Double-wire single-arc symmetrical full penetration welding method for T-shaped thick plate robot

Abstract

The invention relates to the technical field of welding, in particular to a double-wire single-arc symmetrical full penetration welding method for a T-shaped thick plate robot, and provides the following scheme aiming at the problems that in the prior art, when a T-shaped thick plate is welded, the filling amount is large, welding is asymmetrically deformed, back gouging on the reverse side is difficult, and the first-pass yield of welding is unstable. The method comprises the following steps that S1, a workpiece is blanked, the perpendicularity of a cutting face is guaranteed, and the cutting face is ground and subjected to slag removal; s2, grooves are prepared, double-face symmetrical K-shaped grooves are formed in the two sides of the web, the groove angle is 45 degrees, and the groove angle deviation is controlled to be + / -2.5 degrees; and S3, oxide skins on the two sides of the groove and the welding seam are polished till metal luster is achieved. According to the method, the welding filling amount can be effectively reduced, the construction time is shortened, in addition, the welding accuracy and stability of the robot ensure the symmetry and uniformity of welding seams, the one-time qualification rate of the welding seams is increased, and therefore the reverse back gouging difficulty is reduced.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and particularly to a T-shaped thick plate robot double-wire single-arc symmetric full-penetration welding method. Background Art

[0002] In building steel structures, for the full-penetration welds of T-shaped thick plates (t≥30mm), manual welding has problems such as a large welding filling amount, shrinkage deformation caused by welding asymmetry, and back gouging, and the first-pass welding qualification rate is also unstable. However, by using a robot for double-wire single-arc automatic welding, the human factor is solved, the double wires can have the same molten pool and the same speed, the threshold of the technical level of production personnel is reduced, and the penetration requirement of T-shaped welding is effectively guaranteed.

[0003] However, although the robot double-wire single-arc welding technology has made breakthroughs in improving welding efficiency and ensuring welding quality, in actual operation, especially for the symmetric full-penetration welding of T-shaped thick plates, there are still some technical problems: 1. How to ensure the uniform distribution of the double wires in the molten pool; 2. How to accurately control the welding speed and welding parameters to achieve perfect symmetry and complete penetration of the weld seam. For this reason, this solution proposes a T-shaped thick plate robot double-wire single-arc symmetric full-penetration welding method. Summary of the Invention

[0004] The T-shaped thick plate robot double-wire single-arc symmetric full-penetration welding method proposed by the present invention solves the problems of large filling amount, welding asymmetric deformation, difficult back gouging, and unstable first-pass welding qualification rate existing in welding T-shaped thick plates in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A T-shaped thick plate robot double-wire single-arc symmetric full-penetration welding method includes the following steps:

[0007] S1. Workpiece blanking, ensuring the perpendicularity of the cutting surface, and grinding and removing slag from the cutting surface;

[0008] S2. Groove preparation, opening double-sided symmetric K-shaped grooves on both sides of the web, with a groove angle of 45°, and controlling the groove angle deviation within ±2.5°;

[0009] S3. Grinding the oxide scale on both sides of the groove and the weld seam;

[0010] S4. Assembly and positioning, assembling and positioning the web and two flange plates. When assembling the web and the flange plates, leave a 5mm welding gap and fix it by tack welding;

[0011] S5. Welding, adjusting the angle of the robot welding torch and the wire feeding speed to make the angle between the welding wire and the workpiece 35°, and the front and rear inclination angles of the welding direction 10-15°;

[0012] S6. Perform multi-layer and multi-pass welding in the order of the backing layer, filling layer, and capping layer. The thickness of each layer is 3 - 4 mm. Clean the welding slag between layers, and leave a height of 1 - 2 mm for the backing layer.

[0013] S7. Optimize the parameters, use a vision sensor to monitor the weld formation in real time, and cooperate with a closed-loop control system to dynamically adjust the welding parameters.

[0014] S8. Stress relief. After welding, perform heat treatment to eliminate the residual stress, and conduct non-destructive testing on the weld.

[0015] Through the above technical solutions, the welding filling amount can be effectively reduced, and the construction time can be shortened. In addition, the accuracy and stability of robotic welding ensure the symmetry and uniformity of the weld, improve the one-time qualification rate of the weld, and thus reduce the difficulty of back gouging.

[0016] As a further improvement of the above solution, the thickness of the web is ≥ 30 mm, there is no root face left at the edge of the K-shaped 45° groove. The groove is processed by a semi-automatic flame cutting machine, and the grinding range of the groove surface attachment is 30 - 50 mm.

[0017] Through the above technical solutions, the root face-free design eliminates the risk of root lack of fusion, and expanding the grinding range can effectively remove the oxide layer pollution.

[0018] As a further improvement of the above solution, in step S4, the tack welding length is 30 - 50 mm, the fillet weld size hf < 4 mm, and the tack welding starting and ending arcs are welded according to the type AⅠ weld.

[0019] As a further improvement of the above solution, in step S4, when two flange plates and the web form an H-shaped steel, temporary supports are set at both ends of the web to adjust the cross-sectional size. The temporary supports are set at the head and end of the H-shaped steel to control the cross-sectional size accuracy during assembly.

[0020] As a further improvement of the above solution, the temporary support is a detachable rigid support, which is set at 10 - 20 mm from the weld edge at the head and end of the T-shaped structure.

[0021] As a further improvement of the above solution, in step S5, before adjusting the wire angle, first adjust the wire extension length. The length of the wire extending from the contact tip is 15 mm, and the length error is ±1 mm.

[0022] As a further improvement of the above solution, in step S8, the backing weld is performed using the leftward welding method, with a current of 290 - 310 A, a voltage of 28 - 35 V, and a welding speed of 20 - 35 cm / min. The filling weld is performed using the rightward welding method, with a current of 340 - 370 A, a voltage of 36 - 39 V, and a welding speed of 20 - 30 cm / min. The capping stage is performed using the leftward welding method, with a current of 300 - 320 A / voltage of 31 - 34 V, and a welding speed of 20 - 30 cm / min.

[0023] Through the above technical solution, the leftward welding method controls the penetration depth to prevent burn-through, and the rightward welding method improves the filling efficiency.

[0024] As a further improvement of the above solution, in step S9, after welding, ultrasonic or radiographic inspection is used for flaw detection to ensure that there are no defects inside the weld.

[0025] As a further improvement of the above solution, in step S5, double-wire single-arc synchronous wire feeding control is adopted to ensure that the two wires are welded in the same molten pool and at the same speed.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. By using the double-wire single-arc welding method, the welding filling amount can be significantly reduced, thereby shortening the construction time and improving the work efficiency. In addition, the accuracy and stability of robot welding ensure the symmetry and uniformity of the weld, effectively avoiding structural safety problems caused by weld shrinkage deformation.

[0028] 2. The back gouging step is simplified, the operation difficulty and technical requirements are reduced, the first-pass qualification rate of the weld is further improved, the rework phenomenon is reduced, and the project cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of the web groove of the present invention;

[0030] Figure 2 It is a schematic structural diagram of the groove and assembly gap of the H-beam web;

[0031] Figure 3 It is a schematic structural diagram of the tack welding position;

[0032] Figure 4 It is a schematic structural diagram of the welding angle;

[0033] Figure 5 It is a schematic structural diagram of the temporary support;

[0034] Figure 6 It is a schematic structural diagram of the multi-layer multi-pass welding;

[0035] Figure 7 It is a schematic structural diagram of the leftward welding;

[0036] Figure 8 It is a structural schematic diagram of right welding. Specific implementation manners

[0037] Next, in combination with the accompanying drawings and specific implementation manners, the present invention will be further described. It should be noted that, on the premise of no conflict, any combination of the following-described embodiments or technical features can form a new embodiment.

[0038] Embodiment 1:

[0039] Please combine Figures 1-6 , a double-wire single-arc symmetric full-penetration welding method for a T-shaped thick plate robot in this embodiment, includes the following steps:

[0040] S1. Workpiece blanking. The connection weld between the H-beam flange plate and the web is a full-penetration weld. A gap needs to be reserved during assembly. When blanking the web, 10 mm should be deducted from the width dimension, and the perpendicularity of the cutting surface should be ensured during blanking. After the steel plate blanking is completed, due to the residual cutting slag on the surface, a shovel and a grinding machine should be used to polish and remove the slag on the cutting surface, and the surface should be shiny metallic.

[0041] S2. Groove preparation. Double-sided symmetric K-shaped grooves are opened on both sides of the web, the groove angle is 45°, there is no root face left at the edge of the groove, and the deviation of the groove angle is controlled within ±2.5° (as Figure 1 shown). When opening the groove, first take the center line in the width direction of the web as the reference to draw the groove cutting line, and then use a semi-automatic flame cutting machine to cut at the web groove. Open the K-shaped groove according to the joint form and plate thickness, and control the deviation of the groove angle within ±2.5°. After the groove processing is completed, it is necessary to polish the area within 30 - 50 mm near the groove surface to remove impurities such as surface oxide scale, cutting slag, rust, oil, paint, dust, and moisture that affect the welding quality. The design without root face eliminates the risk of root lack of fusion, and the polishing range is expanded to remove the oxide layer pollution.

[0042] S3. Polish the impurities such as cutting slag, oxide scale, and rust within 50 mm on both sides of the groove position of the web and the weld position in the middle of the flange plate until it becomes metallic. The web groove surface is polished with a grinding machine, and the flange plate is polished with a belt grinder;

[0043] S4. Assembly and positioning. Assemble and position the web and two flange plates. When assembling the web and the flange plate, a 5-mm welding gap is reserved and fixed by tack welding (as Figure 3 shown), ensuring that the welding gap in the middle position between the web and the flange plate is uniform. The length of the tack welding is 30 - 50 mm, and the fillet weld size hf < 4 mm. The starting and ending arcs of the tack welding are welded according to the AⅠ-class welds, so as to ensure a smooth joint.

[0044] S5. Welding. Adjust the angle of the robot welding torch and the wire feeding speed so that the angle between the welding wire and the workpiece is 35°, the two wires are in zero-distance contact, and the front and rear inclination angles of the welding direction are 10 - 15°. Adopt the double-wire single-arc synchronous wire feeding control to ensure that the two wires are welded in the same molten pool and at the same speed (as Figure 4 shown);

[0045] S6. Perform multi-layer and multi-pass welding in the order of the backing layer, filling layer, and capping layer. The thickness of each layer is 3 - 4 mm, not exceeding 5 mm (as Figure 6 shown), and the welding slag and surface spatter should be cleaned in time between layers (passes) using a pneumatic chisel, grinder, iron shovel, etc. When defects affecting the welding quality are found, they should be removed before welding. Leave a height of 1 - 2 mm for the backing layer.

[0046] S7. Parameter optimization. Under the condition of ensuring that the two wires are in the same molten pool and at the same speed, use a vision sensor to monitor the weld formation in real time, and cooperate with a closed-loop control system to dynamically adjust the welding parameters;

[0047] S8. Stress relief. After welding, perform heat treatment to eliminate the residual stress. Finally, perform non-destructive testing on the weld. During testing, use one of ultrasonic or radiographic inspection for flaw detection to ensure that there are no defects inside the weld.

[0048] In this embodiment, through the double-sided symmetric K-shaped groove design, a symmetric flow channel of the molten pool is formed. Then, through the robot double-wire synchronous control, the deposited metal is evenly distributed. At the same time, the parameters are optimized in real time by using a vision sensor and a closed-loop system, so as to ensure the penetration consistency, greatly improve the first-pass qualification rate of the weld, and reduce the back gouging process.

[0049] In this embodiment, before welding, first adjust the length of the welding wire extending out. The length of the welding wire extending out of the contact tip is 15 mm, and the length error is ±1 mm, so as to ensure that the welding wire can better contact the workpiece during welding.

[0050] Combined with Figure 5 , in this embodiment, when two flange plates and a web form an H-shaped steel, temporary supports are set at both ends of the web to adjust the cross-sectional dimensions. The temporary supports are set at the head and end of the H-shaped steel and are used to control the cross-sectional dimension accuracy during assembly. The temporary supports are detachable rigid supports and are set at a distance of 10 - 20 mm from the weld edge at the head and end of the T-shaped structure. By setting rigid supports, a reverse binding force is provided to offset the thermal stress deformation of the workpiece during welding.

[0051] In this embodiment, the leftward welding method is used for the backing weld. Combined with Figure 7, In the leftward welding method, the welding current arc moves from the right end to the left end of the joint and points to the part to be welded. Since the molten metal is blown forward, the arc cannot directly act on the base metal, resulting in a relatively shallow penetration depth. At this time, the current is 295 A, the voltage is 32 V, and the welding speed is 25 cm / min. The filling welding uses the rightward welding method. Combining Figure 8 , In the rightward welding method, the welding arc moves from the left end to the right end of the joint and points to the welded part. The molten metal melted by the rightward welding method is directly blown backward, and the arc directly acts on the base metal, resulting in a larger penetration depth. At this time, the current is 355 A, the voltage is 37 V, and the welding speed is 25 cm / min. The leftward welding method is used in the surfacing stage, with a current of 310 A, a voltage of 33 V, and a welding speed of 25 cm / min. The gas flow rate of the CO2 shielding gas is 15 L / min, the qualified rate of UT inspection is 100%, and the deformation amount is 1.3 mm.

[0052] Combining Figure 2 , In this embodiment, according to different plate thicknesses, the groove and erection gap of the H-beam web are as follows. When the plate thickness is 30 mm, the total of the groove width and the gap is 20 mm. When the plate thickness is 40 mm, the total of the groove width and the gap is 25 mm. When the plate thickness is 50 mm, the total of the groove width and the gap is 30 mm.

[0053] Example 2:

[0054] Combining Figures 6-8 , The difference between this embodiment and Example 1 is that the leftward welding method is used for the backing weld, with a current of 290 A, a voltage of 28 V, and a welding speed of 20 cm / min. The rightward welding method is used for the filling weld, with a current of 340 A, a voltage of 36 V, and a welding speed of 20 cm / min. The leftward welding method is used in the surfacing stage, with a current of 300 A, a voltage of 31 V, and a welding speed of 20 cm / min. The gas flow rate of the CO2 shielding gas is 15 L / min, the qualified rate of UT inspection is 95%, and the deformation amount is 1.5 mm.

[0055] Example 3:

[0056] Combining Figures 6-8 , The difference between this embodiment and Examples 1 - 2 is that the leftward welding method is used for the backing weld, with a current of 310, a voltage of 35 V, and a welding speed of 35 cm / min. The rightward welding method is used for the filling weld, with a current of 370 A, a voltage of 39 V, and a welding speed of 30 cm / min. The leftward welding method is used in the surfacing stage, with a current of 320 A, a voltage of 34 V, and a welding speed of 30 cm / min. The gas flow rate of the CO2 shielding gas is 15 L / min, the qualified rate of UT inspection is 96%, and the deformation amount is 1.4 mm.

[0057] Welding process test:

[0058] The welding processes in Examples 1 - 3 were tested, and the results are as follows

[0059] Table 1 Welding Process Parameter Data

[0060]

[0061] Comparative analysis of the data in Table 1 shows that during welding, the root pass uses the leftward welding method with a current of 295 A, a voltage of 32 V, and a welding speed of 25 cm / min; the filler pass uses the rightward welding method with a current of 355 A, a voltage of 37 V, and a welding speed of 25 cm / min; the capping pass uses the leftward welding method with a current of 310 A, a voltage of 33 V, and a welding speed of 25 cm / min; the gas flow rate of the CO2 shielding gas is 15 L / min. At this time, the qualified rate of UT inspection is the best, being 100%, and the deformation amount is the lowest, being 1.3 mm.

[0062] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A double-wire single-arc symmetric full-penetration welding method for T-shaped thick plates by a robot, characterized in that, The following steps are involved: S1. Unload the workpiece, ensure the verticality of the cutting surface, and grind and remove slag from the cutting surface; S2. Bevel preparation: double-sided symmetrical K-shaped bevels are opened on both sides of the web, with a bevel angle of 45° and a bevel angle deviation controlled within ±2.5°; S3. Grind the oxide scale on both sides of the groove and weld; S4. Assemble and position the web plate and the two flange plates. When assembling the web plate and the flange plates, a 5mm welding gap is reserved and fixed by positioning welding. S5, welding, adjust the robot welding gun angle and wire feeding speed, so that the angle between the welding wire and the workpiece is 35°, and the front and rear inclination angle of the welding direction is 10-15°; S6. Perform multi-layer and multi-pass welding in the order of base layer, filling layer and cover layer. The thickness of each layer is 3-4mm. Clean the welding slag between layers and leave 1-2mm height for the base layer. S7, parameter optimization, using visual sensors to monitor weld formation in real time, and dynamically adjusting welding parameters in conjunction with a closed-loop control system; S8. Stress relief: After welding, heat treatment is performed to eliminate residual stress and the weld is subjected to non-destructive testing.

2. The double-wire single-arc symmetric full penetration welding method for T-shaped thick plates by a robot according to claim 1, characterized in that, The web thickness is ≥30mm, the edge of the K-shaped 45° groove has no blunt edge, the groove is processed by a semi-automatic flame cutting machine, and the grinding range of the groove surface accessories is 30-50mm.

3. A T-shaped thick plate robot double-wire single-arc symmetric full penetration welding method according to claim 1, characterized in that, In step S4, the length of the positioning weld is 30-50 mm, the weld leg size hf is less than 4 mm, and the starting and ending of the positioning weld are both in accordance with Class AⅠ welds.

4. A double-wire single-arc symmetric full penetration welding method for T-shaped thick plates by a robot according to claim 1, characterized in that In step S4, when the two flange plates and the web plate form an H-shaped steel, temporary supports are set at both ends of the web plate to adjust the cross-sectional size. The temporary supports are set at the first and second ends of the H-shaped steel to control the cross-sectional size accuracy during assembly.

5. A T-shaped thick plate robot double-wire single-arc symmetric full penetration welding method according to claim 1, characterized in that The temporary support is a detachable rigid support, which is arranged at the first and second ends of the T-shaped structure 10-20 mm away from the edge of the weld.

6. A T-shaped thick plate robot double-wire single-arc symmetric full penetration welding method according to claim 1, characterized in that In step S5, the extension length of the welding wire is adjusted before adjusting the welding wire angle. The length of the welding wire extending out of the conductive nozzle is 15 mm, and the length error is ±1 mm.

7. A method for symmetric full penetration welding of double-wire single-arc of T-shaped thick plate by robot according to claim 1, characterized in that, In step S8, the base welding adopts the left welding method, the current is 290-310A, the voltage is 28-35V, and the welding speed is 20-35cm / min. The filling welding adopts the right welding method, the current is 340-370A, the voltage is 36-39V, and the welding speed is 20-30cm / min. The left welding method is adopted in the covering stage, the current is 300-320A / voltage is 31-34V, and the welding speed is 20-30cm / min.

8. A method for symmetric full penetration welding of a T-shaped thick plate by a robot with double wires and single arc according to claim 1, characterized in that In step S9, after welding, one of ultrasonic or radiographic inspection is used for flaw detection to ensure that there are no defects inside the weld.

9. A method for symmetric full penetration welding of a T-shaped thick plate by a robot with double wires and single arc according to claim 1, characterized in that, In step S5, dual-wire single-arc synchronous wire feeding control is adopted to ensure that the dual wires are welded in the same molten pool and at the same speed.

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