Welding method
By using 3D-printed sand cores and aluminum foil welding combined with flexible grinding tools in narrow airways, the problems of poor welding visibility and difficult cleaning in narrow airways have been solved, achieving high-quality and efficient welding and cleaning results.
Patent Information
- Application Number
- CN202511569904.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-02-27
AI Technical Summary
Welding in narrow airways presents challenges such as poor visibility, insufficient accessibility, and difficulties in post-weld cleaning and finishing, leading to welding defects and inconsistent quality.
The internal flow channel core is 3D printed and wrapped with aluminum foil on the outside. Welding is carried out through the process window, and the weld is cleaned with a flexible grinding tool, combined with endoscopic inspection.
It improves welding quality, reduces weld intrusion into the internal flow channel, lowers the rework rate, and achieves efficient cleaning of narrow airway cavities and surface finish.
Smart Images
Figure CN121571883A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of welding technology, and in particular to a welding method for narrow air passages. Background Technology
[0002] As the core component of centrifugal fluid machinery, the volute housing contains a complex spiral air passage system that collects and guides the medium. To meet structural strength, aerodynamic performance, or specific process requirements, some volute housings incorporate internal reinforcing ribs, guide plates, or baffles. These components are typically welded to the volute body, creating a narrow, enclosed, and difficult-to-access welded area within the air passage system. Furthermore, some cast steel volute housings, due to their limited internal space, not only pose a risk of sand adhesion but also require penetrant testing (PT), demanding extremely high quality and dimensional accuracy. Therefore, additional casting holes are often required for sand removal and internal surface grinding. After the entire flow channel has passed grinding and testing, the openings are then sealed and welded shut. Currently, the main technical challenges in welding operations within the aforementioned narrow gas channels are as follows: First, poor visibility during operation. The welding point is located deep within the gas channel, making it difficult for welders to directly observe the molten pool morphology and the alignment of the welding torch, which can easily lead to defects such as weld misalignment, incomplete fusion, and undercut. Second, insufficient accessibility during welding. Due to space limitations, traditional welding torches cannot be inserted or adjusted to the ideal welding posture, severely affecting the quality of the weld formation. Third, post-weld cleaning and finishing are difficult. Conventional grinding tools cannot enter the narrow area to handle weld slag, spatter, and weld excess. Existing methods mostly rely on flexible tools, which are inefficient, labor-intensive, and difficult to guarantee the smoothness requirements of the inner wall of the flow channel. Summary of the Invention
[0003] In view of the problems of poor visibility, insufficient accessibility, and difficulty in post-weld cleaning and repair when welding narrow airways, it is necessary to propose a welding method that enables high-quality and high-efficiency welding of narrow airways.
[0004] A welding method, comprising,
[0005] Prepare independent internal cavity flow channel sand cores;
[0006] Aluminum foil is wrapped around the outside of the inner cavity flow channel sand core;
[0007] Place the aluminum foil-coated inner cavity flow channel core into the welding position of the narrow airway, and make the inner cavity flow channel core fit tightly against the inner cavity of the narrow airway.
[0008] Place the solder into the process window;
[0009] The welding process window restores the narrow airway to its original state. After welding, the sand core of the inner cavity flow channel is broken and the narrow airway is cleaned out through the volute nozzle.
[0010] This invention optimizes the welding process by using 3D-printed internal flow channel sand cores wrapped with aluminum foil on the outside. By placing the independent internal flow channel sand cores into the welding position of the narrow air passage, making them closely adhere to the air passage, the amount of welding slag and grinding is reduced, which means the area of the weld is reduced, thus achieving high-precision and high-efficiency welding.
[0011] Furthermore, the welding method also includes pre-welding preparation.
[0012] Bevel preparation: Prepare the welding bevel at the process window position, and clean the bevel and its surrounding area, such as removing oil, rust, etc.
[0013] Furthermore, the welding method also includes post-weld cleaning.
[0014] A flexible grinding tool is inserted into the narrow air passage, and the grinding head is driven to rotate at high speed to grind the weld area.
[0015] Workers move grinding tools to grind and clean the weld excess, weld slag, and spatter.
[0016] Furthermore, the flexible grinding tool includes a power source, a flexible drive shaft, a grinding head, and a reinforcing frame. The flexible drive shaft is fitted inside the reinforcing frame, giving the flexible grinding tool a certain strength to ensure the grinding force on the weld. The power source and the grinding head are respectively located at both ends of the flexible drive shaft. The grinding head is used to grind the weld, and the power source is used to provide power to the flexible grinding tool, that is, to the grinding head.
[0017] Furthermore, the flexible drive shaft can be bent to any curvature to accommodate insertion into narrow airways.
[0018] Furthermore, the grinding head is a replaceable miniature grinding head, which can be conveniently adapted to grinding welds in narrow air passages.
[0019] Furthermore, the reinforcing frame includes reinforcing ribs and collars, with the collars fixedly connected to the reinforcing ribs.
[0020] Furthermore, the welding method also includes weld inspection.
[0021] Use an endoscope to visually inspect the welds inside the narrow airway to ensure that the weld surface is smooth and flat.
[0022] The beneficial effects of the technical solution of this invention are as follows: By bonding and welding the inner cavity flow channel sand core, the welding quality is improved, the intrusion of the weld seam into the inner cavity flow channel and the damage of the weld slag to the flow channel are reduced, and the rework rate is reduced; the flexible grinding tool makes it easier to penetrate the airway / flow channel, and realizes the cleaning of the inner cavity of narrow airway. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the volute casing of a centrifugal compressor;
[0024] Figure 2 yes Figure 1 Schematic diagram along the direction of the volute opening;
[0025] Figure 3 yes Figure 2 A cross-sectional view of the volute casing of a centrifugal compressor along the CC direction, showing the welding position of the process window;
[0026] Figure 4 This is a schematic diagram of the flexible polishing tool structure;
[0027] Among them, 1-volute; 2-process window; 3-inner cavity flow channel sand core; 5-volute tube opening; 6-solder; 7-flexible drive shaft; 8-grinding head; 10-reinforcing rib; 11-ring. Detailed Implementation
[0028] To more clearly illustrate the technical solution of the present invention, the technical solution of the invention will be described in detail with reference to the accompanying drawings. Obviously, the following description is some typical embodiments of the present invention. For those skilled in the art, other solutions can be obtained based on these embodiments without creative effort.
[0029] Taking the welding of the process window 2 on the centrifugal compressor volute as an example, the implementation of the technical solution of this patent application is described. The rotating inner cavity of the volute 1 is the narrow air passage.
[0030] One embodiment of the welding method for the centrifugal compressor volute 1 includes:
[0031] Prepare independent internal cavity flow channel sand core 3;
[0032] Aluminum foil is wrapped around the outside of the inner cavity flow channel sand core 3;
[0033] The aluminum foil-coated inner cavity flow channel sand core 3 is placed into the welding position of the narrow air passage, and the inner cavity flow channel sand core 3 is made to fit tightly against the inner cavity of the narrow air passage; specifically, the aluminum foil-coated inner cavity flow channel sand core 3 is pushed through the volute nozzle to the position of the process window to be welded, so that the aluminum foil-coated inner cavity flow channel sand core 3 corresponds to the process window and has a certain gap, the gap being the welding allowance, that is, the weld height.
[0034] Solder 6 is placed into process window 2; the inner cavity flow channel sand core 3 wrapped with aluminum foil is used to support solder 6 to prevent too much solder 6 from entering the narrow air passage and causing over-welding of process window 2; that is, process window 2 is the frame and inner cavity flow channel sand core 3 wrapped with aluminum foil is the bottom, forming a cavity for receiving solder 6. Solder 6 is fused with the narrow air passage through welding to achieve the purpose of welding repair process window 2.
[0035] The welding process window 2 restores the narrow airway to its original state. After welding, the inner cavity flow channel sand core 3 is broken and the narrow airway is cleaned out through the volute port 5.
[0036] By setting a process window 2 on the narrow air passage, the problems of poor weldability, poor operation visibility and difficult cleaning of the narrow air passage are improved. Specifically, the narrow air passage of the volute can be cleaned of sand and PT test through the process window 2.
[0037] As a supplement to this embodiment, a gap of 1.5mm-2.5mm is provided between the inner cavity flow channel sand core 3 wrapped with aluminum foil and the inner wall of the narrow air passage where the process window 2 is located, and the outer contour of the inner cavity flow channel sand core 3 wrapped with aluminum foil extends at least 20mm beyond the edge of the process window 2 to ensure good support for the welding of the process window 2, and to ensure the welding quality of the process window 2, so that it will not collapse or have poor edge fusion.
[0038] As a supplement to this embodiment, in order to prevent the inner cavity flow channel sand core 3 from collapsing due to high temperature during welding, and also to prevent the inner cavity flow channel sand core 3 from causing sand to stick to the weld, 2-3 layers of aluminum foil are wrapped around the outside of the inner cavity flow channel sand core 3 to improve the high temperature resistance of the inner cavity flow channel sand core 3 and prevent sand from sticking.
[0039] As a supplement to this embodiment,
[0040] like Figure 1 As shown, three process windows 2 are made on the outer wall of the narrow air passage from the volute inlet 5 to the volute tail on the three-dimensional model of the centrifugal compressor volute. These process windows 2 disrupt the integrity of the narrow air passage, so after the volute is cast, the process windows 2 need to be repaired by welding to restore the volute's integrity. The purpose of making these process windows 2 is to facilitate cleaning of surface defects such as adhering sand from the volute's inner cavity and to perform PT testing.
[0041] As a supplement to this embodiment, the welding method also includes pre-welding preparation.
[0042] Bevel preparation: A welding bevel is prepared at the process window 2, and the bevel and its surrounding area are cleaned, such as removing oil and rust. Specifically, welding bevels are prepared at the three process windows 2 to facilitate the filling of solder 6. As mentioned, the welding bevel is a V-shaped bevel, and acetone is used to clean the bevel, thus achieving the preparation and cleaning of the bevel to ensure good fusion of solder 6 with the narrow gas passage body.
[0043] As a supplement to this embodiment, the welding method further includes post-weld cleaning.
[0044] The reinforcing skeleton is bent to the curvature of the narrow airway from the first process window to the volute opening 5;
[0045] The flexible grinding tool is inserted into the first process window of the narrow air passage of the volute through the volute port 5, and the grinding head 8 is driven to rotate at high speed to grind the weld of the process window 2 so that the surface quality of the inner wall of the narrow air passage of the volute meets the design requirements, such as the surface roughness, so as to ensure the efficiency and quality of the volute in operation.
[0046] Workers use flexible grinding tools to grind and clean the weld excess, weld slag, and spatter.
[0047] As a supplement to this embodiment, the welding method further includes post-weld cleaning.
[0048] The reinforcing skeleton is bent to the curvature of the narrow airway from the second process window to the volute orifice 5;
[0049] The flexible grinding tool is inserted into the second process window of the narrow air passage of the volute through the volute port 5, and the grinding head 8 is driven to rotate at high speed to grind the weld of the process window 2 so that the surface quality of the inner wall of the narrow air passage of the volute meets the design requirements, such as the surface roughness, so as to ensure the efficiency and quality of the volute in operation.
[0050] Workers use flexible grinding tools to grind and clean the weld excess, weld slag, and spatter.
[0051] As a further supplement to this embodiment, the flexible grinding tool can also clean the sand adhering to the inner wall of the narrow airway after casting through the process window 2, and can also perform PT testing on the inner wall of the narrow airway through the process window 2, thus solving the problems of difficult cleaning and testing of the inner wall of the narrow airway.
[0052] As a further supplement to this embodiment, the flexible grinding tool includes a power source, a flexible drive shaft 7, a grinding head 8, and a reinforcing frame. The flexible drive shaft 7 is fitted inside the reinforcing frame, giving the flexible grinding tool a certain strength to ensure the grinding force on the weld. The power source and the grinding head 8 are respectively located at both ends of the flexible drive shaft 7. The grinding head 8 is used to grind the weld, and the power source provides power to the flexible grinding tool, that is, to the grinding head 8. Specifically, the reinforcing frame is made of a tough material such as steel bars. In order to facilitate the flexible grinding tool to smoothly extend into the weld position of the narrow air passage, before the flexible grinding tool operates, the reinforcing frame is bent into the curvature and shape of the narrow air passage from the inlet to the weld position, thereby facilitating the flexible grinding tool to extend from the volute opening 5 into the weld position. That is, after the weld position changes, the reinforcing frame needs to be bent again to adapt to the different positions.
[0053] As a further supplement to this embodiment, the flexible drive shaft 7 can be bent to any curvature to meet the purpose of extending into the narrow airway. Since the flexible drive shaft 7 is sleeved on the reinforcing frame, the curvature and shape of the reinforcing frame determine the curvature and shape of the flexible drive shaft 7. This allows the grinding head 8 connected to one end of the flexible drive shaft 7 to perform grinding operations on the narrow airway cavity of the volute, thus ensuring that the flexible grinding tool has a certain strength while having a certain curvature, providing support for the grinding head 8.
[0054] As a further supplement to this embodiment, the grinding head 8 is a replaceable miniature grinding head 8, which conveniently adapts to the grinding of welds in narrow air passages. Making the grinding head 8 replaceable facilitates efficient replacement after wear; making the grinding head 8 miniature facilitates grinding in narrow air passages of the volute and allows for targeted grinding of welds.
[0055] As a further supplement to this embodiment, the reinforcing frame includes a reinforcing rib 10 and a collar 11. The collar 11 is fixedly connected to the reinforcing rib 10. For example, the collar 11 can be welded to the reinforcing rib 10. Before welding the collar 11, the reinforcing rib 10 is prepared according to the curvature of the narrow airway to facilitate the insertion of the grinding head 8 at one end of the flexible drive shaft 7 into the weld of the narrow airway to grind the weld.
[0056] As a supplement to this embodiment, the welding method further includes weld inspection.
[0057] Use an endoscope to visually inspect the welds inside the narrow airway to ensure that the weld surface is smooth and flat.
[0058] By implementing the technical solution of this invention, efficient welding of the narrow airway process window 2 is achieved, and the problems of difficult cleaning and poor visibility of the narrow airway are solved by setting the process window 2; the accessibility of welding is achieved by setting the internal flow channel sand core.
[0059] The above embodiments are merely descriptions of a typical application of the technical solution of the present invention. Reasonable extensions can be made without requiring creative effort.
Claims
1. A welding method, characterized in that, include, Prepare independent internal cavity flow channel sand cores; Aluminum foil is wrapped around the outside of the inner cavity flow channel sand core; Place the aluminum foil-coated inner cavity flow channel core into the welding position of the narrow airway, and make the inner cavity flow channel core fit tightly against the inner cavity of the narrow airway. Solder is placed into the process window, and the process window is repaired by welding to restore the narrow airway to its integrity.
2. The welding method as described in claim 1, characterized in that, A gap of 1.5mm-2.5mm is provided between the inner cavity flow channel sand core wrapped with aluminum foil and the inner wall of the narrow air passage where the process window is located.
3. The welding method as described in claim 2, characterized in that, The outer contour of the inner cavity flow channel sand core wrapped with aluminum foil extends at least 20 mm beyond the edge of the process window.
4. The welding method as described in claim 1, characterized in that, The outer side of the inner cavity flow channel sand core is wrapped with 2-3 layers of aluminum foil.
5. The welding method as described in claim 1, characterized in that, It also includes pre-welding preparation, Bevel preparation: Prepare the welding bevel at the process window location and clean the bevel and its surrounding area.
6. The welding method as described in claim 1, characterized in that, It also includes post-weld cleaning. A flexible grinding tool is inserted into the narrow air passage, and the grinding head is driven to rotate at high speed to grind the weld area. Workers move grinding tools to grind and clean the weld excess, weld slag, and spatter.
7. The welding method as described in claim 6, characterized in that, The flexible grinding tool includes a power source, a flexible drive shaft, a grinding head, and a reinforcing frame. The flexible drive shaft is fitted inside the reinforcing frame. The power source and the grinding head are respectively located at both ends of the flexible drive shaft. The reinforcing frame is used to give the flexible grinding tool a certain strength. The grinding head is used to grind weld seams. The power source is used to provide power to the flexible grinding tool.
8. The welding method as described in claim 7, characterized in that, The reinforcing frame is made of a tough material such as steel bars, and includes reinforcing ribs and collars, with the collars fixedly connected to the reinforcing ribs.
9. The welding method as described in claim 7, characterized in that, The grinding head is a replaceable miniature grinding head.
10. The welding method as described in claim 1, characterized in that, It also includes weld inspection. Use an endoscope to visually inspect the welds inside the narrow airway to ensure that the weld surface is smooth and flat.