Welding tool and method for large titanium alloy T-shaped rib plate structure

Abstract

The invention provides a welding tool and method for a large titanium alloy T-shaped rib plate structure. The tool comprises a pressing plate, stand columns, fixing bolts and compression bolts, the pressing plate is connected with a to-be-welded plate through the fixing bolts, the two ends of the pressing plate are connected with the top ends of the stand columns through the compression bolts correspondingly, and the bottom ends of the stand columns are connected with a welding platform through the fixing bolts; the number of the pressing plates is n, the number of the stand columns is 2n, and n is a positive integer and is larger than or equal to 2. By means of the welding tool and method for the large titanium alloy T-shaped rib plate structure, the flexible tool suitable for stirring friction flexible welding of T-shaped fillet welds of workpieces with different thicknesses can be prepared, the structure of the tool is simplified, the universality of the tool is improved, the cost of the tool is reduced, and the welding quality and the qualified rate of products are improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal material welding, and in particular to a friction stir welding tool and method for a large titanium alloy T-shaped rib plate structure. Background Art

[0002] Titanium alloy has become the first choice for key and important parts of aerospace that pursue lightweight structures and harsh service conditions due to its advantages such as low density, high specific strength, good corrosion resistance and good toughness. T-joint is a commonly used welding joint. According to its structural form and characteristics, it is widely used in aerospace, petrochemical, vehicle and agricultural equipment, port lifting machinery, ships, bridges, pressure vessels and pipeline support structures. In aerospace and defense industry structural parts, in order to meet the requirements of light weight and high strength, lightweight structures are widely used, especially thin-walled reinforcement rib structures and skeleton skin structures instead of full solid structures, which greatly reduces the weight of components. T-joints are increasingly needed in such industrial structural parts, and higher requirements are placed on the welding process of T-joints.

[0003] At present, the welding methods of titanium and titanium alloys mainly include non-melting electrode tungsten inert gas welding (TIG), metal arc welding (MIG), plasma arc welding and laser welding.

[0004] Tungsten inert gas welding (TIG) is a welding method that uses tungsten rods as electrodes under argon protection. In order to prevent the air from having a harmful effect on the tungsten electrode, the molten pool and the adjacent heat-affected zone during welding, the argon gas continuously ejected from the nozzle of the welding gun is used to form a gas protection layer around the arc to isolate the air, thereby obtaining an excellent weld. The welding process can selectively add or not add filler wire according to the specific requirements of the process. The structure and size of the nozzle will have a great impact on the welding quality. Due to the poor thermal conductivity of titanium and its alloys, slow heat dissipation, long high-temperature residence time, and the strong activity of titanium, the diameter of the nozzle should be larger, generally 16-18mm. The distance from the nozzle to the workpiece should be smaller. In order to improve the protection effect, ensure visibility and accessibility of the welding torch, a double-layer airflow-protected welding torch can also be used. For titanium alloy weldments with a thickness greater than 1.0mm, the nozzle is not enough to protect the high-temperature metal in the weld and near-weld area. Generally, a drag shield is required. The width of the drag shield is generally 25-60mm, and the length of the drag shield for manual welding is generally 40-100mm. For ease of operation, the nozzle and the drag shield can be made into one piece. The length of the drag shield for automatic welding is generally 60-200mm, depending on the thickness of the weldment. The drag shield for thin weldments is generally shorter, and the drag shield for thick weldments is longer. A flat drag shield is used for welding straight seams, and an arc drag shield is used for circumferential seams. In order to reduce the coarse grains caused by overheating of titanium alloy welded joints, improve the plasticity of the joints, reduce welding deformation and reduce assembly precision requirements, pulse welding can be used. The pulse frequency is generally 2-5Hz. With this process, when the plate thickness is 0.5mm, the deformation can be reduced by 30%, and when it is 2.0mm, it can also be reduced by about 15%. Therefore, it is not difficult to see that when using argon arc welding, different drag covers need to be replaced for T-joints of different thicknesses, which can easily reduce welding efficiency and cause problems such as more complicated welding structures.

[0005] The metal arc welding (MIG) is a welding method that uses the arc between the continuously fed fusible welding wire and the workpiece to be welded as a heat source to melt the welding wire and the base metal to form a molten pool and a weld. In order to obtain a good weld, an external gas should be used as an arc medium to protect the molten droplet, the molten pool metal and the high-temperature metal in the welding area from the harmful effects of the surrounding air. The MIG welding of titanium alloys uses a titanium bare electrode wire instead of a tungsten rod electrode to be continuously supplied from the welding torch. The arc is between the wire end and the base metal, and its heat energy melts the wire and the base metal, thereby welding. Compared with tungsten inert gas welding, this method has a larger thermal power and is used for welding medium-thickness products. It can reduce the number of welding layers, increase welding speed and production efficiency, and reduce costs. The main disadvantage of this method is the spatter problem, which will affect the weld formation and welding protection. In addition, it is easy to produce pores, so the welding speed cannot be too fast. The key to MIG welding lies in the welding wire, welding speed, welding current, number of welds, welding sequence and shielding gas flow. Short-circuit transition is suitable for welding thinner parts, while spray transition is suitable for welding thicker parts. Since there are more filler wires in melting electrode welding, the welding groove angle is generally larger, and the plate with a thickness of 15-25ram is generally selected to be 90. Single-sided V-shaped groove or no groove, leaving a gap of 1-2mm and welding one on each side. The drag hood of tungsten inert gas arc welding can also be used for melting electrode welding, but due to the higher welding speed and longer high temperature zone, the drag hood should be appropriately enlarged and cooled with running water.

[0006] In addition, the laser welding process is a heat conduction type, that is, the laser radiates to the surface of the workpiece, and the heat diffuses into it through heat conduction. The metal melts and then cools to form a weld. During laser welding, there is no need for particularly high energy density to gasify the workpiece material, only melting and bonding. Dual laser beam double-sided synchronous welding technology can effectively make up for the above defects and realize lightweight, efficient and low-cost manufacturing of T-shaped structures. The uneven temperature field during welding will lead to the generation of residual stress, which seriously affects the performance of the welded joint and even causes stress corrosion cracking and fracture, greatly reducing the service life of the weldment.

[0007] As a solid phase welding technology, friction stir welding is very suitable for titanium alloy welding, with dense structure, small welding deformation and high dimensional accuracy. Since the workpiece needs a solid back support during friction stir welding, the tooling used for melting welding of fillet welds in existing patents is not suitable for friction stir welding. For friction stir welding of fillet welds, most of the existing technologies are realized by adding process pads and converting them into measures similar to flat butt welding. However, this tooling is very likely to cause defects such as incomplete penetration and weak connection in the weld area, and the utilization rate of process pads is low. The welding of the inner and outer fillet welds usually requires two sets of tooling to be implemented separately, which is costly. At present, there are no relevant patents for special tooling for friction stir welding of fillet welds. Therefore, it is of great significance to study how to prepare flexible tooling for friction stir welding of T-shaped fillet welds suitable for workpieces of different thicknesses, simplify the structure of the tooling, improve the versatility of the tooling, reduce the cost of the tooling, and improve the welding quality and qualified rate of the product.

[0008] In the patent publication number CN106475677A, a T-type friction stir welding device and welding method for dissimilar alloys with slots are proposed, which is specially used for clamping and fixing the rib plate for friction stir welding, mainly including a supporting fixture, a rib plate and a stirring head. The rib plate is made by welding a thin plate and a rib bar, and an open slot is provided on the rib bar joint surface. The open slot is used for filling powder. The principle is to use an in-situ mixing reaction method, through mechanical stirring and friction heat generation of the open slot filled with powder, to promote the powder to be dispersed and distributed in the weld core area, thereby obtaining better weld joint organization and mechanical properties. However, due to the complex structure of the device, it requires the coordination of multiple components, which easily leads to the problem of high cost. Summary of the invention

[0009] In view of this, the present invention aims to propose a welding tool and method for a large titanium alloy T-shaped rib plate structure, so as to solve the problems that the tooling in the prior art cannot realize the flexible stir friction welding of T-shaped corner welds suitable for workpieces of different thicknesses, and the tooling structure is complex, the cost is high, and the versatility is low; thereby achieving the goal of being able to prepare a flexible tooling for the flexible stir friction welding of T-shaped corner welds suitable for workpieces of different thicknesses, and simplifying the structure of the tooling, improving the versatility of the tooling, reducing the cost of the tooling, and improving the welding quality and pass rate of the products.

[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0011] The present invention relates to a welding tool and method for a large titanium alloy T-shaped rib plate structure. The welding tool comprises a pressure plate, a column, a fixing bolt and a clamping bolt. The pressure plate is connected to a plate to be welded by the fixing bolt, the two ends of the pressure plate are respectively connected to the top of the column by the clamping bolts, and the bottom of the column is connected to a welding platform by the fixing bolts. The number of pressure plates is n, and the number of columns is 2n, where n is a positive integer and n≥2.

[0012] Furthermore, the pressure plate includes a left end, a middle section and a right end, the left end is connected to the right end through the middle section, the left end and the right end are respectively connected to the top of the column at the corresponding position through clamping bolts, and the middle section is connected to the plate to be welded through the clamping bolts.

[0013] Furthermore, end threaded holes are arranged on the left end portion and the right end portion, and the end threaded holes are arranged through the left end portion and the right end portion.

[0014] Furthermore, a plate threaded hole is arranged on the middle section, and the plate threaded hole is arranged through the middle section.

[0015] Furthermore, the plate body is provided with m threaded holes, where m is a positive integer.

[0016] Furthermore, the m plate body threaded holes are evenly arranged in a linear arrangement on the middle section, and the interval between two adjacent plate body threaded holes is L, where L is a positive number.

[0017] Furthermore, countersunk grooves are provided at the bottom of the left end and the right end, and the countersunk grooves are respectively provided at the positions corresponding to the connection between the left end and the right end and the column.

[0018] Furthermore, the column includes a countersunk bolt hole and a column threaded hole; the countersunk bolt hole and the column threaded hole are both arranged on the column.

[0019] Furthermore, n=2, two pressure plates are provided, and four columns are provided; both ends of the two pressure plates are connected to corresponding columns respectively, and opposite sides of the two pressure plates are beveled, and the slope is α degrees, where α is a positive number.

[0020] A friction stir welding method for a large titanium alloy T-shaped rib plate structure, the method is applied to a welding tool for a large titanium alloy T-shaped rib plate structure, the method comprises the following steps:

[0021] Step 1: Fix the plates to be welded: place the plates to be welded, i.e. the web and face plate of the T-shaped rib plate structure, in the tooling in order and fix them;

[0022] Step 2: Heat source assisted friction stir welding: an auxiliary heat source is arranged in front of the stirring head, and the stirring head is preheated under the action of the auxiliary heat source, and then the stirring head is pressed into the connection between the web and the face plate under the protection of inert gas to perform friction stir welding;

[0023] Step 3: After welding is completed, the required T-shaped rib plate structure is obtained. The T-shaped rib plate structure is taken out from the tooling, the next plate to be welded is selected, and the process returns to step 1.

[0024] Compared with the prior art, the welding tool and method of a large titanium alloy T-shaped rib plate structure described in the present invention have the following beneficial effects:

[0025] By setting the tool, the preparation requirements of flexible tool for T-shaped fillet stir friction flexible welding of workpieces of different thicknesses can be achieved, and the structure of the tool can be simplified, the versatility of the tool can be improved, the cost of the tool can be reduced, and the welding quality and qualified rate of the product can be improved. By setting the method, the stability of the welding process can be enhanced and the reliability of the welding quality can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention. In the accompanying drawings:

[0027] Figure 1 It is a schematic diagram of a top view (from top to bottom) of a welding tool;

[0028] Figure 2 This is a schematic diagram of the main view (from front to back) of the welding tool;

[0029] Figure 3 A schematic diagram of a top view of a connecting column;

[0030] Figure 4 It is a schematic diagram of the positional relationship between the T-shaped rib plate fillet weld and the welding tooling during the welding process;

[0031] Figure 5 This is a first-person perspective diagram of the pressing plate after it is beveled;

[0032] Figure 6 This is a schematic diagram of the second viewing angle after the pressing plate is beveled;

[0033] Figure 7 This is a schematic diagram of the overall structure of the column.

[0034] Explanation of the reference numerals: 1. Pressing plate; 11. Left end; 12. Middle section; 13. Right end; 14. End threaded hole; 15. Plate threaded hole; 2. Column; 21. Countersunk bolt hole; 22. Column threaded hole; 3. Fixing bolt; 4. Clamping bolt. DETAILED DESCRIPTION

[0035] The inventive concepts of the present disclosure will be described below using terms commonly used by those skilled in the art to convey the essence of their work to other persons skilled in the art. However, these inventive concepts can be embodied in many different forms and should not be considered limited to the embodiments described herein.

[0036] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0039] In order to solve the problems that the tooling in the prior art cannot be applied to the friction stir welding of T-shaped fillet welds of workpieces of different thicknesses, and the tooling structure is complex, the cost is high, and the versatility is low; this embodiment proposes a welding tooling and method for a large titanium alloy T-shaped rib plate structure, wherein the welding tooling for a large titanium alloy T-shaped rib plate structure includes a pressure plate 1, a column 2, a fixing bolt 3, and a clamping bolt 4. The pressure plate 1 is connected to the plate to be welded by the fixing bolt 3, and the two ends of the pressure plate 1 are respectively connected to the top of the column 2 by the clamping bolt 4, and the bottom of the column 2 is connected to the welding platform by the fixing bolt 3. There are n pressure plates 1 and 2n columns 2, where n is a positive integer and n≥2. Among them, the plate to be welded is a T-shaped rib plate structure, which includes a web and a panel, and the web and the panel are spliced ​​to form a T-shaped rib plate structure.

[0040] Through the setting of the tooling, the preparation requirements of flexible tooling for flexible friction stir welding of T-shaped fillet welds suitable for workpieces of different thicknesses can be met. The structure of the tooling can also be simplified, the versatility of the tooling can be improved, the cost of the tooling can be reduced, and the welding quality and pass rate of the products can be improved.

[0041] The pressing plate 1 includes a left end portion 11, a middle section 12 and a right end portion 13, and the left end portion 11, the middle section 12 and the right end portion 13 are integrally formed. Specifically, the left end portion 11 is connected to the right end portion 13 through the middle section 12, and the left end portion 11 and the right end portion 13 are respectively connected to the top of the column 2 at the corresponding position through the clamping bolt 4, and the middle section 12 is connected to the plate to be welded through the clamping bolt 4.

[0042] Among them, end threaded holes 14 are provided on the left end portion 11 and the right end portion 13, and the end threaded holes 14 are provided through the left end portion 11 and the right end portion 13. The provision of the end threaded holes 14 is conducive to achieving a reliable connection between the pressure plate 1 and the column 2, and is also conducive to ensuring the firmness of the overall tooling. Plate threaded holes 15 are provided on the middle section 12, and the plate threaded holes 15 are provided through the middle section 12. The plate threaded holes 15 are provided in m numbers, where m is a positive integer. The m plate threaded holes 15 are evenly arranged in a linear arrangement on the middle section 12, and the interval between two adjacent plate threaded holes 15 is L, where L is a positive number. Preferably, L is 100 mm. The provision of the plate threaded holes 15 is used to facilitate the subsequent tightening of the plate to be welded during welding, and to improve the tightness between the tooling and the plate to be welded during the welding process.

[0043] In addition, countersunk grooves are provided at the bottom of the left end 11 and the right end 13, and the countersunk grooves are respectively provided at the positions corresponding to the connection between the left end 11 and the right end 13 and the column 2. The size of the countersunk groove is a1×b1, and the size of the top of the column 2 is a2×b2. a1 and a2 are both lengths, b1 and b2 are both widths, a1, a2, b1, and b2 are all positive numbers, wherein a1=a2+c, b1=b2+c, and c is the size difference. In this embodiment, c is 1±dmm, d is a positive number, and d is the size deviation value.

[0044] The setting of the countersunk groove can greatly improve the installation efficiency of the tooling on the one hand, and on the other hand, the setting of the pressure plate countersunk head can not only improve the connection integrity between the pressure plate 1 and the column 2, but also effectively increase the rigidity and stability of the overall tooling.

[0045] The column 2 includes a countersunk bolt hole 21 and a column threaded hole 22. The countersunk bolt hole 21 and the column threaded hole 22 are both arranged on the column 2. The countersunk bolt hole 21 is arranged at the center position of the cross section of the column 2. The nut of the fixing bolt 3 is embedded in the end of the countersunk bolt hole 21 away from the welding platform, and the screw rod of the fixing bolt 3 is connected or separated from the welding platform through the countersunk bolt hole 21 in a rotatable manner. The column threaded holes 22 are evenly distributed along the circumference of the top of the column 2 with the countersunk bolt hole 21 as the center. The end of the screw rod of the clamping bolt 4 away from the nut is rotatably fitted or separated from the inner side of the column threaded hole 22 of the column 2 through the end threaded holes 14 at both ends of the pressure plate 1. In this embodiment, the center position refers to the position where the column axis of the column 2 is located.

[0046] The coordinated arrangement of the countersunk bolt hole 21 and the column threaded hole 22 facilitates effective connection between the column 2 and the welding platform, and the countersunk connection method can ensure that the fixing bolt 3 is entirely below the upper surface of the column 2, avoiding affecting the connection and installation between the column 2 and the pressure plate 1.

[0047] Preferably, n=2, two pressing plates 1 are provided, and four columns 2 are provided. The two ends of the two pressing plates 1 are respectively connected to the corresponding columns 2, and the four columns 2 are connected to the welding platform by fixing bolts 3. The tops of the four columns 2 form a mounting platform for facilitating the installation of the pressing plates 1. There is a certain gap between the two pressing plates 1. The opposite sides of the two pressing plates 1 are beveled, and the slope is α degrees, α is a positive number, and the specific value of α is set according to the needs.

[0048] The mutual coordination of the two pressure plates 1 facilitates the observation of the friction stir welding process, and the beveling treatment helps to improve the convenience of observing the welding degree during the welding process.

[0049] In addition, when welding a T-shaped fillet weld, a resistance heating rod is set near the weld using the special tooling for the fillet weld, which effectively increases the heating temperature of the fillet weld position of the plate to be welded and increases the plastic deformation capacity during welding; the tooling is fixed by fixing bolts 3 and the welding platform to ensure that the welding position is a flat surface.

[0050] When welding a T-shaped fillet weld, place the web of the plate to be welded in a special tooling for fillet welds, with the upper surface of the web 0.5mm-1mm higher than the plane of the special tooling for fillet welds, then place the panel of the plate to be welded, and clamp the plate to be welded by the clamping bolts 4 on the clamping plate 1, and then weld. After welding is completed, take out the welded T-shaped structure from the special tooling for fillet welds, move it to the next welding position, put a new web of the plate to be welded in the special tooling for fillet welds, and start welding a new T-shaped fillet weld, and repeat the clamping and welding process.

[0051] A method for friction stir welding of a large titanium alloy T-shaped rib plate structure, the method being applied to a welding tool for the large titanium alloy T-shaped rib plate structure, the method comprising the following steps:

[0052] Step 1: Fix the plates to be welded: place the plates to be welded, i.e. the web and face plate of the T-shaped rib plate structure, in the tooling in order and fix them;

[0053] Step 2: Heat source assisted friction stir welding: an auxiliary heat source is arranged in front of the stirring head, and the stirring head is preheated under the action of the auxiliary heat source, and then the stirring head is pressed into the connection between the web and the face plate under the protection of inert gas to perform friction stir welding;

[0054] Step 3: After welding is completed, the required T-shaped rib plate structure is obtained. The T-shaped rib plate structure is taken out from the tooling, the next plate to be welded is selected, and the process returns to step 1.

[0055] Wherein, the auxiliary heat source in step 2 includes any one of an arc heat source or a laser heat source.

[0056] Through the coordinated setting of tooling and methods, the problem that stir friction welding cannot be achieved for large titanium alloy T-shaped rib plate structures can be solved. At the same time, the tooling setting can realize fast and efficient welding of large titanium alloy structures, effectively reducing the difficulty of clamping. Through the effective combination of auxiliary heat source and stir friction welding, solid phase welding of thick titanium alloys can be achieved, which greatly improves the welding efficiency and enables the welding tooling to weld plates of different thicknesses to be welded; prolongs the service life of the stirring head during welding, avoids welding defects caused by wear of the stirring head during welding, and improves the welding quality; it can also enhance the stability of the welding process and improve the reliability of the welding quality.

[0057] In addition, step one includes:

[0058] Step S11: firstly put the plate to be welded, i.e. the web of the T-shaped rib plate structure, into the tooling and fix it;

[0059] Step S12: Place the panel of the plate to be welded in the tooling, and fix it between the pressing plate 1 and the welding platform by means of the clamping bolts 4 .

[0060] The setting of the tooling can help increase the stability and reliability of the plates to be welded placed in the tooling, improve the safety of the welding process, and improve the efficiency of welding.

[0061] Step 2 includes:

[0062] Step S21: adjusting the setting position between the auxiliary heat source and the stirring needle according to the thickness of the plate to be welded;

[0063] Step S22: adjusting the distance between the auxiliary heat source and the stirring needle according to the preset welding power;

[0064] Step S23: Before welding, the stirring needle is preheated by an auxiliary heat source, and then, under the protection of an inert gas, the stirring needle is pressed into the connection between the web and the face plate to perform friction stir welding.

[0065] By setting up heat source-assisted friction stir welding, the flow plasticity of titanium alloy can be provided during the welding process. In addition, an arc or laser is set in front of the stirring head as an auxiliary heat source for preheating, and then friction stir welding is performed. This can greatly reduce the welding difficulty during lap welding, while ensuring that the lap interface between the web and face plate of the plate to be welded achieves good metallurgical bonding, effectively avoiding the occurrence of welding defects.

[0066] Wherein, in step S23, during welding, the friction stir welding process is performed after the preheating temperature reaches above 400°C. The flow rate of the shielding gas of the inert gas is in the range of 10L / min-30L / min, and the purity of the inert gas is 99.999%. Preferably, the inert gas is argon. The depth of the stirring needle pressed into the web is in the range of 2mm-3mm.

[0067] The effective protection of the inert gas during the entire welding process can improve the reliability and safety of welding. By setting the depth of the stirring needle pressed into the web, it is possible to achieve a good interface metallurgical bonding while ensuring full penetration of the panel and the web, avoiding the occurrence of welding defects such as lack of fusion. Through the effective coupling of the auxiliary heat source arc and stir friction welding, efficient and high-quality stir friction welding of titanium alloys can be achieved.

[0068] Step S21 includes:

[0069] Step S211: determine whether the thickness of the plate to be welded is less than 6 mm, if yes, execute step S212; if no, execute step S213;

[0070] Step S212: setting the auxiliary heat source and the stirring needle on the same welding axis, and executing step S22;

[0071] Step S213: Determine whether the thickness of the plate to be welded is between 6 mm and 8 mm. If yes, execute step S214; if no, execute step S215;

[0072] Step S214: setting the auxiliary heat source and the stirring needle on different parallel welding axes, and the distance between the two welding axes is within 1 mm;

[0073] Step S215: The auxiliary heat source and the stirring needle are arranged on different parallel welding axes, and the distance between the two welding axes is between 1 mm and b mm, where b is a positive number. In this embodiment, the specific value of b is set as required.

[0074] Step S22 includes:

[0075] Step S221: determine whether the thickness of the plate to be welded is less than 6 mm, if yes, execute step S222, if no, execute step S223;

[0076] Step S222: determining whether the preset welding preheating power is greater than 1000 watts, if yes, setting the distance between the auxiliary heat source and the stirring needle to be greater than 8 mm; if no, setting the distance between the auxiliary heat source and the stirring needle to be less than 8 mm;

[0077] Step S223: Determine whether the thickness of the plate to be welded is between 6 mm and 8 mm. If yes, execute step S224; if no, execute step S225;

[0078] Step S224: determining whether the preset welding preheating power is greater than 1200 watts, if yes, setting the distance between the auxiliary heat source and the stirring needle to be greater than 8 mm; if no, setting the distance between the auxiliary heat source and the stirring needle to be less than 8 mm;

[0079] Step S225: Determine whether the preset welding preheating power is greater than W watts. If yes, set the distance between the auxiliary heat source and the stirring needle to be greater than 8 mm; if no, set the distance between the auxiliary heat source and the stirring needle to be less than 8 mm. W is a positive number, and the specific value of W is set as required.

[0080] By judging the thickness of the plate to be welded and the preset preheating power, and then adjusting the position between the auxiliary heat source and the stirring needle, the efficiency of the auxiliary heat source preheating can be improved when welding plates of different thicknesses, shortening the welding cycle, reducing the welding cost, and ensuring the welding quality. Example 1

[0081] For a large TC4 titanium alloy T-shaped rib plate structure with a thickness of 6mm, a length of 1000mm and a width of 1200mm, the two opposite sides of the two pressure plates 1 in the welding fixture are beveled, α=60 degrees. The size difference between the countersunk groove and the top size of the column 2 is c=1mm. The heating groove is 10mm away from the edge of the fixture. The upper surface of the web of the plate to be welded is 0.5mm higher than the installation plane of the special fixture for the fillet weld.

[0082] The specific welding methods are as follows:

[0083] During welding, the position between the auxiliary heat source arc and the stirring needle is adjusted according to the thickness of the welding plate. For the 6mm plate to be welded, the auxiliary heat source arc and the stirring needle are on the same welding axis, the welding preheating power is 1000 watts, and the distance between the two is 8mm. During welding, the auxiliary heat source arc is preheated first, and stir friction welding begins after reaching 450℃. The whole welding process is protected by inert gas, the protective gas flow rate is 20L / min, and the protective gas is argon with a purity of 99.999%. The top of the stirring head is pressed into the web to a depth of 2mm, which can achieve good interface metallurgical bonding while ensuring that the panel and the web are fully welded, avoiding the generation of welding defects such as unfusion. Through the effective coupling of the auxiliary heat source arc and stir friction welding, efficient and high-quality stir friction welding of titanium alloys is achieved. The welding speed can reach more than 30mm / min, without welding defects, while ensuring that the joint tensile and impact toughness meet the use requirements.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A welding tool for a large titanium alloy T-shaped rib plate structure, characterized in that: The invention comprises a pressing plate (1), a column (2), a fixing bolt (3) and a clamping bolt (4); the pressing plate (1) is connected to the plate to be welded via the fixing bolt (3); both ends of the pressing plate (1) are respectively connected to the top of the column (2) via the clamping bolt (4); and the bottom of the column (2) is connected to the welding platform via the fixing bolt (3); n pressing plates (1) are provided, and 2n columns (2) are provided, where n is a positive integer and n≥2.

2. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 1, characterized in that: The pressing plate (1) comprises a left end portion (11), a middle section (12) and a right end portion (13); the left end portion (11) is connected to the right end portion (13) via the middle section (12); the left end portion (11) and the right end portion (13) are respectively connected to the top ends of the columns (2) at corresponding positions via clamping bolts (4); and the middle section (12) is connected to the plate to be welded via the clamping bolts (4).

3. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 2, characterized in that: The left end portion (11) and the right end portion (13) are both provided with end threaded holes (14), and the end threaded holes (14) penetrate the left end portion (11) and the right end portion (13).

4. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 2, characterized in that: The middle section (12) is provided with a plate body threaded hole (15), and the plate body threaded hole (15) is provided through the middle section (12).

5. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 4, characterized in that: The plate body threaded holes (15) are arranged in m number, where m is a positive integer.

6. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 5, characterized in that: The m plate body threaded holes (15) are evenly arranged on the middle section (12) in a linear arrangement, and the interval between two adjacent plate body threaded holes (15) is L, where L is a positive number.

7. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 2, characterized in that: The bottoms of the left end (11) and the right end (13) are both provided with countersunk grooves, and the countersunk grooves are respectively provided at positions corresponding to the connection between the left end (11) and the right end (13) and the column (2).

8. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 1, characterized in that: The column (2) comprises a countersunk bolt hole (21) and a column threaded hole (22); the countersunk bolt hole (21) and the column threaded hole (22) are both arranged on the column (2).

9. The welding tool for a large titanium alloy T-shaped rib plate structure according to claim 1, characterized in that: The n=2, two pressing plates (1) are provided, and four upright posts (2) are provided; the two ends of the two pressing plates (1) are respectively connected to the corresponding upright posts (2), and the opposite sides of the two pressing plates (1) are both beveled, and the bevel is α degrees, where α is a positive number.

10. A friction stir welding method for a large titanium alloy T-shaped rib plate structure, characterized in that: The method is applied to a welding tool for a large titanium alloy T-shaped rib plate structure according to any one of claims 1 to 9, and the method comprises the following steps: Step 1: Fix the plates to be welded: place the plates to be welded, i.e. the web and face plate of the T-shaped rib plate structure, in the tooling in order and fix them; Step 2: Heat source assisted friction stir welding: an auxiliary heat source is arranged in front of the stirring head, and the stirring head is preheated under the action of the auxiliary heat source, and then the stirring head is pressed into the connection between the web and the face plate under the protection of inert gas to perform friction stir welding; Step 3: After welding is completed, the required T-shaped rib plate structure is obtained. The T-shaped rib plate structure is taken out from the tooling, the next plate to be welded is selected, and the process returns to step 1.

Images