A friction stir welding process based on hot ironing correction technology

Abstract

The present invention discloses a friction stir welding process based on concurrent hot ironing correction technology. A hot ironing correction device is connected to the spindle housing of the friction stir welding equipment. During the friction stir welding process, the hot ironing correction device moves synchronously with the spindle housing, and the working surface of the hot ironing correction device is always pressed against the weld and the workpiece. The present invention achieves all-round concurrent correction of friction stir welds, enabling real-time correction of not only friction stir lap welds and their workpieces, but also friction stir butt welds and their workpieces. It also simplifies the corresponding post-weld heat treatment process. Crucially, it can precisely control the deformation of the friction stir weld.

Description

Technical Field

[0001] The invention belongs to the technical field of friction stir welding, and in particular relates to a friction stir welding process based on a hot ironing correction technology. Background Art

[0002] During friction stir welding, a prestressed fixture (primarily consisting of a triangular truss, a pressure piece, and a pressure plate) is often used to prevent workpiece deformation. The triangular truss provides stability, the pressure piece applies prestress, and the pressure plate acts directly on the workpiece. This ensures uniform pressure on the workpiece during welding, minimizing post-weld deformation.

[0003] Prior art document CN111438435B discloses a stationary shoulder-assisted friction stir welding method. This method regulates deformation by adjusting the temperature of the stationary shoulder plate in the deformation zone based on the material's deformation. When the material deforms due to heat, the pressure is used to determine the deformation. If the material protrudes upward, it compresses the stationary shoulder plate, increasing the gas pressure above it. If the material concave downward, the force on the stationary shoulder plate is reduced.

[0004] As previously mentioned, existing correction techniques used in friction stir welding (FSW) almost exclusively apply stress to the workpiece to prevent deformation. However, the tools used only act on the weld periphery, resulting in minor deformation near the weld and, consequently, significant workpiece deformation. Therefore, it is necessary to develop a method or process that can precisely control the deformation of the FSW weld. Summary of the Invention

[0005] At least in order to solve the technical problems mentioned in the background technology, the present invention aims to provide a friction stir welding process based on hot ironing correction technology.

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

[0007] A friction stir welding process based on hot ironing correction technology is proposed. The hot ironing correction device is connected to the main shaft housing of the friction stir welding equipment. During the friction stir welding process, the hot ironing correction device moves synchronously with the main shaft housing, and the working surface of the hot ironing correction device is always pressed against the weld and the workpiece.

[0008] Furthermore, 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.

[0009] Furthermore, the hot ironing orthopedic device includes a rigid iron, a flexible ironing portion is provided 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.

[0010] Furthermore, the flexible ironing part includes 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 3 mm, and the bag body is connected to a temperature control system.

[0011] Furthermore, 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 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 of the bag body after it is filled with granular materials.

[0013] The friction stir welding process of the present invention comprises the following steps:

[0014] Step 1: Mount the workpiece to be welded on the welding table, with the bottom surface of the workpiece against the working surface of the welding table;

[0015] Step 2: Install the fixing frame near the welding starting point of the workpiece to be welded, adjust the welding tool head of the friction stir welding equipment to the welding starting point, and fix the iron to the spindle housing;

[0016] Step 3: Set the friction stir welding process parameters and the correction temperature of the hot iron correction device, and then start welding. During the welding process, the rigid working surface of the iron is always pressed against the top surface of the workpiece on both sides of the weld near the spindle and / or the weld area, and the bag is compacted in the weld area and the top surface of the workpiece away from the spindle.

[0017] Step 4: After welding is completed, remove the welding tool head and the hot ironing correction device.

[0018] Furthermore, for workpieces that require post-weld heat treatment (tempering), after welding is completed, 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.

[0019] Beneficial effects: The solution of the present invention realizes all-round correction of stir friction welds during welding, which can not only correct the stir friction lap welds and their workpieces in real time, but also correct the stir friction butt welds and their workpieces in real time, and can also simplify the corresponding post-weld heat treatment process. The key is that the deformation (warping) of the stir friction welds can be accurately controlled at the micron level (less than 1 mm); in the present invention, the hot ironing correction device used has a simple structure, good flexibility, and a simple and convenient operation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the friction stir welding process in Example 1, where the arrows indicate the welding direction;

[0021] Figure 2 for Figure 1 Schematic cross-sectional view of ;

[0022] Figure 3 Schematic diagram of the friction stir welding process in Example 2;

[0023] Figure 4 Schematic diagram of the main direction of friction stir welding in Example 2. DETAILED DESCRIPTION

[0024] The following, in conjunction with the accompanying drawings, clearly and completely describes the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. In the present invention, the weight of the nickel-chromium electrothermal alloy beads filled in the bag is no less than 30 kilograms per one meter of length, so that the bag can effectively prevent the workpiece from warping when pressed against it. Example 1

[0025] Combine Figures 1 to 2 The figure shows a friction stir welding process based on hot ironing and correction technology. The hot ironing correction device is connected to the flange 1 of the main shaft housing of the friction stir welding equipment. During the friction stir welding process, the hot ironing correction device moves synchronously with the flange 1 of the main shaft housing, and the working surface of the hot ironing correction device is always pressed against the weld seam and the workpiece 6. The rigid working surface of the hot ironing correction device is in contact with the top surface of the workpiece 6 on both sides of the weld seam near the main shaft, while the flexible working surface of the hot ironing correction device is in contact with the weld seam area and the top surface of the workpiece 6 away from the main shaft.

[0026] In this embodiment, the hot ironing orthosis device includes a rigid iron 2, which is connected to the flange 1 through an adjustment mechanism 7. The adjustment mechanism 7 is used to adjust the height of the rigid iron 2. A flexible ironing portion is provided in the middle of the rigid iron 2. The length of the flexible ironing portion is not less than the length of the weld of the workpiece 6; the flexible ironing portion includes a bag body 3 woven with nickel-chromium electrothermal alloy wire (i.e., a flexible pocket woven with nickel-chromium electrothermal alloy wire), and the bag body 3 is filled with nickel-chromium electrothermal alloy beads 4 with a particle size of not more than 3 mm (refer to Figure 4 (See the cross-section diagram) Bag 3 is connected to the temperature control system. The front end of bag 3 is connected to rigid iron 2 (specifically, to the rear end), and the rear end of bag 3 is connected to a mounting bracket 5, located near the weld starting point. In practice, the diameter of bag 3 can range from 40 to 70 mm, depending on the thickness of workpiece 6.

[0027] In this embodiment, a friction stir welding process based on the hot ironing correction technology is used for lap welding of aluminum alloy plates with a wall thickness of 2.5 mm. The steps include:

[0028] Step 1: Install the workpieces 6 to be welded on the welding workbench, with the bottom surface of one of the workpieces 6 (the lower workpiece to be welded) resting against the working surface of the welding workbench;

[0029] Step 2: Install the fixing frame 5 near the welding starting point of the workpiece 6 to be welded, 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 is always pressed against the top surface of the workpiece 6 (the upper workpiece to be welded) on both sides of the weld groove;

[0030] Step 3: Set the friction stir welding process parameters and the corrective temperature of the hot iron corrective device, and then start welding. During the welding process, the rigid working surface of the iron is always pressed against the top surface of the workpiece 6 (the upper workpiece to be welded) on both sides of the weld near the spindle and can be translated synchronously with the spindle housing. The bag body 3 is pressed against the weld area and the top surface of the workpiece 6 (the upper workpiece to be welded) away from the spindle.

[0031] Step 4: After welding is completed, remove the welding tool head 8 and the hot ironing orthopedic device. Example 2

[0032] Refer to the hot ironing orthosis device in Example 1 and combine Figure 3 and Figure 4 As shown, the rigid iron 2 has two left and right parts that can act on the top surface of the workpiece 6 on both sides of the weld, and the front end of the bag body 3 is connected to the front of the rigid iron 2. This embodiment is a second friction stir welding process based on the welding hot iron correction technology. It is used for butt welding of carbon steel plates with a wall thickness of 6mm, a width of 0.2m and a length of 1m. The steps include:

[0033] Step 1: Install the workpieces 6 to be welded on a welding workbench, with the bottom surfaces of the two workpieces 6 against the working surface of the welding workbench;

[0034] Step 2: Install the fixing frame 5 near the welding starting point of the workpiece 6 to be welded, 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 is always pressed against the top surface of the workpiece 6 on both sides of the weld groove;

[0035] Step 3: Set the friction stir welding process parameters and the corrective temperature of the hot iron corrective device, and then start welding. During the welding process, the rigid working surface of the iron is always pressed against the top surface of the workpiece 6 on both sides of the weld near the spindle and can move synchronously with the spindle housing. The bag body 3 is pressed against the weld area and the top surface of the workpiece 6 away from the spindle.

[0036] Step 4: After welding is completed, 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 orthopedic device (tempering treatment at 450 degrees). After the holding temperature is completed, remove the hot ironing orthopedic device;

[0037] Step 5: Turn the workpiece 6 over and weld it again according to steps 1-4.

[0038] Some key technical points of the present invention are as follows: during the welding process, the rigid iron 2 is first used to promptly perform hot ironing correction on both sides of the welding part. After the hot ironing correction, the welding part and its both sides are immediately and continuously compacted / tightened using a specific flexible ironing part. The bag body is slowly dragged forward in the process of compacting the workpiece and the weld until the welding is completed. The weld and its both sides will hardly deform during the entire welding process, thereby achieving precise control of the deformation of the stir friction weld. During the welding process, regardless of whether the shoulder edge of the welding tool head produces flash or a concave area, the hot ironing correction device can adaptively adjust and can precisely control the deformation of the stir friction weld, solving the technical problem of poor correction effect caused by the uneven weld surface. In addition, the deformation of the workpiece can be adjusted by changing the number of nickel-chromium electrothermal alloy beads filled in the bag body.

[0039] Comparative Example: Friction stir welding was performed using a workpiece with the same specifications and welding process parameters as in Example 2. During the friction stir welding process, a prestressed fixture was used to press the workpiece until the welding was completed.

[0040] Example 3: The third friction stir welding process based on the hot ironing correction technology during welding, referring to the hot ironing correction device in Example 2, differs from Example 1 in that: the rigid iron 2 in Example 1 is used, and during the welding process, the rigid working surface of the hot ironing correction device (the working surface of the rigid iron 2) is always kept against the top surface of the workpiece 6 and the weld area on both sides of the weld near the main axis (that is, the rigid iron 2 is used to simultaneously press the weld and the workpiece); it is used for butt welding of carbon steel plates with a wall thickness of 6 mm, a width of 0.2 m and a length of 1 m, and double-sided welding is performed.

[0041] The deformation after welding in Example 2, Example 3, and the comparative example was tested. The results showed that the deformation of the workpiece in Example 2 was no more than 1 mm (the maximum warping of the workpiece edge relative to the reference plane, which also reflects the deformation of the weld). The deformation of the workpiece in Example 3 was also no more than 1 mm (the maximum warping of the workpiece edge relative to the reference plane). The deformation of the workpiece in the comparative example was 3 to 4 mm (the maximum warping 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 steps include: Step 1: Mount the workpiece to be welded on the welding table, with the bottom surface of the workpiece against the working surface of the welding table; Step 2: Install the fixing frame near the welding starting point of the workpiece to be welded, adjust the welding tool head of the friction stir welding equipment to the welding starting point, and fix the iron to the spindle housing; Step 3: Connect the hot ironing orthopedic device to the spindle housing of the friction stir welding equipment; set the friction stir welding process parameters and the orthopedic temperature of the hot ironing orthopedic device, and then start welding; during the welding process, the hot ironing orthopedic device moves synchronously with the spindle housing, the rigid working surface of the iron is always pressed 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 hot ironing orthopedic device is pressed against the weld area and the top surface of the workpiece away from the spindle; the bag is compacted in the weld area and the top surface of the workpiece away from the spindle; Step 4: After welding is completed, remove the welding tool head and the hot ironing correction device; Among them, the hot ironing orthotic device includes a rigid iron, a flexible ironing part is provided 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; the flexible ironing part includes a bag body woven with nickel-chromium electric heating alloy wire, 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 the temperature control system; the head end of the bag body is connected to the iron, and the tail end of the bag body is connected to the fixed frame, and the fixed frame is located near the starting point of the weld.

2. The friction stir welding process according to claim 1, wherein: The diameter of the bag is 40~70mm.

3. The friction stir welding process according to claim 1, 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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