Stern tube repair method

Abstract

The present invention relates to the technical field of stern tube repair, and in particular to a stern tube repair method, comprising processing a damaged area of ​​the stern tube into a groove; preheating the groove; performing TIG welding on the groove when the temperature of the groove is greater than or equal to a first preset value and less than a second preset value; pausing the groove repair welding when the temperature of the groove is greater than or equal to the first preset value and less than the second preset value, and hammering the edge of the groove until the temperature of the groove is greater than or equal to the first preset value and less than the second preset value; and annealing the groove after completing the groove repair welding. The present invention has the beneficial effect of preventing cracks and deformation of the stern tube by controlling the groove temperature during the repair welding process and taking corresponding measures.

Description

Technical Field

[0001] The present invention relates to the technical field of stern tube repair, and in particular to a stern tube repair method. Background Art

[0002] The stern tube is a crucial component of a ship's shafting system, serving as the passageway for the main propulsion shaft. A stern tube bearing sits between the stern tube and the main shaft, and the two are securely connected via an interference fit. However, this interference fit can sometimes lead to unexpected scratches on the inner wall of the stern tube, potentially failing to meet design and operational requirements.

[0003] Repair welding of scratched parts carries high quality risks and is technically challenging. Because stern tubes are typically made of forged steel, improper welding techniques can create weld cracks. Furthermore, the stern tube has already undergone overall annealing and machining during the interference fit stage, so repair welding at this stage can easily cause deformation that fails to meet actual service requirements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing repair welding has the risk of crack defects when repairing the stern tube, and easily causes the stern tube to deform.

[0005] In order to solve the above technical problems, the present invention provides a stern tube repair method, comprising: processing the damaged area of ​​the stern tube into a groove; preheating the groove; when the temperature of the groove is greater than or equal to a first preset value and less than a second preset value, using TIG welding to repair the groove; when the temperature of the groove is higher than the second preset value, suspending the repair welding of the groove and hammering the edge of the groove until the temperature of the groove is greater than or equal to the first preset value and lower than the second preset value; after completing the repair welding of the groove, annealing the groove.

[0006] In the above technical solution, the repair welding of the groove by TIG welding specifically includes: starting an arc in the groove; and stacking welds in the groove until the groove is completely filled with the welds.

[0007] In the above technical solution, the highest point of the weld is higher than the opening of the groove, and the method further includes: machining the weld so that the weld is flush with the opening of the groove.

[0008] In the above technical solution, the annealing treatment of the groove specifically includes: heating the outer surface of the weld until the temperature of the groove reaches a second preset value; and performing a slow cooling treatment on the groove.

[0009] In the above technical solution, the slow cooling treatment of the groove further includes: covering the groove with thermal insulation cotton.

[0010] The above technical solution also includes: cleaning the damaged area.

[0011] In the above technical solution, the preheating of the groove specifically includes: starting an arc in the groove to heat the groove; and stopping heating the groove when the temperature of the groove reaches the first preset value.

[0012] In the above technical solution, the angle of the groove ranges from 40 to 50°.

[0013] In the above technical solution, a temperature measuring probe is placed on the stern tube, with a distance of at least 30 cm between the temperature measuring probe and the edge of the groove, and the temperature measured by the temperature measuring probe is used as the temperature of the groove.

[0014] In the above technical solution, the range of the hammering is an annular area, there is a first interval between the inner side of the annular area and the groove, and there is a second interval between the outer side of the annular area and the groove.

[0015] In the above technical solution, the first preset value ranges from 100 to 150°C.

[0016] In the above technical solution, the second preset value is 200°C.

[0017] Compared with the prior art, the repair method of the stern tube of the embodiment of the present invention has the following advantages: the damaged area of ​​the stern tube is processed into a groove, which is conducive to the filling of the weld during subsequent repair welding to complete the repair work of the damaged area; the groove is preheated, which is conducive to the groove being at a temperature suitable for repair welding; when the temperature of the groove is higher than the first preset value and lower than the second preset value, TIG welding is used to repair the groove, which is conducive to the implementation of the repair welding work and is also conducive to reducing the stress generated by the groove during the repair welding; when the temperature of the groove is higher than the second preset value, the repair welding of the groove is suspended, which can reduce the influence of stress concentration on the groove, and at the same time, hammering the edge of the groove can release the welding stress at the groove; after completing the repair welding, the groove is annealed to further release the residual stress in the groove.

[0018] In summary, the present invention can prevent cracks and deformation of the stern tube by controlling the temperature of the groove during the repair welding process and taking corresponding measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of a stern tube repair method according to an embodiment of the present invention;

[0020] Figure 2 This is a flow chart of a preheating groove according to an embodiment of the present invention;

[0021] Figure 3 2 is a schematic diagram of the groove structure of an embodiment of the present invention;

[0022] In the figure, 1, stern tube; 2, groove; 3, annular area. DETAILED DESCRIPTION

[0023] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0024] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", "inside", "outside", etc. used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] In the description of the present invention, it should be understood that the terms "connected," "connected," "fixed," etc. used in the present invention should be interpreted broadly. For example, the terms may be fixedly connected, detachably connected, or integrated; may be mechanically connected or welded; may be directly connected or indirectly connected through an intermediate medium; may be internal communication between two elements or an interactive relationship between two elements, unless otherwise clearly defined. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] If the first and second are described, they are only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] like Figure 1 and Figure 3 As shown, a stern tube repair method according to a preferred embodiment of the present invention includes:

[0028] 100: Processing the damaged area of ​​the stern tube 1 into a groove 2;

[0029] 200: Preheating groove 2;

[0030] 300: When the temperature of the groove 2 is greater than or equal to the first preset value and less than the second preset value, the groove 2 is repaired by TIG welding; when the temperature of the groove 2 is higher than the second preset value, the repair welding of the groove 2 is suspended, and the edge of the groove 2 is hammered until the temperature of the groove 2 is greater than or equal to the first preset value and lower than the second preset value;

[0031] 400: After completing the repair welding of groove 2, groove 2 is annealed.

[0032] It can be understood that processing the damaged area of ​​the stern tube 1 into a groove 2 is conducive to filling the weld during subsequent repair welding to complete the repair work on the damaged area; preheating the groove 2 is conducive to the groove 2 being at a temperature suitable for repair welding; when the temperature of the groove 2 is higher than the first preset value and lower than the second preset value, TIG welding is used to repair the groove 2, which is conducive to the implementation of the repair welding work and is also conducive to reducing the stress generated by the groove 2 during the repair welding; when the temperature of the groove 2 is higher than the second preset value, suspending the repair welding of the groove 2 can reduce the impact of stress concentration on the groove 2, and at the same time hammering the edge of the groove 2 can release the welding stress at the groove 2; annealing the groove after completing the repair welding can further release the residual stress in the groove.

[0033] By controlling the temperature of the groove 2 during the repair welding process and taking corresponding measures, the present invention can prevent the stern tube 1 from cracking and deforming.

[0034] Preferably, the first preset value ranges from 100 to 150°C.

[0035] Preferably, the second preset value is 200°C.

[0036] Preferably, when repair welding is performed on the groove 2 by TIG welding, the welding material is TIG-50 welding wire (Φ2.0 / 2.4mm), and argon with a purity of 99.99% is used as the shielding gas. The argon flow rate is 15-20L / min, the welding current is 130-180A, and the thickness of the single-layer weld produced during the repair welding is ≤3mm, and the width of the single-pass weld is ≤6mm.

[0037] Furthermore, the use of a TIG welding arc for preheating before welding reduces the heating range of the stern tube 1, reduces energy consumption, shortens heating and cooling times, and maintains a low temperature inside the stern tube 1 during the repair welding process, improving working conditions. Furthermore, the welding arc has a small diameter, concentrating the heat. TIG welding heats the inner wall of the stern tube 1 within a narrow range, making it less susceptible to welding defects. The repair welding process eliminates welding slag and metal spatter, reducing the difficulty of post-weld surface cleaning. The heat exposure of the stern tube 1 during the repair welding process is limited, minimizing the risk of excessive deformation (changes in inner diameter and ovality).

[0038] In one embodiment, TIG welding is used to repair the groove 2, specifically including:

[0039] Start the arc in groove 2;

[0040] Stack welds on Groove 2 until Groove 2 is completely filled with welds.

[0041] It is understandable that by stacking the welds in the groove 2 , the groove 2 can be filled, thereby completing the repair work on the damaged area.

[0042] Furthermore, the highest point of the weld is higher than the opening of the groove 2, and further comprises:

[0043] The weld is machined so that it is flush with the opening of groove 2.

[0044] It can be understood that the highest point of the weld is higher than the opening of the groove 2 , which is beneficial to the subsequent mechanical processing of the groove 2 and restores the stern tube 1 to the state before the scratch.

[0045] Furthermore, the groove 2 is subjected to annealing treatment, specifically including:

[0046] heating the outer surface of the weld until the temperature of the groove 2 reaches a second preset value;

[0047] The groove 2 is subjected to slow cooling treatment.

[0048] It is understandable that, through the above method, the present invention can reduce the residual stress in the groove 2, stabilize the size of the stern tube 1, and reduce the tendency of deformation and cracking.

[0049] In one embodiment, the slow cooling treatment of the groove 2 further includes:

[0050] Use thermal insulation cotton to cover the slope 2.

[0051] It can be understood that by covering the groove 2 with thermal insulation cotton, the present invention can alleviate the cooling rate of the groove 2, thereby improving the annealing effect.

[0052] Furthermore, it also includes:

[0053] Clean the damaged area.

[0054] It is understandable that the cleaning process can effectively remove the oil stains in the damaged area, thereby preventing the oil stains from entering the groove 2 during the repair process and causing adverse effects on the repair welding process.

[0055] like Figure 2 As shown, further, preheating the groove 2 specifically includes:

[0056] 201: Start arc in groove 2 and heat groove 2;

[0057] 202: When the temperature of the groove 2 reaches a first preset value, stop heating the groove 2.

[0058] It is understandable that, by starting an arc to heat the groove 2 , the present invention can rapidly increase the temperature of the groove 2 , which is beneficial to subsequent repair welding.

[0059] Preferably, the angle of the groove 2 is in the range of 40 to 50 degrees. This arrangement can facilitate the filling of the groove 2 by the weld during repair welding.

[0060] In one embodiment, a temperature probe is placed on the stern tube 1 , with a distance of at least 30 cm between the temperature probe and the edge of the groove 2 , and the temperature measured by the temperature probe is used as the temperature of the groove 2 .

[0061] It can be understood that the stern tube 1 forms a gap of at least 30 cm with the edge of the groove 2, and the measured temperature has a certain accuracy. At the same time, due to the certain gap with the groove 2, it can avoid the situation where the temperature measuring probe is damaged by accidents during repair welding.

[0062] like Figure 3 As shown, further, the hammering range is the annular area 3 , there is a first interval between the inner side of the annular area 3 and the groove 2 , and there is a second interval between the outer side of the annular area 3 and the groove 2 .

[0063] It can be understood that by using the annular area 3 as the range for hammering, the welding stress at the groove 2 can be released.

[0064] The implementation process of the present invention is as follows: use alcohol to thoroughly clean and treat the damaged area and the surrounding area of ​​oil stains; use a grinding wheel to clean the damaged area and grind out the shape of the groove 2; place the temperature probe at a position 30 mm away from the edge of the groove 2 and press it firmly; start an arc in the groove 2 to heat the groove 2, and stop heating when the temperature of the temperature probe reaches 150°C; during repair welding, if the temperature of the temperature probe reaches 200°C, suspend the welding construction, and use a round-headed wooden hammer to hammer until the temperature of the temperature probe drops to 150℃; when groove 2 is fully welded, the repair welding is completed; hammer groove 2, and when the temperature of the temperature probe reaches 150℃, start arc heating on the outer surface of the weld, and stop heating when the temperature of the temperature probe reaches 200℃ to complete annealing; use insulation cotton to insulate groove 2 and its surroundings and slow cool; after 24 hours of insulation, use color flaw detection method to inspect the repair welding area, and if there are no crack defects, prepare to machine the damaged area; machine the damaged area of ​​stern tube 1 to restore stern tube 1 to the state before scratching.

[0065] In summary, an embodiment of the present invention provides a stern tube repair method, which processes the damaged area of ​​the stern tube 1 into a groove 2, which is conducive to filling the weld during subsequent repair welding to complete the repair work on the damaged area; preheating the groove 2 is conducive to the groove 2 being at a temperature suitable for repair welding; when the temperature of the groove 2 is higher than the first preset value and lower than the second preset value, TIG welding is used to repair the groove 2, which is conducive to the implementation of the repair welding work and is also conducive to reducing the stress generated by the groove 2 during the repair welding; when the temperature of the groove 2 is higher than the second preset value, the repair welding of the groove 2 is suspended, which can reduce the influence of stress concentration on the groove 2, and at the same time, hammering the edge of the groove 2 can release the welding stress at the groove 2; annealing the groove after completing the repair welding can further release the residual stress in the groove.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for repairing a stern tube, characterized in that: include: Treat the damaged area of ​​the stern tube into a bevel; preheating the groove; When the temperature of the groove is greater than or equal to a first preset value and less than a second preset value, the groove is repaired by TIG welding; When the temperature of the groove is higher than the second preset value, suspending the repair welding of the groove and hammering the edge of the groove until the temperature of the groove is greater than or equal to the first preset value and lower than the second preset value; After completing the repair welding of the groove, the groove is annealed; The hammering range is an annular area, a first gap exists between the inner side of the annular area and the groove, and a second gap exists between the outer side of the annular area and the groove.

2. The stern tube repair method according to claim 1, characterized in that: The repair welding of the groove by TIG welding specifically includes: Starting an arc in the groove; Welds are stacked on the groove until the groove is completely filled with the welds.

3. The stern tube repair method according to claim 2, characterized in that: The highest point of the weld is higher than the opening of the groove, and further comprises: The weld is machined so that the weld is flush with the opening of the groove.

4. The stern tube repair method according to claim 2, characterized in that: The annealing treatment of the groove specifically includes: heating the outer surface of the weld until the temperature of the groove reaches a second preset value; The groove is subjected to a slow cooling treatment.

5. The stern tube repair method according to claim 4, characterized in that: The slow cooling treatment of the groove further comprises: The groove is covered with thermal insulation cotton.

6. The stern tube repair method according to claim 1, characterized in that: Also includes: The damaged area is cleaned.

7. The stern tube repair method according to claim 1, characterized in that: The preheating of the groove specifically includes: Starting an arc in the groove to heat the groove; When the temperature of the groove reaches the first preset value, heating of the groove is stopped.

8. The stern tube repair method according to claim 1, characterized in that: The angle of the groove ranges from 40 to 50 degrees.

9. The stern tube repair method according to claim 1, characterized in that: A temperature measuring probe is placed on the stern tube, with a distance of at least 30 cm between the temperature measuring probe and the edge of the groove, and the temperature measured by the temperature measuring probe is used as the temperature of the groove.

10. The stern tube repair method according to any one of claims 1 to 9, characterized in that: The first preset value ranges from 100 to 150°C.

11. The stern tube repair method according to any one of claims 1 to 9, characterized in that: The second preset value is 200°C.

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