Bimetal wear-resistant upper wing plate and preparation method thereof

Abstract

The bimetallic wear-resistant upper wing plate comprises a wing plate front end and a wing plate rear end, the upper wing plate front end is made of high-chromium cast iron with the Cr content of 25-27 wt.%, and the upper wing plate rear end is made of low-alloy steel which is good in toughness and easy to weld. The bimetal upper wing plate is manufactured through liquid composite casting, normalizing, quenching and tempering, a groove is formed in the rear end of the bimetal upper wing plate, and the bimetal upper wing plate can be connected with the middle groove through K-shaped groove welding. In addition, the invention also discloses a method for manufacturing the liquid composite bimetallic upper wing plate. By effectively controlling the pouring temperature, the pouring speed and the interval time of the two kinds of molten steel, good metallurgical bonding of the two kinds of steel is achieved, and the bonding part is high in strength and good in toughness.

Description

Technical Field

[0001] The invention relates to the technical field of mining and conveying of fully mechanized working faces in underground coal mines, and in particular to a bimetallic upper wing plate and a preparation method thereof. Background Art

[0002] As the core equipment for underground coal transportation, the stable and efficient operation of the scraper conveyor is the key to ensuring safe production and economic benefits of the mine. The middle trough is a key component of the scraper conveyor, which is mainly composed of trough sides, middle plates, coal retaining plates and bottom plates. When the scraper conveyor is running in the mine, the upper wing plates of the trough sides will continue to be subjected to severe friction from the scraper and coal gangue, which is prone to wear and tear, resulting in failure of the middle trough. Every year, 500,000 to 600,000 middle troughs fail due to wear worldwide, with direct economic losses of tens of billions. At present, the main production method of the upper wing plate is to cast it as a whole with the trough side, but the wear resistance of the trough side material cannot meet the service life requirements of the upper wing plate. Improving the wear resistance of the upper wing plate of the trough side can effectively increase the service life of the middle trough. How to improve the wear resistance of the upper wing plate of the middle trough economically and effectively is an urgent problem to be solved.

[0003] The utility model patent with publication number CN 210102675 U and publication date 2020.02.21 discloses a conveyor middle trough with replaceable upper wing plates, which consists of an upper wing plate with a fixing pin, a middle trough body with corresponding pin holes on the trough side, connecting bolts and corresponding washers and nuts. When the upper wing plate is worn to a specified scale, the upper wing plate can be directly replaced separately, and the trough body can continue to be used after replacement, avoiding the need to replace the entire middle trough. However, the upper wing plate material selected in the patent is the same as the trough side material, with a low lifespan, and it is connected to the trough side by bolts and fillet welding, and cannot be replaced underground, resulting in frequent replacement and long replacement cycles.

[0004] In the utility model patent with publication number CN 214166279 U and publication date 2021.09.10, a scraper conveyor middle trough with replaceable wear parts is disclosed. In the patent, the middle trough is divided into baffle trough side, shovel plate trough side, middle plate and lining. Among them, the middle plate and lining are an integral structure, which are connected to the baffle trough side and shovel plate trough side by bolts. When the middle trough wears out, the service life of the middle trough can be increased by replacing the lining and the middle plate. However, the middle trough of this structure is very prone to bolt failure during the pushing process, resulting in damage to the scraper conveyor. At the same time, considering the failure of the middle trough, the middle plate wears faster. Replacing the middle plate and the lining at the same time will cause a huge waste of resources, and the replacement process is more complicated and difficult to achieve. Summary of the invention

[0005] The object of the present invention is to provide an upper wing plate with high wear resistance through bimetal casting, thereby increasing the service life of the middle tank.

[0006] To achieve the above-mentioned purpose of the present invention, the technical solution adopted is: a highly wear-resistant bimetallic upper wing plate, including a front end and a rear end, the front end and the rear end are molten and connected, the front end is made of wear-resistant high-chromium cast iron, and the rear end is made of high-toughness, easy-to-weld low-alloy steel, and the rear end of the wing plate is provided with a blunt-edged groove, which can be connected to the groove side by K-type groove welding.

[0007] Furthermore, the front end material high chromium cast iron contains the following elements in percentage by mass: C: 2.8~3.0, Cr: 25~27, Si: 0.6~0.8, Mn: 0.6~0.8, Mo: 0.4~0.6, Ni: 0.8~1.0, Cu: 0.8~1.0, RE: 0.6~0.8, and the remainder is Fe and unavoidable impurities.

[0008] Furthermore, the rear end material low alloy steel contains the following elements in percentage by mass: C: 0.25~0.35, Si: 0.60~0.80, Mn: 1.10~1.40, S: 0~0.03, P: 0~0.03, Re: 0~0.15, Al: 0~0.06, B: 0~0.005, and the remainder is Fe and unavoidable impurities.

[0009] The present invention also provides a method for preparing a bimetallic upper wing plate with high wear resistance, comprising the following steps: 1) Wooden mold making A bimetallic dividing line is set on the wood mold of the upper wing plate, and the positions of the gate and the overflow hole are designed on the dividing line. A feeding riser is set at the front end of the upper wing plate. The feeding riser is a top exposed riser, wherein the gate is set at a position parallel to the bimetallic dividing line, the overflow hole is set at the side of the upper wing plate, that is, on the side parallel to the bimetallic dividing line, and the feeding riser is set at the front end of the wing plate. The surface temperature of the steel layer can be measured from the upper part of the riser with a thermometer; 2) Sand mold making The sand mold of the bimetallic upper wing plate uses water glass hardened sand. When making the sand mold, the strength is considered and the reasonable amount of sand is designed. After the sand mold is completed, the cavity part is painted and fully baked and dried. The gate and riser parts are painted or not. After the sand mold is completely dried, it can be assembled and wait for pouring; 3) Casting process The high chromium cast iron liquid corresponding to the front end of the upper wing plate and the medium and low carbon alloy steel liquid at the rear end are smelted in a medium frequency melting furnace respectively. The temperature of the medium and low carbon alloy steel is 1600℃-1640℃, and the pouring temperature is 1520℃-1560℃. After complete deoxidation and degassing to ensure that there are no inclusions, pouring is carried out; the temperature of the high chromium cast iron is 1460℃-1500℃, and the pouring temperature of the molten iron is 1380℃-1420℃; after the pouring of the molten steel, the overflow hole can be blocked after the molten steel flows out, and the molten iron can be poured after a period of time. The interval time is determined by the thickness of the upper wing plate and the temperature of the molten steel and molten iron. The longest interval time shall not exceed 30 seconds. The high melting point and high density alloy is poured first, and the low melting point and low density metal liquid is poured later, which can effectively avoid the impact and mixing between the two metals; 4) Heat treatment process The bimetallic upper wing plate is heated to 910℃±10℃ in a trolley furnace and kept warm for 4-6 hours, and then air-cooled and normalized after being taken out of the furnace; the upper wing plate after normalization is heated at 910℃±10℃ for 3-5 hours, and then quenched with quenching liquid after being taken out of the furnace; finally, tempered at 580℃; 5) Processing After being fired, the upper wing plate is shot blasted to remove the oxide scale, and a blunt-edged groove is opened at the rear end of the upper wing plate. The upper wing plate can be connected to the groove side through the rear end K-shaped groove welding; Beneficial effects of the present invention: 1) The front end of the upper wing plate is the most severely worn part of the middle groove. The front end of the upper wing plate of the present invention uses high-chromium cast iron, which improves the wear resistance of the upper wing plate, increases the service life of the middle groove, and effectively reduces the production cost of the coal mine.

[0010] 2) The low alloy steel used at the rear end of the upper wing plate has good toughness and welding performance. It is connected to the groove side through K-type groove welding, which can effectively absorb the impact received by the upper wing plate, and the connection is stable and the operation is safe.

[0011] 3) The bimetallic upper wing plate adopts liquid-liquid forming process. Due to the effective control of the pouring temperature, pouring speed and interval time of the molten steel and high-chromium cast iron liquid, and the metallurgical bonding is completed within the specified time, the two kinds of steel achieve good metallurgical bonding, and the deoxidation and degassing operation of the molten steel is reasonable, which avoids bubbles and inclusions in the joint, and improves the strength and toughness of the joint part. The front and rear ends of the upper wing plate will not separate or break. First pouring the high melting point and high density alloy, and then pouring the low melting point and low density metal liquid, can effectively avoid the impact and mixing between the two metals.

[0012] It should be pointed out that these modifications or improvements made without departing from the spirit of the present invention are within the scope of protection required by the patent of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1This is a schematic diagram of the structure of the bimetallic wear-resistant upper wing plate of the present invention. Figure 2 A schematic diagram of the sand mold arrangement of the bimetallic wear-resistant upper wing plate of the present invention Figure 3 The connection position between the bimetallic wear-resistant upper wing plate and the groove side of the present invention In the figure: 1. Front end of upper wing plate; 2. Rear end of upper wing plate; 3. Low alloy steel pouring gate; 4. Riser; 5. High chromium cast iron pouring gate; 6. Overflow hole; 7. Groove side. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Example

[0015] 1. Material selection A highly wear-resistant bimetallic upper wing plate, characterized in that: Figure 1 As shown, it includes a front end 1 and a rear end 2, which are fused together, the front end 1 is made of wear-resistant high-chromium cast iron, the rear end 2 is made of high-toughness, easy-to-weld low-alloy steel, and the rear end 2 of the upper wing plate is provided with a blunt-edged groove, which can be connected to the groove side by K-type groove welding.

[0016] The high chromium cast iron used in the front end 1 of this embodiment contains the following elements in mass ratio: C: 2.9, Cr: 26.1, Si: 0.7, Mn: 0.6, Mo: 0.5, Ni: 0.9, Cu: 0.9, RE: 0.7, and the remainder is Fe and unavoidable impurities.

[0017] The low alloy steel used in the rear end 2 of this embodiment contains the following elements in mass ratio: C: 0.3, Si: 0.7, Mn: 1.22, S: 0.02, P: 0.01, and the remainder is Fe and unavoidable impurities.

[0018] 2 Wooden shape making Set a bimetallic dividing line on the wood type of the upper wing plate, such as Figure 3 As shown, a low alloy steel gate 3, a high chromium cast iron gate 5 and an overflow hole 6 are designed on the dividing line, and a top exposed shrinkage feeder 4 is provided at the rear end of the upper wing plate, wherein the gates 3 and 5 are arranged at a position parallel to the bimetallic dividing line, the overflow hole 6 is arranged on the side of the upper wing plate, i.e., on the side parallel to the bimetallic dividing line, and the shrinkage feeder 4 is arranged on the top of the upper wing plate, i.e., the surface temperature of the steel layer can be measured from the upper part of the riser 4 with a thermometer.

[0019] 3 Sand mold making The sand mold of the bimetallic upper wing plate uses water glass hardened sand. When making the sand mold, the strength should be considered and the reasonable amount of sand should be designed. After the sand mold is completed, the cavity part should be painted and fully baked and dried. The gate and riser parts may be painted or not. After the sand mold is completely dried, it can be assembled and wait for pouring; 4. Pouring The high chromium cast iron liquid and the medium and low carbon alloy steel liquid are smelted in a medium frequency melting furnace respectively. The medium and low carbon alloy steel has a furnace outlet temperature of 1620℃±10℃ and a pouring temperature of 1540℃±10℃. After being completely deoxidized and degassed to ensure that there are no inclusions, pouring is performed; the furnace outlet temperature of the high chromium cast iron is 1480℃±10℃, and the pouring temperature of the molten iron is 1400℃±10℃; after the molten steel is poured, the overflow hole can be blocked after the molten steel has flowed out, and the molten iron can be poured after a period of time. The interval time is determined by the thickness of the upper wing plate and the temperature of the molten steel and molten iron, and the longest interval time shall not exceed 30 seconds; 5 Heat treatment Heat the bimetallic upper wing plate to 910℃±10℃ in a trolley furnace and keep it warm for 4-6 hours, and air-cool it for normalization after it comes out of the furnace; heat the upper wing plate after normalization at 910℃±10℃ for 3-5 hours, and quench it with quenching liquid after it comes out of the furnace; finally, temper it at 580℃±10℃; 6. Welding After being taken out of the furnace, the rear end 2 of the upper wing plate is grooved and connected to the groove side 7 by K-type groove welding.

[0020] The groove side of the welded bimetallic wing plate and the ordinary cast groove side were installed on the same equipment and put into use on a certain working face. When the equipment was in operation for three months and the coal flow rate was 2 million tons, the average wear of the upper wing plate of the cast groove side was 4.9mm, and the wear of the upper wing plate of the middle groove of the welded bimetallic wing plate was 1.7mm.

Claims

1. A bimetallic wear-resistant upper wing plate, characterized in that: It comprises a front end (1) and a rear end (2), wherein the front end (1) and the rear end (2) of the upper wing plate are fused together, the front end (1) is made of high-chromium cast iron, and the rear end (2) is made of cast steel.

2. A bimetallic wear-resistant upper wing plate according to claim 1, characterized in that: The rear end (2) is provided with a blunt-edged groove, which can be connected to the middle groove side by K-shaped groove welding.

3. The bimetallic wear-resistant upper wing plate according to claim 1, characterized in that: The front end (1) contains the following elements in percentage by mass: C: 2.8-3.0, Cr: 25-27, Si: 0.6-0.8, Mn: 0.6-0.8, Mo: 0.4-0.6, Ni: 0.8-1.0, Cu: 0.8-1.0, RE: 0.6-0.8, and the remainder is Fe and unavoidable impurities.

4. A bimetallic wear-resistant upper wing plate according to claim 1, characterized in that: The rear end (2) contains the following elements in percentage by mass: C: 0.25-0.35, Si: 0.60-0.80, Mn: 1.10-1.40, S: 0-0.03, P: 0-0.03, Re: 0-0.15, Al: 0-0.06, B: 0-0.005, and the remainder is Fe and unavoidable impurities.

5. A method for preparing a bimetallic wear-resistant upper wing plate, characterized in that: The following steps are involved: 1) Wooden mold making A bimetallic dividing line is set on the wood mold of the upper wing plate, and gates (3), (5) and overflow holes (6) are designed on the dividing line. A top-exposed shrinkage feeder is set at the front end of the upper wing plate, wherein the gates (3) and (5) are set at positions parallel to the bimetallic dividing line, the overflow hole (6) is set on the side of the upper wing plate, i.e., on the side parallel to the bimetallic dividing line, the shrinkage feeder (4) is set at the front end of the wing plate, and the surface temperature of the steel layer can be measured from the upper part of the feeder (4) by a thermometer; 2) Sand mold making The sand mold of the bimetallic upper wing plate uses water glass hardened sand. When making the sand mold, the strength should be considered and the reasonable amount of sand should be designed. After the sand mold is completed, the cavity part should be painted and fully baked and dried. The gate and riser parts may be painted or not. After the sand mold is completely dried, it can be assembled and wait for pouring; 3) Pouring The high chromium cast iron liquid corresponding to the front end (1) of the upper wing plate and the medium carbon alloy steel liquid corresponding to the rear end (2) are smelted in a medium frequency melting furnace respectively, the temperature of the medium and low carbon alloy steel is 1600°C-1640°C, the pouring temperature is 1520°C-1560°C, and after being completely deoxidized and degassed to ensure that there are no inclusions, pouring is then carried out; the temperature of the high chromium cast iron is 1460°C-1500°C, and the pouring temperature of the molten iron is 1380°C-1420°C; after the pouring of the molten steel is completed, the overflow hole (6) can be blocked after the molten steel has flowed out, and the molten iron can be poured after a period of time, and the interval time is determined by the thickness of the upper wing plate and the temperature of the molten steel and the molten iron, and the maximum interval time shall not exceed 30 seconds; 4) Heat treatment Heat the bimetallic upper wing plate to 910℃±10℃ in a trolley furnace and keep it warm for 4-6 hours, and air-cool it for normalization after it comes out of the furnace; heat the upper wing plate after normalization at 910℃±10℃ for 3-5 hours, and quench it with quenching liquid after it comes out of the furnace; finally, temper it at 580℃; 5) Processing After being taken out of the furnace, the upper wing plate is shot blasted to remove the oxide scale, and a blunt-edged groove is opened at the rear end (2) of the upper wing plate. The upper wing plate can be connected to the groove side (7) by K-type groove welding.

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