line between two plate parts, planning the swing welding trajectory with the welding center line as the swing welding center line, setting the swing welding edge current and the swing welding center current, and making the welding current during the swing welding process change according to the change in the distance between the position of the welding torch electrode and the welding center line, different regions with different welding deformation degrees at different distances from the welding center line are input with different amounts of welding heat, realizing precise control of the heat input in the region near the welding center line, thereby reducing the accumulation of thermal stress in the relevant region and effectively suppressing the wave deformation after welding in the relevant region. Description of the Drawings

[0027] Figure 1 Flow chart of the swing welding method for suppressing the wavy deformation of thin plate welding provided by the present invention;

[0028] Figure 2 Schematic diagram showing the linear proportional relationship between the distance of the swing position from the swing welding center line and the welding current in the swing welding method for suppressing the wavy deformation of thin plate welding provided by the present invention;

[0029] Figure 3 Schematic diagram showing the trigonometric function relationship between the distance of the swing position from the swing welding center line and the welding current in the swing welding method for suppressing the wavy deformation of thin plate welding provided by the present invention;

[0030] Figure 4 Schematic diagrams of different shaped swing trajectories in the swing welding method for suppressing the wavy deformation of thin plate welding provided by the present invention;

[0031] Figure 5 Schematic diagram of the swing welding system for suppressing the wavy deformation of thin plate welding provided by the present invention;

[0032] a - zigzag, b - crescent, c - perfect circle, d - trigonometric function curve. Detailed implementation manners

[0033] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention and cannot be used to limit the present invention.

[0034] It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may have other embodiments and variations, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0035] As Figures 1 to 5 shown, a swing welding method for suppressing the wavy deformation of thin plate welding includes the following steps:

[0036] Step S10: Position and clamp two thin - walled plate parts, and determine the welding center line between the two plate parts;

[0037] Step S20: Set the welding center line as the center of the swing welding trajectory;

[0038] Step S30: Set the swing welding width W, swing frequency, swing edge current I1, and swing center current I2. The swing edge current I1 is the welding current when the end of the welding torch electrode swings to the maximum distance from the swing welding center line during the swing welding process, and the swing center current I2 is the welding current when the end of the welding torch electrode swings to the swing welding center line, and I1 > I2;

[0039] Step S40: Perform swing welding on the thin-walled plate, and make the welding current Ix during the welding process change in response to the change in the distance s between the end of the welding torch electrode and the swing welding center line. Moreover, the smaller the distance s between the end of the welding torch electrode and the swing welding center line, the smaller the welding current Ix. The change range of Ix is I2 ≤ Ix ≤ I1.

[0040] Preferably, during the welding process in step S40, the welding current Ix changes in response to the change in the distance s between the end of the welding torch electrode and the swing welding center line. The relationship between the welding current Ix and the distance s between the end of the welding torch electrode and the swing welding center line can be selected as a linear proportional relationship or a trigonometric function relationship according to the welding characteristics of the plate;

[0041] When Ix and s are in a linear proportional relationship, Ix and s satisfy the following quantitative relationship:

[0042]

[0043] When Ix and s are in a trigonometric function relationship, Ix and s satisfy the following quantitative relationship:

[0044]

[0045] where W is the swing width, I1 is the swing welding edge current, and I2 is the swing welding center current.

[0046] Example 1

[0047] Use a swing welding system for suppressing wave deformation in thin plate welding composed of a Fanuc brand M-10iD / 12 series robot, a Fronius RCU5000i welding power source, and a Siemens S200 series PLC controller. Set the welding speed to 60 cm / min according to the process characteristics and production requirements. The swing welding trajectory adopts a crescent shape, and a linear proportional relationship is used between the welding current Ix and the distance s from the swing position to the swing center line. Set the swing frequency to 90 times / min, the swing width to 4 mm. When the end of the welding torch electrode swings to the side with the maximum distance from the swing welding center line, the angle formed by the welding torch and the plate is 75°, and on the other side, the angle formed by the welding torch and the plate is 105°. The swing welding edge current is 120 A, and the swing welding center current is 90 A. During the swing of the welding torch, the welding power source receives the 16-bit digital current value Ix sent by the PLC controller in real time, and controls the output welding current to change back and forth between 90 A and 120 A, so that the plate near the welding center line will not be over-melted, reducing the thermal stress generated by uneven thermal expansion, thereby reducing the degree of wave deformation. At the same time, the 90 A swing welding center current can still ensure the effective fusion of the weld seam and there will be no lack of fusion defects. After welding, the weld quality is good, the plate is flat and there is no obvious deformation.

[0048] Example 2

[0049] The swing welding system for suppressing the wavy deformation of thin plate welding with the same hardware composition as in Example 1 is used to weld a 1.5-mm-thick stainless steel thin plate. The quantitative relationships among the welding speed, swing welding frequency, swing welding trajectory shape, welding current, and swing position are the same as those in Example 1. The swing width is set to 3 mm. When the end of the welding torch electrode swings to the maximum distance from the swing welding center line, the angle formed by the welding torch and the plate is 80° for the interior angle of the triangle, and the angle formed by the other welding torch and the plate is 100° for the exterior angle of the triangle. The swing welding edge current is 90 A. The 1.5-mm-thick thin plate has a lower ability to resist deformation, and the area near the welding center line has a greater tendency to deform due to thermal stress concentration during welding. Therefore, to suppress this deformation tendency, the swing welding center current is 60 A, which is lower in current intensity on the premise of ensuring the full formation of the molten pool and is equivalent to 66% of the swing welding edge current, more effectively suppressing the wavy deformation extending from the weld to both sides. After welding, the weld quality is good, and the plate is flat without obvious deformation.

[0050] Example 3

[0051] The swing welding system for suppressing the wavy deformation of thin plate welding with the same hardware composition as in Example 2 is used to weld a 1.5-mm-thick aluminum alloy thin plate. The quantitative relationship between the welding current and the swing position uses a trigonometric function relationship, which is more effective in controlling the heat input near the control center line and can more easily select appropriate welding parameters to achieve good weld quality and a flat plate effect.

[0052] It should be understood that the above embodiments are multiple embodiments of the present invention. Based on the present invention, there are many other embodiments and their deformations; when ordinary technicians in this industry do not make pioneering innovations, the deformations and modifications made through the present invention all fall within the protection scope of the present invention.

Claims

1. A swing welding method for suppressing the wave deformation of thin plates, characterized in that, It includes the following steps: Step S10: Position and clamp two thin-walled plate parts, and determine the welding center line between the two plate parts; Step S20: Use the welding center line as the swing center line of the weaving welding track; Step S30: Set the weaving welding swing width W, swing frequency, weaving welding edge current I1 and weaving welding center current I2. The weaving welding edge current I1 is the welding current when the end of the welding torch electrode swings to the position with the maximum distance from the weaving welding center line during the weaving welding process, and the weaving welding center current I2 is the welding current when the end of the welding torch electrode swings to the weaving welding center line, and I1 > I2; Step S40: Perform the weaving welding of the thin-walled plate parts, and make the welding current Ix during the welding process change according to the change of the distance s between the position of the end of the welding torch electrode and the weaving welding center line. The smaller the distance s between the end of the welding torch electrode and the weaving welding center line, the smaller the welding current Ix. The change range of Ix is I2 ≤ Ix ≤ I1; Regarding that the welding current Ix during the welding process changes according to the change of the distance s between the position of the end of the welding torch electrode and the weaving welding center line, the relationship between the welding current Ix and the distance s between the end of the welding torch electrode and the weaving welding center line can be selected as a linear proportional relationship or a trigonometric function relationship according to the welding characteristics of the plate; When Ix and s are in a linear proportional relationship, Ix and s satisfy the following quantitative relationship: When Ix and s are in a trigonometric function relationship, Ix and s satisfy the following quantitative relationship: Where W is the swing width, I1 is the weaving welding edge current, and I2 is the weaving welding center current.

2. The swing welding method for suppressing the wave deformation in thin plate welding according to claim 1, characterized in that, The swing track of the welding torch electrode can be one of zigzag, crescent, circular or trigonometric function curve shape.

3. The swing welding method for suppressing the wave deformation in thin plate welding according to claim 1, wherein, The thickness of the thin plate to be welded is less than or equal to 3 mm.

4. The weaving welding method for suppressing the wave deformation of thin plate welding according to claim 1, wherein During the weaving welding process, when the end of the welding torch electrode swings to the weaving welding center line, the angle between the welding torch and the welding plate part is 90°. When the end of the electrode swings to the side with the maximum distance from the weaving welding center line, the angle range of the interior angle of the triangle formed by the welding torch and the welding plate part is 55° - 85°. When the end of the electrode swings to the other side with the maximum distance from the weaving welding center line, the angle range of the exterior angle of the triangle formed by the welding torch and the welding plate part is 95° - 125°.

5. The swing welding method for suppressing the wave deformation of thin plate welding according to claim 1, characterized in that, The setting range of the weaving welding edge current I1 is 10 - 200 A, the setting range of the weaving welding center current I2 is 20% - 90% of the weaving welding edge current I1, and the setting range of the welding speed is less than or equal to 150 cm / min.

6. A swing welding system for suppressing the wave deformation in thin plate welding, which adopts the swing welding method for suppressing the wave deformation in thin plate welding according to any one of claims 1-5, characterized in that, It includes a robot, a welding torch, a welding power source and a PLC controller. The execution end of the robot is fixedly connected to the welding torch, enabling the welding torch to achieve multi-degree-of-freedom movement driven by the robot. The electrode of the welding torch outputs the welding current supplied by the welding power source. The robot, the welding power source and the PLC controller are electrically connected. During the welding process, the robot calculates the distance s between the electrode end of the welding torch and the welding center line in real time based on its own real-time position information and attitude information, and sends it to the PLC controller in real time. The PLC controller calculates the welding current value Ix to be output at the current moment according to the preset quantitative relationship between the distance s and the welding current value Ix, and sends it to the welding power source. The welding power source adjusts the magnitude of the output welding current in real time according to the welding current value Ix received from the PLC controller in real time, realizing the swing welding process for suppressing the wavy deformation of thin plates.

7. The swing welding system for suppressing the wave deformation of thin plate welding according to claim 6, wherein, The welding power source has the function of receiving input variables in real time and controlling the magnitude of the welding current accordingly. The input variables received can be in the form of analog or digital quantities.

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