Friction stir welding process based on welding-following hot ironing shape righting technology

Abstract

The invention discloses a friction stir welding process based on a welding-following hot ironing shape righting technology, which is characterized in that a hot ironing shape righting device is connected to a main shaft shell of friction stir welding equipment, in the friction stir welding process, the hot ironing shape righting device synchronously moves along with the main shaft shell, and the working surface of the hot ironing shape righting device is always compacted on a welding seam and a workpiece. According to the method, all-directional welding-following correction of the friction stir welding seam is achieved, the friction stir lap welding seam and a workpiece thereof can be corrected in real time, the friction stir butt welding seam and the workpiece thereof can be corrected in real time, the corresponding post-welding heat treatment procedure can be simplified, and the production efficiency is improved. And the key point is that the friction stir welding seam deformation can be accurately controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of friction stir welding, and particularly relates to a friction stir welding process based on in - process thermal ironing straightening technology. Background Art

[0002] During the friction stir welding process, prestressed fixtures (mainly including triangular trusses, pressing parts, and pressing plates) are usually used to prevent workpiece deformation. Among them, the triangular truss is used to provide stability, the pressing part is used to apply prestress, and the pressing plate acts directly on the workpiece. In this way, uniform pressure can be applied to the workpiece during welding to reduce post - welding deformation.

[0003] In the prior art, the literature CN111438435B discloses a stationary shoulder assisted friction stir adhesive welding method, which adjusts the temperature on the stationary shoulder plate in the deformation area according to the judged material deformation situation to achieve the function of controlling deformation. When the material deforms due to heat, the material deformation situation is judged by pressure. If the material bulges upward, it will squeeze the stationary shoulder plate, so the gas pressure above this stationary shoulder plate will increase. If the material concaves inward, the force on the stationary shoulder plate is reduced.

[0004] As mentioned above, almost all the existing straightening technologies in the friction stir welding process prevent workpiece deformation by applying stress to the workpiece, and the tools used can only act on the periphery of the weld, resulting in micro - deformation still existing in the area near the weld, and further resulting in a large amount of workpiece deformation. Therefore, it is necessary to develop a method / process that can accurately control the deformation amount of the friction stir weld. Summary of the Invention

[0005] At least to solve the technical problems mentioned in the background art, the purpose of the present invention is to provide a friction stir welding process based on in - process thermal ironing straightening technology.

[0006] The present invention adopts the following technical solutions.

[0007] A friction stir welding process based on in - process thermal ironing straightening technology connects a thermal ironing straightening device to the spindle housing of a friction stir welding equipment. During the friction stir welding process, the thermal ironing straightening device moves synchronously with the spindle housing, and the working surface of the thermal ironing straightening device always compacts on the weld and the workpiece.

[0008] Further, the rigid working surface of the thermal ironing straightening device abuts against the top surface of the workpiece on both sides of the weld near the spindle and / or the weld area, and the flexible working surface of the thermal ironing straightening device abuts against the weld area and the top surface of the workpiece far from the spindle.

[0009] Further, the thermal ironing straightening device includes a rigid iron, and a flexible ironing part is arranged in the middle of the rigid iron, and the length of the flexible ironing part is not less than the length of the workpiece weld.

[0010] Furthermore, the flexible ironing part includes a bag body woven from nickel-chromium electrothermal alloy wire, and nickel-chromium electrothermal alloy beads with a particle size not greater than 3 mm are filled in the bag body. The bag body is connected to a temperature control system.

[0011] Furthermore, the head end of the bag body is connected to the iron, and the tail end of the bag body is connected to a fixing frame, and the fixing frame is located near the starting point of the weld.

[0012] Preferably, the diameter of the bag body is 40 - 70 mm, and the diameter of the bag body refers to the outer diameter after the bag body is filled with granular materials.

[0013] The friction stir welding process in the present invention includes the following steps: Step 1: Install the workpiece to be welded on the welding workbench, and the bottom surface of the workpiece to be welded abuts against the working surface of the welding workbench. Step 2: Install the fixing frame near the starting point of the weld of the workpiece to be welded, adjust the welding tool head of the friction stir welding equipment to the starting point of the weld, and fixedly connect the iron to the spindle housing. Step 3: Set the friction stir welding process parameters, set the straightening temperature of the thermal ironing straightening device, and then start welding; during the welding process, the rigid working surface of the iron always presses on the top surface of the workpiece on both sides of the weld near the spindle and / or the weld area, and the bag body is compacted on the weld area and the top surface of the workpiece far from the spindle. Step 4: After welding, remove the welding tool head and the thermal ironing straightening device.

[0014] Furthermore, for workpieces that require post-welding heat treatment (tempering treatment), after welding, first remove the iron from the spindle housing, then remove the welding tool head, and further set the heat preservation temperature of the thermal ironing straightening device. After heat preservation, remove the thermal ironing straightening device.

[0015] Beneficial effects: By adopting the solution of the present invention, all-round in-welding correction of friction stir welds is achieved. It can not only correct the friction stir lap weld and its workpiece in real time, but also correct the friction stir butt weld and its workpiece in real time. It can also simplify the corresponding post-welding heat treatment process. The key is that it can accurately control the deformation amount (warpage amount) of the friction stir weld within the micron level (less than 1 mm); in the present invention, the used thermal ironing straightening device has a simple structure, good flexibility, and a simple and convenient operation process. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the friction stir welding process in Embodiment 1, and the arrow in the figure indicates the welding direction; Figure 2 is Figure 1 the cross-sectional schematic diagram of; Figure 3 Schematic diagram of the friction stir welding process in Embodiment 2; Figure 4 Schematic diagram of the main direction of friction stir welding in Embodiment 2. Specific implementation manner

[0017] The following combines the accompanying drawings to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. In the present invention, within a unit length of one meter, the weight of the nickel-chromium electrothermal alloy beads filled in the bag body is not less than thirty kilograms, so as to effectively prevent the workpiece from warping when the bag body is pressed on the workpiece. Embodiment 1

[0018] Combined with Figures 1 to 2 As shown, a friction stir welding process based on the in-situ heat ironing and straightening technology connects the heat ironing and straightening device to the flange 1 of the spindle housing of the friction stir welding equipment. During the friction stir welding process, the heat ironing and straightening device moves synchronously with the flange 1 of the spindle housing, and the working surface of the heat ironing and straightening device always presses on the weld and the workpiece 6. The rigid working surface of the heat ironing and straightening device abuts against the top surface of the workpiece 6 on both sides of the weld near the spindle, and the flexible working surface of the heat ironing and straightening device abuts against the weld area and the top surface of the workpiece 6 far from the spindle.

[0019] In this embodiment, the heat ironing and straightening device includes a rigid iron 2, and the rigid iron 2 is connected to the flange 1 through an adjusting mechanism 7. The adjusting mechanism 7 is used to adjust the height of the rigid iron 2. A flexible ironing part is arranged in the middle of the rigid iron 2, and the length of the flexible ironing part is not less than the length of the weld of the workpiece 6; the flexible ironing part includes a bag body 3 woven with nickel-chromium electrothermal alloy wires (that is, a flexible pocket woven with nickel-chromium electrothermal alloy wires), and the bag body 3 is filled with nickel-chromium electrothermal alloy beads 4 with a particle size not greater than 3 mm (refer to Figure 4 Shown in the cross-section), the bag body 3 is connected to the temperature control system. Among them, the head end of the bag body 3 is connected to the rigid iron 2 (specifically, connected to the tail of the rigid iron 2), the tail end of the bag body 3 is connected to the fixing frame 5, and the fixing frame 5 is located near the starting point of the weld. During application, the diameter range of the bag body 3 can be selected from 40 to 70 mm, and it can be specifically selected according to the plate thickness of the workpiece 6.

[0020] One of the friction stir welding processes based on the in-situ heat ironing and straightening technology in this embodiment is used for lap welding of aluminum alloy plates with a wall thickness of 2.5 mm. The steps include: Step 1, install the workpiece 6 to be welded on the welding workbench, and the bottom surface of one workpiece 6 to be welded (the lower workpiece to be welded) abuts against the working surface of the welding workbench; Step 2: Install the fixing bracket 5 near the welding starting point of the workpiece to be welded 6. Adjust the welding tool head 8 of the friction stir welding equipment to the welding starting point. Fix the rigid iron 2 to the flange 1 of the spindle housing and adjust the height of the rigid iron 2 until the working surface of the rigid iron 2 always presses tightly on the top surface of the workpiece 6 (the upper workpiece to be welded) on both sides of the weld groove; Step 3: Set the friction stir welding process parameters and the straightening temperature of the hot ironing straightening device, and then start welding. During the welding process, the rigid working surface of the iron always presses tightly on the top surface of the workpiece 6 (the upper workpiece to be welded) on both sides of the weld near the spindle and can translate synchronously with the spindle housing. The bag body 3 is pressed tightly on the weld area and the top surface of the workpiece 6 (the upper workpiece to be welded) far from the spindle; Step 4: After welding, remove the welding tool head 8 and the hot ironing straightening device. Example 2

[0021] Refer to the hot ironing straightening device in Example 1 and combine with Figure 3 and Figure 4 As shown, the rigid iron 2 has left and right parts that can respectively act on the top surface of the workpiece 6 on both sides of the weld. The front end of the bag body 3 is connected to the front part of the rigid iron 2. In this example, the second friction stir welding process based on the in - process hot ironing straightening technology is used for the butt welding of carbon steel plates with a wall thickness of 6 mm. The width of the carbon steel plate is 0.2 m and the length is 1 m. The steps include: Step 1: Install the workpiece to be welded 6 on the welding workbench, and the bottom surfaces of the two workpieces to be welded 6 are abutted against the working surface of the welding workbench; Step 2: Install the fixing bracket 5 near the welding starting point of the workpiece to be welded 6. Adjust the welding tool head 8 of the friction stir welding equipment to the welding starting point. Fix the rigid iron 2 to the flange 1 of the spindle housing and adjust the height of the rigid iron 2 until the working surface of the rigid iron 2 always presses tightly on the top surface of the workpiece 6 on both sides of the weld groove; Step 3: Set the friction stir welding process parameters and the straightening temperature of the hot ironing straightening device, and then start welding. During the welding process, the rigid working surface of the iron always presses tightly on the top surface of the workpiece 6 on both sides of the weld near the spindle and can translate synchronously with the spindle housing. The bag body 3 is pressed tightly on the weld area and the top surface of the workpiece 6 (the upper workpiece to be welded) far from the spindle; Step 4: After welding, first remove the iron from the flange 1 of the spindle housing, then remove the welding tool head 8, and further set the holding temperature of the hot ironing straightening device (tempering treatment at 450 degrees). After the holding is completed, remove the hot ironing straightening device; Step 5: Turn the workpiece 6 over, and then perform welding again according to Steps 1 - 4.

[0022] Some key technical points in the present invention: During the welding process, first, the rigid iron 2 is used to timely perform thermal ironing and straightening on both sides of the welding part. After thermal ironing and straightening, a specific flexible ironing part is used to immediately continuously compact / press the welding part and its two sides. The bag body is slowly dragged forward during the process of compacting the workpiece and the weld until the welding is completed. The weld and its two sides hardly deform during the whole welding process, thus achieving precise control of the deformation amount of the friction stir weld; during the welding process, whether there are burrs or concave areas on the edge of the shoulder of the welding tool head, the thermal ironing and straightening device can adaptively adjust and can precisely control the deformation amount of the friction stir weld, solving the technical problem of poor straightening effect caused by the uneven surface of the weld; in addition, the deformation amount of the workpiece can be adjusted by changing the number of nickel-chromium electrothermal alloy beads filled in the bag body.

[0023] Comparative example: Friction stir welding is carried out using the same specifications of workpieces and welding process parameters as in Example 2. During the friction stir welding process, a prestressed fixture is used to always press the workpiece tightly until the welding is completed.

[0024] Example 3: The third friction stir welding process based on the in-situ thermal ironing and straightening technology. Referring to the thermal ironing and straightening device in Example 2, the difference from Example 1 is that the rigid iron 2 in Example 1 is applied, and during the welding process, the rigid working surface (the working surface of the rigid iron 2) of the thermal ironing and straightening device is always abutted against the top surface of the workpiece 6 on both sides of the weld near the main shaft and the weld area (that is, the rigid iron 2 is used to press the weld and the workpiece at the same time); it is used for butt welding of carbon steel plates with a wall thickness of 6 mm, the width of the carbon steel plate is 0.2 m, the length is 1 m, and double-sided welding is carried out.

[0025] The deformation amounts after welding in Example 2, Example 3 and the comparative example are detected. The results show that: in Example 2, the deformation amount of the workpiece is not more than 1 mm (the maximum warping amount of the workpiece edge relative to the reference plane, and this warping amount also reflects the size of the weld deformation amount), in Example 3, the deformation amount of the workpiece is also not more than 1 mm (the maximum warping amount of the workpiece edge relative to the reference plane), and in the comparative example, the deformation amount of the workpiece is 3 - 4 mm (the maximum warping amount of the workpiece edge relative to the reference plane).

Claims

1. A friction stir welding process based on hot ironing correction technology, characterized in that: The hot ironing orthopedic device is connected to the spindle housing of the stir friction welding equipment. During the stir friction welding process, the hot ironing orthopedic device moves synchronously with the spindle housing, and the working surface of the hot ironing orthopedic device is always pressed on the weld and the workpiece.

2. The friction stir welding process according to claim 1, characterized in that: The rigid working surface of the hot ironing orthopedic device is against the top surface of the workpiece and / or the weld area on both sides of the weld near the spindle, and the flexible working surface of the hot ironing orthopedic device is against the weld area and the top surface of the workpiece away from the spindle.

3. The friction stir welding process according to claim 2, characterized in that: The hot ironing orthopedic device comprises a rigid iron, a flexible ironing portion is arranged in the middle of the rigid iron, and the length of the flexible ironing portion is not less than the length of the weld of the workpiece.

4. The friction stir welding process according to claim 3, characterized in that: The flexible ironing part comprises a bag body woven with nickel-chromium electric heating alloy wires, the bag body is filled with nickel-chromium electric heating alloy beads with a particle size not greater than 3mm, and the bag body is connected to a temperature control system.

5. The friction stir welding process according to claim 4, characterized in that: The front end of the bag body is connected to the iron, and the rear end of the bag body is connected to a fixing frame, which is located near the starting point of the welding seam.

6. The friction stir welding process according to claim 5, characterized in that: The diameter of the bag is 40~70mm.

7. The friction stir welding process according to claim 6, characterized in that the steps include: Step 1, installing the workpiece to be welded on the welding workbench, with the bottom surface of the workpiece to be welded against the working surface of the welding workbench; Step 2, installing the fixing frame near the welding starting point of the workpiece to be welded, adjusting the welding tool head of the friction stir welding equipment to the welding starting point, and fixing the iron on the spindle housing; Step 3, set the friction stir welding process parameters, set the orthopedic temperature of the hot ironing orthopedic device, and then start welding; during the welding process, the rigid working surface of the iron is always pressed on the top surface of the workpiece on both sides of the weld near the spindle and / or the weld area, and the bag body is compacted on the weld area and the top surface of the workpiece away from the spindle; Step 4: After welding, remove the welding tool head and the hot ironing orthopedic device.

8. The friction stir welding process according to claim 7, characterized in that: For workpieces that require post-weld heat treatment, after welding, first remove the iron from the spindle housing, then remove the welding tool head, and then further set the insulation temperature of the hot ironing correction device. After the insulation is completed, remove the hot ironing correction device.

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