Anti-deformation device for welding inner end cover of steam turbine generator and using method of anti-deformation device

Abstract

The invention relates to an anti-deformation device for welding an inner end cover of a steam turbine generator and a using method. The anti-deformation device comprises a shape follow-up bottom plate, a rib plate, heat conduction silicone grease and a fan. And efficient heat dissipation and stress balance are achieved by controlling a butt welding seam gap, arranging a heat dissipation device on a non-welding side and matching with a double-station symmetrical welding process. The gap between the bottom plate and the base material is filled with heat-conducting silicone grease, the fan accelerates heat exchange, and interlayer temperature is stable. The method obviously inhibits the welding deformation of the thin-wall structure, is small in flatness deviation, reduces the shaping time compared with a traditional process, improves the percent of pass, is suitable for high-precision welding of high-alloy materials, and can be widely applied to the field of electrical equipment manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbine generator equipment manufacturing, and in particular to an anti-deformation device for welding an inner end cover of a steam turbine generator and a use method thereof. Background Art

[0002] As a core device in the power system, the steam turbine generator has a split-flap, thin-walled welded structure (wall thickness ≤ 22mm) with a diameter of 4-6 meters. It needs to operate for a long time in high temperature and vibration environments. Traditional welding processes have the following problems: Deformation control is difficult The inner end cover is welded together by conical wall panels, ring plates, joint plates and ribs. The welding heat input can easily cause local overheating, resulting in radial deformation of 8-10mm, far exceeding the accuracy requirement of 4mm.

[0003] Traditional heat dissipation methods are inefficient Existing technologies use welding methods with low heat input (such as argon arc welding) or discontinuous welding to reduce heat input, thereby reducing welding deformation. However, this method greatly reduces welding efficiency.

[0004] Poor process coordination Insufficient gap control leads to an increase in the molten pool volume and increases the risk of deformation. Summary of the Invention

[0005] The present invention aims to overcome the above-mentioned shortcomings of the prior art and provides an anti-deformation device for welding the inner end cover of a steam turbine generator and a method for using the device.

[0006] The technical solution adopted in the present invention is as follows: A deformation prevention device for welding the inner end cover of a steam turbine generator, wherein the inner end cover is a split-flap thin-walled welded structure, comprising a conical wall plate, a ring plate, a joint plate and a rib plate, wherein the joint plate and the rib plate are arranged on the wall plate, and the ring plate is arranged on the inner and outer rings of the wall plate, comprising a base plate, a rib plate, thermal grease and a fan; the base plate is arranged on the non-operating surface of the weld, and its shape matches the parent material of the inner end cover; the rib plate includes multiple rib plates fixed on the base plate, serving as heat sinks to increase the heat dissipation area and maintain the stability of the base plate shape; the thermal grease is coated between the base plate and the inner end cover; the fan is arranged on the rib plate to remove the heat conducted to the rib plate.

[0007] Furthermore, one group of anti-deformation devices is arranged on each side of the base material of the weld, and the distance between the two groups of devices is adjusted according to the width of the weld.

[0008] Furthermore, the ribs are fixedly connected to the base plate, and the ribs are evenly spaced.

[0009] Furthermore, the fan is fixed to the rib plate through a detachable structure.

[0010] Furthermore, it also includes a gasket, which is arranged on the non-welding side of the butt weld and covers the weld surface.

[0011] Furthermore, a method for using an anti-deformation device for welding an inner end cover of a steam turbine generator comprises the following steps: S1. Ensure that the gap between the inner end cover butt welds is ≤2mm; S2. Tack weld two sections of the joint plate at the groove on one side of the joint surface. After joining the two inner end caps into a full circle, weld the tack block onto the joint plate. S3. After the inner end cap is assembled, attach a gasket to the non-welded side of the butt weld. S4. Clean the inner cover and baseplate. Apply thermal grease evenly to the inner cover. Place the heat sink on the grease and gently press for 3-5 minutes. S5. Secure the cooling fan to the heat sink rib using clips. S6. First weld the ribs, seam plates, and wall plates, then weld the ring plates and butt welds. S7. Use two workstations for symmetrical welding to ensure synchronous growth of welding volume.

[0012] Furthermore, in step S1, the gap of the inner end cover butt weld is ≤2 mm.

[0013] Furthermore, in step S7, the moving speed of the welding gun and the welding parameters of the symmetrical welding are kept consistent.

[0014] Furthermore, in step S4, the bottom plate of the heat dissipation device is conformally fitted to the ring plate, conical wall plate or joint plate of the inner end cover.

[0015] Furthermore, in step S4, the heat dissipation device is placed between adjacent ribs and ribs, and between ribs and joint plates.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: High-precision deformation control The conformal base plate and thermal grease work together: The pure copper base plate adheres to the base material, and combined with the high thermal conductivity silicone grease, the heat dissipation efficiency is improved, and the post-weld deformation is reduced compared to traditional processes.

[0017] Symmetrical welding process: Dual-station synchronous welding makes the temperature field evenly distributed, reduces residual stress, reduces angular deformation, and realizes "zero correction" processing.

[0018] Significantly improve production efficiency Modular design: The fan has a quick-release snap-on structure, which saves maintenance time compared to traditional bolt connections and the device is reusable.

[0019] Process optimization: Gap ≤ 2mm control and pad heat dissipation work together to improve welding qualification rate and shorten single-piece production cycle.

[0020] Reduce overall costs Material saving: reduce the pyrotechnic correction materials required in the shaping process.

[0021] Labor cost: The shaping time is reduced and the labor cost per piece is reduced.

[0022] Enhanced quality stability Interlayer temperature control: Fan-forced air cooling stabilizes the interlayer temperature, avoids the risk of intergranular corrosion of high-alloy steel, and increases the weld flaw detection pass rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the partial structure of the anti-deformation device of the present invention; Figure 2 It is a schematic diagram of the inner end cover structure.

[0024] Markings in the figure: 1-Wall plate, 2-Ring plate, 3-Joint plate, 4-Rib plate, 5-Bottom plate, 6-Stiffener plate, 7-Fan. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings.

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] Example 1 In this embodiment, if Figure 1 As shown, an anti-deformation device for welding the inner end cover of a steam turbine generator is provided. The inner end cover is a split-flap thin-walled welded structure, including a conical wall plate, a ring plate, a joint plate and a rib plate. The joint plate and the rib plate are arranged on the wall plate, and the ring plate is arranged on the inner and outer rings of the wall plate. The device includes a bottom plate, a rib plate, thermal grease and a fan; the bottom plate is arranged on the non-operating surface of the weld, and its shape matches the parent material of the inner end cover; the rib plate includes multiple rib plates, which are fixed on the bottom plate and serve as heat sinks to increase the heat dissipation area and maintain the stability of the bottom plate shape; the thermal grease is coated between the bottom plate and the inner end cover; the fan is arranged on the rib plate to take away the heat conducted to the rib plate.

[0028] The inner end cover is a split-flap thin-walled structure consisting of a conical wall panel, an annular plate (arranged on the inner and outer rings of the wall panel), a joint plate and a rib plate. The joint plate and the rib plate are welded to the wall panel, and the two inner end covers are spliced ​​into a full circle through the joint plate. The anti-deformation device includes: Bottom plate: Made of pure copper, processed into a cone, fan or strip shape, fitting the non-operating surface base material of the ring plate, wall plate or joint plate; Rib plates: multiple long metal plates fixed to the surface of the base plate by soldering, distributed in a grid pattern; Thermal grease: applied between the base plate and the inner end cover to fill the tiny gap; Fan: Installed on the top of the rib plate, with the air outlet facing the outside of the rib plate.

[0029] During welding, the base plate is placed against the non-operating surface of the weld. Thermal grease conducts welding heat to the copper base plate, where it diffuses through the ribs before being forced to cool by fans. Because the inner end cap is thin-walled, welding heat input can easily cause localized temperature rise and deformation. Active heat dissipation reduces interlayer temperatures and reduces thermal stress accumulation, thereby suppressing deformation.

[0030] The conformal base plate and thermal grease ensure efficient heat conduction, and the rib plate and fan combination achieve "contact cooling + forced air cooling", which improves heat dissipation efficiency compared to traditional passive cooling methods and controls post-weld deformation within 4mm.

[0031] Furthermore, one group of anti-deformation devices is arranged on each side of the base material of the weld, and the distance between the two groups of devices is adjusted according to the width of the weld.

[0032] A set of anti-deformation devices described in Example 1 is placed on each side of the base metal. The spacing between the base plate edges of the two sets of devices is adjusted according to the weld width. For example, when the weld width is 3mm, the spacing between the devices is set to 5mm to ensure that the liquid metal in the weld does not contact the base plate before solidification.

[0033] Symmetrically arranged devices dissipate heat synchronously, balancing heat input on both sides of the weld. Dissipating heat from only one side can lead to a large temperature difference and generate additional stress. Adjusting the spacing between the devices can prevent direct contact between the devices and the hot liquid metal, preventing melting damage to the baseplate.

[0034] Symmetrical heat dissipation on both sides makes the temperature field on both sides of the weld evenly distributed, while preventing the device from being damaged by the welding pool and making it reusable.

[0035] Furthermore, the ribs are fixedly connected to the base plate, and the ribs are evenly spaced.

[0036] The ribs are welded to the base plate, and adjacent ribs are evenly spaced 20mm apart to form a heat dissipation grid, ensuring base plate rigidity while maximizing heat dissipation area.

[0037] Evenly spaced ribs avoid heat dissipation blind spots. When welding heat is transferred to the base plate, the ribs increase surface area to facilitate air convection. If the ribs are spaced too closely together, air flow will be obstructed; if they are spaced too sparsely, the heat dissipation area will be insufficient. A 20mm spacing is the optimal solution.

[0038] The evenly arranged ribs improve heat dissipation efficiency. At the same time, the base plate maintains a stable shape during the welding process without the need for additional support, which reduces the need for shape adjustment compared to traditional processes.

[0039] Furthermore, the fan is fixed to the rib plate through a detachable structure.

[0040] The fan is fixed to the top of the rib plate with a U-shaped clip. One end of the clip is equipped with an elastic clip, and the other end is connected to the rib plate with bolts, which can be quickly disassembled and assembled.

[0041] The fan is installed using snap-fits before welding and can be removed after welding to facilitate relocation. This detachable structure protects the fan from long-term high-temperature aging and facilitates maintenance of the motor bearings, extending the life of the device.

[0042] Furthermore, it also includes a gasket, which is arranged on the non-welding side of the butt weld and covers the weld surface.

[0043] The gasket is made of 3mm thick high temperature resistant ceramic plate, which covers the non-welding side surface of the butt weld and is fixed to the inner end cover with high temperature resistant glue.

[0044] When welding the base layer, the gasket blocks molten droplets from penetrating the weld, preventing weld nodules from forming. It also blocks fan airflow from reaching the welding area, preventing it from interfering with arc stability. Without the gasket, airflow can cause oxidation of the molten pool metal, affecting weld quality.

[0045] Example 2 A method for using an anti-deformation device for welding an inner end cover of a steam turbine generator comprises the following steps: S1. Ensure that the gap between the inner end cover butt welds is ≤2mm; S2. Tack weld two sections of the joint plate at the groove on one side of the joint surface. After joining the two inner end caps into a full circle, weld the tack block onto the joint plate. S3. After the inner end cap is assembled, attach a gasket to the non-welded side of the butt weld. S4. Clean the inner cover and baseplate. Apply thermal grease evenly to the inner cover. Place the heat sink on the grease and gently press for 3-5 minutes. S5. Secure the cooling fan to the heat sink rib using clips. S6. First weld the ribs, seam plates, and wall plates, then weld the ring plates and butt welds. S7. Use two workstations for symmetrical welding to ensure synchronous growth of welding volume.

[0046] Specifically: Lift the two inner end covers to the welding cradle, align the ring plate and the joint plate with the positioning pins to ensure that the butt weld gap is ≤2mm If the gap is out of tolerance, mechanical grinding is used.

[0047] Perform two sections of tack welding at the groove of the joint plate, each section is 60mm long and 10mm thick. After the two halves of the inner end cover are spliced ​​into a full circle, a block (made of the same material as the base material) is welded on the outside of the joint plate.

[0048] Paste a 3mm thick ceramic fiber gasket on the non-welding side of the butt weld, covering the root of the weld, and fix the edge with high-temperature tape.

[0049] Clean the inner end cap and base plate of the grease, and evenly apply thermal grease to the surface of the base material to a thickness of 0.2-0.3mm. Place the conformal base plate (laminated ring plate / wall plate / joint plate) on the thermal grease and gently press for 3-5 minutes until the grease overflows the edge.

[0050] Use the U-shaped clips to secure the fan to the rib.

[0051] Welding sequence: First, weld the fillet welds of the ribs and wall panels; then weld the butt welds of the seam plates; and finally weld the butt welds of the ring plates. Dual-station simultaneous welding is used, and welding parameters are maintained consistent.

[0052] Turn on the fan during welding. Visually inspect the weld surface for cracks and pores, and use a spirit level to check the flatness of the inner end cap.

[0053] Furthermore, in step S1, the gap of the inner end cover butt weld is ≤2 mm.

[0054] Use a feeler gauge to measure the gap in the butt weld. If it exceeds 2mm, compensate by adjusting the groove angle of the joint plate or adding a pad.

[0055] A gap that is too large can easily cause the weld pool to drop, forming a weld nub, and the increased heat input can exacerbate deformation. A gap that is too small can result in insufficient weld fusion. A 2mm gap is the perfect balance between welding process and heat dissipation efficiency, ensuring that the solidification rate of the weld pool matches the heat dissipation rate.

[0056] Furthermore, in step S7, the moving speed of the welding gun and the welding parameters of the symmetrical welding are kept consistent.

[0057] The welders at the two workstations use the same model of welding machine, set the same welding current, voltage and welding speed, and monitor the welding progress to ensure that the difference in welding volume is small.

[0058] If the welding parameters on both sides are inconsistent, the heat input will be different, causing the thermal expansion of the metal on both sides of the weld to be asynchronous, resulting in residual stress differences after cooling. Synchronous parameters can make the temperature field on both sides symmetrical, and the residual stresses cancel each other out.

[0059] Symmetrical welding keeps the flatness deviation of the inner end cover ring plate within 2mm, reducing deformation compared to asymmetric welding and eliminating the need for additional shaping procedures.

[0060] Furthermore, in step S4, the bottom plate of the heat dissipation device is conformally fitted to the ring plate, conical wall plate or joint plate of the inner end cover.

[0061] The bottom plate of the conical wall panel is made of fan-shaped copper sheet, which is processed into a cone angle by a CNC bending machine and fits the conical surface of the wall panel; The bottom plate fitted with the ring plate: cut into strips, with rounded edges to fit the arc surface of the ring plate; The bottom plate of the joint plate is processed into a rectangle, and a groove corresponding to the groove of the joint plate is milled on the surface.

[0062] The high-fit bottom plate reduces the temperature of the base material near the weld, effectively suppressing thermal deformation.

[0063] Furthermore, in step S4, the heat dissipation device is placed between adjacent ribs and ribs, and between ribs and joint plates.

[0064] The bottom plate of the heat sink is placed in the gap between adjacent ribs or in the area between the ribs and the joint plates. The distance between the edge of the bottom plate and the ribs is ≥5mm to avoid interference with the ribs.

[0065] The gaps between the ribs provide space for the device to be installed. The ribs also serve as rigid support for the inner end cap, helping to stabilize the base plate and prevent the device from shifting during welding vibrations. If the device covers the ribs, it will affect the rigidity of the inner end cap and exacerbate deformation.

[0066] The above description is only a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the invention should be included in the scope of protection of the invention.

Claims

1. A deformation prevention device for welding an inner end cover of a steam turbine generator, wherein the inner end cover is a split-flap thin-walled welded structure, comprising a conical wall plate, a ring plate, a joint plate, and a rib plate. The joint plate and the rib plate are arranged on the wall plate, and the ring plate is arranged on the inner and outer rings of the wall plate. It includes a base plate, a rib plate, thermal grease and a fan; the base plate is arranged on the non-operating surface of the weld, and its shape matches the parent material of the inner end cover; the rib plate includes multiple pieces, which are fixed on the base plate and serve as heat sinks to increase the heat dissipation area and keep the base plate shape stable; the thermal grease is coated between the base plate and the inner end cover; the fan is arranged on the rib plate to take away the heat conducted to the rib plate.

2. The anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 1, characterized in that: The anti-deformation device is arranged in one group on each side of the base material of the weld, and the distance between the two groups of devices is adjusted according to the width of the weld.

3. The anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 1, characterized in that: The ribs are fixedly connected to the bottom plate, and the ribs are evenly spaced.

4. The anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 1, characterized in that: The fan is fixed on the rib plate through a detachable structure.

5. The anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 1, characterized in that: The invention also includes a gasket, which is arranged on the non-welding side of the butt weld and covers the weld surface.

6. A method for using an anti-deformation device for welding an inner end cover of a steam turbine generator, applied to the anti-deformation device for welding an inner end cover of a steam turbine generator according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Ensure that the gap between the inner end cover butt welds is ≤2mm; S2. Tack weld two sections of the joint plate at the groove on one side of the joint surface. After joining the two inner end caps into a full circle, weld the tack block onto the joint plate. S3. After the inner end cap is assembled, attach a gasket to the non-welded side of the butt weld. S4. Clean the inner cover and baseplate. Apply thermal grease evenly to the inner cover. Place the heat sink on the grease and gently press for 3-5 minutes. S5. Secure the cooling fan to the heat sink rib using clips. S6. First weld the ribs, seam plates, and wall plates, then weld the ring plates and butt welds. S7. Use two workstations for symmetrical welding to ensure synchronous growth of welding volume.

7. The method for using the anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 6, characterized in that: In step S1, the gap of the butt weld of the inner end cover is ≤2 mm.

8. The method for using the anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 6, characterized in that: In step S7, the moving speed of the welding gun and the welding parameters of the symmetrical welding are kept consistent.

9. The method for using the anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 6, characterized in that: In step S4, the bottom plate of the heat dissipation device conforms to the ring plate, conical wall plate or joint plate of the inner end cover.

10. The method for using the anti-deformation device for welding the inner end cover of a steam turbine generator according to claim 6, characterized in that: In the step S4, the heat dissipation device is placed between adjacent ribs and ribs, and between ribs and joint plates.

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