Flux-cored wire carbon-gouging-free welding process

Abstract

The invention relates to the technical field of welding processes, and provides a flux-cored wire carbon-gouging-free welding process, which adopts a flux-cored wire for bottoming, ensures the impact performance of a welding seam, can meet the impact requirements of a land cold-temperature tower and an offshore wind tower on the low temperature of-50 DEG C, and better controls the defects of welding spatter, welding pores and the like. The method improves the welding quality of a product, and comprises the following steps: S1, preparation work before welding: checking whether welding equipment such as a welding machine, a welding gun and a cable is intact or not, checking whether welding materials such as a flux-cored wire and protective gas required by welding are complete or not, and checking and cleaning a welding area of a welding part; appropriate welding parameters such as welding current, voltage and welding speed are set, a backing weld joint of a welding part is welded through a flux-cored wire, the backing weld joint is formed, the welding method is CO2 gas shielded welding, and an outer side weld joint of the welding part is welded in a submerged-arc welding mode.

Description

Technical Field

[0001] The invention relates to the technical field of welding technology, and in particular to a flux-cored wire carbon-free planing welding process. Background Art

[0002] As we all know, flux-cored wire carbon-free planing welding process is a special welding technology, which is often used in the manufacture of structures such as wind towers, especially when the welding quality needs to be guaranteed and there are strict requirements on the carbon content.

[0003] The international standard material for wind tower bodies is mainly European standard S355. Due to the different working environments of wind towers, the requirements for the impact performance of the main materials are also different. The low-temperature impact toughness of onshore cold-temperature towers and offshore wind towers is relatively high. There are more and more cases where the welding requirements for S355 materials must meet the low-temperature impact toughness ratio of -50℃47J. In some use environments, the design requirements for materials even reach more than 70J.

[0004] The main processes of the main welds of wind towers mostly use CO2 gas shielded welding for base assembly and submerged arc welding. In order to achieve carbon-free planing and ensure the pass rate, solid welding wire is used as the base welding material. However, the common CO2 gas shielded welding wire on the market can only meet the maximum impact requirement of -30℃ 27J, which is difficult to meet the new requirements of wind tower design. In addition, solid wire CO2 gas shielded welding has large welding spatter and a high probability of defects such as pores in welding, and the welding pass rate is low. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a flux-cored wire carbon-free planing welding process, which uses flux-cored wire as the base, and the impact performance of the weld is guaranteed, which can meet the -50°C low-temperature impact requirements of onshore cold temperature towers and offshore wind towers. At the same time, compared with solid wire gas shielded welding as the base welding, defects such as welding spatter and welding porosity are better controlled, thereby improving the welding quality of the product.

[0006] To achieve the above object, the present invention provides the following technical solution: a flux-cored wire carbon-free planing welding process, comprising the following steps:

[0007] S1. Preparation before welding:

[0008] S11. Check whether welding equipment such as welding machine, welding gun and cables are in good condition;

[0009] S12. Check whether the welding materials such as flux-cored welding wire and shielding gas required for welding are complete;

[0010] S13. Check and clean the welding area of ​​the welded parts;

[0011] S2. Welding work:

[0012] S21. Setting appropriate welding parameters such as welding current, voltage and welding speed according to the material and thickness of the welded part;

[0013] S22. The base weld of the welded part is welded by flux-cored wire to form the base weld, and the welding method is CO2 gas shielded welding;

[0014] S23, the outer weld of the weldment is welded by submerged arc welding to form an outer weld;

[0015] S24, the inner weld of the welded part is not carbon gouged, and the inner weld 2 is welded with a larger welding parameter to ensure penetration;

[0016] S3. Post-welding processing:

[0017] S31. Perform visual inspection on the weld to check its surface quality and dimensional accuracy;

[0018] S32. Post-process the welded parts to eliminate welding stress.

[0019] Preferably, in the step S13, the welding area of ​​the weldment needs to be provided with a groove, and the groove is divided into an inner groove and an outer groove. The groove angles of the inner groove and the outer groove are both 70°, and the blunt edges of the inner groove and the outer groove are both 2mm to 4mm. During welding, the minimum gap of the weldment is 0mm to 2mm.

[0020] Preferably, the outer weld and the inner weld of the base weld in step S2 need to adjust their corresponding welding current, voltage and welding speed parameters before welding. To ensure the economy and safety of the welding process, the welding speed is maintained between 20cm / min-50cm / min.

[0021] Preferably, during the flux-cored wire carbon-free planing welding in step S22, the angle between the welding gun and the weldment should be maintained between 10° and 15°, and the movement of the welding gun should be kept stable to avoid excessive shaking.

[0022] Preferably, during the carbon-free planing welding with flux-cored welding wire in step S22, the condition of the weld on the welded part should be observed at all times, and a combination of straight-line and serrated-line welding can be used according to the specific situation to ensure the forming quality and penetration depth of the weld.

[0023] Preferably, the base weld of the weldment needs to be positioned before welding. The positioning operation can be achieved by clamping the weldment, or by forming multiple connection positioning welds at the minimum gap of the weldment before the base weld operation.

[0024] Compared with the prior art, the present invention provides a flux-cored wire carbon-free planing welding process, which has the following beneficial effects:

[0025] In the present invention, the impact performance of the weld is guaranteed by the selection of the flux-cored wire primer process, which can meet the -50°C low-temperature impact requirements of onshore cold-temperature towers and offshore wind towers. At the same time, compared with solid wire gas shielded welding primer welding, defects such as welding spatter and welding porosity are better controlled, thereby improving the welding quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the relative distribution of the base weld, the outer weld and the inner weld of the present invention;

[0027] Figure 2 It is a schematic diagram of the groove setting of the weldment of the present invention.

[0028] In the figure: 1, base weld; 2, inner weld; 1' outer weld. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0030] Example

[0031] See also Figure 1-Figure 2 , a flux-cored wire carbon-free planing welding process, comprising the following steps:

[0032] S1. Preparation work before welding: First, check whether the welding equipment such as welding machine, welding gun and cable are in good condition. Then, check whether the welding materials such as flux-cored wire and shielding gas required for welding are complete. Finally, check and clean the welding area of ​​the welded part. The welding area of ​​the welded part needs to be set with a groove. The groove is divided into an inner groove and an outer groove. The groove angle of the inner groove and the outer groove is 70°, and the blunt edge of the inner groove and the outer groove is 2mm~4mm. When welding, the minimum gap of the welded part is 0mm~2mm.

[0033] S2. Welding operation: First, according to the material of the weld and the thickness of the workpiece, set the appropriate welding parameters such as welding current, voltage and welding speed. Then, the base weld 1 of the weld is welded with flux-cored wire to form the base weld 1. The welding method is CO2 gas shielded welding. When flux-cored wire is used for carbon-free planing welding, the angle between the welding gun and the weld should be kept between 10° and 15°, and the movement of the welding gun should be kept stable to avoid excessive shaking. When flux-cored wire is used for carbon-free planing welding, the condition of the weld on the weld should be observed at all times. According to the specific situation, a combination of straight line and sawtooth wire transportation is used to ensure the forming quality and penetration depth of the weld. Then, the outer weld of the weld is welded by Submerged arc welding is used to form an outer weld 1'. Finally, the inner weld of the welded part is not carbon gouged, and a larger welding parameter is used to weld the inner weld 2 to ensure full penetration. Before welding, the base weld 1, the outer weld 1' and the inner weld 2 need to adjust their corresponding welding current, voltage and welding speed parameters. To ensure the economy and safety of the welding process, the welding speed is maintained between 20cm / min-50cm / min. Before welding, the base weld 1 of the welded part needs to be positioned. The positioning operation can be achieved by clamping the welded part, and it can also be achieved by forming a multi-segment connection positioning weld at the minimum gap of the welded part before the base weld 1 operation.

[0034] S3. Post-processing of welding operation: First, the weld is visually inspected to check the surface quality and dimensional accuracy of the weld. After that, the welded parts are post-processed to eliminate welding stress.

[0035] The selection and adjustment of welding cable, welding voltage and welding speed are as follows:

[0036] Welding current: Generally between 120A-200A. The specific value will vary depending on the base material, thickness and welding wire specifications of the welded part. For example, for thinner low-carbon steel, the current may be 120A-150A, and for slightly thicker medium-carbon steel, the current may be 160A-200A.

[0037] Welding voltage: usually around 18V-25V. The voltage needs to be well matched with the current to ensure the stability of the arc. Under low current conditions, the voltage may be 18V-20V. As the current increases, the voltage can be appropriately increased to 22V-25V.

[0038] Welding speed: about 20cm / min-50m / min. For thinner weldments, a relatively faster welding speed can be adopted, such as 30cm / min-50cm / min. For thicker weldments, in order to ensure full penetration, the welding speed should be appropriately reduced, possibly to 20cm / min-30cm / min.

[0039] Shielding gas flow rate: generally 15L / min-22L / min. If the welding environment is well ventilated, the gas flow rate can be appropriately increased to ensure a good shielding effect. For small diameter welding wire, the flow rate can be slightly lower, such as 15L / min-18L / min. For large diameter welding wire, the flow rate can be 18L / min-22L / min.

[0040] Welding wire extension length: usually between 15mm-25mm. Too long extension length may easily lead to arc instability, while too short extension length may affect welding operation and protection effect.

[0041] The welding machine, welding gun and cable in this embodiment are all conventional equipment purchased on the market and known to those skilled in the art. In the present invention, we only use them without improving their structure and function. For those skilled in the art, their setting method, installation method and electrical connection method can be debugged and operated according to the requirements of their instruction manual, and will not be described in detail here.

[0042] In summary, during the welding operation of the flux-cored wire carbon-free planing welding process, the design of the groove angle is very critical. If the groove angle or the blunt edge size is too large, the welding slag is easily embedded in the gap of the blunt edge of the groove when the flux-cored wire is base-welding, and cannot float out of the molten pool, forming a defect. If the groove angle is too small, it is easy to form a pear-shaped weld and cracks during submerged arc welding. If the blunt edge size is too small, due to the large penetration depth of submerged arc welding, it is easy to weld through the groove on the other side of the base weld during submerged arc welding, and normal welding cannot be performed.

[0043] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0044] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A flux-cored wire carbon-free planing welding process, characterized in that: The steps include: S1. Preparation before welding: S11. Check whether the welding machine, welding gun and cable equipment are in good condition; S12. Check whether the flux-cored welding wire and shielding gas required for welding are complete; S13. Check and clean the welding area of ​​the welded parts; S2. Welding work: S21, setting appropriate welding parameters of welding current, voltage and welding speed according to the material of the welded part and the thickness of the workpiece; S22, the weldment is welded by flux-cored wire to form a base weld 1, and the welding method is CO2 gas shielded welding; S23, the outer weld of the weldment is welded by submerged arc welding to form an outer weld 1'; S24, the inner weld of the welded part is not carbon gouged, and the inner weld 2 is welded with a larger welding parameter to ensure penetration; S3. Post-welding processing: S31. Perform visual inspection on the weld to check its surface quality and dimensional accuracy; S32. Post-process the welded parts to eliminate welding stress.

2. A flux-cored wire carbon-free planing welding process according to claim 1, characterized in that: In the step S13, the welding area of ​​the weldment needs to be provided with a groove, and the groove is divided into an inner groove and an outer groove. The groove angles of the inner groove and the outer groove are both 70°, and the blunt edges of the inner groove and the outer groove are both 2mm to 4mm. During welding, the minimum gap of the weldment is 0mm to 2mm.

3. A flux-cored wire carbon-free planing welding process according to claim 2, characterized in that: Before welding, the base weld 1, the outer weld 1' and the inner weld 2 in step S2 need to adjust their respective welding current, voltage and welding speed parameters. To ensure the economy and safety of the welding process, the welding speed is maintained between 20cm / min-50cm / min.

4. A flux-cored wire carbon-free planing welding process according to claim 3, characterized in that: During the carbon-free planing welding with flux-cored wire in step S22, the angle between the welding gun and the welded part should be kept between 10° and 15°, and the movement of the welding gun should be kept stable to avoid excessive shaking.

5. A flux-cored wire carbon-free planing welding process according to claim 4, characterized in that: During the carbon-free planing welding with flux-cored wire in step S22, the weld on the welded part should be observed at all times, and a combination of straight-line and serrated-line welding can be used according to the specific situation to ensure the quality of the weld and the depth of penetration.

6. A flux-cored wire carbon-free planing welding process according to claim 5, characterized in that: The base weld 1 of the weldment needs to be positioned before welding. The positioning can be achieved by clamping the weldment, or by forming multiple connection positioning welds at the minimum gap of the weldment before the base weld 1 is performed.

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