Compact mining chain heat treatment and coating process and equipment

Abstract

The invention discloses a compact mining chain heat treatment and coating process and equipment. The compact mining chain heat treatment and coating equipment comprises a chain inlet section, a heat treatment unit, an acid pickling and plating assisting unit, a hot galvanizing unit, a cooling section, a passivating treatment section and a chain outlet section which are sequentially arranged. The quenching and tempering process and the hot-dip galvanizing process of a traditional chain are combined, the tempering process of the chain is omitted, precipitation of carbides in steel is achieved in the preheating and hot-dip galvanizing process of the chain, a galvanized layer is formed on the surface of the chain, meanwhile, the structure performance regulation and control of the chain steel are completed, and the service life of the chain is prolonged. High-efficiency production of the mining chain is achieved, and the physical quality and the production efficiency of the chain are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chain deep processing, and relates to a compact mining chain heat treatment and coating process and equipment. Background Art

[0002] Mining round link chain is an important component used in mechanized coal mining in coal mines. It is mainly used as a transmission chain on scraper conveyors, scraper transfer machines, coal mining machines and coal planers, and can play a transmission role. In actual use, mining round link chains need to have high strength and toughness, fatigue resistance and wear resistance to ensure normal use; at the same time, since the working environment of coal mines is mostly humid and corrosive underground, mining round link chains are usually required to have good corrosion resistance.

[0003] Mining chains are mainly divided into two types: mining round link chains and mining compact chains. Mining round link chains are connected by each welded ring, and the geometric dimensions are completely consistent. Mining compact chains are composed of welded flat rings and forged vertical rings. The size and type of the flat rings are consistent with those of mining round link chains. The two sides of the vertical rings are flat, and the outer width is smaller than that of mining round link chains. The manufacturing process of the chain mainly includes round steel cutting, ring weaving, welding, quenching and tempering heat treatment. Ring weaving mainly bends the bar of a specified length on the corresponding mold to meet the process size and shape requirements of the chain ring to be welded; welding mainly uses flash welding to weld the braided chain rings into rings; heat treatment mainly uses quenching and tempering processes to make the chain have high strength, high toughness, wear resistance, corrosion resistance and other complex and contradictory comprehensive mechanical properties, as well as stricter requirements such as microstructure and hardness. However, in actual application, coal mines are mostly working in a humid environment. High-strength mining chains are inevitably affected by environmental corrosion during use. In addition, high-strength mining chains have high stress and are more sensitive to stress corrosion. They are very likely to cause corrosion fatigue fractures during use (frequent low-load brittle fractures occur in as little as a few days or as many months), causing early failure of mining chains.

[0004] At present, in response to the needs in practical applications, major domestic steel mills have also developed a series of high-strength and corrosion-resistant mining chain steels according to different user needs; for example, Chinese patent application No. CN201610993472.0 discloses a high-strength and high-toughness corrosion-resistant chain steel and its heat treatment method, the chemical composition of the steel is: C: 0.06~0.11wt.%, Si: 0.15~0.35wt.%, Mn: 0.30~0.50wt.%, Cr: 1.00~3.00wt.%, Ni: 2.00~4.00wt.%, Mo: 0.30~0.60wt.%, Nb: 0.02~0.06wt.%, V: 0.03~0.09wt.%, P<0.015wt.%, S<0.015wt.%, the remainder is Fe and unavoidable impurities. The chain heat treatment adopts a vertical continuous heat treatment furnace and a process of two quenching heat treatments and one tempering heat treatment. The chain passes through A austenitizing heating furnace, A quenching tank, B austenitizing heating furnace, B quenching tank and C tempering heating furnace. After heat treatment, a lath martensite structure with a lath width of 0.3-5μm is obtained. Granular cementite with a diameter of 0.2-0.8μm and a volume fraction of 0.15%-0.35% and MC phase particles with a diameter of 5-15nm and a volume fraction of 0.02%-0.08% are dispersed between and inside the laths. The tensile strength of the chain after heat treatment reaches 1000MPa, the KV2 (-60℃) of the ring back and weld is more than 100, and the seawater corrosion resistance is good.

[0005] In addition, the chain can also be coated to improve the corrosion resistance of the mining chain. Due to the differences between the chain and traditional strip steel coating, the related coating industry and equipment are also different. For example, Chinese patent application number CN201810453063.0 discloses a galvanizing production line for single-strand rope or chain-type plated parts, comprising an ammonium chloride pool and a hot-dip galvanizing furnace arranged in sequence along the traveling direction of the plated parts, the hot-dip galvanizing furnace comprising a zinc furnace steel structure, a furnace body and a zinc pot, a burner is arranged on the furnace body, a fire channel is arranged between the furnace body and the zinc pot, and the flame ejection port of the burner is connected to the fire channel; a plated part drying and preheating device is arranged between the ammonium chloride pool and the hot-dip galvanizing furnace; the plated part drying and preheating device comprises a drying and preheating pipe, the drying and preheating pipe is installed on a preheating bracket, one end of the drying and preheating pipe is opened as a plated part inlet, and a first roller device is installed on the preheating bracket near the plated part inlet; the other end of the drying and preheating pipe is connected to the furnace body, a drying and preheating channel coaxially connected to the inner hole of the drying and preheating pipe is arranged on the furnace body, a plated part outlet is arranged at one end of the drying and preheating channel away from the drying and preheating pipe, and an opening connected to the fire channel is arranged on the side of the drying and preheating channel Chinese patent application number CN201310429159.0 discloses a chain fully automatic galvanizing equipment, including a bearing seat, a frame, a motor, and a transmission shaft. The frame is a rectangular parallelepiped, and there is a zinc pool on the ground directly below the frame. A reducer is installed on each of the left and right sides of the front frame above the frame, and the output end of the motor is connected to the outer side of one of the reducers. The reducers are connected through a transmission shaft. A bearing seat is installed on each of the left and right sides of the rear frame above the frame corresponding to the installation position of the reducer. There are bearings in the bearing seats. The bearing seats are connected to the corresponding reducers through the cooperation of bearings and rotating shafts. Die wheels are installed on the rotating shafts. A guide wheel is also installed on the outer side of the frame close to the motor side corresponding to the position of the mold wheel. A controller is also installed on the leg of the frame. Chinese patent application number CN201720756592.9 discloses a novel chain galvanizing device, including an aqueduct, a plating solution is provided in the aqueduct, a galvanizing mechanism is provided above the aqueduct, and the galvanizing mechanism is made of conductive material, wherein the galvanizing mechanism includes a first chain support rod, a second chain support rod, a cross-connecting rod and a roller, the first chain support rod and the second chain support rod are respectively fixed on the roller symmetrically through the cross-connecting rod, and the two ends of the roller are respectively fixed on the aqueduct through rolling bearings, and a driving device is also provided on one side of the aqueduct, and the driving device is connected to the roller through a transmission mechanism, and a chain is provided on the first chain support rod and the second chain support rod, and the chain is drooped into the plating solution. The chain surface is continuously rotated to contact the plating solution, which effectively avoids the occurrence of uneven rolling, contact leakage plating and the like, and improves the quality of reduction galvanizing.

[0006] From the above technology, the coating and heat treatment processes of the chain are currently carried out separately, without sufficient integration, which is not conducive to energy saving, environmental protection and production efficiency. Therefore, it is necessary to develop a compact heat treatment and coating process and equipment suitable for mining chain steel to improve the physical quality and production efficiency of the chain. Summary of the invention

[0007] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a compact mining chain heat treatment and coating process and equipment, which combines the quenching and tempering process of the traditional chain with the hot-dip galvanizing process, eliminates the tempering process of the chain, and makes full use of the chain during the preheating and hot-dip galvanizing process to realize the precipitation of carbides in the steel, forms a galvanized layer on the surface of the chain, and completes the regulation of the organizational properties of the chain steel, thereby realizing the high-efficiency production of mining chains and significantly improving the physical quality and production efficiency of the chain.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] The first aspect of the present invention provides a compact mining chain heat treatment and coating equipment, comprising a chain inlet section, a heat treatment unit, a pickling and plating assistance unit, a hot dip galvanizing unit, a cooling section, a passivation treatment section and a chain outlet section arranged in sequence;

[0010] The heat treatment unit is used to heat and quench the compact mining chain from the chain inlet section; the heat treatment unit includes a heating furnace and a quenching water cooling tank, and the heating furnace is arranged between the chain inlet section and the quenching water cooling tank;

[0011] The pickling and plating-assisting unit is used to carry out pickling and plating-assisting treatment on the compact mining chain treated by the heat treatment unit; the pickling and plating-assisting unit comprises a pickling tank and a plating-assisting tank arranged in sequence;

[0012] The hot-dip galvanizing unit is used to perform hot-dip galvanizing on the compact mining chain after being treated by the pickling unit; the hot-dip galvanizing unit comprises a high-temperature preheating section and a hot-dip galvanizing section which are arranged in sequence, and the high-temperature preheating section is arranged behind the plating-assisting tank.

[0013] Preferably, a plurality of speed-adjustable rotating teeth are provided in the heating furnace.

[0014] Preferably, the adjustable speed rotating teeth are respectively arranged at the inlet, outlet and inside the furnace of the heating furnace.

[0015] Preferably, a preheating furnace for preheating the compact mining chain is provided in the high temperature preheating section; and / or

[0016] The hot-dip galvanizing section is provided with a zinc pot and an air knife in sequence; the zinc pot is used to hold zinc liquid for hot-dip galvanizing the compact mining chain, and a heating device is provided on the zinc pot; the air knife is used to remove unsolidified zinc liquid on the surface of the compact mining chain coming out of the zinc pot; and / or

[0017] The cooling section is provided with an air jet device or a water cooling device.

[0018] Preferably, the preheating furnace is provided with a pipeline for introducing protective gas.

[0019] The second aspect of the present invention provides a compact mining chain heat treatment and coating process, using the compact mining chain heat treatment and coating equipment as described in the first aspect of the present invention, comprising the following steps:

[0020] S1, heat treatment, the compact mining chain arranged at the chain entrance section enters the heating furnace for heating treatment, and then quenching treatment;

[0021] S2, pickling and plating, the compact mining chain treated in step S1 is pickled and plated;

[0022] S3, hot-dip galvanizing, preheating the compact mining chain after the treatment in step S2 in a high-temperature preheating section, and then the compact mining chain enters a zinc pot for hot-dip galvanizing;

[0023] S4, cooling and passivation, after cooling the compact mining chain treated in step S3, passivating the galvanized layer of the compact mining chain with a passivation solution.

[0024] Preferably, the chain steel used for the compact mining chain includes the following components in mass percentage: C: 0.2-0.26%, Si: 0.05-0.25%, Mn: 1.0-1.4%, Cr: 0.4-0.8%, Ni: 0.8-1.2%, Mo: 0.4-0.8%, Al: 0.02-0.05%, N: 0.004-0.012%, and the balance is Fe and unavoidable impurities.

[0025] Preferably, in the chain steel used for the compact mining chain, among the unavoidable impurities, P≤0.015%, S≤0.01%, O≤0.0015%, H≤0.0002%, and Cu≤0.2%, calculated in mass percentage.

[0026] Preferably, in step S1:

[0027] During the heating treatment, the compact mining chain is heated to 830-1000° C. and kept warm for 1-3 hours; and / or

[0028] The temperature of the cooling water used in the quenching process is 20-25°C.

[0029] Preferably, in step S2:

[0030] During the pickling process, a pickling liquid is used to remove the oxide scale on the surface of the compact mining chain, and a corrosion inhibitor is used to prevent the compact mining chain from absorbing hydrogen during the pickling process; and / or

[0031] The auxiliary plating solution used in the auxiliary plating treatment process is zinc chloride and / or ammonium chloride.

[0032] Preferably, in step S2:

[0033] The pickling solution is H with a mass concentration of 15 to 25 wt%. 2 SO 4 or HCl solution; and / or

[0034] The corrosion inhibitor thiourea or hexamethylenetetramine is added in an amount of 0.1 to 0.3% of the mass of the pickling solution; and / or

[0035] The mass concentration of the plating solution is 25-40wt%.

[0036] Preferably, in step S3:

[0037] During the preheating treatment, the preheating temperature is 380-450° C. and the preheating time is ≥0.5 h; and / or

[0038] During the preheating process, an inert protective gas is passed into the preheating furnace, and the oxygen content in the preheating furnace is controlled to be less than 2wt%; and / or

[0039] During the hot-dip galvanizing process, the heating temperature of the zinc liquid in the zinc pot is 420-530° C.; and / or

[0040] After the hot-dip galvanizing treatment, an air knife is used to blow away the unsolidified zinc liquid on the surface of the compact mining chain; and / or

[0041] After the hot-dip galvanizing treatment, the thickness of the galvanized layer of the compact mining chain is 30 to 200 μm.

[0042] Preferably, in step S4:

[0043] During the cooling process, cooling is performed by jet cooling or water cooling; and / or

[0044] During the passivation treatment, a passivation liquid is applied to the surface of the galvanized layer of the compact mining chain, and then the surface of the compact mining chain is dried or blown dry.

[0045] Preferably, in step S4:

[0046] The passivation solution is a hexavalent chromic acid solution; and / or

[0047] The passivation time of the galvanized layer of the compact mining chain is ≥1 min.

[0048] The compact mining chain heat treatment and coating process and equipment provided by the present invention has the following beneficial effects:

[0049] 1. The compact mining chain heat treatment and coating process and equipment of the present invention combines the quenching and tempering process of the traditional chain with the hot-dip galvanizing process, thereby eliminating the chain tempering process, making full use of the chain to achieve the precipitation of carbides in the steel during the preheating and hot-dip galvanizing process, and forming a galvanized layer on the surface of the chain while completing the microstructure and performance regulation of the chain steel, thereby achieving high-efficiency production of mining chains and significantly improving the physical quality and production efficiency of the chain;

[0050] 2. The compact mining chain heat treatment and coating equipment of the present invention has a compact structure, reasonable process design, a wide process window, is easy to manufacture, and can realize mass commercial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0052] Figure 1 It is a schematic structural diagram of the compact mining chain heat treatment and coating equipment of the present invention. DETAILED DESCRIPTION

[0053] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with embodiments.

[0054] Combination Figure 1 As shown, a compact mining chain heat treatment and coating equipment provided by the present invention comprises a chain inlet section 1, a heat treatment unit A, a pickling and plating unit B, a hot-dip galvanizing unit C, a cooling section 9, a passivation treatment section 10 and a chain outlet section 11 arranged in sequence. The heat treatment unit A is used to heat and quench the compact mining chain from the chain inlet section 1; the heat treatment unit A comprises a heating furnace 2 and a quenching water cooling tank 3, and the heating furnace 2 is arranged between the chain inlet section 1 and the quenching water cooling tank 3. The pickling and plating unit B is used to pickle and plating the compact mining chain treated by the heat treatment unit A; the pickling and plating unit B comprises a pickling tank 4 and a plating tank 5 arranged in sequence; the hot-dip galvanizing unit C is used to hot-dip galvanize the compact mining chain treated by the pickling unit; the hot-dip galvanizing unit C comprises a high-temperature preheating section 6 and a hot-dip galvanizing section 7 arranged in sequence, and the high-temperature preheating section 6 is arranged behind the plating tank 5.

[0055] Combination Figure 1 As shown, the compact mining chain enters the heating furnace 2 after the chain entrance section 1 is arranged. The heating furnace 2 heats the compact mining chain. In order to solve the speed matching problem of the compact mining chain heat treatment and coating equipment, a plurality of adjustable speed rotating teeth are arranged in the heating furnace 2, wherein the adjustable speed rotating teeth are respectively arranged at the inlet, outlet and furnace interior of the heating furnace 2. Through the speed difference of the adjustable speed rotating teeth at the inlet, outlet and furnace interior and the deadweight of the compact mining chain, a loop is formed in the heating furnace 2 to ensure that the heating time of the compact mining chain in the heating furnace 2 meets the process requirements.

[0056] Combination Figure 1 As shown, the quenching water cooling tank 3 is arranged behind the heating furnace 2, and the compact mining chain can be quenched; because the oxide scale on the surface of the compact mining chain is loosened after the quenching treatment, it is more convenient to remove it cleanly, so the pickling tank 4 is arranged to pickle the compact mining chain after the quenching treatment to remove the oxide scale on the surface of the compact mining chain; the plating liquid in the plating assistant tank 5 can keep the surface of the compact mining chain after the pickling treatment to a certain activity, avoid oxidation of the compact mining chain in the subsequent preheating process, and enhance the bonding strength between the galvanized layer and the substrate.

[0057] Combination Figure 1 As shown, a preheating furnace for preheating the compact mining chain is provided in the high-temperature preheating section 6; the preheating furnace can prevent the low-temperature compact mining chain from affecting the temperature of the zinc liquid after entering the zinc pot, resulting in large fluctuations in the temperature of the zinc liquid; on the other hand, the chain steel used for the compact mining chain can disperse and precipitate fine carbides in the supersaturated martensite structure formed after quenching, thereby improving the performance of the chain; in a specific embodiment, in order to prevent the compact mining chain from oxidizing after heating, a pipeline for introducing protective gas is provided on the preheating furnace.

[0058] Combination Figure 1 As shown, the hot-dip galvanizing section 7 is provided with a zinc pot and an air knife 8 in sequence; the zinc pot is used to hold zinc liquid for hot-dip galvanizing the compact mining chain, and a heating device is provided on the zinc pot to maintain the temperature of the zinc liquid; the air knife 8 is used to remove the unsolidified zinc liquid on the surface of the compact mining chain coming out of the zinc pot.

[0059] Combination Figure 1 As shown, the cooling section 9 is provided with an air jet device or a water cooling device for cooling the compact mining chain after hot-dip galvanizing.

[0060] The present invention also provides a compact mining chain heat treatment and coating process, the core part of which lies in the heating treatment, quenching treatment, pickling, plating assistance, preheating, hot-dip galvanizing, cooling, passivation, etc. of the chain; wherein the chain steel used for the compact mining chain includes the following components in mass percentage: C: 0.2-0.26%, Si: 0.05-0.25%, Mn: 1.0-1.4%, Cr: 0.4-0.8%, Ni: 0.8-1.2%, Mo: 0.4-0.8%, Al: 0.02-0.05%, N: 0.004-0.012%, and the balance is Fe and unavoidable impurities.

[0061] In the chain steel used for the compact mining chain of the present invention, the design principles of each chemical element are as follows:

[0062] C: C is an element necessary to ensure the strength of steel. Increasing the C content in steel will increase the non-equilibrium structural transformation ability of steel, thereby significantly improving the strength of steel. The C content in steel should not be too high. Excessive C content will have an adverse effect on the plasticity and toughness of steel, and will significantly increase the carbon equivalent of the material and deteriorate the welding performance of steel. Therefore, the mass percentage of C element is controlled between 0.2 and 0.26%.

[0063] Si: Si can be dissolved in steel to improve the strength and hardness of steel, reduce the diffusion capacity of C in ferrite, and thus inhibit the precipitation of cementite. In addition, adding an appropriate amount of Si element to steel can also improve the stability of austenite during cooling and avoid the formation of coarse carbides. However, it should be noted that the Si content in steel should not be too high. When the Si content in steel is too high, it will increase the brittleness of the steel. Therefore, the mass percentage of Si element is controlled between 0.05 and 0.25%.

[0064] Mn: Mn can not only improve the stability of austenite in steel, but also improve the hardenability of steel. In addition, in the present invention, Mn can also improve the strength of martensite in steel through solid solution strengthening, thereby improving the strength of steel. However, it should be noted that the Mn element content in steel should not be too high. When the Mn element content in steel is too high, it will make the quenching and heating austenite grains grow easily, and can promote the segregation of harmful elements at the grain boundaries. Therefore, the mass percentage of the Mn element is controlled between 1.0 and 1.4%.

[0065] Cr: Cr element can improve the hardenability of steel, form hardened martensitic structure, and help improve the strength of steel. In addition, Cr carbide can slow down the grain growth in the heat-affected zone of the welded joint, which is very beneficial to the welding structure of the ore chain. Adding an appropriate amount of Cr and Ni to the steel is beneficial to improving the corrosion resistance of the steel. However, it should be noted that the Cr content in the steel should not be too high. When the Cr content in the steel is too high, the formation of carbides during the heat treatment process will consume a large amount of C element in the steel, which is not conducive to the formation of residual austenite, and a large number of carbides will gather at the grain boundaries to reduce the toughness of the material and significantly increase the carbon equivalent, thereby reducing the flash welding performance of the chain steel. Therefore, the mass percentage of the Cr element is controlled between 0.4 and 0.8%.

[0066] Ni: Ni can exist in steel in the form of solid solution. When Ni is used in combination with Cr, it can significantly improve the hardenability of steel. Adding an appropriate amount of Ni to steel can reduce the C content at the eutectoid point, increase the volume fraction of pearlite, and help improve the strength of steel. In addition, Ni has little effect on welding performance, but Ni is a precious alloy element. Therefore, in order to ensure lower production costs, the mass percentage of Ni is controlled between 0.8 and 1.2%.

[0067] Mo: Mo mainly exists in the steel in the form of solid solution, which can play a solid solution strengthening effect, which is beneficial to improve the hardenability of steel and form martensite in the quenching process. However, it is not advisable to add excessive Mo to steel. When too much Mo is added to steel, the carbon equivalent of the material will be significantly increased, which is not conducive to the flash welding performance of chain steel. Moreover, Mo is a precious alloy element, and adding too much Mo will lead to an increase in production costs. Therefore, the mass percentage of Mo is controlled between 0.4 and 0.8%.

[0068] Al: Al can mainly play the role of deoxidation and nitrogen fixation. Al can combine with N to form AlN, which can effectively refine the grains. However, it should be noted that the Al content in steel should not be too high. When the Al content in steel is too high, it will not only affect the casting performance of the steel, but also damage the toughness of the steel. Therefore, the mass percentage of Al is controlled between 0.02 and 0.05%.

[0069] N: In the mining chain steel described in the present invention, N is an austenite-forming element and also an MX-type precipitate-forming element. The N element can form Nb(C, N) particles with the Nb element in the steel, thereby effectively refining the structure, preventing the mining chain steel from coarsening during welding, and improving the welding quality. It should be noted that the N element should not be added too much. Too high a content of the N element will cause the MX-type precipitates to precipitate and grow prematurely, reduce the effect of organizational refinement, and reduce the impact toughness and fatigue properties of the mining chain steel. Therefore, the mass percentage of the N element is controlled between 0.004 and 0.012%.

[0070] In a further embodiment, among the inevitable impurities, P≤0.015%, S≤0.01%, O≤0.0015%, H≤0.0002%, and Cu≤0.2%, are calculated by mass percentage. Among them, P element, S element, O element and H element are all impurity elements in steel. Under the condition that technical conditions permit, in order to obtain mining chain steel with better performance and better quality, the content of impurity elements in the material should be reduced as much as possible. Adding an appropriate amount of Cu element to steel can significantly improve the corrosion resistance of steel and reduce the hydrogen-induced crack sensitivity of steel. However, too high Cu content is not conducive to the welding performance of steel, and it is also easy to produce copper brittleness and deteriorate the surface properties of steel. Therefore, the Cu element content does not exceed 0.2%.

[0071] The compact mining chain heat treatment and coating process of the present invention adopts the above-mentioned compact mining chain heat treatment and coating equipment, and specifically includes the following steps:

[0072] S1, heat treatment, the compact mining chain arranged at the chain entrance section enters the heating furnace for heating treatment, and then quenching treatment;

[0073] Specifically, the compact mining chain enters the heating furnace after the chain entrance section is arranged. The heating furnace can heat the compact mining chain, heat the compact mining chain to the target temperature and keep it warm for a period of time. Specifically, the compact mining chain is heated to 830-1000°C and kept warm for 1-3 hours. In order to solve the speed matching problem of compact mining chain heat treatment and coating equipment, a plurality of adjustable speed rotating teeth are set in the heating furnace, wherein the adjustable speed rotating teeth are respectively arranged at the inlet, outlet and furnace of the heating furnace. The speed difference of the adjustable speed rotating teeth at the inlet, outlet and furnace and the weight of the compact mining chain form a loop in the heating furnace to ensure that the heating time of the compact mining chain in the heating furnace meets the process requirements. Afterwards, the compact mining chain after heating treatment is quenched (water quenched) in the quenching water cooling tank and then cooled to room temperature; the temperature of the cooling water used in the quenching process is 20-25°C.

[0074] S2, pickling and plating, the compact mining chain treated in step S1 is pickled and plated;

[0075] Specifically, the quenched compact mining chain is pickled in a pickling tank, the oxide scale on the surface of the compact mining chain is removed by pickling liquid, and a corrosion inhibitor is used to prevent the compact mining chain from absorbing hydrogen during the pickling process; since the oxide scale on the surface of the compact mining chain is loose after the quenching treatment, it is easier to remove it; the pickling liquid uses a mass concentration of 15 to 25wt% H 2 SO 4 or HCl solution; the corrosion inhibitor is thiourea or hexamethylenetetramine, and the addition amount is 0.1-0.3% of the mass of the pickling solution. Then, the pickled compact mining chain is subjected to a plating treatment in a plating tank. The plating solution used for the plating treatment can keep the surface of the pickled compact mining chain active to a certain extent. The plating solution can be zinc chloride and / or ammonium chloride to avoid oxidation during the subsequent preheating process and enhance the bonding force between the zinc layer and the substrate; in a specific embodiment, the mass concentration of the plating solution is 25-40wt%.

[0076] S3, hot-dip galvanizing, preheating the compact mining chain after the treatment in step S2 in a high-temperature preheating section, and then the compact mining chain enters a zinc pot for hot-dip galvanizing;

[0077] Specifically, the compact mining chain treated in step S2 is preheated in the high-temperature preheating section. On the one hand, it can prevent the low-temperature compact mining chain from affecting the temperature of the zinc liquid after entering the zinc pot, resulting in large fluctuations in the temperature of the zinc liquid. On the other hand, it can disperse and precipitate fine carbides in the supersaturated martensite structure formed by the chain steel after quenching, thereby improving the performance of the chain. During the preheating treatment, the preheating temperature is 380-450°C, and the preheating time is ≥0.5h. In a specific embodiment, in order to prevent the compact mining chain from high-temperature oxidation, an inert protective gas is passed into the preheating furnace, and the oxygen content in the preheating furnace is controlled to be lower than 2wt%. After the preheating treatment, the compact mining chain is hot-dip galvanized in the zinc pot of the hot-dip galvanizing section. The zinc liquid solidifies on the surface of the chain compact mining chain to form a galvanized layer with a certain thickness. After the chain compact mining chain is pulled out of the zinc pot, an air knife is used to blow away the unsolidified zinc liquid on the surface of the compact mining chain; in the hot-dip galvanizing process, the zinc liquid can be made of zinc-aluminum alloy and zinc-aluminum-magnesium alloy; the heating temperature of the zinc liquid in the zinc pot is 420-530°C. After the hot-dip galvanizing treatment, the thickness of the galvanized layer on the surface of the compact mining chain is 30-200μm.

[0078] S4, cooling and passivation, after cooling the compact mining chain treated in step S3, passivating the galvanized layer of the compact mining chain with a passivation solution.

[0079] Specifically, the compact mining chain treated in step S3 is cooled and then cooled to the target temperature by jet cooling or water cooling; then the passivation treatment section is entered to passivate the galvanized layer of the compact mining chain, and the passivation liquid is applied to the surface of the galvanized layer of the compact mining chain, and then the surface of the compact mining chain is dried or blown dry; wherein the passivation liquid is a hexavalent chromic acid solution with a mass concentration of 8 to 12wt%; the passivation time of the galvanized layer of the compact mining chain is ≥1min. The compact mining chain after passivation is output from the chain outlet section, and the galvanizing treatment of the chain is completed.

[0080] The compact heat treatment and coating process for mining chains of the present invention combines the quenching and tempering process of traditional chains with the hot-dip galvanizing process, thereby eliminating the tempering process of the chain and making full use of the chain to realize the precipitation of carbides in the steel during the preheating and hot-dip galvanizing process, forming a galvanized layer on the surface of the chain while completing the control of the organizational properties of the chain steel, thereby realizing the high-efficiency production of mining chains.

[0081] After the above compact mining chain heat treatment and coating process, the performance of the compact mining chain meets the following requirements: yield strength Rp 0.2 ≥1150MPa, tensile strength R m ≥1280MPa, elongation A≥12%, section shrinkage Z≥50%, room temperature impact energy AKV≥80J; after 120h of 5% NaCl neutral salt spray corrosion test, its relative corrosion rate is lower than 1 / 4 of the general mining chain, and it has excellent corrosion resistance.

[0082] The compact mining chain heat treatment and coating process and equipment of the present invention are further introduced below with reference to specific examples.

[0083] Example

[0084] The compact mining chain heat treatment and coating process of Examples 1 to 6 is processed by the above-mentioned compact mining chain heat treatment and coating equipment, and the specific steps are as follows:

[0085] After the compact mining chain is made of chain steel with the chemical composition shown in Table 1, compact mining chains with different alloy type coatings are produced through compact mining chain heat treatment and coating processes.

[0086] The compact mining chain enters the production line from the chain entrance section, and the chain is heated to 830-1000°C in the heating furnace. By adjusting the length of the chain loop in the heating furnace, the compact mining chain is ensured to be heated for 1-3 hours. After the compact mining chain leaves the heating furnace, it enters the quenching water cooling tank for quenching treatment. The temperature of the cooling water used for quenching treatment is 20-50°C. After the compact mining chain is rapidly cooled after quenching treatment, the structure changes from austenite to martensite. After that, the compact mining chain is pickled in the pickling tank, and the pickling liquid uses 15-25wt% H 2 SO 4 Or HCl solution, and add a certain amount of corrosion inhibitor thiourea or hexamethylenetetramine, the addition amount is 0.1-0.3% of the pickling solution mass, to prevent the compact mining chain from absorbing hydrogen during the pickling process. After pickling to remove the oxide scale on the surface, the compact mining chain enters the plating tank. The plating solution is zinc chloride and / or ammonium chloride, with a mass concentration of 25-40wt%, which increases the bonding strength between the zinc layer and the substrate during hot-dip galvanizing. After that, the compact mining chain enters the high-temperature preheating section for preheating. The preheating temperature of the compact mining chain is 380-450℃, and the preheating time is ≥0.5h. The preheating furnace is filled with inert protective gas to prevent the compact mining chain from oxidizing, and the oxygen content in the preheating furnace is controlled to be less than 2wt%. Then the compact mining chain enters the zinc pot of the hot-dip galvanizing section for hot-dip galvanizing treatment. The zinc liquid alloy type in the zinc pot is zinc-aluminum alloy and zinc-aluminum-magnesium alloy. The zinc liquid temperature is 420-530°C. The zinc layer thickness of the compact mining chain coming out of the zinc pot is 30-200 μm. Then, the unsolidified zinc liquid adhering to the surface of the compact mining chain is blown away by the air knife 8, and the compact mining chain enters the cooling section. After the compact mining chain is cooled to 50°C by water cooling, it enters the passivation treatment section for passivation treatment of the surface zinc coating. The passivation solution adopts hexavalent chromic acid solution with a mass concentration of 8-12wt%. The passivation time of the zinc coating on the surface of the compact mining chain is ≥1min. After the compact mining chain is dried, it is output through the chain outlet section to complete the chain heat treatment and coating production. Table 2 shows the specific parameters of the heat treatment and coating process of the compact mining chain of Examples 1-6.

[0087] Comparative Example

[0088] Comparative Examples 1 and 2 are made of mining chains made of chain steel with the chemical composition shown in Table 1, and then the compact mining chains in Comparative Examples 1 and 2 are treated as follows: the chain is heated to 880°C and kept warm for 1 hour, then water-quenched, and then heated to 430°C and kept warm for 1 hour for tempering to obtain a finished mining chain.

[0089] Table 1 Composition of chain steel used in Examples and Comparative Examples (wt%)

[0090] C Si Mn P S Cr Ni Mo Cu Al N O H Example 1 0.21 0.14 1.39 0.007 0.007 0.62 1.02 0.65 0.04 0.028 0.0077 0.0011 0.00015 Example 2 0.26 0.07 1.02 0.012 0.008 0.78 0.93 0.71 0.12 0.022 0.0067 0.001 0.0001 Example 3 0.20 0.23 1.22 0.006 0.005 0.71 0.84 0.79 0.15 0.048 0.0048 0.0007 0.00014 Example 4 0.24 0.11 1.15 0.010 0.009 0.57 1.09 0.47 0.11 0.037 0.0055 0.0005 0.00018 Example 5 0.22 0.25 1.34 0.009 0.002 0.43 1.18 0.55 0.18 0.042 0.0115 0.0015 0.00012 Example 6 0.23 0.18 1.28 0.012 0.002 0.52 1.10 0.43 0.08 0.035 0.0096 0.0012 0.00011 Comparative Example 1 0.25 0.15 1.30 0.008 0.006 0.55 0.98 0.56 0.11 0.027 0.0086 0.0017 0.0002 Comparative Example 2 0.22 0.32 0.48 0.013 0.006 0.81 3.02 0.55 0.02 0.03 0.01 0.0015 0.0002

[0091] Table 2 Specific process parameters in the embodiments and comparative examples

[0092]

[0093] The compact mining chains obtained in Examples 1-6 were sampled respectively, and the comparative steel materials obtained in Comparative Examples 1-2 were sampled respectively to obtain corresponding samples; and the performance of the samples of Examples 1-6 and Comparative Examples 1-2 was tested to obtain the performance of the steel plates of each Example and Comparative Example. Then, the samples of Examples 1-6 and Comparative Examples 1-2 were subjected to tensile tests, impact performance tests, and corrosion resistance tests, and the test results of the samples of each Example and Comparative Example are listed in Table 3.

[0094] The specific testing methods for relevant tensile test, Charpy impact test and corrosion resistance test are as follows:

[0095] Tensile test: The steels of the examples and comparative examples were sampled from hot-rolled round steels according to the national standard GB / T 2975, and tensile specimens were prepared, and tensile properties were tested according to the national standard GB / T 228.1.

[0096] Charpy impact test: The steels of the examples and comparative examples were sampled from hot-rolled round steels according to the national standard GB / T 2975, and impact specimens were prepared, and impact performance tests were performed according to the national standard GB / T 229.

[0097] Corrosion resistance test: Take a 100mm long salt spray corrosion specimen from the chain steel, seal both ends, and conduct a 5wt% NaCl salt spray corrosion test according to GB / T10125 standard. After the 120h neutral salt spray test, take out the test specimen, completely remove the surface corrosion products with the solution recommended in GB / T 16545, blow dry the specimen, weigh the mass and record it as M', and then calculate the value according to the formula (Where M is the initial mass of the sample, in g; M' is the mass of the sample after the corrosion products are removed and blown dry, in g; S is the corrosion test area of ​​the sample, in cm 2 ; T is the corrosion time, the dimension is h; D is the sample density) to calculate the corrosion rate R of each sample, the dimension of the corrosion rate R is mm / a. Taking the corrosion rate of comparative example 1 as the benchmark, the corrosion rate of each sample is divided by the corrosion rate of comparative example 1 to obtain the relative corrosion rate of each sample.

[0098] Table 3 Test results of samples in the embodiments and comparative examples

[0099]

[0100] It can be seen from Table 3 that the compact mining chains of Examples 1 to 6 of the present invention have excellent comprehensive performance, wherein the yield strength R of the chain steel of Examples 1 to 6 isp0.2 The tensile strength Rm is between 1160 and 1205 MPa, the elongation A is ≥13.5%, the cross-sectional shrinkage Z is ≥50%, and the room temperature impact energy AKV is ≥80 J. Combined with Table 3, it can be seen that the comprehensive mechanical properties of the compact mining chains of Examples 1 to 6 are better than the existing comparative steels selected in Comparative Examples 1-2. In addition, after the compact mining chains of Examples 1 to 6 are coated and plated, they have excellent corrosion resistance, and their corrosion rate is lower than 1 / 4 of that of general mining chains. They have very good corrosion resistance and are very suitable for mines, oceans and other places with high requirements for chain corrosion performance.

[0101] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A compact mining chain heat treatment and coating equipment, characterized in that: It includes a chain inlet section, a heat treatment unit, a pickling and plating assisting unit, a hot-dip galvanizing unit, a cooling section, a passivation treatment section and a chain outlet section which are arranged in sequence; The heat treatment unit is used to heat and quench the compact mining chain from the chain inlet section; the heat treatment unit includes a heating furnace and a quenching water cooling tank, and the heating furnace is arranged between the chain inlet section and the quenching water cooling tank; The pickling and plating-assisting unit is used to carry out pickling and plating-assisting treatments on the compact mining chain treated by the heat treatment unit; the pickling and plating-assisting unit comprises a pickling tank and a plating-assisting tank arranged in sequence; The hot-dip galvanizing unit is used to perform hot-dip galvanizing on the compact mining chain after being treated by the pickling unit; the hot-dip galvanizing unit comprises a high-temperature preheating section and a hot-dip galvanizing section which are arranged in sequence, and the high-temperature preheating section is arranged behind the plating-assisting tank.

2. The compact mining chain heat treatment and coating equipment according to claim 1 is characterized in that: A plurality of speed-adjustable rotating teeth are arranged in the heating furnace.

3. The compact mining chain heat treatment and coating equipment according to claim 2 is characterized in that: The adjustable speed rotating teeth are respectively arranged at the inlet, outlet and inside of the furnace of the heating furnace.

4. The compact mining chain heat treatment and coating equipment according to claim 1 is characterized in that: The high temperature preheating section is provided with a preheating furnace for preheating the compact mining chain; and / or The hot-dip galvanizing section is provided with a zinc pot and an air knife in sequence; the zinc pot is used to hold zinc liquid for hot-dip galvanizing the compact mining chain, and a heating device is provided on the zinc pot; the air knife is used to remove unsolidified zinc liquid on the surface of the compact mining chain coming out of the zinc pot; and / or The cooling section is provided with an air jet device or a water cooling device.

5. The compact mining chain heat treatment and coating equipment according to claim 4 is characterized in that: The preheating furnace is provided with a pipeline for introducing protective gas.

6. A compact mining chain heat treatment and coating process, characterized in that: The following steps are performed using the compact mining chain heat treatment and coating equipment as described in any one of claims 1 to 5: S1, heat treatment, the compact mining chain arranged at the chain entrance section enters the heating furnace for heating treatment, and then quenching treatment; S2, pickling and plating, the compact mining chain treated in step S1 is pickled and plated; S3, hot-dip galvanizing, preheating the compact mining chain after the treatment in step S2 in a high-temperature preheating section, and then the compact mining chain enters a zinc pot for hot-dip galvanizing; S4, cooling and passivation, after cooling the compact mining chain treated in step S3, passivating the galvanized layer of the compact mining chain with a passivation solution.

7. The compact mining chain heat treatment and coating process according to claim 6 is characterized in that: The chain steel used for the compact mining chain includes the following components in mass percentage: C: 0.2-0.26%, Si: 0.05-0.25%, Mn: 1.0-1.4%, Cr: 0.4-0.8%, Ni: 0.8-1.2%, Mo: 0.4-0.8%, Al: 0.02-0.05%, N: 0.004-0.012%, and the balance is Fe and unavoidable impurities.

8. The compact mining chain heat treatment and coating process according to claim 7 is characterized in that: In the chain steel used for the compact mining chain, among the unavoidable impurities, P≤0.015%, S≤0.01%, O≤0.0015%, H≤0.0002%, and Cu≤0.2%, calculated by mass percentage.

9. The compact mining chain heat treatment and coating process according to claim 6, characterized in that: In step S1: During the heating treatment, the compact mining chain is heated to 830-1000° C. and kept warm for 1-3 hours; and / or The temperature of the cooling water used in the quenching process is 20-25°C, and / or In step S2: During the pickling process, a pickling liquid is used to remove the oxide scale on the surface of the compact mining chain, and a corrosion inhibitor is used to prevent the compact mining chain from absorbing hydrogen during the pickling process; and / or The auxiliary plating solution used in the auxiliary plating treatment process is zinc chloride and / or ammonium chloride, and / or In step S3: During the preheating treatment, the preheating temperature is 380-450° C. and the preheating time is ≥0.5 h; and / or During the preheating process, an inert protective gas is passed into the preheating furnace, and the oxygen content in the preheating furnace is controlled to be less than 2wt%; and / or During the hot-dip galvanizing process, the heating temperature of the zinc liquid in the zinc pot is 420-530° C.; and / or After the hot-dip galvanizing treatment, an air knife is used to blow away the unsolidified zinc liquid on the surface of the compact mining chain; and / or After the hot-dip galvanizing treatment, the thickness of the galvanized layer of the compact mining chain is 30 to 200 μm, and / or In step S4: During the cooling process, cooling is performed by jet cooling or water cooling; and / or During the passivation treatment, a passivation liquid is applied to the surface of the galvanized layer of the compact mining chain, and then the surface of the compact mining chain is dried or blown dry.

10. The compact mining chain heat treatment and coating process according to claim 9, characterized in that: In step S2: The pickling solution is H2SO4 or HCl solution with a mass concentration of 15-25wt%; and / or The corrosion inhibitor is thiourea or hexamethylenetetramine, and the addition amount is 0.1-0.3% of the mass of the pickling solution; and / or The mass concentration of the plating solution is 25-40wt%.

11. The compact mining chain heat treatment and coating process according to claim 9, characterized in that: In step S4: The passivation solution is a hexavalent chromic acid solution; and / or The passivation time of the galvanized layer of the compact mining chain is ≥1 min.

Images