Weld beading removing method

Abstract

The invention provides a weld beading removing method, and belongs to the technical field of welding. The weld beading removing method comprises the steps that according to the position of a weld beading on the back face of a weld joint, a target area located on the front face of the weld joint is thinned, and the projection of the weld beading on the front face of the weld joint is located in the target area; and welding is conducted on the thinned target area, so that the weld beading is melted and is flush with the back face of the weld joint. According to the invention, the service life of the welding part is not influenced while the weld beading can be removed.

Description

Technical Field

[0001] The present disclosure belongs to the field of welding technology, and in particular relates to a method for removing weld nodules. Background Art

[0002] Weld nodules are a typical welding defect, commonly found inside pipe butt welds and particularly prone to formation during the root pass welding process. These nodules protrude significantly from the back of the weld, significantly affecting its appearance and causing stress concentration at the raised areas. Furthermore, under alternating loads, the raised areas can easily cause weld cracking and nodules to fall off, potentially damaging or rendering the equipment useless. Therefore, removal of nodules is essential.

[0003] In the prior art, weld nodules are often removed using grinding tools or methods. A grinding device is placed on the inside of a part (such as a pipe) to smooth or remove the nodules. However, due to the thinness and length of some parts, the grinding device has difficulty reaching the interior of the part and thus cannot reach the nodules. In such cases, the nodules can be removed by first grinding through the front of the weld where the nodules are located, and then re-welding.

[0004] However, grinding through the front of the weld and then re-welding to remove the weld bump not only results in secondary defects but also deteriorates the weldability of the part due to multiple re-weldings. This leads to a greater risk of part scrapping and shortens the service life of the part. Summary of the Invention

[0005] The present disclosure provides a method for removing weld nodules, which can remove weld nodules without affecting the service life of parts. The technical solution is as follows:

[0006] An embodiment of the present disclosure provides a method for removing weld nodules, comprising: thinning a target area located on the front side of the weld according to the position of the weld nodules on the back side of the weld, wherein the projection of the weld nodules on the front side of the weld is located in the target area; and welding is performed at the thinned target area so that the weld nodules melt and become flush with the back side of the weld.

[0007] In another embodiment of the present disclosure, the width of the target area is equal to the width of the weld, the length of the target area is greater than the length of the weld nodule, and the minimum distance between the end of the target area and the end of the weld nodule is no more than 4 mm.

[0008] In yet another implementation of the present disclosure, the shortest distance from the target area after thinning to the back side of the weld is 1.5-2 mm.

[0009] In another embodiment of the present disclosure, thinning a target area on the front side of the weld according to the position of the weld bump on the back side of the weld includes:

[0010] The method comprises the following steps: determining a position of the weld bead on the back side of the weld; marking the target area on the front side of the weld; and grinding the target area.

[0011] In another embodiment of the present disclosure, welding is performed at the thinned target area so that the weld bead melts and becomes flush with the inner side of the weld, comprising:

[0012] Manual tungsten inert gas arc welding is used to perform welding at the target area.

[0013] In another embodiment of the present disclosure, the welding at the target area using manual tungsten inert gas arc welding includes:

[0014] Start an arc at a distance of 0.8-1.2 cm from the edge of the target area; move the welding gun, and when the arc moves to the edge of the target area, slow down the movement of the welding gun, and stop moving the welding gun when the molten pool in the target area becomes wider and the molten pool is half-moon shaped; move the welding gun in the opposite direction until it reaches the arc starting point and extinguishes the arc.

[0015] In yet another implementation of the present disclosure, when the arc moves to the edge of the target area, the moving speed of the welding gun is slowed down.

[0016] In yet another implementation of the present disclosure, when the molten pool within the target area becomes wider and takes a crescent shape, the welding gun is stopped from moving, so that the welding gun pauses for 0.5-1 second.

[0017] In another embodiment of the present disclosure, before welding is performed at the target area after thinning, the weld flash removal method further includes:

[0018] Through trial welding, target parameters for welding at the target area after thinning are determined.

[0019] In another embodiment of the present disclosure, determining target parameters for welding at the target area after thinning by trial welding includes:

[0020] Two test plates are provided, wherein the material and thickness of one of the test plates are the same as the material and thickness of one of the two parts connected by the weld, and the material and thickness of the other test plate are the same as the material and thickness of the other of the two parts connected by the weld; multiple test weldings are performed on the two test plates to determine the target parameters.

[0021] The technical solutions provided by the embodiments of the present disclosure have the following beneficial effects:

[0022] When the weld nodule removal method provided by the embodiment of the present disclosure is used to remove the weld nodule on the back side of the weld between two adjacent pipes, since the method first thins the target area on the front side of the weld according to the position of the weld nodule on the back side of the weld, and then welds on the thinned target area to melt the weld nodule, welding can be performed on the original weld to melt the weld nodule, thereby avoiding multiple repair weldings that may cause deterioration of pipeline performance and render the pipeline scrapped.

[0023] That is to say, the above method can be used to weld on the front side of the weld where the weld nodule is located, so that the weld nodule is melted again, thereby achieving the purpose of eliminating the weld nodule. This method is simple and quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 A flow chart of a method for removing weld nodules is provided for an embodiment of the present disclosure;

[0026] Figure 2 A flow chart of another method for removing weld nodules is provided for an embodiment of the present disclosure;

[0027] Figure 3 This is a structural diagram of two adjacent oil pipes connected together after welding;

[0028] Figure 4 for Figure 3 Cross-sectional view of

[0029] Figure 5 A schematic diagram showing the position of the weld nodule on the back of the weld;

[0030] Figure 6 A schematic diagram showing the position of the weld nodule on the front side of the weld;

[0031] Figure 7 This is a schematic diagram of marking the target area in the weld;

[0032] Figure 8 for Figure 7 A partial enlarged view of the

[0033] Figure 9 Schematic diagram of the welding process.

[0034] The symbols in the figure mean the following:

[0035] 100. Oil pipeline;

[0036] 101. Welding seam;

[0037] 102. Weld nodule. DETAILED DESCRIPTION

[0038] Unless otherwise defined, the technical or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present disclosure belongs. The words “first”, “second”, “third” and similar terms used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as “one” or “a” do not indicate a quantity limitation, but rather indicate the presence of at least one. Words such as “include” or “comprising” and similar terms mean that the elements or objects appearing before “include” or “comprising” cover the elements or objects listed after “include” or “comprising” and their equivalents, and do not exclude other elements or objects.

[0039] An embodiment of the present disclosure provides a method for removing weld nodules, which is used to remove weld nodules present in two adjacent and coaxially welded pipes.

[0040] Figure 1 A method for removing weld nodules is provided in the embodiment of the present disclosure. Figure 1 As shown, the weld flash removal methods include:

[0041] S101: thinning a target area on the front side of the weld according to the position of the weld bump on the back side of the weld.

[0042] The projection of the weld flash onto the front side of the weld seam is located in the target area.

[0043] The back side of the weld and the front side of the weld are opposite sides of the weld.

[0044] S102: Welding is performed at the target area after thinning, so that the weld bead melts and becomes flush with the back of the weld.

[0045] When the weld nodule removal method provided in the embodiment of the present disclosure is used to remove the weld nodule on the back side of the weld between two adjacent pipes, the method first thins the target area on the front side of the weld according to the position of the weld nodule on the back side of the weld, and then welds on the thinned target area to melt the weld nodule. In this way, welding can be performed on the original weld to melt the weld nodule, thereby avoiding multiple repair weldings that may cause deterioration of pipeline performance and render the pipeline scrapped.

[0046] That is to say, the above method can be used to weld on the front side of the weld where the weld nodule is located, so that the weld nodule is melted again, thereby achieving the purpose of eliminating the weld nodule. This method is simple and quick.

[0047] On the other hand, the embodiment of the present disclosure also provides another method for removing weld nodules, such as Figure 2 As shown, the weld flash removal methods include:

[0048] S201: Determine the position of the weld bead on the back side of the weld.

[0049] In welding, the front and back of the weld are distinguished based on the viewing direction during the welding operation or the position of the weld formation.

[0050] The front side of the weld refers to the side that the operator directly welds during welding, or the surface that can be directly observed by the naked eye after the weld is formed.

[0051] For example, when butt welding steel plates, the side on which the welding gun / torch is applied is the front face. When girth welding pipes, the outer surface that the welder directly welds is the front face.

[0052] The back of a weld is the side opposite the front. The back of a weld usually refers to the root of the weld or the side not directly welded.

[0053] For example, when butt-welding steel plates, the back side corresponds to the bottom of the plate (the side not directly welded). When welding pipes, the inner wall is the back side (which requires internal welding or shielding gas to prevent oxidation).

[0054] Since the weld nodule exists on the back of the weld seam of the pipeline, when determining the location of the weld nodule, you can observe it with a flashlight from the open end of the pipeline that is closer, or use endoscopic inspection or X-ray filming to confirm the specific location of the weld nodule.

[0055] In the disclosed embodiment, the position of the weld nodule in the weld is determined by direct flashlight illumination and visual observation.

[0056] S202: Mark a target area on the front side of the weld.

[0057] Once the specific position of the weld nodule on the back of the weld is confirmed, the corresponding position of the weld nodule on the front of the weld can be marked with a marker on the front of the weld.

[0058] Then, the target area is marked according to the corresponding position.

[0059] The target area is the area that contains the location of the weld flash.

[0060] For example, the target area can be determined by taking the corresponding position of the weld nodule as the center and radiating outward to form an area.

[0061] In this embodiment, the size of the target area can be determined according to the corresponding position of the weld bump on the front side of the weld.

[0062] For example, the width of the target area (that is, the length along the axial direction of the pipe) is the same as the width of the weld, and the length of the target area (along the length direction of the weld, that is, along the circumference of the pipe) at both ends is greater than the length of the weld bump.

[0063] In this embodiment, the length of the target area is greater than the length of the weld bump, and the minimum distance between the end of the target area and the end of the weld bump is no greater than 4 mm.

[0064] S203: Polishing the target area.

[0065] When thinning the target area, it can be directly ground manually or with a pneumatic grinder to make the thickness of the target area smaller than the thickness of the weld (ie, the length along the radial direction of the pipe).

[0066] In the disclosed embodiment, the target area is ground by a pneumatic grinder so that the thickness of the target area is smaller than the thickness of the weld.

[0067] It should be noted that when thinning the target area, the target area should not be worn through.

[0068] In this embodiment, the shortest distance from the target area after thinning to the back side of the weld is 1.5-2 mm in thickness.

[0069] S204: Determine target parameters for welding at the target area after thinning through trial welding.

[0070] Before welding in the target area, the target welding parameters need to be determined.

[0071] The target parameters include current parameters, voltage parameters, speed parameters, etc. during welding.

[0072] Since the purpose of welding is to melt the weld nodules and re-form the weld, in order to melt the weld nodules completely, it is necessary to first determine the target parameters during welding through experiments.

[0073] In the embodiment of the present disclosure, when conducting trial welding, it is achieved through a simulated test plate.

[0074] In order to further improve the accuracy of welding parameters, you can follow the following steps during trial welding:

[0075] (1) Provide two test plates, one of which has the same material and thickness as the material and thickness of one of the two parts connected by the weld, and the other has the same material and thickness as the material and thickness of the other of the two parts connected by the weld.

[0076] (2) Perform multiple test welds on two test plates to determine the target parameters.

[0077] After multiple test welds, the target parameters can be determined by comparing the welds obtained after each test. The parameters corresponding to the best weld quality among all welds are the target parameters. The quality of a weld can be determined by macroscopic observation of the weld surface and microscopic observation of the weld's internal structure. For example, a weld that is uniform, has no undercut, has moderate reinforcement, has full penetration at the weld root, and has no pores or cracks in its microstructure, while also exhibiting good mechanical properties (such as tensile strength and passing bend tests), is considered a good weld.

[0078] In this embodiment, in order to simplify the trial welding process, the object of the trial welding is a plate structure whose material is the same as that of the pipeline.

[0079] In other examples, the structure of the object to be welded may be other structures, such as a ring-shaped structure.

[0080] S205: Welding is performed at the target area after thinning, so that the weld bead melts and becomes flush with the inner side of the weld.

[0081] Optionally, step S205 may be implemented in the following manner:

[0082] Manual tungsten inert gas arc welding is used to weld the target area.

[0083] Manual Gas Tungsten Arc Welding (GTAW or TIG welding) is a high-precision welding method that uses a non-consumable tungsten electrode as an electrode and an inert gas (such as argon) to protect the molten pool.

[0084] In manual tungsten electrode argon arc welding, an arc is ignited between the tungsten electrode and the workpiece, and then the arc melts the base material and welding wire.

[0085] Argon / helium is ejected from the welding gun nozzle to isolate the air (O2, N2 content <0.01%) in order to protect the molten pool, heat-affected zone and high-temperature tungsten electrode.

[0086] In this embodiment, during welding, the following steps can be followed:

[0087] (1) Start the arc at a distance of 0.8-1.2 cm from the edge of the target area.

[0088] (2) Move the welding gun, and when the arc moves to the edge of the target area, slow down the movement of the welding gun, and stop moving the welding gun when the molten pool located in the target area becomes wider and the molten pool becomes a half-moon shape.

[0089] (3) Move the welding gun in the opposite direction until it reaches the arc starting point and extinguishes the arc.

[0090] The molten pool, as described above, is the liquid metal region formed by the melting of the base metal and filler metal under the action of the heat source during welding. Its dynamic behavior directly determines the weld formation and quality. Therefore, by observing the morphology of the molten pool and flexibly controlling the movement speed of the welding gun, the weld nub can be quickly melted and smoothed without forming a bulge.

[0091] Moreover, during welding, by controlling the welding gun to pause, the weld nodule can be fully melted into the molten pool, and the surface tension of the molten pool can be used to make the melted weld nodule spread and become smooth.

[0092] It should be noted that the pause time should not be too long or too short. If it is too long, it is easy to burn through, and if it is too short, the weld nodule cannot be fully melted into the molten pool.

[0093] That is, in this embodiment, manual tungsten inert gas arc welding is used to weld the thinned target area.

[0094] Before actual welding, adjust the current parameters required for appropriate welding. The specific parameter values are determined by trial welding on a simulated test plate of the same material and thickness.

[0095] When welding, start the arc about 1 cm from the polished edge. Be careful not to add welding wire when the arc is started, and slowly move the welding torch forward. When the arc reaches the edge of the target area, slow the welding torch movement by about 50%, and add welding wire appropriately to prevent the molten pool temperature from overheating.

[0096] When the width of the molten pool is observed to be significantly wider and the front end of the molten pool is a smooth half-moon shape during the movement, pause for 0.5-1s and then immediately move the welding gun in the opposite direction.

[0097] The pause is to allow the weld nodule to fully melt into the molten pool and use the surface tension of the molten pool to spread and become smooth.

[0098] Finally, continue to move the welding gun in the opposite direction until it reaches the arc starting point and extinguishes the arc. During the arc extinguishing process, it is necessary to add welding wire appropriately to avoid pits at the arc extinguishing point.

[0099] In other examples, other welding methods may also be used for welding, such as resistance welding, ultrasonic welding, etc. As long as the weld nub can be melted and re-laid flat, the present disclosure does not impose any restrictions on the welding method used.

[0100] By using the above weld nodule removal method to remove weld nodules from oil pipes, not only can the problem that conventional grinding tools and methods are difficult to reach the back of the weld seam be solved, but also the problem of secondary defects caused by conventional means of grinding through the weld nodules and then re-welding to fill them can be avoided. In addition, the problem of deterioration of the welding performance of the base material due to multiple re-welding can be avoided, thereby solving the problem of a large risk of scrapping the pipeline. The obtained weld seam has a beautiful shape and good quality, and passes the flaw detection test in one time.

[0101] The following is an example of the weld of a certain oil pipe to explain the above weld nodule removal method in detail:

[0102] Figure 3 This is a structural diagram of two adjacent oil pipes connected together after welding. Figure 3 When two adjacent oil pipes 100 need to be butted together to form a new pipeline, welding is required at the butt joint. After welding, a weld 101 is located at the butt joint of the two oil pipes.

[0103] Figure 4 for Figure 3 Cross-sectional view, combined with Figure 4 The back side of the weld formed after the two oil pipes are welded has at least one protrusion along the circumference of the pipe, and the protrusion is the weld nodule 102 formed after the welding.

[0104] In the case of using the weld nodule removal method provided by the above embodiment of the present disclosure Figure 4 When removing weld nodules from oil pipes, you can follow the steps below:

[0105] First, determine the location of the weld bead on the back side of the weld.

[0106] Figure 5 Schematic diagram of the position of the weld nodule on the back of the weld, combined with Figure 5 , use a flashlight to confirm the location A of the weld nodule from the right end of the oil pipe (the length of the oil pipe at the right end is shorter).

[0107] Then, mark the corresponding position on the front side of the weld that corresponds to the position of the weld flash on the back side of the weld.

[0108] Figure 6 Schematic diagram of the position of the weld nodule on the front of the weld, combined with Figure 6 , use a marking pen to mark the corresponding position B of the weld bead on the front of the weld.

[0109] The projections of position A and position B on the weld along the radial direction of the oil pipe coincide with each other.

[0110] Next, the target area is marked by position B.

[0111] The target area can be determined according to the method discussed above.

[0112] For example, the width of the target area (that is, the length along the axial direction of the pipe) is the same as the width of the weld, the length of the target area (along the length direction of the weld, that is, along the circumference of the pipe) is greater than the length of the weld nodule, and the minimum distance between the end of the target area and the end of the weld nodule is not greater than 4 mm.

[0113] Figure 7 This is a schematic diagram of the target area in the weld, combined with Figure 7 , the target area is determined based on the location of the weld nodule.

[0114] For example, the weld flash can be located in the middle of the target area.

[0115] Next, thinning is performed on the target area.

[0116] For example, a pneumatic grinder may be used to grind the target area, so that the thickness of the target area is reduced to form a grinded area.

[0117] Figure 8 for Figure 7 Partial enlargement of the picture, combined with Figure 8 , the target area after thinning (also known as the polishing area) is Figure 8 Remove the dotted box area.

[0118] The distance from the target area after thinning to the root of the weld (i.e. Figure 8 The h) in the figure is approximately between 1.5 and 2 mm.

[0119] The width of the target area is equal to the width of the weld. The length of the target area is the distance beyond the weld bead at both ends (i.e. Figure 8 d1 and d2) are not greater than 4mm.

[0120] Then, manual tungsten inert gas arc welding is used to weld in the target area after thinning to melt the weld nodules.

[0121] Before welding in the target area after thinning using manual tungsten inert gas arc welding, first connect the DC positive connection and perform a test weld on a 1.5-2mm test plate.

[0122] After trial welding, the following target parameters were determined:

[0123] The current is 80-90A; the voltage is self-matching; the welding speed is 10-12cm / min; and the gas flow rate is 15-20L / min.

[0124] Figure 9 The schematic diagram of the welding process is as follows. Figure 9As shown, then, when welding, control the distance from the welding gun to the edge of the target area after thinning (that is, Figure 9 The arc starts at a position where L) is about 10 mm.

[0125] After the arc is started, follow Figure 9 Continue moving the welding gun in the direction indicated by the arrow.

[0126] When the arc moves to the edge of the thinned target area, the moving speed of the welding gun is controlled to be reduced to half of the original speed while observing the melting condition of the molten pool.

[0127] When the welding gun moves, pay attention to feeding the welding wire in a point-like manner, and point the welding wire into the molten pool once or twice. This can reduce the temperature of the molten pool and prevent the temperature of the molten pool from being too high and burning through the target area or weld, causing the weld to penetrate inside and outside.

[0128] Move the welding gun. If the length (length along the circumference of the pipe) and width (length along the axial direction of the pipe) of the molten pool (the liquid metal area formed after the base material and welding wire are melted during the welding process) are found to be significantly increased during the movement of the welding gun, and the front end of the molten pool is a smooth half-moon shape with back-side penetration characteristics, control the welding gun to stop for 0.5-1s to allow the weld area where the weld nodule is located to be fully melted.

[0129] In this way, the surface tension of the molten pool can be used to melt the weld nodule and automatically spread it flat.

[0130] After pausing, immediately control the welding gun to move in the opposite direction.

[0131] The pause is to allow the weld nodule to fully melt into the molten pool and use the surface tension of the molten pool to spread and become smooth.

[0132] It should be noted that the welding gun pause time should not be too long or too short. If the welding gun pauses for too long, it is easy to burn through the weld. If the welding gun pauses for too short a time, the weld nodule cannot be fully melted into the molten pool.

[0133] After pausing, continue to move the welding gun in the opposite direction until it reaches the arc starting point and extinguishes the arc. During the arc extinguishing process, it is necessary to add welding wire appropriately to avoid pits at the arc extinguishing point.

[0134] By using the above weld nodule removal method to remove weld nodules from oil pipes, not only can the problem that conventional grinding tools and methods are difficult to reach the inside of the weld seam be solved, but also the problem of secondary defects caused by conventional means of grinding through the weld nodules and re-welding to fill them can be avoided. It can also avoid the problem of deterioration of the welding performance of the base material after multiple repair welding, thereby solving the problem of a large risk of scrapping the pipeline. The obtained weld has a beautiful shape and good quality, and passes the flaw detection test in one go.

[0135] It should be noted that the above weld nodule removal method can be applied to any weld, for example, the removal of weld nodules in welds between plates, and is not limited to the removal of weld nodules in welds formed between pipes listed above.

[0136] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A method for removing weld nodules, characterized in that: The welding nodule removal method comprises: thinning a target area on the front side of the weld according to the position of the weld bump on the back side of the weld, wherein the projection of the weld bump on the front side of the weld is located in the target area; Welding is performed at the thinned target area so that the weld bead melts and becomes flush with the back surface of the weld.

2. The method for removing weld flash according to claim 1, characterized in that: The width of the target area is equal to that of the weld, the length of the target area is greater than the length of the weld bump, and the minimum distance between the end of the target area and the end of the weld bump is no more than 4 mm.

3. The method for removing weld flash according to claim 2, characterized in that: The shortest distance from the target area after thinning to the back side of the weld is 1.5-2 mm.

4. The method for removing weld flash according to claim 1, wherein: The method of thinning a target area on the front side of the weld according to the position of the weld bump on the back side of the weld includes: Determining the position of the weld bump on the back side of the weld; marking the target area in the front face of the weld; The target area is polished.

5. The method for removing weld flash according to claim 1, characterized in that: The welding is performed at the target area after thinning so that the weld bead melts and becomes flush with the inner side of the weld, comprising: Manual tungsten inert gas arc welding is used to perform welding at the target area.

6. The weld flash removal method according to claim 5, characterized in that: The method of welding at the target area by manual tungsten inert gas arc welding comprises: Start the arc at a distance of 0.8-1.2 cm between the welding gun and the edge of the target area; Moving the welding gun, and when the arc moves to the edge of the target area, slowing down the movement speed of the welding gun, and stopping the movement of the welding gun when the molten pool in the target area becomes wider and the molten pool becomes a half-moon shape; The welding gun is moved in the opposite direction until the arc is reached and the arc is extinguished.

7. The method for removing weld flash according to claim 6, characterized in that: When the arc moves to the edge of the target area, the moving speed of the welding gun is slowed down.

8. The method for removing weld flash according to claim 6, characterized in that: When the molten pool in the target area becomes wider and takes on a crescent shape, the welding gun is stopped from moving, so that the welding gun pauses for 0.5-1 second.

9. The method for removing weld flash according to claim 1, wherein: Before welding at the target area after thinning, the weld nodule removal method further comprises: Through trial welding, target parameters for welding at the target area after thinning are determined.

10. The weld flash removal method according to claim 9, characterized in that: The method of determining target parameters for welding at the target area after thinning by trial welding includes: Providing two test plates, wherein the material and thickness of one of the test plates are the same as the material and thickness of one of the two parts connected by the weld, and the material and thickness of the other test plate are the same as the material and thickness of the other of the two parts connected by the weld; Multiple test weldings are performed on the two test plates to determine the target parameters.

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