A protective device and method for argon arc welding of gas turbine inserts

Abstract

The present invention provides a protective device and method for argon arc welding of gas turbine inserts, including a welding protective tool, wherein the welding protective tool includes a base, a cover plate, an adjusting screw and a bottom pad, wherein the upper end of the base is an arc surface structure, the lower end of the base is connected to the cover plate, and an argon gas channel is provided on the base; one end of the adjusting screw is connected to the lower end of the cover plate; the free end of the adjusting screw is connected to the bottom pad; the present invention utilizes a protective device to ensure an accurate welding position, prevent internal welding defects and welding cracks, and improve labor production efficiency and processing quality.

Description

Technical Field

[0001] The invention belongs to the field of gas turbines, and in particular relates to a protective device and method for argon arc welding of gas turbine inserts. Background Art

[0002] The main material of a gas turbine power turbine bearing housing is 1Cr12Ni3MoVN. Its structure is a thin-walled, slender annular casing. Five arc-surface embedded bosses need to be welded on the outer wall of the part. The weld grade is Class III Group 11. After welding, 100% of the welds need to be inspected by X-ray flaw detection. This places high demands on the weld forming quality and welding defect control of manual argon arc welding. Due to the small diameter of the inner wall of this casing, the accessibility of the embedded weld root cleaning and grinding operation from the inside is poor, and the manual argon arc welding of the weld at this location is difficult. 1Cr12Ni3MoVN is a martensitic stainless steel. After welding, the strength and hardness of this material increase, the plasticity and toughness decrease, the residual stress is large, and cold cracks are prone to occur. The pass rate of the initial welding X-ray inspection of this part is only 20%.

[0003] At present, the conventional methods used for manual argon arc welding of such casing parts are as follows:

[0004] 1. Welding groove

[0005] 1. Groove form: For full penetration butt welds, a 60° double-sided V-groove is often used (such as Figure 2 shown).

[0006] 2. Blunt edge thickness: The blunt edge thickness of the groove is 2mm.

[0007] 3. Gap size: When assembling, the groove gap size between the casing and the welding parts is 1 to 2 mm.

[0008] 2. Main welding process parameters

[0009] 1. Power supply type and polarity: Use DC positive connection method.

[0010] 2. Electrode material and specifications: Cerium tungsten electrode is usually selected, with a diameter of φ3.2.

[0011] 3. Welding current: 150~180(A).

[0012] 4. Shielding gas and flow rate: The shielding gas on the front of the weld is ventilated at the welding torch, and the back of the weld is not ventilated for protection. 3. Welding steps:

[0013] 1. Spot weld along the weld to ensure the weld is firm.

[0014] 2. Base welding: No protective device is used on the back of the weld. Base welding is performed from the front of the weld, and then the root is ground and cleaned from the back of the weld.

[0015] 3. After removing welding defects, weld the filling layer and cover layer.

[0016] According to the above method, when welding the arc surface insert on the outer wall of the thin-walled slender bearing housing, argon protection is not used on the back of the weld. Due to the high sensitivity of 1Cr12Ni3MoVN material to oxygen, the back weld is oxidized and blackened, with many welding defects and poor forming. Although the back welding defects can be removed by grinding and root cleaning, the grinding area is not easy to observe and it is extremely inconvenient for workers to operate during grinding due to the limitations of the casing structure and size. If the welding defects are not removed, the subsequent welding cannot meet the X-ray inspection acceptance requirements. In addition, due to the thin wall thickness of the shell, the welding area is locally heated, and the lack of tooling positioning can easily cause the embedded parts to shrink into the annular casing after welding, resulting in a large welding shape. Conventional methods restrict the processing efficiency and quality of parts. Summary of the invention

[0017] The purpose of the present invention is to provide a protective device and method for argon arc welding of gas turbine inserts, which is used for argon arc welding of single-sided welding and double-sided forming of gas turbine casing and curved surface inserts, with the purpose of solving the problems of many internal defects in high-grade welds, low X-ray detection pass rate, poor forming on the back of welds, and difficulty in repairing welding defects.

[0018] In order to achieve the above object, the technical solution adopted by the present invention is:

[0019] The present invention provides a protective device for argon arc welding of gas turbine inserts, including a welding protective tooling, wherein the welding protective tooling includes a base, a cover plate, an adjusting screw and a bottom pad, wherein the upper end of the base is an arc surface structure, the lower end of the base is connected to the cover plate, and an argon gas channel is provided on the base; one end of the adjusting screw is connected to the lower end of the cover plate; and the free end of the adjusting screw is connected to the bottom pad.

[0020] Preferably, a square annular groove is provided at the lower end of the base; a molten pool is provided at the upper end of the base;

[0021] A plurality of vent holes are evenly distributed along the circumference between the molten pool and the square annular groove;

[0022] The square annular groove, the vent hole and the molten pool are connected in sequence to form an argon gas channel.

[0023] Preferably, the molten pool is a ring-shaped groove, and the cross section of the groove is an arc-shaped structure.

[0024] Preferably, a step arranged in a square ring is provided on the top of the cover plate, and the step is clamped in a square ring groove opened at the lower end of the base.

[0025] Preferably, the argon gas channel is connected to an external gas cylinder.

[0026] Preferably, a pad is provided between the lower end of the cover plate and the top end of the adjusting screw.

[0027] Preferably, a sleeve is provided on the adjusting screw.

[0028] Preferably, a bolt is provided at the top center of the base.

[0029] Preferably, one end of the welding protection tooling is in contact with the inner wall surface of the to-be-welded area of ​​the casing and the inner surface of the embedded boss.

[0030] A method for argon arc welding of a gas turbine insert comprises the following steps:

[0031] Step 1, setting the weld between the casing of the gas turbine and the embedded boss to a butt full penetration type, and the weld is a single-sided 50° groove form;

[0032] Step 2, assembling the protective device, the embedded boss and the casing;

[0033] Step 3, introducing argon gas into the argon gas channel;

[0034] Step 4, perform multi-point positioning welding along the circumferential direction of the weld between the casing and the embedded boss, and after completion proceed to step 5;

[0035] Step 5, perform base welding in the circumferential direction of the weld between the casing and the embedded boss by using a symmetrical method, and after completion proceed to step 6;

[0036] Step 6: Weld the cover layer using the symmetrical method.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides a protective device for argon arc welding of gas turbine inserts, wherein a welding protection tooling is arranged between the inner wall surface of the casing to be welded area and the inner surface of the embedded boss, and an argon gas channel is arranged on the welding protection tooling, so that a closed argon gas protection area is formed on the back of the weld gap between the embedded boss to be welded and the casing shell, and during the base welding process, argon gas is evenly filled to block the entry of air and protect the weld pool from oxidation. At the same time, since the embedded boss is in a suspended state when being welded, a lead screw is designed on the cover plate, and the deformation of the embedded boss can be better controlled by adjusting the weld misalignment amount when the embedded boss is welded and assembled with the shell.

[0039] Furthermore, an arc-shaped groove is designed at the argon gas outlet to support the molten pool and control the back side forming of the weld.

[0040] The present invention provides a method for argon arc welding of gas turbine inserts. First, a weld between a casing of the gas turbine and an embedded boss is set to a single-sided 50° groove form, so that the casing reduces the amount of groove processing. At the same time, the welding heat input is small, which is convenient for controlling the deformation of the embedded boss; a protective device is used to ensure an accurate welding position, prevent internal welding defects and welding cracks, and improve labor production efficiency and processing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure between the casing and the embedded boss;

[0042] Figure 2 This is a schematic diagram of a conventional 60° double-sided V-groove;

[0043] Figure 3 This is a schematic diagram of a single-sided 50° groove of the present invention;

[0044] Figure 4 Schematic diagram of the thickness of the blunt edge of the groove of the present invention;

[0045] Figure 5 Schematic diagram of the gap between welding assemblies of the present invention;

[0046] Figure 6 This is a schematic diagram of the symmetrical bottom welding sequence of the present invention;

[0047] Figure 7 It is a schematic diagram of the arrangement of the bottom welding points and the swing trajectory of the welding gun of the present invention;

[0048] Figure 8 It is a schematic diagram of the structure of the protection device of the present invention;

[0049] Fig. 9 is a schematic diagram of the base of the protection device of the present invention;

[0050] Fig.10 is an AA view of the base of the protective device of the present invention;

[0051] Fig.11 is a schematic diagram of a cover plate of a protective device of the present invention;

[0052] Fig.12 It is a BB view of the cover plate of the protective device of the present invention;

[0053] Fig.13 It is a schematic diagram of the use of the protection device of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0055] The present invention provides a gas turbine insert argon arc welding method, which is a single-sided welding and double-sided forming argon arc welding method that can control welding deformation and improve the first-time qualified rate of welding. The welding method uses an argon protection device to fit the inner wall surface of the casing area to be welded and the inner surface of the embedded boss, and forms a closed argon protection area on the back of the weld gap between the boss to be welded and the shell. During the base welding process, argon is evenly filled to block the entry of air and protect the weld pool from oxidation. The argon outlet is designed as an arc-shaped groove to support the molten pool and control the back forming of the weld. At the same time, since the boss is in a suspended state when it is welded, a lead screw is designed on the cover plate of the protection device, which is threadedly connected to the protection device. By adjusting the weld misalignment when the boss is welded to the shell, the deformation of the boss can be well controlled.

[0056] The present invention provides a protective device for argon arc welding of gas turbine inserts, including a welding protective tool, wherein the welding protective tool includes a base 1, a cover plate 2, an adjusting screw 3 and a bottom pad 6, wherein the upper end of the base 1 is an arc surface structure, the lower end of the base 1 is connected to the cover plate 2, and an argon gas channel is provided on the base 1; one end of the adjusting screw 3 is connected to the lower end of the cover plate 2; and the free end of the adjusting screw 3 is connected to the bottom pad 6.

[0057] The present invention provides a method for argon arc welding of a gas turbine insert, comprising the following steps:

[0058] Step 1, setting the weld between the casing of the gas turbine and the embedded boss to a butt full penetration type, and the weld is a single-sided 50° groove form;

[0059] Step 2, assembling the protective device, the embedded boss and the casing;

[0060] Step 3, introducing argon gas into the argon gas channel;

[0061] Step 4, perform multi-point positioning welding along the circumferential direction of the weld between the casing and the embedded boss, and after completion proceed to step 5;

[0062] Step 5, perform base welding in the circumferential direction of the weld between the casing and the embedded boss by using a symmetrical method, and after completion proceed to step 6;

[0063] Step 6: Weld the cover layer using the symmetrical method.

[0064] Example

[0065] The present invention provides a protective device for argon arc welding of gas turbine inserts, such as Figure 1 As shown, taking the welding of embedded square boss as an example, the design and production of the welding protection device are explained:

[0066] 1. Material selection: In order to ensure that the welding tooling will not be contaminated by the melt during welding, affecting the quality of the weld, and to have a better welding heat conduction effect, the main material is made of brass H68.

[0067] 2. Structural design: It mainly consists of base 1, cover plate 2, adjusting screw 3, connecting bolt 4, pad 5, base pad 6, air guide tube 7, sleeve 8 and connecting bolt 9, among which:

[0068] like Fig. 9 , Fig.10 As shown, the upper part of the base 1 is designed to be an arc surface that fits the casing, and a Φ6 annular groove is designed on the arc surface. The cross-sectional shape of the groove is an arc structure, which is used to form a molten pool to ensure the back side of the weld is formed.

[0069] The lower part of the base 1 is designed with a square ring groove for argon gas circulation. There are Ø2 air holes every 20mm between the upper arc-shaped groove and the lower square groove. Argon gas can flow evenly from the lower part of the base to the upper part, which plays a rectifying role and forms a stable argon gas layer.

[0070] like Fig.11 , Fig.12 As shown, the cover plate 2 has an annular square step on the upper portion, and the annular square step is used to cooperate with the square ring groove at the lower portion of the base 1 to seal the argon gas on the back.

[0071] One end of the adjusting screw 3 is threadedly connected to the bottom pad 6 to serve as the top pad.

[0072] The other end of the adjusting screw 3 is inserted into the central hole of the backing plate 5 to support the base 1 with uniform force so that the upper curved surface of the base 1 fits with the casing.

[0073] The connecting bolts 4 connect the base 1 and the cover plate 2 .

[0074] The centers of the pad 5 and the bottom pad 6 are both provided with threaded holes for supporting the adjusting screw and playing a top supporting role.

[0075] One end of the air guide tube 7 is connected to the square ring groove provided on the base 1, and the other end is connected to the external gas cylinder, so as to pass argon gas from the external gas cylinder into the protection device.

[0076] One end of the air guide tube 7 is an elbow structure.

[0077] The adjusting screw 3 is provided with a sleeve 8; the sleeve 8 is used to adjust the tightness of the fit between the casing, the protective device and the embedded convex seat.

[0078] The connecting bolt 9 is used in different situations. When there is a through hole on the embedded boss, it is used to clamp the embedded boss and the protective device; if there is no hole on the embedded boss, it is not used.

[0079] The method for using the welding protection device comprises the following steps:

[0080] Step 1: The annular square step on the cover plate 2 is installed into the square ring groove of the base 1 and fastened with connecting bolts 4 so that the annular square step on the cover plate 2 fits and seals with the step surface of the square ring groove.

[0081] Step 2: Place the bottom surface of the workpiece to be welded tightly against the arc surface of the base 1.

[0082] Step 3, screw one end of the air guide tube 7 into the vent hole on the side of the base 1, and seal the other end with the argon gas cylinder through a hose, with the elbow of the air guide tube 7 facing the bottom of the base 1.

[0083] Step 4, screw one end of the adjusting connecting rod 3 into the threaded hole on the bottom pad 6, and screw the other end into the pad 5.

[0084] Step 5, press the connected connecting rod 3 and the bottom pad 6 against the inner wall of the casing, and the pad 5 presses the cover plate 2.

[0085] Step 6, adjust the installation height and tightening degree of the workpiece to be welded by rotating sleeve 8, so that the arc surface of the base 1 is close to the inner wall of the casing, the arc surface of the bottom of the boss is flush with the inner wall of the casing, and the welding gap between the boss shape and the bearing housing is uniform.

[0086] Step 7: Check the clamped assembly to see if the bolts on the protective device are loose.

[0087] The present invention provides a method for argon arc welding of a gas turbine insert, comprising the following steps:

[0088] Step 1: Welding groove design

[0089] (1) Groove type: This part is a full penetration weld, and the design uses a single-sided 50° groove type, such as Figure 3 As shown;

[0090] (2) Blunt edge thickness: The blunt edge thickness of the groove is 0.5 mm. Figure 4 As shown;

[0091] (3) Gap size: The groove gap size between the base workpiece and the workpiece to be welded is 2 to 3 mm. Figure 5 shown.

[0092] Its purpose is to:

[0093] First, the base parts (casing) no longer need to be processed with grooves, which reduces the amount of groove processing;

[0094] Second, the weld is well fused and has few defects;

[0095] Third, the welding heat input is small, which facilitates the control of welding deformation.

[0096] Step 2: Assembling: Using the protective device of the present invention, assemble the embedded boss with the casing, such as Fig.13 As shown;

[0097] Step 3: introduce argon gas into the protective device.

[0098] (1) Ventilate the front torch with an argon gas flow rate of 8 to 15 (L / min).

[0099] (2) The back of the weld is protected by welding protection equipment, and the argon gas flow rate is 10-15 (L / min).

[0100] Step 4: Multi-point positioning welding

[0101] (1) Positioning welding current 130~150 (A).

[0102] (2) Evenly distribute 12 to 15 positioning welds around the weld, with a weld diameter of 4 to 5 mm and a weld penetration of 2 to 2.5 mm.

[0103] Positioning welding must consider both firm positioning and controlled penetration thickness. During the base welding, the weld shrinks due to uneven heating around the weld. If the weld is not firm, it is easy to cause the weld to crack. The penetration thickness of the weld must also be controlled. If the thickness is too large, it is difficult to penetrate during the base welding.

[0104] Step 5: Symmetrical bottom welding

[0105] (1) The base welding current is 150~180 (A).

[0106] (2) Use the symmetrical method to weld in the order of 1, 2, 3, 4, such as Figure 6 As shown;

[0107] (3) The double-point superposition method is used for wire filling, and the wire filling sequence and welding gun swing trajectory are Z-shaped, such as Figure 7 As shown;

[0108] (4) The weld thickness is 2.5 to 3.5 mm. If the base weld is too thin, stress cracking may occur easily. If the weld is too thick, the heat input may be too high and the welding deformation may be large, which may affect the formation of the cover weld.

[0109] Step 6: Symmetrical welding of the cover layer

[0110] (1) The welding current of the cover layer is 150~180 (A).

[0111] (2) Control the interlayer temperature, and when the temperature of the base weld drops to the range of 150-200°C, perform the welding of the symmetrical cover weld.

[0112] (3) The welding gun swing trajectory is the same as that of the base welding, and both make Z-shaped swings to ensure that the weld is evenly formed and beautiful.

[0113] Step 7: Remove the welding protection device and inspect the weld.

[0114] The advantages of the present invention are:

[0115] By adopting the above welding method and welding device, the X-ray inspection pass rate of high-grade welds of embedded workpieces has been significantly improved, solving the problem of difficult rework due to welding defects, and also has better control over welding deformation, ensuring accurate welding position, preventing internal welding defects, welding cracks, etc., ensuring welding qualification, reducing rework, and improving labor production efficiency and processing quality. This welding method and welding device can be applied to the welding of other similar models of gas turbine casings and embedded parts.

Claims

1. A method for argon arc welding of gas turbine inserts, characterized in that: The following steps are involved: Step 1, setting the weld between the casing of the gas turbine and the embedded boss to a butt full penetration type, and the weld is in the form of a single-sided 50° groove, the single-sided 50° groove blunt edge thickness is 0.5 mm, and the groove gap size between the casing of the gas turbine and the embedded boss is 2 to 3 mm; Step 2, assembling a protective device, an embedded boss and a casing for argon arc welding of a gas turbine insert; Step 3, introducing argon gas into the argon gas channel, wherein: Introduce argon gas into the front welding torch at a flow rate of 8L / min to 15L / min. The back of the weld is protected by welding protection tooling, and the argon gas flow rate is 10L / min~15L / min; Step 4, perform multi-point positioning welding along the circumferential direction of the weld between the casing and the embedded boss, and after completion, proceed to step 5, wherein: Set the positioning welding current to 130A~150A; Along the weld, evenly distribute 12 to 15 positioning welding points, with a welding point diameter of 4 to 5 mm and a welding point penetration depth of 2 to 2.5 mm; Step 5, perform base welding in the circumferential direction of the weld between the casing and the embedded boss by using a symmetrical method, and after completion proceed to step 6, wherein: Set the base welding current to 150A~180A; Use symmetrical welding method; The double-point superposition method is used for wire filling, and the wire filling sequence and welding gun swing trajectory are Z-shaped; Weld thickness 2.5mm~3.5mm; Step 6, welding the cover layer using a symmetrical method, wherein: Set the cover layer welding current to 150A~180A; Control the interlayer temperature, wait until the base weld temperature drops to 150-200℃, and then weld the symmetrical cap weld; The welding gun swing trajectory is the same as that of the base welding, both are Z-shaped swing; The protection device comprises a welding protection tool, and the welding protection tool comprises a base (1), a cover plate (2), an adjusting screw (3) and a bottom pad (6), wherein the upper end of the base (1) is an arc surface structure, the lower end of the base (1) is connected to the cover plate (2), and an argon gas channel is provided on the base (1); one end of the adjusting screw (3) is connected to the lower end of the cover plate (2); and the free end of the adjusting screw (3) is connected to the bottom pad (6); A square annular groove is provided at the lower end of the base (1); a molten pool is provided at the upper end of the base (1); A plurality of vent holes are evenly distributed along the circumference between the molten pool and the square annular groove; The square annular groove, the vent hole and the molten pool are connected in sequence to form an argon gas channel; The molten pool is a groove arranged in an annular shape, and the cross section of the groove is an arc-shaped structure; The arc surface at the upper end of the base (1) of the welding protection tooling fits the inner wall surface of the area to be welded in the casing and the inner surface of the embedded convex seat; The top of the cover plate (2) is provided with steps arranged in a square ring, and the steps are clamped in a square ring groove opened at the lower end of the base (1); The argon gas channel is connected to an external gas cylinder; A pad (5) is provided between the lower end of the cover plate (2) and the top end of the adjusting screw (3); The adjusting screw (3) is provided with a sleeve (8); A bolt (9) is arranged at the top center of the base (1).

Images