Bevel X-shaped groove submerged-arc welding process for pressure steel pipe thick plate

Abstract

The invention provides a bevel X-shaped groove submerged-arc welding process for a pressure steel pipe thick plate, and belongs to the technical field of welding processes. A bevel X-shaped groove submerged-arc welding process for a pressure steel pipe thick plate comprises the following steps that firstly, cutting and assembling before welding are conducted, specifically, firstly, a plate is machined into a >-shaped groove, the groove is an X-shaped groove with a bevel, and the outer side groove is in a V shape; secondly, the X-shaped bevel position of the bevel is washed, and drying treatment is carried out; thirdly, manual welding or gas shield welding is adopted for bottoming, the bottom of the inner side groove is fully welded, and it is guaranteed that a weld joint is not burnt through; fourthly, submerged-arc welding is adopted for welding the inner side, and double-pass submerged-arc welding is adopted for the last covering face; and fifthly, after the inner side is welded, back gouging is conducted on the outer side through carbon arc air gouging, and a groove obtained after back gouging is completed is polished. According to the method, the mode of the groove is changed, the defects that in a traditional technology, the groove machining amount is large, the welding filling amount is large, and submerged-arc welding is adopted for double capping are overcome, and the qualified rate of welding seams is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding processes, and relates to the submerged arc welding process for a folded X-shaped groove, especially a submerged arc welding process for thick plates of penstocks using a folded X-shaped groove. Background Art

[0002] Welding is a commonly used process in the field of machining and manufacturing, also known as fusion welding. It is a manufacturing process and technology that joins metals or other thermoplastic materials such as plastics by heating, high temperature or high pressure.

[0003] The butt welding of thick plates of penstocks is an important link in the production and manufacturing of pressure vessels and steel structure products. The traditional welding methods for this type of weld generally use a single V or X-shaped groove, with manual arc welding or gas shielded welding for backing, submerged arc welding on the front side, gouging on the back side, and then submerged arc welding on the back side. Using this method requires a large amount of manpower, carbon rods, and electric energy. The weld metal filling is large, and the production efficiency is low, time-consuming, and costly. Using an X-shaped groove directly for submerged arc welding backing, filling, and capping requires a reserved root face, which increases the processing process of the groove. The requirements for the roughness, gap size, and root face size of the workpiece groove are very strict and are not easy to achieve. Therefore, we have designed a submerged arc welding process for thick plates of penstocks using a folded X-shaped groove. Summary of the Invention

[0004] The purpose of the present invention is to address the above problems in the existing technology and propose a submerged arc welding process for thick plates of penstocks using a folded X-shaped groove. The technical problem to be solved by this invention is: how to improve the weld qualification rate.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A submerged arc welding process for thick plates of penstocks using a folded X-shaped groove includes the following steps: Step 1: Pre-welding cutting and assembly: First, the plate is machined into a >-shaped groove, and the groove form is a folded X-shaped groove. The outer groove is a V-shaped groove, with a groove size of t / 3, a groove angle of 45° ≤ α ≤ 60°, a root face c of 2 ≤ c ≤ 4, a gap b of 0 ≤ b ≤ 3, 80° ≤ γ ≤ 90°, and 10° ≤ β ≤ 15°; Step 2: Flush the position of the folded X-shaped groove and perform a drying treatment to remove surface moisture, grease, or dirt. Before welding, moisture, grease, dirt, etc. on the metal surface need to be thoroughly removed to prevent the generation of pores and other defects during the welding process. This usually involves methods such as degreasing with organic solvents, treatment with strong alkaline cleaners, or laser cleaning; Step 3: Use manual welding or gas shielded welding for backing welding to fill the bottom of the inner groove completely, ensuring that the weld does not burn through. Use a solid wire with a diameter of φ1.2mm, with a current of 120A - 200A, a voltage of 18V - 25V, and a welding speed of 150 - 250mm / min; Step 4: Use submerged arc welding to weld the inner side. Ensure that the weld penetration is as large as possible without welding leakage. The weld penetration is between 1mm and 3mm. Weld 2 - 3 layers with a total thickness > 6mm. Use a solid wire with a diameter of φ4.0 or φ5.0mm, with a current of 400A - 600A, a voltage of 31V - 35V, and a welding speed of 350 - 500mm / min. This reduces the filling amount of the traditional welding groove. The last layer of surfacing uses double - pass submerged arc welding for surfacing; Step 5: After the inner side welding is completed, use carbon arc air gouging to root - clean the outer side. Grind the groove after root - cleaning, and then use submerged arc welding for welding. Use a solid wire with a diameter of φ4.0 or φ5.0mm, with a current of 450A - 850A, a voltage of 34V - 38V, and a welding speed of 350 - 500mm / min. The last layer of the weld also uses double - pass submerged arc surfacing.

[0006] The working principle of the present invention is as follows: The plate is machined into a > - shaped groove, and the groove form is a chamfered X - shaped groove. The outer groove is a V - shaped groove. Wash the position of the chamfered X - shaped groove and perform a drying treatment to remove surface moisture, grease or dirt, improving the safety and reliability of welding. Use manual welding or gas shielded welding for backing welding to fill the bottom of the inner groove completely. Use submerged arc welding to weld the inner side, reducing the filling amount of the traditional welding groove. The last layer of surfacing uses double - pass submerged arc welding for surfacing, effectively reducing welding deformation and ensuring welding quality. The weld formation is beautiful. After the inner side welding is completed, use carbon arc air gouging to root - clean the outer side. Grind the groove after root - cleaning, and then use submerged arc welding for welding. Carbon arc air gouging uses a high - speed rotating tool and a high - heat and high - pressure gas flow generated by gas injection to perform cutting on the workpiece. The last layer of the weld also uses double - pass submerged arc surfacing. Adjust the welding sequence of the front and back sides at any time according to the plate thickness and product deformation until the welds on both the front and back sides are completely filled.

[0007] Where t ≥ 30mm, the groove form is a chamfered X - shaped groove, the outer groove is a V - shaped groove, the groove size is t / 3, the groove angle is 45° ≤ α ≤ 60°, the root face c is 2 ≤ c ≤ 4, the gap b is 0 ≤ b ≤ 3, 80° ≤ γ ≤ 90°, and 10° ≤ β ≤ 15°.

[0008] For the double - pass submerged - arc surfacing, after welding 1 - 2 layers on the back, 1 - 2 layers are welded on the front. For each weld seam, a solid wire with a diameter of φ4.0 or φ5.0 mm is used, the current is 450 A - 850 A, the voltage is 34 V - 38 V, and the welding speed is 350 - 500 mm / min; the welding sequence of the front and back is adjusted at any time according to the plate thickness and product deformation until the weld seams on both the front and back are completely filled.

[0009] The carbon - arc air gouging uses a high - speed rotating tool and a high - heat and high - pressure air flow generated by gas injection to perform cutting on the workpiece. In carbon - arc air gouging, the arc heat generated between the carbon rod and the workpiece melts the metal, and at the same time, compressed air blows away the melted metal, thereby creating a groove on the metal, which is a thermal processing technology.

[0010] The use of the carbon - arc air gouging includes the following steps: Step 1: Preparation work, check whether all parts of the carbon - arc air gouging are normal; Step 2: Select a suitable tool according to the processing requirements, and adjust the position and angle of the tool; Step 3: Adjust the air flow rate and air pressure of the carbon - arc air gouging according to the workpiece material and processing requirements; Step 4: Bring the carbon - arc air gouging close to the workpiece, turn on the air flow and power supply, and start processing; Step 5: After processing, turn off the air flow and power supply, and clean the working area and the carbon - arc air gouging.

[0011] Due to the adoption of the above - mentioned process: Before use, it should be checked whether all parts of the carbon - arc air gouging are normal, such as the power supply, gas source, tool, clamping device, etc.; Do not use the carbon - arc air gouging for unsuitable materials or occasions to avoid safety accidents; When using the carbon - arc air gouging, protective equipment such as safety glasses, earplugs, gloves, etc. should be worn to ensure personal safety; During the processing, attention should be paid to the direction of the air flow and the tool to avoid hurting oneself or others; After processing, the air flow and power supply should be turned off, and the working area and the carbon - arc air gouging should be cleaned to keep the working environment clean.

[0012] Post - weld hydrogen - removal treatment shall be carried out immediately after welding.

[0013] Compared with the prior art, the submerged - arc welding process for the fillet X - type groove of thick - walled penstocks of the present invention has the following advantages: 1. In the present invention, by changing the form of the groove, the large amount of groove processing and large amount of welding filling in the traditional process are removed. By using double - pass submerged - arc surfacing, the weld qualification rate is guaranteed.

[0014] 2. In the present invention, the position of the flush corner X-shaped groove is rinsed and dried to remove surface moisture, grease or dirt. Before welding, moisture, grease, dirt, etc. on the metal surface are thoroughly removed to prevent the generation of pores and other defects during the welding process and ensure the stability of welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of a submerged arc welding process for a flush corner X-shaped groove of a thick steel plate for a penstock in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following are specific embodiments of the present invention in combination with the drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0017] As Figure 1 shown, a submerged arc welding process for a flush corner X-shaped groove of a thick steel plate for a penstock includes the following steps: Step 1: Pre-welding cutting and assembly: First, the plate is machined into a >-shaped groove, and the groove form is a flush corner X-shaped groove. The outer groove is a V-shaped groove with a groove size of t / 3, a groove angle of 45° ≤ α ≤ 60°, a root face c of 2 ≤ c ≤ 4, a gap b of 0 ≤ b ≤ 3, 80° ≤ γ ≤ 90°, and 10° ≤ β ≤ 15°; Step 2: Rinse the position of the flush corner X-shaped groove and perform a drying treatment to remove surface moisture, grease or dirt. Before welding, moisture, grease, dirt, etc. on the metal surface need to be thoroughly removed to prevent the generation of pores and other defects during the welding process, which usually involves methods such as degreasing with organic solvents, treatment with strong alkaline cleaners or laser cleaning; Step 3: Use manual welding or gas shielded welding for backing, fill the bottom of the inner groove completely, and ensure that the weld does not burn through. Use a solid wire with a diameter of φ1.2 mm, a current of 120 A to 200 A, a voltage of 18 V to 25 V, and a welding speed of 150 to 250 mm / min; Step 4: Use submerged arc welding to weld the inner side. Ensure that the weld penetration is as large as possible without welding leakage. The weld penetration is between 1 mm and 3 mm, weld 2 to 3 layers with a total thickness > 6 mm. Use a solid wire with a diameter of φ4.0 or φ5.0 mm, a current of 400 A to 600 A, a voltage of 31 V to 35 V, and a welding speed of 350 to 500 mm / min, reducing the filling amount of the traditional welding groove. The last pass of surfacing uses double-pass submerged arc welding for surfacing; Step Five: After the inner side welding is completed, the outer side is gouged with carbon arc air gouging for root cleaning. The bevel after root cleaning and grinding is welded by submerged arc welding. Solid wires with a diameter of φ4.0 or φ5.0 mm are used, the current is 450 A - 850 A, the voltage is 34 V - 38 V, the welding speed is 350 - 500 mm / min, and the last layer of weld is also covered with double-pass submerged arc welding.

[0018] Where t ≥ 30 mm, the bevel form is a bevel with a corner X shape, the outer bevel is a V shape, the bevel size is t / 3, the bevel angle is 45° ≤ α ≤ 60°, the root face c is 2 ≤ c ≤ 4, the gap b is 0 ≤ b ≤ 3, 80° ≤ γ ≤ 90°, 10° ≤ β ≤ 15°.

[0019] For the double-pass submerged arc surfacing, after 1 - 2 layers of welding on the back side, 1 - 2 layers of welding are carried out on the front side. Each weld pass uses solid wires with a diameter of φ4.0 or φ5.0 mm, the current is 450 A - 850 A, the voltage is 34 V - 38 V, and the welding speed is 350 - 500 mm / min; the welding sequence of the front and back sides is adjusted at any time according to the plate thickness and the deformation of the product until the welds on the front and back sides are completely filled.

[0020] The carbon arc air gouging uses a high-speed rotating tool and a high-temperature and high-pressure air flow generated by gas injection to perform cutting on the workpiece. The carbon arc air gouging melts the metal through the arc heat generated between the carbon rod and the workpiece, and at the same time blows off the melted metal with compressed air, thereby creating a groove on the metal, which is a thermal processing technology.

[0021] The use of the carbon arc air gouging includes the following steps: Step One: Preparation work, check whether all parts of the carbon arc air gouging are normal; Step Two: Select a suitable tool according to the processing requirements, and adjust the position and angle of the tool; Step Three: Adjust the air flow speed and air pressure of the carbon arc air gouging according to the workpiece material and processing requirements; Step Four: Bring the carbon arc air gouging close to the workpiece, turn on the air flow and power supply, and start processing; Step Five: After processing, turn off the air flow and power supply, and clean the working area and the carbon arc air gouging.

[0022] Due to the adoption of the above process: Before use, it should be checked whether all parts of the carbon arc air gouging are normal, such as the power supply, air source, tool, clamping device, etc.; Do not use the carbon arc air gouging for unsuitable materials or occasions to avoid safety accidents; When using the carbon arc air gouging, protective articles such as goggles, earplugs, gloves, etc. should be worn to ensure personal safety; During the processing, attention should be paid to the direction of the air flow and the tool to avoid hurting oneself or others; After processing, the air flow and power supply should be turned off, and the working area and carbon arc air gouging should be cleaned to keep the working environment clean.

[0023] Post-weld hydrogen removal treatment shall be carried out immediately after welding.

[0024] The working principle of the present invention: The plate is machined into a >-shaped groove, and the groove form is a chamfered X-shaped groove. The outer groove is V-shaped. The chamfered X-shaped groove position is rinsed and dried to remove surface moisture, grease or dirt, improving the safety and reliability of welding. Manual welding or gas shielded welding is used for backing, filling the bottom of the inner groove. Submerged arc welding is used for welding the inner side, reducing the filling amount of the traditional welding groove. The last layer of surfacing is carried out by double-pass submerged arc welding, effectively reducing welding deformation and ensuring welding quality. The weld formation is beautiful. After the inner side welding is completed, the outer side is gouged with carbon arc air gouging for root cleaning. The groove after root cleaning is polished, and submerged arc welding is used for welding. Carbon arc air gouging uses a high-speed rotating tool and a high-temperature and high-pressure air flow generated by gas injection to machine the workpiece. The last layer of weld is also covered with double-pass submerged arc welding. The welding sequence of the front and back sides is adjusted at any time according to the plate thickness and product deformation until the front and back side welds are completely filled.

[0025] In summary, in the present invention, by changing the groove form, the large amount of groove processing and welding filling amount in the traditional process are removed. Double-pass submerged arc surfacing is adopted to ensure the qualified rate of welds.

[0026] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements or use similar methods to replace them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A submerged arc welding process for angled X-shaped groove of thick plate of pressure steel pipe, characterized in that: The steps include: Step 1: Cutting and assembly before welding: First, the plate is machined into a >-shaped groove, the groove form is an X-shaped groove with a folded angle, the outer groove is V-shaped, the groove size is t / 3, the groove angle is 45°≤α≤60°, the blunt edge c is 2≤c≤4, the gap b is 0≤b≤3, 80°≤γ≤90°, 10°≤β≤15°; Step 2: Rinse the X-shaped groove of the corner and dry it to remove surface moisture, grease or dirt; Step 3: Use manual welding or gas shielded welding to weld the bottom of the inner groove to ensure that the weld is not burned through. Use φ1.2mm solid welding wire, current of 120A~200A, voltage of 18V~25V, welding speed of 150~250mm / min; Step 4: Use submerged arc welding to weld the inside to ensure that the weld penetration is as large as possible without leakage. The weld penetration is between 1mm and 3mm. Weld 2 to 3 layers with a total thickness of > 6mm. Use φ4.0 or φ5.0mm solid welding wire, current of 400A to 600A, voltage of 31V to 35V, welding speed of 350 to 500mm / min, reducing the filling amount of traditional welding grooves. The last cover is covered with double-pass submerged arc welding; Step 5: After the inner side is welded, the outer side is cleaned with a carbon arc gouging machine, and the groove is polished. Submerged arc welding is used for welding, using a solid welding wire of φ4.0 or φ5.0 mm, a current of 450A~850A, a voltage of 34V~38V, a welding speed of 350~500mm / min, and the last layer of weld is also covered with double-pass submerged arc.

2. A submerged arc welding process for angled X-shaped groove of a pressure steel pipe thick plate according to claim 1, characterized in that: The t is ≥30 mm, the groove form is an X-shaped groove with a folded angle, the outer groove is V-shaped, the groove size is t / 3, the groove angle is 45°≤α≤60°, the blunt edge c is 2≤c≤4, the gap b is 0≤b≤3, 80°≤γ≤90°, and 10°≤β≤15°.

3. A submerged arc welding process for angled X-shaped groove of a pressure steel pipe thick plate according to claim 2, characterized in that: The double-pass submerged arc cap is welded 1 to 2 layers on the back and then 1 to 2 layers on the front. Each weld uses a solid welding wire of φ4.0 or φ5.0 mm, with a current of 450A to 850A, a voltage of 34V to 38V, and a welding speed of 350 to 500mm / min. The order of front and back welding is adjusted at any time according to the plate thickness and product deformation until the front and back welds are completely filled.

4. A submerged arc welding process for angled X-shaped groove of a pressure steel pipe thick plate according to claim 3, characterized in that: The carbon arc gouging utilizes a high-speed rotating tool and a high-temperature, high-pressure airflow generated by a gas jet to cut a workpiece. The carbon arc gouging melts the metal through the arc heat generated between the carbon rod and the workpiece, and simultaneously blows off the molten metal with compressed air, thereby gouging a groove on the metal.

5. A submerged arc welding process for angled X-shaped groove of a pressure steel pipe thick plate according to claim 4, characterized in that: The use of the carbon arc gouging comprises the following steps: Step 1: Preparation, check whether all parts of the carbon arc gouging are normal; Step 2: Select the appropriate tool according to processing needs and adjust the position and angle of the tool; Step 3: Adjust the air velocity and pressure of the carbon arc gouging according to the workpiece material and processing requirements; Step 4: Bring the carbon arc gouging machine close to the workpiece, turn on the airflow and power, and start processing; Step 5: After processing, turn off the air flow and power, and clean the work area and carbon arc gouging.

6. A submerged arc welding process for angled X-shaped groove for thick plate of penstock according to claim 5, characterized in that: Post-weld dehydrogenation treatment is performed immediately after welding.

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