Method for welding composite middle plate and casting ledge of middle trough and middle trough

Abstract

The invention provides a welding method for a composite middle plate and a casting ledge of a middle trough and the middle trough, and belongs to the technical field of manufacturing of middle troughs of scraper conveyors. Comprising the steps that S1, a welding area is divided into a base layer area, a transition area and a cover face area according to the structure of the composite middle plate; and S2, welding wires of different strength grades are selected for welding based on the material characteristics of all the welding areas. The welding area is divided into the base layer area, the transition area and the cover face area according to the structure of the composite middle plate, welding wires of different strength grades are selected for welding according to the material characteristic requirement of each welding area, the welding seam strength of each area is matched with the strength of a corresponding component, the internal stress problem during welding of different materials is effectively relieved, and the welding quality is improved. And the defects of weld cracks, incomplete fusion and the like are reduced, so that the overall structural strength and wear resistance of the middle trough are improved, and the overall wear resistance and structural stability of the scraper conveyor are improved.

Description

Technical Field

[0001] This invention relates to the field of manufacturing technology for the central trough of scraper conveyors, specifically to a welding method for a composite central plate and a central trough casting sidewall, and the central trough itself. Background Technology

[0002] In coal mining operations, scraper conveyors are crucial coal transportation equipment, and the performance of their core component, the central trough, directly determines the operating efficiency and service life of the entire conveying system. During operation, the central trough continuously transports materials such as coal, enduring impacts and friction. Simultaneously, it serves as the running track for the coal mining machine, providing stable support and resisting the lateral forces and compressive stresses generated during machine operation. Therefore, it places extremely high demands on its structural strength and wear resistance.

[0003] Currently, the industry generally uses high-strength wear-resistant steel as the center plate of the coal trough to meet basic strength and wear resistance requirements. However, in mine conditions with high gangue content, the gangue mixed in the coal is hard and has sharp edges, which will cause severe erosion and wear on the center plate of the coal trough. The wear resistance of existing high-strength wear-resistant steel can no longer meet the requirements of long-term stable operation, resulting in a significant reduction in the service life of the coal trough. This not only increases equipment replacement costs but also frequently interrupts coal mining operations, affecting mining efficiency.

[0004] To address this issue, the industry has attempted to create composite mid-plate structures by adding super wear-resistant materials to the surface of wear-resistant mid-plates, thereby improving their wear resistance. However, composite mid-plates consist of a base material (the original wear-resistant mid-plate) and an additive layer (super wear-resistant material). The significant differences in the chemical composition and physical properties (such as melting point, coefficient of thermal expansion, and hardness) of these two materials make the welding of the composite mid-plate to the cast groove side of the mid-channel a critical manufacturing challenge. Improper welding processes can easily lead to defects such as cracks, lack of fusion, and porosity at the weld, severely affecting the overall structural strength and sealing of the mid-channel, and even causing potential problems such as weld cracking and mid-plate detachment during use. Summary of the Invention

[0005] In view of this, the present invention provides a welding method for a composite middle plate and a central groove cast wall, as well as a central groove, to solve the technical problem that existing welding methods for composite middle plates and central groove cast wall are prone to defects such as cracks and lack of fusion at the weld.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A welding method for a composite middle plate and a central channel casting side includes the following steps:

[0008] S1. Based on the structure of the composite plate, the welding area is divided into a base layer area, a transition area, and a cover area.

[0009] S2. Select welding wires of different strength grades for welding based on the material properties of each welding area.

[0010] Preferably, the composite medium plate includes a composite medium plate substrate and an additive cladding layer. The base layer area is the connection area between the composite medium plate substrate and the middle groove casting sidewall. The transition area is the area from the weld surface of the base layer area to the position corresponding to the weld surface 1-2 mm away from the surface of the additive cladding layer. The cover area is the area from the upper surface of the transition area to the surface of the additive cladding layer.

[0011] Preferably, in step S2, a base welding wire with the same strength grade as the cast wall of the central trough is used to perform multi-layer and multi-pass welding on the base area.

[0012] Preferably, in step S2, after welding is completed in the base area, a transition welding wire with a strength grade one grade lower than that of the base welding wire is used for welding in the transition area.

[0013] Preferably, in step S2, a high wear-resistant welding wire with the same strength grade as the additive cladding layer is used to perform multi-layer, multi-pass welding on the cover area.

[0014] Preferably, after the welding of the cover area is completed, the surface of the weld is flush with or slightly higher than the surface of the additive cladding layer, and the height difference does not exceed 1 mm.

[0015] Preferably, the welding area is preheated before welding, and the preheating range is 100mm on both sides of the weld.

[0016] Preferably, a symmetrical welding sequence is adopted during the welding process, and the welding is advanced from the symmetrical sides of the composite medium plate substrate and the middle groove casting groove side to the middle.

[0017] The present invention also provides a central channel, comprising a composite central plate and a central channel cast sidewall, wherein the composite central plate and the central channel cast sidewall are welded together using the welding method described above for the composite central plate and the central channel cast sidewall.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention divides the welding area into a base area, a transition area, and a cover area based on the structure of the composite plate. According to the material characteristics of each welding area, welding wires of different strength grades are selected for welding, so that the weld strength of each area matches the strength of the corresponding component. This effectively alleviates the internal stress problem when welding different materials, reduces the generation of defects such as weld cracks and lack of fusion, thereby improving the overall structural strength and wear resistance of the central trough, and further improving the overall wear resistance and structural stability of the scraper conveyor. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the central groove after welding using traditional welding methods.

[0021] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0022] Figure 3 This is a schematic diagram of the structure of the middle groove after welding using the welding method of the composite middle plate and the middle groove casting side of the present invention.

[0023] Figure 4 for Figure 3 A magnified view of a portion of the image.

[0024] In the figure: central channel 10, composite medium plate 100, composite medium plate substrate 110, additive cladding layer 120, central channel cast sidewall 200, base area 310, transition area 320, cover area 330, traditional weld position 400, non-welded area 500. Detailed Implementation

[0025] The technical solutions and effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] For welding composite intermediate plates to the cast sidewalls of the central channel, the current common method is a low-strength matching welding method using a single welding wire. For example... Figure 1 As shown, the traditional weld position 400 between the composite middle plate 100 and the central channel cast trough side 200 is welded using a single low-strength welding wire. However, the use of a single low-strength welding wire results in an overall weld strength lower than that of the composite middle plate substrate. Even in the welded area, it is difficult to meet the load-bearing requirements of long-term high-intensity operation of the central channel, limiting the service life and operational reliability of the equipment. Meanwhile, as... Figure 2As shown, existing methods leave a 20mm unwelded area 500 during welding. This unwelded area 500 creates a "connection break" between the composite middle plate substrate 110 and the cast sidewall of the middle trough 200, severely weakening the overall structural strength of the middle trough. Under material impact and lateral forces from the coal mining machine, this area easily becomes a stress concentration point, leading to structural deformation or cracking. Therefore, this invention provides a welding method for the composite middle plate and the cast sidewall of the middle trough, as well as a middle trough itself.

[0027] Please refer to Figure 3 A welding method for a composite middle plate and a central channel casting side, comprising the following steps:

[0028] S1. Based on the structure of the composite plate 100, the welding area is divided into a base area 310, a transition area 320, and a cover area 330.

[0029] S2. Select welding wires of different strength grades for welding based on the material properties of each welding area.

[0030] This invention divides the welding area into a base area 310, a transition area 320, and a cover area 330 based on the structure of the composite plate. According to the material characteristics of each welding area, welding wires of different strength grades are selected for welding, so that the weld strength of each area matches the strength of the corresponding component. This effectively alleviates the internal stress problem when welding different materials, reduces the generation of defects such as weld cracks and lack of fusion, thereby improving the overall structural strength and wear resistance of the central trough, and further improving the overall wear resistance and structural stability of the scraper conveyor.

[0031] Further, please see Figure 4 The composite medium plate 100 includes a composite medium plate substrate 110 and an additive cladding layer 120. The base region 310 is the connection area between the composite medium plate substrate 110 and the central channel casting side 200. The transition region 320 extends from the weld surface of the base region 310 to a position 1-2 mm away from the surface of the additive cladding layer 120. The cover region 330 extends from the upper surface of the transition region 320 to the surface of the additive cladding layer 120. Figure 4 As can be seen from the above, the welding method of the present invention eliminates the reserved unwelded area 500 in the prior art, and realizes full coverage welding of the connection area between the composite middle plate 100 and the middle channel casting side 200, eliminating the structural "breakpoints" and thus significantly improving the overall structural strength and load-bearing capacity of the middle channel.

[0032] Further, in step S2, a base welding wire with the same strength grade as the central channel casting sidewall is used to perform multi-layer, multi-pass welding on the base region 310. Specifically, the base region 310 is the connection area between the composite medium plate substrate 110 and the central channel casting sidewall 200. The composite medium plate substrate 110 has a strength grade of 1250 MPa, and the central channel casting sidewall 200 has a strength grade of 900-1000 MPa. Since the welding adopts the low-strength matching principle, a base welding wire with the same strength grade as the central channel casting sidewall is selected for the base region 310, i.e., the strength grade of the base welding wire is 900-1000 MPa. After selecting the base welding wire, multi-layer, multi-pass welding is performed on the base region 310, i.e., layer-by-layer, multi-pass filling weld, with each layer fused before the next layer is filled. This divides the welding process into multiple small segments, reducing welding deformation and making the welding strength more uniform, thereby increasing the welding strength. Furthermore, the multi-layer, multi-pass welding process can better control the welding temperature and welding speed, thereby improving the welding quality. Meanwhile, due to the more meticulous welding process, the probability of welding defects is also reduced. The welding current is 280-320A, the welding voltage is 20-33V, and the welding speed is 260-280mm / min.

[0033] Further, in step S2, after welding the base region 310, welding is performed in the transition region 320 using a transition welding wire with a strength grade one level lower than the base welding wire. Specifically, after welding the base region 310, welding is performed in the transition region 320. The transition region 320 extends from the weld surface of the base region 310 to a position 1-2 mm away from the surface of the additive cladding layer 120. A transition welding wire with a strength grade one level lower than the base welding wire is used, wherein the strength grade of the transition welding wire is 700-800 MPa. The welding parameters for the transition region 320 are the same as those for the base region 310, namely, the welding current for the transition region is 280-320 A, the welding voltage is 20-33 V, and the welding speed is 260-280 mm / min.

[0034] Further, in step S2, high-wear-resistant welding wire with the same strength grade as the additive cladding layer is used to perform multi-layer, multi-pass welding on the cover area 330. The additive cladding layer 120 has a strength grade of 500-600 MPa; therefore, a welding wire with a strength grade of 500-600 MPa is selected for welding the cover area 330. Simultaneously, the use of high-wear-resistant welding wire in the cover area 330 ensures that the weld surface has consistent wear resistance with the additive cladding layer, extending the service life of the central tank under high gangue content conditions. After the transition area 320 is welded, multi-layer, multi-pass welding is performed on the area from the surface of the transition area to the surface of the additive cladding layer. The welding current is 320-340 A, the welding voltage is 28-32 A, and the welding speed is 280-300 mm / min. In some embodiments, after the cover area 330 is welded, the weld surface is flush with or slightly higher than the surface of the additive cladding layer, and the height difference does not exceed 1 mm, so as to improve the wear resistance of the cover area 330.

[0035] As can be seen from the above, based on the material characteristics of the welding area, the strength grade of the welding wire in the base area 310, the transition area 320 and the cover area 330 decreases sequentially. Thus, by matching the layered welding wires and transitioning the strength gradient, the internal stress problem of welding different materials is solved. At the same time, it ensures that the weld strength in each area matches the strength of the corresponding component, reducing the occurrence of defects such as weld cracks and lack of fusion.

[0036] Furthermore, a symmetrical welding sequence is adopted during the welding process, advancing from the symmetrical sides where the composite middle plate substrate 110 connects to the central channel casting side 200 towards the center. Specifically, a symmetrical welding sequence is used during the welding process, i.e., two passes are welded on the front side, and then two passes are welded on the reverse side, with each welding operation advancing from the symmetrical sides where the composite middle plate substrate 110 connects to the central channel casting side 200 towards the center. During front-side welding, the metal melts due to heat, and when welding stops, the molten metal solidifies and shrinks, causing the weldment to warp upwards; while during reverse-side welding, a downward force is applied to the weldment. Thus, through symmetrical welding, the upward and downward forces cancel each other out, thereby eliminating welding deformation, reducing weld defects, and improving welding quality.

[0037] In some implementations, before each weld pass, the slag, spatter, and oxide scale of the previous weld pass must be cleaned. Residual slag or spatter can lead to defects such as slag inclusions and porosity in subsequent welds, affecting weld quality. A wire brush can be used to clean the slag, spatter, and oxide scale of the previous weld pass to improve weld quality. Thorough removal of slag and oxide scale exposes a clean metal surface, promoting full fusion between the next weld pass and the previous pass, and preventing poor interface bonding.

[0038] Furthermore, the welding area is preheated before welding, extending to a 100mm zone on both sides of the weld. Preheating methods include flame heating, resistance heating, and induction heating. Flame heating utilizes a flame generated by the combustion of a mixture of fuel gas and oxygen to heat the weld and its surrounding area; resistance heating and induction heating utilize heat generated by electrical energy or electromagnetic induction. Preheating ensures that the areas on both sides of the weld reach a certain temperature, reducing the temperature gradient during welding and thus minimizing stress and deformation. In addition, preheating improves the plasticity of the metal, reduces its hardness, makes welding easier, and enhances the stability and reliability of the weld quality.

[0039] During welding, hydrogen from the welding rod, flux, and air is decomposed into atomic states and dissolved in the liquid metal at high temperatures. As the weld cools, the solubility of hydrogen in the steel decreases sharply. Due to the rapid cooling, the hydrogen cannot escape quickly enough and remains in the weld metal, accumulating over time in the weld or fusion zone. When the hydrogen accumulates to a certain level, it can cause delayed cracking in the weld or heat-affected zone under welding stress. Therefore, post-weld heat treatment is necessary to eliminate hydrogen. Specifically, after welding, the weld area is heated to 200-350℃ and maintained for 0.5-1 hour to promote hydrogen diffusion, allowing it to escape rapidly from the weld and heat-affected zone, effectively reducing the risk of cold cracking and improving weld quality.

[0040] In some implementations, after the overall welding is completed, ultrasonic testing is used to perform 100% internal quality inspection of the weld, while visual inspection is also performed to ensure that there are no defects such as cracks, porosity, slag inclusions, or undercut.

[0041] The present invention also provides a central groove 10, comprising a composite central plate 100 and a central groove cast side 200. The composite central plate 100 and the central groove cast side 200 are welded together using the welding method described above for the composite central plate and the central groove cast side. The welding method based on the present invention can reduce the generation of defects such as weld cracks and lack of fusion, thereby avoiding the hidden dangers of weld cracking and central plate detachment during the use of the central groove 10, and improving the overall structural strength and wear resistance of the central groove.

[0042] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A welding method for a composite middle plate and a central channel casting sidewall, characterized in that, Includes the following steps: S1. Based on the structure of the composite plate, the welding area is divided into a base layer area, a transition area, and a cover area. S2. Select welding wires of different strength grades for welding based on the material properties of each welding area.

2. The welding method for the composite middle plate and the central groove casting sidewall according to claim 1, characterized in that, The composite medium plate includes a composite medium plate substrate and an additive cladding layer. The base area is the connection area between the composite medium plate substrate and the middle groove casting side. The transition area is the area from the weld surface of the base area to the position corresponding to the weld surface 1-2mm away from the surface of the additive cladding layer. The cover area is the area from the upper surface of the transition area to the surface of the additive cladding layer.

3. The welding method for the composite middle plate and the middle channel casting sidewall according to claim 2, characterized in that, In step S2, a base welding wire with the same strength grade as the cast wall of the central trough is used to perform multi-layer and multi-pass welding on the base area.

4. The welding method for the composite middle plate and the middle channel casting sidewall according to claim 3, characterized in that, In step S2, after welding is completed in the base area, a transition welding wire with a strength grade one grade lower than that of the base welding wire is used for welding in the transition area.

5. The welding method for the composite middle plate and the middle channel casting sidewall according to claim 2, characterized in that, In step S2, high wear-resistant welding wire with the same strength grade as the additive cladding layer is used to perform multi-layer, multi-pass welding on the cover area.

6. The welding method for the composite middle plate and the middle channel casting sidewall according to claim 5, characterized in that, After the welding of the cover area is completed, the surface of the weld is flush with or slightly higher than the surface of the additive cladding layer, and the height difference does not exceed 1mm.

7. The welding method of the composite middle plate and the middle channel casting side according to any one of claims 1-6, characterized in that, Before welding, the welding area is preheated, and the preheating range is 100mm on both sides of the weld.

8. The welding method for the composite middle plate and the middle channel casting side according to claim 7, characterized in that, The welding process employs a symmetrical welding sequence, progressing from the symmetrical sides where the composite medium plate substrate connects to the central groove casting side towards the middle.

9. The welding method of the composite middle plate and the middle channel casting side according to claim 8, characterized in that, After welding, post-heating hydrogen removal treatment is performed.

10. A central channel, comprising a composite central plate and a central channel cast sidewall, wherein the composite central plate and the central channel cast sidewall are welded together using the welding method for the composite central plate and the central channel cast sidewall as described in any one of claims 1-9.

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