Multi-metal material combined composite scraper and manufacturing method thereof

Abstract

The invention provides a multi-metal material combined composite scraper blade and a manufacturing method thereof, and belongs to the field of mine conveying equipment parts. Comprising a scraper axe and a scraper middle section, the scraper axe comprises a working surface layer and a base body, the working surface layer wraps the outer surface of the base body, the working surface layer is made of high-chromium cast iron, and the base body is made of low-carbon cast steel; the middle scraper blade section is formed by die forging of alloy steel; the scraper blade axe and the scraper blade middle section are connected in a welded mode. The sectional structure of the scraper blade axe and the scraper blade middle section is adopted, adaptive materials are selected according to the functional requirements of different parts, the material performance limitation of a traditional integral scraper blade is broken through, and precise adaptation of abrasion-resistant parts special for abrasion resistance and stress parts special for strength is achieved. And moreover, the scraper axe and the scraper middle section are combined through welding, so that the connection reliability of the segmented structure can be guaranteed, and weld joint cracking under the underground impact working condition is avoided.

Description

Technical Field

[0001] This invention relates to the field of mining conveying equipment components technology, specifically to a multi-metal composite scraper and its manufacturing method. Background Technology

[0002] As a core conveying equipment in mining, scraper conveyors have scrapers that come into direct contact with materials such as coal and gangue. During operation, they must withstand continuous high-load friction and impact loads from the materials, as well as corrosion and wear caused by damp and corrosive media (such as sulfides and groundwater) underground. These scraper blades are the most rapidly worn and most severely damaged parts of the scraper conveyor. The replacement of worn-out scraper blades not only increases production costs in mining but also leads to equipment downtime, severely impacting mining efficiency.

[0003] like Figure 1 As shown, traditional scrapers mostly adopt a one-piece structure, forged from a single alloy steel. To improve wear resistance, induction hardening is usually used to increase the surface hardness of the scraper head. Although this can meet the wear resistance requirements of the scraper head (the main wear area) to a certain extent, due to the limitations of the overall structure, uneven temperature field is prone to occur during the hardening process, resulting in inconsistent hardened layer thickness, unreasonable hardness gradient, and even problems such as hardening cracking and deformation. Moreover, there is an inherent contradiction in integral alloy steel: "hardness and toughness are difficult to balance"—that is, increasing hardness reduces toughness, making it prone to fracture under impact load; ensuring toughness results in insufficient wear resistance and shortened service life. Summary of the Invention

[0004] In view of this, the present invention provides a multi-metal composite scraper and its manufacturing method to solve the technical problems of uneven quenching and cracking that easily occur when traditional integral scrapers use induction hardening process to improve wear resistance, as well as the inherent contradiction of "difficulty in balancing hardness and toughness".

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A multi-metal composite scraper includes a scraper head and a scraper middle section. The scraper head includes a working surface layer and a substrate. The working surface layer is wrapped around the outer surface of the substrate. The working surface layer is made of high-chromium cast iron, and the substrate is made of low-carbon cast steel. The scraper middle section is formed by die forging of alloy steel. The scraper head and the scraper middle section are connected by welding.

[0007] Preferably, the chemical composition of the high-chromium cast iron includes C: 3.3~3.5, Cr: 26~32, Mn: 1.75~2.0, Mo: 1.5~1.85, Cu: 0.8~1.0, B: 0.02, P, S≤0.6.

[0008] Preferably, the chemical composition of the low-carbon cast steel includes C: 0.16~0.23, Si: 0.20~0.60, Mn: 1.00~1.60, P≤0.025, S≤0.025, Ni≤0.40, Cr≤0.40, Cu≤0.40, Mo≤0.15, and V≤0.05.

[0009] Preferably, the connecting surface of the scraper axe head is provided with a first connecting boss, and two second connecting bosses are provided at intervals at both ends of the middle section of the scraper. The first connecting boss is inserted into the gap formed between the two second connecting bosses, and the connection between the first connecting boss and the second connecting boss is welded together.

[0010] The present invention also provides a method for manufacturing a multi-metal composite scraper, which is used to manufacture the multi-metal composite scraper as described above, comprising the following steps:

[0011] S1. First pour the base material, and when a liquid film forms on the surface of the base material, pour the working surface layer.

[0012] S2. After the casting has cooled, it is machined to complete the production of the scraper axe.

[0013] S3. The middle section of the scraper is manufactured using alloy steel die forging process;

[0014] S4. Use welding rods to perform arc welding on the connection between the scraper axe head and the middle section of the scraper.

[0015] Preferably, in step S1, the pouring temperature of the working surface layer is 1450~1500℃, and the pouring temperature of the substrate is 1300~1350℃.

[0016] Preferably, in step S3, after forging, normalizing treatment is performed, wherein the heating temperature is 880~900℃, and the temperature is held for 2~3 hours before air cooling.

[0017] Preferably, in step S4, the welding current is 120~150A, the arc voltage is 22~28V, and the welding speed is 3~5mm / s.

[0018] Preferably, before step S4, the connecting surface between the scraper axe and the middle section of the scraper is sandblasted; after sandblasting, the connecting part is preheated, and the preheating temperature is controlled at 250~300℃.

[0019] Preferably, the joint is immediately wrapped with asbestos cloth after welding and allowed to cool slowly to room temperature.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The multi-metal composite scraper of this invention adopts a segmented structure of scraper axe head and scraper middle section. The scraper axe head, as the working wear part of the scraper, is designed with a working surface layer and a substrate. The working surface layer is made of high-chromium cast iron, wrapped around the outer surface of the substrate, utilizing the high hardness of high-chromium cast iron to improve the wear resistance of the scraper axe head. The substrate is made of low-carbon cast steel, utilizing the high toughness and impact resistance of low-carbon cast steel to prevent the scraper axe head from breaking under material impact. Thus, the scraper axe head of this invention can simultaneously meet the dual requirements of "high wear resistance" and "high toughness and fracture resistance." The scraper middle section, as the force-bearing traction part of the scraper, is made of alloy steel through die forging to ensure sufficient load-bearing capacity and deformation resistance. Therefore, this invention, by adopting a segmented structure of scraper axe head and scraper middle section, selects appropriate materials for the functional requirements of different parts, breaking through the material performance limitations of traditional integral scrapers, and achieving precise adaptation where "wear-resistant parts focus on wear resistance, and force-bearing parts focus on strength." Furthermore, the scraper axe head and the middle section of the scraper are assembled by welding, which can ensure the reliability of the connection of the segmented structure and avoid weld cracking under downhole impact conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a traditional scraper.

[0023] Figure 2 This is a schematic diagram of the structure of the multi-metal composite scraper of the present invention.

[0024] Figure 3 This is a schematic diagram of the scraper axe head of the present invention.

[0025] Figure 4 This is a schematic diagram of the middle section of the scraper of the present invention.

[0026] In the figure: scraper axe head 100, working surface 110, base 120, first connecting boss 130, scraper middle section 200, second connecting boss 210, weld 300. Detailed Implementation

[0027] 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.

[0028] Please also refer to Figure 2 and Figure 3 A multi-metal composite scraper 10 includes a scraper axe head 100 and a scraper middle section 200. The scraper axe head 100 includes a working surface layer 110 and a base 120. The working surface layer 110 is wrapped around the outer surface of the base 120. The working surface layer 110 is made of high-chromium cast iron, and the base 120 is made of low-carbon cast steel. The scraper middle section 200 is formed by die forging of alloy steel. The scraper axe head 100 and the scraper middle section 200 are connected by welding.

[0029] The multi-metal composite scraper 10 of this invention adopts a segmented structure of scraper axe head 100 and scraper middle section 200. The scraper axe head 100, as the working wear part of the scraper, is designed with a working surface layer 110 and a base 120. The working surface layer 110 is made of high-chromium cast iron and wraps around the outer surface of the base 120 to utilize the high hardness of high-chromium cast iron to improve the wear resistance of the scraper axe head 100. The base 120 is made of low-carbon cast steel to utilize the high toughness and impact resistance of low-carbon cast steel to prevent the scraper axe head from breaking under material impact. Thus, the scraper axe head 100 of this invention can simultaneously meet the dual requirements of "high wear resistance" and "high toughness and fracture resistance". The scraper middle section 200, as the force-bearing traction part of the scraper, is made of alloy steel by die forging to ensure that the scraper middle section 200 has sufficient load-bearing capacity and deformation resistance. Therefore, this invention, by employing a segmented structure of the scraper axe head 100 and the scraper middle section 200, selects suitable materials for the functional requirements of different parts, breaking through the material performance limitations of traditional integral scrapers and achieving precise adaptation where "wear-resistant parts focus on wear resistance and stress-bearing parts focus on strength." Furthermore, the scraper axe head 100 and the scraper middle section 200 are welded together, ensuring the reliability of the segmented structure connection and preventing weld cracking under downhole impact conditions.

[0030] Furthermore, the chemical composition of high-chromium cast iron includes C: 3.3~3.5, Cr: 26~32, Mn: 1.75~2.0, Mo: 1.5~1.85, Cu: 0.8~1.0, B: 0.02, and P and S ≤ 0.6. Among these, C is one of the main alloying elements in high-chromium cast iron, which can improve the material's hardness and strength; Cr is a key alloying element in high-chromium cast iron, which can improve the material's wear resistance and corrosion resistance; Mn can improve the material's strength and toughness; Mo and Cu can further improve the material's corrosion resistance and wear resistance; B, as a strong carbide-forming element, can increase the hardenability of the material matrix and promote martensite formation, thereby improving strength and wear resistance without reducing toughness. Thus, the high hardness of high-chromium cast iron is utilized to improve the wear resistance of the working surface of the scraper axe.

[0031] Furthermore, the chemical composition of low-carbon cast steel includes C: 0.16~0.23, Si: 0.20~0.60, Mn: 1.00~1.60, P≤0.025, S≤0.025, Ni≤0.40, Cr≤0.40, Cu≤0.40, Mo≤0.15, and V≤0.05. Low-carbon cast steel generally has a low carbon content, which improves its toughness. Si (Si) improves the fluidity of cast steel, reduces casting defects, and enhances its corrosion resistance. Mn (Mn) increases the hardness and strength of cast steel, improves its heat treatment performance, refines grains, and enhances its toughness. S (S) and P (P) are harmful elements in low-carbon cast steel; their content should be as low as possible. Excessive sulfur and phosphorus content reduces the toughness and weldability of the steel and increases the risk of brittleness. Therefore, the content of these two elements needs to be strictly controlled during the casting process. Ni (Ni) lowers the toughness-brittle transition temperature of steel, improving not only its plasticity and toughness at room temperature but also its performance at low temperatures. The toughness of low-carbon cast steel is improved by Cr, which enhances its hardness, wear resistance, and compressive strength. The presence of Cr also enhances the toughness and strength of low-carbon cast steel, making it more robust. In the tempered state, Cu lowers the toughness-brittle transition temperature of steel, thus improving its toughness. The addition of Mo significantly refines the grains and inhibits austenite grain coarsening, thereby improving the toughness and strength of low-carbon cast steel. V primarily refines the grains, strengthens the matrix structure, increases strength, and improves thermal stability. By using different elements, low-carbon cast steel acquires high toughness and impact resistance, thus preventing the scraper axe 100 from breaking under material impact.

[0032] Furthermore, please also refer to Figure 2 , Figure 3 and Figure 4 The scraper axe head 100 has a first connecting boss 130 on its connecting surface. Two second connecting bosses 210 are spaced apart at both ends of the scraper middle section 200. The first connecting boss 130 is inserted into the gap formed between the two second connecting bosses 210, and the connection between the first connecting boss 130 and the second connecting bosses 210 is achieved by welding. Specifically, after the first connecting boss 130 is inserted into the two second connecting bosses 210, the scraper axe head 100 and the scraper middle section 200 are welded together using welding wire to achieve a fixed connection between the scraper axe head 100 and the scraper middle section 200. In some embodiments, V-shaped bevels are pre-formed on the surfaces of the first connecting boss 130 and the second connecting bosses 210. The formation of the V-shaped bevels increases the gap between the scraper axe head 100 and the scraper middle section 200, thereby forming a... Figure 2 The weld 300 shown facilitates the formation of effective penetration depth during welding, thereby enhancing the connection strength between the scraper axe head 100 and the middle section 200 of the scraper.

[0033] The present invention also provides a method for manufacturing a multi-metal composite scraper, which is used to manufacture the multi-metal composite scraper as described above, comprising the following steps:

[0034] S1. First pour the base material, and when a liquid film forms on the surface of the base material, pour the working surface layer.

[0035] S2. After the casting has cooled, it is machined to complete the production of the scraper axe.

[0036] S3. The middle section of the scraper is manufactured using alloy steel die forging process;

[0037] S4. Use welding rods to perform arc welding on the connection between the scraper axe head and the middle section of the scraper.

[0038] This invention employs sand casting to manufacture the scraper axe head. First, the base material is poured, and once a liquid film forms on the surface of the base material, the working surface layer is poured to form the scraper axe head. This liquid film bonding method achieves the bonding between the working surface layer and the base material, solving the problems of weak bonding and easy detachment of the wear-resistant layer in traditional overlay welding. At the same time, it achieves the complementary performance of the high-chromium cast iron working surface layer and the low-carbon cast steel base material. Then, the scraper middle section is manufactured using alloy steel die forging. Finally, the connection between the scraper axe head and the scraper middle section is arc welded using welding rods. This ensures the reliability of the connection between the segmented structure of the scraper axe head and the scraper middle section, and avoids weld cracking under downhole impact conditions.

[0039] Further, in step S1, the pouring temperature of the working surface layer is 1450~1500℃, and the pouring temperature of the base is 1300~1350℃. Specifically, in manufacturing the scraper axe, this invention employs a sand casting process. First, low-carbon cast steel is poured to form the base, with a pouring temperature of 1300~1350℃. When a 5~8mm liquid film forms on the base surface, i.e., when the base surface is not fully solidified, high-chromium cast iron is poured to form the working surface layer, with a pouring temperature of 1450~1500℃. Because the pouring temperature of the working surface layer is different from that of the base, and a liquid film forms on the base surface during the pouring of the working surface layer, atoms at the interfaces of the working surface layer and the base diffuse into each other under the drive of the temperature difference, forming a strong metallurgical bonding interface. Metallurgical bonding not only enhances the mechanical connection between the scraper axe head and the scraper middle section but also promotes the fusion of chemical properties, enabling the two different metals to integrate more tightly. This solves the problems of weak bonding and easy detachment of traditional weld overlay wear-resistant layers, while achieving complementary properties between the high-chromium cast iron surface layer and the low-carbon cast steel substrate. Scraper axes manufactured using this method have an interface strength ≥150MPa, a working surface hardness of HRC55~60, and a substrate impact toughness ≥20J / cm². In some embodiments, machining is performed after the casting has cooled. On the one hand, a bevel is machined on the first connecting boss of the scraper axe head to facilitate effective weld penetration; on the other hand, the connecting surface of the scraper axe head is machined to ensure that the flatness of the connecting surface with the scraper middle section is ≤0.2mm / m, ensuring welding precision.

[0040] Further, in step S3, normalizing treatment is performed after forging, wherein the heating temperature is 880~900℃, and the temperature is held for 2~3 hours before air cooling. The scraper middle section of the present invention is made of 42CrMo alloy steel to meet the huge tensile force requirements generated by chain traction. At the same time, the scraper middle section is manufactured by die forging and normalized after forging to eliminate forging stress and refine the grain, so that the tensile strength of the scraper middle section is ≥1080MPa, the yield strength is ≥930MPa, and the elongation is ≥15%, ensuring that the scraper middle section has sufficient load-bearing capacity and deformation resistance. After forming, second connecting bosses matching the scraper axe head are machined at both ends of the scraper middle section. The surface of the second connecting boss has a V-shaped bevel, which facilitates the formation of effective penetration depth during welding and improves the connection strength.

[0041] Further, in step S4, the welding current is 120~150A, the arc voltage is 22~28V, and the welding speed is 3~5mm / s. Specifically, this invention uses ER69~G welding electrodes for MAG arc welding, with a welding current of 120~150A, an arc voltage of 22~28V, and a welding speed of 3~5mm / s. The welding process employs a multi-layer, multi-pass welding technique, i.e., filling the weld seam in layers and passes, 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 technique allows for better control of welding temperature and speed, thus improving welding quality. Simultaneously, due to the more meticulous welding process, the probability of welding defects is also reduced. In multi-layer welding, after each layer is welded, the surface is cleaned with a wire brush to remove weld slag and spatter. Residual weld slag or spatter can lead to defects such as slag inclusions and porosity in subsequent welds, affecting weld quality. Thoroughly removing weld slag and oxide scale exposes a clean metal surface, promoting full fusion between the next weld layer and the previous layer and preventing poor interface bonding. Furthermore, in multi-layer, multi-pass welding, controlling the interpass temperature is crucial. Excessively high interpass temperatures result in coarse weld microstructure, reducing toughness and strength; excessively low interpass temperatures increase welding stress, making cracking more likely. In this invention, the interpass temperature needs to be controlled at no less than 200°C to prevent rapid cooling and cracking.

[0042] Further, before step S4, the connection surface between the scraper axe and the middle section of the scraper is sandblasted. After sandblasting, the connection area is preheated, with the preheating temperature controlled at 250~300℃. Specifically, before welding, abrasive is sprayed at high speed through a spray gun onto the connection surface between the scraper axe and the middle section of the scraper to remove impurities such as oxide scale and rust from the surface of the connection surface, ensuring that the weld is in a clean, smooth, and rough state, ensuring a clean weld surface, providing a good foundation for welding, and avoiding welding defects such as porosity or slag inclusions caused by impurities. After sandblasting, the connection area needs to be preheated. Preheating methods include flame heating, resistance heating, and induction heating, with the preheating temperature controlled at 250~300℃. The temperature measuring point is 50mm away from the bevel to ensure uniform temperature. Among them, flame heating uses the flame generated by the combustion of a mixture of gas and oxygen to heat the weld and its surrounding area; resistance heating and induction heating use the heat generated by electrical energy or electromagnetic induction. Preheating allows the weld and its surrounding area to reach a certain temperature, reducing the temperature gradient during welding and thus decreasing stress and deformation. Furthermore, preheating improves the plasticity of the metal, reduces its hardness, making welding easier and improving weld quality. Simultaneously, preheating can reduce defects such as hydrogen-induced cracking during welding, increasing the strength and toughness of the weld joint.

[0043] Furthermore, immediately after welding, the joint is wrapped with asbestos cloth and allowed to cool slowly to room temperature to eliminate residual welding stress, prevent defects such as porosity and cracks, and ensure that the weld tensile strength is ≥700MPa. In some embodiments, after welding, ultrasonic testing can be used to detect internal weld cracks, porosity, and other defects, with a flaw detection pass rate of ≥99%. This invention effectively eliminates welding stress, ensures the reliability of segmented structure connections, and avoids weld cracking under downhole impact conditions through targeted pre-weld pretreatment, multi-layer multi-pass welding, and post-weld slow cooling processes.

[0044] As an example, the multi-metal composite scraper of the present invention was manufactured using the above-described manufacturing method. The performance of the multi-metal composite scraper of the present invention was compared with that of a conventional integral scraper, and the performance results are shown in Table 1.

[0045] Table 1: Performance Comparison of Multi-Metal Composite Scraper Blade and Traditional Integral Scraper Blade Performance indicators Traditional integrated scraper This invention relates to a multi-metal composite scraper. Axe hardness (HRC) 45~50 55~60 Wear-resistant life (months) 3~6 ≥12 Repair cost comparison 100% Reduce by 60% Adaptability Single working condition Adjustable for multiple operating conditions

[0046] As shown in Table 1, the axe head of the multi-metal composite scraper of this invention has a higher hardness than that of the traditional integral scraper head. Furthermore, the wear resistance of the scraper head of this invention is 3-6 times higher than that of the traditional integral scraper head, the risk of fracture in the middle section of the scraper is reduced by 80%, and the overall service life is extended to more than 12 months. This indicates that the scraper head of the multi-metal composite scraper of this invention adopts an optimized match of "wear-resistant surface layer + tough matrix," and the forged steel in the middle section of the scraper ensures overall strength, thus resolving the contradiction of traditional scrapers being "wear-resistant but not fracture-resistant, and fracture-resistant but not wear-resistant." Moreover, this invention adopts a segmented design, allowing for individual replacement of worn scraper heads, reducing maintenance costs by 60%; the welding process is mature and facilitates industrial production.

[0047] The above description discloses only 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 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 composite scraper made of multiple metal materials, characterized in that, The device includes a scraper axe head and a scraper middle section. The scraper axe head includes a working surface layer and a base body. The working surface layer is wrapped around the outer surface of the base body. The working surface layer is made of high-chromium cast iron, and the base body is made of low-carbon cast steel. The scraper middle section is formed by die forging of alloy steel. The scraper axe head and the scraper middle section are connected by welding.

2. The multi-metal composite scraper according to claim 1, characterized in that, The chemical composition of the high-chromium cast iron includes C: 3.3~3.5, Cr: 26~32, Mn: 1.75~2.0, Mo: 1.5~1.85, Cu: 0.8~1.0, B: 0.02, P, S≤0.

6.

3. The multi-metal composite scraper according to claim 2, characterized in that, The chemical composition of the low-carbon cast steel includes C: 0.16~0.23, Si: 0.20~0.60, Mn: 1.00~1.60, P≤0.025, S≤0.025, Ni≤0.40, Cr≤0.40, Cu≤0.40, Mo≤0.15, and V≤0.

05.

4. The multi-metal composite scraper according to claim 1, characterized in that, The connecting surface of the scraper axe head is provided with a first connecting boss, and two second connecting bosses are provided at intervals at both ends of the middle section of the scraper. The first connecting boss is inserted into the gap formed between the two second connecting bosses, and the connection between the first connecting boss and the second connecting boss is welded together.

5. A method for manufacturing a multi-metal composite scraper, used to manufacture the multi-metal composite scraper as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. First pour the base material, and when a liquid film forms on the surface of the base material, pour the working surface layer. S2. After the casting has cooled, it is machined to complete the production of the scraper axe. S3. The middle section of the scraper is manufactured using alloy steel die forging process; S4. Use welding rods to perform arc welding on the connection between the scraper axe head and the middle section of the scraper.

6. The method for manufacturing a multi-metal composite scraper according to claim 5, characterized in that, In step S1, the pouring temperature of the working surface layer is 1450~1500℃, and the pouring temperature of the substrate is 1300~1350℃.

7. The method for manufacturing a multi-metal composite scraper according to claim 5, characterized in that, In step S3, after forging, normalizing treatment is performed, wherein the heating temperature is 880~900℃, and the temperature is held for 2~3 hours before air cooling.

8. The method for manufacturing a multi-metal composite scraper according to claim 5, characterized in that, In step S4, the welding current is 120~150A, the arc voltage is 22~28V, and the welding speed is 3~5mm / s.

9. The method for manufacturing a multi-metal composite scraper according to claim 8, characterized in that, Before step S4, the connecting surface between the scraper axe and the middle section of the scraper is sandblasted; after sandblasting, the connecting part is preheated, and the preheating temperature is controlled at 250~300℃.

10. The method for manufacturing a multi-metal composite scraper according to claim 9, characterized in that, Immediately after welding, wrap the joint with asbestos cloth and allow it to cool slowly to room temperature.

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