Electron beam welding method and fixture for 2A70 aluminum alloy

Abstract

The present application provides an electron beam welding method and fixture for 2A70 aluminum alloy, belonging to the field of welding process technology. The method includes cleaning a part, pressing and assembling both ends of the part using a first fixture; placing the assembled part into an electron beam welder, with the position to be welded of the part offset from the position directly below the electron gun of the electron beam welder, and performing tack welding on the position to be welded using a first electron beam; removing the part, disassembling the fixture, and securing one end of the part using a second fixture; placing the secured part into an electron beam welder, and welding the position to be welded using a second electron beam, wherein the second electron beam has multiple electron beam spots and the energy of the second electron beam is greater than that of the first electron beam. The processing scheme of the present application avoids defects such as cracks, perforations, and pores in the weld, and achieves qualified welding of the part.

Description

Technical Field

[0001] The present application relates to the field of welding process technology, and in particular to an electron beam welding method and fixture for 2A70 aluminum alloy. Background Art

[0002] 2A70 aluminum alloy (old brand LD7 aluminum alloy) is a heat-treatable and strengthened alloy with high heat resistance. Its operating temperature is between 200℃ and 250℃. It can be used to manufacture aircraft engine pistons, impellers, wheels and other parts used at higher temperatures. The material has good hot and cold processing properties but poor welding performance.

[0003] A ventilation impeller part of a certain type of engine is made of 2A70 material. At the same time, it needs to be welded to the casing. Due to structural limitations, the part cannot be welded using solid-phase welding methods such as friction welding, and can only be welded using electron beam welding. However, due to the combined effects of the poor fusion welding performance of the 2A70 aluminum alloy itself, the constraints during part welding, and the interference of metal vapor during welding, the electron beam welding of the part is prone to defects such as cracks, pores, and discharge perforations, which affect the welding quality. Summary of the Invention

[0004] In view of this, an embodiment of the present application provides an electron beam welding method and fixture for 2A70 aluminum alloy, which at least partially solves the problem in the prior art that 2A70 aluminum alloy parts are prone to defects such as cracks, pores, and discharge perforations during electron beam welding, which affect the welding quality.

[0005] In a first aspect, an embodiment of the present application provides an electron beam welding method for 2A70 aluminum alloy, for welding parts made of 2A70 aluminum alloy, the method comprising:

[0006] Cleaning the parts, and pressing and assembling the two ends of the parts by a first fixture;

[0007] The assembled parts are placed in an electron beam welder, wherein a position of the parts to be welded is offset from a position directly below an electron gun of the electron beam welder, and a first electron beam flow is used to perform tack welding on the position to be welded;

[0008] Taking out the part, disassembling the first fixture, and fixing one end of the part with a second fixture to remove the external fixing constraint of the part during the welding process;

[0009] The fixed parts are placed in the electron beam welding machine, and the positions to be welded are welded using a second electron beam flow, wherein the electron beam spots of the second electron beam flow are multiple beams, and the energy of the second electron beam flow is greater than that of the first electron beam flow.

[0010] According to a specific implementation method of an embodiment of the present application, the welding parameters of the first electron beam are set to: working voltage of 150KV, working distance of 1020±10mm, surface collection current of 1903±15mA, deflection reference value of 782, collection current during welding of 1933±15mA, electron beam current of 3±0.5mA, and welding speed of 1200±10mm / min.

[0011] According to a specific implementation method of an embodiment of the present application, the second electron beam is controlled by a high-frequency coil to realize the electron beam deflection scanning function, and the electron beam spot is set to 3 beams, namely the first sub-beam, the second sub-beam and the third sub-beam, respectively. The first sub-beam is used for preheating, the second sub-beam is used for welding, and the third sub-beam is used for post-heating.

[0012] According to a specific implementation method of an embodiment of the present application, the welding parameters of the second sub-beam flow are set to: working voltage of 150KV, working distance of 1020±10mm, surface collection current of 1903±15mA, deflection reference value of 782, collection current during welding of 1923±15mA, electron beam current of 10±0.5mA, and welding speed of 1200±10mm / min; the energy of the first sub-beam flow and the third sub-beam flow are both less than the energy of the second sub-beam flow.

[0013] According to a specific implementation of an embodiment of the present application, the parameters of the first beam stream are set to AC_SET(5,1.0,0,500,0,0,0,30,1,8), the parameters of the second beam stream are set to AC_SET(5,1.0,0,2000,0,1,0,0,1,6), and the parameters of the third beam stream are set to AC_SET(5,1.0,0,500,0,1,0,-30,1,2). The parameters in the AC_SET are, from left to right, scanning waveform, X-direction scanning amplitude, Y-direction scanning amplitude, scanning frequency, scanning waveform rotation angle, scanning number, X-direction offset, Y-direction offset, offset mode and group; the welding time of the first beam stream is set to 200μs, the welding time of the second beam stream is set to 600μs, and the welding time of the third beam stream is set to 200μs.

[0014] According to a specific implementation method of the embodiment of the present application, when performing tack welding, the position to be welded is evenly divided into several sections, two sections arranged opposite to each other are a group, and tack welding is performed on each group in turn.

[0015] According to a specific implementation of the embodiment of the present application, when the two ends of the part are pressed and assembled by the first clamp, the weld gap at the position to be welded is less than 0.1 mm.

[0016] In the second aspect, an embodiment of the present application also provides an electron beam welding fixture, which includes the first fixture used for positioning welding, the first fixture including a first base plate, a cover plate, a clamping nut and a screw, the screw being vertically connected to the first base plate, the part and the cover plate being sleeved on the screw, and the part being located between the first base plate and the cover plate, the clamping nut being located on the side of the cover plate away from the part, and the clamping nut being threadedly connected to the screw.

[0017] According to a specific implementation method of an embodiment of the present application, the fixture also includes a second fixture used for welding, and the second fixture includes a second base plate. The second base plate is located at one end of the part, and the second base plate is provided with evenly distributed screws, and the outer peripheral surface of the part is clamped and fixed by the screws.

[0018] According to a specific implementation of the embodiment of the present application, a soft material layer is provided at the end of the screw that contacts the part.

[0019] Beneficial effects

[0020] The electron beam welding method and fixture for 2A70 aluminum alloy in the embodiment of the present application clamp the tack welding and the formal welding separately, which satisfies the parts clamping accuracy and avoids the rigid constraints in the formal welding process, reduces stress, and reduces the tendency of weld solidification cracks; the adopted parts staggered placement method reduces the interference of metal vapor on the electron beam and reduces the probability of weld defects caused by electron beam discharge; the high-frequency multi-beam welding method is adopted to realize the preheating, welding and post-heating treatment of the weld, reduce the temperature gradient during the weld solidification process, and reduce the welding stress and the tendency of weld solidification cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 A schematic diagram of a tack welding and pressing assembly according to an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of parts placement according to an embodiment of the present invention;

[0024] Figure 3 Schematic diagram of a clamping method during welding according to an embodiment of the present invention;

[0025] Figure 4is a schematic diagram of beam splitting of a second electron beam according to an embodiment of the present invention;

[0026] Figure 5 FIG. 4 is a schematic diagram illustrating electron beam parameters according to an embodiment of the present invention.

[0027] In the figure: 1. First base plate; 2. Cover plate; 3. Pressing nut; 4. Screw; 5. Part; 6. Position to be welded; 7. Electron gun; 8. Electron beam; 9. Second base plate; 10. Screw; 11. First sub-beam; 12. Second sub-beam; 13. Third sub-beam. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0029] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0030] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0032] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0033] In the first aspect, the present invention provides an electron beam welding method for 2A70 aluminum alloy, which is used to weld parts made of 2A70 aluminum alloy. In this embodiment, a ventilation impeller part of a certain type of engine is used as the welding object. Figures 1 to 5 Provide a detailed description.

[0034] Specifically, the electron beam welding method of 2A70 aluminum alloy includes the following steps:

[0035] Step 1: Clean the part 5 and press the two ends of the part 5 together with the first clamp. When cleaning, use an alloy brush to clean the area of ​​the part 5 to be welded to expose the metallic luster, and then use acetone to wipe it to remove impurities that affect welding to ensure the welding quality. Then, assemble the rear cover shell and the impeller and press them with the first clamp to ensure that the weld gap is less than 0.10mm. The specific assembly structure at this time refers to Figure 1 .

[0036] Step 2: Place the assembled part 5 together with the fixture into the electron beam welder. The position 6 of the part 5 to be welded is offset from the position directly below the electron gun 7 of the electron beam welder. Use the first electron beam flow to perform tack welding on the position 6 to be welded. The position relationship between the part 5 and the electron gun 7 is shown in Figure 2. Figure 2 As shown, the electron beam 8 emitted by the electron gun 7 is deflected by the deflection coil within the electron gun 7 to accommodate the positional offset of the part 5. In this step, the offset distance between the weld position 6 of the part 5 and the position directly below the electron gun 7 of the electron beam welder ranges from 0 to 60 mm. Preferably, the offset distance is set to 60 mm.

[0037] Step 3: Take out the part 5 after positioning welding, disassemble the first fixture, fix one end of the part 5 with the second fixture, and remove the external fixing constraint of the part 5 during the welding process. In this step, only fix the part 5 by clamping the outer circle of the lower end of the part 5. Figure 3 As shown in the structural diagram, at this time, there is no external constraint force at both ends of the axial position of part 5. Therefore, the rigid constraint in the formal welding process is avoided during welding, the stress is reduced, and the tendency of weld solidification cracks is reduced.

[0038] Step 4: Place the fixed part 5 into the electron beam welder and use the second electron beam to weld the position 6 to be welded. The electron beam spot of the second electron beam is multi-beam, and the energy of the second electron beam is greater than that of the first electron beam. It should be noted that the placement position of the part 5 is consistent with the position during positioning welding. Figure 2 .

[0039] Step 5: Open the vacuum chamber of the electron beam welder and take out the welded part 5.

[0040] In this embodiment, during welding, part 5 is positioned not directly below electron gun 7 but offset from it. This allows for welding via electron beam deflection, mitigating interference from metal vapor on electron gun 7 and preventing perforation defects in the weld caused by discharge. Furthermore, separate clamping for tack welding and the main weld ensures accurate clamping of part 5 while avoiding rigid constraints during the main weld, reducing stress and minimizing the tendency for solidification cracks to form in the weld.

[0041] In one specific embodiment, the second electron beam is controlled by a high-frequency coil to achieve a deflection and scanning function for electron beam 8, splitting the electron beam spot into three beams: a first sub-beam 11, a second sub-beam 12, and a third sub-beam 13. First sub-beam 11 is used for preheating, second sub-beam 12 is used for welding, and third sub-beam 13 is used for post-heating. In this embodiment, a high-frequency multi-beam welding method is employed to achieve weld preheating, welding, and post-heating, reducing temperature gradients during weld solidification, welding stress, and the tendency for weld solidification cracks to occur.

[0042] In a specific embodiment, the welding parameters of the first electron beam are set as follows: working voltage of 150KV, working distance of 1020±10mm, surface collection current of 1903±15mA, deflection reference value of 782, collection current during welding of 1933±15mA, electron beam current of 3±0.5mA, and welding speed of 1200±10mm / min.

[0043] In another specific embodiment, the welding parameters of the second sub-beam 12 are set as follows: the working voltage is 150KV, the working distance is 1020±10mm, the surface collection current is 1903±15mA, the deflection reference value is 782, the collection current during welding is 1923±15mA, the electron beam current is 10±0.5mA, and the welding speed is 1200±10mm / min; the energy of the first sub-beam 11 and the third sub-beam 13 is less than the energy of the second sub-beam 12.

[0044] It should be noted that the electron beam current value in the above parameters is for the case where the weld thickness is 2.0 mm (with a 2.0 mm thick lock bottom on the back). The electron beam current value can be adjusted according to a certain proportion when welding other weld thicknesses.

[0045] For the settings of each beam of the second electron beam flow, refer to the parameter settings. Figure 5As shown in FIG. 1 , the parameters of the first beam stream 11 are set to AC_SET(5,1.0,0,500,0,0,0,30,1,8), the parameters of the second beam stream 12 are set to AC_SET(5,1.0,0,2000,0,1,0,0,1,6), and the parameters of the third beam stream 13 are set to AC_SET(5,1.0,0,500,0,1,0,-30,1,2). The parameters in AC_SET are, from left to right, the scanning waveform, the X-direction scanning amplitude, and the Y-direction scanning amplitude. Directional scanning amplitude, scanning frequency, scanning waveform rotation angle, scanning number, X-direction offset, Y-direction offset, offset mode and group; the welding time of the first sub-beam flow 11 is set to 200μs, the welding time of the second sub-beam flow 12 is set to 600μs, and the welding time of the third sub-beam flow 13 is set to 200μs; by setting the welding time of each sub-beam, high-frequency beam splitting is achieved, and in actual welding, three electron beams 8 work simultaneously, realizing preheating, welding and post-heating processing in the welding process, such as Figure 4 shown.

[0046] In one embodiment, when performing tack welding, the weld location 6 is evenly divided into several segments, with two oppositely positioned segments forming a group. Tack welding is then performed on each group sequentially. For example, the weld location 6 is evenly divided into eight segments, with two oppositely positioned segments forming a group, resulting in four groups of welds. These four groups of welds are then welded sequentially. This ensures weld uniformity by sequentially welding symmetrically positioned welds, preventing cracks or deformation in the welds and improving weld quality.

[0047] In the second aspect, the embodiment of the present application further provides an electron beam welding fixture, which is applied to any embodiment of the first aspect above, and the fixture includes a first fixture used for positioning welding, the first fixture includes a first base plate 1, a cover plate 2, a clamping nut 3 and a screw 4, the screw 4 is vertically connected to the first base plate 1, the part 5 and the cover plate 2 are sleeved on the screw 4, and the part 5 is located between the first base plate 1 and the cover plate 2, the clamping nut 3 is located on the side of the cover plate 2 away from the part 5, and the clamping nut 3 is threadedly connected to the screw 4. The specific structure is described in detail in the embodiment of the present application. Figure 1 .

[0048] In one embodiment, the fixture further includes a second fixture used for welding, the second fixture including a second base plate 9, the second base plate 9 is located at one end of the part 5, and the second base plate 9 is provided with uniformly distributed screws 10, which are used to clamp and fix the outer peripheral surface of the part 5. For specific structure, refer to Figure 3 The second base plate 9 is provided with a circle of outer extension edges in the circumference, and screws 10 are installed on the outer extension edges. The screws 10 are used to clamp and fix the circumference of the bottom of the part 5. That is, the screws 10 apply radial force to the part 5 to achieve the clamping and fixing effect.

[0049] Specifically, a soft material layer is provided at the end of the screw 10 that contacts the part 5. By providing the soft material layer, problems such as the screw 10 scratching the surface of the part 5 or the surface of the part 5 being deformed by external force during the clamping process can be avoided.

[0050] The embodiment provided by the present invention clamps the tack welding and the formal welding separately, which satisfies the parts clamping accuracy and avoids the rigid constraints in the formal welding process, reduces stress, and reduces the tendency of weld solidification cracks. The parts staggered placement method adopted in the present invention reduces the interference of metal vapor on the electron beam and reduces the probability of weld defects caused by electron beam discharge. The high-frequency multi-beam welding method adopted in the present invention realizes the preheating, welding and post-heating treatment of the weld, reduces the temperature gradient in the weld solidification process, reduces welding stress and the tendency of weld solidification cracks.

[0051] The comprehensive adoption of the welding measures and parameters in this method can avoid defects such as cracks, perforations, and pores in the welds and achieve qualified welding of parts.

[0052] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for electron beam welding of 2A70 aluminum alloy, for welding parts (5) made of 2A70 aluminum alloy, characterized in that: The method comprises: Cleaning the part (5), and pressing and assembling the two ends of the part (5) using a first clamp; The assembled part (5) is placed in an electron beam welding machine, wherein a position (6) of the part (5) to be welded is offset from a position directly below an electron gun (7) of the electron beam welding machine, and a first electron beam flow is used to perform positioning welding on the position (6) to be welded; Taking out the part (5), disassembling the first fixture, fixing one end of the part (5) with a second fixture, and removing the external fixing constraint of the part (5) during the welding process; The fixed part (5) is placed in the electron beam welding machine, and the position to be welded (6) is welded using a second electron beam flow, wherein the energy of the second electron beam flow is greater than the energy of the first electron beam flow; The second electron beam current is controlled by a high-frequency coil to realize an electron beam current deflection scanning function, and the electron beam spot is set to three beams, namely a first sub-beam current (11), a second sub-beam current (12) and a third sub-beam current (13), wherein the first sub-beam current (11) is used for preheating, the second sub-beam current (12) is used for welding, and the third sub-beam current (13) is used for post-heating; the welding time of the first sub-beam current (11) is set to 200 μs, the welding time of the second sub-beam current (12) is set to 600 μs, and the welding time of the third sub-beam current (13) is set to 200 μs.

2. The electron beam welding method for 2A70 aluminum alloy according to claim 1, characterized in that: The welding parameters of the first electron beam are set as follows: working voltage of 150KV, working distance of 1020±10mm, surface collection current of 1903±15mA, deflection reference value of 782, collection current during welding of 1933±15mA, electron beam current of 3±0.5mA, and welding speed of 1200±10mm / min.

3. The electron beam welding method for 2A70 aluminum alloy according to claim 1, characterized in that: The welding parameters of the second sub-beam (12) are set as follows: working voltage of 150KV, working distance of 1020±10mm, surface collection current of 1903±15mA, deflection reference value of 782, collection current during welding of 1923±15mA, electron beam current of 10±0.5mA, and welding speed of 1200±10mm / min; the energy of the first sub-beam (11) and the third sub-beam (13) are both less than the energy of the second sub-beam (12).

4. The electron beam welding method for 2A70 aluminum alloy according to claim 1, characterized in that: When performing tack welding, the position to be welded (6) is evenly divided into several sections, two sections arranged opposite to each other form a group, and tack welding is performed on each group in turn.

5. The electron beam welding method for 2A70 aluminum alloy according to claim 1, characterized in that: When the two ends of the part (5) are pressed and assembled by the first clamp, the weld gap at the position to be welded (6) is less than 0.1 mm.

6. An electron beam welding fixture for use in the electron beam welding method for 2A70 aluminum alloy according to any one of claims 1 to 5, characterized in that: The fixture includes the first fixture used for positioning welding, the first fixture includes a first base plate (1), a cover plate (2), a clamping nut (3) and a screw (4), the screw (4) is vertically connected to the first base plate (1), the part (5) and the cover plate (2) are sleeved on the screw (4), and the part (5) is located between the first base plate (1) and the cover plate (2), the clamping nut (3) is located on the side of the cover plate (2) away from the part (5), and the clamping nut (3) is threadedly connected to the screw (4).

7. The electron beam welding fixture according to claim 6, characterized in that: The clamp also includes a second clamp used for welding, the second clamp including a second base plate (9), the second base plate (9) is located at one end of the part (5), and the second base plate (9) is provided with evenly distributed screws (10), and the outer peripheral surface of the part (5) is clamped and fixed by the screws (10).

8. The electron beam welding fixture according to claim 7, characterized in that: One end of the screw (10) in contact with the part (5) is provided with a soft material layer.

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