Electron beam welding method for special-shaped angle double-t type net size member

Abstract

The present application belongs to the field of material processing and manufacturing, and relates to an electron beam welding method for a special-shaped angle double-T type net size component. The present application adopts an electron beam deep penetration welding mode, controls the penetration of a welding bead by additionally arranging a backing plate at the back of the welding bead, utilizes the decrease of the density of the material itself after the material changes from a forged state to a welded state before and after welding to realize the increase of the volume of the material at the welding bead, so as to compensate for the material loss at the welding edge and inhibit the welding edge; according to the manufacturing requirements, the clamping points of the welding tool are designed at the positions of the components with assembly relationship, the deformation of the clamping point positions in the welding process is controlled, a reasonable welding sequence is designed, and the welding deformation is controlled; for the oversized components, an inclined welding mode is adopted, the spatial position of the welding bead is controlled by adjusting the inclination angle of the component, the force balance of the welding pool is realized, and the stability of the welding pool is improved.

Description

Technical Field

[0001] The invention belongs to the field of material processing and manufacturing, and relates to an electron beam welding method for special-shaped angle double T-shaped net size components. Background Art

[0002] Aviation frame beam components play a primary load-bearing role in aviation equipment and are typically formed using a forging process followed by CNC machining. However, for components with complex structures and closed cavities, the processing capabilities of forming equipment and manufacturing processes are limited. Furthermore, to meet the concept of low-cost manufacturing, components must be formed separately and then welded together. Electron beam welding technology, due to its high energy density, strong heat source penetration, and ability to weld in a vacuum environment, has been widely used in the joining of thick components. However, electron beam welding of large net-size components will produce undercuts on both sides of the weld after welding is completed due to the gradient effect of the electron beam heat source energy density being high in the center and low around. Electron beam welding of thick components requires a large heat input to ensure full penetration of the weld, which will produce large welding deformation after welding is completed. Once these defects occur, they will affect the overall quality of the final component. Therefore, it is necessary to increase the margin in the waiting-to-weld state before welding to ensure the subsequent processing size of the component, which increases the processing cycle of the component. Electron beam welding is limited by the size of the vacuum box. For welding of some oversized components, horizontal welding cannot be used and they need to be tilted at a certain angle before they can be placed in the vacuum box. In this way, the weld will be placed at an angle and the electron beam flow will be vertical in its original state. Under such circumstances, it will cause the defect of unfused bottom of the weld bead; in the electron beam welding of double T-shaped structures, due to the existence of the intersection of the weld bead, the "nail tip" feature at the bottom of the electron beam will remain inside the weld bead, which is prone to pores and has a high tissue gradient, reducing the mechanical properties of the weld bead and posing a hidden danger to the safety of subsequent use; therefore, for the electron beam welding process of special-shaped double T-shaped components, it is urgent to develop a net-size component electron beam welding technology with good applicability, stable and reliable welding process, and high adaptability and tolerance to component size, to solve defects such as welding deformation and welding undercut, improve the processing technology of the component, shorten the processing cycle of the component, and realize fast and good component manufacturing, providing new ideas and technical basis for the precise manufacturing of frame beam components. Summary of the Invention

[0003] In view of the welding deformation and the risk of subsequent component scrap caused by the welding edge defects of the net size welding, and the risk of the bottom of the inclined welding bead not being fused in the connection forming of the oversized component, an electronic beam welding method of a special-shaped angle double-T net size component is provided.The electronic beam deep penetration welding mode is adopted, the back plate is added at the back of the welding bead to control the penetration of the welding bead, the density of the material itself is reduced after being changed from the forged state to the welded state before and after welding, the volume of the material at the welding bead is increased, so that the purpose of compensating for the material loss at the welding edge and inhibiting the welding edge is achieved;According to the manufacturing requirements, the clamping points of the welding tooling are designed at the positions of the subsequent components with assembly relationship to control the deformation of the clamping point positions in the welding process, and a reasonable welding sequence is designed to control the welding deformation;For the oversized component, the inclined welding mode is adopted, the space position of the welding bead is controlled by adjusting the inclination angle of the component, the stress balance of the welding pool is realized, and the stability of the welding pool is improved;In addition, the dynamic gun type electronic beam welding equipment with strong adaptability is selected, the space incident direction of the electron beam current is adjusted, the incident direction of the electron beam current is perpendicular to the surface of the inclined welding bead, and the welding of the inclined welding bead is completed.The electronic beam welding method of the special-shaped angle double-T net size component can effectively control the welding deformation, inhibit the welding edge defects, and realize the welding of the oversized component, so that the high-quality and efficient welding of the final component is realized.

[0004] The technical means adopted by the present application are as follows:

[0005] The electronic beam welding method of the special-shaped angle double-T net size component is as follows:

[0006] Step 1: Determination of welding sequence of the to-be-welded component

[0007] According to the required welding object, the dynamic gun type electronic beam welding equipment is selected, the to-be-welded component with the welding bead back plate is clamped to the anti-deformation tooling in sequence according to the reasonable welding sequence, and is placed in the electronic beam welding vacuum box, and the deep penetration welding mode of the electronic beam is adopted to realize the welding connection of the component;

[0008] Step 2: Design and manufacture of tooling

[0009] According to the shape size of the component and the control points of the final component shape size, the anti-deformation clamping tooling is designed and manufactured, so that the axis of the external top pressure block coincides with the axis of the size control point of the component, the axis of the internal down pressure point is perpendicular to the plane where the welding bead of the to-be-welded component is located and is symmetrically distributed on both sides of the size control point, and there is no interference between the support accessory parts of each pressure block in the space position, in addition, the inclination angle of the component is calculated by formula to be less than 50°, therefore, the welding clamping tooling of the rear welding bead is designed to be the clamping tooling with a space inclination angle of 45° of the rear welding bead;

[0010] The component is placed obliquely to meet the welding connection of the oversize component, when the welding bead is placed horizontally, the electron beam current accessibility is poor or the component size exceeds the inner cavity size of the vacuum box, the component should be placed obliquely in the vacuum box, the diagonal size of the vacuum box is fully utilized, the electron beam welding of the component is met, the oblique angle θ of the component should meet the relationship between the self gravity and the surface tension of the molten pool shown in formula (1), the surface tension of the whole molten pool at the gap between the upper surface of the backing plate and the lower surface of the to-be-welded component is prevented from being less than the downward flow driving force caused by the self weight of the molten pool due to the obliqueness of the placed component being too large, the molten metal in the molten pool overflows along the gap between the lower surface of the to-be-welded component and the upper surface of the backing plate,

[0011] pr 2 Lcosθ<αL (1)

[0012] In the formula, ρ is the liquid metal density of the to-be-welded material, r is the molten pool radius, α is the surface tension coefficient of the liquid metal of the to-be-welded material, and L is the gap between the upper surface of the backing plate and the lower surface of the to-be-welded component.

[0013] The welding sequence is that the welding bead length of the to-be-welded part of the comparison component is used, and the welding sequence from long to short is sequentially used to complete the welding of each to-be-welded bead, and if there is a crossing place of the welding bead, a circular process hole for preventing the cross defect is drilled at the crossing place by using material removal, the size of the circular process hole is greater than the size of the welding bead at the crossing position, and the edge of the process hole is smoothly transitioned, so that the welding defects at the crossing position are effectively removed, and the stress concentration caused by the edge in the subsequent use process is reduced.

[0014] The electron beam deep penetration welding mode is:

[0015] The characteristics of the high energy density of the electron beam current are used, the energy intensity of the electron beam current is adjusted in the welding process, the high energy density electron beam current forms a small hole at the to-be-welded plate, and the beam current penetrates through the small hole and acts on the upper surface of the backing plate at the back of the welding bead, but the beam current does not penetrate the backing plate, so that the molten pool of the to-be-welded bead and the molten pool on the upper surface of the backing plate form an integral molten pool under the joint action of the beam current and the plasma flow in the small hole, then as the electron beam current moves along the welding direction, a new integral molten pool is formed at the position acted on by the electron beam current, and the position acted on by the electron beam current solidifies with the molten pool, the butt joint connection of the to-be-welded part component and the lap joint connection of the component and the backing plate are completed, after the to-be-welded plate and the backing plate material are melted and solidified, the volume increases due to the grain growth and the density reduction caused by the change from the forged state to the welded state, finally the excess height is generated on the front surface of the welding bead, the compensation of the missing material of the welding undercut is realized, and the welding undercut is inhibited.

[0016] The back lining plate is used as a process part and should be removed after the component welding is finally completed. It is made of the same material as the component material to be welded. The shape of the lining plate should be consistent with the profile of the back weld bead, and it should fit with the lower surface of the weld bead to be welded during assembly, with a gap of less than 0.1mm to prevent the liquid metal of the welding pool from flowing out from the gap between the bottom of the weld bead and the lining plate during deep penetration welding, causing the loss of material in the weld bead area and eventually resulting in a sagging defect. The width of the lining plate should be greater than 2 times the thickness of the plate to be welded to ensure the molten width at the bottom of the weld bead. Smaller than the liner width to prevent the back molten pool diameter from being larger than the liner width during deep penetration welding, which would cause the molten pool liquid metal to fall, resulting in the loss of material at the weld bead, and eventually lead to sagging defects. The liner thickness is not less than the thickness of the plate at the weld bead to be welded. During deep penetration welding, the energy acting on the liner surface cannot penetrate the liner. The bottom of the liner supports the entire molten pool during welding, and the "nail tip" shaped defect at the bottom of the electron beam welding can remain inside the liner. After the component completes the welding process, the defect can be removed together with the liner.

[0017] The clamping position of the anti-deformation tooling is set according to the size control point position of the component that will be subsequently equipped with other components or has specific size requirements. The positioning of the component to be welded is achieved by pressing down on both sides of the internal weld and pressing inward from the outside. The axis of the pressure block used for external inward pressure should coincide with the axis of the size control point of the component. The axis of the internal downward pressure point is perpendicular to the plane where the weld of the component to be welded is located and is symmetrically distributed on both sides of the size control point to ensure that the pressure on the component is balanced when the component is fixed before welding. There should be no spatial interference between the supporting accessories of each pressure block. After welding is completed, the tooling should be disassembled after the temperature of the component drops to room temperature and then maintained for not less than 30 minutes to achieve welding deformation control of the component.

[0018] The movable gun type electron beam welding equipment should satisfy the requirement of infinitely adjustable welding gun between vertical and horizontal states, thereby improving the welding adaptability of components with different weld bead spatial positions, ensuring that the electron beam can be incident vertically relative to the weld bead as the weld bead spatial position of the component changes, thereby enhancing the adaptability of the welding process and ensuring the welding quality of the weld bead.

[0019] Step 3: Clamp the component to be welded onto the welding fixture and place it in the vacuum box for electron beam welding. Adjust the spatial posture of the electron beam welding gun so that the electron beam flow can be vertically incident on the entire weld. Set the welding parameters, start the welding equipment, and complete the welding of the component.

[0020] Step 4: Removal of back lining and circular process holes to prevent cross defects

[0021] The welded component is removed from the clamping fixture, and the back lining is processed by a CNC machine tool until it is flush with the plane of the component, and the edges of the process holes are chamfered to complete the welding process of the component.

[0022] Beneficial effects of the present invention:

[0023] 1. To suppress electron welding undercut and improve weld quality, the present invention adds a lining plate to the back of the weld to be welded, controls the size of the lining plate, and uses the electron beam deep penetration welding mode. By utilizing the characteristics of forged metal that grows in grain size after melting and solidification and becomes a welded state with lower density and increases in volume, a residual height is created on the upper surface of the completed weld to compensate for the missing material at the undercut on both sides of the weld.

[0024] 2. Improve the adaptability of electron beam welding to meet the welding requirements of super-large components. Use dynamic gun mode electron beam welding equipment, combine with the inclined placement welding method of components, control the inclination angle, improve the stability of the molten pool, and achieve high-quality electron beam welding of inclined welds.

[0025] 3. Control welding deformation, improve the shape accuracy of the net size component welding, design the clamping position of the welding tooling according to the key size requirements of the final component, and at the same time, control the time for disassembly of the tooling attached to the completed welded component to reduce the welding deformation of the overall component. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of special-shaped angle double T-shaped member;

[0027] Figure 2 Schematic diagram of clamping for welding the weld bead of the component first;

[0028] Figure 3 This is a schematic diagram of the clamping of the post-weld weld of the component;

[0029] Figure 4 Schematic diagram of electron beam deep penetration welding mode.

[0030] In the figure: 1 is the first weld bead; 2 is the second weld bead; 3 is the pressure block used for external inward pressure; 4 is the internal downward pressure point 4; 5 is the welding clamping tool for the second weld bead; 6 is the spatial inclination angle of the second weld bead; 7 is the component to be welded; 8 is the back lining plate. DETAILED DESCRIPTION

[0031] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] Example 1:

[0033] The electron beam welding method for special-shaped double T-shaped net size components is as follows:

[0034] Step 1: Determine the welding sequence of components to be welded

[0035] Measure the lengths of the two weld passes of the component and compare them to determine that the longer weld pass is the first weld pass 1 and the shorter one is the second weld pass 2. When welding the second weld pass, the inclined welding mode should be adopted;

[0036] Step 2: Design and manufacture of tooling

[0037] Based on the control points of the component's outer dimensions and the final component's outer dimensions, an anti-deformation clamping fixture is designed and manufactured so that the axis of the external inward pressing block 3 coincides with the axis of the component's dimensional control point. The axis of the internal downward pressing point 4 is perpendicular to the plane of the weld bead of the component to be welded 7 and is symmetrically distributed on both sides of the dimensional control point. There should be no spatial interference between the supporting accessories of each clamp. In addition, according to Formula 1, the component's inclination angle should be less than 50°. Therefore, the welding clamping fixture 5 for the post-weld weld bead is designed to provide a spatial inclination angle 6 of 45° for the post-weld weld bead.

[0038] Step 3: Pre-welding cleaning of components to be welded

[0039] Within 12 hours before welding, use a metal brush to polish the surface of each component within 20mm from the edge of the weld to be welded and the butt end face to improve the metallic luster, and wipe the polished area with an organic flux to remove oil, rust, oxides, dust, dirt, grease and other foreign matter, and cover the polished and cleaned area with kraft paper;

[0040] Step 4: Assembly of components to be welded

[0041] Clean the welding tooling with an organic flux. All surfaces should be free of oil and dust. Install the component to be welded 7 onto the corresponding welding tooling for the first weld bead. Add a 10mm thick welding liner to the back of the weld bead and use the internal downward pressure device and external upward pressure device of the tooling to clamp the component. Measure the dimensions of each shape control point to confirm whether the dimensions of each control point meet the requirements of the drawing. Check the gap between the end faces of the weld bead to ensure that the gap size is no more than 0.1mm and the misalignment is no more than 0.2mm. Use argon arc welding to position the liner and the component to be welded 7.

[0042] Step 5: Weld the weld first

[0043] Place the weld bead that has been clamped and fixed by the tooling into the vacuum box, adjust the position of the welding gun so that the focus is completely aligned with the butt joint of the weld bead to be welded, and use the deep penetration welding mode to ensure that the component to be welded 7 is fully penetrated and the back lining 8 is partially penetrated. Set the welding speed to 1000mm / min, welding current to 30mA, welding voltage to 55kV, and focusing current to 3.0A, turn on the equipment to complete the welding, and remove the clamping tooling of the weld bead when the component cools to room temperature;

[0044] Step 6: Post-weld weld

[0045] Clean the subsequent weld and assemble the liner and the fixture according to steps 3 and 4, and place the weld bead that has been fixed by the fixture into the vacuum box. Adjust the position of the welding gun so that the focus is completely aligned with the butt joint of the weld bead to be welded. According to the deep penetration welding mode, ensure that the welded component 7 is fully penetrated and the back liner 8 is partially penetrated. Set the welding speed to 1000mm / min, welding current to 30mA, welding voltage to 55kV, and focusing current to 3.0A. Start the equipment to complete the welding. When the component cools to room temperature, remove the fixture of the weld bead.

[0046] Step 7: Removal of back lining and circular process holes to prevent cross defects

[0047] The welded component is removed from the clamping fixture, and the back lining plate 8 is processed by a CNC machine tool until it is flush with the plane of the component. The width of the weld is measured, and the diameter of the circular process hole to prevent cross defects is calculated to be 20 mm. A circular process hole with a diameter of 20 mm is drilled at the intersection of the weld, and the edges of the process hole are chamfered to complete the welding process of the component.

Claims

1. Electron beam welding method for special-shaped double T-shaped net size components, characterized in that: Here are the steps: Step 1: Determine the welding sequence of components to be welded According to the required welding object, a dynamic gun type electron beam welding device is selected, and according to a reasonable welding sequence, the components to be welded (7) with the weld bead backing plate (8) at the weld bead are clamped on the anti-deformation fixture clamp in sequence, and placed in the electron beam welding vacuum box, and the electron beam deep penetration welding mode is used to respectively realize the welding connection of the components; Step 2: Design and manufacture of tooling According to the control points of the outer dimensions of the component and the outer dimensions of the final component, the anti-deformation clamping fixture is designed and manufactured so that the axis of the pressure block (3) used for external inward pressure should coincide with the axis of the dimension control point of the component, the axis of the internal downward pressure point (4) is perpendicular to the plane where the weld bead of the component to be welded (7) is located and is symmetrically distributed on both sides of the dimension control point, and there should be no spatial interference between the supporting auxiliary parts of each pressure block. In addition, the inclination angle of the component should be less than 50° calculated by formula (1). Therefore, the welding clamping fixture (5) for the post-weld weld bead is designed to make the spatial inclination angle (6) of the post-weld weld bead 45°. rr 2 L cosθ<αL (1) Where: ρ is the density of the liquid metal of the material to be welded, r is the radius of the molten pool, α is the surface tension coefficient of the liquid metal of the material to be welded, and L is the fitting gap between the upper surface of the liner and the lower surface of the component to be welded (7); The welding sequence is as follows: by comparing the length of the weld bead at the position to be welded in the component, the welding of each weld bead to be welded is completed in the order from long to short. At the same time, if there is an intersection of the weld bead, a circular process hole to prevent the intersection defect should be drilled at the intersection by removing the material. The size of the circular process hole should be larger than the size of the weld bead at the intersection, and the edge of the process hole should be smoothly transitioned. While ensuring the effective removal of the welding defects at the intersection, it can also reduce the stress concentration in the subsequent use process due to the existence of the edge after the process hole is manufactured. Step 3: Clamp the component to be welded (7) onto the welding fixture and place it in the vacuum box of the electron beam welding, adjust the spatial posture of the electron beam welding gun so that the electron beam flow can be vertically incident on the entire weld, set the welding parameters, start the welding equipment, and complete the welding of the component; Step 4: Removal of back lining and circular process holes to prevent cross defects The welded component is removed from the clamping fixture, and the back lining plate (8) is processed by a CNC machine tool until it is flush with the plane of the component, the width of the weld is measured, and the edges of the process hole are chamfered to complete the component welding process.

2. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 1, characterized in that: The electron beam deep penetration welding mode is: By utilizing the characteristic of high energy density of electron beam, the energy intensity of electron beam is adjusted during welding so that electron beam with high energy density forms a small hole at the plate to be welded, and the beam passes through the small hole and acts on the upper surface of the liner (8) at the back of the weld, but the beam does not penetrate the liner, so that the metal molten pool at the welded portion and the molten pool on the upper surface of the liner form an integral molten pool under the combined action of beam force and plasma flow force in the small hole. Then, as the electron beam moves along the welding direction, a new integral molten pool is generated at the portion where the electron beam acts, and as the molten pool solidifies at the portion where the electron beam acts, the butt connection of the components at the welded portion and the overlap connection of the components and the liner are completed. After the plate to be welded and the liner material are melted and solidified, as the forged state changes to the welded state, the grains grow and the density decreases, resulting in an increase in volume. Finally, excess height is generated on the front side of the weld, thereby compensating for the missing material at the weld undercut and suppressing the weld undercut.

3. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 1 or 2, characterized in that: The back lining plate (8) is made of the same material as the material of the component to be welded. The shape of the lining plate should be consistent with the profile of the back weld bead, and should be fitted with the lower surface of the weld bead to be welded during assembly, with a gap of less than 0.1 mm, to prevent the liquid metal of the welding pool from flowing out from the gap between the bottom of the weld bead and the lining plate during deep penetration welding, resulting in the loss of material at the weld bead position, and eventually causing a sagging defect. The width of the lining plate should be greater than 2 times the thickness of the plate to be welded, to ensure that the molten width at the bottom of the weld bead is less than the lining plate width, to prevent the diameter of the back molten pool from being greater than the lining plate width during deep penetration welding, causing the liquid metal of the molten pool to fall, resulting in the loss of material at the weld bead position, and eventually causing a sagging defect. The thickness of the lining plate is not less than the thickness of the plate at the weld bead to be welded, to ensure that the energy acting on the upper surface of the lining plate cannot penetrate the lining plate during deep penetration welding, and the bottom of the lining plate plays a supporting role on the overall molten pool during welding, and the "nail tip" shaped defect at the bottom of the electron beam welding may remain inside the lining plate. After the component completes the welding process, the defect can be removed together with the lining plate.

4. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 1 or 2, characterized in that: The anti-deformation tooling adopts the method of pressing down on both sides of the internal weld and pressing inward from the outside to achieve the positioning of the component to be welded (7). The axis of the pressure block used for the external inward pressing should coincide with the axis of the size control point of the component. The axis of the internal downward pressing point is perpendicular to the plane where the weld of the component to be welded (7) is located and is symmetrically distributed on both sides of the size control point to ensure the balance of pressure on the component when the component is fixed before welding. There should be no spatial interference between the supporting auxiliary parts of each pressure block. After the welding is completed, the tooling should be disassembled after the temperature of the component drops to room temperature and is kept for not less than 30 minutes to achieve the control of welding deformation of the component.

5. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 3, characterized in that: The anti-deformation tooling adopts the method of pressing down on both sides of the internal weld and pressing inward from the outside to achieve the positioning of the component to be welded (7). The axis of the pressure block used for the external inward pressing should coincide with the axis of the size control point of the component. The axis of the internal downward pressing point is perpendicular to the plane where the weld of the component to be welded (7) is located and is symmetrically distributed on both sides of the size control point to ensure the balance of pressure on the component when the component is fixed before welding. There should be no spatial interference between the supporting auxiliary parts of each pressure block. After the welding is completed, the tooling should be disassembled after the temperature of the component drops to room temperature and is kept for not less than 30 minutes to achieve the control of welding deformation of the component.

6. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 1, 2 or 5, characterized in that: The movable gun type electron beam welding equipment should satisfy the stepless adjustment of the welding gun between vertical and horizontal states, improve the welding adaptability of different weld bead spatial positions of the component, ensure that as the position of the weld bead space of the component changes, the electron beam flow can be vertically incident relative to the weld to be welded, enhance the adaptability of the welding process, and ensure the welding quality of the weld.

7. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 3, characterized in that: The movable gun type electron beam welding equipment should satisfy the stepless adjustment of the welding gun between vertical and horizontal states, improve the welding adaptability of different weld bead spatial positions of the component, ensure that as the position of the weld bead space of the component changes, the electron beam flow can be vertically incident relative to the weld to be welded, enhance the adaptability of the welding process, and ensure the welding quality of the weld.

8. The electron beam welding method for special-shaped double-T-shaped net size components according to claim 4, characterized in that: The movable gun type electron beam welding equipment should satisfy the stepless adjustment of the welding gun between vertical and horizontal states, improve the welding adaptability of different weld bead spatial positions of the component, ensure that as the position of the weld bead space of the component changes, the electron beam flow can be vertically incident relative to the weld to be welded, enhance the adaptability of the welding process, and ensure the welding quality of the weld.

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