High-efficiency electron beam welding method for long and short intersection weld structure of t-shaped cross section

Abstract

The present application belongs to the technical field of aircraft structure manufacturing, and proposes a high-efficiency electron beam welding method for T-shaped section long-short intersection weld structure. The T-shaped section long-short intersection weld structure is clamped and vacuumed once, and the welding of two welds is completed; the welding sequence of the T-shaped section long-short intersection weld structure is long first and short later; according to the cooperation of the double-weld welding tooling and the tooling indexing mechanism, the long weld is ensured to be welded in a horizontal state, and the short weld is ensured to be welded in a vertical state; after the welding of the two welds, further optimization processing is carried out to obtain the required parts. The present application eliminates the instability and quality risks of the welding process caused by twice clamping, reduces the once disassembly and once clamping, reduces the labor intensity of the welding process, and reduces the level of manual intervention. The two welds of the part are welded by using a longitudinal gun and a transverse gun respectively, the influence of gravity on the molten pool can be eliminated when the electron beam is transversely welded, and compared with longitudinal welding, the heat input of the part can be reduced and the internal stress level of the part can be reduced.

Description

Technical Field

[0001] This invention relates to the field of aircraft structural component manufacturing technology, and in particular to a highly efficient electron beam welding method for a T-shaped cross-section structure with intersecting long and short weld seams. Background Technology

[0002] Aerospace load-bearing structural components are mostly manufactured using high-strength steel. Due to the high density and large mass of high-strength steel, and considering the need for aircraft weight reduction, these components are characterized by numerous semi-enclosed weight-reduction cavities and complex structures. To improve processing efficiency, reduce economic costs, and simplify processing, they are often designed as welded structures. Electron beam welding, due to its advantages and characteristics such as high energy density, strong penetration, relatively small welding deformation, and high degree of automation, has been widely used in the welding of aerospace structural components. The T-shaped cross-section with intersecting long and short welds is initially divided into left and right parts, connected by two welds to form a whole, with the two welds intersecting in a T-shape from the cross-sectional direction. The following problems exist in the actual production process of this structure:

[0003] 1) Due to the limited space of the two weld seams and the size of the electron beam vacuum chamber, it is necessary to use two different sets of tooling to position and weld a part. The entire process involves two assembly, disassembly, cleaning, vacuuming and heat preservation processes, resulting in low welding efficiency, long processing cycle, high cost, high labor intensity for workers and a lot of manual intervention.

[0004] 2) In the actual welding process, the tooling needs to be changed when welding the two welds. When the first weld is removed from the corresponding tooling after electron beam welding, the stress state inside the part changes. The part with the changed stress state and deformation is then clamped again for electron beam welding of the second weld. There is a risk that the welding deformation may cause the design requirements to be unmet.

[0005] 3) The stress release, deformation, and changes in stress state caused by repeated clamping can affect the mating state and internal stress level of the second weld before welding, often resulting in incomplete fusion defects and a high tendency to crack after the second weld, seriously affecting the welding quality of the part. After incomplete fusion defects occur, repairs are carried out according to relevant standards. However, the heat input during the repair welding process further intensifies the internal stress and deformation of the part, and in severe cases, the part may be scrapped.

[0006] 4) For the welding process, the greater the weld thickness of the part, the greater the heat input required during welding, and the greater the deformation. When welding with an electron beam longitudinal spot gun along a direction perpendicular to the ground plane, the weld pool is affected by gravity, which hinders the maintenance of the keyhole in the electron beam weld pool, resulting in a reduction in the penetration ability of the electron beam weld. Therefore, electron beam longitudinal welding requires a greater heat input than electron beam transverse welding to achieve the same weld penetration depth. This additional heat input will further aggravate the welding deformation of the part.

[0007] Therefore, for T-section structures with intersecting long and short weld seams, there is an urgent need to develop a more efficient, stable, reliable, and precise electron beam welding method that can control welding deformation, reduce cracking tendency, minimize welding defects, and lower the risk of component scrap. This method would solve the problems of long cycle time, low efficiency, high labor intensity for workers, severe deformation, and easy generation of welding defects, improve the electron beam welding efficiency and precision of components, and provide a technical solution for electron beam welding of similar aerospace structural components. Summary of the Invention

[0008] To overcome and solve the aforementioned technical problems of long welding cycles, low production efficiency, high manual intervention, high processing costs, risk of scrapping due to deformation exceeding tolerances, high post-weld stress levels, and susceptibility to welding defects in T-section long-short intersecting weld structures for aerospace applications, this invention provides a highly efficient electron beam welding method for T-section long-short intersecting weld structures. This method enables welding of both welds in a single clamping and vacuuming operation, controls welding deformation of the T-section long-short intersecting weld structure, reduces worker labor intensity during welding, minimizes manual intervention, and doubles the efficiency of electron beam welding, fully utilizing equipment capacity. Simultaneously, it reduces the risk of defects such as incomplete fusion and cracks, reduces welding deformation and lowers internal stress levels, calculates and eliminates defect areas at the intersection of the two welds, significantly reducing their impact on the structural strength of the part and improving its service life.

[0009] The technical solution of this invention is as follows: A highly efficient electron beam welding method for a T-shaped cross-section long and short intersecting weld structure, wherein the T-shaped cross-section long and short intersecting weld structure is clamped and vacuumed in one operation to complete the welding of two welds; the welding sequence of the T-shaped cross-section long and short intersecting weld structure is long weld first and short weld second; according to the cooperation of the double weld welding fixture 4 and the fixture rotation mechanism 5, the long weld 1 is welded in a horizontal state and the short weld 2 is welded in a vertical state; after the two welds are welded, further optimization processing is performed to obtain the required part.

[0010] The angle between the short weld 2 and the long weld 1 was measured using 3D modeling software and is defined as A.

[0011] When A = 90°, the electron beam vacuum chamber turntable is used to directly rotate and weld the two weld seams of the part during the welding process; when welding the long weld seam 1, the double weld seam welding fixture 4 is placed horizontally, with the weld seam horizontal along the X-axis of the electron beam welder and the surface to be welded facing the positive direction of the Z-axis of the electron beam welder; when welding the short weld seam 2, the orientation is vertical along the Z-axis, with the surface to be welded facing the negative direction of the Y-axis of the electron beam welder.

[0012] In most T-section structures with intersecting long and short weld seams, the included angle A between the two weld seams is not exactly 90°. This necessitates the design of a welding fixture indexing mechanism to change the welding posture of the two weld seams during the welding process. When A < 90°, the double weld seam welding fixture 4 and the fixture indexing mechanism 5 work together to adjust the posture of the short weld seam 2 to a vertical posture during welding. During the welding process, the electron beam vacuum chamber turntable and the fixture indexing mechanism 5 work together to achieve the indexing and welding of the two weld seams of the part.

[0013] When welding the long weld 1, the double weld welding fixture 4 is placed horizontally, with the long weld 1 horizontally along the X-axis of the electron beam welder and the surface to be welded facing the positive Z-axis of the electron beam welder. When welding the short weld 2, the fixture indexing mechanism 5 adjusts the double weld welding fixture 4 to a horizontal tilt angle B, where B = (90° - A). The short weld 2 is vertical along the Z-axis, with the surface to be welded facing the negative Y-axis of the electron beam welder.

[0014] The double-weld welding fixture 4 includes a positioning pin 9, a lateral floating head positioning mechanism 10, and a web floating head positioning mechanism 11. The positioning pin 9 is installed at one end of the bottom surface of the double-weld welding fixture 4, and the lateral floating head positioning mechanisms 10 are installed on both sides of the bottom surface. The web floating head positioning mechanism 11 is installed above the structure to be welded. The diameter of the positioning pin 9 is set according to the aperture size of the structure to be welded, and it is used to connect and position the structure to be welded and the double-weld welding fixture 4, restricting the four degrees of freedom of the structure to be welded. Two lateral floating head positioning mechanisms 10 are symmetrically arranged on both sides of the weld section of the structure to be welded, with a spacing of 100-150mm. Two web floating head positioning mechanisms 11 are used to press the web of the structure to be welded, distributed on both sides of the long weld 1, with a spacing of 100-150mm, and the spacing between the web floating head positioning mechanisms 11 on both sides of the weld is 10-20mm.

[0015] According to the relevant requirements of the electron beam welding standard for the structural materials to be welded, the structure to be welded is ground, cleaned, and fitted; check whether the magnetic flux of the structure to be welded and the double weld welding fixture 4 meets the relevant standard requirements. If not, demagnetize it; install the demagnetized and cleaned structure to be welded onto the double weld welding fixture 4. First, perform pre-assembly, using the positioning pin 9 to position the two parts of the structure to be welded, and clamp it through the lateral floating head positioning mechanism 10; check the weld gap and misalignment according to the electron beam welding standard. After passing the inspection, use manual argon arc welding to position the welding pad and arc-starting plate required for welding the two welds; then perform formal assembly, clamping all positioning and limiting mechanisms.

[0016] The operation steps for clamping the lateral floating head positioning mechanism 10 and the web floating head positioning mechanism 11 are as follows: first, place the floating heads on both sides at the maximum stroke position, and then rotate them synchronously to make the floating heads on both sides fit with the parts. From the time the floating heads fit together to the final clamping process, the number of rotations of each floating head does not differ by more than 1 / 5 of a rotation.

[0017] The tooling shifting mechanism 5 consists of two blocks, respectively installed on both sides of one end of the bottom surface of the double weld seam welding fixture 4, located on the side of the short weld seam 2. The tooling shifting mechanism 5 includes a mutually perpendicular shifting mechanism engraving observation surface G6 and a shifting mechanism positioning surface F7. The shifting mechanism positioning surface F7 is in contact with the worktable surface of the electron beam welding machine turntable, and the double weld seam welding fixture 4 is in a horizontal tilted posture of B degrees. On the side of the bottom surface of the double weld seam welding fixture 4 away from the tooling shifting mechanism 5, an auxiliary positioning surface E8 is set at an angle A degrees with the bottom surface of the double weld seam welding fixture 4. The shifting mechanism positioning surface F7 and the auxiliary positioning surface E8 are in contact with and supported by the worktable surface of the electron beam welding machine turntable. In this posture, the short weld seam of the structure to be welded can be achieved by using the electron beam welding transverse electron gun.

[0018] The tooling indexing mechanism has two main working positions. When the double-weld welding fixture 4 is placed horizontally, the tooling indexing mechanism does not participate in the positioning of the double-weld welding fixture 4. The bottom surface of the double-weld welding fixture 4 is in contact with the worktable surface of the electron beam welding machine. In this posture, the longitudinal electron gun of the electron beam welding machine can be used to weld the long weld of the structure to be welded. When the tooling indexing mechanism rotates to below the bottom surface of the fixture, the short weld 2 is in a vertical state. In this posture, the transverse electron gun of the electron beam welding machine can be used to weld the short weld of the structure to be welded. When the indexing mechanism rotates to below the bottom surface of the fixture, the engraved observation surface G6 of the indexing mechanism is perpendicular to the worktable surface of the equipment and parallel to the short weld surface.

[0019] When welding the two welds, the structure to be welded is positioned on the double weld welding fixture 4, and the double weld welding fixture 4 is positioned on the electron beam welding equipment; a vacuum is drawn and the long weld is welded using an electron beam longitudinal gun; the temperature is maintained and the fixture is rotated and calibrated; the short weld is welded using an electron beam transverse gun; after maintaining the temperature, the vacuum is released by venting and heat treatment annealing is performed.

[0020] The positioning of the double-seam welding fixture 4 on the electron beam welding equipment is specifically as follows:

[0021] The double-weld welding fixture 4, assembled with the structure to be welded, is hoisted onto the turntable of the electron beam welding equipment. The turntable angle is adjusted so that the long weld 1 is horizontal and parallel to the X-axis of the electron beam welding equipment. Then, the Z-axis position of the worktable surface is adjusted, and the distance from the end face of the electron beam torch to the surface of the long weld is adjusted to meet the working distance requirements in the process document. The X1Y1Z1 coordinate values ​​of the electron beam welding equipment are recorded at this time. The equipment turntable is rotated 90° counterclockwise, and the fixture indexing mechanism 5 is operated to make the short weld vertical. The position of the indexing mechanism's observation surface G6 is recorded at this time. The Y-axis and X-axis positions of the worktable surface are adjusted so that the Y-axis meets the short weld welding working distance requirements in the process document, and the X-axis index is located at the center of the weld. The X2Y2Z2 coordinate values ​​of the equipment are recorded at this time. Then, the fixture indexing mechanism 5 is adjusted according to the recorded X1Y1Z1 values ​​to reset the equipment to the welding state of the long weld of the part, so that it is in the welding state.

[0022] The specific steps of vacuuming and welding long seams using an electron beam longitudinal gun are as follows:

[0023] Once the vacuum level is reached, the formal welding current for the long weld is I1. First, the long weld is preheated and sealed with a current of 0.175I1. Then, the formal welding program is called to weld the long weld 1.

[0024] The specific steps of heat preservation, tooling rotation, and calibration are as follows:

[0025] After the long weld 1 is welded and kept warm for 20 minutes, the tooling indexing mechanism 5 is run to rotate the short weld 2 to a vertical position. The electron beam vertical gun is placed directly above the scale observation surface of the indexing mechanism. The electronic observation window of the electron beam vertical gun is used to observe whether the scale position of G is consistent with the recorded scale position. After confirming that they are consistent, the worktable is adjusted to the X2Y2Z2 coordinate position of the short weld to meet the working distance requirements.

[0026] The specific method for welding short seams using an electron beam crossbar is as follows:

[0027] Switch the electron gun to the electron beam cross gun, adjust the focus of the observation window to make the surface of the short weld clearly visible; check whether the vacuum degree of the electron gun and the vacuum chamber meets the welding requirements. The formal welding current of the short weld is I2. First, use a current of 0.175I2 to preheat and seal the short weld; then call the formal welding program to weld the short weld.

[0028] The process of releasing the vacuum by venting after heat preservation and then performing heat treatment annealing specifically involves:

[0029] After the short weld is completed, it is kept at a temperature for 60 minutes, then ventilated and removed, and then handed over for heat treatment for post-weld annealing.

[0030] The further optimization process specifically includes:

[0031] Calculate the area P where the arc termination and nail tip meet, and then remove the welded part by CNC drilling to remove defects. The area P where the arc termination and nail tip meet is the intersection of two welds. The longer weld terminates here, and the nail tip defect of the shorter weld is in this area. The transition arc at the intersection of the welds is R, the arc termination length of the longer weld is K, and the electron beam nail tip defect control area of ​​the shorter weld is L, where L = R × cos(A / 2). Therefore, the area P where the arc termination and nail tip meet is P = L + K + 1. The part is then transferred to CNC machining for CNC drilling to remove the defects at the intersection of the two welds. The process involves first using a CNC machine tool to remove the backing plates and arc-starting / arrival plates from the long and short weld seams of the part. Then, according to the calculated intersection area P of the arc-ending and nail tip defects, a hole with a diameter of D is drilled parallel to the direction of the short weld seam at the intersection of the T-shaped sections of the two weld seams. D is the rounded-up value of P. The center of this hole is located on the mating line of the long weld seam, and the circumference of the hole is tangent to the back of the short weld seam. The intersection area P of the arc-ending defect of the long weld seam and the nail tip defect of the short weld seam is removed by drilling. Subsequent inspection work is then carried out, and the electron beam welding of the T-shaped section long and short intersecting weld seam structure is completed.

[0032] The beneficial effects of this invention are as follows: 1. A highly efficient electron beam welding method for completing the T-shaped cross-section long and short intersecting weld structure in one go is designed. The method utilizes the same tooling and welding under the same constraint force to complete the electron beam welding of two welds in succession, thereby achieving deformation control of the T-shaped cross-section long and short intersecting weld structure.

[0033] 2. A tooling and tooling shifting mechanism suitable for electron beam welding of T-shaped cross-section long and short intersecting weld seams were designed. It can complete the welding of two weld seams in one clamping and one vacuuming, eliminating the instability and quality risks in the welding process caused by two clampings, reducing one disassembly and one clamping, reducing the labor intensity of the welding process and reducing the level of manual intervention.

[0034] 3. The electron beam welding of the T-shaped cross-section with intersecting long and short weld seams in two vacuum furnaces was reduced to be completed in one vacuum furnace, thus doubling the part processing efficiency.

[0035] 4. By using both longitudinal and transverse welding guns to weld the two weld seams of the parts, the equipment capacity is fully utilized. At the same time, the second weld seam with greater constraint stress is welded using the transverse electron beam gun. The transverse electron beam welding can overcome the influence of gravity on the molten pool and improve the penetration ability of electron beam welding. Compared with longitudinal welding, it can reduce the heat input of the parts, reduce the internal stress level of the parts, reduce the risk of defects such as incomplete fusion and cracks, and reduce the welding deformation of the parts.

[0036] 5. By rationally designing the arc termination length of long welds and the electron beam pin tip control area of ​​short welds, defects at the intersection of the two welds in the T-shaped cross-section long and short weld structure are controlled within a reasonable range. Combined with the strength gain of the component structure corner and the fact that round holes have the least impact on the strength of the original structure and do not cause stress concentration, defects are completely removed by drilling at the part that is attached to the back of the short weld, which greatly reduces their impact on the structural strength of the component and improves the service life of the component. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a typical T-shaped cross-section weld structure with alternating long and short sections.

[0038] Figure 2 A schematic diagram of a double-weld-seam welding fixture and a fixture indexing mechanism;

[0039] Figure 3 A schematic diagram of the area P where the arc and the spike tip meet;

[0040] Figure 4 A schematic diagram illustrating the process of drilling to remove defects at the weld junction.

[0041] In the figure: 1. Long weld; 2. Short weld; 3. Typical T-shaped cross-section long and short weld structure; 4. Double weld welding fixture; 5. Fixture indexing mechanism; 6. Indexing mechanism observation surface G; 7. Fixture indexing mechanism positioning surface F; 8. Auxiliary positioning surface E; 9. Fixture positioning pin; 10. Lateral floating head positioning mechanism; 11. Web floating head positioning mechanism; 12. Intersection area of ​​arc termination and nail tip; 13. Hole. Detailed Implementation

[0042] Appendix Figure 1 The embodiment is a typical T-shaped cross-section structure with alternating long and short welds 3. The part material is AF1410. The welding thickness of the long weld 1 is 6mm, and the welding thickness of the short weld 2 is 12mm. The specific structural form is as follows. Figure 1 As shown, the specific electron beam welding process for a typical T-shaped cross-section structure with intersecting long and short weld seams is as follows:

[0043] (1) Determine the welding posture based on the positional relationship between the two welds;

[0044] The two weld seams of a typical T-shaped cross-section intersecting long and short weld structure 3 intersect in a T-shape, with an angle of A = 83° between the long weld 1 and the short weld 2. Since A < 90°, a rotation mechanism needs to be designed for the welding fixture to adjust the short weld 2 to a vertical position, facilitating welding with an electron beam torch. During welding, the electron beam vacuum chamber turntable and the fixture rotation mechanism work together to rotate and weld the two weld seams. When welding the long weld 1, the welding fixture is placed horizontally, with the weld seam horizontally along the X-axis of the electron beam welder, and the surface to be welded facing the Z+ direction of the electron beam welder. When welding the short weld, the fixture rotation mechanism adjusts the fixture to a horizontal tilt angle of B = 7°, with the weld seam vertically along the Z-axis. The electron beam vacuum chamber turntable adjusts the surface to be welded to face the Y- direction of the electron beam welder, thus determining the orientation of the part during the welding process.

[0045] (2) Design double weld seam welding fixture 4 and fixture indexing mechanism 5;

[0046] The welding fixture mainly consists of a fixture positioning pin 9, a lateral floating head positioning mechanism 10, and a web floating head positioning mechanism 11. The fixture base plate is connected to the fixture indexing mechanism 5. Figure 2 As shown. The diameter of the tooling positioning pin 9 is φ65mm. Six sets of lateral floating head positioning mechanisms 10 are set on both sides of the weld T-section, with a spacing of 120mm. Four sets of web floating head positioning mechanisms 11 are set for clamping the web of the structure to be welded. The floating heads are 10mm away from the weld and spaced 120mm apart. The tooling indexing mechanism 5 is set on one side of the short weld 2 of the welding tooling 4. The tooling indexing mechanism 5 has two working positions: one is horizontal, and the other is rotated to below the bottom surface of the tooling. The welding posture of the part is changed by rotating and switching the positioning surface. When the indexing mechanism is in position one, the long weld 1 of the part is in a horizontal posture. The indexing mechanism does not participate in the positioning of the double weld welding tooling 4. The bottom surface of the double weld welding tooling 4 is in contact with the worktable surface of the electron beam welding machine turntable. In this posture, the longitudinal electron gun of the electron beam welding can be used to weld the long weld 1 of the structure to be welded. When the tooling indexing mechanism 5 is in position two, the short weld 2 is in a vertical state. At this point, the positioning surface 7 of the indexing mechanism is in contact with the worktable surface of the electron beam welding machine, and the fixture is tilted horizontally at 7°. An auxiliary positioning surface 8 is set at an angle of 83° to the bottom plane of the double-weld welding fixture 4 on the side furthest from the indexing mechanism 5. The positioning surface 7 and the auxiliary positioning surface 8, in contact with the worktable surface of the electron beam welding machine, jointly support the fixture. In this orientation, the short weld 2 of the structure to be welded can be achieved using the electron beam welding transverse electron gun. A scribing observation surface 6 is created on the indexing mechanism. This surface is perpendicular to the positioning surface 7 of the indexing mechanism. When the indexing mechanism is in position two, the scribing observation surface 6 is perpendicular to the worktable surface of the equipment and parallel to the surface of the short weld 2.

[0047] (3) Positioning of the structure to be welded on welding fixture 4;

[0048] Grind and repair the structure to be welded, ensuring the surface roughness of the mating surfaces is no greater than Ra3.2, and maintain the edges of the weld joints. Wipe the structure to be welded and the tooling with a white cotton cloth soaked in acetone to ensure that the joints are free of dents, scratches, dents, rust, oil, oxides, and other dirt after cleaning. Check that the magnetic flux of the typical T-section long and short intersecting weld structure 3 and the double weld welding tooling 4 is no greater than 2Gs. If it does not meet the requirement, demagnetize it. Install the demagnetized and cleaned typical T-section long and short intersecting weld structure 3 onto the welding tooling 4. First, perform pre-assembly by inserting the tooling positioning pins 9 through and into the typical T-section long and short intersecting weld structures 3 and the double weld welding tooling 4 on both sides to position the two parts. Then, clamp the tooling lateral floating head positioning mechanism 10. Inspect the gap and misalignment of the weld joints of the structure to be welded. The weld gap should be less than 0.12mm and the misalignment should not exceed 0.2mm. After passing inspection, use manual argon arc welding to position all welding backing plates and arc-starting plates. Then proceed with the formal assembly, clamping and rotating all web plate limiting floating head positioning mechanisms 11 to fit the parts. The operating steps for clamping all floating heads are as follows: first, place both floating heads at their maximum stroke position, then rotate them synchronously to make both floating heads fit against the parts. From fitting to final clamping, the number of rotations of each floating head should not differ by more than 1 / 5 of a turn.

[0049] (4) Positioning tooling and parts on the electron beam welding equipment;

[0050] The assembled typical T-shaped cross-section long and short intersecting weld structure 3 and double weld welding fixture 4 are hoisted onto the rotary table of the electron beam welding equipment. The turntable angle is adjusted so that the long weld 1 is horizontal and parallel to the X-axis of the electron beam welding equipment. Then, the Z-axis position of the worktable is adjusted so that the distance from the end face of the electron beam longitudinal gun to the surface of the long weld 1 is 400mm. The X1Y1Z1 coordinate values ​​of the electron beam welding equipment are recorded at this time. The turntable is rotated 90° counterclockwise and the indexing mechanism is activated so that the short weld 2 is vertical. The position of the scribe line observation surface 6 of the indexing mechanism is recorded at this time. The X-axis position of the worktable is adjusted so that the X-axis scribe line is located at the center of the weld. The Y-axis of the equipment is adjusted so that the distance from the surface of the short weld 2 to the nozzle of the electron beam transverse gun is 400mm. The coordinate values ​​of the equipment at this time are recorded as X2Y2Z2. Then, the fixture indexing mechanism is reset, and the equipment is adjusted to the ready-to-weld state of the long weld 1 of the part according to the recorded X1Y1Z1 values.

[0051] (5) Vacuum is drawn and the first long and thin weld seam is welded using an electron beam longitudinal gun;

[0052] The vacuum level reached 5.0 × 10⁻⁶. -3The welding parameters were: mbar, welding voltage: 150kV, focusing current: 2455mA, welding speed: 800mm / min, electron beam scanning waveform: circular, scanning amplitude: 0.7mm, scanning frequency: 200Hz. The workpiece position was adjusted so that the focus was aligned with the long weld seam 1 to be welded. Electron beam tack welding was performed on the workpiece. The formal welding current for long weld seam 1 was I1 = 40mA. First, electron beam tack welding of long weld seam 1 was performed using a welding current of 0.175I1 = 7mA to preheat and seal the part. Then, the welding program was called, with other parameters unchanged, and a current of 40mA was used to weld long weld seam 1 of a typical T-shaped cross-section long-short intersecting weld structure.

[0053] (6) Perform tooling rotation and calibration;

[0054] After the long weld 1 is welded and kept warm for 20 minutes, run the equipment turntable and tooling indexing mechanism to rotate the short weld 2 to a vertical position. Adjust the platform position so that the electron beam gun is directly above the scribe line observation surface of the indexing mechanism. Use the electronic observation window of the electron beam gun to observe whether the scribe line position of the scribe line observation surface 6 of the indexing mechanism is on the recorded scribe line position. If there is a deviation, adjust the Y-axis position of the equipment for correction. After confirmation and correction, adjust the worktable to the position of 400mm working distance of the short weld 2 in step (4) so ​​that the focus is aligned with the welding joint of the short weld 2.

[0055] (7) Use an electron beam cross gun to weld the short weld seam 2 of the part;

[0056] After releasing the high voltage from the electron beam longitudinal gun, run the electron gun switching program to switch the electron gun from longitudinal to transverse. Adjust the focus of the equipment's observation window to make the surface of short weld 2 clearly visible. Check the vacuum levels of the electron gun and vacuum chamber; the electron gun vacuum level should reach 5.0 × 10⁻⁶. -5 mbar, the vacuum level of the vacuum chamber reaches 5.0 × 10 mbar. -3 mbar. The formal welding current for short weld 2 is I² = 77mA, the tack welding current is 0.175 × I² = 13mA, the welding voltage is 150kV, the focusing current is 2593mA, the welding speed is 800mm / min, the electron beam scanning waveform is circular, the scanning amplitude is 1.3mm, and the scanning frequency is 200Hz. Adjust the workpiece position so that the focus is aligned with the joint of short weld 2, and use a welding current of 13mA to perform electron beam tack welding on short weld 2. Then call the welding program and use a current of 77mA to weld short weld 2 of a typical T-shaped cross-section long-short intersecting weld structure. The welding of the part is completed.

[0057] (8) After heat preservation, the vacuum is released and heat treatment annealing is performed;

[0058] After holding at a high temperature for 60 minutes, the vacuum chamber is filled with gas, and the parts are then removed and transferred to a heat treatment facility for post-weld annealing.

[0059] (9) Calculate and remove the area 12 where the arc and nail tip meet, and then remove the part by CNC drilling 13 to remove the defects;

[0060] The area where the arc ends and the nail tip meet (12) is the intersection of two weld seams, such as... Figure 3 As shown. The long weld 1 terminates at this point, while the short weld 2 leaves the welding nail tip defect in this area. The transition arc at the weld intersection is 10mm. Due to the smaller thickness of the long weld 1, the smaller electron beam keyhole, and the shallower penetration depth, the length K of the termination segment of the long weld 1 is set to 10mm. The electron beam nail tip defect control area for the short weld 2 is L = R × cos(A / 2) = 7.49mm. Therefore, the intersection area of ​​the long weld 1 termination and the short weld 2 nail tip control is P = L + K + 1 = 18.49mm. The part is then transferred to a CNC machine tool for CNC machining and drilling. First, the CNC machine tool is used to remove the backing plates and arc initiation and termination plates from the long and short welds of the part. The calculated intersection area of ​​the arc termination and the nail tip is P = 18.49 mm, parallel to the direction of short weld 2. A hole 13 with a diameter of D = 19 mm is drilled at the intersection of the T-shaped section. The center of hole 13 is located on the mating line of long weld 1, and the periphery of the hole is tangent to the back of short weld 2. The intersection area 12 of the arc termination of long weld 1 and the nail tip defect of short weld 2 is removed by drilling hole 13. Figure 4 As shown.

[0061] (10) The parts are inspected by X-ray to check the internal quality of the welding. The electron beam welding of the T-shaped cross section with long and short intersecting weld seams is completed.

Claims

1. A highly efficient electron beam welding method for a T-shaped cross-section structure with intersecting long and short weld seams, characterized in that, The T-shaped cross-section long and short intersecting weld structure is clamped and vacuumed in one go to complete the welding of two welds; the welding sequence of the T-shaped cross-section long and short intersecting weld structure is long first and short last; according to the cooperation of the double weld welding fixture (4) and the fixture rotation mechanism (5), the long weld (1) is welded in a horizontal state and the short weld (2) is welded in a vertical state; after the two welds are welded, further optimization is carried out to obtain the required parts; The double-weld welding fixture (4) includes a positioning pin (9), a lateral floating head positioning mechanism (10), and a web floating head positioning mechanism (11). The positioning pin (9) is installed at one end of the bottom surface of the double-weld welding fixture (4), and the lateral floating head positioning mechanisms (10) are installed on both sides of the bottom surface. The web floating head positioning mechanism (11) is installed above the structure to be welded. The diameter of the positioning pin (9) is set according to the hole size of the structure to be welded. It is used to connect and position the structure to be welded and the double-weld welding fixture (4), and to restrict the freedom of the structure to be welded in four directions. The two lateral floating head positioning mechanisms (10) are symmetrically arranged on both sides of the weld section of the structure to be welded, with a spacing of 100-150mm. The two web floating head positioning mechanisms (11) are used to press the web of the structure to be welded. They are distributed on both sides of the long weld (1), with a spacing of 100-150mm. The spacing between the web floating head positioning mechanisms (11) on both sides of the weld is 10-20mm. According to the relevant requirements of the electron beam welding standard for the structural material to be welded, the structure to be welded is ground, cleaned and repaired; check whether the magnetic flux of the structure to be welded and the double weld welding fixture (4) meets the relevant standard requirements. If not, demagnetize it; install the demagnetized and cleaned structure to be welded onto the double weld welding fixture (4), first perform pre-assembly, use positioning pins (9) to penetrate the two parts of the structure to be welded for positioning, and clamp it through the lateral floating head positioning mechanism (10); check the weld gap and misalignment according to the electron beam welding standard. After passing the standard, use manual argon arc welding to position the welding pad and arc-starting plate required for welding the two welds; then perform formal assembly and clamp all positioning and limiting mechanisms. The tooling shifting mechanism (5) consists of two blocks, which are respectively installed on both sides of one end of the bottom surface of the double weld welding tool (4) and located on the side of the short weld (2). The tooling shifting mechanism (5) includes a shifting mechanism engraving observation surface G (6) and a shifting mechanism positioning surface F (7) that are perpendicular to each other. The shifting mechanism positioning surface F (7) is in contact with the worktable of the electron beam welding machine turntable, and the double weld welding tool (4) is in a horizontal tilted posture of B degrees. On the side of the bottom surface of the double weld welding tool (4) away from the tooling shifting mechanism (5), an auxiliary positioning surface E (8) is set at an angle A degrees with the bottom surface of the double weld welding tool (4). The shifting mechanism positioning surface F (7) and the auxiliary positioning surface E (8) are in contact with and supported by the worktable of the electron beam welding machine turntable. In this posture, the short weld of the structure to be welded can be achieved by using the electron beam welding transverse electron gun. The tooling shifting mechanism has two main working positions. When the double weld seam welding tool (4) is placed horizontally, the tooling shifting mechanism does not participate in the positioning of the double weld seam welding tool (4). The bottom surface of the double weld seam welding tool (4) is in contact with the worktable surface of the electron beam welding machine turntable. In this posture, the longitudinal electron gun of the electron beam welding can be used to weld the long weld seam of the structure to be welded. When the tooling shifting mechanism is rotated to the bottom surface of the tooling and the short weld seam (2) is in a vertical state, the transverse electron gun of the electron beam welding can be used to weld the short weld seam of the structure to be welded. When the shifting mechanism is rotated to the bottom surface of the tooling, the engraved observation surface G (6) of the shifting mechanism is perpendicular to the worktable surface of the equipment and parallel to the short weld seam surface.

2. The efficient electron beam welding method for T-shaped cross-section long and short intersecting weld structures according to claim 1, characterized in that, The angle between the short weld (2) and the long weld (1) is A; When A=90°, the electron beam vacuum chamber turntable is used to directly rotate and weld the two weld seams of the part during the welding process; when welding the long weld seam (1), the double weld seam welding fixture (4) is placed horizontally, the weld seam is horizontal along the X-axis of the electron beam welding machine, and the surface to be welded faces the positive direction of the Z-axis of the electron beam welding machine; when welding the short weld seam (2), the posture is vertical along the Z-axis, and the surface to be welded faces the negative direction of the Y-axis of the electron beam welding machine. When A < 90°, the double weld seam welding fixture (4) and the fixture indexing mechanism (5) work together to adjust the posture of the short weld seam (2) to a vertical posture during welding. During the welding process, the electron beam vacuum chamber turntable and the fixture indexing mechanism (5) are used together to realize the indexing and welding of the two weld seams of the part. When welding the long weld (1), the double weld welding fixture (4) is placed horizontally, with the long weld (1) horizontally along the X-axis of the electron beam welder and the surface to be welded facing the positive direction of the Z-axis of the electron beam welder; when welding the short weld (2), the fixture indexing mechanism (5) adjusts the double weld welding fixture (4) to a horizontal tilt angle B, where B = (90° - A); the short weld (2) is vertical along the Z-axis and the surface to be welded faces the negative direction of the Y-axis of the electron beam welder.

3. The efficient electron beam welding method for T-shaped cross-section long and short intersecting weld structures according to claim 1, characterized in that, The operation steps of the lateral floating head positioning mechanism (10) and the web floating head positioning mechanism (11) when clamping are as follows: first, the floating heads on both sides are placed at the maximum stroke position, and then they are rotated synchronously to make the floating heads on both sides fit with the parts. From the time the floating heads fit together to the final clamping process, the number of rotations of each floating head is no more than 1 / 5 of a rotation.

4. The efficient electron beam welding method for T-shaped cross-section long-short intersecting weld structures according to claim 1, characterized in that, When welding the two welds, the structure to be welded is positioned in the double weld welding fixture (4), and the double weld welding fixture (4) is positioned on the electron beam welding equipment; vacuum is drawn and the long weld is welded using an electron beam longitudinal gun; heat preservation is performed and the fixture is rotated and calibrated; the short weld is welded using an electron beam transverse gun; after heat preservation, the vacuum is released by ventilation and heat treatment annealing is performed. The positioning of the double-weld-seam welding fixture (4) on the electron beam welding equipment is specifically as follows: The double-weld welding fixture (4) with the assembled structure to be welded is hoisted onto the turntable of the electron beam welding equipment. The turntable angle is adjusted so that the long weld (1) is in a horizontal state and parallel to the X-axis of the electron beam welding equipment. Then the Z-direction position of the worktable is adjusted, and the distance from the end face of the electron beam longitudinal gun to the surface of the long weld is adjusted so that it meets the working distance requirements in the process document. The X1Y1Z1 coordinate values ​​of the electron beam welding equipment are recorded at this time. The equipment turntable is rotated 90° counterclockwise and the fixture indexing mechanism (5) is run so that the short weld is in a vertical state. The position of the indexing mechanism's observation surface G (6) is recorded at this time. The Y-direction and X-direction positions of the worktable are adjusted so that the Y-direction meets the working distance requirements of the short weld in the process document, and the X-direction index is located at the center of the weld. The X2Y2Z2 coordinate values ​​of the equipment are recorded at this time. Then the fixture indexing mechanism (5) is adjusted according to the recorded X1Y1Z1 values ​​to reset the equipment to the waiting state of the long weld of the part, so that it is in the waiting state. The specific steps of vacuuming and welding long seams using an electron beam longitudinal gun are as follows: The vacuum is drawn to the predetermined vacuum level. The formal welding current of the long weld is I1. First, the long weld is preheated and sealed with a current of 0.175 I1. Then, the formal welding program is called to weld the long weld (1). The specific steps of heat preservation, tooling rotation, and calibration are as follows: After the long weld (1) is finished and kept warm for 20 minutes, the tooling shifting mechanism (5) is run to turn the short weld (2) to the vertical position. The electron beam vertical gun is placed directly above the observation surface of the shifting mechanism. The electronic observation window of the electron beam vertical gun is used to observe whether the position of the gravitational line where G is located is consistent with the recorded position of the gravitational line. After confirming that they are consistent, the worktable is adjusted to the X2Y2Z2 coordinate position of the short weld to meet the working distance requirements. The specific method for welding short seams using an electron beam crossbar is as follows: Switch the electron gun to the electron beam cross gun, adjust the focus of the observation window to make the surface of the short weld clearly visible; check whether the vacuum degree of the electron gun and the vacuum chamber meets the welding requirements. The formal welding current of the short weld is I2. First, use a current of 0.175 I2 to preheat and seal the short weld; then call the formal welding program to weld the short weld. The process of releasing the vacuum by venting after heat preservation and then performing heat treatment annealing specifically involves: After the short weld is completed, it is kept at a temperature for 60 minutes, then ventilated and removed, and then handed over for heat treatment for post-weld annealing.

5. The efficient electron beam welding method for T-shaped cross-section long-short intersecting weld structures according to claim 4, characterized in that, The further optimization process specifically includes: Calculate the area P where the arc termination and nail tip meet, and then remove the welded part by CNC drilling to remove defects. The area P where the arc termination and nail tip meet is the intersection of two welds. The longer weld terminates here, and the nail tip defect of the shorter weld is in this area. The transition arc at the intersection of the welds is R, the arc termination length of the longer weld is K, and the electron beam nail tip defect control area of ​​the shorter weld is L, where L = R × cos(A / 2). Therefore, the area P where the arc termination and nail tip meet is P = L + K + 1. The part is then transferred to CNC machining for CNC drilling to remove the defects at the intersection of the two welds. The process involves first using a CNC machine tool to remove the backing plates and arc-starting / arrival plates from the long and short weld seams of the part. Then, according to the calculated intersection area P of the arc-ending and nail tip defects, a hole with a diameter of D is drilled parallel to the direction of the short weld seam at the intersection of the T-shaped sections of the two weld seams. D is the rounded-up value of P. The center of this hole is located on the mating line of the long weld seam, and the circumference of the hole is tangent to the back of the short weld seam. The intersection area P of the arc-ending defect of the long weld seam and the nail tip defect of the short weld seam is removed by drilling. Subsequent inspection work is then carried out, and the electron beam welding of the T-shaped section long and short intersecting weld seam structure is completed.

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